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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.
Welcome @saphnich and @rowow ! Membranes are definitely something relevant to our work here, to date we have avoided ion-exchange ones like Nafion due to the high cost but having a low-cost and open-source option would be great. I'll hop into the thread @rowow started on DIY membranes.
@rowow said in New member introduction thread!:
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.
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.
Zinc bromide flow batteries have been researched very extensively during the past 30 years. There are many advantages to this chemistry, very high potential (~1.8V), high efficiencies, symmetric electrolyte and low reagent costs. Nonetheless, the disadvantages are also huge: zinc dendrites, hydrogen evolution, bromine corrosion, etc. Despite all the development, a lot of these disadvantages remain insurmountable.
A recent nature paper has disrupted the field by using sulfamate ions as a bromine scavenger. Unlike previously used complexing agents that sequestered Bromine as reactive Br3- species, the new scavenging method sequesters Bromine as an N-bromosulfamate, which is stable in solution in the timescales necessary for energy storage. Furthermore, the N-bromosulfamate is chemically much milder than elemental Br2 or Br3-, making the use of cheaper gasketing materials possible and preventing a lot of issues associated with the high reactivity of elemental bromine species.
A model of the nicotinamide molecule. The Br reacts primarily with the amide group (NH2) under mildly acidic conditions.
I have been very excited by these findings and have ordered some sodium sulfamate to test this chemistry myself in our FBRC development kit. However, the development of this technology is likely not open source and it is very likely that the people involved with it want to patent it and lock down the technology. This made me think about potential alternatives that could be used outside of the sulfamate family that could also exploit the mechanism of Br storage in N-Br bonds. Such a technology might be outside the scope of their original paper and therefore be exempt from intellectual property registration.
Thinking about the stability of N-Br compounds (usually not stable at all), I immediately think about NBS and analogous chemical compounds. These are very stable reagents that are routinely used in chemical synthesis, although their aqueous solubility is very low and therefore not useful in the creation of a ZnBr2 aqueous battery.
With that said, nicotinamide (vitamin B3) is a very water soluble and readily available material that also forms a stable N-Br compound in mildly acidic conditions. This 2007 paper describes how N-bromonicotinamide can be created using elemental bromine. While N-bromine compounds from amines like this would often go through a Hoffman rearrangement to yield the corresponding amine, this doesn’t happen under mildly acidic condition in the case of nicotinamide. In fact, the 2007 paper mentions that a concentrated solution of this N-Br compound was stored for months without degradation. The solubility of nicotinamide is also very high (5-6M), compared to sodium sulfamate’s solubility limit of 1.3M at 25C.
An example of a nicotinamide-Zn complex. Check this paper to learn more.
Furthermore, nicotinamide forms mono and dimeric complexes with Zn atoms through the nitrogen in their pyridine ring, which makes this nitrogen unavailable for potential deactivation with direct bromination of this N to yield the corresponding quaternary nitrogen salt (irreversible and undesirable in the context of a battery).
Given that vitamin B3 is very soluble, very low cost, already produced industrially, has a stable amide N-Br compound and is unlikely to undergo Hoffman rearrangement or similar decomposition modes, it is a great candidate to serve as a Br2 scavenger in a ZnBr2 battery. I am going to buy some vitamin B3 to test this idea out. Stay tuned for some tests of this and the sodium sulfamate chemistry.
We will be presenting at FOSDEM 2026 and hope to see you there! Kirk and Daniel will be presenting at 12:30 on Saturday, January 31 in the Energy track in room AW1.126. Full details here, including the link to the livestream (talk should also be recorded and watchable later).
The title of the talk is "Scaling up open-source batteries: what's worth pursuing?". Here is the abstract:
Storing energy reversibly is useful. For clean energy, electrochemical batteries are one of the most attractive options. Most battery technology is proprietary, hard to recycle, and complicated to manufacture. What if that wasn't the case?
We will present our collective and individual efforts with the Flow Battery Research Collective (https://fbrc.dev/) to build open-source batteries for stationary storage applications. This includes our flow battery work, such as efforts to build a larger-format cell with simple manufacturing techniques like laser cutting and FDM printing, as well as our different experiments with flow battery electrolytes based on zinc, iodine, iron, and manganese.
