Na ₄ Fe ₃ (PO ₄ ) ₂ (P ₂ O ₇ ) cathode for sodium-ion batteries: from crystal structure to high-energy-density design and solid-state battery application prospects

), a promising candidate with improved application potential, and discusses the issues arising from the incorporation of Mn, along with proposed solutions. Furthermore, we include a detailed discussion on the prospective applications of NFPP-based cathode materials within the realm of solid-state batteries. Finally, the relationship between NFPP modification research and the practical applications of sodium-ion batteries is emphasized, and potential future research directions for pyrophosphate-based cathode materials in the large-scale deployment of sodium-ion batteries are proposed.