Polymer-based dielectric nanocomposites with high energy density via using natural sepiolite nanofibers

[Display omitted] •Low-cost natural-sepiolite was used to develop large-scale production of high performance dielectrics.•Organophilic-sepiolites nanofibers possessed well dispersion in the PVDF matrix.•The maximal Ue of 7.2 J·cm−3 was achieved in 2.5%-APTES@Sepiolites/PVDF nanocomposites. The preparation of large-aspect-ratio nanofillers is challenging due to the complicated and expensive artificial processing procedures and low yields, obstructing scale-up production of 1D nanofillers/polymer dielectric nanocomposites. In this paper, a kind of natural sepiolite nanofiber was utilized to fabricate scale-up of PVDF-based dielectric nanocomposites. The sepiolite nanofibers were modified by aminopropyltriethoxysilane (denoted as APTES@Sep) and 1H,1H,2H,2H-perfluoroheptadecane trimethysiloxane (denoted as PFDTES@Sep), respectively, before being incorporated into PVDF. The effect of nanfibers loading and modifiers on the dielectric behaivor and energy stroage properties of nanocomposites was investigated. As results, the nanocomposites with 7.5 vol% PFDTES@Sep exhibited highest permittivity of 16.4 at 103 Hz originating from well dispersibility, strong interfacial polarization and orientation polarization. The nanocomposites with 2.5 vol% APTES@Sep displayed maximal discharged energy density of 7.2 J·cm−3 owing to highest breakdown strength. This work provides a simple and cheap strategy for developing high performance flexible dielectric nanocomposites, which is suitable for large-scale preparation.