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1.
We report a novel comb-shaped anion exchange membrane based on poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) and 4-(dimethylamino)butyraldehyde diethyl acetal (DABDA). The Menshutkin reaction successfully introduced DABDA into the brominated PPO backbone, which was proved through FT-IR and 1H NMR. The distinct hydrophilic/hydrophobic microphase separation structure observed by transmission electron microscope (TEM). As the increase of grafting degree, so does the water uptake, swelling ratio, hydroxide conductivity and alkaline stability. The membranes also possess good mechanical property with tensile strength from 14.2 to 38.11 MPa. This is due to the increasing number of hydroxide and unique steric hindrance effect caused the higher water uptake and higher dimensional stability. Simultaneously, especially PPO/DABDA-60 in comb-shaped membranes demonstrate an excellent long-term alkali resistance stability. In a 576-h alkali resistance stability test, the retained ionic conductivity of the PPO/DABDA-60 membrane is 96% of the initial value. The PPO/DABDA-60 is a potential candidate material for AEM.  相似文献   

2.
To develop polymer electrolyte membrane with both high hydroxide conductivity and good alkaline stability, series of poly(arylene ether sulfone)s block copolymers bearing varied imidazolium functionalized aromatic pendants are synthesized, and the relationship between ionic pendants and the membrane properties are investigated and discussed. Atomic force microscopy (AFM) results suggest that, the well-controlled block copolymers and pendent aromatic chain structures are responsible for the formation of the well-defined microphase-separated morphology which is benefit to construct highly conductive ionic transport channels in membrane. The membranes tethering longer imidazolium functionalized aromatic pendants (Im-DFDM-bPES) exhibit large hydroxide conductivity than those bearing shorter ones (Im-DFDB-bPES) in spite of their comparable IEC values, this is in accordance with their sizes of hydrophilic domains in membrane. Among the membranes, Im-DFDM-bPES-x7y32 with IEC of 1.30 mequiv g?1 gives the highest hydroxide conductivity (34.2 and 98.7 mS cm?1 at 25 and 80 °C, respectively). Besides, both Im-DFDM-bPES and Im-DFDB-bPES membranes exhibit high alkaline stability after aging under severe conditions (4 M NaOH at 80 °C) for 144 h, where the aged Im-DFDM-bPES and Im-DFDB-bPES give hydroxide conductivity remaining by 74.8%–77.2% and 64.5%–66.4%, mechanical properties with maximum stress of 47.36–51.30 MPa and 60.03–62.28 MPa, respectively, indicating good chemical stability of both imidazolium moiety and block copolymer backbone.  相似文献   

3.
A series of tunable bis-pyridinium crosslinked PEEK-BiPy-x anion exchange membranes (AEMs) are prepared successfully to improve the “trade-off” between ionic conductivity and alkaline stability. The crosslinking density of bis-pyridinium is optimized to promote microphase separation and guarantee the free volume. All the PEEK-BiPy-x membranes have a distinct microphase separation pattern observed by atomic force microscopy (AFM) and the PEEK-BiPy-x membranes also display adequate thermal, mechanical and dimensional stability. Impressively, the PEEK-BiPy-0.5 membrane exhibits maximum tensile strength (58.53 MPa) and highest IEC of 1.316 mmol·g?1. Meanwhile, its hydroxide conductivity reaches up to 70.86 mS·cm?1 at 80 °C. Besides, great alkaline stability of PEEK-BiPy-0.5 membrane is obtained with conductivity retention of 91.74% after 1440 h in 1 M NaOH solution, owing to the crosslinked structure of the AEMs and steric effect of bis-pyridinium cations. Overall, the PEEK-BiPy-x membranes possess potential applications in AEMs.  相似文献   

