RECYCLING METHODS FOR LITHIUM-ION BATTERIES

Abstract

Various examples disclosed relate to methods for recycling lithium-ion battery cathode materials. The present disclosure includes methods that use ionic liquids, such as containing tetrachloroaluminate anions, or organic solutions of aluminum chloride, for recycling.

Claims

1. A method of recycling a battery cathode material, the method comprising reducing the battery cathode material with a liquid including chloroaluminate ions and separating materials from the battery cathode material.

2. The method of claim 1, wherein the liquid including chloroaluminate ions comprises an ionic liquid with Lewis neutral chloroaluminate anions.

3. The method of claim 1, wherein the liquid including chloroaluminate ions comprises an ionic liquid with tetrachloroaluminate anions.

4. The method of claim 1, wherein the liquid including chloroaluminate ions comprises an organic solution of aluminum chloride.

5. The method of claim 1, wherein reducing the battery cathode material comprises adding 1-Ethyl-3-methylimidazolium tetrachloroaluminate ionic liquid to the battery cathode material.

6. The method of claim 1, wherein reducing the battery cathode material comprises adding tetrachloroaluminate ionic liquid to the battery cathode material.

7. The method of claim 1, wherein reducing the cathode material comprises adding tetrachloroaluminate ionic liquid to the cathode material at a 1:2 molar ratio.

8. The method of claim 1, wherein reducing the cathode material comprises adding tetrachloroaluminate ionic liquid to the cathode material at a 1:10 molar ratio.

9. The method of claim 1, wherein reducing the cathode material comprises adding tetrachloroaluminate ionic liquid to cathode material at a 1:50 molar ratio.

10. The method of claim 1, wherein reducing the cathode material comprises adding EtOHAlCl.sub.3 solution to the battery cathode material.

11. The method of claim 1, separating materials from the battery cathode material comprises separating and removing cobalt from the battery cathode material.

12. The method of claim 1, separating materials from the battery cathode material e comprises separating and removing lithium from the battery cathode material.

13. The method of claim 1, wherein separating materials from the battery cathode material further comprises centrifuge.

14. The method of claim 1, wherein separating materials from the battery cathode material comprises extracting cobalt as a cation.

15. The method of claim 1, wherein separating materials from the battery cathode material comprises extracting cathode active materials.

16. The method of claim 1, wherein separating materials from the battery cathode material comprises extracting cathode active materials with no emissions.

17. The method of claim 1, wherein separating materials from the battery cathode material comprises extracting cathode active materials at room temperature.

18. The method of claim 1, further comprising preparing the liquid including chloroaluminate ions prior to reducing the lithium-ion battery cathode material.

19. The method of claim 18, wherein preparing the liquid including chloroaluminate ions comprises mixing AlCl.sub.3 in EMIMCl with a molar ratio of 1:1.

20. The method of claim 18, wherein preparing the liquid including chloroaluminate ions comprises gradually adding anhydrous AlCl.sub.3 powder to EMIMCl.

21. The method of claim 18, wherein preparing the liquid including chloroaluminate ions comprises adding anhydrous AlCl.sub.3 to ethanol.

Description

[0016] FIG. 1 illustrates XRD data of lithium-ion battery cathode recycling in an example.

[0017] FIG. 2 illustrates UV-Vis data of lithium-ion battery cathode recycling in an example.

[0018] FIG. 3 illustrates NMR data of lithium-ion battery cathode recycling in an example.

[0019] FIG. 4 illustrates XRD data of lithium-ion battery cathode recycling in an example.

[0020] FIG. 5 illustrates XPS data of lithium-ion battery cathode recycling in an example.

[0021] FIG. 6 illustrates NMR data of lithium-ion battery cathode recycling in an example.

[0022] FIG. 7 illustrates UV-Vis data of lithium-ion battery cathode recycling in an example.

[0023] FIG. 8 illustrates UV-Vis data of lithium-ion battery cathode recycling in an example.

[0024] FIG. 9 illustrates XRD data of lithium-ion battery cathode recycling in an example.

[0025] FIG. 10 illustrates XRD data of lithium-ion battery cathode recycling in an example.

[0026] FIG. 11 illustrates NMR data of lithium-ion battery cathode recycling in an example.

DETAILED DESCRIPTION

[0027] Reference will now be made in detail to certain examples of the disclosed subject matter, examples of which are illustrated in part in the accompanying drawings. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter.

Definitions

[0028] Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of about 0.1% to about 5% or about 0.1% to 5% should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement about X to Y has the same meaning as about X to about Y, unless indicated otherwise. Likewise, the statement about X, Y, or about Z has the same meaning as about X, about Y, or about Z, unless indicated otherwise.

[0029] In this document, the terms a, an, or the are used to include one or more than one unless the context clearly dictates otherwise. The term or is used to refer to a nonexclusive or unless otherwise indicated. The statement at least one of A and B has the same meaning as A, B, or A and B. In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section.

[0030] In the methods described herein, the acts can be carried out in any order without departing from the principles of the disclosure, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

[0031] The term about as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range, and includes the exact stated value or range.

[0032] The term substantially as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%.

