Energy storage device and method for manufacturing energy storage device

An energy storage device comprising:

• an electrode body;
• and
• an outer packaging that seals the electrode body, wherein
• the outer packaging is constituted by a film-like outer packaging member,
• the outer packaging includes a piece in which peripheral edges of surfaces that face each other are joined together in a state in which the outer packaging member is wrapped around the electrode body,
• a base portion of the piece is at a boundary between surfaces of the outer packaging,
• a space in which the surfaces that face each other are not joined is in the piece,
• in the piece, a region in which the surfaces that face each other are joined together and a region in which the surfaces that face each other are not joined are side-by-side in a vicinity of the boundary, and
• in the region in which the surfaces that face each other are not joined, opposing inner surfaces of the outer packaging member face each other directly without any intervening element.

A method for manufacturing an energy storage device from an unfinished product,

• the unfinished product including
• an electrode body, and
• an outer packaging that seals the electrode body,
• the outer packaging being constituted by a film-like outer packaging member,
• the outer packaging including a piece in which peripheral edges of surfaces that face each other are joined together in a state in which the outer packaging member is wrapped around the electrode body,
• a base portion of the piece being at a boundary between surfaces of the outer packaging,
• a space in which the surfaces that face each other are not joined being in the piece, and
• in the piece, a region in which the surfaces that face each other are joined together and a region in which the surfaces that face each other are not joined being side-by-side in a vicinity of the boundary,
• the manufacturing method comprising:
• unsealing the outer packaging with use of the piece and discharging gas from the outer packaging;
• and
• resealing the outer packaging by joining the surfaces that face each other in at least a portion of the piece.