4.
Partially crosslinked anion exchange membranes (AEMs) with imidazolium-based cationic functionalities were fabricated based on a poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) matrix. The PPO was activated by bromomethylation and functionalized with methylimidazole and 1,4-bis(imidazolyl)butane at different ratios through a gentle and facile heat curing method. The use of 1,4-bis(imidazolyl)butane resulted in a membrane with cationic functionalities incorporated in covalent crosslinks, which allowed for high ion exchange capacities (IECs) without compromising on mechanical robustness. Comprehensive characterizations were performed in terms of thermal stability, water uptake, IEC, swelling, conductivity, mechanical properties and alkaline stability to investigate the correlation of the structure and physicochemical properties. Comparing with the un-crosslinked imidazolium PPO membrane, crosslinked membranes exhibited improved mechanical robustness and alkaline stabilities. The membrane with a crosslinking degree of 10% displayed an IEC of around 1.5 mmol g−1, tensile strength of 4.1 MPa, hydroxide ion conductivity of 40.5 mS cm−1, and a retained ratio in conductivity of 40% after tolerance test of nearly 150 h in 1 mol L−1 KOH (aq.) at 60 °C.  相似文献   

5.
To mitigate the membrane stabilities (dimensional and mechanical) and ionic properties, we report well functionalized hydrophilic and hydrophobic (responsible for stabilities) phase separated quaternized anion exchange membrane (AEM). The N,N,N,N-Tetramethyl-1,3-propanediamine quaternized AEM spliced with alkyl chain (DQCP-36) formed self-amassed morphology with larger ionic clusters. The most suitable optimized AEM (DQCP-36) demonstrated enhanced hydroxide ion conductivity (4.66 × 10?2 S cm?1), ion-exchange capacity (1.35 meq./g) and lower activation energy (11.52 kJ/mol). These AEMs showed self-amassed morphology (well balanced hydrophilic and hydrophobic domain) and excellent stabilities (thermal, alkaline and dimensional). Under harsh alkaline medium (2 M NaOH) at 60 °C, DQCP-36 AEM showed about 9% reduction in conductivity after 700 h treatment, and assessment to be a suitable candidate for alkaline fuel cells.  相似文献   

6.
A new type of symmetrical bis-crown ether is prepared by connecting dibenzo-18-crown-6 ether on both sides of the chromotropic acid, and then grafting the aforementioned bis-crown ether onto polyvinyl alcohol matrix to prepare a series of anion exchange membranes (AEMs), which their have high conductivity and strong alkali stability. These synthesized membranes were named B-CX%-P AEMs (x is the mass percentage of the symmetrical bis-crown ether (B–C)). Then, the chemical structure of aforementioned AEMs were verified by means of 1H NMR, FT-IR and UV. Meanwhile, the OH conductivity, alkaline stability and single cell performance of the synthesized membrane were also investigated. The results revealed that the conductivity of B–C30%-P membrane is the highest at 80 °C (235 mS cm−1), and the power density is also the highest (197 mW cm−2), and the alkali stability of the membrane synthesized in this paper was also improved. The conductivity at 80 °C was only reduced by 4%, which was obtained by immersing the B–C30%-P membrane immersed in 6 mol L−1 KOH solution for 168 h, which the aforementioned results proved that the synthesized membrane in this research had excellent OH conductivity and alkaline stability.  相似文献   

7.
Traditional quaternary ammonium (QA)-type anion exchange membranes (AEMs) usually exhibit insufficient alkaline stability, which impede their practical application in fuel cells. To address this issue, a facile method for the simple and accessible preparation of QA-type AEMs with improved alkaline stability was developed in this study. A series of novel AEMs (QPPO-xx-OH) were prepared from commercially available poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) and 3-(dimethylamino)-2,2-dimethyl-1-propanol, via a three-step procedure that included bromination, quaternization, and ion exchange. Scanning electron microscopy revealed that dense, uniform membranes were formed. These QPPO-xx-OH membranes exhibited moderate hydroxide conductivities with ranges of 4–15 mS/cm at 30 °C and 12–36 mS/cm at 80 °C. When tested at similar ion exchange capacity (IEC) levels, the IEC retentions of QPPO-xx-OH membranes were 16–22% higher than that of traditional PPO membranes containing benzyltriethylammonium ions, after immersed in 2 M NaOH aqueous solution at 60 °C for 480 h, and the QPPO-47-OH membrane displayed excellent alkaline stability with the IEC retention of 92% after 480 h. In addition, the QPPO-xx-OH membranes also exhibited robust mechanical properties (tensile strength up to 37.6 MPa) and good thermal stability (onset decomposition temperature up to 150 °C). This study provides a new and scalable method for the facile preparation of AEMs with improved alkaline stability.  相似文献   

