POWER SUPPLY UNIT AND MANUFACTURING METHOD OF THE SAME

PROBLEM TO BE SOLVED: To provide a sealed battery requiring a lid body with a thickness of 0.3 mm or more, which exhibits an excellent operating pressure accuracy of a valve and comprises a safety device having a structure that can be manufactured with high productivity.SOLUTION: A safety valve part 206 is provided on a part of a lid body 202. The safety valve part 206 consists of a valve part 207 and a cleavage part 208 surrounding it, and the cleavage part 208 is extended from the lid body 202 toward the outside of a cell with its thickness made thinner than the thickness of the lid body to be connected to the valve part 207. By employing a structure that, when the internal pressure of the cell rises, allows the tensile stress to be concentrated on a thinnest part 209 of the cleavage part 208 so as to break the cleavage part, work hardening of the material of the cleavage part is decreased and a stable valve operating pressure is ensured, and the safety valve part can be easily manufactured by a press machine.