Exploration, of magnetic sesquioxide nanocomposite as a potential electrode material for the fabrication of high energy density asymmetric supercapacitors

Abstract

upercapacitor electrode materials with multiple redox-active sites and superior electrical conductivity are highly desirable for future energy storage devices in a cost-effective manner. Here, the nanocomposite (NC) based on the sesquioxides of iron oxide-chromium oxide (Fe2O3-Cr2O3) is synthesized by a one-step hydrothermal approach. Fe2O3-Cr2O3 NC electrode delivers a high specific capacity of 544.2 Cg−1 at the scan rate of 10 mV/s. Trasatti method reveals the charge storage mechanism of Fe2O3-Cr2O3 NC providing the total, outer, and inner capacity of 1118, 71.3, and 1047 Cg−1 respectively. In addition, the low solution resistance (RS) and charge transfer resistance (Rct) of 0.75 and 0.06 Ω respectively are being evaluated by Electrochemical Impedance Spectroscopy (EIS) analysis. Furthermore, the faradic charge–discharge curves with prolonged discharge time are achieved for the Fe2O3-Cr2O3 NC electrode material with the maximum specific capacity of 814 Cg−1 at the current density of 1 Ag−1 and the capacitive retention of 79.2 % is maintained after 5000 consecutive charge–discharge cycles. Hence, the asymmetric supercapacitor (ASC) device is being constructed using Fe2O3-Cr2O3 cathode and activated carbon (AC) anode, delivering a high energy density of 77.17 Wh kg−1 corresponding to the power density of 650 W kg−1.