8.
Anion exchange membrane from poly(phenylene oxide) containing pendant quaternary ammonium groups is fabricated for application in alkaline polymer electrolyte fuel cells (APEFCs). Chloromethylation of poly(phenylene oxide) (PPO) was performed by aryl substitution and then homogeneously quaternized to form an anion exchange membrane (AEM). The influence of various parameters on the chloromethylation reaction was investigated and optimized. The successful introduction of the above groups in the polymer backbone was confirmed by 1H NMR and FT-IR spectroscopy. Membrane intrinsic properties such as ion exchange capacity, water uptake and ionic conductivity were evaluated. The membrane electrolyte exhibited an enhanced performance in comparison with the state-of-the-art commercial AHA membrane in APEFCs. A peak power density of 111 mW/cm2 at a load current density of 250 mA/cm2 was obtained for PPO based membrane in APEFCs at 30 °C.  相似文献   

9.
Anion exchange membranes with enough alkaline stability and ionic conductivity are essential for water electrolysis. In this work, a class of anion exchange membranes (PAES-TMI-x) with dense 1,2,4,5-tetramethylimidazolium side chains based on poly(aryl ether sulfone)s are prepared by aromatic nucleophilic polycondensation, radical substitution and Menshutkin reaction. Their chemical structure and hydrophilic/hydrophobic phase morphology are characterized by hydrogen nuclear magnetic resonance (1H NMR) and atomic force microscope (AFM), respectively. The water uptake, swelling ratio and ionic conductivity for PAES-TMI-x are in the range of 23.8%–48.3%, 8.3%–14.3% and 18.22–96.31 mS/cm, respectively. These AEMs exhibit high alkaline stability, and the ionic conductivity for PAES-TMI-0.25 remains 86.8% after soaking in 2 M NaOH solution at 80 °C for 480 h. The current density of 1205 mA/cm2 is obtained for the water electrolyzer equipped with PAES-TMI-0.25 in 2 M NaOH solution at 2.0 V and 80 °C, and the electrolyzer also has good operation stability at current density of 500 mA/cm2. This work is expected to provide a valuable reference for the selection and design of cations in high-performance AEMs for water electrolysis.  相似文献   

10.
To avoid the detrimental effect of aryl ethers on the alkali stability of anion exchange membrane (AEM), elaborately designed and synthesized poly(styrene-co-4-vinyl pyridine) (PS4VP) copolymer without aryl ether linkages is used to prepare AEMs. By introducing commercialized polyquaternium-10 (PQ-10) as the main ion-conducting molecule, the fully-interpenetrating polymer network quaternized PS4VP/PQ-10 (F-IPN QPS4VP/PQ-10) AEMs are prepared by cross-linking PS4VP and PQ-10, respectively. The as-prepared F-IPN QPS4VP/PQ-10 AEMs have obvious nanoscale microphase-separated morphologies, which ensure the membranes have good mechanical properties and dimensional stability. With optimized component ratios, F-IPN QPS4VP/PQ-10 AEM exhibits high ionic conductivity (74.29 mS/cm at 80 °C) and power density (111.83 mW/cm2 at 60 °C), as well as excellent chemical stabilities (94.36% retaining of initial mass after immersion in Fenton reagent at 30 °C for 10 days, and 92.28% retaining of original ionic conductivity after immersion in 1 M NaOH solution at 60 °C for 30 days), which are greater than those of semi-interpenetrating polymer network QPS4VP/PQ-10 AEM. In summary, a combination of fully-interpenetrating polymer network and stable polymer chains and ion-conducting moieties is found to effectively overcome the trade-off between high ionic conductivity and good dimensional/chemical stabilities.  相似文献   

