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

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 hydrother-mal 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 omega respectively are being evaluated by Electrochemical Impedance Spectroscopy (EIS) analysis. Furthermore, the faradic charge-discharge curves with prolonged dis-charge 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 consec-utive 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 cor-responding to the power density of 650 W kg-1.

Automated summary

Materials composed of iron oxide-chromium oxide (Fe2O3-Cr2O3) nanocomposites with multiple redox-active sites and superior electrical conductivity are synthesized for efficient energy storage. The Fe2O3-Cr2O3 nanocomposite electrode exhibits a high specific capacity of 544.2 Cg-1 at a scan rate of 10 mV/s, along with low solution resistance (0.75 Ω) and charge transfer resistance (0.06 Ω) as evaluated by Electrochemical Impedance Spectroscopy. Prolonged discharge time and a maximum specific capacity of 814 Cg-1 at a current density of 1 Ag-1 are achieved for the Fe2O3-Cr2O3 nanocomposite, with a capacitive retention of 79.2% after 5000 consecutive charge-discharge cycles. An asymmetric supercapacitor device, using Fe2O3-Cr2O3 as the cathode and activated carbon (AC) as the anode, delivers a high energy density of 77.17 Wh kg-1 corresponding to a power density of 650 W kg-1.