Preparation of black materials

Abstract

Described herein is a method for purifying a black material for a battery, comprising the steps of providing a prepared cathode or anode black material, contacting the prepared black material with an alkaline mixture, where the alkaline mixture comprises at least one alcohol and at least one alkoxide. Also disclosed is the use of the alkaline mixture for the purification of black materials.

Description

Technical Field

[0001] The present invention relates to a method for purifying black materials and an application of purifying black materials with an alkaline mixture. Background Art

[0002] In the sustainable utilization of raw materials, recycling has become increasingly important. Traditional (thermal) mechanical recycling processes usually result in significant pollution. For example, when directly recycling NMC (nickel manganese cobalt mixed oxide) cathode waste in battery core production, the aluminum content is too high. The combination of different processes (thermal, wet, and dry mechanical) usually results in insufficient quality (purity of recyclable raw materials, too high aluminum content).

[0003] In the end-of-life (EoL) recycling of batteries, there is a solvent extraction method that extracts individual metals as recyclable raw materials.

[0004] Document US9825341B2 discloses the use of solvents to prepare battery materials.

[0005] Document WO2022 / 133585A1 discloses a method for recovering metals from black materials using formic acid and hydrogen peroxide.

[0006] Document EP3806229 A1 discloses a method for recycling lithium-ion batteries using polar solvents.

[0007] Document CN115347266A discloses a method for recycling lithium-ion batteries by wet grinding. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a method for purifying black materials and an application of purifying black materials with an alkaline mixture, which at least partially overcomes the above disadvantages.

[0009] The above technical problem is solved by the method according to the present invention as claimed in claim 1 and the application as claimed in claim 8.

[0010] Further advantageous designs of the present invention are derived from the dependent claims and the description of the preferred embodiments of the present invention below.

[0011] The method for purifying black materials of batteries according to the present invention comprises the steps of:

[0012] - providing the prepared black materials,

[0013] - contacting the prepared black materials with an alkaline mixture, wherein the alkaline mixture comprises at least one alcohol and at least one alkoxide.

[0014] The black material of the battery is an electrochemically active layer that contains various metals such as lithium, manganese, copper, nickel, cobalt, etc. In the case of the cathode, the black material is an aluminum foil on which a layer composed of NMC (nickel-manganese-cobalt mixed oxide), binder, conductive additive, etc. is applied. NMC can be replaced by other active materials such as iron phosphate, nickel-cobalt-aluminum oxide, or sulfur compounds. Lithium can be used as an additional cation. In the case of the anode, the black material is mainly graphite with a binder and a conductive additive. The black material can also include silicon, graphene, and / or lithium titanium dioxide. Generally, most active materials are doped with additional metals.

[0015] Here it can be the black material of the cathode or the black material of the anode. In an alternative embodiment, it can also be a mixture composed of the black material of the cathode and the black material of the anode.

[0016] The black material can come from waste streams, i.e., recyclable feed streams, and these streams can be processed specifically. It is advantageous for each preparation to separate the material streams in advance. For example, it can bring advantages to the anode because it can be specifically adapted to the anode foil, such as a copper foil, and through (thermal) mechanical treatment, its residues can be specifically avoided and removed, and thus a black material with very few impurities is produced. Therefore, on the anode side, due to the availability of relatively inert active materials and aqueous systems, impurities such as copper can be selectively removed, and even the separation of aluminum may not be required due to the single classification (Sortenreinheit).

[0017] The method according to the present invention includes the step of providing a prepared black material, preferably a high-purity black material, for example, by using a single-classified input stream (for example, a material stream from production waste or pre-classified materials can be used). High purity means, for example, that the impurity content of the black material is at most 2000 ppm, preferably at most 500 ppm, and further preferably at most 20 ppm. The preparation can be various mechanical and / or chemical methods. In one embodiment, the preparation can be mechanically crushing production waste / scrap into black material. Mechanical crushing can include fragmentation, cutting, grinding, electrohydraulic crushing, deagglomeration, or other crushing processes.

