Imaging the effect of dielectric breakdown in a multilayered polymer film

Wolak, Mason A.; Wan, A.; Shirk, James S.; Mackey, Matt; Hiltner, A.; Baer, E.

doi:10.1002/app.34269

Cited by 43 publications

(36 citation statements)

References 24 publications

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“…%, are required for enhanced dielectric properties, which always lead to severe deterioration of the breakdown strength. 16 Recently, Hu et al expanded the traditional 0-3 nanocomposite to a multilayered topological-structure and realized both greater dielectric displacement and higher breakdown strength. 7 Aggregation of the filler particles would further aggravate the local electric field concentration and reduce the capacitor device reliability.…”

Section: Introductionmentioning

confidence: 99%

Flexible BaTiO₃/PVDF gradated multilayer nanocomposite film with enhanced dielectric strength and high energy density

et al. 2015

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a Organic-inorganic 0-3 nanocomposites, which combine the potentially high dielectric strength of the organic matrix and the high dielectric permittivity of the inorganic filler, are extensively studied as energy-storage dielectrics in high-performance capacitors. In this study, a gradated multilayer BaTiO 3 /poly(vinylidenefluoride) thin film structure is presented as a means to achieve both a higher breakdown strength and a superior energy-storage capability. The central layer of this film designed to provide the high electric displacement, is composed of high volume fraction 6-10 nm BTO nanocrystals produced by a TEG-sol method. The small particle size contributes to the high dispersibility of the nanocrystals in the polymer media, as well as a high interfacial area to mitigate the local electric field concentration. The outer layers of the structure are predominantly PVDF, with a significantly lower volume fraction of BTO, taking advantage of the higher dielectric strength for pure PVDF at the electrode-nanocomposite interface. The film is mechanically flexible, and can be removed from the substrate, with total thicknesses in the range of 1.2 -1.5 μm. Parallel plate capacitance devices exhibit highly improved dielectric performances with low-frequency permittivity values of 20-25, a maximal discharged energy density of 19.37 J/cm 3 and dielectric (breakdown) strengths of up to 495 kV/mm.BaTiO 3 /PVDF nanocomposite film with high flexibility and gradated BaTiO 3 distribution structure is fabricated by sequential deposition of uniform dispersions of pure PVDF and 8-nm BaTiO 3 nanoparticle sol. These films show high low-frequency dielectric constents of 20-25 with low dispation, a maximal discharged energy density values of 19.37 J/cm 3 and dielectric breakdown strengths of up to 495 kV/mm.

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Section: Introductionmentioning

confidence: 99%

Flexible BaTiO₃/PVDF gradated multilayer nanocomposite film with enhanced dielectric strength and high energy density

et al. 2015

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“…Significant enhancements were observed for dielectric lifetime and breakdown strength, and hysteresis was reduced by decreasing poly(vinylidene fluoride)(PVDF) layer thickness. Wolak and Mackey studied the fracture mechanisms of the layered polycarbonate/poly(vinylidene fluoride‐CO‐hexafluoro propylene)[PC/P(VDF‐HFP)] under divergent field (needle‐plane electrode configuration) conditions. However, little has been done on studying the fracture mechanisms under uniform field, which is more close to the actual use condition of capacitor films.…”

Section: Introductionmentioning

confidence: 99%

Fracture phenomena in micro‐ and nano‐layered polycarbonate/poly(vinylidene fluoride‐co‐hexafluoropropylene) films under electric field for high energy density capacitors

Zhou

Mackey

Yin

et al. 2013

J of Applied Polymer Sci

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The long-term dielectric lifetime properties of multilayered polycarbonate/poly(vinylidene fluoride-co-hexafluoropropylene) [PC/P(VDF-HFP)] films were measured as a function of the layer thickness. An optimum layer thickness of 160 nm was determined with the longest dielectric lifetime. The morphology of the damaged sites after dielectric breakdown was examined using scanning electron microscope. Acoustic emission detection system was coupled with the dielectric setup to correlate fracture events and dielectric breakdown to thereby elucidate the mechanisms of the enhancements in dielectric lifetime properties. Two types of acoustic signals were always observed during the breakdown process for multilayered films. The high-amplitude signals were attributed to the formation of breakdown pinholes caused by the primary discharge from top to bottom electrode. The subsequent lowamplitude signals were attributed to internal discharges that could further damage the film. The total number of acoustic hits, in particular, low-amplitude hits, increased with decreasing layer thickness, indicating more internal discharges occurred along the layered interface. It was concluded that the breakdown event initiated at a defect initiated "hotspot" formed because of internal pressure buildup. The film was punctured when the pressure buildup inside the film overcame the mechanical strength of the film. More number of PC layers and layer interfaces were desirable to slow down and divert the damage propagation through the film thickness direction. The crazes in P(VDF-HFP) can, however, easily propagate across PC layers with less than 160 nm layer thickness.Recent studies on the layered polymer capacitor films have focused on dielectric properties, including dielectric lifetime, 3 breakdown strength, 1,2 and hysteresis. 14 Significant enhancements were observed for dielectric lifetime and breakdown strength, and hysteresis was reduced by decreasing poly(vinylidene fluoride)(PVDF) layer thickness. Wolak 15 and Mackey 2

