Battery Liquid Refilling Stations?

safe

safe

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Battery Liquid Refilling Stations?

Here's a rather strange idea...

A battery consists of a cathode and an anode (something physical and metal usually) that is brought in contact by the acid. (LiFePO4)

Now this might be so chemically dangerous that it's a terrible idea because if the acid spilled onto someone's body it could cause serious harm. I know that I got a very minute spray from opening a battery and the burns were so severe that it took days before the pain subsided completely and the skin recovered.

But just think...

What if you could go to a "LiFePO4 Refilling Station" and simply get a refill of your acid? (doing the same as giving a recharge)

:arrow: Filler up?

Or bad idea... too dangerous?
 
Sounds like you're describing a flow battery.
http://en.wikipedia.org/wiki/Flow_battery

A NiMH cell is kind of a closed-circuit flow cell.
The hydride tank instead of being outboard is combined with the anode & cathode under a single housing.
This is why it's my feeling Chevron prohibited anyone from producing NiMH cells larger than 15 Ah in size.
If large form factors would be readily available it wouldn't take much for some backyard tinkerer to put together his own flow battery.
With little more than some plumbing from Home Despot a pressure tank to store hydrogen which could be made at home to store excess PV panel output it could conceivably kick-start a grass-roots hydrogen economy.
With only smaller cell sizes available it's too finicky & not cost effective.
 
The Wiki link Toorbough ULL-Zeveigh gave will lead you to the Vanadium sulphate "flow" battery. I researched that a couple of years back, but I didn't find any news about commercialization then, I'll have another look. Safe is on to a really good idea here, I don't know why it isn't getting any further. If you find anything let us know. BTW it won't be LiFePO4 based - Vanadium is good cause it has 5 valency states. :wink: :D
 
Vanadium Redox Batteries are, it seems, highly developed for LARGE, STATIC setups to replace batteries. See:
http://www.vrbpower.com/technology/faqs.html#faq3
Here's a relevant extract:

3. What is the Energy Density of the Electrolyte (Wh/litre?)?

This is a function of the application requirement and can range from 15Wh/litre to 25Wh/litre as measured on a round trip charge/discharge cycle. These are actual measured and delivered values and should not be confused with ideal theoretical values which could be as high as 28 to 43Wh/litre. Other energy storage systems often quote theoretical values.
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4. What is the Power Density (W/kg)?

This is a function of the system cell stacks and electrolyte. For large systems this is 100-150 Watts/kg and for the small systems about 80 Watts/kg.
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5. Does the Electrolyte Self-Discharge?

Once charged the Electrolyte has very low self discharge as it is circulated through the cell stacks. If charged and stored separately it can remain charged indefinitely.
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6. How Many Hours are Required to Charge for Each Hour of Discharge?

You can charge the system as quickly as you discharge it. The system provides a roundtrip efficiency of 65 - 75%. Therefore with the input of 25 -35% additional power to cover the losses, you can get 1 hour of discharge for every hour of charge. A practical charge discharge ratio for optimal performance is about 1.8 to 1.

-----------
So the power density looks feasible (12.5kg per KilowattHour) but the recharge ratio is a bit slow, unless you use Safe's notion of "refuelling" at a "converted gas station". It's not rocket science.
 
:idea: It does appear to be a good idea.

However, the danger of spilled acid needs to be taken seriously. Unlike gasoline which can be spilled on the hands without any problems all it would take is a drop of spilled battery acid that the person then uses to touch their face or eyes and you have a serious problem.

The acid becomes the fuel.

I remember long ago looking into an idea that used Borax as a chemical in a similiar reaction which turns out to be very good for holding hydrogen. The problem was that while the liquid was not very toxic it was also very inefficient to charge up. (well, to form into the chemical that is active) Taking the same idea and using an acid might be the way to do it.

It's less dangerous than 3,000 volts in a supercapacitor and if you are going short distances you might not even need to go to the refilling station.
 
As I understand it the electrolyte is Vanadium Sulphate. I don't know how toxic/corrosive it is, but it's not an acid. Safe, you are fixated on Lead-Acid - you seem to think that the electrolyte in a battery must be an acid. I'll try to find out the safety aspects of that electrolyte.

[later] ... apologies! :oops: it is an acid but...

