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 Co 9 S 8 -based biomorphic materials were prepared by simple immersion of discarded scallion roots in Co(NO 3 ) 2 solution, followed by in situ calcination and sulfidation reactions under different atmospheres. Among them, the Co 9 S 8 /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 ·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 Co 9 S 8 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 Co 9 S 8 /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 Co 9 S 8 /GC-1 nanocomposite has good capacity retention and long-cycling performance, further being applied as a candidate anode for LIBs.