Method for recovering organic solvent from liquid waste from all-solid-state battery process, and apparatus for recovering same

Abstract

The present invention relates to a method for recovering an organic solvent from a liquid waste generated in a process of manufacturing an all-solid-state battery, and an apparatus for recovering the organic solvent. More specifically, the method comprises: preparing a first raw material solution containing a cathode active material, a solid electrolyte, and a solvent, from a liquid waste generated in a process of manufacturing an all-solid-state battery; forming a second raw material solution by mixing the first raw material solution and a viscosity modifier; forming a third raw material solution by removing the cathode active material from the second raw material solution; and extracting the solvent of the third raw material solution from the third raw material solution. The removal of the cathode active material uitilizes the difference in particle size between the cathode active material and the solid electrolyte.

Description

Method for recovering organic solvent from waste liquid of all-solid-state battery process, and device for recovering the same

[0001] The present invention relates to a method for recovering an organic solvent from waste generated in a process for manufacturing an all-solid-state battery and a device for recovering the same.

[0002]

[0003] Lithium secondary batteries are widely used as energy storage and supply sources in various fields. They are widely used not only in portable devices such as mobile phones, tablets, wearable devices, laptops, digital cameras, and power tools, but also in transportation such as hybrid cars, electric vehicles, and electric scooters. Recently, their application is expanding to future industries such as drones, robots, and urban air mobility (UAM).

[0004] In particular, the electric vehicle market has grown significantly due to the recent increase in awareness of climate change and interest in environmental friendliness, and as a result, the use of lithium secondary batteries is increasing rapidly.

[0005] However, most current lithium secondary batteries contain liquid electrolytes, posing a risk of short circuits. Because this can lead to major accidents such as fires or explosions, active research is underway to find alternative solutions to address short circuits.

[0006] To address the aforementioned short circuit, alternatives using solid electrolytes instead of liquid electrolytes are gaining attention. Namely, all-solid-state batteries are gaining attention. All-solid-state batteries can physically isolate the anode and cathode by using a solid electrolyte, and their safety can be further enhanced by using low-flammability materials as the solid electrolyte.

[0007] However, all-solid-state batteries are relatively expensive to manufacture, making commercialization difficult at present. This high manufacturing cost stems from the high cost of the cathode active materials, solid electrolytes, and solvents used in all-solid-state batteries, as well as the relatively high cost of the manufacturing process.

[0008] Therefore, in order to commercialize all-solid-state batteries, a method to lower the current high manufacturing costs must first be developed.

[0009]

[0010] The problem to be solved by the present invention is to provide a method for recovering an organic solvent from waste liquid generated in the process of manufacturing an all-solid-state battery.

[0011] Another problem to be solved by the present invention is to provide a device for recovering organic solvent from waste liquid generated in the process of manufacturing an all-solid-state battery.

[0012]

[0013] A method for recovering an organic solvent according to the concept of the present invention may include preparing a first raw material solution including a positive electrode active material, a solid electrolyte, and a solvent from a waste liquid generated in a process for manufacturing an all-solid-state battery; forming a second raw material solution by mixing the first raw material solution and a viscosity modifier; forming a third raw material solution by removing the positive electrode active material from the second raw material solution; and extracting a solvent of the third raw material solution from the third raw material solution. Removing the positive electrode active material may utilize a difference in particle size between the positive electrode active material and the solid electrolyte.

[0014] A device for recovering an organic solvent according to another concept of the present invention may include a raw material supply unit that supplies a first raw material solution including a positive electrode active material, a solid electrolyte, and a solvent; a viscosity control unit that controls the viscosity of the first raw material solution to form a second raw material solution; a filtering unit that removes the positive electrode active material from the second raw material solution to form a third raw material solution; a solvent extraction unit that extracts the solvent of the third raw material solution from the third raw material solution; a first transport unit that transports the extracted solvent to the viscosity control unit for reuse; and a second transport unit that transports the extracted solvent to the filtering unit for reuse. The filtering unit may include a filter unit and a rinsing unit.

[0015]

[0016] The method for recovering an organic solvent according to the present invention allows the recovered organic solvent to be reused.

[0017] By reusing the recovered organic solvent, the purity of the positive electrode active material recovered in the process following the organic solvent recovery process can be increased.

[0018] By reusing the recovered organic solvent, the purity of the solid electrolyte recovered in the process following the organic solvent recovery process can be increased.

