Exploring the synergistic effects of chemical activation and N-doping in carbon nanospheres for advanced Li–CO2Mars batteries

Lithium-CO2 batteries can be used to mitigate CO2 emissions by recycling CO2 for energy storage and potential utilization as a standalone energy storage device on Mars as it contains 95 % CO2 (Li-CO2Mars batteries). The incomplete decomposition of the discharge product, Li2CO3, reduces the battery's cycle life, limiting its practi-cability. Herein, we develop a hierarchical porous, high surface area (1845 m2 g-1) activated N-doped candle soot (ANCS) carbon catalyst by modifying the candle soot carbon through the combination of the techniques of activation and hereroatom N-doping for enhanced CO2 reduction and evolution reactions. The ANCS-based Li-CO2Mars batteries exhibit a high discharge capacity of 11,490 mAh g-1 and a stable cycle life of over 130 cycles with a low overpotential of 1.4 V at the high current density of 200 mA g-1. Furthermore, density functional theory (DFT) studies reveal that the ANCS catalyst's higher affinity for CO2 adsorption and Li2CO3 production leads to the excellent performance of the Li-CO2Mars batteries. The developed method offers way of repurposing the pollutant carbons as metal-free carbon catalysts for the future progress of the Li-CO2Mars bat-teries for use as a future sustainable energy source for both Earth and Mars.