季铵盐阴离子交换膜研究进展

近年来,阴离子交换膜燃料电池的发展受到了广泛关注。开发具有碱稳定性能优异,电导率高的阴离子交换膜(AEMs)材料成为了研究的热点。AEMs主要由聚合物骨架和阳离子基团组成,这两者是影响膜碱稳定性和电导率的重要因素。本文综述了季铵盐类阴离子交换膜聚合物骨架结构中含有醚氧键和不含醚氧键的烷基季铵盐AEMs、N-螺环季铵盐AEMs和环季铵盐AEMs的碱稳定性、电导率等性能;总结了不同骨架结构季铵盐AEMs碱稳定性的差异;分析了季铵盐的降解机理。同时对于含有季铵盐阳离子交换基团的AEMs的结构设计进行了分析和展望。     

碱性阴离子交换聚合物膜研究进展

碱性燃料电池(AFCs)是一种直接将化学能转化为电能的发电装置,因其高效、环保等优点,得到了科学界与工业界的广泛关注。阴离子交换聚合物膜作为碱性阴离子交换膜燃料电池的核心组成部分,要求其具备优异的电导率、良好的化学稳定性及力学强度。本文主要从聚合物主链及阳离子官能团的结构与性能之间的关系及调控方式方面,综述了碱性阴离子交换膜的研究进展。     

阴离子交换膜的离子电导率和稳定性影响因素及其研究进展

从阴离子交换膜直接甲醇燃料电池(AEM-DMFC)的工作原理以及AEM的分子结构与AEM多级导电机理角度出发,阐述了影响AEM离子电导率和稳定性主要因素。综述了近年来通过设计AEM主链和侧链分子结构调控AEM性能,以及设计多相复合AEM体系来获得兼具优异电导率和稳定性的AEM的研究进展。     

后官能化工艺制备侧链离子结构的部分氟化阴离子交换膜

以十氟联苯、双酚A低温聚合制备可高温官能化的聚合物主链,以3,5-二甲基苯酚为功能侧链,采用后官能化工艺制备了系列不同离子交换容量(IEC)值的含侧链苄基季铵基团的部分氟化阴离子交换膜.用GPC、1H-NMR、19F-NMR、IR、SASX等表征了膜的分子结构及聚集态结构,并且测试了膜的各种性能.结果表明,该系列部分氟化阴离子交换膜的分子主链线性好,官能度可控,具有明显的微相分离结构.部分氟化结构和微相分离的侧链离子结构极大的改善了膜的吸水溶胀性、电导率和化学稳定性.QFPAE-95膜具有最高的氢氧根离子电导率和适度吸水溶胀性,80oC时离子电导率和溶胀比分别达到108.6 m S cm-1和42.6%.QFPAE-55具有最大的拉伸强度,达到21.01 MPa.该系列膜还具有出色的碱稳定性,QFPAE-55膜在1 mol/L Na OH溶液中于60oC下浸泡20天后,其电导率和IEC值分别保持为原膜的82.3%和84.2%,有望作为新型阴离子交换膜并应用于碱性膜燃料电池.     

季铵化聚砜/层状双金属氢氧化物阴离子交换膜的制备与表征

共沉淀法制备的层状双金属氢氧化物(LDH)分散于氯甲基化聚砜的溶液,经流延法制备了有机-无机杂化膜.通过季铵化、碱性化处理,杂化膜被转变为阴离子交换膜(AEM).使用X-射线衍射对LDH和AEM样品的结构进行了表征,同时用扫描电镜对AEM样品形貌进行了直接观察,测试了AEM的吸水率、溶胀率、机械性能和离子传导率等.结果表明,LDH含量为5%的AEM具有最佳的综合性能,95℃的离子传导率为3.81×10-2S/cm.     

