To facilitate the practical application of lithium-oxygen batteries, it is necessary that they be shifted from utilizing pure O2 to air. To achieve this practical application, the effects of CO2 traces in air on the electrochemistry of the battery must be accounted for. Although this effect on the electrochemistry and formation of peroxocarbonate intermediates has been well-studied, the effects of temperature change have not been well understood. Therefore, density-functional theory (DFT) calculations are employed to shed light on the temperature-dependent reaction kinetics in the highly-solvating tetraethylene glycol dimethyl ether (G4) electrolyte. DFT calculations reveal the mechanism behind the entropically-driven dwindling stabilization of metastable peroxocarbonate intermediates as a function of operating temperature. In addition to gaining insight about the temperature-dependency of G4—solute interactions, our calculations shed light on the experimentally observed accelerated precipitation of Li2CO3 with increased cycling. Namely, our DFT-based nudged elastic band (NEB) calculations suggest that partially delithiated carbonate species act as active surfaces, effectively catalyzing the formation of the Li2CO3 precipitates during subsequent discharge steps. Therefore, our study established for the first time the temperature-induced reaction mechanisms and precipitate formation in practical CO2-containing Li-O2 batteries.

Density-functional theory investigation of temperature-governed reaction mechanisms in CO2—containing Li-O2 batteries

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