| 摘要 |
PROBLEM TO BE SOLVED: To make the connection of a negative active material with a conductive material satisfactory through the use of graphite powder obtained by crushing expanded graphite, having the center particle size larger than the center particle size of the negative active material as the conductive material. SOLUTION: Graphite powder obtained by crushing expanded graphite has center particle size larger than the center particle size of a negative active material, preferably 2-4 times larger than that of the center particle, and thin thickness and a flake shape. The content of the graphite powder in an electrode layer as a conductive material is preferably 0.1-15 wt.%. As the negative active material, graphitization retarding carbon and polymer carbon are preferable from the standpoint of increasing the capacity. The polymer carbon is the carbon material obtained by heat-treating a high polymer, having crosslinked structure and obtained by carbonizing cellulose or the like. The center particle size of the negative active material is preferably 4-15 μm. |
