Rui Huang,Hongye Wang,Cheng Tao,Hua Hao,Zhonghua Yao,Hanxing Liu,Minghe Cao
Thin film capacitors with large energy storage density and high breakdown strength are widely used in modern electronic fields. To solve the problems of interface effect and different polarization mechanism between matrix and fillers in conventional heterogeneous structure composite thin film capacitors, a new-type inorganic microcrystal-amorphous composite film of 0.92BaTiO 3 -0.08Bi(Ni 0.5 Zr 0.5 )O 3 (0.92BT-0.08BNZ) are prepared by sol–gel method. The amorphous matrix improving the breakdown strength is introduced into the film by adjusting preparation technology. Moreover, the nano-scale polar microcrystalline regions (fillers) are introduced and uniformly distributed in the amorphous matrix under various annealing temperatures. Through investigating the influence of different amorphous matrix and microcrystal trend on the dielectric and energy storage properties, it is found that synergistic effect between the polarized microcrystalline regions and the amorphous matrix are optimal at an annealed temperature of 550 ℃. The result shows that a high energy storage density of 103.7 J cm −3 and an efficiency of 88.3% are obtained under the electric field of 8.30MV cm −1 . Simultaneously, the excellent dielectric and energy storage stability is achieved in a wide temperature range of 20–200 °C. Conclusively, this microcrystal-amorphous composite film overcome the low energy storage capability and poor thermal stability of conventional composite films and provide a feasible way for preparing high energy storage performance films.
The electrostatic energy storage performance of polymer dielectrics at high temperature and high electric field can be significantly improved by the incorporation of wide-bandgap, nano-sized particles. It is traditionally believed that the embedded nanoparticles can scatter the hot charges and lead to charge trapping in the interfacial region , which suppress the conduction loss and promote the energy storage performance. In this work, the nano-sized γ-Al 2 O 3 with cubic defect spinel structure and nano-sized α-Al 2 O 3 with a wider bandgap are introduced into a heat-resistant dielectric polymer, respectively, to form two different nanocomposites . The field-dependent energy storage performance, electrical conductivity , and breakdown strength of the polymer nanocomposites at high temperatures, as well as the thermally stimulated depolarization current , are investigated. The results indicate that the intrinsic deep traps introduced by γ-Al 2 O 3 with cubic defect spinel structure are a more critical factor in improving the energy storage performance of the polymer-based composites. We anticipate that our findings reported in this work may help to better guide the selection of nanofillers for high-temperature dielectric polymer nanocomposites.
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