Novel plum pudding structured BaTiO3@ZIF-67 filler design for high-performance dielectric polymer composites

The dielectric composites which are consisted of polymer matrix and ceramic fillers recently spark tremendous research interest as the promising energy storage materials in dielectric capacitors. However, the poor compatibility and huge dielectric mismatch between inorganic ceramic and organic polymer inevitably induce the severe aggregation and local free charge carriers accumulation at the interface, thus deteriorating the breakdown strength and energy storage performance. Herein, a novel plum pudding structured BaTiO3@ZIF-67 filler is designed and prepared for the first time, where numerous BaTiO3 nanoparticles are distributed uniformly within the ZIF-67, therefore effectively alleviating the aggregation phenomenon. Employing P(VDF-HFP) as the polymer matrix, BaTiO3@ZIF-67/P(VDF-HFP) composites with various filler loadings are fabricated. Notably, the composite with 3 wt% filling ratio presents the maximum discharge energy density of 12.8 J/cm3, which is much higher than that of the pristine P(VDF-HFP) and the counterpart filled with the same loading uncoated BaTiO3 nanoparticles. The improvement of the energy storage performance is mainly attributed to the increase of breakdown strength after introducing the ZIF-67 interlayer, and the enhancement mechanism is further revealed by finite element analysis method. This work provides an intriguing strategy of the filler structure modulation for achieving high-performance composite dielectrics.