Fabrication and dielectric properties of advanced high permittivity polyaniline/poly(vinylidene fluoride) nanohybrid films with high energy storage density

Abstract

Energy storage capacitors have been the focus of increasing attention due to their advantages such as handiness, high efficiency and environment friendliness. To obtain the dielectric capacitor composites, poly(vinylidene fluoride) (PVDF) and conductive polyaniline (PANI) were selected as the polymer matrix and the filler respectively. The influences of volumetric fraction of PANI (f_PANI), preparation processing and frequency on dielectric properties were studied. The results showed when the f_PANI was up to 0.05 (higher than the percolation threshold f_c = 0.042), the dielectric permittivity of the hybrid film was as high as 385 (at 10³ Hz), the breakdown strength was 60 MV m⁻¹, and the energy storage density was 6.1 J cm⁻³, which was three times higher than that of neat PVDF. Moreover, the dielectric permittivity was frequency-independent even for the hybrid films with the f_PANI approaching the f_c. SEM and XRD revealed that the PANI can be dispersed uniformly in the PVDF matrix, and that the PVDF existed mainly as typical β-crystal PVDF for our preparation method. Percolative theory and microcapacitor modeling were employed to explain these results. This route was demonstrated to be effective to prepare the high energy density capacitor material used in the wide frequency range.