Method for recovering active metals from lithium secondary batteries

Abstract

1. A method for recovering active metals of lithium secondary batteries, comprising: preparing a cathode active material mixture from a cathode of a waste lithium secondary battery; fluidizing the cathode active material mixture in a fluidized bed reactor with an oxygen-containing gas; injecting a reducing gas into the fluidized bed reactor to form a pre-precursor mixture from the fluidized cathode active material mixture; and recovering a lithium precursor from the pre-precursor mixture.

Description

[Technical Field]

[0001] The present invention relates to a method for recovering active metals from lithium secondary batteries, and more particularly to a method for recovering active metals from discarded positive electrodes of lithium secondary batteries. [Background technology]

[0002] Secondary batteries are capable of repeated charging and discharging, and have been widely used in portable electronic communication devices such as camcorders, mobile phones, and laptops with the development of the information and communication and display industries. Examples of secondary batteries include lithium secondary batteries, nickel-cadmium batteries, and nickel-metal hydride batteries. Among them, lithium secondary batteries have been actively developed and applied due to their high operating voltage and energy density per unit weight, as well as their advantages of fast charging and lightweight design.

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

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

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

[0006] The use of the aforementioned expensive valuable metals in the positive electrode active material results in a significant cost for the production of the positive electrode material. Furthermore, in recent years, growing interest in environmental protection has led to research into methods for recycling positive electrode active materials. To recycle the positive electrode active material, it is necessary to regenerate the lithium precursor from waste positive electrodes with high efficiency and high purity. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a method for recovering active metals of lithium secondary batteries with high efficiency and high purity. [Means for solving the problem]

[0008] In the method for recovering active metals from a lithium secondary battery according to an embodiment of the present invention, spare A positive electrode active material mixture is prepared. spare The positive electrode active material mixture is fluidized in a fluidized bed reactor with an oxygen-containing gas. to form a positive electrode active material mixture. A reducing gas is injected into the fluidized bed reactor to form a pre-precursor mixture from the fluidized cathode active material mixture, and a lithium precursor is recovered from the pre-precursor mixture.

[0009] In some embodiments, the positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector and including a binder, a conductive material, and a positive electrode active material. spare The step of preparing a positive electrode active material mixture may include removing the positive electrode current collector from the positive electrode. spare The positive electrode active material mixture may include the binder, the conductive material, and the positive electrode active material.

[0010] In some embodiments, the spare The step of fluidizing the positive electrode active material mixture with the oxygen-containing gas may include decomposing or combusting the binder and the conductive material in the fluidized bed reactor.

[0011] In some embodiments, the oxygen-containing gas can include oxygen (O) and a non-reactive gas, which can include at least one selected from the group consisting of helium (He), nitrogen (N), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).

[0012] In some embodiments, the Oxygen-containing The volume ratio of oxygen to the total volume of the gas may be 10 to 30 vol %, and the volume ratio of the non-reactive gas may be 70 to 90 vol %.

[0013] In some embodiments, the spare The step of fluidizing the positive electrode active material mixture with the oxygen-containing gas can be carried out at a temperature of 100 to 600°C.

[0014] In some embodiments, the spare The step of fluidizing the positive electrode active material mixture with the oxygen-containing gas can include raising the temperature from a temperature below 50° C. to a target temperature in the range of 400 to 600° C. for 1 to 2 hours. In some embodiments, the step of forming the preliminary positive electrode active material mixture can include heat treating at the target temperature for 2 to 5 hours.

[0015] In some embodiments, the reducing gas can include hydrogen.

[0016] In some embodiments, the step of forming the pre-precursor mixture can be carried out at a temperature in the range of 400-500°C.

[0017] In some embodiments, the spare The steps of fluidizing the positive electrode active material mixture with the oxygen-containing gas and forming the pre-precursor mixture can be performed in situ consecutively within the fluidized bed reactor.

[0018] In some embodiments, the pre-precursor mixture can include pre-lithium precursor particles and transition metal-containing particles, which can include Ni, Co, NiO, CoO, and MnO.

[0019] In some embodiments, the reserve lithium precursor particles can include at least one of lithium hydroxide, lithium oxide, or lithium carbonate.

[0020] In some embodiments, recovering the lithium precursor can include washing the preliminary lithium precursor particles with water to collect the lithium hydroxide. [Effects of the Invention]

[0021] According to the above-described exemplary embodiment, a lithium precursor can be recovered from the positive electrode active material of a used lithium secondary battery through a fluidization process in which an oxygen-containing gas is introduced to decompose and combust the binder and conductive material, and a hydrogen reduction process. This minimizes particle aggregation caused by side reactions (e.g., lithium over-reduction) due to the heat of decomposition generated by the binder decomposition and the heat of combustion generated by the conductive material combustion.

