Fuel Cells vs Electrolysers
Although fuel cells and electrolysers both use PEM-style MEAs, their operating environments differ, and so do some material choices.
1. Membrane (PEM):
- Conducts protons
- Separates hydrogen and oxygen environments
- Must remain properly hydrated to maintain conductivity
2. Catalyst layers:
- Fuel cells often use platinum-based catalysts (especially at the cathode for oxygen reduction)
- Electrolysers use catalysts suited to oxygen evolution and hydrogen evolution reactions (often including iridium/ruthenium oxides for the oxygen side)
3. Porous transport layers (PTL/GDL):
- Provide pathways for gas/water transport
- Conduct electrons and help distribute reactants
- Influence flooding, drying, and mass transport losses
4. Microporous layers / interfaces:
- Improve water distribution and contact
- Reduce local hotspots and uneven reaction regions
Why compression and contact matter
The MEA operates within a stack under compression. Too little compression increases contact resistance and leaks; too much can crush layers and reduce permeability.