Bimetallic Chalcogenides Enable Highly Efficient Polysulfide Capture and Conversion in Lean-Electrolyte Li-S Batteries

Bimetallic Chalcogenides Enable Highly Efficient Polysulfide Capture and Conversion in Lean-Electrolyte Li-S 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 Research Article Bimetallic Chalcogenides Enable Highly Efficient Polysulfide Capture and Conversion in Lean-Electrolyte Li-S Batteries Junhua Wang, Hao Sun, Weiran Zhao, Chongxiang Pan, Rongrong Li, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4655461/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 26 Oct, 2024 Read the published version in Journal of Applied Electrochemistry → Version 1 posted 15 You are reading this latest preprint version Abstract The commercialization of Li-S batteries is obstructed by the sluggish redox kinetics and serious shuttling behaviors of polysulfides. Herein, we report a rationally structured sulfur host material to tackle these issues, i.e. (Co, Ni) 9 S 8 nanoparticles uniformly decorated on electrospun carbon nanofibers. The (Co, Ni) 9 S 8 nanoparticles are demonstrated to effectively capture polysulfides and catalytically promote their redox conversions. Moreover, the interlinked porous architecture of (Co, Ni) 9 S 8 @CNFs also contributes to alleviate volume expansion of sulfur cathode and provide the rapid electron transfer paths and Li-ion diffusion channels. Benefiting from these attributes, the (Co, Ni) 9 S 8 @CNFs cathode delivers an excellent rate capability and long cycling stability (capacity decay of 0.142% per cycle over 300 cycles). Additionally, the (Co, Ni) 9 S 8 @CNFs with high sulfur content (83.3%) and lean electrolyte (5 μL mg -1 ) shows high capacity of 556 mAh g -1 at 0.5 C and 590 mAh g -1 after 180 cycles at 0.2 C, demonstrating highly efficient utilization of sulfur and extraordinary potential for practical application of Li-S batteries. (Co Ni)9S8@CNFs electrospun catalyst high sulfur content lean electrolyte Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Among the alternatives currently proposed to overcome the limitations of lithium-ion batteries, lithium-sulfur batteries (LSBs) have aroused overwhelming attention because of the high theoretical energy density (2567 W h kg − 1 ), the low cost and eco-friendly of sulfur cathode. [ 1 – 3 ] However, the commercial application of LSBs has encountered several intractable technical difficulties. [ 4 – 5 ] The insulativity (5×10 − 30 S cm − 1 at 25 ℃) of sulfur and its discharge products (Li 2 S 2 /Li 2 S) leads to a sluggish discharge/charge reaction kinetics and a poor practical capacity. [ 6 ] The sulfur cathode is also subjected to the structure collapse arising from the large volume expansion (~ 80%) when the initial S (2.07 g cm − 3 ) completely converted to Li 2 S (1.66 g cm − 3 ). [ 7 ] Most importantly, lithium polysulfides (Li 2 S n , 3≤ n ≤8, denoted as LiPSs) bring shuttling effect between the electrodes and electrolyte, resulting in the continual and irreversible loss of active sulfur, rapid capacity fading, and low Coulombic efficiency. [ 8 ] Numerous strategies have been devoted to addressing the above-mentioned issues. Among them, the rational configuration of sulfur host is tremendous importance in enhancing the performance of LSBs. [ 9 – 11 ] Carbonaceous hosts can boost the electronic transfer to S and Li 2 S and buffer the volume change of sulfur electrodes as well as suppress the LiPS migration by the physical confinement. [ 12 – 14 ] However, the nonpolar physical restriction is usually too weak to anchor effectively LiPSs, leading to a dissatisfactory cycle stability of LSBs. [ 15 – 16 ] The polar host materials, despite their strong chemical absorbability towards the LiPSs, have poor electrical conductivity, resulting in a low sulfur utilization, especially under a high sulfur loading. [ 17 – 21 ] Therefore, it is highly required to design a unique sulfur host with excellent electrical conductivity and efficient adsorption effect as well as superior catalytic performance. Recently, Ni/Co-based metal or bimetallic sulfides have been widely reported as efficient bifunctional electrocatalyst. [ 22 – 24 ] Among these metal sulfides, Co 9 S 8 -based catalysts presented high catalytic activities due to the unique next-nearest-neighbor metal-metal bonds, the pseudo-metallic electronic structure and suitable adsorption for species. [ 25 ] Moreover, it has been widely used as an electrocatalyst in the water splitting, [ 23 – 24 , 26 ] sensors, [ 27 ] and energy storage. [ 28 – 32 ] Nevertheless, these studies insists that the relatively low ion transport kinetics and poor stability seriously impede further improvement of Co 9 S 8 electrocatalyst. [ 24 , 33 – 34 ] In this regard, metal-incorporation or integration with carbon materials are two effective strategies to enhance the electrocatalytic activity for metal sulfides. [ 35 – 38 ] As for metal incorporating, some investigations have verified that the introduction of Ni into Co 9 S 8 materials ( e.g. , (Co 0.64 Ni 0.36 ) 9 S 8 and Co 4.7 Ni 4.3 S 8 ) is a worthwhile tactic. [ 35 , 38 ] These studies show that the incorporation of heteroatom metals can modify electronic states and rearrange valence electrons. Additionally, the encapsulation or anchoring of metal nanoparticles in carbon shell/carbon cage is an effective approach to improve the stability of Co 9 S 8 electrocatalyst. Motivated by these considerations, it is significant to configurate (Co, M) 9 S 8 (M = Co, Ni, Fe) nanoparticles uniformly supported on carbon nanofibers as electrocatalytic sulfur host materials. On the one hand, the (Co, M) 9 S 8 nanoparticles tend to build a chemical bonding with LiPS to suppress the shuttling effect. [ 39 ] On the other hand, they also can served as electrocatalysts to facilitate the electron transport and accelerate LiPS conversion, yielding satisfactory cell performance. [ 9 , 40 ] Whereas, the most reported LSBs that demonstrates high capacity and long cycling life usually exhibits a low S content ( 20 µl mg − 1 ). [ 1 , 8 , 41 ] Therefore, designing novel host structure is pivotal for achieving commercial applications of LSBs with high sulfur content and lean electrolyte. Herein, a rational structure composed of (Co, Ni) 9 S 8 nanoparticles decorated on the carbon nanofibers ((Co, Ni) 9 S 8 @CNFs) as sulfur host is designed to maximize the catalytic effect via electrospun. Figure 1 a presents the feasible synthesized process of (Co, Ni) 9 S 8 @CNFs. Such composite offers several advantages: (i) the small and uniformly distributed polar nanoparticles can maximize the chemical adsorption capability for solvable LiPSs; (ii) CNTs interlinked into the network structure can prevent sulfur cathode large volume expansion and provide rapid electron transfer; (iii) porous architecture of the (Co, Ni) 9 S 8 @CNFs not only contributes to the permeation of electrolyte and sulfur, but also exposes abundant active interface areas. The theoretical analysis reveals that the introduction of Ni into Co 9 S 8 forming (Co, Ni) 9 S 8 can boost the metallic properties and reinforce the interaction between LiPSs and catalysts. As a results, (Co, Ni) 9 S 8 @CNFs/S electrode can achieve high initial discharge capacity (1123 mAh g − 1 ), outstanding rate capability and cyclic stability (with an average CE of 99.1% and capacity decay per cycle of 0.142% over 300 cycles at 0.5 C) at 20 µL mg − 1 . Moreover, the (Co, Ni) 9 S 8 @CNFs with high sulfur content (83.3%) and lean electrolyte (5 µL mg − 1 ) presents 556 mAh g − 1 at 0.5 C and high capacity of 590 mAh g − 1 after 180 cycles at 0.2 C, demonstrating highly efficient utilization of sulfur and extraordinary potential for practical application of Li-S batteries. 2. Experimental Section 2.1 Material synthesis The (Co, Ni) 9 S 8 particles decorated on carbon nanofibers ((Co, Ni) 9 S 8 @CNFs) were prepared through an electrospinning technique. Typically, 3.0 g PVP (average M w =58000) was dissolved into 12.0 mL H 2 O and ethanol (1:1 by volume) by stirring overnight. Ni(CH 3 COO) 2 .4H 2 O, Co(CH 3 COO) 2 .4H 2 O, and CH 4 N 2 S with a molar ratio of 1:2:4 were dissolved in PVP solution. Then the precursor was electrospun at a high voltage of 18 kV, rapid feeding rate of 1.0 mL h − 1 , and large receiver distance of 15 cm. The as-collected membrane was annealed at 550 ℃ (5 ℃ min − 1 ) in Ar atmosphere for 2 h to obtain (Co, Ni) 9 S 8 @CNFs. The Co 9 S 8 decorating on carbon nanofibers (Co 9 S 8 @CNFs) and PVP-derived carbon nanofibers (CNFs) were obtained by a similar method. (Co, Ni) 9 S 8 @CNFs/S, Co 9 S 8 @CNFs/S, CNFs/S were prepared by mixing S power with the samples ((Co, Ni) 9 S 8 @CNFs, Co 9 S 8 @CNFs, CNFs), then heated at 155. ℃ for 12. h in Ar atmosphere. 2.2 Electrochemical measurements The sulfur cathodes were fabricated by mixing the active materials ((Co, Ni)9S8@CNFs/S, Co9S8@CNFs/S, CNFs/S, 80 wt.%), Super P (10 wt.%), and PVDF (10 wt.%). This mixture was abrasively dispersed in NMP to form slurry. Then the slurry was coated on current collector and the sulfur loading depends on the coating thickness. Li metals were employed as anodes. The electrolyte is 1 M LiTFSI in DOL/DME (1:1 by volume) mixture with 0.1 M LiNO 3 . The electrolyte-to-sulfur (E/S) ratio is about 20 µl mg − 1 for the cathode of ~ 2.8 mg cm − 2 . The electrochemical performances of lean E/S ratios (5, 10, 15, 20, and 25 µl mg − 1 ) were also estimated. Galvanostatic discharge/charge tests of all cells were measured with a voltage range of 1.4–2.8 V. Through a PARSTAT3000A-DX electrochemical workstation, the CV curves were conducted under various scan rates (0.1, 0.2, 0.5, and 0.8 mV s − 1 ) and EIS was performed from 50 mHz to 100 kHz with a voltage amplitude of 10 mV. 2.3 Adsorption tests of polysulfides Li 2 S x solution was obtained by mixing Li and element S in electrolyte (1 M LiTFSI in DOL/DME, v:v = 1:1) to prepared saturated LiPSs solution. Then 50 mg of (Co,Ni) 9 S 8 @CNFs, Co 9 S 8 @CNFs, CNFs powders were added into Li 2 S x solution (2000 µL), respectively. After standing for 12 h, the supernatant was taken for UV-vis analysis and the precipitate was dried for XPS tests. 2.4 Characterizations The X-ray diffraction patterns were conducted on X’Pert 3 Powder with Cu Kα as the radiation. The morphology of the sample was characterized by scanning electron microscope (Nova NanoSEM 450), and transmission electron microscopy. X-ray photoelectron. spectroscopy (XPS) was obtained on a Thermo Scientific K-Alpha. + system. The thermogravimetric analysis (TGA) test was performed using a PerkinElmer STA-800 TGA instrument. 2.5 Computational details Density functional theory (DFT) was applied to evaluate the LiPSs adsorption. The Co 9 S 8 and (Co, Ni) 9 S 8 stripes with (311) exposure were simulated. DFT calculations were carried out using DMol3. package in the Materials. Studio. Perdew-Burke-Ernzerhof (PBE) of general gradient approximation (GGA) was applied to depict the exchange-correlation interaction. Spin-polarized calculation was applied. A 4×4×1 Monkhorst-Pack mesh k-points was used for the sampling of the Brillouin zone. Moreover, all the results was adopted using spin-polarized calculations. 