Method of recovering lithium precursor, method of preparing positive electrode active material including the lithium precursor, and lithium secondary battery including the positive electrode active material

Abstract

To provide a method in which a waste solution generated in a washing process of a positive electrode active material is used to recover a lithium precursor from waste related to lithium secondary batteries.SOLUTION: The present invention relates to a method of recovering a lithium precursor, a method of preparing a positive electrode active material including the lithium precursor, and a lithium secondary battery including the positive electrode active material. The method of recovering a lithium precursor according to the present invention includes: preparing a first solution that contains lithium ions and transition metal ions; preparing a second solution by mixing the first solution and a first basic reagent; preparing a third solution by extracting a transition metal from the second solution; preparing a fourth solution by mixing the third solution and a second basic reagent; and extracting a lithium precursor from the fourth solution. The first basic reagent is prepared using a waste solution generated in a washing process of a positive electrode active material.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a method for recovering lithium precursors from waste materials related to lithium secondary batteries, and more particularly to a method for recovering lithium precursors from waste materials using waste liquid generated in a process for washing a positive electrode active material with water. [Background technology]

[0002] Lithium secondary batteries are used as energy storage and supply sources in a variety of fields. They are widely used as energy storage and supply sources not only in portable devices such as mobile phones, tablet PCs, wearable devices, laptops, digital cameras, and power tools, but also in transportation such as hybrid cars, electric cars, and electric scooters. Recently, their applications have expanded to future industrial fields such as drones, robots, and urban air mobility (UAM).

[0003] In particular, the recent rise in concern about climate change and environmental friendliness has led to significant growth in the electric vehicle market, which has led to a rapid increase in the use of lithium secondary batteries. However, because the main raw materials needed to manufacture lithium secondary batteries must be obtained from natural resources, the raw material extraction process inevitably causes environmental destruction and pollution. Therefore, there is an urgent need to develop raw material recycling technology.

[0004] Accordingly, methods for recovering valuable metals, such as transition metal precursors and lithium precursors, from lithium secondary battery-related waste, such as discarded lithium secondary batteries, waste generated in the lithium secondary battery manufacturing process, and wastewater generated in the positive electrode active material washing process, are attracting attention. The recovered valuable metals can be recycled for the manufacture of lithium secondary batteries, and active research and development is being actively conducted on recycling methods that are more environmentally friendly, less costly, and capable of recovering valuable metals in high concentrations.

[0005] Various methods for recovering valuable metals from discarded lithium secondary batteries or waste generated during the lithium secondary battery manufacturing process have been implemented. However, conventional methods have a problem in that they require the use of a large amount of basic solution during the recovery process. Since by-products generated from the basic solution cause environmental pollution, it is necessary to prepare an alternative that can replace the basic solution.

[0006] Various methods for recovering lithium precursors from wastewater generated during the washing process of a positive electrode active material have been implemented. The wastewater generated during the washing process of a positive electrode active material contains a large amount of lithium. However, conventional methods have the problem of requiring a separate process to recover the lithium precursor from the wastewater. Furthermore, since there is no process with a 100% recovery rate, creating a separate process itself inevitably results in lithium loss. Therefore, an improved method for recovering lithium precursors is needed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent No. 10-1839460 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention provides a method for recovering lithium precursors from lithium secondary battery waste using wastewater generated in a process for washing cathode active materials with water. More specifically, the present invention aims to solve the environmental problems caused by the use of a large amount of basic solution, the economic problems caused by the production process requiring a single process, and the efficiency problems caused by lithium loss.

[0009] Another object of the present invention is to provide a method for manufacturing a cathode active material including the lithium precursor recovered through the recovery method, and a lithium secondary battery including the cathode active material. [Means for solving the problem]

[0010] A method for recovering a lithium precursor according to the present invention may include preparing a first solution containing lithium ions and transition metal ions, mixing the first solution with a first basic reagent to prepare a second solution, extracting the transition metal from the second solution to prepare a third solution, mixing the third solution with a second basic reagent to prepare a fourth solution, and extracting the lithium precursor from the fourth solution. The first basic reagent may be prepared using wastewater generated in a water washing process of a positive electrode active material.

[0011] A method for preparing a positive electrode active material according to another aspect of the present invention may include mixing a transition metal precursor and the lithium precursor recovered by the above-described recovery method, followed by calcining the mixture, and washing the calcined mixture with water.

[0012] A lithium secondary battery according to another aspect of the present invention may include a positive electrode active material prepared by the above-described method for preparing a positive electrode active material. [Effects of the Invention]

[0013] The method for recovering a lithium precursor according to the present invention can prepare a basic reagent from wastewater generated in a water washing process of a positive electrode active material and then introduce the basic reagent into a lithium precursor recovery process. Therefore, the amount of basic solution used in the lithium precursor recovery process can be reduced, lithium in the wastewater can be easily recovered without a separate process, and a lithium precursor with higher purity can be recovered.

[0014] Furthermore, by preparing the basic reagent so that it contains lithium ions at a high concentration and does not contain impurity ions, an additional step of separating and removing undesired recovered materials derived from impurity ions can be omitted. [Brief explanation of the drawings]

[0015] [Figure 1]1 is a conceptual diagram illustrating a lithium secondary battery according to an embodiment of the present invention; [Figure 2] 1 is a schematic diagram illustrating a lithium secondary battery according to an embodiment, the lithium secondary battery having a cylindrical battery shape. [Figure 3] 1 is a cross-sectional view showing a lithium secondary battery according to an embodiment. [Figure 4] 1 is a schematic diagram illustrating a lithium secondary battery according to an embodiment, the battery having a prismatic shape. [Figure 5] 1 is a schematic diagram illustrating a lithium secondary battery according to an embodiment, in the form of a pouch-shaped battery. [Figure 6] FIG. 2 is a flow chart illustrating the preparation of a first basic reagent according to the present invention. [Figure 7] FIG. 2 is a flow chart illustrating the preparation of a first solution according to the present invention. [Figure 8] FIG. 2 is a flow chart illustrating the preparation of a second solution according to the present invention. [Figure 9] FIG. 2 is a flow chart illustrating the preparation of a third solution according to the present invention. [Figure 10] FIG. 4 is a flow chart illustrating the preparation of a fourth solution according to the present invention. [Figure 11] 1 is a flow chart illustrating a method for recovering a lithium precursor according to the present invention. [Figure 12] 1 is a graph showing the results of X-ray diffraction (XRD) analysis of lithium carbonate (Li2CO3) according to Example 6-1 and Comparative Example 4. [Figure 13] 1 is a graph showing the results of characteristic evaluation of lithium secondary batteries according to Example 8-1, Example 8-2, and Comparative Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0016] In order to fully understand the configuration and effects of the present invention, preferred manufacturing examples of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be realized in various forms and can be modified in various ways. The description of the present embodiments is provided solely to ensure a complete disclosure of the present invention and to fully convey the scope of the invention to those skilled in the art to which the present invention pertains.

[0017] In this specification, when a component is referred to as being on another component, it means that it may be formed directly on the other component, or a third component may be interposed between them. Also, in the drawings, the thickness of the components is exaggerated for the sake of efficient explanation of the technical content. Parts designated with the same reference numerals throughout the specification refer to the same components.

[0018] Unless otherwise specified herein, the singular can also include the plural. Furthermore, unless otherwise specified, "A or B" can mean "including A, including B, or including A and B." As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other elements to the referenced element.

