Anion Exchange Membranes For Applications Research Articles

Atomistic Modeling of Quaternized Chitosan Head Groups: Insights into Chemical Stability and Ion Transport for Anion Exchange Membrane Applications.

The chemical stability and ion transport properties of quaternized chitosan (QCS)-based anion exchange membranes (AEMs) were explored using Density Functional Theory (DFT) calculations and all-atom molecular dynamics (MD) simulations. DFT calculations of LUMO energies, reaction energies, and activation energies revealed an increasing stability trend among the head groups: propyl trimethyl ammonium chitosan (C) < oxy propyl trimethyl ammonium chitosan (B) < 2-hydroxy propyl trimethyl ammonium chitosan (A) at hydration levels (HLs) of 0 and 3. Subsequently, all-atom MD simulations evaluated the diffusion of hydroxide ions (OH-) through mean square displacement (MSD) versus time curves. The diffusion coefficients of OH- ions for the three types of QCS (A, B, and C) were observed to increase monotonically with HLs ranging from 3 to 15 and temperatures from 298 K to 350 K. Across different HLs and temperatures, the three QCS variants exhibited comparable diffusion coefficients, underlining their effectiveness in vehicular transport of OH- ions.

Graphene Oxide Nanosheets Reinforced Quaternized Poly(2,6-Dimethyl-1,4-Phenylene Oxide) Composite Membranes with Enhanced Hydroxide Ions Conduction at Subzero Temperature

The realization of high hydroxide ion conductivity on the premise of enough alkaline stability is basic of the practical application of anion exchange membranes (AEMs). In this research, we propose a facile way to enhance the hydroxide ion conductivity at subzero temperature through constructing multilayered microstructures of AEMs. Graphene oxide (GO) nanosheets and 3,6-diazaspiro[5.5]undecane bromide (DSUBr) are alternately deposited on the surface of a quaternized poly(2,6-dimethyl-1,4-phenylene oxide) (QPPO) membrane with the layer by layer self-assembly process. Multilayered and compact microstructures are retained even if the prepared QPPO/(GO/DSUOH)5 membranes are immersed in 2M KOH solution for 300h. The hydroxide ions conduction resistance is reduced, deriving from the well-ordered dispersion of components. For example, the QPPO/2-(GO/DSUOH)5 membrane exhibits the hydroxide ion conductivities of 0.922 mS/cm at -25 °C and 58.5 mS/cm at 80 °C. Furthermore, the prepared AEMs possess the enhanced hydroxide ion conductivity owing to the fine dimension and component stabilities. After the ten-cycle hydroxide ion conductivity stability test, the retention rates of hydroxide ion conductivity are 99.4% at -25 °C and 105% at 30 °C. Additionally, the residual hydroxide ion conductivity reaches 61.6 mS/cm at 80 °C in 2M KOH solution for 624h. A single fuel cell equipped with the QPPO/2-(GO/DSUOH)5 membrane exhibits the maximum power densities of 80.8mW/cm2 at 30 °C and 351.6mW/cm2 at 60 °C.

Two-dimensional MXene supported Ru-Cr(OH)x clusters as an efficient electrocatalyst for hydrogen oxidation reaction

The development of high-performance non-platinum catalysts remains a key challenge for the practical application of anion-exchange membrane fuel cells due to the sluggish kinetics response of the hydrogen oxidation reaction (HOR) in alkaline electrolytes. Herein, we report an outstanding HOR electrocatalyst using a facile one-step method with the two-dimensional double transition metal MXene (Mo2TiC2Tx) as a carrier mixed with metallic ruthenium and Cr(OH)x clusters (Ru-Cr(OH)x/MXene). Specifically, the as-prepared Ru-Cr(OH)x/MXene electrocatalyst exhibits a high apparent kinetic current (jk) of 18.32 mA cm−2 and exchange current (j0) of 1.64 mA cm−2 at an overpotential of 50 mV, respectively, which are 4.74 and 1.46 times as high as those of Pt/C catalyst. Additionally, mechanism experiments indicated that the Ru-Cr(OH)x/MXene electrocatalyst could attenuate the adsorption of hydrogen intermediate (Had) and enhance the adsorption of hydroxyl species (OHad) to promote CO oxidation, which resulted in a significant increase in the HOR activity and enhanced tolerance to CO. Furthermore, combining theoretical studies via density functional theory calculations, our work confirm that the interaction effect of each components of Ru-Cr(OH)x/MXene can optimize the binding energy of the Had and OHad for the HOR. This work develops a new approach to design of HOR electrocatalyst with MXene-based materials.

