Method for recycling lithium-ion secondary battery

Abstract

In a valuable metal reactant according to an embodiment of the present invention, comprising a first valuable metal-containing material, a second valuable metal-containing material, and carbon, which have been recovered from a waste battery, the first valuable metal-containing material includes a Ni-Co alloy and a manganese-based oxide, and in an X-ray diffraction analysis, a (111) peak of the Ni-Co alloy has a position of 44.3° to 44.6°, a MnO (200) peak of the manganese-based oxide has a position of greater than 44.7° and less than 44.9°, and the second valuable metal-containing material includes a non-magnetic material.

Description

Lithium-ion secondary battery recycling method

[0001] The present invention relates to a method for recycling waste lithium-ion secondary batteries, and specifically, to a method for recovering Ni and Co, excluding Mn, by heat-treating waste lithium-ion secondary batteries in a high-temperature reducing atmosphere.

[0002] With the recent emergence of global warming as a major issue, the demand for and adoption of electric vehicles (EVs) for carbon reduction are increasing. Due to this explosive growth in EV usage, a large volume of discarded EVs will be generated in the near future. These scrapped EVs contain valuable metallic elements such as nickel, cobalt, manganese, and lithium.

[0003] These valuable metals are concentrated in specific countries, causing supply chain instability, and their production processes can lead to severe environmental pollution; consequently, many nations are mandating the recycling of spent batteries. Therefore, developing technologies and systems to efficiently recover and recycle valuable metals from spent batteries has become a critical task. This can reduce resource waste and increase economic value while making a significant contribution to environmental protection.

[0004] For the recycling of secondary batteries, the batteries are processed through crushing, grinding, gravity separation, and magnetic separation to produce black powder, which is a mixture of cathode and anode materials. This black powder contains, for example, oxides of nickel, cobalt, manganese, lithium, aluminum, and oxygen as cathode materials, as well as graphite and mixtures thereof as anode materials, and some impurities such as aluminum and copper. Methods for recovering valuable metals from this black powder are broadly divided into wet processes and dry processes.

[0005] The advantage of the dry process is that the time required for the leaching process is reduced by about 70% compared to the wet process. This is because the leaching process can proceed faster since the graphite is dissolved within the alloy.

[0006] However, the dry process presents several significant challenges. First, valuable metals such as lithium and aluminum are consumed as slag, making recovery difficult. This not only reduces resource efficiency but can also result in substantial economic losses.

[0007] Second, the large amount of carbon dioxide generated when oxygen is blown in to remove graphite during the high-temperature dry process can cause environmental problems. This may result in outcomes contrary to global efforts to reduce carbon emissions and undermine the environmental sustainability of the recycling process.

[0008] The objective of the present invention to solve the aforementioned problem is to provide a valuable metal reactant recovered from a spent lithium-ion battery and a method for recovering transition metals including Ni and Co from a spent lithium-ion battery.

[0009] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0010] As a means to achieve the above-mentioned purpose, a valuable metal reactant comprising a first valuable metal containing material, a second valuable metal containing material, and carbon recovered from a waste battery according to one embodiment of the present invention, wherein the first valuable metal containing material comprises a Ni-Co alloy and a manganese-based oxide, and upon X-ray diffraction analysis, the (111) peak of the Ni-Co alloy has a position of 44.3° to 44.6°, and the MnO (200) peak of the manganese-based oxide has a position greater than 44.7° and less than 44.9°, and the second valuable metal containing material may comprise a non-magnetic material.

[0011] In a valuable metal reactant according to one embodiment of the present invention, the Ni-Co alloy particles have a spherical shape and may be in the form of flakes embedded in a second valuable metal inclusion and carbon.

[0012] In a valuable metal reactant according to one embodiment of the present invention, the average particle size of the Ni-Co alloy particles may be less than 200 μm.

[0013] In a valuable metal reactant according to one embodiment of the present invention, when X-ray diffraction analysis is performed on the first valuable metal containing material, at least one peak may occur in each interval where 2theta is 44.3° to 44.6°, 51.5° to 53°, and 76.1° to 78°.

[0014] In a valuable metal reactant according to one embodiment of the present invention, when X-ray diffraction analysis is performed on the first valuable metal containing material, at least one peak may occur in each interval where 2theta is 34.5° to 35.5°, 40.0° to 41.5°, and 69.5° to 70.5°.

[0015] In a valuable metal reactant according to one embodiment of the present invention, the Ni-Co alloy particles may include those alloyed with copper (Cu).

