Method for recovering valuable materials from lithium-ion secondary battery

Abstract

To provide a method for recovering valuable materials from a lithium-ion secondary battery, where the recovery rate for copper can be improved.SOLUTION: A method for recovering valuable materials from a lithium-ion secondary battery comprises a heating step for heating a lithium-ion secondary battery, a crushing step for crushing after the heating, and any one or more steps for sieving, magnetic sorting and gravity sorting after the crushing. In the crushing step, the crushing is performed such that the size of crushed materials is 20 mm or less.SELECTED DRAWING: Figure 3

Description

Technical field

[0001] The present invention relates to a method for recovering valuable materials from a lithium ion secondary battery. [Background technology]

[0002] Lithium ion secondary batteries have traditionally been used as batteries for small mobile devices such as mobile phones, notebook computers, and video cameras. In recent years, electric vehicles have become popular as part of decarbonization efforts, and large lithium-ion secondary batteries for automotive use are being produced in large quantities. In addition, in recent years, in order to improve safety and volumetric energy density, research has been actively conducted on the development of new materials constituting negative and positive electrodes and on solid electrolytes.

[0003] Generally, a lithium ion secondary battery is composed of a positive electrode, a negative electrode, a separator, an electrolyte, and the like. The positive electrode used is an aluminum foil (positive electrode current collector) coated with an active material such as lithium, cobalt, or nickel together with a binder. The negative electrode used is a copper foil (negative electrode current collector) coated with an active material such as graphite along with a binder. These are housed in a metal exterior material.

[0004] Lithium-ion secondary batteries contain valuable materials such as lithium, cobalt, nickel, copper, and aluminum, so after they are used after repeated charging and discharging, valuable materials are collected from them. ing. Regarding the recovery method, for example, Patent Document 1 describes a method for easily and efficiently recovering valuable materials such as copper and aluminum from lithium ion secondary batteries. Additionally, Patent Documents 2 and 3 disclose methods for separating and recovering copper, aluminum, and active materials from used lithium ion batteries. [Prior art documents] [Patent document]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2015-170480 [Patent Document 2] Japanese Patent Application Publication No. 2017-174517 [Patent Document 3] Japanese Patent Application Publication No. 2018-120716 [Summary of the invention] [Problem to be solved by the invention]

[0006] Generally, when recovering valuables from a lithium ion secondary battery, the battery is first discharged until the battery voltage drops below a certain level, and then the separator, electrolyte, etc. are decomposed and removed by heating. Next, the metals contained in the exterior material, current collector, active material (hereinafter also referred to as electrode material powder), etc. are separated by sieving, specific gravity sorting, magnetic separation, etc. after being crushed while still contained in the exterior material. do. Through such a process, copper, aluminum, iron, electrode material powder (lithium, nickel, cobalt, manganese, titanium, rare metals such as niobium, graphite, silicon), etc. can be separated. Since the quality of rare metals contained in electrode material powder is likely to decline in the future, recovery of copper, aluminum, and iron is extremely important in recycling lithium-ion secondary batteries.

[0007] However, when the exterior material of a lithium-ion secondary battery is crushed, the copper foil that makes up the current collector gets stuck to the ferrous metal (steel, stainless steel, etc.) or aluminum lump that makes up the exterior material, as shown in Figure 1. In addition, as shown in Figure 2, copper lumps such as sealing bolts and conductive busbars attached to the exterior material cannot be separated from the exterior material, resulting in a significant reduction in the recovery rate of valuable copper. The problem arose of a decline. In addition, copper trapped in ferrous metals can be recycled into iron. A problem arose in that it also inhibited Kuru.

