Reversible Carbon Dioxide/Lithium Oxalate Regulation toward Advanced Aprotic Lithium Carbon Dioxide Battery.

Li-CO batteries have received significant attention owing to their advantages of combining greenhouse gas utilization and energy storage. However, the high kinetic barrier between gaseous CO and the LiCO product leads to a low operating voltage (<2.5 V) and poor energy efficiency. In addition, the reversibility of LiCO has always been questioned owing to the introduction of more decomposition paths caused by its higher charging plateau. Here, a novel "trinity" Li-CO battery system was developed by synergizing CO, soluble redox mediator (2,2,6,6-tetramethylpiperidoxyl, as TEM RM), and reduced graphene oxide electrode to enable selective conversion of CO to LiCO. The designed Li-CO battery exhibited an output plateau reaching up to 2.97 V, higher than the equilibrium potential of 2.80 V for LiCO, and an ultrahigh round-trip efficiency of 97.1 %. The superior performance of Li-CO batteries is attributed to the TEM RM-mediated preferential growth mechanism of LiCO, which enhances the reaction kinetics and rechargeability. Such a unique design enables batteries to cope with sudden CO-deficient environments, which provides an avenue for the rationally design of CO conversion reactions and a feasible guide for next-generation Li-CO batteries.