[0019] The above-mentioned recovered organic solvent can be reused and used in a process for manufacturing an all-solid.

[0020] The method for recovering an organic solvent according to the present invention can reduce the manufacturing cost of an all-solid-state battery.

[0021]

[0022] Figure 1 is a flowchart illustrating a method for recovering an organic solvent according to the present invention.

[0023] Figure 2 illustrates a positive electrode layer of a solid electrolyte according to one embodiment.

[0024] Figure 3 illustrates forming a second raw material solution (S220).

[0025] Figure 4 illustrates rinsing of a positive electrode active material according to one embodiment of the present invention.

[0026] Figure 5 illustrates rinsing of a positive electrode active material using a method not according to the present invention.

[0027] Figure 6 is a flowchart for explaining a device for recovering an organic solvent according to the present invention.

[0028] Figure 7 is a graph showing the results of X-ray diffraction (XRD) analysis for NCM811 powder and Li6PS5Cl powder.

[0029] Figure 8 is a graph showing the results of X-ray diffraction (XRD) analysis of the positive electrode active material powder of Example 1.

[0030] Figure 9 is a graph showing the results of X-ray diffraction (XRD) analysis of the residual solid powder of Example 1.

[0031] Figure 10 is a graph showing the results of X-ray diffraction (XRD) analysis for the residual solid powder of Comparative Example 1.

[0032]

[0033] To fully understand the structure and effects of the present invention, preferred manufacturing examples and embodiments 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, but can be implemented in various forms and subject to various modifications. However, the description of these embodiments is provided to ensure a complete disclosure of the present invention and to fully inform those skilled in the art of the invention of the scope of the invention.

[0034] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. Furthermore, in the drawings, the thicknesses of the components are exaggerated for the sake of clarity. Parts designated by the same reference numerals throughout the specification represent the same components.

[0035] Unless otherwise specified herein, the singular may also include the plural. Furthermore, unless otherwise specified, "A or B" may 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 components.

[0036] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0037] Unless otherwise defined herein, the particle size may be the average particle size. In addition, the particle size refers to the average particle size (D50), which means the diameter of particles with a cumulative volume of 50% by volume in a particle size distribution. The average particle size (D50) can be measured by a method well known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) photograph or a scanning electron microscope (SEM) photograph. Alternatively, the average particle size (D50) value can be obtained by measuring with a measuring device that utilizes dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and calculating from the counted number. Alternatively, the average particle size (D50) value can be obtained by measuring with a laser diffraction method. When measuring by laser diffraction, more specifically, after the particles to be measured are dispersed in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasonic waves of approximately 28 kHz at an output of 60 W, and the average particle size (D50) based on 50% of the particle size distribution in the measuring device can be calculated.

[0038] Embodiments described herein will be described with reference to cross-sectional and / or plan views, which are ideal illustrations of the present invention. In the drawings, the thicknesses of films and regions are exaggerated for the purpose of effectively explaining the technical contents. Accordingly, the regions illustrated in the drawings have a schematic nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific shapes of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, and third are used to describe various components in various embodiments of the present specification, these components should not be limited by such terms. These terms are used only to distinguish one component from another. The embodiments described and illustrated herein also include complementary embodiments thereof.

[0039]

[0040] Figures 1 to 5 are flowcharts illustrating a method for recovering an organic solvent according to the present invention. Hereinafter, with reference to Figures 1 to 5, the method for recovering an organic solvent according to the present invention will be described in more detail.

[0041] A method for recovering an organic solvent according to the present invention may include preparing a first raw material solution including a positive electrode active material, a solid electrolyte, and a solvent from a waste liquid generated in a process for manufacturing an all-solid-state battery (S210); mixing the first raw material solution and a viscosity modifier to form a second raw material solution (S220); removing the positive electrode active material from the second raw material solution to form a third raw material solution (S230); and extracting the solvent of the third raw material solution from the third raw material solution (S240). Removing the positive electrode active material may utilize a difference in particle size between the positive electrode active material and the solid electrolyte.

[0042] Preparing the first raw material solution (S210)

[0043] Referring to Fig. 1, a first raw material solution including a positive electrode active material, a solid electrolyte, and a solvent can be prepared (S210) from waste liquid generated in a process of manufacturing an all-solid-state battery.

