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- AEMION+™ - AP3-HNN9-00
AEMION+™ - AP3-HNN9-00
- Enabling precious metal free systems
- High conductivity
- Catalyst layer ionomer
Product Description
AP3-HNN9-00 ionomer can be used as a coating as well as a binder. Ink formulations can be prepared to be used in fuel cell catalyst layers. Commonly the Ionomer is being mixed with a suitable alcohol that is then stirred and poured dropwise with an appropriate mass of catalyst powder and water.
Aemion+™ is the updated product line from Ionomr with better chemical stability and durability for electrolysis. It is a breakthrough material that is completely stable in both strongly basic and strongly acidic environments on a continuous basis, enabling a broad range of innovative energy storage chemistries and configurations. The material has a hydrocarbon backbone, which makes it less impactful on the environment than common fluorinated materials. By using advanced stabilization techniques, Aemion™ is able to compete with the most robust of alternatives.
Typical applications can be found in Metal Air, Nickel metal Hydride and Solid state battery chemistries. This highly conductive binder material has an affinity for negatively charged electrode constituents. It is processable in low boiling solvents for use as alkaline/acid stable electrode coating or binder and is highly customizable for optimized electrochemical properties, application size and manufacturing methods.
Technical Specifications
| Chemical Properties | |
| Ion Exchange Capacity (IEC) Ion Exchange Capacity (IEC) Ion-exchange capacity measures the ability of a material to undergo displacement of ions, previously attached into its structure, by oppositely charged ions. It is measured as the quantity of ions that can pass through a specific volume and a common unit is eq/L. In the case of an Ion-exchange polymer, it represents the total of active sites or functional groups responsible for the exchange and is the theoretical maximum amount of ions that we can load. | 1.9 - 2.7 meq/g |
Additional Information
AP3-HNN9-00-X Ionomer Properties
| Ionomer Type | IEC1 (meq/g) | Conductivity Cl− (mS/cm) | Water Uptake2 OH− (%) | Water Uptake2 Cl− (%) |
|---|---|---|---|---|
| AP3-HNN9-00-X | 1.9–2.7 | 4–9 | 20–50 | 10–15 |
- IEC in the hydroxide (OH−) counter-ion form, calculated by NMR. Recommend silver nitrate for measurement by titration.
- Approximate swelling properties when cast into membrane form at 25–50 µm, at 80 °C.
Role of Ion Exchange Polymers in Membrane Electrode Assemblies of Water Electrolyzers and Fuel Cells
The membrane electrode assembly (MEA) is considered the heart of water electrolyzers and fuel cells. It is composed of the gas diffusion layers (or porous transport layers), catalyst layers (CLs), and ion exchange membranes. The MEA contains the sites where electrochemical reactions occur and governs mass transport processes—transferring reactants in and products out, while also conducting electrons from the electrodes to the external circuit.
Water electrolyzer and fuel cell performance is significantly influenced by the properties of GDLs, CLs, and membranes. The electrodes should have high electrical conductivity and porosity, while the CL should exhibit strong catalytic activity. Ideally, MEAs combine these traits while remaining cost-effective. For PEM-based devices, high acidity requires platinum-group catalysts such as Pt/C, which remain costly.
Membrane–Electrode Assembly Fabrication
Balancing cost and performance requires optimization of MEA fabrication. Two major approaches are used: gas diffusion electrode (GDE) coating, where the catalyst layer is deposited on the GDL, and the catalyst-coated membrane (CCM) technique, where the catalyst is directly coated onto the ion exchange membrane through electrostatic spray coating, ultrasonic coating, decal transfer, or screen printing.
The CCM method offers lower interfacial resistance due to shorter diffusion paths and larger contact area. However, direct catalyst deposition can cause cracks in the CL because of catalyst agglomeration and solvent evaporation.
Functions of Ion Exchange Polymers in Catalyst Inks
To improve catalyst utilization, ion exchange polymers (ionomers) are added to catalyst inks. Catalyst inks typically contain catalyst, solvent, and ionomer, and their properties depend heavily on how these interact.
Ionomers adsorb onto catalyst particles, increasing surface charge and electrostatic repulsion, which prevents agglomeration. They also create steric hindrance, helping keep particles dispersed. In addition, ionomers extend ionic conductivity from the membrane into the CL, act as binders maintaining structural and electrical integrity, and retain water to keep the membrane hydrated.
