Method for recovering battery elements from waste slurry

Abstract

The present invention relates to a method for recovering battery elements from waste slurry, the method comprising the steps of: mixing waste slurry, including a sulfide-based solid electrolyte and an organic solvent, with an aqueous alkaline solution; allowing the mixture to separate into layers such that, due to a density difference, the waste slurry forms an upper layer and the alkaline aqueous solution forms a lower layer; after layer separation, allowing the sulfide-based solid electrolyte to move to the lower layer due to the specific gravity thereof; and separating the upper layer to recover the organic solvent and separating the lower layer to recover battery elements contained in the waste slurry.

Description

Method for recovering battery elements from waste slurry

[0001] This relates to a method for recovering battery elements from waste slurry.

[0002] Lithium-ion batteries are widely used as power sources for mobile information terminals such as smartphones and laptops due to their high energy density and portability. Although these batteries are rechargeable and have a relatively long lifespan, they are consumables, and consequently, the amount of waste is on the rise alongside increased usage. Consequently, active research is being conducted on methods to recover and recycle battery components from discarded lithium-ion batteries.

[0003] Lithium-ion battery waste can be classified into two types: liquid waste and solid waste. The former includes waste slurry containing organic solvents from the manufacturing process, while the latter consists of spent batteries.

[0004] In the case of waste batteries, which are solid waste, although the current recovery yield is low, a process is known in which the waste batteries are decomposed after discharge to recover the anodes, and valuable metals are recovered from the recovered anodes through smelting or acid treatment.

[0005] However, when recovering battery components from liquid waste slurry, particularly waste slurry for all-solid-state batteries containing sulfide-based solid electrolytes, there is a problem in that harmful gases such as hydrogen sulfide (H2S) are generated at room temperature or in aqueous solutions due to the characteristics of sulfide-based solid electrolytes.

[0006] Accordingly, there is a need for a method to recover battery components, such as organic solvents and sulfide-based solid electrolytes, from waste slurry while suppressing the generation of harmful gases.

[0007] One embodiment is intended to provide a method for effectively recovering battery elements from waste slurry through a relatively simple process while suppressing the generation of harmful gases.

[0008] In one embodiment, a method for recovering battery elements from waste slurry is provided, comprising the steps of: mixing waste slurry containing a sulfide-based solid electrolyte and an organic solvent with an alkaline aqueous solution; separating the layers such that the waste slurry becomes an upper layer and the alkaline aqueous solution becomes a lower layer due to a difference in density; moving the sulfide-based solid electrolyte to the lower layer by specific gravity after the layer separation; and separating the upper layer to recover the organic solvent and separating the lower layer to recover the battery elements contained in the waste slurry.

[0009] A method for recovering battery elements from waste slurry according to one embodiment can effectively recover battery elements from waste slurry through a relatively simple process while suppressing the generation of harmful gases.

[0010] FIG. 1 is a schematic diagram illustrating a series of processes describing a method for recovering battery elements from waste slurry according to an embodiment.

[0011] Specific embodiments are described below in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0012] The terms used herein are for describing exemplary embodiments only and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0013] Here, "combinations of these" refers to mixtures of components, laminates, composites, copolymers, alloys, blends, reaction products, etc.

[0014] The terms "include," "equip," or "have" used herein are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0015] In the drawings, thicknesses have been enlarged to clearly represent various layers and regions, and the same reference numerals have been used for similar parts throughout the specification. When a part such as a layer, film, region, or plate is described as being "on" or "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between. Conversely, when a part is described as being "immediately on" another part, it means that there is no other part in between.

[0016] In addition, the term “layer” here includes not only shapes formed on the entire surface when viewed in a plan view, but also shapes formed on some surfaces.

[0017] The average particle size can be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by using transmission electron microscope or scanning electron microscope images. Alternatively, the average particle size value can be obtained by measuring using dynamic light scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Unless otherwise defined, the average particle size is the diameter (D) of the particle at which the cumulative volume in the particle size distribution is 50 volume percent. 50 It may mean ). In addition, unless otherwise defined, the average particle size is obtained by measuring the size (diameter or length of the major axis) of approximately 20 randomly selected particles from scanning electron microscope images to obtain a particle size distribution, and the diameter (D) of the particle with a cumulative volume of 50% in the said particle size distribution. 50It may be that ) was taken as the average particle size.

[0018] Here, “or” is not interpreted in an exclusive sense; for example, “A or B” is interpreted to include A, B, A+B, etc.

