Significantly Improved Dielectric Breakdown Strength and Energy Density in P(VDF-TrFE-CTFE) Polymer via a Facile Uniaxial Drawing Process

Abstract

In the past decade, poly­(vinylidenefluoride) (PVDF)-based polymers have attracted increasing attention in energy storage applications due to the advantages of high breakdown strength, flexibility, processability, and low cost. Compared with the PVDF homopolymer and binary copolymer, terpolymer poly­(vinylidenefluoride-trifluoroethylene-chlorotrifluoroethylene) (P­(VDF-TrFE-CTFE)) possesses higher permittivity due to a strong polar group and its relaxor characteristic. However, its breakdown strength is limited due to the premature saturated polarization and low Young’s modulus. In this work, a facile drawing strategy has been employed to overcome this problem. With the increase in the stretching ratio from 0 to 10, the crystalline grain size is declined from 8.9 to 6.7 nm with the increase in crystallinity, all of which are favorable to improving the breakdown strength and energy storage density, and α/γ-phase tends to transform to β-phase as well. It turns out that the optimal property could be obtained with the stretching ratio of 6, where the breakdown strength could reach 620 kV/mm and a discharge energy density could reach up to 18.3 J/cm3. The optimized performance is significantly larger than that of the original terpolymer P­(VDF-TrFE-CTFE) with breakdown strength and energy density of 280 kV/mm and 6.9 J/cm3, respectively. This work demonstrates that the uniaxial drawing is an effective strategy to improve the performance of P­(VDF-TrFE-CTFE).

Enhancement of Energy Storage Performance of PMMA/PVDF Composites by Changing the Crystalline Phase through Heat Treatment

“…At the same time, the interface polarization caused by doping inorganic materials will also produce significant losses, reducing the material charge and discharge efficiency. Blending multiple polymers to combine their properties is also a common and effective means to enhance the performance of dielectric materials [23][24][25]. Since PVDF is a non-linear dielectric material with a significant dielectric loss, researchers often add linear polymers with a low dielectric loss and a high breakdown strength.…”

Improved Dielectric and Energy Storage Properties of Polypropylene-Based Organic Films through Construction of a Microcompatible “Sea–Island” Structure

“…Simulation with density functional theory (DFT) in the DMol module (a), electrostatic potential distribution model (b), and LUMO and HOMO molecular orbitals of PP, PP- g -MAH, and MG (c).…”

“…The rapid development of modern power electronics technology has put forward higher requirements for the energy storage performance of capacitors. Polymer-based thin film capacitors play an essential role in modern electronic equipment and electricity systems due to the advantages of rapid discharge rate, high voltage resistance, high reliability, lightweight, and low cost. − For example, the most common commercial film capacitors use bioriented polypropylene (BOPP) as the dielectric material and the capacitors behave with low dielectric loss (∼0.0003), high breakdown strength (∼600 MV/m), and ultrahigh room temperature charge/discharge efficiency (>90%). However, the low dielectric constant (∼2.2) of PP makes it difficult to improve the energy storage density (∼2 J/cm 3 ) of thin film capacitors, which has become an obstacle for miniaturization, integration, and high functionality of the electronic and electrical equipment.…”