Use Of Polyvinylidene Fluoride Research Articles

Side-Reactions of Polyvinylidene Fluoride and Polyvinylidene Chloride Binders with Aluminum Chloride-Based Ionic Liquid Electrolyte in Rechargeable Aluminum-Batteries

Abstract Rechargeable aluminum batteries (RABs) use a Lewis acidic aluminum chloride (AlCl3) and 1-Ethyl-3-methylimidazolium chloride (EMImCl) ionic liquid electrolyte. Electrode fabrication often relies on procedures from lithium-ion batteries (LIBs), including the use of Polyvinylidene fluoride (PVdF) as a binder. However, PVdF reacts with Al2Cl7- in the RAB electrolyte, making it unsuitable for new battery types. The literature lacks details on the products formed, changes in the ionic liquid electrolyte, and the implications for electrochemical performance. With potential European Chemical Agency restrictions on per- and polyfluoroalkyl substances (PFAS) by 2025, Polyvinylidene chloride (PVdC) is being explored as an alternative binder. In contact with AlCl3:EMImCl (1.50:1.00) electrolyte, both, PVdF and PVdC transform into amorphous carbon during dehydrofluorination and dehydrochlorination, respectively, as confirmed by Raman spectroscopy. Furthermore, via 19F-NMR, it is shown that the reaction time between the soaked polymers and the ionic liquid has a significant influence on the newly formed aluminum chlorofluoride complexes. Electrochemical tests of graphite-based electrodes indicate increasing specific capacity of PVdF compared to PVdC with a continuous number of cycles. Amorphous carbon can prevent the disintegration of graphite and enhance conductivity. Furthermore, newly formed AlF4- can run a co-intercalation and lead to increasing specific capacity.

Optimizing the polar phase transformation in PVDF-HFP/BaTiO3-activated carbon composite films with the mixture design of experiments

ABSTRACT A salient bottleneck to driving the wider use of polyvinylidene fluoride (PVDF) and its copolymers in smart applications is the requirement for a high-voltage poling process required to activate their β -phase crystal structure before the realisation of the piezoelectricity response. In pursuit of enhancing the β-phase content of PVDF-based films, various approaches have been employed in recent years. Yet, a perfect solution to the challenge remains elusive. Here, we report a preliminary investigation into the production of unpoled poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) films reinforced with barium titanate (BaTiO3) and activated carbon (AC) to improve the piezoelectric property. Employing the mixture design of experiments (MDOE) method, various formulations of the composite’s constituents weight fractions were determined. Afterwards, series of composite films were produced via a toxic-free solution casting method and characterised by Fourier Transform Infrared Spectrum (FTIR) to determine the β-phase content. A non-linear polynomial regression model was established from the experimental FTIR data, and the adequacy of the model was confirmed using ANOVA. Subsequently, an MDOE-enabled optimisation was undertaken, generating a formulation of the composite to obtain the highest β-phase content to be 15 wt.% BaTiO3 and 0.74 wt.% AC. This combination produces a theoretically predicted β-phase content of 72.7 %. A further experimental test employing the optimal formulation produced a β-phase content of 71.90 %, achieved with neither mechanical stretching, thermal annealing, nor electrical poling.

Synthesis and Evaluation of Poly (Trifluoroethyl Methacrylate) Binders as a Polyvinylidene Fluoride Alternative for Lithium‐Ion Batteries

The binder, a critical electrode component, significantly influences lithium‐ion batteries (LIB) performance, yet remains an under‐researched area. The widespread use of polyvinylidene fluoride (PVDF) as a commercial binder is challenged by its surging cost, attributed to limited production and increased demand, highlighting the necessity for alternatives. Here, we synthesize poly (trifluoroethyl methacrylate) (PTFEMA), a polymer with a molecular weight in the million range, through a straightforward radical solution polymerization method, aiming to use it as a cathode binder for LIBs. PTFEMA demonstrate good stability across the typical operating temperatures and voltages, along with robust adhesion to the current collector. Moreover, the PTFEMA outperforms PVDF in terms of electrolyte affinity and lithium‐ion conductivity, thereby achieving capacity and stability comparable to those of its PVDF counterparts. This investigation confirms the homopolymer form of PTFEMA as a compelling alternative to PVDF, representing a valuable exploration of binder technology for LIBs.