[0022] In addition, the conductive material can be combusted by reacting with oxygen contained in the oxygen-containing gas, preventing the generation of carbonaceous by-products (e.g., lithium carbonate) derived from the conductive material. This increases the recovery rate of the desired lithium precursor and eliminates the need for a subsequent process to remove the by-products, thereby improving the economic efficiency and long-term operability of the process. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic flow chart illustrating a method for recovering active metals from a lithium secondary battery according to an exemplary embodiment. [Figure 2]FIG. 2 is a schematic flow chart illustrating a method for recovering active metals from a lithium secondary battery according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0024] An embodiment of the present invention provides a method for recovering active metals with high purity and high yield from the positive electrodes of used lithium secondary batteries.

[0025] Hereinafter, the present invention will be described in detail with reference to the preferred embodiments. However, since the present invention can be modified in various ways and can have various forms, specific embodiments will be illustrated in the drawings and described in detail herein. However, it should be understood that the present invention is not limited to the specific disclosed form, and that all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention are included. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention pertains. Terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted in an idealized or overly formal sense unless expressly defined in this application.

[0026] As used herein, the term "precursor" is used to refer collectively to a compound containing a specific metal to provide the specific metal contained in the electrode active material.

[0027] FIG. 1 is a schematic flow chart illustrating a method for recovering active metals from a lithium secondary battery according to an exemplary embodiment.

[0028] Referring to FIG. 1, the waste positive electrodes of lithium secondary batteries are spare Cathode active material mixture 50 (For example, a waste positive electrode active material mixture) can be prepared (for example, step S10).

[0029] The lithium secondary battery may include an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and the positive electrode and the negative electrode may include a positive electrode active material layer and a negative electrode active material layer coated on a positive electrode current collector and a negative electrode current collector, respectively.

[0030] For example, the positive electrode active material contained in the positive electrode active material layer can include an oxide containing lithium and a transition metal.

[0031] In some embodiments, the positive electrode active material can include a compound represented by Formula 1:

[0032] [Chemical formula 1] Li x M1 a M2 b M3 c O y

[0033] In Chemical Formula 1, M1, M2, and M3 may be a transition metal 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≦2.02、0<a<1、0<b<1、0<c<1、0<a+b+c≦1であってもよい。

[0034] In some embodiments, the positive electrode active material may be an NCM-based lithium oxide containing nickel, cobalt, and manganese.

[0035] The positive electrode can be separated from the used lithium secondary battery to recover the used positive electrode. The used positive electrode includes a positive electrode current collector (e.g., aluminum (Al)) and a positive electrode active material layer, as described above. The positive electrode active material layer may include a conductive material and a binder in addition to the positive electrode active material.

[0036] The conductive material may include, for example, a carbon-based material such as graphite, carbon black, graphene, carbon nanotubes, etc. The binder may include, for example, a resin material such as vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, etc.

[0037] According to an exemplary embodiment, the recovered waste positive electrodes are crushed to produce a spare Cathode active material mixture 50 This allows the above spare Cathode active material mixture 50 can be produced in powder form. spare Cathode active material mixture 50 As described above, the powder contains a lithium-transition metal oxide, for example, an NCM-based lithium oxide powder (e.g., Li(NCM)O2), a binder powder, and a conductive material powder.

[0038] As used herein, the term " spare The term "positive electrode active material mixture" may refer to raw materials that are input into a process of fluidizing the waste positive electrode with an oxygen-containing gas, which will be described later, after the positive electrode current collector has been substantially removed from the waste positive electrode. spare The cathode active material mixture 50 can include cathode active material particles, such as the NCM-based lithium oxide. spare The positive electrode active material mixture 50 may partially contain components derived from the binder 70 or the conductive material 80 .

[0039] In some embodiments, spare The average particle size (D50) of the positive electrode active material mixture 50 may be 5 to 100 μm. spareThe lithium-transition metal oxide to be recovered, such as Li(NCM)O 2 , can be easily separated from the positive electrode current collector, binder 70, and conductive material 80 contained in the positive electrode active material mixture 50.

[0040] In some embodiments, the recovered positive electrode may be heat-treated before the pulverization treatment, which can promote detachment of the positive electrode current collector during the pulverization treatment and at least partially remove the binder 70 and the conductive material 80. The temperature for the heat treatment may be, for example, about 100 to 500°C, preferably about 350 to 450°C.

[0041] In some embodiments, spare The positive electrode active material mixture 50 can be obtained by immersing the recovered positive electrode in an organic solvent. For example, the recovered positive electrode is immersed in an organic solvent to separate and remove the positive electrode current collector, and then centrifuged to separate the positive electrode active material particles, the binder, and the conductive material. spare The positive electrode active material mixture 50 can be selectively extracted.

