Composite NiCo2O4@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 NiCo2O4@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 Li2O2, while the introduction of CeO2 can increase oxygen vacancies and optimize the electronic structure of NiCo2O4, 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 NiCo2O4@CeO2 is clarified from the perspective of electronic structure and reaction kinetics. This work demonstrates the high efficiency of NiCo2O4@CeO2 as an electrocatalyst and confirms the contribution of the current design concept to the development of LOBs cathode materials.

Automated summary

A composite microsphere material composed of NiCo2O4@CeO2 is synthesized and used as an electrocatalyst for lithium-oxygen batteries (LOBs) to address the challenges of high overpotential and poor cycle stability. The unique microstructured catalyst provides sufficient catalytic surface for barrier-free oxygen and lithium ion transport. The introduction of CeO2 increases oxygen vacancies and optimizes the electronic structure of NiCo2O4, thereby enhancing electron transport in the electrode. The catalytic cathode material reduces overpotential to 1.07 V and exhibits stable cycling performance.