Fabrication and its electrochemical investigation of coin cell supercapacitors in redox additive electrolyte

Abstract

The development of coin cell supercapacitors with enhanced performance played a pivotal role in modern energy storage devices. In this study, high-performance coin cell supercapacitors were fabricated using conventional copper oxide (CuO-CO) and multiwalled carbon nanotube-mediated CuO (CuO@MWCNT-CM) nanocomposites (NCs)-based electrodes and aqueous KOH electrolyte with potassium ferrocyanide as redox additive electrolyte (RAE). The synergistic effects between the metal oxide and MWCNT in terms of conductivity, redox stability, and performances significantly boosted the electrode performance. Further, the additional redox active sites produced by the optimized concentration of RAE enhanced the supercapacitor’s performances. As the evident of synergistic effect between CuO and MWCNT, and redox additives utilization, the developed supercapacitors with CM NCs delivered the highest C_sp and specific capacities of 240.54 F g⁻¹ and 93.54 mAh g⁻¹, respectively, with the superior energy density, power density, and cyclic stability values of 40.09 Wh kg⁻¹, 1125 W kg⁻¹, and 70.1% (after 10,000 GCD cycles), respectively, in RAE. The asymmetrical coin cell supercapacitors (CR2032) were fabricated using CO NPs and CM NCs with KOH and RAE electrolytes. The charging and discharging capacities of the fabricated coin cell supercapacitors were tested, and it revealed that CM NCs-based coin cell supercapacitors with RAE explored extended charge and discharge capabilities than other coin cell combinations.