Biomass-Derived Graphitic Carbon/Co9S8 Nanocomposite as Anode for Enhanced Lithium Storage

Biomass carbon-encapsulated transition metal sulfides (TMSs) as anodes for enhanced lithium-ion storage have recently been one hot topic in sustainable development. Herein, three Co9S8-based biomorphic materials were prepared by simple immersion of discarded scallion roots in Co(NO3)(2) solution, followed by in situ calcination and sulfidation reactions under different atmospheres. Among them, the Co9S8/GC-1 nanocomposite is formed by the cross-linkage of 43 wt % biomass-derived graphitized carbon (GC) and small-sized nanoparticles, which possess multilevel mesoporous distribution and a large specific surface area (109.3 m(2)center dot g(-1)). Such unique structure not only shortens the migration path of Li+ ions and promotes the rapid penetration of electrolyte to form a stable solid electrolyte interphase (SEI) membrane but also inhibits the agglomeration of Co9S8 nanoparticles and alleviates their volume expansion, which in turn ensures the structural stability of the electrode material and provides good pseudocapacitance behavior. As an anode for lithium-ion batteries (LIBs), the discharge capacity of the Co9S8/GC-1 electrode is 381 mA h g(-1) at 5 A g(-1). Especially at 1 A g(-1), its capacity can still be stabilized to 471.3 mA h g(-1) over 2000 cycles. This indicates that the Co9S8/GC-1 nanocomposite has good capacity retention and long-cycling performance, further being applied as a candidate anode for LIBs.