Electricity storage device and method for manufacturing electricity storage device

An electricity storage device comprising:

• a case including a tubular part that is cylindrical and that includes an opening end part at a first end, and a bottom part closing a second end of the tubular part;
• an electricity storage element disposed inside the case and including a pair of electrodes;
• a lead connected to one electrode of the pair of electrodes;
• and
• a sealing member for sealing the opening end part of the case,
• the sealing member including a gasket with an insulating property, and a sealing plate with electric conductivity,
• the gasket including a compression part interposed between the tubular part and the sealing plate, and a base that is disk-shaped and that overlaps the sealing plate, and
• the sealing plate including a displaceable part including a protrusion protruding toward the electricity storage element, and an outer peripheral part provided in a periphery of the displaceable part and clamped by the compression part,
• the base disposed between the sealing plate and the electricity storage element,
• the base including a through hole,
• the protrusion of the sealing plate inserted into the through hole,
• the lead including a folded part that is folded at least double and joined by at least one weld-deposited part,
• the protrusion of the sealing plate and the folded part of the lead being connected to each other, and
• connection between the protrusion and the lead being disconnected when the protrusion is displaced in a direction away from the lead in response to an increase in an internal pressure inside the case.