diy solar

diy solar

My adventures building a Zinc-Bromine battery

metaros said:
For sure, Ill look over your blog, I think I remember seeing instructions for the build. Ill take any documents / tips you have. For testing, Ive already purchased a ZKETECH battery tester using their free software (EB Tester v1.85)
Click to expand...
Can you measure charge/discharge curves with it? These are the most fundamental measurements in battery science.
 
Tim K said:
Yes I would but lots of items here in France are very difficult to obtain due to Covid and Brexit
Click to expand...
I ordered everything from China and it was sent through DHL, I believe you should be able to get everything to France without much trouble if this mail couriers are working fine.
 
danielfp248 said:
Can you measure charge/discharge curves with it? These are the most fundamental measurements in battery science.
Click to expand...
Yes! It does a lot. I work full time as active duty military and I do this stuff on the side on weekends. Ill share my next trials in a few days with actual data. For reference the electrodes ive made with the condutive plastic laminated copper mesh and graphite felt are 8x8 cm in a small 9x9x2cm PP container. From the exposed tab to farthest edge I register 1.5 ohms.
 
metaros said:
Yes! It does a lot. I work full time as active duty military and I do this stuff on the side on weekends. Ill share my next trials in a few days with actual data. For reference the electrodes ive made with the condutive plastic laminated copper mesh and graphite felt are 8x8 cm in a small 9x9x2cm PP container. From the exposed tab to farthest edge I register 1.5 ohms.
Click to expand...
Awesome! Looking forward to seeing your charge/discharge curves!
 
400USD seems a bit much for testing here...
Maybe we can consider group buys?
 
Hi All

I was looking at some prices for potassium bromide today and was thinking of maybe experimenting with chloride instead of bromide to keep experimental costs a bit down before switching to bromine. Has anyone tried other halogens yet?

I know chloride is a bit more aggressive so more precautions need to be taken. I then remembered seeing some experiments where Zinc Iodine and Zinc bromine where mixed which helps the Iodine/Bromine to settle better as they interact... Maybe a mixed approach would also be good to investigate.

I also checked the potential difference between the halogens salts and how many Watt hours theoretically could be stored per mole of solution (correct me if I am wrong: 2 electrons... coulombs...= +- 53A/h per mole * voltage):
Zinc Florine: 3.63v => 192 Watt/h per mole
Zinc Iodine: 1.29v => 68 Watt/h per mole
Zinc Bromine: 1.82v => 96 Watt/h per mole
Zinc Chlorine: 2.15v => 113 Watt/h per mole

When mixing these salts, the cell voltage can be calculated in the molar ratio e.g. 1x ZnBr : 2 ZnI2 => (1x1.82v+2x1.29v)/3 = 1.46v

ZnFl2 would store nearly double the W/h, but I think Florine is riskier/more expensive compared to chlorine/iodine/bromine? (speaking as non chemist here). The chlorine is readily available and stores more watts... so it sound worth investigating.

Has anyone tried alternative halogens? Any thoughts?

Anyway, I will be sharing my first 3D printed experimental battery design soon
 
Eiskuh said:
Hi All

I was looking at some prices for potassium bromide today and was thinking of maybe experimenting with chloride instead of bromide to keep experimental costs a bit down before switching to bromine. Has anyone tried other halogens yet?

I know chloride is a bit more aggressive so more precautions need to be taken. I then remembered seeing some experiments where Zinc Iodine and Zinc bromine where mixed which helps the Iodine/Bromine to settle better as they interact... Maybe a mixed approach would also be good to investigate.

I also checked the potential difference between the halogens salts and how many Watt hours theoretically could be stored per mole of solution (correct me if I am wrong: 2 electrons... coulombs...= +- 53A/h per mole * voltage):
Zinc Florine: 3.63v => 192 Watt/h per mole
Zinc Iodine: 1.29v => 68 Watt/h per mole
Zinc Bromine: 1.82v => 96 Watt/h per mole
Zinc Chlorine: 2.15v => 113 Watt/h per mole

When mixing these salts, the cell voltage can be calculated in the molar ratio e.g. 1x ZnBr : 2 ZnI2 => (1x1.82v+2x1.29v)/3 = 1.46v

ZnFl2 would store nearly double the W/h, but I think Florine is riskier/more expensive compared to chlorine/iodine/bromine? (speaking as non chemist here). The chlorine is readily available and stores more watts... so it sound worth investigating.

