diy solar

diy solar

My adventures building a DIY Mn/Fe flow battery

Necessity if the mother of all inventions which could indicate an external driving force like you focus on in your reply, but necessity is equally found internally, to challenge the mind and to find or expose the true nature of oneself. Not meant to be poetic, but it could be.

Inventing or "to boldly go where no man has gone before" isn't always about financial gain or recovery, sometimes its to push boundary's of what is possible or meaningful. Science have never been about financial gain, science has always been about expanding the mind and our collective understanding of oneself in this universe.

.. and then there is... *yawn*.. money ;). Profit isn't evil in itself, to that I degree. But it can be if solely used as an argument for... etc. But I'll think its better to stop here. There is room for multiple views and perspective when it comes to "right & wrong", but this is hardly the place for deep political views.

But thanks for sharing
 
Q: Couldn't Fe-EDDHA be used in a similar manor as FeCl ? ... the reason for asking is twofold. One: It would reduce the complexity of the battery and two: reduce the crossover contamination. If it can't, I'd love to hear the reason since I am going on the same ionisation states as that of the FeCl counterpart.
 
Q: Couldn't Fe-EDDHA be used in a similar manor as FeCl ? ... the reason for asking is twofold. One: It would reduce the complexity of the battery and two: reduce the crossover contamination. If it can't, I'd love to hear the reason since I am going on the same ionisation states as that of the FeCl counterpart.
You cant use it this way. The FeEDDHA chelate dissociates under strongly acidic conditions. You end up with Fe3+ and H4EDDHA in solution.
 
Happy late Easter. I periodically refresh chemisting dot com to see if there is any news and noticed that the page is down. Is it maintenance or something going on ?
 
A new friend who is currently doing a post doc in France and did his Ph.D. in flow batteries donated me a basic setup for flow battery research, including two motors and a cell with a small area (many thanks if you read this!!). You can see the setup below. He was also kind enough to send me small samples of microporous membranes and graphitic felt electrodes.

The pumps are driven by a 24V power supply and a low cost NoceMCUv3 board. They draw around 2.1W each.

My potentiostat sadly got damaged in a small accident (got some liquid on it), so I have ordered a new and improved version (based on this paper https://www.sciencedirect.com/science/article/pii/S2468067220300729) to continue my research. The total cost was around 310 USD, including shipping and customs to the EU.

In the meantime I am doing some Fe-EDTA crossover tests using the microporous membrane, to see how bad the crossing of the Fe is as a function of time.
 

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Exciting news for the separator. It is still and despite the use of sulfuric acid, a budget approach, which is part if your goal.
 
Good to hear and I am glad you explored another venue for the structure material. Super excited about the qualification of this separator and how it will compare to commercial grade. But, even if the time period between service is less compared to commercial separators, that might not matter since a new one can be manufactured
 
I replaced my old potentiostat with a mystat potentiostat from this paper (https://www.sciencedirect.com/science/article/pii/S2468067220300729). I had it made on pcbway and shared it on the site so anyone interested can order their own. (make sure to select PCB+assembly to get the full board) (https://www.pcbway.com/project/shareproject/MyStat_Potentiostat_9df57df2.html). Also make sure you read the description for notes on the power supply and cable needed for the electrodes.

This potentiostat has an extended potential range (-11 to 11V) and an extended current range (up to 200mA).
 
Daniel, i've been reading on your work and i'm mighty impressed, kudos to you! I've been recently wondering though about a flow battery chemistry that would use the O2 from the atmosphere, so that one half of the redox reaction is basically free, making the battery cheaper and more energy dense. Have you considered that option when deciding on the chemistry to use?
There's some literature on sulfide-air flow batteries but they seem to be problematic. I wonder if there are other options.
 
Daniel, i've been reading on your work and i'm mighty impressed, kudos to you! I've been recently wondering though about a flow battery chemistry that would use the O2 from the atmosphere, so that one half of the redox reaction is basically free, making the battery cheaper and more energy dense. Have you considered that option when deciding on the chemistry to use?
There's some literature on sulfide-air flow batteries but they seem to be problematic. I wonder if there are other options.

Thanks for posting and reading my content!

It is very difficult to create these batteries in a durable manner. There are mainly 2 issues faced by batteries that use O2. The first is that they require effective transport of oxygen containing species, which only happens under very basic conditions in water. This makes poisoning of the battery by CO2 from the air a huge problem. The CO2 forms carbonates, which are not electrochemically active and clog the battery.

Another is that these batteries will tend to form some insoluble oxide in the electrode, which is often poorly conductive. This makes the energy efficiency of the batteries lower and also generates "dead zones" in the cathode.

For the above reasons, I don't consider these chemistries, as they require material engineering beyond my DIY capabilities.
 
Thanks for your reply, and sorry to read about the problems with the Fe-EDDHA. So the problems with an air breathing battery are due to the water, basically. I wonder if some other solvent could be used, i'll try to do some research.
 
I stumbled on your posts and found them interesting. I was hoping this would be a cheap renewable DIY project but I guess if it was, there would be more commercial options. Reminds me of making potato batteries in school. Maybe that deserves looking into. Hopefully with a byproduct of Vodka.
 
You talk about Iron Salt and Manganese salt, but call it a Manganese/Iron battery. I see a lot of talk about Iron/Salt flow batteries, but they seem to be saying salt water as in Sodium. Maybe it was mentioned some were in the pas 8 pages, but I take these are two different batteries. And if so, what was the reason for not going Iron/Salt?
 
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