聚偏氟乙烯-Nafion共混膜的制备及阻醇质子导电性能研究

直接甲醇燃料电池 (Ｄｉｒｅｃｔｍｅｔｈａｎｏｌｆｕｅｌｃｅｌｌ,ＭＤＦＣ)以高效、清洁和燃料储运方便等优点成为一类极具发展潜力的新型动力源 .但目前ＤＭＦＣ中普通使用的全氟磺酸膜 (如ＮａｆｉｏｎＴＭ 系列膜 )阻醇性能太差 ,导致大量甲醇从阳极穿过膜直接透到阴极 ,造成燃料的浪费和电池整体性能的下降 .据文献报道 ,即使甲醇浓度低到 1ｍｏｌ Ｌ ,也有近40 %的醇透过膜 .缺乏高性能的阻醇质子导电聚合物电解质膜是制约ＤＭＦＣ发展的瓶颈之一 .已有一些研究人员致力于新型膜材料的开发 ,如有人研制了聚苯并咪唑膜[1] 及各种掺杂…     

A Pd-impregnated nanocomposite Nafion membrane for use in high-concentration methanol fuel in DMFC

Pd nanophases in a Nafion polymer membrane electrolyte were used to enhance DMFC performance by preventing or reducing methanol crossover through the electrolyte. Interestingly, the Pd-impregnated nanocomposite membrane showed a lower permeability for methanol and maintained a proton conductivity comparable to that of a pure Nafion membrane. Because of the modification of the membrane by the Pd nanophases, a high molar concentration of methanol could be applied for use in practical DMFC without any power loss.     

直接甲醇燃料电池中的膜性能比较

制备了磺化聚醚醚酮(SPEEK)和磺化酚酞型聚醚砜(SPES-C)两种质子交换膜,考察了其质子导电和阻醇性能.实验发现,两种新型质子交换膜具有一定的化学稳定性和质子电导率,尤其在高温下两种新膜的质子电导率与Nafion膜接近.两种新膜的甲醇透过系数要比Nafion膜的低1～2个数量级.分别以两种新型膜和Nafion115膜为电解质制备了直接甲醇燃料电池膜电极,讨论了膜材料的性能对直接甲醇燃料电池性能的影响.结果表明,膜材料的阻醇性越好,电池的开路电压越高;膜的电导率越高,在较高电流密度区域内电池的性能越好.     

磷钨酸/磺化聚醚醚酮质子导电复合膜

直接甲醇燃料电池(Direct methanol fuelcell,DMFC)作为各种用途的可移动动力源具有高效、清洁和燃料储运方便等优点,成为20世纪90年代以来研究与开发的热点。目前,这种电池的研究难点主要集中在催化剂不稳定和质子交换膜透醇上,DMFC膜不但要可传递质子和绝缘电子,还应具有     

Surface modified multi‐walled carbon nanotubes and Nafion nanocomposite membranes for use in fuel cell applications

The preparation and characterization of the nanocomposite polyelectrolyte membranes, based on Nafion, sulfonated multi‐walled carbon nanotubes (MWCNT‐SO₃H) and imidazole modified multi‐walled carbon nanotubes (MWCNT‐Im), for direct methanol fuel cell applications is described. The results showed that the modification of multi‐walled carbon nanotubes (MWCNT) with proton‐conducting groups (sulfonic acid groups or imidazole groups) could enhance the proton conductivity of the nanocomposite membranes in comparison to Nafion 117. Regarding the interactions between the protonated imidazole groups, grafted on the surface of MWCNT, and the negatively charged sulfonic acid groups of Nafion, new electrostatic interactions can be formed in the interface of the Nafion and MWCNT‐Im, which result in both lower methanol permeability and higher proton conductivity. The physical characteristics of these manufactured nanocomposite membranes were investigated by thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, water uptake, methanol permeability, and ion exchange capacity, as well as proton conductivity. The Nafion/MWCNT‐Im membranes showed the higher proton conductivity, lower methanol permeability, and, as a consequence, a higher selectivity parameter in comparison to the neat Nafion or Nafion membrane containing MWCNT‐SO₃H or ─OH functionalized multi‐walled carbon nanotubes (MWCNT‐OH) membranes. The obtained results indicated that the Nafion/MWCNT‐Im membranes could be used as efficient polyelectrolyte membranes for direct methanol fuel cell applications.     

