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Energy storage devices play a crucial role in all kinds of electronic devices. Rechargeable lithium-ion batteries have run across problems such as energy density, toughness, and safety. In order to conquer these hindrances, in this work, a novel solid-state polymer electrolyte for lithium-ion batteries was synthesized by blending polymethyl methacrylate (PMMA) in poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) with constant weight percent of ethylene carbonate (EC) and lithium bis (trifluoro methane sulfonyl) imide (LiTFSI), and different concentrations of calcium oxide (CaO). The composite polymer electrolytes (CPEs) (PVdF-HFP:PMMA:LiTFSI:EC:CaO) were fabricated using the solution casting technique. Powder XRD reveals enhancement in intensity with increasing CaO content. FTIR shows the interaction between the polymer-salt matrix. Among the analyzed films, PVdF-HFP:PMMA:LiTFSI:EC:CaO (10 wt.%) exhibits high ionic conductivity (10–4 S/cm) and good electrochemical (4 V) and thermal stability (350℃) which makes it suitable for solid-state electrolyte as a separator in energy storage applications. [ABSTRACT FROM AUTHOR]

This study is the first application of a PVDF-HFP-based polymer inclusion membrane incorporating the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and di(2-ethylhexyl)phosphoric acid (D2EHPA) as the base polymer and extractant for the extraction of bismuth(III), respectively. It is demonstrated that the PIM comprised of 60 wt% PVDF-HFP and 40 wt% D2EHPA is the most effective in the extraction of bismuth(III) from feed solution containing 20 mg L−1 bismuth(III) and 0.2 mol L−1 sulfate adjusted to pH 1.4. The extracted bismuth(III) ions are back-extracted quantitatively to the receiving solution containing 1 mol L−1 sulfuric acid. The stoichiometry experiments reveal that the Bi: D2EHPA ratio in the bismuth(III) extracted complex is 1:6, and D2EHPA is dimer. Moreover, it is shown that the studied PIM has high selectivity in the extraction of bismuth(III) over other interfering ions such as Mo(VI), Cr(III), Al(III), Fe(III), Ni(II), Zn(II), Cd(II), Co(II), Cu(II), and Mn(II). The interference of Fe(III) is also eliminated by masking with fluoride, leading finally to a nearly pure extraction of bismuth(III). [ABSTRACT FROM AUTHOR]

Supercapacitors based on ionic liquid gel polymer electrolytes (GPEs) have attracted considerable attention as a new energy storage device due to their good specific capacitance, good cycling capacity and stability. In this work, flexible gel polymer electrolyte (GPE) films were prepared and applied using three butyl imidazole ionic liquids with different anions as additives based on polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). The structure and the mechanical properties of the GPE films and the electrical properties of the assembled symmetrical supercapacitors have been characterized. In particular, the structure–activity relationship between the structure and properties of the gel electrolyte was revealed by combining calculations with experiments. In particular, the structure–activity relationship between the structure and properties of the GPE was revealed through the combination of calculation and experiment. The results show that the electronegativity of the anions plays an important role in improving the stability and electrochemical properties of the gel system. This work is useful to further verify the influence of the anionic component of ionic liquids on the physical and chemical properties of gel electrolytes and to prepare more excellent solid electrolytes for supercapacitors. [ABSTRACT FROM AUTHOR]

