Boosted Mg−CO 2 Batteries by Amine‐Mediated CO 2 Capture Chemistry and Mg 2+ ‐Conducting Solid‐electrolyte Interphases

Mg−CO 2 battery has been considered as an ideal system for energy conversion and CO 2 fixation. However, its practical application is significantly limited by the poor reversibility and sluggish kinetics of CO 2 cathode and Mg anode. Here, a new amine mediated chemistry strategy is proposed to realize a highly reversible and high‐rate Mg−CO 2 battery in conventional electrolyte. Judiciously combined experimental characterization and theoretical computation unveiled that the introduced amine could simultaneously modify the reactant state of CO 2 and Mg 2+ to accelerate CO 2 cathodic reactions on the thermodynamic‐kinetic levels and facilitate the formation of Mg 2+ ‐conductive solid‐electrolyte interphase (SEI) to enable highly reversible Mg anode. As a result, the Mg−CO 2 battery exhibits boosted stable cyclability (70 cycles, more than 400 h at 200 mA g −1 ) and high‐rate capability (from 100 to 2000 mA g −1 with 1.5 V overpotential) even at −15 °C. This work opens a newly promising avenue for advanced metal‐CO 2 batteries.