The Preparation of PI/PVDF Organic Blend Films with Improved Energy Storage Performances

In recent years, there has been a growing demand for energy storage in high-temperature applications, such as electric vehicles inverter and distributed new energy generation. Dielectric energy storage materials with good energy storage performances at high temperatures (150~200° C) have become a hot topic in current research. In this work, polyimide (PI) was used as the matrix because of its high thermostability and dielectric stability. The solution blending method was employed to blend PI with polyvinylidene fluoride (PVDF), which has a high relative permittivity. By adjusting the solid content of the blending solution, a well-dispersed organic blend solution was obtained. Finally, the PI/PVDF blend films were prepared through thermal imidization in vacuum environment. The test results indicate that the ‘sea-island’ structure is created after the introduction of PVDF into the PI matrix. Furthermore, the high dielectric performance of PVDF improves the relative permittivity of the PI/PVDF blend film. At the same time, more deep trap centers were incorporated into the PI, enhancing the breakdown strength of the PI/PVDF blend film. Consequently, the energy storage density and the charge-discharge efficiency were improved. This work lays a solid foundation for future research on energy storage at high temperatures, which is benefit from the excellent thermal stability of PI/PVDF blend films.