High-temperature dielectric polymers have broad application potential in high-temperature electrostatic energy storage film capacitor. However

the low dielectric constant and energy density of conventional high-temperature polymer dielectrics limit their application in high temperature environment. In order to improve the dielectric and energy st

orage performances of high-temperature dielectric materials at high temperatures further

all-organic PVDF/PI composite dielectric films are prepared with polyvinylidene fluoride (PVDF) as filler and polyimide (PI) as matrix through in-situ polymerization method in this study. The effects of ferroelectric PVDF phase on the microstructures

morphologies

dielectric properties

energy storage properties

and thermal properties of PI are systematically studied. The results show that PVDF fillers have good compatibility and dispersion in PI matrix. The introduction of PVDF reduces the breakdown strength of the PI-based composite film to a certain extent

but can significantly improve the dielectric constant and discharge energy density of the composite films. PVDF/PI composite films with 30 wt.% PVDF exhibit a discharged energy density of 1.89 J/cm

3

and a charge-discharge efficiency of 92.4% at room temperature and 250 MV/m

and those of 1.13 J/cm

3

and the charge-discharge efficiency of 89.1% at 100℃ and 200 MV/m. In addition

the PVDF/PI composite films possess excellent charge-discharge cycle performance and thermal stability under high temperature and high electric field conditions. This study provides a new design idea for improving the energy storage performance of polymer-based dielectrics in high-temperature environments.