[0019] The term “metal” is interpreted as a concept that includes ordinary metals, transition metals, and metalloids (semimetals).

[0020] Method for recovering battery elements from waste slurry

[0021] A waste slurry according to one embodiment is characterized by containing a sulfide-based solid electrolyte, and more specifically, a method for recovering a battery element from a waste slurry according to one embodiment includes the step of mixing a waste slurry containing a sulfide-based solid electrolyte and an organic solvent with an alkaline aqueous solution.

[0022] In the step of mixing the waste slurry and the alkaline aqueous solution, the volume ratio of the waste slurry and the alkaline aqueous solution is not specifically limited, but may be, for example, 20:80 to 80:20. For example, it may be 30:70 to 80:20, 40:60 to 80:20, 50:50 to 80:20, or 60:40 to 80:20. When the volume ratio of the waste slurry and the alkaline aqueous solution satisfies the above range, efficient separation is possible without generating harmful gases such as hydrogen sulfide (H2S).

[0023] The step of mixing the waste slurry and the alkaline aqueous solution may be carried out at 25°C to 70°C for 10 minutes to 10 hours. For example, the temperature of the mixing step may be 30°C to 60°C or 30°C to 50°C. Additionally, the time of the mixing step may be 30 minutes to 5 hours, 30 minutes to 3 hours, or 30 minutes to 1 hour. By carrying out the step of mixing the waste slurry and the alkaline aqueous solution at temperatures and times within the above ranges, the mixing effect between the solvent in the waste slurry and the alkaline aqueous solution can be enhanced.

[0024] The above mixing method is not specifically limited, but, for example, ultrasonic irradiation or mechanical stirring may be used. That is, ultrasonic waves may be applied to the mixture of waste slurry and alkaline aqueous solution, or the mixture may be mechanically stirred.

[0025] As mentioned above, sulfide-based solid electrolytes generally generate harmful gases such as hydrogen sulfide (H2S) immediately at room temperature or in aqueous solution, so caution is required when recovering battery components from waste slurry containing them.

[0026] When waste sludge is separated into solid and liquid phases by methods such as filtering, sulfide-based solid electrolytes are exposed to air or water, generating harmful gases such as hydrogen sulfide (H2S). Therefore, there is a need for a method to effectively separate and recover battery components while maintaining the sulfide-based solid electrolytes in a stabilized state without exposing them to air.

[0027] When using general aqueous solutions such as water, sulfide-based solid electrolytes may dissolve, but the inventors [have] hydroxide ions (OH - It was confirmed that using an alkaline aqueous solution containing ) suppresses the generation of harmful gases while dissolving sulfide-based solid electrolytes, and that it is possible to effectively separate harmful gases while suppressing their generation through a simple process of mixing waste slurry and an alkaline aqueous solution.

[0028] Such waste slurry can be, for example, a positive electrode slurry for all-solid-state batteries.

[0029] In this case, the waste slurry may further contain an anode active material in addition to the aforementioned sulfide-based solid electrolyte and organic solvent.

[0030] The above-mentioned positive active material may be applied without limitation as long as it is commonly used in all-solid-state secondary batteries. For example, the above-mentioned positive active material may be a compound capable of reversible intercalation and deintercalation of lithium, and may include a compound represented by any one of the following chemical formulas.

[0031] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5); 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 E 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a E 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 D α (0.90 ≤ a ≤1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 <α ≤ 2); Li a Ni 1-b-c Co b X c O 2-α T α(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mr b X c D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mr b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mr b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b HAVE BEEN c G d O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mr d G e O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤0.5, 0.001 ≤ 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); Lia Mn 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn2G b 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); QO2; QS2; LiQS2; V2O5; LiV2O5; LiZO2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2); Li a FePO4(0.90 ≤ a ≤ 1.8).

[0032] In the above chemical formulas, A is selected from Ni, Co, Mn, and combinations thereof; X is selected from Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is selected from O, F, S, P, and combinations thereof; E is selected from Co, Mn, and combinations thereof; T is selected from F, S, P, and combinations thereof; G is selected from Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; Q is selected from Ti, Mo, Mn, and combinations thereof; Z is selected from Cr, V, Fe, Sc, Y, and combinations thereof; and J is selected from V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

[0033] The above-mentioned positive electrode active material may be, for example, lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt oxide (NC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium nickel manganese oxide (NM), lithium manganese oxide (LMO), or lithium iron phosphate oxide (LFP).

