Enhanced energy storage capability of P(VDF-HFP) nanodielectrics by HfO2 passivation layer: Preparation, performance and simulation

Abstract

Flexible dielectric nanocomposites have shown great potential for electrostatic capacitors due to their excellent energy storage properties. In an effort to eliminate the disadvantages induced by the interfacial polarization of two different components in the nanocomposite, in this work, HfO2@BaTiO3 nanoparticles (HfO2@BT NPs) with core-shell structure were synthesized and used to fabricate poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP))/HfO2@BT nanocomposite films via solution casting method. The passivation HfO2 layer with high resistivity and moderate dielectric permittivity could act as a buffering barrier and alleviate the dielectric mismatch between the BT nanoparticles (BT NPs) and P(VDF-HFP) matrix. The breakdown strength (Eb) and discharged energy density (Ue) of P(VDF-HFP)/HfO2@BT nanocomposites have been substantially enhanced. The nanocomposite filled with 1 wt% HfO2@BT presents a maximum Ue of 10.7 J/cm3 at 450 MV/m, which is 36% and 59% higher than that of the pristine P(VDF-HFP) and nanocomposite filled with the same BT NPs, respectively. Meanwhile, P(VDF-HFP)/HfO2@BT nanocomposites show a charge-discharge efficiency of 72%, which is superior to most of the reported values. The possible mechanism of HfO2 layer on above performance enhancements is proposed based on both experimental analysis and finite element simulation. This work demonstrates that utilizing dielectric fillers with passivation layer might be an effective way to improve the energy storage performance of the flexible dielectric nanodielectrics.