The development of metal-CO2 batteries is a promising technology due to their high energy density and, more importantly, their ability to utilize the greenhouse gas carbon dioxide (CO2) as an energy carrier and, therefore, to combat the climate change effects. Furthermore, the metal-CO2 battery can offer great benefits in terms of energy storage and in-situ resource utilization for the interplanetary Mars mission, reducing overall mission cost, weight, and complexity. This work is a novel attempt to realize the feasible development of a metal-CO2Mars battery for Mars exploration. To the best of our knowledge, we hereby report the practical configuration of metal (X)-CO2Mars batteries (X = Li, Na and K) which is operated in a simulated Martian atmosphere for the first time. To develop a better fundamental understanding, we investigate the effective reversibility and discharge-reaction product formation of these metal-CO2Mars batteries. Further, the electrochemical performance and underlying mechanism of metal-CO2Mars batteries are evaluated using electrochemical testing (galvanic discharge-charge, cyclic voltammetry), potentiodynamic polarization, and Raman spectroscopy analysis, which are then later supported by first-principle calculation based on density functional theory. Thus, we believe that this work provide a rational design strategy for the practical development of metal-CO2Mars and metal-CO2 batteries.