Investigation of supercapacitor properties using iron tungsten porous electrode in neutral aqueous electrolyte

Porous supercapacitors (SCs) materials are great interesting for energy storage systems. Electrolyte contributes to the enhancement of supercapacitor performance. In this paper, iron tungstate mixed oxides electrode was prepared by polymeric precursor method. The material was deposited onto conductor substrate by drop casting and annealed at 500 ºC for 2 h. The thermal, structural, and morphological characterizations were realized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), micro-Raman, emission–scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM), respectively. The crystallization process of polymeric resin occurred at 454 °C. The synergistic effect of monoclinic FeWO4 and monoclinic Fe2W3O12 phases was confirmed with Fe2+|Fe3+ of iron tungstate mixed oxides. An irregular shape of condensed spherical-like particles aggregated with rough and porous nanostructures was observed. Neutral electrolytes were employed in electrochemical measurement as lithium nitrate (LiNO3) and sodium sulfate (Na2SO4). SC electrochemical analyses of FeWO4|Fe2W3O12 electrode accomplishes a capacitance of 75 F g–1 at 5 mV s–1, energy density of 3.73 Wh kg–1, power density of 582.1 W kg−1and long-term electrochemical cycling with a capacity retention of 94.04% after 6000 cycles in 1.0 mol L−1 Na2SO4. Therefore, an iron tungstate-based electrode demonstrates a potential supercapacitor device with excellent stability in a nontoxic aqueous electrolyte.