My adventures building a Zinc-Bromine battery

danielfp248

Battery researcher
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Sep 7, 2020
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315
Hi
Thanks for that.
Sorry, what I meant was to reference the board they did for you, that way it would probably make it easier for them, if you see what I mean. Could I ask roughly how much they charged if that''s ok?

It was around 160 USD including shipping via DHL. However, components might be more expensive now. Here is the information for my order in case any of it is useful for you :

1621455659007.png
 

danielfp248

Battery researcher
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These are the files. They might charge you to create a component placement file, sadly I don't have that one.
 

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  • Files_for_pcb_manufacturing.zip
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Juptron

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Nov 2, 2020
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My original zinc bromide batteries were discharging at an alarming rate ie 75% in 12 hours, but they are much better now. I agree with your statement regarding an acceptable amount of self discharge with it's regard to cost. My cell costs are very low, so should be ok. I intend to do some more tests based on a 0.5C charge/discharge rates to full charge and see how they go as dendrites may now be my only problem.
Hello how did you reduce self discharge for your battery?
 

Identernet

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May 10, 2021
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Hi Juptron
I've been working on these batteries on and off for about 4 years, so I don't really want to disclose my methods. I trust you will understand this. I can tell you that you will need some form of sequestration as Daniel discusses, otherwise you have no chance. I found that my separator played a large part also, both in stopping dendrites and self discharge. The cell also need to be sealed well as bromine vapours and electrolyte leakage results in massive self discharge also.
I would gladly make my methods open source but I don't want Universities/companies getting any of my research. Universities like to charge people to access papers which have ultimately been paid by the taxpayer, hence my dislike of their methods. Obviously I can't afford patent protection. Patents are in place to protect the already rich Universities/Companies.
 

Juptron

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Hi Juptron
I've been working on these batteries on and off for about 4 years, so I don't really want to disclose my methods. I trust you will understand this. I can tell you that you will need some form of sequestration as Daniel discusses, otherwise you have no chance. I found that my separator played a large part also, both in stopping dendrites and self discharge. The cell also need to be sealed well as bromine vapours and electrolyte leakage results in massive self discharge also.
I would gladly make my methods open source but I don't want Universities/companies getting any of my research. Universities like to charge people to access papers which have ultimately been paid by the taxpayer, hence my dislike of their methods. Obviously I can't afford patent protection. Patents are in place to protect the already rich Universities/Companies.
Ok thanks for sharing, good success to you and everyone on this..
 

Substrate

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I think it's pretty awesome the work you've done. My only concern is that because of the bromide / bromine it would be best left to industrial batteries where professional waste services can be employed.

In the hands of a consumer, you know where 90% goes - straight to the landfill.

I know other inventors like Charles Renard (1847-1905) gave up on bromine and stuck to chlorine-zinc in the end, but that was after the early flow batteries for blimps stuff. :)

I gotta' re-read the thread slowly, because it sure is fascinating. Nice job and thanks for sharing.
 

danielfp248

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So guys, I moved countries earlier this year and hadn't had the time to start my home-research into Zn-Br batteries again. However, I have now reached a stable situation and will start researching Zn batteries again. I will start another thread as I will start research into some additional Zn chemistries, since some problems of the Zn-Br chemistry seem to make them hopelessly impractical for long-term DYI batteries.

These are the problems that I believe make static Zn-Br batteries an impractical choice and why I won't research them any further:
  1. Sequestration of the Br2 requires the use of sequestering agents. Most of these have low solubility values in concentrated ZnBr2 solutions (>0.5M). High capacity batteries require high concentrations of ZnBr2, which means a highly soluble sequestering agent with a very low solubility perbromide would be required.
  2. The low solubility perbromides effectively sequester bromide as insoluble perbromides, but then they inevitably reduce the conductivity of the cathode on deposition. If large amounts are deposited, then the reduction of the perbromides becomes difficult due to this. This inherently limits capacity.
  3. There is hydrogen generation at the anode. This leads to a basification of the battery that eventually pacifies the anode, as Zn oxides and hydroxides deposit on the anode. This kills the battery and would require refurbishing.
  4. Using an inverted geometry (Zn anode at the bottom and carbon cathode at the top) effectively fixes the hydrogen evolution issue, but at the expense of making the issue of self discharge worse (as elemental bromine and solid perbromide can fall into the anode and react with the Zn).
The above issues are, in my opinion, quite insurmountable from a DIY perspective - especially without incurring very high costs to test more elaborate sequestering agents - so I've decided to focus on more friendly chemistries.