Effect of autoclaving on the dimensional stability and surface characteristics of 3D printed PVDF composite-based implants

In the past decade, a lot of work has been reported on the use of polyvinylidene fluoride (PVDF) based thermoplastic composites as energy storage devices, and implant materials. But hitherto little has been reported on the dimensional stability and surface characteristics of 3D-printed PVDF composites after autoclaving for implant applications. In this study, the effect of autoclaving on surface characteristics (Shore-D hardness, surface roughness (Ra), morphological characteristics), and dimensional stability of 3D printed PVDF-hydroxyapatite (HAp)- chitosan (CS) composite has been reported for implant applications. The signal-to-noise (S/N) ratio approach was used to ascertain the best setting of process parameters for 3D printing by fused filament fabrication (FFF) process. This study suggests that the best setting for the FFF process, for the 3D printing of PVDF composite (90%PVDF-8%HAp-2%CS) are the nozzle temperature (NT) of 225°C, raster angle (RA) 0°, and printing speed (PS) 40 mm/s, resulting in Shore-D hardness 48.5 HD (before autoclaving) and 55.0 HD (after autoclaving), dimensional deviation 0.01 mm (after autoclaving). The results are supported by scanning electron microscopy (SEM) and Fourier transmission infrared (FTIR) spectroscopy analysis.

A “micro-explosion” strategy for preparing membranes with high porosity, permeability, and dye/salt separation efficiency

In this study, inspired by “micro-explosion” strategies, a separation membrane with high porosity and permeability, and highly efficient separation performance was prepared. With the use of polyvinylidene fluoride (Solvay6015) as membrane material, azodicarbonamide (AC) as an “explosion center point” to the casting membrane solution, and NaOH as an “external stimulus” in the coagulation bath, the two chemicals undergo in-situ foaming reaction to form a loose nanofiltration membrane. FTIR, XPS, and TGA results demonstrated that the decomposition of AC was complete, which produced gases that increased the porosity of the membrane. The optimized membrane has a higher flux (101.72 L m−2 h−1 at 0.3 Mpa), higher negative surface charge, and better mechanical properties under the premise of separating CR/NaCl. In the separation of pollutants with different molecular weights, the permeation flux of the optimized membrane increased by more than double. This foaming technology was also applied to another membrane material, ethylene vinyl alcohol, from which we found that the membrane also had higher porosity and better permeability. Together, this paper presents an in-situ foaming method for preparing separation membranes and lays the foundation for solving the trade-off between membrane permeability and rejection in dye/salt separation.

A Brief Introduction and Current State of Polyvinylidene Fluoride as an Energy Harvester

This review summarizes the current trends and developments in the field of polyvinylidene fluoride (PVDF) for use mainly as a nanogenerator. The text covers PVDF from the first steps of solution mixing, through production, to material utilization, demonstration of results, and future perspective. Specific solvents and ratios must be selected when choosing and mixing the solution. It is necessary to set exact parameters during the fabrication and define whether the material will be flexible nanofibers or a solid layer. Based on these selections, the subsequent use of PVDF and its piezoelectric properties are determined. The most common degradation phenomena and how PVDF behaves are described in the paper. This review is therefore intended to provide a basic overview not only for those who plan to start producing PVDF as energy nanogenerators, active filters, or sensors but also for those who are already knowledgeable in the production of this material and want to expand their existing expertise and current overview of the subject.

Inner Surface Hydrophilic Modification of PVDF Membrane with Tea Polyphenols/Silica Composite Coating

The use of Polyvinylidene fluoride (PVDF) membranes is constrained in wastewater treatment because of their hydrophobic nature. Therefore, a large number of researchers have been working on the hydrophilic modification of their surfaces. In this work, a superhydrophilic tea polyphenols/silica composite coating was developed by a one-step process. The composite coating can achieve not only superhydrophilic modification of the surface, but also the inner surface of the porous PVDF membrane, which endows the modified membrane with excellent water permeability. The modified membrane possesses ultrahigh water flux (15,353 L·m−2·h−1). Besides this, the modified membrane can realize a highly efficient separation of oil/water emulsions (above 96%).

Use of polyvinylidene fluoride in treatment of female stress urinary incontinence: Efficacy and safety of midurethral slings: 24-month follow-up results.

