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综述了质子交换膜在直接甲醇燃料电池中的作用和要求,目前质子交换膜的研究进展,重点介绍了适用于直接甲醇燃料电池用质子交换膜的各种材料的改性方法。按照物理和化学两种方法对几类质子交换膜材料进行改性。同时对比了改性前和改性后各种聚合物膜的物性特点。 相似文献
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进行了甲醇重整气与燃料电池的联合试验。与PEMFC配套的甲醇制氢氢源系统运行稳定,出口氢浓度为43-45%,CO含量为0-6ppm,压力控制在0.22~0.25MPa(表压)。单对电池氢的利用率可达到83%,电池排氢浓度为12%以下。不同氢源下PEMFC性能从高到底的顺序为纯氢、甲醇重整气、配气。单电池试验表明,微量的甲醇或二甲醚对电池未发现明显的影响。 相似文献
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质子交换膜燃料电池可视化研究进展 总被引:1,自引:0,他引:1
质子交换膜燃料电池(包括氢氧质子交换膜燃料电池和直接甲醇燃料电池)内的两相流动以及相应的水管理、气管理对燃料电池的性能和寿命有很大的影响,而可视化方法是研究流场槽道内两相流动非常重要的方法之一。可视化实验可以真实地展示气泡或液滴在流场槽道内的生成以及发展过程,有利于了解其进化机制,从而进一步优化气管理、水管理并提高电池性能。本文主要综述了质子交换膜燃料电池两极流场内两相流动的可视化研究进展,讨论了扩散层的润湿性以及扩散层内水的传递机理,还介绍了实现可视化的方法,并提出了可视化研究的不足及发展方向。 相似文献
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引 言质子交换膜燃料电池 (PEMFC)是极具吸引力的电化学能量转换装置 ,是未来电动汽车的主要动力源 ,也是洁净高效的新型化学电源 .对于电动汽车的应用 ,要求PEMFC提供高能量密度、低催化剂负载量 ,以降低系统体积和成本[1] .膜电极(membraneandelectrodeassembly ,简称MEA)是由聚合物电解质膜、电极催化剂和扩散层材料组合而成的三明治式结构组件 ,类似于计算机的芯片 ,是燃料电池的核心部件 ,长期以来大量的研究集中于MEA新材料设计与制备 ,以提高电池的性能 .近年来 ,对MEA的微观结构分析、MEA制备工艺与电池性能的关系研究工作明显增多[2~ 7] .从PEM FC研究实践中发现 ,如何减少电极中Pt催化剂负载量并能继续保持或者提高电池性能的MEA制备技术开发至关重要 .其中超薄Pt层沉积法[8~ 10 ] 是MEA的制备新技术之一 .与传统的基于墨水涂布(based inkprinting)的方法相比 ,喷溅沉积法(sputterdeposit) [9] 制备的MEA提高了电池的性能和催化剂的利用率 ,它是用直接喷溅沉积法 (directlydeposit) [10... 相似文献
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The impedance characteristics of the ohmic overpotential of the proton exchange membrane (PEM) fuel cells are studied analytically using the process modeling approach. The water transport in the membrane, the cathode catalyst layer, and gas diffusion layer are analyzed. The analytical relation of the impedance of the ohmic loss is determined and is converted to an equivalent circuit. Then, the impedance of a PEM fuel cell is measured experimentally in different current densities, operating temperatures and the anode and cathode relative humidities. The measured impedances are compared with the predicted ones from the analytical model. It is shown that the predicted impedance characteristics are in great agreement with the measured ones in all different operating conditions. 相似文献
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T. Z. Fu J. Liu Z. M. Cui J. Ni G. Zhang H. B. Yu C. J. Zhao Y. H. Shi H. Na W. Xing 《Fuel Cells》2009,9(5):570-578
The sulphonated phenol novolac (PNBS) which was used as a curing agent of epoxy was synthesised from phenol novolac (PN) and 1, 4‐butane sultone and confirmed by FTIR and 1H NMR. The degree of sulphonation (DS) in PNBS was calculated by 1H NMR. The semi‐IPN membranes composed of sulphonated tetramethyl poly(ether ether ketone) (STMPEEK) (the value of ion exchange capacity is 2.01 meq g–1), epoxy (TMBP) and PNBS were successfully prepared. The semi‐IPN membranes showed high thermal properties which were measured by differential scanning calorimeter (DSC) and thermogravimetric analyses (TGA). With the introduction of the cross‐linked TMBP/PNBS, the mechanical properties, dimensional stability, methanol resistance and oxidative stability of the membranes were improved in comparison to the pristine STMPEEK membrane. Although the proton conductivities of the semi‐IPN membranes were lower than those of the pristine STMPEEK membrane, the higher selectivity defined as the ratio of the proton conductivity to methanol permeability was obtained from the STMPEEK/TMBP/PNBS‐14 semi‐IPN membrane. The results indicated that the semi‐IPN membranes could be promising candidates for usage as proton exchange membranes in direct methanol fuel cells (DMFCs). 相似文献
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In the present work, carbon nanotubes (CNT) and CNT‐carbon nanohorns (CNH) (0, 30, 50, 70 and 100 wt.% CNH) composite Buckypapers (BPs) were fabricated using vacuum filtration technique. Structure and property relation of composite BPs were studied using scanning electron microscope, four probe technique, BET surface area and contact angle measurements. Properties such as electrical conductivity, hydrophobic nature and microstructure of CNT‐30 wt.% CNH composite BP are superior to other composite BP. Hence, CNT‐30 wt.% CNH composite BP is chosen as a microporous layer (MPL) for PEMFCs and tested in fuel cell testing fixture. Polarization studies reveal that the cells performance with composite BPs is comparable with SGL‐MPL based cell. Hydrogen pumping and polarization studies of the cells confirms that composite BPs act as a good MPL at anode as well as cathode at 0.4 to 0.8 V. Hence, CNT‐CNH composite BPs are potential candidates for PEMFC applications. 相似文献
