Electrical double-layer capacitors EDLC

Porous carbons are among the most attractive electrode materials for electric double layer capacitors (EDLC), where the charge accumulation occurs mainly by electrostatic attraction forces at the clcctrode/electrolyte interface [1-3]. Advantages of this class of materials include high surface... 

Endo, M., Takeda, T., Kim, Y.J., Koshiba, K., and Ishii, K. High power electric double layer capacitor (EDLC s) From operating principle to pore size control in advanced activated carbons. Carbon Sci. 1, 2001 117-128. 

In recent years there has been increasing interest in the power capacitors, ultracapacitors or supercapacitors based on electrochemical systems. These include electric double layer capacitor (EDLC) types based on carbon electrodes with suitable electrolyte systems, and electrochemical capacitors with pseudocapacitance [34,35],... 

By using porous carbon materials with a veiy high surface area in both positive and negative electrodes, a large amount of electrical charge was found to be stored, and electric double-layer capacitors (EDLCs) were developed [81,82], The fundamental concept of this capacitor is the formation of electric double-layers on the surface of electrodes, as illustrated in Fig. 28. The total amount of electeic charges aligned in double layers on both electrodes increases by the application of potential difference and it is easily understood to depend on the area of this interface, i.e. the surface area of solid electrodes. 

Typically, a supercapacitor is composed of two electrodes dipped in an electrolyte solution with a suitable separator. It is generally accepted that the energy storage mechanism of supercapacitors can be classified into electrical double layer capacitors (EDLCs) and pseudocapacitors (Fig. 6.1A) (Jost et al., 2014). In EDLCs, the charge storage is based on a reversible ion adsorption from an electrolyte onto electrodes with high specific surface areas to form a double layer structure. The capacitance comes from the pure electrostatic... 

MAIN PROPERTIES OF ELECTRIC DOUBLE-LAYER CAPACITORS (EDLC)... 

The main difference between PsC and electric double-layer capacitor (EDLC) is that there is no overall ion exchange between the electrode and electrolyte in PsCs. That is, the concentration of electrolyte remains constant during the charging and discharge. As pointed out above, EDL capacitance in such systems always coexists with pseudocapacitance. However, the amount of ions participating in the process of EDL formation is much lower than the amount of protons exchanged between the two electrodes. Thus, pseudocapacitance is much higher than EDL capacitance in the same system. 

Electrodes of various types are used in hybrid (asymmetric) supercapacitors (HSCs). For example, one of the electrodes is highly dispersed carbon, that is, a double-layer electrode, and the other electrode is a battery one or one of the electrodes is carbon and the other one is a pseudocapacitor, for example, based on electron-conducting polymer (ECP). The main advantage of HSCs as compared EDLCs is an increase in energy density because of the wider potential window. The main fault of HSCs, meanwhile, as compared to electric double-layer capacitors (EDLCs), is a decrease in cyclability following the limitations posed by the nondouble-layer electrode. 

It is most convenient to use Ragone diagrams for the comparison of the main characteristics of electrochemical devices. Figure 30.1 shows a Ragone diagram for diverse commercial electrochemical devices conventional electrolytic capacitors, electrochemical supercapacitors (ECSCs), batteries, and fuel cells (Pandolfo and Hollenkamp, 2006). One should point out that it is mainly electric double-layer capacitors (EDLCs) of all the available ECSC types that are produced at present. 

This chapter describes the fundamentals of different kinds of electrochemical capacitors (ESs), including electrical double-layer capacitors (EDLCs), pseudocapacitors, and hybrid ESs. This serves as a foundation for understanding ES science... 

Lei, C. H., F. Markoulidis, Z. Ashitaka, and C. Lekakou. 2013. Reduction of porous car-bon/Al contact resistance for an electric double-layer capacitor (EDLC). Electrochimica Acta 92 183-187. 

Pahn et al. [34] employed the CV method to investigate the effect of the concentration of the addition of l-butyl-3-methylimidazolium tetrafluoroborate ([BMIM] [BFJ) in l-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) electrolyte on the electrochemical characteristics for electrical double-layer capacitors (EDLCs). They found the concentration of [BM1M][BF4] has little influence on the... 

Depending on the charge storage mechanism, supercapacitors can be classified into two types electrical double layer capacitors (EDLC) and pseudocapadtors [108]. EDLCs store and release energy based on the accumulation of charges at the interface between a porous electrode, typicalty a carbonaceous material with high surface area, and the electrotyte. In pseudocapadtors, the mechanisms rely on fast and reversible Faradaic redox reactions at the surface and/or in the bulk. 

To increase electrical conductivity of electrospun carbon nanofibers, embedding of MWCNTs was performed in relation to electric double-layer capacitor (EDLC] application. Embedding of 0.8 wt.% MWCNTs led to an increase in the electrical conductivity... 

Electrical double-layer capacitor (EDLC) Electrochemical capacitor (EC) Simulation of supercapacitors Ultracapacitors... 

There has been growing interest in the field of supercapacitors due to their possible applications in medical devices, electrical vehicles, memory protection of computer electronics, and cellular communication devices. Their specific energies are generally greater than those of electrolytic capacitors and their specific power levels are higher than those of batteries. Supercapacitors can be divided into redox supercapacitors and electrical double layer capacitors (EDLCs). The former uses electroactive materials such as insertion-type compounds or conducting polymers as the electrode, while the latter uses carbon or other similar materials as the blocking electrode. 

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