High energy density and breakdown strength from β and γ phases in poly(vinylidene fluoride-co-bromotrifluoroethylene) copolymers

Matthew R. Gadinski, Kuo Han, Qi Li, Guangzu Zhang, Wuttiichai Reainthippayasakul, Qing Wang

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

Poly(vinylidene fluoride) PVDF-based copolymers represent the state of the art dielectric polymers for high energy density capacitors. Past work on these copolymers has been done with limited emphasis on the effects of copolymer composition and with a limited range of defect monomers, focusing primarily on the commercially available poly(vinylidene fluoride-co-chlorotrifluoroethylene), P(VDF-CTFE), and poly(vinylidene fluoride-co-hexafluoropropylene), P(VDF-HFP), and the processing thereof. To expand on this area of research, copolymers of VDF and bromotrifluoroethylene (BTFE) were synthesized examining the composition range where uniaxial stretching was possible. It is found that P(VDF-BTFE) copolymers with small BTFE contents (< 2 mol %) stabilize the γ phase, compared to P(VDF-CTFE)s and P(VDF-HFP)s that are largely α phase in composition. Furthermore, different from P(VDF-CTFE)s and P(VDF-HFP)s, whose energy storage capabilities depend on the reversibility of the α to β phases transformation, high discharged energy densities (i.e., 20.8 J/cm3 at 716 MV/m) are also achievable through the β and γ phases in P(VDF-BTFE)s without significantly reducing crystallinity and breakdown strength. This study demonstrates new avenues to the development of high energy density ferroelectric copolymers via manipulation of the γ phase through variation of the structure and content of comonomers.

Original languageEnglish (US)
Pages (from-to)18981-18988
Number of pages8
JournalACS Applied Materials and Interfaces
Volume6
Issue number21
DOIs
StatePublished - Nov 12 2014

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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