Carbon Dioxide Tornado-Type Atmospheric-Pressure-Plasma-Jet-Processed rGO-SnO2 Nanocomposites for Symmetric Supercapacitors

Abstract

Pastes containing reduced graphene oxide (rGO) and SnCl2 solution were screen printed on carbon cloth and then calcined using a CO2 tornado-type atmospheric-pressure plasma jet (APPJ). The tornado circulation of the plasma gas enhances the mixing of the reactive plasma species and thus ensures better reaction uniformity. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were performed to characterize the synthesized rGO-SnO2 nanocomposites on carbon cloth. After CO2 tornado-type APPJ treatment, the pastes were converted into rGO-SnO2 nanocomposites for use as the active electrode materials of polyvinyl alcohol (PVA)-H2SO4 gel-electrolyte flexible supercapacitors (SCs). Various APPJ scanning times were tested to obtain SCs with optimized performance. With seven APPJ scans, the SC achieved the best areal capacitance of 37.17 mF/cm2 in Galvanostatic charging/discharging (GCD) and a capacitance retention rate of 84.2% after 10,000-cycle cyclic voltammetry (CV) tests. The capacitance contribution ratio, calculated as pseudocapacitance/electrical double layer capacitance (PC/EDLC), is ~50/50 as analyzed by the Trasatti method. GCD data were also analyzed to obtain Ragone plots; these indicated an energy density comparable to those of SCs processed using a fixed-point nitrogen APPJ in our previous study.

Ultrafast Fabrication of H2SO4, LiCl, and Li2SO4 Gel Electrolyte Supercapacitors with Reduced Graphene Oxide (rGO)-LiMnOx Electrodes Processed Using Atmospheric-Pressure Plasma Jet

“…Second, ions have more time to adsorb/desorb on the electrode surface, thus contributing to EDLC. Figure S2 and Table S1 (please see the Supplementary Material/File for more information) show the capacitance contribution ratio calculated using the Trasatti analysis method [ 44 ]. Trasatti analysis indicates that, compared to H 2 SO 4 , LiCl and Li 2 SO 4 exhibit a higher proportion of PC.…”

Comparison between PEDOT:PSS and Carbon Pastes for Preparing Flexible Electrodes of Supercapacitors

“…Previous research showed that the higher hydrophilicity increases the contact between the electrode and the gel-electrolyte, and improves the specific capacitance in a SC. 27,38,39 SEM inspection of electrodes.-Figure 2 shows SEM images of electrodes at 1000× magnification. After screen-printing PEDOT: PSS pastes and CP, some glue-type material was formed between the carbon fibers.…”

East Asian Calligraphy Black Ink-Coated Paper as Flexible Conducting Electrode for Supercapacitor

“…Electrochemical measurement of a supercapacitor.-The specific capacitance is represented by the areal specific capacitance. The areal specific capacitance was calculated from CV curves as follows 64 :…”

“…where C a is the specific capacitance (mF cm -2 ); A, the area of the CV curve; s, the geometric area of the active part (2 × 1.5 cm 2 ); v, the scan rate (V s −1 ); and V , ∆ is the potential window (V). The areal specific capacitance was calculated from GCD curves as follows 64 : Figure 10 shows CV curves and GDC curves for 1 M H 2 SO 4 gelelectrolyte supercapacitors that used 3-coated paper as the electrode under different potential scan rates and different constant charge/ discharge currents. Figure 10a shows the CV curves results of the 1 M H 2 SO 4 gel-electrolyte supercapacitor.…”