Recently, Huisheng Peng and Bingjie Wang and others from Fudan University designed a new electrolyte system,which used metallic lithium as the negative electrode, 1,3-dioxolane (DOL) as the electrolyte solvent, and lithium bistrifluoromethanesulfonimide (LiTFSI) as the electrolyte lithium salt. Based on this electrolyte system, an iridium-based positive electrode was used to achieve high-efficiency operation of lithium-carbon dioxide (Li-CO2) batteries in ultra-low temperature environments.

Li-CO2 batteries are an attractive energy storage system. Unlike the conditions that most lithium-air batteries need to operate in high-purity oxygen, Li-CO2 batteries use the greenhouse gas carbon dioxide as the reaction gas to participate in the redox reaction and have energy, this makes the Li-CO2 batteries have dual role of transformation and environmental friendliness.

The energy density of Li-CO2 batteries is more than seven times that of ordinary lithium-ion batteries, and it can work in extreme environments such as high carbon dioxide concentration.

So the researchers envisage that if Li-CO2 batteries can overcome the low temperature environment below -60 ℃, it may work on Mars with a carbon dioxide concentration of up to 96%. So, the researchers designed this new electrolyte system.

The electrolyte system has ultra-low freezing point, high ionic conductivity and excellent low-temperature electrochemical stability, coupled with the advantages of iridium-based positive electrode for CO2 reduction reaction and CO2 precipitation reaction and other advantages, so that Li-CO2 batteries work efficiently in ultra-low temperature environment.

After testing, Li-CO2 batteries based on the new electrolyte system have excellent electrochemical performance and excellent stability. Under the ultra-low temperature environment of -60 ℃, the deep discharge capacity is as high as 8976mAh / g when the weekly capacity is 500mAh / g at a current density of 100mA / g and the cycle can be stable for more than 150 weeks, and the corresponding working time is 1500 hours. Those provides the possibility to work on Mars.

References: Jiaxin Li et al, Li-CO2 Batteries Efficiently Working at Ultra‐Low Temperatures, Advanced Functional Materials, 2020 DOI: 10.1002 / adfm.202001619