1,4-双(二苯基膦)丁烷交联的季膦化聚芳醚酮阴离子交换膜

以1,4-双(二苯基膦)丁烷为交联剂,以具有四甲基联苯结构的聚芳醚酮为基体材料,分别制备了刚性三苯基膦和柔性三丁基膦修饰的阴离子交联膜材料.交联剂在交联结构形成的过程中转变成季膦盐,在提高膜材料机械稳定性的同时保持离子交换功能基团的含量.研究了2种阴离子交换膜的尺寸稳定性、电导率、机械性能及耐碱稳定性等.研究结果表明,当交联度为20%时,三苯基膦与三丁基膦修饰的阴离子交换膜的拉伸强度分别由未交联时的27和18 MPa提高到45和30 MPa;交联的膜材料在60℃的3 mol/L KOH溶液中浸泡120 h后,三苯基膦修饰的阴离子交换膜的电导率保留率为81%,三丁基膦修饰的阴离子交换膜的电导率保留率为69%,膜的耐碱稳定性均较未交联时有明显提高.交联度相同时,三苯基膦修饰的阴离子交换膜表现出更高的拉伸强度和更好的耐碱稳定性.     

用于碱性膜燃料电池的新型聚苯醚阴离子交换膜的制备与性能

以2,6-二甲基聚苯醚(PPO)为原料, 经溴代及N-甲基咪唑季铵化反应, 制备了N-甲基咪唑季铵化PPO, 并进行了红外光谱(FTIR)和氢核磁共振波谱(¹H NMR)表征.所得季铵化产物与聚乙烯醇(PVA)按不同比例共混后用戊二醛交联成膜, 在碱性液中浸泡转化为OH^-型, 得到一系列阴离子交换膜.通过扫描电子显微镜(SEM) 、交流阻抗(AC)、拉伸实验和热重分析(TGA)等手段考察了膜的微观形貌及电导率、力学性能、热稳定性及耐碱性等性能.结果表明, 膜的外观形貌平整均一; 含水率为50.4%~151.2%; 溶胀度为79.2%~164.2%; 离子交换容量为0.47~1.52 mmol/g; 90℃时, M4膜的电导率高达49.1 mS/cm; 断裂伸长率达到128%, 极大改善了PPO膜应力易裂的状况.同时, N-甲基咪唑鎓基团分解温度达到170℃, 高于常用的阴离子交换膜中的季铵基团(120℃).在2 mol/L的NaOH溶液中浸泡192 h后, 电导率仅下降19%, 具备良好的耐碱性能力.     

燃料电池用阴离子交换膜的研究进展

阴离子交换膜燃料电池(AEMFC)是一种高效环保的发电技术,因为其具有电池效率高、可以使用非贵金属(锌、镍)做为催化剂、优异的催化剂稳定性和灵活的燃料选择性等优点,而被视作新一代的能源动力系统。阴离子交换膜(AEM)是AEMFC电池结构中的重要组成部分,在其中起到隔绝燃料与氧化剂、传导氢氧根离子、支撑催化剂等作用。但是目前商业化的阴离子交换膜因为其离子导电率低、化学稳定性差而不适合于AEMFC方面的应用。因此,开发适于在AEMFC中使用的阴离子交换膜成为研究的热点。本文介绍了用于燃料电池的阴离子交换膜性能要求和功能化方法,同时还综述了近年来开发用于燃料电池应用的阴离子交换膜的研究进展。     

