As in the figure right, an aluminum air battery has air cathode which may be made of silver based catalyst and it helps to block CO2 to enter in the battery but it allows O2 to enter in the electrolyte. Then this oxygen reacts with H2O in KOH electrolyte solution takes electrons from solution and creates OH- ions. These ions then associate with Al anode and create Al(OH)3 and release electrons. These electrons then flow to the air anode from aluminum cathode through the external circuit for compensating lack of electrons in the electrolyte solution due to cathode reduction reaction.