阳极支撑层憎水性对被动式直接甲醇燃料电池传质性能的影响

通过测定甲醇渗透率，详细研究了阳极支撑层的聚四氟乙烯（PTFE）含量对全被动式直接甲醇燃料电池（DMFC）甲醇传质和电池性能的影响。 膜电极集合体均使用相同的阳极催化层，膜和阴极。 实验结果表明，随着阳极支撑层PTFE含量的提高，甲醇渗透速率明显减小。 其含量较高时，甲醇传质阻力较大，会导致电池在很低的电流密度下就出现传质控制区。 采用PTFE质量分数为40%的支撑层时，DMFC以9 mol/L甲醇为燃料最大功率密度可达32×10-3 W/cm2,也进一步证明了适当提高阳极支撑层的憎水性，既有助于减少甲醇的渗透，又缓解了阴极的“水淹”问题。

Effect of Hydrophobicity of Anodic Backing Layer on Mass Transfer Characteristics of Passive DMFCs

The effect of the anode backing layer consisting of carbon papers with different polytetrafluoroethylene(PTFE) contents on the methanol mass transfer and cell performance of a passive direct methanol fuel cell(DMFC) was investigated by methanol permeability measurement. The membrane electrode assemblies(MEAs) were fabricated with the same anode catalyst layer, membrane and cathode. The experimental results showed that the methanol permeability decreased with the increase of PTFE contents in anode backing layer. It was found that PTFE-treated backing layer results in a lower limiting current density, which could be attributed primarily to the increased mass transfer resistance. When the PTFE content in the anode backing layer is up to 40%, the maximum power density of passive DMFC feeding with 9 mol/L methanol solution can achieve 32×10-3 W/cm2. Moreover, the use of a PTFE-treated backing layer also can decrease water transfer from the anode to the cathode, thus mitigating water flooding problem in the cathode.