燃料电池聚合物电解质膜的研究进展

本文根据聚合物电解质膜燃料电池操作温度、使用的电解质和燃料的不同,将其分为高温质子交换膜燃料电池、低温质子换膜燃料电池、直接甲醇燃料电池和阴离子交换膜燃料电池,综述了它们所用电解质膜的最新进展.第一部分简要介绍了这4种燃料电池的优点和不足.第二部分首先介绍了Nafion膜的结构模型,并对平行柱状纳米水通道模型在介观尺度上进行了修正;接着分别对应用于不同燃料电池的改性膜的改性思路作了分析;最后讨论了用于不同燃料电池的新型质子交换膜的研究,同时列举了性能突出的改性膜和新型质子交换膜.第三部分介绍了阴离子交换膜的研究现状.第四部分对未来聚合物电解质膜的研究作了展望.     

聚合物燃料电池离子交换膜新进展

聚合物离子交换膜是聚合物电解质燃料电池的关键部件之一,根据聚合物携带反离子种类,可分为质子交换膜燃料电池（PEMFC）和碱性阴离子交换膜燃料电池（APEFC）。本文着重阐述近年来研究热点：高温低湿质子交换膜（HTPEM）和聚合物碱性阴离子交换膜（APE）的研究进展,指出燃料电池中聚合物离子交换膜（HTPEM和APE）面...     

Advances in the high performance polymer electrolyte membranes for fuel cells

This critical review tersely and concisely reviews the recent development of the polymer electrolyte membranes and the relationship between their properties and affecting factors like operation temperature. In the first section, the advantages and shortcomings of the corresponding polymer electrolyte membrane fuel cells are analyzed. Then, the limitations of Nafion membranes and their alternatives to large-scale commercial applications are discussed. Secondly, the concepts and approaches of the alternative proton exchange membranes for low temperature and high temperature fuel cells are described. The highlights of the current scientific achievements are given for various aspects of approaches. Thirdly, the progress of anion exchange membranes is presented. Finally, the perspectives of future trends on polymer electrolyte membranes for different applications are commented on (400 references).     

Modification and characterization of thin polymer films for electrochemical applications

Proton-conducting polymer membranes are utilized as the solid electrolyte in low temperature polymer electrolyte fuel cells (PEFC), which are efficient energy converters. We have selected the process of radiation grafting and subsequent sulfonation to prepare novel membranes because of its feasibility as a low cost production method. Investigations of the two first preparations steps, i.e., irradiation and grafting, lead to insight concerning the optimization of these two steps and the dependence of the final membrane properties on the various preparation parameters.     

On the use of gamma irradiation crosslinked PVA membranes in hydrogen fuel cells

There is growing interest in the use of fuel cells (FC) with hydrogen as the main fuel for stationary, mobile, and transportation applications. In the FC concept membranes play increasingly important roles. Polymer electrolyte membrane fuel cells (PEMFCs) are considered as the most promising fuel cell technology for a wide range of applications due to the stable operation, the high energy generation yield and the simplicity of the system.In this work, we develop different types of membranes based on poly(vinyl alcohol) (PVA). PVA is a water-soluble polymer that is used in practical applications because of its easy preparation, excellent chemical resistance, thermal and mechanical properties. Crosslinking of the PVA was performed by gamma irradiation since radiation chemistry is found to be a very effective method for constructing three-dimensional polymeric networks. The samples prepared in this way were then immersed in the alkaline solution over a certain period of time to turn them into conductive membranes. Ionic conductivity of the PVA hydrogels, was then measured as a function of concentration of KOH solutions and temperature. Cyclic voltammetry of these PVA hydrogel electrolytes was performed to determine the width of the electrochemical stability window.We examined these membranes impregnated with saturated 6 M KOH electrolyte as polymer membrane for fuel cells application. Our experiments showed that PEMFCs with PVA and Nafion^® membranes had similar polarization curves, under same conditions. Furthermore, PVA membranes proved to be stable during the real cell tests. This study offers a possibility for more earnest approach to the use of PVA membranes for fuel cell applications.     

Anisotropic diffusion of water in perfluorosulfonic acid membrane and hydrocarbon membranes

Polymer electrolyte membranes that are applied for polymer electrolyte fuel cell (PEFC) retain water in their three-dimensional network structure. Diffusion behavior of water in the membranes was analyzed by pulsed field gradient (PFG)-NMR method to estimate diffusion coefficient of proton species as water or hydronium ion. The membrane samples were put in a sample tube vertically or horizontally toward to the field gradient axis under determined temperature and humidity conditions. As the results, anisotropic diffusion behavior of water in the membranes was indicated. Anisotropic properties depended on the sample type, preparation conditions of the wet membranes, and measurement conditions. A perfluorosulfonic acid membrane tended to have smaller anisotropy while hydrocarbon membranes showed greater anisotropy.     

