Search

An innovative approach has been adopted through the synthesis of a cost‐effective ferroelectric host polymer, which was integrated with Barium Titanate (BaTiO3) to develop an efficient electrospun Polyvinylidene Fluoride‐Hexafluoropropylene/BaTiO3 (PVdF‐HFP/BaTiO3) nanocomposite (PBT), designated for energy harvesting and piezocatalytic applications. FT‐IR affirmed the existence of the crystalline β‐phase within the nanofibers. SEM images showed that nanofiber diameter decreases as applied voltage is increased in electrospinning. The BaTiO3 nanoparticles were scattered evenly in PBT, but at lower voltages, they aggregate. PBT showed enhanced piezoelectric performance under higher voltage conditions, registering a maximum piezoelectric output of ~7.7 V and an output current of 0.77 μA. Moreover, the composite exhibited a power density of 14.15 mW/m2 at a load resistance of 20 MΩ. Fabricated piezoelectric nanogenerator (PENG) demonstrated practical utility in flexible electronics, notably in charging capacitors of 0.47 μF and 1 μF. Additionally, the piezocatalytic degradation of the antibiotic ciprofloxacin (CIP) was effectively achieved using the electrospun nanofibers, with an impressive degradation rate of up to 99.6 % within 30 minutes under acidic conditions, and the material displayed notable reusability, maintaining up to 95.5 % efficiency after five cycles. DFT calculations and COMSOL simulations alongside a comparative examination of the electronic properties of PBT. [ABSTRACT FROM AUTHOR]

This work focuses on the development of a composite polymer electrolyte (CPE) for all‐solid‐state lithium metal batteries (ASSLMBs), integrating LLTO nanofibers into a PEO (polyethylene oxide)‐PVDF‐HFP (poly(vinylidene fluoride‐cohexafluoropropylene)) matrix with LiClO4 as the lithium salt. The PEO has high ionic conductivity and flexibility, and the PVDF‐HFP has high mechanical strength and electrochemical stability. Therefore, the resulting composite has improved electrochemical performance and mechanical properties. Incorporating LLTO nanofibers enhances ionic conductivity due to the one‐dimensional ion transport pathways provided by the nanofibers while maintaining mechanical integrity and air stability, overcoming the challenges associated with conventional fillers. The prepared CPE demonstrates exceptional electrochemical stability up to 5.1 V versus Li/Li+, making it suitable for high‐voltage applications over traditional polymer electrolytes. The optimized CPE with 15 wt% LLTO provides the ionic conductivity of 1.1 × 10−5 S cm−1 at room temperature and reaches 1.46 × 10−4 S cm−1 at 80°C. The assembled LiNi1/3Mn1/3Co1/3PO4||PEO‐PVDF‐HFP‐LiClO₄‐LLTO||Li based 2032 coin cell worked in between 3 and 4.8 V versus Li/Li+ potential window without any electrolyte decomposition from 0.5 to 5 mV/s scan rates. Similarly, the fabricated LiFePO₄||PEO‐PVDF‐HFP (1:2)‐LiClO4‐LLTO (15 wt%)||Li cell provides an initial capacity of 149 mAh g−1 at 0.1 C and 85 mAh g−1 at 0.5 C, exploring its potential for lithium metal batteries. Overall, this work offers a promising pathway for developing advanced solid polymer electrolytes for next‐generation lithium metal batteries, which combine high ionic conductivity, excellent electrochemical performances, and robust mechanical properties. [ABSTRACT FROM AUTHOR]

A simple solution casting technique was used to formulate films of polyvinylidenefluoride‐co‐hexafluoropropylene, polymethylmethacrylate, and Ti3AlC2 MAX phase polymer nanocomposites (PPT) with different filler content. The functional groups present in the PPT films were studied using the Fourier transform infrared spectroscopy and the nature of crystallinity was observed using X‐ray diffraction technique. The morphology of the films was studied by scanning electron microscopy. The thermal analysis was done using the thermogravimetric analysis and differential thermogravimetry analysis. The tensile behavior of the prepared films was studied from the stress‐strain graphs. The ultraviolet–visible spectra revealed their optical characteristics. The dielectric parameters of the polymer blend and nanocomposite films like dielectric constant, loss tangent, AC conductivity, and complex impedance spectroscopy with corresponding equivalent circuits were studied. A comparative study of the above parameters was done for both the polymer blend and nanocomposites to find out the advancement in the properties of the prepared nanocomposite compared with the polymer blend. The nanocomposite film having 3 wt% of Ti3AlC2 MAX phase filler loading exhibited the best properties among all the nanocomposites. The enhanced dielectric properties of the nanocomposites with mechanical and thermal resistance can be used for real‐time efficient energy storage applications. [ABSTRACT FROM AUTHOR]

