Novel NiCo2S4 nanorods arrays grown on carbon nanofibers as high-performance anodes for sodium ion batteries

Novel NiCo2S4 nanorods arrays grown on carbon nanofibers as high-performance anodes for sodium ion 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 Novel NiCo 2 S 4 nanorods arrays grown on carbon nanofibers as high-performance anodes for sodium ion batteries Xiaowei Yang, Tongxiang Cai, Zhongran Yao, Guojie Chao This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4671092/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Novel NiCo 2 S 4 nanorods arrays are uniformly grown onto carbon nanofibers (NiCo 2 S 4 @CNF) through a facile hydrothermal approach. The elaborate designed composite structure ensures that the NiCo 2 S 4 nanorods arrays are uniformly dispersed on the surfaces of carbon nanofibers (CNF) and tightly bonded with each other. The conductive networks of CNF can facilitate the electron transport at the interfaces and ions diffusion to readily react with NiCo 2 S 4 , thus leading to increased sodium storage. In view of this, NiCo 2 S 4 @CNF reveals a high reversible capacity (683.6 mAh g − 1 at 0.1 A g − 1 ) and long-term cycle stability (only attenuates 0.07% in each cycle after 400 times). This work provides a simple and efficient strategy for synthesizing high-performance sodium ion battery electrodes. Sodium batteries NiCo2S4 nanorods arrays Anode Carbon nanofibers Structural stability Figures Figure 1 Figure 2 Figure 3 Introduction With the growing energy demand and serious environmental issues, sodium-ion batteries (SIBs) have become promising substitutes for lithium-ion batteries (LIBs) in large-scale energy storage systems due to their abundant resources and low-cost of precursors. As the commercial anodes for LIBs, graphite has excellent discharge specific capacity and cycling stability[ 1 ]. However, the electrode of graphite is not suitable for sodium-ion batteries[ 2 , 3 ]. Therefore, there is an urgent need to make breakthroughs in finding suitable anode materials for SIBs. As one of the transition metal sulfides, NiCo 2 S 4 electrode with excellent theoretical capacity and superior redox reversibility has been widely used in the field of energy storage[ 4 – 6 ]. The NiCo 2 S 4 have received extensive research in recent years, mainly owing to their promising sodium storage behavior when it was utilized as an anode for SIBs[ 7 ]. For instance, Shen et al.[ 4 ] synthesized a self-supporting Ni@NiCo 2 S 4 anode for SIBs with grown bimetallic NiCo 2 S 4 on nickel foam. The three-dimensional hierarchical Ni@NiCo 2 S 4 electrode exhibits high capacity and excellent cycling stability (90.65%, 100 cycles). Additionally, Li et al. [ 8 ] designed a kind of NiCo 2 S 4 nanodots (~ 9 nm) in N-doped carbon as anode for SIBs. The as-prepared NiCo 2 S 4 @NC electrode delivers excellent sodium storage performance (a stable capacity of 570.1 mAh g − 1 at 0.2 A g − 1 ) in the ether-based electrolyte. However, some problems still exist, such as aggregation of intermediates and large volume changes, leading to rapid capacity fading and poor cycle life, limiting the further development of NiCo 2 S 4 electrodes. Herein, NiCo 2 S 4 nanorods arrays are uniformly grown onto carbon nanofibers (NiCo 2 S 4 @CNF) through a facile approach of hydrothermal. The NiCo 2 S 4 nanorods arrays are uniformly dispersed on the surfaces of carbon nanofibers (CNF) and tightly bonded with each other. The CNF nanofibers strengthen the conductive network of the composites, which is beneficial to the transfer of sodium ions and electrons. The increased electrode specific surface area and active sites improve the utilization efficiency of active materials. Benefiting from the synergism between the NiCo 2 S 4 nanorods arrays and carbon nanofibers such as improved electronic conductivity and shortened ion diffusion pathways, the NiCo 2 S 4 @CNF electrodes exhibit excellent electrochemical characteristics as an anode in SIBs. Experimental section Materials preparation Firstly, CNF nanofibers were synthesized through electrospinning of PAN solution, followed by carbonization procedure. NiCo 2 S 4 @CNF composites were synthesized by a hydrothermal reaction. Briefly, Ni(NO 3 ) 2 ·6H 2 O (1 mmol), Co(NO 3 ) 2 ·6H 2 O (2 mmol), urea (4 mmol) and thiourea (8 mmol) were dissolved in ultra-purified water (30 mL). The above solution was then poured into a 50 mL autoclave with a piece of CNF membrane added into the mixed solution, which was kept at 160 ℃ for 6 h. For comparison, pure NiCo 2 S 4 was prepared by a similar procedure without adding CNF nanofibers membrane. Materials characterization X-ray diffraction (XRD) pattern was obtained on an X-ray diffractometer (XRD, DX-2700) with Cu Kα radiation (λ = 1.5406 Å) at 40 kV and 30 mA. Elemental composition and valence state of the samples were detected by X-ray photoelectrons (XPS, ESCLAB 250Xi). The morphologies of the samples were characterized using field-emission scanning electron microscope (FESEM, Hitachi S-4800). Electrochemical measurements The active material, acetylene black and