Significant ultraviolet (UV) technology was used to create a new composite polymer electrolyte (CPE) membrane composed of poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), benzophenone (Bp), and varying amounts of highly ion-conducting Li6.4La3Zr1.4Ta0.6O12 (LLZTO) particles. In lithium metal batteries, the CPE membranes demonstrated improved mechanical properties as well as superior electrochemical performances. CPE-15wt% LLZTO typically demonstrated the highest ionic conductivity (σ = 3.7 × 10−3 S/cm) at room temperature, a high Li-transference (t+ = 0.79), and a wider electrochemical stability window (ESW) above 5 V, as well as good mechanical strength (8.2 MPa). More importantly, the CPE-15wt% LLZTO membrane inhibits Li dendrite expansion in Li symmetric cells and exhibits long-term cyclic stability with a current density of 3 mA/cm2 over 1150 h for Li/CPE-15wt% LLZTO/Li. The current study demonstrates that a UV-irradiated CPE membrane can be a promising electrolyte for next-generation lithium-metallic batteries. [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes (SPEs) based on ionic liquid (IL) were created using poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer mixed with 30 wt.% sodium thiocynate and varying weight ratios of EMIm-TCM ranging from 0 wt.% to 300 wt.%. The structural, electrical, thermal, morphological, and electrochemical features of the SPEs films, showing the effects of PVDF-HFP and the level of IL loading, have all been carefully examined. With the addition of IL, the mechanical qualities and mechanical stability of PVDF-HFP were enhanced, getting closer to the smaller usage for liquid electrolytes in energy devices. With the addition of 300 wt.% IL, the maximum ionic conductivity of 10−3 S cm−1 was attained. Additionally, the presence of the amorphous region in the IL-based electrolyte supported the movement of the EMIm + and TCM − ions in the PVDF-HFP chains, as shown by polarized optical microscopy and the ionic transference number. Due to their strong ionic conductivity, good mechanical attributes, and potential for long-term use in electrical double-layer capacitor applications, the developed PVDF-HFP/NaSCN/EMIm-TCM complex-based SPEs are particularly promising, showing the specific capacitance of 10 Fg−1. [ABSTRACT FROM AUTHOR]

Polymer-based separators for energy storage applications are being developed to ensure the high safety, high performance, light weight, and low cost of the device. In this regard, poly(vinylidene fluoride-co-hexafluoropropylene) PVDF-HFP which is a co-polymer of PVDF is an excellent host polymer for energy storage applications as it possess both the crystalline PVDF and the amorphous HFP groups leading to both mechanical stability and ionic conductivity. Though the lithium-ion-conducting PVDF-HFP membranes are successfully utilized as the polymer electrolyte for lithium ion batteries, the enhanced ionic conductivity by usage of plasticizers often degrade their mechanical and thermal stability. Where else, when incorporated with graphene oxide (GO) as the filler, the membrane electrolytes show good ionic conducting nature, with no compromise on thermal stability and mechanical stability. Incorporation of GO results in porous nature and helps in the high electrolyte retention and electrochemical stability even at high potential window. In this review article, the influence of GO with respect to structural changes, thermal stability, and electrical properties is discussed in detail, which will pave way for further new aspects in membrane modification. [ABSTRACT FROM AUTHOR]

Lithium-ion conducting solid electrolytes has been playing a vital role in designing solid-state lithium batteries to provide a propitious solution for the upcoming generation of energy storage devices that need to store more energy with a high degree of safety. Among different lithium-ion conductors, Li1.5Al0.5Ti1.5(PO4)3, a NASICON-type ceramic, has received attraction due to its good air stability and high lithium-ion conductivity. Herein, tellurium incorporated lithium aluminum titanium phosphate (Li1.3Al0.3Te0.03Ti1.67(PO4)3) (LATTP) has been prepared by solid-state reaction method. Further, the various amounts of LATTP incorporated electro-spun composite polymer electrolytes are prepared by using poly(vinylidenefluoride-hexafluoropropylene) (PVdF-HFP) polymer. Herein, we observed that 8 wt% of LATTP incorporated PVdF-HFP composite polymer electrolyte (CPE-8) exhibited high ionic conductivity of 1.9 × 10−3 S cm−1 at 30 °C, and enhanced lithium dendrite suppression and relatively lesser interfacial stability issues. Remarkably, LATTP incorporated CPE-8 shows improved cycling performance over 200 cycles compared to LATTP free (CPE-0). [ABSTRACT FROM AUTHOR]

Ball milling was used to prepare nanocrystalline TiO2, GO and PVDF-HFP/TiO2/GO nanocomposite, and the effects of milling hours on phase transformation and crystal size wasinvestigated. The films were made using the doctor blade method. XRD, SEM, FTIR spectra were used to characterize the prepared samples. The dielectric constant values were calculated for different milling hour. A lightweight, low-power film is described here for controlling the engagement in a mobile cleaning device. Electrostatic adhesion between thin electrode sheets covered with a dielectric substance underpins the film. The load bearing is influenced by the GO to TiO2 wt.%. A portable device has been fabricated based on the concept of electroadhesion. [ABSTRACT FROM AUTHOR]

