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A facile approach has been chosen for the synthesis of PVDF based copolymer anion exchange membrane using nonhazardous chemicals. The synthetic route was achieved through free radical polymerization between dehydrofluorinated PVDF-co-HFP (DYPVDF) and morpholine functionalized vinyl benzyl chloride (VBC). The variations in properties of formed membranes were evaluated by varying the concentration of VBC. FT-IR, as well as 1 H NMR, confirms the formation of the desired molecular structure of copolymer in form of a membrane. Surface morphology of copolymer anion exchange membranes was checked through TEM and AFM analysis. Standardized techniques were used to evaluate the physicochemical and electrochemical properties of the membranes like ion exchange capacity (IEC), water uptake (WU), ionic conductivity (IC) and linear expansion ratio (LER). The highest value of water uptake and IEC was found to be 28% and 1.27 meq/g for PQM-40 copolymer anion exchange membrane. Membranes were subjected to Fenton's test to evaluate their oxidative stability. Maximum weight loss of 1.67%, 1.44% and 1.39% was found in PQM-40, PQM-30, and PQM-20 respectively. Further, synthesized copolymer membranes were subjected to salt removal by electrodialysis and acid recovery by diffusion dialysis (DD). Maximum current efficiency during desalination and highest separation factor for acid recovery by diffusion dialysis were confirmed by PQM-40, the values are 82.36% and 25% respectively. [ABSTRACT FROM AUTHOR]

Ion-exchange membranes (IEMs) are essential for controlling ion transport in electrochemical membrane-based technologies for water purification, energy generation, and energy storage. In general, IEMs must exhibit high ionic conductivity and selectivity, both of which are significantly influenced by the charge and water content of the hydrated membrane. In this perspective, we compiled the charge and water contents of approximately 1000 IEMs reported over the past several decades to assess their range and variability, as well as to reveal gaps and set clear targets for future membrane design. We compared the charge and water content of negatively and positively charged membranes, as well as membranes developed for desalination and energy applications. The majority of IEMs, regardless of structure or intended application, have volumetric charge densities below 3 mol/L[membrane]. This narrow range of charge densities limits the performance of IEMs and contributes to the observed tradeoff between ion throughput and selectivity. It is critical to develop IEMs with higher charge densities to overcome this performance limitation. We highlighted several design strategies that yielded IEMs with fixed charge densities higher than 3 mol/L[membrane]. These strategies provide valuable insights and can guide the design of next-generation IEMs with high charge densities. [Display omitted] • Charge and water content of ∼1000 published ion-exchange membranes were surveyed. • Charge and water content are coupled, yielding the throughput-selectivity tradeoff. • Charge densities of most reported membranes are between 0 and 3 mol/L[membrane]. • Membranes for energy applications dominate the frontier of high charge densities. • Synthetic strategies for membranes at the upper limit of charge density are discussed. [ABSTRACT FROM AUTHOR]

A novel lithiated polyvinyl formal single-ion conductor (Li-PVFM) membrane has been proposed and prepared as polymer electrolyte for Li-ion batteries with excellent mechanical strength of 11–34 MPa and good thermal stability, but the series faces the common issue of solid-state electrolyte - a low ionic conductivity about 10 −6 S cm −1 at room temperature. Herein, by purifying the polymer matrix to avoid the negative effect of the impurities on Li + diffusion, and linking more Li + from lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) on the matrix to improve the carrier concentration, the as obtained solid-state electrolyte membrane exhibits a significantly improved ambient ionic conductivity in two orders of magnitude to 10 −4 S cm −1 . The results confirm that the polymer matrix is obtained without any residual oxalate and carbonate, resulting in the increasing ionic conductivity of electrolyte membrane from 10 −6 to 10 −5 S cm −1 . Furthermore, the conductor membrane with modulating the lithium content to 0.80 mol L −1 has a high lithium-ion transference number of 0.81, wide electrochemical stability window of > 5 V (vs. Li + /Li) and excellent tensile strength of 44.8 MPa. The solid electrolyte batteries using LiFePO 4 as cathode material exhibit a reversible capacity of 130 mAh g −1 and a good cycling stability. [ABSTRACT FROM AUTHOR]

The membrane performance of conductive polyaniline membrane may be tuned in-situ by applying an external electrical potential. In this study, we focused on the electrical tuneability of polyaniline (PANI) membrane in response to the externally applied potential and also proposed a hypothesis for electrical tuneability in PANI membranes under applied potential. PANI was synthesised via chemical oxidative polymerisation at different polymerisation temperatures (T poly ) (5 °C, 15 °C and 25 °C) and flat sheet PANI membranes were prepared via non-solvent induced phase separation (NIPS). The influence of electrical tuneability on flux and molecular weight cut-off (MWCO) under external potential during cross-flow filtration was studied. The membrane flux and MWCO were measured for neutrally charged polyethylene glycol (PEG) feed solutions as a function of the applied potential from 0 to 30 V. The results demonstrated that the electrically conductive PANI membranes showed a decrease in permeance and MWCO under the applied potential in the cross-flow filtrations, with a higher applied potential producing to a larger decrease. The PANI membrane (T poly = 15 °C) showing the greatest MWCO decrease (down to 2800 g mol −1 ) at 30 V from 6000 g mol −1 at 0 V. It was hypothesised that the swelling of polymer chains caused the narrowing of pore size of membranes on the application of high external potential and resulted in reduction of membrane flux and MWCO. Overall these results suggest that the electrically conductive PANI membranes can self-regulatively adjust their separation properties in response to electrical stimuli, allowing control over neutrally charged molecules transport beyond the ion based separations under applied potential. [ABSTRACT FROM AUTHOR]

