PROCESS

Abstract

A method of recovering a lithium salt from a lithium battery waste mass, comprising the steps of: (a) dissolving the lithium sail in the lithium battery waste mass in a weight of water equivalent to 100 to 0.1 times the weight of the lithium battery waste mass, either in a one-off treatment or successive treatments; (b) evaporating the aqueous solution to dryness; and (c) working up the dry residue with a solvent comprising water, a carbonate, or mixtures thereof.

Claims

1. A method of recovering a lithium salt from a lithium battery waste mass, comprising the steps of: (a) dissolving the lithium salt in the lithium battery waste mass in a weight of water equivalent to 100 to 0.1 times the weight of the lithium battery waste mass, either in a one-off treatment or successive treatments; (b) evaporating the aqueous solution to dryness; and (c) working up the dry residue with a solvent comprising water, an organic solvent, or mixtures thereof.

2. A method of recovering a lithium salt from a lithium battery waste mass, comprising the steps of: a) dissolving the lithium salt in the lithium battery waste mass in a weight of solvent equivalent to 100 to 0.1 times the weight of the lithium battery waste mass, either in a one-off treatment or successive treatments; b) evaporating the solvent solution to dryness; and c) working up the dry residue with a solvent comprising water, an organic solvent, or mixtures thereof.

3. The method according to claim 2, wherein the solvent in step (a) comprises an ether solvent, a nitrile solvent, a carboxylate solvent, or a carbonate solvent containing no water, or containing low levels of water such that the water and the solvent are still miscible at 25 C.

4. The method according to claim 1, wherein the solvent in step (c) comprises an ether solvent, a nitrile solvent, a carboxylate solvent, or a carbonate solvent containing no water, or containing low levels of water such that the water and the solvent are still miscible at 25 C.

5. The method according to claim 4, in which the final working up step (c) serves to effect a purification of the recovered electrolyte salt.

6. The method according to claim 5, in which the carbonate solvent is dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, or mixtures thereof.

7. The method according to claim 5, in which solvent used in the working up step (c) comprises is a carbonate solvent containing no water, or containing low levels of water such that the water and carbonate solvent are still miscible at 25 C.

8. The method according to claim 1, in which lithium battery waste mass comprises black mass.

9. The method according to claim 8 in which the black mass comprises at least 80 wt % of the lithium battery waste mass.

10. The method according to claim 1, in which the lithium battery waste mass prior to step (a) is dry, or containing less than 20 g/kg of liquid.

11. The method according to claim 1, in which the lithium salt is LiPF.sub.6.

12. The method according to claim 1, in which dissolution step (a) is carried out at a temperature of less than 50 C.

13. The method according to claim 1, in which dissolution step (a) is carried out using water which is more than 95 wt % pure.

14. The method according to claim 1, in which the contact time of the water with the lithium ion battery mass in step (a) is less than 5 hours, or less than 10 minutes.

15. The method according to claim 1, in which the evaporating to dryness step (b) is carried out by vacuum evaporation or spray drying.

16. The method according to claim 1, in which dissolution step (a) is carried out dynamically.

17. The method according to claim 1, in which the weight ratio of water to lithium battery waste mass is 10 to 0.5:1, or 3 to 0.5:1.

18. The method according to claim 4, wherein the solvent in step (c) is independently selected from the group consisting of diethyl ether, acetonitrile, propionitrile, ethyl acetate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and any mixture thereof.

19. The method according to claim 3, wherein the solvent in step (c) comprises an ether solvent, a nitrile solvent, a carboxylate solvent, or a carbonate solvent containing no water, or containing low levels of water such that the water and the solvent are still miscible at 25 C.

20. The method according to claim 19, wherein the solvent in either or both of step (a) or step (c) is independently selected from the group consisting of diethyl ether, acetonitrile, propionitrile, ethyl acetate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and any mixture thereof.

Description

[0040] FIGS. 1 and 2 show typical .sup.19F and .sup.31P NMR spectra of the aqueous extracts which serve to confirm the presence of the PF.sub.6 anion in the aqueous extract solutions.