[0042] By the above-described process, the positive electrode current collector components such as aluminum were substantially completely separated and removed, and the content of carbonaceous components derived from the binder 70 and / or the conductive material 80 was reduced. spare A positive electrode active material mixture 50 can be obtained.

[0043] The aforementioned spare The positive electrode active material mixture 50 is fluidized in the fluidized bed reactor 100 by injecting an oxygen-containing gas. , forming a positive electrode active material mixture 90 This can be done (for example, step S20).

[0044] As used herein, the term "fluidized bed reactor" refers to a reactor in which a fluid (gas or liquid) is passed through the injected preliminary positive electrode active material mixture 50, spare It may refer to a reactor that fluidizes the positive electrode active material mixture 50. For example, the fluid may be an oxygen-containing gas, which will be described later.

[0045] In an exemplary embodiment, a positive electrode active material mixture 50 including positive electrode active material particles 60 , a binder 70 and a conductive material 80 can be injected into the interior of the fluidized bed reactor 100 .

[0046] For example, preliminary positive electrode active material mixture 50 can be injected into fluidized bed reactor 100 through upper inlet 108 a located at the top of fluidized bed reactor 100 .

[0047] In an exemplary embodiment, an oxygen-containing gas may be injected into the interior of the fluidized bed reactor 100 .

[0048] The oxygen-containing gas may be injected into the reactor body 110 of the fluidized bed reactor 100 through a gas inlet 104 located at the bottom of the fluidized bed reactor 100 .

[0049] In an exemplary embodiment, the oxygen-containing gas may be a gas mixture including oxygen (O) and a non-reactive gas, which may include at least one selected from the group consisting of helium (He), nitrogen (N), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).

[0050] For example, the volume ratio of oxygen may be 10 to 30 vol % and the volume ratio of the non-reactive gas may be 70 to 90 vol % relative to the total volume of the oxygen-containing gas.

[0051] By injecting the oxygen-containing gas into the fluidized bed reactor 100, the preliminary positive electrode active material mixture 50 injected into the fluidized bed reactor 100 can be fluidized.

[0052] For example, the fluidized bed reactor 100 may include an expanded tube section 120 at its upper portion, the expanded tube section 120 having a diameter larger than that of the reactor body 110. The expanded tube section 120 has a diameter larger than that of the reactor body 110, and can reduce the flow rate of the oxygen-containing gas that is injected into the lower part of the fluidized bed reactor 100 and ascends. This increases the injection rate of the oxygen-containing gas, effectively preventing a decrease in recovery rate due to leakage of the preliminary cathode active material mixture 50 out of the reactor body 110.

[0053] Illustrative Embodiments According to the preliminary Cathode active material mixture 50 The step of fluidizing the binder and the conductive material with the oxygen-containing gas may further include heat treating the binder and the conductive material in the fluidized bed reactor to decompose or combust them. For example, the conductive material 80 may be removed by reacting with oxygen contained in the oxygen-containing gas and combusting it to produce carbon monoxide (CO) or carbon dioxide (CO).

[0054] This can reduce the generation of carbon-derived by-products (e.g., lithium carbonate) in the hydrogen reduction process described below. In this case, for example, the lithium hydroxide content of the preliminary lithium precursor can be increased, thereby increasing the recovery rate of the lithium precursor. For example, a subsequent process for removing the by-products is not required, thereby improving process economy and long-term operability.

[0055] For example, the decomposition rate of the binder 70 by the heat treatment may be 95% or more, and preferably 99% or more.

[0056] For example, the burn rate of the conductive material 80 due to the heat treatment may be 95% or more, and preferably 99% or more.

[0057] In some embodiments, the binder 70 and conductive material 80 can be simultaneously decomposed or combusted by the fluidization heat treatment described above.

[0058] In an exemplary embodiment, the temperature of the heat treatment is about 100 to 600°C. the law of nature,More preferably, it may be about 400 to 600° C. In this case, the fluidized bed reactor 100 may include a heating means capable of adjusting the temperature inside the reactor main body 110.

[0059] In this temperature range, for example, decomposition of the binder 70 and combustion reaction of the conductive material 80 can be initiated.

[0060] For example, when the temperature of the heat treatment satisfies the above range, the residual ratio of the binder 70 and the conductive material 80 in the positive electrode active material mixture 90 can be significantly reduced.

[0061] For example, if binder 70 remains in positive electrode active material mixture 90, over-reduction may occur during the hydrogen reduction step described below, for example, due to the heat generated by decomposition of binder 70, causing particles to aggregate and reducing the recovery rate of the lithium precursor.

[0062] For example, if conductive material 80 remains in positive electrode active material mixture 90, the content of carbon-derived by-products, such as lithium carbonate (Li2CO3), may increase during the hydrogen reduction process described below, which may reduce process stability and the recovery rate of the lithium precursor. In this case, a subsequent process (e.g., a filtration process) to remove the carbon-derived by-products may be required, which may reduce the economic efficiency and process stability of the method for recovering active metals for lithium secondary batteries.

