The main difference between Nafion N115 and N117 is nominal thickness: Chemours lists N115 at 127 µm and N117 at 183 µm. Both are chemically stabilized, extrusion-cast, unreinforced perfluorosulfonic acid membranes. Other conditions being comparable, the thinner N115 provides a shorter proton-conduction path, while the thicker N117 provides more membrane thickness between the two electrodes. That trade-off can influence ionic resistance, gas crossover margin, handling, sealing geometry, and the choice of test conditions. Neither grade is automatically better; the correct selection depends on the electrochemical system and its validated operating window.

Nafion N115 vs N117 at a Glance

What the 127 µm and 183 µm Values Mean

The nominal thickness difference is 56 µm. N117 is approximately 1.44 times as thick as N115. This comparison is useful, but nominal dry thickness is not the complete assembled-cell dimension. Hydration, conditioning, catalyst coating, frame design, gasket thickness, surface contact, and compression all affect the final stack-up. A buyer should therefore specify the membrane grade and nominal thickness while separately defining the cell's sealing and compressed-geometry requirements.

How Thickness Affects Ionic Resistance

For membranes with comparable chemistry and hydration, a shorter conduction path can reduce the membrane contribution to area-specific ionic resistance. This is why N115 may be evaluated when voltage efficiency and membrane resistance are high priorities. The thinner grade does not guarantee a better polarization curve: water content, temperature, catalyst-ionomer interfaces, electrode structure, current distribution, and electrical contact can dominate the measured result. Compare N115 and N117 in the same fixture, with the same conditioning, compression, reactant conditions, and test protocol.

How Thickness Affects Crossover and Pressure Margin

A thicker membrane generally creates a longer transport path for unwanted gas crossover, all else being equal. This can make N117 worth evaluating where product-gas separation or differential-pressure margin is important. However, thickness alone is not a safety or durability specification. Defects, pinholes, edge damage, chemical degradation, pressure cycling, water management, and seal design can still control the result. Set an agreed crossover or purity limit and measure it under representative temperature, hydration, pressure, and differential-pressure conditions.

Handling, Coating, and Sealing Considerations

Both N115 and N117 are unreinforced membranes. N117's greater thickness may provide more handling margin during cutting, coating, framing, and assembly, but it should not be described as a reinforced membrane. The grade change also alters the uncompressed layer stack. If N115 is replaced by N117 without reviewing the frame and gaskets, the new geometry may change local compression, electrical contact, edge stress, or sealing. Update the drawing and validate the complete cell rather than treating the two membranes as drop-in substitutes.

Which Applications Commonly Use N115 and N117?

Chemours currently lists energy storage, hydrogen generation, and various electrolytic processes as common uses for both N115 and N117. In a PEM water electrolyzer, the membrane conducts protons from the oxygen-evolving anode side to the hydrogen-producing cathode side while separating product gases and blocking electronic conduction. Membrane selection must therefore be evaluated together with the catalyst-coated membrane, porous transport layers, seals, water quality, current density, pressure, and gas-quality requirements.

For system context, see the H2Gatech PEM water electrolyzer stack range.

N115 and N117 may also appear in laboratory fuel-cell or other electrochemical work, but a buyer should not assume that an older or thicker membrane is the best match for every PEM fuel cell. Chemours' current product table lists the thinner solution-cast NR211 and NR212 among grades commonly used for fuel cells. Compare the available grades against the actual pressure, humidity, crossover, handling, durability, and resistance targets.

For a thinner-membrane comparison, read Nafion NR211 vs NR212: How to Choose a PEM Fuel Cell Membrane.

When to Evaluate N115

·      When a 127 µm extrusion-cast PFSA membrane is specified or already qualified.

·      When reducing the membrane's ionic path is important and crossover can be kept within the agreed limit.

·      When the frame, gasket, coating, and assembly process are designed for the thinner stack-up.

·      When cell testing can verify performance, gas purity, and durability at the intended pressure and duty cycle.

When to Evaluate N117

·      When a 183 µm extrusion-cast PFSA membrane is specified or already qualified.

·      When greater membrane thickness is preferred for crossover, handling, or process margin.

·      When the additional ionic path is acceptable within the efficiency and voltage targets.

·      When the sealing and compression design has been checked for the thicker membrane stack-up.

Buyer Specification Checklist

H2gatech Engineering Note: Do Not Approve a Grade by Thickness Alone

Engineering note: When an RFQ specifies N115 or N117, H2gatech recommends confirming the electrochemical application, active area, differential pressure, operating temperature, catalyst-layer design, frame and gasket stack-up, sample quantity, and validation method before coating or assembly. Record the exact membrane grade and any permitted substitution on the drawing or purchase specification. This prevents an apparently small material change from becoming an uncontrolled change to resistance, crossover, or sealing geometry.

If the membrane will be supplied as a coated or assembled component, use How to Specify a Custom Fuel Cell MEA as an RFQ checklist.

Frequently Asked Questions

What is the thickness of Nafion N115 and N117?

Chemours lists N115 at 127 µm (0.127 mm) and N117 at 183 µm (0.183 mm). N117 is 56 µm thicker, or approximately 44% thicker than N115 based on the nominal values.

Are Nafion N115 and N117 reinforced membranes?

No. Chemours lists both grades in its unreinforced, extrusion-cast membrane group. Greater thickness is not the same as internal reinforcement.

Does N117 always have lower hydrogen crossover?

A thicker intact membrane generally provides a longer crossover path, but actual crossover depends on material condition, hydration, temperature, pressure, differential pressure, defects, chemical aging, and the test method. Verify the required purity or crossover limit in the intended cell.

Can N115 and N117 be substituted without changing the gasket?

Not without review. Their nominal thicknesses differ by 56 µm, so the frame, gasket, land contact, and compression stack-up should be recalculated and validated before substitution.

Can N115 or N117 be used in a PEM fuel cell?

They can be evaluated in compatible electrochemical hardware, but Chemours currently positions their common uses around energy storage, hydrogen generation, and electrolytic processes. For a fuel-cell project, compare them with thinner or reinforced alternatives and validate resistance, crossover, handling, durability, and sealing under the actual operating conditions.

Request a Membrane or CCM Specification Review

H2gatech supports membrane selection, customized catalyst-coated membranes, framed components, and membrane electrode assemblies for PEM electrochemical applications. Send the intended system, membrane grade, drawing, active area, catalyst requirements, operating conditions, pressure, sealing stack-up, sample quantity, and acceptance method. Explore H2gatech membrane electrode assembly solutions or contact H2gatech for a specification review.

Technical References

Chemours - Nafion Sulfonic Membranes
U.S. Department of Energy - Hydrogen Production: Electrolysis
U.S. Department of Energy - Technical Targets for Proton Exchange Membrane Electrolysis

Related H2Gatech Resources

H2Gatech - Membrane Electrode Assembly
H2Gatech - PEM Water Electrolyzer Stack