polyvinylidene fluoride were mixed in a weight ratio of 8:1:1 and N-methyl-2-pyrrolidone was worked as the solvent. Then, the formed slurry was coated on aluminum foil and dried at 80 ℃ for 12 h. The CR2032 type batteries were assembled in a super purification glove box. Pure Na metal foil was worked as a counter electrode, glass microfiber (Whatman® GF/D) was used as a separator, and 1.0 M NaClO 4 dissolved in DEC/EC (1:1, in volume) was worked as electrolyte. The cyclic voltammetry (CV) test was measured using an electrochemical workstation (CS-2350H, CORRTEST). The cells were cycled with a LAND battery measurement system between 0.01 V and 3.0 V. Results and discussion SEM images of Fig. 1 a shows the microstructure of as-obtained CNF nanofibers sample. The nanofibers of CNF exhibit clean surfaces with the diameters of 200–300 nm. It can be observed that CNF is composed of large amounts of fibers with well-distributed diameter and thickness, which ensures the uniform growth and distribution of NiCo 2 S 4 particles. The NiCo 2 S 4 nanorods arrays are generated around the carbon fibers after hydrothermal reaction, and the morphological changes of the carbon fibers before and after hydrothermal treatment are shown in Fig. S1 . As shown in Fig. 1 b and c, NiCo 2 S 4 nanorods arrays are dispersed on top of CNF and tightly intertwined with each other to form NiCo 2 S 4 @CNF electrodes. The dispersed nanorods arrays of NiCo 2 S 4 can exposed more active sites for sodium and the conductive network of CNF ensures faster electrolyte transport. Furthermore, the energy dispersive spectroscope (EDS) spectrum and corresponding mapping images reveal the uniform distribution of C, S, Ni and Co elements in the NiCo 2 S 4 @CNF sample (Fig. 1 d). The crystalline feature of as-obtained samples was elucidated by XRD in Fig. 2 a. It is noticed that both the NiCo 2 S 4 @CNF and pure NiCo 2 S 4 display same diffraction peaks located at 2θ = 23.8°, 27.1°, 31.9°, 38.6°, 47.7°, 50.8°, 55.6°, 65.4°, 69.6° and 78.5°, respectively. All the characteristic peaks can be indexed to the standard PDF card of NiCo 2 S 4 (JCPDS 01-073-1704)[ 9 ]. The peak intensity of NiCo 2 S 4 @CNF is slightly weaker than that of NiCo 2 S 4 , mainly due to the composite effect of carbon fiber membrane. As shown in Fig. 2 b, the chemical state of NiCo 2 S 4 @CNF electrode was investigated by X-ray photoelectron spectroscopy (XPS) measurements. The survey spectrum manifests that NiCo 2 S 4 @CNF contains Ni, Co, S, O and C elements. The oxygen content in NiCo 2 S 4 @CNF is attributed to the natural properties of carbon fibers and the exposure of sample to air. High-resolution C 1 s signal of NiCo 2 S 4 @CNF in Fig. 2 c can be fitted into a series of peaks located at 284.8, 285.5, 286.2 and 288.9 eV, which correspond to C-C, C-O, C = O and O-C = O bonds, respectively. In the S 2p spectrum of Fig. 2 d, the peaks located at 161.4 eV and 162.5 eV are assigned to S 2p 3/2 and S 2p 1/2 orbitals of S 2− . Ni-S and Co-S can be also observed, confirming the formation of multi-metal sulfides. The Ni 2p spectrum in Fig. 2 e reveals two strong peaks located at 856.2 eV and 873.9 eV, corresponding to Ni 2p 3/2 and Ni 2p 1/2 , respectively[ 10 ]. From the Co 2p spectrum of Fig. 2 f, strong peaks at 781.5 eV and 796.8 eV correspond to Co 2p 3/2 and Co 2p 1/2 , respectively. Furthermore, the corresponding elemental analysis is summarized in Table S1 . These results are in accordance with the reported characteristics of NiCo 2 S 4 . The sodium ion storage characteristics of NiCo 2 S 4 @CNF electrodes were investigated in CR2032 coin type half-cell, as shown in Fig. 3 . Figure 3 a exhibits the rate performance of NiCo 2 S 4 and NiCo 2 S 4 @CNF samples in the range of current densities from 0.1 A g − 1 to 5.0 A g − 1 . It is obvious that the NiCo 2 S 4 @CNF electrode delivers a higher discharge specific capacity than NiCo 2 S 4 , which are 683.6, 551.9, 470.2, 403.6, 345.1 and 256.7 mAh g − 1 at the current densities of 0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 A g − 1 , respectively. As for the NiCo 2 S 4 electrode, only a specific capacity of 478.8 mAh g − 1 released at a current of 0.1 A g − 1 , and it decayed rapidly. When the current density increases to 1.0 A g − 1 , there is almost no capacity. Figure 3 b shows the galvanostatic charge and discharge (GCD) curves of the NiCo 2 S 4 @CNF electrode at a current density of 0.1 A g − 1 . The NiCo 2 S 4 @CNF electrode represents an initial capacity of 756.2 mAh g − 1 and secondary capacity of 683.6 mAh g − 1 , with a high initial coulombic efficiency (ICE) of 90.4%. As shown in Fig. 3 c, the EIS measurement was conducted to analyze the kinetic feature of NiCo 2 S 4 @CNF electrode toward sodium ions. The semicircle district represents the resistance of charge transfer (R ct ), which is related to the electrochemical kinetics of the electrodes. Meanwhile, the oblique line represents the Warburg impedance (Zw), which is determined by the diffusion of sodium ions in the electrode. Based on the equivalent circuit (the inset in Fig. 3 