Computational study of the mechanisms of superoxide-induced decomposition of organic carbonate-based electrolytes

There is increasing experimental evidence that organic carbonate-based electrolytes are incompatible with the discharge products of the nonaqueous lithium-air (oxygen) battery. Theoretically, the lithium-air battery offers the highest gravimetric density for energy storage applications, promising to revolutionize electric vehicle transportation. Calculations suggest that propylene carbonate, ethylene carbonate, and dimethyl carbonate, commonly used electrolytes in Li-ion batteries, are easily decomposed by the superoxide ion via nucleophilic attack at the ethereal carbon atom. In the case of propylene carbonate, base-mediated proton abstraction from the methyl group has to be considered as an additional solvent decomposition pathway. The present study provides a mechanistic understanding of solvent instability to assist the design of stable electrolytes for Li-air energy storage systems.