The lithium–air battery (Li–air) is a metal–air electrochemical cell or battery chemistry that uses oxidation of lithium at the anode and reduction of oxygen at the cathode to induce a current flow. Pairing lithium and ambient oxygen can theoretically lead to electrochemical cells with the highest possible specific energy.
The theoretical energy density of the aqueous lithium–air battery based on the reaction: (2)4 Li + O2 + 6H2O = 4 (LiOH·H2O), is 1,910 Wh/kg (2,004 Wh/L) . The energy density is lower than that of the non-aqueous lithium–air system, but higher than that of the internal combustion engine.
Theoretically with unlimited oxygen, the capacity of the battery is limited by the amount of lithium metal present in the anode. The theoretical specific energy of the Li-oxygen cell, as shown with the above reactions, is 11.4 kWh/kg (excluding the weight of oxygen), the highest for a metal air battery.
2.3. Rechargeable solid-state and molten salt lithium–air batteries The serious problems of lithium–air batteries with liquid electrolytes are leakage and evaporation of the electrolyte over long operation period of more than 10 years for EVs and stationary use under open air.
Theoretically, lithium–air can achieve 12 kW·h/kg (43.2 MJ/kg) excluding the oxygen mass. Accounting for the weight of the full battery pack (casing, air channels, lithium substrate), while lithium alone is very light, the energy density is considerably lower.
Energy density of non-aqueous Li-air batteries is predicted to be 2,790 Wh/kg, and battery cells are terminated by air cathode being clogged by precipitated lithium oxides which are insoluble in electrolyte.