Enhanced energy density in sandwich-structured P(VDF-HFP) nanocomposites containing Hf0.5Zr0.5O2 nanofibers

Ceramic/polymer composites with high energy density attract great interest due to their application in microelectric power systems. However, the large permittivity mismatch between ceramic fillers and polymer matrix will largely decrease the breakdown strength and energy density of nanocomposites. Herein, one-dimensional Hf0.5Zr0.O-5(2) nanofibers (HZO-NFs) with very low permittivity were proposed as the loading fillers in poly (vinylidene fluoride - hexafluoro propylene) (P(VDF-HFP)) copolymer for energy-storage applications for the first time via a simple scalable method of electrospinning technique. P(VDF-HFP) nanocomposites with 3 wt% HZONFs (3 wt% HZO/P) showed a high discharged energy density (U-d) of 13.68 J/cm(3) with a high breakdown strength (E-b) of 508.66 kV/mm. Sandwich-structured P-3 wt% HZO/P-P nanocomposite achieved an excellent U-d of 21.63 J/cm(3) and a high eta of similar to 65.68% at ultrahigh E-b of 706.71 kV/mm, which are much higher than those of the commercial BOPP, i.e. 2 J/cm(3) at 640 kV/mm. Moreover, the COMSOL simulations revealed that the introduction of 1D nanofibers and charge traps could effectively improve the local distribution of electric field, and finally increased the breakdown strength. The major contribution to the improved U-d originates from the large breakdown strength (4 similar to 8 MV/cm), because of the large band width of HZO and the existence of multiinterfaces. This work can provide a new perspective for promoting the performance of polymer nanocomposites.