Copper Indium Sulfide Enables Li-CO₂ Batteries with Boosted Reaction Kinetics and Cycling Stability

High energy density Li-CO₂ batteries have attracted much attention owing to the “two birds with one stone” feature in fixing greenhouse gas CO₂ and providing renewable energy. However, poor reversibility of the discharge product Li₂CO₃ 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-CO₂ batteries. Combined with the synergistic effect of bimetallic valence bonding and coordinated electron transfer, Li-CO₂ 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-CO₂ 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.