Enhanced Permittivity and Energy Density in Neat Poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) Terpolymer Films through Control of Morphology

Abstract

Polymer materials with large dielectric constants are desirable for the development of high energy density capacitors. We show that the dielectric properties of poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE)] can be improved by the use of processing conditions that favor formation of a highly crystalline morphology of the nonpolar α-phase. Through the use of spin coating, thermal treatment above the melting temperature, and quenching, we were able to attain a highly crystalline, α-phase rich morphology that has a quite large dielectric constant of 77 ± 10 at 1 kHz. The final morphology and phase composition of the terpolymer films depend strongly on the postprocessing thermal treatment and the quality of the solvent. Evaluation of the polarization behavior of the terpolymer films as a function of electric field reveal that the polymer exhibits a relaxor-ferroelectric behavior and has a substantial energy density of 9.7 J/cm(3) at fields of up to approximately 470 V/μm. Under millisecond pulsed charge-discharge measurements a 3-fold increase in energy density (27 J/cm(3)) is obtained at high fields (∼600 V/μm). Our study demonstrates that the processing conditions and morphology of fluorinated terpolymer films are controlling factors for achievement of high dielectric permittivity and energy density that are critical for high performance capacitors.

Tube-Super Dielectric Materials: Electrostatic Capacitors with Energy Density Greater than 200 J·cm−3

“…For example barium titanate powders loaded with metal particles show higher dielectric values [30,31,32,33], and there are many reports of high dielectric values arising from “extrinisic” properties, particularly surface states, often called “colossal dielectric” materials [34,35,36,37,38,39]. Only recently was a much higher energy density reported for an electrostatic capacitor, and the material used was a polymer [20]. Clearly there is evidence that barium titanate is not the ultimate dielectric.…”

Enhanced Ferroelectric Property of P(VDF‐TrFE‐CTFE) Film Using Room‐Temperature Crystallization for High‐Performance Ferroelectric Device Applications

“…[ 17,21 ] In contrast, an SA treated fi lm revealed right shifted XRD peak toward 19.4° that is attributed to the formation of the ferroelectric β-phase. [ 17 ] Consistent with XRD measurements, DSC analysis revealed that P(VDF-TrFE-CTFE) fi lms prepared through different annealing methods did indeed lead to the formation of different phases. [ 17 ] Consistent with XRD measurements, DSC analysis revealed that P(VDF-TrFE-CTFE) fi lms prepared through different annealing methods did indeed lead to the formation of different phases.…”

“…[ 9,13 ] Additionally, it has been reported that P(VDF-TrFE-CTFE) has a much higher dielectric constant (κ) than other PVDF-based polymers as well as a high electromechanical response and elastic energy density. [ 11,17,21 ] As a result, despite the remarkable features of the P(VDF-TrFE-CTFE) polymer it has not received as much attention as an active material in ferroelectric devices compared with other PVDF-based polymers. [14][15][16][17][18][19][20] Notwithstanding these attractive features and potential benefi ts, however, there still remain a number of important challenges that are associated with the formation of the ferroelectric phase in the P(VDF-TrFE-CTFE) polymer.…”

“…A TA fi lm showed a sharp XRD peak at 18.4°, which is associated with the paraelectric α-phase. [ 17,24,25 ] A relatively broad SA peak might be due to either the existence of a small portion of the α-phase or weak long-range ordering. [ 17,24,25 ] A relatively broad SA peak might be due to either the existence of a small portion of the α-phase or weak long-range ordering.…”

Characterization of Micron-Scale Nanotublar Super Dielectric Materials

“…In this study and others focused on the characterization of dielectric materials and their application in energy storage capacitors [31], [32], [33], [34], capacitance was measured using the classic RC time constant method discussed earlier. In short, this was accomplished by repetitively charging each NTSDM capacitor with a constant DC voltage, and then discharging through a load resistor, all the while measuring the potential across the capacitor.…”