Research Progress on NASICON-Type Cathode Materials for Sodium Ion Batteries

With the rapid development of secondary battery technology, lithium ion batteries (LIBs) have become an important energy storage device today. However, lithium resources in the earth's crust are limited and lithium-based compounds are expensive. Hence, researchers are looking for the alternatives of LIBs. Not only sodium-ion batteries (SIBs) works at a similar mechanism as LIBs, but also sodium is more abundant and more homogeneous on the earth, and its price is lower, making SIBs are one most promising secondary battery system to replace LIBs. Unfortunately, the shortcomings including the larger Na+ radius and the higher irreversibility of electrode reactions lead to a very large difficulty to achieve high-performance SIBs. Therefore, it is still a big challenge to develop advanced electrode materials for SIBs. Amongst all types of cathode materials, Na superionic conductor (NASICON) type materials are one class of compounds with ultrafast Na+ transformation and high structural stability during the successive de-sodiation/sodiation processes, suggesting its obvious application possibility for actual SIBs. In this review, we firstly introduced the crystal structure of NASICON materials, and then summarized the research progresses on the NASICON-type cathode for SIBs from the point of view of types and numbers of transition metal and the introduction of anions, and further analyzed the main problems and challenges of NASICON-type materials.