Copper Indium Sulfide Enables Li‐CO 2 Batteries with Boosted Reaction Kinetics and Cycling Stability

High energy density Li‐CO 2 batteries have attracted much attention owing to the “two birds with one stone” feature in fixing greenhouse gas CO 2 and providing renewable energy. However, poor reversibility of the discharge product Li 2 CO 3 is one of the main problems that limit its application, resulting in poor cycling stability and severe polarization. Herein, copper indium sulfide (CIS), a semiconducting non‐precious metal sulfide, is fabricated as cathode catalysts for high‐performance Li‐CO 2 batteries. Combined with the synergistic effect of bimetallic valence bonding and coordinated electron transfer, Li‐CO 2 batteries using CIS cathodes exhibit high full specific discharge capacity, excellent rate capability and cycle stability, namely it delivers a high specific full discharge capacity of 8878 μAh cm −2 , runs steadily from 10 to 100 μA cm −2 , and performs a stable long‐term cycling behavior (>1050 h) under a high energy efficiency of 84% and a low charge voltage of approximately 3.4 V at 20 μA cm −2 within 100 μAh cm −2 . In addition, a flexible Li‐CO 2 pouch cell is constructed to reveal the potential of employing CIS to fabricate flexible high energy storage devices in practical applications. This work shows a promising development pathway toward next‐generation sustainable energy storage devices.