Na2FePO4F Fluorophosphate as Positive Insertion Material for Aqueous Sodium‐Ion Batteries

Abstract Exploring stable and economic cathodes for aqueous sodium‐ion batteries, we have investigated iron‐based fluorophosphate (Na 2 FePO 4 F) as a compound for applications in aqueous battery systems. Solution combustion synthesized Na 2 FePO 4 F is found to act as an efficient cathode for aqueous Na‐ion batteries delivering a reversible capacity over 85 mAh g −1 (at a rate of 1 mA cm −2 ) with excellent rate kinetics. Further, this layered Na 2 FePO 4 F has been successfully implemented to design a full aqueous cell with NASICON‐type NaTi 2 (PO 4 ) 3 as anode, delivering a reversible capacity of 90 mAh g −1 . In conclusion, Na 2 FePO 4 F is proposed as a potential cathode material for aqueous Na‐ion batteries.