Flow Battery Research Collective

This guy made a zinc/iron cell. He put carbon felt in the iron side chamber and some sort of fiber glass in the zinc side to control dendrites. Would have to go through the video again to see. https://www.youtube.com/watch?v=Cp3tvMAlrkE

Did a few cycles at low SOC and then attempted to cycle at 10Ah/L. [image: 1782403366618-c6cbcd66-b4d5-4594-97c7-8266ae815951-image.jpeg] Catholyte (left) anolyte (right) below: [image: 1782406513535-d429c06d-318c-4865-b5a4-8eab115d9f66-image.jpeg] pH of catholyte was 0.24 and anolyte was 4.7. As you can see on second cycle to 10Ah/L the CE dropped from 93% to 83% and then capacity continued to decrease. On disassembly a lot of unreacted passivated iron remained on the anode, likely due to the pH increase. As Fe deposits water activity likely increases, which increases HER, which increases pH and leads to Fe passivation. I am going to run a test adding 1M ZnCl2 to the electrolyte, to see how the additional salinity changes water activity and metal passivation.

@bipolaron @kirk This project in Switzerland is currently building a 2.1 GWh capacity / 1.2 GW output redox-flow battery. Scheduled to go online in 2029, and by their own PR material "the largest in the world". https://www.swissinfo.ch/eng/climate-solutions/switzerland-builds-worlds-most-powerful-redox-flow-battery/91181119

I caught the version on YT, but having the same vid on PT is great.

I'm no chemist, so this may not apply here, but I've been looking at info on different batteries. I looked at Nickel/Iron because of their known long life. One change mention from original Edison design is adding a little Lithium oxide or dioxide ( forget exactly) to the electrolyte To extend the life of the Iron electrode. There was also something about making plates (instead of just using sheets of iron) using iron powder with carbon (for conductivity) and something else which I forget that reduced the production of hydrogen.

Edit: after original post, realized that one connection lead was loose, and the negative pump tubing was blocked/degraded---PTFE liner had detached from the wall and formed some sort of blob inside the tubing, it seems.

The battery looks interesting but has some problems. From what I've read, it tends to use up the water in the electrolyte fairly quick by splitting into hydrogen and oxygen. Also, It's working voltage is ~1.2v but it needs 1.6v (1.65v if added lithium) to take a change? The inverter I'm leaning towards now, GTIL2000, for low cost and simple connection has an input range of 45v-90v. When using a 48v LFoP battery, it only can produce about 1300w. With a 72v, it's around 1700w according post on a solar forum. One of these batteries with enough sells to put the charge voltage just below 90v with give me a battery that only has about 60v when no solar to charge it. That would really cripple the inverter. Here is a few videos of someone messing with this battery making his own electrodes and a gell electrolyte in an effort to improve the battery. https://www.youtube.com/watch?v=NaOzDt83XWY https://www.youtube.com/watch?v=0mYaei0O1sU https://www.youtube.com/watch?v=pjoxC4kwA9I

https://www.youtube.com/watch?v=t09aBKUejSs&list=PLYDTEjzfnaSVHeUiCOX5Z9G7i_AiSifpR&index=10

@idlestate also, some studies of these systems I think point to complexes being formed in solution, that contain both chloride and iodide/iodine, like ICl-, for example. They might show up with some spectroscopic techniques like Raman? So chloride can play more of a role than just supporting electrolyte.

@Methylzero "I heard you like batteries, so I got you a battery for your battery..." Definitely it's backing up a headless Raspberry Pi, a potentiostat, Arduino, and two peristaltic pumps.

I mean stable as in, it hasn't obviously degraded. "Stable" cycling means different things to different people ofc.

It's the same electrolyte formulation as currently in the docs

Also, this reminds me of the OpenAFPM project - they also use FreeCAD and provide a dashboard for people to input custom parameters for a small wind turbine generator, there is some FEM, and then design files are output. There is a video demo here: https://www.openafpm.net/cad-visualization I know a few of the folks behind that project, I'm sure they'd be happy to give input on how to accomplish a similar goal but for flow batteries.