ABSTRACT
The hydroxyl groups on the surface of the cellulose-based gel polymer electrolyte lead to poor interfacial compatibility due to side reactions with lithium sheets. In this paper, a novel cellulose-based gel polymer electrolyte was prepared by uniformly coating the surface of a cellulose membrane with a nanohydrotalcite/PVDF-HFP composite using electrospinning technology. This cellulose-based gel polymer electrolyte exhibits good interfacial compatibility and excellent cycling stability (91.7% specific capacity retention after 500 cycles at 0.5C). Theory and experiments have shown that nanohydrotalcite on the surface of cellulose membrane can effectively prevent the contact of hydroxyl groups with lithium sheets to reduce the side reactions. In addition, nanohydrotalcite can also act as a Li+ transport redistributor to facilitate the uniform deposition of Li+ and reduce the formation of lithium dendrites to extend the cycle life.
ABSTRACT
Lithium-ion batteries (LIBs) have revolutionized the energy storage landscape and are the preferred power source for various applications, ranging from portable electronics to electric vehicles. The constant drive and growth in battery research and development aim to enhance their performance, energy density, and safety. Advanced lithium batteries (LIBs) are considered to be the most promising electrochemical storage devices, which can provide high specific energy, volumetric energy density, and power density. However, the trade-off between ionic conductivity and cycling stability is still a major contradiction for SPEs. In this work, a novel hydroxylated PAF-1 was designed and synthesized through post-modification, and the lithium-rich single-ion porous aromatic framework PAF-1-OLi was thereafter prepared by lithiation, achieved with a specific surface area to be 155 m2 g-1 and a lithium content of 2.01 mmol g-1. PAF-1-OLi, lithium bis(trifluoromethanesulfony)limine (LiTFSI), and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) were compounded to obtain PAF-1-OLi/PVDF by solution casting, which had good mechanical, thermodynamic, and electrochemical properties. The ion conductivity of PAF-1-OLi/PVDF infiltrated with plasticizer was 2.93 × 10-4 S cm-1 at 25 °C. The tLi+ was 0.77, which was much higher than that of the traditional dual-ion polymer electrolytes. The electrochemical window of PAF-1-OLi/PVDF can reach 4.9 V. The Li//PAF-1-OLi/PVDF//LiFePO4 battery initial discharge specific capacity was 147 mAh g-1 and reached 134.9 mAh g-1 after 600 cycles with a capacity retention rate of 91.2%, demonstrating its good cycling stability. The anionic part of lithium salt was fixed on the framework of PAF-1 to increase the Li+ transfer number of PAF-1-OLi/PVDF. The lithium-rich PAF-1-OLi and the LiTFSI provided abundant Li+ sources to transfer, while PAF-1-OLi helped to form a continuous Li+ transport channel, effectively promoting the migration of Li+ in the PAF-1-OLi/PVDF and effectively improving the Li+ conductivity. This study afforded a novel polymer electrolyte based on lithium-rich PAF-1-OLi, which has excellent electrochemical performance, providing a new choice for the polymer electrolyte of lithium batteries.
ABSTRACT
Solid polymer electrolytes (SPEs) are regarded as a superior alternative to traditional liquid electrolytes of lithium-ion batteries (LIBs) due to their improved safety features. The practical implementation of SPEs faces challenges, such as low ionic conductivity at room temperature (RT) and inadequate interfacial contact, leading to high interfacial resistance across the electrode and electrolyte interfaces. In this study, we addressed these issues by designing a quasi-gel polymer electrolyte (QGPE), a blend of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), poly(ethylene oxide) (PEO), and succinonitrile (SN), with the desired mechanical strength, ionic conductivity, and interfacial stability through a simple solution casting technique. The QGPE features a thin solvated PEO layer on its surface, which wets the electrode, reducing the interfacial resistance and ensuring a homogeneous Li-ion flux across the interface. The optimized QGPE exhibits a good lithium-ion conductivity of 1.14 × 10-3 S cm-1 with a superior lithium-ion transference number of 0.7 at 25 °C. The Li/QGPE/Li symmetric cell exhibits a highly reversible lithium plating/stripping process for over 1300 h with minimal voltage polarization of â¼20 mV. The Li/QGPE/LiFePO4 full cell demonstrates good rate capability and excellent long-term cycling performance at a 0.1 C rate at 25 °C, maintaining a specific discharge capacity of 148 mAh g-1 over 200 cycles. The effectiveness of QGPE for LIBs is proven using a graphite/QGPE/LiFePO4 4 × 4 cm pouch cell, showcasing outstanding flexibility and tolerance against intentional abuse.
