21700 batteries are rechargeable lithium ion batteries that have been used in many electronic devices such as cell phones, laptops, cameras, camcorders, digital cameras, MP3 players, GPS units, PDAs, video games, toys, medical equipment, power tools, electric vehicles, and more.

21700 batteries are rechargeables that use lithium ions for energy storage. They are commonly used in portable electronics because they provide high capacity and long life.

They are also known as 18650 batteries or 18650 cells.

These batteries are available in different sizes and capacities. The size refers to the diameter of the battery while the capacity refers to how much charge the battery holds. A higher number means a larger capacity and a smaller diameter.

They are also commonly known as 18650 batteries or AA batteries.

There are two main types of 21700 batteries: button cells and prismatic cells. Button cells are cylindrical with rounded edges and prismatic cells are rectangular with flat sides. Both types of 21700 batteries are made up of three parts: positive electrode, negative electrode, and separator.