Method for recycling waste lithium-ion battery

Abstract

The present invention relates to a method for recycling a waste lithium-ion battery and, more specifically, to a method for recycling a waste lithium-ion battery to be capable of more economically recovering lithium by increasing the recovery rate of non-magnetic metals, such as copper, which are treated as impurities, during the recovery of lithium from the waste battery.

Description

Waste Lithium-ion Battery Recycling Method

[0001] The present invention relates to a method for recycling spent lithium-ion batteries, and more specifically, to a method for recycling spent lithium-ion batteries that can recover lithium more economically by increasing the recovery rate of non-magnetic metals, such as copper, which are treated as impurities, during the process of recovering lithium from spent batteries.

[0002] Lithium-ion batteries have advantages such as high energy density, operating voltage, and a relatively small self-discharge rate compared to commercial water-based secondary batteries (Ni-Cd, Ni-MH, etc.), and are currently widely used in portable electronic communication devices, electric vehicles, and energy storage systems (ESS). In particular, when large capacity is required, such as in electric vehicles, they are installed and used in units of multiple battery cells, battery modules, and battery packs; as battery capacity and usage increase, the amount of discarded batteries also increases.

[0003] Accordingly, recovering rare metals such as lithium by recycling discarded lithium-ion batteries is emerging as a major issue.

[0004] The above-mentioned spent lithium-ion batteries are processed into a mixed powder form of cathode material, anode material, and other materials, known as Black Powder, through steps such as discharge, crushing, grinding / classification, and heat treatment.

[0005] The above black powder contains cathode material constituents such as nickel, cobalt, manganese, and lithium, anode material constituents such as graphite, and impurities such as aluminum or copper. The above black powder contains NCM alloy, lithium compound, graphite, copper, and aluminum, and each of these may be included in the black powder in an amount of approximately 7%.

[0006] In order to recover lithium elements from the above black powder, a magnetic separation process is performed, and the black powder subjected to magnetic separation can be separated into a non-magnetic lithium compound and a magnetic NCM alloy.

[0007] At this time, copper is a non-magnetic metal and is separated along with the lithium compound during the magnetic separation process; consequently, copper is present in the lithium compound.

[0008] As such, as the copper content in the lithium compound increases, the recovery rate of lithium, the final recovered material, may decrease; therefore, conventionally, the copper was removed by undergoing a wet smelting process on the lithium compound. However, as the copper content increases, a load may be placed on the wet smelting process, so methods are being sought to recover as much copper as possible from the lithium compound before undergoing the wet smelting process.

[0009] One aspect of the present invention for solving the aforementioned problem is to provide a method for recycling spent lithium-ion batteries that can recover metal particles, which are impurities, at a high recovery rate during the process of recovering lithium from spent lithium-ion batteries.

[0010] The technical problems intended to be solved in this document are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this invention belongs from the description below.

[0011] To achieve the above objective, a waste lithium-ion battery recycling method according to one embodiment of the present invention may include: a process of preparing a waste lithium-ion battery crushed material; a non-magnetic material separation process of magnetically separating the waste lithium-ion battery crushed material; a non-magnetic material treatment process of agglomerating metal particles among the non-magnetic materials and finely granulating non-metal particles; and a process of classifying and recovering the agglomerated metal particles.

[0012] In a method for recycling waste lithium-ion batteries according to one embodiment of the present invention, the metal particles may include Cu (copper).

[0013] In a method for recycling waste lithium-ion batteries according to one embodiment of the present invention, the assembled metal particles may include a plate-like structure.

[0014] In a method for recycling waste lithium-ion batteries according to one embodiment of the present invention, the plate-shaped structure may have an aspect ratio of 1:1 or more, a width of 1 to 20 mm, and a thickness of 0.1 to 5 mm.

[0015] A waste lithium-ion battery recycling method according to one embodiment of the present invention may include, in the non-magnetic material treatment process, a process in which a non-magnetic material is introduced within 30% of the total volume of a crushing container (Jar) and dry crushed for 5 minutes or more.

[0016] A waste lithium-ion battery recycling method according to one embodiment of the present invention may include the above-mentioned non-magnetic material treatment process, and a process of introducing a non-magnetic material within 20% of the total volume of a crushing container (Jar) and wet crushing for at least 3 minutes.

