The Effect of Vacuum Annealing and HDDR Processing on the Electrochemical Characteristics of Activated Carbon and Graphene Oxide for the Production of Supercapacitors Electrodes

2020 ◽  
Vol 1012 ◽  
pp. 125-130
Author(s):  
P.V.D. Cruz ◽  
Ivana Conte Cosentino ◽  
E. Galego ◽  
D.S. Yoshikawa ◽  
R.N. Faria
Keyword(s):  
Activated Carbon ◽  
Specific Capacitance ◽  
Activated Carbons ◽  
Electrochemical Characteristics ◽  
Equivalent Series Resistance ◽  
Carbon Structure ◽  
Morphological Evaluation ◽  
Current Densities ◽  
Double Layer Capacitors ◽  
Parallel Resistance

Electric double-layer capacitors prepared using activated carbons have been subjected to vacuum heat treatments at low and high temperatures (200, 400, 600, 800 and 1000°C). The electrodes have been tested at a potential of 1.1 V employing a KOH electrolyte (1.0and 6.0 mol.L-1). The effect of or HDDR upon the electrical properties has been investigated by cyclic voltammetry. It has been shown that the specific capacitance at 5 msV-1 increases from 50 Fg-1 to 130 Fg-1 after a heat treatment at 400°C for 1 hour under back pump vacuum. At 400°C the diminution in the specific capacitance with higher scanning rate (10 msV-1) was much less pronounced (from 130 Fg-1 to 100 Fg-1). Equivalent series resistance (ESR) and equivalent parallel resistance of supercapacitors electrodes have also been investigated. Internal resistances of the supercapacitors were calculated using the galvanostatic curves at current densities (100 mAg-1).A compositional and morphological evaluation of these electrodes showed no significant change on the activated carbon structure.

scholarly journals Effect of porosity enhancing agents on the electrochemical performance of high-energy ultracapacitor electrodes derived from peanut shell waste

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
N. F. Sylla ◽  
N. M. Ndiaye ◽  
B. D. Ngom ◽  
D. Momodu ◽  
M. J. Madito ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Electrochemical Performance ◽  
Specific Capacitance ◽  
Activated Carbons ◽  
High Energy ◽  
Specific Power ◽  
Koh Activation ◽  
Peanut Shell ◽  
Equivalent Series Resistance ◽  
Shell Waste

Abstract In this study, the synthesis of porous activated carbon nanostructures from peanut (Arachis hypogea) shell waste (PSW) was described using different porosity enhancing agents (PEA) at various mass concentrations via a two-step process. The textural properties obtained were depicted with relatively high specific surface area values of 1457 m2 g−1, 1625 m2 g−1 and 2547 m2 g−1 for KHCO3, K2CO3 and KOH respectively at a mass concentration of 1 to 4 which were complemented by the presence of a blend of micropores, mesopores and macropores. The structural analyses confirmed the successful transformation of the carbon-containing waste into an amorphous and disordered carbonaceous material. The electrochemical performance of the material electrodes was tested in a 2.5 M KNO3 aqueous electrolyte depicted its ability to operate reversibly in both negative and positive potential ranges of 0.90 V. The activated carbon obtained from the carbonized CPSW:PEA with a mass ratio of 1:4 yielded the best electrode performance for all featured PEAs. The porous carbons obtained using KOH activation displayed a higher specific capacitance and the lower equivalent series resistance as compared to others. The remarkable performance further corroborated the findings linked to the textural and structural properties of the material. The assembled device operated in a neutral electrolyte (2.5 M KNO3) at a cell potential of 1.80 V, yielded a ca. 224.3 F g−1 specific capacitance at a specific current of 1 A g−1 with a corresponding specific energy of 25.2 Wh kg−1 and 0.9 kW kg−1 of specific power. This device energy was retained at 17.7 Wh kg−1 when the specific current was quadrupled signifying an excellent supercapacitive retention with a corresponding specific power of 3.6 kW kg−1. These results suggested that peanut shell waste derived activated carbons are promising candidates for high-performance supercapacitors.

