Composite NiCo₂ O₄ @CeO₂ Microsphere as Cathode Catalyst for High-Performance Lithium-Oxygen Battery

The large overpotential and poor cycle stability caused by inactive redox reactions are tough challenges for lithium-oxygen batteries (LOBs). Here, a composite microsphere material comprising NiCo₂ O₄ @CeO₂ is synthesized via a hydrothermal approach followed by an annealing processing, which is acted as a high performance electrocatalyst for LOBs. The unique microstructured catalyst can provide enough catalytic surface to facilitate the barrier-free transport of oxygen as well as lithium ions. In addition, the special microsphere and porous nanoneedles structure can effectively accelerate electrolyte penetration and the reversible formation and decomposition process of Li₂ O₂ , while the introduction of CeO₂ can increase oxygen vacancies and optimize the electronic structure of NiCo₂ O₄ , thereby enhancing the electron transport of the whole electrode. This kind of catalytic cathode material can effectively reduce the overpotential to only 1.07 V with remarkable cycling stability of 400 loops under 500 mA g^-1 . Based on the density functional theory calculations, the origin of the enhanced electrochemical performance of NiCo₂ O₄ @CeO₂ is clarified from the perspective of electronic structure and reaction kinetics. This work demonstrates the high efficiency of NiCo₂ O₄ @CeO₂ as an electrocatalyst and confirms the contribution of the current design concept to the development of LOBs cathode materials.