Here is an extract from:
http://www.ehponline.org/members/2007/115-7/EHP115pa358PDF.pdf

-------
VRBs are far greener than other batteries, as they lack potentially toxic metals as lead, cadmium, zinc, and nickel, which can contaminate the environment at all phases of the conventional battery life cycle. VRBs’ most toxic component is the sulfuric acid of the electrolyte, which is only one-third as acidic as that in a lead-acid battery. But unlike lead-acid batteries, the electrolytes in a VRB function indefinitely, eliminating the disposal problem.
Vanadium itself has very low toxicity, and the batteries are designed to contain electrolyte
spills. “We have the best environmental footprint of any storage technology, ” says Simon Clarke,
executive vice president for corporate development at VRB Power Systems.
------

N.B. that "VRBs’ most toxic component is the sulfuric acid of the electrolyte, which is only one-third as acidic as that in a lead-acid battery"

I think that dismisses your worry about the electrolyte, Safe.
 
Just so you understand there is no "acid" in a LiFePO4 battery cell. The active ingredient is Lithium Iron Phosphate which is a powder - not a liquid,
thus no possibility of spilling anything on your skin. Furthermore, the worst that could happen would be if a cell were severly overcharged to rise to
a degree of 180 Celsius it would "vent" and produce a puff of Lithium gas. You wouldn't want to sniff it - but it would not burn your skin.

Best,

Don Harmon
 
Partially right. The pH of the electrolyte in a LiFePO4 cell is pretty neutral, so is neither a strong acid or a strong alkali.

Lithium is a soft, white metal, not a gas, so it's not lithium itself that's vented when a cell gets abused. The electrolyte in most lithium chemistry cells is some form of lithium salt, disolved in an organic solvent, often something like ether, although this is effectively a polymer, rather than a free liquid. If it vents, then the major risk is from the flammability of the traces of organic solvent that may still be present, although this will only be in very small volumes from a LiFePO4 cell. It was this flammability of the solvent electrolyte, combined with the high reactivity of lithium metal used as the cathode, that made early lithium batteries seriously scary in the event of abuse.

It's the cathode in a LiFePO4 cell that is fabricated from Lithium Iron Phosphate, in the form of sintered phosphate powder onto a lithium foil, I believe. The anode is most often graphite, or a graphite coated foil.

Jeremy
 
Jeremy Harris said:
Partially right. The pH of the electrolyte in a LiFePO4 cell is pretty neutral, so is neither a strong acid or a strong alkali.
Click to expand...
It seems that you need some type of liquid in order to allow chemical reactions to take place more freely. If everything were solid inside you would have a far more durable battery, but I just can't imagine how you could do that.

A neutral chemical that can be swapped out at a "refilling station" makes for the ideal fuel supply. The cathode and anode just need to not wear out... it's the electrolyte that does the "work" of moving things around.

:arrow: So is this all consistent with the idea of replenishing the cells when the charge is low? Would the idea work with LiFePO4?

:arrow: Could the "refilling station" also be given the task of purifying the liquid while in storage so that over time there is no decay problem? (this might effectively make the battery last forever as long as the cathode and anode don't run out)

My battery chemistry knowledge is still weak... :?

Filler up?
 
First of all there is no such thing as a re-filling station for LiFePO4. Unlike SLA there is no chemical reaction that takes place within a LiFePO4 cell. Instead, electricity is generated by an exchange of ions. Hence the term " Lithium - ion" or Li-on.

Therfore, to acheieve a LiFePO4 "filling station" you would have to either be swapping out packs or "modules" or diagnosing and replacing weak or damaged individual cells within a pack. Or maybe simply charging up a good pack with a speed charger in 20 minutes.

Capiche ?

Don Harmon
 
Technically yes. But there are a whole set of differences between SLA and LiFePO4. Since the original proposition put forward was concerning the idea of LiFePO4 Refilling Stations, all I am trying to say is that this idea can only work in one of two ways:

1) You would swap- out discharged packs with freshly charged packs.

2) You would "fast charge"the existing packs right in the vehicle.

Either method would probably require the same amount of time to do - thus the whole idea really has little merit IMO. The term "refilling" does not have any context to batteries whether they are SLA or LiFePO4 or any other chemistry for that matter. It is simply a contradiction in terms. Perhaps if you re-named the concept a "Recharging Station" we would be able to better comprehend what the author is trying to suggest?

Don Harmon
 
I think the confusion here is the misconception that a lead-acid, battery can be recharged by changing the water electrolyte of a discharged battery with fresh sulfuric acid. This comes from a confusion of cause-and-effect regarding how the specific gravity of the electrolyte indicates the state of charge. The changing specific gravity of the electrolyte is an effect, not a sole cause of the batteries state of charge. The redox reactions takes place on the lead (anode) and lead oxide (cathode) plates, so merely changing the electrolyte back to nice, high specific gravity sulfuric acid will not reduce/oxidize the PbSO4 on the plates back to Pb And PbO2.

