Anionic aggregates induced interphase chemistry regulation toward wide-temperature silicon-based batteries

Anionic aggregates induced interphase chemistry regulation toward wide-temperature silicon-based batteries | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Anionic aggregates induced interphase chemistry regulation toward wide-temperature silicon-based batteries Yingying Lu, Shulan Mao, Jiahui Zhang, Jiale Mao, Zeyu Shen, Ziren Long, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3865538/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Silicon nanoparticles (SiNPs) show great promise as high-capacity anodes owing to their ability to mitigate mechanical failure. However, the substantial surface area of SiNPs triggers interfacial side reactions and solid electrolyte interphase (SEI) permeation during volume fluctuations. The slow kinetics at low temperatures and the degradation of SEI at high temperatures further hinder the practical application of SiNPs in real-world environments. Here, we address these challenges by manipulating the solvation structure through molecular space hindrance. This manipulation enables anions to aggregate in the outer Helmholtz layer under an electric field, leading to rapid desolvation capabilities and the formation of anion-derived SEI. The resulting double-layer SEI, where nano-clusters are uniformly dispersed in the amorphous structure, completely encapsulates the particles in the first cycle. The ultra-high modulus of this structure can withstand stress accumulation, preventing electrolyte penetration during repeated expansion and contraction. As a result, SiNPs-based batteries demonstrate exceptional electrochemical performance across a wide temperature range from − 20 to 60°C. The assembled 80 mAh SiNPs/LiFePO 4 pouch cell maintains a cycling retention of 85.6% after 150 cycles. This study elucidates the intricate relationship between interface solvation, SEI chemistry, and bulk stability, offering new insights for the development of wide-temperature Si-based batteries. Physical sciences/Materials science/Materials for energy and catalysis/Batteries Physical sciences/Engineering/Chemical engineering Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction The advancement and widespread adoption of electric vehicles and energy storage grids underscore the need for state-of-the-art lithium-ion batteries (LIBs) with high energy density and long lifespan, capable of withstanding the environmental temperatures in residential areas 1 – 4 . Silicon (Si) has emerged as a strong contender to replace conventional graphite anodes due to its ultrahigh theoretical capacity (3579 mAh g − 1 for Li 15 Si 4 ), relatively low lithiation potential (< 0.4 V vs Li/Li + ), and abundant natural availability 5 – 8 . Nevertheless, the practical application of Si anodes in commercial batteries is impeded by substantial volume expansion (300%-400%) during the alloy process with lithium 9 , 10 . The stress accumulation resulting from repeated expansion and contraction leads to the fracture and even pulverization of Si particles, causing the detachment of fragments from the current collector to create “dead Si” 11 . This dramatic loss of active materials severely limits the lifespan of pure-Si anodes. Hence only a small amount (5–15 wt%) of Si is typically blended with graphite anodes in industrial manufacturing to enhance the energy density of LIBs 12 . Nanosizing Si has been proven effective in mitigating mechanical failure, as evidence indicates that the rupture of Si particles is significantly alleviated when their size is below the critical diameter of 150 nm 13 , 14 . However, the fragile solid electrolyte interphase (SEI) formed by side reactions between the increased Si surface and electrolyte breaks down during volume swing. The electrolyte gradually penetrates along the nanovoids, triggering new SEI growth at the expense of active Li + 15 . Over cycling, the SEI infiltrates into the agglomerated Si nanoparticles (SiNPs), resulting in large and inactive Si-SEI composites (“dead Si”) 16 . The evolution of the spatial configuration of Si-SEI gradually disrupts the electron conduction pathways and contributes to the capacity loss of SiNPs-based batteries. Therefore, it is imperative to regulate the interphase chemistry of SiNPs to enhance the mechanical robustness of SEI. Electrolyte engineering is recognized as a pivotal strategy for shaping the SEI chemistry and configuration by carefully selecting and modulating the electrolyte composition 17 , 18 . In the realm of Si-based batteries, the incorporation of fluoroethylene carbonate (FEC) is indispensable due to its significant enhancement of cyclic performance 19 . The resultant rigid SEI has proven to effectively mitigate cracking and delamination of the Si thin-film electrode 20 . However, FEC is prone to decomposing and generating HF gas at high temperatures 21 , causing not only the corrosion of Si bulk phase and cathode materials but also the expansion of cells 22 . Additionally, the recent application of localized high-concentration electrolytes (LHCEs) in Si anodes has gained traction due to their ability to form an inorganic-rich SEI derived from anion-dominated solvation structure 23 – 25 . However, this approach necessitates a substantial amount of expensive and environmentally unfriendly fluorinated diluents such as hydrofluoroether. It is worth noting that the inevitable fluctuations of environmental temperature require advanced battery systems to operate within a range of -20-60°C. Although fluorocarboxylic esters have allowed SiNPs to function at -20°C 26 , their practical application is hindered by low boiling points. Furthermore, low temperature results in sluggish Li + transport kinetics, while high temperature leads to more severe side reactions at the interface, posing significant challenges to the development of wide-temperature silicon-based batteries. Herein, we present a novel environmentally friendly non-fluorinated solvent, cyclopentyl methyl ether (CME), which boasts several advantages including low density, a wide liquid phase range, and a moderate dielectric constant (see Supplementary Table 1). The cyclic group within its molecule creates significant steric hindrance, leading to a noteworthy reduction in the solvating energy between CME and Li + . This results in the formation of a solvation structure primarily characterized by ion clusters, particularly anionic aggregates (AGGs) as the concentration of lithium salt (lithiumbis(fluorosulfonyl)imide, LiFSI) increases. Furthermore, the electric field strengthens the coordination of the interface FSI − with lithium, enabling rapid desolvation kinetics and the formation of anion-derived SEI. The application of cryogenic transmission electron microscopy (cryo-TEM) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) reveals a double-layer structure of the SEI, with uniformly dispersed internal nano-inorganic components and a fully covered external amorphous layer. This SEI exhibits a high Young's modulus, capable of withstanding stress accumulation resulting from volume changes, thereby safeguarding the Si particles against the formation of inactive Si-SEI composites after extended cycling. Consequently, the Si anode in the designed electrolyte can operate from − 20°C to 60°C, and the SiNPs/sulfurized polyacrylonitrile (SPAN) full cell in the 5 M LiFSI CME (or abbreviated as 5 M CME) electrolyte maintained an excellent capacity retention of 83.5% after 800 cycles at -20°C. More importantly, this straightforward strategy has successfully yielded an 80 mAh SiNPs-based pouch cell with a capacity retention of 85.6% after 150 cycles, marking a significant step forward in the practical application of silicon anode. Results Solvent selection and solvation structure of electrolytes In response to temperature variations, the selection of solvents is guided by three main criteria 2 , 27 : 1) The solvent should have a wide liquid phase range. 2) It should possess a gentle solvating ability to meet low desolvation energy requirements and a moderate dielectric constant for dissociating ionic salt. 3) It should have an appropriate electrochemical window for Si-based batteries. Among the commonly used ester and ether solvents (Fig. 1 a and Supplementary Table 1), CME stands out due to its high boiling point (106°C) and low melting point (-140°C), providing it a relatively wide liquid phase range to accommodate temperature fluctuations. Differential scanning calorimetry (DSC, Fig. 1 b) analysis also indicates that the LiFSI-CME system remains in a liquid state within the temperature range of -90 to 90°C, while the LiFSI-DME system liquefies at around − 70°C. Additionally, the commercial carbonate electrolyte, 1 M lithium hexafluorophosphate (LiPF 6 ) in ethylene carbonate (EC)/diethyl carbonate (DEC)/FEC (4.5:4.5:1 by volume) (denoted as LPF10), displays a distinct endothermic peak around 0°C and undergoes thermal decomposition around 70°C due to the poor thermal stability of LiPF 6 . These findings are consistent with the observations from optical images at low temperatures (Supplementary Fig. 1). The electrostatic potential (ESP) mapping reveals that the O position in the ether bond carries a negative charge density, which tends to bond with Li + . In comparison to DME, the CME molecule has one less oxygen, and the large steric hindrance of the five-membered ring on the edge leads to a significant reduction in electron density on the O atom, and consequently, weaker Li + coordination ability (Fig. 1 d). Furthermore, we calculated the solvation ability between Li + and various solvents (Fig. 1 c and Supplementary Fig. 2) through density functional theory (DFT) and found that the energy of solvation follows the order CME (190 kJ mol − 1 ) < THF (191 kJ mol − 1 ) < MeTHF (200 kJ mol − 1 ) < DME (269 kJ mol − 1 ). This suggests that the interaction between Li + and CME is relatively weak, facilitating the solvation structure alterations and a rapid desolvation process. This result is consistent with nuclear magnetic resonance (NMR, Supplementary Fig. 3). At the same concentration, the DME systems are more upfield-shifted than CME systems, indicating that DME provides more electron density to shield Li + 28 . Moreover, the dielectric constant of CME is 4.7, and it has a high solubility of LiFSI (7 M) 29 , supporting its suitability as an electrolyte solvent. After dissolving LiFSI into CME and DME with different concentrations, the coordination of Li + -FSI − /-solvent was demonstrated by Raman spectra (Fig. 1 e). The vibrational bond at 895 cm − 1 represents the CME solvent molecule, while the peaks at 820 cm − 1 and 850 cm − 1 are assigned to the stretching vibration of CH 2 ─O─CH 3 of the DME solvent molecule 23 . With an increase in salt concentration, the corresponding peaks of the free solvent molecules were profoundly weakened. An additional peak at 873 cm − 1 , resulting from the blue shift of pure DME is attributed to the Li + -coordinated DME 23 , indicating a strong interaction between DME and Li + . The bonds in the range of 700–775 cm − 1 correspond to the stretching/vibration of the S-N-S in FSI − anions 30 . In comparison to DME, the FSI − in the CME electrolyte exhibits a smaller red shift relative to the crystalline LiFSI (775 cm − 1 ), representing a weaker coordination ability. Specifically, the coordination environment of FSI − can be decoupled into free ions (720 cm − 1 ), contact ion pair (CIP, FSI − coordinating to one Li + , 731 cm − 1 ), ion-pair aggregate (AGG, FSI − coordinating to two Li + , 745 cm − 1 ), and nanometric aggregates (n-AGG, FSI − coordinating to three or more Li + , 756 cm − 1 ) 31,32 as shown in Fig. 1 f and Supplementary Fig. 4. As shown in Fig. 1 g, despite the salt concentration reaching 5 M, there is still approximately 5% free FSI − in DME, indicating that the strong solvation of DME prevents some FSI − from entering the first Li + solvation shell. In contrast, in CME, the FSI − exist almost entirely in the form of AGG and n-AGG. When the concentration exceeds 5 M, n-AGG predominates, meaning the FSI − are strongly interconnected through the intensive association with Li + , forming an enhanced three-dimensional network 31 . This is beneficial for widening the voltage window due to the suppression of free-solvent decomposition (Supplementary Fig. 5) 33 . However, at excessively high concentrations, such as 7 M, it leads to excessively high viscosity, a decrease in Li + conductivity, and an increase in polarization, resulting in dendrite formation during silicon lithiation (Supplementary Fig. 6). Therefore, based on the half-cell performance in Supplementary Fig. 7, the concentration of 5 M is selected for further study. The solvation structures of Li + in three electrolytes (LPF10, 5 M LiFSI DME, and 5 M LiFSI CME) from − 30 to 60°C were further analyzed using molecular dynamics (MD) simulations in Fig. 1 h-k and Supplementary Figs. 8–10. According to the radial distribution functions (RDFs) and coordination number distribution functions (CNDFs), the first solvation radius for each solvent is ~ 3 Å. In LPF10, EC is the dominant solvent in the first Li + solvation shell, with a CN of 3.42 at 30°C, followed by linear carbonate DEC (1.79) and PF 6 − (0.56). Notably, more EC was coordinated with Li + upon decreasing the temperature, as identified by the increased CN for EC (3.61 at -30°C) and the decreased CN of DEC and PF 6 − . However, when the temperature rose to 60°C, the CN of EC decreased to 3.20, followed by the enhancement of PF 6 − (0.78). This solvation structure variation has, on the one hand, increased the difficulty of low-temperature desolvation due to the strong polarity of EC. On the other hand, it has reduced the stability of the electrolyte at high temperatures, thus hindering the application of LPF10 at both high and low temperatures. In contrast, the solvation structures of 5M LiFSI DME and CME do not change significantly at different temperatures, which further verifies their temperature compatibility. More specifically, the electrolyte of 5 M LiFSI CME shows strong interaction between FSI − and Li + , with a CN of 3.66, while the CN is only 2.86 in 5 M LiFSI DME, further indicating the weak solvation behavior of CME. Different from DME, the CN of Li + -CME is only 0.93, which means the presence of numerous AGG and n-AGG structures (nano-clusters) to form three-dimensional ion-rich networks 34 within the free CME solvent molecules (Supplementary Fig. 11). Anionic aggregates at the electrified interface Although studies have shown that anion-dominated solvation structure facilitates the formation of inorganic-rich interphase 23 , 35 , the reaction behavior of n-AGG at the interface have not been thoroughly revealed. Therefore, interfacial MD simulations incorporating an external electric field were conducted to elucidate the ion distributions, solvation structures, and their effects on interfacial reactions. The snapshots are displayed in Fig. 2 a and Supplementary Fig. 12. A constant electric field (100 mV nm − 1 ) 36–38 was applied in the direction perpendicular to the silicon plane to investigate the changes in the interfacial nanostructure. Figure 2 b exhibits the number density profiles of Li + , FSI − anions and CME molecules as a function of distance from Si anode without/with applied electric field. In the inner Helmholtz layer (0.36 nm) which tightly contacts with the electrode, some CME solvent molecules exist due to the hydrogen bonding of the hydroxyl groups on the silicon surface, while in the outer Helmholtz layer (0.36-0.55nm), there is the solvation structure of lithium ions 39 . After applying the external electric field, the height of the first sharp peak of Li + increases rapidly, which suggests that electric field promote the Li + migration toward the negatively charged Si anode. Meanwhile, a large amount of FSI − are involved to approach the interface due to the strong cohesive cation-anion association, resulting in an accumulation of anions at the interface (Supplementary Fig. 12). In contrast, the number of CME molecules in the outer Helmholtz layer is significantly reduced, which indicates that CME has partially desolvated from Li + solvation shell due to its weak solvation ability while more FSI − has been incorporated into the solvation structure (Fig. 2 c). Figure 2 d further demonstrates the changes in the solvation structure at the electrified interface, where the CN of FSI − in first Li + solvation shell increases with the reduced CN of CME. Abundant coordinated FSI − (n-AGG) have high priority to decompose at negatively charged Si anode, leading to the formation of an inorganic-rich SEI. It is worth noting that FSI − tends to move away from the interface under the applied electric field in Fig. 2 b, as the farther approach of the anions to the negatively charged silicon, the greater electrostatic repulsion between them 36 , indicating the reason why FSI − is easy to desolvate under the external electric field. In order to illustrate the influence of different electrolytes on the SEI reaction, the lowest unoccupied molecular orbital (LUMO) energies of different molecules and clusters were calculated to elucidate their sequence of decomposition at the Si anode (Fig. 2 f) and validated by the first cyclic voltammetry (CV) curves (Fig. 2 e). The LUMO energies of free solvent molecules EC, DEC, FEC, DME, and CME are − 0.45, -0.098, -0.941, 1.116, and 0.913 eV, respectively, indicating that the reduction stability of ethers is higher than that of esters. In LPF10, due to the large distribution of free solvents at the electrode interface, FEC and EC are thermodynamically favorable for decomposition, corresponding to the decomposition peaks at 1.47 V and 1.16 V in CV curves 40 , respectively. When cooperated with Li + , the LUMO energies of solvents decrease because of the electron deficiency nature of Li + 41 . When introducing anions into the Li + solvation sheath, on the one hand, the LUMO energies of FSI − in Li + -solvent-FSI − complexes decline compared to that of free anions. On the other hand, FSI − shoulder the burden of electron-withdrawing effects from solvents, resulting in an increased LUMO energy of the solvent in Li + -solvent-FSI − complex compared to Li + –solvent. These phenomena suggest that the reductive stability of solvents/anions can be reduced when they connected with Li + 42 . In three types of ether electrolytes (5 M LiFSI DME, 1 M LiFSI CME, and 5 M LiFSI CME), the reduction stability reduces in sequence since the proportion of n-AGG in the solvation structure (i.e., the strong association between Li + and FSI − ) grows successively. Figure 2 e shows that the reduction potentials of 5 M LiFSI DME, 1 M LiFSI CME, and 5 M LiFSI CME are 1.13, 1.22, and 1.28 V, respectively, which is consistent with the DFT results. SEI properties determined by interfacial solvation structure The properties of SEI including its composition and nanostructure, are revealed by various characterization techniques at different spatial scales such as cryo-TEM, TOF-SIMS, and X-ray photoelectron spectroscopy (XPS). In order to illustrate the initial formation state and long-term evolution of SEI, we characterized the first lithiation/delithiation Si anode and the SEI after 50 cycles, respectively. Cryo-TEM images show that the Li 5 Si 4 crystals are formed to distinguish the SEI and bulk-phase components when Si is fully lithiated to 10 mV 43 . In 5 M LiFSI CME electrolyte, the Li 5 Si 4 crystal structure is completely wrapped by a uniform SEI with a thickness of 35–40 nm (Fig. 3 a, c). The surface SEI exhibits a typical bilayer structure with inorganic nanocrystals evenly dispersed on the inner side and covered by outer amorphous organic species. Fast Fourier transform (FFT, Fig. 3 b) and local magnified images (Fig. 3 d and Supplementary Fig. 13) reveal detailed information about its components, including Li 2 O (111), LiF (111), and Li 2 S (311) lattice planes that originate from the interfacial LiFSI decomposition. However, in LPF10 (Fig. 3 e), no obvious SEI components have been found on the crystalline Li 5 Si 4 particle surface (Fig. 3 g), but spherical LiF particles with a diameter of approximately 45–100 nm have been observed (Supplementary Fig. 14). FFT (Fig. 3 f) and local magnified images (Fig. 3 h) further exhibit lattice fringes with an interplanar spacing of 0.201 nm, which belongs to the LiF (200) plane. This phenomenon indicates that a single LiF precipitates in the form of particles from the decomposition of FEC in the LPF10 system, which is consistent with previous studies 44 , possibly due to the high interfacial energy of LiF itself. The schematics of interphases of lithiated SiNPs in 5 M LiFSI CME and LPF10 are illustrated in Fig. 3 i-j, respectively. The composition of SEI over a wide range was verified using TOF-SIMS, as shown in Fig. 3 k and Supplementary Fig. 15. After lithiation to 10 mV in the 5 M LiFSI CME electrolyte, ultra-thin organic fragments C 2 HO − concentrates at the outermost layer of SEI (corresponding to the amorphous structure in the cryo-TEM), while inorganic components Li 2 O and LiF make up the inner layer of SEI. In addition, the SEI fragment signals disappear after sputtering for 600s, indicating its uniform distribution on the silicon surface. In contrast, the signal of LiF 2 − in LPF10 penetrates the entire sputtering process, while the signals of Li 2 O − and C 2 HO − are very weak. This is consistent with the results of cryo-TEM, namely that LiF large particles precipitate in the pores of silicon anode. Many studies have demonstrated that LiF exhibits electronic insulating properties, a low Li + diffusion barrier, and a high elastic modulus 17 , 23 . However, the effectiveness of LiF in large particle form is limited, and only its uniform dispersion on the surface can protect silicon anode from volume swing. The SiNPs are amorphized while delithiated to 1 V, as shown in the cryo-TEM image and its FFT in Supplementary Fig. 16. In the 5 M LiFSI CME electrolyte, part of the Li 2 O in the SEI reacts with silicon to form Li x SiO y 19 , where the elastic Li 4 SiO 4 layer is proven to be beneficial for the integrity of the Si electrode 17 , 45 . In LPF10, LiF remains stable during lithium removal and still stacks in a granular form, where the presence of some Li 5 Si 4 indicates slow Li + transportation. In addition, XPS was employed to analyze the SEI on the silicon anodes after 50 cycles in delithiation state. In LPF10, a large amount of C-O, C = O, and O-C = O components originating from the decomposition of solvents were observed in the C1s spectrum 26 , 46 (Supplementary Fig. 17) and O1s spectrum (Fig. 3 m), indicating that the initially incomplete coverage SEI of the active silicon anode continues to undergo side reactions with the electrolyte. Despite the subsequent formation of a LiF-rich SEI (Fig. 3 m, o), a significant amount of Li + are consumed during the SEI reconstruction process, leading to rapid initial decay of the Li/Si half-cell in LPF10. Furthermore, the decomposition of FEC results in the incorporation of LiF into the interior of the silicon nanoparticles during cycling 47 , which causes some damage to the integrity of the silicon particles. In the 5 M LiFSI CME electrolyte, the bilayer SEI remains stable during cycling. The outer layer of the SEI contains a high content of Li x SiO y and a small amount of organic components, while the inner layer consists of LiF and Li 2 S inorganic components (Fig. 3 l, n and Supplementary Fig. 17). This rigid and flexible SEI, composed of dispersed LiF nanoclusters embedded amorphous Li x SiO y and organic materials, can withstand the stress accumulation from volume changes and does not undergo fragmentation during long cycling. For 5 M LiFSI DME, the SEI components are similar to those in 5 M LiFSI CME due to the decomposition of solvated FSI − (Supplementary Figs. 18–19). However, there are more FSI − decomposition intermediates S n 2− and -SO 2 - in its SEI since less FSI − present in the form of n-AGG in the 5 M LiFSI DME electrolyte 48 , which indicates that the anion continues to decompose with incomplete passivation protection of the silicon surface. Improvement of electrochemical kinetics The sluggish transport kinetics inhibit the performance of SiNPs anode at low temperatures. Among the three kinetic processes of Li + migration in bulk electrolyte, desolvation, and diffusion through the SEI layer, the latter two are generally considered as the rate-determining steps 49 , 50 . Due to the heterogeneous solvation structure of the 5 M LiFSI CME, the migration of Li + no longer follows the Stokes-Einstein law, but rather moves in a hopping manner through Lewis basic sites from one anion to another 33 . This results in a higher ion transfer number ( t + ) of 0.50 for the 5 M LiFSI CME electrolyte compared to 0.35 for the LPF10 (Supplementary Fig. 21), despite its lower ion conductivity originated from low dielectric constant of CME and high viscosity at room temperature (Supplementary Fig. 20). When the temperature falls to -20°C, the ion conductivity of LPF10 drops sharply due to its solidification. To unravel the difference of Li + transport property between the interface in two electrolytes, temperature-dependent electrochemical impedance spectroscopy (EIS) and the distribution relaxation time (DRT) analysis were conducted (Fig. 4 a-b and Supplementary Fig. 22). The DRT analysis classified different electrochemical processes based on local maxima in the continuous distribution function 51 , 52 , including ohmic resistance (R b ), SEI layer resistance (R SEI ), and charge transfer resistance (R ct ). The solvated Li + from electrolyte to reach the silicon surface need to overcome two energy barriers: the desolvation activation energy (E a1 ) and the energy for crossing the SEI (E a2 ), which can be obtained through the Arrhenius equation from R ct and R SEI respectively 26 , 49 . To eliminate the influence of lithium metal, symmetrical lithiated Si cells were assembled at 60% state of charge after cycling three times with the corresponding electrolytes. The R ct of the LPF10 electrolyte significantly increased from 30°C to -20°C, with the E a1 value reaching 71.08 kJ mol − 1 , far greater than that of 5 M LiFSI CME (42.57 kJ mol − 1 , Fig. 4 c). This is consistent with the previous analysis about desolvation energy and the interfacial solvation structure. In addition, the double-layer SEI formed in 5 M LiFSI CME exhibited a value of E a2 (52.38 kJ mol − 1 ), also lower than the SEI formed in LPF10 (58.56 kJ mol − 1 , Fig. 4 d). The decreased E a2 implies that the SEI in 5 M LiFSI CME has high Li + conductivity, stemming from uniformly embedded inorganic nano-structures in the amorphous components and abundant grain boundaries favorable for ion transport within the SEI. The rapid kinetic process is conducive to the low-temperature capacity release. Figure 4 e shows the low-temperature application potential of different electrolytes in Li/SiNPs half-cells. After activating the battery for three cycles at 0.05 C under 30°C, capacity tests at different temperatures were carried out at 0.1 C. The initially reversible (charge) specific capacities of the half-cell in LPF10, 5 M LiFSI DME, and 5 M LiFSI CME were 2949, 3859.2, and 3408.8 mAh g − 1 , corresponding to their initial coulombic efficiencies (ICE) of 89.92%, 91.97%, and 91.2%, respectively. Although the initial capacity of DME is higher, its rapid capacity attenuation suggests the poor passivation ability of SEI. When the temperature drops to -10°C or even − 20°C, the capacity of SiNPs electrode in LPF10 is only 1010.4 and 0 mAh g − 1 (Fig. 4 g), because of the high melting point of EC and its strong binding energy with Li + . Although the electrolyte 5 M LiFSI DME remains liquid at -20°C, SiNPs in it can only release the capacity of 188 mAh g − 1 (Fig. 4 h). In contrast, SiNPs in the 5 M LiFSI CME electrolyte can still release a delithiation capacity of 941 mAh g − 1 at -20°C (Fig. 4 i), and when the temperature rises to 20°C, the capacity rapidly increases to 2844.4 mAh g − 1 , demonstrating its ability to withstand temperature fluctuations. In addition, the silicon electrode exhibited the best rate performance in the 5 M LiFSI CME (Supplementary Fig. 24), with a capacity of 1014.5 mAh g − 1 even at a high current rate of 5 C, far exceeding that of 5 M LiFSI DME (608.8 mAh g − 1 ) and LPF10 (457.8 mAh g − 1 ). Figure 4 f shows the long-term cycling performance of the Li/Si half-cell in different electrolytes, where it maintained 80.8% capacity retention after 200 cycles in 5 M LiFSI CME, with an average CE of 99.52%, fully demonstrating the structural stability of the SiNPs in this electrolyte. In contrast, the SiNPs anode exhibited a drastic capacity decay after 120 cycles in LPF10, while only 17.7% capacity retention after 200 cycles in 5 M LiFSI DME. The initial capacity increase in the first 20 cycles in 5 M LiFSI CME can be attributed to the slow electrochemical activation process of the silicon anode in this viscous electrolyte. Subsequently, the SiNPs anodes are subjected to more severe 1 C long-term cycling conditions (Supplementary Fig. 25). The battery in 5 M LiFSI CME exhibited a high capacity retention of 97.2% after 200 cycles, with a remaining capacity of 1296.4 mAh g − 1 . In comparison, the capacity retention of the SiNPs anode in LPF10 and 5 M LiFSI DME were only 38% and 30%, respectively. High temperature strengthens the parasitic reaction between the SiNPs anode and the electrolytes (Supplementary Fig. 26). The short circuit of LPF10 after 25 cycles possibly due to increased polarization and lithium dendrites formation sourced from electrolyte consumption, while the rapid capacity decay of 5 M LiFSI DME is due to the loose SEI on SiNPs surface. In contrast, 5 M LiFSI CME still maintains 81% of its capacity after 100 cycles which confirms the robustness of the bilayer SEI. In order to reveal the evolution of interface impedance in the long cycle process, EIS testing (Supplementary Fig. 27) and DRT analysis of Li/SiNPs half-cells were carried out in different electrolytes. According to the literature, the time constant (τ) for lithium ions to pass through SEI is between 10 − 5 and 10 − 3 s, and the charge transfer is between 10 − 3 and 10 s 52 , 53 . As shown in Fig. 4 j-l, with the progress of the cycles, the interfacial impedance including R SEI and R ct gradually increases. The increase ratio of LPF10 is the highest, while the impedance of 5 M LiFSI CME remains almost unchanged after 100 cycles. It further illustrates that the designed electrolyte 5 M LiFSI CME can construct a highly stable SEI on the surface of SiNPs, which can fully encapsulate the silicon and prevent electrolyte corrosion during long cycles. Suppression of spatial configuration evolution Scanning electron microscopy (SEM) was conducted to investigate the morphology and thickness evolution of the SiNPs anode after 50 cycles. In Supplementary Fig. 28, the SiNPs anode in LPF10 electrolyte experienced severe cracking, while the enlarged image shows that surface of SiNPs underwent pulverization after long-term expansion and contraction. In 5 M LiFSI DME, the fissures were smaller compared to LPF10 electrolyte, but still more pronounced than that of 5 M LiFSI CME. The SiNPs after 50 cycles in 5 M LiFSI CME electrolyte still exhibited an intact structure, indicating that the encapsulated SEI has a good protective effect on the integrity of the SiNPs anode. In addition, cross-sectional images are presented to explore the thickness expansion of SiNPs electrodes before and after cycling in Fig. 5 a. Compared to the initial thickness of silicon electrode (37 µm), the thicknesses of SiNPs anode after 50 cycles increased by 89%, 51%, and 35% in LPF10, 5 M LiFSI DME, and 5 M LiFSI CME electrolytes, respectively. The significant electrode volume expansion is partly due to the poor mechanical strength of the LPF10-drived SEI and also the extensive pulverization and loosening of internal SiNPs. The elastic SEI formed in 5 M LiFSI CME can resist internal stress from volume changes, thereby protecting the structure of SiNPs. Atomic force microscopy (AFM) was performed to further investigate the mechanical properties of the SEI formed in different electrolytes. As shown in the 3D electrode mapping in Fig. 5 b, the SiNPs anode in LPF10 exhibits significant expansion and abruption morphology after 50 cycles, with an average roughness of 93.4 nm. In comparison, the SiNPs anode cycled in 5 M LiFSI CME electrolyte shows a more uniform surface morphology, with an average roughness of only 40.3 nm. Furthermore, the Derjaguin-Muller-Toporov (DMT) modulus mapping (Fig. 5 c) further demonstrates that the SEI produced by 5 M LiFSI CME has a higher modulus value (3.35 Gpa) compared to the SEI of LPF10 (2.13 Gpa). The modulus distribution of the SEI produced by LPF10 is unhomogeneous, and low modulus areas are damaged after stress accumulation, leading to particle pulverization and electrode fractures. Additionally, through corresponding 2D adhesion mapping analysis (Supplementary Fig. 29), strong adhesion is observed at the fracture site of the electrode cycled in LPF10, which would lead to continuous electrolyte penetration and subsequent side reactions. Differently, the SEI derived from 5 M LiFSI CME has uniform modulus and adhesion distributions, which are beneficial for the long-term structure stability and excellent electrochemical performance of the SiNPs anode. The microstructural changes of the silicon anode were examined using high-resolution transmission electron microscopy (HR-TEM). As depicted in Supplementary Fig. 30, the pristine SiNPs were initially spherical, with a diameter of around 100 nm and a 2.3 nm amorphous SiO 2 layer on the surface. Upon undergoing 50 cycles in LPF10 electrolyte, the SiNPs underwent deformation and agglomeration, forming blocks several hundred nanometers in size 16 (Fig. 5 d). A magnified image (Fig. 5 e) revealed that the surface SEI with low contrast had ruptured, primarily due to its poor mechanical properties. These observations were further supported by the selected area electron diffraction (SAED, Supplementary Fig. 31) and lattice fringes in Fig. 5 g, which indicates that the SEI framework (Fig. 5 f) primarily consisted of dispersed LiF nanoclusters. This suggests that the initial LiF particles gradually adhered to the silicon surface and doped it during the cycling process. Moreover, the