CO₃ O₄ coating on graphite prepared by electrodeposition and heat treatment as negative electrode for lithium-ion batteries

With copper foil and graphite coated on the copper coil as cathode, electrochemical deposition was carried out in the solution of 0.5 mol/L CO (NO₃) ₂ at 50 °C and room temperature respectively. The deposition samples were then heat treated under vacuum at 245 °C. XRD analyses demonstrate that the main phase of the as-deposited layer is CO (OH)₂, which is transformed to CO₃ O₄ after heat treatment. SEM results show that the CO₃ O₄ phase deposited directly on the copper foil substrate has a uniform honeycomb structure, while the CO₃ O₄ phase deposited on the graphite coating demonstrates a nonuniform honeycomb structure. Charge-discharge tests show that the cycle performance of graphite-CO₃ O₄ composite is much better than that of CO₃ O₄ deposited on copper foil and its specific capacity is higher than that of pure graphite electrode.