HYBRID ASYMMETRIC SUPERCAPACITORS HSCs

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. 

Electrochemical Power Sources Batteries, Fuel Cells, and Supercapacitors, First Edition. Vladimir S. Bagotsky, Alexander M. Skundin, and Yurij M. Volfkovich 2015 John Wiley Sons, Inc. Published 2015 by John Wiley Sons, Inc. 

A new HSC type containing a negative polarizable electrode based on activated carbon and a positive weakly polarizable electrode based on the known system of PbS04/H2S04/Pb02 has been developed in Inkar CISC and in A.N. Erumkin Institute of Physical Chemistry and Electrochemistry (Russia) (Volfkovich and Shmatko, 2003). 

The electrolyte is in the porous space of the two electrodes and the separator and is absent in the free state. The activated carbon electrodes (ACEs) used were made of ACC Viskumak with S = 1000 m /g. The maximum voltage of discharge 

In practice, the ratio of active materials of both the electrodes was often chosen such that the capacitor should operate in the mode, in which capacitance was determined by the polarizable carbon electrode. Owing to the relative smallness of the volume of electrolyte in HSC, a change in its volume and concentration occurs in the course of charging and discharge. It was found that a 5-20% decrease in the liquid phase volume occurs in the course of charging, and a 15-50% decrease in the concentration of electrolyte is observed in the course of discharge. Herewith, an increase 

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