c), the R ct of NiCo 2 S 4 @CNF and NiCo 2 S 4 are calculated to 187.6 Ω and 392.7 Ω respectively. The smaller R ct value of NiCo 2 S 4 @CNF indicates lower charge transfer resistance and higher conductivity. Figure 3 d reveals the first three CV curves of NiCo 2 S 4 @CNF electrode in the potential range of 0.01-3 V at a scan rate of 0.1 mV s − 1 . In the first cathodic scan, two peaks located at ∼0.5 V should be assigned to the reversible formation of solid electrolyte interphase (SEI) film and activation process of Na + insertion into NiCo 2 S 4 @CNF. The subsequential anodic peaks at 1.88 V correspond to the extraction of Na + and the formation of NiS and CoS. In the following scan, two pair of conspicuous peaks reflected the reverse process between NiS/CoS and Na. The profile of successive cycles fits well, confirming the excellent stability of the electrode. The long-term cycling stability of the NiCo 2 S 4 @CNF electrode was also evaluated under high current density and the result is shown in Fig. 3 e. At a high current density of 2.0 A g − 1 , the reversible capacity still maintained at 283.2 mAh g − 1 after 400 cycles with the CE over 99%, indicating the superior stability of NiCo 2 S 4 @CNF. In addition, the comparison between the reported literatures on NiCo 2 S 4 materials in sodium ion batteries in Table S2 also confirms the superiority of NiCo 2 S 4 @CNF[ 11 – 16 ]. Conclusions In summary, NiCo 2 S 4 nanorods arrays have been uniformly grown onto carbon nanofibers through a facile approach of hydrothermal. Benefiting from the robust structure and excellent conductivity of 3D novel architecture, it can effectively mitigate the volume expansion effect of NiCo 2 S 4 electrode during cycling and accelerate the ion/electron transport. The synergistic effect of the NiCo 2 S 4 nanorods arrays and CNF promotes the electrochemical reaction process that the as-prepared NiCo 2 S 4 @CNF electrode delivers excellent sodium storage properties, showing a high reversible capacity and superior cyclic stability. This work offers a new guidance for the improvement the sodium storage performance of NiCo 2 S 4 electrodes. Declarations Author contribution Xiaowei Yang: methodology, data curation, validation, investigation, funding acquisition, writing-original draft, review, and editing. Tongxiang Cai: conceptualization, validation, writing-original draft, data curation. Zhongran Yao: resources, methodology, data curation. Guojie Chao: resources, methodology, data curation. Funding This work was financially supported by Natural Science Research of Jiangsu Higher Education Institutions of China (No. 23KJB430038). Data Availability No datasets were generated or analysed during the current study. Competing Interests The authors declare no competing interests. References Zhang, T. Y., Ran, F. (2021) Design strategies of 3d carbon-based electrodes for charge/ion transport in lithium ion battery and sodium ion battery. Adv. Funct. Mater. 31(17):2010041 Zhao, J. H., He, X. X., Lai, W. H., Yang, Z., Liu, X. H., Li, L., Qiao, Y., Xiao, Y., Li, L., Wu, X. Q., Chou, S. L. (2023) Catalytic defect-repairing using manganese ions for hard carbon anode with high-capacity and high-initial-coulombic-efficiency in sodium-ion batteries. Adv. Energy. Mater. 13(18):2300444 Xie, F., Niu, Y., Zhang, Q., Guo, Z., Hu, Z., Zhou, Q., Xu, Z., Li, Y., Yan, R., Lu, Y., Titirici, M. M., Hu, Y. S. (2022) Screening heteroatom configurations for reversible sloping capacity promises high-power na-ion batteries. Angew Chem. Int. Ed. Engl. 61(11):202116394 Zhang, J., Song, K., Mi, L., Liu, C., Feng, X., Zhang, J., Chen, W., Shen, C. (2020) Bimetal synergistic effect induced high reversibility of conversion-type Ni@NiCo 2 S 4 as a free-standing anode for sodium ion batteries. J. Phys. Chem. Lett. 11(4):1435–1442 Ma, X., Fu, J., Gao, L., Zhang, J., Tao, S., Guo, W., Liu, X., Yang, B., Lu, J. (2023) Dual-duty NiCo 2 S 4 nanosheet-based solar rechargeable batteries toward multi-scene solar energy conversion and storage. Nanoscale 15(25):10584–10592 Chu, K., Hu, M., Qiu, M., Han, L., Sheng, W., Xu, M., Li, Z., Sun, X., Zheng, F. (2023) MOF-derived porous NiCo 2 S 4 nanocrystals embedded in nitrogen-doped carbon nanorods as lithium battery anodes. J. Mate. Sci.: Mater. Electron. 34(23):1660 Zhang, H., Xie, Y., Yang, S., Gao, X., Bai, H., Yao, F., Yue, H. (2023) NiCo 2 S 4 nanocone arrays on three-dimensional graphene with small hole diameters for asymmetric supercapacitor. J. Alloy Compd. 968:171694 Li, S., Ge, P., Jiang, F., Shuai, H., Xu, W., Jiang, Y., Zhang, Y., Hu, J., Hou, H., Ji, X. (2019) The advance of nickel-cobalt-sulfide as ultra-fast/high sodium storage materials: The influences of morphology structure, phase evolution and interface property. Energy Storage Mater. 