Improving the comprehensive energy storage performance of composite materials through the coupling effect of AgNbO3/PVDF nanocomposite

Ceramic-polymer nanocomposites with high energy storage density can achieve excellent energy storage performance and have a wide range of application prospects. Currently, it has been shown that the coupling effects have a great impact on improving the performance of dielectric composites, but increasing the breakdown strength of polymer nanocomposite is still a tremendous challenge to the achievement of high energy density under high voltages. The aim of this paper is to further investigate this problem and obtain AgNbO3/PVDF flexible composites by introducing a small amount of AgNbO3 ultrafine powder prepared by hydrothermal method into poly(vinylidene fluoride) (PVDF). The interfacial coupling effect within this nanocomposite with the coupling effects of nonlinear dielectric materials improves its energy storage capacity and electrical strength resistance. The energy density of the 2 wt% AgNbO3/PVDF composite film was raised to 16.5 J/cm(3) at the electric breakdown strength of 391.7 MV/m, and its energy storage capacity is two to three times that of AgNbO3 lead-free antiferroelectric ceramics. Finite element simulations showed the further enhancement of breakdown strength was ascribed to the local electric field and to the AgNbO3 ultrafine powder which blocked the breakdown path in the nanocomposites and coupling effects occurred with PVDF. Hence, the AgNbO3 ultrafine powder has a positive effect on improving the energy storage performance of flexible composites. The effects of nonlinear dielectric material coupling effects and interfacial coupling effects on the dielectric properties of composite dielectric materials are further investigated, which are important for the development of flexible high energy storage capacitors.