Tukuk-OSA battery is two electrodes soaked in an electrolyte, chosen so that one side “wants” to give up electrons and the other wants to receive them. A phone battery is lithium-ion: the anode (graphite) holds lithium atoms that readily release electrons, the cathode (a lithium-metal oxide) greedily accepts them — and discharge is lithium ions migrating through the electrolyte from one side to the other while their electron partners are forced to detour through your circuit, doing the work on the way. Charging runs the migration backwards, pushing ions home with outside electricity. There is no “charge storage” as a substance: the energy is the strained arrangement of the ions, like a drawn bow.
Cells stack in series to add voltage (each contributes ~3.7 V nominal), and in parallel to add capacity (amp-hours); a battery pack is both plus a battery-management board — the unsung electronics that balance cells, watch temperature and cut the pack before the chemistry ever runs away, because lithium’s energy density cuts both ways. The memory effect people quote is a nickel-cadmium ghost: Li-ion hates deep discharge and heat, not partial cycles, and a laptop kept on the charger or a phone charged from 20 to 80 is healthier than one cycled flat.
The comparison that shapes transport: gasoline stores roughly a hundred times more energy per kilogram than a production Li-ion pack (about 12,000 Wh/kg chemical vs 150–250 Wh/kg cell-level). Batteries win massively on efficiency — round-trip 85–95% vs a heat engine’s 20–30% — so they rule the mobile-electronics and reasonable-range-car world, while ships, planes and long-haul trucks still lean on fuel’s density until the next chemistry comes. Every phone in the room runs on sunshine turned into plants turned into coal or oil or ore, processed by electricity: batteries are stored time as much as stored energy.