scholarly journals Hierarchical VOOH hollow spheres for symmetrical and asymmetrical supercapacitor devices

2018 ◽  
Vol 5 (1) ◽  
pp. 171768 ◽  
Author(s):  
Xuyang Jing ◽  
Cong Wang ◽  
Wenjing Feng ◽  
Na Xing ◽  
Hanmei Jiang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Electrochemical Impedance ◽  
Hydrothermal Reaction ◽  
Hollow Spheres ◽  
Asymmetric Supercapacitor ◽  
Galvanostatic Charge ◽  
Promising Candidate ◽  
Template Free ◽  
Charge Discharge ◽  
Better Than

Hierarchical VOOH hollow spheres with low crystallinity composed of nanoparticles were prepared by a facile and template-free method, which involved a precipitation of precursor microspheres in aqueous solution at room temperature and subsequent hydrothermal reaction. Quasi-solid-state symmetric and asymmetric supercapacitor (SSC and ASC) devices were fabricated using hierarchical VOOH hollow spheres as the electrodes, and the electrochemical properties of the VOOH//VOOH SSC device and the VOOH//AC ASC device were studied by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS). Results demonstrated that the electrochemical performance of the VOOH//AC ASC device was better than that of the VOOH//VOOH SSC device. After 3000 cycles, the specific capacitance of the VOOH//AC ASC device retains 83% of the initial capacitance, while the VOOH//VOOH SSC device retains only 7.7%. Findings in this work proved that hierarchical VOOH hollow spheres could be a promising candidate as an ideal electrode material for supercapacitor devices.

Template-free fabrication of NiO nanobelts: promising candidate for ethanol gas sensor at room temperature

2016 ◽  
Vol 33 (2) ◽  
pp. 68-72 ◽  
Author(s):  
Zhiwei Li
Keyword(s):  
Electron Microscopy ◽  
Gas Sensor ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Hydrothermal Reaction ◽  
Ethanol Vapor ◽  
Promising Candidate ◽  
Content Type ◽  
X Ray ◽  
Template Free

Purpose The purpose of this paper is to seek a surfactant or template-free, simple and green method to fabricate NiO nanobelts and to find an effective technique to detect the ethanol vapor at room temperature. Design/methodology/approach NiO nanobelts with high aspect ratio and dispersive distribution have been synthesized by a template-free hydrothermal reaction at 160°C for 12 h. The products are studied by X-ray diffraction (XRD), energy dispersive spectroscopY, scanning electron microscopy, atomic force microscopy, high-resolution transmission electron microscopy, selective area electron diffractio and X-ray photoelectron spectroscopy. In particular, the room-temperature ethanol sensitivity of NiO nanobelts is investigated by the surface photo voltage (SPV) technique. Findings The prepared NiO nanobelts is single crystalline bunsenite structure with the length of approximately 10 μm and the diameter of approximately 30 nm. The atomic ratio of “Ni” to “O” is 0.92:1. When the concentration of ethanol vapor reaches 100 ppm, the sensitivity of NiO nanobelts is 7, which can meet the commercial demanding of ethanol gas sensor. Originality/value The NiO nanobelts can be obtained by a template-free, simple and green hydrothermal reaction at 160°C for 12 h. The NiO nanobelts-based gas sensor is a promising candidate for the application in ethanol monitoring at room temperature by SPV technique.