ABSTRACT
Fouling and biofouling remain significant challenges in seawater desalination plants. One practical approach to address these issues is to develop anti-biofouling membranes. Therefore, novel hybrid zinc phthalocyanine/polyvinylidene fluoride-co-hexafluoropropylene (Zn(4-PPOx)4Pc/PVDF-HFP) membranes were prepared by electrospinning to evaluate their properties against biofouling. The hybrid nanofiber membrane was characterized by atomic force microscopy (AFM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and contact angle measurements. The theoretical calculations of PVDF-HFP, Zn(4-PPOx)4Pc), and Zn(4-PPOx)4Pc/PVDF-HFP nanofibers were performed using a hybrid functional RB3LYP and the 6-31 G (d,p) basis set, employing Gaussian 09. DFT calculations illustrated that the calculated physical and electronic parameters ensured the feasibility of the interaction of PVDF-HFP with Zn(4-PPOx)4Pc via a halogen-hydrogen bond, resulting in a highly stable and remarkably reactive structure. Moreover, molecular electrostatic potential (MEP) maps were drawn to identify the reactive regions of the Zn(4-PPOx)4Pc and PVDF-HFP/Zn(4-PPOx)4Pc nanofibers. Molecular docking analysis revealed that Zn(4-PPOx)4Pc has highest binding affinity (-8.56 kcal/mol) with protein from S. aureus (1N67) mainly with ten amino acids (ASP405, LYS374, GLU446, ASN406, ALA441, TYR372, LYS371, TYR448, LYS374, and ALA442). These findings highlight the promising potential of Zn(4-PPOx) 4Pc/PVDF-HFP nanocomposite membranes in improving the efficiency of water desalination by reducing biofouling and providing antibacterial properties.
ABSTRACT
Here we report the liquid-solid interaction in droplet-based triboelectric nanogenerators (TENG) for estimation of human Na+/K+levels. The exploitation of PVDF-HFP encapsulated WS2as active layer in the droplet-based TENG (DTENG) leads to the generation of electrical signal during the impact of water droplet. Comparison over the control devices indicates that surface quality and dielectric nature of the PVDF-HFP/WS2composite largely dictates the performance of the DTENG. The demonstration of excellent sensitivity of the DTENG towards water quality indicates its promising application towards water testing. In addition, the alteration in output signal with slightest variation in ionic concentration (Na+or K+) in water has been witnessed and is interpreted with charge transfer and ion transfer processes during liquid-solid interaction. The study reveals that the ion mobility largely affects the ion adsorption process on the active layer of PVDF-HFP/WS2and thus generates distinct output profiles for diverse ions like Na+and K+. Following that, the DTENG characteristics have been exploited to artificial urine where the varying output signals have been recorded for variation in urinary Na+ion concentration. Therefore, the deployment of PVDF-HFP/WS2in DTENG holds promising application towards the analyse of ionic characteristics of body fluids.
