A battery including a first conductive part, an electrode assembly, a second conductive part, and a first layer. The first conductive part includes a cover part and a concave part connected to the cover part. The concave part includes a first wall and a first side wall connected to the first wall. The electrode assembly is electrically connected to the first conductive part and the second conductive part, and is configured inside the concave part. Viewed in a first direction, the second conductive part and the electrode assembly partly overlap, the second conductive part is located in the first conductive part, the second conductive part includes a first surface and a second surface, and the second surface faces away from the first conductive part. The first layer includes a part located between the first conductive part and the second conductive part; and an insulating material.