Effect of Synthesis Conditions on Pseudocapacitance Properties of Nitrogen-Doped Porous Carbon Materials

2019 ◽  
Vol 59 ◽  
pp. 112-125
Author(s):  
Volodymyr Boichuk ◽  
Volodymyr Kotsyubynsky ◽  
Andrii Kachmar ◽  
Sergiy Budzulyak ◽  
Ivan Budzulyak ◽  
...  
Keyword(s):  
Carbon Materials ◽  
Aqueous Electrolyte ◽  
Electrochemical Impedance ◽  
Galvanostatic Charge ◽  
Discharge Data ◽  
Synthesis Conditions ◽  
Capacitive Properties ◽  
Charge Discharge ◽  
Redox Capacitance

The electrochemical properties of the nitrogen-enriched carbons obtained by plant raw treatment as electrode material for supercapacitors were investigated by electrochemical impedance spectroscopy, cycling voltammetry and galvanostatic charge-discharge cycling in KOH aqueous electrolyte. The effect of activation agent (NaOH) concentration and carbonization temperature were analyzed. The separation of double layer and redox capacitance components was done. The dominating role of microporosity for capacitive properties was demonstrated. The capacitance of model capacitors based on carbons obtained at different modes was calculated from both from cycling voltammetry and galvanostatic charge-discharge data. The maximal values of specific capacitance of carbon materials carbonized at 600°C and 900°C are about 100 and 120 F/g, respectively.

Physicochemical Characteristics of an Ultra-Thin Hydrophobic Trichlorosilanes Using SiO2 as Adhesion

2019 ◽  
Vol 796 ◽  
pp. 80-87
Author(s):  
Akinsanya Damilare Baruwa ◽  
Esther Titilayo Akinlabi ◽  
Oluseyi Philip Oladijo ◽  
Stephen Akinwale Akinlabi ◽  
Jeff Chinn
Keyword(s):  
Room Temperature ◽  
Electrochemical Impedance ◽  
Physicochemical Characteristics ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Natural Seawater ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrophobic Silane ◽  
Better Than

The aim of the research is to subject the three different silanes to chemical and electrochemical investigations in other to determine the most efficient organic compound. Three types of hydrophobic silanes [Tris (Trimethylsiloxy) silyethyl] dimethylchlorosilane (Alkyl); Tridecafloro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS) and Henicosyl-1,1,2,2-tetrahydrododecyltricholrosilane (FDDTS) are presented and investigated. The three silanes are of different composition but are deposited at the same parameters and conditions. The chemical investigation was studied through (attenuated total reflection Fourier-transform infrared (ATR-FTIR) and x-ray diffraction (XRD), while the electrochemical study was conducted through EIS using natural seawater electrolyte at room temperature. From the investigation techniques, only electrochemical impedance results show that FDDTS performed better than both Alkyl and FOTS. The chemical analysis showed the presence of hydrophobic silane on all the coated samples, and no distinction can be drawn from associated peaks.

Influence of Separator Thickness on the Performance of Electric Double Layer Supercapacitors in Aqueous Electrolyte

2020 ◽  
Vol 1012 ◽  
pp. 109-113
Author(s):  
D.V. Silva ◽  
G.S. Galdino ◽  
Lusinete Pereira Barbosa ◽  
J.C.S. Casini ◽  
R.N. Faria
Keyword(s):  
Electric Double Layer ◽  
Room Temperature ◽  
Aqueous Electrolyte ◽  
Carbon Electrodes ◽  
Galvanostatic Charge ◽  
Homogeneous Microstructure ◽  
X Ray ◽  
Morphological Evaluation ◽  
Charge Discharge ◽  
Discharge Curves

The effects of the separator thickness (δ) upon the equivalent series resistances (ESR) and specific capacitances (Cs) of supercapacitors electrodes have been investigated using commercially available porous filter paper (δ=150 μm, pores size=7.5 μm, 80 gm-2). Commercial activated carbon electrodes immersed in 1molL-1 KOH electrolyte (25°C) have been employed in this study. The specific capacitances were calculated from cyclic voltammetry curves at room temperature employing various scan rates (5, 10, 15 and 30 mVs-1). Internal series resistances of the supercapacitors were measured using the galvanostatic charge discharge curves also at room temperature. A maximum of 28 separators (δ=4200 μm) have been employed in this investigation. It has been shown that the ESR increases substantially with separator thickness (from 3.1 to 7.9 Ωcm2). The specific capacitance decreased somewhat with increasing separator thickness and scan rates (from 64 to 52 Fg-1; at 5 mVs-1). The microstructures of the electrode material have been investigated using scanning electron microscopy (SEM) and chemical microanalyses employing energy dispersive X-ray analysis (EDX). A compositional and morphological evaluation of these electrodes showed a very homogeneous microstructure.