Example 2Extraction and Recovery of LiPF.SUB.6 .from Black Mass

Aqueous Extraction of Black Mass Powder

[0041] The soluble components from a sample of black mass (5 g) material were extracted with water (10 mL) using batch contacting in an open beaker with mixing for a defined period (1.5 h). After this defined period the orange-tinted mixture obtained was filtered under vacuum, yielding an orange-tinted filtrate which was made up to 10 mL with water. This solution was analysed by .sup.19F and .sup.31P NMR to confirm the presence of the PF.sub.6 anion and determine its concentration and hence recovery rate. A doublet was observed by .sup.19F NMR and a heptet by .sup.31P NMR and the amount of LiPF.sub.6 in solution was determined by .sup.19F NMR to be equivalent to 10.97 mg/g black mass.

Removal of Solvent from Filtrate

[0042] Some filtrate was transferred to a 75 mL round-bottomed flask and the water removed in vacuo at 30 mbar and 45 C. Under these conditions all of the solvent was removed in less than 30 minutes.

[0043] The solid residue obtained after water removal was redissolved in water (10 mL) and the solution so obtained was again analysed by .sup.19F and .sup.31P NMR which showed that the PF.sub.6 anion survived the water removal and re-dissolving steps largely intact. By .sup.19F NMR the LiPF.sub.6 content of this solution was determined to be 10.80 mg/g black mass, slightly reduced from the 10.97 mg/g black mass in the original extract solution.

Selective Extraction of LiPF.sub.6 from Solid Residue into Ethyl Methyl Carbonate (EMC)

[0044] The extraction and evaporation steps described above were repeated and the solid residue obtained extracted with EMC. The aqueous extract and EMC solution so obtained was analysed by .sup.31P NMR spectroscopy which showed that the PF.sub.6 anion survived the extraction and evaporation processes intact and was extracted from the evaporation residue by EMC, see FIG. 3.

Stability of PF.SUB.6 .Anion in EMC Solvent

[0045] A sample of PF.sub.6 anion recovered by extraction into EMC was stored over a period of 15 days. .sup.19F NMR was used to quantify the concentration of the PF.sub.6 anion in solution over this period. The results are shown below in Table 2, and show the PF.sub.6 anion is stable in EMC after removal of water and extraction into EMC for at least two weeks.

TABLE-US-00002 TABLE 2 Day Mmol PF.sub.6 1 0.175 8 0.161 11 0.165 15 0.158

Example 3: Repeated Demonstration of Process Steps

[0046] The basic aqueous extraction, solvent removal and extraction of solids with EMC procedure of Example 2 was repeated six times, and the results are summarised in Table 3. The amount of LiPF.sub.6 extracted and recovered in the EMC solution was quantified by .sup.19F NMR with confirmation by .sup.31P NMR.

TABLE-US-00003 TABLE 3 Experiment 1 2 3 4 5 6 LiPF.sub.6 yield 0.99 1.10 1.14 0.74 0.75 0.74 (% wt Black mass)

Example 4: Repeated Washing/Process Steps

[0047] The basic aqueous extraction, solvent removal and extraction of solids of Example 2 was repeated on the same sample five times, and the results are summarised in FIG. 4. The amount of LiPF.sub.6 extracted and recovered was quantified by .sup.19F NMR with confirmation by .sup.31P NMR.

Example 5: Extraction and Recovery of LiPF.SUB.6 .from Black Mass

[0048] The basic aqueous extraction, solvent removal and extraction of solids of Example 2 was repeated on three different battery material samples (200 g) with 100 mL solvent, and the results are summarised in Table 4. The amount of LiPF.sub.6 extracted and recovered was quantified by .sup.19F NMR with confirmation by .sup.31P NMR.

TABLE-US-00004 TABLE 4 LiPF.sub.6 extracted Sample of Black Maa Solvent (wt %) Heavily dried, end of life batteries Water 0.22 Minimal drying, partially used batteries Water 1.09 Electrolyte-doped jelly rolls (1M LiPF.sub.6) Water 3.32 Electrolyte-doped jelly rolls (1M LiPF.sub.6) Organic (DMC) 1.99

Example 6: Extraction and Recovery of LiPF.SUB.6 .from Black Mass

Solvent Extraction with Water or EMC

[0049] The basic aqueous extraction, solvent removal and extraction of solids of Example 2 was repeated on three different battery material samples (200 g) with 100 mL solvent, and the results are summarised in FIGS. 5 to 7. Both layers analysed by ion chromatography (topanions, bottomcations). The blue profile is the separated aqueous composition, and the pink profile that of the remaining EMC mixture. The amount of LiPF.sub.6 extracted and recovered was quantified by .sup.19F NMR with confirmation by .sup.31P NMR.