Functionalization of rubbery domains in SBS triblock copolymers for anion exchange membrane applications with enhanced robustness

A series of anion exchange membranes (AEMs) based on hydrogenated poly (styrene-b-butadiene-b-styrene) (h-SBS) triblock copolymers were prepared via thiol-ene click reaction of the mid-block polybutadiene with 6-mercapto-1-hexanol, followed by hydrogenation of the remaining double bonds, direct bromination of the pendant alcohol group, and substitution of with trimethylamine (TMA). The thiol-ene click reaction provided a facile and effective control of degree of functionalization up to 50 mol% of total CC bonds in the polymer. Membrane properties of the TMA-functionalized h-SBS for AEM applications were investigated by measuring ion exchange capacity (IEC), water uptake, and ion conductivity. h-SBS-TMA-1.83 with 24% degree of functionalization of polybutadiene block exhibited an IEC of 1.83 mequiv./g and the highest hydroxide ion conductivity of 93 mS/cm at 80 °C. IEC and hydroxide ion conductivity of all h-SBS AEMs were preserved after treatment with aq. 1 M NaOH solution at 80 °C for 4 weeks, demonstrating good alkaline stability. The h-SBS AEMs with quaternary ammonium groups tethered to the rubbery polybutadiene block of SBS showed better mechanical properties, lower water uptake, less water swelling under humidified conditions, and higher and more stable hydroxide conductivity at 80 °C than the ones tethered to the rigid polystyrene block of hydrogenated SBS AEMs. These results suggest that ionic group functionalization at the rubbery block of SBS provides mechanically more robust AEMs and is better AEM material design than that of glassy block functionalized AEM.

V-O Species-Doped Carbon Frameworks Loaded with Ru Nanoparticles as Highly Efficient and CO-Tolerant Catalysts for Alkaline Hydrogen Oxidation.

Efficient and CO-tolerant catalysts for alkaline hydrogen oxidation (HOR) are vital to the commercial application of anion exchange membrane fuel cells (AEMFCs). Herein, a robust Ru-based catalyst (Ru/VOC) with ultrasmall Ru nanoparticles supported on carbon frameworks with atomically dispersed V-O species is prepared elaborately. The catalyst exhibits a remarkable mass activity of 3.44 mA μgPGM, which is 31.3 times that of Ru/C and even 4.7 times higher than that of Pt/C. Moreover, the Ru/VOC anode can achieve a peak power density (PPD) of 1.194 W cm-2, much superior to that of Ru/C anode and even better than that of Pt/C anode. In addition, the catalyst also exhibits superior stability and exceptional CO tolerance. Experimental results and density functional theory (DFT) calculations demonstrate that V-O species are ideal OH- adsorption sites, which allow Ru to release more sites for hydrogen adsorption. Furthermore, the electron transfer from Ru nanoparticles to the carbon substrate regulates the electronic structure of Ru, reducing the hydrogen binding energy (HBE) and the CO adsorption energy on Ru, thus boosting the alkaline HOR performance and CO tolerance of the catalyst. This is the first report that oxophilic single atoms distributed on carbon frameworks serve as OH- adsorption sites for efficient hydrogen oxidation, opening up new guidance for the elaborate design of high-activity catalysts for the alkaline HOR.

Hydrogenated diblock copoly(norbornene)s bearing triimidazolium anion exchange membranes with enhanced alkaline stability for fuel cells

Overcoming the trade-off relationship between conductivity and alkaline stability is a crucial challenge for the practical application of anion exchange membranes (AEMs) in fuel cells. The cross-linked hydrogenated diblock copoly (norbornene)s AEMs with bulky substituted s-triazine based triimidazolium cation clusters were prepared. The prepared H-rPNB-T-triMPh-diMIm-1.64 has the low swelling ratio (SR less than 20%), reasonable water uptake (WU = 82.9%), and high ionic conductivity (114.8 mS cm−1) at 80 °C. In addition, the membrane is able to maintain 91.3% of the initial conductivity after being exposed to 1 M NaOH solution at 80 °C for 32 days. The single cells assembled with H-rPNB-T-triMPh-diMIm-1.64 exhibit a peak power density of 272 mW cm−2 under a current density of 650 mA cm−2 at 80 °C. The novel development strategy that the imidazolium cation cluster functionalized poly (norbornene) is promised to be an effective approach to develop the high-performance AEMs for application in fuel cells.

