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 CO 2 and decomposition of Li 2 CO 3 at the cathode is the key for high‐performance Li‐CO 2 batteries. Herein, topological defect‐rich graphene (TDG) based materials are developed as metal‐free cathodes for Li‐CO 2 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‐CO 2 batteries with the TDG cathodic electrocatalyst can be attributed to the introduction of topological defects in the carbon skeleton, providing sufficient active sites for CO 2 reduction and evolution to facilitate the formation/decomposition of Li 2 CO 3 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 CO 2 molecules and the activation sites for the decomposition of Li 2 CO 3 , and that the heterocyclic pentagon ring (C5) has a relatively low theoretical potential gap (1.01 V) during the charge and discharge processes.