CYLINDRICAL SEALED BATTERY AND BATTERY PACK

A nonaqueous electrolyte secondary battery representing an embodiment of a sealed battery of the present invention includes a bottomed cylindrical exterior case, a sealing member, a cylindrical wound electrode assembly and an electrolyte. An open end of the exterior case is crimped together with the sealing member via an insulating gasket so as to form a seal. The sealing member includes a lid having a thin and fragile portion, an insulating ring, and a terminal plate having a thin and fragile portion. The terminal plate is electrically connected to a positive electrode current collector leading out from the cylindrical wound electrode assembly. The lid and the terminal plate are electrically connected within an opening of the insulating ring. The lid is disposed so as to expose an outer side of at least a portion of the lid opposed to the opening of the insulating ring directly to an outside environment.