Effects of Electrolyte Substitution on the Specific Capacitance and Equivalent Series Resistance of Energy Storage Electrochemical Supercapacitors

2020 ◽  
Vol 1012 ◽  
pp. 131-135
Author(s):  
L.B. Fantin ◽  
D.S. Yoshikawa ◽  
E. Galego ◽  
R.N. Faria
Keyword(s):  
Specific Capacitance ◽  
Series Resistance ◽  
Specific Capacity ◽  
Initial Study ◽  
Organic Electrolyte ◽  
Equivalent Series Resistance ◽  
Morphological Evaluation ◽  
Discharge Density ◽  
Current Densities ◽  
A Current

The microstructure, chemical composition, equivalent series resistance (ESR) and specific capacitance (Cs) of supercapacitors electrodes have been investigated. Commercial activated carbon electrodes employing organic electrolyte have been tested at a potential window of 1.1 and 2.7 V. Specific capacitances were calculated from cyclic voltammetry curves at room temperature employing various scan rates (2-70 mVs-1). Internal resistances of the supercapacitors were calculated using the galvanostatic cycling curves at several current densities (10-175 mAg-1). A maximum specific capacity of 58 Fg-1 has been achieved with the organic electrolyte at a current density of 30 mAg-1 and a potential window of 2.7V. After this initial study, the organic electrolyte was removed from the electrodes by back pumping vacuum. Two new aqueous electrolytes have been substituted in the commercial electrodes for a comparison: Na2SO4 and KOH (1.0 mol.L-1). At a discharge density of 75 mAg-1, the electrodes with KOH showed a maximum specific capacitance of 53 Fg-1 whereas the Na2SO4 showed only 6 Fg-1. ESR of the electrodes with organic electrolyte and KOH were in the range of 20 Ωcm2 whereas with Na2SO4 of 14 Ωcm2. 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 structure.

Surface Oxidation Modification and Performance of Activated Carbon Electrode Material

2011 ◽  
Vol 347-353 ◽  
pp. 3456-3458
Author(s):  
Ren Qing Wang ◽  
Mei Gen Deng
Keyword(s):  
Activated Carbon ◽  
Specific Capacitance ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Surface Oxidation ◽  
Constant Current ◽  
Carbon Electrode ◽  
Constant Current Charge ◽  
And Performance ◽  
Double Layer Capacitors

Superscript text Commercial activated carbon was modified by surface treatment using nitric acid, The modified carbons were characterized by X-ray photoelectron spectroscopy (XPS).The resultant carbon electrode-based electric double-layer capacitors (EDLCs)were assembled with 1 mol/L （NH4）2SO4 as the electrolyte. The influence of introduced functional groups, such as hydroxyl and carbonyl, on the performance of EDLCs was studied by Constant current charge-discharge. These functional groups significantly improved the wettability of AC. As a result, the specific capacitance of the carbon modified with 40wt.%HNO3 achieved a specific capacitance of 223.45 F/g at a current density of 5mA/cm2, which is 100.9% higher than that of original AC.

scholarly journals Sago Waste Based Activated Carbon Film as an Electrode Material for Electric Double Layer Capacitor

2010 ◽  
Vol 4 (1) ◽  
pp. 117-124 ◽  
Author(s):  
H. Aripin ◽  
L. Lestari ◽  
D. Ismail ◽  
S. Sabchevski
Keyword(s):  
Activated Carbon ◽  
Double Layer ◽  
Electrode Material ◽  
Electric Double Layer ◽  
Specific Capacity ◽  
Carbon Film ◽  
Electrochemical Characteristics ◽  
Double Layer Capacitor ◽  
Sago Waste ◽  
Double Layer Capacitors

In this feasibility study a novel prospective electrode material for electric double layer capacitors (EDLC) has been investigated. This promising material is activated carbon (AC) film produced using sago waste as a precursor. Important parameters of the technological process are the KOH to charcoal ratio and the content of the polytetrafluoroethylene (PTFE) binder. The influence of these parameters on the microtexture and pore structure and on the electrochemical characteristics of the AC films has been studied in detail. The measured specific surface area (SSA) of the samples is in the range from 212 to 1498 m2/g. It has been found that the presence of micropores increases the specific capacity while the presence of the mesopores acts in the opposite direction, because these mesopores are too wide in diameter for aqueous electrolyte. The specific capacitance of the studied samples has been found to be in the range from 16 to 64 F/g.