Catalytic Pt layers are coated on the surface of the mixed proton-electron conductive membranes based on La 5.5 W 0.45 Nb 0.15 Mo 0.4 O 11.25-δ (LWNM) aiming to promote the hydrogen surface exchange, and effect of the Pt layer on the hydrogen permeation flux through the LWNM membrane has been investigated. A hydrogen permeation flux of 0.483 mL/min∙cm 2 is achieved at 1000 °C fed with a mixture of 50% H 2 − 50% He under wet condition with catalytic Pt layers on both sides of the LWNM membrane, which is twice as much as that of the uncoated membrane, indicating that the Pt layers on the membrane surface exhibit obvious positive effect on the hydrogen permeation. The increase of the hydrogen permeation flux is resulted from the enhancement of hydrogen dissociation/combination on the membrane surface by the Pt layer, which promotes the hydrogen surface exchange process. Moreover, it is more effective when the Pt layer is coated on the sweep side, which demonstrates that the hydrogen surface reaction on the sweep side of the membrane plays a predominant role compared with that on the feed side. [ABSTRACT FROM AUTHOR]

In this study, we fabricated electrically conductive membranes using graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) via the blending phase inversion method. The effects of the membrane polymer: solvent and the GO: MWCNTs weight ratios on the electrical conductivity of membrane were investigated. It was discovered that batch M10 membranes exhibited moderately high electrical conductivity due to incorporation of carbon nanomaterials forming continuous electron paths across the membrane matrix. Using this optimized batch of membranes, performance test was conducted on the palm oil mill effluent (POME). In general, the flux decline was reduced with the continuous and intermittent electric fields. The presence of an electric field exerted a stronger repulsion force to repel the foulant and thus reduced the blockage of the membrane surfaces. As compared to the absence of electric field, M10(c)-5, M10(c)-10, and M10(c)-20 had improved the normalized flux by 108.14%, 90.54%, and 89.69%, respectively, with the continuous electric field of 300 V/cm. M10(c)-5 exhibited the optimal extent of fouling mitigation, as attributed to the enhancement of membrane electrical conductivity without compromising other membrane characteristics. Overall, this study showed that, with the right membrane formulation, a good conductive membrane with electrically-enhanced antifouling properties can be fabricated. [ABSTRACT FROM AUTHOR]

A high performance of anion exchange membranes (AEMs) is highly demanded in anion exchange membrane fuel cells (AEMFCs) and has been extensively studied. However, the poor ionic conductivities and the alkaline stability might limit their applications. Herein, we developed a novel strategy to improve the ionic conductivity and alkaline stability of AEMs by introducing hydrophilic oligo(ethylene glycol)(OEG) groups. Continuous ion-conducting channels were efficiently formed thanks to the dynamic aggregation of water molecules assisted by the hydrophilic side chains. The resultant AEMs with low IEC values showed significant enhancement in hydroxide conductivity compared to the AEMs functionalized by the conventional 1,2-dimethylimidazolium (PSf-Im), as the hydroxide conductivity of PSf-2 membrane with an IEC of 1.05 mmol g −1 was 59.5 mS·cm −1 at 60 °C while the hydroxide conductivity of PSf-Im membrane with an IEC of 1.27 mmol g −1 was 36.7 mS·cm −1 . In addition, the alkaline stability and the mechanical properties of the resultant AEMs were improved remarkably. The density functional theory (DFT) study showed that the introduction of OEG part can significantly increase the LUMO energy of functional group and then enhance the alkaline stability. [ABSTRACT FROM AUTHOR]

As the core component in anion exchange membrane fuel cells (AEMFCs), anion exchange membranes (AEMs) have been expected to possess high ionic conductivity, low swelling, excellent mechanical, chemical and thermal stabilities. With the goal in mind, in this study, a series of long side-chain polybenzimidazole membranes with high conductivity and chemical stability has been fabricated. Firstly, a polybenzimidazole (PBI) with high molecular weight was synthesized by 3,3′,4,4′-Biphenyltetramine and 4,4′-oxybisbenzoicacid through polycondensation reaction. Then, a long side-chain is grafted onto the PBI, resulting in a highly durable long side-chain polybenzimidazole AEMs (N-PBIs) successfully. The chemical structure of the PBI, side-chain (Sc) and N-PBI was characterized by FT-IR and 1 H NMR. The IEC of N-PBI samples is 0.83–1.36 mmol g −1 and the swelling ratios of these samples are 1.20–1.50%. The OH - conductivity of N-PBI increased from 0.040 to 0.11 S/cm with the increase of temperature from room temperature to 80 °C. The N-PBI membrane demonstrated highly alkaline stability in 1 M NaOH at 80 °C for over 1000 h. [ABSTRACT FROM AUTHOR]

