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The Xergy Xion AEM-Dappion-20 membrane is a composite anion exchange membrane (AEM) that uses the Dappion Gen1 resin (3-D polyphenylene) as the polymer backbone with a benzyl trimethyl ammonium side chain as its functional group and has an ion exchange capacity of 2.1 - 2.5 mequiv/g. Dappion Gen1 membranes offer excellent mechanical strength and stability to a wide variety of chemistries. Xergy currently produces Dappion Gen1 anion exchange membrane sheets in 5, 10, 20, and 30µm thicknesses and 5x5cm, 10x10cm and 15x15cm sizes. Image on the right side shows the chemical composition of the anion exchange resin used to manufacture Xion Composite Dappion Gen1 membranes.
The Xion AEM-Dappion-20 is a 20 micrometers thick anion exchange membrane and it can be used in fuel cells, electrolyzers, electrodialysis, redox flow batteries, electrochemical compressors, and a wide variety of other devices.
XION Composite Dappion Gen1 AEMs are ultra-thin, ultra-strong, provide ultra-high performance for various alkaline chemistry based applications. The ionomer structure contains a 3-D polyphenylene backbone with a benzyl trimethyl ammonium side chain for its functional groups. A reinforcement layer is integrated into the structure of the membrane to provide enhanced mechanical properties and this is composed of microporous ePTFE (also known as expanded PTFE). The enhanced mechanical properties as free-standing membranes, providing higher ionic conductance without sacrificing strength.
-High anionic conductivity
-Great chemical stability at low and high temperatures
-Ultra-thin membranes with excellent mechanical strength
The membrane is delivered in dry form with the counter anion being either in bromide or chloride. Depending on application and cell design, assembling is possible in dry form (without pretreatment) or wet form.
For standard alkaline fuel cell / electrolysis applications, the membrane should be converted into OH-form by treating it with 0.5 – 1.0 M NaOH or KOH solution: Put the membrane sample in an aqueous solution of 0.5 – 1.0 M NaOH or KOH for at least 24 h at 20°C – 30°C. After rinsing with demineralised water (pH ~ 7) the membrane is ready to use. Use closed container to avoid CO2 contamination (carbonate formation that may affect conductivity). The membrane in OH-form must be stored under wet / humidified and CO2-free conditions, avoid drying out of the membrane in OH-form. Long-term storage in dry conditions should be preferably done in carbonate, Cl- or Br-form.
For electrochemical CO2 reduction applications, the anion exchange membrane should be converted to the carbonate or bicarbonate form by treating the membrane initially with 0.1 to 0.5 M KOH or NaOH solution and then with 0.1 to 0.5 M water soluble carbonate or bicarbonate salt solutions (such as potassium carbonate or potassium bicarbonate that is dissolved in de-ionized water or distilled water). Fully submerging the anion exchange membrane into KOH or NaOH solution for 6 to 12 hours and then to the desired carbonate or bicarbonate salt solution for a period of 48-72 hours would be sufficient to fully convert the membrane into either carbonate or bicarbonate form. After rinsing the membrane (which is in the carbonate form) with deionized water or distilled water, it can be assembled inside the electrochemical setup for electrochemical CO2 reduction experiments. While the submersion of the membrane into the KOH or NaOH can be skipped, for such situations, a longer submersion time may be required in order to fully convert the membrane to carbonate or bicarbonate form. Initial conversion to OH- form significantly improves the carbonate ion exchange process due to expanded pore sizes.
For other electrochemical (electrodialysis, desalination, electro-electrodialysis, reverse electrodialysis, acid recovery, salt splitting, etc.) and non-electrochemical applications, the membrane should be converted into the anionic form that is relevant for the intended application. For example, if the application is requiring the Cl- anions to be transferred through the membrane, then this anion exchange membrane needs to be converted into the Cl- form. In order to convert this membrane into Cl- form, it needs to be submerged into a 1-2 M salt solution of NaCl or KCl (dissolved in deionized water) for a period of 24-72 hours and then rinsed with deionized water to remove the excess salt from the membrane surface. Or if the intended application is requiring to transfer sulfate anions, then this anion exchange membrane needs to be converted into the sulfate form prior to its assembly into the cell. A neutral salt solution of Na2SO4 or K2SO4 would usually be sufficient to achieve the full conversion of membrane into the sulfate form after fully submerging the membrane into the salt solution for 24-72 hours at room temperature.
If you have any concerns about storage, chemical stability, pre-treatment or before proceeding, please feel free to contact us for further information.
The article by Hibbs et al. entitled "Synthesis and Characterization of Poly(Phenylene)-Based Anion Exchange Membranes for Alkaline Fuel Cells" is an excellent article that details out the advantage of 3-D poly(phenylene) based backbones and their suitability for alkaline fuel cell and other applications including various synthesis pathways for manufacturing different compositions.
The article by Kim et al. entitled "Resonance Stabilized Perfluorinated Ionomers for Alkaline Membrane Fuel Cells" is an excellent article that details out the advantage of 3-D poly(phenylene) based backbones and their suitability for alkaline fuel cell and other applications including actual alkaline fuel cell performance at a temperature of 80 °C with H2/O2 reactants.
The article by Choe et al. entitled "Alkaline Stability of Benzyl Trimethyl Ammonium Functionalized Polyaromatics: A Computational and Experimental Study" is an excellent article that investigates the stability of benzyl trimethyl ammonium as the functional group with 3-D poly(phenylene) based backbone both theoretically and experimentally and then suitability of such anion exchange membranes for alkaline electrochemical devices.
The article by Michael Hibbs entitled "Alkaline Stability of Poly(phenylene)-Based Anion Exchange Membranes with Various Cations" is an excellent article that investigates the stability of benzyl trimethyl ammonium and several other functional groups as the ion conducting entities with 3-D poly(phenylene) based backbone and demosntrates the advantages of the 3-D poly(phenylene) with benzyl trimethyl ammonium compared to other cationic groups.
A typical lead time of 2-3 weeks is to be expected.
|Membrane Thickness||20 micrometers|
|Polymer Type||3-D Polyphenylene based backbone|
|Functional Group||Benzyl Trimethyl Ammonium based functional groups|
|Counter ion||Halide (Br- or Cl-)|
|Mechanical Reinforcement||Yes, ePTFE (also known as expanded PTFE) is the mechanical reinforcement substrate|
|Ion Exchange Capacity||2.1 - 2.5 meq/g|
|pH range||1 - 14. With alkaline electrolytes, concentrations greater than 1 - 1.5M should not be used with this membrane.|
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