The Study of Water Adsorption and Desorption by a PBI Membrane and Its Impact on H3PO4 Transport

The objective of this study is to aid the development of an understanding of the mechanisms of H(3)PO(4) loss and transport in PolyBenzImidazole (PBI)-type High Temperature Membranes (HTM) fuel cells. The isotherms for adsorption and desorption of water in PBI-type HTM are critical data and reported for the first time here for a commercially available membrane. Depending on their values, this adsorption/desorption could play an important role in the long-term dilution of acid and thereby affect (in the long-term) the transport of this acid and proton flux in the membrane. Inclusion of these data is necessary in the development of a mechanistic model that allows for design of new experiments and prediction of fuel cell performance.