low voltage lithium recovery

the principal is the chemistry of the lipf6. uranium hexafluride is called yellow cake, which you may be familiar with.

another perflourate is tungsten hexaflouride which we used in the gas phase to make tungsten depositions on the surface of the silicon wafers in the furnace tubes to make the metal 2 layer.

i consider all the hexaflouride heavy metals to be carcinogenic is very tiny doses.

it was the cause of an epidemic of glial carcinomas of the brain at oak ridge and i consider it the source of the neuroglial blastoma that took the life of one of our technicians who worked on the vacuum pumps for the metal 2 deposition furnaces.

if you intend to follow through on this you will likely be carefully examined by the people who you ask to sell you these chemicals. i think you will be disturbed when you find out the cost of these types of specialized reagent grade hexaflourides.

about 30% of the lithium from the lipf6 is consumed in the formation charge, deposited into the intercalation pores of the carbon.
 
Thanks for the heads up on the dangers of lipf6. I haven't tried to source lipf6 as yet, I shall post any results on that.
I was though presently surprised to find that ec:dmc is not expensive ( takes a bit of searching to get past the main sellers which are very expensive). Fortunately only a small amount of lipf6 is required once you have the electrolyte ( 1 to 1.2 molar).
Another danger is if water gets into the electrolyte, with consequent hydrogen and hydrogen flouride being produced.
Any of this experimenting really needs to be done in a glove box with argon or similar gas, there might be some simpler methods to create a low moisture environment. Its probably beyond most diy backyard ebikers to try rejuvenating cells by electrolyte flush and new lipf6 electrolyte.
Just for interest sake here is an a123 electrolyte composition from one of their recent patents ( by Cho) :
rechargeable battery comprising a nonaqueous electrolyte solution comprising a lithium salt, LiPF6, at 0.6-2 M and an organic solvent mixture which includes 35 vol. % ethylene carbonate, 5 vol. % propylene carbonate, 50 vol. % ethyl methyl carbonate, and 10 vol. % diethyl carbonate, and at least one additive containing a sulfonyl group, ethylene sulfite, at 0.1-5 wt. % and vinylene carbonate at 0.2-8 vol. %.
One of the ingredients ( I think its the propylene carbonate?? ) makes it non-aqueous i.e. commonly called polymer type lithium.
Interesting to note no dmc is used: 35% ec: 50%emc:10%dec.
 
there is no documented correlation between heavy metal hexavalent flourides but there was an epidemic of neuroglial blastomas at oak ridge when enrichment was begun during the war. it was not reported and is still not comon knowledge but my major professor had literature about it because of his background in nuclear research and antinuclear activism which was how i learned of it. i was not able to interest the family of my technician in pursuing his neuroblastoma cause so nothing ever came from that.

lithium is not a heavy metal. lipf6 has no known carcinogenic indications that i am aware of, but i would recommend you understand the world you have now decided to investigate. i doubt if you will ever be able to obtain these chemicals in any case because of their expense and the nature of how business is done with specialty chemicals. you might even expect a call from a guvment agency.
 
Dont worry I'll be posting progress, whatever happens.
Some calculations:
Seems that Lipf6 is used at either 1 mol/litre electrolyte or 1.2mol/L electrolyte ( from supplier data and various research papers). I mole of lipf6 =152grams approx.
So 1 litre of electrolyte would require 152grams of lipf6.
Lipf6 can be bought in powder form, since I will need dmc:ec to flush cells, lipf6 can be added to unused dmc:ec to make the new electrolyte solution. Seems its commonly sold in 500gram bags, that would be enough for 4 litres electrolyte approx.
No idea how much electrolyte is required for each cell.
The volumes of electrolytes and lithium salt being produced to meet the lithium battery market would be huge, it looks like electrolyte is available at low cost. Lipf6 remains to be seen what is available price.
 
