Surface Analytical Methods for the Development of Electrochemical Components of Polymer Electrolyte Fuel Cells

Abstract

The transition from fossil to renewable energies implies significant changes in the energy system regarding the distribution, storage and energy conversion due to the intrinsic natural fluctuations of renewable power sources. Polymer electrolyte fuel cells (PEFC) are highly efficient electrochemical energy converters that may be implemented in a wide range of power and dynamics. Their high gravimetric energy density makes them attractive for many applications, especially for mobile purposes. In particular they are a key to hydrogen fuelled electric cars. However, the durability of fuel cells is still an important issue. The understanding of the occurring degradation mechanisms is a crucial step in the development of sustainable fuel cells with long operational times. Surface analytical methods provide insight into the surface chemistry of PEFCs and allow the studying of degradation products and mechanisms. The combination of methods gives complementary information about the investigated fuel cell components. X-ray photoemission spectroscopy (XPS) yields information about elements and binding states. Infrared and Raman spectromicro-scopy in combination with scanning and/or imaging techniques allows a fast investigation of larger sample areas. Due to roughness and reflectivity issues the use of diffuse reflection or attenuated total reflection in direct contact (ATR) need to be pondered. An overview of the applied surface analysis methods and their advantages and difficulties is presented.