High‐Performance Li‐CO2 Batteries Based on Metal‐Free Carbon Quantum Dot/Holey Graphene Composite Catalysts

Abstract

AbstractLi‐CO2 batteries have attracted ever increasing attention due to their high energy and power densities. However, Li2CO3 formed during the discharge process is difficult to decompose, leading to a large charge overpotential and poor cyclability. Thus, high‐performance and low‐cost catalysts that can be integrated into the electrode architecture are urgently needed for the development of practical Li‐CO2 batteries with a low overpotential and long cyclability. Herein, a high‐performance composite catalyst is reported based on carbon quantum dots supported by holey graphene (CQD/hG), which, when used as the cathodic catalyst in a Li‐CO2 battery, can support the fast formation and decomposition of Li2CO3 in organic electrolytes and achieve an overpotential as low as 1.02 V (Li/Li+) at current density of 0.1 A g−1. The discharge capacity of this Li‐CO2 battery is 12300 mAh g−1 under the current density of 0.5 A g−1, showing an excellent long‐term stability with up to 235 cycles even at a high current density of 1 A g−1. The observed superb battery performance is attributable to synergistic effects that the CQD/hG composite architecture provides a high catalytic activity of the defect‐rich CQDs and fast electron/electrolyte transport through the conducting holey graphene sheets.