Manufacturing methods for recycled materials

Abstract

To provide a method for manufacturing recycled materials with reduced levels of impurities. [Solution] A method for manufacturing recycled material includes (a) preparing battery material, (b) forming molten glass by melting the battery material, (c) separating the molten glass from at least one selected from the group consisting of metal materials and organic compounds contained in the battery material, and (d) forming a glass material by cooling the molten glass.

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing recycled materials. [Background technology]

[0002] Japanese Patent Publication No. 2021-9838 (Patent Document 1) discloses a positive electrode containing an olivine-type phosphate compound as a positive electrode active material. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-9838 [Overview of the project] [Problems that the invention aims to solve]

[0004] Battery materials such as electrodes contain various renewable materials. The production of recycled materials by recovering renewable materials from battery materials is being considered. However, other battery materials may become mixed in with the recycled material to be produced. These contaminants may degrade the performance of the recycled material.

[0005] The purpose of this disclosure is to provide a method for producing recycled materials with reduced amounts of impurities. [Means for solving the problem]

[0006] The technical configuration and effects of this disclosure are described below. However, the mechanism of action of this disclosure includes assumptions. The mechanism of action does not limit the technical scope of this disclosure.

[0007] [1] (a) Prepare the battery materials, (b) Forming molten glass by melting the battery material, (c) Separating the molten glass from at least one selected from the group consisting of metallic materials and organic compounds contained in the battery material, and (d) Forming a glass material by cooling the molten glass, A method for manufacturing recycled materials, including

[0008] It is assumed that metallic materials and organic compounds will not be mixed into the molten glass. Therefore, by melting the battery material to form molten glass, it is expected that the metallic materials and organic compounds will be more easily separated, thereby suppressing their inclusion in the recycled material.

[0009] [2] The method for producing a recycled material according to [1], wherein the battery material comprises at least one selected from the group consisting of a positive electrode, a negative electrode, and a bipolar electrode.

[0010] The battery material can be any material, as long as it includes at least one selected from the group consisting of metallic materials and organic compounds. Examples of battery materials include positive electrodes, negative electrodes, and bipolar electrodes.

[0011] [3] The battery material comprises a phosphate, (e) To obtain glass powder by crushing the glass material, (f) Heat treatment of the glass powder, A method for producing recycled material according to [1] or [2], further comprising:

[0012] When battery materials contain phosphates, it is expected that trace amounts of impurities (e.g., chromium) will react with phosphoric acid and become harmless.

[0013] [4] The battery material comprises an olivine-type phosphate compound. The method for producing the recycled material according to [3].

[0014] [5] The above (b) is, (b1) Adding flux to the battery material, (b2) Maintaining the battery material at a temperature of 700 °C or higher and 900 °C or lower, (b3) Maintaining the battery material at a temperature of 1000 °C or higher and 1100 °C or lower, The method for producing a recycled material according to any one of [1] to [4], which includes these steps in this order.

[0015] By adding a flux to the battery material, the melting of the battery material is promoted. By maintaining the battery material at a temperature of 700 °C or higher and 900 °C or lower, the separation of the metal material is expected to be promoted, and by maintaining the battery material at a temperature of 1000 °C or higher and 1100 °C or lower, the separation of the organic compound is expected to be promoted.

[0016] Hereinafter, embodiments of the present disclosure (hereinafter may be abbreviated as "the present embodiments") will be described. However, the present embodiments do not limit the technical scope of the present disclosure. The present embodiments are illustrative in all respects. The present embodiments are non-limiting. The technical scope of the present disclosure includes all modifications within the meaning and scope equivalent to the description of the claims. For example, any configurations are extracted from the present embodiments and the present examples, and their arbitrary combinations are also initially planned.

Brief Description of Drawings

[0017] [Figure 1] It is a schematic flowchart of the method for producing a recycled material in the present embodiment. [Figure 2] It is a schematic flowchart of the method for producing a recycled material in Examples No. 3 to 5. [Figure 3] It is a table showing the production conditions and experimental results of the recycled material in the examples.

Modes for Carrying Out the Invention

[0018] <Terms and Phrases> "Comprising", "including", "having", and their modifications are open-ended expressions. A configuration expressed in an open-ended manner may further include additional elements in addition to the essential elements, or may not include them.

[0019] "Recycled materials" refers to all materials that can be recovered from battery materials. Recycled materials are not limited to active materials. For example, substrates (e.g., aluminum foil, copper foil, etc.) are also recycled materials. Electrode composites are also recycled materials. The applications of recycled materials are not limited to batteries. Recycled materials may be used for applications other than batteries.

