Construction of Co9S8@C-MoS2 heterostructure for fast charging and superior long-term cycling performance of sodium ion batteries

Abstract

Cobalt sulfide (Co9S8) is a promising anode material for sodium-ion batteries (SIBs) due to its high theoretical capacity, cost-effectiveness, and environmental friendliness. Unfortunately, the inevitable structural deterioration induced by the huge volume changes during the discharge/charge cycles leads to poor cycle performance and rate capability when evaluated as the anode material for SIB. Herein, we designed a Co9S8@C-MoS2 heterostructure with abundant heterointerface and hollow structure. In the designed hybrid architecture, the self-supporting hollow carbon scaffold can provide sufficient space for volume expansion caused by Na+ insertion, and the abundant heterointerface can accelerate ion-diffusion and electron transfer kinetics and dissipate the internal stress induced by volume expansion during the sodiation/desodiation process. As expected, the Co9S8@C-MoS2 composite shows excellent sodium storage performance. Specifically, the Co9S8@C-MoS2 composite displays excellent long-term cycling life (a high capacity of 429.4 mAh g−1 is maintained after 1500 cycles at 5.0 A/g), and superior rate performance (412.6 mAh g−1 is achieved even at 10.0 A/g).