| CPC H01M 50/367 (2021.01) [H01G 11/80 (2013.01); H01M 2200/20 (2013.01)] | 14 Claims |

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1. A valve device for a power storage device, the power storage device comprising a power storage device element and a housing in which the power storage device element is housed, the valve device for being attached to the housing of the power storage device, wherein
the valve device is configured to reduce an internal pressure of the housing when the pressure increases due to a gas generated inside the housing,
the valve device comprises:
a first portion in which a valve mechanism is formed, the valve mechanism being configured to reduce the internal pressure of the housing when the pressure increases due to a gas generated inside the housing; and
a second portion in which a vent passage is formed, the vent passage being configured to guide the gas generated inside the housing to the valve mechanism, wherein
the second portion has a wing-shaped extending end formed with a thickness that decreases toward an end in a width direction orthogonal to a thickness direction of the housing,
the housing is formed of a laminate including at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order, and
such that an amount of helium leakage from a secondary side to a primary side of the valve device is 5.0×10−11 Pa·m3/sec or more and 5.0×10−6 Pa·m3/sec or less, as measured in a 25° C. environment.
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