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

The coupling relationship between dielectric constant (epsilon) 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 epsilon and BDS by optimizing filler composition and morphology. Results showed that glass fibers promoted the alpha to gamma phase transition in PVDF, enhancing both epsilon and BDS over a broad filler content range (0 similar to 6 vol.%). Specifically, epsilon increased by up to 105%, and BDS reached a maximum of 2620 kV/mm. In contrast, KNN particles rapidly increased epsilon but reduced the decoupling degree due to the quick alpha to beta 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.