The invention provides a battery, and the battery comprises a housing and a bare cell located in the housing. The bare cell comprises pole pieces A, pole pieces B and a diaphragm, and the pole piece Acomprises a first empty foil area and a first coating area, wherein the first coating area is divided into two mutually independent parts by a single first empty foil area; the diaphragm is arrangedbetween the pole pieces A and the pole pieces B which are adjacent to each other to prevent short circuit between the pole piece A and the pole pieces B; at least two pole pieces A are arranged in a stacked mode, and the pole pieces A arranged in the stacked mode are welded together through a first empty foil area. Two pole pieces B are arranged between every two adjacent pole pieces A and locatedon the two sides of the first empty foil area respectively. The problem that the energy density of a battery module in the prior art is difficult to improve is solved, and the energy density of the battery module is effectively improved.