摘要 |
A releasing pressure and a pressure releasing position, when enclosing films are expanded by gas produced at an abnormal time, are easily and positively configured. A film-enclosed battery (1) has a battery element (2) and two enclosing films (4, 5) for sealing the battery element (2). The enclosing films (4, 5) include heat-sealable resin layers and air-impermeable layers, and the heat-sealable resin layers and air-impermeable layers, and the heat-sealable resin layers that are face each other hold the battery element (2) and seal the battery element (2) when their peripheral edges are thermally fused. A cross-linking structure (8) formed by cross-linking heat-sealable resin layer is formed in one of the enclosing films (4, 5) so that a region in part of a heat-sealed area (6) has a position exposed to a battery element housing unit and another portion in contact with outside air.
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