[0016] In a valuable metal reactant according to one embodiment of the present invention, the second valuable metal containing material may include at least one of Cu, Al, Al2O3, LiAlO2, Li5AlO4, LiAl5O8, Li2CO3, LiF, Li3PO4, Li4P2O7, LiPO3, Li2SiO3, Li4SiO4, Li2Si2O5, LiFeO2, LiFe5O8, Li3Fe5O8, and Li5FeO4.

[0017] A method for recovering a transition metal from a spent lithium-ion battery according to one embodiment of the present invention may include: a step of generating a reducing gas by thermally decomposing a separator, an outer material, and a binder present in the spent lithium-ion battery crush; a step of obtaining a valuable metal reactant by reducing Ni and Co in the spent lithium-ion battery crush with the reducing gas; a magnetic separation step of separating the valuable metal reactant into a first valuable metal containing material and a second valuable metal containing material; a step of separating Cu contained in the second valuable metal containing material; and a step of separating a lithium compound contained in the second valuable metal containing material.

[0018] In a method for recovering a transition metal from a waste lithium-ion battery according to one embodiment of the present invention, the reducing gas generated by thermally decomposing the separator, outer material, and binder may be characterized as being at least one of H2, CO, and CxHy (a hydrocarbon with 1≤x≤10 and 4≤y≤22).

[0019] A method for recovering a transition metal from a spent lithium-ion battery according to one embodiment of the present invention may further include a step of removing impurities by magnetic separation after the step of generating the reducing gas.

[0020] In a method for recovering transition metals from a spent lithium-ion battery according to one embodiment of the present invention, the step of reducing Ni and Co may be characterized by being performed at 700 to 1000°C.

[0021] In a method for recovering transition metals from a spent lithium-ion battery according to one embodiment of the present invention, the step of reducing Ni and Co may be characterized by maintaining the maximum reduction reaction temperature for 15 minutes or more.

[0022] In a method for recovering a transition metal from a waste lithium-ion battery according to one embodiment of the present invention, the step of separating Cu contained in the second valuable metal inclusion may be performed by at least one of a ball mill, a cup mill, a lot mill, a hammer mill, and an attrition mill.

[0023] A method for recovering a transition metal from a waste lithium-ion battery according to one embodiment of the present invention further comprises, after the step of separating Cu from the second valuable metal inclusion, a step of separating carbon from the second valuable metal inclusion, wherein the separation may be performed by at least one of particle size separation, cyclone separation, gravity separation, and flotation separation.

[0024] In a method for recovering transition metals from a waste lithium-ion battery according to one embodiment of the present invention, Ni and Co reduced in the magnetic separation step can be recovered with a recovery rate of 95% or more.

[0025] According to one embodiment of the present invention, a method for recovering valuable metal reactants recovered from a spent lithium-ion battery and transition metals including Ni and Co from a spent lithium-ion battery can be provided.

[0026] The effects obtainable from this invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which this invention pertains from the description below.

[0027] Figure 1 is a figure showing X-ray diffraction (XRD) measurement data of the first valuable metal inclusion.

[0028] Figure 2 is a photograph of Cu before and after separation by a roll mill.

[0029] Figure 3 is a scanning electron microscope (SEM) image of the first valuable metal inclusion after magnetic separation.

[0030] Figure 4 is a scanning electron microscope (SEM) image of the first valuable metal inclusion.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] Unless otherwise specifically stated in this specification, the % indicating the content of each element is based on weight.

[0036] For the recycling of secondary batteries, the batteries are processed through crushing, grinding, gravity separation, and magnetic separation to produce black powder, which is a mixture of cathode and anode materials. This black powder contains, for example, oxides of nickel, cobalt, manganese, lithium, aluminum, and oxygen as cathode materials, as well as graphite and mixtures thereof as anode materials, and some impurities such as aluminum and copper. Methods for recovering valuable metals from this black powder are broadly divided into wet processes and dry processes.

[0037] Among them, the wet process produces NiSO4, CoSO4, MnSO4, and Li2CO3 through leaching, solvent extraction, and lithium production. When the black powder is processed by the wet process, there is a problem in that the graphite, which is the cathode material contained in the black powder, does not dissolve in a strong acid atmosphere, resulting in an excessively long leaching process time, and there is a problem in that the yield is reduced as the black powder is separated together with the graphite.