[0033] The term organic group as used herein refers to any carbon-containing functional group. Examples can include an oxygen-containing group such as an alkoxy group, aryloxy group, aralkyloxy group, oxo(carbonyl) group; a carboxyl group including a carboxylic acid, carboxylate, and a carboxylate ester; a sulfur-containing group such as an alkyl and aryl sulfide group; and other heteroatom-containing groups. Non-limiting examples of organic groups include OR, OOR, OC(O)N(R).sub.2, CN, CF.sub.3, OCF.sub.3, R, C(O), methylenedioxy, ethylenedioxy, N(R).sub.2, SR, SOR, SO.sub.2R, SO.sub.2N(R).sub.2, SO.sub.3R, C(O)R, C(O)C(O)R, C(O)CH.sub.2C(O)R, C(S)R, C(O)OR, OC(O)R, C(O)N(R).sub.2, OC(O)N(R).sub.2, C(S)N(R).sub.2, (CH.sub.2).sub.0-2N(R)C(O)R, (CH.sub.2).sub.0-2N(R)N(R).sub.2, N(R)N(R)C(O)R, N(R)N(R)C(O)OR, N(R)N(R)CON(R).sub.2, N(R)SO.sub.2R, N(R)SO.sub.2N(R).sub.2, N(R)C(O)OR, N(R)C(O)R, N(R)C(S)R, N(R)C(O)N(R).sub.2, N(R)C(S)N(R).sub.2, N(COR)COR, N(OR)R, C(NH)N(R).sub.2, C(O)N(OR)R, C(NOR)R, and substituted or unsubstituted (C.sub.1-C.sub.100)hydrocarbyl, wherein R can be hydrogen (in examples that include other carbon atoms) or a carbon-based moiety, and wherein the carbon-based moiety can be substituted or unsubstituted.

[0034] The term substituted as used herein in conjunction with a molecule or an organic group as defined herein refers to the state in which one or more hydrogen atoms contained therein are replaced by one or more non-hydrogen atoms. The term functional group or substituent as used herein refers to a group that can be or is substituted onto a molecule or onto an organic group. Examples of substituents or functional groups include, but are not limited to, a halogen (e.g., F, Cl, Br, and I); an oxygen atom in groups such as hydroxy groups, alkoxy groups, aryloxy groups, aralkyloxy groups, oxo(carbonyl) groups, carboxyl groups including carboxylic acids, carboxylates, and carboxylate esters; a sulfur atom in groups such as thiol groups, alkyl and aryl sulfide groups, sulfoxide groups, sulfone groups, sulfonyl groups, and sulfonamide groups; a nitrogen atom in groups such as amines, hydroxyamines, nitriles, nitro groups, N-oxides, hydrazides, azides, and enamines; and other heteroatoms in various other groups. Non-limiting examples of substituents that can be bonded to a substituted carbon (or other) atom include F, Cl, Br, I, OR, OC(O)N(R).sub.2, CN, NO, NO.sub.2, ONO.sub.2, azido, CF.sub.3, OCF.sub.3, R, O (oxo), S (thiono), C(O), S(O), methylenedioxy, ethylenedioxy, N(R).sub.2, SR, SOR, SO.sub.2R, SO.sub.2N(R).sub.2, SO.sub.3R, C(O)R, C(O)C(O)R, C(O)CH.sub.2C(O)R, C(S)R, C(O)OR, OC(O)R, C(O)N(R).sub.2, OC(O)N(R).sub.2, C(S)N(R).sub.2, (CH.sub.2).sub.0-2N(R)C(O)R, (CH.sub.2).sub.0-2N(R)N(R).sub.2, N(R)N(R)C(O)R, N(R)N(R)C(O)OR, N(R)N(R)CON(R).sub.2, N(R)SO.sub.2R, N(R)SO.sub.2N(R).sub.2, N(R)C(O)OR, N(R)C(O)R, N(R)C(S)R, N(R)C(O)N(R).sub.2, N(R)C(S)N(R).sub.2, N(COR)COR, N(OR)R, C(NH)N(R).sub.2, C(O)N(OR)R, and C(NOR)R, wherein R can be hydrogen or a carbon-based moiety; for example, R can be hydrogen, (C.sub.1-C.sub.100)hydrocarbyl, alkyl, acyl, cycloalkyl, aryl, aralkyl, heterocyclyl, heteroaryl, or heteroarylalkyl; or wherein two R groups bonded to a nitrogen atom or to adjacent nitrogen atoms can together with the nitrogen atom or atoms form a heterocyclyl.

[0035] The term deplete as used herein refers to decreasing in quantity or concentration, such as of a liquid, gas, or solute. For example, a mixture of gases A and B can be depleted in gas B if the concentration or quantity of gas B is decreased, for example by selective permeation of gas B through a membrane to take gas B away from the mixture, or for example by selective permeation of gas A through a membrane to add gas A to the mixture.

[0036] The term solvent as used herein refers to a liquid that can dissolve a solid, liquid, or gas. Non-limiting examples of solvents are silicones, organic compounds, water, alcohols, ionic liquids, and supercritical fluids.

[0037] The term room temperature as used herein refers to a temperature of about 15 C. to 28 C.

[0038] The term standard temperature and pressure as used herein refers to 20 C. and 101 kPa.

[0039] In various examples, salts having a positively charged counterion can include any suitable positively charged counterion. For example, the counterion can be ammonium (NH.sub.4.sup.+), or an alkali metal such as sodium (Na.sup.+), potassium (K.sup.+), or lithium (Li.sup.+). In some examples, the counterion can have a positive charge greater than +1, which can in some examples complex to multiple ionized groups, such as Zn.sup.2+, Al.sup.3+, or alkaline earth metals such as Ca.sup.2+ or Mg.sup.2+.