[0050] The black profile is the direct extract from the battery material with water. It can clearly be seen that the majority of PF.sub.6, along with Li+ and some Na+ have transferred into the aqueous phase leaving some residual ions in the EMC.

Further Extraction of EMC Extract

[0051] The EMC mixture containing LiPF.sub.6 was washed with the same volume of water, and ether added to encourage separation of organic and aqueous layer. Both layers analysed by ion chromatography (topanions, bottomcations) and the results are summarised in FIGS. 8 to 10. The blue profile is the separated aqueous composition, and the pink profile that of the remaining EMC mixture. The black profile is the direct extract from the battery material with water. It can clearly be seen that the majority of PF.sub.6.sup., along with Li.sup.+ and some Na.sup.+ have transferred into the aqueous phase leaving some residual ions in the EMC.

Example 7: Extraction and Recovery of LiPF.SUB.6 .from Black Mass

Solvent Extraction with Water or EMC

[0052] The basic aqueous extraction, solvent removal and extraction of solids of Example 2 was repeated on different battery material samples (200 g) with 100 mL solvent (DMC or water), and the results are summarised in FIG. 11 (DMC (blue); water (black)). The amount of LiPF.sub.6 extracted and recovered was quantified by .sup.19F NMR with confirmation by .sup.31P NMR.

[0053] It can be seen that extracting LiPF.sub.6 with an organic carbonate does not extract all the other components that is observed when water is used. The bulk of the DMC extracted material is LiPF.sub.6.

Example 8: Extraction and Recovery of LiPF.SUB.6 .from Black Mass

Solvent Extraction with Water

[0054] The basic aqueous extraction, solvent removal and extraction of solids of Example 2 was repeated on four different battery material samples (200 g) with 100 mL solvent (water), and the results are summarised in FIG. 12 (DMC (blue); water (black)). The amount of LiPF.sub.6 extracted and recovered was quantified by .sup.19F NMR with confirmation by .sup.31P NMR.

[0055] It can be seen that different samples exhibit different amounts of LiPF.sub.6 and degree of hydrolysis of existing LiPF.sub.6. Figure shows anion chromatograms.

Example 9: Measurement and Extraction and Recovery of LiPF.SUB.6 .with Different Solvents

Solvent Extraction

[0056] Aqueous extraction, solvent removal and extraction of solids was performed.

[0057] The measurement of LiPF.sub.6 extracted using different solvents; based on the concentrations of either PF.sub.6 anion or the Li cation (with ion chromatography) in various solvents is shown in Table 5 below.

TABLE-US-00005 TABLE 5 Wt. % LiPF.sub.6 in WBM Battery Based on Based on Difference Batch Type Solvent [PF.sub.6] [Li] (%) WBM1 Unknown Water 0.10 2.45 2350 EMC 0.064 0.066 3.13 WBM2 EV field returns Water 0.58 1.75 201.7 EMC 0.83 0.79 4.82 WBM3 Mfg scrap Water 0.19 1.94 921.1 EMC / / / WBM4 Doped jelly rolls Water 2.14 4.81 124.8 EMC 1.22 1.35 10.7 WBM5 EV field returns (different supplier) Water / / / EMC 0.00 0.15 /

[0058] Assuming the concentration of LiPF.sub.6 is based on both the amount of PF.sub.6 and the amount of Li, there is shown a massive excess of Li when water is used as the extractant compared to EMC.

[0059] These results are shown pictorially in FIGS. 13a and 13b.

[0060] It can be seen that there is a clear difference in additional components extracted from black mass samples when using water vs EMC. Shown above are anion chromatograms (colours not the same WBM batch).

Example 10

[0061] 200 g of waste battery material was washed with 100 mL EMC. The filtrate was split in three aliquots; one untreated, 7 g 4 molecular sieve added to one, 7 g MgO pellets to another. Both left in fume cupboard for one week and analysed by coulometric Karl-Fisher for moisture, and IC for decomposition. The results are shown in Table 6 below.

TABLE-US-00006 TABLE 6 Water Drying Drying agent concentration Sample ID agent pre-treatment (ppm) Dry EMC / / 94 Untreated / / 2433 Extract EMC-Z4 Zeolite 4 306 C., 36 h 8 pellets EMC-MgO MgO 306 C., 36 h 2690 pellets

[0062] This shows the importance of drying solvent immediately as it picks up a lot of moisture during LiPF.sub.6 extraction and hydrolyses into the known decomposition products.