Abstract: The secondary cell—includes an exterior can, a sealing body closing one end of the exterior can, an electrode group disposed inside the exterior can, and an insulating plate disposed between the sealing body and the electrode group. In the electrode group, a positive electrode and a negative electrode are wound in a spiral shape with a separator interposed between. The insulating plate is shaped as a disc having a lead hole penetrated by a positive electrode lead drawn out from the electrode group, and a center hole penetrating the center part of the insulating plate. The outer edge of the lead hole includes a curve part positioned along an arc that is concentric with respect to the outer circumference of the insulating plate as seen in plan view, and linear parts-positioned along a chord linking the two ends of the arc.

Abstract: A cylindrical battery provided with: an electrode body in which a positive electrode plate and a negative electrode plate are rolled with a separator being disposed therebetween; an electrolytic solution; an external packaging can which has a bottomed cylindrical shape and which houses the electrode body and the electrolytic solution; and a sealing plate which is fixed by swaging to an opening of the external packaging can with a gasket therebetween. As viewed in a planar view, the sealing plate is formed to have a circular shape, and has a central part recessed inward of the battery. In the sealing plate, an outer circumferential edge fixed by swaging to the external packaging can is configured to bifurcate into a first portion and a second portion in the thickness direction.

Abstract: A cylindrical battery wherein a central part of a sealing plate, fixed by swaging to an opening of an external packaging can, is configured to be warped toward the inner part of the battery. One embodiment is provided with: an electrode body in which a positive electrode plate and a negative electrode plate are rolled with a separator being disposed therebetween; an electrolytic solution; an external packaging can which has a bottomed cylindrical shape and which houses the electrode body and the electrolytic solution; and a sealing plate which is fixed by swaging to an opening of the external packaging can with a gasket therebetween. In the sealing plate, prior to the swage fixing, an outer peripheral edge to be fixed by swaging to the external packaging can is formed inclined so as to be directed to the inner part of the battery, toward radially outward.

Abstract: A sealed cell having a safety mechanism is provided. The safety mechanism has a non-resealable valve structure formed in a sealing plate that seals the cell. The valve structure is broken as soon as the internal pressure reaches or exceeds a predetermined value so as to permit the internal gas to be released outside. The valve structure has at least one dome protruding toward the interior of the cell, which in turn has at the periphery thereof a break groove for facilitating the breakage of the valve structure. This makes the valve structure highly responsive to the internal pressure and causes to form a break-opened orifice of a sufficient area at the time of operation in response to the increased internal pressure. The valve structure is not unnecessarily broken by the impacts of, for example, dropping. As a result, the safety of the sealed cell is significantly improved.

Abstract: A sealed cell having a safety mechanism is provided. The safety mechanism has a non-resealable valve structure formed in a sealing plate that seals the cell. The valve structure is broken as soon as the internal pressure reaches or exceeds a predetermined value so as to permit the internal gas to be released outside. The valve structure has at least one dome protruding toward the interior of the cell, which in turn has at the periphery thereof a break groove for facilitating the breakage of the valve structure. This makes the valve structure highly responsive to the internal pressure and causes to form a break-opened orifice of a sufficient area at the time of operation in response to the increased internal pressure. The valve structure is not unnecessarily broken by the impacts of, for example, dropping. As a result, the safety of the sealed cell is significantly improved.