Reinforced Cation-Exchange Membrane (Gore, M series) for Flow Battery, Electrolyzer and Fuel Cell, CFBEFCRCEMG

W. L. Gore & Associates is a pioneer in reinforced cation exchange membranes (CEMs), specifically their GORE-SELECT® product line. While "Nafion" is often the household name for these materials, Gore revolutionized the field by introducing ePTFE (expanded polytetrafluoroethylene) reinforcement, which allows for much thinner membranes without sacrificing mechanical strength.

Traditional CEMs (like standard Nafion 117) are thick, homogenous sheets of ionomer. Gore’s approach uses a "scaffold" technique: (1) The Reinforcement: A microporous ePTFE skeleton provides high mechanical strength and dimensional stability. (2) The Ionomer: High-conductivity perfluorosulfonic acid (PFSA) fills the pores of the skeleton. The ultrathin membrane thickness as low as 5–15um significantly reduces ohmic resistance, leading to much higher power densities. 

Gore is the market leader for automotive fuel cell membranes. (1) Automotive/Heavy Duty: The M775.15 and M765.08 series are optimized for passenger and commercial vehicles. They handle the rapid "wet-dry" cycling of automotive use better than non-reinforced membranes, which tend to crack under the mechanical stress of swelling and shrinking. (2) Dry Performance: Their thinness allows for better back-diffusion of water from the cathode to the anode, enabling the fuel cell to operate at lower relative humidity (RH) levels.

Gore recently expanded its focus to large-scale hydrogen production with the GORE® PEM for Water Electrolysis. (1) Efficiency: By reducing membrane thickness while maintaining gas crossover safety (keeping H2 out of the O2 stream), these membranes can improve voltage efficiency by roughly 5% over thicker industry standards. (3) Intermittent Loading: Designed to handle the fluctuating power input from renewable sources (wind/solar) without mechanical failure.

Use Note:

(1) Selected Critias based on application conditions: 

• If you need max efficiency/compactness: Choose M765.08.

  If you are building a standard automotive stack: Choose M788.12.

  If you need 20,000+ hours of operation: Choose M820.15 or M735.18.

(2) No chemical pre-teatment is needed. 

(3) These membranes (especially M765.08) are essentially "gossamer thin," handling is the most critical part of the "treatment."

• Backer Removal: Gore membranes often come with a protective polymer backer (usually PET or PEN).

  • Do not remove the backer until the last possible second.

  • If you are direct-coating catalyst ink (Slot-die or Spray), the backer provides the necessary tension to keep the membrane flat.

• Static Control: These films are highly prone to static electricity, which attracts dust. Use ionizing air blowers in your assembly area to keep the surface pristine.

• Tensioning: When moving a membrane like the M788.12 into a coating frame, it must be held under uniform tension. If the membrane is "loose," the solvent in your catalyst ink will cause localized swelling, leading to "mud-cracking" in your catalyst layer.

(4) For Gore membranes, the primary "treatment" happens inside the cell after assembly. This is known as the Break-in or Activation Protocol. (1) Initial Hydration: Once the stack is assembled, it is operated at high humidity (100 %RH) and low current to fully hydrate the ionomer channels within the ePTFE scaffold. (2) Voltage Cycling: Most protocols for M765 and M788 involve cycling the voltage between 0.6V and 0.9V. This "pumps" water through the membrane, ensuring all sulfonic acid sites are connected by a continuous water network. (3) Timeframe: Modern GORE-SELECT® membranes are designed for "Rapid Conditioning," often reaching 95% of their peak performance within 2–4 hours of operation, compared to 24+ hours for older technologies.