Degradation Study of MEA for PEMFC under Low Humidity Conditions

Research Center, Asahi Glass Co., Ltd. 1150 Hazawacho, Kanagawaku, Yokohama, JAPAN Introduction In the development of the Proton Exchange Membrane Fuel Cells (PEMFC), durability of the membrane electrode assembly (MEA) is one of the vital issues. Recently, it was reported that the degradation of the MEA occurred under low humidity conditions, whereas no obvious degradation was observed under high humidity conditions. 2 In order to develop durable MEAs, it is inevitably important to understand the degradation mechanism of the MEA. It is commonly believed that chemical degradation of the ion exchange ionomer proceeds via peroxide radical attack. However, there has been no direct evidence of radical formation in the MEA. We have conducted an ESR study of the degenerated MEA and confirmed the formation of radicals in the catalyst layers. We have also confirmed the formation of H2O2 on the Pt electrode. In this paper, we will report the results of these studies.