Interfacial failure mechanisms and surface engineering of Ni-based layered cathodes for high-performance and high-safety Li/Na-ion batteries

Nickel-based layered oxides (NLOs) are regarded as promising cathode materials for high-performance Li-ion and Na-ion batteries owing to their high theoretical capacity, efficient two-dimensional ion diffusion pathways, and manufacturing scalability. However, their application is impeded by severe surface and interfacial instabilities, especially under high voltages and high temperature conditions. The next-generation NLOs cathode demands high energy density, fast rate capability, and extended cycling life, which necessitates a surface architecture possessing robust chemical, mechanical, and electrochemical integrity. This review provides a comprehensive analysis of interfacial degradation mechanisms by categorizing three distinct types of interfaces: the cathode–air interface, the cathode–electrolyte interface, and intra/intergranular interfaces. We summarize recent surface engineering strategies to mitigate these challenges, including surface coatings, gradient near-surface structural design, controlled surface reconstruction, and electrolyte regulation. Forward-looking perspectives are provided to highlight the critical multifunctional interfaces, cost-effective processing, and precise regulation of the cathode–electrolyte interphase.