Ziyue Wang,Jiajun Zhu,Jiyang Xie,Chengding Gu,Wanbiao Hu
Tuning the structure-activity of fillers and matrix is crucial for designing polymer-based dielectric capacitors with high energy storage performance. Up to date, how the fillers’ structural characteristics (surface/interface configurations, dimensions, orientations etc .) contribute to the overall energy storage is far from unveiled. To this end, a combined filler-polymer dual-side design strategy is developed, which involves the DFT guidance for the electronic transport criteria for the designable synthesis of KNb 3 O 8 fillers. Four different structural configurations are constructed, which are surface-modified with polydopamine (PDA) to fabricate the final composite films, i.e . PDA@KNb 3 O 8 /PVDF-P(VDF-HFP)-PMMA with particular orientations and arrangements, through a well-controlled solution casting method. Comprehensive structural and electrical investigations reveal that 1D/2D-orientated PDA@KNb 3 O 8 fillers could obviously enhance the breakdown field and energy storage performance. The difference is that the 1D fillers more effectively improve the energy efficiency (up to 72%), while the 2D fillers more steadily achieve high energy density ( U e = 28.35 J/cm 3 ) among the highest U e reported for the composites. This work not only uncovers the structural origin of the electrostatic storage in inorganic-polymer composite films but also provides critical insights in designing high-energy-density film capacitors.
Ziyue Wang,Huan Liu,Yicheng Peng,Jiyang Xie,Chengding Gu,Wanbiao Hu
Enhancing the breakdown strength (Eb) and polarization of the polymer-based composites through improving the effective interface bonding between the inorganic fillers and polymer matrix is always pursued to achieve high electrostatic energy storage performances. Along with this, paraelectric–ferroelectric (P–F) structured bipolymer PMMA-P(VDF-HFP) was copolymerized and blended to maintain the high Eb but reduce the residual polarization, and meanwhile, potassium triniobate (KNb3O8) rods synthesized by a molten salt (KCl and K2SO4) method were surface-modified using a polydopamine (PDA) shell to form fillers for the fabrication of the composite films that were prepared by a solution casting process. The fabricated PDA@KNb3O8/PMMA-P(VDF-HFP) composite film by filling only a tiny amount of PDA@KNb3O8 (1.0 wt %) exhibits a much enhanced dielectric constant (ε ∼ 9) and polarization (Pmax ∼ 6.9) and large Eb (∼600 MV m–1), therefore giving rise to a high energy density of 15.30 J cm–3 combined with a discharge energy efficiency of 65%. The results herein can be comparative and superior to those of many high-energy storage inorganic–polymer systems that may render this system much potential for dielectric energy storage capacitors.
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