[0034] The above positive active material may include, for example, a lithium nickel-based oxide represented by the following chemical formula 1, a lithium cobalt-based oxide represented by the following chemical formula 2, a lithium iron phosphate-based compound represented by the following chemical formula 3, a cobalt-free lithium nickel-manganese-based oxide represented by the following chemical formula 4, or a combination thereof.

[0035] [Chemical Formula 1]

[0036] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0037] In the above chemical formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1, and 0≤b1≤0.1, and M 1 and M 2 Each is independently one or more elements selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zn, and Zr, and X is one or more elements selected from F, P, and S.

[0038] In the above chemical formula 1, 0.6≤x1≤1, 0≤y1≤0.4, and 0≤z1≤0.4, or 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.2.

[0039] [Chemical Formula 2]

[0040] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0041] In the above chemical formula 2, 0.9≤a2≤1.8, 0.7≤x2≤1, 0≤y2≤0.3, 0.9≤x2+y2≤1.1, and 0≤b2≤0.1, and M 3is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from F, P, and S.

[0042] [Chemical Formula 3]

[0043] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0044] In the above chemical formula 3, 0.9≤a3≤1.8, 0.6≤x3≤1, 0≤y3≤0.4, and 0≤b3≤0.1, and M 4 is one or more elements selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from F, P, and S.

[0045] [Chemical Formula 4]

[0046] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0047] In the above chemical formula 4, 0.9≤a2≤1.8, 0.8≤x4<1, 0 <y4≤0.2, 0≤z4≤0.2, 0.9≤x4+y4+z4≤1.1, 및 0≤b4≤0.1이고 M 5 is one or more elements selected from Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from F, P, and S.

[0048] Average particle size (D of the above positive active material) 50) may be 1 μm to 25 μm, for example, 3 μm to 25 μm, 1 μm to 20 μm, 1 μm to 18 μm, 3 μm to 15 μm, or 5 μm to 15 μm. As an example, the anode active material has an average particle size (D 50 Fine particles with a diameter of 1 μm to 9 μm and an average particle size (D 50 ) may include a coarse particle with a size of 10 μm to 25 μm. Here, the average particle size may be obtained by selecting approximately 20 particles from a scanning electron microscope image of the positive electrode active material, measuring their particle sizes (diameter, or major axis, or length of the major axis), obtaining a particle size distribution, and taking the diameter of the particle with a cumulative volume of 50 volume% from the particle size distribution as the average particle size.

[0049] The above positive active material may be in the form of secondary particles formed by the aggregation of a plurality of primary particles, or in the form of single particles. In addition, the above positive active material may be spherical or have a shape close to spherical, or may be polyhedral or amorphous.

[0050] Meanwhile, the above-mentioned positive electrode active material may include a buffer layer on the particle surface. As an example, the buffer layer may include a lithium metal oxide, wherein the metal may be one or more elements selected from, for example, Al, B, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, and Zr.

[0051] The above waste slurry may optionally further include a binder, a conductive material, or a combination thereof.

[0052] The above binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples include polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but are not limited thereto.

[0053] The above conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.; metal-based materials in the form of metal powder or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or conductive materials comprising a mixture thereof.

[0054] As long as the organic solvent in the aforementioned waste slurry does not react with the sulfide-based solid electrolyte used in general all-solid-state secondary batteries, its type may be used without restriction.

[0055] In one embodiment, the organic solvent may include octyl acetate, isobutylyl isobutylate, xylene, toluene, benzene, hexane, tetralin, triethyl phosphate, 2-chloro-p-xylene, 1,2-dichlorobenzene, hexyl butyrate, or a combination thereof.

[0056] The sulfide-based solid electrolyte contained in the above waste slurry can exist in a stabilized state by dissolving it in an alkaline aqueous solution. In other words, the sulfide-based solid electrolyte can exist in a stabilized state by dissolving it in an alkaline aqueous solution located in the lower layer, thereby preventing exposure to air and thus preventing the generation of harmful gases such as hydrogen sulfide (H2S).

[0057] Therefore, the above alkaline aqueous solution can be one that can stabilize the sulfide-based solid electrolyte, and has a high density when mixed with waste slurry, allowing the layer to be separated into the lower layer.

[0058] These alkaline aqueous solutions dissolve in water to form hydroxide ions (OH⁻). - It means emitting ).

[0059] The above alkaline aqueous solution can be represented by the following chemical formula 5.