[0018] Chemical preparation can be treatment with appropriate chemicals such as organic or inorganic acids or bases.

[0019] It is also conceivable that, additionally, or alternatively to mechanical or chemical preparation, thermal preparation is carried out.

[0020] The mechanically and / or chemically and / or thermally treated black material can also be divided into fractions of different particle sizes. Additionally or alternatively, individual particles can also be separated.

[0021] Preferably, the black material is processed into a powdered material. For example, the prepared black material can be a single-classified powdered cathode material.

[0022] In a further step of the method, the prepared black material is contacted with an alkaline mixture, wherein the alkaline mixture comprises at least one alcohol and at least one alkoxide.

[0023] In one embodiment, the at least one alcohol is selected from C 3 -C 8 alcohols. Preferably, the at least one alcohol is selected from C 3 -C 6 alcohols. The at least one alcohol may be selected from propanol, isopropanol, n-butanol, pentanol, and hexanol isomers.

[0024] The at least one alcohol is preferably n-butanol.

[0025] The at least one alcohol may also be a mixture of at least two alcohols. The at least one alcohol may also be a mixture of at least one alcohol (such as C 3 -C 8 alcohol) and water.

[0026] In addition, the alkaline mixture comprises at least one alkoxide. In one embodiment, the alkoxide is an alkali metal alkoxide or a transition metal alkoxide. The alkoxide may also be an alkaline earth metal alkoxide.

[0027] The alkali metal alkoxides may be selected from the group consisting of lithium alkoxides, sodium alkoxides, and potassium alkoxides. In one embodiment, the alkali metal alkoxide is a lithium alkoxide.

[0028] The transition metal alkoxides may be selected from the group consisting of iron alkoxides, nickel alkoxides, and chromium alkoxides.

[0029] The at least one alkali metal alkoxide or transition metal alkoxide may also be a mixture of at least two alkoxides.

[0030] The alkoxide is preferably matched with the at least one alcohol used. For example, the alcohol may be butanol and the alkoxide may be butoxide.

[0031] Preferably, the alkaline mixture comprises isopropanol and lithium isopropoxide. Alternatively, the alkaline mixture may comprise tert-butanol and lithium tert-butoxide.

[0032] The at least one alcohol and the at least one alkoxide may be present in a determined ratio. The ratio of the at least one alcohol to the at least one alkoxide may be in the range of 99:1 to 8:2, preferably in the range of 99:1 to 9:1, and more preferably in the range of 98:2 to 95:5.

[0033] In one embodiment, the alkaline mixture has a pH value in the range greater than 7.5. In a preferred embodiment, the alkaline mixture has a pH value in the range of 8 to 14, and in another preferred embodiment, the alkaline mixture has a pH value in the range of 9 to 12.

[0034] The alkaline mixture may also have other components. The alkaline mixture may have complexing agents or other auxiliary materials. For example, the alkaline mixture may have complexing agents for various metals, such as aluminum complexing agents.

[0035] By bringing the prepared black material into contact with the alkaline mixture, the components of the black material, such as aluminum and / or aluminum oxide, can be selectively separated. Aluminum can form amphoteric aluminum with the alkaline mixture and is thus separated from the prepared black material. By forming amphoteric aluminum, even small amounts of aluminum can be separated, and thus the prepared black material is purified. Particularly preferably, the other components of the black material are not eroded or damaged by the alkaline mixture, and the particle structure of components such as NMC (nickel manganese cobalt mixed oxide) is not eroded.

[0036] The separated components, such as aluminum, can be sent for further processing or recycling and thus re-introduced into the material cycle.

[0037] The black material can be a dry black material. The dry black material from battery recycling does not include liquid components such as electrolytes or liquid battery slurries. Instead, the dry black material can be a coated coil, a material crumpled in a malfunction, a single sheet or a stacked material, which is re-classified (separating cathodes, anodes, separators, auxiliary materials) and, if necessary, previously removed from the housing (hard case or soft pack). The dry black material especially comes from production waste.