[0020] "Battery material" refers to any material, component, or part included in a battery. Battery material may be a single element or a mixture (e.g., composite material). Battery material may also be a composite (e.g., an electrode), a molded body, etc.

[0021] "Black mass" refers to a concentrate obtained by heat treatment (roasting) of batteries, crushing of the roasted material, and sorting of the crushed material. Black mass contains, for example, metals such as nickel, cobalt, manganese, and iron, as well as organic compounds. The metals may be components derived from, for example, the positive electrode active material or current collector foil. The organic compounds may be components derived from, for example, the conductive material or binder.

[0022] <Method for manufacturing recycled materials> Figure 1 is a schematic flowchart of the method for manufacturing recycled material in this embodiment. Hereinafter, "the method for manufacturing recycled material in this embodiment" may be abbreviated as "this manufacturing method". This manufacturing method includes "(a) preparation", "(b) melting", "(c) separation", and "(d) cooling". This manufacturing method may further include, for example, "(e) crushing" and "(f) calcination". In this manufacturing method, "(b) melting" may further include, for example, "(b1) addition of flux", "(b2) first melting", and "(b3) second melting".

[0023] (a) Preparation This manufacturing method includes preparing battery materials.

[0024] The battery material is arbitrary. The battery material may include, for example, at least one selected from the group consisting of a positive electrode, a negative electrode, and a bipolar electrode. The battery material may also include at least one black mass selected from the group consisting of a positive electrode, a negative electrode, and a bipolar electrode. The battery material can be prepared by any method. For example, various battery materials may be recovered by dismantling used batteries, defective batteries, etc. For example, black mass may be formed by subjecting used batteries, defective batteries, etc. to various treatments such as roasting.

[0025] The positive electrode includes a positive electrode current collector foil and a positive electrode composite material. The positive electrode current collector foil may contain, for example, aluminum. The positive electrode composite material is attached to the positive electrode current collector foil. The positive electrode composite material includes, for example, a positive electrode active material, a conductive material, a binder, etc. The positive electrode active material may contain, for example, lithium nickel composite oxide (LNO), lithium-containing composite phosphate, etc. The conductive material may contain, for example, graphite, carbon black, carbon fiber, carbon nanotubes, graphene flakes, etc. The binder may contain, for example, polyvinylidene fluoride, etc.

[0026] LNO may have a crystal structure belonging to the space group R-3m, for example. The space group is identified by powder X-ray diffraction (XRD) measurement. LNO may have a composition represented by the following general formula, for example. Li 1-a Ni x M 1-x O2 In the formula, the relationships -0.5 ≤ a ≤ 0.5 and 0 ≤ x ≤ 1 may be satisfied. M may include, for example, at least one selected from the group consisting of Co, Mn, and Al.

[0027] LNO may be represented, for example, by the following general formula. Compounds represented by the following general formula may also be called "NCM". Li 1-a Ni x Co y Mn z O2 In the formula, the relationships of -0.5 ≤ a ≤ 0.5, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1 may be satisfied.

[0028] The lithium-containing composite phosphate contains at least one selected from the group consisting of nickel, cobalt, manganese, and iron. When the battery material contains phosphate, it is expected that trace contaminants capable of reacting with phosphoric acid are rendered harmless. Examples of the lithium-containing composite phosphate include olivine-type phosphate compounds.

[0029] The olivine-type phosphate compound may have, for example, a crystal structure belonging to the space group Pnma. The olivine-type phosphate compound may include, for example, lithium iron phosphate (LFP), lithium manganese phosphate (LMP), etc. In LMP, a part of manganese (Mn) may be substituted with iron (Fe). The Fe-substituted product of LMP is also referred to as lithium manganese iron phosphate (LMFP). LMP may have, for example, a composition represented by the following general formula. Li 1-a Mn 1-x Fe x PO4 For example, the relationships of -0.5 ≤ a ≤ 0.5 and 0 ≤ x ≤ 1 may be satisfied.

[0030] The negative electrode includes a negative electrode current collector foil and a negative electrode composite material. The negative electrode current collector foil may include, for example, copper or the like. The negative electrode composite material adheres to the negative electrode current collector foil. The negative electrode composite material includes, for example, a negative electrode active material, a conductive material, a binder, etc. The negative electrode active material may include, for example, graphite, soft carbon, hard carbon, silicon, silicon oxide, silicon-carbon composite material (Si / C material), lithium titanium composite oxide, etc. The conductive material is the same as that of the positive electrode composite material. The binder may include, for example, carboxymethyl cellulose, styrene-butadiene rubber, etc.