16:267–280 Guan, B., Qi, S. Y., Li, Y., Sun, T., Liu, Y. G., Yi, T. F. (2021) Towards high-performance anodes: Design and construction of cobalt-based sulfide materials for sodium-ion batteries. J. Energy Chem. 54:680–698 Liu, J., Ren, L., Wang, Y., Lu, X., Zhou, M., Liu, W. (2023) A highly-stable bifunctional NiCo 2 S 4 nanoarray@carbon paper electrode for aqueous polysulfide/iodide redox flow battery. J. Power Sources 561:232607 Fan, S., Liu, H., Xie, Y., Bi, S., Meng, X., Zhang, K., Sun, L., Zhang, S., Guo, Z. (2023) Electrolyte engineering on performance enhancement of NiCo 2 S 4 anode for sodium storage. Small 19(26): 2300188 Fan, S., Liu, H., Bi, S., Meng, X., Wang, Q., Zhang, K., Chen, Z., Xie, Y. (2023) NiCo 2 S 4 nanoparticles anchored in the 3d interpenetrating framework composed of GNs and CNTs toward enhanced sodium storage performance. Electrochim. Acta 441:141760 Li, J., Zhou, J., Zhou, Q., Wang, X., Guo, C., Li, M. (2021) Promoting the Na + -storage of NiCo 2 S 4 hollow nanospheres by surfacing Ni-B nanoflakes. J. Mater. Sci. Technol. 82:114–121 Liu, B., Kong, D., Wang, Y., Lim, Y. V., Huang, S., Yang, H. Y. (2018) Three-dimensional hierarchical NiCo 2 S 4 @MoS 2 heterostructure arrays for high performance sodium ion battery. FlatChem. 10:14–21 Qin, B., Wang, M., Wu, S., Li, Y., Liu, C., Zhang, Y., Fan, H. (2023) Carbon dots confined nanosheets assembled NiCo 2 S 4 @CDs cross-stacked architecture for enhanced sodium ion storage. Chinese Chem. Lett. 35:108921 Miao, Y., Zhao, X., Wang, X., Ma, C., Cheng, L., Chen, G., Yue, H., Wang, L., Zhang, D. (2020) Flower-like NiCo 2 S 4 nanosheets with high electrochemical performance for sodium-ion batteries. Nano Res. 13(11): 3041–3047 Additional Declarations No competing interests reported. Supplementary Files SupportingInformation.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4671092","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":330121934,"identity":"9f7d40ce-8f71-4a25-8b58-1b673edf38fa","order_by":0,"name":"Xiaowei Yang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCklEQVRIiWNgGAWjYDACZjApASIYHyT+seHhZ28gXguzwcOGNBnJngPEW8gm+bDhsI3BDQf8ygyOMz98zFNhkdg/u/2CROKO8zwMNxgYP3zMwa1FspnN2JjnjETijDtnCgwSz9zmYZzdwCw5cxtuLfzMDGbSuW0SiQ03chISEthu8zDLHGBj5sWjhY2Z/Zt07j+JxPlALQcS2M7xsEkk4NfCz8wDtKVBInHDjfSDDYltB3h4CGmRbOYpNv5zTMJ4440cZoaEM8k8EjwHm/H6xeD88Y0PZ9TUyc67kf78548KO3v7480HP3zEowUGHBsYeAygbMYGwuqBwJ6Bgf0BUSpHwSgYBaNg5AEAeshT0GwULBcAAAAASUVORK5CYII=","orcid":"","institution":"Wuxi Institute of Technology","correspondingAuthor":true,"prefix":"","firstName":"Xiaowei","middleName":"","lastName":"Yang","suffix":""},{"id":330121935,"identity":"da1db6ae-9a8d-4547-9843-2b20bea2175e","order_by":1,"name":"Tongxiang Cai","email":"","orcid":"","institution":"Yadea Technology Group Co., Ltd","correspondingAuthor":false,"prefix":"","firstName":"Tongxiang","middleName":"","lastName":"Cai","suffix":""},{"id":330121936,"identity":"1426d025-61a0-43a0-80e4-b49291a481c3","order_by":2,"name":"Zhongran Yao","email":"","orcid":"","institution":"Wuxi Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Zhongran","middleName":"","lastName":"Yao","suffix":""},{"id":330121937,"identity":"185395d0-2325-40fd-926c-cf5e067bc28f","order_by":3,"name":"Guojie Chao","email":"","orcid":"","institution":"Wuxi Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Guojie","middleName":"","lastName":"Chao","suffix":""}],"badges":[],"createdAt":"2024-07-02 03:22:21","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4671092/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4671092/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":61098416,"identity":"d3afaf83-aef7-44af-ba4b-2ad6cd10c099","added_by":"auto","created_at":"2024-07-25 14:35:33","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1046841,"visible":true,"origin":"","legend":"\u003cp\u003e(a) SEM of CNF. (b, c) SEM of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF. (d) Element mapping of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF for C, S, Ni and Co.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4671092/v1/9efdf307036ae62deb814660.png"},{"id":61098413,"identity":"ca5859ac-a7f5-4ec4-b7bd-ebafbff03194","added_by":"auto","created_at":"2024-07-25 14:35:33","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":157564,"visible":true,"origin":"","legend":"\u003cp\u003e(a) XRD patterns. (b) XPS spectra. High-resolution XPS spectrum of the NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF: (c) C 1s, (d) S 2p, (e) Ni 2p and (f) Co 2p.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4671092/v1/85d7bcabc7994b86652e2ba4.png"},{"id":61098414,"identity":"114bba57-1cb4-478e-bdb2-bca5a6952f54","added_by":"auto","created_at":"2024-07-25 14:35:33","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":117724,"visible":true,"origin":"","legend":"\u003cp\u003eElectrochemical performance. (a) Rate performance. (b) GCD profiles at 0.1 A g\u003csup\u003e-1\u003c/sup\u003e. (c) EIS diagram (The inset is the corresponding equivalent circuit). (d) CV profiles of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF at the scan rate of 0.1 mV s\u003csup\u003e-1\u003c/sup\u003e. (e) Long-term cycles of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF at 2.0 A g\u003csup\u003e-1\u003c/sup\u003e.