Metal–air electrochemical cell

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The types of metal–air batteries have different capacities

A metal–air electrochemical cell is an electrochemical cell that uses an anode made from pure metal and an external cathode of ambient air, typically with an aqueous electrolyte.[1][2]


The Li–air battery discharge reaction between Li and oxygen Li2O, according to 4Li + O2 → 2Li2O, has an open-circuit voltage of 2.91 V and a theoretical specific energy of 5210 Wh/kg. Since oxygen is not stored in the battery, the theoretical specific energy excluding oxygen is 11140 Wh/kg (40.1 MJ/kg). Compare this to the figure of 12,200 Wh/kg (44 MJ/kg) for gasoline (see petrol energy content).

Metal–air battery Calculated open-circuit voltage, V Theoretical specific energy, Wh/kg
(including oxygen)
Theoretical specific energy, Wh/kg
(excluding oxygen)
Aluminium–air 1.2 4300[3] 8140[4]
Calcium-air 3.12 2990 4180
Lithium–air 2.91 5210 11140
Magnesium–air 2.93 2789 6462
Sodium–air 2.3[5][6] 1677 2260
Zinc-air 1.65 1090 1350

See also[edit]