Tuning CO₂ Electrocatalytic Reduction Path for High Performance of Li‐CO₂ Battery

Abstract

The production of Li2CO3/C through CO2 reduction reaction in nonaqueous systems is a complex four‐electron, multi‐step process, and the short existence time of intermediate monomers is not conducive to observation, which causes great difficulties in clarifying and regulating the CO2 reduction path. Herein, ferrocene (Fc) as a functional additive into the electrolyte can stabilize the discharge intermediates and favor the occurrence of the two‐electron reaction path during CO2RR, which leads to more stable operation of the Li‐CO2 battery; with the assistance of Fc, the CO2 reduction pathway in Li‐CO2 battery is also clarified. Theoretical calculation analysis combined with experimental characterization observation confirms that Fc can shorten the CO2 reduction distance through interaction with CO2 and affecting the solvent environment around Li+, stabilize intermediate products to clarify the discharge path. The existence time of intermediates and discharge depth of the battery are key factors affecting the CO2 reduction pathway. The Li2C2O4 formed by CO2 reduction through the 2‐electron pathway is more favorable for the reversible operation of the Li‐CO2 battery than Li2CO3/C through the 4‐electron pathway. This work provides inspiration for clarifying the reaction mechanism and regulating the CO2 reduction pathway to improve the electrochemical performance of Li‐CO2 battery in the future.