Organic extracting solvents for successfully recycling LIPF6 from waste shredded battery material

Abstract

A method of extracting lithium salts (e.g., LiPF6) from waste battery materials by dissolving the lithium salt in a polar aprotic solvent and separating the dissolved lithium salt to obtain an extracted solution. The solvent is preferably a volatile and highly solubilizing solvent that can extract the lithium salt and be removed subsequently, or a solvent that is common to lithium-ion battery system that does not need to be removed.

Description

[0001] ORGANIC EXTRACTING SOLVENTS FOR SUCCESSFULLY RECYCLING LIPF6 FROM WASTE SHREDDED BATTERY MATERIAL

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] Priority is hereby claimed to U.S. provisional application Ser. No. 63 / 650,117, filed May 21 , 2024, which is incorporated herein by reference.

[0004] BACKGROUND

[0005] LiPFe (lithium hexafluorophosphate) is a critical component of lithium-ion batteries. It is one of the most commonly used electrolyte salts in such batteries. The factors that make it one of the most-used compounds for battery salts are its high electrochemical stability, high ionic conductivity7, and high solubility in numerous organic solvents. Despite its crucial role in batteries, LiPFe is unstable at high temperatures and upon exposure to water. When it degrades, LiPFe can produce hydrogen fluoride (HF). This is highly undesirable due to the extremely toxic and corrosive nature of HF. HF also adversely impacts battery performance. The reactions leading from LiPFe to HF are shown below:

[0006] LiPF6■ PF5+ LiF

[0007] PF5+ H2o - POF3+ 2HF

[0008] POF3+ H2O ■ HPO2F2+ HF

[0009] Given the importance of LiPFe salt in lithium-ion batteries and considering the amount of waste generated in the battery industry, there is an unmet need for recycling LiPFe from waste battery7materials.

[0010] SUMMARY

[0011] Disclosed herein is a method of extracting lithium salt from a waste battery material. The method comprises: contacting the waste battery material with a first solvent comprising a polar aprotic solvent for a time and under conditions where at least a portion of lithium salt present in the waste battery material is dissolved in the first solvent; and mechanically separating the first solvent comprising the dissolved lithium salt from undissolved solids of the waste battery7material to yield a first solution.

[0012] Preferably, the first solvent is substantially anhydrous, i.e., free or nearly free of water. The polar aprotic solvent may include, but is not limited to, a ketone, a nitrile, an ester, an ether, an organosilane, a carbonate solvent, an ionic liquid, a fluorinated ether, a fluorinated ester, a fluorinated dioxolane, a polyfunctional ether, a cyclic polyether, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, dichloromethane, chloroform, pyridine, fluoropyridine, or a combination thereof.

[0013] By way of illustration (and not limitation), the ketone may comprise acetone, methyl ethyl ketone, or a combination thereof; the nitrile may comprise acetonitrile, butyronitrile, succinonitrile, adiponitrile, valeronitrile, or a combination thereof; the ester may comprise ethyl acetate; the ether may comprise dimethoxy ethane, dioxane, diethyl ether, or a combination thereof; the organosilane may be a fluorinated organosilane; the carbonate solvent may comprise dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate or a combination thereof.

[0014] In one version of the method, the polar aprotic solvent is a volatile solvent. In some embodiments, the volatile solvent may comprise tetrahydrofuran, acetone, acetonitrile, diethyl ether, ethyl acetate, dimethyl sulfoxide, chloroform, pyridine, Z-3, 3,3 ,-trifluoro-l (2,2,2- trifluoroethoxy)prop-I-ene, fluonnated dioxolanes such as 2-(trifluoromethyl)di oxolane, 4- (trifluoromethyl)-l,3-dioxolan-2-one, 2-(2,2,2-Trifluoroethyl)-l,3-dioxolane, and the like, or a combination thereof.

[0015] In another version of the method, the polar aprotic solvent comprises a volatile solvent and an organosilane. In one embodiment, the volatile solvent comprises tetrahydrofuran, and the organosilane is a fluorinated organosilane.

[0016] In yet another version of the method, the polar aprotic solvent is a solvent suitable for use in an electrolyte of a lithium-ion cell. In this approach, the solvent suitable for use in an electrolyte of a lithium-ion cell may comprise a carbonate solvent, a polyfunctional ether, a cyclic poly ether, or a combination thereof.

[0017] The method may further comprise subjecting the first solution to one or more postprocessing steps to obtain a second solution, wherein the second solution contains at least a portion of the dissolved lithium salt from the first solution.

[0018] In one version, the method comprises concentrating at least a portion of the first solution by removing at least a portion of the first solvent to obtain the second solution.

[0019] In another version, the method comprises extracting the first solution with a second solvent under conditions where at least a portion of the dissolved lithium salt from the first solution is extracted into the second solvent to yield the second solution. Preferably, the second solvent is a solvent suitable for use in an electrolyte of a lithium-ion cell.

[0020] The lithium salt recovered using the method may comprise lithium hexafluorophosphate (LiPFe), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (L1PO2F2), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), or a combination thereof.

[0021] The amount of the first solvent used in the method is not particularly limited. In certain versions, the first solvent may be used in an amount of about 1 to about 2.5 times the volume of the waste battery material. In certain versions, the first solvent may be used in an amount approximately equal to the volume of the waste battery material.

