METHOD FOR RECYCLING LITHIUM-ION BATTERY ELECTROLYTE

Abstract

The present disclosure discloses a method for recycling a lithium-ion battery electrolyte. After the waste lithium-ion battery is discharged, it is frozen and disassembled to obtain a battery cell containing an electrolyte. The battery cell is immersed in a lithium hydroxide solution containing a catalyst for reaction. The battery cell after the reaction is taken out and washed. The washing solution is mixed with the lithium hydroxide solution after the reaction to obtain a mixed solution. The mixed solution is filtered to obtain a filtrate and a filter residue. The filter residue is reacted with a hydrofluoric acid solution to obtain anhydrous lithium salt. The anhydrous lithium salt is mixed with an organic solution, and PF.sub.5 gas is introduced. The mixture is reacted, and filtered to obtain an organic liquid. The organic solution is frozen and filtered to obtain lithium hexafluorophosphate.

Claims

1. A method for recycling a lithium-ion battery electrolyte, comprising the following steps: (1) freezing a waste lithium-ion battery after being discharged; disassembling the frozen waste lithium-ion battery to obtain a battery cell containing an electrolyte; (2) immersing the battery cell obtained in step (1) in a lithium hydroxide solution containing a catalyst for reaction; (3) taking out the battery cell after the reaction in step (2), and washing the battery cell with a lithium hydroxide solution to obtain a washing solution; mixing the washing solution with the lithium hydroxide solution after the reaction in step (2) to obtain a mixed solution; (4) filtering the mixed solution obtained in step (3) to obtain a filtrate and a filter residue; (5) mixing the filter residue obtained in step (4) with a hydrofluoric acid solution, heating and evaporating to dryness, and then calcining to obtain an anhydrous lithium salt; (6) mixing the anhydrous lithium salt obtained in step (5) with an organic solvent, introducing gas PF.sub.5, reacting, and filtering to obtain an organic liquid; and (7) freezing and filtering the organic liquid obtained in step (6) to obtain lithium hexafluorophosphate.

2. The method for recycling the lithium-ion battery electrolyte according to claim 1, wherein in step (1), components of the electrolyte comprise at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

3. The method for recycling the lithium-ion battery electrolyte according to claim 1, wherein in step (2), the catalyst comprises at least one of quaternary ammonium salt and methylamino diethanol.

4. The method for recycling the lithium-ion battery electrolyte according to claim 1, wherein in step (2), a reaction time is 0.3 h to 3 h.

5. The method for recycling the lithium-ion battery electrolyte according to claim 1, wherein in step (5), a calcination temperature is 500 C. to 800 C.; and a calcination time is 0.3 h to 3 h.

6. The method for recycling the lithium-ion battery electrolyte according to claim 1, wherein in step (6), the organic solvent comprises at least one of acetonitrile, diethyl ether, pyrrole, and pyridine.

7. The method for recycling the lithium-ion battery electrolyte according to claim 1, wherein in step (6), a liquid-solid ratio of the organic solvent to the anhydrous lithium salt is (30 to 60) mL:1 g.

8. The method for recycling the lithium-ion battery electrolyte according to claim 1, wherein in step (6), a reaction pressure is 0.2 MPa to 0.8 MPa; and a reaction time is 0.5 h to 3 h.

9. The method for recycling the lithium-ion battery electrolyte according to claim 1, wherein in step (6), a temperature during the filtration is 40 C. to 80 C.

10. The method for recycling the lithium-ion battery electrolyte according to claim 1, wherein in step (7), a freezing temperature is 40 C. to 10 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings are used to provide a further understanding of the technical solutions herein and constitute part of the description, and are used together with the examples of the present application to interpret the technical solution herein, and do not constitute a limitation on the technical solution herein

[0043] FIG. 1 is a schematic diagram of a method for recycling a lithium-ion battery electrolyte according to an example.

DETAILED DESCRIPTION

[0044] The content of the present application will be further described in detail below through specific examples. Unless otherwise specified, the raw materials or devices used in the examples can be obtained from conventional commercial channels, or can be obtained by methods of the related art. Unless otherwise specified, test or test methods are routine in the art.

Example 1

[0045] Referring to the schematic diagram of FIG. 1, the method for recycling a lithium-ion battery electrolyte in the present example included the following steps: [0046] (1) after the waste lithium-ion battery was discharged, it was frozen to 60 C. or less by using liquid nitrogen; [0047] (2) the frozen waste lithium-ion battery was disassembled, and a battery cell containing an electrolyte was taken out; [0048] (3) the battery cell was immersed in a lithium hydroxide solution containing a catalyst for 2 h, the battery cell was all covered by the liquid, the concentration of the lithium hydroxide solution was 0.1 mol/L, the catalyst was methylamino diethanol, and the concentration thereof was 10 g/L; [0049] (4) the battery cell obtained after the reaction in step (3) was taken out, and washed with a lithium hydroxide solution with a concentration of 0.1 mol/L to obtain a washing solution; the washing solution was mixed with the lithium hydroxide solution obtained after the reaction in step (3) to obtain a mixed solution; [0050] (5) the mixed solution was filtered to obtain filtrate and filter residue; [0051] (6) the filter residue was added to a sufficient amount of hydrofluoric acid solution, and then the mixture was heated and evaporated to dryness to recycle redundant hydrogen fluoride, and was calcined at a temperature of 600 C. for 2 h to obtain anhydrous lithium salt; [0052] (7) according to the liquid-solid ratio of 40 mL:1 g, anhydrous lithium salt was added into anhydrous acetonitrile, and the mixture was put in a closed environment, in which gas PF.sub.5 was slowly introduced, so that the reaction system pressure was 0.3 MPa, to react for 2 h. After the reaction was completed, the mixture was heated to 50 C. and filtered to obtain an organic liquid; [0053] (8) the organic liquid was frozen to 30 C. to separate out crystal, and filtered to obtain a filter cake; and [0054] (9) the filter cake was dried at 0 C. for 24 h under nitrogen atmosphere to obtain lithium hexafluorophosphate.

