Batteries store chemical energy and convert it to electrical energy. the chemical reactions that happen involve the movement of electrons which creates an electric current
When you charge a battery you "force" a chemical reaction. You store chemical energy. This chemical state is forced but can not be reversed until you allow current to flow in the oposite direction as in charging.
LargeGasValve t1_j9ziwzx wrote
chemical reactions are atoms exchanging electrons, all a battery does is force the atoms to exchange electrons through a wire