In short, changing the electrolyte does not recharge any kind of conventional battery.
 
The important elements of this thread are in danger of being swamped by LiFePO4.
1. FORGET LiFePO4 for the purposes of this thread.
2. The significant point is a chain of "battery refueling stations".
3. The most likely candidate for this is the VRB (Vanadium Redox Battery).

VRB has been highly developed for STATIC applications (see http://www.vrbpower.com/technology/index.html)
As I pointed out above the watthours per kg (80) seem suitable for our application. We just need to find out why they have neglected TRANSPORT (i.e. non-static) applications. And then we need to persuade them to change tack! :D
I just emailed them as follows:

I am interested in VRB for electric bicycles. It would seem that 80watts per kg energy density would make this possible. Why have you ruled out non-static uses of VRB? With a refuelling infrastructure it would seem possible to use your technology to replace petrol/diesel transportation systems.
 
I am curious, since I can find no such "VRB" Bike Batteries and wonder if they even exist ? All the information regarding this technology relates to large installations to store energy from wind farms or possible solar installations. I don't see this being scaled to use on an e-bike ? Do you have some information to share that shows small scale development happening that isn't published ? Or are "wishing" they can develop a product for this market ?

Don Harmon
 
Don Harmon said:
Or are "wishing" they can develop a product for this market ?
Click to expand...
This is a "theoretical thread" about the abstract concept of being able to somehow replenish a battery by physically replacing the liquid inside the cell rather than having to electrically reverse the chemical reactions that go on inside.

:arrow: It might be impossible with LiFePO4 for technical reasons. At least for the electrolyte alone.

Like I've said before I'm no battery chemistry expert, but the idea does seem to exist for some battery chemistries. It would be "nice" if it could work with LiFePO4, but some doubts about the technical possibility have made that uncertain.

Would it be possible to first drain the electrolyte, then flush the cathode and anode with a cleaning solvent (to get it back to something more "raw") and then refill the electrolyte? That might reset the battery to it's new and filled state.

:idea: Thoughts?

This will obviously wear out the cathode and anode, but that might be the price of getting an instant refill. :?

Honey?

Yes.

The car needs some new cathodes and anodes could you go down to WalMart and get some new ones?

Oh all right... :(
 
Safe, if you are still talking about LiFePO4, since that is the title of this thread - please understand there is no "electrolyte" that can be "poured out" of a LiFePO4 battery. They come in two flavors - one is a bunch of foil packs and the other is a bunch of hard metal cylinders like a standard AA Battery. Neither one would be able to be opened and "re-filled". The only thing you can do is re-cycle them. Thus your concept of a "refilling station" just makes zero sense. Now if you want to re-phrase your concept to say "re-charging" station then it might make more sense. See my previous post regarding how that might apply. As far as "theoretical" goes I guess you can make up anything in your mind for "refilling" like non-existent fuel cells, etc. But take LiFePO4 out of the prefix, please.

Thanks,

Don Harmon
 
Personally, I think that we're stuck on the concept of liquids. A tank of this, refilling that, in general.

I think it is easily feasible to use "refilling stations" swapping batteries or quick-charging. At this time, it is much more feasible to simply swap batteries by developing some sort of quick-release battery system standardized across vehicle manufacturers. The goal is an infrastructure where the average consumer can drive in, press a button to have a mechanical device do the heavy lifting, and pay in less than five minutes. Sell the first battery with the car, and pay a few bucks to replace the low battery with a freshly-charged one. The gas station, instead of selling fuel, sells freshly charged (though used) batteries, in much the same way they sell exchangeable propane tanks. They then charge you for the service of recharging batteries, and maintaining the pool of batteries (minus overhead and enough profit to make it worth their while).