[0063] In some embodiments, if the heat treatment temperature exceeds 600°C, lithium carbonate may be formed due to a side reaction (e.g., over-reduction by carbon) of the positive electrode active material particles 60, causing the particles to aggregate. In this case, the reduction rate of the positive electrode active material particles may decrease, and the recovery rate of the lithium precursor may decrease.

[0064] In an exemplary embodiment, spare Cathode active material mixture 50 The step of fluidizing with an oxygen-containing gas can include ramping the temperature from below 50° C. to a target temperature in the range of 400-600° C. for 1-2 hours.

[0065] In this case, for example, the method may further include heat treatment at the target temperature for 2 to 5 hours.

[0066] In some exemplary embodiments, the heat treatment decomposes binder 70 and burns conductive material 80. The temperature rise in fluidized bed reactor 100 due to the decomposition of binder 70 and the combustion of conductive material 80 may be about 50° C. or less, and preferably about 30° C. or less. The lower limit of the temperature rise is more advantageous, but may be about 1° C. or more.

[0067] Since the decomposition of the binder 70 and the combustion of the conductive material 80 can be carried out inside the fluidized bed reactor 100, the heat of decomposition of the binder 70 and the heat of combustion of the conductive material 80 can be spare The heat generated by the decomposition and combustion can be minimized by dispersing the heat throughout the positive electrode active material mixture 50. spare This suppresses the melting and aggregation of particles due to side reactions of the positive electrode active material mixture 50 (for example, over-reduction reactions due to the heat of decomposition and combustion), and increases the reduction rate in the hydrogen reduction step described below.

[0068] In some embodiments , positive The average diameter of the cathode active material mixture 90 may be about 1 to 100 μm. Within this range, the contact area between the reducing gas and the cathode active material mixture 90 in the reduction step described below increases, and the recovery rate of the lithium precursor can be increased.

[0069] In some exemplary embodiments , positive The particle size distribution of the electrode active material mixture 90 may be greater than about 0 μm and equal to or less than about 500 μm.

[0070] When the particle size distribution range is satisfied, for example, the cathode active material mixture 90 can be reduced uniformly throughout. RecordingThe lithium precursor is uniformly dispersed throughout the electrode active material mixture 90, minimizing the side reaction caused by heat during the reduction reaction, thereby improving the recovery rate of the lithium precursor.

[0071] In the comparative example, the decomposition and combustion of the binder 70 and the conductive material 80 by heat treatment can be carried out in a non-fluidized reactor. In the case of the non-fluidized reactor, the decomposition heat of the binder 70 and the combustion heat of the conductive material 80 are not dispersed throughout the reactor, and the side reactions described above may occur due to the temperature rise caused by the uneven distribution of the decomposition heat and combustion heat. spare The particles contained in the positive electrode active material mixture 50 may melt and agglomerate.

[0072] in this case, spare The diameter of the particles contained in the positive electrode active material mixture 50 may increase to 1 cm or more. spare If the positive electrode active material mixture 50 cannot be refluidized, the process efficiency of the reduction reaction described below may decrease, and the recovery rate of the lithium precursor may decrease.

[0073] In the comparative example, spare The cathode active material mixture 50 may be prepared by heat treatment in a combustion furnace other than the fluidized bed reactor 100. However, in this case, agglomeration may occur between metal (e.g., Ni and Co) particles contained in the cathode active material mixture 90. If the agglomerated particles are added to perform the reduction process described below, the reduction rate may decrease, resulting in a decrease in the recovery rate of the lithium precursor.

[0074] In an exemplary embodiment, the film formed by the step S20 Tadashi The electrode active material mixture 90 can be collected through the outlet 108b of the fluidized bed reactor 100. Tadashi The electrode active material mixture 90 can be injected into the hydrogen reduction step described below.

[0075] In an exemplary embodiment , positiveThe electrode active material mixture 90 may be subjected to a reduction treatment to form a preliminary precursor mixture containing preliminary lithium precursor particles and transition metal-containing particles (for example, step S30).

[0076] For example, the transition metal-containing particles can include Ni, Co, NiO, CoO, and MnO.

[0077] For example, the preliminary lithium precursor particles can include at least one of lithium hydroxide (LiOH), lithium oxide (LiO), and lithium carbonate (LiCO). From the viewpoint of the charge / discharge characteristics, life characteristics, high-temperature stability, etc. of the lithium secondary battery, the lithium precursor can include lithium hydroxide.