[0022] The objects and advantages of the disclosure will appear more fully from the following detailed description of the preferred embodiment of the disclosure made in conjunction with the accompanying drawings.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figs. 1A-1C are NMR spectra of a first solution obtained from shredded NMC battery waste using THF as the extracting solvent. The NMR spectra were obtained prior to concentration of the first solution. Fig. 1 A (*H-NMR spectrum) shows peaks corresponding to EC and THF. Fig. IB (19F-NMR spectrum) and Fig. 1C (31P-NMR spectrum) show peaks corresponding to PFe'.

[0025] Figs. 2A-2B are NMR spectra of the second solution (z.e., after concentrating the first solution whose NMR spectra are shown in Figs. 1A-1C). Here, the first solution was concentrated by removing THF under vacuum to form a viscous paste. Fig. 2A is a ’H-NMR spectrum showing peaks corresponding to EC, EMC / DEC, and THF. Fig. 2B is a19F-NMR spectrum showing peaks corresponding to PFe'.

[0026] Figs. 3A-3B show the results of ion chromatography (IC) analysis of the first and second solution obtained from shredded NMC battery waste using THF as the extracting solvent. Fig. 3A shows peaks corresponding to PO2F2' and PFe" in the first solution prior to concentration. Fig. 3B shows peaks corresponding to PFe' after concentrating the first solution to yield the second solution by removing THF under vacuum.

[0027] Figs. 4A-4B are NMR spectra of a second solution (z.e., after concentrating the first solution) obtained from shredded NMC battery waste using a combination of THF and F 1 S3MN as the extracting solvent. The first solution was concentrated by removing THF under vacuum. Fig. 4A shows peaks corresponding to EC and FIS3MN. Fig. 4B shows peaks corresponding to PFe' and FIS3MN.

[0028] Fig. 5 shows the results of IC analysis of the second solution obtained from shredded NMC balteiy waste using a combination of THF and FIS3MN as the extracting solvent. The figure shows peaks corresponding to F' and PFe'. Figs. 6A-6C are NMR spectra of a first solution obtained from shredded NMC batten' waste using DEC as the extracting solvent. Fig. 6A ( 'H-NMR spectrum) shows peaks corresponding to DEC and EC. Fig. 6B (19F-NMR spectrum) and Fig. 6C (31P-NMR spectrum) show peaks corresponding to PFe’.

[0029] Fig. 7 shows the results of IC analysis of the first solution obtained from shredded NMC battery waste using DEC as the extracting solvent. The figure shows peaks corresponding to PFe’.

[0030] Figs. 8A-8B are NMR spectra of a first solution obtained from shredded NMC battery waste using DMC as the extracting solvent. Fig. 8 A (' H-NMR spectrum) shows peaks corresponding to DMC and EC. Fig. 8B (19F-NMR spectrum) shows peaks corresponding to PF6-.

[0031] Fig. 9 shows the results of IC analysis of the first solution obtained from shredded NMC battery waste using DMC as the extracting solvent. The figure shows peaks corresponding to F’ and PFe’.

[0032] Figs. 10A-10B are NMR spectra of a first solution obtained from shredded NMC battery waste using acetone as the extracting solvent. Fig. 10A ('H-NMR spectrum) shows peaks corresponding to acetone and EC. Fig. 10B (19F-NMR spectrum) shows peaks corresponding to PFe’ and PVDF.

[0033] Fig. 11 shows the results of IC analysis of the first solution obtained from shredded NMC battery waste using acetone as the extracting solvent. The figure shows peaks corresponding to PFe’.

[0034] Figs. 12A-12B are NMR spectra of a first solution obtained from shredded NMC battery waste using acetonitrile as the extracting solvent. Fig. 12A ('H-NMR spectrum) shows peaks corresponding to acetonitrile and EC. Fig. 10B (19F-NMR spectrum) shows peaks corresponding to PFe’.

[0035] Fig. 13 shows the results of IC analysis of the first solution obtained from shredded NMC batten’ waste using acetonitrile as the extracting solvent. The figure shows peaks corresponding to PFe’.

[0036] Figs. 14A-14B are NMR spectra of a first solution obtained from shredded NMC battery waste using diethyl ether as the extracting solvent. Fig. 14A ('H-NMR spectrum) shows peaks corresponding to diethyl ether and EC. Fig. 10B (19F-NMR spectrum) shows peaks corresponding to PFe’, PChF’, and PO2F2’.

[0037] Fig. 15 shows the results of IC analysis of the first solution obtained from shredded NMC battery’ waste using diethyl ether as the extracting solvent. The figure shows peaks corresponding to PFe’. Figs. 16A-16C are NMR spectra of a first solution obtained from shredded NMC battery waste using ethyl acetate as the extracting solvent. Fig. 16A ('H-NMR spectrum) shows peaks corresponding to ethyl acetate and EC. Fig. 16B (19F-NMR spectrum) and Fig. 16C (31P-NMR spectrum) show peaks corresponding to PFg'.

[0038] Fig. 17 shows the results of IC analysis of the first solution obtained from shredded NMC batten waste using ethyl acetate as the extracting solvent. The figure shows peaks corresponding to PFe' and F'.

[0039] Figs. 18A-18C are NMR spectra of a first solution obtained from shredded NMC battery waste using dimethyl sulfoxide (DMSO) as the extracting solvent. Fig. 18A ('H-NMR spectrum) shows peaks corresponding to DMSO and EC. Fig. 18B (19F-NMR spectrum) and Fig. 18C (31P-NMR spectrum) show peaks corresponding to PFg'.

