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

•Li2O2 and Li2CO3 are first identified as discharge products of Li-CO2/O2 batteries.•CO2 participates in discharge reaction via a chemical route between Li2O2 and CO2.•Ex-situ EPR and operando fluorescence techniques are used to study 1O2 formation.•CO2 captures O2•− that decomposed from Li2O2 to suppress 1O2 yield during charging.•CO2 stabilizes Li anode by forming Li2CO3 on the anode surface instead of LiOH.