[0040] In various examples, salts having a negatively charged counterion can include any suitable negatively charged counterion. For example, the counterion can be a halide, such as fluoride, chloride, iodide, or bromide. In other examples, the counterion can be nitrate, hydrogen sulfate, dihydrogen phosphate, bicarbonate, nitrite, perchlorate, iodate, chlorate, bromate, chlorite, hypochlorite, hypobromite, cyanide, amide, cyanate, hydroxide, permanganate. The counterion can be a conjugate base of any carboxylic acid, such as acetate or formate. In some examples, a counterion can have a negative charge greater than 1, which can in some examples complex to multiple ionized groups, such as oxide, sulfide, nitride, arsenate, phosphate, arsenite, hydrogen phosphate, sulfate, thiosulfate, sulfite, carbonate, chromate, dichromate, peroxide, or oxalate.

Reaction Mechanisms

[0041] In an example method, lithium metal oxide cathodes such as LiCoO.sub.2, LiNi.sub.xMn.sub.yCo.sub.1-x-yO.sub.2, and any other containing transition metals can be recycled by deep eutectic systems containing AlCl.sub.4.sup. anion, not limited to the presented EMIMAlCl.sub.4 ionic liquid. Any deep eutectic system or ionic liquid containing AlCl.sub.4 may work. The EMIMAlCl.sub.4 ionic liquid is a mixture of aluminum chloride (AlCl.sub.3) and 1-ethyl-3-methylimidazolium aluminum chloride (EMIMCl) at 1:1 molar ratio, and composed of EMIM.sup.+ cation and tetrachloroaluminate anion (AlCl.sub.4.sup.) according to the following reaction:

EMIMCl+AlCl.sub.3.fwdarw.EMIM.sup.++AlCl.sub.4.sup.

[0042] Based on the elemental ratio obtained from experimentation and the identification of products including LiCl, CoCl.sub.4.sup.2, and O.sub.2, lithium may be extracted from the crystal lattice of LiCoO.sub.2 by the strong affinity with Cl.sup. in AlCl.sub.4.sup. anion. Or oxygen vacancy in LiCoO.sub.2 is created by the strong affinity between Al cation and oxide. As a result, Co(III) is reduced to Co(II) by the oxide in LiCoO.sub.2 and oxygen gas may be released. The example reaction mechanisms between LiCoO.sub.2 and AlCl.sub.4.sup. may be as follows:

2AlCl.sub.4.sup.+LiCoO.sub.2.fwdarw.LiCl+CoCl.sub.4.sup.2+O.sub.2+Al.sub.4O.sub.3Cl.sub.6

OR

[0043]
2AlCl.sub.4.sup.+LiCoO.sub.2.fwdarw.LiCl+CoCl.sub.4.sup.2+O.sub.2+AlCl.sub.3+ 3/2AlOCl

[0044] The proposed compound Al.sub.4Cl.sub.6O.sub.3 from the low LiCoO.sub.2/AlCl.sub.4.sup. ratio reaction is amorphous and a stoichiometric combination of the more distinct compounds of AlCl.sub.3 and aluminum oxychloride (AlOCl) from the reaction with high LiCoO.sub.2/AlCl.sub.4.sup. ratio.

[0045] This demonstrates a method to extract lithium and cobalt from LiCoO.sub.2, and this method can be used to recycle spent Li-ion batteries. This method is based on a reaction between tetrachloroaluminate AlCl.sub.4.sup. anion and LiCoO.sub.2. A reagent containing AlCl.sub.4.sup. anion can be used to extract lithium and transition metals from Li-ion batteries using lithium transition metal oxide cathodes including LiCoO.sub.2, LiNi.sub.xMn.sub.yCo.sub.1-x-yO.sub.2, and related materials.

[0046] In other examples, a solution of AlCl.sub.3 in organic solvent can be used as the recycling medium. Where an organic solvent, such as ethanol, is used in preparation of the solution, the following reaction mechanisms may occur:

2AlCl.sub.2.sup.++2LiCoO.sub.2+CH.sub.3CH.sub.2OH .fwdarw.2Li.sup.++2Co.sup.2++4Cl.sup.+Al.sub.2O.sub.3+CH.sub.3COH+H.sub.2O

OR

[0047]
2AlCl.sup.2++2LiCoO.sub.2+CH.sub.3CH.sub.2OH .fwdarw.2Li.sup.++2Co.sup.2++2Cl.sup.+Al.sub.2O.sub.3+CH.sub.3COH+H.sub.2O

[0048] Here, AlCl.sub.2 .sup.+ and AlCl.sup.2+ are aluminum-chloride complex cations and the representative active species in the AlCl.sub.3 solution in ethanol (EtOHAlCl.sub.3) that can react to LiCoO.sub.2. These reaction mechanisms are supported and discussed with reference to the Examples section below.

Methods

[0049] In an example, a method of recycling a lithium-ion battery cathode material, the method comprising reducing the lithium-ion battery cathode material with an liquid including chloroaluminate ionic liquids or AlCl.sub.3 solutions in organic solvents and separating materials from the lithium-ion battery cathode.

[0050] The chloroaluminate ionic liquid can contain Lewis neutral chloroaluminate anions (AlCl.sub.4.sup.) or Lewis acidic chloroaluminate anions (Al.sub.2Cl.sub.7.sup.

[0051] The AlCl.sub.3 solution in organic solvents can contain chloroaluminate anions, chloride anions, and aluminum-chloride complex cations.

[0052] The lithium-ion battery cathode material can include any Li-ion battery cathode material containing lithium and transition metals. The lithium-ion battery cathode material can include, for example, Lithium cobalt oxide (LCO), Lithium nickel cobalt aluminum oxide (NCA), Lithium manganese oxide (LMO), Lithium iron phosphate (LFP), Lithium nickel manganese cobalt oxide LiNi(1-y-z)Mn(y)Co(z)O2(NMC), or combinations thereof.

