Construction and Regulation of Defect Electrocatalysts for Rechargeable Li-O₂ Batteries

Li-O₂ batteries (LOBs) have garnered significant interest due to their extraordinarily high theoretical energy density. Nonetheless, their development is severely constrained by sluggish kinetics at the cathodic three-phase interfaces. Addressing these limitations hinges on the rational design of electrocatalysts capable of efficiently promoting both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Central to catalytic performance is the precise modulation of electronic structure, particularly the creation of nonuniform surface charge distributions to expose highly active sites and optimize the adsorption energy of key intermediates. Among various strategies, defect engineering has emerged as a powerful approach for tailoring surface electronic properties. This review systematically summarizes recent advances in defect-engineered cathode materials for nonaqueous LOBs. The characteristic defect types and their influences on oxygen electrocatalysis are analyzed, followed by an in-depth discussion of the fundamental roles of defects in electronic structure modulation, interfacial synergistic catalysis, and catalyst stability. By correlating defect configurations with electrochemical performance, this review aims to establish clear structure-activity-performance relationships for rational catalyst design. Finally, future opportunities involving promising catalyst systems, advanced defect design strategies, integrated catalytic systems, and remaining challenges for defect electrocatalysts are outlined to promote the practical implementation of LOB technologies.