[0044] The waste liquid generated in the process of manufacturing the above-mentioned all-solid-state battery may be, for example, a cleaning waste liquid generated from cleaning equipment used in the process of manufacturing the above-mentioned positive electrode active material. For example, it may be a cleaning waste liquid generated from cleaning a positive electrode slurry mixing tank. The cleaning waste liquid may have a high viscosity. The solids ratio of the cleaning waste liquid may be 20% or more, 30% or more, or 40% or more. A high solids ratio may mean a high viscosity. The solids ratio of the cleaning waste liquid may be the mass of the solid content contained in the cleaning waste liquid relative to the total mass of the cleaning waste liquid. That is, it may be 'the mass of the solid content contained in the cleaning waste liquid / the total mass of the cleaning waste liquid'. The solid content may include a positive electrode active material, a binder, a conductive agent, and a solid electrolyte.

[0045] Fig. 2 illustrates a positive electrode layer of a solid electrolyte according to one embodiment. Referring to Fig. 2, the positive electrode layer may include a positive electrode current collector (COL) and a positive electrode active material layer. The positive electrode active material layer may include a positive electrode active material (AM), a solid electrolyte (SE), a binder (BND), and a conductive material (CDM). The first raw material solution may include materials included in the positive electrode layer. However, for the convenience of explanation, the positive electrode layer is only used as an example, and the materials included in the first raw material solution are not limited to those derived from the positive electrode layer.

[0046] The positive electrode active material included in the first raw material solution may include a compound represented by the following chemical formula 1:

[0047] [Chemical Formula 1]

[0048] LiM1 a M2 b M3 cM4 d O2

[0049] In the above chemical formula 1, 0≤a≤1, 0≤b≤1, 0≤c≤1, 0≤d≤1 and a+b+c+d=1 may be satisfied, and each of M1, M2, M3 and M4 of the above 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.

[0050] The solid electrolyte included in the first raw material solution may include a sulfide-based solid electrolyte. The sulfide-based solid electrolyte includes, for example, Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, capital letter “Z” represents Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, capital letter “M” is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may include at least one selected from (0≤x≤2).

[0051] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x(0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x (0≤x≤2) may be an argyrodite-type compound including at least one selected from. In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I. The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0052] The solvent included in the first raw material solution may be a solvent that was added when manufacturing the positive electrode active material slurry and remains in small amounts without being completely dried. Alternatively, the solvent included in the first raw material solution may be a cleaning solvent added when cleaning equipment used in the manufacturing process of the positive electrode active material. For example, the solvent included in the first raw material solution may include at least one selected from the group consisting of octyl acetate, octanol, nonyl acetate, nonyl alcohol, heptyl acetate, and heptanol. The solvent included in the first raw material solution may further include at least one selected from the group consisting of heptane, xylene, toluene, and diethylbenzene. The solvent included in the first raw material solution may further include at least one selected from the group consisting of ethylene carbonate, diethyl carbonate, and dimethyl carbonate. The solvent may be included in the organic solvent that is ultimately recovered.

[0053] The first raw material solution may further include a binder and a conductive material. The binder may include, for example, one or more selected from the group consisting of polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. The conductive material may include a carbon-based material. The conductive material may include, for example, one or more selected from the group consisting of graphite, carbon black, acetylene black, Ketjen black, metal powder, carbon nanofibers, and carbon nanotubes.

[0054] As described above, the first raw material solution contains expensive materials for manufacturing all-solid-state batteries. Efficiently separating, recovering, and reusing these materials can help reduce the manufacturing costs of all-solid-state batteries.

[0055]

[0056] Forming a second raw material solution (S220)

[0057] Referring to Fig. 1, a first raw material solution and a viscosity modifier can be mixed to form a second raw material solution (S220).

[0058] Fig. 3 illustrates forming a second raw material solution (SSN2) by mixing a first raw material solution (SSN1) and a viscosity modifier (VCA) (S220). Referring to Fig. 3, the first raw material solution (SSN1) and the viscosity modifier (VCA) can be mixed to further increase the distance between the solids. The solids can be a positive active material (AM), a solid electrolyte (SE), a binder (BND), and a conductive material (CDM). That is, the viscosity modifier can function to lower the solids ratio of the second raw material solution (SSN2).

[0059] When the solids content of the second raw material solution is high, the distance between the solids contained in the second raw material solution may be close. Coagulation may occur due to van der Waals forces. For example, nano-sized binders may coagulate to form aggregates of several tens of micrometers in size. This may reduce the efficiency of the process of separating and recovering the positive electrode active material, solid electrolyte, binder, and conductive material, which is performed after the organic solvent recovery process of the present invention.

