Electric energy storage properties of poly(vinylidene fluoride)

Abstract

High discharged energy density observed in poly(vinylidene fluoride) (PVDF) based copolymers has attracted considerable research interests in the past years. Crystalline properties exhibit great influence on their dielectric and energy storage properties. To understand how crystalline properties influence the energy storage properties of PVDF, PVDF films with three different crystal forms are investigated in this paper. It is shown that γ-PVDF is allowed to work under higher electric fields than α- and β-PVDF in the absence of phase transition in α-PVDF and early polarization saturation in β-PVDF. Consequently, γ-PVDF exhibits the highest energy density of 14 J/cm3 under 500 MV/m electric field.

Polarization of poly(vinylidene fluoride) and poly(vinylidene fluoride-trifluoroethylene) thin films revealed by emission spectroscopy with computational simulation during phase transition

“…These changes correspond to the enthalpy of process DH $ À3.35 J/g (per volume unit, for the corresponding molar mass M c , above). All these data compare well with many published values 37,[46][47][48][49][50] and correspond to the T-G phase transition in the P(VDF-TrFE) (70:30) structure and crystal cell.…”

Ultrahigh β-phase content poly(vinylidene fluoride) with relaxor-like ferroelectricity for high energy density capacitors

“…Our work focuses on virgin, commercially available and inexpensive PVDF homopolymers, and demonstrates a facile and scalable processing route to obtain an ultrahigh content of β-phase (~98% of crystalline phase) with RFE-like behaviour that has an exceptionally high energy storage density of 35 J cm −3 , which is achieved by reversible field-induced transitions related to thermally unstable local polar structures. This is the highest value reported for a polymer-based dielectric material (Supplementary Table 1) 22–31 , to the best of our knowledge. The produced homopolymer PVDF films show the lowest dielectric loss (0.02 at 1 kHz) and highest maximum working temperature (120 °C) in PVDF-based ferroelectric materials (dielectric loss: 0.03–0.05 for previously reported PVDF and copolymer films; 0.08–0.10 for terpolymer films; maximum working temperatures: 100–120 °C for previously reported PVDF and copolymer films; 50–60 °C for terpolymer films), which challenges the performance of commercial electrochemical capacitors and ceramic capacitors, with the added benefits of mechanical flexibility, toughness and low density.…”

Role of polymer matrix in large enhancement of dielectric constant in polymer-metal composites

“…These PCC undergo an insulator-metal transition (IMT) at a critical volume fraction of the conductor ðf con Þ called percolation threshold ðf c Þ which is characterized by an abnormal increase in ac conductivity ðr eff Þ and divergence in the real part of e eff in accordance with the percolation theory. 16 [4][5][6][7][8][9][10][11][12][13][14][15] These investigations show scattered values of e eff and f c . The effects of nature of filler, along with their particle size, shape, and process conditions on e eff and f c have been investigated in various PCC.…”

“…The effects of nature of filler, along with their particle size, shape, and process conditions on e eff and f c have been investigated in various PCC. [4][5][6][7][8][9][10][11][12][13][14][15][18][19][20][21][22] However, few studies are oriented towards investigation of (i) what is the role of polymer matrix in increasing the e eff at f c ? (ii) whether the extent of enhancement of e eff at f c depend on the polymer matrix in case of PMC.…”