membrane electrode assemblies - MEA) whose durability represented barriers for widespread commercialization of hydrogen fuel cell technology. This in-depth investigation will focused on critical fuel cell components (e.g.
#Cm2 ast download update#
UTC will led a top-tier team of industry and national laboratory participants to update and improve DOE’s Accelerated Stress Tests (AST’s) for hydrogen fuel cells.
It is inferred that during the OCV RHC AST, the decay of the membrane’s mechanical properties is accelerated such that materials can be evaluated in hundreds, instead of thousands, of hours, while replicating the degradation and failure modes of field operation associated AST protocols are recommended as OCV RHC at 90☌ for 500 hours with wet/dry cycle durations of 30s/45s and 2m/2m for automotive and bus operation, respectively. Conversely, steady-state OCV tests result in significant ionomer morphology changes and global thinning, which do not replicate field degradation and failure modes. While RHC in air also reproduces these failure modes, it is not aggressive enough to more » differentiate between different membrane types in >1,333 hours (55 days) of testing. Changes to membrane thickness, hydrophilic domain spacing, and crystallinity were observed to be most similar between field-operated cells and OCV RHC ASTs, where local thinning and divot-type defects are the primary failure modes.
Membrane degradation and failure were investigated using scanning electron microscopy and small- and wide-angle X-ray scattering.
A combined chemical/mechanical accelerated stress test (AST) was developed for proton exchange membrane (PEM) fuel cells based on relative humidity cycling (RHC) between dry and saturated gases at open circuit voltage (OCV).
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