Low-Temperature CO₂-Assisted Lithium–Oxygen Batteries for Improved Stability of Peroxodicarbonate and Excellent Cyclability

Lithium-oxygen (Li-O-2) batteries suffer from undesirable chemical reactions. Side products, such as lithium carbonates (Li2CO3), undergo partial decomposition during charging, and their accumulation leads to poor cyclability. Herein, we show significantly improved cyclability by forming peroxodicarbonate (C2O62-) as the soluble discharging product, hence preserving its stability at low temperatures. The Li-O-2 cells comprising 10% CO2 gas and tetraglyme electrolyte solution form anhydride-linked C2O62-. However, despite the improved stability of C2O62- at 0 degrees C, the low ionic conductivity of tetraglyme results in poor cyclability. In contrast, dimethylacetamide-based cells produce peroxo-linked C2O62- and offer over 100 cycles at -10 degrees C. During cycles, the first charging plateaus belonging to C2O62- oxidation appear consistently at 3.75 V (vs Li/Li+. In addition, Li2CO3 is entirely decomposed during the second charging plateau at 4.45 V. Our results show promise for the development of highly rechargeable Li-O-2/CO2 batteries.