Construction of an Oxygen-Vacancy-Rich CeO2@CoO Heterojunction toward High-Performance Lithium–Oxygen Batteries

Lithium-oxygen (Li-O2) batteries theoretically possess an exceptional energy density comparable to gasoline (up to 3500 W h kg-1), but in practical applications, the discharge products are difficult to effectively decompose, which leads to clogging of the cathode, resulting in severe polarization, limited actual capacity, and shortened battery life for Li-O2 batteries. Herein, we construct a highly active and stable catalyst with d-f electronic orbit coupling as a redox center by anchoring CeO2 onto CoO, simultaneously, oxygen vacancy (Ov) and CeO2 coactivated CoO. By leveraging the effects of interface engineering and defect engineering on the electronic structure of the catalyst, the adsorption energy for LiO2 can be adjusted to an ideal range. This not only avoids surface passivation caused by excessively strong binding energy but also overcomes the issue of sluggish Li2O2 decomposition efficiency due to excessively weak binding energy. Bracingly, the CeO2/CoO-based Li-O2 batteries exhibit an ultralow charge-discharge polarization, and Li2O2 was successfully induced to nucleate uniformly in nanoflower-like shapes, which could promote the reversible decomposition of the discharge products during the charging process and thereby enhance the electrochemical performance of Li-O2 batteries. Therefore, the CeO2@CoO/CC cathode exhibited an ultralow overpotential of 0.57 V and achieved a high discharge capacity of 19,850 mA h g-1. This work provides an important reference for designing the structure of cathode catalysts for Li-O2 batteries and regulating the growth paths and morphologies of discharge products.