To evaluate the safety and efficacy rate of polyvinylidene fluoride (PVDF) slings in the treatment of female stress urinary incontinence (SUI). A prospective pilot study was conducted with women with SUI who underwent PVDF slings. Data regarding subjective (International Consultation on Incontinence Questionnaire - Urinary Incontinence [ICIQ-UI] and International Consultation on Incontinence Questionnaire - Overactive Bladder [ICIQ-OAB]) and objective (stress test and bladder diary) outcomes and complication rates were evaluated. Primary outcomes were objective (negative pad and stress test) and subjective (no leakage episodes) success after a median follow-up of 24 months. PVDF slings demonstrated a high level of satisfaction with objective cure (transobturator 90% compared with retropubic 100%, P = .90), urgency to urinate, frequency of de novo incontinence (transobturator 90% compared with retropubic 80%, P = .85), ability of physical and sexual activity (transobturator 90% compared with retropubic 100%, P = .90). The multivariate logistic regression model for satisfaction was associated with overall treatment success (odds ratio [OR] = 3.55, 95% confidence interval [CI] 2.32-6.1), greater reduction in ICIQ-UI (OR = 0.85; 95% CI 0.78-1.85) and ICIQ-OAB (OR =0.99; 95% CI 0.89-1.78). The total Female Sexual Function Index (FSFI) score for both groups was 19.3 ± 1.2 and 20.7 ± 1.8, statistically significant when compared with perioperative FSFI score 16.7 ± 1.1 and 17.6 ± 1.4 (P < .001). PVDF mid-urethral slings are safe with clinically efficacies at 3, 6, 12, and 24-month follow-up for the treatment of SUI. The high level of satisfaction seen after PVDF sling procedures is associated with objective improvement of SUI and fewer slings related complications. Further studies using larger sample sizes with longer and comparative clinical follow-up are required.

Use of polyvinylidene fluoride (PVDF) meshes for ventral hernia repair in emergency surgery.

The implantation of non-absorbable meshes is the gold standard technique for ventral hernia (VH) repairs. However, emergency surgeries are often related to contaminated/infected fields, where the implantation of prosthetic materials may not be recommendable. Our aim was to evaluate the results of polyvinylidene fluoride (PVDF) meshes used for contaminated and/or complicated VH repairs in the acute setting. We conducted a retrospective analysis of patients with VH who underwent emergency surgery involving PVDF meshes, in a tertiary hospital (from November 2013 to September 2019). We analyzed postoperative complications and 1-year recurrence rates. We evaluated the relationships between contamination grade, mesh placement, infectious complications, and recurrences. We gathered data on 123 patients; their mean age was 62.3years, their mean BMI was 31.1kg/m2, and their mean CeDAR index was 51.6. 96.4% of patients had a grade 2-3 ventral hernia according to the Rosen index. The mean defect width was 8cm (IQR 2-18). 93 cases (75.6%) were described as contaminated or dirty surgeries. A PVDF mesh was placed using an IPOM technique in 56.3% of cases, and via interposition location in 39.9%. The one-month recurrence rate was 5.7% and recurrence after one year was 19.1%. The overall mortality rate was 27.6%. Risk of recurrence was related to patients with a Rosen score over 2 (p < 0.001), as well as with postoperative SSI (p = 0.045). Higher recurrence rates were not related to PVDF mesh placement. The use of PVDF meshes for emergency VH repairs in contaminated surgeries seems safe and useful, with reasonable recurrence rates, and acceptable infectious complication rates, similar to those published in the literature.

Ultrasonic Transducers Shaped in Archimedean and Fibonacci Spiral: A Comparison.

We developed and investigated a particular geometry of transducers, emulating the shape of bats’ cochlea, to transmit and receive ultrasounds in the air. Their design involved the use of polyvinylidene fluoride (PVDF) as a piezoelectric material, thanks to its excellent conformability and flexibility. This material offers the primary requirements for sensing devices in applications such as sonar system or energy harvesting technology. The piezo film was folded according to both the Archimedean and Fibonacci spirals, and their performances were investigated in the frequency range from 20 kHz up to more than 80 kHz. The finite element analysis (FEA) of the proposed transducers highlighted the presence of multiple resonance vibrations, proved by the experimental measurements of the equivalent electric impedance and frequency response. Far-field radiation patterns demonstrated, horizontally and vertically, omnidirectional properties both as transmitters and receivers. All was enough to establish the best validity of the spiral shaped transducers for applications based on the bio sonar principle.