Subject(s)
Nanostructures , Fluorocarbon Polymers/chemistry , Polyvinyls/chemistry , Nanostructures/chemistry , Capsules , Tungsten Compounds/chemistry , Sulfides/chemistry , Electricity , Potassium/chemistry , Ions/chemistry , Chlorine/chemistryABSTRACT
Aggregation-induced emission (AIE) has been widely used in research on electrochemiluminescence (ECL) due to its excellent luminescence intensity. In this work, copper superparticles (Cu SPs) were used to construct ECL biosensor to detect the microRNA-103a (miRNA-103a) in triple-negative breast cancer (TNBC) tumor tissues. Firstly, GSH-capped copper clusters were used as precursors to prepare Cu SPs by the AIE effect. Compared with clusters, Cu SPs possessed higher luminescence performance and energy stability, making them an ideal choice for ECL nanoprobe. The film of PVDF-HFP/CeVO4 NPs was constructed and modified with CPBA and GSH as the sensing interface (PCCG). The PCCG film displayed good conductivity and hydrophilicity, and desirable mechanical stability. Moreover, the PCCG film can induce high carrier mobility rates and dissociate large amounts of the co-reactant K2S2O8 to enhance the ECL intensity of Cu SPs. As a result, the prepared ECL sensor with the catalyzed hairpin assembly (CHA) strategy was employed to quantify miRNA-103a in the range of 100 fM to 100 nM. The biosensor provided a novel analytical approach for the clinical diagnosis of TNBC.
Subject(s)
Biosensing Techniques , Copper , MicroRNAs , MicroRNAs/analysis , Copper/chemistry , Humans , Biosensing Techniques/methods , Polyvinyls/chemistry , Luminescent Measurements/methods , Electrochemical Techniques/methods , Metal Nanoparticles/chemistry , Limit of Detection , Triple Negative Breast Neoplasms/geneticsABSTRACT
Over the last years, solid-state electrolytes made of an ionic liquid (IL) confined in a solid (inorganic or polymer) matrix, also known as ionogels, have been proposed to solve the leakage problems occurring at high temperatures in classical electrical double-layer capacitors (EDLCs) with an organic electrolyte, and thereof improve the safety. However, making ionogel-based EDLCs perform with reasonable power at low temperature is still a major challenge due to the high melting point of the confined IL. To overcome these limitations, the present contribution discloses ionogel films prepared in a totally oxygen/moisture-free atmosphere by encapsulating 70 wt % of an equimolar mixture of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide and 1-ethyl-3-methylimidazolium tetrafluoroborate - [EMIm][BF4]0.5[FSI]0.5 - into a poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) network. The further called "binary ionogel" films demonstrated a high flexibility and a good ionic conductivity of 5.8â mS cm-1 at 20 °C. Contrary to the ionogels prepared from either [EMIm][FSI] or [EMIm][BF4], displaying melting at Tm=-16 °C and -7 °C, respectively, the crystallization of confined [EMIm][BF4]0.5[FSI]0.5 is quenched in the binary ionogel, which shows only a glass transition at -101 °C. This quenching enables an increased ionicity and ionic diffusion at the interface with the PVdF host network, leading the binary ionogel membrane to display higher ionic conductivity below -20 °C than the parent binary [EMIm][BF4]0.5[FSI]0.5 liquid. Laminate EDLCs were built with a 100â µm thick binary ionogel separator and electrodes made from a hierarchical micro-/mesoporous MgO-templated carbon containing a reasonable proportion of mesopores to enhance the mass transport of ions, especially at low temperature where the ionic diffusion noticeably decreases. The EDLCs operated up to 3.0â V with ideal EDL characteristics from -40 °C to room temperature. Their output specific energy under a discharge power of 1â kW kg-1 is ca. 4â times larger than with a cell implementing the same carbon electrodes together with the binary [EMIm][BF4]0.5[FSI]0.5 liquid. Hence, this binary ionogel electrolyte concept paves the road for developing safe and flexible solid-state energy storage devices operating at subambient temperatures in extreme environments.
