A device of the present disclosure includes: a power-generation element including at least one battery cell and having a first main surface, a second main surface opposite to the first main surface, and a side surface connecting the first main surface and the second main surface; a first structure being in contact with the side surface and having a component electrochemically connected to one or more of the at least one battery cell at the side surface; and a second structure having a first member which is located near the first main surface of the power-generation element and which covers the first main surface and the first structure, the first member of the second structure has, at a region covering the first structure, an inclined structure which becomes progressively thicker with distance from the side surface.