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1.
A.A. Kulikovsky 《Journal of Applied Electrochemistry》2000,30(9):1005-1014
The results of a numerical simulation of a direct methanol fuel cell (DMFC) with liquid methanol feed are presented. A two-dimensional numerical model of a DMFC is developed based on mass and current conservation equations. The velocity of the liquid is governed by gradients of membrane phase potential (electroosmotic effect) and pressure. The results show that, near the fuel channel, transport of methanol is determined mainly by the pressure gradient, whereas in the active layers, and in the membrane, diffusion transport dominates. Shaded zones, where there is a lack of methanol, are formed in front of the current collectors. The results reveal a strong influence of the hydraulic permeability of the backing layer K
p
BL
on methanol crossover through the membrane. If the value of K
p
BL
is comparable to that of the membrane and active layers, electroosmotic effects lead to the formation of an inverse pressure gradient. The flux of liquid driven by this pressure gradient is directed towards the anode and reduces methanol crossover. 相似文献
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Material aspects of the liquid feed direct methanol fuel cell 总被引:3,自引:0,他引:3
A study of a small scale Liquid Feed Direct Methanol Fuel Cell (LFDMFC), based on solid polymer electrolyte membrane, is reported. Two flow cell designs, one with a parallel flow channel arrangement and the other with a spot design of flow bed, are used. The structure of the DMFC comprises a composite of two porous electrocatalytic electrodes; Pt–Ru–carbon catalyst anode and Pt–carbon catalyst cathode, on either side of a solid polymer electrolyte (SPE) membrane. The performance of three Pt–Ru catalysts is compared. The influence of the degree of Teflon loading on the electrode structure is also reported. The effect of the following parameters: cell temperature, oxygen gas or air pressure, methanol liquid flow rate and methanol concentration on the power performance is described. 相似文献
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直接甲醇燃料电池的阳极采用甲醇作为燃料,阴极采用纯氧或空气作为氧化剂,具有能量密度高、燃料储存方便、结构简单的优点,有望成为下一代小型电子设备的电源。反应物的浓度对直接甲醇燃料电池的性能、效率和燃料利用率等都有很大的影响,因此对燃料电池中反应物的浓度进行准确测量至关重要。本文综述了直接甲醇燃料电池中反应物浓度的测量方法,主要包括化学测量方法和物理测量方法,并对这些测量方法的优缺点、基本原理及适用范围进行了分析和评述。 相似文献
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An investigation of scale-up on the response of the direct methanol fuel cell under variable load conditions 总被引:3,自引:0,他引:3
The electrical response of the direct methanol fuel cell, based on solid polymer electrolyte, to variable load is reported. The dynamic power response of the direct methanol fuel cell is of importance particularly when the cell is used for transportation applications. The study reports the dynamic characteristics of a small-scale cell (active area 9 cm2), a large-scale cell (active area 272 cm2), and a three-cell stack. The effect of operating conditions (i.e., flow rate, cathode pressure and solution concentration) on the voltage response is described and the effect of a change of scale is discussed. 相似文献
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Li Liu Cong Pu Rameshkrishnan Viswanathan Qinbai Fan Renxuan Liu E.S Smotkin 《Electrochimica acta》1998,43(24):9547
A comparative study of the use of supported and unsupported catalysts for direct methanol fuel cells has been performed. The effect of catalyst loading, fuel concentration and temperature dependence on the anode, cathode and full fuel cell performance was determined in a fuel cell equipped with a reversible hydrogen reference electrode. Although the measured specific activities of supported catalysts were as much as 3-fold greater than the unsupported catalysts, membrane electrode assemblies prepared with supported catalysts showed no improvement with loadings above 0.5 mg/cm2. Fuel cells utilizing 0.46 mg/cm2 supported catalyst electrodes performed as well as unsupported catalyst electrodes with 2 mg/cm2. The temperature dependence and methanol concentration dependence studies both suggest increased methanol permeation through the thinner supported catalyst layers relative to the unsupported catalyst layers. 相似文献
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Sulfonated polyimide (SPI) membranes have been evaluated as electrolyte membranes in direct methanol fuel cells (DMFCs). The membrane-electrode assembly (MEA) was made by hot-pressing the membrane, an anode and a cathode, catalyzed with PtRu/CB (PtRu dispersed on carbon black) and Pt/CB bound with Nafion® ionomer, respectively. The performance of the cell based on SPI was compared with that of Nafion® 112 in various operation conditions such as cell temperature (Tcell), cathode relative humidity (RH), and methanol concentration (CMeOH). The methanol crossover at the cell based on SPI was a half of Nafion® 112, resulting in the improved cell efficiency. Advantage of the use of SPI became much distinctive from the conventional Nafion® 112 when the DMFC was operated at a higher Tcell or a higher CMeOH. 相似文献
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T. Schultz U. Krewer T. Vidaković M. Pfafferodt M. Christov K. Sundmacher 《Journal of Applied Electrochemistry》2007,37(1):111-119
The dynamic operating behaviour of the direct methanol fuel cell (DMFC) is governed by several physico-chemical phenomena
which occur simultaneously: double layer charging, electrode kinetics, mass transport inside the porous structures, reactant
distributions in the anode and cathode flowbeds etc. Therefore it is essential to analyse the interactions of these phenomena