Proton-conducting polymer membranes for direct methanol fuel cells

Three methods to block the methanol transport through proton-conducting polymer membranes while maintaining the proton conductivity unchanged have been conducted; 1) selective layer formation on the surface of the membrane, 2) prearation of nanoclay composite membrane providing tortuous pathway of methanol, 3) control and fixation of the proton transport channels. The methanol permeability through the membranes decreased significantly at the expense of the small decrease in the proton conductivity. It is thus concluded that both the structure and the fixation of the proton transport channels are crucial in optimizinging proton conducting membranes for direct methanol fuel cells.     

Non-Fluorinated Polymer Composite Proton Exchange Membranes for Fuel Cell Applications – A Review

The critical component of a proton exchange membrane fuel cell (PEMFC) system is the proton exchange membrane (PEM). Perfluorosulfonic acid membranes such as Nafion are currently used for PEMFCs in industry, despite suffering from reduced proton conductivity due to dehydration at higher temperatures. However, operating at temperatures below 100 °C leads to cathode flooding, catalyst poisoning by CO, and complex system design with higher cost. Research has concentrated on the membrane material and on preparation methods to achieve high proton conductivity, thermal, mechanical and chemical stability, low fuel crossover and lower cost at high temperatures. Non-fluorinated polymers are a promising alternative. However, improving the efficiency at higher temperatures has necessitated modifications and the inclusion of inorganic materials in a polymer matrix to form a composite membrane can be an approach to reach the target performance, while still reducing costs. This review focuses on recent research in composite PEMs based on non-fluorinated polymers. Various inorganic fillers incorporated in the PEM structure are reviewed in terms of their properties and the effect on PEM fuel cell performance. The most reliable polymers and fillers with potential for high temperature proton exchange membranes (HTPEMs) are also discussed.     

Electrochemical characterization of ionically conductive polymer membranes

Cation conductive membranes, especially highly proton conductive membranes, are of interest not only for chlor-alkali electrolysis but for polymer electrolyte fuel cells as well. The very challenge for electrochemical characterization in this case is the low specific resistance of the polymer required for such applications, which in turn makes resistance measurements a non-trivial problem. We investigate the different possibilities to characterize such membranes. The present part of our work deals with the adequate conditioning and equilibration of membranes designed especially for direct methanol fuel cell applications, with the measurement of the conductivity and with the determination of apparent transport numbers in the membrane. The usefulness of the respective leaching investigations, impedance spectroscopy measurements and concentration potential measurements for the case of membranes made from sulfonated poly(phenylene oxide) is discussed.     

Direct chemical deposition of platinum on ionic conductive membranes and evaluation of the electrocatalytic activity

Direct chemical deposition of platinum at different polymer electrolyte membranes for a fuel cell application was studied. The developed method allows depositing platinum on acid and alkaline membranes. The depositions realized under different experimental conditions were characterized by RBS (Rutherford backscattering spectroscopy) and TEM (transmission electron microscopy) to determine the depth profile in the membranes and the mean size of platinum particles. The active surface area of the catalysts and the related particle size were characterized by cyclic voltammetry. Results indicated that a part of platinum was deposited inside the membrane. Roughness as high as 500 could however be achieved. Oxygen reduction reaction under working conditions close to those of a fuel cell cathode was studied to draw some kinetic data.     

燃料电池聚合物电解质膜

本文简要介绍了聚电解质膜燃料电池的定义、分类、工作原理及其特点,综述了国内外在燃料电池聚电解质领域的最新成果。对质子传导率与甲醇渗透系数的关系进行了初步探讨,详细评述了近年来AAPEM和ACPEM这两类聚电解质膜的研究进展,并对今后的研究趋势作了展望。     

Tuned polymer electrolyte membranes based on aromatic polyethers for fuel cell applications

Poly(arylene ether sulfone)-based ionomers containing sulfofluorenyl groups have been synthesized for applications to polymer electrolyte membrane fuel cells (PEMFCs). In order to achieve high proton conductivity and chemical, mechanical, and dimensional stability, the molecular structure of the ionomers has been optimized. Tough, flexible, and transparent membranes were obtained from a series of modified ionomers containing methyl groups with the ion-exchange capacity (IEC) ranging from 1.32 to 3.26 meq/g. Isopropylidene tetramethylbiphenylene moieties were more effective than the methyl-substituted fluorenyl groups in giving a high-IEC ionomer membrane with substantial stability to hydrolysis and oxidation. Dimensional stability was significantly improved for the methyl-substituted ionomer membranes compared to that of the non-methylated ones. This new ionomer membrane showed comparable proton conductivity to that of the perfluorinated ionomer membrane (Nafion 112) under a wide range of conditions (80-120 degrees C and 20-93% relative humidity (RH)). The highest proton conductivity of 0.3 S/cm was obtained at 80 degrees C and 93% RH. Although there is a decline of proton conductivity with time, after 10 000 h the proton conductivities were still at acceptable levels for fuel cell operation. The membranes retained their strength, flexibility, and high molecular weight after 10 000 h. Microscopic analyses revealed well-connected ionic clusters for the high-IEC membrane. A fuel cell operated using the polyether ionomer membrane showed better performance than that of Nafion at a low humidity of 20% RH and high temperature of 90 degrees C. Unlike the other hydrocarbon ionomers, the present membrane showed a lower resistance than expected from its conductivity, indicating superior water-holding capability at high temperature and low humidity.     

