PRODUCTION METHOD FOR COMPOSITE GRAPHITE PARTICLE, COMPOSITE GRAPHITE PARTICLE, CATHODE MATERIAL FOR LITHIUM ION SECONDARY BATTERY, AND LITHIUM ION SECONDARY BATTERY

摘要

PPROBLEM TO BE SOLVED: To provide graphite particles for a lithium ion secondary battery being composite graphite having high load characteristics, high cycle characteristics, good crystallizability, a high capacity, and a small irreversible capacity, a production method therefor, a cathode material using the particles, and a method for producing the cathode material. PSOLUTION: The method for producing the composite graphite particles comprises applying pitch to the surface of spherical graphite particles obtained by spherically granulating flaky graphite particles with a mechanical external force, oxidizing the resultant surface coating layer, and heat-treating the coating layer to carbonize it, forming a carbonized coating layer in an amount of 0.5-20 mass% in terms of fixed carbon. Thus, the composite graphite particles are produced. The cathode material for a lithium ion secondary battery is made of the composite graphite particles. The lithium ion secondary battery uses the composite graphite particles as the cathode material. PCOPYRIGHT: (C)2004,JPO&NCIPI