Recycled positive electrode precursor, method for manufacturing recycled positive electrode precursor, and recycled lithium-ion battery using recycled positive electrode precursor

Abstract

To provide a recycled positive electrode precursor that can contribute to an increase in the recycling of used batteries accompanying the increase in demand for lithium ion batteries, and a recycled lithium ion battery using the recycled positive electrode precursor, and to provide a method for manufacturing a recycled positive electrode precursor that can manufacture a positive electrode precursor from black mass in a simple process.SOLUTION: A recycled positive electrode precursor is a powdered recycled positive electrode precursor primarily composed of manganese, with iron, copper, and aluminum contents each less than 0.5 mass%. The average particle size of the recycled positive electrode precursor is 0.01 μm to 50 μm. The cobalt content of the recycled positive electrode precursor is 31 mass% to 85 mass%. The nickel content of the recycled positive electrode precursor is 31 mass% to 85 mass%. The specific surface area of the recycled positive electrode precursor is 10 m2 / g or greater.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a recycled positive electrode precursor, a method for producing the recycled positive electrode precursor, and a recycled lithium-ion battery using the recycled positive electrode precursor. [Background technology]

[0002] In recent years, lithium-ion batteries have been used in a wide range of electronic and electrical devices, including hybrid and electric vehicles, smartphones, and PCs, and production volumes are increasing. However, as electric vehicles (EVs) become more widespread in the future, the number of used and discarded batteries is expected to increase.

[0003] Because lithium-ion batteries contain valuable materials such as nickel and cobalt, it is important to recover these materials from used lithium-ion batteries and reuse them in the manufacture of new lithium-ion batteries. There is a need for an increased supply of recycled positive electrode precursors to meet the growing demand for lithium-ion batteries and the increasing need to recycle used batteries.

[0004] Conventional methods for recovering useful materials from lithium-ion batteries include dry refining using heat treatment and hydrometallurgy using solutions. However, these methods are costly and do not recover all the necessary materials. In addition, when considering the purity and quality of the recovered metal resources, recycling costs, and the price of the metal resources, they are difficult to make a profit from and are not profitable.

[0005] Patent Document 1 describes a method for producing a recycled cathode material precursor, in which a heat-treated product obtained by heat-treating a lithium-ion battery at a predetermined temperature is crushed, and the crushed product is physically separated by classification or magnetic separation. This method is a hydrometallurgical process in which, after physical separation, the physically treated product is treated with an acid to dissolve the metal elements in the physically treated product, and the acid-treated solution is treated with an alkali to precipitate and recover the metal elements in the acid-treated solution as hydroxides.

[0006] The method of Patent Document 1 has the problem that it requires many steps such as physical sorting and treatment with acid and alkali solutions, which makes the recycling cost high and makes it unprofitable.

[0007] On the other hand, if metal particles are contained in the precursor during the process of manufacturing electrodes using black mass as a precursor, the deposits in the electrode may grow into dendrites (needle-shaped crystals), causing an internal short circuit and the risk of fire. For this reason, there is a need to thoroughly remove metals that can cause short circuits from black mass. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 7176707 specification Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been made in consideration of the above-mentioned conventional problems, and has an object to provide a recycled positive electrode precursor that has a low content of conductors such as iron, copper, and aluminum, and is capable of preventing ignition, and that can contribute to an increase in the recycling of waste batteries accompanying the increase in demand for lithium-ion batteries, as well as a recycled lithium-ion battery that uses the recycled positive electrode precursor, and to provide a method for producing a recycled positive electrode precursor that can produce a positive electrode precursor from black mass in a simple process. [Means for solving the problem]

[0010] The first means for solving the above problem is: The recycled positive electrode precursor is a powdered precursor mainly composed of manganese, and has an iron, copper, and aluminum content of less than 0.5 mass % each. The average particle size of the recycled positive electrode precursor is 0.01 μm to 50 μm. The cobalt content in the recycled positive electrode precursor is 31% by mass to 85% by mass. The content of nickel in the recycled positive electrode precursor is 31% by mass to 85% by mass. The specific surface area of ​​the recycled positive electrode precursor is 10 m 2 / g or more.

