ELI5: Explain Like I'm 5

Lithium-ion battery

A lithium-ion battery is a type of rechargeable battery that uses lithium, a kind of metal, to store energy. When you're using something that needs power, like your phone, the energy stored in the lithium-ion battery is released and used to power the device. When the battery runs out over time, you need to recharge, or plug it in, to put more energy back in and make it work again.