ABSTRACT
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
In the realm of polymer composites, there is growing interest in the use of more than one filler for achieving multifunctional properties. In this work, a composite separator membrane has been developed for lithium-ion battery application, by incorporating conductive silver nanowires (AgNWs) and titanium dioxide (TiO2) nanoparticles into a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer matrix. The composite membranes were manufactured by solvent casting and thermally induced phase separation, with total filler content varying up to 10 wt%. The ternary composites composites present improved mechanical characteristics, ionic conductivity and lithium transfer number compared to the neat polymer matrix. On the other hand, the filler type and content within the composite has little bearing on the morphology, polymer phase, or thermal stability. Once applied as a separator in lithium-ion batteries, the highest discharge capacity value was obtained for the 5 wt% AgNWs/5 wt% TiO2/PVDF-HFP membrane at different C-rates, benefiting from the synergetic effect from both fillers. This work demonstrates that higher battery performance can be achieved for next-generation lithium-ion batteries by using separator membranes based on ternary composites.
ABSTRACT
Focusing on the uncontrolled discharge of organic dyes, a known threat to human health and aquatic ecosystems, this work employs a dual-functional catalyst approach, by immobilizing a synthesized bismuth sulfur iodide (BiSI) into a poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymeric matrix for multifunctional water remediation. The resulting BiSI@PVDF nanocomposite membrane (NCM), with 20 wt% filler content, maintains a highly porous structure without compromising morphology or thermal properties. Demonstrating efficiency in natural pH conditions, the NCM removes nearly all Rhodamine B (RhB) within 1 h, using a combined sonophotocatalytic process. Langmuir and pseudo-second-order models describe the remediation process, achieving a maximum removal capacity (Qmax) of 72.2 mg/g. In addition, the combined sonophotocatalysis achieved a degradation rate ten and five times higher (0.026 min-1) than photocatalysis (0.002 min-1) and sonocatalysis (0.010 min-1). Furthermore, the NCM exhibits notable reusability over five cycles without efficiency losses and efficiencies always higher than 90%, highlighting its potential for real water matrices. The study underscores the suitability of BiSI@PVDF as a dual-functional catalyst for organic dye degradation, showcasing synergistic adsorption, photocatalysis, and sonocatalysis for water remediation.
Subject(s)
Bismuth , Coloring Agents , Nanocomposites , Polyvinyls , Rhodamines , Water Pollutants, Chemical , Water Purification , Water Pollutants, Chemical/chemistry , Nanocomposites/chemistry , Catalysis , Rhodamines/chemistry , Bismuth/chemistry , Coloring Agents/chemistry , Water Purification/methods , Polyvinyls/chemistry , Fluorocarbon PolymersABSTRACT
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 ß-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
In this study, flexible nanocomposites made from PVDF-HFP reinforced with carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) are manufactured using a sonication and solvent casting method for monitoring purposes. More specifically, the effect of the volume batch under the sonication process is explored. For CNT-based composites, the electrical conductivity decreases as the batch volume increases due to less effective dispersion of the CNTs during the 30-min sonication. The maximum electrical conductivity achieved in this type of sensor is 1.44 ± 0.17 S/m. For the GNP-based nanocomposites, the lower the batch volume is, the more breakage of nanoplatelets is induced by sonication, and the electrical response decreases. This is also validated by AC analysis, where the characteristic frequencies are extracted. Here, the maximum electrical conductivity measured is 8.66 ± 1.76 S/m. The electromechanical results also show dependency on the batch volume. In the CNT-based nanocomposites, the higher gauge factor achieved corresponds to the batch size, where the sonication may be more effective because it leads to a dispersed pathway formed by aggregates connected by tunneling mechanisms. In contrast, in the CNT-based nanocomposites, the GF depends on the lateral size of the GNPs. The biggest GF of all sensors is achieved with the PVDF-HFP/GNP sensors, having a value of 69.36 × 104 at 35% of strain, while the highest GF achieved with a PVDF-HFP/CNT sensor is 79.70 × 103 at 70%. In addition, cycling tests show robust electromechanical response with cycling for two different strain percentages for each type of nanocomposite. The sensor with the highest sensitivity is selected for monitoring two joint movements as proof of the applicability of the sensors manufactured.
