Patent attributes
A lithium ion secondary battery which includes: a negative electrode plate 406 in which a negative electrode mixture layer 404 is formed on each of both surfaces of a negative electrode current collector 401 containing copper as a principle component and having a sheet shape; a positive electrode plate 407 in which a positive electrode mixture layer 405 is formed on each of both surfaces of a positive electrode current collector 402 containing aluminum as a principle component and having a sheet shape; and a separator 403 holding an electrolyte. The negative electrode plate 406, the positive electrode plate 407 and the separator 403 are spirally wound or stacked. The thickness of the positive electrode current collector 402 is smaller than the thickness of the negative electrode current collector 401.
