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A membrane electrode assembly (MEA) is an assembled stack of proton-exchange membranes (PEM) or alkali anion exchange membrane (AAEM), catalyst and flat plate electrode used in fuel cells and electrolyzers.[1][2]
The PEM is sandwiched between two electrodes which have the catalyst embedded in them. The electrodes are electrically insulated from each other by the PEM. These two electrodes make up the anode and cathode respectively.
The PEM is typically a fluoropolymer (PFSA) proton permeable electrical insulator barrier. Hydrocarbon variants are currently being developed and are expected to succeed fluoropolymers. This barrier allows the transport of the protons from the anode to the cathode through the membrane but forces the electrons to travel around a conductive path to the cathode. The most commonly used Nafion PEMs are Nafion XL, 112, 115, 117, and 1110.
The electrodes are heat pressed onto the PEM. Commonly used materials for these electrodes are carbon cloth or carbon fiber papers.[3] NuVant produces a carbon cloth called ELAT which maximizes gas transport to the PEM as well as moves water vapor away from the PEM. Imbedding ELAT with noble metal catalyst allows this carbon cloth to also act as the electrode. Many other different methods and procedures also exist for the production of MEAs which are quite similar between fuel cells and electrolyzers.[1]
Platinum is one of the most commonly used catalysts, however other platinum group metals are also used. Ruthenium and platinum are often used together, if carbon monoxide (CO) is a product of the electro-chemical reaction as CO poisons the PEM and impacts the efficiency of the fuel cell. Due to the high cost of these and other similar materials, research is being undertaken to develop catalysts that use lower cost materials as the high costs are still a hindering factor in the widespread economical acceptance of fuel cell technology.
Current service life is 7,300 hours under cycling conditions, while at the same time reducing platinum group metal loading to 0.2 mg/cm2.[4]
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At this time most companies manufacturing MEAs specialize solely in high volume production, such as W. L. Gore & Associates, Johnson Matthey, and 3M. However, there are other companies which produce MEAs, allowing different shapes, catalysts or membranes to be evaluated as well, which include Fuel Cell Store, FuelCellsEtc, and many others.
The global market for Membrane Electrode Assemblies (MEA) was estimated to be worth US$ 672 million in 2023 and is forecast to reach US$ 3853 million by 2030, with a CAGR of 28.2% during the forecast period 2024-2030.[5]
By Type
- 5-layer MEA: The 5-layer MEA is the most widely used type due to its balance of performance and cost-effectiveness. It typically consists of an anode, cathode, and two ion exchange membranes. This configuration allows for efficient proton conduction and effective gas diffusion, making it suitable for various applications, including fuel cell vehicles and portable power systems. Research has shown that 5-layer MEAs can provide improved performance under different operating conditions, making them a preferred choice in the industry.
- 7-layer MEA: The 7-layer MEA incorporates additional layers that enhance performance and durability. This design usually includes extra catalyst and membrane layers, which can improve the overall efficiency of the fuel cell. These MEAs are often used in high-performance applications where maximum power output and longevity are critical. Studies indicate that the 7-layer configuration can achieve higher current densities and lower degradation rates compared to simpler designs, making them suitable for demanding environments such as heavy-duty transport and stationary power generation.
- 3-layer MEA: The 3-layer MEA is primarily used in applications where cost reduction is a priority. While this type may not provide the same level of performance as 5-layer or 7-layer configurations, it can still be effective for specific low-power applications. This design typically includes fewer catalyst layers and is more suitable for small-scale devices or applications where weight and cost are significant factors.
By Application
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