Charging is to reverse the discharge process on top.
Take lead battery as an example:
Lead-acid battery is a practical battery which is manufactured first. The principle is as follows:
Insert A, b two lead plates into sulfuric acid solution, lead in sulfuric acid effect, so that a, b two lead plate on the formation of lead sulfate, the solution is also lead to the saturation of sulfuric acid, which is still no potential, to recharge the battery, the chemical reaction occurred at the Poles are as follows:
It can be seen that after charging, a plate on the PbO2 becomes a positive, b board PB become negative. When discharging, the two polar reactions occur as follows:
Cathode: pbo2+h2so4+2h+ -2e-→pbso4+2h2o-2e-;
When the discharge occurs, the reaction is the reverse process of charging. When charging, the maximum electromotive force is 2.2V. When discharging, the electromotive force reduces gradually, must charge when low to 1.8V, otherwise will damage the plate.