Has anyone tried alternative halogens? Any thoughts?

Anyway, I will be sharing my first 3D printed experimental battery design soon
Click to expand...
Bear in mind elemental chlorine and fluorine are gases, very poisonous and corrosive gases, so it is really hard to keep them properly contained in a battery system. For chlorine or fluorine you will have to go with flow battery designs - to properly store these gases - this is not easy, safe, convenient or cheap to do. If you want to go this route, make sure you know what you're doing.

Also consider that Bromine and Iodine are both quite reactive and will eat through most 3D printer materials, so you will need to either apply PTFE or similar coatings to your materials or print in materials like PTFE or CPVC (which is sadly not very easy). Iodine is the safest of the halogens, so go with that one if you're new to working with these materials.
 
danielfp248 said:
Bear in mind elemental chlorine and fluorine are gases, very poisonous and corrosive gases, so it is really hard to keep them properly contained in a battery system. For chlorine or fluorine you will have to go with flow battery designs - to properly store these gases - this is not easy, safe, convenient or cheap to do. If you want to go this route, make sure you know what you're doing.

Also consider that Bromine and Iodine are both quite reactive and will eat through most 3D printer materials, so you will need to either apply PTFE or similar coatings to your materials or print in materials like PTFE or CPVC (which is sadly not very easy). Iodine is the safest of the halogens, so go with that one if you're new to working with these materials.
Click to expand...
Gas.... wasn't thinking of that and looking at the solubility of chlorine at room temperature is not that great at either.

Regarding plastics, I am testing it with ABS. I did some research but all plastic manufacturers have no data available for halogens in solution. Only 1 manufacturer does list chlorine in solution as stable with ABS but chlorine out of solution as corrosive... hence I will be testing with ABS.

My final battery design intent is to remove the cathode and/or anode from the electrolyte after charging to reduce self-discharge. This too would reduce the contact of the halogen with the plastic. This will however depend on my tests where I will also see how the plastics cope.
 
Eiskuh said:
Gas.... wasn't thinking of that and looking at the solubility of chlorine at room temperature is not that great at either.

Regarding plastics, I am testing it with ABS. I did some research but all plastic manufacturers have no data available for halogens in solution. Only 1 manufacturer does list chlorine in solution as stable with ABS but chlorine out of solution as corrosive... hence I will be testing with ABS.
Click to expand...

Both bromine and iodine will react with ABS, so you sadly cannot use that without any treatment. They will also react quite fast with this plastic. If you want a cheap material for battery construction I would go with glass, which is stable against both bromine and iodine.

My final battery design intent is to remove the cathode and/or anode from the electrolyte after charging to reduce self-discharge. This too would reduce the contact of the halogen with the plastic. This will however depend on my tests where I will also see how the plastics cope.
Click to expand...

This is why Zn-Br batteries ended up with flow battery designs, to prevent discharge reactions from happening. However moving around elemental Bromine or perbromides is not easy to do, because of how reactive they are (special pumps are required) manipulating any meaningful quantity of these chemicals by hand is also not advisable because of how dangerous they can be.

My advice would be, do this at a very small scale - like using the swagelok cells I describe in my blog - as this will involve only milligram amounts of material and will allow you to experiment without putting yourself in any significant risk. Working with larger scales, even if it only in the 1-10g scale, can already lead to health hazards if you're not careful. If you learn about the batteries at the smallest practical scales you will be way better prepared for when you scale up.
 
danielfp248 said:
I have watched all of Robert's videos, I even decided to pay to become a member of his community to get access to several extra videos about this topic not available to the general public.