Solvent Compatibility of AP3-HNN9-00
The interaction of the ionomer with the solvent and catalyst determines ink dispersion stability and viscosity. Below are suitable solvents for Aemion+™ AP3-HNN9-00.
| Solvent Type | Comments | Solubility (wt%) |
|---|---|---|
| Ethanol / Acetone | 50:50 (v/v) mixture; recommended low-boiling solvent | 1–7% |
| Methanol / MEK | 50:50 (v/v) mixture | 1–6% |
| NMP, DMF | High-boiling solvents; may affect gas permeability | 1–10% |
We provide ionomers in powder form and offer dissolution guidance so customers can prepare their own solutions. This eliminates the need to ship flammable liquids, reducing cost and safety risks.
Both PEM and AEM ionomers dissolve readily in common low-boiling laboratory solvents.
Solubility of AP3-HNN9-00 in EtOH/Acetone Solution
| EtOH [mass, g] | Acetone [mass, g] | AP3 (7 wt%) Solubility | Approximate Viscosity* [cP] |
|---|---|---|---|
| 9 | 1 | No | – |
| 8 | 2 | No | – |
| 7 | 3 | No | – |
| 6 | 4 | Dissolved | 192 |
| 5 | 5 | Dissolved | 114 |
| 4 | 6 | Dissolved | 90 |
| 3 | 7 | Dissolved | 61 |
*Viscosity calculated by Ionomr internal falling ball viscometer method
Note: Achieving solubility at mid to high wt% range may require appropriate heating and stirring for up to 48 hours. Sonication may speed up this process but is not recommended beyond ~30 minutes in a sonication bath.
Ink Preparation Using Anion Exchange Ionomer Dispersions
The following is a starting point for preparing catalyst inks based on an ink formulation designed for fuel cell catalyst layers. Please note that different ionomer content may be required depending on the application. Similarly, depending on the application and performance requirements, further optimization may be required, such as solvent composition and weight percent of solids in solution.
Calculate the mass of polymer, catalyst, and solvents
Calculate the mass of polymer, catalyst powder, and solvents required for electrode composition. As a guideline, the final ionomer to catalyst ratio should be around 10 to 25 wt%. This is heavily application dependent. Adapting existing ink formulation based on polymers of other densities based on vol% is suggested for an initial approximation. The density of Aemion⁺® is ~1.2 g/mL, so an ink based on 30 wt% of a ~2.0 g/mL polymer would be approximately equivalent to 18 wt% Aemion⁺®.
It is recommended that the solvent ratio is 1:1 organic solvent (or solvent mix) to water (e.g., 1:1 MeOH:water). The primary alcohol can be adjusted after the polymer is dissolved in Step 2. The volume of solvents required should be dictated by a final weight percent of total solids (catalyst powder + ionomer), with 1–2 wt% suggested for electrode application by spray-coating. One method of controlling drying characteristics (e.g., membrane swelling, wrinkled catalyst layers, or porosity) is to alter the alcohol ratio; it is strongly inadvisable to increase this ratio above 3:1.
Prepare a 3–5 wt% ionomer solution
On a stir plate (with magnetic stirring capabilities), prepare a 3–5 wt% solution of Aemion⁺® using a suitable low-boiling alcohol mixture for dissolution (e.g., methanol/MEK). If particulates are noted, pass the ionomer solution through a 0.45 µm filter to remove contaminants. Reserve approximately 5 mL of the alcohol to capture residual polymer during glassware rinsing in a later step.
Disperse catalyst powder and wet fully
Preferably in a narrow-necked glass bottle and on a stir plate capable of magnetic stirring, add the catalyst (e.g., Pt/C powder) followed by a stir bar and all the calculated water. Stir gently (≈ 100 RPM) until the catalyst powder is fully wetted and dispersed. Increase the stir rate until a vortex begins to form but before cavitation (≈ 400–600 RPM, depending on ink volume and stir bar size).
Combine alcohol and ionomer; finish the ink
Slowly pour in the calculated alcohol, apart from the 5 mL reserve and that contained in the ionomer solution. Maintain vigorous stirring and add the alcohol/ionomer solution dropwise, ensuring surface accumulation of polymer is minimized. Occasionally swirl to integrate catalyst particles that accumulate at the ink-bottle interface.
Use the remaining 5 mL of alcohol to rinse the ionomer glassware (to capture any residual polymer so calculated values for ionomer are realized) and dislodge remaining catalyst powder from the bottle sides. Stir at moderate rate (≈ 300 RPM) until use; a minimum of four hours is recommended. A low-power bath sonication for 15–30 minutes after the initial 30–60 minutes of stirring improves ink homogeneity.
Disclaimer: These prototype materials are for early development use only. Product information is for guidance, not a design specification, and may change without notice. Ionomr makes no warranties and assumes no liability for the use of this information.
