The oxydation-reduction reaction during the discharge of a galvanic battery is: Zn + Cu2+ = Zn2+ + Cu. During the charging phase, the reaction will be in the opposite way. An external source provides electrons and energy for recharging the battery. If we consider the battery completly discharged, emf is zero. During the recharging phase, the emf will increase gradually. My question is: Does the emf increase because the reactants of the charging phase are reappearing again during the phase of recharge? When the reactants reappear, Does the reaction during discharge happens at the same time of the recharging one? How about the charge separation on the electrodes? Do they reappear again thus creating electric field inside the battery? How about the ions inside the salt bridge, do they move in the opposite direction of the charging phase?