[0040] Fig. 19 shows the results of IC analysis of the first solution obtained from shredded NMC battery waste using DMSO as the extracting solvent. The figure shows peaks corresponding to PFg' and F'.

[0041] Fig. 20 shows the results of IC analysis of the first solution obtained from shredded NMC battery waste using Z-3,3,3-trifluoro-l(2,2,2-trifluoroethoxy)prop-l-ene as the extracting solvent. The figure shows peaks corresponding to PFg'.

[0042] Fig. 21 shows the results of IC analysis of the first solution obtained from shredded NMC battery waste using 2-(2,2,2-Trifluoroethyl)-l,3-dioxolane as the extracting solvent. The figure shows peaks corresponding to PFg'.

[0043] Fig. 22 shows the results of IC analysis of the first solution obtained from shredded NMC battery’ waste using chloroform as the extracting solvent. The figure shows peaks corresponding to PFg' and some decomposition products.

[0044] Figs. 23A-23B are NMR spectra of a first solution obtained from shredded NMC battery’ waste using pyridine as the extracting solvent. Fig. 23A ('H-NMR spectrum) shows peaks corresponding to pyridine and EC. Fig. 23B (19F-NMR spectrum) shows peaks corresponding to PFg'.

[0045] Fig. 24 shows the results of IC analysis of the first solution obtained from shredded NMC battery waste using pyridine as the extracting solvent. The figure shows peaks corresponding to PFg' and F'.

[0046] DETAILED DESCRIPTION

[0047] Abbreviations and Definitions

[0048] DEC = Diethyl carbonate; DMF = Dimethylformamide; DMSO = Dimethyl sulfoxide; EC = Ethylene carbonate; HF = Hydrogen fluoride; IC = Ion chromatography; LiBF4 = Lithium tetrafluoroborate; LiBOB = Lithium bis(oxalato)borate; LiDFOB = Lithium difluoro(oxalato)borate; LFP = Lithium iron phosphate; LiFSI = Lithium bis(fluorosulfonyl)imide; LiNCL = Lithium nitrate; LiPFe = Lithium hexafluorophosphate; LiPO2F2 = Lithium difluorophosphate; LiTFSI = Lithium bis(trifluoromethanesulfonyl)imide; NMC = Nickel, Manganese, and Cobalt; NMR = Nuclear magnetic resonance; OS = Organosilicon; THF = Tetrahydrofuran; WBM = Wet black mass.

[0049] As used herein, “solvents” refers generally to polar aprotic solvents that are capable of solubilizing lithium salts such as LiPFe, LiPO2F2, LiFSI, LiTFSI, LiBF4, LiBOB, LiDFOB or a combination thereof.

[0050] As used herein, “polar aprotic solvent” refers to a t pe of solvent characterized by its polarity and inability to donate protons (FL ions). These solvents have polar bonds but lack acidic hydrogen atoms that can be readily donated. Examples of polar aprotic solvents include, but are not limited to, acetone, acetonitrile, ethyl acetate, dichloromethane, chloroform, dioxane, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, tetrahydrofuran (THF), and the like.

[0051] Unless the context clearly dictates otherwise, the solvents used in the method are substantially anhydrous, i.e., free or nearly free of water. Preferably, the solvents contain less than about 1% by weight of water, more preferably less than about 0.5% by weight, and more preferably less than about 0.1% by weight, more preferably less than about 0.05% by weight, and more preferably less than about 0.01% by' weight.

[0052] As used herein, “ionic liquids” refers to organic salts in the liquid state at ambient conditions that consists of an organic cation paired with an organic or inorganic anion. They typically have melting points below 100 °C. Some common examples of ionic liquids include compounds based on the l-ethyl-3-methylimidazolium (EMIM) cation including EMIM chloride (Cl), EMIM acetate (Ac), EMIM dicyanamide, EMIM tetrafluoroborate (BF4), and EMIM hexafluorophosphate (PFo): l-octyl-3-methylimidazolium chloride; and N,N-diethyl- Wmethyl-A-(2-methoxyethyl)ammonium tetrafluoroborate.

[0053] All references to singular characteristics or limitations of the present invention shall include the corresponding plural characteristic or limitation, and vice-versa, unless otherwise specified or clearly implied to the contrary by the context in which the reference is made. The indefinite articles “a” and “an” mean “one or more.”

[0054] As used herein, the term “or” is an inclusive “or” operator and is equivalent to the term “and / or” unless the context clearly' dictates otherw ise.

[0055] Numerical ranges as used herein are intended to include every' number and subset of numbers contained within that range, whether specifically disclosed or not. Further, these numerical ranges should be construed as providing support for a claim directed to any number or subset of numbers in that range. For example, a disclosure of from 1 to 10 should be construed as supporting a range of from 2 to 8, from 3 to 7, from 5 to 6, from 1 to 9, from 3.6 to 4.6, from 3.5 to 9.9, and so forth.

[0056] All patents, patent publications, and peer- reviewed publications (z.e., “references”) cited herein are expressly incorporated by reference to the same extent as if each individual reference were specifically and individually indicated as being incorporated by reference. In case of conflict between the present disclosure and the incorporated references, the present disclosure controls.

[0057] The elements and method steps described herein can be used in any combination or order whether explicitly disclosed or not. All combinations of method steps as used herein can be performed in any order, unless otherwise specified or clearly implied to the contrary by the context in which the referenced combination is made.