3. Results and Discussion 3.1 Morphology of (Co, Ni) 9 S 8 @CNFs (Co, Ni) 9 S 8 @CNFs were synthesized by a feasible electrospinning technique (Fig. 1 a, Experimental Section). The scanning electron microscope (SEM) of (Co, Ni) 9 S 8 @CNFs reveals that it has 1 D interconnected scaffolds morphology ( Figure S1 ). The CNFs fiber has a diameter of about 100 nm and its surface contains abundant (Co, Ni) 9 S 8 nanoparticles as well as pores due to the release of CO 2 gas from high-temperature calcination (Fig. 1 b). The uniform distribution of the abundantly active (Co, Ni) 9 S 8 nanoparticles on CNFs fiber is verified by the energy dispersive spectrometer (EDS) mapping images ( Figure S2 ). Moreover, elemental analysis illustrates the (Co, Ni) 9 S 8 @CNFs contains about 16.59 wt% carbon species. The transmission electron microscopy (TEM) of (Co, Ni) 9 S 8 @CNFs further reveal that (Co, Ni) 9 S 8 nanoparticles are uniformly decorated on CNFs skeleton and the diameter of sulfides particles are about 3 nm (Fig. 1 d, 1 e). The high-resolution TEM image (Fig. 1 e (Inset) ) displays the clear lattice fringes with 0.281 nm space, matching well with the (311) plane of cubic (Co, M) 9 S 8 . To confirm the advantages of the fiber as sulfur host, (Co, Ni) 9 S 8 @CNFs/S was prepared by S infiltration treatment. The (Co, Ni) 9 S 8 @CNFs/S display smooth surfaces as the pores were filled with sulfur (Fig. 1 c). Additionally, The STEM image and EDS line-scan analysis of (Co, Ni) 9 S 8 @CNFs/S are shown in Fig. 1 f. It demonstrates that sulfur has penetrated into the interspace and pores of (Co, Ni) 9 S 8 @CNFs fibers and uniformly distributed on surface. 3.2 Physical properties of (Co, Ni) 9 S 8 @CNFs The crystallographic structure of Co 9 S 8 @CNFs and (Co, Ni) 9 S 8 @CNFs before and after sulfur permeation is investigated by X-ray diffraction (XRD) (Fig. 2 a, S3b). Clearly, all the strong diffraction peaks of Co 9 S 8 @CNFs agree well with the cubic (Co, M) 9 S 8 exhibiting a space group of Fm-3m (PDF #30–0444), which are consistent with those reported works. [ 35 , 42 ] For (Co, Ni) 9 S 8 @CNFs, no diffraction line corresponds to the Ni-based sulfides has been observed, implying the successful incorporation of the Ni in the tetrahedral and octahedral sites of the pentlandite structure. [ 43 – 44 ] This should be attributed to the similar size of Co 2+ (74 pm) and Ni 2+ (69 pm). The contents of Co, Ni and S in the (Co, Ni) 9 S 8 detected by an inductively coupled plasma-optical emission spectrometer (ICP-OES) measurements are about 45.05 wt%, 22.59 wt%, and 32.47 wt%, respectively ( Figure S3a ). The corresponding molar ratio is approximately 6:3:8, which consists with the molar ratio of raw materials. While the CNFs/S, Co 9 S 8 @CNFs/S and (Co, Ni) 9 S 8 @CNFs/S inherit prominent peaks of sublimed sulfur and (Co, M) 9 S 8 reconfirming the existence of surface sulfur and catalytic host materials ( Figure S3b ), in line with the TEM results. The sulfur content of the three host materials is measured to be 80 wt% by thermogravimetric analysis (TGA) tests (Fig. 2 b). Figure 2 c illustrates the Raman spectrum of CNFs, Co 9 S 8 @CNFs and (Co, Ni) 9 S 8 @CNFs hosts. The ratios of the intensities of the G-band at 1590 cm − 1 and the D-band at 1350 cm − 1 ( I G / I D ) for the three hosts are calculated to be 0.823, 0.900, and 0.965, respectively. The higher ratio of Co 9 S 8 -based CNFs compound indicates higher graphitization degree than that of CNFs, [ 45 ] which may be due to the rapid electron-transfer effect between Co 9 S 8 and carbon. [ 46 ] The outstanding graphitized carbon is favorable to boost the electronic conductivity of the S host and further reinforce its utilization during cycling processes. [ 46 ] The surface resistances of host materials were tested by a four-point probes resistivity measurement system (RTS-9). As displayed in Figure S3c , the resistivities of the three hosts are about 148, 76, and 39 Ω cm, respectively. The high electrical conductivity of (Co,Ni) 9 S 8 @CNFs contributes to rapid electron transfer to remedy the insulativity of sulfur and its discharge products. [ 9 , 18 ] The specific surface and pore structures of CNFs, Co 9 S 8 @CNFs, and (Co, Ni) 9 S 8 @CNFs were investigated by Brunauer EmmettTeller (BET) method (Fig. 2 d). The results show that (Co, Ni) 9 S 8 @CNFs have a higher specific surface area of 89.48 m 2 g − 1 and a total pore volume of 0.36 cm 3 g − 1 than those of CNFs (51.38 m 2 g − 1 , 0.17 cm 3 g − 1 ) and Co 9 S 8 @CNFs (87.48 m 2 g − 1 , 0.33 cm 3 g − 1 ). The high surface area and large pore volume of (Co, Ni) 9 S 8 @CNFs can provide a high sulfur loading and facilitate electrolyte infiltration. [ 47 – 48 ] 3.3 LiPSs adsorption and kinetics characterization The strong interaction between (Co, Ni) 9 S 8 @CNFs and polysulfides (LiPSs) was examined systematically by visual adsorption experiments and UV-vis tests. The same amount of three host composites was separately added into LiPSs solution, which were then placed in glove box for 12 h (Fig. 3 a). The LiPSs solution before and after adsorbing was measured by UV-vis tests (Fig. 3 b). The peak located at 260 nm is attributed to the S 8 2− /S 6 2− species, the sharp peak at 350 nm is assigned to S 6 2− /S 4 2− species, and the wide peak at about 490 nm is ascribed to S 4 2− species. [ 49 – 50 ] Obviously, (Co, Ni) 9 S 8 @CNFs completely decolors the LiPSs solution after 12 h and significantly removes the characteristic peak of Li 2 S 4 (Fig. 3 a), confirming that the (Co, Ni) 9 S 8 @CNFs has strong chemisorption towards LiPSs. The adsorption mechanism was further probed by XPS analysis. The peak intensity of S element in the XPS spectrums of CNFs/Li 2 S x , Co 9 S 8 @CNFs/Li 2 S x , and (Co, Ni) 9 S 8 @CNFs/Li 2 S x is stronger than that before soaking Li 2 S x ( Figure S4 ), which implies that large amounts of LiPSs were adsorbed. The peaks of S2p located at 162.18 and 164.08 eV should belong to the terminal sulfur (S T −1 ) and bridging sulfur (S B −1 ), respectively ( Figure S5a ). [ 51 ] The other peaks at 166.98 and 169.28 eV can be assigned to the thiosulfate and polythionate. The presence of the sulfates has a positive mediator effect on the conversion from long-chain to short-chain LiPSs. [ 46 , 52 ] Additionally, S-Co and S-Ni bonds at about 163.62 and 161.37 eV corroborates the synergetic adsorption effect of Co and Ni sites. [ 45 , 53 ] Compared with the original Co 2p 3/2 core level, electron binding energies of Co 3+ and Co 2+ in (Co, Ni) 9 S 8 @CNFs/Li 2 S x slightly shift to lower energies (Fig. 3 c), implying the electron transfer from Li 2 S x to Co. Meanwhile, the proportion of Co 3+ from 34.2% decreases to 27.0% after adsorbing Li 2 S x solution, which originates form the partial reduction of Co 3+ induced by the charge transfer from S x 2− . [ 53 ] Similarly, the binding energy of Ni 2p peaks is reduced more significantly in Fig. 3 d, and the content of Ni 3+ from 51.3% decreases sharply to 37.5% after adsorbing Li 2 S x , indicating that Li 2 S x interact more strongly with Ni than Co sites of (Co, Ni) 9 S 8 . [ 54 ] Co 2p core level of the Co 9 S 8 @CNFs and Co 9 S 8 @CNFs/Li 2 S x were also investigated ( Figure S5b , S5c ), the proportion of Co 3+ decreases significantly and the content of Co 2+ increases obviously. Meanwhile, the binding energy of Co 2p peaks is reduced significantly. These XPS spectra analysis together with the adsorption experiments support the fact that (Co, Ni) 9 S 8 @CNFs exhibits a strong chemical affinity towards LiPSs, which is essential for a stable cycle of battery. To further rationalize the electrocatalytic activity of (Co, Ni) 9 S 8 @CNFs at the atomic level, the density functional theory (DFT) calculation was carried out. The total density of states (TDOS) of Co 9 S 8 and (Co, Ni) 9 S 8 are shown in Fig. 3 e. The introducing of Ni atoms contributes to the energy levels of Co 9 S 8 shifting to the Fermi level, which suggests that the (Co, Ni) 9 S 8 has better conductivity than Co 9 S 8 . [ 40 , 55 ] According to calculation in Figure S6 (a, b) , the band gap of (Co, Ni) 9 S 8 (0.006 eV) is much lower than that of the Co 9 S 8 (0.024 eV), further indicating the enhancement of metallicity. The TDOS analysis of polysulfides adsorbed on the (311) surfaces of Co 9 S 8 and (Co, Ni) 9 S 8 in Figure S6 (c, d) shows that the conductivity of Co 9 S 8 weakens after adsorption of polysulfides while (Co, Ni) 9 S 8 is almost unchanged. [ 56 ] Once again proving there is excellent electronic conductivity of (Co, Ni) 9 S 8 @CNFs. Figure 3 f and Figure S7 display the Li 2 S 4 , Li 2 S 6 , and Li 2 S 8 adsorption configuration on Co 9 S 8 and (Co, Ni) 9 S 8 (311) surfaces. The binding energy in Fig. 3 g verifies that polysulfide molecules are adsorbed more strongly on the surface of (Co, Ni) 9 S 8 than Co 9 S 8 , implying that the introduction of Ni is helpful to suppress polysulfides shuttle effect. To investigate the transformation kinetics of polysulfides, various electrochemical measurements were performed. The electrochemical impedance spectra (EIS) tests of LSBs after first discharge and 400th discharge at 0.1 C were conducted (Fig. 4 a, b), and the fitted data were showed in Table S1 . After first cycle, both the charge-transfer resistance ( R ct ) and the resistance of the deposited Li 2 S 2 /Li 2 S on the electrode surface ( R l ) [ 18 ] of Co 9 S 8 @CNFs and (Co, Ni) 9 S 8 @CNFs are slight larger than CNFs (Fig. 4 a). After 400 cycles, the semicircle in high frequency region gradually become smaller, accompanied with relatively large semicircle in medium-high frequency region (Fig. 4 b). It means that the deposition of the insoluble Li 2 S 2 /Li 2 S layer of three composites during the cycling processes is induced. [ 31 ] After cycling, as shown in Table S1 , the values of R ct and R l after 400th cycle are decreased sharply to 12.9 Ω and 12.0 Ω, 23.1 Ω and 7.4 Ω for Co 9 S 8 @CNFs/S and (Co, Ni) 9 S 8 @CNFs/S cathodes, respectively. It is verified (Co, Ni) 9 S 8 @CNFs possesses outstanding electronic conductivity, which is consistent with the above TDOS results. Additionally, CNFs/S electrode exhibits higher R ct resistance after 400th cycling, which possibly caused by the accumulation of Li 2 S 2 and Li 2 S. The discharge products (Li 2 S 2 and Li 2 S) with low conductivity are physically covered on the surface of CNFs/S electrode, which gives rise to slow electron transfer, enlarged impedance and cracked electrode because of the shuttle effect. On the other hand, for (Co, Ni) 9 S 8 @CNFs electrodes, the low resistance can be ascribed to the rapid reversible transformation between Li 2 S 2 /Li 2 S passivation layer and sulfur as well as fast charge transfer during cycling process, owing to the strong chemical adsorption. [ 57 ] Fig. 4 c presents the typical CV curves of the three kinds of electrodes in window of 1.4 ~ 2.8 V. Two cathodic peaks at. 2.36 V (Peak a) and. 2.04 V (Peak b) correspond to the stepwise reduction from Li 2 S 8 /Li 2 S 6 to Li 2 S 4 , and then to Li 2 S 2 /Li 2 S. Correspondingly, a sharp anodic peak at 2.42 V (Peak c) is associated with the reverse reaction. [ 51 ] CV tests were also conducted under different scan rates to demonstrate the effect of (Co, Ni) 9 S 8 @CNFs on the redox reaction kinetics of intermediate LiPSs ( Figure S8 ). As shown in Fig. 4 d-f, it can be found that a linear relationship between redox peak currents ( I p ) and the square root of scan rate ( v 0.5 ), implying the rate-determining step dependents on the diffusion rate of LiPSs. [ 9 ] The Li + ion diffusion process can accord with the Randles-Sevcik equation: [ 30 , 49 ] $${I}_{p}=\left(2.69\times {10}^{5}\right).