Direct dimethyl-ether fuel cell

近年来，聚合物电解质燃料电池（PEFC）的直接甲醇燃料电池（DMFC）作为小型便携式电源受到了广泛的关注。DMFC的一个缺点是甲醇通过聚合物电解质膜（PEM）的渗透性太大，这会降低燃料效率和电池性能。1998年，我们展示了第一个直接二甲醚燃料电池（DDFC），其性能几乎与DMFC相当。本文研究了DDFC的渗透特性及其相关现象，并与DMFC进行了比较。在相对湿度为95%的条件下，在60 ~ 80℃的温度范围内，二甲醚通过PEM的渗透系数约为甲醇的十分之一。使用DDFC的燃油交叉泄漏量约为DMFC的十分之一。在DDFC上观察到的现象与在DMFC上观察到的现象相同。它们分别是燃料扩散渗透、电渗透渗透和阳极催化剂层燃料消耗导致的渗透降低。ddfc可获得90%以上的法拉第系数。二甲醚在水中的溶解度在20℃时为5.3% wt%，在80℃时为0.83 wt%。当在阳极上使用Pt-Ru催化剂时，DDFC的性能异常低下。研究了DDFC的分解种类和催化剂上CO的吸附量，但这种异常现象的原因尚不清楚。

Recently, a direct methanol fuel cell (DMFC) using polymer electrolyte fuel cell (PEFC) has received much attention for small portable power sources. A drawback of the DMFC is too much permeation of methanol through a polymer electrolyte membrane (PEM) which reduces fuel efficiency and the cell performance. In 1998, we demonstrated the first direct DME (dimethyl-ether) fuel cell (DDFC), the performance of which was almost equal to that of the DMFC. The permeation properties of the DDFC and their related phenomena are studied and compared with those of DMFC in this report.1. The permeability coefficient of DME through a PEM was about one-tenth as small as that of methanol within temperature range from 60 to 80 ℃ under relative humidity of 95%.2. The fuel cross leak of operating DDFC was about one-tenth as small as that of operating DMFC. The same phenomena were observed on the DDFC as were observed on the DMFC. They were fuel permeation by diffusion, electro-osmotic permeation, and decrease of permeation due to fuel consumption in the anode catalyst layer. Farady coefficient of more than 90% was attained by DDFC.3. DME solubility in water is 5.3wt% at 20℃ and O.83wt% at 80℃4. When Pt-Ru catalyst is used on the anode, abnormal low performance of the DDFC is observed. Decomposition species from the DDFC and absorbed CO quantity on the catalyst are examined, but the origin of this abnormal phenomenon is still unknown.