Adjusting the lattice spacing and sandwich structure design of molybdenum disulfide nanosheets synergistically enhances the electrical properties of polyimide based composites

Abstract Polyimide (PI) based composites have recently attracted much attention due to their very high potential for use as advanced dielectric capacitors. However, in the actual working process, the growth of electrical trees will lead to the premature breakdown of dielectric materials. It is still challenging to improve the inherent low breakdown strength of polymer dielectrics. Herein, the lattice spacing of molybdenum disulfide nanosheets has been expanded by using the hydrothermal method. The single‐layer polyimide/ expanded molybdenum disulfide composites (PI/E‐MoS 2 ), as well as “positive‐sandwich” (PI/P‐E‐MoS 2 ) and “anti‐sandwich” structures (PI/A‐E‐MoS 2 ) composites, were prepared through in‐situ polymerization and multilayer coating processes. The PI/A‐E‐MoS 2 composites simultaneously achieved a comprehensive dielectric performance with a high dielectric constant of 4.47 and an excellent breakdown strength of 198.67 kV/mm. The outer layer of molybdenum disulfide effectively blocks the injection of charge carriers, enhances the interfacial effect, and significantly improves the electrical performance of the composites. Drawing upon experimental analysis, the finite element simulation method is employed to explore the impact of varied interlayer configurations of expanded molybdenum disulfide on the dielectric characteristics of the composites. This work offers a novel design methodology for the creation of high‐insulation composite dielectrics. Highlights Ultra‐large lattice spacing molybdenum disulfide nanosheets have been prepared. Sandwich‐structured PI/P‐E‐MoS 2 and PI/A‐E‐MoS 2 films were successfully prepared. The breakdown behavior of the composites was simulated. The mechanism of breakdown performance of sandwich composites was studied. It provides an approach for designing high‐performance dielectric films.