Method for regenerating lithium precursors

Abstract

In the method for regenerating a lithium precursor, a positive electrode active material mixture containing lithium composite oxide particles is prepared. The positive electrode active material mixture is agglomerated to produce an active material powder having a unimodal particle size distribution. The active material powder is reduced to produce a preliminary precursor mixture. The lithium precursor is recovered from the preliminary precursor mixture. This can improve the recovery efficiency of the lithium precursor.

Description

Technical Field

[0001] The present invention relates to a method for regenerating a lithium precursor, and more particularly to a method for regenerating a lithium precursor from a waste lithium-containing compound.

Background Art

[0002] A secondary battery is a battery capable of repeating charging and discharging, and has been widely applied to portable electronic communication devices such as camcorders, mobile phones, and notebook computers as the information communication and display industries have developed. Examples of secondary batteries include lithium secondary batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and the like. Among them, lithium secondary batteries have been actively developed and applied because of their high operating voltage and energy density per unit weight, as well as their advantages in charging speed and weight reduction.

[0003] A lithium secondary battery can include an electrode assembly including a positive electrode, a negative electrode, and a separator, and an electrolyte that impregnates the electrode assembly. The lithium secondary battery can further include, for example, a pouch-shaped exterior material that houses the electrode assembly and the electrolyte.

[0004] As the positive electrode active material of the lithium secondary battery, a lithium metal oxide can be used. The lithium metal oxide can further contain transition metals such as nickel, cobalt, and manganese together.

[0005] The lithium metal oxide as the positive electrode active material can be produced by reacting a lithium precursor with a nickel-cobalt-manganese (NCM) precursor containing nickel, cobalt, and manganese.

[0006] Because the aforementioned high-cost valuable metals are used in the positive electrode active material, the manufacturing of the positive electrode material accounts for more than 20% of the manufacturing cost. Furthermore, in recent years, with growing concern for environmental protection, research into recycling methods for positive electrode active materials is progressing. For the recycling of the positive electrode active material, it is necessary to regenerate the lithium precursor from waste positive electrodes with high efficiency and high purity. [Overview of the project] [Problems that the invention aims to solve]

[0007] One objective of the present invention is to provide a method for regenerating lithium precursors to recover lithium precursors from lithium-containing compounds in high purity and high yield. [Means for solving the problem]

[0008] In the lithium precursor regeneration method according to an embodiment of the present invention, a positive electrode active material mixture containing lithium composite oxide particles is prepared. The positive electrode active material mixture is agglomerated to produce an active material powder having a unimodal particle size distribution. The active material powder is subjected to a reduction treatment to produce a preliminary precursor mixture. The lithium precursor is recovered from the preliminary precursor mixture.

[0009] In some embodiments, the positive electrode active material mixture In the preparation stage, the positive electrode is separated from the waste lithium secondary battery. Then, the separated positive electrode is crushed to produce a positive electrode active material mixture.

[0010] In some embodiments, the positive electrode active material mixture may have a multimodal particle size distribution.

[0011] In some embodiments, the particle size of the positive electrode active material mixture may be 10 to 500 μm.

[0012] In some embodiments, the particle size of the active material powder may be 20 to 1,000 μm.

[0013] In some embodiments, the density of the active material powder is 1 to 10 g / cm³. 3 That's fine.

[0014] In some embodiments, the active material powder may contain aggregates with a volume fraction of 0.7 or more.

[0015] In some embodiments, the active material powder may include aggregates with a volume fraction of 0.58 or less.

[0016] In some embodiments, the Cathode active material mixture Aggregation can be carried out using a disc pelletizer or a spray dryer.

[0017] In some embodiments, the reduction treatment of the active material powder can be carried out in a fluidized bed reactor using a reducing gas. [Effects of the Invention]

[0018] According to the exemplary embodiment described above, a positive electrode active material mixture can be agglomerated to produce an active material powder having a unimodal particle size distribution. In this case, the active material powder is more easily fluidized, which improves the efficiency of the reduction process. This makes it easier to obtain a lithium precursor with high yield and high purity.

