A battery includes an unpackaged cell and a packaging film, where an edge of the unpackaged cell includes at least one first open space. The first open space runs through a thickness direction of the unpackaged cell. No unpackaged cell exists in the first open space. The packaging film encloses an enclosed space that accommodates the unpackaged cell. The packaging film forms a first sealing part in the first open space. The first sealing part does not cover the unpackaged cell. The first sealing part encloses a second open space with a packaging film on a sidewall of the first open space. The first open space partly overlaps the second open space.