[0017] In a waste lithium-ion battery recycling method according to one embodiment of the present invention, the crushing process may input at least three times the amount of milling medium compared to the non-magnetic material.

[0018] In a waste lithium-ion battery recycling method according to one embodiment of the present invention, the recovery rate of the metal particles may be 80% or more.

[0019] The waste lithium-ion battery recycling method according to the present invention can reduce the load of the wet smelting process involved in recovering non-magnetic metal particles by recovering non-magnetic metal particles, including copper (Cu), which are treated as impurities, with a high recovery rate of 80% or more during the process of recovering lithium, a rare metal, from waste lithium-ion batteries. Accordingly, the amount of acid or alkali added to the wet smelting process can be reduced, thereby effectively reducing chemical costs while increasing the yield.

[0020] In addition, the waste lithium-ion battery recycling method according to the present invention recovers metal particles with a high recovery rate during the process of recovering lithium, thereby enabling the recovery of lithium, the final recovered material, with high purity.

[0021] Furthermore, according to the present invention, the non-magnetic metal particles are in a form in which lithium particles are fixed and distributed in a plate-like structure. Such plate-like metals can be utilized for purposes such as electromagnetic shielding and components, like industrial copper sources, and can maximize the added value of by-products generated during the recycling process.

[0022] The effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

[0023] FIG. 1 is a flowchart illustrating a method for recycling spent lithium-ion batteries according to one embodiment of the present invention.

[0024] Preferred embodiments of the present invention are described below. However, embodiments of the present invention may be modified in various other forms, and the technical concept of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more completely explain the present invention to those with average knowledge in the relevant technical field.

[0025] The terms used in this application are used merely to describe specific examples. For this reason, singular expressions include plural expressions unless the context clearly requires them to be singular. Additionally, it should be noted that terms such as “comprising” or “comprising” used in this application are used to clearly indicate the presence of features, steps, functions, components, or combinations thereof described in the specification, and are not used to preliminarily exclude the existence of other features, steps, functions, components, or combinations thereof.

[0026] Meanwhile, unless otherwise defined, all terms used in this specification shall be understood to have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Accordingly, unless explicitly defined in this specification, specific terms should not be interpreted in an overly ideal or formal sense. For instance, singular expressions in this specification include plural expressions unless the context clearly indicates an exception.

[0027] Additionally, terms such as "about," "substantially," etc., in this specification are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the said sense, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosed content in which precise or absolute values ​​are mentioned to aid in understanding the invention.

[0028] As explained above, spent lithium-ion batteries can typically be processed into a mixed powder of cathode materials, anode materials, and other materials called Black Powder through steps such as discharge, crushing, grinding / classification, and heat treatment, and lithium is recovered through magnetic separation and wet smelting of the Black Powder.

[0029] However, in the case of the aforementioned conventional method, non-magnetic metal particles, which are impurities, are not sufficiently recovered during the magnetic separation process, so wet smelting is carried out with a mixture of lithium compounds and a large amount of metal particles. In this process, an excessive amount of chemicals and time are required to separate lithium from the metal particles, which increases chemical costs while decreasing yield.

[0030] Accordingly, in the present invention, before wet smelting is performed after magnetic separation, a grinding and classification process is performed on the non-magnetic material separated through the magnetic separation process to recover non-magnetic metal particles containing copper at a high recovery rate.

[0031] The waste lithium-ion battery recycling method according to the present invention separates non-magnetic materials from crushed waste lithium-ion batteries, processes the separated non-magnetic materials, classifies them, and recovers metal particles. This is described in more detail with reference to FIG. 1 as follows.

[0032] FIG. 1 is a flowchart illustrating a method for recycling spent lithium-ion batteries according to one embodiment of the present invention.

[0033] Referring to FIG. 1, a recycling method for waste lithium-ion batteries according to one embodiment of the present invention is as follows: First, waste lithium-ion battery crushed material is prepared (S110).

[0034] As previously explained, the spent lithium-ion battery shredder is black powder formed by undergoing steps such as discharge, shredding, grinding / classification, and heat treatment of spent lithium-ion batteries.