[0019] Furthermore, the active material powder can have a relatively large particle size. This effectively reduces the amount of the active material powder that scatters and flows out during the fluidization process. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1 is a schematic flowchart illustrating a method for regenerating a lithium precursor according to an exemplary embodiment. [Figure 2]FIG. 2 is a schematic graph showing the minimum fluidization velocity according to the density of the active material powder according to an exemplary embodiment. [Figure 3] FIG. 3 is a schematic diagram showing a disk pelletizer according to an exemplary embodiment. [Figure 4] FIG. 4 is a schematic diagram showing a spray dryer according to an exemplary embodiment. [Figure 5] FIG. 5 is a schematic graph showing the minimum fluidization velocity according to the volume fraction of the active material powder according to an exemplary embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

[0021] Embodiments of the present invention aggregate a positive electrode active material mixture to produce an active material powder having a unimodal particle size distribution. Since the active material powder has a unimodal particle size distribution, it can be more easily fluidized.

[0022] As used herein, the term "unimodal" particle size distribution means that there is one peak in the particle size distribution diagram. For example, a "multimodal" particle size distribution means that there are multiple peaks in the particle size distribution diagram.

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, these embodiments are merely exemplary and do not limit the present invention.

[0024] As used herein, the term "precursor" is used to comprehensively refer to a compound containing a specific metal in order to provide the specific metal contained in the electrode active material.

[0025] FIG. 1 is a schematic flowchart for explaining a method for regenerating a lithium precursor according to an exemplary embodiment.

[0026] Referring to Figure 1, a cathode active material mixture containing a lithium composite oxide can be prepared (e.g., step S10).

[0027] The positive electrode active material mixture may include lithium-containing compounds obtained or regenerated from electrical or chemical elements. The positive electrode active material mixture may include various lithium-containing compounds such as lithium oxide, lithium carbon oxide, and lithium hydroxide.

[0028] The positive electrode active material mixture may include lithium-containing compounds obtained or recycled from waste lithium secondary batteries. The waste lithium secondary battery may include an electrode assembly comprising a positive electrode, a negative electrode, and a separator membrane interposed between the positive electrode and the negative electrode. The positive electrode and the negative electrode may each include a positive electrode current collector and a positive electrode active material layer and a negative electrode active material layer coated on the negative electrode current collector, respectively.

[0029] For example, the positive electrode active material contained in the positive electrode active material layer may include a lithium composite oxide containing lithium and a transition metal.

[0030] In some embodiments, the positive electrode active material may include a lithium composite oxide represented by the following chemical formula 1.

[0031] [Chemical formula 1] Li x M1 a M2 b M3 c O y

[0032] In chemical formula 1, M1, M2, and M3 may be transition metals selected from Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga, or B. <x≦1.1、2≦y≦2.2、0<a<1、0<b<1、0<c<1、0<a+b+c≦1であってもよい。

[0033] In some embodiments, the positive electrode active material may include an NCM-based lithium composite oxide containing nickel, cobalt, and manganese. The NCM-based lithium composite oxide can be produced by reacting a lithium precursor and an NCM precursor (e.g., an NCM oxide) with each other, for example, by a coprecipitation reaction.

[0034] However, the embodiments of the present invention can be applied not only to cathode materials containing the NCM-based lithium composite oxide, but also to lithium-containing lithium composite oxide cathode materials in general.

[0035] For example, the positive electrode can be separated and recovered from the waste lithium secondary battery. The positive electrode includes a positive electrode current collector (e.g., aluminum (Al)) and a positive electrode active material layer, and the positive electrode active material layer may include a conductive material and a binder together with the positive electrode active material.

[0036] The conductive material may include, for example, carbon-based materials such as graphite, carbon black, graphene, and carbon nanotubes.

[0037] The binder may include, for example, resin substances such as vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, and polymethyl methacrylate.

[0038] In some exemplary embodiments, the positive electrode active material mixture can be prepared by separating the positive electrode from the waste lithium secondary battery and grinding the separated positive electrode.