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4671092/v1/f6b9971438a520aa41ffadad.png"},{"id":63241543,"identity":"98ac2b52-fbd5-4eef-bc76-1be1da8cc8d7","added_by":"auto","created_at":"2024-08-26 04:42:03","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1621890,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4671092/v1/43cbdeef-d0be-4ee0-8b4b-76a45a9e10b0.pdf"},{"id":61098415,"identity":"4e050c17-5f9a-4614-8853-b933f6260704","added_by":"auto","created_at":"2024-07-25 14:35:33","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":266594,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-4671092/v1/10444829371a14774cbb9502.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eNovel NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanorods arrays grown on carbon nanofibers as high-performance anodes for sodium ion batteries\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eWith the growing energy demand and serious environmental issues, sodium-ion batteries (SIBs) have become promising substitutes for lithium-ion batteries (LIBs) in large-scale energy storage systems due to their abundant resources and low-cost of precursors. As the commercial anodes for LIBs, graphite has excellent discharge specific capacity and cycling stability[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. However, the electrode of graphite is not suitable for sodium-ion batteries[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Therefore, there is an urgent need to make breakthroughs in finding suitable anode materials for SIBs.\u003c/p\u003e \u003cp\u003eAs one of the transition metal sulfides, NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e electrode with excellent theoretical capacity and superior redox reversibility has been widely used in the field of energy storage[\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e have received extensive research in recent years, mainly owing to their promising sodium storage behavior when it was utilized as an anode for SIBs[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. For instance, Shen et al.[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] synthesized a self-supporting Ni@NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e anode for SIBs with grown bimetallic NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e on nickel foam. The three-dimensional hierarchical Ni@NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e electrode exhibits high capacity and excellent cycling stability (90.65%, 100 cycles). Additionally, Li et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] designed a kind of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanodots (~\u0026thinsp;9 nm) in N-doped carbon as anode for SIBs. The as-prepared NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@NC electrode delivers excellent sodium storage performance (a stable capacity of 570.1 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 0.2 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) in the ether-based electrolyte. However, some problems still exist, such as aggregation of intermediates and large volume changes, leading to rapid capacity fading and poor cycle life, limiting the further development of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e electrodes.\u003c/p\u003e \u003cp\u003eHerein, NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanorods arrays are uniformly grown onto carbon nanofibers (NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF) through a facile approach of hydrothermal. The NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanorods arrays are uniformly dispersed on the surfaces of carbon nanofibers (CNF) and tightly bonded with each other. The CNF nanofibers strengthen the conductive network of the composites, which is beneficial to the transfer of sodium ions and electrons. The increased electrode specific surface area and active sites improve the utilization efficiency of active materials. Benefiting from the synergism between the NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanorods arrays and carbon nanofibers such as improved electronic conductivity and shortened ion diffusion pathways, the NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF electrodes exhibit excellent electrochemical characteristics as an anode in SIBs.\u003c/p\u003e"},{"header":"Experimental section","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eMaterials preparation\u003c/h2\u003e \u003cp\u003eFirstly, CNF nanofibers were synthesized through electrospinning of PAN solution, followed by carbonization procedure. NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF composites were synthesized by a hydrothermal reaction. Briefly, Ni(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO (1 mmol), Co(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO (2 mmol), urea (4 mmol) and thiourea (8 mmol) were dissolved in ultra-purified water (30 mL). The above solution was then poured into a 50 mL autoclave with a piece of CNF membrane added into the mixed solution, which was kept at 160 ℃ for 6 h. For comparison, pure NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e was prepared by a similar procedure without adding CNF nanofibers membrane.