Electrocatalyst Stability under Dynamic and Stationary Operation of Polymer Electrolyte Fuel Cells

Abstract

Durability and cost are two barriers recognized for the extensive application of proton exchange membrane (PEM) fuel cell as a promising clean energy technology. To date, considerable effort has been made to study the performance and component degradation via diverse methods and for accelerated degradation, routines have been developed. For instance, operation at open circuit voltage (OCV) is one of the most frequently employed high potential stressors for a PEM fuel cells leading to Pt electrocatalyst dissolution and membrane decomposition. Single cells as well as short stacks were aged under different operation conditions which are discussed in the literature to accelerate degradation of electrocatalyst and membranes. Numerous in-situ and ex-situ analysis is applied to understand the importance of different degradation mechanisms. A general conclusion from these measurement is that Pt dissolution plays an important – perhaps even the crucial – role for the loss of electrochemical surface area and membrane decomposition. To demonstrate this aspect, membranes were first impregnated with Pt ions which were reduced and the fluoride emission rate was measured.