Heteroepitaxial interface of layered cathode materials for lithium ion batteries

Abstract Electrochemical energy storage systems with high energy/power density are a key technology for the development of intelligent society, especially for portable electronics devices and electric vehicles. The most effective strategy to enhance the energy/power density of batteries is to explore for high-capacity electrode materials. Layered cathode materials with high specific capacity and high operating voltage have attracted great research interests. However, severe surface structural degradation, irreversible oxygen release and interfacial side-reactions occurring in the cycles of layered materials at high voltage, cause undesirable capacity and voltage deterioration, blocking their further development. Interface engineering, in particular constructing stable heteroepitaxial interfaces on layered cathode materials, has been recognized as an effective strategy to solve these abovementioned problems comprehensively. Here, the development history and structural characteristics of layered cathode materials are reviewed, different types of heteroepitaxial interfaces and their construction methods are discussed in detail. Particularly, the mechanism and function of constructing heteroepitaxial interface in layered materials are emphasized. However, some essential issues still remain controversial, especially with regard to understanding of the surface structure and chemistry properties related to the material composition and synthesis process, and charge transfer and ionic transport of the interfacial processes of layered cathodes. A clear understanding of these fundamental mechanisms is therefore essential to optimize the synthesis process and electrochemical performance of layered cathodes.