Oxygen Vacancy-Rich Ce-Doped NiO Nanorods as Cathode Catalysts for Oxygen Evolution and Lithium–Oxygen Batteries

Lithium–oxygen batteries (LOBs) with a high theoretical energy density have attracted widespread attention. The large overpotential and poor cycle stability caused by inactive redox reactions are severe challenges for LOBs. NiO is a classic OER electrocatalyst, but its insufficient active sites lead to poor actual performance. Rare earth (RE) elements are regarded as crucial promoters for regulating electrocatalysis due to their unique orbital characteristics. Here, a flower-like Ce-doped NiO (Ce-NiO) nanorod catalyst is constructed to explore the influence of cerium doping on the structure of pure NiO and its application in LOBs. Ce-NiO undergoes significant structural changes, including an increased specific surface area and a more abundant distribution of surface defects. The doping process introduces a large number of oxygen vacancies, which improve the oxygen absorption capacity and reduce the charge transfer impedance. These modifications could effectively enhance the electrochemical performance and improve the OER kinetics. In the application of LOBs, Ce-NiO-based batteries achieve excellent rate performance and a high discharge capacity of 19787 mAh g^–1 at a current density of 200 mA g^–1. In addition, they could stably cycle more than 255 times at a current density of 200 mA g^–1 and a cutoff capacity of 1000 mAh g^–1. Notably the initial overpotential in the first cycle is as low as 0.62 V.