Enhanced electrochemical properties of W-doped Na3V2(PO4)2F3@C as cathode material in sodium ion batteries

Sodium super ion conductors (NASICON) based structures are being explored as cathode materials for application in sodium ion battery technology. Na3V2(PO4)2F3 has been established as an important candidate in this category but suffers from low electronic conductivity. In this work, the effect of the substitution of Tungsten (W) in place of Vanadium on the electrochemical performance of Na3V2(PO4)2F3@C in sodium ion battery (SIB) has been elucidated in detail. The crucial role played by the synthesis method and the product morphology on the electrochemical property of the cathode material has been highlighted. The Na3V1.96W0.04(PO4)2F3@C cathode synthesized using sonochemically assisted sol gel followed by ball milling method exhibits improved structural integrity and enhanced Na-ion mobility. The cathode delivers a high reversible capacity of 153 mAh g−1 at 0.1C. Theoretical studies indicate that incorporation of W reduces the band gap and improves the interfacial resistance of Na3V2(PO4)2F3@C.