Nafion membranes come in many different thickness and types. How do you know which to choose when designing an electrolyzer (hydrogen generator)?
Choosing the proper thickness depends primarily on the differential pressure you expect across the membrane (i.e. what pressure you will be generating the hydrogen at vs. the oxygen), the type of support the membrane will have, and the operating lifetime (both hours and on/off cycles).
Our Standard Choice:
- Thin enough for high-efficiency (thinner is less resistive & therefore produces hydrogen at a lower voltage)
- Thick enough to handle 50+ psi differential pressure (depending on the support design)
- Thick enough to decrease cross-over (H2 diffusing through the membrane from the H2 side to the O2 side)
- Thick enough to have bulk that will yield good long-term stability of the membrane
When would you use a thinner membrane?
When the best efficiency is required and there won't be much differential pressure across the membrane. We have made membranes using Nafion 212 (0.002" thick), Nafion 211 (0.001") and Nafion XL (~0.001"; chemically reinforced) that have all been shown to be exceptionally efficient.
What about thicker membranes?
Thicker membranes and fiber reinforced membranes are more appropriate for very high differential pressure applications (1000+ psi) or very long operating life (100,000+ hrs).
Some of these factors can also be mitigated with good mechanical design of the electrolyzer cell, good catalyst configurations, etc.
If you have any questions about what might be the best membrane for your hydrogen generation application, feel free to leave a comment or email us at AskUs@FuelCellsEtc.com