Extraction of Cobalt and Lithium from Lithium-Ion Batteries

Описание: An acid-base approach to extracting Cobalt and Lithium from some old phone and laptop batteries.

Some small corrections:

1. The explanation presented at 3:45 - 4:12 is probably incorrect. As pointed out by @chemicalmaster3267, Co3+ has a higher reduction potential than H2O2 and is thus actually reduced to Co2+ in it's presence. In fact, addition of Hydrogen Peroxide is probably necessary to maximize yield of both Cobalt and Lithium.

The most likely explanation is the formation of Cobalt(II, III) Oxide when aqueous HCl is added to LiCoO2. The Cobalt(II, III) Oxide forms a porous "crust" around the LiCoO2, buffering it from further attack by the HCl. While Cobalt(II, III) Oxide does react with HCl, it is considerably slower. By adding H2O2, the Co3+ in the oxide is reduced, making it soluble and allowing the HCl to access the LiCoO2 again, creating Cl2 as a byproduct. This is why I noticed increased evolution of Cl2 when adding H2O2, but mistakenly believed the H2O2 was oxidizing the Co2+ to Co3+, forming the unstable CoCl3 which then decomposing to CoCl2 and Cl2.

Sauce: https://www.sciencedirect(dot)com/science/article/pii/S0045653521024929

2. Some of the formulas were "technically incorrect":
a. At 4:55, the "CoOH2" should be "Co(OH)2"
b. At 7:23 the balanced equation should read "CoCl2 + Na2CO3 === CoCO3 + 2 NaCl"

3. At 7:40 during the formation of Cobalt Carbonate, I mentioned that I "neutralized the pH". Technically, I continued to add Sodium Carbonate until the mother liquor turned clear (suggesting all the cobalt chloride had reacted). This actually brought the pH up to about 8.5.

Additional Thoughts and Notes:

1. If the goal is simply cool looking Cobalt Chloride without regard for the Lithium, the easiest thing to do is to simply dissolve everything - Aluminum and all - in some HCl. Then boil down the solution and let it crystalize. That's actually how I obtained the Cobalt Chloride crystal shown in the video.

2. Acetone may work for separating the oxides from the aluminum. When I shook the RBF vigorously, it did appear to loosen things quite a bit. Perhaps if it were placed into an ultrasonic cleaner while being heated under reflux it could be much more effective. But I don't know how practical that is.

3. It's probably best to just skip the ammonia all together. I left a small text box during the lithium precipitation briefly mentioning this. The only purpose of the ammonia was to reduce the overall sodium content. More sodium means I can't boil off as much of the solution, which means lower Lithium yield. However, given that Lithium Carbonate has a solubility of like 0.70g/100mL @ 100C, the impact is probably negligible and not worth the potential headache caused by adding more ions to solution. It'd be more impactful on final yield to bubble CO2 through the solution at the end to make the carbonate rather than adding Sodium Carbonate. If Ammonium IS used, don't add it past a pH of 2.

4. Filtering the Cobalt Hydroxide was a real PITA. Its very fine and thick, like a clay. So it takes FOREVER to gravity filter. Also, the highly alkaline solution has a tendency to make coffee filters very fragile and easy to tear. So unless a very robust vacuum filtration setup is used, expect to be very patient.

5. While I didn't test it myself, drying of the Cobalt Carbonate could probably be accelerated by doing a final wash with some ethanol (which it's still insoluble in but evaporates faster than water).

6. My Cobalt Carbonate yield is irrelevant to my Hydroxide yield, as I had used up nearly half of my hydroxides to try making Nitrate, Chloride, and Sulfate salts. It was when this didn't seem to be working that I moved forward with making the carbonate. Which was probably just a better idea all around since the carbonate is safer to handle and more useful than the hydroxides.