[0053] Reducing the lithium-ion battery cathode material can include, for example, adding 1-Ethyl-3-methylimidazolium tetrachloroaluminate ionic liquid to the lithium-ion battery cathode material or adding tetrachloroaluminate ionic liquid to the lithium-ion battery cathode material.

[0054] Adding tetrachloroaluminate ionic liquid to the cobalt (or other transition metal) in the lithium-ion battery cathode material can be down at a 1:20 molar ratio, at a 1:10 molar ratio, at a 1:5 molar ratio, or at a 1:2 molar ratio.

[0055] In some cases, reducing the lithium-ion battery cathode material comprises adding EtOHAlCl.sub.3 solution to the lithium-ion battery cathode material.

[0056] Separating materials from the lithium-ion battery cathode comprises separating and removing cobalt from the lithium-ion battery cathode or separating and removing lithium from the lithium-ion battery cathode. In some cases, separating materials from the lithium-ion battery cathode can include centrifuge. In some cases, separating materials from the lithium-ion battery cathode can include extracting cobalt and other transition metals as a cation.

[0057] Separating materials from the lithium-ion battery cathode can include extracting cathode active materials, such as with no emissions, such as at room temperature.

[0058] Preparing the ionic liquid can include chloroaluminate anion prior to reducing the lithium-ion battery cathode material. Preparing the ionic liquid comprises can include mixing AlCl.sub.3 in EMIMCl with a molar ratio of 1:1. In some cases, preparing the ionic liquid can include gradually adding anhydrous AlCl.sub.3 powder to EMIMCl.

[0059] Preparing the AlCl.sub.3 solution inorganic solvents can include adding anhydrous AlCl.sub.3 to ethanol.

Examples

[0060] Various examples of the present disclosure can be better understood by reference to the following Examples which are offered by way of illustration. The present disclosure is not limited to the Examples given herein.

Example 1. Extraction of Lithium and Cobalt from LiCoO.SUB.2 .Cathode via an Ionic Liquid Containing Tetrachloroaluminate Anion (AlCl.SUB.4..SUP..)

[0061] In Example 1, lithium-ion battery cathode materials were recycled through extraction of lithium and cobalt using ionic liquids containing tetrachloroaluminate anion. In Example 1, reactivity of LiCoO.sub.2 with an EMIMAlCl.sub.4 ionic liquid was tested.

[0062] First, a reaction of LiCoO.sub.2 with EMIMAlCl.sub.4 was performed. A 1-Ethyl-3-methylimidazolium tetrachloroaluminate (EMIMAlCl.sub.4) ionic liquid was prepared by slowly mixing AlCl.sub.3 (AlCl.sub.3, anhydrous, 99.99%, Sigma-Aldrich) in 1-Ethyl-3-methylimidazolium Chloride (EMIMCl) (>98%, HPLC, TCI Chemicals) with molar ratio 1:1 (EMIMCl: AlCl.sub.3), then stirring for 12 hours at room temperature before use. 1-Ethyl-3-methylimidazolium Chloride (EMIMCl) (>98%, HPLC, TCI Chemicals) was dried under vacuum inside glovebox at 60 C. for 12 hours before use.

[0063] After preparing the EMIMAlCl.sub.4 ionic liquid, Lithium cobalt oxide (LiCoO.sub.2, 99.8% trace metal basis, Sigma-Aldrich) powder was added with different LiCoO.sub.2: EMIMIAlCl.sub.4 molar ratios (1:20, 1:10, 1:5, and 1:2), then stir for 12 hours at 150 C. The reactor flask is equipped with a condenser on top with water circulating at 10 C. It appears that LiCoO.sub.2 dissolves in EMIMAlCl.sub.4 and the reaction produces a blue solution and white solid precipitate. Generation of oxygen was detected by Dissolved Oxygen Kit (Atlas Scientific).

[0064] For reactions with LiCoO.sub.2/AlCl.sub.4.sup. molar ratios at 1:20, 1:10, and 1:5, the supernatant and the precipitate after the reaction were separated by centrifuge at 20,000 g for 5 min for further analysis.

[0065] X-ray powder diffraction measurement (XRD) was conducted with Panalytical Empyrean Series 2 to analyze the precipitate. The precipitate was washed with benzene three times and then dried inside a glovebox filled with argon gas at room temperature for 24 h. subsequently, the dried powder was pressed to form a pallet on a zero-diffraction silicon plate then the surface was covered with Kapton tape film to prevent the sample's reaction with air and avoiding moisture absorption. XRD measurement was then conducted. The XRD pattern in FIG. 1 indicates that precipitate contains lithium chloride (LiCl).

[0066] Agilent Cary 60 UV-Vis spectrophotometer was used to analyze the Co species in the supernatant. 3 ml of the supernatant liquid diluted with the EMIMAlCl.sub.4 ionic liquid was inserted into a 1010 mm quartz cuvette and sealed with a cap. Baseline measurement were taken on the EMIMAlCl.sub.4 ionic liquid alone in the same cuvette in the range of 550 to 750 nm. FIG. 2 depicts the UV-Vis spectrum of the supernatant after the reaction. The identifiable peaks at 630, 667, and 696 nm are indexed to cobalt tetrachloride anions (CoCl.sub.4.sup.2)

[0067] Liquid state Nuclear Magnetic Resonance (NMR) was also performed on the supernatant. Liquid state NMR spectra (.sup.27Al and .sup.1H) were acquired by Bruker Avance 600 spectrometer with a 14.1 T narrow bore superconducting magnet operating at 104.26 and 600.13 MHz for 27Al and 1H nuclei, respectively. To avoid mixing samples with the standard solution, a double-tube assembly was used where the sample was sealed inside a 5 mm NMR tube with the standard chloroform-d in a 3 mm NMR tube inserted inside the larger tube (with a Sample: Standard volume ratio of 2:3). All liquid-state .sup.27Al and .sup.1H experiments were conducted with radio frequency field strengths of 20.8 kHz and 26 kHz, respectively and with a recycle delay of 12.0 s when all the spins relaxed back to the thermal equilibrium. .sup.27Al and .sup.1H NMR were conducted at 110 C. and 25 C., respectively.

