Backing Out Diffusion Coefficients in Alkaline Anion Exchange Membranes

• Published in: ECS transactions Vol. 33; no. 1; pp. 1923 - 1933
• Main Authors: Myles, Timothy D., Kiss, Andrew, Grew, Kyle, Peracchio, Aldo, Chiu, Wilson
• Format: Journal Article
• Language: English
• Published: 01.01.2010
• ISSN: 1938-5862; 1938-6737
• DOI: 10.1149/1.3484684

Water diffusion coefficients for electrolyte membranes are a subject of interest due to the relationship between water content and ionic conductivity. These diffusion coefficients are functionally dependent on water content. Many existing techniques for measuring the diffusion coefficient suffer from experimental complexity or a lack the diffusion coefficient's detailed behavior. This paper uses a simple technique for determining the water diffusion coefficient involving the use of experimental data coupled with a numeric model. This back out algorithm was validated through the use of Nafion®, a proton exchange membrane, with the results comparing well with NMR data from the literature. The process has also been applied to SnowPure ExcellionTM, an alkaline exchange membrane, to obtain the diffusion coefficient as a function of water content. It was found that these membranes are much less permeable to water with the diffusion coefficient being almost an order of magnitude less than that of Nafion®.