[0078] In an exemplary embodiment, spare Cathode active material mixture 50 The steps of fluidizing the precursor mixture with an oxygen-containing gas and forming the pre-precursor mixture can be performed sequentially in situ in the fluidized bed reactor 100. Recording Since the formation of the electrode active material mixture 90 and the hydrogen reduction reaction are carried out in the same reactor, , positive During the process of transporting the electrode active material mixture 90, Positive This can prevent the problem of loss of the electrode active material mixture 90. This can further improve the recovery rate of the lithium precursor.

[0079] Positive The electrode active material mixture 90 may be reduced by a reducing gas injected into the reactor body 110 through a gas inlet 104 located at the bottom of the fluidized bed reactor 100 to form a pre-precursor mixture.

[0080] The reducing gas can be a mixed gas of hydrogen and the non-reactive gas, and the volume ratio of hydrogen to the total volume of the mixed gas may be 5 to 40%, and the volume ratio of the non-reactive gas may be 60 to 95%.

[0081] The hydrogen reduction reaction can be carried out at a temperature of about 300 to 700°C, preferably 400 to 500°C. , positive The yield of the pre-precursor mixture produced from the electrode active material mixture 90 can be improved.

[0082] In some embodiments, the additional temperature increase in the fluidized bed reactor 100 due to the hydrogen reduction reaction is about 10°C. below The lower limit of the additional temperature increase is not particularly limited, but may be about 1°C or more.

[0083] for example , positive The electrode active material mixture 90 may be substantially free of a binder, and in this case, it is possible to prevent a temperature rise inside the fluidized bed reactor 100 due to the decomposition heat of the binder. Ru Prevents over-reduction of the electrode active material mixture 90 , positive It is possible to minimize particle aggregation due to bonding between nickel (Ni) and cobalt (Co) contained in the electrode active material mixture 90. , positive The pre-precursor mixture formed by reducing the electrode active material mixture 90 can be more easily collected in a slurry state.

[0084] for example , positive The electrode active material mixture 90 may be substantially free of the conductive material 80, which can reduce the content of by-products (e.g., lithium carbonate) formed by the reduction reaction with carbon. In this case, the content of lithium hydroxide, which has a high solubility in the leaching solution, in the preliminary precursor mixture increases, which can increase the recovery rate of the lithium precursor in the lithium precursor recovery step described below.

[0085] In some embodiments , positive Since the electrode active material mixture 90 does not substantially contain the conductive material 80, the reaction heat generated by the reduction reaction of carbon can be reduced, and in this case, the temperature rise due to the reduction reaction can be partially suppressed.

[0086] According to an exemplary embodiment, before collecting the formed pre-precursor mixture, water and a non-reactive gas may be injected into the fluidized bed reactor 100 to turn the pre-precursor mixture into a slurry state. In this case, the agglomerated pre-precursor mixture can be de-agglomerated by the hydrogen reduction reaction, and the pre-precursor mixture can be more easily collected in a slurry state.

[0087] For example, water may be injected into the fluidized bed reactor 100 through an upper inlet 108a of the fluidized bed reactor 100, and the non-reactive gas may be injected into the fluidized bed reactor 100 through a gas inlet 104 located at the bottom of the fluidized bed reactor 100.

[0088] For example, the pre-precursor mixture in a slurry state can be collected through the outlet 108b located at the bottom of the fluidized bed reactor 100. The collected pre-precursor mixture can be injected into the lithium precursor collection step described below.

[0089] According to some embodiments, the formed pre-precursor mixture may not be separately collected from the fluidized bed reactor 100, but may be located inside the fluidized bed reactor 100, and the lithium precursor collection process described below may be performed inside the fluidized bed reactor 100. In this case, it is possible to prevent a problem in which a portion of the pre-precursor mixture is lost during the process of transporting the formed pre-precursor mixture, thereby further improving the recovery rate of the lithium precursor.

[0090] According to an exemplary embodiment, the lithium precursor can be collected from the pre-precursor mixture (eg, step S40).

[0091] For example, the pre-precursor mixture formed from the hydrogen reduction reaction described above can be reacted with the leachate to collect the lithium precursor.

[0092] For example, the pre-precursor mixture may react with the leachate to form a solution in which the lithium precursor is dissolved and a precipitate in which the transition metal precursor is precipitated.

[0093] For example, lithium oxide may react with the leachate to form lithium hydroxide, which may dissolve in the leachate.

[0094] In some embodiments, the leachate may include water, in which case the pre-precursor mixture may be washed with water to react with the water and form a lithium precursor in which lithium hydroxide is dissolved in water.

[0095] In some exemplary embodiments, the leachate may further include dimethyl carbonate or diethyl carbonate.

[0096] For example, dimethyl carbonate or diethyl carbonate can promote the reaction of the pre-precursor mixture with water, thereby improving the separation efficiency of the lithium precursor.

[0097] In some embodiments, the precipitate can include a slurry containing the pre-precursor mixture.

[0098] For example, the slurry may be formed by dispersing transition metal-containing particles that are insoluble in the leachate in the leachate, and the lithium precursor may be collected by separating the slurry from the solution containing the dissolved lithium precursor.