11.
This paper reports the performance of a graphene oxide modified non noble metal based electrode in alkaline anion exchange water electrolyzer. The electrolytic cell was fabricated using a polystyrene based anion exchange membrane and a ternary alloy electrode of Ni as cathode and oxidized Ni electrode coated with graphene oxide as anode. The electrochemical activity of the graphene oxide modified electrode was higher than the uncoated electrode. The anion exchange membrane water electrolyzer (AEMWE) with the modified electrode gave 50% higher current density at 30 °C with deionised water compared to that of an uncoated electrode at 2 V. Performance was found to increase with increase in temperature and with the use of alkaline solutions. The results of the solid state water electrolysis cell are promising method of producing low cost hydrogen.  相似文献   

12.
The poly(ether ether ketone) (PEEK) was prepared as organic matrix. ZIF-8 and GO/ZIF-8 were used as fillers. A series of novel new anion exchange membranes (AEMs) were fabricated with imidazole functionalized PEEK and GO/ZIF-8. The structure of ZIF-8, GO/ZIF-8 and polymers are verified by 1H NMR, FT-IR and SEM. This series of hybrid membranes showed good thermal stability, mechanical properties and alkaline stability. The ionic conductivities of hybrid membranes are in the range of 39.38 mS cm?1–43.64 mS cm?1 at 30 °C, 100% RH and 59.21 mS cm?1–86.87 mS cm?1 at 80 °C, 100% RH, respectively. Im-PEEK/GO/ZIF-8-1% which means the mass percent of GO/ZIF-8 compound in Im-PEEK polymers is 1%, showed the higher ionic conductivity of 86.87 mS cm?1 at 80 °C and tensile strength (38.21 MPa) than that of pure membrane (59.21 mS cm?1 at 80 °C and 19.47 MPa). After alkaline treatment (in 2 M NaOH solution at 60 °C for 400 h), the ionic conductivity of Im-PEEK/GO/ZIF-8-1% could also maintain 92.01% of the original ionic conductivity. The results show that hybrid membranes possess the ability to coordinate trade-off effect between ionic conductivity and alkaline stability of anion exchange membranes. The excellent performances make this series of hybrid membranes become good candidate for application as AEMs in fuel cells.  相似文献   

13.
The preparation of quaternary ammonium polysulfone anion exchange membranes (AEMs) with good dimensional stability and alkaline stability is an urgent problem to solve. In response, a series of cross-linked based on polysulfone and 4, 4′-trimethylenedipiperidine (TMDP) as crosslinkers with different degrees AEMs were developed in this work through a simple process. Among the fabricated AEMs, CAPSF-5 exhibits superb alkaline stability in a 1 M KOH aqueous solution at 60 °C for 15 days, whereas the non-crosslinked APSF membrane became tremendously brittle within 24 h and could not be further studied under the same conditions. In addition, even at 60 °C, CAPSF-5 demonstrates a superior dimensional stability compared to the non-crosslinked APSF membrane due to the formation of a dense internal network structure. These observations demonstrate that crosslinked CAPSF membranes can be a viable strategy to improve the deficiency of the polysulfone backbone, especially in terms of alkaline stability.  相似文献   

