In-situ synthesis of Co1−xS-rGO composite for high-rate lithium-ion storage

Abstract

Cobalt sulfide (Co1−xS) is studied extensively as an anode material for lithium-ion batteries (LIBs) due to high theoretical capacity, however, low electronic conductivity and large volume change during the discharge/charge process limit its actual application. In this study, we synthesize Co1−xS-reduced graphene oxide (Co1−xS-rGO) composite through a simple solvothermal reaction and then freeze-drying process. The introduction of rGO not only improves electronic conductivity and redox kinetics of electrode material but also prevents Co1−xS nanoparticles from aggregation. At a current density of 200mAg−1, the discharge capacity of Co1−xS-rGO maintains 643mAhg−1 after 100cycles. Even at high current density of 1000mAg−1, the discharge capacity of 625mAhg−1 is retained after 200cycles, which is close to theoretical capacity (683mAhg−1). And then, Co1−xS-rGO delivers good rate performance and cycling stability. In the meanwhile, in-situ synthesis method is facile. These results indicate that Co1−xS-rGO could be a promising anode material for LIBs.