Superior electrochemical properties of spherical-like Co-2(OH)(3)Cl-reduced graphene oxide composite powders with ultrafine nanocrystals

Abstract

Co-2(OH)(3)Cl/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. Co-2(OH)(3)Cl nanocrystals less than 10 nm in size were uniformly distributed throughout the spherical Co-2(OH)(3)Cl/RGO composite powder. CoCl2 center dot 6H(2)O/RGO, CoCl2 center dot 6H(2)O/Co3O4/RGO, and Co3O4 powders were also prepared by post-treatment of the Co-2(OH)(3)Cl/RGO powders at 200, 300, and 400 degrees C, respectively, in air. The initial discharge capacities of the Co-2(OH)(3)Cl/RGO, CoCl2 center dot 6H(2)O/RGO, CoCl2 center dot 6H(2)O/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 Co-2(OH)(3)Cl/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 Co-2(OH)(3)Cl/RGO powders had smaller charge transfer resistance and faster lithium-ion diffusion rate than the other materials. (C) 2014 Elsevier Ltd. All rights reserved.