Challenges and strategies for enhancing surface stability of high-nickel layered oxide cathodes for lithium-ion...

The growing demand for electric vehicles and grid storage has driven the need for high-energy-density lithium-ion batteries. High-nickel layered oxide cathodes offer high theoretical specific capacity and energy density. However, their practical application is critically hindered by severe surface and interfacial side reactions, primarily associated with the enrichment of highly oxidizing Ni species. The elevated nickel content renders the cathode surface highly reactive, promoting oxygen release and surface reconstruction, which ultimately lead to rapid capacity fading and poor cycling stability. In this review, we focus on nanoscale surface structure regulation strategies aimed at enhancing the surface stability of high-nickel cathodes. We first analyze the primary mechanisms underlying surface degradation, which proceeds progressively from surface instability to coupled bulk mechanical failure. Then, we summarize recent advances in surface engineering strategies, which have evolved from conventional surface coatings toward more sophisticated multifunctional and multiscale designs. Finally, we provide perspectives on future directions for developing robust and viable stabilization approaches. We emphasize the necessity of hierarchical interface regulation from the nanoscale to the macroscale to address these intricately coupled degradation pathways.