Li‐CO2 Batteries Efficiently Working at Ultra‐Low Temperatures

Lithium‐carbon dioxide (Li‐CO2) batteries are considered promising energy‐storage systems in extreme environments with ultra‐high CO2 concentrations, such as Mars with 96% CO2 in the atmosphere, due to their potentially high specific energy densities. However, besides having ultra‐high CO2 concentration, another vital but seemingly overlooked fact lies in that Mars is an extremely cold planet with an average temperature of approximately −60 °C. The existing Li‐CO2 batteries could work at room temperature or higher, but they will face severe performance degradation or even a complete failure once the ambient temperature falls below 0 °C. Herein, ultra‐low‐temperature Li‐CO2 batteries are demonstrated by designing 1,3‐dioxolane‐based electrolyte and iridium‐based cathode, which show both a high deep discharge capacity of 8976 mAh g−1 and a long lifespan of 150 cycles (1500 h) with a fixed 500 mAh g−1 capacity per cycle at −60 °C. The easy‐to‐decompose discharge products in small size on the cathode and the suppressed parasitic reactions both in the electrolyte and on the Li anode at low temperatures together contribute to the above high electrochemical performances.