Synthesis and electrical studies of Na3Fe(SO4)3 cathode material for sodium ion batteries

In this paper, we report phase formation and dielectric studies of Na3Fe(SO4)3 compound, a possible cathode material for sodium ion batteries. Na3Fe(SO4)3 was synthesized using conventional ceramic powder mixing and solid state reaction route. The phase formed powder was investigated using powder X-ray diffraction (XRD) which revealed a eldfellite Na3Fe(SO4)3 phase for the compound. The electrode material was tested for its conductivity and permittivity behavior over a wide frequency (1 Hz to 1 MHz) and temperature (−100 to 100 °C) ranges. The conductivity of the sample, without addition of any conducting carbon, was found to vary between 10−6 S/cm - 10−9 S/cm over measured frequency and temperature ranges. The complex impedance (Z′ vs −Z″) study was carried out over the sample to understand contribution of various components (viz. interfaces at sample collector, junction between grain and grain boundaries etc.) on the overall electronic behavior of this positive electrode.