{n}^{1.5}\cdot A\cdot {D}_{Li}^{0.5}{v}^{0.5}{C}_{\text{L}\text{i}}$$ 1 The Li + ion diffusion rate ( D Li + ) is positively correlated with the slope of ( I p / v 0.5 ) due to the n , A , and C Li can be seen as constants in LSBs. Obviously, the slopes of the. reduction/oxidation peaks (peak a, b, c) of Co 9 S 8 @CNFs/S and (Co, Ni) 9 S 8 @CNFs/S electrodes are higher than that of CNFs/S, especially (Co, Ni) 9 S 8 @CNFs/S, verifying the rapid diffusion process of Li + ions. The high D Li + of (Co, Ni) 9 S 8 @CNFs should be attributed to the modified electronic structure induced by the introduction of Ni element, leading to outstanding catalytic performance. To further evaluate the catalytic kinetics of Co 9 S 8 @CNFs/S and (Co, Ni) 9 S 8 @CNFs/S electrodes, the activation energy is calculated based on the transformation from Li 2 S 4 to Li 2 S through temperature-dependent CV tests ( Figure S9a-c ). [ 52 ] According to the Arrhenius equation, the peak current ( j ) is positively correlated with the reaction rate. [ 54 ] By fitting the slops (Fig. 4 g), the barrier potential of (Co, Ni) 9 S 8 @CNFs (15.86 kJ mol − 1 ) is lower than that of Co 9 S 8 @CNFs (16.34 kJ mol − 1 ) and CNFs (19.43 kJ mol − 1 ), implying easier to catalytic conversion of polysulfides. The polarization voltage gap (peak b and c) reveals the excellent catalytic property of Co 9 S 8 @CNFs species, especially (Co, Ni) 9 S 8 @CNFs ( Figure S9d ). Potential polysulfides conversion kinetics enhancements were also investigated by the CNFs, Co 9 S 8 @CNFs, and (Co, Ni) 9 S 8 @CNFs symmetrical cells. Compared with CNFs, Co 9 S 8 @CNFs and (Co, Ni) 9 S 8 @CNFs symmetric cells present smaller charge-transfer resistances (Fig. 4 h), hinting the improved LiPSs conversion kinetics. As shown by the CV profiles in Fig. 4 i, all symmetric cells present four main peaks at -0.46, -0.06, 0.07, and 0.46 V. The (Co, Ni) 9 S 8 @CNFs symmetric cell exhibits the largest current response, further suggesting its rapid polysulfides conversion kinetics. [ 51 ] These results collectively validate that the uniform distributions of (Co, Ni) 9 S 8 nanoparticles on carbon nanofibers will greatly facilitate the conversion rate of sulfur and decrease polarization during cycling process. Meanwhile, they also demonstrate that the reversible conversion of LiPSs can significantly accelerate by the introduction of Ni in Co 9 S 8 @CNFs. 3.4 Electrochemical properties of (Co, Ni) 9 S 8 @CNFs/S electrode Further electrochemical evaluations were carried out for different electrodes by CR2032 coin cells. Figure 5 a presents the rate capacity of CNFs/S, Co 9 S 8 @CNFs/S, and (Co, Ni) 9 S 8 @CNFs/S cathodes at 0.1 to 5.0 C and returning to 0.1 C (1 C = 1675 mA g − 1 , E/S = 20 µl mg − 1 ). Evidently, the (Co, Ni) 9 S 8 @CNFs/S cathode shows superior rate performance than the other two electrodes under different rates. Based on (Co, Ni) 9 S 8 @CNFs/S, at 0.1 C, 0.2 C, 0.5 C, 1.0 C, and 2.0 C, the discharge specific capacity is as high as 976, 850, 704, 584, and 485, respectively. Even current density is up to 5.0 C, a reversible capacity of 342 mAh g − 1 is presented. The excellent rate of (Co, Ni) 9 S 8 @CNFs/S electrode benefits from the strong adsorption-catalysis interaction between (Co, Ni) 9 S 8 @CNFs and LiPSs. The Co 9 S 8 @CNFs/S shows a similar rate performance but lower capacity. and utilization of S. In sharp contrast, the CNFs/S exhibits low rate. capacity. of only 160 mAh g − 1 at the 5.0 C. This kinetic. difference. can also be reflected from the voltage profiles (Fig. 5 b and Figure S10a, b ). For (Co, Ni) 9 S 8 @CNFs electrode, a remarkably steady discharge plateau at ~ 1.9 V representing the conversion from long-chain LiPSs to insoluble Li 2 S 2 /Li 2 S can be shown even under 5.0 C. In contrast, CNFs/S has no obvious discharge plateau at 2.0 C, and it also presents a larger polarization at each current density. When the current density returns back to 0.1 C after diverse rates, the discharge behavior can be self-healed very well for catalytic electrodes, especially (Co, Ni) 9 S 8 @CNFs/S, which recurred 95% of its discharge capacity of second cycle suggesting excellent catalytic activity and reversibility. By comparison, CNFs/S recovered to 700 mAh g − 1 , only 77% of its discharge capacity of second cycle. So again, the results demonstrate the higher catalytic ability and the faster redox kinetics of the (Co, Ni) 9 S 8 @CNFs than CNFs/S. It is essential to satisfy the practical application of LSBs with low electrolyte/sulfur (E/S) ratio. [ 17 ] The cycling performances of (Co, Ni) 9 S 8 @CNFs under S loading 2.8 mg cm − 2 with different E/S ratios have been investigated at 0.5 C. As shown in Fig. 5 c, it still obtains decent cycling performance at 15 and 20 µl mg − 1 . Significantly, when the E/S = 20 µl mg − 1 , the (Co, Ni) 9 S 8 @CNFs electrode delivers the high initial capacity of 770 mAh g − 1 and retains a desirable capacity of 440 mAh g − 1 (capacity retention of 57% and capacity decay of 0.142% per cycle) after 300 cycles. This is attributable to the effective wetting and penetration of electrolyte across the electrode/electrolyte interface. [ 51 ] However, a further increase in the E/S ratio to 25 leads to a highest initial capacity of 826 mAh g − 1 and unsatisfied capacity retention of 45% after 300 cycles, which arises from the LiPSs dissolution and diffusion in the electrolyte resulting in serious shuttle effect and poor utilization of sulfur. At an even low E/S ratio of 5 µl mg − 1 , the (Co, Ni) 9 S 8 @CNFs/S cell shows a high initial capacity of 582 mAh g − 1 and a reversible capacity of 315 mAh g − 1 after 300 cycles at 0.5 C. The corresponding initial charge-discharge curves are shown in Fig. 5 d at 0.5 C. The remarkably steady discharge plateaus at ~ 1.9 V can be sighted even under the low E/S ratios of 5 µl mg − 1 , implying the relatively fast conversion kinetics and very weak polarization of (Co, Ni) 9 S 8 @CNFs/S. To further enhance the energy density of LSBs, the electrochemical performance of (Co, Ni) 9 S 8 @CNFs/83.3S with 83.3 wt% sulfur content, 5.0 mg cm − 2 areal sulfur loading and 5 µl mg − 1 E/S ratio was also investigated. The sulfur content was determined by TGA ( Figure S11 ). Figure 5 e presents the rate and cycling capabilities of (Co, Ni) 9 S 8 @CNFs/80S and (Co, Ni) 9 S 8 @CNFs/83.3S. Obviously, (Co, Ni) 9 S 8 @CNFs/83.3S shows high discharge capacity at various current densities, but also displays a more stable cycling performance, suggesting high sulfur utilization. Significantly, a high discharge capacity (376 mAh g − 1 ) is presented at 2.0 C, indicating excellent reversibility of high sulfur content and lean electrolyte cell. After being subjected to cycling at different rates, the current density was restored to 0.1 C, (Co, Ni) 9 S 8 @CNFs/83.3S electrode still maintain relatively stable cycling performance, which shows a high discharge capacity (590 mAh g − 1 ) is maintained after 180 cycles at 0.2 C with high CE (> 94%). The corresponding charge-discharge profiles of (Co, Ni) 9 S 8 @CNFs/83.3S and (Co, Ni) 9 S 8 @CNFs/80S cathodes at different current density are displayed in Fig. 5 f and Figure S10c , which further prove the superior rate performance. The results imply that the (Co, Ni) 9 S 8 @CNFs/83.3S cathode has a fast redox reaction. Compared with similar works based on catalyst-anchored carbon cathodes for Li-S batteries, (Co, Ni) 9 S 8 @CNF/S displays excellent cycling stability at high sulfur content and lean electrolyte (Table S2). These results suggest that the (Co, Ni) 9 S 8 @CNFs host delivers potential as efficient sulfur electrocatalysts for LSBs. 4. Conclusion In summary, a rationally structured sulfur host material, i.e. (Co, Ni) 9 S 8 nanoparticles decorated on electrospun carbon nanofibers, was successfully prepared. The experimental results and DFT calculations show that the introduction of Ni into Co 9 S 8 forming (Co, Ni) 9 S 8 leads to effectively capture polysulfides and catalytically promote their redox conversions as compared to Co 9 S 8 , rendering significantly suppressed shuttle effect and fast reaction kinetics. Moreover, the interlinked porous architecture of the (Co, Ni) 9 S 8 @CNFs also contributes to the alleviated volume expansion of sulfur cathode, the rapid electron transfer paths, and abundant active interface areas. As a result, the (Co, Ni) 9 S 8 @CNFs electrode displays excellent rate capacity (490 mAh g − 1 at 2.0 C), high average coulombic efficiency (> 99%). More importantly, the (Co, Ni) 9 S 8 @CNFs electrode with high sulfur content (83.3%) and lean electrolyte (5 uL mg − 1 ) shows large capacity of 590 mAh g − 1 after 180 cycles at 0.2 C. This work not only presents a high-efficiency catalytic sulfur-host material, but also inspires further exploration of other metallic sulfide catalysts for advanced lithium/sodium/potassium-sulfur energy storage systems. Declarations Conflict of Interest The authors declare no conflict of interest. Author Contribution J.H. Wang, C.Y. Chang and Y. Yao designed the conception and experimental process; J.H. Wang and W.R. Zhao wrote the main manuscript text; H. Sun prepared Figure 3e-g; R.R. Li and C.X. Pan supported the preparation and characterizationn of materials. Acknowledgements The authors thank for the support from the Guangdong Basic and Applied Basic Research Foundation (2022A1515110672) and China Postdoctoral Science Foundation (2023M733648). 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Additional Declarations No competing interests reported. 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(b) SEM images of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs. (c) SEM and (d,e) TEM images of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S. (f) STEM and EDS line-scan analysis of (i) (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs and (ii) (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4655461/v1/d8dce2900c636cbdbcb75c6e.png"},{"id":60894369,"identity":"47d10bc8-4b36-433e-9349-56f28ad61584","added_by":"auto","created_at":"2024-07-23 09:35:31","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":319047,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eCharacterization of different materials.\u003c/strong\u003e (a) XRD patterns of the CNFs, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs, and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs. (b) TG curves of CNFs/S, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S, and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S. (c) Raman spectra and (d) N\u003csub\u003e2\u003c/sub\u003e adsorption-desorption isotherm and pore size distributions (inset) of the CNFs, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs, and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4655461/v1/29b4065362a604810c92baf0.png"},{"id":60895102,"identity":"abc3569b-53f9-4685-a66a-cbc1208346df","added_by":"auto","created_at":"2024-07-23 09:43:31","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":541221,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAdsorption properties test.