ABSTRACT
Numerous endeavors have been dedicated to the development of composite polymer electrolyte (CPE) membranes for all-solid-state batteries (SSBs). However, insufficient ionic conductivity and mechanical properties still pose great challenges in practical applications. In this study, a flexible composite electrolyte membrane (FCPE) with fast ion transport channels was prepared using a phase conversion process combined with in situ polymerization. The polyvinylidene fluoride-hexafluoro propylene (PVDF-HFP) polymer matrix incorporated with lithium lanthanum zirconate (LLZTO) formed a 3D net-like structure, and the in situ polymerized polyvinyl ethylene carbonate (PVEC) enhanced the interface connection. This 3D network, with multiple rapid pathways for Li+ that effectively control Li+ flux, led to uniform lithium deposition. Moreover, the symmetrical lithium cells that used FCPE exhibited high stability after 1200 h of cycling at 0.1 mA cm-2. Specifically, all-solid-state lithium batteries coupled with LiFePO4 cathodes can stably cycle for over 100 cycles at room temperature with high Coulombic efficiencies. Furthermore, after 100 cycles, the infrared spectrum shows that the structure of FCPE remains stable. This work demonstrates a novel insight for designing a flexible composite electrolyte for highly safe SSBs.
ABSTRACT
Herein, ZIF-8 inorganic particles with different sized reinforced poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) solid composite polymer electrolytes (PVDF-HFP/10%ZIF-8) were prepared via a facile blade-coating approach, and free-standing quasi solid-state composite electrolytes (PVDF-HFP/10%ZIF-8(0.6)/Plasticizer, abbreviated as PH/10%ZIF-8(0.6)/P), were further obtained through the introduction of plasticizer. Optimized PH/10%ZIF-8(0.6)/P exhibited a high ionic conductivity of 2.8 × 10-4 S cm-1 at 30 °C, and superior Li+ transfer number of 0.89 with an ultrathin thickness (26 µm). Therefore, PH/10%ZIF-8(0.6)/P could effectively inhibit the growth of lithium dendrites, and the assembled Li/LiFePO4 cell delivered good cycling stability with a capacity retention rate of 89.1% after 100 cycles at 0.5 C.
ABSTRACT
Nowadays, bacterial infection is regarded as a serious threat to humankind, which needs to be taken care of. The emergence of antibiotic resistance and multidrug resistance (MDR) is rendering this situation more troublesome. However, several alternative treatment regimens have aided such diseases quite well in the recent past, among which dynamic antibacterial therapies combat this situation quite well. Among various dynamic therapies, piezodynamic therapy is a very recent avenue, in which mechanical stimuli have been exploited to treat bacterial infections. Herein, piezo-active bismuth ferrite-loaded poly(vinylidene fluoride-co-hexafluoropropylene) polymer has been utilized to eradicate gram-positive bacteria (E. faecalis) and gram-negative bacteria (E. coli). The sample has been designed in a free-standing membrane form, which, under soft ultrasound (~10 kHz), generates reactive radicals to ablate bacteria. Initially, the structure and morphology of the membrane have been substantiated by using X-ray diffraction and scanning electron microscopy methods; besides, Fourier transform infrared spectrum of the sample depicts a tremendously high value of polarizability and further confirms the piezo-activity of the membrane. More than 99% of E. coli and E. faecalis have been successfully eradicated within 30 min of ultrasound. Moreover, the solid-state structure and hydrophobic nature of the membrane help us to reuse it in a cyclic manner, which is possibly reported herein for the very first time. This novel membrane could be deployed in healthcare systems and pigment industries and could be exploited as a self-cleaning material.