磺化酚酞型聚醚砜膜的制备及其阻醇和质子导电性能

直接甲醇燃料电池 (Directmethanolfuelcell,DMFC)以高效、清洁和燃料储运方便等优点适宜于作为各种用途的可移动动力源 ,成为 2 0世纪 90年代以来研究与开发的热点[1,2 ] .目前 ,这种电池的研究难点主要集中在催化剂不稳定和质子交换膜透醇上 .一张好的DMFC膜不但要可传递质子、绝缘电子 ,还应具有良好的阻醇性能 .如果膜的阻醇性能不好 ,甲醇会穿过膜到达阴极 ,与氧直接反应而不产生电流 ,不但造成燃料的浪费 ,同时也影响阴极的正常反应 ,使电池效率下降[3 ] .目前广泛应用于燃料电池中的Nafion 系列膜是由美国DuPont公司生产的一种…     

Self-assembled polyelectrolyte multilayered films on Nafion with lowered methanol cross-over for DMFC applications

The paper is concerned with the deposition of self-assembled polyelectrolyte multilayer on Nafion membrane by layer-by-layer (LbL) technique with lowered methanol cross-over for direct methanol fuel cell (DMFC) applications. The formation of self-assembled multilayered film on Nafion was characterized by UV–vis spectroscopy and it was found that the polyelectrolyte layers growth on the Nafion surface regularly. Furthermore, the proton conductivity and methanol cross-over measurements were carried out for characterization of the LbL self-assembled composite membranes. The results showed that the concentration and pH of the polyelectrolytes significantly affect the proton conductivity and methanol barrier properties of the composite membranes. 10⁻¹ monomol polyelectrolyte concentration and pH 1.8 was found to be optimum deposition conditions considering proton conductivity and methanol permeation properties of the LbL self-assembled composite membranes. The methanol permeability of the 10 bi-layers of PAH1.8/PSS1.8 deposited LbL self-assembly composite membrane was significantly suppressed and found to be 4.41 × 10⁻⁷ cm²/s while the proton conductivity value is in acceptable range for fuel cell applications.     

Formation and characterization of PEDOT-modified Nafion 117 membranes

Nafion 117 membranes were modified with a thin film of poly(3,4-ethylenedioxythiophene) (PEDOT) by a diffusion-controlled polymerization process using a two-compartment cell with the monomer EDOT on one side of the membrane and the oxidizing agent FeCl₃ on the other side. The methanol permeability and ion conductivity of the composite PEDOT/Nafion membranes were measured as a function of temperature and polymerization time by DC and AC polarization measurements in four-electrode technique and permeation experiments in a diaphragm cell. These modified membranes have lower methanol permeability while maintaining adequate conductivity.     

Blend membranes of Nafion/sulfonated poly(aryl ether ketone) for direct methanol fuel cell