[0011] The second means for solving the above problem is: a crushing step of crushing a fired product obtained by firing the cathode material recovered from used batteries into powder; a dispersing step of dispersing the powder with a dispersant to obtain a dispersion; a magnetic separation step of extracting cobalt, nickel, and compounds from the dispersion by magnetic separation; a calcination step of calcining the dispersion from which the cobalt, nickel and compounds have been removed; The present invention relates to a method for producing a recycled positive electrode precursor. The pulverization step uses a jet mill or a roll mill to produce powder of 50 μm or less. In the magnetic separation process, the powder is made to flow through a pipe as a liquid dispersion, and downstream of a magnet placed outside the pipe, the flow is divided into a flow containing magnetic materials consisting of cobalt, nickel, and their compounds and a flow containing non-magnetic materials, and the two flows are separated. In the calcination step, the dispersion containing cobalt, nickel, and compounds is heated to 700°C or higher, and C is added to remove oxides that may ignite, thereby obtaining a powder containing cobalt, nickel, and compounds.

[0012] The third means for solving the above problem is: A lithium ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, The positive electrode is a recycled lithium ion battery using the recycled positive electrode precursor of the first means. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a recycled positive electrode precursor that has a low content of conductors such as iron, copper, and aluminum, is able to prevent ignition, and can contribute to an increase in the recycling of used batteries in line with the increasing demand for lithium-ion batteries, as well as a recycled lithium-ion battery that uses the recycled positive electrode precursor.It is also possible to provide a method for producing a recycled positive electrode precursor that can produce a positive electrode precursor from black mass in a simple process. [Brief explanation of the drawings]

[0014] [Figure 1] 3 is a flowchart showing a manufacturing process for a recycled positive electrode precursor according to an embodiment of the present invention. [Figure 2] A diagram showing the process of crushing black mass using a jet mill. [Figure 3] A diagram showing the separation of various elements from black mass using a magnetic separator. [Figure 4] FIG. 1 shows charge / discharge curves for lithium ion batteries using the treated regenerated precursor of the present invention, virgin material, and untreated regenerated precursor. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described.

[0016] 1. Regenerated cathode precursor The recycled positive electrode precursor of the present invention is a powdered recycled positive electrode precursor mainly composed of manganese, with iron, copper, and aluminum contents each less than 0.5 mass %.

[0017] The reason why the material primarily contains manganese is that the black mass used as the raw material for recycled cathode precursors is mainly obtained from manganese-based lithium-ion batteries. By primarily containing manganese, the material can be easily recycled into cathode materials for manganese-based lithium-ion batteries or ternary lithium-ion batteries.

[0018] By keeping the iron, copper, and aluminum contents below 0.5% by mass, the amount of these conductive metals is reduced, reducing the risk of internal short circuits due to dendritic growth of electrode deposits and preventing fires in lithium-ion batteries recycled using the recycled positive electrode precursor. Because iron, copper, and aluminum are oxidized and become non-conductors during firing, the amounts of conductors such as iron, copper, and aluminum can be kept below 0.5% by mass.

[0019] The average particle size of the recycled positive electrode precursor is 0.01 μm to 50 μm, preferably 0.05 μm to 10 μm. By setting the average particle size to 50 μm or less, when the particles are conductors of iron, copper, or aluminum, it is possible to suppress the occurrence of internal short circuits, and when dispersing the recycled positive electrode precursor with a dispersant, no precipitation occurs, making dispersion easier. Furthermore, by setting the average particle size to 50 μm or less, it is possible to convert more particles into oxides in a shorter time.

[0020] The cobalt content of the recycled positive electrode precursor is preferably 31% to 85% by mass. The cobalt content can be recovered to a certain extent by magnetic separation of black mass, but can be adjusted to 31% to 85% by mass by adding a lithium compound such as lithium cobalt oxide. Since the cobalt content is 31% to 85% by mass, the recycled positive electrode precursor contains cobalt, an expensive rare metal, which increases its added value and allows it to be fully used as a recycled positive electrode material.

[0021] The nickel content in the recycled positive electrode precursor is preferably 31% to 85% by mass. As with cobalt, the nickel content is mostly recovered by magnetic separation of black mass, but can be adjusted to 31% to 85% by mass by adding nickel nitrate or the like. A nickel content of 1% to 30% by mass allows for sufficient use as a recycled positive electrode material.

[0022] The specific surface area of ​​the recycled positive electrode precursor is 10m 2 / g or more. 2 / g or more, the particle size is small, and when the particles are conductors of iron, copper, and aluminum, they are easily converted into non-conductors by firing treatment, which can suppress the occurrence of internal short circuits. In addition, when the recycled positive electrode precursor is dispersed with a dispersant, no precipitation occurs, making dispersion easier.