Transforming Single‐Crystal CuO/Cu2O Nanorods into Nano‐Polycrystalline Cu/Cu2O through Lithiation

AbstractOne‐dimensional single‐crystal CuO/Cu2O nanorods were fabricated by controlled oxidation of a copper substrate and examined as the active material in porous anodes for lithium‐ion batteries. Electrochemical testing against Li‐metal revealed that using sodium carboxyl methyl cellulose (CMC) as the binder enabled an excellent capacity retention for 50 cycles, while the use of polyvinylidene fluoride (PVDF) resulted in a continuous capacity fade. Transmission electron microscopy illustrated the phase composition and morphological changes throughout cycling, revealing that for both types of binders, lithiation of CuO and Cu2O disrupted the single‐crystal nanorod structure, producing multiple Cu/Cu2O nanograins within the rods. With continuous cycling the average grain size of these nanocrystals decreased. A significant difference between the CMC and PVDF binder electrodes was the irreversible formation of LiCuO during delithiation for the PVDF case, which can explain the continuous capacity fade. Scanning electron microscopy also revealed microcracks throughout the electrode surface when the PVDF binder was employed.

Study of PVDF Based Electrode Structure in Supercapacitors

Because of increasing demand there is a need for energy storage.Supercapacitor the new age energy storage device which can provide quick burst of energy. The study focuses on use of Polyvinylidene fluoride as the binder material in making of electrodes for supercapacitors. Polyvinylidene fluoride (PVDF) is a highly non-reactive thermoplastic fluoropolymer produced by the polymerization of vinylidene difluoride. It is a strong piezoelectric element. Piezoelectric effect is useful for generation of high voltages. Binder materials are responsible for holding the active material particles within the electrode. The study was focused on use of PVDF in Electric Double Layer Capacitors (EDLC) and Pseudo capacitors. In case of Electric Double Layer Capacitors the PVDF is used as binder material with activated carbon as electrode material. In case of Pseudo capacitor the PVDF is used as a binder material with activated carbon and metal oxide as electrode material. Research was performed with preparation of electrodes using 6 types of Activated carbons namely Vulcun XC 72, Pica, RP20, C60, NORIT and Graphene for different compositions. The test was conducted on single electrode and it was initially charged at a voltage of 2.2V and its discharge was recorded for a time period of 3 minutes. The research focuses on the material which is giving the best results in regarding to the key parameters of supercapacitors and also concentrates on the composition of Polyvinylidene fluoride (PVDF) which gives the highest value of capacitance with the lowest value of Equivalent series resistance in making electrodes for supercapacitors.

Fully-coupled piezoelectric assumed-strain least-squares nonlinear shell

Relevance of finite strain shell piezoelectric analysis is significant due to the general use of polyvinylidene fluoride (PVDF). A finite-strain geometrically exact shell model for the analysis of piezoelectric laminated structures is introduced. An assumed-strain formulation is employed, with least-squares fitting of contravariant linear stress fields. This allows the condensation of internal degrees-of-freedom corresponding to the assumed strains. The resulting piezoelectric shell has 8 degrees-of-freedom in each node, with 3 position/displacement degrees-of-freedom, 3 rotation parameters and the upper and lower electrostatic potential at the nodes. This contrasts with available formulations where only one electric degree-of-freedom is considered. A total of 32 degrees-of-freedom in each 4-node element are used. In term of implementation, we use a generalized strain and generalized stress formulation to reproduce the conventional finite element organization. Six examples are presented, with transversely isotropic and orthotropic cases, including finite strains and asymmetric plies. Results show a remarkably good agreement with the sources and we achieve higher values of actuation.

