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Q.m. Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Ferroelectric Polymers as multifunctional Electroactive materials: recent advances, potential, and challenges
    MRS Communications, 2015
    Co-Authors: Xiaoshi Qian, Shan Wu, Eugene Furman, Q.m. Zhang, Ji Su
    Abstract:

    As multifunctional Electroactive materials, ferroelectric Polymers are unique owing to their exceptionally high dielectric strength (>600 MV/m), high flexibility, and easy and low-temperature fabrication into required shapes. Although polyvinylidene difluoride (PVDF)-based ferroelectric Polymers have been known for several decades, recent findings reveal the potential of this class of Electroactive Polymers (EAPs) to achieve giant Electroactive responses by tuning the molecular, nano, and meso-structures. This paper presents these advances, including giant electrocaloric effect, giant electroactuation, and large, hysteresis-free polarization response. New developments in materials benefit applications, such as environmentally benign and potentially highly energy-efficient electrical field controlled solid-state refrigeration, artificial muscles, and high-energy and power density electric energy storage devices. The challenges in developing these materials to realize these applications, and strategies to further improve the responses of EAPs will be also discussed.

  • Relaxor ferroelectric Polymers - Fundamentals and applications
    Ferroelectrics, 2007
    Co-Authors: Qin Chen, Baojin Chu, Kailiang Ren, Vid Bobnar, Q.m. Zhang, Yong Liu, Adrijan Levstik
    Abstract:

    We present recent studies in the fundamentals and applications of the relaxor ferro-electric Polymers, i.e., Poly(vinylidene fluoride-trifluroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE) terPolymers and high energy electron irradiated P(VDF-TrFE) coPolymers. We show that the dynamic processes in these relaxor ferroelectric Polymers are very similar to these observed in various polar-glasses. We further show that the large and reversible polarization change in these Polymers leads to giant electrostriction and large electro-optic effect. By employing active electric boundary conditions, we demonstrate that the large electromechanical responses in these Electroactive Polymers can be made use of effectively for energy harvesting with high hat-vested electric energy density and efficiency. Terpolymer composites with ZnS nanoparticles provide an advanced E-O polymer which refractive index can be varied widely by small amount of ZnS in the composites while maintaining the large E-O effect of the matrix.

  • recent advances in highly electrostrictive p vdf trfe cfe terPolymers
    IEEE Transactions on Dielectrics and Electrical Insulation, 2006
    Co-Authors: F Bauer, E Fousson, Q.m. Zhang
    Abstract:

    Ferroelectric materials are intrinsically multifunctional and have found a broad range of applications. A new class of semicrystalline terPolymers comprising vinylidene fluoride (VDF), trifluoroethylene (TrFE), and 1,1-chlorofluoroethylene (CFE), were prepared at Institut de Saint-Louis (ISL) via a suspension polymerization process. Relevant studies and results show that this class of Electroactive Polymers offers unique properties in comparison with other ferroelectric Polymers. The terpolymer exhibits high electrostrictive strain (>7%) with relatively high modulus (>0.3GPa). It has been also observed that the large electrostrictive strain is nearly constant in the temperature range from 20 to 80 degC. The high room temperature relative dielectric constant (~50), which is the highest among all the known Polymers), high induced polarization (~0.05 C/m2), and high electric breakdown field (>400 MV/m) lead to very high volume efficiency for the electric energy storage operated under high voltage (~10 J/cm3)

  • poly vinylidene fluoride trifluoroethylene based high performance Electroactive Polymers
    IEEE Transactions on Dielectrics and Electrical Insulation, 2004
    Co-Authors: Cheng Huang, Q.m. Zhang, F Bauer, Feng Xia, Rob J Klein, Hui Li, Z Y Cheng
    Abstract:

