Cylindrical secondary battery

There is provided a cylindrical secondary battery including: an electrode assembly including a first electrode plate, a separator, and a second electrode plate; a case accommodating the electrode assembly and electrically connected to the second electrode plate; a terminal passing through a lower surface of the case and electrically connected to the first electrode plate; and a cover plate sealing an upper end portion of the housing and having an exhaust port. The exhaust port is a thinner portion of the cover plate than other regions of the cover plate, and has a central notch having an annular shape and at a central portion of the cover plate, and an inner peripheral notch having a linear shape extending from the central notch toward an edge of the cover plate. 提供了一种圆柱形二次电池,所述圆柱形二次电池包括：电极组件，包括第一电极板、隔膜和第二电极板；壳体，容纳电极组件并电连接到第二电极板；端子，穿过壳体的下表面并且电连接到第一电极板；以及盖板，密封壳体的上端部并且具有排气口。排气口是与盖板的其他区域相比盖板的较薄的部分，并且具有呈环形形状且处于盖板的中心部分处的中心凹口以及从中心凹口朝向盖板的边缘延伸的具有线形形状的内周凹口。