High‐Performance K–CO₂ Batteries Based on Metal‐Free Carbon Electrocatalysts

Metal–CO 2 batteries have attracted much attention owing to their high energy density and use of greenhouse CO 2 waste as the energy source. However, the increasing cost of lithium and the low discharge potential of Na–CO 2 batteries create obstacles for practical applications of Li/Na–CO 2 batteries. Recently, earth‐abundant potassium ions have attracted considerable interest as fast ionic charge carriers for electrochemical energy storage. Herein, we report the first K–CO 2 battery with a carbon‐based metal‐free electrocatalyst. The battery shows a higher theoretical discharge potential ( E ⊖ =2.48 V) than that of Na–CO 2 batteries ( E ⊖ =2.35 V) and can operate for more than 250 cycles (1500 h) with a cutoff capacity of 300 mA h g −1 . Combined DFT calculations and experimental observations revealed a reaction mechanism involving the reversible formation and decomposition of P 12 1 / c 1‐type K 2 CO 3 at the efficient carbon‐based catalyst.