Characterization and evaluation of commercial poly (vinylidene fluoride)‐g‐sulfonatedPolystyrene as proton exchange membrane

The possibility of developing low‐cost commercial grafted and sulfonated Poly(vinylidene fluoride) (PVDF‐g‐PSSA) membranes as proton exchange membranes for fuel cell applications have been investigated. PVDF‐g‐PSSA membranes were systematically prepared and examined with the focus of understanding how the polymer microstructure (degree of grafting and sulfonation, ion‐exchange capacity, etc) affects their methanol permeability, water uptake, and proton conductivity. Fourier transform infrared spectroscopy was used to characterize the changes of the membrane's microstructure after grafting and sulfonation. The results showed that the PVDF‐g‐PSSA membranes exhibited good thermal stability and lower methanol permeability. The proton conductivity of PVDF‐g‐PSSA membranes was also measured by the electrochemical impedance spectroscopy method. It was found that the proton conductivity of PVDF‐g‐PSSA membranes depends on the degree of sulfonation. All the sulfonated membranes show high proton conductivity at 92°C, in the range of 27 to 235 mScm⁻¹, which is much higher than that of Nafion212 (102 mScm⁻¹ at 80°C). The results indicated that the PVDF‐g‐PSSA membranes are particularly promising membranes to be used as polymer electrolyte membranes due to their excellent stability, low methanol permeability, and high proton conductivity.     

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).     

Proton transport in radiation-grafted membranes for fuel cells as detected by SECM

Scanning electrochemical microscopy (SECM) has been applied to investigate counter ion transport through four different proton conducting membranes with poly(styrene sulfonic acid) side chains. These membranes, intended for the polymer electrolyte fuel cell, are based on PVDF and PVDF-co-HFP matrix materials and have been prepared by an irradiation grafting method. SECM is found to be suitable for mapping variations in proton diffusion coefficient and concentration in these inhomogeneous membranes. It was found that the variations in these parameters are most considerable in a membrane with a high degree of grafting. Ionic conductivities measured with impedance spectroscopy were in agreement with calculated values obtained on the basis of the SECM measurements.     

Preparation of poly(ether ether ketone)-based polymer electrolytes for fuel cell membranes using grafting technique

Poly(ether ether ketone) (PEEK)-based polymer electrolyte membranes (PEMs) was successfully prepared by radiation grafting of a styrene monomer into PEEK films and the consequent selective sulfonation of the grafting chains in the film state. Using milder sulfonation, the sulfonation reactions proceeded at the grafted chains in preference to the phenylene rings of PEEK main chains; as a result, the grafted films could successfully transform to a PEM with conductivity of more than 0.1 S/cm. The ion exchange capacity (IEC) and conductivity of the grafted PEEK electrolyte membranes were controlled to the ranges of 1.2–2.9 mmol/g and 0.03–0.18 S/cm by changing the grafting degree. It should be noted that this is the first example of directly transforming super-engineering plastic films into a PEM using radiation grafting.     

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。     

Influence of grafting solvents on the properties of polymer electrolyte membranes prepared by γ-ray preirradiation method

The effect of grafting solvents, such as isopropanol (iPrOH), tetrachloroethane (TCE), tetrahydrofuran (THF), and toluene, on the preparation of poly(ethylene-co-tetrafluoroethylene)-graft-poly(styrene sulfonic acid) (ETFE-g-PSSA) electrolyte membranes by the γ-ray preirradiation grafting method was investigated. It was found that the iPrOH can drastically accelerate the grafting, resulting in a higher degree of grafting. However, for an appropriate degree of grafting of about 50%, the sulfonic acid groups in the ETFE-g-PSSA membrane prepared with the iPrOH were mainly distributed near the membrane surface, as shown by low proton conductivity in the membrane thickness direction. In contrast to this result, the ETFE-g-PSSA membranes prepared with the THF, toluene and TCE exhibited uniform distribution of the sulfonic acid groups in the membrane. Especially, in the case of the TCE grafting solvent, the chemical stability of the resultant electrolyte membrane was clearly higher than those prepared with the other grafting solvents.     

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.     

New hybrid membranes based on phosphonic acid functionalized silica particles for PEMFC

This work concerns the development of hybrid organic/inorganic membranes from styrenic phosphonic polymers. The phosphonic charge, composed phosphonic polymers grafted onto silica nanoparticles, was obtained by “grafting onto” method. It consists of synthesizing first the polymer, and then the terminal functions of the latter react with silanol groups of silica. The phosphonated polymer was isolated in two steps, that is, an ATRP polymerization of 4‐chloromethylstyrene followed by Mickaelïs‐Arbusov reaction. After the grafting onto silica, membranes are prepared through formulation containing the charge and the polymer matrix PVDF‐HFP, which are dispersed in DMF. The acid form is obtained by hydrolysis in chlorydric acid. The membrane possessing a 40 wt % charge ratio (IEC = 1.08 meq g^?1) was selected as reference. A proton conductivity of 65 mS cm^?1 at 80 °C was measured in immersed conditions. When the membrane is no more immersed, the value decreases drastically (0.21 mS cm^?1 at 120 °C and 25% RH). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

High ionic conductive PVDF-based fibrous electrolytes

The high ionic conductive polymer electrolytes were prepared based on poly(vinylidenefluoride) (PVDF) fibers modified via preirradiation grafting poly(methyl methacrylate) (PMMA). In these polymer electrolytes, the PVDF fibers served as the supporting phase providing dimensional stability, and PMMA acted as the gel phase helping for the trapping liquid electrolyte and substituting the nonconductive PVDF phase to provide contact with electrodes well thus increasing conductive area. The modified PVDF fibrous membranes were used as a polymer electrolyte in lithium ion battery after they were activated by uptaking 1 M LiPF₆/ethylene carbonate–dimethyl carbonate (1:1 vol) liquid electrolyte, which showed a much higher room-temperature ionic conductivity than the pristine PVDF fibrous membrane. The LiCoO₂-mesocarbon microbead coin cells containing the dual-phase fibrous membrane (degree of graft, 111.8%) demonstrated excellent rate performance, and the cell still retained about 86% of discharge capacity at 4C rate, as compared to that at 0.1C rate. The prototype cell showed good cycle performance.     