[0035] Next, non-magnetic materials are separated (S120) by magnetic separation of the above-mentioned spent lithium-ion battery crushed material.

[0036] The above-mentioned crushed waste lithium-ion battery material may include magnetic materials such as NCM (nickel-cobalt-manganese)-based compounds, iron, and fastening parts, and non-magnetic materials such as lithium compounds, copper, aluminum, graphite, and plastic.

[0037] In the above magnetic separation process, the crushed waste lithium-ion battery material can be fed into a magnetic separator to separate magnetic materials such as nickel, cobalt, and iron.

[0038] One or more of a belt magnetic separator, a drum magnetic separator, or a high-intensity magnetic separator may be used as the above magnetic separator.

[0039] Through the magnetic separation described above, the crushed waste lithium-ion battery is separated into magnetic and non-magnetic materials. The waste lithium-ion battery recycling method according to the present invention is intended to separate non-magnetic metal particles during the process of recovering lithium compounds that are non-magnetic, and the treatment of the non-magnetic material is described.

[0040] When a non-magnetic material is separated (S120) by the magnetic separation above, the separated non-magnetic material is processed (S130) to separate metal particles and non-metal particles again, and in this non-magnetic material processing process (S130), dry milling and wet milling can be selectively performed on the non-magnetic material.

[0041] At this time, the dry grinding can be performed by introducing a non-magnetic material within 30% of the total volume of the grinding container (Jar), ​​preferably within 25%, and more preferably within 23%. The dry grinding time can be performed for 5 minutes or more, preferably 10 minutes or more, and more preferably 20 minutes or more.

[0042] The non-magnetic material subjected to the above dry grinding exhibits different effects depending on the characteristics of the material. Non-metallic particles, such as lithium compounds, are finely crushed and pulverized by impact, whereas metallic particles, such as copper, can clump together and become aggregated due to impact and relatively high ductility. At this time, the aggregated metallic particles can form a plate-like structure during the aggregation process.

[0043] In addition, the wet grinding can be performed by introducing a non-magnetic material within 30% of the total volume of the grinding container (Jar), ​​preferably within 20%, and more preferably within 17%. The wet grinding time can be performed for 3 minutes or more, preferably 7 minutes or more, and more preferably 10 minutes or more.

[0044] In the above dry grinding and / or wet grinding, the milling media for grinding may be added in an amount of at least 3 times the non-magnetic material to be ground, preferably at least 5 times, and more preferably at least 7 times.

[0045] As with the dry grinding above, the non-metallic particles that have undergone the wet grinding above can be formed into fine and uniform particles by being crushed and finely ground, and the metallic particles can be formed into a plate-like structure by being coarsely ground.

[0046] As described above, the non-magnetic material that has undergone the dry grinding and / or wet grinding exhibits different effects depending on the characteristics of the material. Non-metallic particles, such as lithium compounds, are finely crushed by impact and finely divided to an average particle size (D50) of 100 μm or less, whereas metal particles are aggregated together due to impact and high ductility characteristics, forming a plate-like structure with an average particle size (D50) of 400 μm or more.

[0047] The above-mentioned plate-shaped metal particles may have an aspect ratio of 1:1 or higher, preferably 1:1.2, and more preferably 1:1.5 or higher.

[0048] The above-mentioned plate-shaped metal particles may have a horizontal length of 1 to 20 mm, preferably 2 to 10 mm, and more preferably 2 to 8 mm.

[0049] In addition, the metal particles of the plate-like structure may have a thickness of 0.1 to 5 mm, preferably 0.1 to 3 mm, and more preferably 0.1 to 1 mm.

[0050]

[0051] Subsequently, after the above non-magnetic material processing process (S130) is completed, classification (S140) can be performed.

[0052] The above classification is a method of separating substances based on particle size, shape, or other physical or chemical properties, and one or more classification methods among sieve classification, air classification, gravity classification, centrifugal classification, electrostatic classification, density classification, or optical classification may be utilized.

[0053] The above sieve classification is a method of separating materials based on particle size using a sieve. In the present invention, a sieve with a hole size of 1.18 mm, i.e., a 16-mesh sieve, may be used, but the classification conditions of the present invention are not necessarily limited to this and can be appropriately applied according to various other classification environments.