There are some common abbreviations for electrolytes for lithiums with lipf6:

popular commercially available non-aqueous electrolyte,
LP 71 (1 M LiPF 6 in EC / DEC / DMC in a weight ratio of 1: 1: 1),
LP 30 (1 M LiPF6 in EC / DMC in a weight ratio of 1: 1),
LP 40 (1 M LiPF 6 in EC / DEC in a weight ratio of 1: 1),
LP 50 (1 M LiPF 6 in EC / EMC in a weight ratio of 1: 1)
 
On the first page of this thread, I mentioned a research paper that rinsed the negative electrode with water and they found the graphite structure was the same as when the cell was new ( i.e. removed the sei layer). I found a link that has the whole paper
http://www.researchgate.net/publica...in_Li_ion_cells_and_calendar_life_predictions

The section of the paper that mentions cleaning the graphite layer is very brief they say
Negative electrodes, dismantled after more than 1 year
̄floating at a charged state at 60degC, were rinsed with water,
vacuum dried and, assembled in a coin cell versus Li. These
recovered electrodes exhibited an ability to cycle lithium at
the same initial specific capacity and polarization, thus,
demonstrating the stability of the carbon structure. In the
same way, the positive material on both cobalt and nickel
based electrodes exhibited their starting crystalline structure
with no modifications) and no additional phases were observed
in the X-ray data.

This also leads to another possible method of rejuvenation of a cell, but involves opening up the cell and separating the
sheets. Fortunately the lithium salts are soluble in water.
The cell would have to be rebuilt ( if the graphite layer is still in a useable ( not severely cracked) state) and new electrolyte added. Of course all traces of water would need to be evaporated. It would be extremely time consuming process, deionised water would need to be used most likely.
It would be possible to flush a cell with deionised water without dismantling it, but would it be possible to remove all the water after the flush?? The water will react with the electrolyte though producing hydrogen and hydrogen fluoride gas, so it might be a dangerous thing to try.
 
never say never
I realise that even extremely low concentrations of water can contaminate a cell. But this is not about adding water to a good cell. The reason for doing so is to remove lithium products from a spent cell ( as can be done with dmc/ec),
will there be an exothermic reaction?
will any heat be generated?
will hydrogen gas be produced?
will hydrogen fluoride or hydrofluoric acid be produced?
Will it catch fire, will it explode?

I think there is only one way to find out ( with safety in mind of course), it would be a much cheaper process to flush a cell with water and dry it, rather than using dmc/ec or other electrolytes to flush the cell.
I shall video the attempt and post when I get around to it.

I welcome any predictions on the outcome of the experiment.
 
I opened the gas vent hole in a cell, and put it in a glass of de-mineralised water, some minimal gas given off, tested the gas with simple flame test, gas popped so its hydrogen as expected. Since the vent hole is quite small it will take alot of time for the water to get into the cell. After about 3 hrs there is still small amount of gas being produced. No heating of the cell at this time.
video of the test:
View attachment P1090428.mp4
 
after 24hrs still slow bubbling of hydrogen occuring, the water is starting to turn slightly milky colour.
 
from a patent
http://www.google.com.ar/patents/US6383688
a fairly simple method to reduce water content of electrolyte solution to low levels using nitrogen gas.

Commercially available dimethyl carbonate (hereinafter referred to as DMC) and propylene carbonate (hereinafter referred to as PC) were used. The initial water content of the solvents were 736 ppm and 494 ppm, respectively. Through 4 liters of each of the solvents, dried nitrogen gas was led via a glass capillary at a flow rate of 3 liters/minute at room temperature for 24 hours. The resultant water content of each of the solvents was 55 ppm and 12 ppm, respectively. The both solvents were heated for 3 hours while continuing the nitrogen gas flow. Then, the final water content of each of the solvents was 1.3 ppm and 0.8 ppm, respectively.

After cooling both of the above solvents in a thermostat to about 18° C., they were mixed together in a volume ratio of 4:6. In the mixed solvent, lithium hexafluorophosphate was dissolved in a concentration of 1 mole/liter in a nitrogen gas atmosphere in a manner where the rate of the addition of lithium hexafluorophosphate was controlled so that the temperature of the solvent did not exceed 20° C. The water content of the resultant electrolytic solution was 2 ppm and the free acids content, converted to hydrofluroric acid content, was 7 ppm.
 
GM Motors has three patents which are methods to rejuvenate lithium batteries by flushing with electrolyte to remove components of sei layer, and then refill with new electrolyte ( containing lithium salt : lipf6 etc).
The three patents are aimed at large pouch cells but can apply to any of the main lithium battery types.
First three patents in this link
https://www.google.com.ar/search?tbm=pts&q=lithium+battery+rejuvenate&gws_rd=ssl
 
Makes me think of servicing a car, new filters and oil and you are good to go again :lol:
 
A few notes on the cell that I soaked in water:
A note of caution: if you put a cell that uses pure lithium metal in water it will likely explode/catch fire when the water reaches the lithium metal ( commonly found in aa lithium batteries), these experiments I'm doing are only for lithium iron phosphate,
lithium cobalt oxide and lithium manganese oxide or similar. The dont use pure lithium metal strips.

