Fine assembly of TiO2 on the surface of Si particles leading to enhanced dielectric performance of PVDF composites

With the wide applications of polymer dielectrics in electronic devices and power supply systems, it is of great importance to explore polymeric composites with simultaneously high dielectric permittivity ( ε ) along with low loss ( tan δ ), and large breakdown strength ( E b ). To concurrently achieve these superior qualities in silicon (Si)/poly(vinylidene fluoride) (PVDF), in this study, a sol-gel method was used to decorate raw Si with a layer of titanium oxide (TiO 2 ), which was then incorporated into PVDF to produce a series of Si@TiO 2 /PVDF composites with diverse TiO 2 shell thicknesses. The findings demonstrate that compared with pristine Si/PVDF both loss and leakage conductivity of Si@TiO 2 /PVDF are markedly decreased by the TiO 2 shell, which enhances the interfacial compatibility between Si and PVDF, and blocks the creation of conductive network from virgin Si particles, inhibiting the long-range migration of carriers. Furthermore, the TiO 2 interlayer not only induces traps and increases the energy barrier height for trapped charges to de-trap, but also mitigates the intense interfacial dielectric mismatch subsequently lifting the E b . The theoretic fitting results via Havriliak-Negami equation demonstrate the TiO 2 shell’ suppression on charge migration and reveal the underlying polarization mechanism. Fine assembly of TiO 2 with desirable thickness onto Si realizes effective regulation of over dielectric parameters of the composites. The developed Si@TiO 2 /PVDF present concurrently high ε , E b but low loss characteristics, indicating promising potential applications in advanced electronic devices and power systems.