Free-standing self-polarised films of Ho3+ modified Polyvinylidene fluoride co-hexafluoropropylene (PVDF-HFP) have been prepared using a simple and cost-effective solvent casting method. A study was initiated to bring out the impact of rare earth hydrated salt on the electroactive nucleation of PVDF-HFP. Holmium hydrated salt acts as an excellent filler to induce electroactive γ and β phases of PVDF-HFP. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy were used to authenticate the enhancement in the electroactive phases of PVDF-HFP. Furthermore, differential scanning calorimetric (DSC) measurements reveal an increase in the melting temperature, which indicates an enhancement in the polar β phase. An excellent enhancement in the dielectric constant value has been observed for Ho3+ incorporated composite films. The value reached 24 ~ (at 1 kHz), which is ~3 times greater than the pure polymer for the highest salt-loaded film. The effect of rare earth hydrated salt on the optical properties of the PVDF-HFP composite films has also been examined by analysing the direct and indirect band gaps of hybrid films. In addition, the ferroelectric properties of the prepared composites were also analysed by P-E measurements, and the composite films show remarkable improvement in polarisation. These multi-functionalities, such as the enhanced electroactive nature, flexibility lightweight, high value of dielectric constant, and the possibility for bandgap tuning make the prepared PVDF-HFP/Ho3+ cast films useful in piezo, photonic device applications. [ABSTRACT FROM AUTHOR]

Ferroelectric ceramic–polymer composites consisting of Poly Vinyledine Fluoride–Hexa Fluoro Propylene (PVDF-HFP) as polymer host and 0.5Ba(Zr0.2Ti0.8)O3−0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) ceramics as filler were prepared using solution casting technique. These composites are characterized for structural, microstructural, vibrational, optical, dielectric and ferroelectric properties at various experimental conditions. The electroactive β phase fraction (observed from XRD and FTIR analysis) increases as the filler concentration increases up to 20 wt% of BZT-BCT and above that its value decreases. FTIR results were analyzed to understand the mechanism of enhancement of β phase by the interaction between negatively surface charged ions of filler with the CH2 dipole of polymer matrix. UV–visible spectroscopy also employed to confirm polymer–ceramic filler interaction. Variation of the dielectric constant with different filler concentrations is explained using the percolation theory. Finally, the interplay between the functional properties and the β phase is discussed in detail. [ABSTRACT FROM AUTHOR]

Lithium (Li) metal has been considered as a potential substitute for the graphite anode in Li-ion batteries to further boost their energy density. Polymer electrolytes (PEs) are expected to be applied in Li metal batteries (LMB) to replace liquid electrolytes due to safety concerns. Among others, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based electrolytes offer clear advantages such as improved processability and chemical/electrochemical stability. However, Li dendrite growth in LMBs and the low Li-ion conductivity of solid polymer electrolytes (SPEs) still hinder their practical applications. To address this issue, it has been proposed that solvent-enhanced PVDF-HFP-based polymer electrolytes (SPPEs) with a tuned amount of residual N-methyl-2-pyrrolidone (NMP) could provide improved ionic conductivity and outstanding chemical/electrochemical stability. We report herein the effects of different salts, polymer, and additives on the electrochemical performance and interface stability of SPPEs. We demonstrate that lithium salts and blended polymers play a pivotal role in the electrochemical performance of SPPEs. In addition, additives exert a remarkable effect on the stripping/plating behaviors of metallic lithium anode in SPPEs. SPPEs with adequate LiNO3 are found to be stable with lower overpotentials at 0.5 mA cm−2 on cycling of symmetrical Li cells. These results highlight novel SPPE strategies for optimizing the ionic conductivity and stabilizing the lithium metal anodes. [ABSTRACT FROM AUTHOR]