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“…Effective permittivity, breakdown strength, and energy density measurements indicate improvements with the appropriate PC/PVDF-HFP compositions (Wolak et al, 2008). Images of treeing structures and punch-through pin holes obtained using focus ion beam (FIB) milling and scanning electron microscopy (SEM) clearly show the extent and nature of damage including delamination, punch-through, voids, and treeing structures (Wolak et al, 2012). Breakdown in layered structures are influenced by charge injected from both electrodes which can migrate and accumulate at interfaces leading to electric field modification.…”

Section: Introductionmentioning

confidence: 98%

“…Material interfaces serve as trapping sites, especially for mobile negative charge (Wolak et al, 2008;Wolak et al, 2012). Physical interfaces constructed of the same material exhibit the same behavior in allowing the passage of positive charge and to a lesser extent, negative charge.…”

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confidence: 99%

Simulation of charge packet formation in layered polymer film

Lean¹,

Chu²

2014

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

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Purpose -The purpose of this paper is to describe a rapid and robust axisymmetric hybrid algorithm to create dynamic temporal and spatial charge distributions, or charge map, in the simulation of bipolar charge injection using Schottky emission and Fowler-Nordheim tunneling, field-dependent transport, recombination, and bulk and interfacial trapping/de-trapping for layered polymer films spanning the range from initial injection to near breakdown. Design/methodology/approach -This hybrid algorithm uses a source distribution technique based on an axisymmetric boundary integral equation method (BIEM) to solve the Poisson equation and a fourth-order Runge-Kutta (RK4) method with an upwind scheme for time integration. Iterative stability is assured by satisfying the Courant-Friedrichs-Levy (CFL) stability criterion. Dynamic charge mapping is achieved by allowing conducting and insulating boundaries and material interfaces to be intuitively represented by equivalent free and bound charge distributions that collectively satisfy all local and far-field conditions. Findings -Charge packets cause substantial increase of electric stress and could accelerate the breakdown of polymeric capacitors. Conditions for the creation of charge packets are identified and numerically demonstrated for a combination of impulsive step excitation, high charge injection, and discontinuous interface. Originality/value -Metallized bi-axially oriented polypropylene (BOPP) dielectric thin film capacitor with self-clearing and enhanced current carrying capability offer an inexpensive and lightweight alternative for efficient power conditioning, energy storage, energy conversion, and pulsed power. The originality is the comprehensive physics and multi-dimensional modeling which span the dynamic range from initial injection to near breakdown. This model has been validated against some empirical data and may be used to identify failure mechanisms such as charge packets, gaseous voids, and electroluminescence. The value lies in the use of this model to develop mitigation strategies, including re-designs and materials matching, to avoid these failure mechanisms.

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Imaging the effect of dielectric breakdown in a multilayered polymer film

Cited by 43 publications

References 24 publications

Flexible BaTiO₃/PVDF gradated multilayer nanocomposite film with enhanced dielectric strength and high energy density

Flexible BaTiO₃/PVDF gradated multilayer nanocomposite film with enhanced dielectric strength and high energy density

Fracture phenomena in micro‐ and nano‐layered polycarbonate/poly(vinylidene fluoride‐co‐hexafluoropropylene) films under electric field for high energy density capacitors

Simulation of charge packet formation in layered polymer film

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Imaging the effect of dielectric breakdown in a multilayered polymer film

Cited by 43 publications

References 24 publications

Flexible BaTiO3/PVDF gradated multilayer nanocomposite film with enhanced dielectric strength and high energy density

Flexible BaTiO3/PVDF gradated multilayer nanocomposite film with enhanced dielectric strength and high energy density

Fracture phenomena in micro‐ and nano‐layered polycarbonate/poly(vinylidene fluoride‐co‐hexafluoropropylene) films under electric field for high energy density capacitors

Simulation of charge packet formation in layered polymer film

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Flexible BaTiO₃/PVDF gradated multilayer nanocomposite film with enhanced dielectric strength and high energy density

Flexible BaTiO₃/PVDF gradated multilayer nanocomposite film with enhanced dielectric strength and high energy density