Sciencemadness Discussion Board

1000%+ of expected yield of cobalt from lithium ion batteries. Why?

itsallgoodjames - 15-2-2021 at 15:28

So I've been extracting cobalt from cell phone batteries. I found online a figure of 0.3 grams of lithium per 1000 milliamp hours. I started with about approximately 8,000 milliamp hours of batteries, meaning that I'd expect 2.4 grams of lithium. This would mean I have 0.34 moles of lithium. Lithium cobalt oxide, the material used in the batteries has equal numbers of cobalt and lithium atoms, meaning that I should get 0.34 moles of cobalt out. This would mean I would expect 20 grams of cobalt. I did this:


  1. Dissolve the black strip things inside the battery in HCl. Chlorine gas was liberated.
  2. Decant off the liquid
  3. Add sodium hydroxide, and gravity filter
  4. Transfer the residue left in the filter paper into a beaker
  5. Dissolve in HCl
  6. Boil down to leave cobalt chloride


In step 3, I was expecting cobalt hydroxide to be produced. Instead, cobalt oxide was produced. I haven't been able to figure out why this happened, but it doesn't really matter. The bigger issue is the fact that well over 200 grams of the oxide was produced. I haven't been able to weigh it yet, as some of it is still filtering, as it needs two filter papers, but the half that was done filtering weighed at least 200 grams, probably even more. I have no clue why that is. Any ideas? The half of the solution that finished filtering is pictured.
20210215_170257.jpg - 195kB
Any ideas why this is?

Thanks!



[Edited on 15-2-2021 by itsallgoodjames]

Fyndium - 15-2-2021 at 15:38

FYI, you uploaded a 16k picture. A more proper size could be 800x600pix.

itsallgoodjames - 15-2-2021 at 15:51

Oh, I'll fix that. Sorry

Amos - 15-2-2021 at 15:52

You say you expected 20 grams of cobalt to be in the batteries, and you say you were dissolving lithium cobalt oxide. But you didn't dissolve only 33 grams of pure lithium cobalt oxide in HCl, did you? Whatever you dumped into the acid, you've probably dissolved every single metal in the material, and you're going to have to find a way to separate their hydroxides. Not to mention it's not exactly very accurate weighing when you put a sopping wet mass of precipitate on the scale.

itsallgoodjames - 15-2-2021 at 16:04

Quote: Originally posted by Amos  
You say you expected 20 grams of cobalt to be in the batteries, and you say you were dissolving lithium cobalt oxide. But you didn't dissolve only 33 grams of pure lithium cobalt oxide in HCl, did you? Whatever you dumped into the acid, you've probably dissolved every single metal in the material, and you're going to have to find a way to separate their hydroxides. Not to mention it's not exactly very accurate weighing when you put a sopping wet mass of precipitate on the scale.


I put the copper sheets in the acid. The copper sheets were coated with the lithium cobalt oxide. I tested for copper after dissolving by putting a bit of the solution in a test tube and adding ammonia. The solution did not become a blue color, as the production of the tetraamminecopper(ii) ion would show. The copper appeared the exact same as it had before, just without the lithium cobalt oxide. The solution also was always the color I expected it to be. So I don't think that the issue is contamination with other metals. I know it's not very accurate to measure while it's wet, but I don't think that water is making up 180 extra grams of weight.

RustyShackleford - 15-2-2021 at 16:54

You should read my post here about the extraction and purification of cobalt from Li batteries
http://www.sciencemadness.org/talk/viewthread.php?tid=156817

You must NOT include the copper foil, because in the HCl + Cl2 conditions it dissolve and is very difficult to separate.

[Edited on 16-2-2021 by RustyShackleford]

itsallgoodjames - 15-2-2021 at 17:07

the copper didn't really seem to be damaged. My test thing also didn't show any copper. So it doesn't seem to have dissolved. Also like I said, the solution looked exactly how I expected it would look the entire time, blue/green at the beginning when dissolving, and purple when the sodium hydroxide is added or it is diluted. Very typical cobalt ii colors, and exactly what I was expecting.

[Edited on 16-2-2021 by itsallgoodjames]

clearly_not_atara - 16-2-2021 at 10:28

Some (but not very many) batteries are Li-Co. Some are Li-Co-Ni. Some are just Li-Mn. Modern ones are usually Li-Co-Ni-Al or Li-Co-Ni-Mn. In a few cases you also see Fe or V make an appearance.

The primary metal in modern lithium battery cathodes is nickel, and other metals, usually one of Al/Co/Mn/Fe, are added as dopants.

If you didn't have reliable information about the battery chemistry of the particular batteries you're working with, you could have any of about six metals in the ppt. See the problem?

itsallgoodjames - 16-2-2021 at 10:50

I was unaware of that. I guess I'll have to go through some separation steps then. Kind of odd that the solution was all the right colors the whole time.

Amos - 17-2-2021 at 09:43

Quote: Originally posted by Amos  
You say you expected 20 grams of cobalt to be in the batteries, and you say you were dissolving lithium cobalt oxide. But you didn't dissolve only 33 grams of pure lithium cobalt oxide in HCl, did you? Whatever you dumped into the acid, you've probably dissolved every single metal in the material, and you're going to have to find a way to separate their hydroxides. Not to mention it's not exactly very accurate weighing when you put a sopping wet mass of precipitate on the scale.


If you're so sure that only the intended compound dissolved, you should try again measuring everything you put into the acid vs. everything that survives.

ChemTalk - 19-2-2021 at 08:21

Quote: Originally posted by itsallgoodjames  


II know it's not very accurate to measure while it's wet, but I don't think that water is making up 180 extra grams of weight.


Actually, we've found that extra water weight can add a lot more weight to the precipitate than one would predict.

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ChemTalk
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