Sulfonated poly(aryl ether ketone) (sPAEK) synthesized by LG Chem. was confirmed by FT-IR. To estimate the thermal stability, glass transition temperature and decomposition temperature were investigated. They showed that sPAEK had good thermal properties. The proton conductivity, methanol permeability and water uptake of sPAEK were also measured. Nafion/sulfonated poly(aryl ether ketone) composite membranes were prepared by blending two materials. The blend ratios of sPAEK and Nafion were 2:1, 3:1, 5:1, and 7:1. The blend membranes showed phase separated morphology since they became immiscible during the solvent evaporation process. Due to the differences in specific gravity and solvent concentration profile during the solvent evaporation process, the upper region had lower Nafion volume fraction with smaller domains and the lower region had higher Nafion volume fraction with larger domains. Mechanical properties such as the stress at break, yield stress, Young's modulus, and elongation at break were measured. The sPAEK had better mechanical properties than Nafion. The mechanical properties increased with increasing sPAEK content. Proton conductivity and methanol permeability of the blend membranes were lower than those of Nafion. Both decreased with decreasing Nafion content. Since the methanol permeability of sPAEK was lower than that of Nafion, sPAEK acted as the methanol barrier. Water uptake of sPAEK was higher than that of Nafion.     

磺化聚醚醚酮膜的制备及其阻醇和质子导电性能

直接甲醇燃料电池 (Ｄｉｒｅｃｔｍｅｔｈａｎｏｌｆｕｅｌｃｅｌｌ,ＤＭＦＣ)以高效、清洁和燃料储运方便等优点适宜于作为各种用途的可移动动力源 ,成为 2 0世纪 90年代以来研究与开发的热点[1,2 ] .目前 ,这种电池的研究难点主要集中在催化剂不稳定和质子交换膜透醇上 .一张好的ＤＭＦＣ膜不但要可传递质子、绝缘电子 ,还应具有良好的阻醇性能 .如果膜的阻醇性能不好 ,甲醇会穿过膜到达阴极 ,与氧直接反应而不产生电流 ,不但造成燃料的浪费 ,同时也影响阴极的正常反应 ,使电池效率下降[3] .目前广泛应用于燃料电池中的Ｎａｆｉｏｎ系列膜…     

DMFC用PES/SPEEK共混阻醇质子交换膜

将磺化聚醚醚酮(SPEEK, 磺化度DS为68.3%)和聚醚砜(PES)两种聚合物共混制得PES/SPEEK共混膜. DSC研究表明两种聚合物之间具有较好的相容性, 因而共混膜均匀致密, 未发生大尺度相分离. PES的混入能有效降低膜的溶胀度及甲醇透过系数. 纯SPEEK 膜40 ℃时在1 mol•L−1甲醇水溶液中溶胀度达到160%, 45 ℃时就完全溶解, 而含30%(w)PES的共混膜在80 ℃时的溶胀度仅有15%. 室温下含20%−30%(w)PES的共混膜的甲醇透过系数为1×10−7 cm2•s−1左右, 比Nafion 115膜的透过系数小一个数量级. 尽管80 ℃下30%(w)PES/SPEEK共混膜的电导率与Nafion 115膜相当, 但由于共混膜的厚度比Nafion 115膜小1/3左右, 膜电阻较小, 因而其电池性能比Nafion 115膜的好.     

Acid–base blend membranes based on 2-amino-benzimidazole and sulfonated poly(ether ether ketone) for direct methanol fuel cells

Direct methanol fuel cells (DMFC) are attractive for portable and automobile power needs, but their commercialization is hampered by high methanol permeability and the high cost of the currently used Nafion membrane. We report here a novel, low-cost blend membrane consisting of polysulfone-2-amide-benzimidazole (a basic polymer) and sulfonated poly(ether ether ketone) (an acidic polymer), which facilitates proton conduction through acid–base interactions while preserving excellent chemical and mechanical stabilities. The blend membrane exhibits performance in DMFC much higher than that of Nafion 115 and similar to that of Nafion 112, but with a remarkably superior long-term performance than Nafion 112 due to significantly reduced methanol crossover, enhancing the commercialization prospects of DMFC.     