[0099] In one embodiment, the precipitated transition metal-containing particles can be collected to form a transition metal precursor, for example, the transition metal-containing particles can be reacted with an acid solution to form a transition metal precursor.

[0100] In an exemplary embodiment, the acid solution may be sulfuric acid, and the transition metal precursor may include a transition metal sulfate, such as NiSO4, MnSO4, or CoSO4.

[0101] The reaction between the pre-precursor mixture and the leachate is , positive This can be done in the fluidized bed reactor 100 where the electrode active material mixture 90 is formed. , positive The step of forming the electrode active material mixture 90, the step of reducing with hydrogen, or the step of collecting each product after the step of forming the preliminary precursor mixture is not required, and the decrease in the recovery rate of the lithium precursor that may occur during the transport of each product can be minimized.

[0102] FIG. 2 is a schematic flow chart illustrating a method for recovering active metals from a lithium secondary battery according to some embodiments.

[0103] Referring to FIG. 2, in some embodiments , positive The electrode active material mixture 90 can be collected through a gas inlet 104 located at the bottom of the fluidized bed reactor 100. Tadashi The electrode active material mixture 90 is fed into a separate reduction reactor 200 where the aforementioned reduction process can be carried out.

[0104] for example , positive The electrode active material mixture 90 may be injected into the reduction reactor 200 through an upper inlet 208a located at the top of the reduction reactor 200, and the hydrogen may be injected into the reactor body 210 through a gas inlet 204 located at the bottom of the reduction reactor 200.

[0105] For example, an expanded tube portion 220 may be located at the top of the reduction reactor 200. The expanded tube portion 220 is configured to expand the above-mentioned fuel injected from the bottom of the reduction reactor 200. Reducibility The gas flow rate is reduced, and the Ru In the process of refluidizing the electrode active material mixture 90 , positiveThis can effectively prevent the electrode active material mixture 90 from leaking out.

[0106] In some embodiments, before collecting the pre-precursor mixture, water and a non-reactive gas may be injected into the reduction reactor 200 to form a slurry of the pre-precursor mixture, whereby the reduction reaction can deflocculate the agglomerated pre-precursor mixture, making it easier to collect the slurry of the pre-precursor mixture.

[0107] For example, water can be injected into the reduction reactor 200 through the upper inlet 208a of the reduction reactor 200, and the non-reactive gas can be injected into the reduction reactor 200 through the gas inlet 204 located at the bottom of the reduction reactor 200.

[0108] For example, the slurry-state pre-precursor mixture may be collected through the outlet 208b located at the bottom of the reduction reactor 200. The collected pre-precursor mixture may be injected into the lithium precursor collecting process described above.

[0109] According to one embodiment, the formed pre-precursor mixture is not separately collected from the reduction reactor 200, but is located inside the reduction reactor 200, and the aforementioned lithium precursor collection process may be performed inside the reduction reactor 200.

[0110] In this case, the step of collecting each product after the step of forming the preliminary precursor mixture is not necessary, and a decrease in the recovery rate of the lithium precursor that may occur during the process of transporting each product can be prevented.

[0111] Specific examples are presented below to aid in understanding the present invention, but these examples are merely illustrative of the present invention 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 examples within the scope and technical spirit of the present invention, and it is natural that these changes and modifications also fall within the scope of the appended claims.

[0112] Example 1 1 kg of cathode material separated from waste lithium secondary batteries is cut into small units and pulverized by milling to produce a composite material containing Li-Ni-Co-Mn oxide, binder (polyvinylidene fluoride, PVDF), and conductive material (carbon black). spare The positive electrode active material mixture was collected (step S10).

[0113] collected spare 0.2 kg of the positive electrode active material mixture was poured into a fluidized bed reactor, and a mixed gas of 20 vol% oxygen / 80 vol% nitrogen was poured into the bottom of the fluidized bed reactor. spare The positive electrode active material mixture was fluidized. The internal temperature of the fluidized bed reactor was increased from 20°C to 500°C, and then the temperature was maintained at 500°C for 3 hours. spare The binder contained in the positive electrode active material mixture is thermally decomposed, and the conductive material is burned and removed. to form a positive electrode active material mixture. (S20 process).

[0114] A 20 vol% hydrogen / 80 vol% nitrogen mixed gas was injected through a gas inlet located at the bottom of the fluidized bed reactor for 4 hours to fluidize the fluidized bed reactor and react with the hydrogen gas to form a pre-precursor mixture containing lithium hydroxide, while the internal temperature of the fluidized bed reactor was maintained at 460°C (step S30).

[0115] Water and nitrogen gas were added to the pre-precursor mixture to form a slurry of the pre-precursor mixture, which was then collected and washed with water to obtain an aqueous lithium precursor solution (step S40).