In this study, two unique organic–inorganic hybrids are synthesized and optimized to obtain a new type of hybrid blend membrane. A soft hybrid is obtained from reaction of polyetheramine (M-2070) and (3-glycidyloxypropyl)trimethoxysilane (GLYMO), whereas a hard hybrid is prepared from reactions of polyetherdiamine (ED2003), poly(ethylene glycol) diglycidyl ether (PEGDGE) and GLYMO. Both hybrids are finally blended with poly(vinylidene fluoride-co-hexafluoropropylene) (P(VdF-HFP)) to get the hybrid blend membrane and plasticized with 1 M LiPF 6 in EC/DEC. The successful synthesis of the hybrid blend membrane structure is established from 13 C and 29 Si solid-state NMR spectroscopy. FTIR results reveal the interactions of different groups of the hybrid blend membrane. The hybrid blend electrolyte possesses maximum ionic conductivity value of 6.9 mS cm −1 at 30 °C and is electrochemically stable up to 5 V. The electrochemical performance of the hybrid blend electrolyte assemble in a battery cell with the LiFePO 4 cathode exhibits a good cycle life of over 200 cycles with an initial discharge capacity of 150 mA h g −1 . In addition, coulombic efficiency of 97–99% is maintained for the whole cycles. Our results demonstrate that the present hybrid blend electrolyte can be a potential candidate serving as an effective electrolyte in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Ceramic–ceramic composite (cercer) membranes of (Mo-doped) lanthanum tungstate, La 27 (W,Mo) 5 O 55.5− δ , and lanthanum chromite, La 0.87 Sr 0.13 CrO 3− δ , have recently been shown to exhibit H 2 permeabilities among state-of-the-art. The present work deals with the long-term stability of these cercer membranes in line with concern of flux degradation and phase instability observed in previous studies. The H 2 permeability of disc shaped membranes with varying La/W ratio in the lanthanum tungstate phase (5.35≤La/W≤5.50) was measured at 900 and 1000 °C with a feed gas containing 49% H 2 and 2.5% H 2 O for up to 1500 h. It was observed that the H 2 permeability decreased by a factor of up to 5.3 over 1500 h at 1000 °C. Post-characterization of the membranes and similarly annealed samples was performed by SEM, STEM and XRD, and segregation of La 2 O 3 was observed. The decrease in H 2 permeability was ascribed to the compositional instability of the cation-disordered lanthanum tungstate under the measurement conditions. Equilibration of the La/W ratio by segregation of La 2 O 3 leads to a lower ionic conductivity according to the materials inherent defect chemistry. Partial decomposition and reduction of the lanthanum tungstate phase, presumably to metallic tungsten, was also observed after exposure to nominally dry hydrogen. [ABSTRACT FROM AUTHOR]

In the present contribution we investigated the influence of the acid pretreatment procedure of Nafion® 117 membranes on the resulting ionic conductivity by using electrochemical impedance spectroscopy. For this purpose, a setup allowing to measure the ionic conductivity at different temperatures, relative humidities, and contact pressures was developed. The state of protonation was determined by the ionic exchange capacity which is a measure of the amount of protonated sulfonic acid groups for the overall ionic exchange ability of the Nafion® membrane. The state of hydration was determined by water uptake and water vapor adsorption while structural observation was conducted by infrared spectroscopy. Additional thermophysical characterization was performed using differential scanning calorimetry. It was found that the pK a value and the concentration of the used acid for the pretreatment mainly influence the ion exchange capacity, whereas the temperature during pretreatment mainly influences the water uptake. The combination of high values for temperature, relative humidity and contact pressure leads to enhanced ionic conductivity of Nafion® membranes with a maximum value of 85.2 mS cm −1 for the membrane pretreated with HCl. [ABSTRACT FROM AUTHOR]

Anion exchange membranes (AEM) are promising solid polymer electrolytes utilized in alkali fuel cells and electrochemical energy conversion devices. AEMs must efficiently conduct ions while maintaining chemical and mechanical stability under a range of operating conditions. The ionic nature of AEMs leads to stiff and brittle membranes under dry conditions while at higher hydrations, water sorption causes significant softening and weakening of the membrane. In this work, a new polyethylene-b-poly(vinylbenzyl trimethylammonium) polymer (70 kg/mol) was cast into large (300 cm 2 ), thin (12±3 μm) membranes. These membranes exhibited improved elasticity over previously tested AEMs, minimal dimensional swelling, and moderate ionic conductivity (5±2 mS/cm at 50 °C, 95% RH in the bromide form). Extensional testing indicated a 95% reduction in Young's modulus between dry and hydrated states. Further investigation of the complex modulus as a function of hydration, by dynamic mechanical analysis, revealed a sharp decrease in modulus between dry and hydrated states. Mechanical softening was reversible, but the location of the transition displayed hysteresis between humidification and dehumidification. Conductivity increased after membrane softening; suggesting bulk mechanical properties can identify the hydration level required for improved ion transport. Understanding the relationship between ion conduction and mechanical properties will help guide AEM development and identify operating conditions for sustained performance. [ABSTRACT FROM AUTHOR]

Alkaline doped PBI membranes are investigated for their physicochemical properties when employed in alkaline direct alcohol fuel cells. Alkali uptake, water uptake, alcohol permeability, ion conductivity, mechanical strength and evolution of the morphology for the alkaline doped PBI membranes are measured. It is demonstrated that the alkaline doping process has a profound influence on the physicochemical properties of PBI membranes. With a high alkaline doping level, the alkali uptake of alkaline doped PBI membranes reaches 14%. The high alkaline uptake results in a separation of the polymer backbones and partial cleavage of hydrogen bonds, which leads to a reduction in the mechanical strength and an increase the alcohol permeability of alkaline doped PBI membranes. However, the high alkaline doping level is beneficial to the ionic conductivity. The conductivity of alkaline doped PBI membranes increases to 96.1 mS cm −1 at 363.15 K after PBI membranes are doped with 6 M KOH solution. Based on these investigations, a mechanism is proposed to interpret the chemical interaction during the alkaline doping process and its influence on physicochemical properties. The existence of a neutralization reaction and the re-establishment of hydrogen bonding networks should be attributed to the property transformation during the alkaline doping process. [ABSTRACT FROM AUTHOR]