[0023] 2. Manufacturing method for recycled positive electrode precursor Next, a method for producing a recycled positive electrode precursor will be described.

[0024] As shown in Figure 1, if used lithium-ion batteries are available, the process begins with the production of black mass. If black mass recovered from used lithium-ion batteries is available from a recycler, the process begins with the production of a recycled positive electrode precursor from this black mass.

[0025] The target lithium-ion batteries are used lithium-ion batteries and defective lithium-ion batteries scrapped during the lithium-ion battery manufacturing process. There are no particular restrictions on the type, shape, or size of the lithium-ion batteries, but they can be cobalt-based lithium-ion batteries, manganese-based lithium-ion batteries, iron phosphate-based lithium-ion batteries, or ternary lithium-ion batteries. If possible, it is desirable to sort them by type before use.

[0026] [Black Mass Manufacturing Process] When used lithium-ion batteries are obtained, in step 101, the lithium-ion battery container, electrolyte, electrodes, and separator are removed, and the positive and negative electrode materials are extracted. The raw material for black mass production is preferably the positive electrode material alone, but from the perspective of reuse, the negative electrode material may also be used as raw material. The extracted positive electrode material can be used as is, but for ease of handling, it is recommended to crush it into appropriate sizes as needed.

[0027] The cathode material is pulverized in a jet mill to a particle size of 50 μm or less. In step 102, the raw material consisting of the cathode material is doped with carbon in an Ar (argon) or N2 (nitrogen) atmosphere and heat-treated at a temperature of 700°C or higher. The carbon addition is performed in an Ar atmosphere so that the carbon concentration can be adjusted. By adding carbon and performing calcination, the oxygen present in the cathode can be reduced, which can prevent fires from occurring during the recovery process.

[0028] By heat treating the cathode material, a black powder (black mass) containing cobalt, nickel, lithium, manganese, aluminum, etc. contained in the cathode material is obtained.

[0029] [Manufacturing process for recycled positive electrode precursor] In step 103, the black mass obtained through the black mass production process in steps 101 and 102, or obtained from a recycler, is pulverized using a jet mill, roll mill, or the like to a size of 50 μm or less, 0.01 μm to 50 μm, and preferably 0.05 μm to 10 μm. A jet mill is preferably used to prevent contamination. By pulverizing the black mass to 50 μm or less, internal short circuits can be prevented when the particles are conductors of iron, copper, or aluminum. Furthermore, precipitation does not occur when dispersing the recycled positive electrode precursor with a dispersant, facilitating dispersion.

[0030] As shown in Figure 2, jet mill 1 is a device in which black mass, the raw material, is fed into container 2 through raw material supply port 3, and the black mass granules are accelerated by a gas flow injected from gas supply port 4, causing them to collide with each other and pulverize, and the pulverized fine granules are classified and removed from upper discharge port 5. Roll mills feed the raw material black mass between rolls rotating in opposite directions, and the compression and shear forces of the rolls reduce the black mass granules to fine particles.

[0031] The black mass consisting of finely atomized particles is mixed with a dispersant in step 104 to form a dispersion liquid, which is then dispersed by stirring. The dispersant can be one or more selected from polymer dispersants (acid type, low acid value), low molecular weight surfactants, polymer surfactants, polymer anionic dispersants, and polymer polycarboxylic acid dispersants.

[0032] In step 105, the black mass dispersion is magnetically separated by a magnetic separator to recover magnetic materials such as cobalt, nickel, and their compounds from the black mass.

[0033] As shown in FIG. 3, the magnetic separator 10 has an electromagnet 12 disposed outside an outer pipe 11 and an inner pipe 13 inserted downstream of the electromagnet 12. A black bass dispersion introduced into the inlet 11a of the outer pipe 11 is divided into an outer flow that passes between the inner pipe 13 and the outer pipe 11 and an inner flow that flows inside the inner pipe 13. The black trout dispersion containing nickel, cobalt, and their compounds flows along the outer flow and is recovered from a recovery port 14 at the rear end of the outer pipe 11. The black trout dispersion containing non-magnetic materials such as aluminum and copper flows along the inner flow and flows out from an outlet 15 at the rear end of the inner pipe 13. Manganese in the black trout dispersion is a paramagnetic substance, but unlike ferromagnetic materials such as iron, nickel, and cobalt, it does not have a magnetic force strong enough to be separated, and therefore flows out from the outlet 15 along with the aluminum, copper, and other elements.