[0038] Alternatively, it can also be a wet black material. The wet black material from battery recycling includes liquid components such as electrolytes or liquid battery slurries. The wet black material can come from defective batteries, battery materials during mixing and coating processes, or batteries that have reached the end of their service life.

[0039] If a wet black material is used, it can be wet-ground with the alkaline mixture and thus continue to be applied in the process.

[0040] The method may also include the step of mechanically separating the black material and the alkaline mixture. The mechanical separation can be filtration, screening, sedimentation, centrifugation or other mechanical separation processes. The separation can be carried out, for example, by a sieve, a decanter, a filter, etc.

[0041] The separated black material can be further purified. The further purification can be carried out by washing or washing multiple times with a suitable solvent or even with the alkaline mixture. The washed black material can then have the solvent or the alkaline mixture removed. This can be carried out by drying at a high temperature, passing dry air or an inert gas stream over it, or by washing with a solvent (such as NMP) that is favorable for further processing the black material. Solvent recovery may be included here.

[0042] The subject matter of the present invention further includes the use of an alkaline mixture comprising at least one alcohol and at least one alkoxide for purifying a black material. The black material can be a dry black material, as described. Alternatively, it can be a wet black material, as described.

[0043] The alkaline mixture, at least one alcohol and at least one alkoxide can be the alkaline mixture, alcohol and alkoxide as described herein. Preferably, the alkaline mixture comprises at least one lithium alkoxide. The lithium alkoxide can be the lithium alkoxide as described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Embodiments of the present invention will now be described by way of example and with reference to the accompanying drawings, in which,

[0045] Figure 1 schematically shows a method according to the present invention,

[0046] Figure 2 schematically shows a method according to the present invention,

[0047] Figure 3 schematically shows a method according to the present invention. DETAILED DESCRIPTION

[0048] An embodiment of method 100 according to the present invention is shown in Figure 1 . Method 100 for purifying a black material of a battery comprises step 101, in which a prepared black material is provided. The prepared black material is then contacted 102 with an alkaline mixture, wherein the alkaline mixture comprises at least one alcohol and at least one alkoxide.

[0049] Figure 2Another embodiment 200 of a method for purifying the black mass of a battery is shown. First, a conventional black mass acquisition 203 can be carried out. The conventional black mass acquisition 203 can be a dry mechanical delamination. When necessary, heat preparation and / or dry separation are also carried out in the conventional black mass acquisition 203. The prepared black mass 201 and residues 210, such as aluminum foil, can be obtained through the conventional black mass acquisition 203. The residues 210, such as aluminum foil, can be fed into an aluminum recycling process 211. The prepared black mass 201 can then be contacted with an alkaline mixture 202, thereby forming a slurry. The alkaline mixture includes at least one alcohol and at least one alkoxide (such as lithium alkoxide) herein. Thereby, the aluminum still present in the black mass can be selectively dissolved. Then, mechanical separation 204 can be carried out by removing the contaminated solvent, for example, by filtration, decantation (or said pouring), etc. The separated solid material can be cleaned by washing 205 and contacted with the alkaline mixture 202 again. The solid material 206 obtained from the separation 204 is the prepared black mass. The liquid 207 obtained from the separation 204 is at least one alcohol, at least one alkoxide, and at least one aluminum ion or at least one aluminum complex. At least one alcohol, at least one alkoxide, and the aluminum ion or aluminum complex can be fed into a regeneration process 208. Herein, at least one alcohol, at least one alkoxide, and / or the aluminum ion or aluminum complex are re-prepared and reused. Then, the residual moisture 209 can be removed, and thereby, for example, the solvent that cannot be reused is removed. The removal of the residual moisture 209 can be carried out by drying and / or washing with a suitable solvent (such as NMP).