[0060] [Chemical Formula 5]

[0061] A(OH) n

[0062] In Chemical Formula 5, A is an alkali metal or an alkyl earth metal, and n represents the valence of A.

[0063] The alkaline aqueous solution represented by the above chemical formula 5 may include, for example, sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), or a combination thereof.

[0064] The above alkaline aqueous solution may have a pH of 10 or higher. For example, the pH of the above alkaline aqueous solution may be 10 or higher, 11 or higher, 12 or higher, or 13 or higher, and may be 14 or lower. When the pH of the alkaline aqueous solution satisfies the above range, the generation of hydrogen sulfide by the sulfide-based solid electrolyte can be effectively suppressed.

[0065] The above sulfide-based solid electrolyte is, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element, e.g., I or Cl), 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 and n are integers, respectively, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are integers, and M is P, Si, Ge, B, Al, Ga or In), or may include a combination thereof.

[0066] Such sulfide-based solid electrolytes may be obtained, for example, by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10 or 50:50 to 80:20 and optionally heat-treating. Additionally, SiS2, GeS2, B2S3, etc., may be included as other components to further improve ionic conductivity.

[0067] For example, the sulfide-based solid electrolyte may include an argyrodite-type sulfide. The argyrodite-type sulfide is, for example, Li a M b P c S d A e It can be expressed by the chemical formula (where a, b, c, d, and e are all between 0 and 12, M is Ge, Sn, Si, or a combination thereof, and A is F, Cl, Br, or I), and as a specific example, Li 7-x PS 6-x A xIt can be expressed by the chemical formula (where x is 0.2 or greater and 1.8 or less, and A is F, Cl, Br, or I). Specifically, the azirodite-type sulfide is Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0068] A azirodite-type sulfide-based solid electrolyte may include, for example, a compound represented by Chemical Formula 21 below.

[0069] [Chemical Formula 21]

[0070] (Li a M 1 b M 2 c )(P d M 3 e )(S f M 4 g )X h

[0071] In the above chemical formula 21, 4≤a≤8, and M 1 is Mg, Ca, Cu, Ag, or a combination thereof, 0≤b<0.5, and M 2 is Na, K, or a combination thereof, 0≤c<0.5, and M 3 is Sn, Zn, Si, Sb, Ge, or a combination thereof, and 0 <d<4, 0≤e<1 이고, M 4 is N, O, SO n , or a combination thereof, 1.5≤n≤5, 3≤f≤12, 0≤g<2, X is F, Cl, Br, I, or a combination thereof, and 0≤h≤2.

[0072] For example, in Chemical Formula 21, a halide element (X) may be required to be included, in which case 0 <h≤2로 표시될 수 있다. 일 예로 화학식 21에 M 1An element may be required, in which case 0 <b<0.5로 표시될 수 있다. 화학식 21에서 M 3 can be understood as an element substituted in the P position, and 0 <e<1일 수 있다. 화학식 21에서 M 4 is substituted in the S position, for example, 0 <g<2일 수 있으며 S의 비율인 f는 예를 들어 3≤f≤7일 수 있다. M 4 ga SO n In the case of SO n It can be, for example, S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4, or SO5, and as an example, it can be SO4.

[0073] For example, in chemical formula 21, a+b+c+h=7, d+e=1, and f+g+h=6.

[0074] As a specific example, azirodite-type sulfide-based solid electrolytes include Li3PS4 and Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 , Li 5.75 PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )PS 4.75 Cl 1.25 , (Li 5.72 Cu 0.03 )PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.70 (SO4) 0.05 )Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.60 (SO4) 0.15 )Cl 1.25 , (Li 5.72 Cu 0.03 )P(S4.725 (SO4) 0.025 )Cl 1.25 , (Li 5.72 Na 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , Li 5.75 P(S 4.725 (SO4) 0.025 )Cl 1.25 , or a combination thereof may be included, but is not limited thereto.

[0075] The above sulfide-based solid electrolyte is in the form of particles, and the average particle size (D) of the particles 50 ) may be 5.0 μm or less, for example, 0.1 μm to 5.0 μm, 0.5 μm to 5.0 μm, 0.5 μm to 4.0 μm, 0.5 μm to 3.0 μm, 0.5 μm to 2.0 μm, or 0.5 μm to 1.0 μm. The solid electrolyte may be fine particles of 0.1 μm to 1.9 μm, coarse particles of 2.0 μm to 5.0 μm, or a mixture thereof. The average particle size of the sulfide-based solid electrolyte particles may be measured using electron microscope images, for example, by measuring the size (diameter or length of the major axis) of about 20 particles in scanning electron microscope images to obtain a particle size distribution, where D 50 It could be that it was calculated.

