Karim, Alamgir2023-01-11August 2022022-08-09https://hdl.handle.net/10657/13308Improving the present technology's energy storage capacity and efficiency is crucial for society's sustainable development and progress. The different forms of energy storage devices include fuel cells, batteries, supercapacitors, and electrostatic capacitors. Batteries and fuel cells have high energy density but low power density. Capacitors have high power density but low energy density. If the energy density of capacitors increases, they will be suitable energy storage devices with better performance and high efficiency. Also, capacitors are more compact than batteries and fuel cells for unit energy density. Polymer dielectrics are suitable for pulsed power applications due to their high breakdown strength, low cost, low loss, flexibility, and good processability. The energy density of the capacitor can be increased by enhancing its breakdown strength and dielectric permittivity. The energy storage capacity of dielectrics has a quadratic dependence on breakdown strength. This study used two strategies to increase polymer dielectric breakdown strength and permittivity. We studied the effect of filler concentration in nanocomposite dielectrics in enhancing dielectric permittivity without compromising its breakdown strength. Polymer-Grafted-Nanoparticles have performed much better than Polymer-Nanoparticle blend films. PGNPs have shown an increase of 40% in breakdown strength due to the creation of well-defined barriers which delay the breakdown propagation. Also, the fillers contribute to the enhancement in permittivity, which is 3.5 times higher than pure PMMA films. Another method employed was free volume reduction of polymers by reducing the chain end density. We used Polystyrene (PS) and Cyclic polystyrene (cPS) for the study. cPS has shown a 50% increase in breakdown strength and almost 80% increase in discharge energy density compared to PS. Also, thermal stability analysis of PS and cPS films with nanopatterned waves shows that cPS films are more thermally stable than PS films. These strategies to enhance the breakdown strength and dielectric permittivity, along with the novel insights into the dielectric failure, will pave the way for the design of high energy and power density dielectric capacitors for fulfilling the energy demand of the next generation.application/pdfengThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).NanocompositesThin filmsEnergy storageCapacitorsDielectric polymers2023-01-11Thesisborn digital