The Continuous Monitoring of the Health of Composite Structure

Currently nondestructive testing techniques for composite aircraft structures are disadvantaged when compared to instant structural health monitoring (SHM) systems that monitor the structure while being in-service and give real-time data. This paper reports on the use of Polyvinylidene Fluoride (PVDF) sensors in sensing (or monitoring) and locating the defect of a flexible composite structure. The samples used for the tests were manufactured through the use of vacuum infusion process. The three-point bending test was performed to determine the material properties. The vertical sample deflection was measured through the use of vertical height Vernier. It should be noted that the samples were analyzed as cantilever beam due to limited availability of test equipment. The sample health was monitored through the use of PVDF sensor. The sensor data was logged and recorded through the use of Fluke-View scopemeter. The 50 g mass pieces were used as a mode of subjecting the structure to the vertical load. The experiment was performed on samples with defects (drilled 3 mm hole) sample and no-defected sample. The deflection and output voltage from the PVDF sensor of all the samples were comparatively studied.

Polyvinylidene fluoride effects on the electrocatalytic properties of air cathodes in microbial fuel cells

The use of polyvinylidene fluoride (PVDF) as a binder was investigated in order to prepare the active carbon catalyst and carbon black diffusion layers of a microbial fuel cell cathode. Compared with other binders, PVDF performed competitively as it did not require a lengthy curing time and high curing temperature. Results of XRD characterization showed that the typical β-PVDF was enhanced as PVDF content ratio increased. SEM results indicated that the catalyst layer easily peeled off due to the low binder concentration of binder, but the high binder content was deemed undesirable because the large amount of non-conductive PVDF interrupted the percolation path. The optimum binder concentration was double checked using Tafel and EIS tests. Results indicated that the cathode with 10% PVDF is the optimum operated concentration. The cathode can obtain 180mV of cathode potential and the smallest total impedance of 2500Ω, which are consistent with the SEM analysis. Moreover, the cathode with 10% PVDF concentration produced a maximum power density of 1600mWm−2, suggesting that PVDF can compete with other traditional binders.

Polyvinylidene Fluoride Micropore Membranes as Solid-Phase Extraction Disk for Preconcentration of Nanoparticulate Silver in Environmental Waters.

Efficient separation and preconcentration of trace nanoparticulate silver (NAg) from large-volume environmental waters is a prerequisite for reliable analysis and therefore understanding the environmental processes of silver nanoparticles (AgNPs). Herein, we report the novel use of polyvinylidene fluoride (PVDF) filter membrane for disk-based solid phase extraction (SPE) of NAg in 1 L of water samples with the disk-based SPE system, which consists of a syringe pump and a syringe filter holder to embed the filter membrane. While the PVDF membrane can selectively adsorb NAg in the presence of Ag+, aqueous solution of 2% (m/v) FL-70 is found to efficiently elute NAg. Analysis of NAg is performed following optimization of filter membrane and elution conditions with an enrichment factor of 1000. Additionally, transmission electron microscopy (TEM), UV-vis spectroscopy, and size-exclusion chromatography coupled with ICP-MS (SEC-ICP-MS) analysis showed that the extraction gives rise to no change in NAg size or shape, making this method attractive for practical applications. Furthermore, feasibility of the protocol is verified by applying it to extract NAg in four real waters with recoveries of 62.2-80.2% at 0.056-0.58 μg/L spiked levels. This work will facilitate robust studies of trace NAg transformation and their hazard assessments in the environment.

Characterization of single polyvinylidene fluoride (PVDF) nanofiber for flow sensing applications

The use of Polyvinylidene Fluoride (PVDF) based piezoelectric nanofibers for sensing and actuation has been reported widely in the past. However, in most cases, PVDF piezoelectric nanofiber mats have been used for sensing applications. This work fundamentally characterizes a single electrospun PVDF nanofiber and demonstrates its application as a sensing element for nanoelectromechanical sensors (NEMS). PVDF nanofiber mats were spun by far field electrospinning (FFES) process and complete material characterization was conducted by means of scanning electron microscope (SEM) imaging, Raman Spectroscopy and FTIR spectroscopy. An optimized recipe was developed for spinning a single suspended nanofiber on a specially designed MEMS substrate which allows the nano-mechanical and electrical characterization of a single PVDF nanofiber. Electrical characterization is conducted using a single suspended nanofiber to determine the piezoelectric coefficient (d33) of the nanofiber to be -58.77 pm/V. Also the mechanical characterization conducted using a nanoindenter revealed a Young’s Modulus and hardness of 2.2 GPa and 0.1 GPa respectively. Finally, an application that utilizes the single PVDF nanofiber as a sensing element to form a NEMS flow sensor is demonstrated. The single nanofiber flow sensor is tested in presence of various oscillatory flow conditions.