[0068] Comparing to the original EMIMAlCl.sub.4, the .sup.1H nuclear magnetic resonance (NMR) spectra FIG. 3 of the supernatant after the reaction at different LiCoO.sub.2/AlCl.sub.4.sup. molar ratio indicate that the EMIM.sup.+ cation remains intact. The downfield chemical shift with the increasing LiCoO.sub.2/AlCl.sub.4.sup. molar ratio and the broadening of the peaks is due to the paramagnetic effect of Co.sup.2+. The .sup.27Al NMR spectrum of the pristine EMIMAlCl.sub.4 shows a single peak at 104.1 ppm, which represents AlCl.sub.4.sup. anion. Room temperature .sup.27Al NMR spectra of the supernatants after reactions with 1:20 and 1:10 LiCoO.sub.2/AlCl.sub.4.sup. molar ratios also only the AlCl.sub.4.sup. peak, which suggests no soluble Al-containing species generated during the reaction. However, the.sup.27Al NMR spectrum of the supernatant after reaction with 1:5 LiCoO.sub.2/AlCl.sub.4.sup. molar ratio shows a broader peak further shifted to downfield comparing to the ones from 1:20 and 1:10 ratio. A .sup.27Al NMR spectrum of the supernatant from the 1:5 LiCoO.sub.2/AlCl.sub.4.sup. molar ratio was obtained at 150 C. As displayed in the inset of FIG. 3, the spectrum shows two peaks that can be indexed as AlCl.sub.4.sup. and a new anionic species Al.sub.2Cl.sub.7.sup., which is formed from the reaction between AlCl.sub.4.sup. and AlCl.sub.3 according to following reaction:

AlC.sub.4.sup.+AlCl.sub.3.fwdarw.Al.sub.2C.sub.7.sup.

Therefore, this result indicates that AlC.sub.3 may be produced from the reaction with high LiCoO.sub.2/AlCl.sub.4.sup. molar ratio.

[0069] The reaction between LiCoO.sub.2 and EMIMAlCl.sub.4 ionic liquid with 1:2 molar ratio resulted to a paste-like product due to the high content of precipitate. This paste product is characterized by X-ray diffraction (XRD). The XRD patterns of the project in FIG. 4 shows pattern of LiCl when a Kapton tape was used to seal the sample to prevent contact from ambient environment. Once the tape was removed, the XRD pattern indicated the content of AlCl.sub.3.Math.6H.sub.2O, in which the crystal water is likely absorbed from the environment. The XRD also indicate EMIMCl and CoCl.sub.2.

[0070] Oxygen gas was identified in the reaction with the LiCoO.sub.2: EMIMAlCl.sub.4 molar ratio of 1:2. The reaction was sealed and closed inside a glovebox with O.sub.2<0.01 ppm. When the reaction was complete, the valve connected to the reaction flask was opened while the exhaust relighted a dying match proving the presence of oxygen. This suggests that oxygen gas is generated from the reaction.

[0071] Based on the finding that LiCl, CoCl.sub.4.sup.2, and O.sub.2 are three of the products, it is likely that lithium is extracted from the crystal lattice of LiCoO.sub.2 by the strong affinity with Cl.sup. in AlCl.sub.4.sup. anion. Or, oxygen vacancy is created due to the strong affinity between O.sup.2+ and Al.sup.3+. As a result, Co(III) is reduced to Co(II) by the oxide in LiCoO.sub.2 and oxygen gas may be released.

[0072] Based on the above spectroscopic analyses, the reaction mechanisms between LiCoO.sub.2 and AlCl.sub.4.sup. are as follows:

2AlCl.sub.4.sup.+LiCoO.sub.2.fwdarw.LiCl+CoCl.sub.4.sup.2+O.sub.2+Al.sub.4O.sub.3Cl.sub.6 at relatively low ratio of LiCoO.sub.2/AlCl.sub.4.sup.

OR

[0073]
2AlCl.sub.4.sup.+LiCoO.sub.2.fwdarw.LiCi+CoCl.sub.4.sup.2+O.sub.2+AlCl.sub.3+AlOCl at relatively high ratio of LiCoO.sub.2/AlCl.sub.4.sup.

The compound Al.sub.4Cl.sub.6O.sub.3 from the low LiCoO.sub.2/AlCl.sub.4.sup. ratio reaction is amorphous and a stoichiometric combination of the more distinct compounds of AlCl.sub.3 and aluminum oxychloride (AlOCl) from the reaction with high LiCoO.sub.2/AlCl.sub.4.sup. ratio.

[0074] X-ray photoelectron spectroscopy (XPS) analysis was performed on the product from the reaction with 1:2 LiCoO.sub.2/AlCl.sub.4.sup. molar ratio. XPS data was collected using Kratos AXIS Supra (Al K=1486.7 eV) at UC Irvine Materials Research Institute (IMRI). The samples were transported to the XPS facility inside a stainless-steel tube with KF flange sealing filled with argon. The samples were loaded in the sample chamber in the glovebox integrated with Kratos AXIS Supra for XPS analysis. All peaks of XPS data were analyzed by Casa XPS52 and calibrated with the reference peak of C is at 284.6 eV (the adventitious carbon).

