| 摘要 |
PURPOSE: A secondary battery employing safety equipment is provided, to improve the stability of a battery by enabling a certain part to be fractured when a case is expanded by overcharging. CONSTITUTION: The secondary battery comprises a battery part comprising multilayered positive electrode plates, separators and negative electrode plates; and a multilayered case(22) where the battery part is inserted, and which comprises an interior layer(230) made of a polymer resin, an exterior layer(250) made of a polymer resin and an intermediate layer(210, 220) made of a metal thin plate containing at least one hole, placed between the interior layer and the exterior layer. Preferably the metal thin plate is aluminium; at least one metal thin plate has a hole whose thickness is thinner than that of the other part; and the thickness of the intermediate layer is 50-300 micrometer. Preferably the interior layer is a double layer of a polyamide-based resin and an ethylene-vinyl alcohol copolymer resin; and the external layer is made of polyamide, high density polyethylene, polyethylene terephthalate or polypropylene.
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