annular dark field (ADF) image in Fig. 5 l and the corresponding energy dispersive spectrum (EDS) mapping demonstrated the presence of the F element inside the agglomerated silicon, representing inward permeation of the SEI, consistent with previous reports 15 . The original spherical SiNPs transformed into a fibrous shape. This phenomenon illustrates the pulverized SiNPs-SEI composite as illustrated in Fig. 5 k and exposes the failure mechanism of the SiNPs anode. Conversely, in the 5 M LiFSI CME electrolyte, the SiNPs remained dispersed and spherical after long cycles (Fig. 5 h). The magnified image (Fig. 5 i-j) revealed the presence of an intact wrapped SEI on the SiNPs surface with approximately 44 nm. EDS mapping (Fig. 5 m) showed that the elements O, F, S, and N in the SEI were uniformly distributed on its particle surface, consistent with XPS results. Similar phenomena were observed on other particles as well (Supplementary Fig. 31). In the 5 M LiFSI DME electrolyte (Supplementary Fig. 32), a small amount of particle agglomeration and a thicker SEI (46-55nm) were observed, which was identified as the primary reason for its poor electrochemical performance. Electrochemical performance of SiNP-based full cells The practical application potential of the electrolyte in wide-temperature SiNPs-based batteries was verified through the use of SPAN and lithium iron phosphate (LFP) as cathodes to prepare full cells. Notably, the SPAN cathode does not contain any lithium inventory, thus the SiNPs anode was pre-lithiated in half-cells with corresponding electrolytes and then reassembled into SiNPs/SPAN full cells. On the other hand, pre-cycling or pre-lithiation operations were not conducted on the SiNPs anodes for SiNPs/LFP cells. Figure 6 a depicts the excellent cyclic stability of SiNPs/SPAN in the 5 M LiFSI CME electrolyte at 30°C, demonstrating a capacity retention of 90% after 400 cycles. In contrast, the polarization of the full cells in LPF10 and 5 M LiFSI DME significantly increased after 100 cycles (Supplementary Fig. 33). Furthermore, at a high temperature of 60°C (Fig. 6 b and Supplementary Fig. 34), the SiNPs/SPAN battery in the 5 M LiFSI CME electrolyte exhibits a capacity retention of 80.8% for 140 cycles and an average CE of 99.95%, surpassing that of 5 M LiFSI DME (99.78%) and LPF10 (99.34%), thus reflecting that the robust and stable SEI on SiNPs anodes can suppress side reactions from the electrolyte at high temperatures. Encouragingly, the SiNPs/SPAN full cell in the 5 M LiFSI CME electrolyte maintained a capacity retention of 83.5% after 800 cycles at -20°C (Fig. 6 c). The voltage-capacity profiles indicate the release of a specific capacity of 938.6 mAh g − 1 at 0.3 C (1 C = 1675 mAh g − 1 according to SPAN) at the 4th cycle, while cells in 5 M LiFSI DME and LPF10 electrolytes can only release capacities of 800.8 mAh g − 1 and 755.4 mAh g − 1 , respectively (Fig. 6 d-e and Supplementary Fig. 35). The enhanced electrochemical performance is attributed to the solvation structure of the anion aggregation at the interface and its rapid interfacial ion transport kinetics in the 5 M LiFSI CME electrolyte system. Likewise, this electrolyte is also compatible with LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode (Fig. 6 f), releasing a capacity of over 60 mAh g − 1 at -20°C in the SiNPs/NCM811 full cell and maintaining stability for 200 cycles, while cells in other electrolytes struggle to work. In addition, LFP cathodes with different loading are used to match the silicon anode in Supplementary Fig. 36 to illustrate the salient merits of the designed electrolyte because high loading exacerbates thickness swelling and lengthens the transmission path of Li + . When the designed capacity is 0.5 mAh cm − 2 , the capacity retention of the SiNPs/LFP coin cell is 82.1% after 300 cycles in 5 M LiFSI CME electrolyte. When the designed capacities is increased to 1 mAh cm − 2 and 1.5 mAh cm − 2 , the capacity retention is 92% (120 cycles) and 77% (100 cycles), respectively, while the capacity deteriorates quickly in LPF10. Finally, we assembled a double-layer pouch cell (80 mAh, 8.7 ×4.5 cm 2 in Fig. 6 g) assembled with SiNPs anode and LFP cathode with limited electrolyte (electrolyte/cathode, E/C = 3g Ah − 1 ), which is rarely reported in pure Si-based batteries. The pouch cell demonstrates excellent cycling performance, with a capacity retention of 85.6% after 150 cycles. Compared to previous reports on SiNPs-LFP full cell configurations, as shown in Fig. 6 h and Supplementary Table 3, the electrochemical performance of our SiNPs/LFP full cells has a strong competitive advantage. If the graphite anode in the existing commercial LFP batteries is replaced with the SiNPs anode, we speculate that its gravimetric energy density can be increased by 20% (Supplementary Table 2). This work makes a significant step toward the practical application of Si anode and demonstrates the potential for future commercialization in high energy density LIBs. Discussion In this work, we present an electrolyte solvation engineering to overcome several challenges associated with SiNPs anode, including fragile SEI, low-temperature kinetics, and high-temperature parasitic reactions. We found that an electrolyte based on CME is capable of maintaining a liquid phase within a wide temperature range (-90 to 90°C). The spatial hindrance of CME molecules reduces the solvation energy between Li + and themselves, which allows AGG and n-AGG to primarily occupy their solvation structure. Additionally, the electric field facilitates the entry of FSI − ions with Li + into the outer Helmholtz layer of silicon anode, which preferentially decomposes to form anion-derived SEI. Compared to the SEI from LPF10 which exhibits initial precipitation of particulate LiF and subsequent reconstruction during cycling, the designed electrolyte enables the formation of a fully encapsulated double-layer SEI in the first cycle and maintains stability in subsequent cycling processes. The inner layer composed of LiF and Li 2 S inorganic nano-clusters, uniformly dispersed in the amorphous outer structure of the SEI, provides flexibility and high mechanical strength to handle the stress accumulation resulting from the volume expansion of SiNPs, thereby preventing SEI rupture and electrolyte invasion during cycling. Consequently, the SiNPs anode maintains its intact spherical particle structure without the occurrence of dead pulverized silicon-SEI composites during long cycling processes, leading to stable operation at temperatures ranging from − 20 to 60°C. The assembled SiNPs/SPAN full cell demonstrates excellent electrochemical performance with capacity retention of 83.5% after 800 cycles at -20°C. Furthermore, the enlarged 80 mAh SiNPs/LFP pouch cell retains 85.6% of its capacity after 150 cycles under limited electrolyte conditions. This study on the relationship between interfacial solvation structure, SEI chemistry, and spatial configuration evolution of silicon anode is of great significance for the development of next-generation high-energy-density LIBs. Methods Electrolyte preparation Lithium hexafluorophosphate (LiPF 6 ), lithium bis(fluorosulfonyl)imide (LiFSI), 1,2-dimethoxyethane (DME), ethylene carbonate (EC), fluoroethylene carbonate (FEC), and diethyl carbonate (DEC) were purchased from DodoChem. Cyclopentyl methyl ether (CME, ≥ 99.9%) was used as received from Aladdin. The LPF10 electrolyte was prepared by dissolving the 1 M LiPF 6 into the EC/DEC/FEC with volume ratio 4.5:4.5:1. The 5 M LiFSI DME electrolyte was prepared by dissolving the 5 M LiFSI into the DME solvent. As for the preparation of CME-based electrolyte, LiFSI with different concentration (1 M, 3 M, 5 M, and 7 M) was dissolved in the CME. All the electrolytes were thoroughly stirred for 3 h before use. The whole process of electrolyte preparation was conducted in the Ar-filled glove box with water and oxygen concentration less than 0.1 ppm. Electrode preparation The silicon electrode was fabricated with 70 wt% SiNPs powder (Shanghai St-Nano Science and Technology Co., Ltd), 15 wt% super P (Timcal) as conductive additive, and 15 wt% lithium polyacrylate (LiPAA, 4 wt% aqueous solution) binder in water to form a slurry. The obtained slurry was cast onto copper foil, dried at room temperature for 6 h and further dried at 80°C overnight under vacuum. The typical mass loading of the SiNPs anode in Li/SiNPs half-cell is ~ 1.0 mg cm − 2 and the corresponding areal capacity is ~ 3.0 mAh cm − 2 . Similarly, the slurry of LFP cathode was prepared by mixing commercial LFP materials, polyvinylidene fluoride (PVDF, 99.5%, Arkema), super P and carbon nanotube (CNT, Guangdong Canrd New Energy Technology Co., Ltd.) with the mass ratio of 8:1:0.5:0.5. The slurry was dissolved in N-methyl-1,2-pyrrolidone (NMP, 99.9%, MTI corporation KJ GROUP) and cast onto aluminum foil collector. After NMP solvent was evaporated at 110°C for 12 h in vacuum oven, the electrode was calendared. The mass loading of the LFP cathode is 4–11 mg cm − 2 and the corresponding areal capacity is 0.5–1.5 mAh cm − 2 . The Synthesis of SPAN material could be accessed in our previous work 54 . The SPAN cathode was prepared by slurry coating on Al foils, with SPAN, CNT and PVDF in a mass ratio of 8:1:1 mixed in NMP solvent. Cell fabrication In Li/SiNPs coin cells, the prepared Si electrodes, Li foils (500 µm) and Polyethylene (PE, Asahi Kase) membranes were used as working electrodes, counter electrodes and separators, respectively. In full cell configurations, the negative/positive (N/P) ratio is controlled to about 1.1. The coin cells (CR2032) were assembled with the above cathode, SiNPs anode and polypropylene (PE) separator in an argon-filled glovebox. And 60 µL electrolyte was added in each coin cell. The pouch-type SiNPs/LFP cells with dimensions of 8.7 cm × 4.5 cm were assembled using pouch-cell production machines (MTI corporation KJ GROUP) utilizing above-mentioned electrodes and PE as separator (one LFP cathode foil with double-side coated and two SiNPs anode foils with single-side coated). Electrochemical measurements The galvanostatic charge–discharge measurements of coin cells and pouch cells were carried out using a Land CT3001A battery test system (Wuhan Land Electronics Co. Ltd). The batteries were placed in the climatic chamber (GPR, Espec, Guangzhou, China) and brought to an appropriate onset temperature (− 20°C to 60°C) for the cycling test in wide temperature range. The Li/SiNPs half cells were measured at 0.05 C for the first 3 cycles and 0.2 C/1 C for the subsequent cycles between 0.01 V and 1.0 V (vs. Li/Li + ) at room temperature, where 1 C = 3579 mA g − 1 . Temperature fluctuation for Li/SiNPs half cells was tested at 0.05 C for the first 3 cycles at 30°C and 0.1 C charge–discharge mode in different temperatures. The SiNPs/SPAN coin cells were cycled at 0.6-3.0 V at − 20°C, 30°C, and 60°C after fabrication. The SiNPs/NCM811 coin cell were conducted within a voltage window of 2.0–4.0 V at − 20°C. The SiNPs/LFP coin cells and pouch cells were tested at the voltage of 2.5–3.7 V at 30°C. The electrochemical impedance spectroscopy (EIS), Cyclic voltammetry (CV), linear sweep voltammetry (LSV) were examined in VMP3 potentiate/galvanostatic (Bio-Logic) electrochemical workstation. The temperature-dependent EIS was carried out in the climatic chamber with a temperature range from − 20°C to 30°C with the frequency range of 300 kHz–10 mHz with a voltage amplitude of 10 mV. The CV curves were obtained at a rate of 0.05 mV s − 1 in a voltage range of 0.01- 2 V (vs. Li/Li + ). LSV test was carried out within OCV-7 V with aluminum foil as the work electrode and lithium foil as the counter electrode and reference electrode. The ionic conductivities of electrolytes are tested in stainless-steel symmetrical cells. EIS of these cells were measured at a voltage amplitude of 10 mV and in a frequency range of 10 6 to 0.1Hz. The calculation is based on the following equation: $$\sigma =\frac{L}{RS}$$ where R is the intercept of the Nyquist plot and Z’ axis, L and S is the distance and area of stainless steels. The Li + transference numbers are tested in Li/Li symmetric cells using 10 mV direct-current (DC) polarization and alternating-current (AC) impedance before and after polarization. The calculation formula is: $${t}_{{Li}^{+}}=\frac{{I}_{s}(\varDelta \text{V}-{I}_{0}{R}_{0})}{{I}_{0}(\varDelta \text{V}-{I}_{s}{R}_{s})}$$ where I s and I 0 is the steady-state currents and initial current, respectively, R 0 and R s is the interfacial resistance before and after polarization, respectively. The EIS was characterized in a frequency range between 10 6 and 0.1 Hz with a voltage amplitude of 5 mV. Characterizations The DSC experiments were carried out using a NETZSCH DSC 204HP at a cooling/heating rate of 5°C min − 1 . Raman spectra were carried out on on a Horiba Jobin Yvon LabRAM HR Evolution (532 nm laser). 7 Li-NMR spectra are recorded on an Agilent DD2-600 (600 MHz) at room temperature. The Scanning electron microscopy (SEM) images of all materials were obtained using a field emission scanning electron microscope (FE-SEM, Hitachi SU8000) at 5 kV. Cryo-Electron Microscopy was carried out on FEI Talos F200C under low dose mode at an accelerating voltage of 200 kV. The element analysis of Si surface after 50th cycling was performed by X-ray photoelectron spectroscopy (XPS) (Thermo ESCALAB 250Xi) with X-ray excitation source (monochrome Al Ka, power 150W, X-ray beam spot 500 µm). To avoid exposure to air and moisture, samples were transported from the glovebox to the XPS instrument directly. The data we obtained were corrected by a standard C 1s peak at 284.8 eV. The time-of-flight secondary ion mass spectrometry (TOF-SIMS) was obtained from PHI nanoTOFII Time-of-Flight SIMS. The sputtering and analysis areas were 400 × 400 µm 2 and 50 × 50 µm 2 , respectively. To access the morphology evolution of Si nano-particles in different electrolytes, a high-resolution TEM (HR-TEM) was conducted using a cold field emission transmission electron microscope (JEM-2100F, JEOL) at 200 kV. The Atomic Force Microscopy (AFM) of cycled Si electrodes was carried out on Bruker Dimension Icon. Derjaguin–Muller–Toporov (DMT) modulus images were acquired using an insulating silicon AFM tip (k = 26 N m − 1 , f 0 = 300kHz) with peak force tapping mode. Cryo-TEM sample preparation To avoid the influence of binder and surper P, we prepared the SiNPs anode sample by the slurry with SiNPs powder and LiPAA in a mass ratio of 9.5:0.5. After drying, the anode was lithiated to 1 mV and delithiated to 1 V respectively, using different electrolytes in Li/Si half cells. After cycling, cells were disassembled in an Ar-filled glove box. The Si electrodes were rinsed by DMC/DME to remove residual Li salts and then dried in the vacuum chamber. Then the electrodes are scratched, and deposited onto a microgrid carbon film supported by a copper grid. The microgrid carbon film were quickly transferred into liquid nitrogen outside of the argon-filled glovebox using a sealed container. The samples were then placed onto the cryo-EM holder, immersed in liquid nitrogen. DFT caculation The Spin-polarized density functional theory (DFT) calculations were carried out in Material Studio software’s DMol3 module. Geometry optimizations and energy calculations were performed using Lee–Yang–Parr correlation functional (B3LYP) at DNP level along with the Grimme method for dispersion correction. The convergence criteria of the energy and force were set to 1 × 10 − 5 Hartree and 0.002 Hartree/Å, respectively. The global orbital cutoff was set to 4.4 Å. The solvent–solute interaction was considered with the universal solvation model of conductor-like screening model (COSMO). Frequency analysis was performed to ensure the ground state of molecular structures. The solvating energy (E b ) was defined as: E b = E [Li−solvent]+ - E solvent - E Li+ Where E [Li−solvent]+ is the energy of the Li + -solvent complex, E solvent is the energy of the solvent molecule and E Li+ is the energy of the Li + ion. This calculation is restricted to a local single ideal solvation structure, and the effect of increasing overall coordination number is not considered. Molecular dynamics simulation Atomistic molecular dynamics simulations have been performed in the GROMACS 55 (version 2020.6) simulation package, using the optimized potentials for liquid simulations all-atom (OPLS-2009IL 56 and OPLSAAM 57 , 58 ) force field. Three systems were simulated, sys1 contains 369 LiFSI and 632 CME molecules; sys2 contains 342 LiFSI and 658 DME; sys3 contains 84 LiPF6, 379 EC, 422 DEC, and 115 FEC. For all systems the molecules were first randomly placed in cubic boxes of around 10 nm. After thousands of steps of energy minimization, the systems were equilibrated for 10 ns and followed the production runs of 40 ns under the NPT ensemble at three temperatures of 333, 303, and 243 K. For interfacial simulations, the Si surface was built through the Materials Studio Software with side length around 5.7 nm, and 368 LiFSI and 632 CME molecules were randomly placed on the surface. After thousands of steps of energy minimization, the systems were equilibrated for 10 ns with the lateral axis fixed under the semi-isotropic NPT ensemble, and followed the production runs of 40 ns under with and without an electric field of 0.1 V/nm perpendicular to the surface. The temperature was controlled using the Nose-Hoover method and the pressure was coupled to 1 atm using the Parrinello-Rahman method. The cutoff scheme of 1.2 nm was implemented for the non-bonded interactions, and the Particle Mesh Ewald method 59 with a fourierspacing of 0.1 nm was applied for the long range electrostatic interactions. All covalent bonds with hydrogen atoms were constraint using the LINCS algorithm 60 . Declarations Data availability All data are available in the main test or the Supplementary information. Acknowledgements We acknowledge financial support from the Natural Science Foundation of China (22022813), the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang (2019R01006), the Zhejiang Provincial Natural Science Foundation of China (LQ24B030002) and the China Postdoctoral Science Foundation (2022M722729, 2023T160571). We thank Mrs. Lingyun Wu in the Center of Cryo-Electron Microscopy (CCEM), Zhejiang University for her technical assistance on Cryo-EM. Authors thank Mrs. Na Zheng at State Key Laboratory of Chemical Engineering in Zhejiang University for performing SEM. We also thank Xiaokun Ding at Department of Chemistry, Zhejiang University for HRTEM operation. Author contributions Y.L. conceived the idea and supervised the project. S.M. and J.Z. designed the experiments. S.M. performed the experiments with the help of S.Z., Z.L., Q.W., and H.C. J.Z. performed the cyro-TEM characterizations. J.M. performed the DFT calculations. Z.S. synthesized and fabricated the SPAN electrodes. All authors discussed the results and participated in writting the manuscript. Competing interests The authors declare no competing interests. References Armand, M. & Tarascon, J.