| 摘要 |
The embodiments are aimed at avoiding battery damage due to overcharge and achieving a highly safe reliable secondary battery. A lithium ion secondary battery according to an embodiment includes: an electrode assembly formed by rolling up a positive electrode, a separator, and a negative electrode and an overcharge preventer, which are incorporated in a battery can. The overcharge preventer includes: a voltage detector configured to detect a voltage equal to or higher than a predetermined value between the positive and negative electrodes, a fuse body provided on the positive electrode lead or the negative electrode lead, and a switch unit member. The fuse body and the switch unit are connected in series to constitute a short circuit for the electrode assembly, and when the voltage between the positive and negative electrodes reaches a predetermined value or higher in the case of charging, the voltage detector closes the switch unit, and melt down the fuse body by energy accumulated in the electrode assembly. |