Membrane wetting caused by substances in the feed solution with low surface tension has posed serious issues for membrane distillation (MD). Omniphobic membranes could be helpful when dealing with this problem because they strongly repel liquids with a wide range of surface tensions. We fabricated electrospun omniphobic membranes containing PVDF‐TEOS‐PFDTMS, PVDF‐HFP‐TMOS‐PFDTMS, and PVDF‐HFP‐TEOS‐PFDTMS. All electrospun membranes have shown contact angles >90°, but the electrospun membrane containing PVDF‐HFP‐TEOS‐PFDTMS has shown super repellence with a contact angle >150° and maintains stable salt rejection and water flux in direct contact MD processes in the presence of sodium dodecyl sulfate surfactant (up to 0.3 mM). Furthermore, the morphology and crystallinity of the electrospun membranes were studied by scanning electron microscopy and Fourier‐transform infrared spectroscopy, and the percentage composition of elements was analyzed by x‐ray photoelectron spectroscopy. liquid entry pressure, mechanical strength, and the porosity of the electrospun omniphobic membranes were also studied. [ABSTRACT FROM AUTHOR]

Highlights Flexible sensors, made of PVDF‐HFP reinforced with carbon nanotubes (CNTs), are manufactured by solvent casting. More specifically, the effect of evaporation temperature and sonication time is explored. It is seen that two effects govern the dispersion of CNT: the sedimentation half‐time, and the breakage induced by the ultrasonication process. In this regard, it is found that 60°C is an optimum evaporation temperature to reach the highest value of electrical conductivity, since it offers a good balance between these effects, leading to the creation of a more efficient electrical network. This is also confirmed by the AC analysis, where these samples show the highest characteristic frequencies. The electromechanical results show a greater dependency on evaporation temperature for low sonication times, as the breakage induced by an ultrasonic process is not so pronounced and, therefore, the sedimentation effect plays a more dominant role. In addition, cycling tests show robust electromechanical response with cycling, and creep tests prove good electrical response of the sensors, less than 200 ms in some cases. Finally, proof of concept testing of wrist, shoulder, and neck monitoring highlights the potential of the proposed materials for sensing applications. PVDF‐HFP/CNT nanocomposite strain sensors via solvent casting are proposed. The effect of evaporation temperature and sonication time is studied. DC and AC conductivities were analyzed and modeled via an equivalent circuit. An outstanding Gauge Factor of 86.30 × 104 is achieved at 95% of strain level. Two proof‐of‐concepts of medium and large movements are successfully achieved. [ABSTRACT FROM AUTHOR]

In today's technological landscape, advancing methods for producing conductive membranes that simplify and streamline the development of advanced interface materials is crucial. This study introduces a versatile and innovative method for fabricating superhydrophilic, conductive nanofibrous membranes based on the in situ synthesis of polypyrrole nanoparticles on poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) electrospun fibers. The composite membranes morphologically exhibit a particle‐decorated nanofibrous configuration, with polypyrrole nanoparticles distributed along the individual fibers' surface. The nanoparticle‐nanofiber configuration shows distinctive properties; electrochemically, the electrospun mats demonstrate excellent inherent electrical conductivity, good cyclic and high electrochemical stability, and low resistance. Furthermore, the amphiphilic and superhydrophilic behavior, achieved through nanotopography, porosity and interactions between the intrinsically conductive polymer and the PVDF‐HFP fibers, enables efficient uptake of polar and nonpolar analytes. The membranes also demonstrate good in vitro cell viability of both murine and human fibroblasts. Given its efficient interaction with liquids and omnidirectional 360‐degree conductivity, this material emerges as an excellent candidate for use as a biocompatible, multifunctional interface layer. The produced nanoparticle‐nanofibrous membrane materials offer a promising platform for interface applications, featuring enhanced spatiotemporal configurations and wide‐ranging applicability. [ABSTRACT FROM AUTHOR]

For enhanced security in hardware‐based security devices, it is essential to extract various independent characteristics from a single device to generate multiple keys based on specific values. Additionally, the secure destruction of authentication information is crucial for the integrity of the data. Doped amorphous indium gallium zinc oxide (a‐IGZO) thin‐film transistors (TFTs) using poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) induce a dipole doping effect through a phase‐transition process, creating physically unclonable function (PUF) devices for secure user information protection. The PUF security key, generated at VGS = 20 V in a 20 × 10 grid, demonstrates uniformity of 42% and inter‐Hamming distance (inter‐HD) of 49.79% in the β‐phase of PVDF‐HFP. However, in the γ‐phase, the uniformity drops to 22.5%, and inter‐HD decreases to 35.74%, indicating potential security key destruction during the phase transition. To enhance security, a multi‐factor authentication (MFA) system is integrated, utilizing five security keys extracted from various TFT parameters. The security keys from turn‐on voltage (VON), VGS = 20 V, VGS = 30 V, mobility, and threshold voltage (Vth) exhibit near‐ideal uniformities and inter‐HDs, with the highest values of 58% and 51.68%, respectively. The dual security system, combining phase transition and MFA, establishes a robust protection mechanism for privacy‐sensitive user information. [ABSTRACT FROM AUTHOR]

