Phase-Field Modeling to Investigate the Influence of Nano-Filler Properties on Composite Breakdown Strength and Discharge Energy Density

Abstract

Composite materials have wide range of energy storage applications where high energy density is desirable. Inclusion of nano-fillers with low electrical conductivity in the polymers have been associated with the improvement in breakdown strength and hence the discharge energy density. A phase-field model is developed to investigate the influence of nano-filler properties, shape and volume fraction on the breakdown phase evolution, breakdown strength and discharge energy density. The model is validated with the experimental results from literature. The results reveal that the inclusion of nano-filler (nano-sheets) with lower electrical conductivity as compared to polymer, result in the increase of breakdown strength. The results also show that nano-fillers with high dielectric constant would result in high discharge energy density. This increase in discharge energy density comes at the expense of decrease in breakdown strength. This work reports strategies on choosing suitable nano-filler material (and shape) for specific polymer material.