The perbromide sequestration and hydrogen evolution problems are issues with no obvious practical DIY solution - at least to me - and compromises lead to batteries with high self-discharge, low capacities, low energy densities or low energy efficiencies. In my view, there is no point in making a battery if you cannot at least do as well as Li-Fe-PO4 batteries from an economic perspective (either by having much longer cycle life or better energy density or capacity).

Also some notes for those who might be interested and have done some online reading but don't want to read my whole blog or this thread:
  1. This Chinese paper, has serious issues and should NOT be considered a substantial breakthrough in Zn-Br batteries. The capacity values reported are based on the mass of active cathode material (3mg per battery), while the entire cathode mass is likely 10x that and the total battery mass - including electrolyte - is likely 50-100x more. The capacities are therefore entirely misleading, since capacity in Zn-Br batteries comes from the mass of electrolyte, NOT the mass of the cathode. The power densities do not account for the mass of the water, anode or entire cathode either, so they are also extremely misleading. The Zn-Br concentration is also kept quite low (0.5M) this is because of a very good reason, TPABr is not soluble in ZnBr2 solutions above this threshold. When accounting for entire battery mass, this is orders of magnitude below lithium ion in terms of power density or capacity.
  2. Robert Murray Smith has done several videos about Zn-Br batteries, but these batteries represent a compromise that is unacceptable in practice. The series resistance of these batteries is directly proportional to the distance between the electrodes and all the batteries he has shown have very large distances and likely suffer from huge internal resistance. Although he might have quite high Coulombic efficiency values - what he often quotes as being above 85% - the energy efficiency, or how much energy you get out for energy you put in, is likely extremely low, around 10-15%. Be prepared to put 10kWh for every 1kWh you want to get out if you intend to follow his geometries and advice on these batteries. A high energy efficiency Zn-Br battery should have a cathode-anode distance of around 3-5mm if using 1-2.5M ZnBr2 solutions.
  3. The Princeton minimal architecture papers show some of the issues I've discussed above. They run into issues with unacceptable cell discharge and anode deactivation due to hydrogen evolution. If you look into the PhD theses from this research group, you will find theses dedicated to the scaling of these batteries, these show how these issues completely precluded the use of these batteries at any significant scale.
While the Zn-Br chemistry might seem a pretty obvious and clear option for DIY, reality shows why companies and researchers decided to switch to flow batteries and how - even when doing this - some pretty hard problems still remain.

The devil is clearly in the details when it comes to Zn-Br batteries. 🤓

The above is also not meant to discourage others who might want to pursue this technology, but just a list of issues so that you can go into this chemistry with eyes wide open.
 
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100kwh-hunter

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@danielfp248
Still biting the bullet for zn-br cells?
Well i can not leave it behind me also, it keeps on rambling in my mind........on and on.
When i finished rebuilding my house, i also will give it another go.
Thank you VERY much for your efforts, very helpful and constructive ideas!
(we met on a different forum btw)
Matter a fact i was cleaning my shed last month and found some of my old experiments, but not the data that i promest you, sorry.

Thanks for keeping up, with best regards Igor aka 100kwh hunter.
Time sure flies.....
 

metaros

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Jan 26, 2021
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Anyone still getting after it with this battery research? I came to the same conclusion as @danielfp248 that Zn Br cells are not a viable or safe homemade solution. Zn I2 is a logical next step. Here are some other ideas to consider:

1) Zinc Iodine: Use of propylene carbonate as complexing agent (https://www.sciencedirect.com/science/article/abs/pii/S0013468619312939?via=ihub)
2) Zinc Iodine: Use of Ammonium Chloride as electrolyte enhancer (https://www.sciencedirect.com/science/article/abs/pii/S2405829720302531?via=ihub)

There seem to be some irreversible reactions related to the ZnI2 battery on the iodine side, especially if the battery is over charged, so keep that in mind.

