Na₂MoO₄-Incorporated Polymer Gel Electrolyte for High Energy Density Flexible Supercapacitor

Abstract

The recent advancement in flexible/bendable displays such as phones, smart bands, laptops, and televisions demands flexible energy storage devices. Heteroatom-doped graphene electrodes are promising candidates for flexible energystorage applications because of its dual nature of electrochemical double-layer capacitance and pseudocapacitance. The low energy density of supercapacitors limits their potential use and attempts are in progress to overcome this issue. Redox-additive electrolytes are presumed to be one of the elite tactics to augment the energy density of the supercapacitor device. Here, the sodium molybdate (Na 2 MoO 4 )-incorporated polymer gel electrolyte has been demonstrated to enhance the energy density of a flexible supercapacitor. The supercapacitor electrode with Na 2 MoO 4 /H 2 SO 4 (714 F/g) acquired ∼2.4-fold greater specific capacitance than with H 2 SO 4 (300 F/g) in a threeelectrode configuration. Moreover, the energy density of symmetric supercapacitor with Na 2 MoO 4 /H 2 SO 4 (23 Wh/kg) is ∼2-fold higher compared with H 2 SO 4 electrolyte (13 Wh/kg). The fabricated flexible supercapacitor device with sodium molybdate/ poly(vinyl alcohol)/sulfuric acid (Na 2 MoO 4 /PVA/H 2 SO 4 ) gel electrolyte showed 3.4-fold higher energy density (E = 24 Wh/kg) compared to a device with PVA/H 2 SO 4 gel electrolyte (E = 7 Wh/kg). The increase in energy density has been observed after the incorporation of Na 2 MoO 4 , which is due to the faradaic reaction between the MoO 4 2− ions in the redox-additive and H + ions in the H 2 SO 4 electrolyte.

Fabrication of Flexible Supercapacitor Using N-Doped Porous Activated Carbon Derived from Poultry Waste

“…The deconvoluted C 1s high-resolution spectrum (Figure A) reveals the presence of four well-defined peaks at 284.5, 285.7, 287.6, and 290.3 eV, attributed to the nonoxygenated sp 2 carbon, sp 3 carbon, C–N, and CO bonds, respectively . Similarly, the three peaks at 284.4, 285.4, and 287.4 eV observed for the deconvoluted N 1s spectrum attributed to the presence of pyridinic-N, pyrrolic-N, and quaternary/graphitic-N, respectively (Figure B). − The intensity of pyrrolic-N is more than the other peaks. Moreover, the amount of N present in the PW-700 has also been quantified using XPS.…”

Solid-State Double-Network Hydrogel Redox Electrolytes for High-Performance Flexible Supercapacitors

“…Liu et al reported that double-cross-linked HEs possessed excellent stability and a great tensile strength up to 3.1 MPa . However, the solid-state DN HEs still possess inferior energy densities. − , The supercapacitors with redox electrolytes, such as KI and Na 2 MoO 4 , have been proved to possess much-enlarged capacitance and increased energy density. , To address the small capacitance and low energy density of supercapacitors, we introduce Na 2 MoO 4 , a kind of pseudocapacitive redox additive, into the double-network gel electrolytes.…”

“…[26][27][28][29]31 The supercapacitors with redox electrolytes, such as KI and Na 2 MoO 4 , have been proved to possess much-enlarged capacitance and increased energy density. 32,33 To address the small capacitance and low energy density of supercapacitors, we introduce Na 2 MoO 4 , a kind of pseudocapacitive redox additive, into the double-network gel electrolytes.…”

Nano Carbon Doped Polyacrylamide Gel Electrolytes for High Performance Supercapacitors

“…While they have good mechanical properties and are very suited to flexible devices, the solid electrolytes typically show low ionic conductivity and overall performance. Gel polymer electrolytes (GE) are a great compromise between Molecules 2021, 26, 2631 2 of 12 the liquid and solid, have relatively good mechanical properties, are lightweight, can be packaged easily, and can have higher ionic conductivity than the solids [22][23][24][25][26].…”