Unveiling the reaction mechanism and ¹O₂ suppression effect of CO₂ in Li-CO₂/O₂ battery through the reacquaintance of discharge products

Li-CO₂/O₂ battery has been described as an exceptional strategy for CO₂ conversion, however, the effect of CO₂ is urgently required for development of practical cells. Here, we innovatively unveil the mysterious role of CO₂ by comprehensively analyzing the discharge/charge products, the reaction mechanism, the ¹O₂ yield, and the corrosion of Li anode in batteries. Unlike previous results where Li₂CO₃ is the sole discharge product, Li₂O₂ and Li₂CO₃ are definitely identified as final discharge products of Li-CO₂/O₂ battery, confirming a chemical reaction between Li₂O₂ and CO₂ during discharge in TEGDME solvent. During charging, CO₂ affects the decomposition pathway of Li₂O₂ by capturing O₂ ^•−, thus suppressing the formation of notorious ¹O₂. Additionally, introduction of CO₂ influences the morphology and structure of the discharge products and improves the stability of Li anode. Since the above effects of CO₂ are closely related to the CO₂/O₂ ratio, appropriate CO₂/O₂ ratio can optimize various effects of CO₂ and obtain the best battery performance.