Advances and Prospects of Surface Modification on Nickel-Rich Materials for Lithium-Ion Batteries^†

Although layered Ni-rich cathode materials have attracted lots of attention for their high capacity and power density, several significant issues, such as poor thermal stability and moderate cyclability, limit their practical applications. Most of these undesired problems of Ni-rich materials are caused by the unstable surface or the parasitic reactions at cathode-electrolyte interface. Surface coating is the most common method to suppress such interfacial problems for Ni-rich materials. This review focuses on the surface engineering of the Ni-rich materials in recent years, including the species used in coating, synthetic strategies of uniform coating layer, and the positive effects of coating species on the active materials. Detailed discussions are also taken to describe the formation mechanism of the surface coating layer with design philosophy. Finally, the prospects for further developments and challenges in surface coating are also summarized.