Preparation of Activated Carbons for Electrochemical Capacitors by Microwave Heating

2011 ◽  
Vol 704-705 ◽  
pp. 1061-1067
Author(s):  
Bao Lin Xing ◽  
Lun Jian Chen ◽  
Chuan Xiang Zhang ◽  
Hui Guo
Keyword(s):  
Specific Capacitance ◽  
Microwave Heating ◽  
Current Density ◽  
Electrochemical Impedance ◽  
Activated Carbons ◽  
Electrochemical Capacitors ◽  
Weight Ratio ◽  
Heating Time ◽  
Koh Activation ◽  
Electrochemical Characteristics

Activated carbons (ACs) were prepared from lignite by microwave heating with KOH as activation agent, the effects of the weight ratio of KOH to coal and microwave heating time on the pore structure of ACs were investigated by N2 adsorption. The electrochemical characteristics of electrochemical capacitors (ECs) with ACs as electrodes in 3mol/L KOH electrolyte were evaluated by galvanostatic charge/discharge cycling, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the BET specific surface area and total pore volume of ACs (denoted as AC-R3) can reach 2097m2/g and 1.19cm3/g respectively when the weight ratio of KOH to coal is 3:1 and the microwave heating time is 10 min. The ECs with AC-R3 as electrodes presents a high specific capacitance of 335F/g at a low current density of 50mA/g and still remains 288F/g even at a high current density of 5A/g, it has excellent cycling stability and low leakage current, and the residual specific capacitance is as high as 93.6% after 1000 cycles under the current density of 2.5A/g. The results have demonstrated that the microwave heating with KOH activation is an efficient approach to prepare ACs with high performance for ECs. Keywords: Activated Carbons; Microwave Heating; Electrochemical Capacitors; Electrochemical Characteristics

RESOURCE STABILITY OF ACTIVATED CARBON FROM WOOD IN SUPERCAPACITORS WITH ORGANIC ELECTROLYTE

1970 ◽  
Vol 61 (11) ◽  
Author(s):  
Daria E. Vervikishko ◽  
Svetlana A. Kochanova ◽  
Alexander V. Dolzhenko ◽  
Irina A. Lipatova ◽  
Evgeny I. Shkolnikov
Keyword(s):  
Activated Carbon ◽  
Functional Groups ◽  
Activated Carbons ◽  
Autonomous Systems ◽  
Great Influence ◽  
Organic Electrolyte ◽  
Electrochemical Characteristics ◽  
High Resource ◽  
Electric Capacity ◽  
A Charge

One of advantages of supercapacitors in comparison with batteries is their potentially high resource. Resource stability, as well as a supercapacitor self-discharge, depends on many factors. The most important of them are impurities in electrolyte, carbon materials and functional groups on their surface. Authors have offered perspective carbon material – the activated carbon from wood received by thermochemical synthesis. The electric capacity around 160 F/g is reached in supercapacitors with aprotic organic electrolyte (1M tetraethylammonium tetrafluoroborate). Authors have conducted the research of properties of the developed activated carbons from wood aiming to check resource opportunities supercapacitors with aprotic organic electrolyte. Resource tests lasted more than 6.5 months. Today more than one million cycles of a charge – discharge are reached at charge current of 100 mA/cm2. It is established that functional groups have a great influence on a resource of supercapacitors. To achieve high levels of stability in the resource activation technology developed carbon is provided to minimize the number of functional groups. Heat treatment of carbons after activation in the environment of argon at the increased temperatures was in addition carried out. It is shown that electrochemical characteristics of the supercapacitor throughout resource tests are at the stable level. Thus, there are bases to believe that devices on the basis of this carbon will be able to work continuously during the large period of time that is especially important, for example, for the autonomous systems located in hard-to-reach spots.