For the "large-format" cell, we'd like to target as large of a geometric area as possible, and ideally have the flow frame be useable both for single-cell and stack testing. This means it needs to possess adequate internal fluid manifolds and flow diffuser/spreading geometry. We must also consider shunt currents once we progress to stack testing, so we'd like to design the cell with that issue in mind upfront.
We plan to start with a flow-through design, as it is much, much simpler to design and manufacture than flow field-based approaches.
This thesis has some helpful figures - I haven't read it yet myself, but it looks quite useful. The author is now a professor at University of Padua.
Basically we want to make our own version of this. Ideally we could prototype it with polypropylene FDM printing... but in any real application it would be injection molded.
A good image showing the path of a shunt current, which leads to a drop in energy efficiency as well as uneven current distribution (and possibly plating, for hybrid RFBs):
Did another leak test today with water, correctly with 2x ~12 mm plywood endplates each side. Saw no leaks through the edges which was great news, but the barbed connections on the cell showed signs. Also, the MP-6R pumps struggle with the current flow frame design, which has 0.8 mm wall thickness and a 1 mm internal channel (electrode area therefore 2x0.8 + 1 = 2.6 mm thick). I remade (and pushed to the repo) the flow frame with a 3 mm internal thickness, in order to alleviate this pressure drop.
Here is the test setup, I ran out of tubing (ordered 2m but they sent 1 m ), so the connections aren't ideal but this time no kinks in the flow path. Note, I put these drain valves in, of course they are pointing the wrong way for now, will need to elevate the setup so they can point down in the future.
[image: 1769764493660-9fafda86-7f70-439f-9ecb-eeb9a7316215-img_20260129_153901-resized.jpg]
Because all the connections are on one side (in anticipation of stacking these cells), I also made "front" and "rear" versions of endplates, inner/outer current collectors, and gaskets in the FreeCAD files. This will make low-volume prototyping a bit more expensive but more robust against leaks, which no one wants!
[image: 1769763690358-037a7741-97dc-4012-8e95-cf8ab8760653-image.png]
This is the dimension that went from 1 mm to 3 mm to facilitate using MP-6R pumps.
[image: 1769763764115-d4ac6efb-4694-4d13-a941-8ffb85995001-image.png]
We have the MP-6R now. It is the 6W high-flow version. the MP-10 is also 6W but lower flow / 50 % higher max pressure, then the MP-15R can do almost 3x higher pressure than the MP-6R but at 10 W.
@danielfp248 can hopefully print the 3mm flow frames and I can get them at FOSDEM, then try them out. If it turns out we need the bigger pumps, I'll order them from AliExpress:
[image: 1769763852108-f14b9379-cbc5-4542-940c-b33c0bacdb14-image.png]
as part of the CIRCLE project at the Bochum University of Applied Sciences, our student group is preparing to conduct a life cycle assessment (LCA) for the Flow Battery Research Collective’s open-source redox-flow battery. If possible, we would like to take a look on the upscaled cell/stack/battery.
During our Zoom meeting on 19. November 2025, you shared several ideas for meaningful LCA topics. Based on your input, we developed two possible options that could support the ongoing development of the battery. To proceed, we would like to know which option you prefer or where you can provide the most useful data.
Option 1: Electrolyte–Membrane interactions
This topic focuses on how the electrolyte composition and membrane material affect each other, especially regarding efficiency and degradation. Goal:
To assess the environmental impact and technical relevance of electrolyte–membrane interactions, and to perform a screening comparison of membrane and electrolyte choices from production to end-of-life. Information we would need (please provide as much information as possible):
• How the selected electrolyte interacts with different membrane materials and which parameters are considered for choosing the electrolyte-membrane pairing
• Measured efficiencies of the current electrolyte-membrane selection
• Background on membrane selection in the development kit (e.g. which specific materials were chosen and why)
• How is the material wear currently counteracted (replacement only)?
• How is waste (wastewater, solid waste, co-products from chemical manufacture) disposed of?
Option 2: Electrolyte Leakage
Leakage is an important practical and environmental concern, and understanding its causes could support improvements in design, sealing, and material choice. Goal:
To analyse the environmental implications of electrolyte leakage, identify contributing factors, and explore what design or material changes might minimise it. Information we would need (please provide as much information as possible):
• How frequently leakage occurs (per cycle/per kit/in what percentage of the kits)
• How leakage is currently detected (refill volume, reduced power output, emissions, etc.)