[0019] As used herein, "combinations thereof" can mean mixtures, laminates, composites, copolymers, alloys, blends, reaction products, and the like of compositions.

[0020] 1 is a schematic diagram illustrating a lithium secondary battery according to an embodiment of the present invention. Referring to FIG. 1, the lithium secondary battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0021] The positive electrode 10 and the negative electrode 20 may be separated from each other by a separator 30. The separator 30 may be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20, and the separator 30 may be in contact with the electrolyte solution ELL. The positive electrode 10, the negative electrode 20, and the separator 30 may be immersed in the electrolyte solution ELL.

[0022] The electrolyte ELL can be a medium for transferring lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, the lithium ions can pass through the separator 30 and move toward the positive electrode 10 or the negative electrode 20.

[0023] positive electrode 10 The positive electrode 10 for a lithium secondary battery may include a current collector COL1 and a positive electrode active material layer AML1 formed on the current collector COL1. The positive electrode active material layer AML1 includes a positive electrode active material and may further include a binder and / or a conductive material.

[0024] For example, the positive electrode 10 may further include an additive that can act as a sacrificial positive electrode.

[0025] The content of the positive electrode active material in the positive electrode active material layer AML1 may be 90 wt % to 99.5 wt % relative to 100 wt % of the positive electrode active material layer AML1, and the contents of the binder and conductive material may be 0.5 wt % to 5 wt % each relative to 100 wt % of the positive electrode active material layer AML1.

[0026] The binder serves to firmly adhere the positive electrode active material particles to each other and to firmly adhere the positive electrode active material to the current collector COL1. Representative examples of binders include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylate styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0027] The conductive material is used to impart conductivity to the electrode, and any material that is electronically conductive without causing a chemical change in the battery that is constructed can be used. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials in the form of metal powder or metal fiber containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; and mixtures thereof.

[0028] The current collector COL1 can be made of Al, but is not limited to this.

[0029] positive electrode active material The positive electrode active material in the positive electrode active material layer AML1 can be a compound capable of reversibly intercalating and deintercalating lithium (lithiated intercalation compound). Specifically, one or more of composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0030] The composite oxide is a lithium transition metal composite oxide, and specific examples thereof include lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate compound, cobalt nickel manganese oxide, or a combination thereof.

[0031] As an example, a compound represented by any one of the following chemical formulas can be used: Li a A 1-b X b O 2-c D c (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05);Li a Mn 2-b X b O 4-c D c (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05);Li a Ni 1-b-c Co b X c O 2-α D α (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.5, 0<α<2);Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.5, 0<α<2);Li a Ni b Co c L 1 d G e O2(0.90≦a≦1.8, 0≦b≦0.9, 0≦c≦0.5, 0≦d≦0.5, 0≦e≦0.1);Li a NiG b O2(0.90≦a≦1.8, 0.001≦b≦0.1);Li a CoG b O2(0.90≦a≦1.8, 0.001≦b≦0.1);Li a Mn 1-b G b O2(0.90≦a≦1.8, 0.001≦b≦0.1);Li a Mn2Gb O4(0.90≦a≦1.8, 0.001≦b≦0.1);Li a Mn 1-g G g PO4(0.90≦a≦1.8, 0≦g≦0.5);Li (3-f) Fe2(PO4)3(0≦f≦2);Li a FePO4(0.90≦a≦1.8). In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; and L1 is Mn, Al, or a combination thereof.

[0032] For example, the positive electrode active material may be a high-nickel-based positive electrode active material in which the nickel content relative to 100 mol% of metals excluding lithium in a lithium transition metal composite oxide is 60 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more but not more than 99 mol%. The high-nickel-based positive electrode active material can achieve high capacity and can therefore be applied to high-capacity, high-density lithium secondary batteries.

[0033] negative electrode 20 The negative electrode 20 for a lithium secondary battery includes a current collector COL2 and a negative electrode active material layer AML2 located on the current collector COL2. The negative electrode active material layer AML2 includes a negative electrode active material and may further include a binder and / or a conductive material.

[0034] For example, the negative electrode active material layer AML2 may contain 90 to 99 wt % of the negative electrode active material, 0.5 to 5 wt % of the binder, and 0 to 5 wt % of the conductive material.

[0035] The binder serves to firmly adhere the negative active material particles to each other and to firmly adhere the negative active material to the current collector COL 2. The binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0036] Examples of the non-aqueous binder include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, and combinations thereof.

[0037] The water-based binder may be selected from styrene-styrene rubber, (meth)acrylate styrene-styrene rubber, (meth)acrylonitrile-styrene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0038] When an aqueous binder is used as the negative electrode binder, a cellulose-based compound that can impart viscosity may be further included. The cellulose-based compound may be a mixture of one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, or alkali metal salts thereof. The alkali metal may be sodium, potassium, or lithium.

[0039] The dry binder may be a polymeric material that can be fiberized, such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0040] The conductive material is used to impart conductivity to the electrode, and any material that is electronically conductive without causing a chemical change in the battery may be used. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials in the form of metal powder or metal fiber, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; and mixtures thereof.

[0041] The current collector COL2 may be made of a material selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0042] negative electrode active material The negative electrode active material in the negative electrode active material layer AML2 includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, a lithium metal alloy, a material capable of being doped with and dedoped from lithium, or a transition metal oxide.

[0043] The material capable of reversibly intercalating / deintercalating lithium ions may be a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite. Examples of the amorphous carbon include soft carbon, hard carbon, mesophase pitch carbide, and calcined coke.

[0044] As the alloy of the lithium metal, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0045] As the substance capable of doping and undoping lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. The Si-based negative electrode active material can be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-Q alloy (where Q is selected from an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element (excluding Si), a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and a combination thereof), or a combination thereof. The Sn-based negative electrode active material can be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0046] The silicon-carbon composite can be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite can be in a form in which silicon particles and amorphous carbon are coated on the surface of the silicon particles. For example, it can include secondary particles (cores) formed by aggregation of primary silicon particles and an amorphous carbon coating layer (shell) located on the surface of the secondary particles. The amorphous carbon can also be located between the primary silicon particles, and for example, the primary silicon particles can be coated with amorphous carbon. The secondary particles can be dispersed and present in an amorphous carbon matrix

[0047] The silicon-carbon composite may further contain crystalline carbon. For example, the silicon-carbon composite can include a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core.

[0048] The Si-based negative electrode active material or the Sn-based negative electrode active material can be used by mixing with a carbon-based negative electrode active material. <00​​Depending on the type of lithium secondary battery, a separator 30 may be present between the positive electrode 10 and the negative electrode 20. As such a separator 30, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof can be used, and it goes without saying that mixed multilayer films such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator can also be used.

[0050] Separator 30 can include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0051] The porous substrate may be a polymer membrane formed of any one polymer selected from polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetal, polyamide, polyimide, polycarbonate, polyether ketone, polyaryl ether ketone, polyetherimide, polyamide imide, polybenzimidazole, polyethersulfone, polyphenylene oxide, cyclic olefin copolymer, polyphenylene sulfide, polyethylene naphthalate, glass fiber, Teflon (registered trademark), and polytetrafluoroethylene, or a copolymer or mixture of two or more of these polymers.