[0055] The prepared lithium hexafluorophosphate met the standard requirement of HG/T 4066-2015 Lithium Hexafluorophosphate Electrolyte.

Example 2

[0056] Referring to the schematic diagram of FIG. 1, the method for recycling a lithium-ion battery electrolyte in the present example included the following steps: [0057] (1) after the waste lithium-ion battery was discharged, it was frozen to 60 C. or less by using liquid nitrogen; [0058] (2) the frozen waste lithium-ion battery was disassembled, and a battery cell containing an electrolyte was taken out; [0059] (3) the battery cell was immersed in a lithium hydroxide solution containing a catalyst for 1 h, the battery cell was all covered by the liquid, the concentration of the lithium hydroxide solution was 2 mol/L, the catalyst was [(CH.sub.3).sub.3NCH.sub.2CH.sub.2Cl]Cl, and the concentration thereof was 30 g/L; [0060] (4) the battery cell obtained after the reaction in step (3) was taken out, and washed with a lithium hydroxide solution with a concentration of 2 mol/L to obtain a washing solution; the washing solution was mixed with the lithium hydroxide solution obtained after the reaction in step (3) to obtain a mixed solution; [0061] (5) the mixed solution was filtered to obtain filtrate and filter residue; [0062] (6) the filter residue was added to a sufficient amount of hydrofluoric acid solution, and then the mixture was heated and evaporated to dryness to recycle redundant hydrogen fluoride, and was calcined at a temperature of 650 C. for 1 h to obtain anhydrous lithium salt; [0063] (7) according to the liquid-solid ratio of 45 mL:1 g, anhydrous lithium salt was added into anhydrous acetonitrile, and the mixture was put in a closed environment, in which gas PF.sub.5 was slowly introduced, so that the reaction system pressure was 0.5 MPa, to react for 1.5 h. After the reaction was completed, the mixture was heated to 60 C. and filtered to obtain an organic liquid; [0064] (8) the organic liquid was frozen to 25 C. to separate out crystal, and filtered to obtain a filter cake; and [0065] (9) the filter cake was dried at 3 C. for 18 h under nitrogen atmosphere to obtain lithium hexafluorophosphate.

[0066] The prepared lithium hexafluorophosphate met the standard requirement of HG/T 4066-2015 Lithium Hexafluorophosphate Electrolyte.

Example 3

[0067] Referring to the schematic diagram of FIG. 1, the method for recycling a lithium-ion battery electrolyte in the present example included the following steps: [0068] (1) after the waste lithium-ion battery was discharged, it was frozen to 60 C. or less by using liquid nitrogen; [0069] (2) the frozen waste lithium-ion battery was disassembled, and a battery cell containing an electrolyte was taken out; [0070] (3) the battery cell was immersed in a lithium hydroxide solution containing a catalyst for 0.5 h, the battery cell was all covered by the liquid, the concentration of the lithium hydroxide solution was 4 mol/L, the catalyst was [(CH.sub.3CH.sub.2).sub.3NCH.sub.2CH.sub.2OH]Cl, and the concentration thereof was 50 g/L; [0071] (4) the battery cell obtained after the reaction in step (3) was taken out, and washed with a lithium hydroxide solution with a concentration of 4 mol/L to obtain a washing solution; the washing solution was mixed with the lithium hydroxide solution obtained after the reaction in step (3) to obtain a mixed solution; [0072] (5) the mixed solution was filtered to obtain filtrate and filter residue; [0073] (6) the filter residue was added to a sufficient amount of hydrofluoric acid solution, and then the mixture was heated and evaporated to dryness to recycle redundant hydrogen fluoride, and was calcined at a temperature of 700 C. for 0.5 h to obtain anhydrous lithium salt; [0074] (7) according to the liquid-solid ratio of 50 mL:1 g, anhydrous lithium salt was added into anhydrous diethyl ether, and the mixture was put in a closed environment, in which gas PF.sub.5 was slowly introduced, so that the reaction system pressure was 0.7 MPa, to react for 1 h. After the reaction was completed, the mixture was heated to 70 C. and filtered to obtain an organic liquid; [0075] (8) the organic liquid was frozen to 20 C. to separate out crystal, and filtered to obtain a filter cake; and [0076] (9) the filter cake was dried at 5 C. for 24 h under nitrogen atmosphere to obtain lithium hexafluorophosphate.

[0077] The prepared lithium hexafluorophosphate met the standard requirement of HG/T 4066-2015 Lithium Hexafluorophosphate Electrolyte.