-M. Building better batteries. Nature 451 , 652–657 (2008). Xu, J. et al . 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3865538","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":267442554,"identity":"10650385-de40-4c0a-909a-974188d4ca33","order_by":0,"name":"Yingying Lu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA9UlEQVRIiWNgGAWjYDACZhBhwMDAx8B8gEECxDlArBY2BrYEIrXAABsDjwGERUiLwXHew695Cu7YtUnkfP5g2cYgx3cjgfFzAT4th/nSrHkMniW3SeRuMJBsYzCWvJHALD0DrxYeM2Meg8PJbEAtCUAtiRtuJLAx8xCnJefBAaCWemK0GD8GarEDamFsAGpJMCCkRRJoC+Mcg8MJbDzPjBkkzkkYzjzzsFkanxa+82eMP7z5c9ienz358WeJMht5vuPJBz/j06JwgIFNCqggsQHIYZYARyZjAx4NDAzyDQzMH38wMNiDOIwf8KodBaNgFIyCkQoAQMVH4ZlVe3oAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0001-9713-8441","institution":"Zhejiang University","correspondingAuthor":true,"prefix":"","firstName":"Yingying","middleName":"","lastName":"Lu","suffix":""},{"id":267442555,"identity":"acfffdf6-8a3e-4950-bf2d-a6131460a942","order_by":1,"name":"Shulan Mao","email":"","orcid":"","institution":"Zhejiang University","correspondingAuthor":false,"prefix":"","firstName":"Shulan","middleName":"","lastName":"Mao","suffix":""},{"id":267442556,"identity":"2a446e0a-c4d8-40c9-bafc-3aa6866ec092","order_by":2,"name":"Jiahui Zhang","email":"","orcid":"","institution":"Zhejiang University","correspondingAuthor":false,"prefix":"","firstName":"Jiahui","middleName":"","lastName":"Zhang","suffix":""},{"id":267442557,"identity":"6b5f496b-4c46-4284-9697-4f5eff079d52","order_by":3,"name":"Jiale Mao","email":"","orcid":"","institution":"Zhejiang University","correspondingAuthor":false,"prefix":"","firstName":"Jiale","middleName":"","lastName":"Mao","suffix":""},{"id":267442558,"identity":"795dba0d-8f6c-4137-a2c4-3d960c13c4ed","order_by":4,"name":"Zeyu Shen","email":"","orcid":"","institution":"Zhejiang University","correspondingAuthor":false,"prefix":"","firstName":"Zeyu","middleName":"","lastName":"Shen","suffix":""},{"id":267442559,"identity":"812037e3-7a0a-4b68-820a-9075a180ce1d","order_by":5,"name":"Ziren Long","email":"","orcid":"","institution":"Zhejiang University","correspondingAuthor":false,"prefix":"","firstName":"Ziren","middleName":"","lastName":"Long","suffix":""},{"id":267442560,"identity":"74c9c01f-3fc6-4e1c-a648-d116e0491326","order_by":6,"name":"Shichao Zhang","email":"","orcid":"","institution":"Zhejiang University","correspondingAuthor":false,"prefix":"","firstName":"Shichao","middleName":"","lastName":"Zhang","suffix":""},{"id":267442561,"identity":"fe759ef8-6c0b-4243-8daa-b12c3f037bde","order_by":7,"name":"Qian Wu","email":"","orcid":"","institution":"Zhejiang University","correspondingAuthor":false,"prefix":"","firstName":"Qian","middleName":"","lastName":"Wu","suffix":""},{"id":267442562,"identity":"3e2997e3-3de5-4606-aed7-c81ca56deac3","order_by":8,"name":"Hao Cheng","email":"","orcid":"https://orcid.org/0000-0003-1031-8357","institution":"Zhejiang University","correspondingAuthor":false,"prefix":"","firstName":"Hao","middleName":"","lastName":"Cheng","suffix":""}],"badges":[],"createdAt":"2024-01-15 06:00:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3865538/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3865538/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":50053606,"identity":"8834ed6d-0ef4-460b-81ba-e8838729cd2c","added_by":"auto","created_at":"2024-01-23 17:04:24","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":5807225,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePhysical properties and solvation structure of electrolytes.\u003c/strong\u003e \u003cstrong\u003ea\u003c/strong\u003e Comparison of melting points and boiling points between CME and some commonly reported solvents. \u003cstrong\u003eb \u003c/strong\u003eDSC heating curves of different electrolytes at a rate of 5 °C min\u003csup\u003e-1\u003c/sup\u003e. \u003cstrong\u003ec\u003c/strong\u003e Solvating energies between Li\u003csup\u003e+\u003c/sup\u003e and the various solvent molecules. \u003cstrong\u003ed\u003c/strong\u003e ESP mappings\u003cstrong\u003e \u003c/strong\u003eof DME and CME, respectively. \u003cstrong\u003ee \u003c/strong\u003eRaman spectra of the corresponding electrolytes and solvents. \u003cstrong\u003ef, g\u003c/strong\u003e Fitted Raman data at LiFSI regions (f) and ratios of coordination structures (g). \u003cstrong\u003eh, j\u003c/strong\u003e Snapshots of MD simulation in 5 M LiFSI DME (h) and 5 M LiFSI CME (j) at 30 °C. \u003cstrong\u003ei, k\u003c/strong\u003e RDFs and CNDFs of Li\u003csup\u003e+\u003c/sup\u003e-solvents and Li\u003csup\u003e+\u003c/sup\u003e-anion pairs and representative ionic solvation clusters in 5 M LiFSI DME (i) and 5 M LiFSI CME (k) at 30 °C.\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-3865538/v1/1430f2d44ed8d943b1c7def6.png"},{"id":50053608,"identity":"3dd4145a-a4ff-48da-aef3-1ac2c30f706f","added_by":"auto","created_at":"2024-01-23 17:04:24","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":8415978,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eInterfacial electrolytes and SEI formation process. a\u003c/strong\u003e Snapshots of MD simulation near the Si surface in 5 M LiFSI CME.\u003cstrong\u003e b \u003c/strong\u003eNumber density profiles of Li\u003csup\u003e+\u003c/sup\u003e (uppermost), FSI\u003csup\u003e–\u003c/sup\u003e (middle), and CME (bottom), under electric field of 0, and 100 mV near the Si surface in 5 M LiFSI CME obtained from MD simulation.\u003cstrong\u003e\u0026nbsp;c \u003c/strong\u003eTypical Li\u003csup\u003e+\u003c/sup\u003e solvation structures in the interfacial region of (a).\u003cstrong\u003e d \u003c/strong\u003eRDFs and CNDFs of Li\u003csup\u003e+\u003c/sup\u003e-CME and Li\u003csup\u003e+\u003c/sup\u003e-FSI\u003csup\u003e-\u003c/sup\u003e pairs on the electrified surfaces. \u003cstrong\u003ee \u003c/strong\u003eCV plots\u003cstrong\u003e \u003c/strong\u003eof Li/Si cells using different electrolytes at a scan rate of 0.05 mV s\u003csup\u003e-1\u003c/sup\u003e (The inset shows a magnified view from 1.0 to 1.5 V vs Li/Li\u003csup\u003e+\u003c/sup\u003e). \u003cstrong\u003ef\u003c/strong\u003e Highest occupied molecular orbital (HOMO) and LUMO levels of different molecules and clusters from DFT calculation.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-3865538/v1/14732448d7cb670bb5a1a175.png"},{"id":50053611,"identity":"485967c1-3266-4ef1-b711-9919ff8244a3","added_by":"auto","created_at":"2024-01-23 17:04:24","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":26981968,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eChemistry and structure of SEI on SiNPs.\u003c/strong\u003e Cryo-TEM images and corresponding FFT images of SiNPs after first lithiation to 10 mV in 5 M LiFSI CME (\u003cstrong\u003ea-d\u003c/strong\u003e) and LPF10 (\u003cstrong\u003ee-h\u003c/strong\u003e). Schematics of interphases of lithiated SiNPs in 5 M LiFSI CME (\u003cstrong\u003ei\u003c/strong\u003e) and LPF10 (\u003cstrong\u003ej\u003c/strong\u003e). \u003cstrong\u003ek\u003c/strong\u003e 3D reconstructions of TOF-SIMS of the formed SiNPs SEI for the 5 M LiFSI CME (k1) and LPF10 (k2) electrolyte. The sputtered area is 50 µm× 50 µm. XPS spectra of F 1s and O 1s of the SEI on SiNPs anode after 50 cycles in 5 M LiFSI CME (\u003cstrong\u003el\u003c/strong\u003e) and LPF10 (\u003cstrong\u003em\u003c/strong\u003e). Atomic concentration at different etching times of the SEI formed in 5 M LiFSI CME (\u003cstrong\u003en\u003c/strong\u003e) and LPF10 (\u003cstrong\u003eo\u003c/strong\u003e).\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-3865538/v1/b90bafd131b7f7e8ed381842.png"},{"id":50053767,"identity":"d41d6a0e-6574-4a67-a176-294de042858e","added_by":"auto","created_at":"2024-01-23 17:12:24","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":739268,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eElectrochemical kinetics and wide temperature performance of SiNPs. \u003c/strong\u003eTemperature-dependent DRT analysis derived from EIS data for LPF10 (\u003cstrong\u003ea\u003c/strong\u003e) and 5 M LiFSI CME (\u003cstrong\u003eb\u003c/strong\u003e) electrolytes in lithiated Si (SOC=60%) symmetric cells. Corresponding Arrhenius curves and the calculated activation energies for R\u003csub\u003ect\u003c/sub\u003e (\u003cstrong\u003ec\u003c/strong\u003e) and R\u003csub\u003eSEI\u003c/sub\u003e (\u003cstrong\u003ed\u003c/strong\u003e) with LPF10 and 5 M LiFSI CME electrolytes. \u003cstrong\u003ee\u003c/strong\u003e Cycling performance of SiNPs anode using different electrolytes at various temperatures. \u003cstrong\u003ef\u003c/strong\u003e Long-term cycling capabilities and CEs of SiNPs anode in various electrolytes at 0.2 C (1 C = 3579 mA g\u003csup\u003e−1\u003c/sup\u003e). The temperature-dependent delithiation profiles of Li/Si half-cells with the LPF10 (\u003cstrong\u003eg\u003c/strong\u003e), 5 M LiFSI DME (\u003cstrong\u003eh\u003c/strong\u003e), and 5 M LiFSI CME (\u003cstrong\u003ei\u003c/strong\u003e) electrolytes. DRT data of Li/Si half-cells after 3, 20, 50, and 100 cycles with the LPF10 (\u003cstrong\u003ej\u003c/strong\u003e), 5 M LiFSI DME (\u003cstrong\u003ek\u003c/strong\u003e), and 5 M LiFSI CME (\u003cstrong\u003el\u003c/strong\u003e) electrolytes, respectively.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-3865538/v1/ae9c0a548aca13fb912762b4.png"},{"id":50053612,"identity":"4653b247-c121-450e-9ffa-7e65fc1c459b","added_by":"auto","created_at":"2024-01-23 17:04:24","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":21777363,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSpatial configuration evolution of SiNPs after long cycles. a \u003c/strong\u003eCross-sectional SEM images of pristine Si electrodes and cycled Si electrodes in different electrolytes. 3D AFM images (2 μm × 2 μm scan size) (\u003cstrong\u003eb\u003c/strong\u003e)\u003cstrong\u003e \u003c/strong\u003eand corresponding DMT modulus mappings (\u003cstrong\u003ec\u003c/strong\u003e) of Si electrodes after 50 cycles\u003cstrong\u003e \u003c/strong\u003ein\u003cstrong\u003e \u003c/strong\u003eLPF10 and 5 M LiFSI CME electrolytes.\u003cstrong\u003e \u003c/strong\u003eHR-TEM images\u003cstrong\u003e \u003c/strong\u003eof SiNPs after 50 cycles in\u003cstrong\u003e \u003c/strong\u003eLPF10 (\u003cstrong\u003ed-g)\u003c/strong\u003e and 5 M LiFSI CME (\u003cstrong\u003eh-j) \u003c/strong\u003eelectrolytes.\u003cstrong\u003e k \u003c/strong\u003eSchematic illustration of the morphology of SiNPs after 50 cycles in different electrolytes. ADF images and corresponding EDS mapping of SiNPs anodes after 50 cycles in\u003cstrong\u003e \u003c/strong\u003eLPF10 (\u003cstrong\u003el)\u003c/strong\u003e and 5 M LiFSI CME (\u003cstrong\u003em)\u003c/strong\u003eelectrolytes.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-3865538/v1/61e0917a0fc06779eb337709.png"},{"id":50053610,"identity":"4d936136-0f24-43c2-b45f-52197121402c","added_by":"auto","created_at":"2024-01-23 17:04:24","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":2742658,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eElectrochemical performance of SiNPs/SPAN and SiNPs/LFP full cells. \u003c/strong\u003eCycling performance of SiNPs/SPAN full cells using different electrolytes at 30 °C under 0.5 C (\u003cstrong\u003ea\u003c/strong\u003e), 60 °C under 1 C (\u003cstrong\u003eb\u003c/strong\u003e), and -20 °C under 0.3 C (\u003cstrong\u003ec\u003c/strong\u003e). Charge/discharge curves of Si/SPAN full cells at -20 °C with the LPF10 (\u003cstrong\u003ed\u003c/strong\u003e), 5 M LiFSI DME (\u003cstrong\u003ee\u003c/strong\u003e) electrolytes. \u003cstrong\u003ef\u003c/strong\u003e Cycling performance of SiNPs/NCM811 full cells at -20 °C withdifferent electrolytes. \u003cstrong\u003eg\u003c/strong\u003e Cycling behavior of SiNPs/LFP pouch cells at 30 °C with different electrolytes. \u003cstrong\u003eh\u003c/strong\u003e Comparison of the electrochemical performance of SiNPs-based anodes/LFP full cells with previous reports.\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-3865538/v1/98e7f8143623ffc02d8eb0bf.png"},{"id":51856344,"identity":"77963c31-bc8e-4733-a895-b1ff4904d6f4","added_by":"auto","created_at":"2024-03-01 11:44:02","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6870763,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3865538/v1/173dd162-fdce-40f4-b1e9-82b0e16e45ae.pdf"},{"id":50053615,"identity":"f85eb54a-a8e9-4522-9df3-cab6b40d12d9","added_by":"auto","created_at":"2024-01-23 17:04:48","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":367331069,"visible":true,"origin":"","legend":"\u003cp\u003eSupporting information\u003c/p\u003e","description":"","filename":"Supplementaryinformation3.docx","url":"https://assets-eu.researchsquare.com/files/rs-3865538/v1/a807149128ca05c0678a7d48.docx"},{"id":50053607,"identity":"d76b4493-14e7-4fe7-bf5e-7c9147ec02ac","added_by":"auto","created_at":"2024-01-23 17:04:24","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":1575588,"visible":true,"origin":"","legend":"\u003cp\u003eTOC\u003c/p\u003e","description":"","filename":"toc2.docx","url":"https://assets-eu.researchsquare.com/files/rs-3865538/v1/bb30f59a5554631c7d208f63.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Anionic aggregates induced interphase chemistry regulation toward wide-temperature silicon-based batteries","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe advancement and widespread adoption of electric vehicles and energy storage grids underscore the need for state-of-the-art lithium-ion batteries (LIBs) with high energy density and long lifespan, capable of withstanding the environmental temperatures in residential areas\u003csup\u003e\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. Silicon (Si) has emerged as a strong contender to replace conventional graphite anodes due to its ultrahigh theoretical capacity (3579 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for Li\u003csub\u003e15\u003c/sub\u003eSi\u003csub\u003e4\u003c/sub\u003e), relatively low lithiation potential (\u0026lt;\u0026thinsp;0.4 V vs Li/Li\u003csup\u003e+\u003c/sup\u003e), and abundant natural availability\u003csup\u003e\u003cspan additionalcitationids=\"CR6 CR7\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. Nevertheless, the practical application of Si anodes in commercial batteries is impeded by substantial volume expansion (300%-400%) during the alloy process with lithium\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e. The stress accumulation resulting from repeated expansion and contraction leads to the fracture and even pulverization of Si particles, causing the detachment of fragments from the current collector to create \u0026ldquo;dead Si\u0026rdquo;\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. This dramatic loss of active materials severely limits the lifespan of pure-Si anodes. Hence only a small amount (5\u0026ndash;15 wt%) of Si is typically blended with graphite anodes in industrial manufacturing to enhance the energy density of LIBs\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e. Nanosizing Si has been proven effective in mitigating mechanical failure, as evidence indicates that the rupture of Si particles is significantly alleviated when their size is below the critical diameter of 150 nm\u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. However, the fragile solid electrolyte interphase (SEI) formed by side reactions between the increased Si surface and electrolyte breaks down during volume swing. The electrolyte gradually penetrates along the nanovoids, triggering new SEI growth at the expense of active Li\u003csup\u003e+\u0026thinsp;15\u003c/sup\u003e. Over cycling, the SEI infiltrates into the agglomerated Si nanoparticles (SiNPs), resulting in large and inactive Si-SEI composites (\u0026ldquo;dead Si\u0026rdquo;)\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. The evolution of the spatial configuration of Si-SEI gradually disrupts the electron conduction pathways and contributes to the capacity loss of SiNPs-based batteries. Therefore, it is imperative to regulate the interphase chemistry of SiNPs to enhance the mechanical robustness of SEI.