Efficient construction of a CoCO3/graphene composite anode material for lithium-ion batteries by stirring solvothermal reaction

Transition-metal carbonates have recently been investigated as anode materials for lithium-ion batteries because of their relatively high capacity compared with that of the corresponding transition-metal oxides. In this work, a facile stirring solvothermal reaction is used to prepare a CoCO3/graphene composite without the use of an additional organic chelating agent. The as-prepared CoCO3/graphene composite exhibits a smaller cubic particle size of 1-2 µm and a larger specific surface area than the composite obtained by a traditional solvothermal reaction. The composite prepared with stirring delivers a highly reversible capacity of 602 mAh g−1 after 100 cycles. Even at a high current density of 2.0 A g−1, the composite maintains charge-discharge capacities of 605/598 mAh g−1. The composites contained the same amount of graphene, indicating that the improved electrochemical properties are attained independently of the amount of the graphene. In addition, the results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS)experiments also reveal that the CoCO3/graphene composite electrode materials synthesised via a stirring solvothermal reaction exhibit substantially enhanced kinetics. The stirring solvo/hydrothermal reaction develops in this work is considered a promising candidate for efficiently preparing carbonate/graphene composites with better electrochemical properties for practical applications, without the use of an extra chelating agent.