Carbon Nanofibers Derived From Polymer Blends as Electrodes for High Performance Supercapacitors

Nowadays, generation and storage of energy is vital in our life. Supercapacitors as one the energy storage devices are safe and can store high amount of energy and deliver it in a fast manner. Also, they can be used in a wide range of temperatures and show a high cyclability, which make them proper candidates for broad range of applications. However, compared to other common energy storage systems such as batteries, their energy density is low. Carbon materials are known as the most common materials for making electrodes for supercapacitors. To achieve supercapacitors with high energy density it is important to use the right materials as electrodes with proper morphologies. Two main energy storage mechanisms include electric double layer capacitance which energy is stored electrostatically, in the interface of electrode and electrolyte and pseudocapacitance, in which fast redox reactions occur at or near surface of electrodes. In double layer capacitors, high surface area and controlled pore size and pore distribution is required hence, choice of carbon precursors to obtain these properties is essential. Chapter 1 gives basic information about energy storage systems and mechanisms involved in supercapacitors. Also, carbon nanofibers as one of the popular materials for making electrodes are introduced and how they are made is explained. Chapter 2 introduces polymer blends derived from polyacrylonitrile (PAN) and polymethacrylic acid (PMAA) as suitable candidates for making high surface area carbon fibers with high performance. It shows PMAA can be used as a new degrading polymer which, blended with PAN, can result in phase-separation in carbon fibers. Chapter 3 describes fabricating hybrid materials as electrodes for supercapacitors using PANPMAA blend as carbon source and cobalt oxide. It is shown how using PMAA as a chelating polymer can enhance the distribution and uniformity of metal oxide nanoparticles on the carbon fibers which improve the performance of supercapacitors compared to the ones that are made only with PAN.