| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium secondly cell with high density of energy, in which a negative electrode active substance composed of either a mixture of a natural graphite and a coke or a natural graphite and a hard carbon is bound sufficiently with a small amount of a binder. SOLUTION: The lithium secondary cell is equipped with a positive electrode 1 composed of a nickel/cobalt composite oxide containing lithium as a positive activate substance expressed as LiNi1-xCoxO2 (0.1<x<0.6) and a negative electrode 2 bound through a binder from a negative electrode active substance composed of either a mixture of a natural graphite and a oke or a natural graphite and a hard carbon. As a binder for the negative electrode, polyfluorinated vinylidene with an average molecular weight of 500,000 or more and an amount of the binder related to overall weight of the negative electrode active substance and the binder should be either in a range of 3-7 wt.%, if the average particle diameter of the natural graphite is 18 μm or larger, or 5-7 wt.%, if an average particle diameter of the natural graphite is 18 μm or lower. |
