PVDF-Based Dielectric Composites with High Energy Density by Coloading of C-MWCNTs and CTAB@Sepiolite Nanofibers

Due to the limitation of the intrinsic dielectric constant, the energy storage density of PVDF polymers cannot meet the needs of electronic materials. In this regard, this work focuses toward enhancing the dielectric and energy storage performance of PVDF by preparing PVDF nanocomposites impregnated with sepiolite modified with cetyltrimethylammonium bromide (CTAB@Sep) and carboxylated carbon nanotubes (C-MWCNTs). The results show that CTAB@Sep nanofibers can serve as efficient nucleation agents for γ-PVDF crystals. Furthermore, Sep nanofibers modified with CTAB can significantly promote the dispersion of C-MWCNTs through the electrostatic adsorption effect and then block the conductive path, therefore improving the dielectric and energy storage properties of PVDF-based composites. The dielectric constant of PVDF/CTAB@Sep/C-MWCNTs composites increases by 8 times compared with that of pure PVDF at 1 kHz, while the loss remains at only 0.08. Under an electric field of 110 kV·mm–1, the discharge energy density is 4.03 J·cm–3, and the energy storage efficiency reaches 81.85%. Therefore, this work provides an alternative strategy for preparing high-performance polymer-based energy storage materials under low field strength.