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Is this the Holy Grail of home energy storage for DIYers?
#1
I was watching this video, and I got really excited!



The video shows how to make a minimal architecture zinc–bromine battery (MA-ZBB). According to the papers:

Quote:... The ultimate figure of merit for feasibility in grid-scale energy storage system is $ per kWh over its lifetime (number of cycles) at a given energy efficiency, or the levelized cost of energy stored (LCOES). Fig. 5 shows the LCOES comparison of MA-ZBB against other battery chemistries and designs. Li-ion and Na–S batteries are expensive and have a life of ∼1500 cycles. Despite operating at almost 100% EE, their average LCOES is around $0.5 per kWh per cycle. Advanced lead-acid batteries have a limited cycle life, and hence has an average LCOES of $0.75 per kWh per cycle. The RFBs have an exceptionally long reported lifetime, which results in an average LCOES of less than $0.10 per kWh per cycle. However, if MA-ZBB can last for 10,000 cycles, like ZnBr–RFB, the projected LCOES would be $0.017 per kWh per cycle, placing it an order of magnitude below the rest of EES available today. ...


I would love to hear everyone's thoughts on this. Maybe there's considerable drawbacks I've overlooked..
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#2
Interesting idea. Definitely something where the batteries would need to be stable and not moving around. I would guess (still reading comments, and maybe watch a few other vids) that the solution when charged shouldn't be moved around. Altho, one of the commenters brought out that it is very similar to the way RedFlow works, which is a flow battery using ZnBr as well. But as Rob mentions, it has other agents in the solution.

One thing I wonder though is what the capacity of these batteries are. He didn't mention that in this video even though he had one on the bench he'd been charging. This is where the problems, feasibility, economics and scalability will come into play. If the battery he made on camera can only hold 1000mAh, then you'd need an awful lot of these to make them work for a house storage.

In a comment it is stated that the capacity is directly related to the amount of Zinc in solution. I suppose the more zinc you put into solution the higher the capacity. However, how much capacity is there in saturation?


Now if you have large amount of space (like several acres of land) then I think this idea would work great. I say this as it gives plenty of space to work with as you would could only build Up so far. I would imagine you would also need to keep an eye on solution levels, similar to Lead Acids, unless you could seal the containers good enough. But would need a vent hole for safety measures. This can still create acids if charged to fast, so those measures would need to be taken into account as well.

Because they must be charged at low amps, this is another reason for "many" of them, as you would need to be able to charge the bank at full amperage of your energy generators. He states that for each cell, they can only be charged at <100mA for best results. This is what we do with Lithium based cells here. However, they are "much" smaller compared.
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#3
(01-14-2020, 02:55 PM)vspin Wrote: I was watching this video, and I got really excited!



The video shows how to make a minimal architecture zinc–bromine battery (MA-ZBB). According to the papers:

Quote:... The ultimate figure of merit for feasibility in grid-scale energy storage system is $ per kWh over its lifetime (number of cycles) at a given energy efficiency, or the levelized cost of energy stored (LCOES). Fig. 5 shows the LCOES comparison of MA-ZBB against other battery chemistries and designs. Li-ion and Na–S batteries are expensive and have a life of ∼1500 cycles. Despite operating at almost 100% EE, their average LCOES is around $0.5 per kWh per cycle. Advanced lead-acid batteries have a limited cycle life, and hence has an average LCOES of $0.75 per kWh per cycle. The RFBs have an exceptionally long reported lifetime, which results in an average LCOES of less than $0.10 per kWh per cycle. However, if MA-ZBB can last for 10,000 cycles, like ZnBr–RFB, the projected LCOES would be $0.017 per kWh per cycle, placing it an order of magnitude below the rest of EES available today. ...


I would love to hear everyone's thoughts on this. Maybe there's considerable drawbacks I've overlooked..

Its an interesting watch but...  I didn't hear come away with the *key* info I was looking for  - e.g. voltage, amps, and power of the example battery.   Maybe I missed it? He alluded that a few amps discharge can be expected but wasn't clear what size of cell he was thinking of. He mentioned voltage going up/down/up during charging but didn't give an values or length of time.
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#4
(01-14-2020, 03:52 PM)OffGridInTheCity Wrote: Its an interesting watch but...  I didn't hear come away with the *key* info I was looking for  - e.g. voltage, amps, and power of the example battery.   Maybe I missed it? He alluded that a few amps discharge can be expected but wasn't clear what size of cell he was thinking of. He mentioned voltage going up/down/up during charging but didn't give an values or length of time.

You have to dig further down into the comments to get those answers.
Voltage is 1.85V per cell
Amps are based on surface area. He mentions that folding the electrode will give higher amp yields (I imagine like an air filter with all those folds)
Capacity is based on the amount of Zinc in solution
Charge rate is about 100-300mA. I'm guessing that is based on surface area, as well, but not sure
Discharge rate is around 1A
Each cell must be separate from another electrolyte wise. So you can't stack multiple plates in the same solution, like that of Pb batts.
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#5
(01-14-2020, 04:35 PM)Korishan Wrote:
(01-14-2020, 03:52 PM)OffGridInTheCity Wrote: Its an interesting watch but...  I didn't hear come away with the *key* info I was looking for  - e.g. voltage, amps, and power of the example battery.   Maybe I missed it?    He alluded that a few amps discharge can be expected but wasn't clear what size of cell he was thinking of.  He mentioned voltage going up/down/up during charging but didn't give an values or length of time.