In this paper, a high‐performance composite nanofiber membrane with excellent air filtration and dye degradation properties was prepared by incorporating MIL‐53(Fe) nanoparticles into the electrospinning solution. The results showed that the filtration efficiency for PM2.5 of the PP/PVDF‐HFP/MIL‐53(Fe) composite nanofiber membrane reached up to 99.3% with the addition of 2 wt% MIL‐53(Fe). Moreover, the composite nanofiber membrane exhibited steady filtration efficiency across different parameters, including air velocity, PM2.5 concentration, and extended testing time. Furthermore, the incorporation of MIL‐53(Fe) significantly enhanced the removal efficiency of the composite nanofiber membrane toward Rh B, resulting in a remarkable 91% removal rate. The polymer/MOF composite nanofiber membranes prepared by simple and cheap electrospinning technology have a wide range of practical applications in the field of environmental protection. Highlights: PPM composite nanofiber membrane was prepared via electrospinning method.MIL‐53(Fe) nanoparticles were introduced to PPM composite nanofiber membrane.PPM composite nanofiber membrane showed excellent removal efficiency for PM2.5.PPM composite nanofiber showed a good removal performance for RhB in solution. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride‐hexafluoropropylene (PVDF‐HFP) is a standard electrolyte membrane and binder material for lithium‐ion batteries (LIBs) because of the benefits of membrane formation and strong mechanical properties. Still, its use is limited due to unavoidable defects such as high crystallinity and poor electrochemical performance. In this paper, a larger specific surface area and three‐dimensional (3D) permeable lamellae carboxylated g‐C3N4 (HCN) were successfully prepared by HNO3 and introduced into the PVDF‐HFP to obtain a high‐performance composite separator. The wettability and electrolyte absorption of PVDF‐HFP separator can be improved through the carboxylated HCN. More crucially, because PVDF‐HFP has several active sites and low crystallinity, adding HCN can greatly increase the ionic conductivity of separators. The ionic conductivity of PH‐HCN at 25 °C is 0.52 S cm−1, 4.7 times higher than the initial PVDF‐HFP membrane, and the oxidation potential can reach 4.8 V. The assembled lithium‐ion batteries half‐cell has a capacity of 71 % at a 5 C rate and 94 % after 400 cycles at a 2 C rate. Therefore, the improved separator has the potential to be applied to high‐performance LIBs. [ABSTRACT FROM AUTHOR]

Solid polymer electrolyte (SPE) films based on poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF–HFP) with salt and ionic‐liquid (IL) are synthesized using the solution‐cast technique and summarized in this review. Doping ILs or salts increases ionic conductivity up to the device level. This is further confirmed using differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) measurements. Polarized optical microscopy (POM) affirms that enhancement in ionic conductivity is due to increase in amorphous nature of film. The complex nature of polymer electrolyte films is confirmed using Fourier transform infrared (FT‐IR) spectroscopy. Overall results show that doping IL into polyether matrix is advantageous material playing a dominant role in electrochemical devices. [ABSTRACT FROM AUTHOR]

In this work, poly(vinylidene fluoride‐hexafluoropropylene) (PVDF‐HFP)/mesoporous graphitic carbon nitride (mpg‐C3N4) composite fiber web have been prepared and characterized for photocatalytic methylene blue (MB) degradation and sensing applications. The electrospinning technique, operating at a flow rate of 1 mL/h and a voltage of 15 kV, was utilized to prepare the composite membranes of PVDF‐HFP with the uniform distribution of the mpg‐C3N4. The composite web demonstrated outstanding photocatalytic activity for the degradation of MB, reaching a quick 68% drop in MB concentration in just 45 min. The composite web furthermore worked as a sensor for MB detection. After MB exposure, the film resistance was increased, suggesting its potential as a chemiresistive sensor. The maximum resistivity of PVDF‐HFP/mpg‐C3N4 composites was found to be 90 Ω·m at 2% concentration of MB. The MB molecules' adsorption on the surface of the composite web and the existence of photocatalytic byproducts on the surface may be responsible for this shift in resistance. This dual functionality highlights the adaptability and potential of the PVDF‐HFP/mpg‐C3N4 composite web as a versatile material for environmental sensing and cleanup. This research presents a comprehensive approach to the synthesis, characterization, and evaluation of such flexible membranes for potential applications as self‐cleaning devices and chemiresistive sensor. Highlights: PVDF‐HFP/mpg‐C3N4 composite membranes act as an efficient material for MB degradation (68%) with visible light exposure.mpg‐C3N4 plays the role of active material in degradation.PVDF‐HFP/mpg‐C3N4 composite membrane also act as sensors for MB detection.Composite membrane becomes chemiresistive due to notable resistivity changes with MB concentration. [ABSTRACT FROM AUTHOR]

