固体高分子形燃料電池のフラツデイングにおよぼす触媒層とガス拡散層の劣化の影響

摘要

固体高分子形燃料電池（PEFC）に使用される固体高分子rn電解質膜（PEM）は，高含水状態において高いプロトン伝rn導性を示す。したがって，高いセル性能を得るためには，燃rn料および酸化剤を十分に加湿して供給するとともに，触媒rn層（CL）で発電によって生成された水をCLとガス拡散層rn（GDL）との間に設けた水管理多孔層（WML）によってセrnル内部に保持するなどしてPEMを高含水状態に保持rnした運転が必要となる。%Regarding a polymer electrolyte fuel cell (PEFC), the influence of degradations of a catalyst layer and a gas diffusion layer which are parts of membrane electrode assembly (MEA) on electrode flooding was investigated. On a PEFC, high humidity operation is desired for high performance because it is necessary to contain much water in proton exchange membrane and ionomer at catalyst layer. Additionally, high gas utilization is required for high system efficiency. However, under these conditions, significant degradation in a cell performance is caused by water-flooding of electrodes. The purpose of this study is to investigate how the degradation of a catalyst layer and a gas diffusion layer give the influence to occur flooding on electrode. The single cell was generated at 0.3 A/cm~2 under high humidity operation for 10000 hours. And the cell performance was evaluated as cell voltage, cell resistance, IV curves, gas crossover rate, electrochemical surface area and Oxygen gain in order to find which part of the cell dominates such cell degradation. Consequently, it is found that the gas diffusivity degradation finally dominates the decay of the cell performance and it is mainly caused not in the gas diffusion layer but in the catalyst layer.