A Comprehensive Review of Na4Fe3(PO4)2P2O7 Cathode Materials for Sodium-Ion Batteries: From Crystal Structure and Phase Purification to Modification Strategies Progress
Na4Fe3(PO4)2P2O7 (NFPP), an iron-based mixed phosphate–pyrophosphate cathode material, has emerged as one of the most commercially promising candidates for large-scale sodium-ion battery (SIB) energy storage applications. Its exceptional characteristics—an ultralow volume change of less than 4% during Na+ de/intercalat...