[0076] A method for recovering battery elements from waste slurry according to one embodiment further includes the step of mixing the aforementioned waste slurry and an alkaline aqueous solution, and then separating the layers such that the waste slurry becomes the upper layer and the alkaline aqueous solution becomes the lower layer due to a difference in density.

[0077] In the above waste slurry, the aforementioned battery elements are dispersed within an organic solvent. Since this organic solvent typically has a lower density than an alkaline aqueous solution, the waste slurry containing the organic solvent is separated into an upper layer and the alkaline aqueous solution into a lower layer due to the difference in density.

[0078] A method for recovering battery elements from waste slurry according to one embodiment further includes the step of moving a sulfide-based solid electrolyte to a lower layer by specific gravity after layer separation.

[0079] As described above, due to the difference in density between the organic solvent and the alkaline aqueous solution in the waste slurry, the waste slurry is separated into an upper layer and the alkaline aqueous solution into a lower layer. The sulfide-based solid electrolyte present in the waste slurry moves to the alkaline aqueous solution in the lower layer due to specific gravity, thereby stabilizing the sulfide-based solid electrolyte while not being exposed to the outside, thus completely suppressing the generation of harmful gases such as hydrogen sulfide (H2S).

[0080] The step of the sulfide-based solid electrolyte moving to the lower layer by specific gravity after layer separation may take 10 minutes to 10 hours. For example, it may take 1 hour to 9 hours, 2 hours to 8 hours, or 3 hours to 7 hours.

[0081] In addition to the above-mentioned sulfide-based solid electrolyte, the positive active material, binder, conductive material, or combination thereof that may be included in the waste slurry can also move to the lower layer of the alkaline aqueous solution, just like the sulfide-based solid electrolyte.

[0082] In one example, only an organic solvent may be present in the upper layer, and other battery elements such as a sulfide-based solid electrolyte and a positive electrode active material may be present in the lower layer along with an alkaline aqueous solution.

[0083] A method for recovering battery elements from waste slurry according to one embodiment further includes the step of separating the upper layer to recover an organic solvent and separating the lower layer to recover battery elements contained in the waste slurry.

[0084] A method for recovering battery elements from waste slurry according to one embodiment allows for the recovery of high-quality organic solvent remaining in the upper layer as battery elements, such as a sulfide-based solid electrolyte and a positive electrode active material, within the waste slurry move to the lower layer according to their specific gravity, and the recovered organic solvent can be recycled during the manufacture of an all-solid-state battery.

[0085] The above method may further include a step of separating and recovering the positive active material, sulfide-based solid electrolyte, binder, and / or conductive material present in the lower layer.

[0086] The positive active material, sulfide-based solid electrolyte, binder, and / or conductive material present in the lower layer are not specifically limited as long as there is a method to recover each element, and can be recovered according to known methods.

[0087] For example, the positive active material, sulfide-based solid electrolyte, binder, and / or conductive material present in the lower layer can be recovered using solid-liquid separation. For example, the above solid-liquid separation method may use a filter press, centrifugal separation, a coagulant, etc.

[0088] Embodiments of the present invention are described below. However, the embodiments described below are merely examples of the present invention, and the present invention is not limited to the embodiments described below.

[0089] Examples

[0090] Washing waste liquid containing anode slurry was obtained during the anode manufacturing process. The solid content of the obtained washing waste liquid was 60%.

[0091] Octyl acetate as an organic solvent, Li6PS5Cl as a sulfide-based solid electrolyte, and LiNi as an anode active material. 0.945 Co 0.04 Al 0.015 The above anode slurry containing O2 was mixed with an alkaline aqueous solution containing NaOH with a pH of about 12.

[0092] At this time, due to the difference in density, the anode slurry was separated into an upper layer and the alkaline aqueous solution into a lower layer, and after the separation, the solid components in the upper layer moved to the alkaline aqueous solution in the lower layer according to specific gravity.

[0093] As a result of leaving it for 1 hour after moving, the positive active material and the sulfide-based solid electrolyte completely moved to the lower layer, which is an alkaline aqueous solution, and due to the organic solvent present in the upper layer, the sulfide-based solid electrolyte suppressed the generation of harmful gas (H2S) due to contact with oxygen.