[0034] In step 106, the dispersion liquid containing nickel, cobalt, and their compounds flowing out of the recovery port 14 of the porcelain sorting device 10 is doped with carbon in an Ar (argon) or N2 (nitrogen) atmosphere and heat-treated at a temperature of 700°C or higher. The reason for adding carbon in an Ar atmosphere is that the carbon concentration can be adjusted by creating a low-oxygen atmosphere. By baking the positive electrode material with carbon added, the oxygen present in the positive electrode can be reduced, making it possible to prevent fires during the recovery process. The cobalt content is 31% to 85% by mass, the nickel content is 31% to 85% by mass, and the specific surface area of ​​the recycled positive electrode precursor is 10m2 / g or more.

[0035] 3. Recycled lithium-ion batteries Next, a regenerated lithium ion battery using the regenerated positive electrode precursor of the above embodiment will be described.

[0036] The recycled lithium-ion battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. The positive electrode is an aluminum positive electrode current collector coated with a positive electrode active material, and the recycled positive electrode precursor of the above embodiment is used as the positive electrode active material. The negative electrode, separator, and electrolyte are not particularly limited.

[0037] To prepare the regenerated positive electrode precursor, reagents containing lithium, nickel, manganese, and cobalt are added to achieve a composition equivalent to the desired regenerated positive electrode material for lithium-ion batteries, such as a ternary positive electrode material such as LiNi1 / 3Mn1 / 3Co1 / 3O2 (NMC111). Examples of lithium-containing reagents include lithium carbonate, lithium hydroxide, lithium nitrate, and lithium chloride. Examples of nickel-containing reagents include nickel nitrate hexahydrate, nickel acetate, and nickel hydroxide. Examples of manganese-containing reagents include manganese acetate tetrahydrate and manganese nitrate. Examples of cobalt-containing reagents include cobalt nitrate hexahydrate and cobalt acetate.

[0038] The recycled positive electrode precursor and each reagent are mixed and baked in an air atmosphere at 800°C for 4 hours to produce a baked product, which is then pulverized to produce the recycled positive electrode powder material.

[0039] The resulting recycled positive electrode powder material is applied to an aluminum current collector substrate to form a positive electrode. This positive electrode, negative electrode, and separator are stacked and housed in a case, and an electrolyte is injected to form a recycled lithium battery. There are no particular restrictions on the type, shape, or size of the recycled lithium battery. [Example]

[0040] The recycled cathode precursor derived from black mass prepared using the above method was analyzed by EDX (energy dispersive X-ray fluorescence spectroscopy). The analysis revealed that the total weight ratio of Co, Ni, Mn, and O was 76.3%. To adjust the composition to that of a ternary cathode material (LiNi1 / 3Mn1 / 3Co1 / 3O2 (NMC111)), reagents containing lithium, nickel, manganese, and cobalt were added to the recycled cathode precursor. The lithium reagent was lithium carbonate, with 27 g added at 5 mol% per 100 g of recycled cathode precursor. The nickel reagent was nickel nitrate hexahydrate, with 17.6 g added at 5 / 3 mol% per 100 g of recycled cathode precursor. The manganese reagent was manganese acetate tetrahydrate, with 14.9 g added at 5 / 3 mol% per 100 g of recycled cathode precursor. Cobalt nitrate hexahydrate was used as the cobalt reagent, and 17.6 g of it was added to 100 g of the regenerated positive electrode precursor at a 5 / 3 mol% ratio. The regenerated positive electrode precursor and the added reagent were mixed in a mortar and heated to 800 °C in an electric furnace over two hours. After maintaining the temperature at 800 °C for another two hours, the furnace was allowed to cool naturally to room temperature. The resulting powder was passed through a 75 μm stainless steel mesh to produce the black mass-derived positive electrode powder material of the invention. Meanwhile, commercially available LiNi1 / 3Mn1 / 3Co1 / 3O2 (NMC111) was used as the positive electrode powder material for the first comparative example (hereinafter referred to as "virgin material"). In the second comparative example, a regenerated positive electrode precursor without the missing lithium, nickel, manganese, and cobalt was used (hereinafter referred to as "untreated regenerated precursor").

