Low Young’s moduli induced D–E loop dispersion and its effect on the energy discharging performance of PVDF and P(VDF-co-HFP) films

Weimin Xia,Yang Liu,Bing Chen,Qing Wang,Zhicheng Zhang

doi:10.1063/1.5016258

Weimin Xia, Yang Liu + Show 3 more

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https://doi.org/10.1063/1.5016258

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Abstract

Large-scale stretched films of PVDF and its copolymer P(VDF-co-HFP) with various molar contents of VDF were found to possess the considerable breakdown electric fields of about 900 MV/m. Under such a high electric field, soft polymer films with lower Young’s moduli are larger compressed, giving rise to a constraining of reversal of dipoles and thereby a depressing of the dielectric response. Consequently, the displacement–electric field loops at above 700 MV/m show a dispersion phenomenon, which agrees with the reduction of in phase dielectric constant from 10 to 7 in soft P(VDF-co-HFP) 85/15mol% thick film caused by ultra-high isostatic pressure of about 400Mpa. Comparatively, in mechanically stretched PVDF and 95.5/4.5mol% P(VDF-co-HFP) thick films with a relatively high hardness, the considerable discharged energy densities of 27.1 J/cm3 and 27.7 J/cm3 were obtained, providing an effective way to achieve high discharging performance for these fluoropolymers.

Highlights

Low Young’s moduli induced D–E loop dispersion and its effect on the energy discharging performance of PVDF and P(VDF-co-HFP) films
PVDF-based polymers with high energy storage densities and fast charging/discharging rates have attracted much attention in academia and engineering owing to their proposed application to power electronics for hybrid electric vehicles, medical devices, and directed-energy weapon systems, as a result of their high polarization and combination of high breakdown strength, low cost, and graceful failure nature.[1,2,3,4]
By considering how the reduced thickness influences the dielectric permittivity of these thick films, we found that a large Young’s moduli can prevent the sample from large-scale compression and improve the discharged energy storage performance of the PVDF-type copolymers

Summary

Introduction

Low Young’s moduli induced D–E loop dispersion and its effect on the energy discharging performance of PVDF and P(VDF-co-HFP) films. We compared the breakdown electric fields of films of β-PVDF and its copolymer β-P(VDF-co-HFP) with different Young’s moduli, and the hardness shows little influence on the Eb for these polymers.

Results

Conclusion