Stable 2e−/2CO2 Electrochemistry Triggered by Enriched Interfacial Oxygen Mo2N@Ti3C2O2 Elcetrocatalyst for High Rates and High Energy Efficiency Li‐CO2 Batteries

Abstract

AbstractRechargeable lithium‐carbon dioxide (Li‐CO2) batteries present a compelling strategy for carbon capture and utilization techniques. Nevertheless, the formation of Li2CO3 as the main discharge product in the 4e−/3CO2 electrochemistry of Li‐CO2 batteries necessitates an elevated applied voltage to achieve full decomposition, which leads to severe performance issues in Li‐CO2 batteries. In this work, a stable lithium oxalate (Li2C2O4) electrochemistry involving a 2e−/2CO2 process triggered by Mo2N@Ti3C2O2 electrocatalyst is proposed, which facilitates highly reversible redox reactions in Li‐CO2 batteries. The presence of enriched ‐O terminations at the interface between Mo2N and Ti3C2O2 strengthens charge redistribution of Mo 3d orbital electron and enhances the coupling between Mo 3d orbitals and O 2p orbitals in Li2C2O4. The adsorption energy of Li2C2O4 on Mo2N@Ti3C2O2 surface and energy barrier for self‐disproportionation reaction of Li2C2O4 are further increased, enabling the stable Li2C2O4 electrochemistry. Therefore, the Mo2N@Ti3C2O2 based Li‐CO2 battery can produce Li2C2O4 discharge products even at a high discharge rate of 500 mA g−1 (ten times to previous studies) and during deep cycling processes. Due to the stable Li2C2O4 electrochemistry, Li‐CO2 batteries exhibit excellent electrochemical performance, including ultra‐low overpotential (0.55 V), ultra‐high energy efficiency (82.9%), and excellent cycling stability electrode (800 h).