Flow Battery Research Collective

No worries! Good luck and let us know how it goes. Internal leakage is a pretty common issue to have when you're getting your first cells set up and debugged!

@gus said in Following your documentation – feedback & questions: I’ve returned to testing the flow cell and even built a second one to check repeatability. I’m wondering what could cause such a large difference in performance between them. Hey, welcome back! As sepi said, please upload the correct firmware to the MYSTAT as an outdated version was previously present in the repo, also be sure to recalibrate your MYSTAT before cycling again, this is likely the source IMO. It wouldn't be bad to add some sort of calibration reminder/routine into the MYSTAT software... @sepi said in Following your documentation – feedback & questions: Good luck with your further investigations! You might want to rzun your future experiments in a transparent PP box in the future. I will for sure once I'm ready for actual electrolyte. Definitely a good idea! @gus said in Following your documentation – feedback & questions: The next day, when I returned to the workshop, both tubes from the pumps had detached from the cell, and the electrolyte had spilled on the table. Do you have any idea what might have happened? Ah shoot, sorry to hear this. I suspect if the MYSTAT was out of calibration it may have caused issues with the cycling. An issue with the iodide-containing chemistries is possible clogging of the felts with iodine if something goes wrong; normally the triethylene glycol should prevent this by forming a soluble complex, but it's possible your system got outside the normal operating range. I'd try again fresh (in a PP box/spill tray/secondary containment), with a calibrated MYSTAT running the latest firmware. Tagging @danielfp248 in case he has any suggestions.

Here is a video of assembling the large-format cell. https://spectra.video/w/m9RKg1QWrFdkkn9qUBFMTS FYI, you are meant two use two endplates per side (I used one here), I intentionally left the graphite felt out as this was for leak-testing, and the cell is missing washers on one side. The video illustrates the basic process of assembling our cell and how it is designed and seals. All the design files are available at https://codeberg.org/FBRC/RFB-large-format-cell. The setup is essentially there, waiting on chemicals and sorting out the power electronics set up and we should be able to run our first real charge/discharge tests with this large-format cell! The work to get to this point has been supported by the NGI0 Entrust Fund, a fund established by NLnet, to whom we are very grateful!

Charging to 6Ah/L at 30mA/cm2 and discharging at 5mA/cm2. At most we only get 2-3 Ah/L of available capacity, same as if we charged to 4Ah/L. [image: 1758211363268-f3e1b8fc-98a1-4c8b-b305-b4d4a5bedee6-image.png]

This test showed some deterioration on cycling: [image: 1758097795042-c586de1d-8d24-4884-bd7a-a00afb789080-image.png] I took out the catholyte and anolyte when charged (you can see the anolyte (left) and catholyte (right) in the pictures below). There isn't any hydroxide precipitation in either one. However there are some pieces of detached Fe metal on the anolyte, which I think are what causes the slight loss in capacity and increases in ohmic resistance as a function of time. [image: 1758097834649-5ee56443-1754-4f62-9a96-83d6194304ca-image-resized.png]