Carbon coating for Si nanomaterials as high-capacity lithium battery electrodes

We report a new method to generate a thin carbon layer on active materials for electrochemical energy storage. A solid precursor can be simply placed on the target material in a tailored vertical quartz tube and sublimated at a slightly high temperature. The carbon source gas remains around the target material during the heat treatment because of the vapor density difference and subsequent decomposition of the gas phase leads to a uniform carbon coating. For demonstration of the concept, carbon coating on Si nanoparticles, which are a high-capacity anode material for lithium-ion batteries, was realized by sublimation and decomposition of naphthalene. A conformal carbon layer was confirmed by various analyses and improved electrochemical performance of the Si nanoparticle electrode was clearly exhibited.