Electrochemical performance of facile developed aqueous asymmetric (Fe,Cr)2O3//MnO2 supercapacitor

Highlights: • Preparation of (Fe,Cr)₂O₃ oxide layer and MnO₂ nanoparticles as a binder free electrode materials. • (Fe,Cr)₂O₃ and MnO₂ shows the specific capacitance of 372 and 174 Fg^-1 in Na₂SO₄ electrolyte. • Development of aqueous asymmetric supercapacitor made from (Fe,Cr)₂O₃ and MnO₂. • Asymmetric supercapacitor shows the high specific capacitance of 37 Fg^-1 in Na₂SO₄ electrolyte. • Asymmetric supercapacitor shows the high-energy density of 20.89 Whkg⁻¹ in Na₂SO₄ electrolyte. The present study demonstrate the development of novel aqueous asymmetric supercapacitor based on polygonal integrated oxide layer ((Fe,Cr)₂O₃) as the anode and spherical MnO₂ nanoparticles as the cathode. The polygonal (Fe,Cr)₂O₃ integrated oxide layer was obtained by the simple thermal oxidation method and low-cost, scalable chemical route was employed for the synthesis of spherical MnO₂ nanoparticles. Furthermore, electrochemical investigations of asymmetric supercapacitor (ASC) studied in aqueous electrolytes show an extended operating voltage of 1.6 and 2.0 V with the maximum specific capacitance of 34 and 37 Fg^-1 in KOH and Na₂SO₄, respectively. The observed energy density and power density of ASC in Na₂SO₄ (or KOH) electrolyte is 20.89 (or 12.36) Whkg⁻¹ and 2173.913 (or 1739) Wkg⁻¹, respectively. ASC shows the better capacitance retention over the 5000 cycles in both the electrolytes. Therefore, present study open-up new construction of inexpensive petty (Fe,Cr)₂O₃ anode material for the development of high energy density ASCs.