[0038] On the other hand, the dry process is a method of recovering valuable metals by processing black powder at high temperatures. This process is carried out at high temperatures, for example, between 1400°C and 1600°C, and graphite and oxygen are introduced to reduce the Ni-Mn-Li-Al-O oxides within the black powder at high temperatures, generating CO or CO2 gas in the process. The results of this process include a Ni-Co-Mn alloy and lithium and aluminum separated in the form of slag. The Ni-Co-Mn alloy produced through the dry process can subsequently be converted into useful metal compounds such as NiSO4, CoSO4, and MnSO4 through the same wet process described above.

[0039] NCM-based rechargeable batteries are largely composed of a current collector, a cathode material, a negative electrode material, a separator, and an electrolyte. First, copper and aluminum are used as current collectors, responsible for transmitting the current generated at the electrodes to the external circuit. The cathode material consists of oxides containing lithium, nickel, cobalt, and manganese. Graphite is primarily utilized as the negative electrode material, serving to store and release electrons. Additionally, a separator is included to physically separate the cathode and negative electrodes while allowing the movement of ions. The electrolyte is injected into the separator and plays a crucial role as a medium mediating conductive ions. The electrolyte consists of a solvent and a salt. As the solvent, a mixture of organic carbonates, such as ethylene carbonate and propylene carbonate, may be used. LiPF6 is typically used as the salt, contributing to increasing the ionic conductivity of the electrolyte. These components combine to form the rechargeable battery.

[0040] Waste battery composed of the above-mentioned current collector, positive electrode material, negative electrode material, separator, and electrolyte can be completely discharged, dismantled, and crushed to prepare shredded waste battery material. By crushing the waste battery, the surface area in contact with oxygen is increased, thereby improving reaction efficiency.

[0041] The above waste battery crushed material may include not only crushed materials of the current collector, positive electrode material, negative electrode material, separator, and electrolyte as described above, but also defective products generated during the manufacturing process, residues within the manufacturing process, and generated debris.

[0042] A valuable metal reactant according to one embodiment of the present invention is recovered from crushed waste batteries and may include a first valuable metal containing material, a second valuable metal containing material, and carbon.

[0043] FIG. 1 is a figure showing X-ray diffraction (XRD) measurement data of a first valuable metal inclusion. Referring to FIG. 1, the first valuable metal inclusion includes a Ni-Co alloy and a manganese-based oxide. When X-ray diffraction analysis is performed, it can be confirmed that the (111) peak of the Ni-Co alloy is located at a position between 44.3° and 44.6°, and the MnO (200) peak of the manganese-based oxide is located at a position greater than 44.7° and less than 44.9°.

[0044] Figure 1 shows the results of X-ray diffraction (XRD) analysis using Cu (Kα-ray) on the first valuable metal inclusion after magnetic separation. XRD characteristics were measured using Rigaku’s SMARTLAB instrument.

[0045] The first valuable metal inclusion described above includes a Ni-Co alloy. Referring to FIG. 1, it can be confirmed that a Ni-Co alloy is formed through an XRD peak formed around 44.5 degrees. As Co (1.26 Å), which has a larger atomic radius than Ni (1.24 Å), is dissolved into the Ni lattice, the lattice spacing increases, causing the XRD peak to shift to a lower angle. As the content of Ni in the cathode material increases, the crystal structure of the alloy becomes closer to the structure of Ni, and thus approaches the position of the Ni (100) peak.

[0046] Meanwhile, manganese exists in the form of MnO2 with an oxidation state of +4 before heat treatment, but after heat treatment it is reduced to an oxidation state of +2, but is not reduced to a metallic state and remains in the form of an oxide (MnO). Referring to Figure 1, it can be confirmed that manganese exists stably as an oxide in the form of MnO, as the MnO (200) peak is located at a position greater than 44.7° and less than 44.9°.

[0047] The above Ni-Co alloy particles have a spherical shape and may be in the form of flakes embedded in the second valuable metal inclusion and carbon.

[0048] In addition, the average particle size of the above Ni-Co alloy particles may be less than 200 μm. FIG. 3 is a photograph of the first valuable metal inclusion after magnetic separation taken in the backscattered electron mode (BSE) of a scanning electron microscope (SEM). Referring to FIG. 3, a white Ni-Co alloy aggregate structure consisting of spherical particles with an average diameter of less than 200 μm can be observed.

[0049] In a valuable metal reactant according to one embodiment of the present invention, when X-ray diffraction analysis is performed on the first valuable metal containing material, at least one peak may occur in each interval where 2theta is 44.3° to 44.6°, 51.5° to 53°, and 76.1° to 78°.

[0050] In a valuable metal reactant according to one embodiment of the present invention, when X-ray diffraction analysis is performed on the first valuable metal containing material, at least one peak may occur in each interval where 2theta is 34.5° to 35.5°, 40.0° to 41.5°, and 69.5° to 70.5°.

