Progress of metal phosphides as the anode materials for sodium ion batteries

Metal phosphide has been recognized as a promising anode material for sodium-ion batteries due to its high theoretical specific capacity and suitable redox potential. However, the challenges such as poor electronic conductivity and large volume expansion of metal phosphide lead to poor cyclic stability of metal phosphide, which limits its practical application. In recent years, metal phosphide with various structure and composition designs have been developed to effectively improve their cyclic stability and reaction kinetics. This review provides a systematic summary of the recent research advancements in metal phosphide anode materials for sodium-ion batteries (SIBs), covering sodium-ion storage mechanisms, synthesis strategies, modification methods, and future challenges and opportunities for further development. The aim of this review is to promote the research on metal phosphide anode materials for expediting the development and application of sodium-ion batteries. In addition, the future development of MPs for SIB anodes is proposed.