I left in water for about 30hrs, bubbling had stopped ( or extremely slow). Water had turned slightly milky. There was no reaction of the water with calcium carbonate ( i.e. poured on concrete). Hydrogen fluoride or hydroflouric acid is extremely corrosive and dangerous, so the water was disposed of safely as it would likely contain hf acid, it was not a strong acid as the glass the cell and water was contained in did not become etched. Though its still best to not get in contact with the water/acid left over.

The glue that held the blue plastic on the outer casing of the cell dissolved in the weak acid solution, so it might have caused the milky look to the water. The plastic was easy to remove after soaking cell in water ( almost impossible to remove completely before the test), so the cell is now shiny stainless steel only on outer case. There was some deposits around the aluminium electrode on the top of the cell, which seemed to dissappear once I washed the cell after taking it out of the water ( just using normal tap water on outer parts of cell only).

I then renewed the water and soaked the cell again, hardly any hydrogen given off. So it appears the reactions have finished.
Assuming the water found its way into all of the cell. The cell had been quite distended when last charged, the cell now has no pressure on the outer walls, which suggests some of the sei layer has been removed. There was no gas pressure build up in the cell, the gas safety valve ( just a tiny piece of very thin copper) was in tact, I broke that valve in order to give access for water into the cell.

So next step is to dry out the cell, I will leave it out in the sun and try to evaporate the remaining water/acid out of the cell.
It will almost certainly be necessary to dismantle the cell to see if all the water/acid has been removed.
Still working on finding low cost source for lipf6, at this stage $75uds/500g is best I have found. Considering only 152g/Litre of electrolyte is needed, it appears at this stage that the costs involved will be in the range of the diy backyarder.
( assuming shipping costs are low and no problems with customs).

So just to summarise:
Ideally a flush with emc or dmc or both, will remove sei layer components. A refill with new lipf6 in electrolyte ( dmc/ec or similar) should regain capacity.
Here I've flushed a cell with water to see if it will do the same as dmc/ec flush. I doubt it will work as well dmc/ec flush, as the reaction of water with electrolyte produces hydrogen and hydrogen flouride, which may lead to other products being formed in the cell. But the water should still remove some sei components since they are soluble in water.

The cell was discharged before the experiment, there was no explosion/fire etc, only a slow production of hydrogen gas as the water made its way into the cell. It appears that the ingress of water into the cell is quite a slow process given the gas production is very low and no heat formed in the cell.
The acid produced appears to be a weak acid, so this experiment has shown at least its a safe procedure in this instance.

I would think that anyone with contacts in battery factories in china, the cost of electrolyte and lithium salt will be extremely low due to the huge production numbers of these chemicals.

pics of the cell after water soak for 30hrs:

View attachment 1

post water1.jpg
 
was thinking along those lines.
Trying to keep things simple as possible: one way to get nitrogen atmosphere is to burn off the oxygen from normal air.
Thought:
since it looks like its going to be quite complex to do a flush and refill with correct electrolyte/lithium salts, not to mention some expense. Is there a simple way to at least try a method to increase lost capacity, using commonly available materials.
There may be a way:
ethyl acetate ( found in nail polish remover) has been used in lithium cells alongside the dmc/ec electrolytes ( in order to lower the temperature range)
This paper on page 65 mentions some studies that used it.
http://repository.lib.ncsu.edu/ir/bitstream/1840.16/2016/1/etd.pdf
the work of Herreyre et al.
showed that EA and MA can be used as co-solvents for low-temperature
electrolytes. They reported excellent results using EA or MA. For example, by using
EC/DMC/EA with 1M LiPF6
with vinylene carbonate as an additive in LiCoO2/graphite cells, the charge capacity
at -30 oC was between 88-95% of that at room temperature. In
addition, it was shown that capacity fading at high-temperature storage is comparable with
cells using state-of-art electrolytes (0.05 % per cycle).