Novel proton conducting composite membranes based on sulfonated polysulfone (sPSU)/SiO 2 doped with phosphomolybdic acid (PMoA) were synthesized, and their proton conductivity in acid solutions was evaluated. The hybrid membranes were prepared by casting and the characterization by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD) confirmed the presence of the inorganic charges into the polymer. Thermal properties and proton conductivity were also studied by means of thermogravimetric analysis (TGA) and electrochemical impedance spectroscopy (EIS), respectively. The incorporation of the inorganic particles modified the thermal and mechanical properties of the sPSU as well as its proton conductivity. Taking into account that a compromise between these properties is necessary, the hybrid membrane with 2%SiO 2 and 20%PMoA seems to be a promising candidate for its application in proton-exchange membrane in fuel cells (PEMFCs) operated at high temperatures. [ABSTRACT FROM AUTHOR]

Anion exchange membrane fuel cells (AEMFCs) have become one of the most promising energy-conversion devices due to the potential of adopting non-noble metal catalysts and faster oxygen reduction reaction kinetics in an alkaline operating environment. Here, a series of anion exchange membranes with high ionic-conductivity and low swelling ratio were prepared from imidazolium-functionalized crosslinked cardo poly(arylene ether sulfone)s for AEMFCs. Two oligomers, tertiary amine-containing poly(arylene ether sulfone) (PES-DA) and bromomethyl-containing poly(arylene ether sulfone) (BPES), are synthesized and then mixed at −40 °C. They are spontaneously inter-crosslinked at room temperature to form dense anion exchange membranes (AEMs), in which the tertiary amine groups of PES-DA rapidly react with the bromomethyl groups of BPES to form the crosslinked bonds. This avoids the use of crosslinking agents and the expense of functional groups. The resulting membranes show a high hydroxide conductivity up to 82.4 mS cm −1 at 80 °C and a slight swelling low to traditional AEMs due to its crosslinked network structure. An open circuit voltage (OCV) of 0.82 V and a maximum power density of 92.1 mW cm −2 are achieved in a H 2 /O 2 single cell. The as-prepared membranes have a great potential for the application in AEMFCs. [ABSTRACT FROM AUTHOR]

Novel graphene based poly(vinyl alcohol)/chitosan nanocomposite membranes are prepared in this study. PVA/chitosan blend membrane (PCS91), the ratio being 9/1, is prepared by direct blend process and solution casting method and used as control in this study. The homogeneous, nonporous graphene or sulfonated graphene modified PCS membranes were prepared by casting the polymer solutions of PVA/chitosan (ratio being 9/1) with different contents of graphene or sulfonated graphene to get graphene modified PCS membranes (PCG), or sulfonated graphene modified PCS membranes (PCsG). The thermal property, KOH uptakes, ionic conductivity, and methanol permeability of the PCG and PCsG nanocomposite membranes are measured. Differential scanning calorimetry, X-ray diffraction, and thermogravimetry analysis are used for the characterization of PCG and PCsG nanocomposite membranes. The polymer electrolyte membranes are formed by immersing the various PCG and PCsG nanocomposite membranes in KOH solution and the ionic conductivity through the polymer electrolyte membrane is studied using the AC impedance technique. [ABSTRACT FROM AUTHOR]

In this contribution the performance of two acid–base blend membranes in an all-vanadium redox-flow battery (VRFB) is studied. The first membrane is a nonfluorinated acid–base blend membrane composed of a sulfonated poly(arylene ether sulfone) and polybenzimidazole PBIOO, the second, partially fluorinated, membrane is composed of a sulfonated polymer from decafluorobiphenyl and bisphenol AF and the polybenzimidazole F 6 PBI. It turns out from gel permeation chromatography experiments that the molecular weight of both membranes degrades in VRFB. However it is found that the partially fluorinated membrane (S1B1) is more stable in VRFB, which can be seen in the number of charge/discharge cycles, while the nonfluorinated membrane S2B2 fails after 137 cycles, the partially fluorinated membrane S1B1 survives 200 cycles. Moreover, the percentage of residual molecular weight of the nonfluorinated membrane after failure (after 137 cycles) is 34.0%, and of the partially fluorinated membrane (after 200 cycles) is 58.8%, respectively. Both membranes show better peak power densities than a Nafion ® 117 membrane operated in VRFB under the same conditions. In contrast to Nafion ® 117 and S2B2, the S1B1 membrane shows stable voltage and energy efficiency within the first 60 charge/discharge cycles. Moreover, the Coulomb efficiency of the S1B1 membrane was higher than that of S2B2 and Nafion ® 117, respectively, being nearly 100%. [ABSTRACT FROM AUTHOR]

Three different ionic liquids (ILs), 1-ethylpyridinium bis(trifluoromethylsulfonyl)imide (EPy TFSI), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM TFSI), and trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide (P 6,6,6,14 TFSI), with the same anion, TFSI − , were added, with or without ZnTf 2 salt, to the host polymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) in order to obtain Gel Polymer Electrolytes (GPEs). The incorporation of IL or IL+ZnTf 2 salt to the polymer produces more amorphous and more ionic membranes when compared to pristine PVdF-HFP films. Ionic conductivity values, impedance spectra, dielectric measurements, voltammograms and results of potential stability depend clearly on the IL cation type used in the GPE. Also, the incorporation of ZnTf 2 salt inside the film increased the ionic conductivity for all GPEs, which can be related to the existence of free triflate anions. The participation of Zn 2+ cations on the conduction process has been demonstrated by cyclic voltammetry and EDX measurements. Among the six GPEs analyzed, the PVdF-HFP+EMIM TFSI+ZnTf 2 membrane exhibits the best results: maximum value of ionic conductivity, 1.73×10 − 1 S m −1 , low activation energy value, and a highly reversible and high current density voltammetric behavior. [ABSTRACT FROM AUTHOR]