[0041] 2.7g of the positive electrode powder material of the invention example was mixed with 6g of NMP (N-methyl-2-pyrrolidone, Mitsubishi Chemical Corporation), stirred for 120 seconds, 0.15g of conductive carbon (EC-600-JD, Lion Corporation) was added and stirred for 360 seconds, 3g of 5% PVDF solution (Zolbay Chemical) was added and stirred for 360 seconds, and then stirred for an additional 180 seconds and 360 seconds to prepare a positive electrode coating ink. Positive electrode coating inks were also prepared in the same manner for the positive electrode powder materials of the first and second comparative examples.

[0042] The positive electrode coating inks of the invention example and the first and second comparative examples were coated on an aluminum current collector substrate to a film thickness of 300 μm and dried at 800° C. for 8 hours to form positive electrodes. A flat cell was fabricated using Li metal as the negative electrode, a commercially available separator, and a standard carbonate-based electrolyte for lithium-ion batteries.

[0043] Charge-discharge tests were conducted on the flat cells of the invention example and the first and second comparative examples. The applied current was 0.1 C, and charge-discharge was performed with a lower limit of 2.7 Vm and an upper limit of 4.2 V. Figure 4 shows the charge-discharge curves of the lithium-ion batteries using the invention example, virgin material, and untreated recycled precursor. In each figure, the charge-discharge curves are shown from right to left for the initial cycle, 5, 10, 25, 50, and 100 cycles.

[0044] As a result, in the example of the present invention, as shown in FIG. 4(a), the initial cycle: 121 mAhg -1 After 50 cycles: 43mAhg -1 The open circuit voltage was about 3.8V. In contrast, in the first comparative example, as shown in FIG. 4(b), the initial cycle: 123 mAhg -1 After 50 cycles: 61mAhg -1 The open circuit voltage was about 3.8V. In the second comparative example, as shown in FIG. 4(c), the initial cycle: 24 mAhg -1 After 50 cycles: 2mAhg -1 The open circuit voltage was about 3.8V. Thus, it was found that the invention example, by adding the missing amounts of lithium, nickel, manganese, and cobalt to the untreated recycled precursor of the second comparative example, had battery performance comparable to that of the first comparative example, which used virgin material. [Explanation of symbols]

[0045] 1...Jet mill 2…Container 3...Raw material supply port 4...Gas supply port 5…Discharge port 10...Magnetic separator 11...Outer pipe 11a...Inlet 12...Electromagnet 13...Inner pipe 13 14...Collection port 15... Outlet

Claims

1. A recycled positive electrode precursor in the form of a powder, which is mainly composed of manganese, and has an iron, copper and aluminum content of less than 0.5 mass % each.

2. The recycled positive electrode precursor according to claim 1, wherein the average particle size of the recycled positive electrode precursor is 0.01 μm to 50 μm.

3. The recycled positive electrode precursor according to claim 1, wherein the content of cobalt in the recycled positive electrode precursor is 31% by mass to 85% by mass.

4. The recycled positive electrode precursor according to claim 1, wherein the content of nickel in the recycled positive electrode precursor is 31% by mass to 85% by mass.

5. The specific surface area of ​​the recycled positive electrode precursor is 10 m ２ 2. The regenerated positive electrode precursor of claim 1, wherein the Cr content is 1 / g or more.

6. a crushing step of crushing a fired product obtained by firing the cathode material recovered from used batteries into powder; a dispersing step of dispersing the powder with a dispersant to obtain a dispersion; a magnetic separation step of extracting cobalt, nickel, and compounds from the dispersion by magnetic separation; a calcination step of calcining the dispersion containing cobalt, nickel, and the compound; A method for producing a recycled positive electrode precursor comprising:

7. The method for producing a recycled positive electrode precursor according to claim 6 , wherein the pulverizing step uses a jet mill or a roll mill to produce a powder of 50 μm or less.

8. 7. The method for producing a recycled positive electrode precursor according to claim 6, wherein the magnetic separation step comprises flowing the powder as a liquid dispersion through a pipe, and separating the powder downstream of a magnet arranged outside the pipe into a flow containing magnetic materials consisting of cobalt, nickel, and compounds thereof and a flow containing non-magnetic materials, and separating the flow.

9. 7. The method for producing a recycled positive electrode precursor according to claim 6, wherein the firing step comprises heating the dispersion containing cobalt, nickel, and the compound to 700°C or higher in an argon or nitrogen atmosphere, adding C, and heating the mixture to obtain a powder containing cobalt, nickel, and the compound.

10. A lithium ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, A recycled lithium ion battery, wherein the positive electrode uses the recycled positive electrode precursor according to any one of claims 1 to 5.

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