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.