The interfacial surface of an electrode for a supercapacitor as a factor affecting the capacitance and energy density (original) (raw)
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International Journal of Power Electronics and Drive System (IJPEDS), 2018
Activated carbon monoliths (ACMs) for electrochemical double layer capacitor (EDLC) electrode with average pore diameters in the meso-and micropore regions were successfully produced from biomass material. ACM synthesis uses chemical activation with KOH and ZnCl2 activating agents. The carbon and activating agent mass ratios were 1:1, 1:3, 1:5 and 1:7. Both activating materials produced an ACM with an average pore diameter of 3.2 nm. The specific capacitance, specific surface area, energy and power were as high as 63 F g-1 , 650 m 2 g-1 , and 0.23 Whkg-1 for KOH and 73 F g-1 , and 522 m 2 g-1 , and 19 W kg-1 for ZnCl2 activating agents, respectively. For comparison, we also studied the physical and electrochemical properties of ACM with an average pore size in the micropore range from the same raw material.
Electrochimica Acta, 2012
In the present study, we report the microstructural characterization and the electrochemical performance of six activated carbons with varied textural properties. Activated carbons were investigated in terms of specific surface area, pore size distribution, surface chemistry and electrochemical behaviour in acidic, neutral and organic electrolytes. For this purpose, N 2 adsorption isotherms, thermogravimetric analysis (TGA), infrared spectroscopy (FT-IR) and cyclic voltammetry (CV) techniques were used. Electrochemical properties of symmetric supercapacitors using these carbons were investigated by galvanostatic charge-discharge experiments and electrochemical impedance spectroscopy (EIS). Differences in textural properties of the activated carbons were analysed and correlated with their electrochemical behaviour indicating that mesoporous carbons of high surface area are promising materials for high power applications, whereas microporous carbons with higher specific capacitances would be preferred for high energy and medium power applications.
Thermochemically activated carbon as an electrode material for supercapacitors
Nanoscale research letters, 2015
The results of electrochemical studies of nanoporous carbon as electrode material for electrochemical capacitors (EC) are presented in this work. Nanoporous carbon material (NCM) was obtained from the raw materials of plant origin by carbonization and subsequent activation in potassium hydroxide. It is established that there is an optimal ratio of 1:1 between content of KOH and carbon material at chemical activation, while the maximum specific capacity of NCM is 180 F/g. An equivalent electrical circuit, which allows modeling of the impedance spectra in the frequency range of 10(-2) to 10(5) Hz, is proposed, and a physical interpretation of each element of the electrical circuit is presented.
Activated carbon for supercapacitor electrodes with an aqueous electrolyte
High Temperature, 2015
Activated carbons on the basis of wood are obtained; the carbons are characterized by the optimal characteristics necessary to apply in supercapacitors with a sulfuric acid based electrolyte. The properties of activated carbon including detailed study of the porous structure by the limited evaporation technique, as well as their electrochemical parameters in the supercapacitor structure, are investigated comprehensively. For material synthesis, correlations between the regime factors, the porous structure, and the functional charac teristics of the supercapacitors on that basis are found. Suppositions concerning the peculiarities of formation of the porous structure of activated carbons obtained by the thermochemical synthesis method with use of an alkali as the activator, as well as the influence of the synthesis parameters on the electrochemical character istics of the supercapacitors, are proposed.
Influence of electrode preparation on the electrochemical behaviour of carbon-based supercapacitors
This work investigates the influence of electrode preparation on the electrochemical behaviour of carbon-based supercapacitors. Studies were performed using the same activated carbon and polymer polyvynilidene fluoride (PVDF) in the same proportions (10 wt.% PVDF). Only the way in which these components were mixed was modified. The procedure for mixing the activated carbon and the polymer has a significant influence on the electrochemical behaviour of the electrode used in a supercapacitor, as this determines the surface area accessible to the electrolyte. The mixing procedure can be selected in order to ensure optimum performance of the electrode. The use of N-methyl-2-pyrrolidone (NMP) in the mixing procedure, the most common method reported in the literature, blocks a significant part of the porosity of the activated carbon, causing a decrease in capacitance. The addition of the polymer using one of the other methods studied reduces the accessible surface area to a lesser extent,...
