The core-shell metal–organic framework-derived composite Fe₃O₄/Co₃O₄ heterojunction catalyst embedded in electrospun N-doped carbon nanofibers for Li-CO_2Mars batteries provides enhanced CO₂ adsorption, high full discharge capacity, and improved cycle life. The developed system scaled to a pouch-cell type battery offers practical solutions for Earth and Mars.

Li-CO₂ batteries offer a revolutionary energy storage solution, combining high specific energy with the utilization of greenhouse CO₂. Although promising for applications on Earth and Mars, the limited cycle life and significant overpotentials from stable discharge products, Li₂CO₃ and amorphous carbon, hinder the practicalization of Li-CO₂ batteries. To address these, a unique freestanding core-shell metal–organic framework-derived heterojunction catalyst, Fe₃O₄/Co₃O₄, embedded in electrospun nitrogen-doped carbon nanofibers for the Li-CO_2Mars batteries, is designed. It eliminates the need for insulating binders, toxic solvents and ensures uniformly distributed composite catalysts across the nanofibers. The electrochemical performance of Fe₃O₄/Co₃O₄/N-doped carbon fiber (FCo/NCF)-based Li-CO_2Mars coin cells operated in the simulated Mars’ atmosphere achieves a cycling life of 120 cycles at a current density of 50 μA cm^{− 2}, with a limited discharge/charge capacity of 0.1 mAh cm^{− 2}, and delivers a full discharge capacity of 6.8 mAh cm^{− 2} outperforming the conventional catalysts. In situ and first-principle studies demonstrate that enhanced CO₂ adsorption and improved reversibility, driven by the bifunctional catalytic activity of FCo/NCF, lead to exceptional electrochemical performance of Li-CO_2Mars batteries. A prototype of Li-CO_2Mars pouch cell is also developed, operating with an average efficiency of ≈68%, advancing the scalable development of Li-CO_2Mars batteries for diverse applications.