Zinc Nickel
I went down the rabbit hole with Zinc Nickel batteries, and I can tell you that getting an electrochemically active version of Nickel Hydroxide - Ni(OH)2 is an extremely finicky process involving PH / temperature / proper precursor matching / mix rate / drip rate.... I got it done once! and could not repeat the process. Nickel compounds are also expensive and I've put this one on the shelf

Zinc Mn3O4

I've moved on to testing Zinc Manganese based chemistries. I am keeping with the Zinc anode theme because it's cheap, available, offers great voltages and well studied (even with potential dendrite issues). Manganese is also very cheap ( Just look at the price of a 5lb back of MnSO4 on amazon... and compare that to a 5lb bag of NiSO4)

This is a good overview to help guide research: https://onlinelibrary.wiley.com/doi/10.1002/inf2.12042

Best of luck! and I definately understand what @Juptron is saying about keeping his own research protected. I've also encountered similar problems in the literature, especially with chinese type papers, and I think there are plenty of mistakes in a tremendous amount of battery related articles (both accidental and possibly deliberate...)

I've attached some files. Spending money on all these articles is expensive, maybe we can share the load here a little bit :) hopefully I start a trend.
 

Attachments

  • 00 Zinc Manganese Battery Complete Study.pdf
    8.2 MB · Views: 7
  • 05 ZnI2 with Propylene Carbonate.pdf
    2.5 MB · Views: 4
  • 06 ZnI2 with Ammonium Chloride.pdf
    2.5 MB · Views: 4

danielfp248

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Messages
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@metaros Unscrupulous people who want free scientific papers will often download telegram, add the scihub bot (@scihubot) and send it the DOI website address of any paper they want to download so that the bot sends it back for free. This is something you should absolutely never do.
 

toms

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danielfp248

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@danielfp248

I’m curious to hear your views on this article regarding an Australian ZnBr cell, or indeed your opinion on the viability of the gelion battery


You can read the gelion patents to get a better idea about this technology. This likely works, but it is going to be quite expensive - the gels are expensive ionic liquid electrolytes - so these are unlikely to ever be able to compete against Li-ion or to be available for someone to build in a DIY manner. Ionic liquids are expensive, despite a ton of research on ionic liquids in batteries we have no large scale commercial applications in the battery area.
 

toms

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Thanks for that. It will be interesting to see where they go with their technology.
 

geekineer

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Oct 4, 2021
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I apologize for this reply to work you did quite a while ago BUT
did you ever try or consider as a 'dendrite prevention solution'
a 'physical' barrier - i.e. phenolic sponge (thin 2mm? Oasis layer) or a gel???
Hope your current ZnI work is going well - super enjoy reading everything you've published.
 

danielfp248

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Sep 7, 2020
Messages
315
I apologize for this reply to work you did quite a while ago BUT
did you ever try or consider as a 'dendrite prevention solution'
a 'physical' barrier - i.e. phenolic sponge (thin 2mm? Oasis layer) or a gel???
Hope your current ZnI work is going well - super enjoy reading everything you've published.

I'm glad you enjoy reading about my experiments!

About physical barriers, there are two main issues with them. One, physical barriers are physical barriers to everything, including ions, so they greatly increase the electrical resistance of batteries. A battery with a 2mm oasis foam layer has a huge internal resistance, so incredibly inefficient. Second, dendrites are very sharp, they easily pierce through physical barriers.

Note that zinc dendrites are much much harder than Lithium dendrites, reason why this approach - which has been tested in the Li battery world - doesn't work well in Zn.
 