\u003c/strong\u003e (a) Digital photos of Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e solution without and with CNFs, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs, and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs. (b) UV-vis spectra of supernatant of Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e solution after the adsorption test. (c) Co 2p core level and (d) Ni 2p core level of the pristine (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs (top) and precipitate recovered from (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e suspension (bottom). (e) The total density of states (TDOS) for Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e. (f) Calculated binding strength for polysulfides and (g) optimized adsorption configuration for Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e on Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e (311) surfaces.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4655461/v1/aa584c64ee78199707d50fcd.png"},{"id":60895103,"identity":"4c03d93e-6dd2-4e83-8b03-c32b61087b45","added_by":"auto","created_at":"2024-07-23 09:43:31","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":514289,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eKinetics of the catalytic conversion of LiPSs on CNFs, Co\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e9\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eS\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e8\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e@CNFs and (Co, Ni)\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e9\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eS\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e8\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e@CNFs.\u003c/strong\u003e The EIS spectra (a) after first discharge and (b) after 400th discharge at 0.1 C of LSBs assembled by CNFs/S, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S, and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S cathodes. (c) CVs of the three cathodes at the scan rate of 0.1 mV s\u003csup\u003e-1\u003c/sup\u003e. The relationships between the peak current and scan rate for different reaction processes: (d) Peak a, S\u003csub\u003e8\u003c/sub\u003e→Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e, (e) Peak b, Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e→Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003e/Li\u003csub\u003e2\u003c/sub\u003eS, (f) Peak c, Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e→S\u003csub\u003e8\u003c/sub\u003e (4 ≤ x ≤ 8). (g) Relation of Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e6\u003c/sub\u003e conversion reaction with respect to temperatures for CNFs/S, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S, and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S. The EIS spectra (h) and CV (i) curves of CNFs, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs symmetric cell.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4655461/v1/193fdd760fbe7c7fe07a178c.png"},{"id":60894373,"identity":"4ad18730-5df0-4d8c-8353-594116841b5f","added_by":"auto","created_at":"2024-07-23 09:35:32","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":192813,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eElectrochemical performance of different materials.\u003c/strong\u003e (a) Rate-cycling properties and (b) the discharge-charge curves of CNFs/S, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S, and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S. (c) Cycling performance and (d) the discharge-charge curves of three cathodes at 0.5 C with different E/S ratios. (e) Rate-cycling capabilities of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/80.0S and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/83.3S at lean electrolyte (5 μl mg\u003csup\u003e-1\u003c/sup\u003e) operation. (f) The corresponding discharge-charge curves of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/83.3S cathodes.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4655461/v1/0e98ed39202678e67c83c529.png"},{"id":67682546,"identity":"6dc1916d-a044-4150-8fb0-46b8d41c82a5","added_by":"auto","created_at":"2024-10-28 16:14:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3723641,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4655461/v1/3f60ae73-eebf-47da-b818-e9f11326fccc.pdf"},{"id":60894372,"identity":"b7d46856-e9eb-444f-8235-7a0b2dfb44a8","added_by":"auto","created_at":"2024-07-23 09:35:31","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":11010954,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-4655461/v1/472457ee5a424ec9615e3414.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Bimetallic Chalcogenides Enable Highly Efficient Polysulfide Capture and Conversion in Lean-Electrolyte Li-S Batteries","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAmong the alternatives currently proposed to overcome the limitations of lithium-ion batteries, lithium-sulfur batteries (LSBs) have aroused overwhelming attention because of the high theoretical energy density (2567 W h kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), the low cost and eco-friendly of sulfur cathode.\u003csup\u003e[\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e However, the commercial application of LSBs has encountered several intractable technical difficulties.\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e The insulativity (5\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;30\u003c/sup\u003e S cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 25 ℃) of sulfur and its discharge products (Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003e/Li\u003csub\u003e2\u003c/sub\u003eS) leads to a sluggish discharge/charge reaction kinetics and a poor practical capacity.\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e The sulfur cathode is also subjected to the structure collapse arising from the large volume expansion (~\u0026thinsp;80%) when the initial S (2.07 g cm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e) completely converted to Li\u003csub\u003e2\u003c/sub\u003eS (1.66 g cm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e).\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e Most importantly, lithium polysulfides (Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e\u003cem\u003en\u003c/em\u003e\u003c/sub\u003e, 3\u0026le;\u003cem\u003en\u003c/em\u003e\u0026le;8, denoted as LiPSs) bring shuttling effect between the electrodes and electrolyte, resulting in the continual and irreversible loss of active sulfur, rapid capacity fading, and low Coulombic efficiency.\u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e Numerous strategies have been devoted to addressing the above-mentioned issues. Among them, the rational configuration of sulfur host is tremendous importance in enhancing the performance of LSBs.\u003csup\u003e[\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e Carbonaceous hosts can boost the electronic transfer to S and Li\u003csub\u003e2\u003c/sub\u003eS and buffer the volume change of sulfur electrodes as well as suppress the LiPS migration by the physical confinement.\u003csup\u003e[\u003cspan additionalcitationids=\"CR13\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e However, the nonpolar physical restriction is usually too weak to anchor effectively LiPSs, leading to a dissatisfactory cycle stability of LSBs.\u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e The polar host materials, despite their strong chemical absorbability towards the LiPSs, have poor electrical conductivity, resulting in a low sulfur utilization, especially under a high sulfur loading.\u003csup\u003e[\u003cspan additionalcitationids=\"CR18 CR19 CR20\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e Therefore, it is highly required to design a unique sulfur host with excellent electrical conductivity and efficient adsorption effect as well as superior catalytic performance.\u003c/p\u003e \u003cp\u003eRecently, Ni/Co-based metal or bimetallic sulfides have been widely reported as efficient bifunctional electrocatalyst.\u003csup\u003e[\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e Among these metal sulfides, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e-based catalysts presented high catalytic activities due to the unique next-nearest-neighbor metal-metal bonds, the pseudo-metallic electronic structure and suitable adsorption for species.\u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e Moreover, it has been widely used as an electrocatalyst in the water splitting,\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e sensors,\u003csup\u003e[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e and energy storage.\u003csup\u003e[\u003cspan additionalcitationids=\"CR29 CR30 CR31\" citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/sup\u003e Nevertheless, these studies insists that the relatively low ion transport kinetics and poor stability seriously impede further improvement of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e electrocatalyst.\u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e In this regard, metal-incorporation or integration with carbon materials are two effective strategies to enhance the electrocatalytic activity for metal sulfides.\u003csup\u003e[\u003cspan additionalcitationids=\"CR36 CR37\" citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/sup\u003e As for metal incorporating, some investigations have verified that the introduction of Ni into Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e materials (\u003cem\u003ee.g.\u003c/em\u003e, (Co\u003csub\u003e0.64\u003c/sub\u003eNi\u003csub\u003e0.36\u003c/sub\u003e)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e and Co\u003csub\u003e4.7\u003c/sub\u003eNi\u003csub\u003e4.3\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e) is a worthwhile tactic.\u003csup\u003e[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/sup\u003e These studies show that the incorporation of heteroatom metals can modify electronic states and rearrange valence electrons. Additionally, the encapsulation or anchoring of metal nanoparticles in carbon shell/carbon cage is an effective approach to improve the stability of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e electrocatalyst. Motivated by these considerations, it is significant to configurate (Co, M)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e (M\u0026thinsp;=\u0026thinsp;Co, Ni, Fe) nanoparticles uniformly supported on carbon nanofibers as electrocatalytic sulfur host materials. On the one hand, the (Co, M)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e nanoparticles tend to build a chemical bonding with LiPS to suppress the shuttling effect.\u003csup\u003e[\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]\u003c/sup\u003e On the other hand, they also can served as electrocatalysts to facilitate the electron transport and accelerate LiPS conversion, yielding satisfactory cell performance.\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]\u003c/sup\u003e Whereas, the most reported LSBs that demonstrates high capacity and long cycling life usually exhibits a low S content (\u0026lt;\u0026thinsp;70%) and high electrolyte/sulfur ratio (\u0026gt;\u0026thinsp;20 \u0026micro;l mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e).\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]\u003c/sup\u003e Therefore, designing novel host structure is pivotal for achieving commercial applications of LSBs with high sulfur content and lean electrolyte.