Organically modified montmorillonite and chitosan–phosphotungstic acid complex nanocomposites as high performance membranes for fuel cell applications

Nanocomposite membranes based on polyelectrolyte complex (PEC) of chitosan/phosphotungstic acid (PWA) and different types of montmorillonite (MMT) were prepared as alternative membranes to Nafion for direct methanol fuel cell (DMFC) applications. Fourier transform infrared spectroscopy (FTIR) revealed an electrostatically fixed PWA within the PEC membranes, which avoids a decrease in proton conductivity at practical condition. Various amounts of pristine as well as organically modified MMT (OMMT) (MMT: Cloisite Na, OMMT: Cloisite 15A, and Cloisite 30B) were introduced to the PEC membranes to decrease in methanol permeability and, thus, enhance efficiency and power density of the cells. X-ray diffraction patterns of the nanocomposite membranes proved that MMT (or OMMT) layers were exfoliated in the membranes at loading weights of lower than 3 wt.%. Moreover, the proton conductivity and the methanol permeability as well as the water uptake behavior of the manufactured nanocomposite membranes were studied. According to the selectivity parameter, ratio of proton conductivity to methanol permeability, the PEC/2 wt.% MMT 30B was identified as the optimum composition. The DMFC performance tests were carried out at 70 °C and 5 M methanol feed and the optimum membrane showed higher maximum power density as well as acceptable durability compared to Nafion 117. The obtained results indicated that owing to the relatively high selectivity and power density, the optimum nanocomposite membrane could be considered as a promising polyelectrolyte membrane (PEM) for DMFC applications.     

SPEEK/PES-C、SPEEK/SPES-C共混质子交换膜研究

通过在磺化聚醚醚酮(SPEEK,DS=61.68%)中分别混入酚酞型聚醚砜(PES-C)、磺化酚酞型聚醚砜(SPES-C,DS=53.7%)制备出SPEEK/PES-C、SPEEK/SPES-C共混质子交换膜.结果表明,共混的两种聚合物之间均具有较好的相容性.PES-C、SPES-C的混入能有效降低膜的溶胀及甲醇透过,且随着共混量的增加,这种作用越趋明显.纯SPEEK膜在75℃左右溶解,而SPEEK/PES-C(30wt%)、SPEEK/SPES-C(30wt%)共混膜在80℃时溶胀度仅为22.5%、26.32%.在室温至80℃范围内,纯SPEEK及共混膜的甲醇透过系数都在10-7cm2.s-1数量级上,远小于Nafion115膜.在饱和湿度下,温度大于90℃时,SPEEK/PES-C(20wt%)共混膜电导率超过Nafion115膜;温度大于110℃时,SPEEK/SPES-C(30wt%)共混膜电导率与Nafion115膜相当,达到0.11S.cm-1.高电导率,低透醇系数以及明显提高了的可使用温度表明该类共混膜有望在DMFC中使用.     

低甲醇透过直接甲醇燃料电池

复合膜;甲醇透过率;低甲醇透过直接甲醇燃料电池     

Poly(vinyl alcohol) (PVA)/sulfonated polyhedral oligosilsesquioxane (sPOSS) hybrid membranes for direct methanol fuel cell applications

Organic/inorganic hybrid membranes based on poly(vinyl alcohol) (PVA) and sulfonated polyhedral oligosilsesquioxane (sPOSS), crosslinked by ethylenediaminetetraacetic dianhydride (EDTAD), were prepared as candidate materials for proton exchange membranes in direct methanel fuel cell (DMFC) applications. Fourier transform infrared (FT‐IR) spectroscopy and ion exchange capacity measurements for the prepared networks clearly revealed sPOSS incorporation. We found that proton conductivity increased and methanol permeability decreased with increasing sPOSS content in the hybrid membrane. In particular, our hybrid membranes demonstrated proton conductivities as high as 0.042 S/cm, which is comparable to that of Nafion?, while exhibiting two orders of magnitude lower methanol permeability as compared to Nafion?. We postulate that the polar sulfonic acid groups of the incorporated sPOSS cages assemble to provide ion conduction paths while the hydrophobic portions of the same sPOSS cages combine to form a barrier to methanol permeation with improved thermal stability of the hybrid membrane. Copyright © 2007 John Wiley & Sons, Ltd.     

