Comparative Study of Carbon and Conducting Polymer-Based Electrochemical Capacitors Utilizing Potassium Iodide Redox Electrolyte

摘要

A key challenge for the existing electrochemical charge storage systems, enabling versatile and advanced applications in modern electronics, is related with the improvement of their performance in terms of gravimetric and volumetric energy and power, durability, exploitation costs and safety. However, neither batteries, nor electrochemical capacitors (ECs) technologies do not meet all these demands. Hence, the concept of hybrid capacitor has been developed allowing to combine the main advantages of batteries (high energy) and ECs (high power, long lifespan). Among various strategy of development of such hybrid devices is the incorporation of electrochemically active redox species in addition or instead of a conventional double-layer supporting electrolyte. To date, it has been widely reported that the electron transitions between redox centers present in the electrolyte at various oxidation states result in the increased capacity and energy in comparison to the simple electrical double-layer-type systems. By the fact that these processes are fast and highly reversible, the rate of charging/discharging remains on a level expected for high power systems. In this respect, it is important to refer to works describing electrocatalytic properties of certain systems (Pt, PEDOT, nanostructured carbons) toward electron transfers within the iodine/iodide redox couple with respect to dye sensitized solar cell applications.