\u003c/p\u003e \u003cp\u003eHerein, a rational structure composed of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e nanoparticles decorated on the carbon nanofibers ((Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs) as sulfur host is designed to maximize the catalytic effect via electrospun. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea presents the feasible synthesized process of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs. Such composite offers several advantages: (i) the small and uniformly distributed polar nanoparticles can maximize the chemical adsorption capability for solvable LiPSs; (ii) CNTs interlinked into the network structure can prevent sulfur cathode large volume expansion and provide rapid electron transfer; (iii) porous architecture of the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs not only contributes to the permeation of electrolyte and sulfur, but also exposes abundant active interface areas. The theoretical analysis reveals that the introduction of Ni into Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e forming (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e can boost the metallic properties and reinforce the interaction between LiPSs and catalysts. As a results, (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S electrode can achieve high initial discharge capacity (1123 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), outstanding rate capability and cyclic stability (with an average CE of 99.1% and capacity decay per cycle of 0.142% over 300 cycles at 0.5 C) at 20 \u0026micro;L mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Moreover, the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs with high sulfur content (83.3%) and lean electrolyte (5 \u0026micro;L mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) presents 556 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 0.5 C and high capacity of 590 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e after 180 cycles at 0.2 C, demonstrating highly efficient utilization of sulfur and extraordinary potential for practical application of Li-S batteries.\u003c/p\u003e"},{"header":"2. Experimental Section","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Material synthesis\u003c/h2\u003e \u003cp\u003eThe (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e particles decorated on carbon nanofibers ((Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs) were prepared through an electrospinning technique. Typically, 3.0 g PVP (average \u003cem\u003eM\u003c/em\u003e\u003csub\u003ew\u003c/sub\u003e=58000) was dissolved into 12.0 mL H\u003csub\u003e2\u003c/sub\u003eO and ethanol (1:1 by volume) by stirring overnight. Ni(CH\u003csub\u003e3\u003c/sub\u003eCOO)\u003csub\u003e2\u003c/sub\u003e.4H\u003csub\u003e2\u003c/sub\u003eO, Co(CH\u003csub\u003e3\u003c/sub\u003eCOO)\u003csub\u003e2\u003c/sub\u003e.4H\u003csub\u003e2\u003c/sub\u003eO, and CH\u003csub\u003e4\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eS with a molar ratio of 1:2:4 were dissolved in PVP solution. Then the precursor was electrospun at a high voltage of 18 kV, rapid feeding rate of 1.0 mL h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and large receiver distance of 15 cm. The as-collected membrane was annealed at 550 ℃ (5 ℃ min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) in Ar atmosphere for 2 h to obtain (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs. The Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e decorating on carbon nanofibers (Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs) and PVP-derived carbon nanofibers (CNFs) were obtained by a similar method. (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S, CNFs/S were prepared by mixing S power with the samples ((Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs, CNFs), then heated at 155. ℃ for 12. h in Ar atmosphere.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Electrochemical measurements\u003c/h2\u003e \u003cp\u003eThe sulfur cathodes were fabricated by mixing the active materials ((Co, Ni)9S8@CNFs/S, Co9S8@CNFs/S, CNFs/S, 80 wt.%), Super P (10 wt.%), and PVDF (10 wt.%). This mixture was abrasively dispersed in NMP to form slurry. Then the slurry was coated on current collector and the sulfur loading depends on the coating thickness. Li metals were employed as anodes. The electrolyte is 1 M LiTFSI in DOL/DME (1:1 by volume) mixture with 0.1 M LiNO\u003csub\u003e3\u003c/sub\u003e. The electrolyte-to-sulfur (E/S) ratio is about 20 \u0026micro;l mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for the cathode of ~\u0026thinsp;2.8 mg cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e. The electrochemical performances of lean E/S ratios (5, 10, 15, 20, and 25 \u0026micro;l mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) were also estimated. Galvanostatic discharge/charge tests of all cells were measured with a voltage range of 1.4\u0026ndash;2.8 V. Through a PARSTAT3000A-DX electrochemical workstation, the CV curves were conducted under various scan rates (0.1, 0.2, 0.5, and 0.8 mV s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and EIS was performed from 50 mHz to 100 kHz with a voltage amplitude of 10 mV.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Adsorption tests of polysulfides\u003c/h2\u003e \u003cp\u003eLi\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e solution was obtained by mixing Li and element S in electrolyte (1 M LiTFSI in DOL/DME, v:v\u0026thinsp;=\u0026thinsp;1:1) to prepared saturated LiPSs solution. Then 50 mg of (Co,Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs, CNFs powders were added into Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e solution (2000 \u0026micro;L), respectively. After standing for 12 h, the supernatant was taken for UV-vis analysis and the precipitate was dried for XPS tests.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Characterizations\u003c/h2\u003e \u003cp\u003eThe X-ray diffraction patterns were conducted on X\u0026rsquo;Pert 3 Powder with Cu Kα as the radiation. The morphology of the sample was characterized by scanning electron microscope (Nova NanoSEM 450), and transmission electron microscopy. X-ray photoelectron. spectroscopy (XPS) was obtained on a Thermo Scientific K-Alpha.\u003csup\u003e+\u003c/sup\u003e system. The thermogravimetric analysis (TGA) test was performed using a PerkinElmer STA-800 TGA instrument.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Computational details\u003c/h2\u003e \u003cp\u003eDensity functional theory (DFT) was applied to evaluate the LiPSs adsorption. The Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e stripes with (311) exposure were simulated. DFT calculations were carried out using DMol3. package in the Materials. Studio. Perdew-Burke-Ernzerhof (PBE) of general gradient approximation (GGA) was applied to depict the exchange-correlation interaction. Spin-polarized calculation was applied. A 4\u0026times;4\u0026times;1 Monkhorst-Pack mesh k-points was used for the sampling of the Brillouin zone. Moreover, all the results was adopted using spin-polarized calculations.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Morphology of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs\u003c/h2\u003e \u003cp\u003e(Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs were synthesized by a feasible electrospinning technique (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea, Experimental Section). The scanning electron microscope (SEM) of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs reveals that it has 1 D interconnected scaffolds morphology (\u003cb\u003eFigure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e\u003c/b\u003e). The CNFs fiber has a diameter of about 100 nm and its surface contains abundant (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e nanoparticles as well as pores due to the release of CO\u003csub\u003e2\u003c/sub\u003e gas from high-temperature calcination (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). The uniform distribution of the abundantly active (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e nanoparticles on CNFs fiber is verified by the energy dispersive spectrometer (EDS) mapping images (\u003cb\u003eFigure S2\u003c/b\u003e). Moreover, elemental analysis illustrates the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs contains about 16.59 wt% carbon species. The transmission electron microscopy (TEM) of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs further reveal that (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e nanoparticles are uniformly decorated on CNFs skeleton and the diameter of sulfides particles are about 3 nm (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed, \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee). The high-resolution TEM image (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee \u003cb\u003e(Inset)\u003c/b\u003e) displays the clear lattice fringes with 0.281 nm space, matching well with the (311) plane of cubic (Co, M)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e. To confirm the advantages of the fiber as sulfur host, (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S was prepared by S infiltration treatment. The (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S display smooth surfaces as the pores were filled with sulfur (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). Additionally, The STEM image and EDS line-scan analysis of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ef. It demonstrates that sulfur has penetrated into the interspace and pores of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs fibers and uniformly distributed on surface.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Physical properties of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs\u003c/h2\u003e \u003cp\u003eThe crystallographic structure of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs before and after sulfur permeation is investigated by X-ray diffraction (XRD) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea, S3b). Clearly, all the strong diffraction peaks of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs agree well with the cubic (Co, M)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e exhibiting a space group of \u003cem\u003eFm-3m\u003c/em\u003e (PDF #30\u0026ndash;0444), which are consistent with those reported works.\u003csup\u003e[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]\u003c/sup\u003e For (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs, no diffraction line corresponds to the Ni-based sulfides has been observed, implying the successful incorporation of the Ni in the tetrahedral and octahedral sites of the pentlandite structure.