[0052] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0053] The inorganic material may include, but is not limited to, inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0054] The organic material and the inorganic material may be mixed in one coating layer, or may be stacked in a coating layer containing an organic material and a coating layer containing an inorganic material.

[0055] Electrolyte ELL The electrolyte ELL for lithium secondary batteries contains a non-aqueous organic solvent and a lithium salt.

[0056] The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can migrate.

[0057] The non-aqueous organic solvent can be a carbonate, ester, ether, ketone, or alcohol solvent, an aprotic solvent, or a combination thereof.

[0058] Examples of the carbonate solvent that can be used include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC).

[0059] Examples of ester solvents that can be used include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolide, mevalonolactone, valerolactone, and caprolactone.

[0060] Examples of ether solvents that can be used include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran. Examples of ketone solvents that can be used include cyclohexanone. Examples of alcohol solvents that can be used include ethyl alcohol and isopropyl alcohol. Examples of aprotic solvents that can be used include nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms, which may contain a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and 1,4-dioxolane; and sulfolanes.

[0061] The non-aqueous organic solvents can be used alone or in combination of two or more.

[0062] In addition, when a carbonate-based solvent is used, a cyclic carbonate and a chain carbonate may be mixed and used, and the cyclic carbonate and the chain carbonate may be mixed in a volume ratio of 1:1 to 1:9.

[0063] The lithium salt is dissolved in an organic solvent and acts as a lithium ion source in the battery, enabling basic lithium secondary battery operation and promoting the movement of lithium ions between the positive electrode and the negative electrode. Representative examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1SO2) (x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro(oxalato)borate (LiDFOB), lithium difluorobis(oxalato)phosphate (LiDFBOP), and lithium bis(oxalato)borate (LiBOB).

[0064] Lithium secondary battery Lithium secondary batteries can be classified into cylindrical, prismatic, pouch, and coin types depending on their shape. FIGS. 2 to 5 are schematic diagrams showing lithium secondary batteries according to embodiments, with FIG. 2 illustrating a cylindrical type, FIG. 3 illustrating a cross-sectional view, FIG. 4 illustrating a prismatic type, and FIG. 5 illustrating a pouch type. Referring to FIGS. 2 to 4, a lithium secondary battery 100 may include an electrode assembly 40 having a separator 30 interposed between a positive electrode 10 and a negative electrode 20, and a case 50 in which the electrode assembly 40 is housed. The positive electrode 10, the negative electrode 20, and the separator 30 may be immersed in an electrolyte (not shown). The lithium secondary battery 100 may include a sealing member 60 that seals the case 50, as shown in FIG. 2. Also, as shown in FIG. 3, the lithium secondary battery 100 may include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. As shown in FIGS. 4 and 5, the lithium secondary battery 100 may include electrode tabs 70, i.e., a positive electrode tab 71 and a negative electrode tab 72, which serve as electrical paths for conducting current generated in the electrode assembly 40 to the outside.

[0065] The lithium secondary battery according to an embodiment of the present invention may be applied to automobiles, mobile phones, and / or various types of electrical devices, but the present invention is not limited thereto.

[0066] 6 to 11 are flow charts illustrating a method for recovering a lithium precursor according to the present invention. Hereinafter, the method for recovering a lithium precursor according to the present invention will be described in more detail with reference to FIGS. 6 to 11.

[0067] Preparing a first basic reagent 6 is a flow chart illustrating the preparation of the first basic reagent according to the present invention. Hereinafter, the preparation of the first basic reagent according to the present invention will be described in detail with reference to FIG.

[0068] 6, preparing the first basic reagent may include mixing and calcining a transition metal precursor and a lithium precursor (S110), washing the calcined first positive electrode active material with a washing solution (S120), recovering the waste liquid generated after washing and removing solids (S130), and adjusting the pH of the waste liquid to be between 8 and 16 (S140). As a result, a first basic reagent containing lithium ions can be prepared from the waste liquid generated in the washing process of the first positive electrode active material (S150).

[0069] A first positive electrode active material may be prepared by mixing and firing a transition metal precursor and a lithium precursor (S110). The first positive electrode active material may be a positive electrode active material represented by the following Chemical Formula 2: [Chemical formula 2] LiM5 e M6 f M7 g M8 h O2

[0070] In the formula 2, 0≦e≦1, 0≦f≦1, 0≦g≦1, 0≦h≦1, and e+f+g+h=1; Each of M5, M6, M7, and M8 in Chemical Formula 2 is an element selected from Ni, Co, Al, Cu, Mn, Ti, Mo, Zn, Zr, Si, Ge, V, Cr, B, Mg, Na, Sr, Ag, Nb, Ga, Ca, or Ba.

[0071] The surface of the calcined first positive electrode active material may be washed with water (S120). Residual lithium by-products on the surface of the calcined first positive electrode active material may be removed through the water washing. The washing solution used for the water washing may be distilled water or an alkaline solution. After the water washing, a waste liquid may be generated. The waste liquid may contain lithium hydroxide (LiOH) and / or lithium carbonate (Li2CO3) derived from the residual lithium by-products.

[0072] Although not shown in FIG. 6, after the mixing and firing (S110), a coating layer may be formed on the surface of the particles of the first positive electrode active material, if necessary. In one embodiment, the coating layer may include at least one of cobalt, aluminum, and zirconium. Forming the coating layer may include adding sodium hydroxide (NaOH) to a coating raw material. Therefore, the waste liquid may additionally contain sodium hydroxide (NaOH).

[0073] After the water washing, the waste liquid generated may be collected and solids removed (S130). The solids may include impurities introduced during the water washing and the first positive electrode active material. The solids may be removed using a decanter (centrifuge), a filter, or a filter press. In one embodiment, the filter paper used in the filter or filter press may have pores of 0.5 μm to 5 μm. In another embodiment, the filter paper used in the filter or filter press may have a D10 smaller than that of the first positive electrode active material.

[0074] The D10 of the first positive electrode active material refers to the diameter of particles that make up 10% of the cumulative volume from the smallest particle size in the particle size distribution of the first positive electrode active material. The D10 can be measured by a method well known to those skilled in the art.

[0075] The pH of the wastewater from which the solids have been removed may be adjusted (S140). Adjusting the pH (S140) may be adjusting the wastewater to be basic. In one embodiment, the pH of the wastewater may be adjusted to 8 to 16. Alternatively, the pH of the wastewater may be adjusted to 12 to 16. Alternatively, the pH of the wastewater may be adjusted to 14 to 16.

[0076] The pH adjusting step (S140) may include adding an alkali hydroxide to the wastewater or evaporating the wastewater. For example, the alkali hydroxide may include one or more compounds selected from the group consisting of sodium hydroxide (NaOH), lithium hydroxide (LiOH), and potassium hydroxide (KOH). However, the alkali hydroxide is not limited to the above-mentioned ranges and may include any alkaline hydroxide.

[0077] The first basic reagent prepared through the above process may contain a high concentration of lithium ions. In one embodiment, the lithium ion concentration of the first basic reagent may be 1,000 ppm to 10,000 ppm. Alternatively, the lithium ion concentration of the first basic reagent may be 3,000 ppm to 10,000 ppm. Alternatively, the lithium ion concentration of the first basic reagent may be 6,000 ppm to 10,000 ppm. The lithium ion concentration of the first basic reagent refers to the mass of lithium ions contained in the first basic reagent relative to the total mass of the first basic reagent. The lithium ion concentration may be measured, for example, using inductively coupled plasma mass spectrometry (ICP-MS).

