Secondary battery

Abstract

Secondary battery (10) comprising a housing (100), a bare cell (200) and an upper cover assembly (300); wherein the housing (100) has an opening (110) at one end; the bare cell (200) is arranged in the housing (100); the upper cover assembly (300) has an end cover (310) and a lower plastic element arranged on the end cover (310); the end cover (310) is hermetically connected to the opening (110); the end cover (310) is provided with a through-hole (312) for an explosion-proof valve, configured to accommodate an explosion-proof valve (500);a side of the lower plastic element (320) away from the end cover (310) is oriented towards the bare cell (200), the lower plastic element (320) is provided with an exhaust gas passage (321) which is in contact with the explosion-proof valve (500), and the area dimension of the passage (312) for the explosion-proof valve is 1.5% to 8% of an area dimension of the end cover (310); several exhaust gas passage openings (321) are provided, which are spaced apart from each other, a second surface dimension of an orthographic projection of all exhaust gas passage openings (321) on the end cover (310) is 1% to 5% of the surface dimension of the end cover (310), the second surface dimension lies in a range of 42 mm² to 3750 mm³, and the surface dimension of the end cover (310) lies in a range of 4200 mm² to 75000 mm².

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