Dual carbon composited with Co9S8 through C-S bond as a high performance Binder-Free anode for Sodium-Ion batteries

Cobalt sulfide/ carbon cloth composites with conversion reactions mechanism as anodes for sodium-ion storage have attracted tremendous attention due to high theoretical capacity and binder-free. However, the severe volume change and exfoliation of cobalt sulfide makes composite materials cycle stability and rate capability unsatisfactory. In this work, we report dual carbon materials composited with Co9S8 through C-S bonds to further stabilize the structure of the composite (Co9S8/[email protected]). Dual C-S bonds can provide ultrafast charge transport paths between Co9S8 and carbon materials, further ensure the stable reversible conversion reaction process. Furthermore, dual C-S bonds effectively prevent exfoliation of Co9S8 from carbon cloth, significantly improved structural stability of the composite. Benefiting from dual C-S bonds, the Co9S8/[email protected] composite electrode delivers high reversible capacity of 785.6 mAh g−1 at 0.1 A g−1 after 100 cycles with capacity retention of 74.81 %. Notably, it preserves a considerable capacity of 417.2 mAh g−1 after 1000 cycles at 5 A g−1. This work provides a good reference for improving cycle stability and rate performance of Co9S8-based electrodes to designing advanced anodes for sodium-ion batteries.