• Whether it is monitored proactively or noticed after cycle completion
• Estimated amount of electrolyte lost per cycle
-> If no data is available, could it be collected by measuring leakage over multiple cycles?
• Whether leakage becomes more common with aging or due corrosion
• Current methods or design choices used to minimise leakage (e.g. sealing, welding, bonding)
We also have some general questions. More questions will probably arise in the future. General questions:
• How much energy supply does a RFB require (for one cycle/in total)?
• Which electricity mix is currently used to operate the battery (is there a proportion of green electricity)?
• Where are the materials purchased? From which countries are they delivered and how (train, car, ship)?
• In which country are the batteries assembled and tested?
We would be happy to work on either topic, and we aim to select the one that is most helpful for the FBRC team and for which the necessary data can be provided.
We look forward to hearing your thoughts and continuing our collaboration!
Kind regards,
Rieke Huesmann, Anita Thaqi, Stella Vucemilovic
Hi all, and apologies for the delay! This year has started off with quite a lot of administrative burden for me and I haven't had as much time for research as I anticipated.
@Santiago-Eduardo said in Life Cycle Assessment (LCA) for the FBRC redox-flow battery:
Elektrolyte:
The group noticed that two slightly different electrolyte compositions are mentioned.
Sorry for the confusion, the correct mass composition can be found in the documentation here: https://fbrc.codeberg.page/rfb-dev-kit/electrolyte.html, the masses listed will prepare approximately 10 mL of electrolyte.
@Santiago-Eduardo said in Life Cycle Assessment (LCA) for the FBRC redox-flow battery:
They assume an 880 ml volume for one single cell. Do you estimate this volume to maintain the obtained results until now? Is this the volume foreseen to achieve the 22 Wh/single large-format cell?
Yes this would be correct volume scaling for the large-format cell, although of course still a lot smaller than an eventual life-size system! It is basically t]e volume that we will end up using for our tests of the large-format cell (still to come).
@Santiago-Eduardo said in Life Cycle Assessment (LCA) for the FBRC redox-flow battery:
The group is assuming the EE value to estimate this. This value does not include energy demand from pumps and electronics, correct?
Correct, these losses are often summed up in RFB literature as "balance-of-plant" or BoP if you want to search for some values.
@Santiago-Eduardo said in Life Cycle Assessment (LCA) for the FBRC redox-flow battery:
Meaning: to store 1 Wh, 1.56 Wh needs to be taken from the grid (excluding electronics and pumps). Does this make sense, or are we oversimplifying here?
You've got it exactly!
@Santiago-Eduardo said in Life Cycle Assessment (LCA) for the FBRC redox-flow battery:
Used electricity
For the same purpose of modelling the use phase, it is important to define from which country and what type of energy/electricity is being used to charge the electrolyte. Since the users of the FBRC battery can be anywhere, but are currently mostly centered in Europe, the group has decided to choose the European electricity grid mix data to represent the current FBRC reality.
This makes sense to me.
@Santiago-Eduardo said in Life Cycle Assessment (LCA) for the FBRC redox-flow battery:
The separator, for instance, would be one of these peripheral impacts, since it would need to be replaced after some cycles (probably faster than the electrolyte). Since cycle durability of photo paper is still unknown, the group will model different scenarios from 10–100 cycles in steps of 30 cycles. Do you feel this is a reasonable range? Do you already now conditions such as density and flow rate the larger cell will work with? The group will assume 4 layers for the larger cell although in some parts are 3 layers stated.
While separators can be replaced, I am doubtful in an industrial system that they would, due to the labor costs. From my understanding, Li-ion lifetimes are often given as 2,000 cycles to 80% of initial capacity; for flow batteries, the data isn't as solid, but for VRFB the lifetime claims are more on the scale of 20,000 cycles or 20 years, whichever comes sooner (taken with a grain of salt...). We haven't done any testing that long-term, so don't have much for your to extrapolate, but RFB technoeconomic papers with operation and maintenance (O&M) costs incorporated would give you a good idea of membrane/pump replacement
frequency (if ever). I would increase the cycle range to much longer terms, with the upper end in the 1,000s at least.
We aren't yet locked-in on flow rates for the large cell as we are still settling on choice of pumps and flow field design.
