Ultrahigh‐Voltage Li‐CO ₂ Batteries Enabled by the Incorporation of Mn(II) Soluble Catalyst and Crown Ether Electrolyte

Abstract The CO 2 reduction reaction (CO 2 RR) in Li‐CO 2 batteries involves solid, liquid, and gas phases, so the sluggish kinetic is one of the main bottlenecks faced by current research in Li‐CO 2 batteries. Here, a Mn(II) redox mediator (Mn(II)RM) molecule, is introduced as a soluble catalyst to optimize the reaction pathway of CO 2 RR. Mn(II)RM captures CO 2 molecule and promotes their intramolecular charge transfer, the soluble CO 2 first participates in the binding process with Mn(II)RM to generate a stable intermediate product. Subsequently, this intermediate product gains electrons on the solid electrode, during this electrochemical reduction process, the final discharge product Li 2 CO 3 is formed. Furthermore, 15‐crown‐5 ether (15C5) is adopted as solvent to regulate the capture process of Mn(II)RM with CO 2 , benefit from the incorporation of CO 2 capture capability in Mn(II)RM and strong affinity to Li + in 15‐crown‐5 ether, Li‐CO 2 batteries using this Mn(II)RM‐15C5 electrolyte exhibit a high discharge voltage up to 3.2 V, an enlarged discharge capacity of 9023 mAh g −1 , and a stable cyclability over 130 cycles. This work inspires a novel approach for electrolyte design to regulate the Li 2 CO 3 growth and decomposition pathway in Li‐CO 2 batteries.