Research progress in sodium-iron-phosphate-based cathode materials for cost-effective sodium-ion batteries: Crystal structure, preparation, challenges, strategies, and developments

Abstract

Owing to their long cycle life, high energy density, and ecological friendliness, lithium-ion batteries (LIBs) have been widely used in portable electronic devices and electric vehicles over the past few decades. Nonetheless, the high cost and limited abundance of lithium pose significant obstacles to its widespread use. In response, sodium-ion batteries (SIBs) have gained significant attention owing to their abundant sodium resources, similar intercalation chemistry to that of lithium, and low cost. Cathode materials are key components of SIBs, as they significantly impact the electrochemical performance. Among the several cathode candidates, polyanion-type cathode materials are considered the most promising and attractive options for developing SIBs owing to their outstanding electrochemical performance. In this review, the crystal structure classification and synthesis methods of sodium iron phosphate (NaFePO₄) are comprehensively examined. The issues associated with NaFePO₄ cathode materials for emerging SIBs are also summarized. Furthermore, optimization strategies for enhancing electrochemical performance are discussed, including surface morphology modification, elemental ion substitution, nano-structure architecture, and the probing of innovative structures. Finally, recent research developments and perspectives on NaFePO₄ cathode materials are reviewed. This article provides valuable insights into the development of NaFePO₄ cathode materials for realizing high-performance SIBs for commercialization.