[0051] In a valuable metal reactant according to one embodiment of the present invention, the Ni-Co alloy particles may include those alloyed with copper (Cu). FIG. 4 is a photograph of a first valuable metal containing material taken with a scanning electron microscope (SEM). Table 1 below shows the results of quantitative elemental analysis using Energy Dispersive Spectroscopy (EDS) by extracting an arbitrary spot from the first valuable metal containing material shown in the photograph of FIG. 4. Referring to Table 1, it can be confirmed that copper (Cu) is included in the Ni-Co alloy.

[0052] C KO KMn KCo KNi KCu K Weight % 10.75 2.95 15.27 11.00 46.71 13.30 Atomic % 35.1 17.24 10.9 17.32 31.21 8.21

[0053] Meanwhile, the second valuable metal inclusion may include a non-magnetic material. The second valuable metal inclusion may include at least one of Cu, Al, Al2O3, LiAlO2, Li5AlO4, LiAl5O8, Li2CO3, LiF, Li3PO4, Li4P2O7, LiPO3, Li2SiO3, Li4SiO4, Li2Si2O5, LiFeO2, LiFe5O8, Li3Fe5O8, and Li5FeO4. A method for recovering a transition metal from a spent lithium-ion battery according to an embodiment of the present invention will be described below.

[0054] A method for recovering a transition metal from a spent lithium-ion battery according to one embodiment of the present invention may include: a step of generating a reducing gas by thermally decomposing a separator, an outer material, and a binder present in the spent lithium-ion battery crush; a step of obtaining a valuable metal reactant by reducing Ni and Co in the spent lithium-ion battery crush with the reducing gas; a magnetic separation step of separating the valuable metal reactant into a first valuable metal containing material and a second valuable metal containing material; a step of separating Cu contained in the second valuable metal containing material; and a step of separating a lithium compound contained in the second valuable metal containing material.

[0055] In a method for recovering a transition metal from a waste lithium-ion battery according to one embodiment of the present invention, the reducing gas generated by thermally decomposing the separator, outer material, and binder may be characterized as being at least one of H2, CO, and CxHy (a hydrocarbon with 1≤x≤10 and 4≤y≤22).

[0056] A method for recovering a transition metal from a spent lithium-ion battery according to one embodiment of the present invention may further include a step of removing impurities by magnetic separation after the step of generating the reducing gas. The magnetic separation may, for example, utilize a magnetic material to separate particles through contact with the magnetic material, and various types of magnetic separation methods may be applied. Since iron is a material that exhibits strong magnetism, magnetic materials containing iron components can be separated from the crushed spent battery material containing iron components by utilizing magnetism.

[0057] In a method for recovering transition metals from spent lithium-ion batteries according to one embodiment of the present invention, the step of reducing Ni and Co may be characterized by being performed at 700 to 1000°C. In the reduction step, a heat treatment process may be carried out in a reducing atmosphere to minimize the oxidation of graphite. Therefore, the problem of excessive carbon dioxide generation when oxygen is blown in to remove graphite in a high-temperature dry process can be improved. By carrying out the reduction step at 700 to 1000°C, only Ni and Co among the complex metal oxides composed of lithium-nickel-cobalt-manganese in the crushed spent battery material can be selectively reduced.

[0058] In a method for recovering transition metals from a spent lithium-ion battery according to one embodiment of the present invention, the step of reducing Ni and Co may be characterized by maintaining the maximum reduction reaction temperature for 15 minutes or more.

[0059] After the above reduction heat treatment, the valuable metal reactants include LiAlO2, graphite, Ni-Co alloy, and MnO. The lithium-nickel-cobalt-manganese composite oxide (cathode material), in its form prior to the reduction heat treatment, does not exhibit magnetism. However, when reduced to the form of the Ni-Co alloy as described above after the reduction heat treatment, it regains its original magnetic properties. The lithium contained in the crushed waste battery material prior to the heat treatment is converted into the form of LiAlO2 after the reduction heat treatment and can be obtained as a non-magnetic material. Therefore, the first valuable metal containing material that exhibits magnetism and the second valuable metal containing material that exhibits non-magnetism can be separated through magnetic separation.

[0060] Subsequently, the step of separating Cu contained in the second valuable metal inclusion can be performed by at least one of a ball mill, a cup mill, a lot mill, a hammer mill, or an attrition mill. Figure 2(a) is a photograph of the second valuable metal inclusion before roll milling, and (b) is a photograph of Cu after separation by roll milling. Since Cu has ductility, it clumps into large particles during roll milling, and in this process, some black crushed material attached to the Cu falls off. By distinguishing particle sizes through the above method, Cu contained in the second valuable metal inclusion can be easily separated.

