Electroactive poly(vinylidene fluoride)-based materials: recent progress, challenges, and opportunities

Barbosa

et al. 2021

Macro Materials & Eng

Considering the high levels of materials used in the fields of electronics and energy storage systems, it is increasingly necessary to take into consideration environmental impact. Thus, it is important to develop devices based on environmentally friendlier materials and/or processes, such as additive manufacturing techniques. In this work, poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) are prepared by direct-ink-writing (DIW) by varying solvent evaporation temperature and fill density percentage. Different morphologies for both polymers are obtained, including dense films and porous membranes, as well as different electroactive 𝜷-phase content, thermal and mechanical properties. The dielectric constant and piezoelectric d 33 coefficient for dense films reaches up to 16 at 1 kHz and 4 pC N −1 , respectively for PVDF-HFP with a fill density of 80 and a solvent evaporation temperature of 50 °C. Porous structures are developed for battery separator membranes in lithium-ion batteries, with a highest ionic conductivity value of 3.8 mS cm −1 for the PVDF-HFP sample prepared with a fill density of 100 and a solvent evaporation temperature of 25 °C, the sample showing an excellent cycling performance. It is demonstrated that electroactive films and membranes can be prepared by direct-ink writing suitable for sensors/actuators and energy storage systems.

Section: Dielectric Constant and Piezoelectric Coefficientmentioning

confidence: 99%

Direct‐Ink‐Writing of Electroactive Polymers for Sensing and Energy Storage Applications

Pinto

Barbosa

et al. 2021

Macro Materials & Eng

“…13 Dielectric EAPs can show effects, including piezoelectricity, pyroelectricity, and ferroelectricity, as well as triboelectric characteristics. 14,15 EAPs include silicon elastomer, 16 polyurethane, 12 polypyrrole, 17 polyaniline 18 poly(vinyl alcohol), 19 and poly-(vinylidene fluoride) (PVDF) and its copolymers, 20 among others. In particular, PVDF and its copolymers are commonly used in the production of flexible sensing platforms due to their chemical stability, high polarity, and easy processing in different shapes and forms, such as films, membranes, spheres, and fibers.…”

Section: Introductionmentioning

confidence: 99%

Humidity Sensors Based on Magnetic Ionic Liquids Blended in Poly(vinylidene fluoride-co-hexafluoropropylene)

ACS Appl. Polym. Mater.

Fernandes

Pereira

et al. 2022

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films incorporating 40 wt % of different types of imidazolium ionic liquids (ILs) comprising different magnetic anions (tetrachloroferrate [FeCl 4 ] − , tetrathiocyanatocobaltate [Co(SCN) 4 ] 2− , and tetrachlorocobaltate [CoCl 4 ] 2− ) and imidazolium cation chain lengths (1-butyl-3-methylimidazolium and 1ethyl-3-methylimidazolium) have been developed for humiditysensing applications. The influence of the different ILs on the morphology of the IL/PVDF-HFP composites has been evaluated, with a porous structure observed independently of the IL anion type and cation chain length. The inclusion of the ILs into PVDF-HFP induces polymer crystallization into the electroactive β phase, with the increase more noticeable for PVDF-HFP/[Bmim][FeCl 4 ], which reaches a β phase content of 85%. The degree of crystallinity slightly decreases with the incorporation of the filler and the incorporation of [Bmim] 2 [CoCl 4 ], [Bmim] 2 [Co(SCN) 4 ], and [Emim] 2 [Co(SCN) 4 ], leading to a degree of crystallinity between 11 and 13%. A decrease in the thermal stability and yield strength is observed in the hybrid samples with respect to neat PVDF-HFP, with this decrease being more noticeable for the PVDF-HFP/[Bmim] 2 [Co(SCN) 4 ] samples. Further, the highest magnetization has been obtained for the PVDF-HFP/[Bmim] 2 [Co-(SCN) 4 ] and PVDF-HFP/[Bmim][FeCl 4 ] composites with similar filler concentrations. The suitability of the developed materials for humidity sensing has been evaluated by analyzing the impedance variation with varying relative humidity from 30 to 85%. [Bmim] 2 [CoCl 4 ]/PVDF-HFP displays the highest relative humidity (RH) sensing response of −2245 ± 240 Ω/RH. Finally, the applicability of the developed hybrid IL/polymer composites has been demonstrated by the development of a real-time breathing monitoring device.

“…These fillers are essential to provide ionic conductivity to the matrix and to provide mechanical consistency to the SPE. 21 The most used polymers for SPE development are poly(vinylidene fluoride) (PVDF) 22 , 23 and its copolymers with hexafluoropropylene (HFP) 24 and poly(ethylene oxide) (PEO), 25 among others. In relation to the fillers, the most commonly used materials are lithium salts such as lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluorophosphate (LiPF 6 ), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), 26 carbon-based materials (graphene oxide and carbon nanotubes), and particulate materials such as barium titanate (BaTiO 3 ), titanium dioxide (TiO 2 ), 27 and ionic liquids (ILs), 28 among others.…”

Section: Introductionmentioning

confidence: 99%

Lithium-Ion Battery Solid Electrolytes Based on Poly(vinylidene Fluoride)–Metal Thiocyanate Ionic Liquid Blends

ACS Appl. Polym. Mater.

Fidalgo‐Marijuan

Barbosa

et al. 2022

Solid polymer electrolytes (SPEs) are required to improve battery safety through the elimination of the liquid electrolyte solution in current batteries. This work is focused on the development of a hybrid SPE based on poly(vinylidene fluoride), PVDF, and 1-butyl-3-methylimidazolium cobalt(II) isothiocyanate, [BMIM] 2 [(SCN) 4 Co] magnetic ionic liquid (MIL), and its battery cycling behavior at room temperature. The addition of MIL in filler contents up to 40 wt % to the PVDF matrix does not influence the compact morphology of the samples obtained by solvent casting. The polar β-phase of PVDF increases with increasing MIL content, whereas the degree of crystallinity, thermal degradation temperature, and mechanical properties of the MIL/ PVDF blends decrease with increasing MIL content. The ionic conductivity of the MIL/PVDF blends increases both with temperature and MIL content, showing the highest ionic conductivity of 7 × 10 −4 mS cm −1 at room temperature for the MIL/PVDF blend with 40 wt % of MIL. The cathodic half-cells prepared with this blend as SPE show good reversibility and excellent cycling behavior at different C-rates, with a discharge capacity of 80 mAh g −1 at a C/10-rate with a Coulombic efficiency of 99%. The developed magnetic SPE, with excellent performance at room temperature, shows potential for the implementation of sustainable lithium-ion batteries, which can be further tuned by the application of an external magnetic field.