| 摘要 |
A lithium ion secondary battery includes a flat wound electrode body including a positive electrode sheet and a negative electrode sheet that are wound while interposing therebetween separators into a flat shape, and a battery case. In the flat wound electrode body, a central portion has a more constricted shape than end portions by pressing toward a winding axis in a short-side direction and each end portion includes an end-portion positive electrode sheet, an end-portion negative electrode sheet, and end-portion separators, and a core member arranged more inward than them. With tensile forces generated by pressing of the central portion in a central-portion positive electrode sheet, central-portion negative electrode sheet, and central-portion separators, the end-portion positive electrode sheet, end-portion negative electrode sheet, and end-portion separators are in pressure contact with each other and press the outer surfaces of the core member. |
