Enhanced dielectric energy storage properties in linear/nonlinear composites with hybrid-core satellite C/SiO2@TiO2 nanoparticles

Abstract

Polymer dielectrics for electrostatic capacitors possess well-recognized advantages, including ultrahigh power density, excellent processability, and unique self-healing capability. Nevertheless, the negative coupling relationship between dielectric permittivity and breakdown strength in dielectrics always constrains the enhancement of energy density, which cannot satisfy the ever-increasing requirements for integrated and miniaturized technologies. Here, a kind of C/SiO2@TiO2 triphase nanoparticle (CST NP) with a hybrid-core satellite structure is prepared and introduced into nonlinear poly(vinylidene fluoride-co-hexafluoropylene) [P(VDF-HFP)] matrix to improve permittivity and polarization. Benefited from the intensified interfacial polarization induced by CST NPs, a high permittivity of ∼18.8, which is approximately 219% that of pure P(VDF-HFP) (∼8.6), is obtained at 10 kHz. Meanwhile, a linear PEI film with high breakdown strength is stacked with the CST/P(VDF-HFP) composites, forming linear/nonlinear CST/P(VDF-HFP)-PEI bilayer composites. Eventually, a high breakdown strength of ∼503.9 kV/mm, a high energy density of ∼4.26 J/cm3, and a high efficiency of ∼91% are simultaneously achieved in the bilayer composite with merely 0.75 wt. % nanoparticles. The linear/nonlinear bilayer structure incorporated with hybrid-core satellite nanofillers offers an effective strategy to design high-performance dielectric energy storage materials.

Remarkably enhancing dielectric permittivity and suppressing loss of PVDF via incorporating metal nanoparticles decorated glass fibers

“…The test voltage range was from 0 to 200 V, and the test step size was 5 V. Finally, the leakage current density curve was obtained. 200), ( 220), ( 311) and ( 222) crystal planes of the Au (PDF#99-0056), further confirming the presence of Au NPs in composites [20]. For pure PVDF, the sharp diffraction peaks at 17.66 • , 18.3 • and 26.6 • correspond to the (100), ( 020) and (021) crystal planes of α phase [25].…”

“…It can be seen from the XRD patterns of figure2(d) that only two broad peaks around 10.9 • and 25.3 • appear in the XRD pattern of GF, implying amorphous structure of GF[24]. The strong characteristic peaks of Au@GF framework and Au@GF/PVDF composite at 38.2 • , 44.4 • , 64.6 • , 77.6 • and 81.7 • correspond to the (111), (200), (220), (311) and (222) crystal planes of the Au (PDF#99-0056), further confirming the presence of Au NPs in composites[20]. For pure PVDF, the sharp diffraction peaks at 17.66 • , 18.3 • and 26.6 • correspond to the (100), (020) and (021) crystal planes of α phase[25].…”

“…In addition, figure 7 compares the dielectric properties of this work and current published works of polymer-based dielectrics [3,6,7,16,20,21,37,38,42,[44][45][46][47][48][49][50]. Apparently, in previous reports, an enhanced permittivity of dielectric composites is always accompanied by an increase in loss, and vice versa.…”

“…Subsequently, the calcined Au@GF frameworks were dip-coated with the above PVDF slurry under vacuum for 10 min, and then hung in a hot oven for 4 h at 100 • C to completely remove the solvent (DMF). The composites were heated to 200 • C for a few minutes and then quenched in ice-cold water immediately, which is beneficial for maintaining the β phase of PVDF [6,16,20,21]. In comparison, the above pure PVDF solution was uniformly casted onto a clean quartz plate and pure PVDF films were prepared using the same drying and quenching steps.…”

“…In recent years, researchers put their effort into addressing this problematic issue through surface modification (e.g. core shell structure) of conductive particles or indirect loading method to improve the interaction between fillers and polymer matrix [3,[19][20][21]. However, there has been no substantial reduction in loss through current methods, becoming a bottleneck for the development of conductor/polymer composites.…”