[0054] The above air classification is a method of separating particles according to size, density, or shape using airflow, and in the present invention, a cyclone classifier, a precision air classifier, or an inertial air classifier may be used.

[0055] In addition, gravity classification, centrifugal classification, electroclassification, density classification, or optical classification methods may be applied.

[0056] Through the above classification, metal particles can be separated from a non-magnetic material, wherein the aggregated metal particles among the metal particles can be separated through sieve classification, and the metal particles in the form of fine particles that are not aggregated can be separated through air classification.

[0057] After the above classification is completed, the lithium compound and metal particles in the form of fine particles and the plate-like metal particles can be separated, respectively.

[0058] The plate-shaped metal particles separated in this way are recovered (S150), and the lithium compound and metal particles in the form of fine particles undergo a hydrometallurgy process, thereby allowing the lithium, which is the target material for waste battery recycling, to be recovered in the form of compounds such as lithium carbonate (Li2CO3), lithium hydroxide (LiOH), or lithium chloride (LiCl).

[0059] At this time, the recovery rate of the plate-shaped metal particles may be 80% or more, preferably 85% or more, and more preferably 90% or more. This indicates a much higher metal recovery rate compared to the conventional metal recovery rate of 30%.

[0060] That is, the waste lithium-ion battery recycling method according to one embodiment of the present invention can separate non-magnetic metal particles, such as copper, which are treated as impurities during the process of recovering lithium, the final target material, with a higher recovery rate than conventional methods.

[0061] In addition, in the wet smelting process performed to separate the above-mentioned non-magnetic metal particles, the lithium compound can be finally recovered by utilizing the difference in characteristics between the lithium compound, which dissolves easily in acid or alkali solutions, and the metal particles, which have a relatively low dissolution rate.

[0062] The above wet smelting process can recover lithium in the form of a compound by introducing a lithium compound in the form of fine particles and metal particles into an acidic solution such as sulfuric acid (H2SO4) or hydrochloric acid (HCl) or an alkaline solution such as sodium hydroxide (NaOH), and precipitating only the lithium dissolved in the solution.

[0063] As described above, the waste lithium-ion battery recycling method according to one embodiment of the present invention recovers more than 80% of metal particles and reduces the content of metal particles in the material fed into the wet smelting process to about 15% to 20%, thereby reducing the load of the wet smelting process and reducing the amount of acid or alkali solution fed to dissolve the lithium compound. Accordingly, the process yield is increased, and chemical costs are effectively reduced, allowing for more economical recycling of waste lithium-ion batteries.

[0064] The present invention will be explained in more detail below through the following examples. However, the following examples are merely illustrative of the present invention, and the scope of the present invention is not limited thereto.

[0065] Examples

[0066] Example 1

[0067] The black powder formed through a reduction process was magnetically separated using a wet magnetic separator, and the non-magnetic material separated through magnetic separation was fed into a dry grinding device rod mill at a volume of 20% of the total volume of the grinding container (Jar) and then dry ground for 10 minutes. The fine lithium compound particles and plate-shaped metal particles obtained through the grinding were classified using a 16-mesh sieve, and the plate-shaped metal particles were recovered. Wet smelting was then performed on the fine particles using sulfuric acid until all the lithium compounds were dissolved.

[0068] Example 2

[0069] Plate-shaped metal particles were recovered in the same manner as in Example 1 above, except that dry grinding was performed for 15 minutes, and wet smelting was performed on the fine particles.

[0070] Example 3

[0071] Plate-shaped metal particles were recovered in the same manner as in Example 1, except that dry grinding was performed for 20 minutes, and wet smelting was performed on the fine particles.

[0072] Comparative Example 1

[0073] The black powder formed through the reduction process was magnetically separated using a wet magnetic separator, and wet smelting was performed without crushing the non-magnetic material separated through magnetic separation.

[0074] Comparative Example 2

[0075] Plate-shaped metal particles were recovered in the same manner as in Example 1, except that dry grinding was performed for 2 minutes after being introduced at a volume condition of 5% of the total volume of the grinding container (Jar). Wet smelting of fine particles was then performed.