[0058] The elements and method steps of the present disclosure can comprise, consist of, or consist essentially of the essential elements, method steps, and limitations described herein, as well as any additional or optional components, method steps, or limitations described herein or otherwise useful in the art. The disclosure provided herein suitably may be practiced in the absence of any elements or method steps which is not specifically disclosed herein.

[0059] It is understood that the compounds and compositions disclosed herein are not confined to the specific construction and arrangement of parts herein illustrated and described, but embraces such modified forms thereof as come within the scope of the claims.

[0060] The method

[0061] Disclosed herein is a method of extracting lithium salts (e.g., LiPFe) from waste battery materials using a polar aprotic solvent to extract and purify the valuable lithium salts from the waste batery materials.

[0062] The waste batery material is not limited and may include manufacturing scrap or field returns containing NMC (nickel manganese cobalt) material or LFP (lithium iron phosphate) cathode materials. The waste batery material may be unshredded cathodes or cathodes in cell (e.g., by puncturing the can and injecting a solvent). Alternatively, the waste batery material may be treated mechanically, e.g., shredded, to yield a “black mass.” The black mass may be a “wet black mass” (WMB) that contains liquid such as residual electrolyte solution and / or moisture content.

[0063] By way of illustration (and not limitation), the waste battery material may comprise: lithium salts such as LiPFs, LiPO2F2, LiFSI, LiTFSI, LiBF4, LiBOB, LiNCh, LiDFOB, or combinations thereof; carbonates such as ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), fluoroethylene carbonate (FEC), vinylene carbonate (VC), propylene carbonate (PC), or combinations thereof; cathode materials such as nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP), lithium cobalt oxide (LCO), nickel cobalt aluminum oxide (NCA), lithium manganese oxide (LMO), Mn-rich cathode materials, Ni-rich cathode materials, or combinations thereof; anode materials such as synthetic or artificial graphite (Gr), lithium (Li) metal, silicon, silicon / graphite (Si / Gr) composites, lithium titanate (LTO), titanium dioxide (TiCh). or combinations thereof; conductive additives such as carbon black; separator films such as polyethylene (PE) or polypropylene (PP); binders such as carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), polytetrafluoroethylene (PTFE), or combinations thereof; current collectors such as copper (Cu) foil and aluminum (Al) foil; cell casing such as aluminum (Al) and stainless steel; tabs and leads such as nickel (Ni), copper (Cu), aluminum (Al) tabs; and flame retardants.

[0064] The method comprises treating recovered, used battery material with a highly solubilizing solvent that extracts at least a portion of lithium salts present in the recovered battery material from the battery material waste (e.g, wet black mass). The lithium salts may comprise LiPFe, LiBF4, LiPO2F2, LiFSI, LiTFSI, or a combination thereof. The solubilized lithium salt may be separated from undissolved solids of the waste battery material using any suitable mechanical separation technique known in the art, such as filtration. This yields a first solution comprising the first solvent (the extracting solvent), lithium salt, and possibly other compounds extracted along with the lithium salt.

[0065] Preferably, the solvent is a polar aprotic solvent that is substantially anhydrous (or as close to anhydrous as can practically be achieved). The polar aprotic solvent may include, but is not limited to, a ketone, a nitrile, an ester, an ether, an organosilane, a carbonate solvent, an ionic liquid, a fluorinated ether, a fluorinated ester, a fluorinated dioxolane, a polyfunctional ether, a cyclic polyether, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, dichloromethane, chloroform, pyridine, fluoropyridine, or a combination thereof.

[0066] By way of illustration (and not limitation), ketone-containing solvents suitable for use in the method include acetone, methyl ethyl ketone, and the like, and combinations thereof. Nitrile-containing solvents suitable for use in the method include acetonitrile, butyronitrile, succinonitrile, adiponitrile, valeronitrile, and the like, and combinations thereof. Ester- containing solvents suitable for use in the method include ethyl acetate, and the like. Ether- containing solvents suitable for use in the method include tetrahydrofuran, dimethoxy ethane, dioxane, diethyl ether, dimethyl ether, and the like, and combinations thereof. Organosilane- containing solvents suitable for use in the method include any of those disclosed in U.S. Patent Nos. 1 1,444,329; 10,790,536; 10,355,313; 9,991,562; 9,917,328; 9,853,321; 9,799,918; 9,680,185; and 9,437,371. Carbonate-containing solvents suitable for use in the method include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, and the like, and combinations thereof. Fluorinated ether-containing solvents suitable for use in the method include vinyl ethers, cyclic and acyclic ethers, and the like, and combinations thereof. Fluorinated ester-containing solvents suitable for use in the method include acyl esters, cyclic and acyclic carbonate esters, and the like, and combinations thereof. Fluorinated dioxolane-containing solvents suitable for use in the method include 2- (2, 2, 2-trifluoroethyl)- 1,3 -dioxolane, and the like. Polyfunctional ether-containing solvents suitable for use in the method include Z-3,3,3-trifluoro-l(2,2,2-trifluoroethoxy)prop-l-ene, and the like. Cyclic polyether-containing solvents suitable for use in the method include fluorinated dioxolanes such as 2-(trifluoromethyl)di oxolane, 4-(trifluoromethyl)-l,3- dioxolan-2-one, 2-(2,2,2-Trifluoroethyl)-l,3-dioxolane, and the like, crown ethers, and the like, and combinations thereof.