[0039] The aforementioned grinding can be carried out using commonly used grinding equipment. For example, the grinding can be carried out using a hammer mill, shredder, cut crusher, etc. The positive electrode active material mixture can be prepared into a powder by grinding.

[0040] For example, after grinding, the ground particles can be classified by particle size using a conventional classification device. For example, the classification device may be a twist screen.

[0041] In some embodiments, the recovered positive electrode may be heat-treated before grinding. This can facilitate the desorption of the positive electrode current collector during the grinding process and at least partially remove the binder and conductive material. The temperature of the heat treatment may be, for example, about 100 to 500°C, preferably about 350 to 450°C.

[0042] For example, the positive electrode current collector can be removed by immersing the separated positive electrode in an organic solvent. The positive electrode current collector can be removed from the separated positive electrode by centrifugation, and the positive electrode active material mixture can be selectively extracted by removing the positive electrode current collector.

[0043] Through the aforementioned process, a positive electrode active material mixture can be obtained in which positive electrode current collector components such as aluminum are substantially completely separated and removed, and the content of carbon-based components derived from the carbon-based conductive material and binder is removed or reduced.

[0044] In an exemplary embodiment, the cathode active material mixture can be agglomerated to produce an active material powder having a unimodal particle size distribution (for example, step S20).

[0045] In some exemplary embodiments, the cathode active material mixture may have a multimodal particle size distribution.

[0046] In this case, a mixture of positive electrode active materials having a multimodal particle size distribution can be agglomerated to produce an active material powder having a unimodal particle size distribution.

[0047] For example, a positive electrode active material mixture having a multimodal particle size distribution may not be easily fluidized during the fluidization process because the positive electrode active materials have different particle sizes.

[0048] For example, if the gas flow rate for fluidizing the positive electrode active material mixture is low, sufficient fluidization may not be possible. If the gas flow rate is high, the positive electrode active material with small particle size particles may be scattered, which may reduce the recovery efficiency of the lithium precursor described later.

[0049] In contrast, the active material powder, unlike the positive electrode active material mixture, has a unimodal particle size distribution. Therefore, by adjusting the gas flow rate according to the particle size of the active material powder, fluidization can be performed more easily. This makes it possible to further improve the recovery efficiency of the lithium precursor.

[0050] According to some exemplary embodiments, the particle size of the positive electrode active material mixture may be about 10 to 500 μm. Within this range, aggregation of the positive electrode active material mixture can be effectively performed, making it easier to produce an active material powder having a unimodal particle size distribution.

[0051] According to some exemplary embodiments, the particle size of the active material powder may be about 20 to 1,000 μm. More preferably, the particle size of the active material powder may be about 30 to 500 μm. For example, satisfying this range makes it easier to fluidize the active material powder as described later.

[0052] Furthermore, if the particle size of the active material powder produced in the process of agglomerating the positive electrode active material mixture falls within the aforementioned range, it becomes easier to produce an active material powder having a unimodal particle size distribution.

[0053] According to some exemplary embodiments, the density of the active material powder is approximately 1 to 10 g / cm³. 3 This may also be the case. For example, if the active material powder is within the density range, the active material powder can be made more easily fluid.

[0054] Figure 2 is a graph showing the minimum fluidization rate with respect to the density of the active material powder according to an exemplary embodiment.

[0055] Referring to Figure 2, for example, the greater the density of the active material powder, the greater the fluidization rate for fluidizing the active material powder, and the less the density, the greater the fluidization rate for fluidizing the active material powder.

[0056] In this case, the density of the active material powder can be appropriately adjusted according to the rate of the gas flowing into the fluidized bed reactor, which will be described later. This makes it easier to fluidize the active material powder. This improves the recovery efficiency of the lithium precursor.

[0057] According to some exemplary embodiments, the aggregation of the positive electrode active material mixture can be carried out using a disc pelletizer or a spray dryer.

[0058] Figure 3 is a schematic diagram showing a disk pelletizer according to an exemplary embodiment.

[0059] Referring to Figure 3, the disc pelletizer 100 includes a broad, cylindrical agglomeration body 110 positioned at an angle, into which the positive electrode active material mixture can be injected and agglomerated into an active material powder having a unimodal particle size distribution.

