Method and apparatus for recycling lithium-ion batteries
Cathode material from exhausted lithium ion batteries are dissolved in a solution for extracting the useful elements Co (cobalt), Ni (nickel), Al (Aluminum) and Mn (manganese) to produce active cathode materials for new batteries. The solution includes compounds of desirable materials such as cobalt, nickel, aluminum and manganese dissolved as compounds from the exhausted cathode material of spent cells. Depending on a desired proportion, or ratio, of the desired materials, raw materials are added to the solution to achieve the desired ratio of the commingled compounds for the recycled cathode material for new cells. The desired materials precipitate out of solution without extensive heating or separation of the desired materials into individual compounds or elements. The resulting active cathode material has the predetermined ratio for use in new cells, and avoids high heat typically required to separate the useful elements because the desired materials remain commingled in solution.
1. A method for recycling lithium-ion batteries, comprising:
identifying a molar ratio for cathode materials for a recycled battery;
forming a leach solution by combining crushed battery material from a lithium battery recycling stream with an acidic leach agent and hydrogen peroxide to separate cathode materials from undissolved materials;
filtering the undissolved materials from the leach solution to leave dissolved salts of cathode materials remaining in the leach solution;
determining a composition of the leach solution by identifying a molar ratio of the cathode material salts dissolved therein;
adding, based on the determined composition, at least one of Ni, Co, Mn or Al salts in a sulfate or hydroxide form to adjust the molar ratio of the dissolved cathode material salts in the leach solution to correspond to the identified molar ratio for the recycled battery, including adding a solution of aluminum sulfate and a chelating agent to the leach solution; and
raising the pH of the leach solution to at least 10 for precipitating and filtering metal ions of the cathode materials to form a charge material precursor by coprecipitating the Ni, Co, Mn and Al salts remaining in the leach solution as a combined hydroxide or carbonate having a molar ratio corresponding to the identified molar ratio for the recycled battery, the charge precursor material responsive to sintering for forming active cathode materials in an oxide form following sintering with lithium carbonate (Li 2 CO 3 ).
2. The method of claim 1 further comprising, prior to adjusting the molar ratio, precipitating impurities from the leach solution by adding sodium hydroxide until the pH is in a range between 5.0-7.0 for precipitating hydroxides of impurities.
3. The method of claim 1 further comprising raising the pH to a range of 10-13.0 for precipitating hydroxide precursor material.
4. The method of claim 3 further comprising raising pH by adding sodium hydroxide to increase the pH to 11.0.
5. The method of claim 1 wherein the cathode material salts include Ni, Mn and Co in a hydroxide form with molar ratios of unequal proportions.
6. The method of claim 1 wherein the cathode material salts include Ni, Co and Al in a hydroxide form with molar ratios of unequal proportions.
7. The method of claim 1 wherein the acidic leach agent is sulfuric acid having a concentration of 2-5 M (molar).
8. The method of claim 7 wherein the acidic leach agent is 4M sulfuric acid.
9. The method of claim 1 wherein the charge material precursor is Ni x Mn y Co z (OH) 2 , Ni x Mn y Co z CO 3 , Ni x Co y Al z (OH) 2 or Ni x Co y Al 2 CO 3 where the molar ratios defined by x, y, and z are based on the determined composition of the recycled battery.
10. The method of claim 6 further comprising, prior to adding the cathode material salts for adjusting the molar ratio, removing manganese ions from the leach solution.
11. The method of claim 1 wherein the added chelating agent is 5-sulfosalicylic acid, further including adding the 5-sulfosalicylic acid to a solution of distilled water and the aluminum sulfates.
12. The method of claim 11 further comprising adding the solution of distilled water and including the aluminum sulfate to the leach solution, the leach solution previously formed in a reactor for coprecipitation, the reactor containing ammonium water and sodium hydroxide.
13. The method of claim 1 wherein the concentration of the chelating agent is 0.05M-0.5M, further comprising stirring the leach solution at 500-1000 rpm at a temperature in the range of 30-60° C.