Electrochemical capacitors based on highly porous carbons prepared by KOH activation

Kierzek, Krzysztof; Frąckowiak, Elżbieta; Lota, Grzegorz; Gryglewicz, Grażyna; Machnikowski, J.

doi:10.1016/j.electacta.2003.08.026

Cited by 408 publications

(231 citation statements)

References 11 publications

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“…However, attempts to find a clear linear relationship between the gravimetric capacitance and surface areas, in particular S BET , have not been conclusive, as the specific capacitance (F m −2 ), may vary strongly from carbon to carbon [5,36,37]. This has been explained by different authors, who suggest that a large fraction of the carbon surface area is not accessible to the electrolyte ions and, consequently, the experimental capacitance (F g −1 ) of these materials depends strongly on the pore size distribution and the connectivity between the pores [5,[23][24][25]31,32,36]. In this context, many studies have been carried out to determine the optimum pore size distribution for the diffusion of the solvated ions within the carbon framework.…”

Section: Specific Capacitance At Low Current Densitymentioning

confidence: 99%

Performance of templated mesoporous carbons in supercapacitors

Sevilla

Álvarez

Centeno

et al. 2007

Electrochimica Acta

118

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By analogy with other types of carbons, templated mesoporous carbons (TMCs) can be used as supercapacitors. Their contribution arises essentially from the double layer capacity formed on their surface, which corresponds to 0.14 F m −2 in aqueous electrolytes such as H 2 SO 4 and KOH and 0.06 F m −2 for the aprotic medium (C 2 H 5 ) 4 NBF 4 in CH 3 CN. In the case of a series of 27 TMCs, it appears that the effective surface area determined by independent techniques can be as high as 1500-1600 m 2 g −1 , and therefore exceeds the value obtained for many activated carbons (typically 900-1300 m 2 g −1 ). On the other hand, the relatively low amount of surface oxygen in the present TMCs, as opposed to activated carbons, reduces the contribution of pseudo-capacitance effects and limits the gravimetric capacitance to 200-220 F g −1 for aqueous electrolytes. In the case of non-aqueous electrolyte, it rarely exceeds 100 F g −1 .It is also shown that the average mesopore diameter of these TMCs does not improve significantly the ionic mobility compared with typical activated carbons of pore-widths above 1.0-1.3 nm.This study suggests that activated carbons remain the more promising candidates for supercapacitors with high performances.

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Section: Specific Capacitance At Low Current Densitymentioning

confidence: 99%

Performance of templated mesoporous carbons in supercapacitors

Sevilla

Álvarez

Centeno

et al. 2007

Electrochimica Acta

118

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“…Because the main energy storage mechanism in EDLCs arises from the electrostatic accumulation of electrolyte ions on the electrode surface, the capacitance of EDLCs typically increases with the specific surface area of the ACs [4,5]. Highly porous materials with specific surface areas exceeding 3000 m 2 g -1 have been obtained by KOH activation of carbons [6][7][8][9], but commercially available ACs typically exhibit a more modest porosity of approximately 1000-1500 m 2 g -1 .…”

Section: Introductionmentioning

confidence: 99%

Nitrogen-containing chitosan-based carbon as an electrode material for high-performance supercapacitors

et al. 2016

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Nitrogen-containing activated carbons were prepared from chitosan, a widely available and inexpensive biopolysaccharide, by a simple procedure and tested as electrode material in supercapacitors. The physical activation of chitosan chars with CO 2 led to carbons with a very high nitrogen content (up to 5.4 wt%) and moderate surface areas (1000-1100 m 2 g -1 ). Only chitosan-based activated carbons with a similar microporous structure were considered in this study to evaluate the effect of the nitrogen content and distribution on their electrochemical performance. The N-containing activated carbons were tested in two-and three-electrode supercapacitors using an aqueous electrolyte (1 M H 2 SO 4 ), and they exhibited superior surface capacitance (19.5 lF cm -2 ) and pseudocapacitance compared to a commercial activated carbon with a negligible nitrogen content and similar microporosity. The low oxygen content and the presence of stable quaternary nitrogen improved the charge propagation on the chitosan-based carbons, which was confirmed by the high capacity retention of 83 %. The chitosan-based carbons exhibited excellent cyclic stability and maintained 100 % of their capacitance after 5000 charge/discharge cycles at a current density of 1 A g -1 . These results demonstrate the suitability of chitosan-based carbons for application in energy storage systems.Electronic supplementary material The online version of this article

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“…In the light of nowadays development, a gradual increase of the used electronic equipment is observed, which request the small device able to store enormous energy. The electrochemical double layer capacitors are one of the intensively studied solutions to this problem [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Persulfate treatment as a method of modifying carbon electrode material for aqueous electrochemical capacitors

Kopczyński

Pęziak-Kowalska

Lota

et al. 2016

J Solid State Electrochem

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The activated carbon was modified by the wet method with a solution of ammonium persulfate at room temperature with different times. Kinetics studies showed that the modification took place mostly during the first 60 min of the process. The physicochemical properties of the obtained carbon were evaluated by thermogravimetric studies, Raman and FTIR spectroscopy, elementary and BET analyses. Furthermore, the fabricated material was applied in symmetric capacitors operated on the three aqueous electrolytes (1 M H 2 SO 4 , 6 M KOH and 1 M Na 2 SO 4 ). Mild conditions of the modification process are optimal to obtain electroactive groups on the carbon surface, which make this material useful in a supercapacitor application. In our studies, we noticed that this type of functional groups mainly appears on the surface of the activated carbon, in the first oxidation stage. With prolonged oxidation, they may transform into undesirable groups. The results show that this kind of modification improves the capacity of all the tested supercapacitors. It was connected mainly with an increase of the carbon material's wettability and in the case of capacitor operated in acid and base electrolytes due to a redox reaction of oxygen functional groups.

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Electrochemical capacitors based on highly porous carbons prepared by KOH activation

Cited by 408 publications

References 11 publications

Performance of templated mesoporous carbons in supercapacitors

Performance of templated mesoporous carbons in supercapacitors

Nitrogen-containing chitosan-based carbon as an electrode material for high-performance supercapacitors

Persulfate treatment as a method of modifying carbon electrode material for aqueous electrochemical capacitors

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