Interfacial Degradation and Optimization of Li-rich Cathode Materials^†

High-energy and safe lithium ion batteries (LIBs) are in increasing need as the rapid development of electronic devices, electric vehicles, as well as energy storage station. Li-rich oxides have attracted a lot of attention due to their high capacity and low cost as cathode material for LIBs. However, they still suffer from the vulnerable cathode/ electrolyte interface, which presents the huge challenges of surface degradation and gas release, particularly at high state of charge. Some issues of Li-rich cathode materials, such as moderate cycle stability and voltage decay, are in tight connection with electrode-electrolyte interfacial side reactions. Research in the area of interfacial degradation mechanism and optimization strategies is of great significance as for Li-rich cathode, and extensive efforts have been poured. This review aims to understand the degradation mechanism of Li-rich cathode materials, and summarize the corresponding valuable and effective optimization strategies. Based on these considerations, we also have discussed the remaining challenges and the future research direction.