Simultaneous Measurement of Proton Conductivity and Methanol Permeability for the Development of Direct Methanol Fuel Cell Membranes

Abstract

DMFC membrane development is complicated by the fact that the two most important transport properties, methanol crossover and proton conductivity, are coupled, thus strategies that improve one property will almost invariably have an undesirable effect upon the other. Each measurement is usually done in separate experiments, even under different conditions. These measurements can be carried out in fuel cells and are indeed simultaneous, however, many complicating factors can interfere with the derived properties. This paper presents a methodology for the simultaneous measurement of membrane conductivity and methanol permeability. The equipment and method will be presented, and examples discussed including a comparison to analogous in-fuel cell results as well as examination of a series of experimental DMFC membranes. Further, a graphical means of viewing transport results as well as the derived benefits in rapid analysis and comparison of candidate membranes will be presented.