[0060] For example, the positive electrode active material mixture can rotate inside the agglomeration body 110. In this case, larger particles can rotate at the bottom of the agglomeration body 110, and smaller particles can rotate at the top of the agglomeration body 110. Water can be sprayed onto the positive electrode active material mixture rotating inside the agglomeration body 110 to cause the positive electrode active material mixtures with different particle sizes to agglomerate together.

[0061] In this case, the positive electrode active material mixture with increased particle size moves to the lower part of the agglomeration body 110, and the positive electrode active material mixture with a constant particle size can be discharged through the collection section 120 located at the lower part of the agglomeration body 110. This makes it possible to easily produce an active material powder having a unimodal particle size distribution.

[0062] For example, the angle between the side surface of the aggregated body 110 and the bottom surface may be 40 to 60°. Within this angle range, it is possible to more easily produce an active material powder having a unimodal particle size distribution.

[0063] Figure 4 is a schematic diagram illustrating a spray dryer according to an exemplary embodiment.

[0064] Referring to Figure 4, the spray dryer 200 may include an injector 210, a drying and condensation body 220, and a separator 230.

[0065] For example, the positive electrode active material mixture can be mixed with water to produce a turbidity 240. For example, the turbidity 240 can be introduced into the dry condensation body 220 via an injector 210. The injected turbidity 240 can be dried by a drying gas injected into the top of the dry condensation body 220. In this case, the water evaporates and the positive electrode active material mixture condenses, thereby producing a preliminary active material powder. The preliminary active material powder may include the condensed active material powder and the uncondensed positive electrode active material mixture.

[0066] For example, the sprayer 210 may include a spray nozzle. For example, the spray particle size of the spray nozzle may be about 100 to 1,000 μm.

[0067] For example, the preliminary active material powder can be moved to the separator 230 and separated into the active material powder and the positive electrode active material mixture. For example, the preliminary active material powder can be separated into the active material powder and the positive electrode active material mixture by a cyclone formed by injecting cyclone gas into the separator 230.

[0068] For example, the preliminary active material powder rotates spirally along the inner surface of the separator 230 by the cyclone, and the active material powder, which has agglomerated and increased in particle size during the rotation process, can gradually descend. This makes it possible to produce active material powder having a unimodal particle size distribution. In this case, the produced active material powder can be collected in an active material powder collector 260 located at the bottom of the separator 230.

[0069] For example, the unaggregated positive electrode active material mixture separated from the preliminary active material powder can be scattered to the top of the separator 230 by the cyclone. The scattered positive electrode active material mixture can be discharged along with the residual gas through an outlet 250 located at the top of the separator 230. For example, the positive electrode active material mixture discharged from the outlet 250 can be mixed again with water to produce a turbid liquid 240.

[0070] In some embodiments, the volume fraction of aggregates contained in the active material powder can be selectively adjusted.

[0071] For example, the volume fraction of aggregates contained in the active material powder can be adjusted by adjusting the rotation speed of the agglomeration body 110 of the aforementioned disc pelletizer 100, or by adjusting the angle that the side surface of the agglomeration body 110 makes with the bottom surface.

[0072] For example, the spraying speed of the turbid liquid 240 can be adjusted using the sprayer 210 of the aforementioned spray dryer 200, thereby adjusting the volume fraction of aggregates contained in the active material powder.

[0073] For example, the volume fraction may mean the value obtained by subtracting the porosity of the aggregate from 1. For example, the porosity can be determined by filling a container with particles (e.g., the aggregate), adding water until the container is full, and then dividing the amount of water added by the volume of the container.

[0074] In some embodiments, the active material powder may include aggregates with a volume fraction of 0.7 or more (for example, a volume fraction of voids of 0.3 or less). Preferably, the volume fraction may be between 0.7 and 0.9.

[0075] If the volume fraction of aggregates contained in the active material powder falls within the aforementioned range, for example, the binding force between particles contained in the aggregates can be relatively increased. This makes it possible to reduce the proportion of particles that are scattered and lost during the reduction treatment step in the fluidized bed reactor described later (for example, the particle scattering loss rate).