\u003csup\u003e[\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]\u003c/sup\u003e This should be attributed to the similar size of Co\u003csup\u003e2+\u003c/sup\u003e (74 pm) and Ni\u003csup\u003e2+\u003c/sup\u003e (69 pm). The contents of Co, Ni and S in the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e detected by an inductively coupled plasma-optical emission spectrometer (ICP-OES) measurements are about 45.05 wt%, 22.59 wt%, and 32.47 wt%, respectively (\u003cb\u003eFigure S3a\u003c/b\u003e). The corresponding molar ratio is approximately 6:3:8, which consists with the molar ratio of raw materials. While the CNFs/S, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S inherit prominent peaks of sublimed sulfur and (Co, M)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e reconfirming the existence of surface sulfur and catalytic host materials (\u003cb\u003eFigure S3b\u003c/b\u003e), in line with the TEM results. The sulfur content of the three host materials is measured to be 80 wt% by thermogravimetric analysis (TGA) tests (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec illustrates the Raman spectrum of CNFs, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs hosts. The ratios of the intensities of the G-band at 1590 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and the D-band at 1350 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (\u003cem\u003eI\u003c/em\u003e\u003csub\u003eG\u003c/sub\u003e/\u003cem\u003eI\u003c/em\u003e\u003csub\u003eD\u003c/sub\u003e) for the three hosts are calculated to be 0.823, 0.900, and 0.965, respectively. The higher ratio of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e-based CNFs compound indicates higher graphitization degree than that of CNFs,\u003csup\u003e[\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]\u003c/sup\u003e which may be due to the rapid electron-transfer effect between Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e and carbon.\u003csup\u003e[\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]\u003c/sup\u003e The outstanding graphitized carbon is favorable to boost the electronic conductivity of the S host and further reinforce its utilization during cycling processes.\u003csup\u003e[\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]\u003c/sup\u003e The surface resistances of host materials were tested by a four-point probes resistivity measurement system (RTS-9). As displayed in \u003cb\u003eFigure S3c\u003c/b\u003e, the resistivities of the three hosts are about 148, 76, and 39 Ω cm, respectively. The high electrical conductivity of (Co,Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs contributes to rapid electron transfer to remedy the insulativity of sulfur and its discharge products.\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e The specific surface and pore structures of CNFs, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs, and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs were investigated by Brunauer EmmettTeller (BET) method (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed). The results show that (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs have a higher specific surface area of 89.48 m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and a total pore volume of 0.36 cm\u003csup\u003e3\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e than those of CNFs (51.38 m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 0.17 cm\u003csup\u003e3\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs (87.48 m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 0.33 cm\u003csup\u003e3\u003c/sup\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). The high surface area and large pore volume of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs can provide a high sulfur loading and facilitate electrolyte infiltration.\u003csup\u003e[\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.3 LiPSs adsorption and kinetics characterization\u003c/h2\u003e \u003cp\u003eThe strong interaction between (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs and polysulfides (LiPSs) was examined systematically by visual adsorption experiments and UV-vis tests. The same amount of three host composites was separately added into LiPSs solution, which were then placed in glove box for 12 h (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). The LiPSs solution before and after adsorbing was measured by UV-vis tests (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb). The peak located at 260 nm is attributed to the S\u003csub\u003e8\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e/S\u003csub\u003e6\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e species, the sharp peak at 350 nm is assigned to S\u003csub\u003e6\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e/S\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e species, and the wide peak at about 490 nm is ascribed to S\u003csub\u003e4\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e species.\u003csup\u003e[\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e]\u003c/sup\u003e Obviously, (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs completely decolors the LiPSs solution after 12 h and significantly removes the characteristic peak of Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea), confirming that the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs has strong chemisorption towards LiPSs. The adsorption mechanism was further probed by XPS analysis. The peak intensity of S element in the XPS spectrums of CNFs/Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e, and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e is stronger than that before soaking Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e (\u003cb\u003eFigure S4\u003c/b\u003e), which implies that large amounts of LiPSs were adsorbed. The peaks of S2p located at 162.18 and 164.08 eV should belong to the terminal sulfur (S\u003csub\u003eT\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e) and bridging sulfur (S\u003csub\u003eB\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e), respectively (\u003cb\u003eFigure S5a\u003c/b\u003e).\u003csup\u003e[\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e]\u003c/sup\u003e The other peaks at 166.98 and 169.28 eV can be assigned to the thiosulfate and polythionate. The presence of the sulfates has a positive mediator effect on the conversion from long-chain to short-chain LiPSs.\u003csup\u003e[\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e]\u003c/sup\u003e Additionally, S-Co and S-Ni bonds at about 163.62 and 161.37 eV corroborates the synergetic adsorption effect of Co and Ni sites.\u003csup\u003e[\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e]\u003c/sup\u003e Compared with the original Co 2p\u003csub\u003e3/2\u003c/sub\u003e core level, electron binding energies of Co\u003csup\u003e3+\u003c/sup\u003e and Co\u003csup\u003e2+\u003c/sup\u003e in (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e slightly shift to lower energies (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec), implying the electron transfer from Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e to Co. Meanwhile, the proportion of Co\u003csup\u003e3+\u003c/sup\u003e from 34.2% decreases to 27.0% after adsorbing Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e solution, which originates form the partial reduction of Co\u003csup\u003e3+\u003c/sup\u003e induced by the charge transfer from S\u003csub\u003ex\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e.\u003csup\u003e[\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e]\u003c/sup\u003e Similarly, the binding energy of Ni 2p peaks is reduced more significantly in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed, and the content of Ni\u003csup\u003e3+\u003c/sup\u003e from 51.3% decreases sharply to 37.5% after adsorbing Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e, indicating that Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e interact more strongly with Ni than Co sites of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e.\u003csup\u003e[\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]\u003c/sup\u003e Co 2p core level of the Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs and Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003ex\u003c/sub\u003e were also investigated (\u003cb\u003eFigure S5b\u003c/b\u003e, \u003cb\u003eS5c\u003c/b\u003e), the proportion of Co\u003csup\u003e3+\u003c/sup\u003e decreases significantly and the content of Co\u003csup\u003e2+\u003c/sup\u003e increases obviously. Meanwhile, the binding energy of Co 2p peaks is reduced significantly. These XPS spectra analysis together with the adsorption experiments support the fact that (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs exhibits a strong chemical affinity towards LiPSs, which is essential for a stable cycle of battery.\u003c/p\u003e \u003cp\u003eTo further rationalize the electrocatalytic activity of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs at the atomic level, the density functional theory (DFT) calculation was carried out. The total density of states (TDOS) of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee. The introducing of Ni atoms contributes to the energy levels of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e shifting to the Fermi level, which suggests that the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e has better conductivity than Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e.\u003csup\u003e[\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e]\u003c/sup\u003e According to calculation in \u003cb\u003eFigure S6 (a, b)\u003c/b\u003e, the band gap of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e (0.006 eV) is much lower than that of the Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e (0.024 eV), further indicating the enhancement of metallicity. The TDOS analysis of polysulfides adsorbed on the (311) surfaces of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e in \u003cb\u003eFigure S6 (c, d)\u003c/b\u003e shows that the conductivity of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e weakens after adsorption of polysulfides while (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e is almost unchanged.\u003csup\u003e[\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]\u003c/sup\u003e Once again proving there is excellent electronic conductivity of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ef and \u003cb\u003eFigure S7\u003c/b\u003e display the Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e, Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e6\u003c/sub\u003e, and Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e adsorption configuration on Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e (311) surfaces. The binding energy in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eg verifies that polysulfide molecules are adsorbed more strongly on the surface of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e than Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e, implying that the introduction of Ni is helpful to suppress polysulfides shuttle effect.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo investigate the transformation kinetics of polysulfides, various electrochemical measurements were performed. The electrochemical impedance spectra (EIS) tests of LSBs after first discharge and 400th discharge at 0.1 C were conducted (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, b), and the fitted data were showed in \u003cb\u003eTable \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e\u003c/b\u003e. After first cycle, both the charge-transfer resistance (\u003cem\u003eR\u003c/em\u003e\u003csub\u003ect\u003c/sub\u003e) and the resistance of the deposited Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003e/Li\u003csub\u003e2\u003c/sub\u003eS on the electrode surface (\u003cem\u003eR\u003c/em\u003e\u003csub\u003el\u003c/sub\u003e)\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs are slight larger than CNFs (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea). After 400 cycles, the semicircle in high frequency region gradually become smaller, accompanied with relatively large semicircle in medium-high frequency region (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb). It means that the deposition of the insoluble Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003e/Li\u003csub\u003e2\u003c/sub\u003eS layer of three composites during the cycling processes is induced.