Surface and Subsurface Reactions of Lithium Transition Metal Oxide Cathode Materials: An Overview of the Fundamental Origins and Remedying Approaches

Abstract Lithium‐ion batteries (LIBs) have become one of the most prevailing techniques for rechargeable batteries. Lithium transition metal oxides are prevalent cathode materials currently, but they face great challenges due to unsatisfactory energy density, chemical/electrochemical instability, and elemental scarcity concerns. Surface/subsurface is the interface where lithium ions cross between the electrolyte and the cathode materials. Its properties and complicated nature are unambiguously regarded as a crucial controlling factor for the overall performance. Tremendous efforts have been made in the exploration of surface modification methods with remarkable progress hitherto. The purpose of this work is to review these surface behaviors in order to understand their fundamental origins and provide a summary of various surface modification methods that can be used to address impeding issues. Finally, a rational method of surface modification is proposed for use in cathode materials.