'High-resolution Atomic Force Microscopy Analysis of Conductivity and Mechanical Properties of PEM Membranes'

摘要

Different fuel cell membranes were characterized under current flow using advanced tapping mode atomic force microscopy (AFM) techniques. The distribution of conductive area as well as their mechanical properties under current flow at the nanometer scale was analyzed for Nafion~R, Aquivion~R, and aromatic membranes. The comparison of membrane samples before (as received sample) and after current flow through the membrane revealed changes of the surface structure that were induced by the water flow accompanied with the proton current. A correlation of conductivity with other mechanical properties, such as adhesion force, deformation and stiffness, which were simultaneously measured with the current, provided an indication of subsurface phase separations and phase size and distribution at the surface of the membrane. The distribution of conductive pores at the surface was identified by the formation of water droplets. A comparison of the different membrane types according to the conductive nanostructure was performed and available nanostructure models with high-resolution current images are discussed.