化学交联聚乙烯醇改性纤维素碱性阴离子交换复合膜的制备与性能

高稳定性碱性阴离子交换膜的制备已成为碱性固体电解质膜研究领域的一大热点.本文通过聚乙烯醇化学交联改性制备出了季铵化羟乙基乙氧基纤维素碱性阴离子交换膜（PVA/QHECE）.采用傅里叶变换红外（FTIR）光谱、热重（TG）分析、交流（AC）阻抗等方法考察了复合膜的分子结构、热稳定性、耐碱稳定性及离子电导率等性能.详尽考察了交联时间、交联剂含量、聚合物组成对成膜力学强度、含水率以及OH^-电导率的影响.实验结果表明:随着交联时间的增加,膜的溶胀率降低,力学强度随之增强,而离子电导率随膜含水率的降低没有发生明显变化,室温下OH^-的电导率在3.26×10^-4-4.44×10^-4S·cm^-1范围内变化.热重分析结果显示:掺入42.9%的QHECE时,膜的热分解温度达260℃.此外,将PVA/QHECE膜在6 mol·L^-4 KOH浓碱溶液中80℃浸渍处理168 h,膜的电导率从4.90×10^-4S·cm^-1提高到9.68×10^-4S·cm^-1,而膜的外观和力学强度以及含水率未发生明显变化,这一结果表明该膜具有很好的耐碱化学稳定性,有望作为一种新型的碱性燃料电池用离子交换膜.     

两性质子交换膜的研究进展

两性质子交换膜是一种含有酸、碱结构并具有质子传导功能的聚合物薄膜材料。由于其结构可设计性强,分子链特殊的相互作用使之在导电的同时对甲醇或钒离子等具有优异的阻隔性能,近年来引起了广泛的关注。本文对国内外相关的研究结果进行了评述,并对两性质子交换膜进行了定义,根据化学结构和制备方法将其分为三大类:(1)碱性聚合物与高沸点酸掺杂型;(2)酸、碱聚合物共混型;(3)含有酸碱结构的聚合物本征型,对其在质子交换膜燃料电池和全钒液流电池中的应用性能进行了讨论。     

Highly Conductive Anion‐Exchange Membranes from Microporous Tröger's Base Polymers

The development of polymeric anion‐exchange membranes (AEMs) combining high ion conductivity and long‐term stability is a major challenge for materials chemistry. AEMs with regularly distributed fixed cationic groups, based on the formation of microporous polymers containing the V‐shape rigid Tröger's base units, are reported for the first time. Despite their simple preparation, which involves only two synthetic steps using commercially available precursors, the polymers provide AEMs with exceptional hydroxide conductivity at relatively low ion‐exchange capacity, as well as a high swelling resistance and chemical stability. An unprecedented hydroxide conductivity of 164.4 mS cm^?1 is obtained at a relatively a low ion‐exchange capacity of 0.82 mmol g^?1 under optimal operating conditions. The exceptional anion conductivity appears related to the intrinsic microporosity of the charged polymer matrix, which facilitates rapid anion transport.     

Cationic Metallo‐Polyelectrolytes for Robust Alkaline Anion‐Exchange Membranes

Chemically inert, mechanically tough, cationic metallo‐polyelectrolytes were conceptualized and designed as durable anion‐exchange membranes (AEMs). Ring‐opening metathesis polymerization (ROMP) of cobaltocenium‐containing cyclooctene with triazole as the only linker group, followed by backbone hydrogenation, led to a new class of AEMs with a polyethylene‐like framework and alkaline‐stable cobaltocenium cation for ion transport. These AEMs exhibited excellent thermal, chemical and mechanical stability, as well as high ion conductivity.     

Direct Insertion Polymerization of Ionic Monomers: Rapid Production of Anion Exchange Membranes

The limited number of methods to directly polymerize ionic monomers currently hinders rapid diversification and production of ionic polymeric materials, namely anion exchange membranes (AEMs) which are essential components in emerging alkaline fuel cell and electrolyzer technologies. Herein, we report a direct coordination-insertion polymerization of cationic monomers, providing the first direct synthesis of aliphatic polymers with high ion incorporations and allowing facile access to a broad range of materials. We demonstrate the utility of this method by rapidly generating a library of solution processable ionic polymers for use as AEMs. We investigate these materials to study the influence of cation identity on hydroxide conductivity and stability. We found that AEMs with piperidinium cations exhibited the highest performance, with high alkaline stability, hydroxide conductivity of 87 mS cm⁻¹ at 80 °C, and a peak power density of 730 mW cm⁻² when integrated into a fuel cell device.     

