Asymmetric Structure-Induced d-Orbital Splitting Boosts Highly Active and Stable Li-CO2 Batteries.

Abstract

Lithium-carbon dioxide (Li-CO2) batteries provide an extremely feasible strategy for sustainable development and carbon neutrality. However, due to the sluggish kinetics and complex interfacial reactions, Li-CO2 batteries are limited by low output voltage and poor cycling stability. Developing efficient and durable catalysts remains an urgent challenge. Transition metal oxides have gained significant attention owing to their availability and stability for electrocatalytic reactions, but their catalytic activity remains unsatisfactory toward Li-CO2 batteries. Herein, this work proposes an asymmetric Fe/Cu-incorporated Co3O4 tactic system to tune charge distribution for motivating efficient electrocatalysis and decipher the mechanism of asymmetric structure modulation on the promotion of catalytic activity and stability. It is unraveled that d-orbital spin splitting induces the modification of nondegenerate state, which enhances catalyst durability, while simultaneously increasing electron occupancy in dxz / yz orbitals. This higher electron occupancy facilitates the hybridization with the p orbitals of reactants and intermediates via π bonding, thereby strengthening the adsorption activity. In consequence, the Li-CO2 battery with Cu-Co3O4 cathode demonstrates a low overpotential of 0.73 V and high Coulombic efficiency of 96%, outperforming batteries with Co3O4 and Fe-Co3O4. This work offers a unique insight for electronic structure regulation strategy and displays a high-performance catalyst for Li-CO2 batteries.