\u003csup\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/sup\u003e After cycling, as shown in \u003cb\u003eTable \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e\u003c/b\u003e, the values of \u003cem\u003eR\u003c/em\u003e\u003csub\u003ect\u003c/sub\u003e and \u003cem\u003eR\u003c/em\u003e\u003csub\u003el\u003c/sub\u003e after 400th cycle are decreased sharply to 12.9 Ω and 12.0 Ω, 23.1 Ω and 7.4 Ω for Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S cathodes, respectively. It is verified (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs possesses outstanding electronic conductivity, which is consistent with the above TDOS results. Additionally, CNFs/S electrode exhibits higher \u003cem\u003eR\u003c/em\u003e\u003csub\u003ect\u003c/sub\u003e resistance after 400th cycling, which possibly caused by the accumulation of Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003e and Li\u003csub\u003e2\u003c/sub\u003eS. The discharge products (Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003e and Li\u003csub\u003e2\u003c/sub\u003eS) with low conductivity are physically covered on the surface of CNFs/S electrode, which gives rise to slow electron transfer, enlarged impedance and cracked electrode because of the shuttle effect. On the other hand, for (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs electrodes, the low resistance can be ascribed to the rapid reversible transformation between Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003e/Li\u003csub\u003e2\u003c/sub\u003eS passivation layer and sulfur as well as fast charge transfer during cycling process, owing to the strong chemical adsorption.\u003csup\u003e[\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e]\u003c/sup\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec presents the typical CV curves of the three kinds of electrodes in window of 1.4\u0026thinsp;~\u0026thinsp;2.8 V. Two cathodic peaks at. 2.36 V (Peak a) and. 2.04 V (Peak b) correspond to the stepwise reduction from Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e/Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e6\u003c/sub\u003e to Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e, and then to Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003e/Li\u003csub\u003e2\u003c/sub\u003eS. Correspondingly, a sharp anodic peak at 2.42 V (Peak c) is associated with the reverse reaction.\u003csup\u003e[\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eCV tests were also conducted under different scan rates to demonstrate the effect of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs on the redox reaction kinetics of intermediate LiPSs (\u003cb\u003eFigure S8\u003c/b\u003e). As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed-f, it can be found that a linear relationship between redox peak currents (\u003cem\u003eI\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e) and the square root of scan rate (\u003cem\u003ev\u003c/em\u003e\u003csup\u003e\u003cem\u003e0.5\u003c/em\u003e\u003c/sup\u003e), implying the rate-determining step dependents on the diffusion rate of LiPSs.\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e The Li\u003csup\u003e+\u003c/sup\u003e ion diffusion process can accord with the Randles-Sevcik equation:\u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e]\u003c/sup\u003e\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$${I}_{p}=\\left(2.69\\times {10}^{5}\\right).{n}^{1.5}\\cdot A\\cdot {D}_{Li}^{0.5}{v}^{0.5}{C}_{\\text{L}\\text{i}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe Li\u003csup\u003e+\u003c/sup\u003e ion diffusion rate (\u003cem\u003eD\u003c/em\u003e\u003csub\u003eLi\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e) is positively correlated with the slope of (\u003cem\u003eI\u003c/em\u003e\u003csub\u003ep\u003c/sub\u003e/\u003cem\u003ev\u003c/em\u003e\u003csup\u003e0.5\u003c/sup\u003e) due to the \u003cem\u003en\u003c/em\u003e, \u003cem\u003eA\u003c/em\u003e, and \u003cem\u003eC\u003c/em\u003e\u003csub\u003eLi\u003c/sub\u003e can be seen as constants in LSBs. Obviously, the slopes of the. reduction/oxidation peaks (peak a, b, c) of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S electrodes are higher than that of CNFs/S, especially (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S, verifying the rapid diffusion process of Li\u003csup\u003e+\u003c/sup\u003e ions. The high \u003cem\u003eD\u003c/em\u003e\u003csub\u003eLi\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs should be attributed to the modified electronic structure induced by the introduction of Ni element, leading to outstanding catalytic performance. To further evaluate the catalytic kinetics of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S electrodes, the activation energy is calculated based on the transformation from Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e to Li\u003csub\u003e2\u003c/sub\u003eS through temperature-dependent CV tests (\u003cb\u003eFigure S9a-c\u003c/b\u003e).\u003csup\u003e[\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e]\u003c/sup\u003e According to the Arrhenius equation, the peak current (\u003cem\u003ej\u003c/em\u003e) is positively correlated with the reaction rate.\u003csup\u003e[\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]\u003c/sup\u003e By fitting the slops (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eg), the barrier potential of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs (15.86 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) is lower than that of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs (16.34 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and CNFs (19.43 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), implying easier to catalytic conversion of polysulfides. The polarization voltage gap (peak b and c) reveals the excellent catalytic property of Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs species, especially (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs (\u003cb\u003eFigure S9d\u003c/b\u003e).\u003c/p\u003e \u003cp\u003ePotential polysulfides conversion kinetics enhancements were also investigated by the CNFs, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs, and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs symmetrical cells. Compared with CNFs, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs symmetric cells present smaller charge-transfer resistances (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eh), hinting the improved LiPSs conversion kinetics. As shown by the CV profiles in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ei, all symmetric cells present four main peaks at -0.46, -0.06, 0.07, and 0.46 V. The (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs symmetric cell exhibits the largest current response, further suggesting its rapid polysulfides conversion kinetics.\u003csup\u003e[\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e]\u003c/sup\u003e These results collectively validate that the uniform distributions of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e nanoparticles on carbon nanofibers will greatly facilitate the conversion rate of sulfur and decrease polarization during cycling process. Meanwhile, they also demonstrate that the reversible conversion of LiPSs can significantly accelerate by the introduction of Ni in Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Electrochemical properties of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S electrode\u003c/h2\u003e \u003cp\u003eFurther electrochemical evaluations were carried out for different electrodes by CR2032 coin cells. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea presents the rate capacity of CNFs/S, Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S, and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S cathodes at 0.1 to 5.0 C and returning to 0.1 C (1 C\u0026thinsp;=\u0026thinsp;1675 mA g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, E/S\u0026thinsp;=\u0026thinsp;20 \u0026micro;l mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e). Evidently, the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S cathode shows superior rate performance than the other two electrodes under different rates. Based on (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S, at 0.1 C, 0.2 C, 0.5 C, 1.0 C, and 2.0 C, the discharge specific capacity is as high as 976, 850, 704, 584, and 485, respectively. Even current density is up to 5.0 C, a reversible capacity of 342 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is presented. The excellent rate of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S electrode benefits from the strong adsorption-catalysis interaction between (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs and LiPSs. The Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S shows a similar rate performance but lower capacity. and utilization of S. In sharp contrast, the CNFs/S exhibits low rate. capacity. of only 160 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at the 5.0 C. This kinetic. difference. can also be reflected from the voltage profiles (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb and \u003cb\u003eFigure S10a, b\u003c/b\u003e). For (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs electrode, a remarkably steady discharge plateau at ~\u0026thinsp;1.9 V representing the conversion from long-chain LiPSs to insoluble Li\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003e/Li\u003csub\u003e2\u003c/sub\u003eS can be shown even under 5.0 C. In contrast, CNFs/S has no obvious discharge plateau at 2.0 C, and it also presents a larger polarization at each current density. When the current density returns back to 0.1 C after diverse rates, the discharge behavior can be self-healed very well for catalytic electrodes, especially (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S, which recurred 95% of its discharge capacity of second cycle suggesting excellent catalytic activity and reversibility. By comparison, CNFs/S recovered to 700 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, only 77% of its discharge capacity of second cycle. So again, the results demonstrate the higher catalytic ability and the faster redox kinetics of the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs than CNFs/S.\u003c/p\u003e \u003cp\u003eIt is essential to satisfy the practical application of LSBs with low electrolyte/sulfur (E/S) ratio.\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e The cycling performances of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs under S loading 2.8 mg cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e with different E/S ratios have been investigated at 0.5 C. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec, it still obtains decent cycling performance at 15 and 20 \u0026micro;l mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Significantly, when the E/S\u0026thinsp;=\u0026thinsp;20 \u0026micro;l mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs electrode delivers the high initial capacity of 770 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and retains a desirable capacity of 440 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (capacity retention of 57% and capacity decay of 0.142% per cycle) after 300 cycles. This is attributable to the effective wetting and penetration of electrolyte across the electrode/electrolyte interface.