Patent ID: 8263253

Claim:
A secondary battery, comprising: an electrode assembly; a can having an opening at an upper portion thereof and housing the electrode assembly; a cap assembly sealing the opening of the can; and an insulation case disposed between the electrode assembly and the cap assembly, the insulation case having a first area contacting the electrode assembly and a second area located on a periphery of the first area such that there is a gap between the second area and the electrode assembly, wherein: the cap assembly contacts the insulation case on the second area, the cap assembly includes a cap plate, the cap plate has short edges with lower portions, and protrusions at the lower portions of the short edges; the insulation case includes: a body having a plate-like shape defining a bottom of the insulation case and having short edges, long edges and a lower surface, and first side walls protruding upward from the short edges of the body, and the second area includes first tapered portions tapered from a lower surface of the body toward the short edges of the body.