Semi-interpenetrating network anion exchange membranes based on flexible polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene and rigid Poly(vinylbenzyl chloride) for fuel cell applications

Balancing ion conductivity, mechanical strength, and alkali stability is a significant challenge in the application of anion exchange membranes (AEMs) in anion exchange membrane fuel cells (AEMFCs). In this study, rigid poly(4-vinylbiphenyl chloride) (PVB) and flexible polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) are selected as the polymer backbones to create semi-interpenetrating network (SIPN) AEMs. To achieve high ionic conductivity, quaternary ammonium groups are grafted onto each PVB structural unit, and TMHDA reacts with CMSEBS to construct a cross-linking network while also generating quaternary ammonium groups. This approach, along with well-defined micro-morphology, result in SIPN-SEBS/PVB-10 exhibiting an impressive ionic conductivity of 105.7 mS cm−1 at 80 °C. The SIPN structure, formed by the linear quaternary ammonium PVB and cross-linked SEBS, enhances the compatibility between the rigid and flexible components, resulting in good tensile strength (>14.5 Mpa) and elongation at break (>31.8%) for SIPN-SEBS/PVB AEMs at 25 °C in the wet state. Furthermore, SIPN-SEBS/PVB AEMs exhibit excellent chemical stability, in addition to the restricted swelling behavior, which can be attributed to the stable PVB and SEBS main chains. After immersion in a 1 M NaOH solution at 80 °C for 30 days, the degradation of backbones and cations in all membranes is less than 10% and 20%, respectively. Moreover, the peak power density of SIPN-SEBS/PVB-10 in an H2/O2 single fuel cell reaches an impressive value of 379 mW cm−2. Based on these excellent properties, the developed SIPN AEMs hold great promise as candidates for AEMFCs.

Synthesis and Characterization of Ion Exchange Particles for Application of Anion Exchange Membrane

Synthesis and Characterization of Ion Exchange Particles for Application of Anion Exchange Membrane

Nickel‐Based Electrocatalysts for Hydrogen Oxidation Reaction Under Alkaline Electrolytes

AbstractDeveloping highly efficient and cost effective electrocatalysts towards hydrogen oxidation reaction under alkaline electrolyte is essential for the commercial application of anion exchange membrane fuel cells (AEMFCs). Nickel‐based materials showed great performance for alkaline HOR which have been regarded as promising alternatives for Pt‐group metals. In this review, several effective strategies which can successfully optimize the interaction with intermediates and promote the HOR kinetics of Ni under alkaline medium are discussed, including heteroatom doping, forming alloys and compounds, decorating with supports and constructing heterointerfaces. Meanwhile, based on the structural adjustment, the durabilities of Ni‐based materials are enhanced significantly. We believe this paper might provide guidance for future catalysts design and mechanism investigation for alkaline HOR.

Boosting Hydrogen Oxidation Kinetics by Promoting Interfacial Water Adsorption on d-p Hybridized Ru Catalysts

The search for highly efficient and cost-effective electrocatalysts for hydrogen oxidation reaction (HOR) under alkaline electrolytes is essential for the commercial application of anion exchange membrane fuel cells. However, the kinetics of HOR in an alkaline media is much slower than that in an acidic electrolyte, which usually results in orders of magnitude decrease in the catalytic performance. Herein, we report the synthesis of d-p orbital hybridized Ru catalysts through Sn/Ga doping. Density functional theory (DFT) calculations and experimental results including H2-temperature programmed desorption (H2-TPD) and in situ Raman spectra unveil that the electronic structure modification of Ru derived from the unconventional d-p hybridization could lead to the promoted interfacial water adsorption ability and optimized hydrogen adsorption free energy during the alkaline HOR process. As expected, the d-p hybridized Ru catalyst shows much decreased formation energy of water, which contributes to the changed potential-determining step (PDS) and remarkable HOR activity with the mass activity up to 1790 mA mgRu–1. This work not only illustrates the key role of interfacial water adsorption ability but also provides a strategy for rationally designing advanced electrocatalysts for alkaline HOR.