Anion exchange membranes (AEMs) have found numerous electrochemical applications because of their good conductivity and permselectivity. Herein, we are reporting a method to prepare silica modified poly(ethyleneimine) (SMPEI) with 3-Glycidoxypropyl-trimethoxysilan (GPTMS) by epoxide ring opening reaction. Stable AEMs of different compositions were prepared with SMPEI and a plasticizer poly(vinyl alcohol) (PVA) by acid catalyzed sol–gel followed by formal cross-linking. The reported method is simple and a green alternative for the preparation of AEM without the use of hazardous chemicals. Suitability of prepared AEMs for electrodialytic application was assessed by analyzing their physicochemical properties, stabilities under operating conditions, conductivity, electro-osmotic and chronopotentiometry studies. A highly suitable membrane, SMPEI/PVA-40, exhibited 55.32 mS cm −1 conductivity (in equilibration with 0.04 N NaCl solution at 30 °C), ion-exchange capacity (1.31 meq g −1 ) and permselectivity (0.79) with good electrodialytic performance. Preparation protocols and properties of the reported composite AEM represent a promising starting point for architecting highly conducting and stable AEMs, but we have to study the trade-off between properties, stabilities and electro-osmotic mass drag before its commercial exploitation. [ABSTRACT FROM AUTHOR]

In this work, the gas tight ceramic–carbonate dual phase hollow fibre membranes were developed in stages. To this end, oxygen ionic conducting ceramic of yttria stabilized zirconia (YSZ) hollow fibre was firstly prepared and structurally optimised for its application as the porous support to infiltrate the melting carbonate phase at high temperatures. The dual phase hollow fibre membranes were characterised by SEM, XRD, room-temperature gas leakage detection and CO2 permeation test at temperatures between 550°C and 950°C. The maximum CO2 flux measured reached 0.22mLcm−2 min−1 at 950°C. [ABSTRACT FROM AUTHOR]

In the present work, effects of 100MeV Si9+ ion irradiation of different fluences on poly(vinylidene fluoride-co-hexafluoro propylene) (PVdF-HFP)-layered silicate nanocomposite electrolyte membranes based on ionic liquid, 1-butyl-3-methylimidazolium bromide have been investigated. With increasing ion fluence, intercalation of PVdF-HFP into the interlayers of layered silicate increases eventually leading to exfoliation of silicate layers at the fluence of 5×1011 ionscm−2. Swift heavy ion (SHI) irradiation induces chain scissions in the polymer leading to increase in amorphicity due to which room temperature ionic conductivity increases with increasing ion fluence. Highest room temperature ionic conductivity of 4.96×10–2 Scm−1 has been obtained at the highest fluence of 1×1012 ionscm−2 employed in the present work. SHI irradiation increases the porosity of the nanocomposite electrolyte membranes as confirmed from scanning electron microscopy results. Contact angle measurements reveal that upon SHI irradiation the hydrophilic electrolyte membranes turn hydrophobic. High electrochemical stability window of −3.9V to 6.5 has been achieved at the highest ion fluence of 1×1012 ionscm−2. Upon SHI irradiation the rate of decrease of ionic conductivity becomes slower indicating enhancement in interfacial stability. [ABSTRACT FROM AUTHOR]

Abstract: PVDF/PMMA blend microporous membranes were fabricated via thermally induced phase separation (TIPS) process using a single diluent. Then the blend membranes were soaked in a liquid electrolyte to form polymer electrolytes. Finally, the polymer electrolytes were assembled in coin cells to test electrochemical properties. The effects of PMMA/PVDF weight ratio on the phase diagram of PVDF/PMMA/diluent system, morphology, crystallinity, crystal structure, mechanical properties and porosity of the membranes were discussed. The electrochemical properties of corresponding polymer electrolytes, such as ionic conductivity, cell charge–discharge capacity and discharge performance at different current densities, electrochemical stability windows, were also investigated in this paper. It was found that the cloud point of the system decreased and the membrane morphology changed from cellular structure to network structure with an increase in the amount of PMMA. Both electrolyte uptake of blend membranes and ionic conductivity of corresponding polymer electrolytes also increased with an increase in the amount of PMMA. The maximum ionic conductivity was found to reach 3.38×10−3 S/cm at 25°C. The graphite/polymer electrolyte/LiFePO4 cells of blend membranes showed higher charge–discharge capacity and better discharge performance at different current densities. Electrochemical stability window was stable up to 4.7V (vs. Li+/Li). [Copyright &y& Elsevier]