[0008] The present invention has been made in view of these circumstances, and its purpose is to improve the recovery rate of copper in a method for recovering valuables from lithium ion secondary batteries. An object of the present invention is to provide a method for recovering valuable materials from lithium ion secondary batteries. [Means to solve the problem]

[0009] In order to solve the above problems, the present invention provides the following aspects. [1] Lithium ion secondary batteries are processed through a heating process to heat them, a crushing process to crush them after heating, and one or more of sieving, magnetic sorting, and specific gravity sorting after crushing. 1. A method for recovering valuable materials from a lithium ion secondary battery, the method comprising: crushing the crushed materials to a size of 20 mm or less in the crushing step. [2] The method for recovering valuables from a lithium ion secondary battery as described in [1] above, characterized in that in the crushing step, a shearing type crusher is used. [3] The method for recovering valuables from a lithium ion secondary battery according to [1] or [2] above, characterized in that in the crushing step, a shearing type crusher capable of particle size adjustment is used. [4] The method for recovering valuables from a lithium ion secondary battery according to [1] or [2] above, characterized in that in the crushing step, a three- or four-shaft shear type crusher is used. [5] The method for recovering valuables from a lithium ion secondary battery according to [1] above, wherein the crushing step includes two or more consecutive crushing steps. [6] After the above-mentioned crushing step, there is a step of sieving to separate the pole material powder which is the product under the sieve, and a step where the product on the sieve separated by the sieving is magnetically sorted, and the ferrous metal which is the magnetic material is a step of separating heavy products and light products by gravity sorting the non-magnetic materials separated by the magnetic sorting, and a step of magnetically sorting and / or gravity sorting the heavy products separated by the gravity sorting. a step of separating copper lumps and aluminum lumps, a step of crushing the light products separated by the specific gravity sorting, and a step of sieving the crushed material obtained by the crushing to remove the sieved product, which is a a step of separating the wood flour, a step of gravity sorting the sieved products separated by the sieving to separate heavy products and light products, and a step of magnetically sorting the light products separated by the gravity sorting, The method for recovering valuables from a lithium ion secondary battery as described in [1] above, comprising the step of separating copper foil, which is a non-magnetic material, and aluminum foil, which is a magnetic material. [7] The method for recovering valuables from a lithium ion secondary battery according to [1] or [6] above, wherein the specific gravity sorting uses wind sorting or an air table.

Effect of the invention

[0010] According to the present invention, in a method of recovering valuable materials from a lithium ion secondary battery, it has an excellent effect of improving the recovery rate of copper. Furthermore, since the recovery rate of copper is improved, the amount of copper entrapped in the iron is reduced, and as a result, the quality of the recovered iron is improved. [Brief explanation of drawings]

[0011]

Figure 1

Figure 2

[0012] The present invention will be explained in detail below. The explanation of the constituent elements described below is an example (representative example) of the embodiment of the present invention, and the present invention is not limited by these contents. However, it can be implemented with various modifications within the scope of its gist.

[0013] A lithium ion secondary battery usually consists of a positive electrode, a negative electrode, an electrolyte, a separator, and the like. The lithium ions move in the electrolyte between the positive and negative electrodes, thereby functioning as a battery. Usually, in a positive electrode, a positive electrode material such as lithium, nickel, cobalt, manganese, etc. is coated on an aluminum foil, which is a current collector, along with a binder. On the other hand, in the negative electrode, a negative electrode material such as graphite or silicon is coated on a copper foil as a current collector. Further, titanium, niobium, etc. may be used as the negative electrode material. The positive electrode, negative electrode, electrolyte, separator, etc. are housed in an exterior material made of iron-based metal or aluminum to form a single battery cell. Copper sealing bolts and conductive busbars are attached to the exterior material.

[0014] Lithium-ion secondary batteries for use in vehicles such as electric vehicles have prismatic, cylindrical, and laminated battery cells.Multiple battery cells are assembled to form a battery module; , constitutes a battery pack. Generally, small, rectangular battery cells are used in mobile phones, notebook computers, video cameras, and the like. When valuables are recovered from lithium ion secondary batteries, they are processed without particularly distinguishing between battery cells, battery modules, and battery packs.

