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

Abstract

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.