Double-layer capacitors electrolyte materials

It follows from these data that the (theoretical) specific capacity of the active materials of such a double-layer capacitor may attain 100 F/g. This is many orders of magnitude above the values characterizing other capacitor types (film and electrolytic). For this reason such capacitors have also become known as super- or ultracapacitors. 

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... 

Lewandowski, A. and Galmski, M., General Properties Of Ionic Liquids As Electrolytes For Carbon-based Double Layer Capacitors, New Carbon Based Materials for Electrochemical Energy Storage Systems, Barsukov et al. (Eds), Springer, The Netherlands, 2006, 73-83. 

The selection of the electrolyte material is dependent on the electrode type. In principle, any ionic conductors can be used as the electrolyte material of a double-layer capacitor as long as the current due to the electrochemical reactions (Faradaic current) does not flow in the desired potential region. The electrolyte merely works as an ion source to form a double-layer. 

High safety. One advantage of the double-layer capacitor is that it uses environmentally friendly materials in contrast to the rechargeable batteries using heavy metals. An electrolyte material with high safety and low environmental impact is desired. 

Another method to improve the structural order of CMs is the conversion of the precursors to fibers prior to the pyrolysis step [377]. The precursor polymer may be stretched in addition. Carbon fibers are manufactured in large quantities as reinforcements in composite materials, after Bowen [403] and Fitzer [404]. Surface and bulk activation can be accomplished by anodic oxidation in dilute aqueous electrolytes (cf. Besenhard et al. [405, 406]). But carbon fibers with various degrees of graphitization have also been employed recently in rechargeable batteries [407-411] and in electrochemical double layer capacitors [18, 412-416]. This takes advantage of two fiber specific effects, namely... 

Fig. 38. Symmetrical combinations of positive and negative active materials, PA and NA, in (1) conventional accumulators, (2) swing accumulators and (3) electrochemical double layer capacitors. The relative electrolyte (E) volume is shown schematically. The thick, vertical lines represent the current collector (schematically).

FIGURE 1.3 Schematic diagram for (a) electrostatic capacitor, (b) electric double-layer capacitor, (c) pseudocapacitor, and (d) hybrid capacitor. (Zhong, C. et al. 2015. A review of electrolyte materials and compositions for electrochemical supercapacitors. Chemical Society Reviews 44 7484-7539. Reproduced by permission of The Royal Society of Chemistry.)... 

Vu, A., X. Y. Li, J. Phillips et al. 2013. Three-dimensionally ordered mesoporous (3DOm) carbon materials as electrodes for electrochemical double-layer capacitors with ionic liquid electrolytes. Chemistry of Materials 25 4137-4148. 

Hahn, M., O. Barbieri, F. P. Campana, R. Kotz, and R. Gallay. 2006. Carbon based double layer capacitors with aprotic electrolyte solutions The possible role of inter-calation/insertion processes. Applied Physics A Materials Science Processing 82 633-638. 

Kurig, H., A. Janes, and E. Lust. 2010. Substituted phosphonium cation based electrolytes for nonaqueous electrical double-layer capacitors. Journal of Materials Research 25 1447-1450. 

Pinkert, K., M. Oschatz, L. Borchardt et al. 2014. Role of surface functional groups in ordered mesoporous carbide-derived carbon/ionic liquid electrolyte double-layer capacitor interfaces. ACS Applied Materials Interfaces 6 2922-2928. 

Pandey, G. P., and S. A. Hashmi. 2013. Studies on electrical double layer capacitor with a low-viscosity ionic liquid l-ethyl-3-methylimidazolium tetracyanoborate as electrolyte. Bulletin of Materials Science 36 729-733. 

Fan, L. Q., J. Zhong, J. H. Wu, J. M. Lin, and Y. F. Huang. 2014. Improving the energy density of quasi-solid-state electric double-layer capacitors by introducing redox additives into gel polymer electrolytes. Journal of Materials Chemistry A 2 9011-9014. 

Huang, C. W., C. A. Wu, S. S. Hou, P. L. Kuo, C. T. Hsieh, and H. S. Teng. 2012. Gel electrolyte derived from poly(ethylene glycol) blending poly(acrylonitrile) applicable to roll-to-roll assembly of electric double layer capacitors. Advanced Functional Materials 22 4677-4685. 

Lim, C. S., K. H. Teoh, C. W. Liew, and S. Ramesh. 2014. Capacitive behavior studies on electrical double layer capacitor using poly (vinyl alcohol)-lithium perchlorate based polymer electrolyte incorporated with TiOj. Materials Chemistry and Physics 143 661-667. 

Senthilkumar, S. T., R. K. Selvan, Y. S. Lee, and J. S. Melo. 2013. Electric double layer capacitor and its improved specific capacitance using redox additive electrolyte. Journal of Materials Chemistry A 1 1086-1095. 

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