[0075] FIG. 5 shown the cobalt 2p X-ray photoelectron spectroscopic (XPS) spectra of the pristine LiCoO.sub.2 and the product. The cobalt 2p spectrum of the pristine LiCoO.sub.2 shows the binding energy difference between satellite of 2p 1/2 (790.4 eV) and 2p 1/2 (780 eV) is 10 eV, which indicates the valence of cobalt ion is 3+. For the cobalt 2p XPS spectrum of the product, there is distinguishable change of the binding energy difference between satellite of 2p 1/2 (785.8 eV) and 2p 1/2 (780.8 eV) is about 5 eV, which indicate the valence of cobalt ion in the product is 2+. The XPS spectra comparison clearly demonstrates that Co(III) in LiCoO.sub.2 is converted to Co(II) in the reaction.

[0076] An additional demonstration of extraction of cobalt and lithium from battery materials was demonstrated with visual testing. The products from the reaction with the 1:2 LiCoO.sub.2/AlCl.sub.4.sup. molar ratio was completely soluble in water, resulting in a transparent solution with the characteristic pink color representing hydrated Co(II). White precipitate is generated when the water solution is stirred in ambient environment at 70 C. overnight. Inductively coupled plasma optical emission spectrometry (ICP-OES) analysis show the only metal content in the precipitate is Al, and the XRD demonstrates its amorphous nature. This is likely aluminum oxide (Al.sub.2O.sub.3) generated from the oxidization of AlOCl and Al.sub.4O.sub.3Cl.sub.6. The water is evaporated from the solution after the precipitate is filtered out. The resulted blue power was further heated at 150 C. for overnight. The heated power was added into water, and a pink solution with white precipitate was the produced. The precipitate is Al.sub.2O.sub.3 converted from AlCl.sub.3 by heating, and it is filtered out.

[0077] Inductively coupled plasma optical emission spectrometry (ICP-OES) was conducted on the samples including the final pink supernatant and the total precipitate. The amount of aluminum (Al), cobalt (Co), and lithium (Li) were determined by a Perkin-Elmer Optima 7300DV ICP-OES apparatus. The percentage of the metal in the supernatant and precipitate are listed in Table 1.

TABLE-US-00001 TABLE 1 Percentage of metals in the final products after lithium and cobalt extraction. Al (%) cobalt (%) lithium (%) Supernatant 0.39 0.002 99.86 0.52 36.16 0.09 Precipitate 99.61 0.39 0.14 0.005 63.82 0.46

[0078] The elemental analysis shows that 99.61% of the Al (from the AlCl.sub.4.sup. anion) is removed as the precipitate (Al.sub.2O.sub.3); 99.86% of the cobalt was extracted in the aqueous solution as Co.sup.2+ cation. The aqueous solution also contains 36.16% of the total Li, and the rest of 63.82% of lithium exist in the precipitate.

[0079] This demonstrates a method to extract lithium and cobalt from LiCoO.sub.2, and this method can be used to recycle spent Li-ion batteries. This method is based on a reaction between tetrachloroaluminate AlCl.sub.4.sup. anion and LiCoO.sub.2. Based on these results, it is likely that any reagent containing AlCl.sub.4.sup. anion can be used to extract lithium and transition metals from Li-ion batteries using lithium transition metal oxide cathodes including LiCoO.sub.2, LiNi.sub.xMn.sub.yCo.sub.1-x-yO.sub.2, and related materials.

Example 2. Lithium-ion Battery Recycling Technology with Organic Solutions of Aluminum Chloride

[0080] In Example 2, AlCl.sub.3 solutions in ethanol (EtOHAlCl.sub.3) is used for lithium-ion battery cathode material recycling. Here, 10 wt. % of AlCl.sub.3 (98.5%, anhydrous powder, Thermo Fisher Scientific) was slowly added to 10 ml of ethanol (99.5%, 200 proof, anhydrous, Sigma-Aldrich) while keeping the solution cold inside an argon filled glove box (H.sub.2O and O.sub.2<0.1 ppm). Then, LiCoO.sub.2 or LiNi.sub.0.6Mn.sub.0.2Co.sub.0.2Co.sub.0.2(NMC622) with a molar ratio of 2:1 (Al: LiCoO.sub.2 or NMC622) was added to the EtOHAlCl.sub.3 solution. The sample was heated at 75 C. for 12 h with a condenser on top (10 C.). LiCoO.sub.2 or NMC622 is completely dissolved during the reaction.

[0081] The EtOHAlCl.sub.3 solution and the solutions after the reaction with LiCoO.sub.2 or NMC622 were characterized with a number of methods. The liquid state .sup.27Al and .sup.1H NMR spectra were obtained by a Bruker Avance 600 spectrometer. The spectrometer was operating at 104.26 and 600.13 MHz for 27Al and 1H nuclei, respectively with a 14.1 T narrow bore superconducting magnet carried out with radio frequency field strengths of 20.8 kHz and 26 kHz, respectively and all the spines relaxed back to the thermal equilibrium at a recycle delay of 12.0 s. No standard solution was used in the experiments and all the signals were detected in room temperature.