The other model would be just to recharge the battery in the car. Drive up, plug in, and pay. To be a good option, based on our societal expectations based on gasoline, it needs to be fast, at about 5 minutes. That's a 12C-20C charge rate. The technology isn't there yet, though with a123s, it isn't that far off. To do this in multi-kwh packs, we're talking about a whole crapload of current, so special infrastructure at the station is necessary. That might mean the pack voltage would have to be pretty high, like 480v. With a Prius-like platform, we're talking about ~300Wh/mile, so for a 50-mile range we're talking 15kWh, and ~400 amps to charge the thing in 5min. Those numbers actually didn't come out as bad as I had expected. :p
 
If we must generate a new infrastructure, then I think the Tata air car wins hands down:
http://en.wikipedia.org/wiki/Air_car or http://news.bbc.co.uk/2/hi/science/nature/7243247.stm . It only requires a common-or-garden compressor to fill the tank in 2-3 minutes.
Garages currently often have such compressors already or they're not too expensive to get. However, that leaves us on our bikes! I guess LiFePO4 battery swapping would be possible, but the capital cost would currently be enormous and there's the issue of trust: is the battery you're swapping with me any good?
VRB (Vanadium Redox Batteries) are well developed for static applications. I hope that my email will bring some answers as to why it's not been thought practical for transport.
 
Oh, now that has energy density issues that make SLAs look great.

Still, any massive transportation changes are difficult. While we're still driving cars with tanks of burning fossils, this would be a great help: http://en.wikipedia.org/wiki/Crower_six_stroke
 
lazarus2405 said:
Oh, now that has energy density issues that make SLAs look great.
Click to expand...
:? :shock:
Energy density? I guess what matters is range and this website:
http://www.dancewithshadows.com/autoindia/tata-mdi-compressed-air-car.asp
says:
"The cost f the car is expected to be around £4,000 and would have a range of around 300km between refueling, said a report. It would have a top speed of around 60kmh using air alone and 200kmh using an air and fuel combination engine, it added."
So the range is OK. I don't understand what energy density has to do with it?
 
Yah, but what kind of pressures are the tanks holding back?

I'm guessing somewhere in the 3kpsi range. Your average compresser runs up to a max of 130 or so.
 
:arrow: What is in a LiFePO4 cell?

:arrow: Is it solid or liquid?

Jeremy Harris said:
Lithium is a soft, white metal, not a gas, so it's not lithium itself that's vented when a cell gets abused. The electrolyte in most lithium chemistry cells is some form of lithium salt, disolved in an organic solvent, often something like ether, although this is effectively a polymer, rather than a free liquid. If it vents, then the major risk is from the flammability of the traces of organic solvent that may still be present, although this will only be in very small volumes from a LiFePO4 cell. It was this flammability of the solvent electrolyte, combined with the high reactivity of lithium metal used as the cathode, that made early lithium batteries seriously scary in the event of abuse.

It's the cathode in a LiFePO4 cell that is fabricated from Lithium Iron Phosphate, in the form of sintered phosphate powder onto a lithium foil, I believe. The anode is most often graphite, or a graphite coated foil.
Click to expand...
:arrow: So we have our answer...

The CORRECT answer is that LiFePO4 has SOLID cathodes and anodes and a LIQUID that allows the chemical process to take place.

Of course... gosh... I was being so stupid... why didn't I remember that in order to have a chemical reaction take place I need to have some electrolyte to allow the transfer to take place. Oh well... I guess since I'm an AMATEUR to battery chemistry it's okay for me to not know much about it. It's not like I'm in the business of selling anything and getting such a major thing wrong.

That would be pathetic. :wink:

Here's a good source to go to for research:

http://www.lifebatt.com/asksparky.html

"In contrast, overcharging LiFePO4 battery cells just one time will disable them by damaging the ion-transference capability of their electrolyte chemistry. During normal operation, the LiFePO4 electrolyte material remains relatively unchanged as cations and anions move through the electrolyte between the anode and cathode materials of the cell during charge/discharge cycles. The electrolyte material can also be damaged when totally discharging the LiFePO4 cell under load. These two conditions must never occur and strict thresholds must be established when charging and discharging each LiFePO4 cell within the entire battery pack to prevent this."

Correction: Electrolytes can be solids too... see below...
 
Sorry, Safe, but the electrolyte in LiFePO4 cells isn't a free liquid at all, it's bound up as a polymer. There's a YouTube video somewhere showing them being made, during which you can see that it's a "dry" process.

Jeremy
 
Jeremy Harris said:
Sorry, Safe, but the electrolyte in LiFePO4 cells isn't a free liquid at all, it's bound up as a polymer. There's a YouTube video somewhere showing them being made, during which you can see that it's a "dry" process.
Click to expand...
Wow... that's a shock. :shock:

(proves that I'm not a battery chemistry expert)

So it's possible for an electrolyte to be a solid and not a liquid.

That's rather bizarre... :?
 
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