[0116] Example 2 An aqueous lithium precursor solution was obtained in the same manner as in Example 1, except that the heat treatment temperature was set to 650° C. in the heat treatment step of the preliminary positive electrode active material mixture for producing the positive electrode active material mixture.

[0117] Comparative Example 1 An aqueous lithium precursor solution was obtained in the same manner as in Example 1, except that the heat treatment step of the preliminary positive electrode active material mixture was not carried out during the production of the positive electrode active material mixture.

[0118] Comparative Example 2 A lithium precursor aqueous solution was obtained in the same manner as in Example 1, except that the heat treatment step of the preliminary cathode active material mixture for producing the cathode active material mixture was performed using a separate combustion furnace instead of a fluidized bed reactor, and the resulting cathode active material mixture was then introduced into a fluidized bed reactor to perform the hydrogen reduction reaction.

[0119] Comparative Example 3 A lithium precursor aqueous solution was obtained in the same manner as in Example 1, except that in the heat treatment step of the preliminary positive electrode active material mixture for producing the positive electrode active material mixture, the mixture was fluidized using only nitrogen gas (non-reactive gas) that did not contain oxygen gas as the oxygen-containing gas.

[0120] Experimental example (1) Measurement of temperature change deviation The temperature inside the fluidized bed reactor was measured and the deviation between the minimum and maximum temperature values ​​during the reaction was calculated.

[0121] (2) Measurement of average diameter Positive The diameter of the electrode active material mixture particles was measured using a Mastersizer 3000, a laser light diffraction / scattering type device manufactured by Malvern.

[0122] (3) Measurement of particle size distribution range Positive The electrode active material mixture particles were thoroughly dispersed in an aqueous medium by ultrasonic treatment, and the dispersion was measured using a Mastersizer 3000, a laser light diffraction and scattering type device manufactured by Malvern.

[0123] (4) Measurement of binder removal rate Relative to the mass of the binder contained in the positive electrode active material mixture , positive The binder removal rate was measured by measuring the mass of the binder contained in the electrode active material mixture.

[0124] (5) Measurement of conductive material removal rate Relative to the mass of conductive material contained in the positive electrode active material mixture , positive The conductive material removal rate was measured by measuring the mass of the conductive material contained in the electrode active material mixture.

[0125] (6) Evaluation of the generation of lithium carbonate (Li2CO3) Water was added to the obtained slurry-state aqueous solution of the pre-precursor mixture by 19 times (by weight) and stirred, and then the weight of carbonate ions dissolved in the water was measured to evaluate whether or not they were generated.

[0126] (7) Measurement of lithium precursor recovery rate Water was added to the obtained aqueous solution of the preliminary precursor mixture in a slurry state in an amount of 19 times (by weight) and stirred, and then the lithium precursor in which lithium hydroxide and lithium carbonate were dissolved in water was recovered. The weight of lithium dissolved in water relative to the weight of lithium in the initial positive electrode active material sample was measured to calculate the recovery rate of the lithium precursor.

[0127] (8) Measurement of selectivity of lithium carbonate (Li2CO3) Water was added to the obtained slurry-state aqueous solution of the preliminary precursor mixture by 19 times (by weight) and stirred. The weight of carbonate ions dissolved in the water was measured, and the proportion of lithium carbonate produced in the recovered lithium precursor was calculated.

[0128] Regarding the above-mentioned examples and comparative examples, spare The maximum deviation of the internal temperature change of the fluidized bed reactor measured during the preparation process of the positive electrode active material mixture, the average diameter of the formed positive electrode active material mixture particles, particle size distribution, binder removal rate, conductive material removal rate, whether or not a by-product (LiCO) was generated, and the selectivity for lithium carbonate are shown in Table 1.

[0129] In addition, the maximum deviation value of the temperature change inside the reduction reactor in the reduction step and the lithium after washing with water precursor The recovery rates were determined and are shown in Table 1.

[0130] [Table 1]

[0131] Referring to Table 1, Example 1, in which a fluidization heat treatment process was performed to remove the binder and conductive material contained in the preliminary cathode active material mixture, achieved an excellent lithium precursor recovery rate and reduced the generation of by-products such as lithium carbonate during the reduction process.

[0132] Also, spare In Example 2, in which the heat treatment step for preparing the positive electrode active material mixture was performed at 650°C, a by-product, lithium carbonate, was generated due to a side reaction at high temperature, which resulted in a decrease in the recovery rate of the lithium precursor in the lithium precursor recovery step.

[0133] In contrast, in Comparative Example 1, which did not undergo a thermal decomposition process, side reactions (e.g., over-reduction of the positive electrode active material mixture) occurred due to the heat of decomposition of the binder during the hydrogen reduction process, causing the produced metal active material mixture to aggregate. As a result, the over-reduced metal active material mixture could not be easily transformed into a slurry state. This resulted in a decrease in the recovery rate of the lithium precursor.

