CLOSED BATTERY

PROBLEM TO BE SOLVED: To provide a closed battery without generating leak and excellent in reliability even in case a heat cycle is impressed. SOLUTION: In the closed battery consisting of a battery outer package case with an outer package structure in which a headed rivet-like electrode terminal having a head part 22 with an outer diameter larger than an inner diameter of a through-hole of a plate-like sealing lid and a shaft part 23 with an outer diameter smaller than an inner diameter of the through-hole is inserted into the through-hole through a ring-like insulating sealing member 5, the outer diameter of the sealing lid is expanded by caulking the electrode terminal, and the insulating sealing member is compressed and pinched to be sealed, and a cathode as well as an anode housed in the battery outer package case, the through-hole of the sealing lid is gradually tapered off from a side opposed to an end part toward a side opposed to a head part of the electrode terminal, and an inner diameter D1 specifying a first narrow part of a side of the insulating sealing member opposed to the end part of the electrode terminal, and an inner diameter D2 specifying a second narrow part of a side of the insulating sealing member opposed to the head part of the electrode terminal are in a relation of: D1>D2. COPYRIGHT: (C)2009,JPO&INPIT