[0031] The bipolar electrode includes a positive electrode composite material, a positive electrode current collector foil, a negative electrode current collector foil, and a negative electrode composite material. For example, an adhesive may bond the positive electrode current collector foil and the negative electrode current collector foil. The positive electrode composite material and the negative electrode composite material are in a front-back relationship.

[0032] (b) Melting This manufacturing method includes forming molten glass by melting battery materials.

[0033] The melting temperature and melting time (maintenance time) may be adjusted as appropriate depending on the battery material. For example, the melting temperature may be between 600°C and 1100°C. For example, the melting time may be between 60 minutes and 120 minutes.

[0034] The molten atmosphere can be adjusted as appropriate depending on the battery material. For example, the molten atmosphere may be a nitrogen atmosphere or an atmospheric atmosphere.

[0035] (b1) Addition of flux This manufacturing method may include, for example, adding a flux to the battery material. The flux has a melting point lower than the melting temperature. The flux may be, for example, a hydroxide, chloride, carbonate, etc., containing at least one alkali metal selected from the group consisting of lithium, sodium, and potassium. Examples of fluxes include lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium chloride, sodium chloride, potassium chloride, lithium carbonate, sodium carbonate, potassium carbonate, etc.

[0036] The amount of flux added can be adjusted as appropriate depending on the battery material. The amount of flux added may be, for example, 1% to 20% by mass fraction relative to the battery material.

[0037] (b2) First melt and (b3) Second melt In this manufacturing method, for example, two stages of melting may be performed. That is, a first melt and a second melt may be performed in this order. The second melt may be at a higher temperature than the first melt. The first melt temperature may be, for example, 600°C to 900°C, 700°C to 900°C, or 700°C to 800°C. The second melt temperature may be, for example, 900°C to 1100°C, or 1000°C to 1100°C.

[0038] The first and second melts may be performed (maintained) for the same amount of time, or for different amounts of time. For example, the first and second melts may be performed for 60 minutes each. For example, the first and second melts may be performed for 30 minutes and 90 minutes, or for 90 minutes and 30 minutes.

[0039] (c) Separation This manufacturing method includes separating molten glass from at least one selected from the group consisting of metallic materials and organic compounds contained in the battery material.

[0040] Metallic materials may originate from positive electrode current collector foil, negative electrode current collector foil, etc. Organic compounds may originate from conductive materials, binders, etc.

[0041] The separation method is arbitrary. For example, the liquid component (molten glass) and the solid component may be separated by filtration. For example, the target liquid component (molten glass) and the liquid component containing impurities may be separated by specific gravity separation.

[0042] If the above step (b) includes steps (b2) and (b3), this step may be performed after each of those steps. For example, after the liquid and solid components are separated after step (b2), the separated solid components may be melted by step (b3) and the liquid and solid components may be separated again.

[0043] (d) Cooling This manufacturing method includes forming a glass material by cooling molten glass.

[0044] Cooling may be carried out, for example, at a predetermined rate of cooling, by simple air cooling (natural cooling), or by rapid cooling in the ambient air.

[0045] For example, glass material may be used as recycled material as is (direct recycling). For example, as will be described later, various recycled materials may be manufactured by processing glass material.

[0046] (e) Grinding This manufacturing method may include obtaining glass powder by crushing glass material.

[0047] The grinding method is optional. For example, it may be ground using a ball mill or mortar and pestle.

[0048] (f) firing This manufacturing method may include heat treatment of the glass powder. This step can be applied, for example, when manufacturing a cathode active material as a recycled material.

[0049] The heat treatment temperature and time may be adjusted as appropriate depending on the battery material (positive electrode active material). For example, the heat treatment temperature may be between 200°C and 700°C. For example, the heat treatment time may be between 1 hour and 6 hours.

[0050] The heat treatment atmosphere can be adjusted as appropriate depending on the battery material (positive electrode active material). For example, the heat treatment atmosphere may be a nitrogen atmosphere or an atmospheric atmosphere.

[0051] This manufacturing method is expected to facilitate the separation of metallic materials and organic compounds, thereby suppressing their contamination of the recycled material. Regarding the obtained recycled material, the amount (mass fraction) of contaminated metallic material can be measured by ICP-AES (Inductively coupled plasma atomic emission spectroscopy). The amount (mass fraction) of contaminated organic compounds (carbon) can be measured by a carbon-sulfur analyzer (CS analyzer). [Examples]

[0052] <Manufacturing of recycled materials> (No. 1, 2) A black mass containing only the roasted positive electrode was prepared as a battery material. The positive electrode contained aluminum foil as the positive electrode current collector foil and LMFP as the positive electrode active material. The black mass was roasted at 400°C for 2 hours. Roasting was carried out in an air atmosphere for No. 1 and in a nitrogen atmosphere for No. 2.