Preparation and Electrochemical Characterization of an Activated Carbon Material of High Surface Area for Supercapacitor

2012 ◽  
Vol 463-464 ◽  
pp. 410-414 ◽  
Author(s):  
Jing Li ◽  
Xiao Dong Zhao
Keyword(s):  
Activated Carbon ◽  
Specific Capacitance ◽  
Surface Area ◽  
Carbon Material ◽  
Chemical Activation ◽  
High Surface ◽  
High Surface Area ◽  
High Specific Capacitance ◽  
Carbon Electrode ◽  
Equivalent Series Resistance

A low-cost organic compound mainly comprising of polyarylate was selected as precursor and a chemical activation method was used to prepare an activated carbon material of large surface area, with which the activated carbon electrodes of high specific capacitance were fabricated for supercapacitor. Impact of activating temperature on the specific capacitance of activated carbon electrode was studied, the relationship between the pore structure, surface area and specific capacitance of activated carbon electrode were discussed. The specific capacitance and ESR (equivalent series resistance ) of the electrode fabricated with the activated carbon prepared at 700°C is 211F.g-1 and 0.2Ω/cm2 in hydrous electrolyte and the 122F/g and 1Ω/cm2 in orgnic electrolyte respectively. Because of the different ion diameter in orgnic and hydrous electrolyte, activated electrode show different electrochemical behavior in cyclic voltammetry examinations.

scholarly journals Morphological effect on the electrochemical behavior of electric double-layer capacitors

2001 ◽  
Vol 16 (12) ◽  
pp. 3402-3410 ◽  
Author(s):  
M. Endo ◽  
Y. J. Kim ◽  
T. Maeda ◽  
K. Koshiba ◽  
K. Katayam ◽  
...  
Keyword(s):  
Specific Capacitance ◽  
Surface Area ◽  
Double Layer ◽  
Electric Double Layer ◽  
Activated Carbons ◽  
Equivalent Series Resistance ◽  
Morphological Effect ◽  
Double Layer Capacitor ◽  
Slit Pore ◽  
Powder Type

Activated milled mesophase carbon fibers (AC-mMPCF, MP-series) show a higher specific capacitance in spite of a smaller specific surface area than those of powder-type activated carbons (AC-series). This phenomenon can be interpreted to mean that it is difficult to predict the capacitance of an electric double-layer capacitor (EDLC) knowing just the surface area and the pore size. More information is needed about other inherent characteristics of the samples, for example, the equivalent series resistance (ESR), shape of the pores, etc. We investigate here other characteristics of the samples. Consequently, it was deduced that the MP-series of EDLCs have a slit pore shape, which affects the accessibility of the electrolyte ion onto the electrode surface. Moreover, the MP-series of materials have suitable ESR values, and these material properties themselves should be considered as factors that affects the deterioration of the specific capacitance of EDLCs.

Preparation of Orange Peel Based Activated Carbons as Cathodes in Lithium Ion Capacitors

2014 ◽  
Vol 896 ◽  
pp. 95-99 ◽  
Author(s):  
Arenst Andreas Arie ◽  
Hans Kristianto ◽  
Ignatius Suharto ◽  
Martin Halim ◽  
Joong Kee Lee
Keyword(s):  
Activated Carbon ◽  
Activated Carbons ◽  
Morphological Characteristics ◽  
Reference Electrode ◽  
Lithium Ion ◽  
Orange Peel ◽  
Electrochemical Measurement ◽  
Electrochemical Characteristics ◽  
Mass Ratio ◽  
Half Cell

In this work, activated carbon was prepared from Indonesian local orange peel using ZnCl2 activation method at various chemical ratios. The structural and morphological characteristics of orange peel based activated carbons were investigated using scanning electron microscope (SEM), Brunaeuer-Emmett-Teller surface analyzer. The highest surface area was estimated as 1200 m2g-1, obtained by the mass ratio of 1:2 (biomass : ZnCl2). The obtained carbon samples were then tested as cathodes in Lithium Ion Capacitors. Electrochemical measurement was examined by half cell configuration, using 1 M LiPF6 in EC/EMC/DMC solution (1:1:1 v/v) as electrolyte and Li metal as reference electrode. From cyclic voltammetry (CV) test, it was shown that orange peel based activated carbon demonstrated a stable electrochemical characteristics, with specific capacitance of 56 Fg-1 measured at scan rate of 1 mVs-1 under cut-off voltages between 2.5 and 4 V.

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