[0076] In some embodiments, the active material powder may include aggregates with a volume fraction of 0.58 or less (for example, a volume fraction of voids of 0.42 or more). Preferably, the volume fraction may be between 0.1 and 0.58.

[0077] If the volume fraction of aggregates contained in the active material powder falls within the aforementioned range, fluidization can be performed smoothly, for example, in the reduction treatment step in a fluidized bed reactor. This makes it possible to reduce the amount of reducing gas and carrier gas introduced, thereby improving process economics.

[0078] Figure 5 is a schematic graph showing the minimum fluidization rate by volume fraction of the active material powder according to an exemplary embodiment.

[0079] Referring to Figure 5, a low volume fraction of aggregates in the active material powder can reduce the minimum fluidization rate required for fluidization.

[0080] For example, the volume fraction of aggregates contained in the active material powder can be selectively adjusted according to the purpose and circumstances. This makes it possible to achieve excellent processability and lithium precursor recovery rates.

[0081] According to an exemplary embodiment, a preliminary precursor mixture can be produced from the active material powder (for example, step S30). In an exemplary embodiment, the preliminary precursor mixture can be produced by reducing the active material powder.

[0082] In some embodiments, the hydrogen reduction treatment can be carried out by a fluidized bed reactor. For example, the active material powder can be introduced into the fluidized bed reactor, and a reducing gas can be injected from the bottom of the fluidized bed reactor. For example, the reducing gas may be hydrogen gas.

[0083] The reducing gas can form a cyclone from the bottom of the fluidized bed reactor, and the preliminary precursor mixture can be generated in contact with the active material powder.

[0084] In some embodiments, the particles of the active material powder do not aggregate, and the particle size can be relatively small (e.g., 200 μm or less). In this case, the reducing gas can be injected into the fluidized bed reactor at a flow rate of 8 to 12 cm / s. This reduces the scattering of fine particles due to excessive flow, prevents the unnecessary introduction of reducing gas, and achieves excellent process efficiency and economic efficiency.

[0085] In some embodiments, the particles of the active material powder may partially aggregate, resulting in a relatively larger particle size (e.g., 400 μm or larger). In this case, the reducing gas can be injected into the fluidized bed reactor at a flow rate exceeding 16 cm / s. This enables smooth particle flow and uniform reduction.

[0086] For example, in the aforementioned active material powder manufacturing step, the positive electrode active material mixture may aggregate. In this case, the percentage of particles contained in the active material powder that are scattered and lost to the upper part of the fluidized bed reactor during the reduction treatment (e.g., particle scattering loss rate) can be reduced. This makes it possible to manufacture a preliminary precursor mixture while minimizing the loss of active material powder particles, and to ensure a high lithium precursor recovery rate in the lithium precursor recovery step described later.

[0087] For example, the carrier gas can be mixed and injected from the bottom of the fluidized bed reactor along with the reducing gas. This allows the fluidized bed to promote gas-solid mixing and accelerate the reaction, and facilitates the formation of a reaction bed of the preliminary precursor mixture within the fluidized bed reactor. The carrier gas may include, for example, an inert gas such as nitrogen (N2) or argon (Ar).

[0088] The preliminary precursor mixture may include the hydrogen reduction reaction product of the lithium-transition metal oxide contained in the active material powder. When an NCM-based lithium oxide is used as the lithium-transition metal oxide, the preliminary precursor mixture may include a preliminary lithium precursor and a transition metal-containing reaction product.

[0089] The aforementioned pre-lithium precursor may include lithium hydroxide, lithium oxide, and / or lithium carbon. According to an exemplary embodiment, since the pre-lithium precursor is obtained by a hydrogen reduction reaction, the mixed content of lithium carbon can be reduced.

[0090] The transition metal-containing reactant may include Ni, Co, NiO, CoO, MnO, and the like. The hydrogen reduction reaction can be carried out at approximately 400 to 700°C, preferably 450 to 550°C.

[0091] According to an exemplary embodiment, after collecting the preliminary precursor mixture, a washing treatment can be performed (for example, step S40).

