MESOCARBON MICROBEAD, ITS PRODUCTION, MATERIAL FOR PRODUCING NEGATIVE ELECTRODE OF LITHIUM SECONDARY CELL AND LITHIUM SECONDARY CELL

摘要

PROBLEM TO BE SOLVED: To obtain mesocarbon microbeads(MCMB) produced from a raw material of a coal heavy oil such as coal tar or coal-tar pitch, in which the beads are free from mutual adherence and aggregation, although the surfaces of the beads are homogeneously covered with the pitch component. SOLUTION: A coal heavy oil is thermally treated, the produced crude mesocarbon microbeads are collected and these are washed and purified to obtain mesocarbon microbeads. In this process, a tar middle oil having a boiling point range of 100-500 deg.C is added to the crude mesocarbon microbeads in an amount of 0.1-20 times the microbeads by weight and they are treated at 10-300 deg.C for 0.1-20hr for cleaning. Thus, a raw mesocarbon microbeads having a specific surface area of 0.1-7.0m<2> /g and a true specific gravity of 1.20-1.50 is obtained. The raw mesocarbon microbeads are carbonized or graphitized to produce a carbon material. This invention also provides a lithium secondary cell using the carbon material as the negative electrode.