Li₂ MnO₃ : A Catalyst for a Liquid Cl₂ Electrode in Low-Temperature Aqueous Batteries.

Abstract

Li₂ MnO₃ has been contemplated as a high-capacity cathode candidate for Li-ion batteries; however, it evolves oxygen during battery charging under ambient conditions, which hinders a reversible reaction. However, it is unclear if this irreversible process still holds under subambient conditions. Here, the low-temperature electrochemical properties of Li₂ MnO₃ in an aqueous LiCl electrolyte are evaluated and a reversible discharge capacity of 302 mAh g^-1 at a potential of 1.0 V versus Ag/AgCl at -78 °C with good rate capability and stable cycling performance, in sharp contrast to the findings in a typical Li₂ MnO₃ cell cycled at room temperature, is observed. However, the results reveal that the capacity does not originate from the reversible oxygen oxidation in Li₂ MnO₃ but the reversible Cl₂ (l)/Cl^- (aq.) redox from the electrolyte. The results demonstrate the good catalytic properties of Li₂ MnO₃ to promote the Cl₂ /Cl^- redox at low temperatures.