Discovery of organic catalysts boosting lithium carbonate decomposition toward ambient air operational lithium–air batteries

Abstract

The practical application of lithium–air batteries (LABs), which operate through electrochemical formation and decomposition of lithium peroxide (Li₂O₂), is limited by pure oxygen feeding. When using ambient air instead of pure oxygen, the detrimental lithium carbonate (Li₂CO₃) formation on the cathode surface accelerates, limiting the stable operation of LABs. Although redox molecules have been widely studied as a homogeneous catalyst to facilitate Li₂O₂ oxidation in LABs, their ability to decompose Li₂CO₃ has barely been explored. Here, we examined the catalytic effect of a series of organic redox mediators on removing Li₂CO₃. Systematic investigation confirms that the molecules with a redox potential higher than 3.7 V vs. Li/Li⁺ significantly lower the potential of Li₂CO₃ oxidation, for which the reaction mechanism was further supported by in situ gas analysis. This study suggests new possibilities of exploiting redox molecules to ensure efficient oxidation of both Li₂O₂ and Li₂CO₃ in LABs in ambient air.