[0060] The forming of the second raw material solution may be a process of mixing the first raw material solution and the viscosity modifier so that the solid ratio of the second raw material solution becomes 1% to 30%. Alternatively, the mixing may be a process of mixing so that the solid ratio becomes 1% to 10%. The solid ratio of the second raw material solution may be the mass of the solid content included in the second raw material solution relative to the total mass of the second raw material solution. That is, it may be 'the mass of the solid content included in the second raw material solution / the total mass of the second raw material solution'. The solid content may include a positive electrode active material, a binder, a conductive material, and a solid electrolyte. When the solid ratio of the second raw material solution satisfies the above range, the filtration efficiency can be improved in the subsequent step of 'forming a third raw material solution (S230)'. In addition, the efficiency of the process of separating and recovering the positive electrode active material, the solid electrolyte, the binder, and the conductive material, which is performed after the organic solvent recovery process according to the present invention, can be improved.

[0061] The above viscosity modifier may include an organic solvent recovered by the method of claim 1. That is, the organic solvent recovered by the method of recovering an organic solvent of the present invention may be reused as a viscosity modifier in the organic solvent recovery process of the present invention.

[0062]

[0063] Forming the third raw material solution (S230)

[0064] Referring to Fig. 1, the positive electrode active material can be removed from the second raw material solution to form a third raw material solution (S230).

[0065] Removing the positive electrode active material may utilize the difference in particle size between the positive electrode active material and the solid electrolyte. Referring to FIG. 2, in an all-solid-state battery, the average particle diameter (D50) of the positive electrode active material (AM) may be larger than the average particle diameter (D50) of other solid components. The other solid components may refer to a solid electrolyte (SE), a conductive material (CDM), and / or a binder (BND). This may be a unique characteristic of a typical all-solid-state battery. Since an all-solid-state battery uses a solid electrolyte, it may have structural limitations such as low energy density and poor lithium ion mobility. To overcome this, an all-solid-state battery may typically include an average particle diameter (D50) of other solid components smaller than the average particle diameter (D50) of the positive electrode active material. The method for recovering an organic solvent according to the present invention may utilize the particle size difference that inevitably occurs due to the structure and manufacturing of such an all-solid-state battery.

[0066] Removing the positive electrode active material may include using a filtration device. The filtration device may include one or more of a filtration equipment, a sieving machine, and a hydrocyclone.

[0067] The second raw material solution can be passed through the filtering device. The filtering device can separate the positive electrode active material from the second raw material solution. That is, the positive electrode active material can be removed from the second raw material solution. Finally, a third solution from which the positive electrode active material has been removed can be formed.

[0068] The average particle diameter (D50) of the positive electrode active material may be 8 μm to 50 μm. Alternatively, it may be 10 μm to 50 μm. The average particle diameter (D50) of the solid electrolyte may be 0.01 μm to 5 μm. The average particle diameter (D50) of the conductive material may be smaller than that of the positive electrode active material. The average particle diameter (D50) of the conductive material may be 1 μm or less. The average particle diameter (D50) of the binder may be smaller than that of the positive electrode active material. The average particle diameter (D50) of the binder may be 900 nm or less.

[0069] Removing the positive electrode active material may include removing positive electrode active material having an average particle diameter (D50) greater than 8 μm. Alternatively, it may include removing positive electrode active material having an average particle diameter (D50) greater than 10 μm.

[0070] Forming the third raw material solution (S230) may further include rinsing the positive electrode active material after removing the positive electrode active material. Fig. 4 illustrates rinsing the positive electrode active material. Referring to Fig. 4, a positive electrode active material (AM) and a third raw material solution (SSN3) may be prepared by separating them from the second raw material solution. The positive electrode active material (AM) may be positioned on one side of a filtering device (FTE). The third raw material solution (SSN3) may be positioned on the other side of the filtering device (FTE). The positive electrode active material (AM) may be rinsed with a rinsing solution. The rinsing solution may be an organic solvent (OSV) recovered through a method for recovering an organic solvent according to the present invention. By performing the above rinsing, the positive electrode active material (AM) can be separated more efficiently. That is, other solids mixed in the positive electrode active material (AM) can be washed away once more. The other solids may refer to a solid electrolyte (SE), a conductive material (CDM), and / or a binder (BND).

