NaFePO4 for sodium-ion batteries: Mechanism, synthesis and optimization strategies toward commercialization

Sodium-ion batteries (SIBs) have been considered as a prospective energy storage solution in the near future due to the abundance and wide distribution of sodium resource on the earth. The exploration of high-performance cathode materials is the key to the practical application of advanced SIBs. Among various SIB cathode materials, NaFePO4 possesses the advantages of abundant reserve, low cost and safety, which make it an ideal positive electrode material for SIBs. This paper provides a comprehensive review on the research progress and future prospect of NaFePO4 positive electrode material. Firstly, different crystal structures and sodium storage mechanisms of NaFePO4 have been discussed. Then, the synthesis methods, morphologies, electrochemical properties, and optimization strategies to improve the electrochemical performance of NaFePO4 cathode materials in SIBs are summarized in details. Theoretical studies on the structure-performance relationship and the prediction of high-performance NaFePO4 have also been introduced. Finally, the current challenges, potential research directions and future prospects of NaFePO4 toward commercialization have been proposed. This review aims to provide insights into the rational design of high-performance NaFePO4 cathode materials and to accelerate the practical application of NaFePO4 in SIBs.