[0067] A non-limiting list of organosilanes that can be used in the method includes (but is not limited to): Other compounds that can be used in the method include fluorinated cyanoethers, such as 2-methoxy-3,3,3-trifluoropropionitrile (see WO 2022 / 223678A2):

[0068] Dioxolane-based ethers may also be used, such as 2-(2,2,2-trifluoroethyl)-l,3- dioxolane and 5-trifluoromethyl-2-(2,2,2-trifluoroethyl)-l,3-dioxolane. See WO2022 / 123255A1.

[0069] Fluoro-ethers may also be used, such as 3, 3, 3 -trifluoro- 1(2, 2, 2- trifl uoroethoxy)prop- 1-ene (see WO2022 / 123255A1) and 3,3,3-trifluoro-2(2,2,2- trifluoroethoxy)prop-l-ene (see WO2022 / 123253).

[0070] Other suitable fluoroethers, such as l,l,l-trifluoro-2-methoxy-3-fluoropropane and l,l,l-trifluoro-2-methoxy-3,3-difluoropropane may also be used. See WO2022 / 058714 and WO2021 / 074623.

[0071] Fluorinated oxiranes, dioxanes, and carbonate esters may also be used. See WO2021 / 074627, WO2021 / 069894, and W02020 / 188274, respectively. Representative compounds include:

[0072] 2-Fluoro-3-(trifluoromethyl)oxirane 2,2,5,5-tetrafluoro-l ,4-dioxane and wherein Ri, R2, R3 and R4 are independently selected from the group comprising H, F, Cl, Br, I, CF3, alkyl, fluoroalkyl, haloalkyl with COX2, wherein X is selected from the group comprising -F, -Cl, -OCH3, -OCCI3, imidazole, and succinimidyl.

[0073] The first solution may be subjected to one or more post-processing steps to prepare the recovered lithium salt for use in a battery system. Such post-processing steps may include concentrating the first solution or performing a solvent extraction to obtain a second solution.

[0074] In certain versions, the first solution may be subsequently concentrated by removing at least a portion of the first solvent to obtain a second solution, using any suitable means now known or developed in the future. Such means include, but are not limited to, evaporation or distillation. As used herein, the term '‘evaporation” refers broadly to the process by which the solvent transitions from the liquid phase to the vapor phase, typically through the application of heat, reduced pressure, or both, without the need for boiling. The term “distillation” is used broadly herein to encompass any type of distillation, including simple distillation, destructive distillation, fractional distillation, batch or continuous distillation, steam distillation, vacuum distillation, short path distillation, air-sensitive vacuum distillation, closed-system vacuum distillation (i.e., “cryovap”) and the like. The evaporation or distillation may yield a substantially dry composition comprising the lithium salt.

[0075] In certain versions, the first solution may be extracted with a second solvent (which may be the same or different than the first solvent) under conditions where at least a portion of the dissolved lithium salt from the first solution is extracted into the second solvent to yield a second solution. In a particular embodiment of the method, the second solvent may be a solvent that can be used in lithium-ion batten' systems. In this approach, the second solvent does not need to be removed, but rather can be used in a battery system “as is” or after subsequent purification or other processing steps. In this approach, the second solvent may have a much higher boiling point than the first.

[0076] In one exemplary version of the method, the first solvent is a volatile solvent. The first solution obtained from the extraction may subsequently be concentrated by removing at least a portion of the first solvent to yield a second solution, using any suitable means now know n or developed in the future, such as evaporation or distillation. The evaporation or distillation may produce a substantially dry composition comprising the lithium salt. Alternatively, the first solution may be extracted with a second solvent under conditions where at least a portion of the dissolved lithium salt from the first solution is extracted into the second solvent to yield a second solution. Preferably, the second solvent is a solvent suitable for use in lithium-ion battery systems, and the second solution can be used in a battery system “as is” or after subsequent purification or other processing steps.

[0077] Non-limiting examples of suitable highly volatile solvents include tetrahydrofuran (THF), acetone, acetonitrile, diethyl ether, ethyl acetate, chloroform, pyridine, Z-3,3,3- trifluoro-l(2,2,2-trifluoroethoxy)prop-l-ene, and fluorinated di oxolanes such as 2- (trifluoromethyl)dioxolane, 4-(trifluoromethyl)-l ,3-dioxolan-2-one, 2-(2,2,2-Trifluoroethyl)-

[0078] I,3-dioxolane, and the like. In some cases, less volatile solvents such as dimethyl sulfoxide (DMSO) may also be employed. Exemplary methods and results using these solvents for lithium salt extraction from waste shredded batten,' materials are shown in Examples 1 and 5- 13 below.

[0079] In another exemplary version of the method, the first solvent is a combination solvent comprising a volatile solvent (e g., THF) and an organosilane. Preferably, the organosilane is a fluorinated organosilane.

[0080] Organosilanes are used as electrolyte solvents in lithium-ion batteries for increased thermal stability at elevated temperatures, increased electrolyte flash points for improved safety', increased voltage stability to allow' use of high voltage cathode materials and achieve higher energy density, reduced battery failure rates for consistency with the requirements for large scale Li batteries used in electric vehicle and grid storage applications, and compatibility with materials currently in use in lithium-ion batteries for ease of adoption in cunent designs. Exemplary organosilanes for these purposes are described in, e.g., U.S. Patent Nos.