Characterisation of activated nanoporous carbon for supercapacitor electrode materials
Carbon, 2007
Commercial nanoporous carbon RP-20 was activated with water vapor in the temperature range from 950°C to 1150°C. The XRD analysis was carried out on nanoporous carbon powder samples to investigate the structural changes (graphitisation) in modified carbon that occurred at activation temperatures T P 1150°C. The first-order Raman spectra showed the absorption peak at 1582 cm À1 and the disorder (D) peak at 1350 cm À1 . The low-temperature N 2 adsorption experiments were performed at À196°C and a specific surface area up to 2240 m 2 g À1 for carbon activated at T = 1050°C was measured. The cell capacitance for two electrode activated nanoporous carbon system advanced up to 60 F g À1 giving the specific capacitance 240FgAˋ1tooneelectrodenanoporouscarbonj1.2M(C2H5)3CH3NBF4+acetonitrilesolutioninterface.Averywideregionofidealpolarisabilityfortwoelectrodesystem(240 F g À1 to one electrode nanoporous carbon j1.2 M (C 2 H 5 ) 3 CH 3 NBF 4 + acetonitrile solution interface. A very wide region of ideal polarisability for two electrode system (240FgAˋ1tooneelectrodenanoporouscarbonj1.2M(C2H5)3CH3NBF4+acetonitrilesolutioninterface.Averywideregionofidealpolarisabilityfortwoelectrodesystem(3.2 V) was achieved. The low frequency limiting specific capacitance very weakly increases with the rise of specific area explained by the mass transfer limitations in the nanoporous carbon electrodes. The electrochemical characteristics obtained show that some of these materials under discussion can be used for compilation of high energy density and power density non-aqueous electrolyte supercapacitors with higher power densities than aqueous supercapacitors.
Journal of Solid State Electrochemistry, 2014
r o l y t e o f s o d i u m bis(trifluoromethanesulfonyl)imide (NaTFSI)-polyethylene oxide (PEO) in an organic solvent mixture has been prepared and examined for supercapacitor applications by using activated carbon electrodes. The solvent was a mixture of propylene carbonate, dimethyl carbonate, and ethylene carbonate at equal molar ratio, and also, a propylene carbonate-based gel was used for a comparison. The polymer-salt interaction was viewed by infrared spectral study. The cells have been characterized in a two-electrode type using linear sweep voltammetry, cyclic voltammetry, galvanostatic cycling, and impedance techniques at 22°C. The voltammograms evidence symmetry and reversibility of the cells. The ternary gel has shown better electrochemical performances. Moreover, the cell operative potential window was found to be stable at 2.5 V with high specific capacitance and also a good efficiency at low charge rate. The typical obtained specific capacitance, real power, and energy density values are 24 F g −1 , 0.52 kW kg −1 , and 18.7 Wh kg −1 , respectively, which may be viewable for a compact capacitor.
Microporous and Mesoporous Materials, 2016
Carbon based-supercapacitors are widely used in numerous applications but the knowledge of the specific role of carbon features in their performance is still insufficient. The main aim of this work is to warn readers that the current interpretation of the device operation, mostly based on powdered carbon properties, may be misleading in certain cases and should be complemented with the physicochemical characterization of the corresponding electrodes. Ordered mesoporous carbons highly enriched in surface functionalities were prepared by carbonization of 3aminobenzoic acid into SBA-15 template. These carbons achieved a specific capacitance as high as 220 F/g in 2M H 2 SO 4 aqueous electrolyte. The pseudocapacitance contribution ranged between 35 and 70% of the overall capacitance. It was shown that the structural and textural changes underwent by these advanced carbons during their processing in form of electrodes prevented the full exploitation of their outstanding properties for high-power applications. This makes a difference regarding conventional, disordered activated carbons, which virtually preserve their structure during electrode preparation.
Electrochimica Acta, 2012
Electrochemical properties of EDLC (double electric layer capacitors), which show how much energy can be accumulated in the device and the power that can be expended, depend on many factors, including the ones connected with the carbon material of electrodes. These are: a usable surface of the material, porosity distribution-mutual participation of micro-and mezoporosity as well as chemical preparation of the surface and the features resulting from these aspects such as the ability to agglomerate, the level of wettability by the electrolyte and conductivity of the solid phase. The purpose of the discussed research was to determine the influence of the aforementioned factors on electrochemical properties of EDLC. To achieve this goal, a series of carbon materials with various structures and changed surface properties was produced. The properties were modified by changing the production parameters of the electrode material using the method of carbon aerogels and applying the following additions: surfactants at the stage of the polymer precursor production and MWCNT (multi wall carbon nanotubes) at the stage of preparing the electrode for the examinations. The produced electrodes of EDLC were examined in the supercapacitor models using chosen water and organic electrolytes.