Interface engineering of Co₉S₈/SnS heterostructure as a high-performance anode for lithium/sodium-ion batteries

Transition metal sulfide (TMS) anodes exhibit the characteristics of phase stability and high capacity for lithium/sodium-ion batteries (LIBs/SIBs). However, the TMS anodes often suffer from poor electronic conductivity, low ionic diffusion and large volume expansion during Li/Na-ion intercalation significantly impairing the Li/Na-storage performance. Herein, a long chain heterostructure composed of the Co9S8 and SnS are first reported, which can generate rich phase interfaces, and small crystal domains. The unique structure can facilitate the properties of reactivity, conductivity and ionic diffusion. In addition, the heterostructure surface is modified by the N-doped carbon (N-DC@(CoSn)S), successfully improving the structural stability. The synergistic effects of Co9S8/SnS heterostructure and coated carbon layer effectively increase the capacity and cycling stability. The N-DC@(CoSn)S anode delivers enhanced high specific capacities of 820.6 mAh center dot g(-1 )at 1.0 A center dot g(-1) after 500 cycles for LIBs and 339.2 mAh center dot g(-1) at 0.5 A center dot g(-1) after 1000 cycles for SIBs, respectively. This work is expected to provide a material design idea for preparing LIBs/SIBs with high capacity and long cycling life.