Patent attributes
A power generation element is stored in an inner space formed by combining a battery case (2) and a seal case (3) formed as a half-shell body with a rectangular plane shape such that the individual openings are placed opposing to each other with a gasket (4) interposed therebetween, and the gasket (4) is pressed between the open end of the battery case (2) and a step (35) of the seal case (3) for sealing during caulking. Because recesses (36) are formed on the individual peripheral edges of a bottom surface (31) of the seal case (3), the strength of straight parts of a seal-case side-peripheral surface (32) of the seal case (3) increases against a seal pressure during caulking, and a decrease of seal capability caused by the straight parts bulging toward the outside during sealing is prevented.