The videos have not been very useful though, mainly because of the following reasons:
  1. While Robert shares a lot of info about fabrication, he shares practically zero information about real results (no charge/discharge curves, coulombic efficiency info, self discharge rates, specific power/capacity, etc) so I have no idea how good or bad the batteries he made are.
  2. His choices are sometimes very odd, in particular his battery architecture deviates very substantially from what a modern battery looks like. For example the choice of a very thick phenolic foam separator causes very big internal resistance and heavily reduces ion mobility. These choices are likely to very heavily reduce both energy efficiency and specific power of the battery. The charge/discharge rates are also likely to suffer.
Because of these issues I have instead decided to reproduce the results of well documented research with high specific capacity values. In particular this recent chinese paper on highly efficient static Zinc bromine batteries (https://www.sciencedirect.com/science/article/pii/S2589004220305356). Since TPAB is hard to obtain, my first objective is to see what a battery made using TBAB can achieve within this same architecture.

Note that I am not saying Robert's batteries are "bad" just that because of the lack of information I can't tell and given some odd choices he has made I would rather go with reproducing published research instead.
Click to expand...
Funny, I’ve had the same feelings. I smile each time he describes the “3 types of people”. clearly, he’s saying that the least trustworthy of the 3 are those involved in battery development - and yet we accept all things on the channel at face value. Reminiscent of the ”frog and the scorpion”. :). That being said, I have no particular reason to doubt him.... I think his primary goal (and he‘s quite successful at it) is to inspire others to experiment. To take the published papers and dare to ask “why?”. After all, Flash Graphene synthesis wasn’t optimized on the basis of some quantum revelation. It was a grad student who said something like this... “if we can produce graphene with the power of high intensity lasers, why not try a simple spark discharge?“. Anyone wanting to look at Graphene seriously is in need of a cheap Raman Spectroscope. My old physchem graduate advisor wrote two books on various spectroscopic measurement systems.... he’d be impressed with what you can do with a 3D printer these days!
 
Last edited:
Eiskuh said:
Gas.... wasn't thinking of that and looking at the solubility of chlorine at room temperature is not that great at either.

Regarding plastics, I am testing it with ABS. I did some research but all plastic manufacturers have no data available for halogens in solution. Only 1 manufacturer does list chlorine in solution as stable with ABS but chlorine out of solution as corrosive... hence I will be testing with ABS.

My final battery design intent is to remove the cathode and/or anode from the electrolyte after charging to reduce self-discharge. This too would reduce the contact of the halogen with the plastic. This will however depend on my tests where I will also see how the plastics cope.
Click to expand...

bromine is an element (like most other gases) that exists as a liquid Under specific temps/pressures. The TPAB in the paper being referred to seems to be a pretty effective barrier to bromine migration. Is TMAP or TEAB equally effective? TBAP was a bit pricey, here in Canada.
 
danielfp248 said:
I treated my ZnBr2 solution manufactured from ZnSO2.H2O and NaBr2 with 3% hydrogen peroxide to remove all iron, waited 24 hours, filtered all the generated Fe solids, then added some metallic Zn foil to ensure all peroxide reacted and any elemental bromine was eliminated and waited another 24 hours. I then measured the resulting density of the electrolyte which puts its concentration at around 2.7M ZnBr2. I then added 0.5% Tween 20 to a sample of this electrolyte to build a battery.

The battery was built using a GFE-1 cathode pretreated with a 10% TMPhABr solution, a 0.2mm Zn anode and 15 layers of fiberglass separator. The cell was sealed with minimal compression of the layers and was set in an inverted configuration (cathode on top). Here are the results charging to 15mAh at 15mA, discharging to 0.5V:

View attachment 30221

View attachment 30219
View attachment 30220

The elimination of all the Fe within the electrolyte did give us better stability, improving potentials as a function of time and better voltaic efficiency. Overall energy density was around 25 Wh/L for this device. I opened up the device at this point to observe how the electrodes looked, absolutely no Iron oxide/hydroxide formation on the Zn anode, no dendrite formation and a slighter yellow coloring of the separator layers. If you're going to be preparing your own electrolyte from NaBr2 and ZnSO4.H2O it is absolutely fundamental to remove all the Fe using hydrogen peroxide.

I am going to build another battery with this makeup tomorrow and take it to larger cycle numbers to verify stability.
Click to expand...
How are you affixing the current collector to the Carbon?
 
Nitrous said:
bromine is an element (like most other gases) that exists as a liquid Under specific temps/pressures. The TPAB in the paper being referred to seems to be a pretty effective barrier to bromine migration. Is TMAP or TEAB equally effective? TBAP was a bit pricey, here in Canada.
Click to expand...