Metallic lithium easy and relatively cheap to get from AA batteries that use it.
Idea: dissolve some lithium in ethyl acetate ( I'm assuming here that it will dissolve in EA
I haven't looked that up as yet)
Add that to a lithium cell thats lost capacity in order to resupply the cell with lost lithium. So basically no change to the
cell apart from open the gas vent top up the cell with a small amount of EA with lithium dissolved in it.
It may be a simple way to add additional lithium. If the cell has no swelling but has lost capacity it may indicate that its a lack of lithium, rather than thickening of the sei layer that is the issue. On a swollen cell due to sei thickening I'm guessing the effect of adding lithium wont be as effective as a cell that is not swollen ( i.e. resistance across the sei layer is still relatively low).
It wouldn't be as effective as removing sei components with a flush of electrolyte, but it might have some effect.
It appears that EA is compatible with dmc/ec etc, only a small amount would be required.
I think I'll make that my next experiment, mainly because the ingredients are readily available and cheap. One issue could be other additives in nail polish remover ( alcohol etc), the bulk of it though should be EA, and the alcohol would likely evaporate out pretty quickly. Another issue of course is opening the vent to the atmosphere allowing some moisture in, I doubt it would be a problem, as long as the prodecure if fairly quick, and the vent closed up again in a short time period.
 
something about ethylene acetate in lithiums:
used alone as electrolyte it tends to delaminate the graphite ( from one of the previous articles). So it might work alone as an electrolyte for some time, if lithium can be dissolved in it, but longevity of the cell will likely be low. Also it has a lower voltage than using dmc/ec etc, from memory it was around 3.4v? It might be worth a try though.
 
just looking up ethyl acetate in nail polish remover, seems it has quite a few other chemicals in it, they can be removed
as in this vid
https://www.youtube.com/watch?v=ua9dzsj6ecA
but too complex for me.

Not sure if I posted this before but here is a paper in great detail on rejuvenating lithiums using method of adding new lithium
http://www.researchgate.net/publica..._Methods_for_Spiral-wound_Lithium_Ion_Battery

It shows the method using a123 22650 cells by taking off the bottom cap, they soak it in dmc:ec with lipf6, then discharge the cell to a piece of metallic lithium in order to refill the cell with missing lithium ions.
They go into another method which might not be very useful.
 
did an experiment using a small 220mah lithium cell. The cell was puffed and wouldn't hold voltage, I took off the outer pouch,
unwrapped the layers and put all the layers in demineralised water. I was expecting to see a large amount of hydrogen gas, but no gas was produced, I didn't see any bubbles. This leads me to think that most of the electrolyte had been turned to gas or some other component that doesn't react with water.
some pics
pic below shows the type of cell ( the one in the pic is not puffed like the one in the expt)

1.jpg

pic below shows the aluminium layer ( black) still in very good condition ( probably cobalt or manganese oxide type lithium),
the copper sheet ( foil) all the graphite came off once soaked in water, the graphite had a very weak bond to the copper when first taken out of the pouch, the porous membrane shown soaking in water, no gas given off.

2.jpg

pic below shows membrane in water ( no gas reaction)
3.jpg

another view, you can see the aluminium sheet drying out in the sun
4.jpg

Some observations:
1. the graphite layer was in poor condition, lithium salt deposits were clearly visible ( sorry I didn't take a pic)
2. graphite layer easily peeled/flaked off the copper
3. all graphite came off the copper once soaked in water
4. water quickly dissolved the lithium salts, any contact with the graphite caused it to come off the copper
5. the lithium layer on aluminium in very good condition
6. porous membrane: appeared to be one place where the membrane was broken, a small slit ( perhaps due to lithium crystal growth on the graphite layer puncturing th membrane), in that place the membrane was partially stuck to one of the layers
7.no gas bubbles seen on the porous membrane, no gas oberved when water contacted the other layers also

Ok so what use is all this:

If going to use the method of water washing the graphite layer, to remove sei components, touching the graphite with a cloth etc will damage the layer, so the layer can only be soaked in water to remove lithium products ( not physically washed off with a cloth etc)
Seems to me the graphite layer is the big problem in these cells, especially it seems to flake off the copper easily.
So the copper foil is very easy to remove graphite layer and get a nice clean sheet of copper.........is it possible to re-graphite this layer, with a graphite spray?

The aluminium foil has a very stable layer of metal oxide ( depending on type of cell) and lithium, it can be washed with a cloth without damaging it. It seems it would be readily reuseable after a water wash.
 
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