High-Energy Flexible Supercapacitor—Synergistic Effects of Polyhydroquinone and RuO₂·xH₂O with Microsized, Few-Layered, Self-Supportive Exfoliated-Graphite Sheets

Abstract

An effective and straightforward route for tailoring the self-supporting, exfoliated flexible graphite substrate (E-FGS) using electrochemical anodization is proposed. E-FGS has essential features of highly exfoliated, few-layered, two-dimensional graphite sheets with the size of several tens of micrometers, interconnected along the axis of the substrate surface. The novel hierarchical porous structural morphology of E-FGS enables large active sites for efficient electrolyte ion and charge transport when used as electrode material for a supercapacitor. In order to effectively utilize this promising E-FGS electrode for energy storage purpose, a ternary composite is further synthesized with pseudocapacitive polyhydroquinone (PHQ) and hydrous RuO 2 (hRO). hRO is synthesized via a sol−gel route, while electropolymerization is utilized for the electrodeposition of PHQ over E-FGS. Ultimately, the fabricated self-supporting E-FGS-based flexible supercapacitor is capable of delivering areal specific capacitance values as high as 378 mF cm −2 at a current density of 1 mA cm −2 . Addition of the pseudocapacitive component to the E-FGS texture leads to ∼10 times increase of the electrochemical charge storage capability. The imposition of mechanical forces to this flexible supercapacitor device results in trivial changes in electrochemical properties and is still capable of retaining 91% of the initial specific capacitance after 10 000 cycles. Alongside, the fabricated symmetrical solid-state flexible device exhibited a high energy density of 8.4 μWh cm −2 . The excellent performance along with the ease of synthesis and fabrication process of the flexible solid-state supercapacitor device using PHQ/hRO/E-FGS holds promise for large-scale production.

Advances on Emerging Materials for Flexible Supercapacitors: Current Trends and Beyond

“…While on the other hand, the exfoliated graphene sheets were deposited with the hydrous RuO 2 particles and polyhydroquinone through the simple electrodeposition process. [ 125 ] Due to the hydroquinone having more hydroxylated groups compared to any other conducting polymers, the exchange of protons is more feasible in addition and oxidation reaction reactions. Thus, when the RuO 2 is added, the hydrous part of RuO 2 in the electrochemical reaction expresses a very high conductivity and as expected the discharge cycles were also longer.…”

Controllable Intercalated Polyaniline Nanofibers Highly Enhancing the Utilization of Delaminated RuO2 Nanosheets for High‐Performance Hybrid Supercapacitors

“…The deconvoluted Ru 3p spectrum of RuO 2 exhibits two peaks corresponding to Ru 3p 3/2 and Ru 3p 1/2 , which consist of Ru 4 + peaks (463.9 and 486.2 eV) as well as hydrous RuO 2 peaks (465.9 and 488.3 eV), and this can evidence the presence of RuO 2 . [39] Notablely, the Ru 3p spectrum for PANI/RuO 2 -38 shift to higher binding energy compared to that of RuO 2 , which indicates the electron redistribution at the interface between PANI and RuO 2 . Figure 2f shows that the O1s spectrum convoluted into three peaks at 530.3, 531.2, and 532.3 eV in RuO 2 are assigned to RuÀ OÀ Ru,…”

“…[38] It yields higher specific capacity than that of the crystalline RuO 2 attributed to the hydrous moiety involved in proton permeability. [39] In view of the overlap of the Ru 3d peaks with C 1s peak to some extent, the Ru 3p spectra is used for analyzing the Ru oxidation state (Figure 2e). The deconvoluted Ru 3p spectrum of RuO 2 exhibits two peaks corresponding to Ru 3p 3/2 and Ru 3p 1/2 , which consist of Ru 4 + peaks (463.9 and 486.2 eV) as well as hydrous RuO 2 peaks (465.9 and 488.3 eV), and this can evidence the presence of RuO 2 .…”

Supercapacitor performances of RuO2/MWCNT, RuO2/Fullerene nanocomposites

“…Energy and power density of this h‐RuO 2 /MWCNT was obtained E = 10.2 Wh/kg and P = 431 W/kg. Finally, Muniraj et al investigated the RuO 2 /CNOs material and found energy and power values of RuO 2 /CNOs as E = 10.62 Wh/kg and P = 4.456 kW/kg.…”