UCLA

In recent years, climate change has been an alarming issue and there is a pressing need for a greener, cost-effective, durable high-density energy storage system. This thesis investigates an electrostatic energy storage method using flexible roll-to-roll capacitors at very high voltages (5 kV – 10 kV) and investigates PVDF as a potential dielectric material for the capacitors. PVDF is chosen as a material due to its high dielectric constant, high dielectric breakdown strength, and low flexural modulus (high flexibility). Short-time stepped voltage ramp dielectric breakdown and the time-dependent dielectric breakdown for 75 μm PVDF films have been studied to understand the DC dielectric breakdown strength for the application of PVDF dielectrics under high voltage stress for long periods of time. It has been shown that PVDF can withstand up to 10 kV and does not break down instantaneously. The failure rate dependence on electric field and temperature has been shown along with the prediction of the lifetime of PVDF dielectrics for a period of 10 years (100000 hours). It was found that a capacitor voltage range of 4000 - 9200 V for a 100 μm PVDF dielectric film would lead to a time to failure of 10 years. The acceleration parameters and activation energy of PVDF films have also been shown to demonstrate the temperature dependence on TDDB of PVDF films. This thesis attempts an in-depth understanding of dielectric breakdown mechanisms, proposes, and investigates PVDF as a potential dielectric candidate, and analyzes the TDDB of polymer films using the thermochemical model (E model).