Piezoelectric ceramic and polymeric separators have been proposed to effectively regulate Li deposition and suppress dendrite growth, but such separators still fail to satisfactorily support durable operation of lithium metal batteries owing to the fragile ceramic layer or low‐piezoelectricity polymer as employed. Herein, by combining PVDF‐HFP and ferroelectric BaTiO3, we develop a homogeneous, single‐layer composite separator with strong piezoelectric effects to inhibit dendrite growth while maintaining high mechanical strength. As squeezed by local protrusion, the polarized PVDF‐HFP/BaTiO3 composite separator generates a local voltage to suppress the local‐intensified electric field and further deconcentrate regional lithium‐ion flux to retard lithium deposition on the protrusion, hence enabling a smoother and more compact lithium deposition morphology than the unpoled composite separator and the pure PVDF‐HFP separator, especially at high rates. Remarkably, the homogeneous incorporation of BaTiO3 highly improves the piezoelectric performances of the separator with residual polarization of 0.086 μC cm−2 after polarization treatment, four times that of the pure PVDF‐HFP separator, and simultaneously increases the transference number of lithium‐ion from 0.45 to 0.57. Beneficial from the prominent piezoelectric mechanism, the polarized PVDF‐HFP/BaTiO3 composite separator enables stable cyclic performances of Li||LiFePO4 cells for 400 cycles at 2 C (1 C = 170 mA g−1) with a capacity retention above 99%, and for 600 cycles at 5 C with a capacity retention over 85%. [ABSTRACT FROM AUTHOR]

Iron oxide (Fe2O3) nanoparticles (NPs), graphene nanoplatelets (GNPs), and nanodiamonds (NDs) reinforced poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) nanocomposites were synthesized by a solvent casting technique. The structure and morphology of synthesized nanocomposites were studied using Fourier‐transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy. The thermal behavior of polymer nanocomposites (PNCs) was studied by the thermogravimetric analysis and the derivative thermogravimetry. The dielectric measurements were carried out within the temperature range from 40 to 150°C and in the frequency range from 50 Hz to 15 MHz. At 50 Hz, 140°C, the highest dielectric constant of 92.46 was noted, for the PVDF‐HFP + 10 wt% Fe2O3 + 6 wt% GNPs + 3 wt% NDs and the highest dielectric loss tangent has been observed to be 24.75 at 50 Hz, 140°C for the PVDF‐HFP + 10 wt% Fe2O3 + 4 wt% GNPs + 2 wt% NDs. The electromagnetic interference shielding effectiveness (EMI SE) was studied in the X‐band and Ku‐band frequency regions (8–18 GHz). High EMI SE values of 31.60 dB and 34 dB were observed for PVDF‐HFP/Fe2O3/GNPs/NDs nanocomposites with 10 wt% Fe2O3 + 8 wt% GNPs + 4 wt% NDs in X‐band and Ku‐band, respectively. These findings suggests PVDF‐HFP/Fe2O3/GNPs/NDs‐based PNCs as an appealing material for EMI shielding applications. [ABSTRACT FROM AUTHOR]

Nanocomposite solid polymer electrolytes (NSPEs) with PVDF‐HFP/Pluronic as blend polymer matrix, graphene oxide (GO) as nanofiller, and LiClO4 are reported. FTIR spectroscopy reveals the crystal phase transformation of PVDF‐HFP from nonpolar α phase to electroactive γ phase upon salt addition that suggests the ion‐dipole interaction between the salt and the matrix. Further, Pluronic not only hinders the PVDF crystallization that increases the amorphous character of the matrix but also interacts with the salt and hence assists in salt dissociation in the blend matrix. The dc conductivity of PVDF‐HFP/Pluronic/LiClO4 blend SPE improves with increasing the Pluronic content reaching 0.73 × 10−6 Scm−1 at room temperature with 60 wt.% Pluronic. The dispersion of GO in the same blend SPE leads to a significant jump in room temperature ion conductivity (≈1.2 × 10−6 Scm−1) with 0.4% GO. Temperature‐dependent ion conductivity of the NSPEs reveals an Arrhenius type thermally activated process. The dc polarization data indicates that the conductivity is predominantly due to ions. Impedance plots exhibit a distorted semicircle at higher frequency and a tilted spike at lower frequency. The spike is an indication of ion diffusion and electrode polarization effect. Further, GO also has enhanced the mechanical properties of the fabricated NSPEs. [ABSTRACT FROM AUTHOR]

Polymer electrolytes are being considered as an effective solution for electrochemical devices to replace currently used organic liquid electrolytes due to their excellent mechanical properties and security. Herein, we prepared stretchable polymer electrolytes (SPEs) doped with poly[(2‐acrylamido‐2‐methylpropanesulfonic acid)‐co‐poly(ethylene glycol) dimethacrylate] (P(AMPS‐co‐PEGMA)) and enhanced with poly[(vinylidene fluoride)‐co‐hexafluoropropylene] (PVDF‐HFP), through UV in situ polymerization. The SPEs showed good mechanical performance with an elongation of more than 40% and ionic conductivity reaching the order of 10−3 S cm−1. In terms of application, flexible electrochromic devices based on the UV in situ‐prepared SPEs were assembled, the color switching performance being still good even after 400 switching cycles and 1000 bending cycles, which indicated that the SPEs could have excellent prospects in application for flexible devices. © 2023 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