Preparation and Properties of Poly-2,5-dihydroxyaniline/Activated Carbon Composite Electrode

2012 ◽  
Vol 190-191 ◽  
pp. 528-533
Author(s):  
Miao Sun ◽  
Wei Wang ◽  
Ben Lin He ◽  
Ming Liang Sun ◽  
Fan Sun ◽  
...  
Keyword(s):  
Electrochemical Method ◽  
Composite Electrode ◽  
Electrochemical Impedance ◽  
Carbon Composite ◽  
Galvanostatic Charge ◽  
Acid Aqueous Solution ◽  
Carbon Composite Electrode ◽  
A Current ◽  
Charge Discharge ◽  
Discharge Test

Poly-2, 5-dimethoxyaniline (PDMA) coating was successfully prepared by electrochemical method on the surface of active carbon (AC) electrodes in oxalic acid aqueous solution. The resulted coating was hydrolyzed to produce poly-2,5-dihydroxyaniline (PDHA) to enhance the capacitance of the composite electrode. Scanning electron microscope (SEM), cyclic voltammetry (CV), galvanostatic charge/discharge test, and electrochemical impedance spectroscopy (EIS) were used to investigate the properties of these electrodes. A comparative analysis on the electrochemical properties of bare-carbon electrode was also conducted under similar conditions. The specific capacitance of the PDHA/AC composite electrode was 947.04 F•g-1 between 0.0 and 1.0 V at a current density of 3.0 mA•cm-2 in 0.5 M H2SO4 electrolyte. The capacitance retention of composite electrode was about 89.2% during 700 charge-discharge cycles.

Nitric Acid Activated Carbon Aerogels for Supercapacitors

2013 ◽  
Vol 302 ◽  
pp. 158-164 ◽  
Author(s):  
Ya Jie Li ◽  
Xing Yuan Ni ◽  
Jun Shen ◽  
Dong Liu ◽  
Nian Ping Liu
Keyword(s):  
Activated Carbon ◽  
Nitric Acid ◽  
Electrochemical Impedance ◽  
Carbon Aerogels ◽  
Electrochemical Performances ◽  
Galvanostatic Charge ◽  
Sem Images ◽  
Resorcinol Formaldehyde ◽  
Charge Discharge ◽  
Discharge Test

The electrochemical performances of resorcinol–formaldehyde-based carbon aerogels can be significantly enhanced by nitric acid activation.FT-IR spectra and SEM images reveal the constitution and morphology of samples .The electrochemical performances of materials were tested by cyclic voltammetry,galvanostatic charge/discharge test ,electrochemical impedance spectroscopy and cyclic test. The results show that activation does not influence the molecular structure of carbon aerogels,which maintains their nano-porous structure. Activation increases the specific capacitance by 50% and improves the conductivity of carbon aerogels,resulting in fenfect cycling stability. So nitric acid activated carbon aerogels is an ideal electrode material for supercapacitors.

Ag Doped Co3O4 Nanowire Arrays as an Electrode Material for Electrochemical Capacitors

2012 ◽  
Vol 268-270 ◽  
pp. 157-163 ◽  
Author(s):  
Yang Xu ◽  
Ji Chun Huang ◽  
Lin Cheng ◽  
Dian Xue Cao ◽  
Gui Ling Wang
Keyword(s):  
Electrochemical Impedance ◽  
Nickel Foam ◽  
Nanowire Arrays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Growth Method ◽  
Template Free ◽  
A Current ◽  
Charge Discharge ◽  
Discharge Test