\u003csup\u003e[\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e]\u003c/sup\u003e However, a further increase in the E/S ratio to 25 leads to a highest initial capacity of 826 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and unsatisfied capacity retention of 45% after 300 cycles, which arises from the LiPSs dissolution and diffusion in the electrolyte resulting in serious shuttle effect and poor utilization of sulfur. At an even low E/S ratio of 5 \u0026micro;l mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S cell shows a high initial capacity of 582 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and a reversible capacity of 315 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e after 300 cycles at 0.5 C. The corresponding initial charge-discharge curves are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ed at 0.5 C. The remarkably steady discharge plateaus at ~\u0026thinsp;1.9 V can be sighted even under the low E/S ratios of 5 \u0026micro;l mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, implying the relatively fast conversion kinetics and very weak polarization of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/S.\u003c/p\u003e \u003cp\u003eTo further enhance the energy density of LSBs, the electrochemical performance of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/83.3S with 83.3 wt% sulfur content, 5.0 mg cm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e areal sulfur loading and 5 \u0026micro;l mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e E/S ratio was also investigated. The sulfur content was determined by TGA (\u003cb\u003eFigure S11\u003c/b\u003e). Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ee presents the rate and cycling capabilities of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/80S and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/83.3S. Obviously, (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/83.3S shows high discharge capacity at various current densities, but also displays a more stable cycling performance, suggesting high sulfur utilization. Significantly, a high discharge capacity (376 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) is presented at 2.0 C, indicating excellent reversibility of high sulfur content and lean electrolyte cell. After being subjected to cycling at different rates, the current density was restored to 0.1 C, (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/83.3S electrode still maintain relatively stable cycling performance, which shows a high discharge capacity (590 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) is maintained after 180 cycles at 0.2 C with high \u003cem\u003eCE\u003c/em\u003e (\u0026gt;\u0026thinsp;94%). The corresponding charge-discharge profiles of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/83.3S and (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/80S cathodes at different current density are displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ef and \u003cb\u003eFigure S10c\u003c/b\u003e, which further prove the superior rate performance. The results imply that the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs/83.3S cathode has a fast redox reaction. Compared with similar works based on catalyst-anchored carbon cathodes for Li-S batteries, (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNF/S displays excellent cycling stability at high sulfur content and lean electrolyte (Table S2). These results suggest that the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs host delivers potential as efficient sulfur electrocatalysts for LSBs.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eIn summary, a rationally structured sulfur host material, i.e. (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e nanoparticles decorated on electrospun carbon nanofibers, was successfully prepared. The experimental results and DFT calculations show that the introduction of Ni into Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e forming (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e leads to effectively capture polysulfides and catalytically promote their redox conversions as compared to Co\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e, rendering significantly suppressed shuttle effect and fast reaction kinetics. Moreover, the interlinked porous architecture of the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs also contributes to the alleviated volume expansion of sulfur cathode, the rapid electron transfer paths, and abundant active interface areas. As a result, the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs electrode displays excellent rate capacity (490 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 2.0 C), high average coulombic efficiency (\u0026gt;\u0026thinsp;99%). More importantly, the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs electrode with high sulfur content (83.3%) and lean electrolyte (5 uL mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) shows large capacity of 590 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e after 180 cycles at 0.2 C. This work not only presents a high-efficiency catalytic sulfur-host material, but also inspires further exploration of other metallic sulfide catalysts for advanced lithium/sodium/potassium-sulfur energy storage systems.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of Interest\u003c/h2\u003e \u003cp\u003eThe authors declare no conflict of interest.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eJ.H. Wang, C.Y. Chang and Y. Yao designed the conception and experimental process; J.H. Wang and W.R. Zhao wrote the main manuscript text; H. Sun prepared Figure 3e-g; R.R. Li and C.X. Pan supported the preparation and characterizationn of materials.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThe authors thank for the support from the Guangdong Basic and Applied Basic Research Foundation (2022A1515110672) and China Postdoctoral Science Foundation (2023M733648). 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A\u0026nbsp;\u003c/em\u003e\u003cstrong\u003e2017,\u003c/strong\u003e \u003cem\u003e5\u003c/em\u003e (34), 18020-18028.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-applied-electrochemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jach","sideBox":"Learn more about [Journal of Applied Electrochemistry](http://link.springer.com/journal/10800)","snPcode":"10800","submissionUrl":"https://submission.nature.com/new-submission/10800/3","title":"Journal of Applied Electrochemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"(Co, Ni)9S8@CNFs, electrospun, catalyst, high sulfur content, lean electrolyte","lastPublishedDoi":"10.21203/rs.3.rs-4655461/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4655461/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe commercialization of Li-S batteries is obstructed by the sluggish redox kinetics and serious shuttling behaviors of polysulfides. Herein, we report a rationally structured sulfur host material to tackle these issues, i.e. (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e nanoparticles uniformly decorated on electrospun carbon nanofibers. The (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e nanoparticles are demonstrated to effectively capture polysulfides and catalytically promote their redox conversions. Moreover, the interlinked porous architecture of (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs also contributes to alleviate volume expansion of sulfur cathode and provide the rapid electron transfer paths and Li-ion diffusion channels. Benefiting from these attributes, the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs cathode delivers an excellent rate capability and long cycling stability (capacity decay of 0.142% per cycle over 300 cycles). Additionally, the (Co, Ni)\u003csub\u003e9\u003c/sub\u003eS\u003csub\u003e8\u003c/sub\u003e@CNFs with high sulfur content (83.3%) and lean electrolyte (5 μL mg\u003csup\u003e-1\u003c/sup\u003e) shows high capacity of 556 mAh g\u003csup\u003e-1\u003c/sup\u003e at 0.5 C and 590 mAh g\u003csup\u003e-1\u003c/sup\u003e after 180 cycles at 0.2 C, demonstrating highly efficient utilization of sulfur and extraordinary potential for practical application of Li-S batteries.\u003c/p\u003e","manuscriptTitle":"Bimetallic Chalcogenides Enable Highly Efficient Polysulfide Capture and Conversion in Lean-Electrolyte Li-S Batteries","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-23 09:35:25","doi":"10.21203/rs.3.rs-4655461/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-09-21T23:36:32+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-16T06:54:13+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-16T03:40:40+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-06T18:14:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"196619735659808539496862638778600122667","date":"2024-08-29T09:13:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"278841508676710073357451282440999562708","date":"2024-08-27T06:48:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"27997753855729942876756599873179722891","date":"2024-08-26T12:53:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"96940084844306091841711827229961226257","date":"2024-08-26T05:09:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"214001000833354611354371040698399635139","date":"2024-08-26T03:53:40+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-01T13:42:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"26337855237659898734405684912235666729","date":"2024-08-01T05:40:54+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-31T15:23:25+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-06T16:50:04+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-06-29T12:06:52+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Applied Electrochemistry","date":"2024-06-28T14:38:19+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-applied-electrochemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jach","sideBox":"Learn more about [Journal of Applied Electrochemistry](http://link.springer.com/journal/10800)","snPcode":"10800","submissionUrl":"https://submission.nature.com/new-submission/10800/3","title":"Journal of Applied Electrochemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"b693f63b-1fd3-418e-b0e6-8d85be3ae13d","owner":[],"postedDate":"July 23rd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-10-28T16:10:14+00:00","versionOfRecord":{"articleIdentity":"rs-4655461","link":"https://doi.org/10.1007/s10800-024-02219-4","journal":{"identity":"journal-of-applied-electrochemistry","isVorOnly":false,"title":"Journal of Applied Electrochemistry"},"publishedOn":"2024-10-26 15:57:26","publishedOnDateReadable":"October 26th, 2024"},"versionCreatedAt":"2024-07-23 09:35:25","video":"","vorDoi":"10.1007/s10800-024-02219-4","vorDoiUrl":"https://doi.org/10.1007/s10800-024-02219-4","workflowStages":[]},"version":"v1","identity":"rs-4655461","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4655461","identity":"rs-4655461","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}