Fusion of Bi2O3/ZnO:rGO Nanocomposites and Redox Additive Electrolyte for High-Energy-Density Supercapacitors

The improved supercapacitor performance of bismuth oxide/zinc oxide-incorporated reduced graphene oxide (rGO) (Bi2O3/ZnO:rGO-BZR) nanocomposites (NCs) in newly formulated potassium ferrocyanide-based electrolyte is reported here. BZR NCs were synthesized hydrothermally at 160 degrees and their physicochemical characteristics were examined. The formation of Bi2O3 and ZnO crystalline phases with tetragonal and hexagonal structures, respectively, in BZR NCs was revealed by x-ray diffraction (XRD) analysis. The presence of thin/transparent rGO nanosheets, Bi2O3 nanosheets, and ZnO nanoflowers was confirmed by scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM) analyses. The electrochemical characteristics were investigated through the development of working electrodes/devices with BZR NCs and tested in 1 M potassium hydroxide (KOH) and 1 M KOH with potassium ferrocyanide added (redox additive electrolyte [RAE]) electrolytes, respectively. The fabricated working electrode with BZR NCs demonstrated cyclic stability of 89.67% (5000 galvanostatic charge-discharge cycles) with specific capacitance of 2765 F g-1 in RAE. Likewise, the fabricated BZR NC-loaded supercapacitors demonstrated maximum specific capacitance of 197.2 F g-1, with energy and power density of 34.20 Wh kg-1 and 1890 W kg-1, respectively, in RAE. The proposed BZR NC-based devices thus exhibit improved power and energy density with excellent cycle stability, a core benefit for long-term industrial usage.