Liquid Metal–CO2 Battery Bridged Intermittent Energy Conversion and O2 Production in the Martian Atmosphere

Oxygen and fuels are requisites for outer space exploration. Herein, we use a liquid Na–Sn cathode and a Ni-based inert anode to convert CO2 into Na–Sn and oxygen in molten Na2CO3–NaCl by electrolysis, aiming to produce oxygen and store solar energy in liquid Na–Sn when the sun shines. In the same Na2CO3–NaCl electrolyte, the liquid Na–Sn serves as a negative electrode coupled with a porous FeNi positive electrode that allows the reduction of CO2 to CO in a primary cell, converting chemical energy stored in Na–Sn into electricity and CO that is a valuable fuel when the sun does not shine. This system has an overall energy efficiency of 51.0% at 100 mA cm–2. Therefore, the molten carbonate electrolysis device equipped with a liquid metal electrode could be applied for producing O2 and storing solar energy in energetic chemicals (e.g., Na–Sn, CO), which could be applied for outer space exploration such as Mars.