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eMaterials characterization\u003c/h2\u003e \u003cp\u003eX-ray diffraction (XRD) pattern was obtained on an X-ray diffractometer (XRD, DX-2700) with Cu Kα radiation (λ\u0026thinsp;=\u0026thinsp;1.5406 \u0026Aring;) at 40 kV and 30 mA. Elemental composition and valence state of the samples were detected by X-ray photoelectrons (XPS, ESCLAB 250Xi). The morphologies of the samples were characterized using field-emission scanning electron microscope (FESEM, Hitachi S-4800).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eElectrochemical measurements\u003c/h2\u003e \u003cp\u003eThe active material, acetylene black and polyvinylidene fluoride were mixed in a weight ratio of 8:1:1 and N-methyl-2-pyrrolidone was worked as the solvent. Then, the formed slurry was coated on aluminum foil and dried at 80 ℃ for 12 h. The CR2032 type batteries were assembled in a super purification glove box. Pure Na metal foil was worked as a counter electrode, glass microfiber (Whatman\u0026reg; GF/D) was used as a separator, and 1.0 M NaClO\u003csub\u003e4\u003c/sub\u003e dissolved in DEC/EC (1:1, in volume) was worked as electrolyte. The cyclic voltammetry (CV) test was measured using an electrochemical workstation (CS-2350H, CORRTEST). The cells were cycled with a LAND battery measurement system between 0.01 V and 3.0 V.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results and discussion","content":"\u003cp\u003eSEM images of Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea shows the microstructure of as-obtained CNF nanofibers sample. The nanofibers of CNF exhibit clean surfaces with the diameters of 200\u0026ndash;300 nm. It can be observed that CNF is composed of large amounts of fibers with well-distributed diameter and thickness, which ensures the uniform growth and distribution of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e particles. The NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanorods arrays are generated around the carbon fibers after hydrothermal reaction, and the morphological changes of the carbon fibers before and after hydrothermal treatment are shown in Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb and c, NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanorods arrays are dispersed on top of CNF and tightly intertwined with each other to form NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF electrodes. The dispersed nanorods arrays of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e can exposed more active sites for sodium and the conductive network of CNF ensures faster electrolyte transport. Furthermore, the energy dispersive spectroscope (EDS) spectrum and corresponding mapping images reveal the uniform distribution of C, S, Ni and Co elements in the NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF sample (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe crystalline feature of as-obtained samples was elucidated by XRD in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea. It is noticed that both the NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF and pure NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e display same diffraction peaks located at 2θ\u0026thinsp;=\u0026thinsp;23.8\u0026deg;, 27.1\u0026deg;, 31.9\u0026deg;, 38.6\u0026deg;, 47.7\u0026deg;, 50.8\u0026deg;, 55.6\u0026deg;, 65.4\u0026deg;, 69.6\u0026deg; and 78.5\u0026deg;, respectively. All the characteristic peaks can be indexed to the standard PDF card of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e (JCPDS 01-073-1704)[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The peak intensity of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF is slightly weaker than that of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e, mainly due to the composite effect of carbon fiber membrane. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb, the chemical state of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF electrode was investigated by X-ray photoelectron spectroscopy (XPS) measurements. The survey spectrum manifests that NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF contains Ni, Co, S, O and C elements. The oxygen content in NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF is attributed to the natural properties of carbon fibers and the exposure of sample to air. High-resolution C 1 s signal of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec can be fitted into a series of peaks located at 284.8, 285.5, 286.2 and 288.9 eV, which correspond to C-C, C-O, C\u0026thinsp;=\u0026thinsp;O and O-C\u0026thinsp;=\u0026thinsp;O bonds, respectively. In the S 2p spectrum of Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed, the peaks located at 161.4 eV and 162.5 eV are assigned to S 2p\u003csub\u003e3/2\u003c/sub\u003e and S 2p\u003csub\u003e1/2\u003c/sub\u003e orbitals of S\u003csup\u003e2\u0026minus;\u003c/sup\u003e. Ni-S and Co-S can be also observed, confirming the formation of multi-metal sulfides. The Ni 2p spectrum in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee