Oxygen‐Vacancy Engineering of Na4Fe3(PO4)2P2O7 Enables Fast and Wide‐Temperature Sodium Storage
The polyanionic cathode Na4Fe3(PO4)2P2O7 (NFPP) is regarded as a promising cathode for sodium‐ion batteries owing to its low cost, intrinsic safety, and robust framework stability. However, the strongly localized electronic structure and sluggish Na+ transport kinetics impose coupled limitations on its rate capability...