复合型季铵化聚醚砜碱性聚合物电解质膜的制备及性能

利用4,4?-二氟二苯砜(DFDPS)、9,9?-双(4-羟苯基)芴(BHPF)、2,2?-二(4-羟基苯基)丙烷(双酚A)及4,4?-(六氟异丙叉)双酚(双酚AF)为原料,制备了2类具有不同主链刚性的聚醚砜材料.以聚醚砜及其氯甲基化产物按一定质量比采用溶液浇铸法,制备了2类新型共混阴离子交换膜,并避免了成膜过程中的相分离现象.在高分子主链上通过引入双酚芴(BQPAES系列)及双酚A(BQPES系列)结构调整主链的刚性,探讨了主链刚性对性能的影响;表征了共混膜的离子交换容量(IEC)、吸水及溶胀特性与离子电导率,并考察了它们的耐水解和耐碱稳定性.结果表明:2种聚合物相容性良好,共混膜质地均一,柔韧透明,吸水率和溶胀率适中,均随着温度的升高逐渐增加、随着聚醚砜含量增加逐渐减小;在90?C时,离子电导率最高达到89 m S/cm.经过沸水处理24 h后,均保持高机械强度,失重率低于5%;经2 mol/L的Na OH溶液30?C处理168~240 h后离子电导率仍可保持65%~80%.由于含双酚芴结构的高分子主链具有更高的刚性,在类似IEC条件下,BQPAES膜显示了比BQPES膜更好的尺寸稳定性和化学稳定性,同时维持了较高的电导率水平.由此表明,复合处理及适度提高高分子主链的刚性,有利于提高膜的性能.     

Chloromethylation and Quaternization of Poly(aryl ether ketone sulfone)s with Clustered Electron-rich Phenyl Groups for Anion Exchange Membranes

Ion segregation is critically important for achieving high ion conductivity for anion exchange membranes(AEMs).Herein,a new bisphenol monomer bearing ten electron-rich phenyl groups was designed and polymerized with various amounts of electron-deficient 4,4′-dihydroxydiphenylsulfone and 4,4′-difluorobenzophenone to yield dense and selective reaction sites for chloromethylation and quaternization.As the most challenging step,chloromethylation was optimized by tuning the reaction temperature,reaction time,and reactant ratios.Ion exchange capacity,water uptake,anion conductivity,mechanical stability,and alkaline stability of the resulting AEMs were characterized in detail.It is found that chloromethylation reaction needed to be carried out at low equivalent of chloromethylation agents to avoid undesirable crosslinking.The QA-PAEKS-20 sample with an IEC of 1.19 mmol·g^-1 exhibited a Cl^–conductivity of 11.2 mS·cm^-1 and a water uptake of 30.2%at80°C,which are promising for AEM applications.     

Benzimidazolium functionalized polysulfone-based anion exchange membranes with improved alkaline stability

The stability of anion exchange membranes(AEMs) is an important feature of alkaline exchange membrane fuel cells(AEMFCs), which has been extensively studied. However it remains a real challenge due to the harsh working condition. Herein, we developed a novel type of polysulfone-based AEMs with three modified 1,2-dimethylbenzimidazoliums containing different substitutes at C4-and C7-position. The results showed that the introduction of the substitutes could obviously improve the dimensional and alkaline stabilities of the corresponding membranes. The swelling ratios of resultant AEMs were all lower than 10% after water immersion. The membrane with 4,7-dimethoxy-1,2-dimethylbenzimidazolium group exhibited the highest alkaline stability. Only 9.2% loss of hydroxide conductivity was observed after treating the membrane in 1 mol·L~(-1) KOH solution at 80 °C for 336 h. Furthermore, the density functional theory(DFT) study on the three functional group models showed that the substitutes at C4-and C7-position affected the lowest unoccupied molecular orbital(LUMO) energies of the different 1,2-dimethylbenzimidazolium groups.     