Tape-casting method has been employed to prepare poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF–HFP)-based porous membranes with different microstructures. The prepared porous membranes are characterized by scanning electron microscopy, differential scanning calorimetry and tensile strength to analyse their morphological, thermal and mechanical properties. Polymer membrane with equal amount of urea and PVDF–HFP weight ratio is found as best membrane due to its high porosity, high liquid uptake, excellent thermal and mechanical properties. Owing to above-mentioned properties, the highest porous film (PM66) shows improved electrochemical properties with flexible carbon nanotube-based composite electrode, which makes it a potential candidate as a separator for the flexible Li-ion batteries. The discharge capacity of flexible lithium titanate electrode with PM66 was found to be ~142 mAh g–1 at 0.1 C rate and was stable up to 100 cycles. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) receives increasing attention in membrane separation field based on its advantages such as high mechanical strength, thermal and chemical stability. However, controlling the microporous structure is still challenging. In this work, we attempted to tailor the morphology of PVDF-HFP membrane via a one-step reactive vapor induced phase separation method. Namely, PVDF-HFP was dissolved in a volatile solvent and then was cast in an ammonia water vapor atmosphere. After complete evaporation of solvent, membranes with adjustable porous structure were prepared, and the microstructures of the membranes were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction characterizations. Based on the results, a mechanism of dehydrofluorination induced cross-linking of PVDF-HFP has been suggested to understand the morphology tailoring. To our knowledge, this is the first report of one-step reactive vapor induced phase separation strategy to tailor morphology of PVDF-HFP membrane. In addition, the membranes prepared in the ammonia water vapor exhibited enhanced mechanical strength and achieved satisfactory separation efficiency for water-in-oil emulsions, suggesting promising potential. [ABSTRACT FROM AUTHOR]

Herein, a thin polymeric film prepared by spin coating technique using the blend of poly(vinylidene floride-co-hexafluoropropylene) (PVDF-HFP) and poly(methyl methactrylate) PMMA (1:1 mixing ratio) was introduced and compared with the pure PVDF-HFP. SEM, XRD, FTIR, TGA and DSC characterizations were conducted. Piezoelectric response was measured by hand made setup and the produced signal measured by a digital oscilloscope. Blending with PMMA increased the β-phase content, improved the heat stability. Crystallization point decreased from 140 to 129 °C and glass transition temperature changed from 59 to 94 °C. A uniform porous film structure was obtained with a thickness value of 12 µm. Piezoelectric potential obtained by applying mechanical force was found 4.385 V and 8.101 V for pure PVDF-HFP and the blend film, respectively. 84.7% increase found in the piezoelectric potential could be a promising result for energy harvesting and sensors applications. [ABSTRACT FROM AUTHOR]

In this paper, a precast solid electrolyte interface (SEI) film strategy was explored for Li metal anode with longer cycling life. At the current density of 0.5 mA cm−2 for 0.5 mAh cm−2 of Li, electrochemical performance tests showed that the half cell with optimized precast SEI film had a coulombic efficiency of more than 99.0% after 620 cycles. Cyclic voltammetry, electrochemical impedance spectrum, mechanical properties, ionic conductivity, scanning electron microscopy, infrared spectroscopy, thermogravimetry, etc., were used to analyze the performance of SEI film. The results showed that when 0.04 mol of lithium bis(oxalato)borate was added into 7.0 g of the poly(vinylidene fluoride-co-hexafluoropropylene) matrix as the components of SEI film, the half cell with the precast SEI film showed the best cycling performance. When different kinds of lithium salts were added into the matrix, the morphology and property after curing were different, which affected the tensile strength, elongation, ionic conductivity, electrolyte absorption rate, and thermal decomposition temperature. Moreover, it had also been found that the strength and ionic conductivity were the main factors in determining the performance of the precast SEI film. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based composite nanofibers containing different barium titanate (BaTiO3) nanoparticle contents of 10–60 wt% were fabricated by an efficient electrospinning. The piezoelectric performance of PVDF-HFP/BaTiO3 composite nanofibers under a periodic compressional pressure of ∼20 kPa was investigated by considering the BaTiO3 content and the electric poling. The X-ray diffraction patterns revealed the presence of piezoelectric tetragonal BaTiO3 nanoparticles in the composite nanofibers with PVDF β-form crystals. The SEM images demonstrated that the BaTiO3 nanoparticles were dispersed uniformly in the composite nanofibers at relatively low loadings of 10–20 wt%, but they formed aggregates at high loadings of 30–60 wt%. The piezoelectric performance of the composite nanofibers increased with the BaTiO3 content up to 20 wt% and decreased at higher BaTiO3 contents of 30–60 wt%, which results from the trade-off effect between the piezoelectric performance and the dispersibility of BaTiO3 nanoparticles in the composite nanofibers. Accordingly, the composite nanofibers with 20 wt% BaTiO3 exhibited maximum piezoelectric outputs such as voltage of ~9.63 V, current ~0.52 µA, and electric power of ~7892.2 nW. After the electric poling, the piezoelectric performance was further enhanced to ~11.69 V, ~20.56 µA, and ~1115.2 nW, which was high enough to light up a small LED bulb after rectification. [ABSTRACT FROM AUTHOR]

