Study the coupling relationship between dielectric constant and breakdown strength in PVDF-based dielectric flexible composites

The coupling relationship between dielectric constant (ɛ) and breakdown strength (BDS) in poly(vinylidene fluoride) (PVDF)-based dielectric flexible composites was investigated by comparing the effects of one-dimensional (1D) glass fibers with moderate dielectric constants and zero-dimensional (0D) (K,Na)NbO3 (KNN) particles with high dielectric constants. The study aimed to enhance the decoupling degree between ɛ and BDS by optimizing filler composition and morphology. Results showed that glass fibers promoted the α to γ phase transition in PVDF, enhancing both ɛ and BDS over a broad filler content range (0 ~ 6 vol.%). Specifically, ɛ increased by up to 105%, and BDS reached a maximum of 2620 kV/mm. In contrast, KNN particles rapidly increased ɛ but reduced the decoupling degree due to the quick α to β phase transformation and strong interfacial polarization. The study concludes that optimizing filler morphology and dielectric properties is crucial for developing PVDF-based composites with high energy storage density. Future work should explore other fillers and composite structures to further enhance the decoupling effect and develop advanced dielectric materials for high-performance applications.