[0078] The first basic reagent may contain no impurity ions or may contain impurity ions at a low concentration. The impurity ions may refer to ions other than lithium ions. For example, the impurity ions may include sodium ions. In one embodiment, the impurity ion concentration of the first basic reagent may be 15,000 ppm or less. In one embodiment, the impurity ion concentration of the first basic reagent may be 20 ppm to 14,000 ppm. In one embodiment, the impurity ion concentration of the first basic reagent may be 20 ppm to 6,000 ppm. The impurity ion concentration of the first basic reagent refers to the mass of impurity ions contained in the first basic reagent relative to the total mass of the first basic reagent.

[0079] In the step of mixing and calcining a transition metal precursor and a lithium precursor (S110), the lithium precursor may be a lithium precursor extracted by the method for extracting a lithium precursor of the present invention. That is, the wastewater generated in the process of washing a cathode active material prepared using the lithium precursor extracted by the present invention can be reused as a raw material for preparing the first basic reagent of the present invention.

[0080] Preparing the first solution Figure 11 is a flow chart illustrating a method for recovering a lithium precursor according to the present invention. Figure 7 is a flow chart illustrating in detail the step of preparing a first solution containing lithium ions and transition metal ions (S210) of Figure 11. Hereinafter, the step of preparing a first solution according to the present invention (S210) will be described in detail with reference to Figures 7 and 11.

[0081] 7, preparing the first solution may include preparing a discarded lithium transition metal composite oxide ML1 (S211), dissolving the discarded lithium transition metal composite oxide in an acidic solution AS, and filtering the resulting solution (S212). As a result, a first solution containing lithium ions and transition metal ions can be prepared from the discarded lithium transition metal composite oxide ML1 (S210).

[0082] The discarded lithium transition metal composite oxide ML1 may be derived from powder obtained by crushing discarded lithium secondary batteries or waste generated during the manufacturing process of lithium secondary batteries. The discarded lithium transition metal composite oxide ML1 may include a compound represented by the following Chemical Formula 1: [Chemical formula 1] LiM1 a M2 b M3 c M4 d O2

[0083] In Formula 1, 0≦a≦1, 0≦b≦1, 0≦c≦1, 0≦d≦1, and a+b+c+d=1. Each of M1, M2, M3, and M4 in Formula 1 may be an element selected from Ni, Co, Al, Cu, Mn, Ti, Mo, Zn, Zr, Si, Ge, V, Cr, B, Mg, Na, Sr, Ag, Nb, Ga, Ca, or Ba.

[0084] The discarded lithium transition metal composite oxide ML1 may include nickel (Ni). In one embodiment, the discarded lithium transition metal composite oxide ML1 may be an NCA-based oxide including nickel (Ni), cobalt (Co), and aluminum (Al) or an NCM-based oxide including nickel (Ni), cobalt (Co), and manganese (Mn).

[0085] Among the materials that can be used as raw materials for the discarded lithium transition metal composite oxide ML1, the powder obtained by crushing discarded lithium secondary batteries may be obtained by crushing, heat-treating, and sorting discarded lithium secondary batteries. The powder obtained by crushing discarded lithium secondary batteries may include materials derived from the positive electrode, negative electrode, separator, and electrolyte. In one embodiment, the material derived from the positive electrode may be aluminum (Al). The material derived from the negative electrode may be copper (Cu).

[0086] Among the waste materials that can be used as raw materials for the lithium transition metal composite oxide ML1, the waste generated in the manufacturing process of the lithium secondary battery may be obtained by crushing, heat-treating, and sorting a positive electrode active material and / or a positive electrode. Alternatively, the waste generated in the manufacturing process of the lithium secondary battery may be obtained by solid-liquid separation and heat-treating a positive electrode slurry. The waste generated in the manufacturing process of the lithium secondary battery may include materials derived from the positive electrode active material, the positive electrode, and the positive electrode slurry. In one embodiment, the material derived from the positive electrode active material may be nickel (Ni).

[0087] The acid solution AS may contain at least one selected from the group consisting of sulfuric acid (HSO), hydrochloric acid (HCl), nitric acid (HNO), and phosphoric acid (HPO). When the acid solution AS is added, hydrogen peroxide (HO) and / or sulfur dioxide (SO) may be added together to promote dissolution of the transition metal.

[0088] Optionally, after dissolving the manganese in acid solution AS and filtering (S212), the method can further include adding a manganese extractant to extract manganese ions (S213). The manganese extractant can be a phosphoric acid-based compound. For example, di-(2-ethylhexyl)phosphoric acid (D2EHPA) can be added to extract manganese ions. In the case of manganese with low recovery value, pre-extracting it with a manganese extractant in a low pH range immediately after dissolving it in acid solution AS as described above can prevent the simultaneous extraction of manganese ions during the subsequent extraction of transition metals with high recovery value, such as cobalt and nickel, and can further increase the concentration of lithium ions.

[0089] Preparing the second solution Figure 11 is a flow chart illustrating a method for recovering a lithium precursor according to the present invention. Figure 8 is a flow chart illustrating in detail the step of preparing a second solution (S220) by mixing a first solution and a first basic reagent in Figure 11. Hereinafter, the step of preparing a second solution (S220) according to the present invention will be described in detail with reference to Figures 8 and 11.

[0090] Referring to FIG. 8, preparing the second solution may include mixing the first solution and the first basic reagent (S221), and removing the precipitate generated after the mixing (S222).

[0091] Mixing the first solution and the first basic reagent (S221) may include performing the mixing while maintaining the pH of the second solution within a range in which manganese (Mn), cobalt (Co), and nickel (Ni) ions are not easily precipitated. In one embodiment, the mixing ratio of the first solution and the first basic reagent may be adjusted to maintain the pH of the second solution within a range of 3 to 4. In this case, manganese (Mn), cobalt (Co), and nickel (Ni) remain in an ionic state, while iron (Fe) can be precipitated as Fe(OH)3.

[0092] After mixing the first solution and the first basic reagent, the resulting precipitate may be removed (S222). The precipitate may include transition metals other than manganese (Mn), cobalt (Co), and nickel (Ni). In one embodiment, the precipitate may include iron (Fe), aluminum (Al), copper (Cu), zinc (Zn), magnesium (Mg), and / or calcium (Ca). The precipitate may include divalent and / or trivalent transition metals other than manganese (Mn), cobalt (Co), and nickel (Ni). In one embodiment, the precipitate may include aluminum hydroxide (Al(OH)3) and / or copper hydroxide (Cu(OH)2).

[0093] Removing the precipitate may include removing it through filtration. In one embodiment, filtering the precipitate may be performed using a solid-liquid separation device such as a filter, a filter press, or a decanter (centrifuge).

[0094] After the precipitate is removed, unprecipitated transition metal elements may still be present in the second solution. In one embodiment, small amounts of aluminum (Al), copper (Cu), and / or iron (Fe) may still be present in the second solution. The unprecipitated elements may be present in the third solution produced in a subsequent step.

[0095] In the method for recovering a lithium precursor according to the present invention, a first basic reagent is used to replace a conventional basic solution in the step of preparing the second solution (S220). This has the advantage of reducing the amount of environmentally harmful basic solution used. The use of a first basic reagent containing a high concentration of lithium ions has the advantage of increasing the purity of the finally recovered lithium precursor. Another advantage is that lithium ions in the wastewater generated during the water washing process of the positive electrode active material can be recovered by utilizing an existing lithium precursor recovery process without adding a separate process. The conventional basic solution may be sodium hydroxide (NaOH) and / or sodium carbonate (Na2CO3).

