| 摘要 |
PROBLEM TO BE SOLVED: To provide a power storage device in which safety is enhanced at the time of nail penetration or collapse.SOLUTION: In a lithium ion secondary battery, since a first metal foil 42 is thinner than a third metal foil 46, the time elapsing before short circuit takes place between the first metal foil 42 and a second metal foil 44 is shortened. Consequently, the time after occurrence of short circuit in a short circuit unit 40 before occurrence of short circuit in an electrode assembly is prolonged. Furthermore, since the third metal foil 46 is thicker than the first metal foil 42, battery residual capacity can be reduced efficiently, when short circuit takes place between the second metal foil 44 and third metal foil 46. Consequently, the battery residual capacity can be reduced sufficiently to a safe level, before short circuit takes place in the electrode assembly. |
