Flow Battery Research Collective

@kirk said in New ion exchange membrane recipe using water softener resin and PVC cement:

First off, @rowow , thanks for making your membrane approach open-source! Out of curiosity, is the patent application alongside it meant to prevent patent trolls from taking advantage of it?

YES!!! protecting against patent trolls was exactly the point. I didnt want to deal with being in court the next 15 years prohibited from using my own technology arguing whether or not its open sourced. The certain japanese gaming company patenting a certain game mechanic recently is a great example how terrible the patent situation is...

@danielfp248 has looked into membranes quite a bit and I agree that the only way to know for sure about a membrane's chemical compatibility is to test it with the proposed electrolyte during operation, where it will be exposed to, to take our standard zinc-iodide cell as an example, zinc dendrites (which can puncture an IEM) and high concentrations of triiodide, which can be pretty aggressive and "weird", in the sense that it has attacks and goes through many polymers that are otherwise resistant to similar classes of chemicals.

I personally favor ferric chloride so I dont have any experience with zinc iodide. But I hope this membrane will allow the community to also see other membrane ideas in general. A user on my discord server sent the following research paper which discussed using a carbon slurry as a carrier for the metal to plate off. Really interesting study I wonder what you think, very much worth replicating also and may solve the dendrite/plating issue.
https://link.springer.com/article/10.1557/s43581-022-00046-8

It seems you probably have most of the resources already to test your membranes with ZnI? The other thing that would be quite different in terms of membrane requirements for a battery vs. a refining process would be conductivity, I'm not sure if you've done measurements in terms of Ohm*cm² but this would be a harder target to reach for RFB applications.

I dont have any zinc iodine. I can see about fitting it into a test cell to demonstrate but honestly that would be a month out. I am trying to launch a website store right now alongside many other video ideas first to publish. I havent properly measured its conductivity, definetly varies based off solution. I just know that theres a very low voltage drop when electrolyzing across the membrane vs directly in solution at the same distance. Additionally I get 100-200ma/sqcm depending on the fabrication method. When using the proposed ball milling and spray method you can get paper thin sheets. Currently with my mining setup, the electrodes are the limitation not the membranes.

There's a lot I would love to add to this community. I think the way traditional methodology for this technology needs to be reapproached. Firstly, by using my open sourced membrane recipe you can glue it directly into a PVC cell. Secondly, using foam core PVC sheets which are readily available and cheap from cabinet shops like imeca allows for complex flow cell designs to be easily and rapidly produced with a simple CNC router on various sizes. I have a flow cell design already I'll be glad to upload. I'm new here so sorry there's a lot I love to want to share and am doing things one thing at a time.

You can find more details on the membrane on the following GitHub https://github.com/Rowow1/Open-sourced-off-the-shelf-ion-exchange-membrane
However I started a separate thread specifically for this membrane topic.

@kirk said in New member introduction thread!:

This would be great to see! Feel free to start a thread in @general-discussion about your cell design. We had tossed around the idea of 2D-material milling/laser approaches to flow frames, but have stuck with 3D printed designs for now so that we can have internal geometries in the flow frames - 2D would certainly be easier and cheaper to make, but I was hesitant about the increased gasketing required/adhesives for sealing.

The key aspect of using the proposed PVC membrane recipe together with the pvc foam board actually completely eliminates the need for gaskets. You simply glue the membrane in place since its also made from pvc. Overall there's far less labor and requirements, forming a sealed (technically welded) bonded cell for a fraction of the price that 3d printing would cost. The long term goal and my personal next goal is to get into injection molding which of course is the best option.

Ill see about uploading the cell fusion 360 model soon depending on if people even care or not. But the point is the core principle idea of being able to use much cheaper pvc foam board material and mass produce these cells at a much better scale than one layer at a time with 3d printing. I was able to make unique geometries needed for flow cells with my 2d design.

As a comparison, you can buy these foam boards for $60-80 for 1/2" or 3/4" from imeca for a full 4x8ft sheet

@danielfp248 we use solutions ranging from 10-20% hydrochloric acid. There are many polystyrene crosslinked sulfonated resin membranes used in flow cells. I don't understand the immediate resistance.

I recommend trying first before making assumptions. At the end of the day try different resins if it's a concern for you. The potential of these membranes and their low cost/manafacturing method have significant impacts. Is there a better community to discuss this research as I may have entered the wrong place

We use the following cation exchange resins: https://www.amazon.com/dp/B079P7QCJF
So far they last a very long time without issue. We have them operating for months in very harsh mining conditions with Ph0 and oxidizing redox potentials over 1.5v. I have measured a ORP level of 1000mv but thats the maximum my meter can go. The chemicals being made by our continuous mining unit produces a theoretical level of 1.65v. Would love to be able to buy a proper ORP meter and test it for sure.

Regardless our cells run for almost a year without issue, and with really dirty mining solution waste. We havent really experienced any sort of degradation such as fouling etc so we dont know the limits of these membranes, only that they already perform very great. Would love to test on various resins and so forth.

Hello, I recently open sourced a novel ion exchange membrane recipe using a high speed grinder on water softener resin and mixing with PVC cement. They can be produced for less than $1 a square yard with properties similar to other name brand ion exchange membranes. You can find more details on the following GitHub https://github.com/Rowow1/Open-sourced-off-the-shelf-ion-exchange-membrane

The patent in the GitHub describes more details, but I also made the following video where I released the files patent as a CCL1.0 license. I have lots of other ideas I would love to assist this community in but I hope this can demonstrate the significance change in scope of redox flow batteries.

https://youtu.be/c3tNXDlgE2M?si=ru-gOsw0ogBhBex2

Hello, I recently open sourced a novel ion exchange membrane recipe using a high speed grinder on water softener resin and mixing with PVC cement. They can be produced for less than $1 a square yard with properties similar to other name brand ion exchange membranes. You can find more details on the following GitHub https://github.com/Rowow1/Open-sourced-off-the-shelf-ion-exchange-membrane

There's a lot I would love to add to this community. I think the way traditional methodology for this technology needs to be reapproached. Firstly, by using my open sourced membrane recipe you can glue it directly into a PVC cell. Secondly, using foam core PVC sheets which are readily available and cheap from cabinet shops like imeca allows for complex flow cell designs to be easily and rapidly produced with a simple CNC router on various sizes. I have a flow cell design already I'll be glad to upload. I'm new here so sorry there's a lot I love to want to share and am doing things one thing at a time.