Stabilization of High-Energy Cathode Materials of Metal-Ion Batteries: Control Strategies and Synthesis Protocols

Metal-ion batteries, especially lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), and potassium-ion batteries (PIBs), have emerged as promising electronic devices for energy conversion and storage. To satisfy the upsurging demand for high energy density, cathode materials as the determining component in the battery system are driven to deliver higher capacities by either extracting more active metal ions (Li+, Na+, and K+) or increasing the operating voltage. However, serious side reactions of cathodes will occur, leading to severe capacity fading and safety risk. Surface coating has been confirmed as an effective strategy to stabilize cathodes and has been widely applied in the fabrication of high-energy cathodes for different metal-ion battery systems. In this review, we will summarize the recent progress in surface coating of high-energy cathodes for LIBs, SIBs, and PIBs. We will mainly discuss the available synthetic strategy for precise surface coating as a result of its importance in achieving an optimized balance between surface protection and charge transfer. Thereby, the structure-performance relationship will be built to highlight the contribution from surface control. Finally, challenges and opportunities in the future development of surface coating for high-energy cathodes of rechargeable batteries are also discussed.