Anion exchange membranes with efficient acid recovery obtained by quaternized poly epichlorohydrin and polyvinyl alcohol during diffusion dialysis

Herein, we discussed the synthesis of quaternized poly epichlorohydrin (QPECH) by the reaction of poly epichlorohydrin (PECH) with N, N-dimethylethanolamine (DMEA). After that, different amounts of QPECH were mixed with the polyvinyl alcohol (PVA) and tetraethyl silicate (TEOS) to fabricate a series of anion exchange membranes (AEMs) by sol-gel reaction. The chemical structure of the synthesized QPECH was effectively proved by Fourier transform infrared (FTIR) and 1H NMR. Hereafter, the composite membrane structure was determined by FT-IR, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and the physical and chemical properties such as thermogravimetric analysis (TGA), water uptake (WR), ion exchange capacity (IEC), linear expansion rate (LER) and diffusion dialysis (DD) were tested. The performance, such as acid recovery and selectivity of PVA/QPECH composite membranes with different QPECH content, was discussed comprehensively. The results showed that the WR of the composite membrane was 82.35–158.54%, the LER was 19.23–40.74%, and the IEC was from 0.64 to 1.76 mmol/g. In the DD test simulating waste acid recovery, the acid dialysis coefficient (UH+) was in the range of 11.1–30.0*10-3 m/h, and the separation factor (S) was 24.79–42.24. The UH+ and S of the composite membranes were all better than that of commercial membrane DF-120. In conclusion, this study demonstrated that the application of anion exchange membrane based on PVA/QPECH had the potential in acid recovery by DD method.

The effect of the piperidinium structure on anion-exchange membranes for applications in alkaline water electrolysis cells

The effect of methyl and trifluoromethyl substituents and bonding positions of piperidinium groups on anion-exchange membranes was investigated for applications in alkaline water electrolysis cells.

Hybrid polymer inclusion membrane as anion exchange membrane for recovering Pd2+ ions in electrogenerative process

A novel non-plasticized nano-porous hybrid inorganic-organic polymer inclusion membrane (PIM) was synthesized, characterized, and evaluated as an anion exchange membrane for application in electrogenerative processes to recover Pd2+ ions. Ionic liquids 1-ethyl-3-me­thyl­imidazolium chloride (EMIM-Cl) and 1-butyl-3-methylimidazolium chloride (BMIM-Cl) were used as the carrier molecules in the polymeric network of PIM to enhance anion exchange process. This hybrid anion exchange membrane also consists of a polymeric matrix of non-plasticized cellulose triacetate modified by incorporating an inorganic material (silane) prepared by the sol-gel route. Different parameters affecting the ion transport performance efficiency, i.e., the composition of the membrane, type of ionic liquid (carrier molecule) and ion–exchange capacity, were investigated and optimized. In the electrogenerative process, the results revealed that the prepared PIM yields better recovery results for recovering Pd2+ ions from its chloride solution compared to the commercial anion exchange membrane Neosepta® AM-01, with a full recovery of 100 mg/L Pd2+ ions in 30 min. This preliminary study shows that the prepared low-cost hybrid anion exchange membrane PIM can act as an inexpensive material suitable for the rapid and efficient recovery of Pd2+ ions from an aqueous solution.

Computational Approaches to Alkaline Anion-Exchange Membranes for Fuel Cell Applications.

Anion-exchange membranes (AEMs) are key components in relatively novel technologies such as alkaline exchange-based membrane fuel cells and AEM-based water electrolyzers. The application of AEMs in these processes is made possible in an alkaline environment, where hydroxide ions (OH-) play the role of charge carriers in the presence of an electrocatalyst and an AEM acts as an electrical insulator blocking the transport of electrons, thereby preventing circuit break. Thus, a good AEM would allow the selective transport of OH- while preventing fuel (e.g., hydrogen, alcohol) crossover. These issues are the subjects of in-depth studies of AEMs-both experimental and theoretical studies-with particular emphasis on the ionic conductivity, ion exchange capacity, fuel crossover, durability, stability, and cell performance properties of AEMs. In this review article, the computational approaches used to investigate the properties of AEMs are discussed. The different modeling length scales are microscopic, mesoscopic, and macroscopic. The microscopic scale entails the ab initio and quantum mechanical modeling of alkaline AEMs. The mesoscopic scale entails using molecular dynamics simulations and other techniques to assess the alkaline electrolyte diffusion in AEMs, OH- transport and chemical degradation in AEMs, ion exchange capacity of an AEM, as well as morphological microstructures. This review shows that computational approaches can be used to investigate different properties of AEMs and sheds light on how the different computational domains can be deployed to investigate AEM properties.