    Making use of defects modification to P(VDF-TrFE) via either high energy electron irradiation treatment or copolymerizing VDF-TrFE with a small amount of chlorinated monomer to form a random terpolymer, we demonstrate that high electromechanical responses can be realized in P(VDF-TrFE) based Polymers. It will be shown that in the stretched and irradiated 68/32 mol% copolymer, a transverse strain of 4.5% and a transverse electromechanical coupling factor k/sub 31/ of 0.65 can be induced under a field of 85 MV/m. In addition, the irradiated copolymer also exhibits a high elastic energy density, /spl sim/ 1 J/cm/sup 3/. For PVDF based terPolymers such as P(VDF-TrFE-CFE) terpolymer (CFE: chlorofluoroethylene), an electrostrictive strain of more than 7% can be obtained. To elucidate the microstructure changes due to the defects modification in P(VDF-TrFE) based Polymers, synchrotron X-ray measurement was carried out on the irradiated coPolymers and the results show that, the irradiation converts the polar-phase into a nonpolar phase. In addition, X-ray date show that the polar-phase can be induced, at the expense of the nonpolar phase, by external fields, confirming that the field induced conformation change is responsible for the observed high electromechanical responses. Although the modified PVDF based polymer exhibits the highest room temperature dielectric constant (60 versus below 10), it is still far below those in the inorganic materials. Experimental results show that by using delocalized electrons in conjugated bonds an all-organic composite with a dielectric constant more than 400 can be achieved. As a result, a strain of near 2% with an elastic energy density higher than 0.1 J/cm/sup 3/ can be induced under a low applied field of 13 V//spl mu/m. The strain is proportional to the applied field and the composite has an elastic modulus near 1 GPa.

  • poly vinylidene fluoride trifluoroethylene based high performance Electroactive Polymers
    Smart Structures and Materials 2003: Electroactive Polymer Actuators and Devices (EAPAD), 2003
    Co-Authors: Feng Xia, Hengfeng Li, Cheng Huang, M Y M Huang, Haisheng Xu, Francois Bauer, Z Y Cheng, Q.m. Zhang
    Abstract:

    This paper reports two classes of Electroactive Polymers developed recently which exhibit very high strain and elastic energy density. In the first class of the Electroactive polymer, i.e., the defects modified poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) Polymers, an electrostrictive strain of more than 7% and an elastic energy density above I J/cm 3 can be induced under a field of 150 MV/m. The large electrostrictive strain in this class of Polymers originates from the local molecular conformation change between the trans-gauche bonds and all trans bonds, which accompanies the field induced transformation from the non-polar phase to the polar phase. The second class of the polymer is an all organic composite, which shows a very high dielectric constant (>400) and high strain induced with a low applied field (2% strain under 13 MV/m). The strain is proportional to the applied field and the composite has an elastic modulus near 1 GPa.

Thomas J Richardson - One of the best experts on this subject based on the ideXlab platform.

  • Design Principles for the Use of Electroactive Polymers for Overcharge Protection of Lithium-Ion Batteries
    2020
    Co-Authors: Karen E Thomas-alyea, Guoying Chen, John Newman, Thomas J Richardson
    Abstract:

    Abstract A continuum-scale model is presented to explain how Electroactive Polymers such as polythiophene can be used to provide overcharge protection for lithium-ion batteries. The model shows how the cell is transformed upon overcharge from a battery to a resistor with a resistivity that varies with position across the separator. Upon discharge or open circuit, self discharge transforms the resistor back into a battery, and normal cycling can be resumed. A simplified model yields a design equation that shows how the potential at which the cell shorts depends on the current density, separator thickness, and the variation of the electronic conductivity and the oxidation potential of the polymer with degree of oxidation. The shorting voltage is independent of the choice of positive electrode and scales with the potential of the charged negative electrode

  • overcharge protection for 4 v lithium batteries at high rates and low temperatures
    Journal of The Electrochemical Society, 2010
    Co-Authors: Guoying Chen, Thomas J Richardson
    Abstract:

    Overcharge protection for 4 V Li{sub 1.05}Mn{sub 1.95}O{sub 4}/lithium cells at charging rates in excess of 1 mA/cm{sup 2} (3C) and at temperatures as low as -20 C was achieved using a bilayer separator coated with two Electroactive Polymers. High rate and low temperature overcharge protection and discharge performance were improved by employing a design in which the polymer-coated portion of the separator is in parallel with the cell rather than between the electrodes. The effects of different membrane supports for the Electroactive Polymers are also examined.