ABSTRACT
The major challenge for membrane distillation (MD) is the membrane wetting resistance induced by pollutants in the feed solution. The proposed solution for this issue was to fabricate membranes with hydrophobic properties. Hydrophobic electrospun poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofiber membranes were produced for brine treatment using the direct-contact membrane distillation (DCMD) technique. These nanofiber membranes were prepared from three different polymeric solution compositions to study the effect of solvent composition on the electrospinning process. Furthermore, the effect of the polymer concentration was investigated by preparing polymeric solutions with three different polymer percentages: 6, 8, and 10%. All of the nanofiber membranes obtained from electrospinning were post-treated at varying temperatures. The effects of thickness, porosity, pore size, and liquid entry pressure (LEP) were studied. The hydrophobicity was determined using contact angle measurements, which were investigated using optical contact angle goniometry. The crystallinity and thermal properties were studied using DSC and XRD, while the functional groups were studied using FTIR. The morphological study was performed with AMF and described the roughness of nanofiber membranes. Finally, all of the nanofiber membranes had enough of a hydrophobic nature to be used in DCMD. A PVDF membrane filter disc and all nanofiber membranes were applied in DCMD to treat brine water. The resulting water flux and permeate water quality were compared, and it was discovered that all of the produced nanofiber membranes showed good behavior with varying water flux, but the salt rejection was greater than 90%. A membrane prepared from DMF/acetone 5-5 with 10% PVDF-HFP provided the perfect performance, with an average water flux of 44 kg.m-2.h-1 and salt rejection of 99.8%.
ABSTRACT
Nanofillers' applicability in gel polymer electrolyte (GPE)-based devices skyrocketed in the last decade as soon as their remarkable benefits were realized. However, their applicability in GPE-based electrochromic devices (ECDs) has hardly seen any development due to challenges such as optical inhomogeneity brought by incompetent nanofiller sizes, transmittance drop due to higher filler loading (usually required), and poor methodologies of electrolyte fabrication. To address such issues, herein, we demonstrate a reinforced polymer electrolyte tailored through poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP),1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4), and four types of mesoporous SiO2 nanofillers, porous (distinct morphologies) and nonporous, two each. The synthesized electrochromic species 1,1'-bis(4-fluorobenzyl)-4,4'-bipyridine-1,1'-diium tetrafluoroborate (BzV, 0.05 M), counter redox species ferrocene (Fc, 0.05 M), and supporting electrolyte (TBABF4, 0.5 M) were first dissolved in propylene carbonate (PC) and then immobilized in an electrospun PVDF-HFP/BMIMBF4/SiO2 host. We distinctly observed that spherical (SPHS) and hexagonal pore (MCMS) morphologies of fillers endowed higher transmittance change (ΔT) and coloration efficiency (CE) in utilized ECDs; particularly for the MCMS-incorporated ECD (GPE-MCMS/BzV-Fc ECD), ΔT reached â¼62.5% and CE soared to 276.3 cm2/C at 603 nm. The remarkable benefit of filler's hexagonal morphology was also seen in the GPE-MCMS/BzV-Fc ECD, which not only marked an astounding ionic conductivity (σ) of â¼13.5 × 10-3 S cm-1 at 25 °C, thus imitating the solution-type ECD's behavior, but also retained â¼77% of initial ΔT after 5000 switching cycles. The enhancement in ECD's performance resulted from merits brought by filler geometries such as the proliferation of Lewis acid-base interaction sites due to the high surface-to-volume ratio, the creation of percolating tunnels, and the emergence of capillary forces triggering facile ion transportation in the electrolyte matrix.
