Polymer nanodielectrics: Current accomplishments and future challenges for electric energy storage

Abstract

In response to the need for high energy density and low-loss film capacitors in various electrical and power applications, polymer nanocomposite dielectrics or nanodielectrics have attracted substantial attention in recent years. The idea is to combine the high dielectric constant property from inorganic nanoparticles and the high breakdown strength and low-loss properties from the polymer matrices. Both theoretical and experimental studies have carried out to testify this idea. In this chapter, we review both theoretical and experimental achievements and fundamental understanding on this topic. In particular, we focus on the dielectric loss mechanisms in polymer nanodielectrics. It is found that high permittivity contrast between the nanofillers and the polymer matrices tends to decrease the dielectric breakdown strength because of nonuniform electric field distribution. High conductivity contrast between ceramic nanofillers and the polymer matrix will induce internal electronic conduction loss. For polymer/metallic nanoparticle dielectrics, field electron emission from metallic nanoparticles under a high field tends to increase the electronic conduction and thus decrease the dielectric breakdown strength. In the future, research should focus on mitigating these dielectric loss mechanisms in order to achieve viable polymer nanodielectrics for film capacitor applications.