COMPUTATIONAL STUDY OF DIFFERENTIAL CAPACITANCE-DOUBLE LAYER RELATIONSHIP IN A SUPERCAPACITOR

Abstract

Energy crisis is one of the most pressing problems that the world is facing. It involves a number of issues to be addressed in energy sources, transportation, storage, etc. Novel ways of energy storage are being actively explored. Electrical energy is stored by using devices such as batteries, capacitors, supercapacitors, etc. Supercapacitor seems to be a promising technology for this purpose. Traditionally, batteries have high energy densities but low power delivering density. On the other hand, conventional capacitors are capable of delivering high power densities but possess low energy storage density. Supercapacitors are a bridge between the two devices. Of all the types of supercapacitors available, electric double layer capacitors have promising future applications in mobiles, cars, computers, etc. The present thesis aims to gain deeper understanding of the electrical double layer mechanism of energy storage. In order to study the mechanism, two aqueous electrolytes are considered: potassium hydroxide, and sulphuric acid. A computational approach is adopted to calculate the differential capacitance of the supercapacitor under various temperatures. The differential capacitances for the two different electrolytes under the same conditions are found to be characteristically different. An attempt has been made to relate these differential capacitance curves obtained to the structures of electric double layer for explanation. Finally, future scope of work for understanding electric double layer mechanism and enhancing current capability of storing energy in a supercapacitor is discussed.