Improvement of Rate Capability and Low-temperature Performances of Graphite Negative Electrode by Surface Treatment with Copper Phthalocyanine

Abstract

:The rate capability and low-temperature characteristics of graphite electrode are investigated after surface treatment with copper phthalocyanine (CuPc) or phthalocyanine (Pc). Uniform coating layers comprising amorphous carbon or copper are generated after the treatment. The rate performance of graphite electrodes is enhanced by the surface treatment, which is more prominent with CuPc. The resistance of the graphite electrode estimated from electrochemical impedance spectroscopy and pulse resistance measurement is the smallest for the CuPc-treated graphite. It is likely that the amorphous carbon layer formed by the decomposition of Pc facilitates Li + diffusion and the metallic copper derived from CuPc improves the electrical conductivity of the graphite electrode.