You have to dig further down into the comments to get those answers.
Voltage is 1.85V per cell
Amps are based on surface area. He mentions that folding the electrode will give higher amp yields (I imagine like an air filter with all those folds)
Capacity is based on the amount of Zinc in solution
Charge rate is about 100-300mA. I'm guessing that is based on surface area, as well, but not sure
Discharge rate is around 1A
Each cell must be separate from another electrolyte wise. So you can't stack multiple plates in the same solution, like that of Pb batts.
Did you get a sense of the overall power density or more specifically a reasonable estimate of the power in the demo battery? 

 For example, a discharge of 1.8v@1a = 1.8watts per cell - which would be 1.8wh per hour.     A 2000mah 18650 cell has 7.4wh.   The sample battery would need to run  (7.4wh/1.8wh) = 4.1 hours be in the range of the power of a 2000mah 18650 cell.
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#6
(01-14-2020, 05:37 PM)OffGridInTheCity Wrote: Did you get a sense of the overall power density or more specifically a reasonable estimate of the power in the demo battery? 

 For example, a discharge of 1.8v@1a = 1.8watts per cell - which would be 1.8wh per hour.     A 2000mah 18650 cell has 7.4wh.   The sample battery would need to run  (7.4wh/1.8wh) = 4.1 hours be in the range of the power of a 2000mah 18650 cell.

True, I agree. The power density is only a fraction of that of Lithium based chemistries. However, there is a price difference. As I stated earlier, unless you have the space for these, they aren't really feasible. You'd need a lot of shelf space. The advantages would be that it's super safe, no explosions. It's super easy to build and cheap. It'd be a great system for those who are out in the middle of nowhere (forest dwellers for example) because of the space requirements.

When I get the garage done, I may try building some of these myself to see how easy and reliable they are.

Could you imagine having a solar farm, and under all the panels are banks of these cells? Have the solar panel connected to the batteries through an mppt charger, then connect the batteries to the main line heading to the main storage and/or inverter.
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#7
Just saw the latest youtube - https://youtu.be/OBIiSrodqjE - where he made 'solid' battery cells with same chemistry of the liquid ones and stacked 7 of them for 7 * 1..85 = 12.95v. He also said they (each cell) has about 4.5w.. which is 2432mAh. That sounds fantastic.. as that's not that far from an ordinary 18650 cell and only 2-3 times larger for same power - certainly 'in range' of practicality in my view. Of course we don't know the cycle(s) etc... but still.....

I must say - it looked pretty impressive!
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#8
Isn't Zinc Bromide expensive?
Where would you get it in the US or Canada?

Wikipedia says ~ $400/kWh
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#9
(01-17-2020, 11:00 PM)Bubba Wrote: Isn't Zinc Bromide expensive?
Where would you get it in the US or Canada?

Wikipedia says ~ $400/kWh


According to the Optimization and Design of ..., the estimated cost of Zinc Bromide is $2.3 to $3.1 per kg but I image the estimates are based on buying in large volume, and does not include other costs such as shipping. I don't know where you can purchase it in NA but you can get it in bulk on Alibaba. Robert Murray-Smith is going to be making a video on how to make zinc bromide electrolyte yourself but I wonder how cost effective that would be.

What's really important when building these cells is "$ per kWh over its lifetime (number of cycles) at a given energy efficiency," before going large scale.


(01-17-2020, 04:55 PM)OffGridInTheCity Wrote: Just saw the latest youtube - https://youtu.be/OBIiSrodqjE - where he made 'solid' battery cells with same chemistry of the liquid ones and stacked 7 of them for 7 * 1..85 = 12.95v.  He also said they (each cell) has about 4.5w..  which is 2432mAh.  That sounds fantastic..  as that's not that far from an ordinary 18650 cell and only 2-3 times larger for same power - certainly 'in range' of practicality in my view.    Of course we don't know the cycle(s) etc...  but still.....

I must say - it looked pretty impressive!

It does! I would LOVE to see his cell analyzed with a battery analyzer/cycler. The cell he made is different from the initial, and optimized versions that were created by Princeton University.
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#10
Bromine is more expensive, correct. It's easily obtained from Pool/Spa stores as it's used as a Chlorine replacement in spa/hot-tub sanitizing because it's stable at higher temps. But, this is mostly BromoChloro-5, or basically Bromine and Chlorine bonded together. Probably wouldn't be able to use it without having to process it first.

However, you can get Bromine Water, which is Br2 dissolved in water
https://www.labsupplyoutlaws.com/chemica...-500ml.htm
This costs $125USD

Not sure how much of this solution you'd need, though, to make the batteries.
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