[0081] I I,444,329; 10,790,536; 10,355,313; 9,991,562; 9,917,328; 9,853,321; 9,799,918; 9,680,185; and 9,437,371, the entirety of which are incorporated herein by reference. Fluorinated organosilanes used as electrolyte in lithium-ion batteries exhibit enhanced properties with reduced viscosity, higher conductivity7, and lower flash point. Exemplary fluorinated organosilanes include FIS3MN, DFIS3MN, TFIS3MN, FIS2MN, DFIS2MN, and TF 1 S2MN, the structures of which are shown above.

[0082] In this approach, the first solution obtained from the extraction may be subsequently concentrated by removing at least a portion of the volatile solvent component to obtain a second solution, using any suitable means now known or developed in the future, such as evaporation and distillation. The organosilane facilitates stabilizing the extracted lithium salt and scavenging HF from the extract. Because the organosilane typically has a high boiling point, it is not removed with the volatile solvent and remains in the mixture with the lithium salt. The resulting second solution can be used directly in a battery system “as is” or after subsequent purification or other process steps. Example 2 shows the use of FIS3MN (4- (fluorodimethylsilyl)butanenitrile) added to THF as the extracting solvent, to stabilize LiPFe and scavenge HF from the samples.

[0083] In another exemplary version of the method, the first solvent is a solvent that can be used in lithium-ion battery systems, including, but not limited to, carbonate-based battery solvent, Z-3,3,3-trifluoro-l(2,2,2-trifluoroethoxy)prop-l-ene, and fluorinated dioxolanes such as 2-(trifluoromethyl)dioxolane, 4-(trifluoromethyl)-l,3-dioxolan-2-one, 2-(2,2,2- Trifluoroethyl)-l,3-dioxolane, and the like. Removal of the solvent is not required, and the extracted lithium salt in the solvent is readily usable in new batteries. Optionally, at least a portion of the solvent may be removed to yield a more concentrated solution of the lithium salt prior to reuse. Examples 3 and 4 show the use of diethyl carbonate (DEC) and dimethyl carbonate (DMC), respectively, as extracting solvents. Examples 10 and 1 1 show the use of Z-3,3,3-trifluoro-l(2,2,2-trifluoroethoxy)prop-l-ene and 2-(2,2,2-Trifluoroethyl)-l,3- dioxolane, respectively, as extracting solvents.

[0084] In any case, the method may further comprise subsequent processing steps, such as to remove entrained water and / or HF from the extract prior to reuse. Any methods now known or developed in the future for these purposes may be used for such removal.

[0085] The following examples are provided to further illustrate the methods described herein. These examples are not intended to limit the scope of the disclosure as set forth in the appended claims. EXAMPLES

[0086] Example 1 :

[0087] Using THF (polar aprotic; highly volatile) as an extracting solvent, this example shows a solvent capable of extracting much of the LiPFe salt from black mass and subsequent easy removal of the solvent afterward.

[0088] THF is a cyclic ether with a boiling point of 66 °C and reasonable polarity to solubilize and extract the LiPFe salt from waste battery material. Because the salt (e.g., LiPFe) is highly hygroscopic and can decompose upon exposure to enough water, dry THF (very low moisture content) was used for the extraction.

[0089] 100 grams of shredded field returns NMC battery waste were weighed and placed in a high-density polyethylene container. THF was added in an amount about 2.5 times (by volume) the amount of the WBM. The extraction may alternatively be carried out using 1 equivalent (by volume) of THF. The slurry was stirred for about 30 minutes and then passed through a bed of filter papers in Buchner funnel. The extracted sample was tested for the presence of LiPFe using NMR and IC (Figs. 1A-1C and 3A). Next, under vacuum, the THF solvent was removed. A composition comprising LiPFe was collected as a viscous paste. Further analysis by IC and NMR helped in confirming the amount and the quality of the material. See Figs. 2A-2B and 3B. The obtained 4 grams of a white paste containing about 1 gram of LiPFe and about 3 grams of ethylene carbonate (EC).

[0090] As shown in the Example, using THF as an extracting solvent, 1 gram of LiPFe was extracted from 100 grams of WBM (1 wt%). NMR gives a doublet in19F-NMR and a septet in31P NMR to confirm the presence of LiPFe (Figs. IB, IC and 2B). The IC analysis gives a broad peak for the presence of PFe anion on anion IC (Figs. 3A-3B).

[0091] Example 2:

[0092] Using a combination extracting solvent (THF + 4-(fluorodimethylsilyl)butanenitrile ("F I S3 MN") organosilane), this example shows a solvent capable of extracting LiPFe salt and stabilizing the extract after THF removal.

[0093] 100 grams of shredded field returns NMC battery waste were weighed and placed in a high-density polyethylene container. The combined extracting solvent was added in an amount about 2.5 times the amount of the WBM. 4-(fluorodimethylsilyl)butanenitrile has the capability to stabilize LiPFe. About 5 v% 4-(fluorodimethylsilyl)butanenitrile was included in the combination extracting solvent. Preferably, about 5 to about 7% of 4- (fluorodimethylsilyl)butanenitrile is added to the extracting solvent to yield the most useful final product. The slurry was stirred for about 30 minutes and then passed through a bed of filter papers in Buchner funnel. The extracted sample was tested for the quality using NMR and IC. Next, under vacuum, the THF solvent was removed by reduced pressure evaporation and a composition comprising LiPFe and the 4-(fluorodimethylsilyl)butanenitrile was collected as liquid. The sample was heated at 80 °C for 2 hours; it did not show signs of decomposition. Because 4-(fluorodimethylsilyl)butanenitrile has a high boiling point, it is not removed under reduced pressure at room temperature. The resulting composition of matter comprises the 4- (fluorodimethylsilyl)butanenitrile, LiPFe and EC. Further analysis by IC and NMR helped in confirming the amount and the quality of the material. See Figs. 4A-4B and 5.