—The effect of various types of electrolyte on the behavior of lithium-polyimide batteries was studied. The electrolyte systems used included the liquid 1 M LiPF6 electrolyte in ethylene carbonate/dimethyl carbonate (1: 1), plasticized polymer electrolyte based on the polyvinylidene fluoride copolymer with hexafluoropropylene, and nanocomposite electrolyte with SiO2 nanoparticles introduced in different amounts. The structure rearrangement of polyimide during lithiation—delithiation was studied by cyclic voltammetry (CV), charge—discharge cycling, and quantum—chemical modeling using four types of electrolyte. The use of the polymer and nanocomposite electrolyte was shown to increase the discharge capacity of the polyimide cathode compared to that of the cell with liquid electrolyte, but the structural degradation of the polyimide cathode cannot be avoided. [ABSTRACT FROM AUTHOR]

Lithium-air/oxygen battery has raised widespread interest due to its extraordinary theoretical energy density (up to 3500 Wh kg−1). In this study, a flexible free-standing NASICON (Na-super ionic conductor)-type hybrid solid-state polymer electrolyte (HSPE) based on PVDF-HFP (poly(vinylidene fluoride-hexafluoropropylene)) copolymer and NASICON LATP (Li1.3Al0.3Ti1.7(PO4)3) was prepared and investigated. The HSPE membranes exhibited an ionic conductivity of 1.02 × 10−4 S cm−1 at room temperature along with a electrochemical window from 2 to 4.5 V. Using the HSPE, a lithium-oxygen/air battery with an inorganic solid-state cathode was fabricated. High initial discharge capacities of 4654 and 5564.3 mAh g−1 were reached under pure O2 and ambient air, respectively. Compared to conventional porous polypropylene (PP) separator, the HSPE membrane alleviated the corrosion of the lithium anode, thus improving the cyclability of the cells. The results presented in this study suggest the great potential application of NASICON-type HSPE membrane in solid-state rechargeable lithium-air/oxygen batteries. [ABSTRACT FROM AUTHOR]

A protective conductive polymer electrolyte (PE) composed of poly(vinylidenefluoride-co-hexafluoropropylene), 49% poly(methylmethacrylate)-grafted natural rubber and lithium tetrafluoroborate (PVdF-HFP-MG49-LiBF4, also referred as PHMLi) was used as a strategic method to improve the photocatalyst stability of the dye sensitiser on a TiO2 photoanode. PHMLi was fabricated onto a ruthenium dye-sensitised TiO2 photoanode (FTO/TiO2/Ru/PHMLi) using a dip-coating technique. The COOH anchoring groups in the ruthenium dye are known to undergo hydrolysis in photoelectrochemical cell (PEC) in a direct water-splitting reaction causing the ruthenium dye to desorb from the TiO2 photoanode. Thus, PHMLi was applied to sustain the physical, chemical and photostability properties of the ruthenium dye. The PEC properties of FTO/TiO2/Ru/PHMLi were investigated using a 0.5 M KOH electrolyte. The result indicated that PHMLi protective layer exhibited the ability to retain the ruthenium dye sensitiser on the TiO2 surface and improved the overall photocatalyst stability of the PEC photoanode. [ABSTRACT FROM AUTHOR]