[0096] The first basic reagent may be added at a relatively early stage in the entire lithium precursor recovery process. Therefore, lithium ions derived from the first basic reagent may be further concentrated through subsequent steps. For example, the lithium ions may be further concentrated through preparing a third solution (S230) and a fourth solution (S240). This has the advantage of further increasing the purity of the lithium precursor that is finally recovered.

[0097] When the second solution is prepared using a general basic solution, sodium ions from the basic solution may act as impurity ions. This reduces the concentration of lithium ions in the second solution, which can lead to a problem of lowering the purity of the finally recovered lithium precursor. Furthermore, the sodium ions may be mixed into the finally recovered lithium precursor in the form of sodium sulfate (Na2SO4). Therefore, an additional step is required to separate and remove the sodium sulfate (Na2SO4), which is an unintended recovered product, which can increase the cost of the overall recovery process.

[0098] Preparing the third solution Figure 11 is a flowchart illustrating a method for recovering a lithium precursor according to the present invention. Figure 9 is a flowchart illustrating in detail the step of extracting transition metal ions from the second solution to prepare a third solution (S230) of Figure 11. Hereinafter, the step of preparing the third solution according to the present invention (S230) will be described in detail with reference to Figures 9 and 11.

[0099] Referring to FIG. 9, preparing the third solution may include mixing the second solution and a transition metal extractant (S231), and extracting the transition metal ions (S232).

[0100] Optionally, preparing the third solution (S230) may further include, after extracting the transition metal ions (S232), adding sodium phosphate (NaPO) and then filtering to obtain precipitated lithium phosphate (LiPO) (S233), dissolving the lithium phosphate in a sulfuric acid solution (S234), and adding ferric sulfate (Fe(SO)) and then filtering to remove precipitated iron phosphate (FePO) (S235).

[0101] The transition metal extractant may include a phosphoric acid compound, a phosphonic acid compound, a phosphinic acid compound, and / or a carboxylic acid compound. In one embodiment, the transition metal extractant may be di-(2-ethylhexyl)phosphoric acid (D2EHPA), bis(2,2,4-trimethylpentyl)phosphinic acid (Cyanex 272), and / or 2-ethylhexyl 2-ethylhexyphosphonic acid (PC88A).

[0102] The mixing of the second solution and the transition metal extractant can be performed while gradually increasing the pH. In one embodiment, manganese (Mn) can be extracted by adding di-(2-ethylhexyl)phosphoric acid (DEHPA) while maintaining the pH in the range of 3 to 4. After that, sodium hydroxide (NaOH) is added to adjust the pH to 4 to 5, and bis(2,2,4-trimethylpentyl)phosphinic acid (Cyanex 272) is added to extract cobalt (Co). After that, sodium hydroxide (NaOH) is added to adjust the pH to 5 to 6, and 2-ethylhexyl 2-ethylhexyphosphonic acid (PC88A) is added to extract nickel (Ni).

[0103] As mentioned above, if necessary, manganese (Mn) may be pre-extracted immediately after dissolving it in the acid solution AS and then filtering (S212).

[0104] A saponified transition metal extractant may be used instead of the transition metal extractant. The mechanism by which transition metals are extracted with the transition metal extractant is that the hydrogen ions of the transition metal extractant are replaced by transition metal ions, and the replaced transition metal ions bind to the anions of the transition metal extractant. In this case, the hydrogen ions released from the transition metal extractant lower the pH of the solution, which may make the transition metal extraction performed by gradually increasing the pH as described above difficult. Therefore, to compensate for this, a saponified transition metal extractant in which the hydrogen ions of the transition metal extractant are replaced by sodium ions may be used.

[0105] After the extraction of the transition metal ions (S232), unprecipitated transition metal ions may still remain. In one embodiment, small amounts of aluminum (Al), copper (Cu), and / or iron (Fe) may still remain. The unprecipitated ions may be contained in a fourth solution prepared in a subsequent step.

[0106] Preparing the fourth solution Figure 11 is a flow chart illustrating a method for recovering a lithium precursor according to the present invention. Figure 10 is a flow chart illustrating in detail the step of preparing a fourth solution (S240) by mixing the third solution and the second basic reagent in Figure 11. Hereinafter, the step of preparing the fourth solution (S240) according to the present invention will be described in detail with reference to Figures 10 and 11.

[0107] Referring to FIG. 10, preparing the fourth solution may include mixing the third solution and the second basic reagent (S241), and removing the precipitate formed after mixing (S242).

[0108] The second basic reagent may be prepared using wastewater generated during a washing process of the positive electrode active material. Alternatively, the second basic reagent may be a general basic solution. The general basic solution may be sodium hydroxide (NaOH) and / or sodium carbonate (Na2CO3). When the second basic reagent is prepared using wastewater generated during a washing process of the positive electrode active material, it may be prepared using the same method as the first basic reagent described above.

[0109] Mixing the third solution and the second basic reagent (S241) may include performing the mixing while maintaining a lithium concentration in the fourth solution at not more than 3,000 ppm. The lithium concentration in the fourth solution may refer to the mass of lithium in the fourth solution relative to the total mass of the fourth solution.

[0110] Mixing the third solution and the second basic reagent (S241) may include performing the mixing while maintaining the pH of the fourth solution in the range of 7 to 11.

[0111] When the mixing is performed while satisfying the lithium concentration and pH conditions of the fourth solution, an environment can be formed in which ions other than lithium ions are easily precipitated but lithium ions are not easily precipitated, which allows impurity ions other than lithium ions to be extracted while preventing lithium ions from being extracted, thereby increasing the purity of the lithium precursor obtained later.

[0112] A precipitate formed after mixing the third solution and the second basic reagent may be removed (S242). The precipitate may include the unprecipitated impurities remaining in the second solution preparation (S220). The precipitate may include transition metals excluding manganese (Mn), cobalt (Co), and nickel (Ni). In one embodiment, the solid-phase impurities may include iron (Fe), aluminum (Al), copper (Cu), zinc (Zn), magnesium (Mg), and / or calcium (Ca).

[0113] The precipitate may include the material remaining after preparing the third solution (S230) and may include manganese (Mn), cobalt (Co), and / or nickel (Ni).

[0114] The precipitate may contain divalent and / or trivalent transition metals in the form of hydroxides. For example, the precipitate may contain Al(OH)3 and / or Co(OH)2. The hydroxide ions (OH) from the fourth solution may be added to the precipitate. - ) may combine with divalent and / or trivalent transition metal ions to form the precipitate.

[0115] Removing the precipitate may include removing it through filtration. In one embodiment, filtering the precipitate may be performed using a solid-liquid separation device such as a filter, a filter press, or a decanter (centrifuge).

[0116] The method for recovering a lithium precursor according to the present invention uses a second basic reagent produced from wastewater generated during the washing process of a cathode active material, which can replace a conventional basic solution. This has the advantage of reducing the amount of environmentally harmful basic solution used. Finally, it has the advantage of increasing the purity of the recovered lithium precursor. It has the advantage of recovering lithium ions from wastewater generated during the washing process of a cathode active material by utilizing an existing lithium precursor recovery process without adding a separate process.