  • Overcharge protection for rechargeable lithium batteries using Electroactive Polymers
    Electrochemical and Solid State Letters, 2004
    Co-Authors: Guoying Chen, Thomas J Richardson
    Abstract:

    A conducting polymer shunt capable of providing overcharge protection for rechargeable lithium batteries via a reversible, internal, self-actuating mechanism is described. A microporous separator was impregnated with poly(3-butylthiophene), an electrochemically active polymer that becomes electronically conducting when oxidized. The morphology of the resulting composite membrane and its electrochemistry in a lithium battery electrolyte were examined. The composite membrane was introduced into a TiS 2 -Li cell as an overcharge protection separator. While the discharge capacity of an unprotected cell was rapidly degraded when it was charged above 4 V, the protected cell was undamaged by overcharging by as much as ten times the normal capacity. The excess charge current was carried by the polymer, which limited the charging potential to about 3.2 V.

Guoying Chen - One of the best experts on this subject based on the ideXlab platform.

  • Design Principles for the Use of Electroactive Polymers for Overcharge Protection of Lithium-Ion Batteries
    2020
    Co-Authors: Karen E Thomas-alyea, Guoying Chen, John Newman, Thomas J Richardson
    Abstract:

    Abstract A continuum-scale model is presented to explain how Electroactive Polymers such as polythiophene can be used to provide overcharge protection for lithium-ion batteries. The model shows how the cell is transformed upon overcharge from a battery to a resistor with a resistivity that varies with position across the separator. Upon discharge or open circuit, self discharge transforms the resistor back into a battery, and normal cycling can be resumed. A simplified model yields a design equation that shows how the potential at which the cell shorts depends on the current density, separator thickness, and the variation of the electronic conductivity and the oxidation potential of the polymer with degree of oxidation. The shorting voltage is independent of the choice of positive electrode and scales with the potential of the charged negative electrode

  • overcharge protection for 4 v lithium batteries at high rates and low temperatures
    Journal of The Electrochemical Society, 2010
    Co-Authors: Guoying Chen, Thomas J Richardson
    Abstract:

    Overcharge protection for 4 V Li{sub 1.05}Mn{sub 1.95}O{sub 4}/lithium cells at charging rates in excess of 1 mA/cm{sup 2} (3C) and at temperatures as low as -20 C was achieved using a bilayer separator coated with two Electroactive Polymers. High rate and low temperature overcharge protection and discharge performance were improved by employing a design in which the polymer-coated portion of the separator is in parallel with the cell rather than between the electrodes. The effects of different membrane supports for the Electroactive Polymers are also examined.

  • Overcharge protection for rechargeable lithium batteries using Electroactive Polymers
    Electrochemical and Solid State Letters, 2004
    Co-Authors: Guoying Chen, Thomas J Richardson
    Abstract:

    A conducting polymer shunt capable of providing overcharge protection for rechargeable lithium batteries via a reversible, internal, self-actuating mechanism is described. A microporous separator was impregnated with poly(3-butylthiophene), an electrochemically active polymer that becomes electronically conducting when oxidized. The morphology of the resulting composite membrane and its electrochemistry in a lithium battery electrolyte were examined. The composite membrane was introduced into a TiS 2 -Li cell as an overcharge protection separator. While the discharge capacity of an unprotected cell was rapidly degraded when it was charged above 4 V, the protected cell was undamaged by overcharging by as much as ten times the normal capacity. The excess charge current was carried by the polymer, which limited the charging potential to about 3.2 V.

Vid Bobnar - One of the best experts on this subject based on the ideXlab platform.

  • Relaxor ferroelectric Polymers - Fundamentals and applications
    Ferroelectrics, 2007
    Co-Authors: Qin Chen, Baojin Chu, Kailiang Ren, Vid Bobnar, Q.m. Zhang, Yong Liu, Adrijan Levstik
    Abstract:

    We present recent studies in the fundamentals and applications of the relaxor ferro-electric Polymers, i.e., Poly(vinylidene fluoride-trifluroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE) terPolymers and high energy electron irradiated P(VDF-TrFE) coPolymers. We show that the dynamic processes in these relaxor ferroelectric Polymers are very similar to these observed in various polar-glasses. We further show that the large and reversible polarization change in these Polymers leads to giant electrostriction and large electro-optic effect. By employing active electric boundary conditions, we demonstrate that the large electromechanical responses in these Electroactive Polymers can be made use of effectively for energy harvesting with high hat-vested electric energy density and efficiency. Terpolymer composites with ZnS nanoparticles provide an advanced E-O polymer which refractive index can be varied widely by small amount of ZnS in the composites while maintaining the large E-O effect of the matrix.