BLEND MEMBRANES FOR DIRECT METHANOL AND PROTON EXCHANGE MEMBRANE FUEL CELLS

Sulphonated polystyrene ethylene butylene polystyrene(SPSEBS)prepared with 35%sulphonation was found to be highly elastic and enlarged up to 300%-400%of its initial length.It absorbed over 110%of water by weight.A major drawback of this membrane is its poor mechanical properties which are not adequate for use as polymer electrolytes in fuel cells.To overcome this,SPSEBS was blended with poly(vinylidene fluoride)(PVDF),a hydrophobic polymer.The blend membranes showed better mechanical properties than the base polymer.The effect of PVDF content on water uptake,ion exchange capacity and proton conductivity of the blend membranes was investigated.This paper presents the results of recent studies applied to develop an optimized in-house membrane electrode assembly(MEA)preparation technique combining catalyst ink spraying and assembly hot pressing.Easy steps were chosen in this preparation technique in order to simplify the method,aiming at cost reduction.The open circuit voltage for the cell with SPSEBS is 0.980 V which is higher compared to that of the cell with Nafion 117(0.790 V).From this study,it is concluded that a polymer electrolyte membrane suitable for proton exchange membrane fuel cell(PEMFC)and direct methanol fuel cell(DMFC)application can be obtained by blending SPSEBS and PVDF in appropriate proportions.The methanol permeability and selectivity showed a strong influence on DMFC performance.     

Preparation of polymer electrolyte membranes based on poly(phenylene oxide) with different side chain lengths of phosphonic acid

A series of poly(phenylene oxide) (PPO) polymers bearing phosphonic acid groups on the methyl group and on the phenyl ring are synthesized as membrane materials for fuel cell applications. These phosphonic acid‐based PPO membranes exhibited high chemical resistance, dimensional stability, and good proton conductivity even under low humidity condition. Among the membranes, the one in which the phosphonic acid moiety is attached to the polymer main chain with ? CO(CH₂)₅? shows highest proton conductivity under overall conditions even though it has the lowest water uptake and IEC value. A well‐defined separation of the hydrophilic and hydrophobic phases suggests the phosphonic acid groups to form proton conduction channels via interchain hydrogen bonding. A high storage modulus of the membranes in various temperature ranges indicates that the membranes are suitable for use under a high temperature and low humidity conditions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019     

Aspects of fatigue failure mechanisms in polymer fuel cell membranes

The swelling‐driven fatigue behavior of polymer fuel cell membranes during relative humidity (RH) cycling is investigated. In particular, swelling‐induced membrane stresses are obtained from a numerical model simulating fuel cell RH cycle tests, and compared to the lifetimes obtained experimentally from tests conducted in the absence of electrochemical effects. A strong correlation between the lifetimes of the membranes in the actual tests and model results is obtained. In general, higher RH (or swelling) amplitude results in larger stress amplitudes and shorter lifetime, that is, fewer cycles to failure. Tensile stresses are needed for forming local cavities in the membrane, which may eventually lead to craze formation. Cavitation is less likely to occur in compressed membrane at high humidities. The stress–lifetime plots for polymer fuel cell membranes exhibit similar features to those observed for other polymers. The crazing criterion for polymers suggests that craze initiation during RH cycling is more likely to occur in the low compression regions, such as under the channels, which is in agreement with experimental observations. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1506–1517, 2011     

Synthesis and characterization of high molecular weight hexafluoroisopropylidene‐containing polybenzimidazole for high‐temperature polymer electrolyte membrane fuel cells