[0050] Figure 3 Another embodiment 300 of a method for purifying the black mass of a battery is shown. First, a conventional pre-crushing of the battery material 312 can be carried out. The conventional pre-crushing can be carried out by a crusher or a cutting mill. Then, the crushed material 313 can be fed into a wet grinding process 314. Herein, the crushed material 313 is wet ground with at least one alcohol and at least one alkoxide (such as lithium alkoxide). Parallel delamination and dissolution of the existing aluminum occur herein. In the next step, a multi-stage mechanical separation 315 of the liquid, foil, black mass, and optionally existing grinding media can be carried out. The mechanically separated material is washed 305 when necessary and fed into the wet grinding process 314 again. Through the mechanical separation 315, a solid material 306, that is, the prepared black mass, a liquid 307, such as at least one alcohol, at least one aluminum alkoxide or aluminum complex, and an aluminum foil 316 can be produced. The aluminum foil can be fed into an aluminum recycling process 311. At least one alcohol, at least one alkoxide, and aluminum can be fed into a regeneration process 308. Herein, at least one alcohol, at least one alkoxide, and / or aluminum are re-prepared and reused. Then, the residual moisture 309 can be removed, and thereby, for example, the solvent that cannot be reused is removed. The removal of the residual moisture 309 can be carried out by drying and / or washing with a suitable solvent (such as NMP).

[0051] Example: Preparation of the cathode black material after a simple mechanical process for obtaining the black material

[0052] 1. Shred the cathode foil

[0053] 2. Pyrolyze at 500 °C for 1 hour if necessary

[0054] 3. Hammer mill (sieve diameter 5 mm)

[0055] 4. Screen with a vibrating screen (125 µm)

[0056] 5. Add the fine fraction (about 100 g) to a stirring container containing 1000 g of isopropanol and 50 g of lithium-2-propanolate dissolved in the alcohol

[0057] 6. Mix for 45 minutes to dissolve the aluminum impurities

[0058] 7. Filter (5 µm)

[0059] 8. Solid material: Add to a stirring container containing 1000 g of isopropanol and 10 g of lithium-2-propanolate dissolved in the alcohol

[0060] 9. Filter at 5 µm

[0061] 10. Dry the solid material in an oven at 85 °C

[0062] 11. Control impurities by IPC

[0063] List of reference numerals

[0064] 100, 200, 300 Methods for purifying the black material

[0065] 101, 201 Provide the prepared black material

[0066] 102, 202 Contact the prepared black material with an alkaline mixture

[0067] 203 Conventional black material acquisition

[0068] 204 Mechanical separation

[0069] 205, 305 Cleaning

[0070] 206, 306 Solid material

[0071] 207, 307 Liquid

[0072] 208, 308 Recycling process

[0073] 209, 309 Removal of residual moisture

[0074] 210 Residue

[0075] 211, 311 Aluminum Recycling Process

[0076] 312 Pre-Crushed Battery Materials

[0077] 313 Crushed Materials

[0078] 314 Wet Grinding

[0079] 315 Mechanical Separation

[0080] 316 Aluminum Foil

Claims

1. A method for purifying black material of a battery, comprising the steps of: - Providing a prepared cathode or anode black material, - contacting the prepared black mass with an alkaline mixture, wherein: The alkaline mixture includes at least one alcohol and at least one alkoxide.

2. The method according to claim 1, wherein: At least one alcohol is a C3-C8 alcohol.

3. The method according to claim 1 or claim 2, wherein: At least one alkoxide is an alkali metal alkoxide or a transition metal alkoxide.

4. The method according to at least one of claims 1 to 3, wherein: At least one alkoxide is a lithium alkoxide.

5. The method according to at least one of claims 1 to 4, wherein: The alkaline mixture has a pH value in the range of greater than 7.

5.

6. The method according to at least one of claims 1 to 5, wherein: The ratio of the at least one alcohol to the at least one alkoxide is in the range of 99:1 to 8:

2.

7. The method according to at least one of claims 1 to 6, wherein: Black material is dry black material.

8. The method according to at least one of claims 1 to 6, wherein: The prepared black material is wet ground with the alkaline mixture.

9. The method according to at least one of claims 1 to 8, further comprising the step of mechanically separating the black material and the alkaline mixture.

10. Use of an alkaline mixture comprising at least one alcohol and at least one alkoxide for purifying black materials.

11. The use according to claim 10, wherein the alkaline mixture comprises at least one lithium alkoxide.

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