A Method for Improving Ionic Conductivity of Nafion Membranes and its Application to PEMFC

In this paper, we show that proton conductivity and PEMFC performance of Nafion membranes prepared by solutions casting can be improved by aligning the side cahin ionic aggregations along the membrane thickness direction using an electric field. The nano-structures of Nafion membranes prepared by solutions casting with applying an electric field were investigated using transmission electron microscopy (TEM), which clearly shows fibril-like structures of Nafion molecular aggregations aligned along the electric field. The alignment of ionic aggregations along the membrane thickness direction causes linear and less curved proton transferring pathways across the membrane cross section and thus a higher proton conductivity and a better PEMFC performance.