In this work, montmorillonite (MMT) nanoclay and graphene quantum dots (GQDs) embedded poly (vinylidenefluoride‐co‐hexafluoropropylene) (PVDF‐HFP) nanocomposite films were prepared using the solution‐casting technique and characterized using Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), Scanning electron microscopy (SEM) and Atomic force microscopy (AFM). The thermal, mechanical and dielectric properties of PVDF‐HFP/MMT/GQDs nanocomposite films were also investigated. The dielectric constant (ɛ′), dielectric loss (ɛ″) and conductivity (σ) of synthesized nanocomposite films were evaluated in the frequency and temperature range f100 Hz–1 MHz and 30–150°C, respectively. The highest ɛ′ with relatively high ɛ″ was achieved at low frequency for increasing temperature for all the nanocomposite films. The conductivity results showed good increment from lower to higher frequency up to 100 kHz at increasing temperature. The Cole–Cole plots represent the complex impedance of PVDF‐HFP/MMT/GQDs nanocomposites at 150°C. The attained results imply that the PVDF‐HFP/MMT/GQDs nanocomposite films can be useful candidates for flexible electronic devices. [ABSTRACT FROM AUTHOR]

Gel polymer electrolytes (GPEs) incorporate both the high ionic conductivity of organic liquid electrolyte and the high safety performance of all‐solid‐state electrolytes (ASSEs), greatly improving the electrochemical performance of solid polymer electrolytes (SPEs). However, the practical application of GPEs is still limited by inferior interface compatibility, lithium dendrites, etc. Herein, we prepared GPEs based on poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) further co‐blended the two‐dimensional sheet inorganic filler hectorite and poly(methyl methacrylate) (PMMA) to improve the mechanical and electrochemical properties of the GPEs. When the content of PMMA and hectorite is optimal, this GPEs have an ionic conductivity of 1.06×10−3 S cm−1 and outstanding lithium symmetric cells cycle time of more than 3000 h, indicating that the introduction of filler effectively inhibits the growth of lithium dendrites at room temperature. Moreover, the GPEs adopt a relatively simple solution casting method to provide a fresh idea for the synthesis of high‐performance GPEs. [ABSTRACT FROM AUTHOR]

This paper presents and compares films made using the solution casting method with a mixture of poly (vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP), graphene oxide (GO), and lead zirconate titanate (PZT). The Hummers' method synthesized GO. Scanning electron microscopy (SEM), Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and tensile testing were realized. The developed composite films were found to have a coherent distribution of PZT and GO in PVDF‐HFP. After that, a gradual improvement, such as an increase in the quantity of β phase, produces high piezoelectric performance. Also, the PVDF‐HFP polymer's thermal stability improved. When 0.1 wt% of PZT/GO was added, the melting temperature increased from 140 to 143°C, and the crystallization temperature from 109 to 113°C. PVDF‐HFP elastic modulus and tensile strength were also considerably reduced as PZT/GO increased. As a result, this has enabled us to develop composite films with important properties that can be used as piezoelectric materials for energy harvesting. [ABSTRACT FROM AUTHOR]

Benefiting from employing solid composite electrolytes (SCEs), all‐solid‐state lithium‐ion batteries (ASSLBs) are recognized to occupy with high energy density and safety. Herein, a polymer‐based SCE membrane (SCE‐66@67) with core–shell structured metal–organic frameworks (MOFs) (UiO‐66‐NH2@67) as the fillers is presented. The SCE has combined the advantages of the two kinds of MOFs and shows a satisfying ionic conductivity (2.09 × 10−4 S cm−1 at 60 °C) and a wide electrochemical stability window of ≈5.0 V. The full cell (Li/SCE‐66@67/LiFePO4) also maintains a high capacity of 120.9 mAh g−1 at 3 C. This research might help to promote the development of future SCEs for ASSLBs. [ABSTRACT FROM AUTHOR]

Lithium metal is considered as the most potential anode for next generational high energy density lithium‐ion battery. But due to high activity, the whole manufacturing process of LMA must be protected by inert gas and placed in dry environment, which will increase the significant production cost. The security risk is also increased once unexpected overheating happens. Therefore, prior to the practical application of LMA, these critical issues should be solved. A flame retardant, triphenyl phosphate (TPP), is introduced in this paper. When used as a protective layer on the surface of LMA, it can improve air tolerance of LMA even in a RH 70 % environment. In addition, PVDF‐HFP/TPP complex separator can be constructed via blade casting process, which plays an efficient role in increasing heat stability and flame retardancy. And more meaningfully, the composite separator is expected to form a coating layer by hot‐rolling with LMA, enabling LMA remain stable while in regular production environment. Such a strategy has the function of cutting costs and high temperature protection. [ABSTRACT FROM AUTHOR]

