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Your battery doesn't store electricity — it stores a tug-of-war
💡 A lithium-ion battery stores energy not as trapped electricity but as the position of lithium ions, which shuttle back and forth between two electrodes.
A lithium-ion battery holds almost no electricity as electricity. Instead it stores energy as position: where its lithium sits. Inside are two electrodes separated by a liquid electrolyte — a negative anode (usually layered graphite) and a positive cathode (a lithium-metal oxide). Charging uses outside power to force lithium ions out of the cathode, through the electrolyte, to nestle between the graphite sheets. That crowded, strained arrangement is the stored energy.
When you unplug and use the device, the ions do what they "want": they drift back to the cathode. Each ion that crosses the electrolyte pushes a matching electron through your phone's circuit the long way around — and that moving-electron current is the power your device runs on.
This is why engineers nickname it the "rocking chair" battery: the same lithium rocks back and forth, and nothing is consumed. It also explains aging — every trip strains the electrode lattices a little, and side reactions quietly lock away a few ions for good, so capacity fades cycle by cycle.