Metal–air electrochemical cell
Metal–air electrochemical cells (or metal–air batteries) are electrochemical cells that use an anode made from pure metal and an external cathode of ambient air, typically with an aqueous or aprotic electrolyte. They function by the electrochemical oxidation of the metal at the anode and the reduction of oxygen from the air at the cathode.
Source: Wikipedia — Metal–air electrochemical cell (CC BY-SA 4.0)