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

Metal–CO₂ batteries have attracted much attention owing to their high energy density and use of greenhouse CO₂ waste as the energy source. However, the increasing cost of lithium and the low discharge potential of Na–CO₂ batteries create obstacles for practical applications of Li/Na–CO₂ 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–CO₂ battery with a carbon-based metal-free electrocatalyst. The battery shows a higher theoretical discharge potential (E^⊖=2.48 V) than that of Na–CO₂ 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 P12₁/c1-type K₂CO₃ at the efficient carbon-based catalyst. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.