  • dielectric properties of relaxor like vinylidene fluoride trifluoroethylene based Electroactive Polymers
    Macromolecules, 2003
    Co-Authors: Vid Bobnar, Adrijan Levstik, B. Vodopivec, Marija Kosec, Bozena Hilczer, Q.m. Zhang
    Abstract:

    The dynamic processes in poly(vinylidene fluoride−trifluoroethylene) (P(VDF−TrFE)) copolymer, lead lanthanum zirconate titanate (PLZT)−P(VDF−TrFE) composite, electron-irradiated P(VDF−TrFE) copolymer, and poly(vinylidene fluoride−trifluoroethylene−chlorofluoroethylene) (P(VDF−TrFE−CFE)) terpolymer have been studied by measurements of the temperature and frequency-dependent linear (e1) and third-order nonlinear (e3) dielectric constants. While a paraelectric-to-ferroelectric transition takes place in the crystalline region of the nonirradiated copolymer and composite, electron-irradiated P(VDF−TrFE) copolymer and P(VDF−TrFE−CFE) terpolymer show a significantly different dielectric response:  a broad frequency dispersion in e1 and e3, asymmetric temperature evolution of the relaxation spectrum as the longest relaxation time diverges at a finite freezing temperature while the shortest relaxation times remain active down to the lowest temperatures, and a paraelectric-to-glass crossover in the temperature depe...

Adrijan Levstik - One of the best experts on this subject based on the ideXlab platform.

  • Relaxor ferroelectric Polymers - Fundamentals and applications
    Ferroelectrics, 2007
    Co-Authors: Qin Chen, Baojin Chu, Kailiang Ren, Vid Bobnar, Q.m. Zhang, Yong Liu, Adrijan Levstik
    Abstract:

    We present recent studies in the fundamentals and applications of the relaxor ferro-electric Polymers, i.e., Poly(vinylidene fluoride-trifluroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE) terPolymers and high energy electron irradiated P(VDF-TrFE) coPolymers. We show that the dynamic processes in these relaxor ferroelectric Polymers are very similar to these observed in various polar-glasses. We further show that the large and reversible polarization change in these Polymers leads to giant electrostriction and large electro-optic effect. By employing active electric boundary conditions, we demonstrate that the large electromechanical responses in these Electroactive Polymers can be made use of effectively for energy harvesting with high hat-vested electric energy density and efficiency. Terpolymer composites with ZnS nanoparticles provide an advanced E-O polymer which refractive index can be varied widely by small amount of ZnS in the composites while maintaining the large E-O effect of the matrix.

  • dielectric properties of relaxor like vinylidene fluoride trifluoroethylene based Electroactive Polymers
    Macromolecules, 2003
    Co-Authors: Vid Bobnar, Adrijan Levstik, B. Vodopivec, Marija Kosec, Bozena Hilczer, Q.m. Zhang
    Abstract:

    The dynamic processes in poly(vinylidene fluoride−trifluoroethylene) (P(VDF−TrFE)) copolymer, lead lanthanum zirconate titanate (PLZT)−P(VDF−TrFE) composite, electron-irradiated P(VDF−TrFE) copolymer, and poly(vinylidene fluoride−trifluoroethylene−chlorofluoroethylene) (P(VDF−TrFE−CFE)) terpolymer have been studied by measurements of the temperature and frequency-dependent linear (e1) and third-order nonlinear (e3) dielectric constants. While a paraelectric-to-ferroelectric transition takes place in the crystalline region of the nonirradiated copolymer and composite, electron-irradiated P(VDF−TrFE) copolymer and P(VDF−TrFE−CFE) terpolymer show a significantly different dielectric response:  a broad frequency dispersion in e1 and e3, asymmetric temperature evolution of the relaxation spectrum as the longest relaxation time diverges at a finite freezing temperature while the shortest relaxation times remain active down to the lowest temperatures, and a paraelectric-to-glass crossover in the temperature depe...