| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a square secondary battery in which mixing of a metallic foreign matter into a battery due to sputtering is prevented when welding a battery can (1) and a lid (6).SOLUTION: A square secondary battery (C1) has a square battery can (1), and a battery lid (6) for sealing the opening (1a) of the battery can (1). The battery lid (6) has a continuous protrusion (51) protruding into the battery can (1) so as to face the inner surface of the sidewall (21) thereof, continuously over the whole circumference in the circumferential direction of the sidewall (21). The battery lid (6) has a lid thickness (Tu), at a portion (52) abutting against the upper end of the sidewall (21) of the battery can (1) on the outside of the protrusion (51), which is thicker than one half of the lid thickness (Tt) of a closing portion (54) for closing the opening (1a) on the inside of the protrusion (51), but thinner than the lid thickness Tt of the closing portion (54).</p> |