in order to fully understand the DMFC. These phenomena were initially analysed independently by systematic experiments and
model formulations. Electrode kinetics were determined by fitting models of varying complexity to electrochemical impedance
spectroscopy (EIS) measurements. Reaction intermediates adsorbed on the catalyst seem to play a key role here. To describe
mass transport across the DMFC a one-dimensional model was formulated applying the generalised Maxwell–Stefan equations for
multi-component mass transport and a Flory–Huggins model for the activities of mobile species inside the membrane (PEM). Also
swelling of the PEM as well as heat production and transport were considered. Finally, the anode flowbed was analysed by observing
flow patterns in different flowbed designs and measuring residence time distributions (RTDs). Detailed CFD models as well
as simpler CSTR network representations were used to compare to the experimental results. Even the simpler models showed good
agreement with the experiments. After these investigations the results were combined: the electrode kinetics model was implemented
in the mass transport model as well as in the CSTR network flowbed model. In both cases, good agreement, even to dynamic experiments,
was obtained. 相似文献
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A 500 h life-test of direct methanol fuel cell (DMFC) was conducted in a single cell. X-ray diffraction (XRD) and transmission electron microscopy (TEM) images showed that after life-test, the particle size of electrocatalysts increased both in anode and cathode, and the degree is higher in cathode. Electrochemical areas (ECAs) of anode and cathode catalyst were evaluated by CO-stripping and hydrogen-desorption test, respectively. It was found that the ECA loss is higher than the specific surface area (SSA) loss (determined by XRD) that merely due to the sintering of the electrocatalyst particles. Energy dispersive X-ray analysis (EDX) revealed a crossover of ruthenium from the anode side to the cathode side in the cell. 相似文献
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Francisco Alcaide Garbiñe Álvarez Larraitz Ganborena Juan J. Iruin Oscar Miguel J. Alberto Blazquez 《Polymer Bulletin》2009,62(6):813-827
A series of novel hybrid proton conducting membranes based on sulfonated naphthalimides and phosphotungstic acid (PTA) were prepared from N-Methyl Pyrrolidone (NMP) solutions. These hybrid organic-inorganic materials, composed of two proton-conducting components, have high ionic conductivities (9.3 × 10?2 S cm?1 at 60 °C, 15% PTA), and show good performance in H2|O2 polymer electrolyte membrane fuel cells (PEMFC), previously reported by us. Moreover, they have low methanol permeability compared to Nafion®112. In this paper we describe, for the first time, the behaviour of these hybrid membranes as electrolyte in a direct methanol fuel cell (DMFC). The maximum power densities achieved with PTA doped sulfonated naphthalimide membrane, operating with oxygen and air, were 34.0 and 12.2 mW cm?2, respectively; about the double and triple higher than those showed by the non-doped membrane at 60 °C. 相似文献
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Effects of Fe3+ and Cr3+ ions on the performance of direct methanol fuel cell were investigated. The results show that the cell performance decreased remarkably when the concentration of Fe3+ or Cr3+ exceeded 1 × 10−4 mol L−1. Fe3+ displayed a strong negative effect on the catalytic oxidation of methanol, while Cr3+ affected the cell performance primarily by exchanging with protons of the membrane/ionomer and resulted in ionic conductivity losses. Complete recovery of the cell performance was not obtained after flushing the cell with deionized water. 相似文献
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This research aims at increasing the utilization of platinum-ruthenium alloy (Pt-Ru) catalysts and thus lowering the catalyst
loading in anodes for methanol electrooxidation. The direct methanol fuel cell’s (DMFC) anodic catalysts, Pt-Ru/C, were prepared
by chemical reduction with a reducing agent added in two kinds of solutions under different circumstances. The reducing agent
was added in hot solution with the protection of inert gases or just air, and in cold solution with inert gases. The catalysts
were treated at different temperatures. Their performance was tested by cyclic voltammetry and potentiostatic polarization
by utilizing their inherent powder microelectrode in 0.5 mol/L CH3OH and 0.5 mol/LH2SO4 solution. The structures and micro-surface images of the catalysts were determined and observed by X-ray diffraction and
transmission electron microscopy, respectively. The catalyst prepared in inert gases showed a better catalytic performance
for methanol electrooxidation than that prepared in air. It resulted in a more homogeneous distribution of the Pt-Ru alloy
in carbon. Its size is small, only about 4.5 nm. The catalytic performance is affected by the order of the reducing agent
added. The performance of the catalyst prepared by adding the reductant at constant temperature of the solution is better
than that prepared by adding it in the solution at 0°C and then heating it up to the reducing temperature. The structure of
the catalyst was modified, and there was an increase in the conversion of ruthenium into the alloyed state and an increase
in particle size with the ascension of heat treatment temperature. In addition, the stability of the catalyst was improved
after heat treatment.
Translated from Journal of Harbin Institute of Technology, 2006, 38 (4): 541-545 [译自: 哈尔滨工业大学学报] 相似文献