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 Li 2 CoSiO 4 /carbon nanocomposites via hydrothermal synthesis. TEM-EDX and TGA measurements showed that ∼2 wt % carbon was incorporated within Li 2 CoSiO 4 crystal aggregates on the nanoscale. We find that both the morphology and particle size of the Li 2 CoSiO 4 /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 Li 2 CoSiO 4 /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 Li 2 CoSiO 4 /C composites showed that the nanocarbon played an important role in enhancing the electrochemical performance, when compared with Li 2 CoSiO 4 prepared using fumed silica as the silicate source under similar conditions.