Prismatic secondary battery

Abstract

A prismatic secondary battery includes a battery case in a prismatic shape and a battery cover which seals up an opening part of the battery case. The battery cover has a convex part which projects toward the inside of the battery case, faces an inner surface of a side wall part of the battery case, and extends continuously along the entire periphery of the side wall part. Cover thickness of a contact part of the battery cover which is in contact with the upper end of the side wall part of the battery case at a position outside the convex part is greater than ½ of cover thickness of a blockage part blocking up an opening part at a position inside the convex part and is less than the cover thickness of the blockage part.

1 . A prismatic secondary battery comprising:
 a battery case in a prismatic shape which includes a bottom wall part in a rectangular shape forming a bottom, a side wall part in a prismatic tubular shape forming a side wall, and an opening part being open upward at an upper end of the side wall part; and   a battery cover which is welded to the upper end of the side wall part of the battery case and seals the opening part, wherein:   the battery cover includes a blockage part which blocks the opening part, a convex part which is positioned outside the blockage part, and a contact part which is positioned outside the convex part;   the side wall part includes a step part on an upper end of the side wall;   the step part contact with the contact part;   the convex part is arranged adjacent to the step portion.   
     
     
         2 . The prismatic secondary battery according  claim 1 ,
 wherein the convex part is arranged adjacent to a welding part.