Patent ID: 9705111
Date: 2017-07-11
CPC Classifications: B23K,H01M,Y02E,Y02P

Claim:
1. A secondary battery in which a battery lid is fixed to a battery case by inserting said battery lid into an opening of said battery case having said opening, and emitting laser beams to a butting portion between said battery case and said battery lid to perform butt welding, wherein when a battery lid-side welding mark formed in said battery lid has a distance from a surface of said battery lid to a lowest end of said battery lid-side welding mark which is defined as a battery lid-side welding depth, and a battery case-side welding mark formed in said battery case has a distance from the surface of said battery lid to a lowest end of said battery case-side welding mark which is defined as a battery case-side welding depth, said battery lid-side welding depth is deeper than said battery case-side welding depth, and a ratio between said battery case-side welding depth and said battery lid-side welding depth has a value of 65% to 85%.