@Santiago-Eduardo said in Life Cycle Assessment (LCA) for the FBRC redox-flow battery:
The current BOM and building instructions do not provide specific links to purchase the necessary chemicals. To model the electrolyte production, including the transportation of each chemical, the group has assumed the following production locations based on market data and worldwide production trends. If your own experience differs in this, please do not hesitate to comment.
These assumptions all make sense to me; Daramic separator (which we also use in addition to paper depending on the test) can/is produced in the EU though not exclusively.
I hope this clears things up for you all somewhat, and again, sorry for the delay!
I didn’t want to take over the “New member introduction thread” with my questions, so I’ve started a new one.
At this point, I already have the 3D printed components. I should receive the remaining parts later this month.
One thing I was missing in the documentation was information about the material for the "polymer endplate". In the photo, “PETG 100%” was written on the endplate with a marker, so I used that material and infill.
@danielfp248 I always performed more cycles before starting 40 mA / 100 mAh charging (10 half-cycles at 20 mA / 10 mAh + 4–10 half-cycles at 30 mA / 10 mAh). The cell was also wet with demineralized water (leakage test). Could this also be the cause? I was also always using the membrane frame. Wouldn't the electrolyte leak through the paper membrane?
@kirk Apart from solving the electrolyte leakage issue, does this "pulling-through configuration" improve the total capacity of the system in any other way? Also, I am wondering whether you are using the default flow frame from the documentation (2 mm thick, right?) or a different one with another thickness and the 0.1 mm silicone gaskets.
I have still not been able to test my cell because I wanted to make sure I had my mystat calibrated correctly. For this I wanted to implement a calibration wizard. Unfortunately I was not prepared to deal with the very large single file, single layer codebase of the mystat control software. I therefore had to start refactoring this code. My progress is visible here: https://codeberg.org/sepi/mystat/src/branch/feat-refactor-modular
The advantages of my refactor are amongst others the following:
less global state, easier to understand code
multiple smaller modules making it easier to find code
layered architecture, separating concerns more cleanly
"plugin" system for easier extension
easier testing of both hardware code and gui code due to decoupling into layers. A mock hardware class could be implemented to test the gui or other Tabd could be implemented as new classes
availability of decoupled hardware layer that can be used independently of the gui
easier implementation of new "Tab plugins" by subclassing and using the hardware and gui layer.
This is still work in progress and probably pretty buggy. I tried not to touch any of the implemented logic but there afe surely some problems left. Once I'm done with the refactor, I would like to write a wizard for calibration hoping to make it obsolete to consult the original paper for reference.
I'm open for comments and suggestions now and help with testing once my branch has stabilised a bit.
Hi sepi, your refactor-modular works on my PCs: my mainPC (Kubuntut 2404) and two Notebooks for measurements (Kubuntu 2404 and Win11), thanks.
I'm waiting for your calibration wizard. My hardware is waiting incl. Mystat, but till now I did not do tests.
In the hope that it will be useful to the future work of folks here, I've written up as much as possible about my experience patching up a failing ZCell and nursing it along. I've also included some further general notes about Redflow's hardware and software:
Hello! I'll try to document my building experience here while I impatiently wait for parts to arrive. This is mostly to document and motivate myself to continue. Don't expect super interesting stuff in here.
After having ordered most of the material from aliexpress and amazon.de, I finally got around printing the endplates yesterday. I opted for PLA on my old ender 3. As described in the docs I went for the 60% infill and managed to produce some pretty decent parts. The layer height of 0.25 looks good too. Each plate took around 1h30 on this antique machine. There might have been a tiny bit of warping on one edge but I hope it won't be enough to cause issues.
Anyways, I still need to print the arduino case and the stand (which I might modify in order to use less material). On the ordering front, I still need to order most reagents from synthetica and some PP-filament.
@sepi Without the four-wire control the pump speeds are definitely harder to manage, sorry to hear that, though the PWM regulator may help. Can you visually see how different the rotation speeds are? That should be rough proxy for volumetric flowrate. I am not surprised they won't spin below 11 V.
@sepi said in My build (very slowly progressing):
Is this 20-40ml/min measured with the cell in line or just the pump.
Ideally best to measure with the cell inline, to be closer to the actual conditions. However, as the tubing wears, this can drift, just FYI. Not a huge deal but something to be aware of.
@sepi said in My build (very slowly progressing):
Is the figure obtained with water or electrolyte?
