| 摘要 |
PROBLEM TO BE SOLVED: To obtain a configuration capable of protecting an electrode body disposed inside a battery case even when the battery case is subjected to impacts in a square secondary battery having the electrode body stored in the battery case, the electrode body being formed by stacking and winding a positive electrode, a negative electrode and a separator which are respectively formed in a sheet shape.SOLUTION: A square secondary battery includes: an electrode body formed by stacking and winding a positive electrode (31), a negative electrode (32) and a separator (33), each being formed in a sheet shape; and a flat columnar-shaped battery case configured to store the electrode body therein. The separator (33) has a larger area than the positive electrode (31) and the negative electrode (32). A projected portion (33a) of the separator (33) located on a bottom surface side of the battery case and projecting from the positive electrode (31) and the negative electrode (32) constitutes a buffer part that absorbs impacts exerted on the bottom surface side of the battery case. |
