Recent advances in charge mechanism of noble metal-based cathodes for Li-O2 batteries

Lithium-oxygen (Li-O2) batteries are considered as the next generation for energy storages systems due to the higher theoretical energy density than that of Li-ion batteries. However, the high charge overpotential caused by the insulated Li2O2 results in low energy efficiency, side reaction from electrolyte and cathode, and therefore poor battery performance. Designing noble metal-based catalysts can be an effective strategy to develop high-performance Li-O2 batteries with low charge overpotentials and outstanding cycle stability. However, the charge mechanism for noble metal-based catalysts is not clear and even contradictory. Herein, several charge mechanisms of Li2O2 are first discussed. Subsequently, the possible charge processes of Li-O2 batteries with noble metal-based catalysts are illustrated. In addition, the future development for noble metal-based catalysts is outlined.