| 摘要 |
PROBLEM TO BE SOLVED: To inhibit generation of SEI on the surface of a negative electrode active material and enhance a cycle characteristic by coating the surface of a negative electrode agent mainly containing a carbon with a coating film of LixSiyOz having a lithium ion-conductivity and specifying the ratio of silicon to lithium. SOLUTION: A coating film of LixSiyOz having a lithium ion-conductivity is applied on the surface of a negative electrode agent mainly containing a carbon for coating. A value of 100y/(x+y) being the ratio of silicon to lithium is preferably in the range of 10-80, more preferably in the range of 30-55 in order to enhance the maintaining rate of capacity after allowed to stand at a high temperature. When the value is in the range, the bond of LixSiyOz becomes one-dimensional, it is prevented that a film formed on the surface of the negative electrode agent becomes porous. Then, such deterioration that the lithium ion-conductivity is lowered, the resistance of the negative electrode becomes high and increased in IR drop is prevented. Regarding the coating amount on the surface of the negative electrode agent, LixSiyOz is desirably in the range of 0.01-10% to the negative electrode active material. |
