Manganese ion doping effect on NaFe2PO4(SO4)2 for high electrochemical performances as cathode material for battery application

Sodium-based polyanionic compounds are being widely explored as positive electrode materials for sodium-ion batteries due to the advantages of elevated operating voltage plateaus and exceptional cycling stability. This work investigates the charge/discharge characteristics of a newly developed NASICON-type polyanionic cathode, NaFe2PO4(SO4)2 (NFPS), through X-ray diffraction refinement and cyclic voltammetry. Subsequently, the electrochemical activity is significantly enhanced by Mn2+ doping. Electrochemical testing reveals that Na0.84Mn0.08Fe2PO4(SO4)2 achieves higher capacity and improved rate performance, surpassing pristine NFPS. At a current density of 25 mA g-1, the maximum discharge specific capacity of NFPS-Mn0.08 is 73 mA h g-1. After 60 cycles, the discharge capacity of NFPS-Mn0.08 is 52.7 mA h g-1.