Purpose/Aim
In recent years, flexible polymer-based film capacitors with extremely high power density, excellent insulation properties, and easy processing have been used in the field of electric vehicles, smart grids, pulse power technology. However, the low energy density and pure thermal stability limit the wide applications of current commercial biaxially oriented polypropylene (BOPP) films. Therefore, ferroelectric polymers with high dielectric constant have been utilized to improve the dielectric and energy storage properties.
Experimental/Modeling methods
In the first step, the P(VDF-HFP) pellet was dissolved in 10 ml DMF solvent. Appropriate amounts of NBR fillers were then added into the above solution with different weight fractions with ultrasonication. A stable suspension was obtained after vigorous magnetic stirring for 24 h at elevated temperature of 50 °C. Next, the solution was then drop onto a smooth glass substrate, and cast into films using a blade. The casted films were dried at 40 °C in the oven for 6 h firstly, then 70 °C for 12 h. Finally, NBR/P(VDF-HFP) films with thermal treatment were obtained after quenching in ice water. The field emission scanning electron microscopy (FE-SEM, Zeiss Merlin) was applied to witness cross-sectional morphologies of all-organic NBR/P(VDF-HFP) films. The dielectric spectra of NBR/P(VDF-HFP) films were acquired through the Precision Impedance Analyzer (Agilent 4294A). The dielectric breakdown strength of composites was measured with a high voltage withstand tester. Unipolar displacement-electric field (D-E) hysteresis loops of all-organic composites were performed using the Premier II ferroelectric test system (Radiant Technologies, Inc.).
Results/discussion
The results showed that when the appropriate content of NBR is added, the NBR/P(VDF-HFP) composite film can effectively improve the dielectric and energy storage properties under high temperature conditions, which makes new progress on the basis of existing research.
Conclusions
In summary, the all-organic composites consisting of NBR fillers and P(VDF-HFP) were prepared to improve high-temperature capacitive energy storage. Film capacitors based on the blended all-organic NBR/P(VDF-HFP) dielectrics may improve the energy density and operating reliability.
 

P(VDF-HFP),dielectric properties,high-energy density,high temperature