[0082] The .sup.27Al nuclear magnetic resonance (NMR) spectrum (FIG. 6) on the EtOHAlCl.sub.3 (10 wt. % of AlCl.sub.3) solution at room temperature clearly show the two distinct signals at 9.8 and 12.8 ppm which are assigned to [AlCl(EtOH).sub.5].sup.2+ and [AlCl.sub.2(EtOH).sub.4].sup.+ cations, respectively. When LiCoO.sub.2 (molar ratio of Co/Al is 1:2) was completely dissolved in the solution at 75 C. after 12 h, no new .sup.27Al NMR peak is observed (FIG. 6) except that the [AlCl(EtOH).sub.5].sup.2+ and [AlCl.sub.2(EtOH).sub.4].sup.+ peaks are shifted down filed due to the magnetic effect from the dissolved Co(II) cations.

[0083] An Agilent Cary 60 UV-Vis spectrophotometer was employed for UV-Visible spectroscopy. The spectrum of the pristine EtOHAlCl.sub.3 solution in a range of 350 to 750 nm was used as the baseline measurement. The solutions after the reactions with NMC622 or LiCoO.sub.2 were diluted with the EtOHAlCl.sub.3 solution for UV-Vis measurement. The samples were contained in a 1010 mm quart cuvette sealed with a plastic cap.

[0084] The existence of Co(II) cations is evidenced by the UV-Vis spectrum of the solution after reaction with LiCoO.sub.2 as shown in FIG. 7. The Spectrum shows the characteristic peaks of cobalt tetrachloride anions (CoCl.sub.4.sup.2), and the inset of the FIG. 7 display the picture of the cobalt blue colored solution. Same dissolution behavior of NMC622 in EtOHAlCl.sub.3 is also observed under the identical reaction condition. FIG. 8 shows the UV-Vis spectrum of the solution after NMC622 dissolved, and it shows the characteristic peaks of CoCl.sub.4.sup.2 and NiCl.sub.4.sup.2 anions. The MnCl.sub.4.sup.2 anion does not absorb in the UV-Vis range. The inset of FIG. 8 is the photo of the NMC622 solution in EtOHAlCl.sub.3, which displays the characteristic green color of Ni(II). After the reaction completed, ethanol was evaporated and collected with rotary evaporation to obtain blue (from LiCoO.sub.2) and green (NMC622) powder. Rotary evaporation of ethanol was carried out with a rotation speed of 120 rpm, and temperature of 80 C. under vacuum.

[0085] The crystal structure of the powder was identified using X-ray powder diffraction measurement (XRD) utilizing a Panalytical Empyrean Series 2. All the samples were dried at 80 C. in vacuum for 12 h inside an argon filled glove box. Then, the dried powders were pressed on a zero-diffraction silicon plate to form a flat pallet. The surface was sealed with Kapton tape to avoid contact with air and moisture. The scan range was from 10 to 900 with a 0.013 step size and a time per step of 148.92 s.

[0086] The X-ray diffraction (XRD) pattern of the blue powder (from LiCoO.sub.2) in FIG. 9 clearly indicates the content of lithium chloride (LiCl) and cobalt(II) chloride (COCl.sub.2). FIG. 10 displaying the XRD pattern of the green powder (from NMC622) indicates the content of LiCl, CoCl.sub.2, nickel(II) chloride (NiCl.sub.2), and manganese(II) chloride (MnCl.sub.2). The analyses above indicate that the transition metals in the cathode materials are reduced from M(III) to M(II).

[0087] Oxygen gas tests were performed on the samples. Here, Oxygen gas was identified using a 100 g EtOHAlCl.sub.3 batch with the LiCoO.sub.2 molar ratio of 2:1=Al:Co which was sealed and closed inside a glovebox with O.sub.2<0.01 ppm. Gas test does not detect the generation of oxygen gas; therefore it is unlikely that the oxide in the cathodes is the reducing reagent.

[0088] A possible reducing reagent is ethanol, which is known can be reduced to acetaldehyde. Additional NMR characterization was done to follow up on this. FIG. 11 shows the .sup.1H NMR of the EtOHAlCl.sub.3 after complete dissolution of LiCoO.sub.2 (dotted line). To identify acetaldehyde as a reaction product, .sup.1H NMR spectrum was also obtained from the same solution added with 10 vol. % anhydrous acetaldehyde (solid line in FIG. 11). The comparison proves the formation of acetaldehyde after the reaction as indicated by the doublet at 4 ppm.

[0089] Based on the analysis above, following reaction mechanism between EtOHAlCl.sub.3 and LiCoO.sub.2 is proposed using AlCl.sub.2.sup.+ and AlCl.sup.2+ as the representative active species:

2AlCl.sub.2.sup.+2LiCoO.sub.2+CH.sub.3CH.sub.2OH .fwdarw.2Li.sup.++2Co.sup.2++4Cl.sup.+Al.sub.2O.sub.3+CH.sub.3COH+H.sub.2O

OR

[0090]
2AlCl.sup.2++2LiCoO.sub.2+CH.sub.3CH.sub.2OH .fwdarw.2Li.sup.++2Co.sup.2++2Cl.sup.+Al.sub.2O.sub.3+CH.sub.3COH+H.sub.2O

NMC622 follows the same reaction mechanism.

[0091] Efficiency of the leaching and purification steps were measured through Inductively coupled plasma optical emission spectrometry (ICP-OES) by measuring the amount of aluminum (Al), cobalt (Co), and lithium (Li) utilizing a Perkin-Elmer Optima 7300DV ICP-OES apparatus. A known amount (mg) of the sample was dissolved in a highly acidic solution then the volume was brought up to 100 ml.

[0092] The ICP-OES measurement indicates that the Al content in the blue powder from LiCoO.sub.2 can be readily removed via water rinsing and filtration after heat treatment at 150 C. The heated powder was mixed in deionized water and then pink transparent supernatant and white precipitate can be separated. The elemental analysis with ICP-OES of the supernatant and precipitate is listed in Table 2.