In the present work, we develop a scalable and inexpensive design for lithium-sulfur (Li-S) batteries by capping a flexible gel polymer/carbon nanofiber (CNF)composite membrane onto a free-standing and binder-free CNF + Li2S6 cathode, thus achieving a three-dimensional (3D) structural design. The CNF network is used as the current collector and S holder to overcome the insulating nature and volume expansion of S, while the composite membrane comprises a gel polymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and CNF additive is used as an interlayer to trap polysulfides and recycle the remaining S species, leading to a high specific capacity and long cycle life. This 3D structure enables excellent cyclability for 500 cycles at 0.5 °C with a small capacity decay of 0.092% per cycle. Furthermore, an outstanding cycle stability was also achieved at even higher current densities (1.0 to 2.0 °C), indicating its good potential for practical applications of Li-S batteries. [ABSTRACT FROM AUTHOR]

Abstract: A novel polymer blend electrolyte for dye-sensitized solar cells (DSSCs) was synthesized by quasi-solidifying a liquid-based electrolyte containing an iodide/triiodide redox couple and supporting salts with a mixture of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and indigenous hydroxypropyl methyl cellulose (HPMC). A high ionic conductivity of 8.8 × 10−4 S cm−1 was achieved after introducing 5 wt% of HPMC with respect to the weight of PVDH-HFP. DSSCs were fabricated using gel polymer blend electrolytes, and the J-V characteristics of the fabricated devices were analyzed. Under optimal conditions, the photovoltaic conversion efficiency of cells with the novel HPMC-blended gel electrolyte (5.34%) was significantly greater than that of cells without HPMC (3.97%).Graphical Abstract: [ABSTRACT FROM AUTHOR]

In this paper, a novel method to solve the problem of distortion in commercial lithium-ion pouch cells is introduced. The new approach mainly involves the application of poly(vinylidenefluoride- co-hexafluoropropylene) (PVDF-HFP) binder onto the surface of the separator in a pretreatment process. This binder enhances the strength of the adhesion between the positive electrode and the separator during the hot pressing process. The resulting lithium-ion pouch cell exhibits improved cycle performance and reduced cell thickness swelling. The relationship between the amount of binder coated onto the PP (polypropylene) substrate and the cycle performance was explored, and the optimal amount of binder coating was estimated to be 0.15 mg/cm. Including a composite separator in commercial lithium-ion pouch cells reduces the internal stress between the electrode and the separator and can improve the stability of the jelly-roll structure during cycling, as it balances out the internal stress distribution. [ABSTRACT FROM AUTHOR]

A novel polymer gel electrolyte was used to improve the performance and long-term stability in dye-sensitized solar cells (DSSCs). The polymer gel electrolyte (PGE) was prepared by mixing 5 wt% poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and 2 % TiO nanoparticles. The conductivity of PGE with P25 reached 9.98 × 10 S/cm, which increased by 34.9 % compared with 7.40 × 10 S/cm of PGE without P25, and the diffusion coefficient was also increased by 19.0 %. Different photoelectrodes were obtained by using three kinds of surfactants (cetylamine, octadecylamine, and P123) as pore-forming materials, and their morphologies were contrasted through scanning electron microscopy (SEM). The results showed that gel electrolyte can increase the short-circuit current density ( J ) from 11.01 to 12.99 mA/cm in DSSCs. Moreover, unlike the liquid electrolyte, the gel electrolyte is more conducive to the TiO photoelectrodes with larger pores. In conclusion, the efficiency of DSSC with gel electrolyte and P123 as pore-forming material was 6.73 %, which was 12 % higher than the liquid electrolyte in the same test condition. In addition, the sealed gel electrolyte DSSCs showed better stability than did liquid electrolyte DSSCs during nearly 600 h. [ABSTRACT FROM AUTHOR]