[0071] FIG. 5 illustrates rinsing a positive electrode active material using a method other than the present invention. Referring to FIG. 5, the rinsing solution may not be an organic solvent recovered through the method for recovering an organic solvent according to the present invention. The rinsing solution may be the second raw material solution (SSN2). When the second raw material solution (SSN2) is used, the separation efficiency of the positive electrode active material (AM) may not be good. That is, other solids may be mixed in the separated positive electrode active material (AM). The other solids may refer to a solid electrolyte (SE), a conductive material (CDM), and / or a binder (BND). This may reduce the efficiency of the process of separating and recovering the positive electrode active material, the solid electrolyte, the binder, and the conductive material, which is performed after the organic solvent recovery process.

[0072] After the organic solvent recovery process according to the present invention, valuable metals can be recovered through a separate valuable metal recovery process. The valuable metals may be lithium (Li), nickel (Ni), cobalt (Co), etc. contained in the positive electrode active material. A typical valuable metal recovery process may include a process of leaching the positive electrode active material in an acid solution. At this time, if a solid electrolyte is mixed with the positive electrode active material, the solid electrolyte may react with moisture and generate toxic substances. Therefore, it may be important to reliably separate the positive electrode active material and the solid electrolyte before the valuable metal recovery process. Furthermore, if an organic solvent is mixed with the positive electrode active material, it may interfere with contact between the positive electrode active material and the acid solution, thereby reducing the efficiency of valuable metal recovery. Therefore, it may be important to reliably separate the positive electrode active material and the organic solvent before the valuable metal recovery process.

[0073]

[0074] Extracting the solvent from the third raw material solution (S240)

[0075] Referring to Fig. 1, the solvent of the third raw material solution can be extracted from the third raw material solution (S240).

[0076] Extracting the solvent of the third raw material solution (S240) may include evaporating and extracting the solvent of the third raw material solution. The solvent of the third raw material solution may include the solvent and / or viscosity modifier contained in the first raw material solution. Any method of evaporation generally used for evaporating a solvent may be applied.

[0077] Finally, through the above process, an organic solvent can be recovered from the waste liquid generated in the process of manufacturing an all-solid-state battery. The organic solvent may include at least one selected from the group consisting of octyl acetate, octanol, nonyl acetate, nonyl alcohol, heptyl acetate, and heptanol. The solvent included in the first raw material solution may further include at least one selected from the group consisting of heptane, xylene, toluene, and diethylbenzene. The solvent included in the first raw material solution may further include at least one selected from the group consisting of ethylene carbonate, diethyl carbonate, and dimethyl carbonate.

[0078] The organic solvent recovered according to the method for recovering the organic solvent of the present invention can be reintroduced into the process for manufacturing the all-solid-state battery. This can reduce the manufacturing cost of the all-solid-state battery.

[0079] The residual solid content remaining after extracting the solvent from the third raw material solution may be additionally recovered through a separate process other than the method for recovering the organic solvent of the present invention. The residual solid content may include a solid electrolyte, a binder, and a conductive material.

[0080]

[0081] Figure 6 is a flowchart illustrating a device for recovering an organic solvent according to the present invention. Referring now to Figure 6, the device for recovering an organic solvent according to the present invention will be described in more detail.

[0082] Device for recovering organic solvents

[0083] Referring to FIG. 6, a device for recovering an organic solvent according to the present invention may include a raw material supply unit; a viscosity control unit; a filtration unit; a solvent extraction unit; a first transport unit; and a second transport unit.

[0084] The raw material supply unit can supply a first raw material solution including a positive electrode active material, a solid electrolyte, and a solvent. The viscosity control unit can control the viscosity of the first raw material solution to form a second raw material solution. The filtering unit can remove the positive electrode active material from the second raw material solution to form a third raw material solution. The filtering unit can include a filter unit and a rinsing unit. The solvent extraction unit can extract the solvent of the third raw material solution from the third raw material solution. The first transport unit can transport the extracted solvent to the viscosity control unit and reuse it. The second transport unit can transport the extracted solvent to the filtering unit and reuse it.

[0085] The above first raw material solution may be a waste solution generated in a process for manufacturing an all-solid-state battery. The device for recovering an organic solvent according to the present invention may further include a third transport unit for transporting the extracted solvent to a process for manufacturing the all-solid-state battery for reuse. The process for manufacturing the all-solid-state battery may be, for example, a process for washing a cathode slurry mixing tank. The organic solvent recovered according to the present invention may be reused as a viscosity modifier, a rinsing solution, and a cathode slurry washing solution. This may reduce the manufacturing cost of an all-solid-state battery.

