Lithium-ion phone batteries work by storing electrons from your connected power source. While you charge your phone, these electrons will attract lithium ions, which are microscopic particles of lightweight metal. These lithium ions move around inside the battery from the cathode to the anode. After charging your device and disconnecting it from your charger, the ions will travel in the opposite direction, creating a circuit that powers your device. Once all of the ions return to the cathode, your battery will be â€œdead.â€