A high molecular weight, thermally and chemical stable hexafluoroisopropylidene containing polybenzimidazole (6F‐PBI) was synthesized from 3,3′‐diaminobenzidine (TAB) and 2,2‐bis(4‐carboxyphenyl) hexafluoropropane (6F‐diacid) using polyphosphoric acid (PPA) as both the polycondensation agent and the polymerization solvent. Investigation of polymerization conditions to achieve high molecular weight polymers was explored via stepwise temperature control, monomer concentration in PPA, and final polymerization temperature. The polymer characterization included inherent viscosity (I.V.) measurement and GPC as a determination of polymer molecular weight, thermal and chemical stability assessment via thermo gravimetric analysis and Fenton test, respectively. The resulting high molecular weight polymer showed excellent thermal and chemical stability. Phosphoric acid doped 6F‐PBI membranes were prepared using the PPA process. The physiochemical properties of phosphoric acid doped membranes were characterized by measuring the phosphoric acid doping level, mechanical properties, and proton conductivity. These membranes showed higher phosphoric acid doping levels and higher proton conductivities than the membranes prepared by the conventional membrane fabrication processes. These membranes had sufficient mechanical properties to be easily fabricated into membrane electrode assemblies (MEA) and the prepared MEAs were tested in single cell fuel cells under various conditions, with a focus on the high temperature performance and fuel impurity tolerance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4064–4073, 2009     

Selective Control of Cell Activity with Hydrophilic Polymer‐Covered Cationic Nanoparticles

Cationic polymers exhibit high cytotoxicity via strong interaction with cell membranes. To reduce cell membrane damage, a hydrophilic polymer is introduced to the cationic nanoparticle surface. The hydrophilic polymer coating of cationic nanoparticles resulted in a nearly neutral nanoparticle. These particles are applied to mouse fibroblast (3T3) and human cervical adenocarcinoma (Hela) cells. Interestingly, nanoparticles with a long cationic segment decrease cell activity regardless of cell type, while those with a short segment only affect 3T3 cell activity at lower concentrations less than 500 µg mL^?1. Most nanoparticles are located inside 3T3 cells but on the cell membrane of Hela cells. The short cationic nanoparticle shows negligible cell membrane damage despite its high accumulation on Hela cell membranes. Cell activity changed by hydrophilic polymer‐coated cationic nanoparticles is caused by incorporated nanoparticle accumulation in the cells, not cell membrane damage. To suppress the cytotoxicity from the cationic polymer, cationic nanoparticle needs to completely cover with hydrophilic polymer so as not to exhibit the cationic effect and applies to cell with low concentrations to reduce the nonselective cytotoxicity from the cationic polymer.     

碱性固体燃料电池碱性聚合物电解质膜的最新研究进展

最近,碱性聚合物电解质膜燃料电池(APEMFC)因具有电极反应动力学快以及不依赖于贵金属铂催化剂等诸多优点而成为一个热门话题.作为其中一个关键部件,碱性聚合物电解质膜直接影响燃料电池的性能和成本.然而,迄今为止,仍然没有令人满意的碱性电解质膜材料.为此,大量研究被开展和报道.本文综述了近三年内文献中关于燃料电池碱性聚合物电解质膜的最新研究进展:包括各种各样的合成策略,构效关系,水管理以及非原位或原位稳定性测试等等.尤其是一些新的金属离子基阴离子交换膜和冠醚基阴离子交换膜首次被提及和评论.此外,还进一步预测了将来的发展趋势.     

碱性固体燃料电池碱性聚合物电解质膜的最新研究进展

最近,碱性聚合物电解质膜燃料电池（APEMFC）因具有电极反应动力学快以及不依赖于贵金属铂催化剂等诸多优点而成为一个热门话题. 作为其中一个关键部件,碱性聚合物电解质膜直接影响燃料电池的性能和成本.然而,迄今为止,仍然没有令人满意的碱性电解质膜材料. 为此,大量研究被开展和报道. 本文综述了近三年内文献中关于燃料电池碱性聚合物电解质膜的最新研究进展：包括各种各样的合成策略,构效关系,水管理以及非原位或原位稳定性测试等等. 尤其是一些新的金属离子基阴离子交换膜和冠醚基阴离子交换膜首次被提及和评论.此外,还进一步预测了将来的发展趋势.     

碱性固体燃料电池碱性聚合物电解质膜的最新研究进展

最近,碱性聚合物电解质膜燃料电池（APEMFC）因具有电极反应动力学快以及不依赖于贵金属铂催化剂等诸多优点而成为一个热门话题. 作为其中一个关键部件,碱性聚合物电解质膜直接影响燃料电池的性能和成本.然而,迄今为止,仍然没有令人满意的碱性电解质膜材料. 为此,大量研究被开展和报道. 本文综述了近三年内文献中关于燃料电池碱性聚合物电解质膜的最新研究进展：包括各种各样的合成策略,构效关系,水管理以及非原位或原位稳定性测试等等. 尤其是一些新的金属离子基阴离子交换膜和冠醚基阴离子交换膜首次被提及和评论.此外,还进一步预测了将来的发展趋势.