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Accurate measurement of the through-plane water content of proton-exchange membranes using neutron radiography

Published

Author(s)

Daniel S. Hussey, David L. Jacobson, Dusan Spernjak, Adam Weber, Rangachary Mukundan, Joseph Fairweather, Eric Brosha, John Davey, Jacob Spendelow, Rodney Borup

Abstract

The water sorption of proton-exchange membranes (PEMs) was measured in situ using high-resolution neutron imaging in small-scale fuel-cell test sections. A detailed characterization of the measurement uncertainties and corrections associated with the technique is presented. The developed image-processing procedure resolved a previously reported discrepancy between the measured and predicted membrane water content. With high-resolution neutron-imaging detectors, the water distributions across N1140 and N117 Nafion membranes are resolved in vapor-sorption experiments and during fuel-cell and hydrogen-pump operation. The measured in situ water content of a restricted membrane at 80 °C is shown to agree with ex situ gravimetric measurements of free-swelling membranes over a water activity range of 0.5 to 1.0 including at liquid equilibration. Schroeder's paradox was verified by in situ water-content measurements which go from a high value at supersaturated or liquid conditions to a lower one with fully saturated vapor. At open circuit and during fuel-cell operation, the measured water content indicates that the membrane is operating between the vapor- and liquid-equilibrated states.
Citation
Journal of Physical Chemistry B

Keywords

nafion, neutron radiography, proton exchange membrane fuel cell, Schroeder's paradox, water sorption

Citation

, D. , , D. , Spernjak, D. , Weber, A. , Mukundan, R. , Fairweather, J. , Brosha, E. , Davey, J. , Spendelow, J. and Borup, R. (2021), Accurate measurement of the through-plane water content of proton-exchange membranes using neutron radiography, Journal of Physical Chemistry B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=911111 (Accessed September 20, 2021)
Created April 21, 2021, Updated May 3, 2021