Superior electrochemical properties of spherical-like Co2(OH)3Cl-reduced graphene oxide composite powders with ultrafine nanocrystals

Co2(OH)3Cl/reduced graphene oxide (RGO) composite powders for use as anodes in lithium ion batteries were prepared directly by spray pyrolysis from a colloidal solution of graphene oxide sheets and cobalt chloride. Co2(OH)3Cl nanocrystals less than 10 nm in size were uniformly distributed throughout the spherical Co2(OH)3Cl/RGO composite powder. CoCl2·6H2O/RGO, CoCl2·6H2O/Co3O4/RGO, and Co3O4 powders were also prepared by post-treatment of the Co2(OH)3Cl/RGO powders at 200, 300, and 400 °C, respectively, in air. The initial discharge capacities of the Co2(OH)3Cl/RGO, CoCl2·6H2O/RGO, CoCl2·6H2O/Co3O4/RGO, and Co3O4 powder electrodes at a current density of 1000 mA g−1 were 1685, 1518, 1655, and 1046 mA h g−1, respectively, and their discharge capacities after 200 cycles were 1186, 1030, 884, and 805 mA h g−1, respectively. The discharge capacities of the Co2(OH)3Cl/RGO composite powder electrode for the 2nd and 600th cycles at a current density of 5000 mA g−1 were 1063 and 833 mA h g−1, respectively. The Co2(OH)3Cl/RGO powders had smaller charge transfer resistance and faster lithium-ion diffusion rate than the other materials.