reveals two strong peaks located at 856.2 eV and 873.9 eV, corresponding to Ni 2p\u003csub\u003e3/2\u003c/sub\u003e and Ni 2p\u003csub\u003e1/2\u003c/sub\u003e, respectively[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. From the Co 2p spectrum of Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef, strong peaks at 781.5 eV and 796.8 eV correspond to Co 2p\u003csub\u003e3/2\u003c/sub\u003e and Co 2p\u003csub\u003e1/2\u003c/sub\u003e, respectively. Furthermore, the corresponding elemental analysis is summarized in Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e. These results are in accordance with the reported characteristics of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe sodium ion storage characteristics of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF electrodes were investigated in CR2032 coin type half-cell, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea exhibits the rate performance of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e and NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF samples in the range of current densities from 0.1 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to 5.0 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. It is obvious that the NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF electrode delivers a higher discharge specific capacity than NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e, which are 683.6, 551.9, 470.2, 403.6, 345.1 and 256.7 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at the current densities of 0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. As for the NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e electrode, only a specific capacity of 478.8 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e released at a current of 0.1 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and it decayed rapidly. When the current density increases to 1.0 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, there is almost no capacity. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb shows the galvanostatic charge and discharge (GCD) curves of the NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF electrode at a current density of 0.1 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF electrode represents an initial capacity of 756.2 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and secondary capacity of 683.6 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, with a high initial coulombic efficiency (ICE) of 90.4%.\u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec, the EIS measurement was conducted to analyze the kinetic feature of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF electrode toward sodium ions. The semicircle district represents the resistance of charge transfer (R\u003csub\u003ect\u003c/sub\u003e), which is related to the electrochemical kinetics of the electrodes. Meanwhile, the oblique line represents the Warburg impedance (Zw), which is determined by the diffusion of sodium ions in the electrode. Based on the equivalent circuit (the inset in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec), the R\u003csub\u003ect\u003c/sub\u003e of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF and NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e are calculated to 187.6 Ω and 392.7 Ω respectively. The smaller R\u003csub\u003ect\u003c/sub\u003e value of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF indicates lower charge transfer resistance and higher conductivity. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed reveals the first three CV curves of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF electrode in the potential range of 0.01-3 V at a scan rate of 0.1 mV s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. In the first cathodic scan, two peaks located at \u0026sim;0.5 V should be assigned to the reversible formation of solid electrolyte interphase (SEI) film and activation process of Na\u003csup\u003e+\u003c/sup\u003e insertion into NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF. The subsequential anodic peaks at 1.88 V correspond to the extraction of Na\u003csup\u003e+\u003c/sup\u003e and the formation of NiS and CoS. In the following scan, two pair of conspicuous peaks reflected the reverse process between NiS/CoS and Na. The profile of successive cycles fits well, confirming the excellent stability of the electrode. The long-term cycling stability of the NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF electrode was also evaluated under high current density and the result is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ee. At a high current density of 2.0 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, the reversible capacity still maintained at 283.2 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e after 400 cycles with the CE over 99%, indicating the superior stability of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF. In addition, the comparison between the reported literatures on NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e