Electric storage cell, covering film and electric storage module

A covering film for forming a housing space in which to house an electric storage element, comprising:

• a metal layer with a first principal face on an electric storage element side and a second principal face on an opposite side,
• an internal resin layer made of resin laminated onto the first principal face;
• and
• an external resin layer made of resin laminated onto the second principal face,
• wherein a groove part is formed in the metal layer in a thickness direction of the covering film on a second principal face side of the metal layer, through the external resin layer, wherein the groove part extends continuously and steplessly from the external resin layer into the metal layer in a thickness direction of the covering film, and
• wherein the covering film has a first region where the internal resin layer has a first thickness and a second region constituted by a recess formed in an inner-side surface of the internal resin layer opposite to an interface side between the metal layer and the internal resin layer where the internal resin layer has a second thickness smaller than the first thickness in a thickness direction of the covering film, and the groove part is aligned with the recess of the second region in the thickness direction.

An electric storage module comprising multiple electric storage cells stacked together, wherein the electric storage cell has:

• an electric storage element;
• and
• a covering body that houses the electric storage element and is constituted by a covering film having:
• a metal layer with a first principal face on an electric storage element side and a second principal face on an opposite side,
• an internal resin layer made of resin laminated onto the first principal face, and
• an external resin layer made of resin laminated onto the second principal face,
• wherein the covering body is constituted by:
• an element housing part that forms a flat surface facing the electric storage element,
• a seal part formed by internal resin layers thermally fused to each other along a peripheral edge of the element housing part;
• and
• an intermediate part between the housing part and seal part,
• wherein a groove part is formed in the intermediate part in the metal layer on the second principal face side of the metal layer, through the external resin layer, wherein the groove part extends continuously and steplessly from the external resin layer into the metal layer in a thickness direction of the covering film, wherein the groove part is elongated in a straight line and provided in parallel to a boundary line between the intermediate part and the seal part.