Membrane Durability and Degradation under Dry Fuel Cell Operation Conditions

Abstract

Membranes are a critical component of the fuel cell stack and must be durable in a wide range of operating conditions. In the present study, PFSA membranes were evaluated using accelerated stress testing (AST) methods of OCV and cyclic OCV under dry conditions at 95 {degree sign}C. PFSA membrane degradation rates were determined by measuring fluorine release rate (FRR) and thickness change under different fuel cell operating conditions. The FRR was found to increase with a decrease in inlet relative humidity (RH) and an increase in stack temperature. The degradation active energy (derived from the Arrherius equation) was approximately 932.8 JK-1mol-1. A cyclic OCV test was designed to simulate membrane degradation caused by both mechanical and chemical stresses. Mechanically reinforced membranes showed much longer lifetime in the COCV test as compared to membranes without reinforcement. Under present operating conditions, membrane degradation is shown to initiate from cathode side.