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

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 200 mA g(-1), the discharge capacity of Co1-xS-rGO maintains 643 mAh g(-1) after 100 cycles. Even at high current density of 1000 mA g(-1), the discharge capacity of 625 mAh g(-1) is retained after 200 cycles, which is close to theoretical capacity (683 mAh g(-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.