Multi-layered boron nitride/polyimide high-temperature capacitor dielectric film

Polymer dielectric is the key material for film capacitor. With the development of advanced electronics and power systems, higher requirements are put forward for the temperature resistance of film capacitors (>150 °C). Unfortunately, common high-temperature polymers cannot be practically used due to their high conduction loss under high temperature and high electric fields. Herein, high-temperature dielectric polymer nanocomposites composed of polyimide (PI) and boron nitride nanosheets (BNNS) are presented. By designing an alternating multilayer structure of PI and BNNS, the conduction loss of nanocomposites is effectively reduced. At 150 °C, the discharge energy density of the nanocomposite containing four BNNS layers is 3.98 J/cm 3 , which is 530% higher than that of PI. Simulation and experimental results show that the alternating multilayered structure can reduce conduction loss and leakage current density more effectively comparing with conventional blended polymer-based composites with randomly distributed fillers. This work provides a feasible idea for the scalable design of high-temperature capacitor dielectrics. • Polymer-based dielectric films with the alternating multilayer structure. • Alternating multilayer structure maximizes the advantages of filler's 2D nanosheet morphology. • Alternating multilayer structure is better than random in suppressing current density which is proved by the finite element method. • The influencing factors of alternating multilayer structure are discussed by the finite element method.