Synthesis of sandwich-like Co(CO3)(0.5)(OH)/graphene composite through confined growth and self-assemblies for highly reversible lithium storage

Transition metal carbonate/hydroxide recently exhibits higher specific capacities than that of the relative oxides. Thus, sandwich-like Co(CO3)(0.5)(OH)/graphene composite is obtained here through confined growth and layer-by-layer self-assemblies by one-pot stirring solvothermal reaction. The molecular formula of the composite is exactly proved as Co(CO3)(0.5)(OH) without any crystal water. Furthermore, layer-by-layer stacking between Co(CO3)(0.5)(OH) and graphene are also observed with thickness of about several nanometers. The graphene layers between Co(CO3)(0.5)(OH) layers not only enhances the transfer of electron, but also releases the tension resulting from the volumetric effect during repeated lithiation/delithiation. Thus, highly reversible charge/discharge capacities of 1200 mAh g(-1) at 0.2 A g(-1) are obtained with high coulombic efficiency closed to 100% after 150 cycles, which is due to the potential reduction of carbon and hydrogen. In addition, even at high current densities of 0.5 and 1.0 A g(-1), reversible charge/discharge capacities of about 806/807 and 609/611 mAh g(-1) are remained after 300 cycles. Such basic carbonate/graphene composite with special structure obtained by one-pot stirring solvothermal reaction may be promising as one of the candidates for high-energy anode material in lithium ion batteries. (C) 2018 Elsevier B.V. All rights reserved.