Optimizing dielectric attributes of NiO/P(VDF–HFP) composite films through filling fine α-Al2O3 particles

Abstract

Dielectric composites with high dielectric constant, minimal dielectric loss and low conductivity can well serve for energy storage capacitors. High dielectric loss is not favorable due to large energy waste. Here, to improve dielectric constant of poly(vinylidene fluoride–hexafluoropropylene) by electric percolation, semiconducting NiO filler was added to form composites. However, high leakage current from interfaces can lead to high dielectric loss. Doping insulating α-Al₂O₃ particles with stable structure, low chemical activity and high modulus into above binary composites can reduce dielectric loss. By changing NiO dose, dielectric constant was well tailored. Dose of α-Al₂O₃ was left unchanged. Dielectric loss, conductivity and dielectric constant of composites were measured. By the same NiO loading, dielectric loss, conductivity and dielectric constant in ternary composites can be reduced, compared with binary composites. The optimal ternary composite should contain 35 wt% NiO and 4 wt% α-Al₂O₃. Optimized dielectric traits of this composite can be reflected by dielectric constant of ~ 64 and dielectric loss of ~ 0.27 under 100 Hz electric field.