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Publication
MEA degradation and failure modes in PEM fuel cells
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Advisor(s)
Abstract(s)
The mechanisms of fuel cell degradation are not well understood. Even though the numbers of installed units
around the world continue to increase and dominate the pre-markets, the present lifetime requirements for
fuel cells cannot be guarantee, creating the need for a more comprehensive knowledge of material’s ageing
mechanism.
In this work, failure modes and mechanism of the membrane-electrode assembly (MEA) in PEM fuel cells are
studied stressing the issues that may constrain stability, power and lifetime.
Diagnostics methods and tools used for in-situ and ex-situ analysis of PEM fuel cells were used in order to
better categorize irreversible changes in the kinetic and/or transport properties of the cell.
Data for MEA degradation obtained during and after fuel cell ageing in extreme testing conditions will be
discussed. Electrochemical Impedance Spectroscopy (EIS) is found instrumental in the identification of fuel
cell flooding conditions and membrane dehydration associated to mass transport limitations / reactant
starvation and protonic conductivity decrease, respectively. Cross sections of the membrane catalyst and gas
diffusion layers examined by scanning electron microscopy indicate electrode thickness reduction as a result
of ageing. Catalyst particles are found to migrate outwards and located on carbon backings. Nafion
degradation in fuel cell environment is analysed in terms of the mechanism for fluoride release which is
considered an early predictor of membrane degradation. The application of a full range of diagnostic
techniques and modelling is felt necessary in order to aid design and operating strategies in PEM fuel cells.
Description
In: Proceedings HYPOTHESIS VIII- Hydrogen Systems and Materials for Sustainability, HYP_45, Lisbon, 1-3 April 2009, 5p.
Keywords
PEM Durability Reliability Ageing mechanism Fuel cells
Citation
Silva, R.A.; Paiva, T.I.; Rangel, C. M. Mea degradation and failure modes in PME fuel cells. In: Proceedings HYPOTHESIS VIII- Hydrogen Systems and Materials for Sustainability, HYP_45, Lisbon, 1-3 April 2009, 5p.