Unrevealed Performance of NH₄VO₃ as a Redox-Additive for Augmenting the Energy Density of a Supercapacitor

Abstract

Herein, we have used ammonium vanadate (NH4VO3) as a redox-additive for the first time to boost the energy density of a flexible supercapacitor. Surprisingly, a significant enhancement in the specific capacitance (C sp) is attained after the addition of NH4VO3 with H2SO4 (658 F g–1) when compared with H2SO4 (375 F g–1). In addition, the energy density conquered with NH4VO3/H2SO4 (32 Wh kg–1) is 4.5-fold greater than H2SO4 electrolyte at 3 A g–1 (7 Wh kg–1). Moreover, the flexible solid-state supercapacitor (FSSC) device with ammonium vanadate/poly­(vinyl alcohol)/sulfuric acid (NH4VO3/PVA/H2SO4) gel electrolyte shows a better electrochemical performance while compared with PVA/H2SO4. The electrochemical performance of the working electrode enhanced after the addition of NH4VO3 with conventional H2SO4 due to the redox reaction between the VO3 – and H+ ions.

Prussian Red Anions Immobilized Freestanding Three-Dimensional Porous Carbonaceous Networks: A New Avenue to Attain Capacitor- and Faradic-Type Electrodes in a Single Frame for 2.0 V Hybrid Supercapacitors

“…23,26,27 Mostly, carbon-based materials are electrochemically inactive, which convey outstanding power density rather than energy density. 28 Based on the charge storage mechanism, simple CNFs can offer limited electrochemical performances. However, the porous structure with a large surface area acquires not only copious electroactive sites for coordinating electrons with ions but also accessible transfer channels of electrons and ions for delivering high electrochemical activities.…”

“…From the perspective of electrode materials, carbon-based materials, especially carbon nanofibers (CNFs) stand out as outstanding supercapacitor electrodes, where the charge is accumulated by the oppositely charged ions at the electrode/electrolyte interfaces. , CNFs possess a long cyclic life span, are relatively inexpensive compared to metal-based materials, are stable in acidic and basic mediums, and are produced on a mass scale. − CNFs can be tuned and modified from various dimensionalities (2D and 3D) and porous structures (micro to macro) with desired properties such as pronounced electroactive surface area, noteworthy conductivity, various chemical functionalities, and so on. ,, Mostly, carbon-based materials are electrochemically inactive, which convey outstanding power density rather than energy density . Based on the charge storage mechanism, simple CNFs can offer limited electrochemical performances.…”

Acetaminophen: a novel redox-additive for snowballing the energy density of flexible supercapacitors

“…Harnessing the environmental friendly redox additives is one of the favourable tactics to upswing the energy density of EDLC-type of electrodes in the aqueous medium. 8–10 The quinone-based organic substance, 11,12 K 3 [Fe(CN) 6 ], 13 K 4 [Fe(CN) 6 ], 14 KI, 15 KBr, 16 FeSO 4 , 17 NH 4 VO 3 , 18 VOSO 4 , 19 NaVO 3 , 20 and Na 2 MoO 4 , 21 are the working examples of the redox additives. However, the explorations of new redox additives are in progress to fulfill the issue of the low energy density of supercapacitors.…”

“…22 Sandhiya et al fabricated the flexible supercapacitor using S-doped graphene as an electrode material and NH 4 VO 3 /PVA/H 2 SO 4 as a gel electrolyte showing excellent energy density and cyclic stability. 18 Here, we have fabricated the high-performance supercapacitor using an activated carbon electrode and a novel acetaminophen/PVA/H 2 SO 4 gel electrolyte.…”

Effects of Polyelectrolyte Surface Coating on the Energy Storage Performance in Supercapacitors

“…We note that we reach this point under the condition of fixed surface charge density, and the surface voltage varies as PE coating applies, as discussed above. However, in practical cases 43,44 and many conventional studies, 45,46 the surface voltage is fixed rather than the surface charge density. To further interpret the PE coating effect, we need to convert the capacitance−voltage relation to the conventional capacitance− charge relation.…”