Nitrate Molten Salt Electrolytes with Iron Oxide Catalysts for Open and Sealed Li-O2 Batteries.

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.