A Perspective on the Requirements of Ni‐rich Cathode Surface Modifications for Application in Lithium‐ion Batteries and All‐Solid‐State Lithium‐ion Batteries

The increasing adoption of Ni‐rich cathode active materials in commercial liquid electrolyte Lithium‐ion batteries (LIBs) is testament to the improvements in the cathode stability through various surface modification strategies. The development of a deeper understanding of the cathode/electrolyte interface in LIBs has resulted in coatings capable of mitigating both surface and bulk cathode degradation mechanisms. However, due to increasing demands for safe and high energy density cells, a large portion of the research has now shifted towards applying Ni‐rich cathode active materials in inherently safer all‐solid‐state Lithium‐ion batteries (ASSLBs), with the resulting cathode surface modification strategies evolving differently. In this regard, a review outlining the surface modification strategies of Ni‐rich cathode materials applied in both LIB and ASSLB systems is provided. Within, a review of the traditional, advanced and specialized surface modification strategies of each system is discussed, along with a final perspective on the likely future direction of research regarding the design of system‐specific Ni‐rich cathode‐based surface modification strategies. Ni‐rich layered cathode materials require different surface modification strategies depending on the electrolyte system. In liquid electrolyte‐based lithium‐ion batteries, ensuring chemical protection requires not only external but also internal surface modification. In all‐solid‐state lithium‐ion batteries, there is a demand for uniform external and internal surface coating to enhance ionic conductivity.