materials in sodium ion batteries in Table S2 also confirms the superiority of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF[\u003cspan additionalcitationids=\"CR12 CR13 CR14 CR15\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn summary, NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanorods arrays have been uniformly grown onto carbon nanofibers through a facile approach of hydrothermal. Benefiting from the robust structure and excellent conductivity of 3D novel architecture, it can effectively mitigate the volume expansion effect of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e electrode during cycling and accelerate the ion/electron transport. The synergistic effect of the NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanorods arrays and CNF promotes the electrochemical reaction process that the as-prepared NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF electrode delivers excellent sodium storage properties, showing a high reversible capacity and superior cyclic stability. This work offers a new guidance for the improvement the sodium storage performance of NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e electrodes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contribution\u0026nbsp;\u003c/strong\u003eXiaowei Yang: methodology, data curation, validation, investigation, funding acquisition, writing-original draft, review, and editing. Tongxiang Cai: conceptualization, validation, writing-original draft, data curation. Zhongran Yao: resources, methodology, data curation. Guojie Chao: resources, methodology, data curation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003eThis work was financially supported by Natural Science Research of Jiangsu Higher Education Institutions of China (No. 23KJB430038).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e No datasets were generated or analysed during the current study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e The authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eZhang, T. Y., Ran, F. (2021) Design strategies of 3d carbon-based electrodes for charge/ion transport in lithium ion battery and sodium ion battery. Adv. Funct. Mater. 31(17):2010041\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao, J. H., He, X. X., Lai, W. H., Yang, Z., Liu, X. H., Li, L., Qiao, Y., Xiao, Y., Li, L., Wu, X. Q., Chou, S. 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(2023) Carbon dots confined nanosheets assembled NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CDs cross-stacked architecture for enhanced sodium ion storage. Chinese Chem. Lett. 35:108921\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMiao, Y., Zhao, X., Wang, X., Ma, C., Cheng, L., Chen, G., Yue, H., Wang, L., Zhang, D. (2020) Flower-like NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanosheets with high electrochemical performance for sodium-ion batteries. Nano Res. 13(11): 3041\u0026ndash;3047\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Sodium batteries, NiCo2S4 nanorods arrays, Anode, Carbon nanofibers, Structural stability","lastPublishedDoi":"10.21203/rs.3.rs-4671092/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4671092/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eNovel NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanorods arrays are uniformly grown onto carbon nanofibers (NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF) through a facile hydrothermal approach. The elaborate designed composite structure ensures that the NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e nanorods arrays are uniformly dispersed on the surfaces of carbon nanofibers (CNF) and tightly bonded with each other. The conductive networks of CNF can facilitate the electron transport at the interfaces and ions diffusion to readily react with NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e, thus leading to increased sodium storage. In view of this, NiCo\u003csub\u003e2\u003c/sub\u003eS\u003csub\u003e4\u003c/sub\u003e@CNF reveals a high reversible capacity (683.6 mAh g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 0.1 A g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and long-term cycle stability (only attenuates 0.07% in each cycle after 400 times). This work provides a simple and efficient strategy for synthesizing high-performance sodium ion battery electrodes.\u003c/p\u003e","manuscriptTitle":"Novel NiCo2S4 nanorods arrays grown on carbon nanofibers as high-performance anodes for sodium ion batteries","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-25 14:35:28","doi":"10.21203/rs.3.rs-4671092/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"25484705-ec5d-453c-90b6-e08e80d6b910","owner":[],"postedDate":"July 25th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-08-26T04:33:56+00:00","versionOfRecord":[],"versionCreatedAt":"2024-07-25 14:35:28","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4671092","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4671092","identity":"rs-4671092","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}