Method for Recycling a Solid Electrolyte and Cathode Material From Solid-State Lithium Batteries

Abstract

A method for recycling a cathode material and a solid electrolyte from a solid-state lithium battery is provided. The method has the following steps: a) separating the solid-state lithium battery into a solid mixture, said mixture comprising lithium anode, cathode material, and solid electrolyte components, b) mixing the solid mixture with an aprotic solvent, forming a solution of the solid electrolyte in the aprotic solvent and insoluble constituents comprising lithium anode and cathode material, c) separating the solution of the solid electrolyte from the insoluble constituents, d) bringing the insoluble constituents into contact with a protic solvent, forming a solution of lithium salt of the general formula LiX in the protic solvent and undissolved cathode material, e) separating the solution of lithium salt LiX from the undissolved cathode material, and f) calcinating the separated cathode material while adding a lithium compound.

Claims

1.-10. (canceled)

11. A method for recycling a cathode material and a solid electrolyte from a solid-state lithium battery, the method comprising the steps of: a) separating the solid-state lithium battery into a solid mixture, wherein the mixture comprises lithium anode, cathode material and solid electrolyte components; b) mixing the solid mixture with an aprotic solvent to form a solution of the solid electrolyte in the aprotic solvent and insoluble constituents comprising lithium anode and cathode material; c) separating the solution of the solid electrolyte from the insoluble constituents; d) contacting the insoluble constituents with a protic solvent to form a solution of lithium salts of the general formula LiX in the protic solvent and undissolved cathode material, wherein X is an alkoxide or a hydroxide ion, the lithium anode reacts with the protic solvent to form hydrogen and lithium salts LiX, and the lithium salts LiX dissolves in the protic solvent; e) separating the solution of lithium salts LiX from the undissolved cathode material; and f) calcining the separated cathode material with the addition of a lithium compound.

12. The method according to claim 11, wherein the cathode material is selected from the group consisting of lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt aluminum oxide, lithium nickel manganese cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium nickel manganese oxide, lithium nickel manganese oxide spinel, and combinations thereof.

13. The method according to claim 11, wherein the solid electrolyte comprises a sulfide-based solid electrolyte.

14. The method according to claim 13, wherein the sulfide-based solid electrolyte is a lithium phosphorus sulfide and/or a lithium boron sulfide of the general formula Li.sub.xT.sub.yS.sub.zR.sub.q in which T is boron or phosphorus, and R is a halogen, and where 2x7, 1y7, 3z13, 0q1.

15. The method according to claim 11, wherein the lithium anode comprises a lithium metal or a lithium alloy.

16. The method according to claim 15, wherein the lithium alloy is selected from manganese, zinc, silver, lithium, silicon, germanium and antimony, and combinations thereof.

17. The method according to claim 11, wherein the separating of the solid-state lithium battery is conducted in a closed system.

18. The method according to claim 17, wherein the separating of the solid-state lithium battery is conducted under a protective gas atmosphere.

19. The method according to claim 11, wherein the aprotic solvent is selected from the group consisting of dimethyl carbonate, acetonitrile, cyclohexane, toluene, p-xylene, anisole, pyridine, propylene carbonate, tetrahydrofuran, naphthalene and ethyl methyl carbonate, and mixtures thereof.

20. The method according to claim 11, wherein the mixing of the solid mixture with the aprotic solvent results in a heterogeneous mixture consisting of the liquid aprotic solvent component and the solids comprising cathode material and lithium anode, wherein the solids content in the heterogeneous mixture is not more than 70% by weight, based on the total weight of the mixture.

21. The method according to claim 11, wherein the separating of the solution of the solid electrolyte is followed by isolating and processing of the solid electrolyte dissolved in the aprotic solvent.

22. The method according to claim 21, wherein the isolating and processing of the solid electrolyte dissolved in the aprotic solvent is done with heat treatment.

23. The method according to claim 21, wherein the isolating and processing of the solid electrolyte dissolved in the aprotic solvent is carried out by recrystallization with a further solvent selected from the group consisting of tetrahydrofuran, toluene, dimethyl carbonate, acetonitrile, p-xylene, anisole, pyridine, propylene carbonate, naphthalene and ethyl methyl carbonate and cyclohexane, and mixtures thereof.

24. The method according to claim 11, wherein the protic solvent is selected from the group consisting of water and alkanols, and mixtures thereof, wherein the contacting of the protic solvent with the insoluble constituents comprises an addition of the protic solvent in the liquid phase and/or gas phase.

25. The method according to claim 11, wherein a lithium compound is added in the calcining of the cathode material in step f).

26. The method according to claim 25, wherein the lithium compound is selected from the lithium salts LiX obtained from step e), a solution of the lithium salts LiX in the protic solvent or a lithium compound obtained from lithium salts, and combinations thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] FIG. 1 shows a schematic flow diagram of the steps of a method of the invention for recycling a cathode material and solid electrolyte from solid-state lithium ion batteries.

DETAILED DESCRIPTION OF THE DRAWINGS

[0070] In FIG. 1, a solid-state lithium battery is separated into a solid blend, where the blend comprises the lithium anode, cathode material and solid electrolyte components (step S1).

[0071] The solid blend is admixed with an aprotic solvent, which forms a mixture of a solution of the solid electrolyte in the aprotic solvent and insoluble constituents including lithium anode and cathode material (step S2).

[0072] In the next step, the solution of the solid electrolyte is separated from the insoluble constituents (step S3), for example by suitable filtration or extraction techniques.

[0073] Finally, the solid electrolyte dissolved in the aprotic solvent is isolated from the aprotic solvent and processed, preferably by heat treatment, more preferably by recrystallization with a further solvent (step S4). The solid electrolyte thus recovered is available for use for new production of solid-state lithium ion batteries. Examples of suitable solvents for recrystallization include tetrahydrofuran, toluene and cyclohexane, and mixtures thereof.

[0074] Then the insoluble constituents are contacted with a protic solvent, forming a mixture of a solution of lithium salts of the general formula LiX in the protic solvent and undissolved cathode material, where the lithium anode reacts with the protic solvent to give hydrogen and lithium salts LiX, and where the lithium salts LiX are dissolved in the protic solvent (step S5). In the lithium salts LiX, X denotes an alkoxide or a hydroxide ion.

[0075] The hydrogen formed on contacting of the protic solvent with the insoluble constituents from lithium anode and cathode material can simultaneously be collected and stored (step S6).

[0076] Thereafter, the solution of LiX is separated from the undissolved cathode material (step S7).

[0077] Finally, the solution of lithium salts LiX can be isolated and collected, or the lithium salts LiX can be converted to another lithium compound (step S8).

[0078] Finally, the cathode material separated off is calcined with addition of a lithium compound. The lithium compound is preferably a lithium salt LiX obtained from step S8, further preferably a solution of lithium salts LiX in the protic solvent, or a lithium compound obtained from the lithium salts LiX, such as lithium carbonate (step S9).