[0086] The recovered organic solvent may include at least one selected from the group consisting of octyl acetate, octanol, nonyl acetate, nonyl alcohol, heptyl acetate, and heptanol. The solvent included in the first raw material solution may further include at least one selected from the group consisting of heptane, xylene, toluene, and diethylbenzene. The solvent included in the first raw material solution may further include at least one selected from the group consisting of ethylene carbonate, diethyl carbonate, and dimethyl carbonate. The solvent may be included in the organic solvent that is ultimately recovered.

[0087]

[0088] Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are merely exemplary of the present invention, and the present invention is not limited to the following examples.

[0089] Example 1

[0090] During the process of manufacturing an all-solid-state battery, a first raw material solution was prepared from a process of washing a cathode slurry mixing tank. The organic solvent recovered according to the present invention was used as the washing water for washing the tank. The cathode active material contained in the cathode slurry was NCM811, and the solid electrolyte was Li6PS5Cl. The solids content of the obtained washing waste solution was 30.6%.

[0091] The first raw material solution and viscosity modifier were mixed to form a second raw material solution. At this time, the organic solvent recovered according to the present invention was used as the viscosity modifier. The solids ratio of the second raw material solution was 9.5%.

[0092] The second raw material solution was passed through a filter having pores of 8 μm to remove the positive electrode active material from the second raw material solution.

[0093] The positive electrode active material was rinsed twice with a rinsing solution to form a third raw material solution. The organic solvent recovered according to the present invention was used as the rinsing solution. The volume of the rinsing solution used per rinsing was 30% of the volume of the third raw material solution.

[0094] The rinsed positive electrode active material was dried at 80°C for 1 hour to obtain positive electrode active material powder. The results of X-ray diffraction (XRD) analysis for the positive electrode active material powder are shown in Fig. 8.

[0095] The third raw material solution was evaporated to extract the solvent of the third raw material solution. The organic solvent was recovered. The results of X-ray diffraction (XRD) analysis of the residual solid powder after recovery of the organic solvent are shown in Figure 8.

[0096] Comparing the X-ray diffraction (XRD) graph of FIG. 8 with the X-ray diffraction (XRD) graphs of the NCM811 powder and Li6PS5Cl powder of FIG. 7, it can be confirmed that the positive electrode active material powder of Example 1 does not contain a solid electrolyte. That is, it can be confirmed that the organic solvent recovery method according to the present invention has excellent separation efficiency of the positive electrode active material.

[0097] Comparing the X-ray diffraction (XRD) graph of FIG. 9 with the X-ray diffraction (XRD) graphs of the NCM811 powder and Li6PS5Cl powder of FIG. 7, it can be confirmed that the residual solid powder of Example 1 does not contain a positive electrode active material. That is, it can be confirmed that the method for recovering an organic solvent according to the present invention can reliably separate a positive electrode active material and a solid electrolyte.

[0098]

[0099] Comparative Example 1

[0100] During the process of manufacturing an all-solid-state battery, a raw material solution was prepared from the process of washing the cathode slurry mixing tank. The cathode active material contained in the cathode slurry was NCM811, and the solid electrolyte was Li6PS5Cl. The solids content of the obtained washing waste solution was 30.6%.

[0101] The above raw material solution was evaporated to extract the solvent. The results of X-ray diffraction (XRD) analysis of the residual solid powder remaining after extracting the solvent are shown in Figure 10.

[0102] Comparing the X-ray diffraction (XRD) graph of FIG. 10 with the X-ray diffraction (XRD) graphs of the NCM811 powder and Li6PS5Cl powder of FIG. 7, it can be confirmed that the positive electrode active material and the solid electrolyte are mixed in the residual solid powder of Comparative Example 1. That is, it can be confirmed that if the organic solvent recovery method of the present invention is not followed, the positive electrode active material and the solid electrolyte cannot be clearly separated.

[0103]

[0104] Although the preferred 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 patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

1. Preparing a first raw material solution containing a positive electrode active material, a solid electrolyte, and a solvent from waste liquid generated in the process of manufacturing an all-solid-state battery; Forming a second raw material solution by mixing the first raw material solution and the viscosity modifier; Removing the positive electrode active material from the second raw material solution to form a third raw material solution; and Extracting the solvent of the third raw material solution from the third raw material solution; Removing the positive electrode active material utilizes the difference in particle size between the positive electrode active material and the solid electrolyte. Method for recovering organic solvents.