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This project designs and simulates a cogeneration system of proton exchange membrane fuel cell using Matlab/Simulink software and Thermolib heat module components. The system not only satisfies the need for electric power, but also provides heat recovery for future uses, thus increasing energy transfer efficiency. PEM fuel cell‐based cogeneration system is introduced, including the hydrogen supply subsystem, air supply subsystem, load control subsystem, real‐time monitoring block, and heat recovery subsystem. The complete fuel cell‐based cogeneration system is constructed by assembling the fuel cell stack, fuel, coolant flow rate control system, and all the subsystems. In addition to the fuel cell experiment, influencing factors on the fuel cell‐based system, such as the fuel inhale rate, coolant flow rate, system temperature, fuel humidification, thermal efficiency, electrical efficiency, and combined heat and power (CHP) system efficiency, are analyzed and charted regarding different loads. In this system, with the power at 3 kW, the CHP efficiency reaches 64%. The CHP efficiency is 76.6% with the load power at 4 kW. When the power is at 5 kW, the thermal efficiency reaches 36.9% and the CHP efficiency reaches 82.9%. 相似文献
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The major objectives of this study are to identify the best activation procedure between commonly used procedures that can significantly reduce the conditioning duration and to understand the change in interfacial properties during conditioning. In order to do that, three on‐line activation procedures were employed for activating of identical MEAs in PEMFC and studied by polarization curve and electrochemical impedance spectroscopy (EIS). These methods are constant current (0.25 A cm–2) for 19 h, constant voltage (0.6 V) for 9 h, and USFCC protocol. The best performance was achieved by USFCC protocol within 15 h, but by constant voltage procedure, 96% of mentioned protocol was obtained during 6 h. So constant voltage activation proceeded remarkably fast, and most of the activation process was achieved in the first few hours. Obtained results from Nyquist plots during/after MEA conditioning indicate mentioned process are irreversible and interfacial structures of MEAs are different even after finishing of MEA break‐in. It could be affected the MEA performance and even its durability. These results are consistence with the obtained performance of activated MEAs either in H2/air or H2/O2 PEMFC. We found the mentioned constant current procedure consume long time without reaching to expectable performance even after 19 h. 相似文献
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The cathode electrocatalyst layers were prepared by in situ growing Pt nanowires (Pt‐NWs) in two kinds of matrixes with various Pt loadings for proton exchange membrane fuel cells (PEMFCs). Commercial carbon powder and 20 wt.% Pt/C electrocatalyst were used as the matrix material for the comparison. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), polarization curves tests, and electrochemical impedance spectroscopy (EIS) were carried out to examine the effects of the matrix materials on the Pt‐NW growing and the electrode performance. The optimum Pt‐NW loadings of 0.30 mg cm−2 in the carbon matrix (CM) and 0.20 mg cm−2 for the Pt/C matrix (PM) were obtained. The results indicated that the Pt‐NWs grown in the CM had a better crystalline, longer size length and better catalyst activity than those in the PM. The mechanism of the matrix affection is further discussed in this paper. 相似文献