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

Li-CO 2 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 2 and the Li 2 CO 3 product leads to a low operating voltage (<2.5 V) and poor energy efficiency. In addition, the reversibility of Li 2 CO 3 has always been questioned owing to the introduction of more decomposition paths caused by its higher charging plateau. Here, a novel "trinity" Li-CO 2 battery system was developed by synergizing CO 2 , soluble redox mediator (2,2,6,6-tetramethylpiperidoxyl, as TEM RM), and reduced graphene oxide electrode to enable selective conversion of CO 2 to Li 2 C 2 O 4 . The designed Li-CO 2 battery exhibited an output plateau reaching up to 2.97 V, higher than the equilibrium potential of 2.80 V for Li 2 CO 3 , and an ultrahigh round-trip efficiency of 97.1 %. The superior performance of Li-CO 2 batteries is attributed to the TEM RM-mediated preferential growth mechanism of Li 2 C 2 O 4 , which enhances the reaction kinetics and rechargeability. Such a unique design enables batteries to cope with sudden CO 2 -deficient environments, which provides an avenue for the rationally design of CO 2 conversion reactions and a feasible guide for next-generation Li-CO 2 batteries.