TABLE-US-00002 TABLE 2 Percentage of metals in the final products after lithium and cobalt extraction. Al (%) cobalt (%) lithium (%) Supernatant 4.46 0.05 99.48 0.03 49.76 0.13 Precipitate 95.53 0.05 0.52 0.03 50.24 0.13

[0093] These results demonstrate that EtOHAlCl.sub.3 is able to extract the cathode active materials with high efficiency, low temperature, and no emission. When compared with the hydrometallurgical processes, extremely acidic solutions (pH below zero) were utilized for increasing the leaching efficiency along with the addition of a reducing agent such as H.sub.2O.sub.2. Here the low acidity of the solution proposed indicates the importance of the aluminum complexes in the extraction of transition metals without any requirement for introducing H.sub.2O.sub.2 to the system since ethanol is acting as a reducing agent. Including primary aliphatic alcohols, the method is universal to all other solvents which form any kind of AlCl.sub.n.sup.(3-n)(where n=4, 3, 2, and 1) ion when dissolving AlCl.sub.3. For instance, AlCl.sub.3 in diglyme and tetraglyme forms AlCl.sub.4.sup. anion and AlCl.sub.2 cation or in Tetrahydrofuran (THF), aluminum complexes such as AlCl.sub.3(THF).sub.2 along with AlCl.sub.4.sup., [AlCl.sub.2(THF).sub.4].sup.+ and [AlCl(THF).sub.5].sup.2+ are formed. All these AlCl.sub.3 solutions show a high leaching efficiency for cathode materials. This new type of extraction reagents composed of AlCl.sub.3 in organic solvents can be used to recycle spent Li-ion batteries with any type of lithium transition metal oxide cathodes.

[0094] The terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the examples of the present disclosure. Thus, it should be understood that although the present disclosure has been specifically disclosed by specific examples and optional features, modification and variation of the concepts herein disclosed may be resorted to by those of ordinary skill in the art, and that such modifications and variations are considered to be within the scope of examples of the present disclosure.

ADDITIONAL EXAMPLES

[0095] The following exemplary examples are provided, the numbering of which is not to be construed as designating levels of importance:

[0096] Example 1 is a method of recycling a lithium-ion battery cathode material, the method comprising reducing the lithium-ion battery cathode material with an ionic liquid including chloroaluminate anion and separating materials from the lithium-ion battery cathode.

[0097] In Example 2, the subject matter of Example 1 optionally includes wherein the ionic liquid comprises Lewis neutral chloroaluminate anions.

[0098] In Example 3, the subject matter of any one or more of Examples 1-2 optionally include wherein the ionic liquid comprises tetrachloroaluminate anions.

[0099] In Example 4, the subject matter of any one or more of Examples 1-3 optionally include wherein the ionic liquid comprises an organic solution of aluminum chloride.

[0100] In Example 5, the subject matter of any one or more of Examples 1-4 optionally include -methylimidazolium tetrachloroaluminate ionic liquid to the lithium-ion battery cathode material.

[0101] In Example 6, the subject matter of any one or more of Examples 1-5 optionally include wherein reducing the lithium-ion battery cathode material comprises adding tetrachloroaluminate ionic liquid to the lithium-ion battery cathode material.

[0102] In Example 7, the subject matter of any one or more of Examples 1-6 optionally include 1:2 molar ratio.

[0103] In Example 8, the subject matter of any one or more of Examples 1-7 optionally include 1:10 molar ratio.

[0104] In Example 9, the subject matter of any one or more of Examples 1-8 optionally include 1:50 molar ratio.

[0105] In Example 10, the subject matter of any one or more of Examples 1-9 optionally include solution to the lithium-ion battery cathode material.

[0106] In Example 11, the subject matter of any one or more of Examples 1-10 optionally include separating materials from the lithium-ion battery cathode comprises separating and removing cobalt from the lithium-ion battery cathode.

[0107] In Example 12, the subject matter of any one or more of Examples 1-11 optionally include separating materials from the lithium-ion battery cathode comprises separating and removing lithium from the lithium-ion battery cathode.

[0108] In Example 13, the subject matter of any one or more of Examples 1-12 optionally include wherein separating materials from the lithium-ion battery cathode comprises centrifuge.

[0109] In Example 14, the subject matter of any one or more of Examples 1-13 optionally include wherein separating materials from the lithium-ion battery cathode comprises extracting cobalt as a cation.

[0110] In Example 15, the subject matter of any one or more of Examples 1-14 optionally include wherein separating materials from the lithium-ion battery cathode comprises extracting cathode active materials.

[0111] In Example 16, the subject matter of any one or more of Examples 1-15 optionally include wherein separating materials from the lithium-ion battery cathode comprises extracting cathode active materials with no emissions.

[0112] In Example 17, the subject matter of any one or more of Examples 1-16 optionally include wherein separating materials from the lithium-ion battery cathode comprises extracting cathode active materials at room temperature.

[0113] In Example 18, the subject matter of any one or more of Examples 1-17 optionally include preparing the ionic liquid including chloroaluminate anion prior to reducing the lithium-ion battery cathode material.

[0114] In Example 19, the subject matter of Example 18 optionally includes mixing AlCl.sub.3 in EMIMCl with a molar ratio of 1:1

[0115] In Example 20, the subject matter of any one or more of Examples 18-19 optionally include powder to EMIMCl.

[0116] In Example 21, the subject matter of any one or more of Examples 18-20 optionally include to ethanol.