Secondary battery using system and material for negative electrode of secondary battery

摘要

A lithium secondary battery suitable for use as a power source for a secondary battery using system such as an electric automobile, motor bicycle or portable equipment includes a negative electrode (17) composed of a carbon material including carbon particles carrying fine particles of a metal which forms an alloy with lithium. The carbon particles have a face-to-face dimension which is 3.354 to 3.369 ANGSTROM and a crystal grain size in a C-axis direction which is equal to or greater than 300 ANGSTROM . The metal forming an alloy with lithium has a particle size which is equal to or smaller than 1000 ANGSTROM . With the use of the charge/discharge capacity of an alloy of the metal and lithium, a value exceeding the theoretical capacity 372 mAh/g of graphite can be obtained. The lithium secondary battery is capable of discharge with an output energy density equal to or higher than 350 W/kg.