Elastic and durable multi-cation-crosslinked anion exchange membrane based on poly(styrene-b-(ethylene-co-butylene)-b-styrene)

Anion exchange membranes (AEMs), as the core component of the new generation anion exchange membrane fuel cells (AEMFCs), directly determine the performance and the lifetime of this energy conversion device. Here, AEMs with pendant multiple quaternary ammonium anchored onto the poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) backbone are synthesized. The comb-shaped copolymer SEBS-C16 is synthesized with N,N-dimethyl-1-hexadecylamine and chloromethylated SEBS to improve solubility, then the multi-cation crosslinker is prepared and grafted on the above backbone to fabricate a series of flexible multi-cation crosslinked SEBS-based AEMs (SEBS-C16-xC4, where x% is the ratio of the crosslinker to polystyrene block) with practical properties. The obtained SEBS-C16-20C4 membrane exhibits a microphase separated morphology with an interdomain spacing of 18.87 nm. Benefited from the ion channels, SEBS-C16-20C4 shows high conductivity of 77.78 mS/cm at 80°C. Additionally, the prepared SEBS-C16-20C4 membrane with ion exchange capacity of 2.35 mmol/g also exhibits enhanced alkaline stability (5.87% hydroxide conductivity decrease in 2 M NaOH solution at 80°C after 1,700 hr) and improved mechanical properties, compared with the non-crosslinked SEBS-C16 sample. Furthermore, AEMFC single cell performance is evaluated with the SEBS-C16-20C4 membrane, and a maximum power density of 182 mW/cm² is achieved at 80°C under H₂/O₂ conditions.     

Durable Multiblock Poly(biphenyl alkylene) Anion Exchange Membranes with Microphase Separation for Hydrogen Energy Conversion

Anion exchange membrane fuel cells (AEMFCs) and water electrolysis (AEMWE) show great application potential in the field of hydrogen energy conversion technology. However, scalable anion exchange membranes (AEMs) with desirable properties are still lacking, which greatly hampers the commercialization of this technology. Herein, we propose a series of novel multiblock AEMs based on ether-free poly(biphenyl ammonium-b-biphenyl phenyl)s (PBPA-b-BPPs) that are suitable for use in high performance AEMFC and AEMWE systems because of their well-formed microphase separation structures. The developed AEMs achieved outstanding OH⁻ conductivity (162.2 mS cm⁻¹ at 80 °C) with a low swelling ratio, good alkaline stability, and excellent mechanical durability (tensile strength >31 MPa and elongation at break >147 % after treatment in 2 M NaOH at 80 °C for 3750 h). A PBPA-b-BPP-based AEMFC demonstrated a remarkable peak power density of 2.41 W cm⁻² and in situ durability for 330 h under 0.6 A cm⁻² at 70 °C. An AEMWE device showed a promising performance (6.25 A cm⁻² at 2 V, 80 °C) and outstanding in situ durability for 3250 h with a low voltage decay rate (<28 μV h⁻¹). The newly developed PBPA-b-BPP AEMs thus show great application prospects for energy conversion devices.     

Improving the conductivity and dimensional stability of anion exchange membranes by grafting of quaternized dendrons

High conductivity is critical for the practical applications of anion exchange membranes (AEMs) in fuel cells. In this study, a new strategy for enhanced conductivity and dimensional stability of AEMs by incorporating quaternized dendrons is proposed. Thanks to the introduced quaternized dendrons, distinct nanoscale phase separation and well-connected ion conductive channels are formed in the as-prepared membranes (PPO-QG-x). As a result, PPO-QG-x AEMs achieve high hydroxide conductivities up to 65.5 mS cm⁻¹ at 20 °C and 121.5 mS cm⁻¹ at 80 °C (IEC = 1.95 mmol g⁻¹), while possessing good dimensional stability. Meanwhile, PPO-QG-x AEMs show good alkaline stability with the maximum loss in conductivity of 15.1% after treated in 2 M NaOH at 80 °C for 960 h. In addition, the single-cell assembled with PPO-QG-12 membrane exhibit a peak power density of 249.4 mW cm⁻² at 60 °C. Overall, this work provides a new insight to achieve high conductivity of AEMs.