Patent ID: 10305077

Abstract:
A small cylindrical lithium-ion secondary battery provided with a safety mechanism that enables internal pressure to be released when an anomaly occurs. The battery includes an electrode group formed of a positive electrode and a negative electrode that are wound or stacked with a separator interposed therebetween, an electrolytic solution, a battery case that contains the electrode group and the electrolytic solution, and a sealing body. The battery case has an outer diameter of 10 mm or less. The sealing body includes a ring having a through-hole and includes a sheet-like or film-like valve member disposed such that the valve member covers the through-hole of the ring, and a safety mechanism that causes the valve member to cleave when the internal pressure reaches a predetermined pressure is disposed therein. The ring includes protrusions formed of linear ridge lines that protrude toward an inside of the through-hole.