(Invited) Operando EPR Study on Radicals in Anion-Exchange Membrane Fuel Cells

In the rapidly developing modern society, there is an urgent need for the wide-ranging availability of advanced and eco-friendly energy sources. One of the possible alternatives is the application of anion exchange membrane fuel cells (AEMFCs) with a catalyst reducing dioxygen efficiently. These promising devices can revolutionize the energy sector since they practically produce no pollution. However, to make them more widely used, several obstacles must be overcome. As a result, vast-ranging investigations focus on improving the properties of conductive polymer membranes [1] and catalysts for the oxygen reduction reaction (ORR) [2]. The durability of the membrane electrode assembly (MEA) is one of the critical requirements for the successful commercialization of anion exchange membrane fuel cells (AEMFCs). Despite significant impacts of nucleophilic degradation on ion-exchange capability and the anionic conductivity of investigated membranes, it is believed to affect only cationic sites of membrane polymers and thus cannot explain the reported loss in the mechanical strength of degraded AEMs. Such a phenomenon might be related to polymer backbone degradation caused by free radicals. This was widely described in the literature in the case of fuel cells using proton-conducting membranes [3] but barely mentioned for AEMFCs [4]. Since the oxidative degradation of hydrocarbon polymers is very well known, we aimed to comprehensively investigate the formation of the short-lived species generated during the operation of AEMFCs as well as stable radicals present in the polymer membranes.We investigated the LDPE-base membranes with Pt black, Pd black, PdAg, and Ag as the ORR catalysts, whereas for HOR the Pt black, Pd black, and NiFe catalysts were used. The in-situ measurements are performed with a micro-AEMFC inserted into a resonator of an electron paramagnetic resonance (EPR) spectrometer, which enables separate monitoring of radicals formed on the anode and cathode sides. The creation of radicals was monitored by the EPR spin trapping technique. In Figure 1 the EPR spectra of DMPO spin adducts trapped during operation of micro-fuel cell placed in EPR spectrometer cavity are presented. In this experiment, the LDPE-base membrane with platinum catalysts on both sides was used. The main detected adducts during the operation of the micro-AEMFC were DMPO-OOH and DMPO-OH on the cathode side and DMPO-H on the anode side. Additionally, we clearly show the formation and presence of stable radicals in AEMs during and after long-term AEMFC operation [5]. Preliminary results suggest that the creation of the short-living radicals during AEMFCs operation is independent of the used membrane. However, the applied catalysts determine the number of detected radicals. The EPR investigations indicate that, in addition to the known chemical degradation mechanisms of the cationic ammonium groups of the membrane, oxidative degradation, including radical reactions, has to be taken into account when the stability of an anion conductive polymer for AEMFCs is investigated. The formation of stable radicals in AEMs was proven for the first time in this study. All short-living radicals formed during the AEMFC operation were fully identified. The presence of radicals in the AEM after AEMFC testing indicates that reactive oxygen species may play a very important role in the degradation mechanism of the anion conducting polymers. Results from this study shed light on the understanding of radical formation and presence in the membranes during AEMFC tests, which in turn may help to solve the challenge of anion exchange membrane stability. Acknowledgments. This work was supported by the Polish National Science Centre (NCN) project OPUS-14, No. 2017/27/B/ST5/01004.

Exploring highly soluble ether-free polybenzimidazole as anion exchange membranes with long term durability

A series of ether-free polybenzimidazoles (PBIs) containing alicyclic and aliphatic segments were synthesized for the application of anion exchange membranes (AEMs). The PBI-based AEMs prepared in this work (denoted as Pip-PBIs) possessed both high anionic conductivity and alkaline stability by grafting long alkyl chain 1-methylpiperidinium. Benefiting from the random arrangement of aromatic-alicyclic/aliphatic in backbone and their flexible spatial configurations, most Pip-PBIs showed significantly improved solubility in low boiling point solvents namely methanol and isopropanol, which could allow it as ionomer to improve the phase interface between catalyst and AEMs. Meanwhile, the flexible segments in backbone contributed to the formation of ion conductive channel, the Pip-PBI-C achieved the highest hydroxide ions conductivity of 108.8 mS cm −1 at 80 °C, and the conductivity could retain 82.9% after soaking in a 2 M aqueous NaOH at 80 °C for 1536 h. Furthermore, Pip-PBIs demonstrated well oxidation stability in Fenton's reagent (4 ppm FeSO 4 and 3% H 2 O 2 ). Moreover, the H 2 –O 2 fuel cell using Pip-PBI-C as membrane achieved a high open circuit voltage of 1.0 V and a peak power density of 785.6 mW cm −2 at the current density of 1802.9 mA cm −2 . ● A series of polybenzimidazoles containing alicyclic or aliphatic are prepared; ● Pip-PBIs with flexible chain segments have well solubility in low boiling point solvents namely methanol and isopropanol; ● The Pip-PBI-C shows the OH − conductivity of 108.8 mS cm −1 at 80 °C and excellent alkaline stability; ● The Pip-PBI-C shows the peak power density of 785.6 mW cm −2 at 1802.9 mA cm −2 in a H 2 –O 2 fuel cell.

