Abstract
Sufficient water content within a polymer electrolyte membrane
(PEM) is necessary for adequate ionic conductivity. Membrane
hydration is therefore a fundamental requirement for fuel cell
operation. The hydration state of the membrane affects the water
transport within, as both the diffusion coefficient and electroosmotic
drag depend on the water content. Membrane’s water
uptake is conventionally measured ex situ by weighing freeswelling
samples equilibrated at controlled water activity. In the
present study, water profiles in Nafion® membranes were
measured using high-resolution neutron imaging. The state-of-theart,
13 μm resolution neutron detector is capable of resolving water
distributions across N1120, N1110 and N117 membranes. It
provides a means to measure the water uptake and transport
properties of fuel cell membranes in situ.