14.
In this study, we investigated the long-term stability of anion exchange membrane water electrolyzers (AEMWEs) under various bias conditions. The cell performance was relatively stable under conditions of voltage cycling in a narrow range, constant voltage and constant current. On the other hand, a relatively dynamic condition, voltage cycling, in a wide range detrimentally affected the cell stability. Abnormally high negative and positive currents were observed when the cell voltage was switched between 2.1 and 0 V. Impedance results and post-material analyses indicated that the performance degradation was mainly due to anode catalyst detachments, which increased non-ohmic resistance in the wide range voltage cycling. An increase in ohmic resistance was also observed, which was due to the membrane dehydration that occurred in the frequent rest times. Thus, it can be said that the voltage cycling range as well as the frequency of rest times are critical operational parameters in determining the long-term stability of AEMWEs.  相似文献   

15.
We designed and synthesized a poly(ether imide) (PEI) membrane that has good chemical and mechanical stabilities. Alkalized PEI (A-PEI) membrane was fabricated by solution casting of chloromethylated PEI (CM-PEI) followed by quaternization and alkalization. The chemical structure of the synthesized polymers was verified by proton nuclear magnetic resonance (1H NMR) and Fourier-transform infrared spectroscopy (FT-IR). Physiochemical properties of the membrane such as ion exchange capacity, water uptake, and swelling ratio were investigated. The membranes with a high degree of chloromethylation (DC) exhibited elevated hydroxide ion conductivity in range of 6.7–44.2 mS/cm at 90 °C under 100% relative humidity (RH). The hydrophilic-hydrophobic phase separation was verified by atomic force microscope (AFM) and small angle X-ray scattering (SAXS) measurements. Chemical stability was evaluated by measuring the durability of membranes while they were soaked in oxidative and alkaline solutions at 60 °C for 200 h.  相似文献   

16.
The “trade-off” effect between hydroxide conductivity and dimensional stability is challenging issue for anion exchange membrane fuel cells (AEMFCs). In this study, the framework of UiO-66-NH2 is for the first time applied to anion exchange membranes (AEMs). The robust pore walls of UiO-66-NH2 with mechanical and structural durabilities protect the membrane from the excessive swelling effects (a swelling ratio of 7%). In addition, the framework of UiO-66-NH2 is directly modified into (UiO-66-NH2)+Cl as hydroxide conduction channels by anion stripping for the first time. And we construct well-organized ion nanochannels by the in-situ self-assembly of N,N,N′,N' -tetramethyl-1,6-hexanediamine (TMHDA) and allyl bromide within the highly ordered pores of (UiO-66-NH2)+Cl. The obtained QA@(UiO-66-NH2)+Cl then incorporated into pristine membrane (QAPPO) to fabricate the novel multi-channel AEMs. The hydroxide conductivity of QA@(UiO-66-NH2)+Cl/PPO is up to 123 mS⋅cm−1 at 80 °C, which is greatly improved compared to QAPPO pristine membrane.  相似文献   

17.
This work reported an alkaline anion exchange membrane water electrolyser (AAEMWE) without noble metal as the catalyst. Methylated melamine grafted poly vinyl benzyl chloride (mm-qPVBz/Cl) was synthesized and cast as the membrane. The conductivity of this hydroxide ion exchange membrane increased from 1.6 × 10−2 S cm−1 to 2.7 × 10−2 S cm−1 when the temperature was increased from 25 °C to 60 °C. Membranes were examined using TEM. The oxygen evolution catalyst used was based on Cu0.7Co2.3O4 particle 20–30 nm in size, synthesized through a thermal decomposition method. A membrane electrode assembly was prepared with the resultant membrane as electrolyte, the Cu0.7Co2.3O4 nano-particles as the anode catalyst and Ni nano-powders as the hydrogen evolution catalyst. SEM observations showed that the catalysts were well dispersed on the electrodes. The polarization curves exhibited onset voltages for water electrolysis of around 1.5 V. The MEA polarisation in deionised water exhibited voltages of 2.19 V, 2.05 V, 1.99 V at a current density of 100 mA cm−2 at temperatures of 25 °C, 40 °C and 55 °C respectively.  相似文献   