The hybrid polymer nanocomposites based on poly(vinylidene fluoride-co-hexaflouro propylene) (PVdF-HFP) as a host matrix, propylene carbonate as the plasticizer, and surface modified and unmodified TiO nanoparticles as fillers for dye-sensitized solar cell applications have been prepared using a solvent casting technique. The surface of TiO was modified using aminopropyltrimethoxysilane (APS), and its organic functional groups on TiO were confirmed by Fourier transform infrared (FTIR) spectroscopy. The PVdF-HFP membranes were characterized by FTIR, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), atomic force microscopic (AFM), and ultraviolet-visible (UV-Vis) spectroscopic techniques. It was found a new interaction of APS molecules on TiO surface with matrix as well as electrolyte salt. The experimental observations indicated a noticeable improvement in ionic conductivity of modified TiO of about 6.7 × 10 S/cm when compared with unmodified counterpart (TiO) as the filler within PVDF-HFP matrix. The solid state dye-sensitized solar cell has been fabricated by using silane-modified TiO/PVdF-HFP nanocomposite electrolyte and eosin-Y as sensitizer, and its photoconversion efficiency is measured about 1.47 %. [ABSTRACT FROM AUTHOR]

A polymer electrolyte based on the blending of poly(vinylidene fluoride-hexafluoropylene) (PVDF-HFP) and hydroxypropyl methyl cellulose (HPMC) was prepared for the first time. The structure and performance of the gel polymer electrolyte were characterized and measured by X-ray diffraction, Fourier transform infrared, thermogravimetric analysis, scanning electron microscopy, electrochemical impedance spectroscopy, linear sweep voltammetry, and by a charge/discharge test. The results show that the gel polymer electrolyte has the best performance when PVDF-HFP/HPMC ratio ( w/ w) is 4:1. At room temperature, the ionic conductivity can reach 0.38 × 10 S cm, the electrochemical stable window is up to 5.0 V (vs. Li/Li), and the half cell of Li/GPE/LiMnO shows high-discharge-specific capacity and good cycling performance. [ABSTRACT FROM AUTHOR]

Carbon nanofiber (CNF)/polyvinylidene fluoride-hexafluoro propylene (PVDF-HFP) composite film was prepared by solution casting and melt pressing. The resultant 2 % CNF/PVDF-HFP composite films were uniaxially drawn at 50 °C, 75 °C, and 100 °C, respectively. In the SEM images, the morphology of drawn CNF/PVDF-HFP composite film confirmed the orientation of the CNF and the polymer matrix. The WAXD results showed the coexistence crystal phase of PVDF-HFP. The drawn CNF/PVDF-HFP composite film demonstrates improved electrical properties. The DSC thermogram results indicated no change in the melting temperature but slightly increased crystallinity with increasing drawing temperature. Dynamic mechanical analysis and tensile test showed an improvement in the storage modulus and stress at a drawing temperature of 75 °C. [ABSTRACT FROM AUTHOR]

The aging towards the ionic conductivity have been studied using of different lithium salts namely, lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium fluoroalkylphosphate (LiFAP) and LiPF in polyvinylidenefluoride-hexafluoropropylene (PVdF-HFP) matrix. The crystallization behavior of LiBOB and LiDFOB has been noticed for the first time during storage of such membranes within the texture of PVdF-HFP matrix. At the same time, such behavior has not been observed in the case of LiFAP and LiPF based membranes. The growth of such crystallites would certainly hinder the mobility mechanism of Li ions and it has been confirmed by ionic conductivity measurements. The formation of such crystals has been validated through scanning electron microscopic studies. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP) films were prepared using either a melt pressing or solution casting methods. The resulting PVDF-HFP films were drawn uniaxially at various drawing temperatures and speeds. The mp-PVDF-HFP films were more transparent and had more drawability than the sc-PVDF-HFP films. The crystal form of the initial films was the alpha-phase (non polarity) of PVDF. The maximum draw ratio was 7.6. The mp-PVDF-HFP films were prepared at a drawing speed of 2500 %/min at 100 °C. With increasing drawing speed, the beta-phase (polarity) became the dominant phase of PVDF in mp-PVDF-HFP films. The thermal properties of the resulting PVDF-HFP films improved with increasing drawing temperature. [ABSTRACT FROM AUTHOR]

