Abstract
The development of high-energy-density electrostatic capacitors is critical to addressing the growing electricity need. Currently, the widely studied dielectric materials are polymer nanocomposites incorporated with high-dielectric-constant nanoparticles. However, the introduction of high-dielectric-constant nanoparticles can cause local electric field distortion and high leakage current, which limits the improvement in energy density. In this work, on the basis of conventional polymer nanocomposites containing high-dielectric-constant nanoparticles, oriented boron nitride nanosheets (BNNSs) are introduced as an extra filler phase. By changing the volume ratios of barium titanate (BT) and BNNSs, the dielectric property of polymer nanocomposites is adjusted, and thus the capacitive energy storage performance is optimized. Experimental results prove that the oriented BNNSs can suppress the propagation of charge carriers and decrease the conduction loss. Using poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) as the polymer matrix, the P(VDF-HFP)/BNNS/BT nanocomposite has a higher discharged energy density compared with the conventional nanocomposite with the freely dispersed BT nanoparticles.
Highlights
Dielectric capacitors are widely used as energy storage and conversion devices in electrical systems and advanced electronics, such as power inverters, medical defibrillators, pulse forming networks, hybrid electric vehicles, and portable electronics [1,2,3,4]
We demonstrate a ternary nanocomposite composed of high-dielectricconstant BaTiO3 (BT) nanoparticle and oriented two-dimensional boron nitride nanosheet (2D-boron nitride nanosheets (BNNSs)), which alleviates the drawbacks of free dispersed barium titanate (BT) nanoparticles, retains the excellent insulating property of BNNSs, and realizes the simultaneously enhanced ε and Eb
BNNSs were obtained by an ultrasound-assisted peeling method [17]
Summary
Dielectric capacitors are widely used as energy storage and conversion devices in electrical systems and advanced electronics, such as power inverters, medical defibrillators, pulse forming networks, hybrid electric vehicles, and portable electronics [1,2,3,4]. The breakdown strength of BOPP films is as high as ~700 MV/m, the low dielectric constant of ~2.2 restricts the energy density to only ~5 J/cm3 [10]. To further improve the energy density of ferroelectric polymers, extensive studies have been carried out to further increase ε by adding high-dielectric-constant nanofillers [12], such as barium titanate (BaTiO3), barium strontium titanate (BaxSr1−xTiO3), and lead zirconate titanate (Pb(Zr,Ti)O3) [13,14,15]. The introduction of high-dielectric-constant nanofillers cannot significantly increase the discharged energy density. The dielectric constant, breakdown strength, and discharged energy density of the resultant nanocomposites can be adjustable by tuning the content and ratio of BT and BNNS. It was found that the nanocomposites with the optimal content of nanofillers discharged an energy density as high as 13.0 J/cm with the charge–discharge efficiency of 72% under an electrical field of 547 MV/m
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