ABSTRACT
Membrane technologies and materials development appear crucial for the hydrogen/natural gas separation in the impending transition to the hydrogen economy. Transporting hydrogen through the existing natural gas network could result less expensive than a brand-new pipe system. Currently, many studies are focused on the development of novel structured materials for gas separation applications, including the combination of various kind of additives in polymeric matrix. Numerous gas pairs have been investigated and the gas transport mechanism in those membranes has been elucidated. However, the selective separation of high purity hydrogen from hydrogen/methane mixtures is still a big challenge and nowadays needs a great improvement to promote the transition towards more sustainable energy source. In this context, because of their remarkable properties, fluoro-based polymers, such as PVDF-HFP and NafionTM, are among the most popular membrane materials, even if a further optimization is needed. In this study, hybrid polymer-based membranes were deposited as thin films on large graphite surfaces. Different weight ratios of PVDF-HFP and NafionTM polymers supported over 200 µm thick graphite foils were tested toward hydrogen/methane gas mixture separation. Small punch tests were carried out to study the membrane mechanical behaviour, reproducing the testing conditions. Finally, the permeability and the gas separation activity of hydrogen/methane over membranes were investigated at room temperature (25 °C) and near atmospheric pressure (using a pressure difference of 1.5 bar). The best performance of the developed membranes was registered when the 4:1 polymer PVDF-HFP/NafionTM weight ratio was used. In particular, starting from the 1:1 hydrogen/methane gas mixture, a 32.6% (v%) H2 enrichment was measured. Furthermore, there was a good agreement between the experimental and theoretical selectivity values.
ABSTRACT
Battery safety calls for solid state batteries and how to prepare solid electrolytes with excellent performance are of significant importance. In this study, hybrid solid electrolytes combined with organic PVDF-HFP and inorganic active fillers are studied. The modified active fillers of Li7-x-3yAlyLa3Zr2-xTaxO12are obtained by co-element doping with Al and Ta when LLZO is synthesized by calcination. And an high room temperature ionic conductivity of 5.357 × 10-4S cm-1is exhibited by ATLLZO ceramic sheet. The composite solid electrolyte PVDF-HFP/LiTFSI/ATLLZO (PHL-ATLLZO) is prepared by solution casting method, and its electrochemical properties are investigated. The results show that when the contents of lithium salt LiTFSI and active filler ATLLZO are controlled at 40 wt% and 10%, respectively, the ionic conductivity of the resulting composite solid electrolyte is as high as 2.686 × 10-4S cm-1at room temperature, and a wide electrochemical window of 4.75 V is exhibited. The LiFePO4/PHL-ATLLZO/Li all-solid-state battery assembled based on the composite solid-state electrolyte exhibits excellent cycling stability at room temperature. The cell assembled by casting the composite solid-state electrolyte on the cathode surface shows a discharge specific capacity of 134.3 mAh g-1and 96.2% capacity retention after 100 cycles at 0.2 C. The prepared composite solid-state electrolyte demonstrates excellent electrochemical performance.
ABSTRACT
To further advance the application of flexible piezoelectric materials in wearable/implantable devices and robot electronic skin, it is necessary to endow them with a new function of antibacterial properties and with higher piezoelectric performance. Introducing a specially designated nanomaterial based on the nanocomposite effect is a feasible strategy to improve material properties and achieve multifunctionalization of composites. In this paper, carbon dots (CDs) were sensitized onto the surface of ZnO to form ZnO@CDs nanoparticles, which were then incorporated into polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) to obtain a multifunctional composite. On the one hand, the antibacterial property of ZnO was improved because CDs had good optical absorption of visible light and their surface functional groups were favorable for electrostatic adsorption with bacteria. Therefore, ZnO@CDs endowed the composite with an outstanding antibacterial rate of 69.1% for Staphylococcus aureus. On the other hand, CDs played a bridging role between ZnO and PVDF-HFP, reducing the negative effect of ZnO aggregation and interface incompatibility with PVDF-HFP. As a result, ZnO@CDs induced ß-phase formation of 80.4% in PVDF-HFP with a d33 value of 33.8 pC N-1. The multifunctional device exhibited excellent piezoelectric and antibacterial performance in the application of energy harvesters and self-powered pressure sensors.