[0061] A method for recovering a transition metal from a waste lithium-ion battery according to one embodiment of the present invention further comprises, after the step of separating Cu from the second valuable metal inclusion, a step of separating carbon from the second valuable metal inclusion, wherein the separation may be performed by at least one of particle size separation, cyclone separation, gravity separation, and flotation separation.

[0062] In a method for recovering transition metals from a waste lithium-ion battery according to one embodiment of the present invention, Ni and Co reduced in the magnetic separation step can be recovered with a recovery rate of 95% or more.

[0063] Although exemplary embodiments of the present invention have been described above, the present invention is not limited thereto, and those skilled in the art will understand that various changes and modifications are possible within the scope and concept of the claims set forth below.

Claims

1. A valuable metal reactant comprising a first valuable metal containing material, a second valuable metal containing material, and carbon recovered from a waste battery, The first valuable metal inclusion above includes a Ni-Co alloy and a manganese-based oxide, and When X-ray diffraction analysis is performed, the (111) peak of the Ni-Co alloy is at a position between 44.3° and 44.6°, and the MnO (200) peak among the manganese-based oxides is at a position greater than 44.7° and less than 44.9°, The above second valuable metal inclusion is a valuable metal reactant comprising a non-magnetic material.

2. In Claim 1, The above Ni-Co alloy particles have a spherical shape and are in the form of flakes embedded in the second valuable metal inclusion and carbon, and are valuable metal reactants.

3. In Claim 1, A valuable metal reactant in which the average particle size of the above Ni-Co alloy particles is less than 200 μm.

4. In Claim 1, When X-ray diffraction analysis was performed on the above-mentioned first valuable metal inclusion, A valuable metal reactant having at least one peak in each interval where 2theta is 44.3° to 44.6°, 51.5° to 53°, and 76.1° to 78°.

5. In Claim 1, When X-ray diffraction analysis was performed on the above-mentioned first valuable metal inclusion, A valuable metal reactant having at least one peak in each interval where 2theta is 34.5° to 35.5°, 40.0° to 41.5°, and 69.5° to 70.5°.

6. In Claim 1, The above Ni-Co alloy particles include a valuable metal reactant comprising alloyed with copper (Cu).

7. In Claim 1, The second valuable metal containing above is a valuable metal reactant comprising at least one of Cu, Al, Al2O3, LiAlO2, Li5AlO4, LiAl5O8, Li2CO3, LiF, Li3PO4, Li4P2O7, LiPO3, Li2SiO3, Li4SiO4, Li2Si2O5, LiFeO2, LiFe5O8, Li3Fe5O8, and Li5FeO4.

8. A method for recovering transition metals from spent lithium-ion batteries, A step of generating reducing gas by thermally decomposing the separator, outer material, and binder present in the shredded waste lithium-ion battery material; A step of obtaining valuable metal reactants by reducing Ni and Co in the crushed waste lithium-ion battery with the above-mentioned reducing gas; A magnetic separation step for separating the above valuable metal reactant into a first valuable metal content and a second valuable metal content; A step of separating Cu contained in the second valuable metal inclusion; and A method comprising the step of separating a lithium compound contained in the second valuable metal inclusion.

9. In Claim 8, A method characterized in that the reducing gas generated by thermally decomposing the above-mentioned separator, outer material, and binder is at least one of H2, CO, and CxHy (a hydrocarbon with 1≤x≤10 and 4≤y≤22).

10. In claim 8, A method characterized by further including a step of removing impurities by magnetic separation after the step of generating the reducing gas.

11. In Claim 8, A method characterized in that the step of reducing Ni and Co is performed at 700 to 1000°C.

12. In claim 8, A method characterized by the step of reducing Ni and Co having a reduction reaction time of 15 minutes or more while maintaining the maximum reduction reaction temperature.

13. In claim 8, A method in which the step of separating Cu contained in the second valuable metal inclusion is performed by at least one of a ball mill, a cup mill, a lot mill, a hammer mill, and an attrition mill.

14. In Claim 8, After the step of separating Cu from the second valuable metal inclusion, The above-mentioned second valuable metal inclusion further includes a step of separating carbon, and The above separation is performed by at least one of particle size separation, cyclone separation, gravity separation, and flotation separation.

15. In Claim 8, A method in which Ni and Co reduced in the above magnetic separation step are recovered with a recovery rate of 95% or more.

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