Exterior member for battery element and non-aqueous electrolyte secondary battery using the same

A non-aqueous electrolyte secondary battery is provided, including a battery element having a positive electrode, a negative electrode and a separator; an exterior member for the battery element including: a first layer; a second layer; a bending part for partitioning the first layer and the second layer from each other; a sealing part which is formed by a peripheral part of the first layer in contact with a peripheral part of the second layer and which seals the battery element; a thick-walled part that is a portion of the sealing part and includes at least a part of the bending part, wherein the thick-walled part has a greater thickness in a thickness direction of the battery element than a thickness of a portion of the sealing part other than the thick-walled part, and wherein the thickness direction of the battery element corresponds to a stacking direction of the battery element.