Enhancing dielectric properties and energy storage performance of polyvinylidene fluoride composite by surface-modified AgNbO3 nanoparticles

The introduction of antiferroelectric filler AgNbO₃ into the polyvinylidene fluoride (PVDF) polymer matrix enhances its energy storage properties of PVDF. However, AgNbO₃ and PVDF matrix are incompatible due to their distinct physical and chemical properties, resulting in poor compatibility between the two phases. Surface modification enhances the large difference in physical and chemical properties between the filler and the polymer matrix, and improves the compatibility between the two phases. Silane coupling agents (KH550, KH560), dopamine (DA), and grafted poly(methyl methacrylate) (PMMA) were used to modify the surface of AgNbO₃ particles, and the effects of different surface modification methods on the energy storage performance of the composites were studied. The PVDF matrix was introduced with 0.3 wt% AgNbO₃ particle filler. The results showed that the amino group in KH550 had the strongest binding with PVDF. The ester group in PMMA has a strong binding with PVDF. The epoxy group in KH560 has a weak binding with PVDF, while the amino group in DA has the worst binding with PVDF. The compatibility of the two phases in AgNbO₃@KH550/PVDF composites is the best, and the charge distribution on the surface of the filler is uniform. Under an electric field of 350 kV/mm, the energy storage density is 8.48 J/cm³.