Research on the long-term stability of a PEMFC stack: Analysis of pinhole evolution

In this paper, the structure of a two-cell PEM fuel cell stack is introduced. Results of a long-term stability test are presented. Pinholes are considered to be formed and grow up after the 357th hour because four oscillation stages are found in the temperature profile of each bipolar plate. Based on the data of Pinhole Growth Region, and considering the growth of a pinhole and water droplets formation and their growth and movement, four models are proposed to give reasonable explanations for the pinhole evolution during these four stages. The analysis shows that the pinhole growth increases the amplitude of the temperature oscillation of each bipolar plate. The pressure difference between the anode and the cathode is a key factor to cause deadly destruction to a membrane. The stack is broken after the 647.15th hour because the pinhole is considered to be huge. The dimensionless hydrogen concentration of the cathode exhaust and the temperature of each bipolar plate are closely related, which is a good support for the models. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.