Lithium bis(perfluoroethanesulfonyl)imide (BETI; guest species)-based polyvinylidenefluoride-hexafluoropropylene (PVDF-HFP) (host matrix) polymer nanocomposites (PNC) films by loading barium titanate (BaTiO) as a filler in ascending proportions with plasticizer (mixture of EC + DMC) while keeping host and guest content as constants has been investigated by employing AC impedance, thermal, X-ray diffraction (XRD), phase morphology, and Fourier transform infrared (FTIR) studies. The ionic conductivity measurements on these PNC show that 2.5% BaTiO-loaded polymer nanocomposites (PNC) showed mitigation in magnitude of the conductivity compared with that of 0 wt.% loaded PNC; but increase in conductivity is noted thereafter with increase in filler content of up to 7.5 wt.%. The higher conductivity is observed for 7.5% filler-loaded membrane. The XRD study identifies suppression of polymer phase associated with (200) plane. The SEM image illustrates inhomogeneity in surface morphologies for PNCs with the filler dispersed. The thermal profile registers the endothermic changes associated with polymer host indicating a varying heat of fusion ∆Hm with filler increase. FTIR studies confirm possible interaction between various constituents of the PNCs. [ABSTRACT FROM AUTHOR]

A novel composite microporous polymer electrolyte composed of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) and mesoporous SBA-15 was pre- pared. The composite solid polymer electrolyte (CSPE) exhibits ionic conductivity as high as 0.30 mS·cm-1 with a composition of SBA-15 : PVdF-HFP=3 : 8 at room temperature. Infrared transmission spectroscopic results suggested that the mechanism of micropore formation is similar to that of the phase inversion. X-ray diffraction (XRD) results demonstrated that the addition of SBA-15 inhibits the crystallization of PVdF-HFP, while the SBA-15 preserves well its ordered mesoporous structure during the course of preparation. The Li/CSPE/MCF of half-cell was assembled, and it showed a good electrochemical and cyclability performance during charge-discharge cycles. [ABSTRACT FROM AUTHOR]

A novel solid polymer electrolyte (pore-gel SPE) has been found to provide superior SPE having a high conductivity, good mechanical strength and low solution leakage. This pore-gel SPE was prepared from gelation in pores of polymer membrane with electrolyte solution including solvent. The conductivity of pore-gel type PVDF-HFP/ TEABF4 (Tetraethylammomium tetrafluoroborate) membrane can reach 1.6×10-1 Scm-1. The tensile strength of this membrane was 4,000 kPa, which is about 23 times larger than that of gel-type SPE with the same composition. Poregel SPE reduced solution leakage to 0%, compared with 2% of hybrid-type SPE after 2.0 hr leakage test in PVDFHFP/ TEABF4 membrane. [ABSTRACT FROM AUTHOR]

Polyvinylidenefluoride-co-hexafluoropropylene(PVdF-HFP) and polymethylmethacrylate (PMMA) and sodium triflate(NaTf) were used to prepare P(VdF-HFP)-PMMA-NaTf electrolytes using solution casting technique. The liquid plasticizer ethylene carbonate (EC) was added to the electrolytes in different concentrations say 10, 20, 30 and 40 wt% to achieve the enhancement of Na+ ion conduction at room temperature. Ionic conductivity of the samples was determined using AC impedance analysis and it was 7.86 × 10−8 S cm−1 for the polymer blend electrolyte at room temperature. Inclusion of EC was found to enhance the Na+ ion conduction and maximum value of ionic conductivity, 1.86 × 10−4 S cm−1, was obtained for the EC concentration of 30 wt%. This observation was explained on the basis of FTIR, XRD and AFM analysis of the samples which revealed the enhanced EC-polymer interaction and hence fast ion transport. Larger increase of dielectric constants and the reduced dielectric loss of EC added polymer blend electrolytes revealed the increase of the number of free Na+ ions. Thermal analysis of the samples was done through TGA-DTG technique and the thermal stability was found to decrease after the addition of EC. [ABSTRACT FROM AUTHOR]