2. In paragraph 1, The waste liquid generated in the process of manufacturing the above all-solid-state battery is Comprising a washing waste liquid generated from washing equipment used in the manufacturing process of the above positive electrode active material, Method for recovering organic solvents.

3. In paragraph 1, The above positive electrode active material comprises a compound represented by the chemical formula 1 below. Method for recovering organic solvents: [Chemical Formula 1] LiM1 a M2 b M3 c M4 d O2 In the above chemical formula 1, 0≤a≤1, 0≤b≤1, 0≤c≤1, 0≤d≤1 and a+b+c+d=1 may be satisfied, and each of M1, M2, M3 and M4 of the above 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. In paragraph 1, The above solid electrolyte comprises a sulfide-based solid electrolyte. Method for recovering organic solvents.

5. In paragraph 1, The above organic solvent is, Containing at least one selected from the group consisting of octyl acetate, octanol, nonyl acetate, nonyl alcohol, heptyl acetate and heptanol, heptane, xylene, toluene, diethylbenzene, ethylene carbonate, diethyl carbonate and dimethyl carbonate. Method for recovering organic solvents.

6. In paragraph 1, The above first raw material solution is, Including further binders and conductive agents, Method for recovering organic solvents.

7. In paragraph 1, The viscosity modifier comprises an organic solvent recovered by the method of claim 1. Method for recovering organic solvents.

8. In paragraph 1, Forming the above second raw material solution is: The first raw material solution and the viscosity modifier are mixed so that the solid ratio of the second raw material solution is 1% to 30%. Method for recovering organic solvents.

9. In paragraph 1, Forming the above second raw material solution is: The first raw material solution and the viscosity modifier are mixed so that the solid ratio of the second raw material solution is 1% to 10%. Method for recovering organic solvents.

10. In paragraph 1, The average particle diameter of the above positive electrode active material is 8㎛ to 50㎛, The average particle size of the above solid electrolyte is 0.01㎛ to 5㎛, Method for recovering organic solvents.

11. In paragraph 1, Removing the above positive electrode active material is Including removing positive electrode active material having an average particle size greater than 8㎛, Method for recovering organic solvents.

12. In paragraph 1, Removing the above positive electrode active material is Including the use of one or more of filtration equipment, sieving machine and hydrocyclone. Method for recovering organic solvents.

13. In paragraph 1, Forming the third raw material solution is as follows: Preparing a positive electrode active material removed from the second raw material solution; and Further comprising rinsing the positive electrode active material with a rinsing solution; Method for recovering organic solvents.

14. In paragraph 13, The above rinsing solution is an organic solvent recovered through the recovery method of paragraph 1. Method for recovering organic solvents.

15. In paragraph 1, Extracting the solvent of the third raw material solution above is as follows: Including extracting by evaporating the solvent of the third raw material solution, Method for recovering organic solvents.

16. In paragraph 1, Further comprising reintroducing the organic solvent recovered through the recovery method of paragraph 1 into the process for manufacturing the all-solid-state battery. Method for recovering organic solvents.

17. A raw material supply unit that supplies a first raw material solution containing a positive electrode active material, a solid electrolyte, and a solvent; A viscosity control unit that controls the viscosity of the first raw material solution to form a second raw material solution; A filtering unit for removing the positive electrode active material from the second raw material solution to form a third raw material solution; A solvent extraction unit that extracts the solvent of the third raw material solution from the third raw material solution; A first transport unit for transporting the extracted solvent to a viscosity control unit for reuse; and A second transport unit for transporting the extracted solvent to the filter unit for reuse; The above filtering unit includes a filter unit and a rinsing unit. A device for recovering organic solvents.

18. In paragraph 17, The above first raw material solution is a waste liquid generated in the process of manufacturing an all-solid-state battery. A device for recovering organic solvents.

19. In paragraph 18, Further comprising a third transport unit for transporting and reusing the extracted solvent to the process of manufacturing the all-solid-state battery. A device for recovering organic solvents.

20. In paragraph 17, The above organic solvent is, Containing at least one selected from the group consisting of octyl acetate, octanol, nonyl acetate, nonyl alcohol, heptyl acetate and heptanol, heptane, xylene, toluene, diethylbenzene, ethylene carbonate, diethyl carbonate and dimethyl carbonate. A device for recovering organic solvents.

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