BATTERY

A battery is provided and includes a negative electrode active material layer, a positive electrode active material layer, and a separator disposed between the positive electrode active material layer and the negative electrode active material layer. The negative electrode active material layer includes a first portion and a second portion. The second portion includes a first surface and a first end. The first surface is connected to the first portion through a first connection, and the first end is opposite from the first connection and is an end of the negative electrode active material layer. A thickness of the second portion decreases from the first connection to the first end. The positive electrode active material layer includes a third portion and a fourth portion, and the fourth portion includes a second surface and a second end. The second surface and the second surface are at least partially arranged opposite to each other, and the second surface is connected to the third portion through a second connection. The second end is opposite from the second connection and is an end of the positive electrode active material layer. A thickness of the fourth portion decreases from the second connection to the second end. The first connection is located between the second connection and the second end. The battery in this application helps to inhibit lithium precipitation while maintaining energy density of the battery.