Dielectric Properties Modulation of Zn Particles/ PVDF Composites via Core@Double‐Shell Structured Interface Engineering

ABSTRACT Polymer composites integrating large permittivity ( ε ), low dielectric loss ( tanδ ) and exceptional breakdown strength ( E b ) are desirable for advanced electrical power systems. To achieve superior dielectric properties in zinc (Zn)/poly (vinylidene fluoride, PVDF), the zinc carbonate (ZnCH)@silica (SiO 2 ) double‐shell was coated on raw Zn particles via a sol–gel method, and the Zn@ZnCH@SiO 2 were incorporated into PVDF to investigate the double‐interlayer' effect on morphology and dielectric properties of PVDF composites. The results confirm that in comparison to neat Zn/PVDF, the presence of ZnCH@SiO 2 enhances interfacial compatibility between Zn and PVDF, and diminishes interfacial defects, thereby reducing tanδ and electrical conductivity in the composites. Additionally, the moderate‐ ε SiO 2 shell increases the composite's E b by lessening dielectric interfacial mismatch and introducing deep charge‐trapping sites, which inhibit carrier mobility, alleviate electric field distortion, and suppress electrical tree propagation. For instance, the prepared 50 wt% Zn@ZnCH@SiO 2 /PVDF exhibits an enhanced E b and suppressed tanδ of 15.97 kV/mm and 0.02, respectively, compared to 11.63 kV/mm and 0.04 for raw Zn/PVDF. Theoretical fitting and simulations reveal the underlying polarization and modulated charge transport mechanisms of the composites by the ZnCH@SiO 2 . This core@double‐shell structured composites with concurrently enhanced E b and low loss, showcase broad applications in electrical power systems.