Co3O4 nanowire arrays freely standing on nickel foam are prepared via a template-free growth method，and it is doped by Ag via electrodeposition method (denoted as NWA-Ag/Co3O4，NWA represents Nanowire Arrays). The morphology of NWA-Ag/Co3O4 is examined by scanning electron microscopy. The phase structure of the NWA-Ag/Co3O4 electrode is characterized by X-ray diffraction spectroscopy. The supercapacitance behavior of the NWA-Ag/Co3O4 electrodes is investigated by cyclic voltammetry, galvanostatic charge/discharge test and electrochemical impedance spectroscopy. The results show that the nanowire arrays densely cover the nickel foam substrate and have diameters around 250 nm. The NWA-Ag/Co3O4 electrodes exhibit a specific capacitance of 1009 F g−1 at a current density of 5 mA cm-2 in 6.0 mol dm-3 KOH electrolyte. The capacitance loss is less than 6.5% after 500 charge/discharge cycles at 10 mA cm-2 and with columbic efficiency higher than 97.5%.

Template-free room temperature solution phase synthesis of Cu2O hollow spheres

CrystEngComm ◽  
2010 ◽  
Vol 12 (3) ◽  
pp. 700-701 ◽  
Author(s):  
Wenzhong Wang ◽  
Pengcheng Zhang ◽  
Lei Peng ◽  
Wenjuan Xie ◽  
Guling Zhang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Hollow Spheres ◽  
Solution Phase ◽  
Phase Synthesis ◽  
Solution Phase Synthesis ◽  
Temperature Solution ◽  
Template Free

A high-performance graphene based asymmetric supercapacitor

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040007
Author(s):  
Syeda Wishal Bokhari ◽  
Ahmad Hassan Siddique ◽  
Harshpreet Singh ◽  
Muhammad Dilawer Hayat ◽  
Shenmin Zhu ◽  
...  
Keyword(s):  
Energy Density ◽  
Electrochemical Performance ◽  
Power Density ◽  
High Performance ◽  
Hybrid Nanocomposites ◽  
Asymmetric Supercapacitor ◽  
Galvanostatic Charge ◽  
Asymmetric Device ◽  
Charge Discharge

We present the design of a high-performance 2 V asymmetric supercapacitor made of graphene-based hybrid nanocomposites in 1 M KOH electrolyte. rGO-CNT-FeOOH (GC-F) was used as the cathode and rGO-CNC-MnO2 (GC-M) as the anode. Both composites well balanced each other in the asymmetric device and gave a high electrochemical performance. The energy density of this ASC is 66.6 W h kg[Formula: see text] at 3.8 kW kg[Formula: see text] power density with an excellent capacitance retention of 88% after 3000 galvanostatic charge-discharge cycles.

scholarly journals Capacitive behavior of functionalized activated carbon-based all-solid-state supercapacitor

2021 ◽  
Author(s):  
Kyu Seok Lee ◽  
Ye Ji Seo ◽  
Hyeon Taek Jeong
Keyword(s):  
Cyclic Voltammetry ◽  
Activated Carbon ◽  
Solid State ◽  
Specific Capacitance ◽  
Electrochemical Impedance ◽  
Electrochemical Performances ◽  
Galvanostatic Charge ◽  
Capacitive Behavior ◽  
Charge Discharge ◽  
Discharge Curves

AbstractIn this report, we incorporate activated carbon (AC) onto aluminum substrate via doctor blade method to produce an all-solid-state supercapacitor. The electrochemical properties of the all-solid-state supercapacitor were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Galvanostatic charge/discharge tests also were carried out to exhibit stability of the AC-based supercapacitor. The impedance and charge/discharge curves of the all-solid-state supercapacitor showed good capacitive behavior after functionalized AC. The highest specific capacitance obtained for the AC-based supercapacitor was 106 F g−1. About 160% of specific capacitance increased after functionalization of the AC, which indicated that modification of the AC by nitric acid was able to introduce functional groups on the AC and improve its electrochemical performances.

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