RuP Nanoparticles Supported on N, O Codoped Porous Hollow Carbon for Efficient Hydrogen Oxidation Reaction

AbstractHighly active and low‐cost anodic hydrogen oxidation reaction (HOR) catalysts play a significant role in the large‐scale application of anion exchange membrane fuel cells (AEMFCs). Herein, a novel anodic HOR electrocatalyst with RuP nanoparticles loaded on N, O codoped porous hollow carbon (RuP/NOC) is prepared. The catalyst exhibits high catalytic activity toward HOR, achieving a kinetic mass activity of 3.25 mA µg–1PGM at 50 mV, 13 times higher than that of Ru/NOC and even superior to that of Pt/C. Density functional theory (DFT) calculations demonstrate that the transfer of electrons from ruthenium to phosphorus shifts down the d‐band center of Ru, weakening the hydroxyl binding energy and decreasing the reaction energy barrier for HOR, thus enhancing the catalytic activity of Ru.

Alkaline Stable Anion Exchange Membranes Based on Cross-Linked Poly(arylene ether sulfone) Bearing Dual Quaternary Piperidines for Enhanced Anion Conductivity at Low Water Uptake.

Alkaline stable anion exchange membranes based on the cross-linked poly(arylene ether sulfone) grafted with dual quaternary piperidine (XPAES-DP) units were synthesized. The chemical structure of the synthesized PAES-DP was validated using 1H-NMR and FT-IR spectroscopy. The physicochemical, thermal, and mechanical properties of XPAES-DP membranes were compared with those of two linear PAES based membranes grafted with single piperidine (PAES-P) unit and conventional trimethyl amine (PAES-TM). XPAES-DP membrane showed the ionic conductivity of 0.021 S cm−1 at 40 °C which was much higher than that of PAES-P and PAES-TM because of the possession of more quaternary ammonium groups in the cross-linked structure. This cross-linked structure of the XPAES-DP membrane resulted in a higher tensile strength of 18.11 MPa than that of PAES-P, 17.09 MPa. In addition, as the XPAES-DP membrane shows consistency in the ionic conductivity even after 96 h in 3 M KOH solution with a minor change, its chemical stability was assured for the application of anion exchange membrane fuel cell. The single-cell assembled with XPAES-DP membrane displayed a power density of 109 mWcm−2 at 80 °C under 100% relative humidity.

Hydroxide ion-conducting metal–organic frameworks for anion-exchange membrane applications

Metal–organic frameworks are promising materials for ion-exchange membrane applications. This review paper examines their current status and potential to meet the rigorous ion-conductivity requirements, while identifying promising approaches for improvement.

Macromolecular crosslink of imidazole functionalized poly(vinyl alcohol) and brominated poly(phenylene oxide) for anion exchange membrane with enhanced alkaline stability and ionic conductivity

Anion exchange membranes (AEMs) are important energy conversion device for fuel cell applications, where the overall redox reaction happened. Both alkaline stability and ionic conductivity should be considered in the long-term use of fuel cells. In this work, imidazole functionalized polyvinyl alcohol was designed as the functional macromolecular crosslinking agent to fabricate crosslinked AEMs with brominated poly(phenylene oxide) matrix. Benefitting from the macromolecular crosslinked structure, the membranes displayed enhanced ionic conductivity and alkaline stability at elevated temperature. Moreover, membrane with ion exchange capacity of 1.54 mmol/g displayed ionic conductivity of 78.8 mS/cm at 80 °C, and the conductivity could maintain 75% of the initial value after immersion in 1 M NaOH solution at 80 °C for 1000 h. Moreover, a peak power density of 105 mW/cm2 was achieved when the assembled single cell with c-91 was operated at 60 °C. These results indicated that the construction of macromolecular crosslinked AEMs have great potential in the practical application of anion exchange membranes fuel cells.