[0134] In Comparative Example 2, in which a non-fluidization heat treatment step was performed in a separate combustion furnace before the reduction step, the cathode active material mixture formed by a side reaction (e.g., over-reduction) in the pyrolysis step aggregated with each other to form aggregates with a diameter of 5 cm. As a result, the cathode active material mixture could not be easily fluidized, and the reduction rate of the hydrogen reduction step decreased, resulting in a decrease in the recovery rate of the lithium precursor.

[0135] oxygen-containing gas Instead ofIn Comparative Example 3, in which only a non-reactive gas (N2 gas) not containing oxygen gas was injected, the conductive material was not removed and lithium carbonate, a by-product of the hydrogen reduction process, was generated. As a result, the lithium hydroxide content in the pre-precursor mixture was low, and the recovery rate of the lithium precursor was slightly reduced. Furthermore, because lithium carbonate does not dissolve in the leaching solution, a separate subsequent filtration process was required, which reduced the process economy and long-term operability.

[0136] In Comparative Examples 1 and 2, the conductive material was not removed, and lithium carbonate was generated as a by-product. As a result, the recovery rate of the lithium precursor decreased, and the process economy and long-term operability decreased, as in Comparative Example 3.

Claims

1. preparing a spare positive electrode active material mixture from the positive electrodes of waste lithium secondary batteries; fluidizing the preliminary cathode active material mixture in a fluidized bed reactor with an oxygen-containing gas to form a cathode active material mixture; injecting a reducing gas into the fluidized bed reactor to form a pre-precursor mixture from the cathode active material mixture; recovering a lithium precursor from the pre-precursor mixture; the step of fluidizing the preliminary positive electrode active material mixture with the oxygen-containing gas and the step of forming the preliminary precursor mixture are performed in situ consecutively in the fluidized bed reactor.

2. the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector and including a binder, a conductive material, and a positive electrode active material; the step of preparing the preliminary positive electrode active material mixture includes removing the positive electrode current collector from the positive electrode; The method for recovering active metals from a lithium secondary battery according to claim 1 , wherein the preliminary positive electrode active material mixture comprises the binder, the conductive material, and the positive electrode active material.

3. 3. The method for recovering active metals from a lithium secondary battery according to claim 2, wherein the step of fluidizing the preliminary positive electrode active material mixture with the oxygen-containing gas includes decomposing or combusting the binder and the conductive material in the fluidized bed reactor.

4. The oxygen-containing gas is oxygen (O ２ ) and a non-reactive gas, The non-reactive gases include helium (He), nitrogen (N ２ 2. The method for recovering active metals from a lithium secondary battery according to claim 1, wherein the active metal comprises at least one selected from the group consisting of neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).

5. 5. The method for recovering active metals from a lithium secondary battery according to claim 4, wherein a volume ratio of oxygen to a total volume of the oxygen-containing gas is 10 to 30 vol %, and a volume ratio of the non-reactive gas is 70 to 90 vol %.

6. 2. The method for recovering active metals from a lithium secondary battery according to claim 1, wherein the step of fluidizing the preliminary positive electrode active material mixture with the oxygen-containing gas is performed at a temperature of 100 to 600°C.

7. 7. The method for recovering active metals from a lithium secondary battery according to claim 6, wherein the step of fluidizing the preliminary positive electrode active material mixture with the oxygen-containing gas comprises increasing the temperature from a temperature below 50°C to a target temperature in the range of 400 to 600°C for 1 to 2 hours.

8. 8. The method for recovering active metals from a lithium secondary battery according to claim 7, wherein the step of fluidizing the preliminary positive electrode active material mixture with the oxygen-containing gas includes heat-treating the mixture at the target temperature for 2 to 5 hours.

9. 2. The method for recovering active metals from a lithium secondary battery according to claim 1, wherein the reducing gas contains hydrogen.

10. 10. The method for recovering active metals of a lithium secondary battery according to claim 9, wherein the step of forming the preliminary precursor mixture is carried out at a temperature in the range of 400 to 500°C.

11. the pre-precursor mixture comprises pre-lithium precursor particles and transition metal-containing particles; 10. The method for recovering active metals from a lithium secondary battery according to claim 9, wherein the transition metal-containing particles contain Ni, Co, NiO, CoO, and MnO.

12. 12. The method for recovering active metals of a lithium secondary battery according to claim 11, wherein the preliminary lithium precursor particles include at least one of lithium hydroxide, lithium oxide, or lithium carbonate.

13. 13. The method for recovering an active metal of a lithium secondary battery according to claim 12, wherein the step of recovering the lithium precursor comprises a step of washing the preliminary lithium precursor particles with water to collect the lithium hydroxide.

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