Charging the battery is the process to add new energy to the battery.

During charging, an external electrical power source (the charging circuit) applies an over-voltage, forcing a charging current to flow within the battery from the positive to the negative electrode, i.e. in the reverse direction of a discharge current under normal conditions. The lithium ions then migrate from the Cathode to the Anode, where they become embedded in the porous electrode material in a process known as intercalation.

Battery charging

Charging process