Nitrate Molten Salt Electrolytes with Iron Oxide Catalysts for Open and Sealed Li–O₂Batteries

Li–O2 batteries with nitrate molten salt electrolytes are attracting considerable attention owing to their various electrochemical pathways to form a discharge product upon the open and sealed systems. Here, we investigate nitrate molten salt electrolyte-based open and sealed Li–O2 batteries with pristine and iron oxide catalysts. Through the systematic analysis of various Li–O2 battery characteristics, we observe the irreversible electrochemical reactions of the open Li–O2 battery with an iron oxide catalyst that erodes the battery performance due to the detrimental parasitic reaction of H2 gas evolution from the Li anode. In contrast, the sealed Li–O2 system with cathodes containing the iron oxide catalyst exhibits the formation and decomposition of Li2O discharge products without significant side reactions, which guarantees long cycle endurance, high-rate performance, and a gravimetric energy density. Thus, promising electrochemical results from the sealed Li–O2 system with the iron oxide catalyst provide a viable strategy for the high-performance molten salt-based Li–O2 battery.