Abstract: In this study, Bi1.5Y0.3Sm0.2O3- δ (BYS), an oxide of great ionic conductivity, has been used to develop BYS-La0.8Sr0.2MnO3- δ (LSM) dual-phase ceramic hollow fibre membranes in an objective of promoting oxygen permeation that has been considered as the controlling step of our recent dual-layer ceramic hollow fibre membrane reactor (DL-CHFMR) for methane conversion, and subsequently lowering the temperature needed for both oxygen separation and catalytic reaction. Oxygen permeation of approximately 1.21mlmin−1 cm−2 (900°C, Ar as sweep gas) was achieved by a single-layer BYS–LSM hollow fibre membrane, which is substantially higher than the previous counterpart of (ZrO2)0.90(Sc2O3)0.10(ScSZ)–LSM, proving the advantage of using BYS in promoting oxygen permeation. Although the stability of BYS in strong reducing atmosphere hampers the use of BYS–LSM/BYS–Ni DL-CHFMR for partial oxidation of methane (POM), its great ionic conductivity and catalytic activity to oxidative coupling of methane (OCM) would lead to the further development of more efficient DL-CHFMR design that can be operated at possibly lower temperatures and under less reducing atmospheres. [Copyright &y& Elsevier]

Abstract: Water sorption, water transport and ion transport are compared for polyether–ether ketone polymers functionalized with sulfonic acid, quaternary amine hydroxide, and imidazolium hydroxide. Water sorption in all three ionomers increases modestly with increasing water activity up to a w =0.6 and then increases more rapidly between 0.60.6. The increase in ion conductivity with increasing water activity is 10 times greater for the proton exchanged polymer compared to the hydroxide exchanged polymers. Water permeation from partially saturated vapor streams is primarily diffusion limited for all three ionomers and the permeation rates were approximately the same. Water pervaporation from liquid water appeared to be interfacial transport limited for membranes<120μm thick; the pervaporation rates at 40 and 60°C were independent of membrane thickness. Water sorption and transport show little dependence on the mobile ion while the ion transport appears to depend on both ion size and hydrophilicity of the fixed ion. [Copyright &y& Elsevier]

Abstract: The overall stability of the lithium ion battery separators, under potentially extreme battery operating conditions, will require leading edge design and fabrication techniques to exceed manufacturing and end performance requirements for large scale applications. This paper features the development and performance characterization of an inorganic fiber enhanced composite separator for LIBs. This composite separator can offer a thermally stable alternative for conventional porous polyolefin separators, which shrink significantly at high temperatures. The relative affinities between the electrolyte and the submicron inorganic fibers and the electrolyte and the polyvinylidene fluoride binder ensured a superior wettability of the final separator by the liquid electrolyte. The high porosity and the open porous structure of the composite separator resulted in a good effective ionic conductivity. Coin cells with this composite separator also exhibited stable cycle performance and improved rate capabilities, especially when discharged at rates greater than C/2. [Copyright &y& Elsevier]

Hydrophilic silica (SiO2) nanoparticles (average size = 7 nm), which act as inorganic acids at low pH (<2), were added together with a PEO–PPO–PEO triblock copolymer dispersant to a random disulfonated poly(arylene ether sulfone) copolymer in the potassium salt (—SO3−K+) form in order to control permeation and rejection characteristics of the homopolymer. The dispersants (shell) absorbed on the surface of SiO2 nanoparticles (core) formed a distinctive core–shell structure. The PEO units located at the outside of the dispersant formed complexes with —SO3−K+ groups of BPS-20 via ion–dipole interactions. These interactions induced a compatible binary system following the Flory–Fox equation associated with glass transition temperature (Tg) depression and prevented extraction of the water-soluble dispersant even under aqueous conditions. The ion–dipole interaction, combined with hydrogen bonding between SiO2 and the dispersant, caused SiO2 nanoparticles to be well distributed within the BPS-20 matrix up to a limit of 1 wt.% of SiO2 and minimized the formation of non-selective cavities within the matrix's hydrophilic water channels. The resulting BPS-20_SiO2 nanocomposites showed improved salt rejection and reduced ionic conductivity. These trends are analogous to those of disulfonated copolymer systems, with polar groups creating hydrogen bonding or acid–base complexation with —SO3−K+ groups in BPS copolymers. Well dispersed SiO2 nanoparticles in highly water-permeable desalination membranes are expected to result in an increase in salt rejection but very little change in water permeability. The addition of nanoparticles to desalination membranes may offset the permeability-selectivity tradeoff observed in polymer membranes. Above 1 wt.%, SiO2 nanoparticles increased both the interchain distance between polymer chains and the water uptake. However, the increased hydrophilicity due to high SiO2 content did not yield improved water permeation of the nanocomposite membranes. The SiO2 nanoparticles acted as barriers, hindering water passage (restrictive diffusion) and lowering water permeability. Meanwhile, acidic hydroxyl groups (OH2+) on the SiO2 surface in the sulfonate matrix led to improved ionic conductivity, but NaCl rejection capability decreased because the concentration of —SO3−K+ was diluted by highly absorbed water molecules, resulting in weakened Donnan exclusion. The mechanical properties and chlorine resistance of all BPS-20_SiO2 nanocomposites were comparable to those of BPS-20. [ABSTRACT FROM AUTHOR]

Abstract: Perovskites (La1−x Ca x )FeO3−δ and (La1−x Ca x )(Co0.8Fe0.2)O3−δ with varying La and Ca contents (x =0.4–0.6) were designed by sol–gel route as model membrane materials to be an alternative to Ba- and Sr-based systems for operation in the presence of CO2. It was found that only the first members of the systems with x =0.4 consisted of almost pure perovskite phases. The materials containing more Ca (x =0.5–0.6) exhibited a considerable amount of bi-phase material, such as brownmillerite and/or spinel, after calcination at 1223K. The orthorhombicly distorted (La0.6Ca0.4)FeO3−δ and rhombohedrally distorted (La0.6Ca0.4)(Co0.8Fe0.2)O3−δ perovskites showed relatively high oxygen permeation fluxes at 1223K of 0.26cm3 min−1 cm−2 and 0.43cm3 min−1 cm−2, respectively. The oxygen-ionic conductivity of the materials was improved by about 50% via an asymmetric configuration using a porous support and an approximately 10-μm thick dense layer with the same chemical composition. In situ XRD in an atmosphere containing 50vol.% CO2 and long-term oxygen permeation experiments using pure CO2 as the sweep gas revealed a high tolerance of Ca-based materials toward CO2. Thus, we suggest that Ca-containing perovskite can be considered promising membrane materials if operation in the presence of CO2 is required. [Copyright &y& Elsevier]