[0015] When recovering valuables from lithium-ion secondary batteries, heating is typically used to decompose and remove organic materials such as separators and electrolytes inside. After heating, the exterior material is crushed together, the current collector (copper foil, aluminum foil, etc.) inside it is finely crushed (cut), and the electrode material powder adhering to the current collector is peeled off. After crushing, by appropriately combining sieving, magnetic sorting, and specific gravity sorting, ferrous metals, copper lumps, and aluminum lumps that make up exterior materials, copper foil and aluminum foil that make up current collectors, and poles are separated. Lithium, nickel, cobalt, manganese, graphite, titanium, niobium, silicon, etc. that make up the wood powder are separated and recovered.

[0016] Hereinafter, a method for collecting valuables according to an embodiment of the present invention will be described in detail. [Heating process] In the heating step, the temperature and atmosphere during heating are not particularly limited as long as at least the separator, electrolyte, and other organic substances contained in the lithium ion secondary battery can be burned and removed. For example, the heating temperature can be in the range of 400°C or higher and 600°C or lower. Further, heating can be performed in an oxidizing atmosphere or a non-oxidizing atmosphere. The heating time can be adjusted as appropriate depending on the shape and size of the lithium ion secondary battery, the amount of the object to be heated, etc., and can be, for example, 0.5 to 6 hours. It is possible to heat battery cells, battery modules, battery packs, etc. without any particular distinction.

[0017] Furthermore, before the heating step, the lithium ion secondary battery can be discharged to bring the remaining battery power below a certain level. This is to prevent accidents due to explosions, fires, and electric shocks in subsequent processes. However, since the heating step described above can almost eliminate the battery's function, discharging is an optional step.

[0018] [Crushing process] The heated lithium ion secondary battery is crushed together with its exterior material, the current collector is taken out from inside and crushed, and the electrode material powder adhering to the current collector is separated. At this time, if the exterior material is crushed together, the copper foil of the current collector will be caught up in the scraps of the iron-based metal or aluminum lump that constitutes the exterior material and crushed (caught). Once entrapped, it becomes extremely difficult to separate the copper foil through subsequent sorting steps. In addition, during crushing, copper lumps such as sealing bolts and conductive busbars attached to the exterior material become entangled with iron-based metals and aluminum lumps, making it impossible to separate the copper lumps from the exterior material. , the subsequent sorting process makes it extremely difficult to separate the copper lumps. Therefore, the crushing process uses as much copper as possible. It is important to separate them without getting stuck.

[0019] In the crushing process, the particle size is adjusted and crushed so that the size of the crushed pieces is 20 mm or less. By adjusting the size of the crushed material within the above range, the encroachment of the copper foil and copper lumps described above can be significantly reduced, and the recovery rate of copper can be increased. Preferably, the size of the crushed material is 15 mm or less. Moreover, the size of the crushed material is more preferably 1 mm or more.

[0020] When crushing is performed using a shear type crusher for particle size adjustment, a screen with openings is installed under the crushing blades, and the crushed material is circulated until it reaches a size that can pass through the openings. At this time, it is important to set the opening of the screen to about 20 mm or 15 mm and to repeat crushing until the crushed pieces pass through the openings of the screen to make the size of the crushed pieces uniform. Thereby, it is possible to suppress the copper foil from being caught in the iron-based metal or aluminum lump, and it is also possible to separate the copper lump into individual pieces. Furthermore, the separation efficiency in the subsequent sorting process can be improved. In particular, by aligning the size of the crushed materials, subsequent wind sorting and gravity sorting using an air table will work more effectively.

[0021] In the case of a crusher without a screen, crushing is performed only once, so the size of the crushed products is uneven, making it difficult to separate copper into individual pieces. Therefore, it is preferable to use a crusher equipped with a mechanism for adjusting particle size, such as a screen. In addition, there are impact type crushers other than shear type crushers, but when using an impact type crusher, the exterior material is crushed and the copper lumps cannot be separated individually, and the copper foil is rather , chewing increases. Therefore, in the crushing step, it is preferable to use a shear type crusher.

