Topological Defect‐Rich Carbon as a Metal‐Free Cathode Catalyst for High‐Performance Li‐CO₂ Batteries

Abstract Exploration of the highly efficient bi‐functional catalysts toward the reduction of CO₂ and decomposition of Li₂CO₃ at the cathode is the key for high‐performance Li‐CO₂ batteries. Herein, topological defect‐rich graphene (TDG) based materials are developed as metal‐free cathodes for Li‐CO₂ batteries, presenting an unprecedented full discharge capacity of over 69 000 mA h g⁻¹ at the current density of 0.5 A g⁻¹, a relatively small voltage gap of 1.87 V (Li/Li⁺) even at an extremely high current density of 2.0 A g⁻¹, and an excellent long‐term stable cycle life of up to 600 cycles at 1.0 A g⁻¹. The outstanding performance of Li‐CO₂ batteries with the TDG cathodic electrocatalyst can be attributed to the introduction of topological defects in the carbon skeleton, providing sufficient active sites for CO₂ reduction and evolution to facilitate the formation/decomposition of Li₂CO₃ during the discharging/charging process. The density functional theory calculations reveal the superiority of the negatively charged C atoms in topological defects as the adsorption for CO₂ molecules and the activation sites for the decomposition of Li₂CO₃, and that the heterocyclic pentagon ring (C5) has a relatively low theoretical potential gap (1.01 V) during the charge and discharge processes.