Electricity storage device

An electricity storage device comprising an electrode assembly, wherein

• the electrode assembly is configured by stacking electrodes that have different polarities from each other with a separator that insulates the electrodes from each other,
• each of the electrodes has a rectangular foil, an active material layer in which active material is arranged on the foil, and a tab protruding from a part of one side extending in a longitudinal direction of the foil,
• one end in the longitudinal direction of the electrode coincides with one end in the longitudinal direction of the active material layer,
• the other end in the longitudinal direction of the electrode coincides with the other end in the longitudinal direction of the active material layer,
• the active material has a constant coating direction,
• the separator has one direction in which the stretchability of the separator is higher than in the other directions,
• the coating direction of the active material in at least one of the electrodes is a direction along the protruding direction of the tab,
• the direction of the high stretchability in the separator intersects the coating direction of the active material of at least one of the electrodes,
• the separator is one of a plurality of separators that constitutes the electrode assembly, and
• the separators are stacked such that the directions of the high stretchabilities coincide with each other.