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blaplante

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Nov 5, 2021
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@danielfp248 I have just read your excellent info here and in the blog as I was seriously looking at this chemistry as an alternative to short lived Lithium cells. The ups and downs, the great promise and the final (I totally see your point) surrender. I know part of your goal was to do at least as good as Lithium (or maybe at least lead-acid?). Which got me to thinking --- for a static application, bulk and weight is a lesser issue than long term stability. I'm wondering if the cells weren't pushed as hard (less current, narrower voltage from charge to discharge) and perhaps less concentrated electrolyte... would ZnBr be able to last 1000 cycles or more?

I'm helping my sibling with an off-grid system. It's frustrating knowing that some days with good sun half of the solar power goes to waste. This could be fixed with doubling the Lithium battery size (not cheap, especially when considering limited life). Or, use the excess power to charge some alternative storage (ZnBr?), which then would charge the primary Lithium bank as power is used from it after dark. In this case perfect energy efficiency isn't hugely important as the power would have been lost otherwise (and any shortfall is made up with an LP genset). Using an alternative battery in this case removes a lot of the restrictions --- we can control the charge and discharge rate independent of the house's need.
 

danielfp248

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Messages
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@danielfp248 I have just read your excellent info here and in the blog as I was seriously looking at this chemistry as an alternative to short lived Lithium cells. The ups and downs, the great promise and the final (I totally see your point) surrender. I know part of your goal was to do at least as good as Lithium (or maybe at least lead-acid?). Which got me to thinking --- for a static application, bulk and weight is a lesser issue than long term stability. I'm wondering if the cells weren't pushed as hard (less current, narrower voltage from charge to discharge) and perhaps less concentrated electrolyte... would ZnBr be able to last 1000 cycles or more?

I'm helping my sibling with an off-grid system. It's frustrating knowing that some days with good sun half of the solar power goes to waste. This could be fixed with doubling the Lithium battery size (not cheap, especially when considering limited life). Or, use the excess power to charge some alternative storage (ZnBr?), which then would charge the primary Lithium bank as power is used from it after dark. In this case perfect energy efficiency isn't hugely important as the power would have been lost otherwise (and any shortfall is made up with an LP genset). Using an alternative battery in this case removes a lot of the restrictions --- we can control the charge and discharge rate independent of the house's need.

It is true that lowering the current density immediately reduces or removes a lot of the issues. However, the biggest issue lower current doesn't solve, is the self-discharge of the battery. At low current densities, it will take longer to charge the battery, which gives more opportunity for bromine to migrate from cathode to anode and discharge the device. You would need small separation distance between cathode and anode to be able to charge below 1.9V at a reasonable current density (taking say 12 hours to charge the batteries) which makes the issue worse.

Adding sequestering agents will increase the internal resistance of the battery, which will add to your problems and costs. Especially because sequestering agents that are soluble enough in concentrated ZnBr2 are expensive (TBABr or TPABr do not work well because of lower solubility).

There is not much point in lowering the concentration of electrolyte, as that just makes the battery more inefficient.

It is also false that Zn-Br batteries do not degrade, hydrogen evolution reactions in the anode eventually lead to electrolyte degradation to the point where chemical regeneration of the electrolyte using HBr becomes necessary. This is even true if you were able to charge with no over-potential as the hydrogen evolving reactions are significant a this potential anyway. It isn't trivial to overcome these reactions.

Honestly, there is no demonstrated DIY solution - I am not aware of any solution that has been properly characterized and showed to work as intended - that offers you reasonable energy storage capabilities for lower cost than lithium ion batteries, even at low current densities and low energy/power densities. If you go this route, you are bound to spend a lot of time and effort to end up with something that is likely to be dangerous, not standardized and with unknown performance characteristics. Also, it is likely to last way less than 1000 cycles. Taking these systems apart is also no picnic, dealing with large amounts of nasty bromine is a possibility.

For your siblings build, I would go with a commercial solution.

Everyone likes to say it is super easy to get 60Wh/L with Zn-Br and get +10K cycle life, truth is, it is really not. Obviously I would love to be proven wrong by anyone who has actual charge/discharge cycling data of a DIY system. So far, a lot of people have talked the talk, no one seems to have walked the walk with any success.
 
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