[0076] Classification Lithium Compound Fine Particles Particle Size (㎛) Plate-shaped Metal Particle Size (㎛) Plate-shaped Metal Recovery Rate (%) Type of Wet Smelting Chemical Wet Smelting Process Time (min) Amount of Wet Smelting Chemical Input (mol) Final Non-magnetic Metal Recovery Rate (%) Comparative Example 1 --- Sulfuric Acid 310 1.330% Comparative Example 2 --- Sulfuric Acid 277 1.141% Example 1 641 1409 0.2% Sulfuric Acid 116 0.19 1.4% Example 2 611 1968 9.6% Sulfuric Acid 127 0.19 0.8% Example 3 441 4409 0.3% Sulfuric Acid 141 0.19 2.2%

[0077] As confirmed by Table 1 above, in Examples 1 to 3, in which dry grinding of non-magnetic materials separated by magnetic separation was performed for 5 minutes or more, it can be seen that through dry grinding, the particle size of the lithium compound fine particles is 100 μm or less, and the particle size of the plate-shaped metal is 400 μm or more. As a result of sieve classification of the fine particles and plate-shaped metal, it can be confirmed that the aggregated plate-shaped metal is recovered at a rate of 89% or more. Thus, as the non-magnetic metal is recovered in a plate-shaped structure with a high recovery rate, the non-magnetic metal is contained in a very low content in the material fed into the wet smelting process, so the wet smelting process is performed for 116 to 141 minutes with a small amount of chemical added of about 0.1 mol, and it can be confirmed that the final non-magnetic metal recovery rate is 90% or more.

[0078] On the other hand, in Comparative Example 1, in which no grinding was performed, and Comparative Example 2, in which dry grinding of less than 5 minutes was performed, lithium compound fine particles and plate-shaped metal were not properly formed, making it difficult to recover the plate-shaped metal. It can be confirmed that in the wet smelting process for non-magnetic materials, a total of 1.1 mol of sulfuric acid was used and the process was carried out for more than 270 minutes. As such, despite the relatively large amount of chemicals added and the long time consumed in the wet smelting process, the final non-magnetic metal recovery rates of Comparative Example 1 and Comparative Example 2 were 30% and 41%, respectively, indicating a significant decrease in metal recovery rate compared to the above example.

[0079] Although embodiments of the invention disclosed above have been illustrated and described, the disclosed invention is not limited to the specific embodiments described above, and various modifications may be made by those skilled in the art to which the disclosed invention belongs without departing from the essence claimed in the claims.

Claims

1. Process for preparing crushed spent lithium-ion batteries; A non-magnetic material separation process for separating non-magnetic materials by magnetic separation of crushed spent lithium-ion batteries; A non-magnetic material processing process in which metal particles among the above non-magnetic materials are aggregated and non-metal particles are finely granulated; and A process for classifying and recovering the above-mentioned assembled metal particles; A method for recycling spent lithium-ion batteries including 2. In Paragraph 1, The above metal particles are, A method for recycling waste lithium-ion batteries containing Cu (copper).

3. In Paragraph 1, The above-mentioned assembled metal particles are, A method for recycling waste lithium-ion batteries including a plate-like structure.

4. In Paragraph 3, The above plate-shaped structure is, A method for recycling waste lithium-ion batteries having an aspect ratio of 1:1 or greater, a width of 1 to 20 mm, and a thickness of 0.1 to 5 mm.

5. In Paragraph 1, The above non-magnetic material treatment process is, A method for recycling spent lithium-ion batteries, comprising: a process of introducing a non-magnetic material within 30% of the total volume of a crushing container (Jar) and dry crushing for 5 minutes or more.

6. In Paragraph 1, The above non-magnetic material processing process, A method for recycling spent lithium-ion batteries, comprising: a process of introducing a non-magnetic material within 20% of the total volume of a crushing container (Jar) and wet crushing for 7 minutes or more.

7. In either Paragraph 5 or Paragraph 6, The above grinding process is, A method for recycling spent lithium-ion batteries, wherein the milling medium is input at least three times the amount of the non-magnetic material.

8. In Paragraph 1, The recovery rate of the above metal particles is, A method for recycling spent lithium-ion batteries with a recycling rate of over 80%.

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