Abstract: Novel alkaline anion-exchange membranes (AAEMs) were synthesized by graft copolymerization of vinylbenzyl chloride onto pre-irradiated poly (tetrafluoroethylene-co-perfluoropropyl vinyl ether) film, followed by quaternization and alkalization. Two kinds of radiation modes, continuous radiation and dis-continuous radiation (with 15 min break in each hour''s radiation), were conducted to the PFA films. The structure of the AAEMs was characterized by Fourier transform infrared (FT-IR). The performances of the AAEMs, including ion exchange capacity (IEC), ionic conductivity, water uptake (WU) and methanol permeability, were investigated systematically. The results showed that the degree of grafting of the film prepared by continuous irradiation is higher than the one prepared by discontinuous irradiation, which results in higher IEC, WU and ionic conductivity. The continuously irradiated membrane exhibited a maximum ionic conductivity of 0.05Scm−1 at 60°C. A maximum power density of 16mWcm−2 for a direct methanol single cell was obtained at 60°C with the continuously irradiated membrane as the electrolyte, MnO2/C and PtRu/C as the cathode and anode electrocatalysts, respectively. This result indicates that the direct alcohol alkaline anion-exchange membrane fuel cell is a promising system with further improvement on AAEMs. [Copyright &y& Elsevier]

Abstract: Membranes were prepared by casting a solution of a polymer and ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][TfO] or 1-ethylimidazolium trifluoromethanesulfonate [EIM][TfO] typical representatives of aprotic and protic ionic liquid and evaporating the solvent. The following polymers were used: Udel-type polysulfone, polybenzimidazole derivative containing benzofuranone moieties (PBI-O-Ph), poly(vinylidene fluoride-co-hexafluoropropene) (fluoroelastomer) and Nafion. Polymer–ionic liquid compatibility was investigated by swelling, scanning electron microscopy and differential scanning calorimetry. Membranes conductivities in anhydrous atmosphere depended on temperature, ionic liquid concentration in the membrane, and on the type of matrix polymer. No conductivity could be detected with polysulfone-based membranes due to the incompatibility of polysulfone and the two ionic liquids, low conductivities were found with PBI-O-Ph based membranes, the conductivities of the fully compatible systems based on fluoroelastomer or Nafion matrixes amounted to 40% of that of neat ionic liquids. [ABSTRACT FROM AUTHOR]

Abstract: A series of guanidinium polymeric ionic liquid (PIL) electrolyte membranes combining different anions, such as BF4 −, PF6 −, ClO4 − and N(CF3SO2)2 −, were synthesized through copolymerization and anion exchange reaction as new promising solid polymer electrolytes. The chemical structures of the PILs were characterized by 1H NMR and ATR–FT IR spectra, and their thermal properties, ionic conductivity and electrochemical stability were evaluated, respectively. The PILs present different decomposition temperature and glass transition temperature (T g), and their thermal properties strongly depend on the sort of anions. The 1g2-MA-BF4 possesses the better thermal stability and it decomposes at 353°C. The 1g2-MA-TFSI shows the lower T g and it is below −60°C. The ionic conductivity of the PIL electrolytes depends on the lithium salts used and its content. The best ionic conductivity of the PILs electrolyte 1g2-MA-BF4/LiBF4 (30wt%) was 1.35×10−4 Scm−1 at 30°C. [ABSTRACT FROM AUTHOR]

Abstract: A new carbonate–ceramic dual-phase membrane for high temperature CO2 separation was synthesized from porous La0.6Sr0.4Co0.8Fe0.2O3−δ (LSCF) supports infiltrated with a eutectic molten carbonate (Li2CO3/Na2CO3/K2CO3) mixture. Helium permeances of the LSCF support before and after infiltration of molten carbonate were found to be on the order of 10−6 and less than 10−10 molm−2 s−1 Pa−1 respectively. On average, supports were found to increase in weight by 33% after infiltration. High temperature CO2 permeation experiments were carried out for several membranes of varying thickness under low oxygen partial pressure (). Maximum permeances of 2.01, 3.73, 4.63 and 4.77×10−8 molm−2 s−1 Pa−1 were obtained at 900°C for dual-phase membranes with thicknesses of 3.0, 1.5, 0.75 and 0.375mm respectively. A CO2/Ar separation factor of at least 225 was achieved at 900°C for the 0.375mm thick membrane. The activation energy for CO2 permeation for these membranes was calculated to be 86.4–89.9kJmol−1 depending on membrane thickness. Experimental CO2 permeation data can be well predicted by a model that considers oxygen ionic conduction in the solid phase of LSCF support in conjunction with structure data for the molten carbonate and LSCF solid phases that was characterized by helium permeation and electrical conductivity measurements. [Copyright &y& Elsevier]