Water for now, just as a proxy, minimize exposure to electrolyte. This is kind of a 1, maybe 2 significant digit measurement, no more (the volumetric flowrate).
@sepi said in My build (very slowly progressing):
What would you recommend doing against the excess flow?
@sepi said in My build (very slowly progressing):
the left passing up to 40% more water at the same voltage.
At the same voltage, is the left pump spinning at (nearly) the same rate as the right? if they are spinning at the same rotational speed and the left is passing 40% more water, it sounds like there is some flow restriction in the right pump's flow loop. If they have identical flow loops (in terms of pressure drop), and are set at the same voltage, I would guess that they should rotate at similar speeds, but this may not be the case for the brushed motors (e.g. variance in motor properties).
What is important for testing, is that both pumps are above a minimum flowrate to ensure good mass transfer, and that the pressure imbalance between the two sides isn't too great as to cause transfer of electrolyte from one side to another through the separator. If the flowrates aren't perfectly matched but those two previous conditions are met, it's not a big issue, although it's just better for repeatability for them to be the same.
Hello fellow flow battery enthusiasts! I bought 15m of Tygon Chemical tubing with PTFE lining suitable for the Zn/I chemistry as used in the devkit. I only need around 2m and someone else wanted to take 5m, that's 8m left to be distributed amongst people who need some. I ship in the whole EU and the price is 23€/m (thats what I paid incl. shipping). Just send me a PM if you're interested.
Hey Everyone. I designed and printed some PLA sleeves to go over M6 screws so that you don't need to use tape on the screws anymore with the kit. The tape is often hard to properly wrap around and imo has to be changed quite often, so this should improve the design. I printed these on a Prusa Core One using a 0.4mm diameter nozzle. The screws don't come into contact with active material, so you can use PLA for this (doesn't have to be PP, although this should also work).
@danielfp248 I ran into some of your old work on Fe-Mn batteries. I've been interested in Fe-Mn batteries for some time and was wondering if you could share some of your experience.
In particular, if we look at the pourbaix diagram of Fe and Mn overlapped, there's a region in the pH 4-6 range where Mn2+ oxidizes to MnO2 and Fe2+ reduces to Fe on charge.
Let's say we can ignore the fact that there are solid phases - then ion crossover poses a long term concern. Have you guys found any inexpensive or DIY ion selective membrane options (either specific to a particular ion or broad spectrum diy anion/cation exchange membranes?) In my experience screening for inexpensive battery chemistries, crossover of solution phase species is a problem I haven't really seen an easy DIY solution for. Not that I've looked super hard!
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]
I wanted to dedicate this thread to Fe-only systems, in particular systems that have plated Fe on one side and Fe3+ on the other. I am currently waiting on MgCl2 and CaCl2 to carry out some experiments on WiSE electrolytes, but in the meantime I thought I would test a low water activity system containing large amounts of urea. This contains 5mL of H2O, 2g of Fe2Cl2.2H2O, 5g of Urea and 0.3mL of HCl 15%. System is using a non conductive felt on the anolyte side and carbon felt on the catholyte side. Using 900um Daramic as microporous membrane.
Initial single cycle results show that this system can work at relatively high CE but quite low current (which is not surprising given the high amount of urea in the solution). This is one of the highest capacities I have been able to run for an Fe system (10 Ah/L), but energy efficiency is dismal (below 40%). I also don't know if it will actually cycle in a stable manner, we'll have to wait for some additional cycles to see how the system evolves. Perhaps this system will work better with felt on both sides, as metallic Fe is not as dendrite prone as Zn.
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]
All-Fe flow batteries are very promising due to iron’s high abundance, low toxicity and low cost. In these batteries, FeCl2 is used as the main active salt in solution. When charging Fe2+ gets reduced to Fe metal on the anode while Fe2+ gets oxidized to Fe3+ on the cathode. However, these batteries suffer from a fundamental problem that has made their large scale adoption very difficult up until now.
Cyclic voltammetry of 1M FeCl2 and 4.5M CaCl2 using an Ag/AgCl reference electrode and a glassy carbon working electrode.
The main limiting problem of these batteries is H2 evolution at the anode. Since Fe plating happens at a lower potential than H2 evolution, there is always some hydrogen generation when the battery is charged. This H2 evolution causes an increase in the pH of the battery which then causes iron hydroxides and oxides to precipitate out of solution. This causes passivation of Fe metal surfaces, loss of capacity and potentially clogging of the battery.