[0022] In the case of a crusher with a screen, crushed materials that do not pass through the openings of the screen are circulated through the crusher and repeatedly crushed. At this time, the crushed material remains in the gap between the shafts of the crusher, but the rotation of the shaft causes the electrode material powder adhering to the current collector to be peeled off, thereby increasing the separation efficiency. In order to increase separation efficiency, it is more preferable to use a three-shaft crusher or a four-shaft crusher. In addition, the crushing process can be carried out multiple times, such as primary crushing and secondary crushing, by installing shear type crushers in succession or by replacing the screen and gradually narrowing the screen opening. It is valid.

[0023] [Sifting] In an embodiment of the present invention, sieving is performed as necessary after crushing. The purpose of the sieving is not particularly limited; for example, the purpose of the sieving may be to separate the electrode material powder adhering to the current collector. Alternatively, the purpose may be to obtain crushed material of an optimal size for subsequent specific gravity sorting or magnetic force sorting.

[0024] The opening of the sieve can be set as appropriate depending on the purpose. For example, when separating polar wood powder, the opening can be set to 1 mm or more and 10 mm or less, thereby separating the polar wood powder as a product under the sieve and transferring the product on the sieve to the subsequent sorting process. be able to.

[0025] [Magnetic sorting] In an embodiment of the present invention, magnetic sorting is performed as necessary after crushing. The purpose of the magnetic separation is not particularly limited, and for example, the purpose of the magnetic separation may be to separate the ferrous metal constituting the exterior material as a magnetic substance. Alternatively, it is possible to separate the aluminum foil as a magnetic material and the copper foil as a non-magnetic material.

[0026] The magnetic force used for magnetic force sorting can be appropriately set depending on the purpose. For example, when separating iron-based metals, a magnet with a surface magnetic flux density of 0.3 Tesla or less can be used. In addition, when separating aluminum foil as a magnetic material and copper foil as a non-magnetic material, the surface A magnet with a magnetic flux density of 0.8 Tesla or more can be used.

[0027] [Specific gravity sorting] In an embodiment of the present invention, specific gravity sorting is performed as necessary after crushing. The purpose of specific gravity sorting is not particularly limited; for example, lumps such as exterior materials, bolts, bus bars, etc. can be treated as heavy products, and foil-like materials of current collectors can be separated as light products.

[0028] The method and conditions for specific gravity selection can be set as appropriate depending on the purpose. For example, it can be carried out using an air table, a wind sorter, a fluidized bed sorter, a heavy liquid sorter, or the like. The air table, as described in Patent Document 1, uses airflow and vibration to sort objects. By performing this sorting, the copper lumps can be separated.

[0029] After crushing, various valuable materials can be separated and recovered by combining sieving, magnetic separation, and specific gravity separation as described above. There is no particular restriction on the order or number of times of sieving, magnetic separation, specific gravity separation, etc., and can be appropriately selected depending on the object. For example, after specific gravity sorting, the specific gravity sorting method and conditions can be changed and specific gravity sorting can be performed again. Alternatively, after separating the magnetic objects by magnetic separation, specific gravity separation may be performed, and then magnetic separation may be performed again to separate the magnetic objects.

[0030] Moreover, after sieving, magnetic separation, and specific gravity separation, crushing can be performed again as necessary. What is important in this disclosure is that during crushing before sorting, the size of the crushed pieces is aligned within a certain range to reduce the amount of copper foil caught in iron-based metals and aluminum blocks, and It is to separate the single unit. Therefore, after reducing the amount of clumping and sorting, crushing and sieving can be performed again as necessary.

[0031] Copper foil stuck in iron-based metal or aluminum lumps can be separated by color sorting as in Patent Documents 1 and 3, but by crushing, copper foil stuck in iron-based metal or aluminum lumps can be separated. It is extremely difficult to separate them because they are crushed in a stacked state. In this embodiment, since the crushing process is devised to suppress the copper foil from getting stuck, there is usually no need to perform color sorting.

