Hydrothermal Synthesis and Electrochemical Properties of Li2CoSiO4/C Nanospheres

A highly ordered mesoporous carbon/silica (MCS) framework was used as both a silicate precursor and carbon source to prepare Li2CoSiO4/carbon nanocomposites via hydrothermal synthesis. TEM-EDX and TGA measurements showed that similar to 2 wt % carbon was incorporated within Li2CoSiO4 crystal aggregates on the nanoscale. We find that both the morphology and particle size of the Li2CoSiO4/C composites are significantly influenced by the LiOH concentration in the precursors. By controlling the molar ratio of LiOH:Si:Co = 8:1:1, very uniform Li2CoSiO4/C spheres were obtained with an average diameter of 300-400 nm. Many exhibit hollow or core-shell structures. A mechanism is proposed to account for both the unusual morphology and carbon incorporation. Despite some electrolyte oxidation at high potential, the electrochemical properties of the Li2CoSiO4/C composites showed that the nanocarbon played an important role in enhancing the electrochemical performance, when compared with Li2CoSiO4 prepared using fumed silica as the silicate source under similar conditions.