Chlorophyll natural dye is deemed as an attractive alternative to the expensive and toxic nature Ruthenium‐based dyes, due to its abundance in nature. In this work, the chlorophyll is extracted from the Caulerpa lentillifera seaweed. The absorption spectrum of C. lentillifera shows absorbance in 400–450 and 650–700 nm. The acetone produces the highest yield for the C. lentillifera seaweed, followed by ethanol and methanol. The adherence of chlorophyll pigment to the surface of TiO2 is supported by the FTIR, FESEM, and EDX analyses. Dye‐sensitized solar cells (DSSCs) are fabricated with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐HFP) based gel‐like electrolyte and chlorophyll from C. lentillifera seaweed. The effect of the thickness of the TiO2 mesoporous layer on the light harvesting ability of DSSCs is monitored. The highest efficiency of 0.20% is achieved with a short‐circuit current density (Jsc) of 0.52 mA cm−2, the open circuit voltage (Voc) of 0.58 V and the fill factor (ff) of 0.65. The stability of C. lentillifera seaweed extract in DSSCs is reported. [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes (SPEs) represent one of the most suitable options to overcome durability and safety issues. Herein, three‐component SPEs based on poly(vinylidene fluoride‐co‐hexafluoropropylene) as a binder, the 1‐butyl‐3‐methylimidazolium thiocyanate ionic liquid as an ionic conductive component, and zeolites, to improve SPE ionic conductivity and electrochemical stability, are prepared and characterized. Different zeolite and zeolite‐like structures (clinoptilolite, ETS‐4, and ETS‐10) are used, and the effect of lithium‐ion exchange in their structures is evaluated. A clear influence of the ion exchange process on the crystallinity of the prepared samples is observed, which plays a key role in the conduction mechanisms. The ionic conductivity of the samples at room temperature is of the order of 10−3 S cm−1, making them suitable for battery applications. The assembled batteries show promising results at room temperature, proving that the ion exchange has a positive effect on battery performance. The ion‐exchanged clinoptilolite sample presents the best performance at a prolonged cycle number, with an initial discharge capacity of about 130 mAh g−1 at C/10, and a capacity retention of 70% after 50 cycles. Thus, it is proved that the ion exchange process in microporous silicates represents a suitable strategy to develop high‐performance solid‐state lithium‐ion batteries (LIBs). [ABSTRACT FROM AUTHOR]

Lithium metal batteries (LMBs) show several limitations, such as high flammability and Li dendrite growth. All‐solid‐state LMBs (ASSLMBs) are promising alternatives to conventional liquid electrolyte (LE)‐based LMBs. However, it is challenging to prepare a solid electrolyte with both high ionic conductivity and low electrode–electrolyte interfacial resistance. In this study, to overcome these problems, a solid composite electrolyte (SCE) consisting of Li6.25La3Zr2Al0.25O12 and polyvinylidene fluoride‐co‐hexafluoropropylene is used, which has attracted considerable attention in recent years as a solid‐state electrolyte. To operate LMBs without an LE, optimization of the electrode–solid‐electrolyte interface is crucial. To achieve this, physical and chemical treatments are performed, i.e., direct growth of each layer by drop casting and thermal evaporation, and plasma treatment before the Li evaporation process, respectively. The optimized ASSLMB (amorphous V2O5−x (1 µm)/SCE (30 µm)/Li film (10 µm)) has a high discharge capacity of 136.13 mAh g−1 (at 50 °C and 5 C), which is 90% of that of an LMB with an LE. It also shows good cycling performance (>99%) over 1000 cycles. Thus, the proposed design minimizes the electrode–solid‐electrolyte interfacial resistance, and is expected to be suitable for integration with existing commercial processes. [ABSTRACT FROM AUTHOR]

Poly(ethylene oxide) (PEO)‐based polymer electrolyte has widely been considered as a promising material for high‐performance lithium metal batteries (LMBs) owing to the high safety, low cost, and excellent electrochemical stability. However, PEO‐based solid polymer electrolyte (SPE) has always been suffered with a poor mechanical strength and low room‐temperature ionic conductivity owing to its highly crystalline ethylene oxide (EO) chains. Especially, PEO‐based SPE exhibits an unstable framework at elevated temperature (exceed melting temperature), thus leading to the poor electrochemical performances. Here, the electrospun composite polymer membrane (CPM) based on poly(vinylidene fluoride‐hexafluoropropylene) (PVDF‐HFP) is fabricated by introduction of silica‐coated silver nanowires (AgNWs@SiO2). The PEO/LiTFSI is incorporated into the obtained PVDF‐HFP/AgNWs@SiO2 CPM to form the PEO‐based SPE. The composite polymer electrolyte membrane (CPEM) exhibits a high mechanical strength and wide electrochemical stability window (>5.0 V vs. Li+/Li) at 60 °C. The Li/CPEM/LiFePO4 cells also show a favorable cycle life at different rates and 92.7 mAh g−1 (2 C) of discharge specific capacity at 90 °C. Consequently, the PVDF‐HFP/AgNWs@SiO2 CPEM can exhibit an ideal application prospect for LMBs. [ABSTRACT FROM AUTHOR]