[0094] Subsequently, the organic solvent present in the upper layer was separated and recovered, while the stabilized sulfide-based solid electrolyte and cathode active material present in the lower layer were separated and obtained using a filter press.

[0095] A series of processes describing a method for recovering battery elements from waste slurry according to the above embodiment is illustrated in FIG. 1. Referring to FIG. 1, (A) represents a step of mixing waste slurry (1) and an alkaline aqueous solution (3); (B) represents a step of separating waste slurry (1) and an alkaline aqueous solution (3) into an upper layer and a lower layer, respectively, due to a difference in density; (C) represents a step of moving solid components present in the upper layer (e.g., a sulfide-based solid electrolyte (5) and a positive active material (4)) to the lower layer, an alkaline aqueous solution, due to a difference in specific gravity; and (D) represents a step of separating and recovering the organic solvent (2) in the upper layer.

[0096]

[0097] Although preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concepts defined in the following claims are also included within the scope of the present invention.

[0098] [Explanation of the symbol]

[0099] 1: Waste slurry 2: Organic solvent

[0100] 3: Alkaline aqueous solution 4: Positive electrode active material

[0101] 5: Solid electrolyte

Claims

1. A step of mixing a waste slurry containing a sulfide-based solid electrolyte and an organic solvent with an alkaline aqueous solution; A step in which the layers are separated, with the waste slurry forming the upper layer and the alkaline aqueous solution forming the lower layer due to a difference in density; A step in which the sulfide-based solid electrolyte moves to the lower layer due to specific gravity after layer separation; and A step of separating the upper layer to recover the organic solvent and separating the lower layer to recover the battery elements contained in the waste slurry; including, Method for recovering battery elements from waste slurry.

2. In Paragraph 1, The above waste slurry further comprises a positive electrode active material, Method for recovering battery elements from waste slurry.

3. In Paragraph 1, The above waste slurry further comprises a binder, a conductive material, or a combination thereof, Method for recovering battery elements from waste slurry.

4. In Paragraph 1, The above organic solvent comprises octyl acetate, isobutyryl isobutyrate, xylene, toluene, benzene, hexane, tetralin, triethyl phosphate, 2-chloro-p-xylene, 1,2-dichlorobenzene, hexyl butyrate, or a combination thereof. Method for recovering battery elements from waste slurry.

5. In Paragraph 1, The above alkaline aqueous solution is represented by the following chemical formula 5, Method for recovering battery elements from waste slurry: [Chemical Formula 5] A(OH) n In Chemical Formula 5, A is an alkali metal or an alkyl earth metal, and n represents the valence of A.

6. In Paragraph 1, The above alkaline aqueous solution has a pH of 10 or higher, Method for recovering battery elements from waste slurry.

7. In Paragraph 1, The above sulfide-based solid electrolyte comprises an azirodite-type sulfide, Method for recovering battery elements from waste slurry.

8. In Paragraph 7, The above azirodite-type sulfide is represented by the following chemical formula 21, Method for recovering battery elements from waste slurry: [Chemical Formula 21] (Li a M 1 b M 2 c (P) d M 3 e )(S f M 4 g )X h In the above chemical formula 21, 4≤a≤8, and M 1 is Mg, Ca, Cu, Ag, or a combination thereof, 0≤b<0.5, and M 2 is Na, K, or a combination thereof, 0≤c<0.5, and M 3 is Sn, Zn, Si, Sb, Ge, or a combination thereof, and 0 <d<4, 0≤e<1 이고, M 4 is N, O, SO n , or a combination thereof, 1.5≤n≤5, 3≤f≤12, 0≤g<2, X is F, Cl, Br, I, or a combination thereof, and 0≤h≤2.

9. In Paragraph 1, A method for recovering battery elements from waste slurry, wherein, in the step of mixing the waste slurry and the alkaline aqueous solution, the volume ratio of the waste slurry to the alkaline aqueous solution is 20:80 to 80:

20.

10. In Paragraph 1, A method for recovering battery elements from waste slurry, wherein the step of mixing the waste slurry and the alkaline aqueous solution is carried out at 25°C to 70°C for 10 minutes to 10 hours.

11. In Paragraph 1, A method for recovering battery elements from waste slurry, wherein the step of separating the waste slurry and the alkaline aqueous solution into layers takes 10 minutes to 5 hours.

12. In Paragraph 1, A method for recovering battery elements from waste slurry, wherein the step of moving the sulfide-based solid electrolyte to the lower layer by specific gravity after layer separation takes 10 minutes to 10 hours.

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