When discharging a battery, the cathode is the positive electrode, at which electrochemical reduction takes place. As current flows, electrons from the circuit and cations from the electrolytic solution in the device move towards the cathode. Although these processes are reversed during cell charge in secondary batteries, the positive electrode in these systems is still commonly, if somewhat inaccurately, referred to as the cathode, and the negative as the anode.
Lithium Ion Cells
When discharge begins the lithiated carbon releases a Li+ ion and a free electron. Electrolyte, that can readily transports ions, contains a lithium salt that is dissolved in an organic solvent. The Li+ ion, which moves towards the electrolyte, replaces another Li + ion from the electrolyte, which moves towards the cathode. At the cathode/electrolyte interface, Li+ ions then become intercalated into the cathode and the associated electron is used by the external device.