Research progress and prospect of polymer dielectrics

With the increasing demand for energy, how to store and release energy efficiently and stably has become an urgent research topic. Polymer dielectrics have become a kind of ideal dielectric materials in electrostatic capacitors for energy storage due to their advantages of light weight, easy fabrication, low cost, and high breakdown strength. It has a wide application prospect in smart power grids, new energy vehicles, pulse power weapons, electromagnetic guns, and lasers. However, existing polymer dielectrics cannot simultaneously possess the characteristics of high energy density, high breakdown field intensity, high charge and discharge efficiency, and low dielectric loss, thus limiting the development of compact, efficient, and reliable electronic power technology. In addition, the inherent thermal/field charge injection, excitation, and transport phenomena of polymer dielectrics make the resistivity and dielectric energy storage properties of polymer dielectrics decrease sharply under the combined action of high temperature and high electric field. In order to optimize the energy storage performance of polymer dielectrics (including room temperature and high temperature dielectrics), it has been obtained excellent dielectric breakdown strength, energy storage density, energy storage charge, and discharge efficiency from polymer nanocomposites, polymer/small molecule composites, polymer/polymer blends, new synthetic polymers, multilayer polymers, and other material systems. Based on these material systems, this review summarizes and compares these material systems, points out their advantages and disadvantages including the key problems, and puts forward suggestions for the future research.