[0117] In the method for recovering a lithium precursor according to the present invention, both the first and second basic reagents may be prepared using wastewater generated in a water washing process of a positive electrode active material. This can have the effect of replenishing high-concentration lithium ions twice in the process of recovering a lithium precursor. Therefore, there is an advantage in that the purity of the finally recovered lithium precursor can be further increased.

[0118] Extracting the lithium precursor 11 is a flow chart illustrating a method for recovering a lithium precursor according to the present invention. Hereinafter, the step of extracting a lithium precursor (S250) according to the present invention will be described in detail with reference to FIG.

[0119] A lithium precursor can be extracted (S250) from the fourth solution from which the impurities have been removed. The lithium precursor can be lithium carbonate (Li2CO3) or lithium hydroxide (LiOH).

[0120] When extracting a lithium precursor in the form of lithium carbonate (Li2CO3), an alkali carbonate can be added to the fourth solution from which the impurities have been removed. Then, a lithium precursor in the form of lithium carbonate (Li2CO3) can be extracted through solid-liquid separation. In one embodiment, the alkali carbonate can be sodium carbonate (Na2CO3). The obtained lithium carbonate (Li2CO3) can be used as a raw material for a low-nickel positive electrode active material in which the moles of nickel relative to the moles of metal elements excluding lithium in the positive electrode active material are 60% or less. In one embodiment, the low-nickel positive electrode active material is LiNi 0.6 Co 0.2 Mn 0.2 It can be O2.

[0121] When extracting a lithium precursor in the form of lithium hydroxide (LiOH), an alkali hydroxide can be added to the extracted lithium carbonate. Then, calcium carbonate (CaCO3) can be removed through solid-liquid separation, and a lithium precursor in the form of lithium hydroxide (LiOH) can be extracted through evaporation. In one embodiment, the alkali hydroxide can be calcium hydroxide (Ca(OH)2). The obtained lithium hydroxide can be used as a raw material for a high-nickel positive electrode active material in which the number of moles of nickel relative to the number of moles of metal elements excluding lithium in the positive electrode active material is more than 60%. In one embodiment, the high-nickel positive electrode active material is LiNi 0.8 Co 0.15 Al 0.05 It can be O2.

[0122] The lithium precursor extracted according to the present invention can be used as a raw material for preparing a positive electrode active material. In this case, the transition metal precursor used together as a raw material for preparing the positive electrode active material may be a transition metal precursor represented by the following Chemical Formula 3: [Chemical formula 3] M9 i M10 j M11 k M12 l (OH)2

[0123] In the formula 3, 0≦i≦1, 0≦j≦1, 0≦k≦1, 0≦l≦1, and i+j+k+l=1; Each of M9, M10, M11, and M12 in Chemical Formula 3 is an element selected from Ni, Co, Al, Cu, Mn, Ti, Mo, Zn, Zr, Si, Ge, V, Cr, B, Mg, Na, Sr, Ag, Nb, Ga, Ca, or Ba.

[0124] The lithium precursor recovered according to the present invention may have a high purity of lithium ions, and the mass ratio of lithium ions contained in the recovered lithium precursor to the total mass of the recovered lithium precursor may be 99% or more.

[0125] Examples and comparative examples of the present invention will be described below. However, the following examples are merely illustrative of the present invention, and the present invention is not limited to the following examples.

[0126] Example 1: Preparing the First Basic Reagent Ni 0.6 Co 0.2 Mn 0.2 A positive electrode active material was prepared by mixing (OH)2 and lithium hydroxide (LiOH) and calcining the mixture. The positive electrode active material was washed with a water washing solution to obtain a first waste liquid. The solids in the first waste liquid were filtered through a 5 μm filter paper to obtain a second waste liquid. The pH of the second waste liquid was 12.8. The second waste liquid was evaporated until the pH reached 15 to prepare a first basic reagent. The components of the first waste liquid and the first basic reagent were analyzed and are shown in Table 1 below.

[0127] Example 2: Preparing the First Solution Discarded lithium transition metal oxide, LiNi 0.8 Co 0.15 Al 0.05 O2, sulfuric acid (H2SO4), oxidizing agent (H2O2), and water were mixed in a weight ratio of 1:1.5:0.5:3. A lithium transition metal solution was prepared by solid-liquid separation. The pH of the lithium transition metal solution was 1.1.

[0128] Sodium hydroxide was added to the lithium transition metal solution to adjust the pH to 3. Di-(2-ethylhexyl)phosphoric acid (D2EHPA), an alkyl phosphate-based transition metal extractant, was diluted with kerosene to 25% by volume, and manganese was extracted and removed through solvent extraction. Finally, a first solution was prepared. The components of the lithium transition metal solution and the first solution were analyzed and are shown in Table 2 below.

[0129] Example 3: Preparing the second solution The first basic reagent of Example 1 and the first solution of Example 2 were mixed and the pH was adjusted to 5. Precipitated aluminum (Al) was removed. An oxidizing agent (H2O2) was added to lower the pH to 4. Precipitated iron (Fe) was removed. Finally, a second solution was prepared. The components of the second solution were analyzed and are shown in Table 3 below.

[0130] Comparative Example 1: Preparing the Second Comparative Solution A second comparative solution was prepared in the same manner as in Example 3, except that sodium hydroxide (NaOH) was used instead of the first basic reagent in Example 1. The components of the second comparative solution were analyzed and are shown in Table 3 below.

[0131] Example 4: Preparing the third solution Sodium hydroxide (NaOH) was added to the second solution of Example 3 to adjust the pH to 5. Bis(2,2,4-trimethylpentyl)phosphinic acid (Cyanex 272) was diluted with kerosene to 25% by volume, and cobalt (Co) was extracted and removed through solvent extraction. Sodium hydroxide (NaOH) was added to adjust the pH to 7. 2-Ethylhexyl 2-ethylhexyphosphonic acid (PC88A) was diluted with kerosene to 25% by volume, and nickel (Ni) was extracted and removed through solvent extraction.

[0132] Sodium phosphate (Na3PO4) was added to the solution from which the transition metals had been removed, and precipitated lithium phosphate (Li3PO4) was obtained. The lithium phosphate (Li3PO4) was dissolved in a sulfuric acid (H2SO4) solution. Ferric sulfate (Fe2(SO4)3) was added to the solution, and the precipitated iron phosphate (FePO4) was removed through filtration. Finally, a third solution was prepared.

[0133] Comparative Example 2: Preparing the Third Comparative Solution A third comparative solution was prepared in the same manner as in Example 4, except that the second comparative solution of Comparative Example 1 was used instead of the second solution of Example 3.

[0134] Example 5-1: Preparing the Fourth Solution I Sodium hydroxide (NaOH) was added to the third solution of Example 4 to adjust the pH to 10. The precipitate was removed through solid-liquid separation. Finally, a fourth solution was prepared.

[0135] Example 5-2: Preparing the Fourth Solution II A fourth solution was prepared in the same manner as in Example 5-1, except that the first basic reagent of Example 1 was used instead of sodium hydroxide (NaOH).

[0136] Comparative Example 3: Preparing the Fourth Comparative Solution A fourth comparative solution was prepared in the same manner as in Example 5-1, except that the third comparative solution of Comparative Example 2 was used instead of the third solution of Example 4.

