BATTERY

A battery is provided and includes a negative electrode active material layer, a positive electrode active material layer and a separator. In a first direction, the positive electrode active material layer includes a first portion and a second portion connected to the first portion. The second portion includes a first end, and the first portion includes a first surface. The first surface is connected to the second portion through a first connection, the first end is an end of the positive electrode active material layer, and a thickness of the second portion in a second direction decreases from the first connection to the first end. The second direction is perpendicular to the first direction. The negative electrode active material layer includes a third portion and a second end located on one side of the third portion in the first direction, and the third portion includes a second surface having at least a part arranged opposite to the first surface. A first layer binds the first end, the second portion and the first surface, and covers the first end, the second portion and a part of the first surface. The first layer is capable of blocking migration of ions. The battery helps to inhibit lithium precipitation while maintaining energy density of the battery.