[0092] Through the aforementioned water washing process, the preliminary lithium precursor can be converted into a lithium precursor substantially composed of lithium hydroxide. For example, lithium oxide and lithium carbon mixed in the preliminary lithium precursor can be converted into lithium hydroxide by reacting with water or removed by washing with water. This makes it possible to produce a high-purity lithium precursor converted into the desired form of lithium hydroxide.

[0093] The aforementioned preliminary lithium precursor can react with water and dissolve to produce a substantially aqueous lithium hydroxide solution.

[0094] The transition metal-containing reactant contained in the preliminary precursor mixture can precipitate without dissolving or reacting in water after the washing treatment. This allows the transition metal-containing reactant to be separated by filtration, thereby obtaining a lithium precursor containing high-purity lithium hydroxide.

[0095] In some embodiments, the washing process can be carried out under conditions in which carbon dioxide (CO2) is excluded. For example, by performing the washing process in a CO2-free atmosphere (e.g., an air atmosphere from which CO2 has been removed), the regeneration of lithium carbon oxide can be prevented.

[0096] In one embodiment, a CO2-free atmosphere can be formed by purging the water provided during the washing process with a CO2-deficient gas (for example, nitrogen purging).

[0097] In some embodiments, the precipitated transition metal-containing reaction product can be treated with an acid solution to form precursors in the form of salts of each transition metal. In one embodiment, sulfuric acid can be used as the acid solution. In this case, NiSO4, MnSO4, and CoSO4 can be recovered as the transition metal precursors, respectively.

[0098] As mentioned above, the preliminary precursor mixture produced by hydrogen reduction can be washed with water to obtain a lithium precursor that is substantially composed of lithium hydroxide. This prevents the by-production of other forms of lithium precursors, such as lithium carbon dioxide, and allows for the production of a higher-capacity, longer-lived cathode active material.

[0099] The lithium precursor may include lithium hydroxide (LiOH), lithium oxide (Li2O), or lithium carbon oxide (Li2CO3). From the viewpoint of charge / discharge characteristics, lifespan characteristics, and high-temperature stability of lithium secondary batteries, lithium hydroxide is advantageous as a lithium precursor. For example, lithium carbon oxide may undergo deposition reactions on the separation membrane, weakening its lifespan stability.

[0100] The following are preferred embodiments to aid in understanding the present invention, but these embodiments are merely illustrative and do not limit the scope of the appended claims. It will be apparent to those skilled in the art that various changes and modifications can be made to these embodiments within the scope of the present invention and the technical concept, and that these variations and modifications will naturally fall within the scope of the appended claims.

[0101] Example 1 One kilogram of positive electrode material separated from a waste lithium secondary battery was cut into small units and pulverized by milling to obtain a mixture of positive electrode active materials containing Li-Ni-Co-Mn oxide and a binder (polyvinylidene fluoride, PVDF). The mixture of positive electrode active materials had a multimodal particle size distribution with particle sizes ranging from 10 to 100 μm.

[0102] The positive electrode active material mixture was placed in a disc pelletizer to produce an active material powder with a particle size of 15 μm and a unimodal particle size distribution. The density of the active material powder was 5 g / cm³. 3 That was the case.

[0103] The active material powder was fluidized in the fluidized bed reactor and reacted with hydrogen gas to produce a preliminary precursor mixture containing lithium oxide and lithium hydroxide. The internal temperature of the fluidized bed reactor was maintained at 450°C. The flow rate of the hydrogen gas injected into the fluidized bed reactor was 20 cm / s.

[0104] The formed preliminary precursor mixture was collected and washed with water. The resulting aqueous lithium precursor solution was separated to obtain the lithium precursor.

[0105] Example 2~ 10 A lithium precursor was obtained in the same manner as in Example 1, except that the particle size, density, and hydrogen gas flow rate of the manufactured active material powder were as shown in Table 1 below.

[0106] Comparative Example A lithium precursor was obtained in the same manner as in Example 1, except that the step of producing an active material powder from the positive electrode active material mixture was omitted, and the positive electrode active material mixture was immediately injected into the fluidized bed reactor to perform the hydrogen reduction step.