[0137] Example 6-1: Extracting Lithium Precursors I Sodium carbonate (Na2CO3) was added to the fourth solution of Example 5-1, and a lithium precursor in the form of lithium carbonate (Li2CO3) was extracted through solid-liquid separation.

[0138] To further remove sodium from the extracted lithium precursor, the extracted lithium precursor was washed with water. The temperature of the water was 85°C, and the mass of the water used was twice the mass of the extracted lithium precursor. The components of the extracted lithium precursor were analyzed and are shown in Table 4 below.

[0139] Example 6-2: Extracting Lithium Precursors II A lithium precursor in the form of lithium carbonate (LiCO) was extracted and washed in the same manner as in Example 6-1, except that the fourth solution in Example 5-2 was used instead of the fourth solution in Example 5-1. The components of the extracted lithium precursor were analyzed and are shown in Table 4 below.

[0140] Comparative Example 4: Extracting the Lithium Precursor III A lithium precursor in the form of lithium carbonate (LiCO) was extracted and washed in the same manner as in Example 6-1, except that the fourth comparative solution of Comparative Example 3 was used instead of the fourth solution of Example 5-1. The components of the extracted lithium precursor were analyzed and are shown in Table 4 below.

[0141] Example 7-1: Preparing a positive electrode active material I A positive electrode active material was prepared using lithium carbonate (Li2CO3) of Example 6-1.

[0142] A nickel sulfate (NiSO4) aqueous solution, a cobalt sulfate (CoSO4) aqueous solution, and a manganese sulfate (MnSO4) aqueous solution were mixed so that the molar ratio of nickel:cobalt:manganese elements was 0.6:0.2:0.2. Sodium hydroxide (NaOH) and a coprecipitation chelating agent, ammonia water (NH4OH), were added to the mixed solution to coprecipitation the transition metal precursor Ni 0.6 Co 0.2 Mn 0.2 (OH)2 was prepared.

[0143] Ni 0.6 Co 0.2 Mn 0.2 (OH)2 and lithium carbonate (Li2CO3) of Example 6-1 were mixed so that the molar ratio of Ni:Co:Mn:Li was 0.6:0.2:0.2:1.1, and then the mixture was subjected to a primary firing at 750°C to prepare a positive electrode active material. The positive electrode active material was washed with water to remove the lithium remaining on the surface. To replenish the excess lithium washed with water, additional lithium carbonate (Li2CO3) of Example 6-1 was added, and the mixture was subjected to a secondary firing at 750°C. Finally, LiNi 0.6 Co 0.2 Mn 0.2 The NCM622 cathode active material was prepared.

[0144] Example 7-2: Preparing the Positive Electrode Active Material II An NCM622 positive electrode active material was prepared in the same manner as in Example 7-1, except that the lithium carbonate (Li2CO3) of Example 6-2 was used instead of the lithium carbonate (Li2CO3) of Example 6-1.

[0145] Comparative Example 5: Preparation of Positive Electrode Active Material III An NCM622 positive electrode active material was prepared in the same manner as in Example 7-1, except that the lithium carbonate (Li2CO3) of Comparative Example 4 was used instead of the lithium carbonate (Li2CO3) of Example 6-1.

[0146] Example 8-1: Manufacturing a lithium secondary battery I A lithium secondary battery was fabricated using the cathode active material (NCM622) of Example 7-1. 97 wt% of the cathode active material of Example 7-1, 1.5 wt% of polyvinylidene fluoride binder, and 1.5 wt% of carbon black conductive material were mixed in N-methylpyrrolidone solvent to prepare a cathode active material slurry. The cathode active material slurry was applied to a 15 μm-thick aluminum current collector at a rate of 15 mg per cm2 of the current collector, dried, and rolled to prepare a cathode.

[0147] A 2032-type coin half-cell was fabricated using the positive electrode and a lithium metal counter electrode as the counter electrode. A separator made of a porous polyethylene film was placed between the positive electrode and the lithium metal counter electrode, and an electrolyte was injected to fabricate a lithium secondary battery. The electrolyte contained an organic solvent made by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) in a 1:1 volume ratio, and contained 1M LiPF6 lithium salt.

[0148] Example 8-2: Manufacturing a lithium secondary battery II A lithium secondary battery was fabricated in the same manner as in Example 8-1, except that the positive electrode active material (NCM622) of Example 7-2 was used instead of the positive electrode active material (NCM622) of Example 7-1.

[0149] Comparative Example 6: Manufacturing a Lithium Secondary Battery III A lithium secondary battery was fabricated in the same manner as in Example 8-1, except that the positive electrode active material (NCM622) of Comparative Example 5 was used instead of the positive electrode active material (NCM622) of Example 7-1.

[0150] Evaluation example 1: Component analysis of solution I The components of the solutions at each stage in Example 1 were analyzed, and the results are shown in Table 1.

[0151] [Table 1] *Unit: ppm *N / D: Not Detected

[0152] Referring to Table 1, it can be seen that the lithium concentration in the first basic reagent is higher than that in the first waste liquid, that is, it can be seen that a first basic reagent with an increased lithium ion content was prepared in order to extract high-purity lithium in the subsequent steps.

[0153] Evaluation example 2: Component analysis of solution II The components of the solutions at each stage of Example 2 were analyzed, and the results are shown in Table 2.

[0154] [Table 2] *Unit: ppm *N / D: Not Detected

[0155] Referring to Table 2, it can be seen that the first solution contains lithium ions and a transition metal.

[0156] Evaluation example 3: Component analysis of solution III The components of the second solution of Example 3 and the second comparative solution of Comparative Example 1 were analyzed, and the results are shown in Table 3.

[0157] [Table 3] *Unit: ppm *N / D: Not Detected

[0158] Referring to Table 3, it can be seen that the second solution of Example 3 contains a larger amount of lithium and a smaller amount of sodium than the second comparative solution of Comparative Example 1. Such component characteristics of the second solution increase the lithium content and decrease the sodium content of the final lithium precursor, which can contribute to obtaining a high-purity lithium precursor.

[0159] Evaluation example 4: Component analysis of lithium precursor The components of the lithium precursors of Example 6-1, Example 6-2, and Comparative Example 4 were analyzed, and the results are shown in Table 4. In Table 4, purity refers to the weight of lithium ions relative to the total weight of the lithium precursor.

[0160] The results of X-ray diffraction (XRD) analysis of the lithium precursor of Example 6-1 and the lithium precursor of Comparative Example 4 are shown in FIG.

[0161] [Table 4] *Unit: ppm *N / D: Not Detected

[0162] Referring to Table 4, it can be seen that the lithium purities of the lithium precursors of Examples 6-1 and 6-2 are higher than that of the lithium precursor of Comparative Example 4. It can also be seen that the sodium ion concentrations of Examples 6-1 and 6-2 are lower. In other words, it can be seen that a high-purity lithium precursor can be obtained according to an embodiment of the present invention.

[0163] Referring to Table 4, it can be seen that the sodium ion concentration in Example 6-2 is lower than that in Example 6-1. In other words, it can be seen that when sodium hydroxide (NaOH) is replaced with the "wastewater generated in the washing process of the cathode active material" according to the present invention, the concentration of impurity ions can be reduced.

[0164] 12, it can be seen that the lithium precursor of Example 6-1 contains significantly less sodium compound (NaSO) than the lithium precursor of Comparative Example 4. That is, it can be seen that a high-purity lithium precursor can be obtained according to an embodiment of the present invention.