The problem with TPAB is that its solubility in ZnBr2 solutions is really low, so in practice you cannot get more than a 0.5M solution of TBAP+ZnBr2 which seriously limits your capacity. TEABr's perbromide is a liquid, so it will not be an effective way to sequester the Br unless you're able to move it away since otherwise its diffusion is going to be substantial, then TBABr is way more insoluble with ZnBr2 compared with TPABr. I was never able to get it to work in any effective manner because of this, even trying to add it as a solid.
 
Nitrous said:
Funny, I’ve had the same feelings. I smile each time he describes the “3 types of people”. clearly, he’s saying that the least trustworthy of the 3 are those involved in battery development - and yet we accept all things on the channel at face value. Reminiscent of the ”frog and the scorpion”. :). That being said, I have no particular reason to doubt him.... I think his primary goal (and he‘s quite successful at it) is to inspire others to experiment. To take the published papers and dare to ask “why?”. After all, Flash Graphene synthesis wasn’t optimized on the basis of some quantum revelation. It was a grad student who said something like this... “if we can produce graphene with the power of high intensity lasers, why not try a simple spark discharge?“. Anyone wanting to look at Graphene seriously is in need of a cheap Raman Spectroscope. My old physchem graduate advisor wrote two books on various spectroscopic measurement systems.... he’d be impressed with what you can do with a 3D printer these days!
Click to expand...
I agree, Robert does a great job sharing and getting people excited about chemistry. I support his channel and admire his work in this sense.

However, his Zn-Br battery designs are just not practical or efficient designs. Those foam batteries have huge energy efficiency losses and the jar designs he shared in his last videos about the topic have abysmal energy efficiencies as well. In both of these designs I would estimate you would get 10-15% energy efficiency out of them, which is not acceptable for a battery application.

Also the Chinese paper that started my journey in Zn-Br batteries is just hype, see this post about my comments on their experimental results https://chemisting.com/2020/09/12/zinc-bromine-batteries-can-they-really-be-that-good/
 
danielfp248 said:
I don't add any current collector to the carbon, see my Swagelok cell configuration here https://chemisting.com/2020/12/25/zinc-bromine-batteries-about-my-swagelok-cell-for-s9mall-scale-battery-testing/
Click to expand...
Thanks for that. I’ve been looking at PVDF as a polymer base for electrodes, especially in the context of bipolar electrodes in higher total voltage per cell. I was surprised to find out that there is information on bipolar configurations for LAB systems. Thanks for the link. Doug (I’ve been looking at the active solders for carbon/metal bonds.... very interesting stuff - see Ben Krasnow’s video on US assisted soldering)
 
danielfp248 said:
I agree, Robert does a great job sharing and getting people excited about chemistry. I support his channel and admire his work in this sense.

However, his Zn-Br battery designs are just not practical or efficient designs. Those foam batteries have huge energy efficiency losses and the jar designs he shared in his last videos about the topic have abysmal energy efficiencies as well. In both of these designs I would estimate you would get 10-15% energy efficiency out of them, which is not acceptable for a battery application.

Also the Chinese paper that started my journey in Zn-Br batteries is just hype, see this post about my comments on their experimental results https://chemisting.com/2020/09/12/zinc-bromine-batteries-can-they-really-be-that-good/
Click to expand...
You’re referring to the Zinc-Bromine Static Battery Paper, right?

A High-Performance Aqueous Zinc-Bromine Static Battery LujieGao12ZhuxinLi1YipingZou1ShuangfengYin1PengPeng3YuyingShao3XiaoLiang124​

It’s sad when peer review means nothing.....
 
Nitrous said:
You’re referring to the Zinc-Bromine Static Battery Paper, right?

A High-Performance Aqueous Zinc-Bromine Static Battery LujieGao12ZhuxinLi1YipingZou1ShuangfengYin1PengPeng3YuyingShao3XiaoLiang124​

It’s sad when peer review means nothing.....
Click to expand...