[0094] Example 3 :

[0095] Using diethyl carbonate (DEC) as an extracting solvent, this example shows a solvent capable of extracting LiPFe salt and which also can be used directly in the battery market.

[0096] 100 grams of shredded field returns NMC battery waste were weighed and placed in a high-density polyethylene container. DEC was added in an amount about two times the amount of the WBM. The slurry was stirred for about 30 minutes and then passed through a bed of filter papers in Buchner funnel. The resulting first solution (the extracted and filtered liquid sample) was evaluated using NMR and IC. See Figs. 6A-6C and 7.

[0097] Example 4:

[0098] Using dimethyl carbonate (DMC) as an extracting solvent, this example shows a solvent capable of extracting LiPFe salt and which also can be used directly in the battery market.

[0099] 100 grams of shredded field returns NMC battery waste were weighed and placed in a high-density polyethylene container. DMC was added in an amount about two times the amount of the WBM. The slurry was stirred for about 30 minutes and then passed through a bed of filter papers in Buchner funnel. The resulting first solution (the extracted and filtered liquid sample) was evaluated using NMR and IC. The extracted sample was confirmed to be ~1 gram of LiPFe via IC. See Figs. 8A-8B and 9.

[0100] Example 5:

[0101] Using acetone as an extracting solvent, this example shows a solvent capable of extracting LiPFe salt and subsequent easy removal of the solvent afterward.

[0102] 100 grams of shredded field returns NMC batten- waste were weighed and placed in a high-density polyethylene container. Acetone was added in an amount about two times the amount of the WBM. The slurry was stirred for about 30 minutes and then passed through a bed of filter papers in Buchner funnel. The resulting first solution (the extracted and filtered liquid sample) was evaluated using NMR and IC. The extracted sample was confirmed to be ~1 gram of LiPFg via lC. See Figs. 10A-10B and 11.

[0103] Example 6:

[0104] Using acetonitrile as an extracting solvent, this example shows a solvent capable of extracting LiPfg salt and subsequent easy removal of the solvent afterward.

[0105] 100 grams of shredded field returns NMC battery waste were weighed and placed in a high-density polyethylene container. Acetonitrile was added in an amount about two times the amount of the WBM. The slurry was stirred for about 30 minutes and then passed through a bed of filter papers in Buchner funnel. The resulting first solution (the extracted and filtered liquid sample) was evaluated using NMR and IC. The extracted sample was confirmed to be ~1 gram of LiPFg via IC. See Figs. 12A-12B and 13.

[0106] Example 7 :

[0107] Using diethyl ether as an extracting solvent, this example shows a solvent capable of extracting LiPFg salt and subsequent easy removal of the solvent afterward.

[0108] 100 grams of shredded field returns NMC battery waste were weighed and placed in a high-density polyethylene container. Diethyl ether was added in an amount about two times the amount of the WBM. The slurry7was stirred for about 30 minutes and then passed through a bed of filter papers in Buchner funnel. The resulting first solution (the extracted and filtered liquid sample) was evaluated using NMR and IC. The extracted sample was confirmed to be ~1 gram of LiPFg via IC. See Figs. 14A-14B and 15.

[0109] Example 8:

[0110] Using ethyl acetate as an extracting solvent, this example shows a solvent capable of extracting LiPFg salt and subsequent easy removal of the solvent afterward.

[0111] 2 grams of shredded field returns NMC battery waste were weighed and placed in a polypropylene vial. Ethyl acetate was added in an amount about two times the amount of the WBM. The slurry was stirred for about 30 minutes and then passed through a syringe filter. The resulting first solution (the extracted and filtered liquid sample) was evaluated using NMR and IC. The extracted sample was confirmed to be 36 mg of LiPFg via IC. See Figs. 16A-16C and 17. Example 9:

[0112] Using dimethyl sulfoxide (DMSO) as an extracting solvent, this example shows a solvent capable of extracting LiPFe salt.

[0113] 2 grams of shredded field returns NMC battery waste were weighed and placed in a polypropylene vial. DMSO was added in an amount about two times the amount of the WBM. The slurry was stirred for about 30 minutes and then passed through a syringe filter. The resulting first solution (the extracted and filtered liquid sample) was evaluated using NMR and IC. The extracted sample was confirmed to be ~30 mg of LiPFe via IC. See Figs. 18A- 18C and 19.

[0114] Example 10:

[0115] Using Z-3,3,3-trifluoro-l(2,2,2-trifluoroethoxy)prop-l-ene as an extracting solvent, this example shows a solvent capable of extracting Li PFe salt and subsequent easy removal of the solvent afterward, and which also can be used directly in the battery market.

[0116] 2 grams of shredded field returns NMC battery w aste were weighed and placed in a polypropylene vial. Z-3,3,3-trifluoro-l(2,2,2-trifluoroethoxy)prop-l-ene was added in an amount about two times the amount of the WBM. The slurry' was stirred for about 30 minutes and then passed through a syringe filter. The resulting first solution (the extracted and filtered liquid sample) was evaluated using IC. The extracted sample was confirmed to be ~9 mg of LIPF6via lC. See Fig. 20.

