Abstract
Mechanical reliabilities of membrane electrode assemblies (MEA) in polymer electrolyte fuel cells (PEFCs) are a major concern to fuel cell application. Hygro-thermal cyclic conditions induce the mechanical stress in MEA and cracks are formed under operating conditions. The purpose of this paper is to understand the fatigue properties of MEA under several mechanical and environmental conditions for the critical design of durable PEFCs. We carried out fatigue tests for MEA both in room condition and in a test chamber in which temperature and humidity were controlled. The surface crack formation of MEA was observed by a video micro scope during the fatigue tests and the number of cycles to crack formation was measured. The results revealed that the fatigue strength of MEA was shorter under higher temperature and higher humidity condition. Moreover, ionic conductivity of MEA was affected by mechanical fatigue damage and it may result in the power loss of fuel cells. Therefore, the design of crack prevention in MEA is important.
