Modelling and experimental studies on a direct methanol fuel cell working under low methanol crossover and high methanol concentrations
Modelling and experimental studies on a direct methanol fuel cell working under low methanol crossover and high methanol concentrations
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DOI：
10.1016/j.ijhydene.2009.05.114
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发表时间：
2009-08
影响因子：
7.2
通讯作者：
V. Oliveira;C. M. Rangel;A. Pinto
中科院分区：
文献类型：
--
作者：
V. Oliveira;C. M. Rangel;A. Pinto
在 DMFC 实现商业可行性之前，需要解决许多问题，例如便携式 DMFC 中必须尽量减少甲醇交叉和水交叉。这项工作的主要收获是系统地改变商业 MEA 材料，并检查它们对在接近室温下运行的直接甲醇燃料电池的电池性能的影响。描述了对“内部”开发的 DMFC 性能的详细实验研究，该 DMFC 具有 25cm2 活性膜面积，在接近环境条件下工作。设计并测试了具有不同结构和气体扩散层 (GDL) 组合的定制 MEA（膜电极组件），以便在高甲醇浓度水平下选择最佳工作条件而不牺牲性能。实验极化和功率密度曲线成功地与稳态一维模型的预测进行了比较，该模型解释了耦合热和质量传递，以及同一作者最近开发的 DMFC 中发生的电化学反应。根据预测的跨膜甲醇渗透率解释了阳极气体扩散层介质、膜厚度和 MEA 特性对电池性能的影响。建议使用常见的商业材料构建定制的 MEA，以在高甲醇浓度下操作，实现相对较低的甲醇交叉。使用足够的材料作为气体扩散层（阳极 GDL 处的碳纸和阴极 GDL 处的碳布）可以使用更薄的膜来增强水的反向扩散，这对于在高甲醇浓度下工作至关重要。
A number of issues need to be resolved before DMFC can be commercially viable such as the methanol crossover and water crossover which must be minimised in portable DMFCs. The main gain of this work is to systematically vary commercial MEA materials and check their influence on the cell performance of a direct methanol fuel cell operating at close to room temperature. A detailed experimental study on the performance of an «in-house» developed DMFC with 25cm2of active membrane area, working near the ambient conditions is described. Tailored MEAs (membrane-electrode assemblies), with different structures and combinations of gas diffusion layers (GDLs), were designed and tested in order to select optimal working conditions at high methanol concentration levels without sacrificing performance. The experimental polarization and power density curves were successfully compared with the predictions of a steady state, one-dimensional model accounting for coupled heat and mass transfer, along with the electrochemical reactions occurring in the DMFC recently developed by the same authors. The influence of the anode gas diffusion layer media, the membrane thickness and the MEA properties on the cell performance are explained under the light of the predicted methanol crossover rate across the membrane. A tailored MEA build-up with the common available commercial materials was proposed to achieve relatively low methanol crossover, operating at high methanol concentrations. The use of adequate materials for the gas diffusion layers (carbon paper at the anode GDL and carbon cloth at the cathode GDL) enables the use of thinner membranes enhancing the water back diffusion which is essential to work at high methanol concentrations.