Dielectric and Energy Storage Performance of Poly(vinylidene fluoride-co- hexafluoropropylene) Thin Film with Coupling Agent
Type of DegreeMaster's Thesis
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Dielectric material is an important element in the industries. It can be used for many applications, including capacitors, transistors and energy storage devices. With the development of technology, dielectrics with high permittivity, high dielectric breakdown strength and high energy storage density are required to increase the performance of electric products. In this study, a polymer-based dielectric, P(VDF-HFP), as the main dielectric material is studied for the influence of coupling/additive agent and thermal treatment on its properties. It is found that both the permittivity and electrical breakdown field can be improved by the coupling agent and thermal treatment, which is explained using the free volume theory and the microstructure. Thermal treatment and additive agent were studied to improve the dielectric properties and energy density of P(VDF-HFP) thin film in this study. The P(VDF-HFP) thin film was fabricated by solution casting with the thickness about 12um. First, different quench temperatures were applied to the film (150°C~180°C). Then, based on the result of the quench experiment, analyzing the change of the dielectric properties by adding silane as an additive agent (0.2wt% ~1.0wt%). Permittivity, dielectric loss, polarization-electric field (P-E) loop and differential scanning calorimetry (DSC) were used to analyze the sample in this study. For the thermal treatment process, it is concluded that 160°C is the best quench temperature since it results in the highest electric breakdown field and permittivity. For example, the dielectric permittivity is increased about 7% and corresponding energy density increases about 20%. Moreover, the permittivity can be further improved about 3.5% and energy density about 19% after adding silane as a coupling agent. Overall, P(VDF-HFP) thin film can improve 9% of permittivity and 42% of energy density after quenching and adding silane.