Battery device, manufacturing method of battery device, and energy storage device

The invention discloses a battery device, a manufacturing method of the battery device and energy storage equipment. The battery device comprises a box body and at least two battery modules, an accommodating cavity is formed in the box body; the at least two battery modules are arranged in the accommodating cavity along a first direction, each battery module comprises at least two battery packs, the at least two battery packs are arranged along the first direction, each battery pack comprises at least two battery monomers, the at least two battery monomers are arranged side by side along a second direction, and the first direction is different from the second direction; the cooling assembly comprises two cooling plates, and the cooling plates clamp the at least two battery packs and are attached to the side faces, with the largest area, of the battery monomers. In the battery device, the cooling plate is attached to the side surface with the largest area of the battery monomer, so that the cooling efficiency