Rationally designed yolk–shell Co9S8–Co1−xS hollow spheres for advanced sodium-ion storage. Issue 41 (12th October 2021)

• Record Type: Journal Article
• Authors: Luo, Yuanyi; Shi, Ludi; He, Huanze; Cong, Guangtao; Zhu, Caizhen; Xu, Jian
• Is Part Of: Journal of materials chemistry. Volume 9:Issue 41(2021)
• Page Start: 23537
• Page End: 23544
• Publication Date: 2021-10-12
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d1ta05114h
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Rationally-designed nitrogen-doped carbon-coated Co9 S8 –Co1− x S yolk–shell hollow spheres are synthesized to buffer the volume fluctuation and enhance the electrical/ionic conductivity. Abstract : As one of the most promising sodium-ion battery (SIB) anodes, transition metal sulfides (TMSs) have been extensively studied for their high capacity and abundant resources. However, the performance of TMS electrodes has been plagued by the poor rate capability and short cycle life, resulting from the huge volume change and the shuttling of polysulfides during cycling. Here, rationally-designed nitrogen-doped carbon-coated Co9 S8 –Co1− x S yolk–shell hollow spheres (Co9 S8 –Co1− x S@NC) are synthesized as the SIB anode. The hollow nanostructure shortens the diffusion length of sodium ions/electrons and affords abundant space to accommodate the volume expansion during sodiation. The Co9 S8 –Co1− x S@NC anode delivers a large sodium-ion storage capacity of 578 mA h g −1 even after 500 cycles at 0.5 A g −1 and superior rate capability and cycling stability (323 mA h g −1 at 5 A g −1 over 1200 cycles) in a half cell. In addition, when combined with the advanced Na3 V2 (PO4 )2 O2 F electrode, the full SIB shows a highly stable specific capacity and reversibility. The reaction mechanism of Co9 S8 –Co1− x S@NC was studied using operando X-ray diffraction ( operando XRD), revealing the reversible conversion between cobalt sulfides and Co/Na2 S.