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The nonaqueous rechargeable lithium–O₂ battery containing an alkyl carbonate electrolyte discharges by formation of C₃H₆(OCO₂Li)₂, Li₂CO₃, HCO₂Li, CH₃CO₂Li, CO₂, and H₂O at the cathode, due to electrolyte decomposition. Charging involves oxidation of C₃H₆(OCO₂Li)₂, Li₂CO₃, HCO₂Li, CH₃CO₂Li accompanied by CO₂ and H₂O evolution. Mechanisms are proposed for the reactions on discharge and charge. The different pathways for discharge and charge are consistent with the widely observed voltage gap in Li–O₂ cells. Oxidation of C₃H₆(OCO₂Li)₂ involves terminal carbonate groups leaving behind the OC₃H₆O moiety that reacts to form a thick gel on the Li anode. Li₂CO₃, HCO₂Li, CH₃CO₂Li, and C₃H₆(OCO₂Li)₂ accumulate in the cathode on cycling correlating with capacity fading and cell failure. The latter is compounded by continuous consumption of the electrolyte on each discharge.