Abstract
Capacitance of typical double layer capacitors is generally limited due to electrochemically available surface area of carbon electrode. Hence, significant increase of capacitance can be done by introducing some faradaic reactions that may occur at electrode/electrolyte interface. This kind of effect is called pseudocapacitance. Different solutions based on electroactive species, such as iodides, bromides or di-hydroxybenzenes seem to be very promising ones in order to increase capacitance. However, generally only one electrode is responsible for high capacitance enhancement. In case of iodides, bromides, di-hydroxybenzenes operating range of potential for faradaic reactions is quite narrow (0.1-0.4V) being connected with positive electrode. Unfortunately electrode with smaller capacitance will affect a total capacitor performance. A few examples of pseudocapacitive phenomena originated from electroactive species present in electrolyte will be shown. They can serve as great source of pseudocapacitance and may significantly enhance total capacitance of the system.