The 21700 battery derives its name from its physical dimensions, measuring 21mm in diameter and 70mm in length. This type of battery is ideal for high-performance applications, such as electric vehicles, power tools, and high-powered flashlights, where reliable and powerful energy sources are crucial.

Compared to 18650 batteries, the 21700 batteries offer a higher capacity and a higher energy density. They are also known for their long lifespan and relatively low self-discharge rate, making them a popular choice for various applications.

In recent years, 21700 batteries have become increasingly popular, and many electronic devices that previously used 18650 batteries have started transitioning to use 21700 batteries due to their superior performance.