| 摘要 |
PROBLEM TO BE SOLVED: To improve cycle life characteristic by setting an active material layer of a negative electrode to have a density higher than a specific value, when a lithium-manganese composite oxide and an amorphous material that both allow absorption and release of lithium ions with discharge and charge are respectively used as a positive electrode and the negative electrode. SOLUTION: Density of a negative electrode active material layer formed by coating and drying a slurry-shaped mixture of amorphous material powders, a binder, and a dispersion solvent on both surfaces of a negative collector such as copper foil is preferably at least 1.04 g/cm3. When lithium manganate is used as a positive electrode active material in which aluminum foil is used as the collector, volume decreases and pressurizing force of an electrode group decreases during charge than during using of lithium cobaltate, and electron conductive network between the active materials in the negative electrode damages to increase degradation of the negative electrode. By setting the density of the negative electrode active material layer to be at least a given value, conductivity between the contained amorphous material carbon powders increases, capacity maintaining factor largely increases, and life is extended. |