[0032] [Collected items] By going through the above process, the iron-based metals, copper lumps, aluminum lumps that make up the exterior material, copper foil and aluminum foil that make up the current collector, lithium, nickel, cobalt, manganese that are the electrode material powder, etc. Graphite, silicon, titanium, niobium, silicon, etc. can be separated. Note that in order to improve the performance of lithium ion secondary batteries, electrode materials such as active materials may be changed in the future. In the present disclosure, it is sufficient that the valuables to be recovered contain at least copper.

Example

[0033] The following will explain based on examples. Note that the embodiment is just an example, and the invention is not limited in any way by this example. That is, the present invention is limited only by the scope of the claims, and includes various modifications other than the embodiments included in the present invention.

[0034] (Example 1) Valuable materials were collected from lithium-ion secondary batteries according to the flow shown in Figure 3. First, a vehicle battery module, which is a lithium ion secondary battery, was subjected to heat treatment for 4 hours using a hot air heating furnace capable of generating hot air at 400°C to 600°C. Thereafter, the heat-treated battery module was subjected to primary crushing using a four-axis shearing crusher so that the size of the crushed pieces was 40 mm or less. Next, the fractures obtained by primary crushing The material was subjected to secondary crushing using a four-shaft shear crusher to a size of 15 mm or less. Next, the obtained crushed material was passed through a primary sieve with an opening of 1.0 mm to separate the product under the sieve (pole material powder).

[0035] From the sieved product obtained by the primary sieve, which exceeds 1.0 mm, ferrous metals, which are the crushed exterior material, which is a magnetized component, were removed using hanging magnetic separation equipment with a magnetic flux density of 0.03 Tesla. . Non-magnetic materials were sorted into heavy and light products using wind sorting.

[0036] The ferrous metals, which are magnetized components, were removed from the heavy products obtained in the previous wind sorting process using drum-type magnetic sorting equipment with a magnetic flux density of 0.15 Tesla. On the other hand, non-magnetized materials were sorted into copper lumps and aluminum lumps using an air table.

[0037] The light products obtained in the previous wind sorting were subjected to tertiary crushing using a uniaxial shear type crushing device. The obtained crushed material was passed through a secondary sieve with an opening of 1.0 mm to separate the product under the sieve (polar material powder). The sieved products separated by the sieve and having a size exceeding 1.0 mm were subjected to specific gravity sorting to remove heavy products such as copper lumps and aluminum lumps. The obtained light products were used to remove iron-based metals, which are magnetic components, using drum-type magnetic separation equipment with a magnetic flux density of 0.15 Tesla. For non-magnetic materials, copper foil and aluminum foil were separated using ultra-high magnetic separation equipment with a magnetic flux density of 1 Tesla or more.

[0038] (Example 2) Valuable materials were recovered from the lithium ion secondary battery under the same conditions as in Example 1, except that the size of the crushed material by primary crushing was 25 mm or less.

[0039] (Comparative example 1) Valuables were recovered from the lithium ion secondary battery under the same conditions as in Example 1, except that secondary crushing was not performed.

[0040] Table 1 shows the recovery rates and quality of copper lumps and copper foil, with respect to the amount of copper in the battery module (lithium ion secondary battery) placed in the heating furnace. In addition, various recovery rates and grades were calculated from the following formulas. Recovery rate of copper lumps (%) = Weight of recovered copper lumps / Weight of copper in secondary battery x 100 Copper foil recovery rate (%) = Weight of recovered copper foil / Weight of copper in secondary battery x 100 Total recovery rate of copper (%) = (Weight of recovered copper lumps + weight of copper foil) / Weight of copper in secondary battery x 100 Quality of copper ingots (%) = Weight of copper ingots / (weight of air table heavy products) x 100 Quality of copper foil (%) = Weight of copper foil / (Magnetic sorting (ultra high) non-magnetic material weight) × 100