[0165] Evaluation example 5: Battery characteristic evaluation The characteristics of the lithium secondary batteries of Example 8-1, Example 8-2, and Comparative Example 6 were evaluated.

[0166] The lithium secondary battery was initially charged at 25°C under constant current (0.2C) and constant voltage (4.25V, cutoff current: 0.05C) conditions, rested for 10 minutes, and then discharged at a constant current (0.2C) until the voltage reached 2.5V. The initial charge-discharge cycle was then repeated 100 times at 25°C under 0.2C (4.25V, cutoff current: 0.05C) / 0.2C (2.5V, cutoff current: 0.05C). The battery performance evaluation results are shown in Table 5 and Figure 13.

[0167] [Table 5]

[0168] 13, it can be seen that the lithium secondary batteries of Examples 8-1 and 8-2 have similar or superior initial charge / discharge capacity, initial efficiency, 100-cycle discharge capacity, and room temperature capacity retention rate compared to the lithium secondary battery of Comparative Example 6. That is, it can be seen that the method for recovering a lithium precursor according to the present invention can achieve all of the problems to be solved as described above, while at the same time producing a lithium secondary battery with performance similar to or superior to that of a conventional lithium secondary battery.

[0169] Although the preferred manufacturing examples and embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the claims, the detailed description of the invention, and the accompanying drawings, and it is to be understood that these also fall within the scope of the present invention. [Explanation of symbols]

[0170] 100 Lithium secondary battery 10 positive electrode 11 Positive electrode lead tab 12 Positive terminal 20 negative electrode 21 Negative electrode lead tab 22 Negative terminal 30 Separator 40 Electrode assembly 50 cases 60 Sealing member 70 Electrode tab 71 Positive electrode tab 72 Negative electrode tab

Claims

1. preparing a first solution containing lithium ions and transition metal ions; mixing the first solution and a first basic reagent to produce a second solution; extracting a transition metal from the second solution to produce a third solution; mixing the third solution and a second basic reagent to produce a fourth solution; extracting a lithium precursor from the fourth solution; Including, The first basic reagent is produced using waste liquid generated in a water washing process of a positive electrode active material. Method for recovering lithium precursors.

2. The second basic reagent is produced using waste liquid generated in a water washing process of a positive electrode active material.

10. A method for recovering the lithium precursor of claim 1.

3. Producing the first solution comprises: Dissolving the discarded lithium transition metal composite oxide in an acidic solution; The discarded lithium transition metal composite oxide is derived from powder obtained by crushing discarded lithium secondary batteries or waste generated in a lithium secondary battery manufacturing process, The discarded lithium transition metal composite oxide comprises a compound of the following Chemical Formula 1:

10. A method for recovering the lithium precursor of claim 1. [Chemical formula 1] LiM1 a M2 b M3 c M4 d O 2 (In Chemical Formula 1, 0≦a≦1, 0≦b≦1, 0≦c≦1, 0≦d≦1, and a+b+c+d=1. Each of M1, M2, M3, and M4 in Chemical Formula 1 may be an element selected from Ni, Co, Al, Cu, Mn, Ti, Mo, Zn, Zr, Si, Ge, V, Cr, B, Mg, Na, Sr, Ag, Nb, Ga, Ca, or Ba.)

4. Producing the first basic reagent comprises: washing the fired positive electrode active material with a washing solution; After the water washing, recovering the waste liquid generated and removing solid matter; and adjusting the pH of the waste liquid to 8 to 16.

10. A method for recovering the lithium precursor of claim 1.

5. The positive electrode active material is a positive electrode active material represented by the following Chemical Formula 2:

5. The method for recovering lithium precursors according to claim 4. [Chemical formula 2] L-M5 e M6 f M7 g M8 h O 2 (In the above Chemical Formula 2, 0≦e≦1, 0≦f≦1, 0≦g≦1, 0≦h≦1, and e+f+g+h=1; Each of M5, M6, M7, and M8 in Chemical Formula 2 is an element selected from Ni, Co, Al, Cu, Mn, Ti, Mo, Zn, Zr, Si, Ge, V, Cr, B, Mg, Na, Sr, Ag, Nb, Ga, Ca, or Ba.

6. Removing solids from the waste liquid may include using a decanter (centrifuge), a filter, or a filter press; The filter or filter press comprises filter paper having pores of 0.5 μm to 5 μm.

5. The method for recovering lithium precursors according to claim 4.

7. Adjusting the pH of the waste liquid Adding an alkali hydroxide to the waste liquid or evaporating the waste liquid.

5. The method for recovering lithium precursors according to claim 4.

8. the pH of the first basic reagent is 12 to 16; 10. A method for recovering the lithium precursor of claim 1.

9. The first basic reagent is Lithium carbonate (Li 2 CO 3 ) and lithium hydroxide (LiOH), 10. A method for recovering the lithium precursor of claim 1.

10. a mass value of the lithium ions contained in the first basic reagent relative to the total mass of the first basic reagent is 1,000 ppm to 10,000 ppm; 10. A method for recovering the lithium precursor of claim 1.

11. a mass value of the impurity ions contained in the first basic reagent relative to the total mass of the first basic reagent is 20 ppm to 14,000 ppm; 10. A method for recovering the lithium precursor of claim 1.

12. The step of washing the positive electrode active material with water includes: and washing a positive electrode active material prepared using the lithium precursor recovered by the method for recovering a lithium precursor according to claim 1 with water.

10. A method for recovering the lithium precursor of claim 1.

13. Producing the second solution comprises: mixing the first solution and the first basic reagent so that the pH of the second solution is between 3 and 4; 10. A method for recovering the lithium precursor of claim 1.

14. Producing the fourth solution comprises: mixing the third solution and the second basic reagent while satisfying a condition that the mass of lithium contained in the fourth solution relative to the total mass of the fourth solution is not less than 3,000 ppm; 10. A method for recovering the lithium precursor of claim 1.

15. a mass ratio of lithium ions contained in the recovered lithium precursor to the total mass of the recovered lithium precursor is 99% or more; 10. A method for recovering the lithium precursor of claim 1.

16. The recovered lithium precursor is lithium carbonate (Li 2 CO 3 ) or lithium hydroxide (LiOH), 10. A method for recovering the lithium precursor of claim 1.

17. mixing a transition metal precursor with a lithium precursor recovered by the method of claim 1 and then calcining the mixture; and washing the fired mixture with water. A method for manufacturing a positive electrode active material for a lithium secondary battery.

18. The transition metal precursor is a compound of Formula 3: The method for producing a positive electrode active material for a lithium secondary battery according to claim 17. [Chemical formula 3] M9 i M10 j M11 k M12 l (OH) 2 (In the above Chemical Formula 3, 0≦i≦1, 0≦j≦1, 0≦k≦1, 0≦l≦1, and i+j+k+l=1, Each of M9, M10, M11, and M12 in Chemical Formula 3 is an element selected from Ni, Co, Al, Cu, Mn, Ti, Mo, Zn, Zr, Si, Ge, V, Cr, B, Mg, Na, Sr, Ag, Nb, Ga, Ca, or Ba.

19. M9 in the above Chemical Formula 3 is Ni; The method for producing a positive electrode active material for a lithium secondary battery according to claim 18.

20. A lithium secondary battery comprising a positive electrode active material produced by the method for producing a positive electrode active material for a lithium secondary battery according to claim 17.

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