Utilisation d'electrolyte solide polymere dans les piles a combustibles alcalines

The use of a solid polymer electrolyte in alkaline fuel cells. The objective of this research was to develop a new type of cheap anion exchange membranes for use in alkaline fuel cells. The polyelectrolyte anion exchange membrane was prepared by grafting quaternary amines (DABCO, TEA) on the epichlorhydrine polymer, consolidated by reticulation. Obtained ionic conductivities are over 10⁻² S.cm⁻¹, with a concentration of positive ionic sites of a few milli-equivalents per gram of material. Measured anionic transport numbers are greater than 0.90. Membranes, which can absorb 30 to 50% of water, are quasi impervious to gases such as H₂ and 0₂ and can operate at temperatures up to 120°C. Alkaline fuel cells assembled with both types of membranes showed good performances. Particular attention was devoted to the membrane-electrode interface.     

Poly(vinylidene fluoride-hexafluoropropylene)-based membranes for lithium batteries

Poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) copolymer membranes were prepared by a phase inversion technique with poly(ethylene glycol) as an additive and tetrahydrofuran or acetone or dimethylformamide as solvent. The morphology, ionic conductivity and uptake of electrolyte solution by the polymer membranes were studied. The amount of intake of electrolyte solution by the polymer membranes increases with the increase of PEG content. The morphology and ionic conductivity of the polymer membranes (PM) are correlated with the physical properties of the solvents used in the phase inversion process. The cycling behavior of the membrane was examined with Li/LiCoO₂ cells.     

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.     

Alkaline Zn-air and Al-air cells based on novel solid PVA/PAA polymer electrolyte membranes

High ionic conducting solid polymer electrolyte membranes (SPEM) had been successfully prepared from poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). The solution casting method yielded highly hydrophilic membranes with uniform structure that were suitable for electrochemical applications. The room temperature ionic conductivity of the alkaline PVA/PAA polymer electrolyte membranes was in the range of 0.142–0.301 S cm⁻¹ depending on the composition. The cyclic voltammetry analysis was carried out using Zn|SPEM|Zn and Al|SPEM|Al cells. The analysis results revealed the excellent electrochemical stability of these newly developed alkaline solid PVA/PAA polymer electrolyte membranes. Metal-air fuel cells were also prepared from the alkaline solid PVA/PAA polymer electrolyte membranes. The electrochemical cell performance was evaluated based on Zn-air and Al-air cells at C/10 and C/5 discharge rates. The experimental results exhibited high percent of utilization for metal powders at room temperature. It was up to 90% for Zn-air cell when assembled with PVA:PAA = 10:7.5 polymer electrolyte membrane and discharged at C/10 rate. The power density could be as high as 50 mW cm⁻² at room temperature. However, the cell percent utilization was reduced to 73% with the same composition electrolyte membrane when C/5 discharge rate was tested.     

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.     

Electrical,optical and photoelectrochemical studies on a solid PEO-polymer electrolyte doped with low viscosity ionic liquid

Solid polymer electrolyte (PEO:KI:I₂) membranes doped with low viscosity (34 cP at 25 °C) ionic liquid EMImTFSI (1-ethyl 3-methylimidazolium bis(trifluoromethylsulfonyl)imide) showing plasticizing effect as well as improved dye sensitized solar cell efficiency have been reported first time. Apart from ionic conductivity enhancement due to large number of free charge carriers provided by ionic liquid (IL) it assist in reducing cystallinity of polymer electrolyte matrix which was confirmed by polarized optical microscopy (POM). Cyclic voltammetry was carried out to study the reactions of iodide, iodine and IL in polymer electrolyte matrix.     

染料敏化太阳电池用聚合物电解质

综述了本研究小组近年来用于染料敏化太阳电池中聚合物电解质的研究概况.设计合成了几类性能优良的聚合物电解质,较好地改进了液体电解质染料敏化太阳电池(DSSC)的使用稳定性,研究结果具有实际应用的价值,并提出了此领域研究今后的发展方向.     

微孔型聚丙烯腈固体电解质的结构与导电性能研究

用蒸汽相沉析法和液相沉析法分别制备了两类高孔隙率的聚丙烯腈 (PAN)微孔膜 .用扫描电子显微镜对微孔膜的形态进行了观察 ,发现前者为均匀的蜂窝状结构 ,而后者则具有不对称的三层次结构 .又用这两类微孔膜分别制备了两个系列的微孔型PAN电解质 .电性能测试表明前者的室温电导率较高 ,可以达到 4×10 - 3 S cm ,后者的电导率则相对较低 .微孔膜本身诸因素对微孔型PAN电解质电导率的影响顺序为微孔膜结构—孔隙率—微孔孔径     

ADSORPTION OF COLLOIDAL MATERIALS ON POLYMER SURFACES

Polypropylene surfaces were rendered cationic by hydrophobic implantation and by grafting a quaternized polyvinyl pyridine onto a plasma treated surface. The polypropylene surface with the grafted polymer showed a strong adsorption of an anionic surfactant, corresponding to about ten monomolecular layers. High concentration of electrolyte caused a reduction of the adsorption at low concentrations of surfactant.