New eco-friendly low-cost binders for Li-ion anodes

In the production of commercial Li-ion batteries, the active materials slurries are generally prepared using polyvinylidene fluoride (PVdF) as binder because of its good adhesion properties and electrochemical stability. Unfortunately, there are some disadvantages related to the use of PVdF: the most important is the use of toxic and environmentally unfriendly solvents, such as N-methyl-pyrrolidone (NMP), and the second is the high costs. In the light of these considerations, it seemed straightforward to investigate the suitability of some water-soluble, inexpensive, and eco-friendly materials to test as alternative binders (sodium alginate, chitosan tragacanth gum, gelatin). The rheological properties of these materials have been investigated in addition to the electrochemical characterization. Furthermore, graphite electrodes with PVdF, carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) binders have been considered for sake of comparison. We found that some of these water-soluble binders, besides good electrochemical performances, showed a high adhesion to the current collector and a good electrochemical stability under the experimental conditions employed, which makes them interesting for the next generation of Li-ion batteries.

Polyvinylidene Fluoride Derived Carbon As High Performance Anode Material for Lithium Ion Batteries

Introduction Polyvinylidene fluoride (PVDF) is a fluoropolymer which consists of vinylidene fluoride as a monomer. Conventionally, it is widely used material in electrode preparation as a binder between active carbon material and the current collector. However in this work, we propose the use of PVDF as a polymer precursor to carbon. In literature, PVDF was used as precursor for carbon with ~20% yield.1 However, this yield was increased to ~70% by dehydrofluorination of PVDF prior to pyrolysis.2,3 In our present work, we first carried out dehydrofluorination followed by pyrolysis at different temperatures (900, 1200 and 1400 ⁰C respectively) to obtain the hard carbon as characterization by field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and high resolution transmission electron microscopy. Later, electrochemical performance of these hard carbons pyrolyzed at different pyrolysis temperature was investigated at different current densities. Experimental Section: PVDF powder was dehydrofluorinated in NaOH and Tetra-n-butylammoniumbromide solution. Dehydrofluorinated powder was pyrolyzed in inert atmosphere at different final pyrolysis temperature. Slurry made of this carbon was coated over stainless steel foil and dried for 12 h in a vacuum oven prior to cell packing in argon atmosphere glove box. Electrochemical performance was studied using glavanostat/potentiostat. Results and discussions: Figure 1: (a,b) HRTEM images of CDI-1400 at different magnifications; (c) Comparison of cycling behaviour at 0.1 C rate for carbonized samples for different temperature TEM images (Figure 1a and 1b) clearly reveals that particle size is 290 nm and inside the each spherical particle, there are disordered areas consists of randomly arranged smaller crystallites of graphene. From this, we can conclude that carbon derived from PVDF precursor is a hard carbon. From Figure 1c, we observe that the sample pyrolyzed at 1400 ⁰C exhibited higher reversible capacity (297 mAh/g) than the other two samples (pyrolyzed at 900 ⁰C and 1200 ⁰C) after 11 cycles of charge-discharge at 0.1 C rate. The coulombic efficiency was found to be more than 94 % after 11 cycles for all three samples. A detailed analysis on dehydroflorination and charge discharge experiments at different current densities will be presented at conference. Cyclic voltammetry and impedance studies will also be presented to support the cyclic stability and capacity retention values.

Effect of electron beam irradiation on the capacity fading of hydride-terminated silicon nanocrystal based anode materials for lithium ion batteries

Abstract The selection of binder is extremely important in silicon based lithium-ion batteries (LIBs). Polyvinylidene fluoride (PVDF) has been used as a commercial binder. However, it does not accommodate a large change in volume during cell cycling. In this study, we report on the rediscovery of the use of PVDF without additional synthetic processes or further treatment. By utilizing simple and short e-beam irradiation, hydride-terminated silicon nanocrystals (H-Si NCs) and PVDF can be chemically cross-linked each other, and shows an improved cell performance. This result demonstrates a high potential of the e-beam irradiation process on Si-based anode materials in LIBs.