Although gel polymer electrolytes (GPEs) have attracted tremendous attention for lithium metal batteries due to their high ionic conductivity, high safety, and excellent adaptability, it is still challenging to suppress the uncontrollable lithium dendrite growth for GPEs. Here, an organic/inorganic composite gel electrolyte (PPPL) as GPEs is proposed, which is formed by ring-opening polymerization reaction of poly(methyl vinyl ether-alt-maleic anhydride) (PMVE-MA) and polyethylene glycol (PEG) in polymer matrix of poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) embedded with Li6.4La3Zr1.4Ta0.6O12 (LLZTO) particles. The PMVE-MA participates in the formation of a stable solid electrolyte interface (SEI) and the PEG greatly improves the flexibility of PPPL. The PPPL exhibits excellent performance in terms of a wide electrochemical window (4.7 V), high lithium transference number (0.59), and satisfactory mechanical strength (11 MPa). Besides, the PPPL contributes to the formation of stable and flexible SEI containing organic components and LiF on lithium metal, and constructs fast and uniform lithium transport channels to effectively suppress the lithium dendrite growth. The Li/PPPL/Li symmetric batteries can stably cycle 800 h at the high current density of 5 mA cm-2 and capacity of 5 mAh cm-2. The outstanding electrochemical performance of the PPPL will provide important insights for design of advanced GPEs. [ABSTRACT FROM AUTHOR]

In order to enhance dielectric properties and energy storage density of poly(vinylidene fluoride‐hexafluoro propylene) (PVDF‐HFP), surface charged gas‐phase Al2O3 nanoparticles (GP‐Al2O3, with positive surface charges, ε' ≈ 10) are selected as fillers to fabricate PVDF‐HFP‐based composites via simple physical blending and hot‐molding techniques. The results show that GP‐Al2O3 are dispersed homogeneously in the PVDF‐HFP matrix and the existence of nanoscale interface layer (matrix‐filler) is investigated by SAXS. The dielectric constant of the composites filled with 10 wt % GP‐Al2O3 is 100.5 at 1 Hz, which is 5.6 times higher than that of pure PVDF‐HFP. The maximum energy storage density of the composite is 4.06 J cm−3 at an electrical field of 900 kV mm−1 with GP‐Al2O3 content of 1 wt %. Experimental results show that GP‐Al2O3 could induce uniform fillers' distribution and increase the concentration of electroactive β‐phase as well as enhance interfacial polarization in the matrix, which resulted in enhancements of dielectric constant and energy storage density of the PVDF‐HFP composites. This work demonstrates that surface charged inorganic‐oxide nanoparticles exhibit promising potential in fabricating ferroelectric polymer composites with relatively high dielectric constant and energy storage. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 574–583 [ABSTRACT FROM AUTHOR]

In order to enhance dielectric properties and energy storage density of poly(vinylidene fluoride‐hexafluoro propylene) (PVDF‐HFP), surface charged gas‐phase Al2O3 nanoparticles (GP‐Al2O3, with positive surface charges, ε' ≈ 10) are selected as fillers to fabricate PVDF‐HFP‐based composites via simple physical blending and hot‐molding techniques. The results show that GP‐Al2O3 are dispersed homogeneously in the PVDF‐HFP matrix and the existence of nanoscale interface layer (matrix‐filler) is investigated by SAXS. The dielectric constant of the composites filled with 10 wt % GP‐Al2O3 is 100.5 at 1 Hz, which is 5.6 times higher than that of pure PVDF‐HFP. The maximum energy storage density of the composite is 4.06 J cm−3 at an electrical field of 900 kV mm−1 with GP‐Al2O3 content of 1 wt %. Experimental results show that GP‐Al2O3 could induce uniform fillers' distribution and increase the concentration of electroactive β‐phase as well as enhance interfacial polarization in the matrix, which resulted in enhancements of dielectric constant and energy storage density of the PVDF‐HFP composites. This work demonstrates that surface charged inorganic‐oxide nanoparticles exhibit promising potential in fabricating ferroelectric polymer composites with relatively high dielectric constant and energy storage. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 574–583 [ABSTRACT FROM AUTHOR]