磺化聚醚酰亚胺/聚醚砜共混型质子交换膜的制备及其性能

以磺化聚醚酰亚胺(SPEI)和聚醚砜(PES)为原料, 采用溶液共混法成功制备出了SPEI/PES共混型质子交换膜,并经热重分析、AFM、SEM等对膜的结构和性能进行了表征. 结果表明, 共混膜较纯SPEI膜具有更高的热稳定性和较低的溶胀性; 在室温环境下, 共混膜在干态和湿态时均具有优异的机械性能; 与纯SPEI膜相比, 共混膜的形态结构更为致密, 这将有利于降低甲醇的渗透性. 采用交流阻抗法和隔膜扩散法分别考察了膜的质子传导性和阻醇性能, 对于共混质量比为50/50的膜来说, 其质子传导率达到了5.5 mS·cm-1的水平, 能满足质子交换膜的需求, 但其甲醇渗透系数明显降低, 仅为市用Nafion 112膜的5%, 这表明该共混膜有望作为一种新型的直接甲醇燃料电池用质子交换膜.     

磺化聚芳醚砜/磺化聚酰亚胺复合质子交换膜的制备与性能研究

利用溶液浇铸法制备了一系列双磺化型磺化聚芳醚砜/磺化聚酰亚胺(SPAES/SPI)复合质子交换膜.扫描电子显微镜(SEM)结果显示复合膜不存在明显的相分离,表明二者具有很好的相容性.由于SPI的引入,复合膜在甲醇中稳定性较纯SPAES具有大幅的提高,比Nafion112低得多的甲醇吸收率表明了这些复合膜具有比后者更低的甲醇透过率.复合膜显示了与单组分膜相类似的高温分解稳定性,磺酸基团的分解温度达到了290℃以上.复合膜显示出远高于纯SPAES膜的尺寸稳定性能,在130℃高温中200h处理后,所有的复合膜均保持了高的机械性能,而此时纯SPAES膜已经溶解于水中.而且由于两种磺化聚合物间的复合,复合膜维持了较高的IEC水平,显示了较高的质子导电率,在80%相对湿度时的质子导电率与Nafion112相近,而在水中的质子导电率均高于Nafion112.     

含杂萘联苯结构聚合物膜的直接甲醇燃料电池性能

质子交换膜是直接甲醇燃料电池(DMFC)的关键组成部分. 通过磺化制备了磺化杂萘联苯聚醚酮(SPPEK)、磺化杂萘联苯聚醚砜(SPPES)和磺化杂萘联苯聚醚砜酮(SPPESK)三种含杂萘联苯结构的新质子交换膜, 测试了其热稳定性、质子导电性和甲醇透过性能. SPPESK的热分解温度比相近离子交换容量(IEC)的SPPEK和SPPES约低100 ℃, 三种膜均具有良好的导电和阻醇性能; 分别以三种膜为电解质组装DMFC考察了其性能, DMFC的开路电压随膜的阻醇性的提高而增大, 三种膜的开路电压均高于Nafion115膜, 但在较高电流密度的区域三种新膜的性能均比Nafion115膜差.     

直接甲醇燃料电池新型聚合物膜的研究

通过溶液共混方法 ,制备了聚偏氟乙烯与聚苯乙烯磺酸 (PVDF_PSSA)、聚偏氟乙烯与Nafion(PVDF_Nafion)两种共混膜 .研究了膜组成对膜电导率和甲醇透过率的影响 .与Nafion 1 1 7膜相比 ,PVDF_Nafion共混膜在Nafion含量为 2 5wt%时 ,电导率σ下降 2个数量级 ,而甲醇透过率P却降低 3个数量级 .若以 (σ/P)为综合指标 ,则PVDF_Nafion共混膜和PVDF_PSSA共混膜的综合性能分别比Nafion 1 1 7膜高约 4 0倍、1 6倍