Optimization of Membrane Electrode Assembly in Air-Breathing Direct Methanol Fuel Cell
- 2010年第16卷 
针对空气自呼吸式直接甲醇燃料电池甲醇易渗透和阴极易水淹的特点,通过对催化层催化剂载量、阴极微孔层、阳极微孔层和膜等因素进行调控,对膜电极结构和性能的进行了优化.结果表明,使用高载量催化剂能有效降低甲醇渗透,但载量过高会引起传质阻力.当阳极微孔层PTFE含量为30%(bymass)时,可以有效促进CO2的均一析出,从而降低甲醇浓度梯度,减小甲醇透过.综合考虑甲醇渗透和阴极自返水,经优化后所得MEA在室温时自呼吸工作条件下,比功率密度达到33mW·cm-2,最优甲醇工作浓度为4mol·L-1.The structure and performance of MEA were optimized by tailoring the catalyst layer,cathodic microporous layer ( MPL) ,anodic MPL and membrane,with the considerations of unique characteristics of airbreathing direct methanol fuel cell ( DMFC) such as methanol crossover and cathode flooding. It was found that high catalyst loading could suppress the methanol crossover effectively,but too high catalyst loading can lead to high mass transport resistance. Hydrophobic anodic MPL with 30% ( by mass) PTFE could facilitate the CO2 bubble detachment,which decreased the methanol concentration gradient and suppressed the methanol crossover accordingly. When Nafion 115 was used as membrane,methanol crossover was severe,while Nafion 117 was used, the water in cathode could not be effectively back-flowed to the anode by hydraulic pressure. For considerations of complicated interactions and trades-off between the water and methanol crossover effects,the optimized MEA showed peak power density of 33 mW·cm-2 at ambient conditions,the best working methanol concentration was 4 mol·L-1.