18.
In recent years, ether-free polyaryl polymers prepared by superacid-catalyzed Friedel-Crafts polymerization have attracted great research interest in the development of anion exchange membranes(AEMs) due to their high alkali resistance and simple synthesis methods. However, the selection of monomers for high-performance polymer backbone and the relationship between polymer structure construction and properties need further investigated. Herein, a series of free-ether poly(aryl piperidinium) (PAP) with different polymer backbone steric construction were synthesized as stable anion exchange membranes. Meta-terphenyl, p-terphenyl and diphenyl-terphenyl copolymer were chosen as monomers to regulate the spatial arrangement of the polymer backbone, which tethered with stable piperidinium cation to improve the chemical stability. In addition, a multi-cation crosslinking strategy has been applied to improve ion conductivity and mechanical stability of AEMs, and further compared with the performance of uncrosslinked AEMs. The properties of the resulting AEMs were investigated and correlated with their polymer structure. In particular, m-terphenyl based AEMs exhibited better dimensional stability and the highest hydroxide conductivity of 144.2 mS/cm at 80 °C than other membranes, which can be attributed to their advantages of polymer backbone arrangement. Furthermore, the hydroxide conductivity of the prepared AEMs remains 80%–90% after treated by 2 M NaOH for 1600 h, exhibiting excellent alkaline stability. The single cell test of m-PTP-20Q4 exhibits a maximum power density of 239 mW/cm2 at 80 °C. Hence, the results may guide the selection of polymer monomers to improve performance and alkaline durability for anion exchange membranes.  相似文献   

19.
New anion exchange membranes (AEMs) with high conductivity, good dimensional and alkaline stability are currently required in order to develop alkaline fuel cells into efficient and clean energy conversion devices. In this study, a series of AEMs based on 1, 2-dimethyl-3-(4-vinylbenzyl) imidazolium chloride ([DMVIm][Cl]) are prepared and investigated. [DMVIm][Cl] is synthesized and used as ion carriers and hydrophilic phase in the membranes. The water uptake, swelling ratio, IEC and conductivity of the AEMs increase with increasing the [DMVIm][Cl]. The imidazolium-based AEMs show excellent thermal stability, sufficient mechanical strength, the membrane which containing 30% mass fraction of [DMVIm][Cl] shows conductivity up to 1.0 × 10?2 S cm?1 at room temperature and good long-term alkaline stability in 1 M KOH solution at 80 °C. The results of this study suggest that this type of AEMs have good perspectives for alkaline anion exchange membrane fuel cell applications.  相似文献   

20.
Hypercrosslinked polymer (HCP) holds great potential for utilization as novel anion exchange membrane (AEM) material due to their rich microporous structure and high thermal/chemical stability while remaining challenges due to lack of hydroxide carriers. Herein we report a novel strategy of fabricating poly ionic liquid (PIL)-confined HCP for ion transfer. PIL precursors are loaded into the pores of HCP and in-situ polymerized to prepare PIL@HCP, which is then incorporated into quaternized poly (2,6-dimethyl-1,4-phenylene oxide) (QAPPO) to fabricate composite membrane. The introduction of PIL provides high concentration of quaternary ammonium (QA) groups in the porous networks of HCP. And the organic components impart outstanding compatibility between PIL@HCP and QAPPO matrix. All these permit the formation of interconnected hydroxide transfer channels through the membranes. Especially, the rigid and hydrophobic HCP functions with steric hindrance effectively impedes the attack of hydroxide ions on QA groups and maintains structure stability. Accordingly, the PIL@HCP/QAPPO composite membrane with high ion exchange capacity (IEC) of 2.33 mmol g?1 achieves a hydroxide conductivity of 98 mS cm?1 (80 °C, 100% RH), 92% higher than that of QAPPO. Meanwhile, the area swelling degree of PIL@HCP/QAPPO reduces to 13.6% in comparison to QAPPO (25.7%) and its conductivity retains 88% after alkaline treatment.  相似文献   

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