[0041]

table 1

[0042] In Example 1, the recovery rate as a copper lump was 34% and the quality was 91%, and the recovery rate as a copper foil was 28% and the quality was 87%, and the copper lump and copper foil were combined. The copper recovery rate was 62%. In Example 2, the recovery rate as a copper lump was 35%, the quality was 84%, and the recovery rate as a copper foil was 35%. The recovery rate was 34%, the quality was 94%, and the copper recovery rate for the copper lump and copper foil was 69%. In Comparative Example 1, the recovery rate as a copper lump is 0%, the recovery rate as a copper foil is 20%, and the quality is 80%, and the copper recovery rate for the copper lump and copper foil is It was 20%. From the above results, it can be seen that in Examples 1 and 2, the copper recovery rate was improved by about 40 to 50% compared to Comparative Example 1. As mentioned above, by adjusting the particle size and crushing so that the size of the crushed material is 20 mm or less, the separation of sealing bolts and conductive bus bars into individual units is promoted, and the recovery rate of copper lumps is improved. In addition, the copper foil is less likely to be caught in the exterior material, and the recovery rate of the copper foil is significantly improved. [Industrial applicability]

[0043] According to the present invention, in a method for recovering valuable materials from lithium ion secondary batteries, it is possible to improve the recovery rate of copper, reduce copper in iron-based metals, and improve the quality thereof. Has excellent effects. It can be suitably used as a method for recovering valuables from automotive lithium-ion secondary batteries, which is expected to expand in the market in the future.

Claims

1. A method for recovering valuable materials including copper from lithium ion secondary batteries which use iron-based metals and / or aluminum as exterior materials, comprising crushing the lithium ion secondary batteries so that the maximum size of the crushed pieces is 20 mm or less, and after crushing, carrying out the following steps (1) to (3) in any order or number of times. (1) A step of sieving to separate the oversized product from the undersized product (2) A process of separating magnetic materials from non-magnetic materials by magnetic sorting. (3) Gravity separation to separate heavy and light products

2. 2. The method for recovering valuable materials from lithium ion secondary batteries according to claim 1, wherein a shearing type crusher capable of adjusting particle size is used in the crushing step.

3. 2. The method for recovering valuable materials from lithium ion secondary batteries according to claim 1, wherein a three-axis or four-axis shearing crusher is used in the crushing step.

4. 2. The method for recovering valuable materials from a lithium ion secondary battery according to claim 1, wherein the crushing step includes two or more consecutive crushing steps.

5. 2. The method for recovering valuable materials from lithium ion secondary batteries according to claim 1, wherein the gravity separation is performed using wind separation or an air table.

6. A method for recovering valuables from a lithium ion secondary battery as described in claim 1, comprising a heating step of heating the lithium ion secondary battery before crushing.

7. A method for recovering valuable materials from a lithium-ion secondary battery as described in claim 1, comprising the steps of crushing light products separated by gravity separation, and sieving the crushed material obtained by the crushing to separate the under-sieve product, which is electrode material powder.

8. A method for recovering valuable materials from a lithium-ion secondary battery as described in claim 1, comprising a step of magnetically separating the sieve product separated by sieving to separate the magnetically attached iron-based metals.

9. A method for recovering valuable materials from a lithium-ion secondary battery as described in claim 8, comprising the steps of: gravity separating the non-magnetic materials separated by the magnetic separation to separate heavy products from light products; and magnetically separating and / or gravity separating the heavy products to separate copper lump-like materials from aluminum lumps.

10. A method for recovering valuable materials from a lithium-ion secondary battery as described in claim 9, comprising the steps of crushing the light products separated by the specific gravity separation, and sieving the crushed material obtained by the crushing to separate the under-sieve product, which is electrode material powder.

11. A method for recovering valuables from a lithium-ion secondary battery as described in claim 10, comprising the steps of: gravity separating the on-screen products separated by the sieving to separate them into heavy products and light products; and magnetically separating the light products separated by the gravity separating to separate the copper foil which is a non-magnetic material and the aluminum foil which is a magnetic material.

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