Yea, exactly that one. They calculate their capacity values with only 3mg of cathode material - which is the activated carbon they add to a whole other bunch of things that make up the cathode - for the specific capacity and energy values they use those 3mg plus the mass of ZnBr2+TPABr, ignoring the mass of the water which is critical since you cannot dissolve these things at higher concentrations. Total scam as you simply cannot build a battery without the other components. In reality, the values are 100x lower when you consider all the materials.
 
danielfp248 said:
Yea, exactly that one. They calculate their capacity values with only 3mg of cathode material - which is the activated carbon they add to a whole other bunch of things that make up the cathode - for the specific capacity and energy values they use those 3mg plus the mass of ZnBr2+TPABr, ignoring the mass of the water which is critical since you cannot dissolve these things at higher concentrations. Total scam as you simply cannot build a battery without the other components. In reality, the values are 100x lower when you consider all the materials.
Click to expand...
I am a peer reviewer. I remember getting asked by an editor to “rush a paper” through.... the author was very well known.... I refused to do it. The paper was published, but with changes. Peer review should be a critical review, regardless of the “name” or reputation submitting it. Glad I didn’t spend a fortune on TPAB :). My other thought was to look at bipolar LAB arrangements.... some interesting methods to explore to increase surface area of the electrodes. Lead acid may be old, but old is ripe for improvement :).
 
Daniel, have you looked at the technology being developed by e-Tech? It appears to be a plating technology, but the difference is that the metallic zinc is deliberately dislodged from the receiving electrode. Seems like a clever way of preventing discharge and ultimately, do away with dendrite formation (I'm guessing - I've not read the papers yet)

Energy Storage Technology | Renewable Energy Storage

e-zinc.ca e-zinc.ca
 
Hi Daniel.
I have been reading through your research/experiments with great interest as static zinc bromide batteries have been my main focus of interest for several years. They seem to be a natural contender for mass energy storage but receive little publicity compared to flow batteies. I have had good results but have never, until recently, been able to overcome the problem of massive self discharge. You do not make any comments regarding this (unless I have missed it), so was wondering how your cells perform in this respect. One thing I noticed is that you used graphite in your swagelock. I tried this initially and always found that the graphite resistance made this method next to useless. I believe the stainless steel, or any other metal for that matter, reduces it's efficiency. I make my test cells from a 3D printed container and get good results.
 

Attachments

  • cell.JPG
    cell.JPG
    154.4 KB · Views: 5
  • cell2.JPG
    cell2.JPG
    144.9 KB · Views: 5
Last edited:
svetz said:
That's interesting, are the results something you can publish here or provide a link to?
Click to expand...
Hi
I have attached a zip file giving STL files of the top and bottom if anyone wishes to make the part on their 3D printer. I have also attached a jpeg of the assembly in use. I clamp the assembly using 6 small (22mm) binder clips. These are real cheap on Ebay and are great for applications like this and for electrical connectors. Just put a 3mm screw through one of the holes in the clip and connect your wires via the screw. The test jig makes use of grafoil and materials of a similar thickness. It would probably be a good idea to put O rings (sponge not rubber) in both the top and bottom to get a better seal, although this is a personal preference. You still get a slight smell of Bromine, but not too bad with the window open ?. I use grafoil of about 0.1mm thick which I glue to parcel tape before cutting. I also use parcel tape on the other side of the grafoil which is not used for electrical continuity. This gives a much tougher electrode which does not break easily due to bending. The binder clips do not dig in so do not damage the grafoil quickly.
I will give some results on self discharge when I have done more testing, although I only have one of those cheap china electrical loads which are not massively accurate.
 

Attachments

  • Test cell.zip
    967.8 KB · Views: 10
You must log in or register to reply here.

Similar threads

D
My adventures building a DIY Zn/I flow battery
2
Replies
40
Views
4K
Vorg
Vorg
D
My adventures building a DIY Mn/Fe flow battery
5 6 7
Replies
161
Views
13K
Vorg
Vorg
D
My adventures building a Zn-MnO2 battery
2 3
Replies
65
Views
7K
danielfp248
D
T
Building a battery pack
Replies
4
Views
315
hwy17
hwy17
D
My adventures building a Zinc-Iodine battery
4 5 6
Replies
140
Views
13K
danielfp248
D

diy solar

diy solar
Back
Top