Abstract: Based on the principle of molecular design, three comb-like methyl methacrylate copolymer matrixes for gel polymer electrolyte (GPE) were designed and synthesized by reacting methyl methacrylate-maleic anhydride copolymer (P(MMA-MAh)) with poly(ethylene glycol) monomethyl ether (PEGME) of different molecular weight (350, 600, and 750) respectively. The structures of comb-like polymers were characterized by Fourier transform infrared (FTIR) and 1H-nuclear magnetic resonance (1H NMR), and their thermal properties were investigated with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The membranes of P(MMA-MAh) copolymer and comb-like copolymer based polymer electrolytes, plasticized with propylene carbonate (PC) and LiClO4 as salt, have been prepared by solution casting technique respectively. And AC impedance was used to characterize the ion conductivity of GPE systems. Compared with P(MMA-MAh) copolymer, introducing the flexible ether chain segments can reduce the resistance of ion transport in polymer matrix and improve the mobility of electroactive ions in the GPE systems. With the increase in side chain length of copolymers, ionic conductivity of GPEs is improved dramatically. The highest conductivity observed in MMA/MAh-g-PEGME600 GPE system (matrix content: 45wt%) is 1.22×10−3 S/cm at 60°C. And temperature dependence of GPE membranes could be described by Vogel–Tamman–Fulcher (VTF) behavior. TGA curves showed that these gel polymer electrolyte membranes possessed favorable thermal stability for lithium ion battery use. [Copyright &y& Elsevier]

Abstract: A series of cross-linkable poly(ether ether ketone)s (PEEKs) with pendant sulfonic acid groups were synthesized and used to prepare polymer electrolyte membranes for fuel cells. These transparent and flexible membranes are insoluble in common organic solvents and demonstrated little swelling in hot water. Thermal and mechanical stability of the membranes were evaluated using a thermogravimetric analyzer and strain–stress test, respectively. The methanol permeability of the cross-linked PEEKs with pendant sulfonic acid group membranes is much lower than that of Nafion 117 membrane, by more than 10 times. The conductivity of the cross-linked PEEK membrane with a 5% degree of cross-linking is comparable to that of Nafion 117 at 50°C (0.053Scm−1) and even better above 80°C. This kind of membrane is expected to be a good alternative to Nafion 117 in polymer electrolyte fuel cell applications. [Copyright &y& Elsevier]

Abstract: One of the very important barriers for proton exchange membrane fuel cells (PEMFCs) is the decrease in proton conductivity of membrane at elevated temperature and low relative humidity. In this study, inorganic–organic hybrid membranes have been developed in order to improve water retention and proton conductivity at elevated temperature. Using in situ self-assembly technique, the well-dispersed metal oxide nanoparticles (SiO2, ZrO2) with diameters of ∼5nm can be formed through sol–gel process in Nafion® dispersion. It was found that the doped metal oxide nanoparticles did not affect the crystallinity and structure of Nafion® in the membrane significantly. Compared to Nafion® membrane, hybrid membranes show better water retention properties and higher proton conductivity at relatively low relative humidity. [Copyright &y& Elsevier]

Abstract: A theoretical model has been developed for CO2/O2 permeation through a dual-phase membrane consisting of mixed-conducting oxide ceramic (MCOC) and molten carbonate (MC) phases. Somewhat simpler theoretical CO2 permeation equation is obtained for the special case or pure CO2 permeation case, i.e., oxygen partial pressure in the feeding gases is zero or electronic transference number of the MCOC phase is zero. The results show that CO2 permeation flux is much improved by involving oxygen permeation, which is more than one order of magnitude higher than the corresponding CO2 permeation flux for a pure CO2 permeation case. The fluxes of CO2 and O2 increase with increasing O2 partial pressure in the feeding gases. Both the CO2 and O2 permeation fluxes increase with increasing electronic conductivity () of the MCOC phase. The CO2 permeation flux increases with increasing ionic conductivity () of the MCOC phase at a low electronic conductivity, i.e., , while decreases with an increase of at a high electronic conductivity, i.e., . For pure CO2 permeation, the CO2 permeation flux increases with the increase of and decreases with increasing molten carbonate volume fraction. An ordered ceramic pore structure benefits CO2 and O2 permeation. The modeling results are compared with experimental data, and a reasonable agreement is obtained between modeling and experimental data. [Copyright &y& Elsevier]

Abstract: Two step modification of poly(vinyl alcohol) (PVA) by UV radiation and sol–gel process was used to prepare the modified PVA membranes. From the first step modification of PVA by UV radiation with 2-hydroxy ethyl methacrylate (HEMA) monomer, the poly(2-hydroxy ethyl methacrylate) (PHEMA) modified poly(vinyl alcohol), PVAHEMA, was obtained and characterized by Fourier transfer infrared spectra (FTIR) and optical polarizing microscopy for the chemical compositions and morphology. With the second step modification of sol–gel process, the organic–inorganic hybrid sol–gel material, PVAHEMA–SiO2, was prepared. Both of the modified PVA, (PVAHEMA and PVAHEMA–SiO2), were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). To prepare the alkaline solid polymer electrolyte, the various PVAHEMA and PVAHEMA–SiO2 membranes were immersed in 40wt% KOH solution to form the KOH containing polymer electrolyte membranes. And then their performances were conducted with ac impedance spectroscopy to evaluate the ionic conductivity through the membranes. At room temperature, the ionic conductivity increased from 0.044 to 0.073S/cm for the PVAHEMA membrane; whereas the ionic conductivity was about 0.11S/cm for the PVAHEMA–SiO2 membranes. Compared to other reports in references, our hybrid sol–gel membrane is a highly ionic conducting alkaline solid polymer electrolytes membrane. [Copyright &y& Elsevier]