[0107] Experimental example (1) Measurement of particle dispersion loss rate In the above examples and comparative examples, the particle scattering loss rate was calculated by determining the weight of the preliminary precursor mixture after reduction relative to the weight of the active material powder before reduction using the following formula.

[0108] [formula] Particle dispersion loss rate (%) = {(Weight of active material powder - Weight of preliminary precursor mixture) / (Weight of active material powder)} × 100

[0109] (2) Liquidity assessment In the above examples and comparative examples, the presence of non-flowing active material powder at the bottom of the fluidized bed reactor was visually observed. O: No aggregates of non-flowing active material powder are observed at the bottom of the fluidized bed reactor. X: An aggregate of non-flowing active material powder is observed at the bottom of the fluidized bed reactor.

[0110] The physical properties and particle dispersion loss rates for the above-mentioned examples and comparative examples are shown in Table 1 below.

[0111] [Table 1]

[0112] Referring to Table 1, in the example in which the positive electrode active material mixture was agglomerated into an active material powder having a single-rod particle size distribution, and then the active material powder was hydrogen-reduced in a fluidized bed reactor, the particle scattering loss rate in the fluidized bed reactor was reduced compared to the comparative example in which the positive electrode active material mixture was reduced immediately. As a result, the pre-precursor mixture was produced while minimizing the loss of active material powder particles, and the lithium precursor recovery rate was increased.

[0113] However, Example 1, in which the particle size of the active material powder was less than 20 μm, had a higher particle dispersion loss rate compared to Examples 2-6, in which the particle size was between 20 and 1,000 μm.

[0114] Furthermore, Example 7, in which the particle size of the active material powder exceeded 1,000 μm, had heavier powder particles compared to Examples 2-6, resulting in reduced fluidity.

[0115] Furthermore, Examples 8 and 9, in which the particle size is 200 μm or less and the hydrogen gas flow rate is 8 to 12 cm / s, are comparable to Examples 8 and 9, in which the hydrogen gas flow rate exceeds 12 cm / s despite having the same particle size. 2 and 3 Compared to the previous method, the particle dispersion loss rate decreased.

[0116] Furthermore, Example 10, in which the particle size was 400 μm or larger and the hydrogen gas flow rate was less than 16 cm / s, showed reduced fluidity compared to Example 4, which had the same particle size.

Claims

1. The steps include preparing a positive electrode active material mixture containing lithium composite oxide particles, The steps include: agglomerating the positive electrode active material mixture to produce an active material powder having a unimodal particle size distribution; The steps include: reducing the active material powder to produce a preliminary precursor mixture; The step includes recovering a lithium precursor from the aforementioned preliminary precursor mixture, A method for regenerating a lithium precursor, wherein the reduction treatment of the active material powder is carried out in a fluidized bed reactor using a reducing gas.

2. The step of preparing the positive electrode active material mixture includes the step of separating the positive electrode from the waste lithium secondary battery, A method for regenerating a lithium precursor according to claim 1, comprising the step of crushing the separated positive electrode to produce a positive electrode active material mixture.

3. The method for regenerating a lithium precursor according to claim 2, wherein the positive electrode active material mixture has a multimodal particle size distribution.

4. The method for regenerating a lithium precursor according to claim 3, wherein the particle size of the positive electrode active material mixture is 10 to 500 μm.

5. The method for regenerating a lithium precursor according to claim 1, wherein the particle size of the active material powder is 20 to 1,000 μm.

6. The density of the active material powder is 1 to 10 g / cm³. ３ The method for regenerating a lithium precursor according to claim 1.

7. The method for regenerating a lithium precursor according to claim 1, wherein the active material powder includes aggregates with a volume fraction of 0.7 or more.

8. The method for regenerating a lithium precursor according to claim 1, wherein the active material powder includes aggregates with a volume fraction of 0.58 or less.

9. The method for regenerating a lithium precursor according to claim 1, wherein the aggregation of the positive electrode active material mixture is performed using a disc pelletizer or a spray dryer.

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