The metal named in rechargeable lithium-ion batteries is lithium. Lithium is element 3, the lightest metal and the lightest solid element at room temperature.
Lithium-ion batteries move lithium ions between a negative electrode and a positive electrode during charging and discharging. The lithium is usually present in chemical compounds within the electrodes rather than as a large block of pure metal. This design allows batteries to store substantial energy relative to their mass.
Lithium is a soft, silvery metal that reacts readily with water and air, so it is stored and handled carefully. It belongs to the alkali metals, a group that also includes sodium and potassium. Lithium compounds have uses beyond batteries, including glassmaking, ceramics, lubricating greases, and some medicines.
The battery name does not mean every part is made from lithium. Cathode materials can contain combinations of nickel, manganese, cobalt, iron, phosphate, or other elements. Battery chemistry varies, but lithium ions remain central to the technology called lithium-ion.