[0053] The calcined material was crushed using a ball mill to obtain a powder.

[0054] Recycled material (recycled LMFP) was produced by adding a carbon source to the powder and firing it in a nitrogen atmosphere.

[0055] (No.3~5) Figure 2 is a schematic flowchart of the manufacturing method for recycled material (recycled LMFP) in Examples No. 3 to 5. Each step was then carried out according to Figure 2.

[0056] (a) Preparation The aforementioned black trout was prepared.

[0057] (b) melting and (c) separation Black mass was mixed with 10% potassium chloride by mass fraction. A saggar containing the mixture was placed in a firing furnace. Melting was carried out in a nitrogen atmosphere using the following procedure. First, the furnace temperature was increased at a rate of 10°C / min until it reached the temperature shown in Figure 3 (first melting temperature). The furnace temperature shown in Figure 3 was maintained for 1 hour. After 1 hour, the saggar was removed from the firing furnace and the liquid components were removed. The liquid components may include aluminum and potassium chloride. Next, the saggar was placed back into the firing furnace. The furnace temperature was increased at a rate of 5°C / min until it reached the temperature shown in Figure 3 (second melting temperature). The furnace temperature shown in Figure 3 was maintained for 1 hour. After 1 hour, the saggar was removed from the firing furnace and molten glass was obtained by removing the solid components floating on the surface. The solid components may include organic compounds.

[0058] (d) Cooling The glass material was obtained by allowing the molten glass to cool naturally to 400°C.

[0059] (e) Grinding Glass powder was obtained by crushing the glass material using a ball mill.

[0060] (f) firing Recycled material (recycled LMFP) was produced by adding a carbon source to glass powder and firing it in a nitrogen atmosphere.

[0061] (Coin cell production) A mixture was formed by mixing the positive electrode active material, conductive material (acetylene black), and binder (PVdF). The mixing ratio (mass ratio) was "positive electrode active material / conductive material / binder = 92 / 5 / 3". A paste was formed by dispersing the mixture in a solvent (N-methyl-2-pyrrolidone). The solid content concentration of the paste was 50% by mass fraction. The positive electrode layer was formed by applying the paste to the surface of aluminum foil and drying it. The density of the positive electrode layer was 1.8 g / cm³ by roll pressing. 3The cathode material was formed by adjusting the material. The cathode material was subjected to vacuum drying at 120°C for 12 hours. After drying, a disc sample (diameter: 14 mm) was removed from the cathode material by punching.

[0062] The coin cell was assembled inside the glove compartment. The cell configuration is as follows: Working electrode: Disc sample (positive electrode) Opposite pole: Li foil Separator: Polymer porous membrane Electrolyte: Ethylene carbonate / dimethyl carbonate = 3 / 7 (volume ratio), LiPF6 (1 ml / L)

[0063] <Rating> (measurement) For each sample No., powder (glass powder) was prepared before the addition of the carbon source. The amount of aluminum (mass fraction) contained in each powder was measured. The amount of carbon (mass fraction) contained in each powder was measured using a CS meter. The results are shown in Figure 3. Note that the reduction in aluminum content is evaluated using No. 1 as the baseline, and the reduction in carbon content is evaluated using No. 2 as the baseline.

[0064] (capacity) The capacity (mAh / g) was measured for each coin cell number. The results are shown in Figure 3.

[0065] <Result> As shown in Figure 3, when the manufacturing conditions of this disclosure are met, there is a tendency for the amount of impurities to decrease. Also, Nos. 3-5 have a larger volume compared to Nos. 1-2.

Claims

1. (a) Prepare the battery materials, (b) Forming molten glass by melting the battery material, (c) Separating the molten glass from at least one selected from the group consisting of metal materials and organic compounds contained in the battery material, and (d) Forming a glass material by cooling the molten glass, A method for manufacturing recycled materials, including

2. The method for producing a recycled material according to claim 1, wherein the battery material includes at least one selected from the group consisting of a positive electrode, a negative electrode, and a bipolar electrode.

3. The aforementioned battery material contains a phosphate, (e) To obtain glass powder by crushing the glass material, (f) The glass powder is subjected to heat treatment. A method for producing recycled material according to claim 1, further comprising:

4. The method for producing a recycled material according to claim 3, wherein the battery material comprises an olivine-type phosphate compound.

5. The above (b) is, (b1) Adding flux to the battery material, (b2) Maintain the battery material at a temperature of 700°C or higher and 900°C or lower. (b3) Maintain the battery material at a temperature of 1000°C or higher and 1100°C or lower. A method for producing recycled material according to any one of claims 1 to 4, comprising the following in this order.

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