A few years ago, Tao Gao’s group in Utah discovered that CaCl2 and MgCl2 water-in-salt-electrolytes (WiSE) (read the paper here) could substantially improve Fe plating behavior. While they didn’t test this in flow batteries, they showed that very high Coulomb efficiencies with very low hydrogen evolution rates were possible when using these salts. This is because these salts bond with water and therefore make it substantially harder for water to get reduced at the anode. We are talking about very highly concentrated solutions though, around 4.5M CaCl2, which is around 660g/L of CaCl2.2H2O.
Plate/strip experiment using the 1M FeCl2, 4.5M CaCl2 electrolyte.
We recently obtained some of these reagents to test these chemistries in our flow battery kit. I first ran CV experiments of the 4.5M CaCl2 electrolyte with 1M FeCl2 and obtained the curves showed above. This reveals standard potentials of -0.71V and 0.55V for the two half reactions, which means our battery should have a max potential of around 1.26V. I then ran plate/strip experiments (using different plating times), which generated the second curve above. Using the slope of this plot we can extract the plating efficiency, which is >99% in this case. This means that very little hydrogen evolution is happening within this electrolyte, a result I had never seen with FeCl2 solutions and which is in agreement with the Tao Gao group paper.
After doing this I then ran a flow battery using this electrolyte and noticed some problems with capacity loss because of undissolved metallic Fe on the anode using a Daramic separator. It seems that the above electrolyte has some issues with the reversibility of the plating reaction. While little hydrogen is generated on plating, there still seem to be some important losses of capacity due to passivation of the Fe. To fix this problem I then added 1M NH4Cl into the electrolyte, which helped me fix this issue when dealing with Zn-I flow batteries.
Cycling of an all-Fe battery using 1M FeCl2, 4.5M CaCl2 and 1M NH4Cl. Cycling was done at 20mA/cm2 Charging was done to 4Ah/L and discharge was done to 0V.
I cycled the battery at 4Ah/L, which generated the results above. You can see that we get extremely good CE values (97.88%) which are even better than those we were obtaining with the Zn-I system, even though we’re using a microporous separator. The energy efficiency is lower than for Zn-I but still reaches a value of 53.27%. Given a concentration of 1M FeCl2 , 4Ah/L represents a state-of-charge (SOC) of ~30%. The cycling is stable, although some increase of the charging voltage is indeed happening through time (although this is also matched by an increase in the discharge voltage). The mean discharge potential is quite low though, at 0.7V, which means we have considerable ohmic losses at this current density.
I am now testing the electrolyte at higher SOC values and will continue testing MgCl2 and other modifications, such as additions of ascorbic acid and thiosulfate to remove oxygen from the initial solutions and improve the initial state of the battery (as some capacity is lost due to the presence of oxidized Fe in the initial solution). Make sure to follow our progress on this forum thread.
This flow battery kit work is being funded by the Financed by Nlnet’s NGI0 Entrust Fund. We are also collaborating with the FAIR Battery project.
Hello everyone! I've had the idea floating in my head for quite a while to make my own barbed connectors/fittings for connecting tubing as used in the dev kit. I finally got around printing a series of prototypes in PLA. The results are promising, even if the value of printed ones is questionable. Designed them so that you print them lying flat in order to optimise lengthwise strength. To get them watertight, you just need to sand the barbs a tiny bit.
I have two main reasons to print these parts myself, first of all, I forgot to order them and secondly, the more parts of the dev kot can be printed, the less people will have difficulties sourcing them.
I'll publish a Freecad file once I have it tested and printed in PP.
My pumps didn't have them, only the ones built into the pump. I saw that on some of your pictures, you have additional fittings between the different elements, I guess to make it easier to connect and disconnect the cell. In the end, it might make more sense to just shrink the barbs on the flowframe and/or tank a bit so the tubing comes off mor easily.
Redox Flow Battery Development Kit has the UID FR000028.
Redox Flow Battery Development Kit is: This kit is for testing flow battery components and electrolytes at a benchtop scale (2 cm²) with an affordable, reproducible setup.
Hello! I'll try to document my building experience here while I impatiently wait for parts to arrive. This is mostly to document and motivate myself to continue. Don't expect super interesting stuff in here.
