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

Abstract Rechargeable lithium‐carbon dioxide (Li‐CO 2 ) batteries present a compelling strategy for carbon capture and utilization techniques. Nevertheless, the formation of Li 2 CO 3 as the main discharge product in the 4e − /3CO 2 electrochemistry of Li‐CO 2 batteries necessitates an elevated applied voltage to achieve full decomposition, which leads to severe performance issues in Li‐CO 2 batteries. In this work, a stable lithium oxalate (Li 2 C 2 O 4 ) electrochemistry involving a 2e − /2CO 2 process triggered by Mo 2 N@Ti 3 C 2 O 2 electrocatalyst is proposed, which facilitates highly reversible redox reactions in Li‐CO 2 batteries. The presence of enriched ‐O terminations at the interface between Mo 2 N and Ti 3 C 2 O 2 strengthens charge redistribution of Mo 3d orbital electron and enhances the coupling between Mo 3d orbitals and O 2p orbitals in Li 2 C 2 O 4 . The adsorption energy of Li 2 C 2 O 4 on Mo 2 N@Ti 3 C 2 O 2 surface and energy barrier for self‐disproportionation reaction of Li 2 C 2 O 4 are further increased, enabling the stable Li 2 C 2 O 4 electrochemistry. Therefore, the Mo 2 N@Ti 3 C 2 O 2 based Li‐CO 2 battery can produce Li 2 C 2 O 4 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 Li 2 C 2 O 4 electrochemistry, Li‐CO 2 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).