\u003c/p\u003e \u003cp\u003eElectrolyte engineering is recognized as a pivotal strategy for shaping the SEI chemistry and configuration by carefully selecting and modulating the electrolyte composition\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. In the realm of Si-based batteries, the incorporation of fluoroethylene carbonate (FEC) is indispensable due to its significant enhancement of cyclic performance\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. The resultant rigid SEI has proven to effectively mitigate cracking and delamination of the Si thin-film electrode\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. However, FEC is prone to decomposing and generating HF gas at high temperatures\u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e, causing not only the corrosion of Si bulk phase and cathode materials but also the expansion of cells \u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. Additionally, the recent application of localized high-concentration electrolytes (LHCEs) in Si anodes has gained traction due to their ability to form an inorganic-rich SEI derived from anion-dominated solvation structure\u003csup\u003e\u003cspan additionalcitationids=\"CR24\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e. However, this approach necessitates a substantial amount of expensive and environmentally unfriendly fluorinated diluents such as hydrofluoroether. It is worth noting that the inevitable fluctuations of environmental temperature require advanced battery systems to operate within a range of -20-60\u0026deg;C. Although fluorocarboxylic esters have allowed SiNPs to function at -20\u0026deg;C\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e, their practical application is hindered by low boiling points. Furthermore, low temperature results in sluggish Li\u003csup\u003e+\u003c/sup\u003e transport kinetics, while high temperature leads to more severe side reactions at the interface, posing significant challenges to the development of wide-temperature silicon-based batteries.\u003c/p\u003e \u003cp\u003eHerein, we present a novel environmentally friendly non-fluorinated solvent, cyclopentyl methyl ether (CME), which boasts several advantages including low density, a wide liquid phase range, and a moderate dielectric constant (see Supplementary Table\u0026nbsp;1). The cyclic group within its molecule creates significant steric hindrance, leading to a noteworthy reduction in the solvating energy between CME and Li\u003csup\u003e+\u003c/sup\u003e. This results in the formation of a solvation structure primarily characterized by ion clusters, particularly anionic aggregates (AGGs) as the concentration of lithium salt (lithiumbis(fluorosulfonyl)imide, LiFSI) increases. Furthermore, the electric field strengthens the coordination of the interface FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e with lithium, enabling rapid desolvation kinetics and the formation of anion-derived SEI. The application of cryogenic transmission electron microscopy (cryo-TEM) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) reveals a double-layer structure of the SEI, with uniformly dispersed internal nano-inorganic components and a fully covered external amorphous layer. This SEI exhibits a high Young's modulus, capable of withstanding stress accumulation resulting from volume changes, thereby safeguarding the Si particles against the formation of inactive Si-SEI composites after extended cycling. Consequently, the Si anode in the designed electrolyte can operate from \u0026minus;\u0026thinsp;20\u0026deg;C to 60\u0026deg;C, and the SiNPs/sulfurized polyacrylonitrile (SPAN) full cell in the 5 M LiFSI CME (or abbreviated as 5 M CME) electrolyte maintained an excellent capacity retention of 83.5% after 800 cycles at -20\u0026deg;C. More importantly, this straightforward strategy has successfully yielded an 80 mAh SiNPs-based pouch cell with a capacity retention of 85.6% after 150 cycles, marking a significant step forward in the practical application of silicon anode.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003eSolvent selection and solvation structure of electrolytes\u003c/h2\u003e\n\u003cp\u003eIn response to temperature variations, the selection of solvents is guided by three main criteria\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e: 1) The solvent should have a wide liquid phase range. 2) It should possess a gentle solvating ability to meet low desolvation energy requirements and a moderate dielectric constant for dissociating ionic salt. 3) It should have an appropriate electrochemical window for Si-based batteries. Among the commonly used ester and ether solvents (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ea and Supplementary Table\u0026nbsp;1), CME stands out due to its high boiling point (106\u0026deg;C) and low melting point (-140\u0026deg;C), providing it a relatively wide liquid phase range to accommodate temperature fluctuations. Differential scanning calorimetry (DSC, Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eb) analysis also indicates that the LiFSI-CME system remains in a liquid state within the temperature range of -90 to 90\u0026deg;C, while the LiFSI-DME system liquefies at around \u0026minus;\u0026thinsp;70\u0026deg;C. Additionally, the commercial carbonate electrolyte, 1 M lithium hexafluorophosphate (LiPF\u003csub\u003e6\u003c/sub\u003e) in ethylene carbonate (EC)/diethyl carbonate (DEC)/FEC (4.5:4.5:1 by volume) (denoted as LPF10), displays a distinct endothermic peak around 0\u0026deg;C and undergoes thermal decomposition around 70\u0026deg;C due to the poor thermal stability of LiPF\u003csub\u003e6\u003c/sub\u003e. These findings are consistent with the observations from optical images at low temperatures (Supplementary Fig.\u0026nbsp;1).\u003c/p\u003e\n\u003cp\u003eThe electrostatic potential (ESP) mapping reveals that the O position in the ether bond carries a negative charge density, which tends to bond with Li\u003csup\u003e+\u003c/sup\u003e. In comparison to DME, the CME molecule has one less oxygen, and the large steric hindrance of the five-membered ring on the edge leads to a significant reduction in electron density on the O atom, and consequently, weaker Li\u003csup\u003e+\u003c/sup\u003e coordination ability (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ed). Furthermore, we calculated the solvation ability between Li\u003csup\u003e+\u003c/sup\u003e and various solvents (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ec and Supplementary Fig.\u0026nbsp;2) through density functional theory (DFT) and found that the energy of solvation follows the order CME (190 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u0026thinsp;\u0026lt;\u0026thinsp;THF (191 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u0026thinsp;\u0026lt;\u0026thinsp;MeTHF (200 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u0026thinsp;\u0026lt;\u0026thinsp;DME (269 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). This suggests that the interaction between Li\u003csup\u003e+\u003c/sup\u003e and CME is relatively weak, facilitating the solvation structure alterations and a rapid desolvation process. This result is consistent with nuclear magnetic resonance (NMR, Supplementary Fig.\u0026nbsp;3). At the same concentration, the DME systems are more upfield-shifted than CME systems, indicating that DME provides more electron density to shield Li\u003csup\u003e+\u0026thinsp;28\u003c/sup\u003e. Moreover, the dielectric constant of CME is 4.7, and it has a high solubility of LiFSI (7 M)\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e, supporting its suitability as an electrolyte solvent.\u003c/p\u003e\n\u003cp\u003eAfter dissolving LiFSI into CME and DME with different concentrations, the coordination of Li\u003csup\u003e+\u003c/sup\u003e-FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e/-solvent was demonstrated by Raman spectra (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ee). The vibrational bond at 895 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e represents the CME solvent molecule, while the peaks at 820 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 850 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are assigned to the stretching vibration of CH\u003csub\u003e2\u003c/sub\u003e─O─CH\u003csub\u003e3\u003c/sub\u003e of the DME solvent molecule\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. With an increase in salt concentration, the corresponding peaks of the free solvent molecules were profoundly weakened. An additional peak at 873 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, resulting from the blue shift of pure DME is attributed to the Li\u003csup\u003e+\u003c/sup\u003e-coordinated DME\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e, indicating a strong interaction between DME and Li\u003csup\u003e+\u003c/sup\u003e. The bonds in the range of 700\u0026ndash;775 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e correspond to the stretching/vibration of the S-N-S in FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e anions\u003csup\u003e30\u003c/sup\u003e. In comparison to DME, the FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e in the CME electrolyte exhibits a smaller red shift relative to the crystalline LiFSI (775 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), representing a weaker coordination ability. Specifically, the coordination environment of FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e can be decoupled into free ions (720 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), contact ion pair (CIP, FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e coordinating to one Li\u003csup\u003e+\u003c/sup\u003e, 731 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), ion-pair aggregate (AGG, FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e coordinating to two Li\u003csup\u003e+\u003c/sup\u003e, 745 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), and nanometric aggregates (n-AGG, FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e coordinating to three or more Li\u003csup\u003e+\u003c/sup\u003e, 756 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003csup\u003e31,32\u003c/sup\u003e as shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ef and Supplementary Fig.\u0026nbsp;4. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eg, despite the salt concentration reaching 5 M, there is still approximately 5% free FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e in DME, indicating that the strong solvation of DME prevents some FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e from entering the first Li\u003csup\u003e+\u003c/sup\u003e solvation shell. In contrast, in CME, the FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e exist almost entirely in the form of AGG and n-AGG. When the concentration exceeds 5 M, n-AGG predominates, meaning the FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e are strongly interconnected through the intensive association with Li\u003csup\u003e+\u003c/sup\u003e, forming an enhanced three-dimensional network\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e. This is beneficial for widening the voltage window due to the suppression of free-solvent decomposition (Supplementary Fig.\u0026nbsp;5)\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. However, at excessively high concentrations, such as 7 M, it leads to excessively high viscosity, a decrease in Li\u003csup\u003e+\u003c/sup\u003e conductivity, and an increase in polarization, resulting in dendrite formation during silicon lithiation (Supplementary Fig.\u0026nbsp;6). Therefore, based on the half-cell performance in Supplementary Fig.\u0026nbsp;7, the concentration of 5 M is selected for further study.\u003c/p\u003e\n\u003cp\u003eThe solvation structures of Li\u003csup\u003e+\u003c/sup\u003e in three electrolytes (LPF10, 5 M LiFSI DME, and 5 M LiFSI CME) from \u0026minus;\u0026thinsp;30 to 60\u0026deg;C were further analyzed using molecular dynamics (MD) simulations in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eh-k and Supplementary Figs.\u0026nbsp;8\u0026ndash;10. According to the radial distribution functions (RDFs) and coordination number distribution functions (CNDFs), the first solvation radius for each solvent is ~\u0026thinsp;3 \u0026Aring;. In LPF10, EC is the dominant solvent in the first Li\u003csup\u003e+\u003c/sup\u003e solvation shell, with a CN of 3.42 at 30\u0026deg;C, followed by linear carbonate DEC (1.79) and PF\u003csub\u003e6\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e (0.56). Notably, more EC was coordinated with Li\u003csup\u003e+\u003c/sup\u003e upon decreasing the temperature, as identified by the increased CN for EC (3.61 at -30\u0026deg;C) and the decreased CN of DEC and PF\u003csub\u003e6\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e. However, when the temperature rose to 60\u0026deg;C, the CN of EC decreased to 3.20, followed by the enhancement of PF\u003csub\u003e6\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e (0.78). This solvation structure variation has, on the one hand, increased the difficulty of low-temperature desolvation due to the strong polarity of EC. On the other hand, it has reduced the stability of the electrolyte at high temperatures, thus hindering the application of LPF10 at both high and low temperatures. In contrast, the solvation structures of 5M LiFSI DME and CME do not change significantly at different temperatures, which further verifies their temperature compatibility. More specifically, the electrolyte of 5 M LiFSI CME shows strong interaction between FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e and Li\u003csup\u003e+\u003c/sup\u003e, with a CN of 3.66, while the CN is only 2.86 in 5 M LiFSI DME, further indicating the weak solvation behavior of CME. Different from DME, the CN of Li\u003csup\u003e+\u003c/sup\u003e-CME is only 0.93, which means the presence of numerous AGG and n-AGG structures (nano-clusters) to form three-dimensional ion-rich networks\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e within the free CME solvent molecules (Supplementary Fig.\u0026nbsp;11).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n\u003ch2\u003eAnionic aggregates at the electrified interface\u003c/h2\u003e\n\u003cp\u003eAlthough studies have shown that anion-dominated solvation structure facilitates the formation of inorganic-rich interphase\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e, the reaction behavior of n-AGG at the interface have not been thoroughly revealed. Therefore, interfacial MD simulations incorporating an external electric field were conducted to elucidate the ion distributions, solvation structures, and their effects on interfacial reactions. The snapshots are displayed in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea and Supplementary Fig.\u0026nbsp;12. A constant electric field (100 mV nm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003csup\u003e36\u0026ndash;38\u003c/sup\u003e was applied in the direction perpendicular to the silicon plane to investigate the changes in the interfacial nanostructure. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb exhibits the number density profiles of Li\u003csup\u003e+\u003c/sup\u003e, FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e anions and CME molecules as a function of distance from Si anode without/with applied electric field. In the inner Helmholtz layer (0.36 nm) which tightly contacts with the electrode, some CME solvent molecules exist due to the hydrogen bonding of the hydroxyl groups on the silicon surface, while in the outer Helmholtz layer (0.36-0.55nm), there is the solvation structure of lithium ions\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. After applying the external electric field, the height of the first sharp peak of Li\u003csup\u003e+\u003c/sup\u003e increases rapidly, which suggests that electric field promote the Li\u003csup\u003e+\u003c/sup\u003e migration toward the negatively charged Si anode. Meanwhile, a large amount of FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e are involved to approach the interface due to the strong cohesive cation-anion association, resulting in an accumulation of anions at the interface (Supplementary Fig.\u0026nbsp;12). In contrast, the number of CME molecules in the outer Helmholtz layer is significantly reduced, which indicates that CME has partially desolvated from Li\u003csup\u003e+\u003c/sup\u003e solvation shell due to its weak solvation ability while more FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e has been incorporated into the solvation structure (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec). Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ed further demonstrates the changes in the solvation structure at the electrified interface, where the CN of FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e in first Li\u003csup\u003e+\u003c/sup\u003e solvation shell increases with the reduced CN of CME. Abundant coordinated FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e (n-AGG) have high priority to decompose at negatively charged Si anode, leading to the formation of an inorganic-rich SEI. It is worth noting that FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e tends to move away from the interface under the applied electric field in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb, as the farther approach of the anions to the negatively charged silicon, the greater electrostatic repulsion between them\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e, indicating the reason why FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e is easy to desolvate under the external electric field.\u003c/p\u003e\n\u003cp\u003eIn order to illustrate the influence of different electrolytes on the SEI reaction, the lowest unoccupied molecular orbital (LUMO) energies of different molecules and clusters were calculated to elucidate their sequence of decomposition at the Si anode (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ef) and validated by the first cyclic voltammetry (CV) curves (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ee). The LUMO energies of free solvent molecules EC, DEC, FEC, DME, and CME are \u0026minus;\u0026thinsp;0.45, -0.098, -0.941, 1.116, and 0.913 eV, respectively, indicating that the reduction stability of ethers is higher than that of esters. In LPF10, due to the large distribution of free solvents at the electrode interface, FEC and EC are thermodynamically favorable for decomposition, corresponding to the decomposition peaks at 1.47 V and 1.16 V in CV curves\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e\u003c/sup\u003e, respectively. When cooperated with Li\u003csup\u003e+\u003c/sup\u003e, the LUMO energies of solvents decrease because of the electron deficiency nature of Li\u003csup\u003e+\u0026thinsp;41\u003c/sup\u003e. When introducing anions into the Li\u003csup\u003e+\u003c/sup\u003e solvation sheath, on the one hand, the LUMO energies of FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e in Li\u003csup\u003e+\u003c/sup\u003e-solvent-FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e complexes decline compared to that of free anions. On the other hand, FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e shoulder the burden of electron-withdrawing effects from solvents, resulting in an increased LUMO energy of the solvent in Li\u003csup\u003e+\u003c/sup\u003e-solvent-FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e complex compared to Li\u003csup\u003e+\u003c/sup\u003e\u0026ndash;solvent. These phenomena suggest that the reductive stability of solvents/anions can be reduced when they connected with Li\u003csup\u003e+\u0026thinsp;42\u003c/sup\u003e. In three types of ether electrolytes (5 M LiFSI DME, 1 M LiFSI CME, and 5 M LiFSI CME), the reduction stability reduces in sequence since the proportion of n-AGG in the solvation structure (i.e., the strong association between Li\u003csup\u003e+\u003c/sup\u003e and FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e) grows successively. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ee shows that the reduction potentials of 5 M LiFSI DME, 1 M LiFSI CME, and 5 M LiFSI CME are 1.13, 1.22, and 1.28 V, respectively, which is consistent with the DFT results.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n\u003ch2\u003eSEI properties determined by interfacial solvation structure\u003c/h2\u003e\n\u003cp\u003eThe properties of SEI including its composition and nanostructure, are revealed by various characterization techniques at different spatial scales such as cryo-TEM, TOF-SIMS, and X-ray photoelectron spectroscopy (XPS). In order to illustrate the initial formation state and long-term evolution of SEI, we characterized the first lithiation/delithiation Si anode and the SEI after 50 cycles, respectively. Cryo-TEM images show that the Li\u003csub\u003e5\u003c/sub\u003eSi\u003csub\u003e4\u003c/sub\u003e crystals are formed to distinguish the SEI and bulk-phase components when Si is fully lithiated to 10 mV\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. In 5 M LiFSI CME electrolyte, the Li\u003csub\u003e5\u003c/sub\u003eSi\u003csub\u003e4\u003c/sub\u003e crystal structure is completely wrapped by a uniform SEI with a thickness of 35\u0026ndash;40 nm (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ea, c). The surface SEI exhibits a typical bilayer structure with inorganic nanocrystals evenly dispersed on the inner side and covered by outer amorphous organic species. Fast Fourier transform (FFT, Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb) and local magnified images (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ed and Supplementary Fig.\u0026nbsp;13) reveal detailed information about its components, including Li\u003csub\u003e2\u003c/sub\u003eO (111), LiF (111), and Li\u003csub\u003e2\u003c/sub\u003eS (311) lattice planes that originate from the interfacial LiFSI decomposition. However, in LPF10 (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ee), no obvious SEI components have been found on the crystalline Li\u003csub\u003e5\u003c/sub\u003eSi\u003csub\u003e4\u003c/sub\u003e particle surface (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eg), but spherical LiF particles with a diameter of approximately 45\u0026ndash;100 nm have been observed (Supplementary Fig.\u0026nbsp;14). FFT (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ef) and local magnified images (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eh) further exhibit lattice fringes with an interplanar spacing of 0.201 nm, which belongs to the LiF (200) plane. This phenomenon indicates that a single LiF precipitates in the form of particles from the decomposition of FEC in the LPF10 system, which is consistent with previous studies\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e\u003c/sup\u003e, possibly due to the high interfacial energy of LiF itself. The schematics of interphases of lithiated SiNPs in 5 M LiFSI CME and LPF10 are illustrated in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ei-j, respectively.\u003c/p\u003e\n\u003cp\u003eThe composition of SEI over a wide range was verified using TOF-SIMS, as shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ek and Supplementary Fig.\u0026nbsp;15. After lithiation to 10 mV in the 5 M LiFSI CME electrolyte, ultra-thin organic fragments C\u003csub\u003e2\u003c/sub\u003eHO\u003csup\u003e\u0026minus;\u003c/sup\u003e concentrates at the outermost layer of SEI (corresponding to the amorphous structure in the cryo-TEM), while inorganic components Li\u003csub\u003e2\u003c/sub\u003eO and LiF make up the inner layer of SEI. In addition, the SEI fragment signals disappear after sputtering for 600s, indicating its uniform distribution on the silicon surface. In contrast, the signal of LiF\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e in LPF10 penetrates the entire sputtering process, while the signals of Li\u003csub\u003e2\u003c/sub\u003eO\u003csup\u003e\u0026minus;\u003c/sup\u003e and C\u003csub\u003e2\u003c/sub\u003eHO\u003csup\u003e\u0026minus;\u003c/sup\u003e are very weak. This is consistent with the results of cryo-TEM, namely that LiF large particles precipitate in the pores of silicon anode. Many studies have demonstrated that LiF exhibits electronic insulating properties, a low Li\u003csup\u003e+\u003c/sup\u003e diffusion barrier, and a high elastic modulus\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. However, the effectiveness of LiF in large particle form is limited, and only its uniform dispersion on the surface can protect silicon anode from volume swing.\u003c/p\u003e\n\u003cp\u003eThe SiNPs are amorphized while delithiated to 1 V, as shown in the cryo-TEM image and its FFT in Supplementary Fig.\u0026nbsp;16. In the 5 M LiFSI CME electrolyte, part of the Li\u003csub\u003e2\u003c/sub\u003eO in the SEI reacts with silicon to form Li\u003csub\u003ex\u003c/sub\u003eSiO\u003csub\u003ey\u003c/sub\u003e\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e, where the elastic Li\u003csub\u003e4\u003c/sub\u003eSiO\u003csub\u003e4\u003c/sub\u003e layer is proven to be beneficial for the integrity of the Si electrode\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e. In LPF10, LiF remains stable during lithium removal and still stacks in a granular form, where the presence of some Li\u003csub\u003e5\u003c/sub\u003eSi\u003csub\u003e4\u003c/sub\u003e indicates slow Li\u003csup\u003e+\u003c/sup\u003e transportation. In addition, XPS was employed to analyze the SEI on the silicon anodes after 50 cycles in delithiation state. In LPF10, a large amount of C-O, C\u0026thinsp;=\u0026thinsp;O, and O-C\u0026thinsp;=\u0026thinsp;O components originating from the decomposition of solvents were observed in the C1s spectrum\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e (Supplementary Fig.\u0026nbsp;17) and O1s spectrum (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003em), indicating that the initially incomplete coverage SEI of the active silicon anode continues to undergo side reactions with the electrolyte. Despite the subsequent formation of a LiF-rich SEI (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003em, o), a significant amount of Li\u003csup\u003e+\u003c/sup\u003e are consumed during the SEI reconstruction process, leading to rapid initial decay of the Li/Si half-cell in LPF10. Furthermore, the decomposition of FEC results in the incorporation of LiF into the interior of the silicon nanoparticles during cycling\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e, which causes some damage to the integrity of the silicon particles. In the 5 M LiFSI CME electrolyte, the bilayer SEI remains stable during cycling. The outer layer of the SEI contains a high content of Li\u003csub\u003ex\u003c/sub\u003eSiO\u003csub\u003ey\u003c/sub\u003e and a small amount of organic components, while the inner layer consists of LiF and Li\u003csub\u003e2\u003c/sub\u003eS inorganic components (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003el, n and Supplementary Fig.\u0026nbsp;17). This rigid and flexible SEI, composed of dispersed LiF nanoclusters embedded amorphous Li\u003csub\u003ex\u003c/sub\u003eSiO\u003csub\u003ey\u003c/sub\u003e and organic materials, can withstand the stress accumulation from volume changes and does not undergo fragmentation during long cycling. For 5 M LiFSI DME, the SEI components are similar to those in 5 M LiFSI CME due to the decomposition of solvated FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e (Supplementary Figs.\u0026nbsp;18\u0026ndash;19). However, there are more FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e decomposition intermediates S\u003csub\u003en\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e and -SO\u003csub\u003e2\u003c/sub\u003e- in its SEI since less FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e present in the form of n-AGG in the 5 M LiFSI DME electrolyte\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e, which indicates that the anion continues to decompose with incomplete passivation protection of the silicon surface.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n\u003ch2\u003eImprovement of electrochemical kinetics\u003c/h2\u003e\n\u003cp\u003eThe sluggish transport kinetics inhibit the performance of SiNPs anode at low temperatures. Among the three kinetic processes of Li\u003csup\u003e+\u003c/sup\u003e migration in bulk electrolyte, desolvation, and diffusion through the SEI layer, the latter two are generally considered as the rate-determining steps\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e49\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e. Due to the heterogeneous solvation structure of the 5 M LiFSI CME, the migration of Li\u003csup\u003e+\u003c/sup\u003e no longer follows the Stokes-Einstein law, but rather moves in a hopping manner through Lewis basic sites from one anion to another\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. This results in a higher ion transfer number (\u003cem\u003et\u003c/em\u003e\u003csub\u003e\u003cem\u003e+\u003c/em\u003e\u003c/sub\u003e) of 0.50 for the 5 M LiFSI CME electrolyte compared to 0.35 for the LPF10 (Supplementary Fig.\u0026nbsp;21), despite its lower ion conductivity originated from low dielectric constant of CME and high viscosity at room temperature (Supplementary Fig.\u0026nbsp;20). When the temperature falls to -20\u0026deg;C, the ion conductivity of LPF10 drops sharply due to its solidification.\u003c/p\u003e\n\u003cp\u003eTo unravel the difference of Li\u003csup\u003e+\u003c/sup\u003e transport property between the interface in two electrolytes, temperature-dependent electrochemical impedance spectroscopy (EIS) and the distribution relaxation time (DRT) analysis were conducted (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ea-b and Supplementary Fig.\u0026nbsp;22). The DRT analysis classified different electrochemical processes based on local maxima in the continuous distribution function\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e51\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e\u003c/sup\u003e, including ohmic resistance (R\u003csub\u003eb\u003c/sub\u003e), SEI layer resistance (R\u003csub\u003eSEI\u003c/sub\u003e), and charge transfer resistance (R\u003csub\u003ect\u003c/sub\u003e). The solvated Li\u003csup\u003e+\u003c/sup\u003e from electrolyte to reach the silicon surface need to overcome two energy barriers: the desolvation activation energy (E\u003csub\u003ea1\u003c/sub\u003e) and the energy for crossing the SEI (E\u003csub\u003ea2\u003c/sub\u003e), which can be obtained through the Arrhenius equation from R\u003csub\u003ect\u003c/sub\u003e and R\u003csub\u003eSEI\u003c/sub\u003e respectively\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e49\u003c/span\u003e\u003c/sup\u003e. To eliminate the influence of lithium metal, symmetrical lithiated Si cells were assembled at 60% state of charge after cycling three times with the corresponding electrolytes. The R\u003csub\u003ect\u003c/sub\u003e of the LPF10 electrolyte significantly increased from 30\u0026deg;C to -20\u0026deg;C, with the E\u003csub\u003ea1\u003c/sub\u003e value reaching 71.08 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, far greater than that of 5 M LiFSI CME (42.57 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ec). This is consistent with the previous analysis about desolvation energy and the interfacial solvation structure. In addition, the double-layer SEI formed in 5 M LiFSI CME exhibited a value of E\u003csub\u003ea2\u003c/sub\u003e (52.38 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), also lower than the SEI formed in LPF10 (58.56 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ed). The decreased E\u003csub\u003ea2\u003c/sub\u003e implies that the SEI in 5 M LiFSI CME has high Li\u003csup\u003e+\u003c/sup\u003e conductivity, stemming from uniformly embedded inorganic nano-structures in the amorphous components and abundant grain boundaries favorable for ion transport within the SEI.\u003c/p\u003e\n\u003cp\u003eThe rapid kinetic process is conducive to the low-temperature capacity release. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ee shows the low-temperature application potential of different electrolytes in Li/SiNPs half-cells. After activating the battery for three cycles at 0.05 C under 30\u0026deg;C, capacity tests at different temperatures were carried out at 0.1 C. The initially reversible (charge) specific capacities of the half-cell in LPF10, 5 M LiFSI DME, and 5 M LiFSI CME were 2949, 3859.2, and 3408.8 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, corresponding to their initial coulombic efficiencies (ICE) of 89.92%, 91.97%, and 91.2%, respectively. Although the initial capacity of DME is higher, its rapid capacity attenuation suggests the poor passivation ability of SEI. When the temperature drops to -10\u0026deg;C or even \u0026minus;\u0026thinsp;20\u0026deg;C, the capacity of SiNPs electrode in LPF10 is only 1010.4 and 0 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eg), because of the high melting point of EC and its strong binding energy with Li\u003csup\u003e+\u003c/sup\u003e. Although the electrolyte 5 M LiFSI DME remains liquid at -20\u0026deg;C, SiNPs in it can only release the capacity of 188 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eh). In contrast, SiNPs in the 5 M LiFSI CME electrolyte can still release a delithiation capacity of 941 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at -20\u0026deg;C (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ei), and when the temperature rises to 20\u0026deg;C, the capacity rapidly increases to 2844.4 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, demonstrating its ability to withstand temperature fluctuations. In addition, the silicon electrode exhibited the best rate performance in the 5 M LiFSI CME (Supplementary Fig.