Low-temperature hydrothermal relithiation of spent lithium-ion battery cathodes by redox mediation
View Patent ↗A process for low temperature hydrothermal relithiation of spent lithium-ion battery cathode materials adds a reducing agent to an aqueous Li solution at 80-100° C. followed by a short anneal to achieve complete recovery of composition, crystal structure, and electrochemical performance for heavily degraded cathode materials.
1. A method for regenerating spent lithium-ion battery cathode material, wherein the cathode material is in a powdered form, the method comprising:
processing the cathode material in an aqueous lithium (Li) solution and a reducing agent at a temperature within a range of 80° to 100° C. for a processing period sufficient to relithiate the cathode material;
washing and drying the processed cathode material; and
annealing the dried processed cathode material in oxygen at an annealing temperature for an annealing period to produce a regenerated cathode material.
2. The method of claim 1 , wherein the Li solution comprises LiOH.
3. The method of claim 1 , wherein the cathode material is processed at about 1 bar.
4. The method of claim 1 , wherein the reducing agent is one or a combination of ethanol (ET), ethylene glycol (EG), hydrogen peroxide (HP), glycerol, citric acid, and L-ascorbic acid.
5. The method of claim 1 , wherein the processing period is from 2 to 20 hours.
6. The method of claim 5 , wherein the processing period is about 8 hours at 100° C.
7. The method of claim 1 , wherein the annealing temperature is within a range of 600° C. to 1000° C. and the annealing period is from 1 to 10 hours.
8. The method of claim 7 , wherein the annealing temperature is 850° C. and the annealing period is four hours.
9. The method of claim 1 , wherein the cathode material is LiNi x Co y Mn z O 2 , where 0<x, y, z<1, x+y+z=1 (“NCM”).
10. The method of claim 9 , wherein the NCM is LiNi 0.33 Co 0.33 Mn 0.33 O 2 (NCM111).
11. The method of claim 9 , wherein the NCM is LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622).
12. The method of claim 1 , wherein the aqueous Li solution comprises 0.1 to 4 M LiOH with 1-3% (v/v) of the reducing agent.
13. The method of claim 1 , further comprising, before annealing, mixing 5 mol % of excessive Li 2 CO 3 with the processed cathode material.
14. A method for treating lithium-ion battery cathode material from a spent battery cell, comprising:
separating cathode strips comprising cathode strip substrates from the battery cell;
treating the cathode strips in one or more solvent solutions to remove NCM powder, binder and carbon black from the cathode strip substrates;
extracting the NCM powder;
processing the NCM powder in an aqueous lithium (Li) solution and a reducing agent at a temperature within a range of 80° to 100° C. for a processing period sufficient to produce a relithiated NCM powder;
washing and drying the relithiated NCM powder; and
annealing the dried powder in oxygen at an annealing temperature for an annealing period to produce a cathode powder with restored composition, crystal structure and electrochemical performance.
15. The method of claim 14 , further comprising, before annealing, mixing 5 mol % of excessive Li 2 CO 3 with the relithiated powder.
16. The method of claim 14 , wherein the Li solution comprises LiOH.
17. The method of claim 14 , wherein the NCM powder is processed at about 1 bar.
18. The method of claim 14 , wherein the green reducing additive is one or a combination of ethanol (ET), ethylene glycol (EG) hydrogen peroxide (HP), glycerol, citric acid, and L-ascorbic acid.
19. The method of claim 14 , wherein the processing period is from 2 to 20 hours.
20. The method of claim 19 , wherein the processing period is 8 hours at 100° C.
21. The method of claim 14 , wherein the annealing temperature is within a range of 600° C. to 1000° C. and the annealing period is from 1 to 10 hours.
22. The method of claim 21 , wherein the annealing temperature is 850° C. and the annealing period is four hours.
23. The method of claim 14 , wherein the NCM powder is LiNi x Co y Mn z O 2 , where 0<x, y, z<1, x+y+z=1 (“NCM”).
24. The method of claim 23 , wherein the NCM powder is LiNi 0.33 Co 0.33 Mn 0.33 O 2 (NCM111).
25. The method of claim 23 , wherein the NCM powder is LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622).
26. The method of claim 14 , wherein the aqueous Li solution comprises 0.1 to 4 M LiOH with 1-3% (v/v) of the reducing agent.