Impregnation of cobalt on graphene sheet using liquid phase plasma method for lithium-ion batteries application

The liquid phase plasma (LPP) method was applied to the impregnation of cobalt/graphene and cobalt oxide/graphene composites as the anode materials for lithium-ion batteries. Spherical cobalt and cobalt oxide nanoparticles, approximately 2~7-nm in size, were dispersed uniformly on the surface of the two-dimensional graphene sheet. The amount of cobalt oxide nanoparticles precipitated on the graphene sheet increased with increasing initial concentration of the cobalt precursor. Cobalt nanoparticles on the graphene sheet, which were composed of Co⁰ and CoO, were oxidized by a thermal treatment to cobalt oxide nanoparticles composed of Co₂O₃ or Co₃O₄. The cycling stability and reversible lithium storage capacity were improved by thermal oxidation.