\u0026nbsp;24), with a capacity of 1014.5 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e even at a high current rate of 5 C, far exceeding that of 5 M LiFSI DME (608.8 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and LPF10 (457.8 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e).\u003c/p\u003e\n\u003cp\u003eFigure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ef shows the long-term cycling performance of the Li/Si half-cell in different electrolytes, where it maintained 80.8% capacity retention after 200 cycles in 5 M LiFSI CME, with an average CE of 99.52%, fully demonstrating the structural stability of the SiNPs in this electrolyte. In contrast, the SiNPs anode exhibited a drastic capacity decay after 120 cycles in LPF10, while only 17.7% capacity retention after 200 cycles in 5 M LiFSI DME. The initial capacity increase in the first 20 cycles in 5 M LiFSI CME can be attributed to the slow electrochemical activation process of the silicon anode in this viscous electrolyte. Subsequently, the SiNPs anodes are subjected to more severe 1 C long-term cycling conditions (Supplementary Fig.\u0026nbsp;25). The battery in 5 M LiFSI CME exhibited a high capacity retention of 97.2% after 200 cycles, with a remaining capacity of 1296.4 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. In comparison, the capacity retention of the SiNPs anode in LPF10 and 5 M LiFSI DME were only 38% and 30%, respectively. High temperature strengthens the parasitic reaction between the SiNPs anode and the electrolytes (Supplementary Fig.\u0026nbsp;26). The short circuit of LPF10 after 25 cycles possibly due to increased polarization and lithium dendrites formation sourced from electrolyte consumption, while the rapid capacity decay of 5 M LiFSI DME is due to the loose SEI on SiNPs surface. In contrast, 5 M LiFSI CME still maintains 81% of its capacity after 100 cycles which confirms the robustness of the bilayer SEI.\u003c/p\u003e\n\u003cp\u003eIn order to reveal the evolution of interface impedance in the long cycle process, EIS testing (Supplementary Fig.\u0026nbsp;27) and DRT analysis of Li/SiNPs half-cells were carried out in different electrolytes. According to the literature, the time constant (\u0026tau;) for lithium ions to pass through SEI is between 10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e and 10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e s, and the charge transfer is between 10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e and 10 s\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ej-l, with the progress of the cycles, the interfacial impedance including R\u003csub\u003eSEI\u003c/sub\u003e and R\u003csub\u003ect\u003c/sub\u003e gradually increases. The increase ratio of LPF10 is the highest, while the impedance of 5 M LiFSI CME remains almost unchanged after 100 cycles. It further illustrates that the designed electrolyte 5 M LiFSI CME can construct a highly stable SEI on the surface of SiNPs, which can fully encapsulate the silicon and prevent electrolyte corrosion during long cycles.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n\u003ch2\u003eSuppression of spatial configuration evolution\u003c/h2\u003e\n\u003cp\u003eScanning electron microscopy (SEM) was conducted to investigate the morphology and thickness evolution of the SiNPs anode after 50 cycles. In Supplementary Fig.\u0026nbsp;28, the SiNPs anode in LPF10 electrolyte experienced severe cracking, while the enlarged image shows that surface of SiNPs underwent pulverization after long-term expansion and contraction. In 5 M LiFSI DME, the fissures were smaller compared to LPF10 electrolyte, but still more pronounced than that of 5 M LiFSI CME. The SiNPs after 50 cycles in 5 M LiFSI CME electrolyte still exhibited an intact structure, indicating that the encapsulated SEI has a good protective effect on the integrity of the SiNPs anode. In addition, cross-sectional images are presented to explore the thickness expansion of SiNPs electrodes before and after cycling in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea. Compared to the initial thickness of silicon electrode (37 \u0026micro;m), the thicknesses of SiNPs anode after 50 cycles increased by 89%, 51%, and 35% in LPF10, 5 M LiFSI DME, and 5 M LiFSI CME electrolytes, respectively. The significant electrode volume expansion is partly due to the poor mechanical strength of the LPF10-drived SEI and also the extensive pulverization and loosening of internal SiNPs. The elastic SEI formed in 5 M LiFSI CME can resist internal stress from volume changes, thereby protecting the structure of SiNPs.\u003c/p\u003e\n\u003cp\u003eAtomic force microscopy (AFM) was performed to further investigate the mechanical properties of the SEI formed in different electrolytes. As shown in the 3D electrode mapping in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eb, the SiNPs anode in LPF10 exhibits significant expansion and abruption morphology after 50 cycles, with an average roughness of 93.4 nm. In comparison, the SiNPs anode cycled in 5 M LiFSI CME electrolyte shows a more uniform surface morphology, with an average roughness of only 40.3 nm. Furthermore, the Derjaguin-Muller-Toporov (DMT) modulus mapping (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ec) further demonstrates that the SEI produced by 5 M LiFSI CME has a higher modulus value (3.35 Gpa) compared to the SEI of LPF10 (2.13 Gpa). The modulus distribution of the SEI produced by LPF10 is unhomogeneous, and low modulus areas are damaged after stress accumulation, leading to particle pulverization and electrode fractures. Additionally, through corresponding 2D adhesion mapping analysis (Supplementary Fig.\u0026nbsp;29), strong adhesion is observed at the fracture site of the electrode cycled in LPF10, which would lead to continuous electrolyte penetration and subsequent side reactions. Differently, the SEI derived from 5 M LiFSI CME has uniform modulus and adhesion distributions, which are beneficial for the long-term structure stability and excellent electrochemical performance of the SiNPs anode.\u003c/p\u003e\n\u003cp\u003eThe microstructural changes of the silicon anode were examined using high-resolution transmission electron microscopy (HR-TEM). As depicted in Supplementary Fig.\u0026nbsp;30, the pristine SiNPs were initially spherical, with a diameter of around 100 nm and a 2.3 nm amorphous SiO\u003csub\u003e2\u003c/sub\u003e layer on the surface. Upon undergoing 50 cycles in LPF10 electrolyte, the SiNPs underwent deformation and agglomeration, forming blocks several hundred nanometers in size\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ed). A magnified image (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ee) revealed that the surface SEI with low contrast had ruptured, primarily due to its poor mechanical properties. These observations were further supported by the selected area electron diffraction (SAED, Supplementary Fig.\u0026nbsp;31) and lattice fringes in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eg, which indicates that the SEI framework (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ef) primarily consisted of dispersed LiF nanoclusters. This suggests that the initial LiF particles gradually adhered to the silicon surface and doped it during the cycling process. Moreover, the annular dark field (ADF) image in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003el and the corresponding energy dispersive spectrum (EDS) mapping demonstrated the presence of the F element inside the agglomerated silicon, representing inward permeation of the SEI, consistent with previous reports\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. The original spherical SiNPs transformed into a fibrous shape. This phenomenon illustrates the pulverized SiNPs-SEI composite as illustrated in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ek and exposes the failure mechanism of the SiNPs anode. Conversely, in the 5 M LiFSI CME electrolyte, the SiNPs remained dispersed and spherical after long cycles (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eh). The magnified image (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ei-j) revealed the presence of an intact wrapped SEI on the SiNPs surface with approximately 44 nm. EDS mapping (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003em) showed that the elements O, F, S, and N in the SEI were uniformly distributed on its particle surface, consistent with XPS results. Similar phenomena were observed on other particles as well (Supplementary Fig.\u0026nbsp;31). In the 5 M LiFSI DME electrolyte (Supplementary Fig.\u0026nbsp;32), a small amount of particle agglomeration and a thicker SEI (46-55nm) were observed, which was identified as the primary reason for its poor electrochemical performance.\u003c/p\u003e\n\u003cdiv id=\"Sec8\" class=\"Section3\"\u003e\n\u003ch2\u003eElectrochemical performance of SiNP-based full cells\u003c/h2\u003e\n\u003cp\u003eThe practical application potential of the electrolyte in wide-temperature SiNPs-based batteries was verified through the use of SPAN and lithium iron phosphate (LFP) as cathodes to prepare full cells. Notably, the SPAN cathode does not contain any lithium inventory, thus the SiNPs anode was pre-lithiated in half-cells with corresponding electrolytes and then reassembled into SiNPs/SPAN full cells. On the other hand, pre-cycling or pre-lithiation operations were not conducted on the SiNPs anodes for SiNPs/LFP cells. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ea depicts the excellent cyclic stability of SiNPs/SPAN in the 5 M LiFSI CME electrolyte at 30\u0026deg;C, demonstrating a capacity retention of 90% after 400 cycles. In contrast, the polarization of the full cells in LPF10 and 5 M LiFSI DME significantly increased after 100 cycles (Supplementary Fig.\u0026nbsp;33). Furthermore, at a high temperature of 60\u0026deg;C (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eb and Supplementary Fig.\u0026nbsp;34), the SiNPs/SPAN battery in the 5 M LiFSI CME electrolyte exhibits a capacity retention of 80.8% for 140 cycles and an average CE of 99.95%, surpassing that of 5 M LiFSI DME (99.78%) and LPF10 (99.34%), thus reflecting that the robust and stable SEI on SiNPs anodes can suppress side reactions from the electrolyte at high temperatures. Encouragingly, the SiNPs/SPAN full cell in the 5 M LiFSI CME electrolyte maintained a capacity retention of 83.5% after 800 cycles at -20\u0026deg;C (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ec). The voltage-capacity profiles indicate the release of a specific capacity of 938.6 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 0.3 C (1 C\u0026thinsp;=\u0026thinsp;1675 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e according to SPAN) at the 4th cycle, while cells in 5 M LiFSI DME and LPF10 electrolytes can only release capacities of 800.8 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 755.4 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ed-e and Supplementary Fig.\u0026nbsp;35). The enhanced electrochemical performance is attributed to the solvation structure of the anion aggregation at the interface and its rapid interfacial ion transport kinetics in the 5 M LiFSI CME electrolyte system. Likewise, this electrolyte is also compatible with LiNi\u003csub\u003e0.8\u003c/sub\u003eCo\u003csub\u003e0.1\u003c/sub\u003eMn\u003csub\u003e0.1\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e (NCM811) cathode (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ef), releasing a capacity of over 60 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at -20\u0026deg;C in the SiNPs/NCM811 full cell and maintaining stability for 200 cycles, while cells in other electrolytes struggle to work.\u003c/p\u003e\n\u003cp\u003eIn addition, LFP cathodes with different loading are used to match the silicon anode in Supplementary Fig.\u0026nbsp;36 to illustrate the salient merits of the designed electrolyte because high loading exacerbates thickness swelling and lengthens the transmission path of Li\u003csup\u003e+\u003c/sup\u003e. When the designed capacity is 0.5 mAh cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, the capacity retention of the SiNPs/LFP coin cell is 82.1% after 300 cycles in 5 M LiFSI CME electrolyte. When the designed capacities is increased to 1 mAh cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e and 1.5 mAh cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, the capacity retention is 92% (120 cycles) and 77% (100 cycles), respectively, while the capacity deteriorates quickly in LPF10. Finally, we assembled a double-layer pouch cell (80 mAh, 8.7 \u0026times;4.5 cm\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eg) assembled with SiNPs anode and LFP cathode with limited electrolyte (electrolyte/cathode, E/C\u0026thinsp;=\u0026thinsp;3g Ah\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), which is rarely reported in pure Si-based batteries. The pouch cell demonstrates excellent cycling performance, with a capacity retention of 85.6% after 150 cycles. Compared to previous reports on SiNPs-LFP full cell configurations, as shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eh and Supplementary Table\u0026nbsp;3, the electrochemical performance of our SiNPs/LFP full cells has a strong competitive advantage. If the graphite anode in the existing commercial LFP batteries is replaced with the SiNPs anode, we speculate that its gravimetric energy density can be increased by 20% (Supplementary Table\u0026nbsp;2). This work makes a significant step toward the practical application of Si anode and demonstrates the potential for future commercialization in high energy density LIBs.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this work, we present an electrolyte solvation engineering to overcome several challenges associated with SiNPs anode, including fragile SEI, low-temperature kinetics, and high-temperature parasitic reactions. We found that an electrolyte based on CME is capable of maintaining a liquid phase within a wide temperature range (-90 to 90\u0026deg;C). The spatial hindrance of CME molecules reduces the solvation energy between Li\u003csup\u003e+\u003c/sup\u003e and themselves, which allows AGG and n-AGG to primarily occupy their solvation structure. Additionally, the electric field facilitates the entry of FSI\u003csup\u003e\u0026minus;\u003c/sup\u003e ions with Li\u003csup\u003e+\u003c/sup\u003e into the outer Helmholtz layer of silicon anode, which preferentially decomposes to form anion-derived SEI. Compared to the SEI from LPF10 which exhibits initial precipitation of particulate LiF and subsequent reconstruction during cycling, the designed electrolyte enables the formation of a fully encapsulated double-layer SEI in the first cycle and maintains stability in subsequent cycling processes. The inner layer composed of LiF and Li\u003csub\u003e2\u003c/sub\u003eS inorganic nano-clusters, uniformly dispersed in the amorphous outer structure of the SEI, provides flexibility and high mechanical strength to handle the stress accumulation resulting from the volume expansion of SiNPs, thereby preventing SEI rupture and electrolyte invasion during cycling. Consequently, the SiNPs anode maintains its intact spherical particle structure without the occurrence of dead pulverized silicon-SEI composites during long cycling processes, leading to stable operation at temperatures ranging from \u0026minus;\u0026thinsp;20 to 60\u0026deg;C. The assembled SiNPs/SPAN full cell demonstrates excellent electrochemical performance with capacity retention of 83.5% after 800 cycles at -20\u0026deg;C. Furthermore, the enlarged 80 mAh SiNPs/LFP pouch cell retains 85.6% of its capacity after 150 cycles under limited electrolyte conditions. This study on the relationship between interfacial solvation structure, SEI chemistry, and spatial configuration evolution of silicon anode is of great significance for the development of next-generation high-energy-density LIBs.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n\u003ch2\u003eElectrolyte preparation\u003c/h2\u003e\n\u003cp\u003eLithium hexafluorophosphate (LiPF\u003csub\u003e6\u003c/sub\u003e), lithium bis(fluorosulfonyl)imide (LiFSI), 1,2-dimethoxyethane (DME), ethylene carbonate (EC), fluoroethylene carbonate (FEC), and diethyl carbonate (DEC) were purchased from DodoChem. Cyclopentyl methyl ether (CME, \u0026ge;\u0026thinsp;99.9%) was used as received from Aladdin. The LPF10 electrolyte was prepared by dissolving the 1 M LiPF\u003csub\u003e6\u003c/sub\u003e into the EC/DEC/FEC with volume ratio 4.5:4.5:1. The 5 M LiFSI DME electrolyte was prepared by dissolving the 5 M LiFSI into the DME solvent. As for the preparation of CME-based electrolyte, LiFSI with different concentration (1 M, 3 M, 5 M, and 7 M) was dissolved in the CME. All the electrolytes were thoroughly stirred for 3 h before use. The whole process of electrolyte preparation was conducted in the Ar-filled glove box with water and oxygen concentration less than 0.1 ppm.