Abstract: A PVDF‐HFP/colloidal‐TiO2 composite separator is synthesized for high‐temperature lithium‐ion batteries. Incorporation of colloidal TiO2 in the PVDF‐HFP matrix forms a highly‐uniform composite micro‐structure with strong adsorption interactions between TiO2 and PVDF‐HFP due to the presence of citric acid. The strong interactions are giving rise to advantageous mechanical robustness, separator/electrode interface and electrolyte uptake. The separator shows remarkable stability upon thermal treatment at 150 °C. With a high ionic conductivity up to 1.57×10−3 S cm−1, the LFP/Li cell with PVDF‐HFP/colloidal‐TiO2 composite separator delivers charge‐discharge capacities of 156.95 mAh g−1 (0.1 C) at room temperature and 120.8 mAh g−1 (0.5 C) after annealing cells at 140 °C for 3 hours with a 99 % capacity retention after 100 cycles. The PVDF‐HFP/colloidal‐TiO2 separator demonstrates promising potentials for practical applications in high‐temperature environments. [ABSTRACT FROM AUTHOR]

Abstract: Dual‐ion batteries (DIBs) have attracted increasing attention owing to their merits of high working voltage, low cost, and especially environmental friendliness. However, the cycling stability of most DIBs is still unsatisfying due to the decomposition of conventional liquid carbonate electrolytes under high working voltages. Exploration of gel polymer electrolytes (GPEs) with good electrochemical stability at high voltage is a possible strategy to optimize their cycling stability. A high‐performance flexible DIB based on a poly(vinylidene fluoride‐hexafluoro propylene) GPE codoped with poly(ethylene oxide) and graphene oxide via weak bond interactions is herein reported for the first time. The prepared polymer electrolyte shows a 3D porous network with significantly improved ionic conductivity up to 2.1 × 10−3 S cm−1, which is favorable for fast ionic transportation of both cations and anions. As a result, this DIB exhibits excellent cycling stability with a capacity retention of 92% after 2000 cycles at a high current rate of 5C (1C is corresponding to 100 mA g−1), which is among the best performances of DIBs. Moreover, good flexibility and thermal stability (up to 90 °C) are also achieved for this battery, indicating its potential applications for high‐performance flexible energy storage devices. [ABSTRACT FROM AUTHOR]

Abstract: The polymers poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) and poly(n‐butyl methacrylate) (PBMA) are employed in manufacturing the XIENCE family of coronary stents. PBMA serves as a primer and adheres to both the stent and the drug coating. PVDF‐HFP is employed in the drug matrix layer to hold the drug everolimus on the stent and control its release. Chemical stability of the polymers of XIENCE stents in the in‐vivo environment was evaluated by pyrolysis‐gas chromatography with mass spectrometry (Py‐GC/MS) detection. For this evaluation, XIENCE stents explanted from porcine coronary arteries and from human coronary artery specimens at autopsy after 2–4 and 5–7 years of implantation, respectively, were compared to freshly manufactured XIENCE stents (controls). The comparison of pyrograms of explanted stent samples and controls showed identical fragmentation fingerprints of polymers, indicating that PVDF‐HFP and PBMA maintained their chemical integrity after multiple years of XIENCE coronary stent implantation. The findings of the present study demonstrate the chemical stability of PVDF‐HFP and PBMA polymers of the XIENCE family of coronary stents in the in‐vivo environment, and constitute a further proof of the suitability of PVDF‐HFP as a drug carrier for the drug eluting stent applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1721–1729, 2018. [ABSTRACT FROM AUTHOR]

Co-axial electrospinning technique has proved to be a reliable way of producing thin and small hollow fibers with a symmetric or asymmetric structure that may be useful for water treatment. All the hollow fibers produced had an inner diameter of up to 4 µm and average wall thickness of 600 nm. Poly(vinylidene fluoride-co-hexa fluoro propylene) hollow fibers exhibited a dense structure while the addition of poly(ethylene glycol) changed its structure to an asymmetric one, with a dense layer on both inner and outer sides. The semicrystalline copolylmer fibers exhibited a fibrillar structure. Hollow fibers made of the homopolymer poly(vinylidene fluoride) exhibited an asymmetric structure, while polysulfone or poly(ether imide) hollow fibers exhibited a symmetric porous structure. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Flexible film with both piezoelectric and dielectric properties is considered to be a potential candidate for the energy conversion and storage devices. In this study, the Li+ and H2O modified sepiolite/poly(vinylidene fluoride‐co‐hexafluoropropylene) (LiSEP‐H2O/PVDF‐HFP) composite films with both good piezoelectric and dielectric properties were prepared by traditional coating process. When the H2O content was 13 wt %, the LiSEP‐H2O/PVDF‐HFP composite exhibited high d33 of 32 and dielectric constant of 48. Moreover, the effects of the Li+ and adsorbed H2O on the d33, F(β), dielectric constant, short‐circuit currents were discussed. The adsorbed H2O enhanced the β‐phase by the hydrogen bonds and Li+ improved the polarization to realize the composite film with increased piezoelectric and dielectric properties respectively. We expected the common modification to lead other clay minerals realizing the future applications in the adjustment of composites' electric properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48412. [ABSTRACT FROM AUTHOR]