[0117] Example 11 :

[0118] Using 2-(2,2,2-Tnfluoroethyl)-l,3-dioxolane as an extracting solvent, this example show s a solvent capable of extracting LiPFe salt and subsequent easy removal of the solvent afterw ard, and which also can be used directly in the battery' market.

[0119] 2 grams of shredded field returns NMC battery waste were weighed and placed in a polypropylene vial. 2-(2,2,2-Trifluoroethyl)-l,3-dioxolane was added in an amount about two times the amount of the WBM. The slurry' was stirred for about 30 minutes and then passed through a syringe filter. The resulting first solution (the extracted and filtered liquid sample) was evaluated using IC. The extracted sample was confirmed to be ~13 mg of LiPFe via IC. See Fig. 21.

[0120] Example 12:

[0121] Using chloroform as an extracting solvent, this example shows a solvent capable of extracting LiPFe salt and subsequent easy removal of the solvent afterward. 2 grams of shredded field returns NMC battery waste were weighed and placed in a polypropylene vial. Chloroform was added in an amount about two times the amount of the WBM. The slurry was stirred for about 30 minutes and then passed through a syringe filter. The resulting first solution (the extracted and filtered liquid sample) was evaluated using IC. The extracted sample was confirmed to be ~0.5 mg of LiPFg via IC. See Fig. 22.

[0122] Example 13:

[0123] Using pyridine as an extracting solvent, this example shows a solvent capable of extracting LiPFg salt and subsequent easy removal of the solvent afterward. 2 grams of shredded field returns NMC battery waste were weighed and placed in a polypropylene vial. Pyridine was added in an amount about two times the amount of the WBM. The slurry7was stirred for about 30 minutes and then passed through a syringe filter. The resulting first solution (the extracted and filtered liquid sample) was evaluated using NMR and IC. The extracted sample was confirmed to be -30 mg of LiPFg via IC. See Figs. 23 A- 23B and 24.

Claims

CLAIMSWhat is claimed is:

1. A method of extracting lithium salt from a waste battery material, comprising: contacting the waste battery material with a first solvent comprising a polar aprotic solvent for a time and under conditions where at least a portion of lithium salt present in the waste battery' material is dissolved in the first solvent; and mechanically separating the first solvent comprising the dissolved lithium salt from undissolved solids of the waste battery material to yield a first solution.

2. The method of claim 1, wherein the first solvent is substantially anhydrous.

3. The method of claim 1, wherein the polar aprotic solvent comprises a ketone, a nitrile, an ester, an ether, an organosilane, a carbonate solvent, an ionic liquid, a fluorinated ether, a fluorinated ester, a fluorinated dioxolane, a polyfunctional ether, a cyclic polyether, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, dichloromethane, chloroform, pyridine, fluoropyridine, or a combination thereof.

4. The method of claim 3, wherein the ketone comprises acetone, methyl ethyl ketone, or a combination thereof.

5. The method of claim 3, wherein the nitrile comprises acetonitrile, butyronitrile, succinonitrile, adiponitrile, valeronitrile, or a combination thereof.

6. The method of claim 3, wherein the ester comprises ethyl acetate.

7. The method of claim 3, wherein the ether comprises dimethoxy ethane, dioxane, diethyl ether, or a combination thereof.

8. The method of claim 3, wherein the organosilane is a fluorinated organosilane.

9. The method of claim 3, wherein the carbonate solvent comprises dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, or a combination thereof.

10. The method of claim 3, wherein the polar aprotic solvent is a volatile solvent.

11. The method of claim 10, wherein the volatile solvent comprises tetrahydrofuran, acetone, acetonitrile, diethyl ether, ethyl acetate, dimethyl sulfoxide, chloroform, pyridine, Z- 3,3,3,-trifluoro-l (2, 2, 2-tri fluoroethoxy )prop-l -ene, 2-(trifluoromethyl)dioxolane, 4-(trifluoromethyl)-l,3-dioxolan-2-one, 2-(2,2,2-Trifluoroethyl)-l,3-dioxolane, or a combination thereof.

12. The method of claim 3, wherein the polar aprotic solvent comprises a volatile solvent and an organosilane.

13. The method of claim 12, wherein the volatile solvent comprises tetrahydrofuran, and the organosilane is a fluorinated organosilane.

14. The method of claim 3, wherein the polar aprotic solvent is a solvent suitable for use in an electrolyte of a lithium-ion cell.

15. The method of claim 14, wherein the solvent suitable for use in an electrolyte of a lithium-ion cell comprises a carbonate solvent, a polyfunctional ether, a cyclic polyether, or a combination thereof.

16. The method of claim 1, further comprising subjecting the first solution to one or more post-processing steps to obtain a second solution, wherein the second solution contains at least a portion of the dissolved lithium salt from the first solution.

17. The method of claim 16, wherein the method comprises concentrating at least a portion of the first solution by removing at least a portion of the first solvent to obtain the second solution.

18. The method of claim 16, wherein the method comprises extracting the first solution with a second solvent under conditions where at least a portion of the dissolved lithium salt from the first solution is extracted into the second solvent to yield the second solution.

19. The method of claim 18, wherein the second solvent is a solvent suitable for use in an electrolyte of a lithium-ion cell.

20. The method of claim 1, wherein the lithium salt comprises lithium hexafluorophosphate (LiPFg), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), lithium bis(fluorosulfonyl)imide (LiFSl), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), or a combination thereof.

21. The method of claim 1 , wherein the first solvent is used in an amount of about 1 to about 2.5 times the volume of the waste battery material.

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