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n\u003ch2\u003eElectrode preparation\u003c/h2\u003e\n\u003cp\u003eThe silicon electrode was fabricated with 70 wt% SiNPs powder (Shanghai St-Nano Science and Technology Co., Ltd), 15 wt% super P (Timcal) as conductive additive, and 15 wt% lithium polyacrylate (LiPAA, 4 wt% aqueous solution) binder in water to form a slurry. The obtained slurry was cast onto copper foil, dried at room temperature for 6 h and further dried at 80\u0026deg;C overnight under vacuum. The typical mass loading of the SiNPs anode in Li/SiNPs half-cell is ~\u0026thinsp;1.0 mg cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e and the corresponding areal capacity is ~\u0026thinsp;3.0 mAh cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e. Similarly, the slurry of LFP cathode was prepared by mixing commercial LFP materials, polyvinylidene fluoride (PVDF, 99.5%, Arkema), super P and carbon nanotube (CNT, Guangdong Canrd New Energy Technology Co., Ltd.) with the mass ratio of 8:1:0.5:0.5. The slurry was dissolved in N-methyl-1,2-pyrrolidone (NMP, 99.9%, MTI corporation KJ GROUP) and cast onto aluminum foil collector. After NMP solvent was evaporated at 110\u0026deg;C for 12 h in vacuum oven, the electrode was calendared. The mass loading of the LFP cathode is 4\u0026ndash;11 mg cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e and the corresponding areal capacity is 0.5\u0026ndash;1.5 mAh cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e. The Synthesis of SPAN material could be accessed in our previous work\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e. The SPAN cathode was prepared by slurry coating on Al foils, with SPAN, CNT and PVDF in a mass ratio of 8:1:1 mixed in NMP solvent.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n\u003ch2\u003eCell fabrication\u003c/h2\u003e\n\u003cp\u003eIn Li/SiNPs coin cells, the prepared Si electrodes, Li foils (500 \u0026micro;m) and Polyethylene (PE, Asahi Kase) membranes were used as working electrodes, counter electrodes and separators, respectively. In full cell configurations, the negative/positive (N/P) ratio is controlled to about 1.1. The coin cells (CR2032) were assembled with the above cathode, SiNPs anode and polypropylene (PE) separator in an argon-filled glovebox. And 60 \u0026micro;L electrolyte was added in each coin cell. The pouch-type SiNPs/LFP cells with dimensions of 8.7 cm \u0026times; 4.5 cm were assembled using pouch-cell production machines (MTI corporation KJ GROUP) utilizing above-mentioned electrodes and PE as separator (one LFP cathode foil with double-side coated and two SiNPs anode foils with single-side coated).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n\u003ch2\u003eElectrochemical measurements\u003c/h2\u003e\n\u003cp\u003eThe galvanostatic charge\u0026ndash;discharge measurements of coin cells and pouch cells were carried out using a Land CT3001A battery test system (Wuhan Land Electronics Co. Ltd). The batteries were placed in the climatic chamber (GPR, Espec, Guangzhou, China) and brought to an appropriate onset temperature (\u0026minus;\u0026thinsp;20\u0026deg;C to 60\u0026deg;C) for the cycling test in wide temperature range. The Li/SiNPs half cells were measured at 0.05 C for the first 3 cycles and 0.2 C/1 C for the subsequent cycles between 0.01 V and 1.0 V (vs. Li/Li\u003csup\u003e+\u003c/sup\u003e) at room temperature, where 1 C\u0026thinsp;=\u0026thinsp;3579 mA g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Temperature fluctuation for Li/SiNPs half cells was tested at 0.05 C for the first 3 cycles at 30\u0026deg;C and 0.1 C charge\u0026ndash;discharge mode in different temperatures. The SiNPs/SPAN coin cells were cycled at 0.6-3.0 V at \u0026minus;\u0026thinsp;20\u0026deg;C, 30\u0026deg;C, and 60\u0026deg;C after fabrication. The SiNPs/NCM811 coin cell were conducted within a voltage window of 2.0\u0026ndash;4.0 V at \u0026minus;\u0026thinsp;20\u0026deg;C. The SiNPs/LFP coin cells and pouch cells were tested at the voltage of 2.5\u0026ndash;3.7 V at 30\u0026deg;C. The electrochemical impedance spectroscopy (EIS), Cyclic voltammetry (CV), linear sweep voltammetry (LSV) were examined in VMP3 potentiate/galvanostatic (Bio-Logic) electrochemical workstation. The temperature-dependent EIS was carried out in the climatic chamber with a temperature range from \u0026minus;\u0026thinsp;20\u0026deg;C to 30\u0026deg;C with the frequency range of 300 kHz\u0026ndash;10 mHz with a voltage amplitude of 10 mV. The CV curves were obtained at a rate of 0.05 mV s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in a voltage range of 0.01- 2 V (vs. Li/Li\u003csup\u003e+\u003c/sup\u003e). LSV test was carried out within OCV-7 V with aluminum foil as the work electrode and lithium foil as the counter electrode and reference electrode.\u003c/p\u003e\n\u003cp\u003eThe ionic conductivities of electrolytes are tested in stainless-steel symmetrical cells. EIS of these cells were measured at a voltage amplitude of 10 mV and in a frequency range of 10\u003csup\u003e6\u003c/sup\u003e to 0.1Hz. The calculation is based on the following equation:\u003c/p\u003e\n\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\n\u003cdiv id=\"FileID_Equa\" class=\"mathdisplay\"\u003e$$\\sigma =\\frac{L}{RS}$$\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003ewhere R is the intercept of the Nyquist plot and Z\u0026rsquo; axis, L and S is the distance and area of stainless steels. The Li\u003csup\u003e+\u003c/sup\u003e transference numbers are tested in Li/Li symmetric cells using 10 mV direct-current (DC) polarization and alternating-current (AC) impedance before and after polarization. The calculation formula is:\u003c/p\u003e\n\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\n\u003cdiv id=\"FileID_Equb\" class=\"mathdisplay\"\u003e$${t}_{{Li}^{+}}=\\frac{{I}_{s}(\\varDelta \\text{V}-{I}_{0}{R}_{0})}{{I}_{0}(\\varDelta \\text{V}-{I}_{s}{R}_{s})}$$\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003ewhere I\u003csub\u003es\u003c/sub\u003e and I\u003csub\u003e0\u003c/sub\u003e is the steady-state currents and initial current, respectively, R\u003csub\u003e0\u003c/sub\u003e and R\u003csub\u003es\u003c/sub\u003e is the interfacial resistance before and after polarization, respectively. The EIS was characterized in a frequency range between 10\u003csup\u003e6\u003c/sup\u003e and 0.1 Hz with a voltage amplitude of 5 mV.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\n\u003ch2\u003eCharacterizations\u003c/h2\u003e\n\u003cp\u003eThe DSC experiments were carried out using a NETZSCH DSC 204HP at a cooling/heating rate of 5\u0026deg;C min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Raman spectra were carried out on on a Horiba Jobin Yvon LabRAM HR Evolution (532 nm laser). \u003csup\u003e\u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003eLi-NMR spectra are recorded on an Agilent DD2-600 (600 MHz) at room temperature. The Scanning electron microscopy (SEM) images of all materials were obtained using a field emission scanning electron microscope (FE-SEM, Hitachi SU8000) at 5 kV. Cryo-Electron Microscopy was carried out on FEI Talos F200C under low dose mode at an accelerating voltage of 200 kV. The element analysis of Si surface after 50th cycling was performed by X-ray photoelectron spectroscopy (XPS) (Thermo ESCALAB 250Xi) with X-ray excitation source (monochrome Al Ka, power 150W, X-ray beam spot 500 \u0026micro;m). To avoid exposure to air and moisture, samples were transported from the glovebox to the XPS instrument directly. The data we obtained were corrected by a standard C 1s peak at 284.8 eV. The time-of-flight secondary ion mass spectrometry (TOF-SIMS) was obtained from PHI nanoTOFII Time-of-Flight SIMS. The sputtering and analysis areas were 400 \u0026times; 400 \u0026micro;m\u003csup\u003e2\u003c/sup\u003e and 50 \u0026times; 50 \u0026micro;m\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e, respectively. To access the morphology evolution of Si nano-particles in different electrolytes, a high-resolution TEM (HR-TEM) was conducted using a cold field emission transmission electron microscope (JEM-2100F, JEOL) at 200 kV. The Atomic Force Microscopy (AFM) of cycled Si electrodes was carried out on Bruker Dimension Icon. Derjaguin\u0026ndash;Muller\u0026ndash;Toporov (DMT) modulus images were acquired using an insulating silicon AFM tip (k\u0026thinsp;=\u0026thinsp;26 N m\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, f\u003csub\u003e0\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;300kHz) with peak force tapping mode.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\n\u003ch2\u003eCryo-TEM sample preparation\u003c/h2\u003e\n\u003cp\u003eTo avoid the influence of binder and surper P, we prepared the SiNPs anode sample by the slurry with SiNPs powder and LiPAA in a mass ratio of 9.5:0.5. After drying, the anode was lithiated to 1 mV and delithiated to 1 V respectively, using different electrolytes in Li/Si half cells. After cycling, cells were disassembled in an Ar-filled glove box. The Si electrodes were rinsed by DMC/DME to remove residual Li salts and then dried in the vacuum chamber. Then the electrodes are scratched, and deposited onto a microgrid carbon film supported by a copper grid. The microgrid carbon film were quickly transferred into liquid nitrogen outside of the argon-filled glovebox using a sealed container. The samples were then placed onto the cryo-EM holder, immersed in liquid nitrogen.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\n\u003ch2\u003eDFT caculation\u003c/h2\u003e\n\u003cp\u003eThe Spin-polarized density functional theory (DFT) calculations were carried out in Material Studio software\u0026rsquo;s DMol3 module. Geometry optimizations and energy calculations were performed using Lee\u0026ndash;Yang\u0026ndash;Parr correlation functional (B3LYP) at DNP level along with the Grimme method for dispersion correction. The convergence criteria of the energy and force were set to 1 \u0026times; 10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e Hartree and 0.002 Hartree/\u0026Aring;, respectively. The global orbital cutoff was set to 4.4 \u0026Aring;. The solvent\u0026ndash;solute interaction was considered with the universal solvation model of conductor-like screening model (COSMO). Frequency analysis was performed to ensure the ground state of molecular structures. The solvating energy (E\u003csub\u003eb\u003c/sub\u003e) was defined as:\u003c/p\u003e\n\u003cp\u003eE\u003csub\u003eb\u003c/sub\u003e = E\u003csub\u003e[Li\u0026minus;solvent]+\u003c/sub\u003e - E\u003csub\u003esolvent\u003c/sub\u003e - E\u003csub\u003eLi+\u003c/sub\u003e\u003c/p\u003e\n\u003cp\u003eWhere E\u003csub\u003e[Li\u0026minus;solvent]+\u003c/sub\u003e is the energy of the Li\u003csup\u003e+\u003c/sup\u003e -solvent complex, E\u003csub\u003esolvent\u003c/sub\u003e is the energy of the solvent molecule and E\u003csub\u003eLi+\u003c/sub\u003e is the energy of the Li\u003csup\u003e+\u003c/sup\u003e ion. This calculation is restricted to a local single ideal solvation structure, and the effect of increasing overall coordination number is not considered.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\n\u003ch2\u003eMolecular dynamics simulation\u003c/h2\u003e\n\u003cp\u003eAtomistic molecular dynamics simulations have been performed in the GROMACS\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e55\u003c/span\u003e\u003c/sup\u003e (version 2020.6) simulation package, using the optimized potentials for liquid simulations all-atom (OPLS-2009IL\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e56\u003c/span\u003e\u003c/sup\u003e and OPLSAAM\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e57\u003c/span\u003e,\u003cspan class=\"CitationRef\"\u003e58\u003c/span\u003e\u003c/sup\u003e) force field. Three systems were simulated, sys1 contains 369 LiFSI and 632 CME molecules; sys2 contains 342 LiFSI and 658 DME; sys3 contains 84 LiPF6, 379 EC, 422 DEC, and 115 FEC. For all systems the molecules were first randomly placed in cubic boxes of around 10 nm. After thousands of steps of energy minimization, the systems were equilibrated for 10 ns and followed the production runs of 40 ns under the NPT ensemble at three temperatures of 333, 303, and 243 K. For interfacial simulations, the Si surface was built through the Materials Studio Software with side length around 5.7 nm, and 368 LiFSI and 632 CME molecules were randomly placed on the surface. After thousands of steps of energy minimization, the systems were equilibrated for 10 ns with the lateral axis fixed under the semi-isotropic NPT ensemble, and followed the production runs of 40 ns under with and without an electric field of 0.1 V/nm perpendicular to the surface. The temperature was controlled using the Nose-Hoover method and the pressure was coupled to 1 atm using the Parrinello-Rahman method. The cutoff scheme of 1.2 nm was implemented for the non-bonded interactions, and the Particle Mesh Ewald method\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e59\u003c/span\u003e\u003c/sup\u003e with a fourierspacing of 0.1 nm was applied for the long range electrostatic interactions. All covalent bonds with hydrogen atoms were constraint using the LINCS algorithm\u003csup\u003e\u003cspan class=\"CitationRef\"\u003e60\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data are available in the main test or the Supplementary information.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe acknowledge financial support from the Natural Science Foundation of China (22022813), the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang (2019R01006), the Zhejiang Provincial Natural Science Foundation of China (LQ24B030002) and the China Postdoctoral Science Foundation (2022M722729, 2023T160571). We thank Mrs. Lingyun Wu in the Center of Cryo-Electron Microscopy (CCEM), Zhejiang University for her technical assistance on Cryo-EM. Authors thank Mrs. Na Zheng at State Key Laboratory of Chemical Engineering in Zhejiang University for performing SEM. We also thank Xiaokun Ding at Department of Chemistry, Zhejiang University for HRTEM operation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eY.L. conceived the idea and supervised the project. S.M. and J.Z. designed the experiments. S.M. performed the experiments with the help of S.Z., Z.L., Q.W., and H.C. J.Z. performed the cyro-TEM characterizations. J.M. performed the DFT calculations. Z.S. synthesized and fabricated the SPAN electrodes. All authors discussed the results and participated in writting the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eArmand, M. \u0026amp; Tarascon, J.-M. 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Chem.\u003c/em\u003e \u003cstrong\u003e18\u003c/strong\u003e, 1463-1472 (1997).\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-3865538/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3865538/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eSilicon nanoparticles (SiNPs) show great promise as high-capacity anodes owing to their ability to mitigate mechanical failure. However, the substantial surface area of SiNPs triggers interfacial side reactions and solid electrolyte interphase (SEI) permeation during volume fluctuations. The slow kinetics at low temperatures and the degradation of SEI at high temperatures further hinder the practical application of SiNPs in real-world environments. Here, we address these challenges by manipulating the solvation structure through molecular space hindrance. This manipulation enables anions to aggregate in the outer Helmholtz layer under an electric field, leading to rapid desolvation capabilities and the formation of anion-derived SEI. The resulting double-layer SEI, where nano-clusters are uniformly dispersed in the amorphous structure, completely encapsulates the particles in the first cycle. The ultra-high modulus of this structure can withstand stress accumulation, preventing electrolyte penetration during repeated expansion and contraction. As a result, SiNPs-based batteries demonstrate exceptional electrochemical performance across a wide temperature range from \u0026minus;\u0026thinsp;20 to 60\u0026deg;C. The assembled 80 mAh SiNPs/LiFePO\u003csub\u003e4\u003c/sub\u003e pouch cell maintains a cycling retention of 85.6% after 150 cycles. This study elucidates the intricate relationship between interface solvation, SEI chemistry, and bulk stability, offering new insights for the development of wide-temperature Si-based batteries.\u003c/p\u003e","manuscriptTitle":"Anionic aggregates induced interphase chemistry regulation toward wide-temperature silicon-based batteries","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-23 17:04:19","doi":"10.21203/rs.3.rs-3865538/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5bf9f8ff-22cc-4adc-b5cc-bcccc5e87418","owner":[],"postedDate":"January 23rd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":28176896,"name":"Physical sciences/Materials science/Materials for energy and catalysis/Batteries"},{"id":28176897,"name":"Physical sciences/Engineering/Chemical engineering"}],"tags":[],"updatedAt":"2024-03-01T11:35:52+00:00","versionOfRecord":[],"versionCreatedAt":"2024-01-23 17:04:19","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3865538","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3865538","identity":"rs-3865538","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}