Battery material manufacturing method

Abstract

To provide a method for manufacturing a battery material in which the recovery rate of valuable metals is improved.SOLUTION: The method for manufacturing a battery material disclosed herein includes: a preparation step of preparing a recovery target containing at least one of Ni and Co; an acid leaching step of immersing the recovery target in an acid solution and obtaining an acid leachate; an ammine complex generation step of mixing an ammonia solution containing ammonium ions with the acid leachate to generate a metal solution containing an ammine complex of at least one of Ni and Co; and a solid-liquid separation step of obtaining the metal solution by a solid-liquid separation.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The technology disclosed herein relates to a method for producing battery materials. [Background technology]

[0002] Lithium-ion secondary batteries are widely used in various fields. These lithium-ion secondary batteries use various materials containing valuable metals such as Ni and Co. For example, lithium transition metal composite oxides such as lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, and lithium nickel cobalt manganese composite oxide are used as the positive electrode active material. Furthermore, aluminum or the like is used as the positive electrode core.

[0003] In recent years, development of recovery technologies has been progressing for recovering valuable metals from used batteries and process scraps and reusing them as battery materials. For example, Patent Document 1 discloses an example of a recovery technology for positive electrode plates. As disclosed in Patent Document 1, conventional positive electrode plate recovery technologies involve leaching the object to be recovered (lithium-ion battery scrap) with acid, neutralizing the leaching solution obtained by the leaching, and removing at least a portion of the aluminum ions from the leaching solution to obtain a neutralized solution. Furthermore, the recovery method described in Patent Document 1 includes an extraction step in which the neutralized solution is subjected to solvent extraction to extract the remaining aluminum ions from the neutralized solution. It is disclosed that this allows cobalt (Co) and / or nickel (Ni) to be recovered from the extraction residue from which aluminum has been removed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-164971 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the higher the pH of the neutralization solution, the more rapidly aluminum precipitates, while some valuable metals (Ni and / or Co) also begin to precipitate as precipitates. Therefore, in conventional techniques, it is not possible to increase the pH of the neutralization solution, and aluminum cannot be sufficiently removed from the neutralization solution. Therefore, the technique described in Patent Document 1 requires an extraction step to remove aluminum from the neutralization solution, which increases the number of steps and leads to a loss of valuable metals (Ni and / or Co) in recovery.

[0006] The present disclosure has been made in view of the above circumstances, and aims to provide a method for producing a battery material with an improved recovery rate of valuable metals (Ni and / or Co). [Means for solving the problem]

[0007] To address the above-mentioned problems, a method for producing a battery material (hereinafter also simply referred to as "production method") having the following configuration is provided.

[0008] The method for producing a battery material disclosed herein includes a preparation step of preparing a recovery target containing at least one of Ni and Co; an acid leaching step of immersing the recovery target in an acid solution to obtain an acid leaching solution; an ammine complex formation step of mixing an ammonia solution containing ammonium ions with the acid leaching solution to produce a metal solution containing an ammine complex of at least one of Ni and Co; and a solid-liquid separation step of obtaining the metal solution by solid-liquid separation.

[0009] In the manufacturing method having the above configuration, a metal solution containing an ammine complex of Ni and / or Co can be obtained by subjecting the acid leachate to an ammine complex formation step, thereby improving the recovery rate of valuable metals from the target. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a vertical cross-sectional view schematically showing the internal structure of a lithium ion secondary battery. [Figure 2]FIG. 2 is a perspective view schematically showing an electrode body of the lithium ion secondary battery shown in FIG. [Figure 3] FIG. 3 is a flowchart illustrating the method for producing a battery material according to the first embodiment. [Figure 4] FIG. 4 is a flowchart illustrating in detail the preparation steps in FIG. [Figure 5] FIG. 5 is a flowchart illustrating a method for producing a battery material according to the second embodiment. [Figure 6] FIG. 6 is a flow chart illustrating in detail the solvent extraction step according to the second embodiment. [Figure 7] FIG. 7 is a flowchart illustrating a method for producing a battery material according to the third embodiment. [Figure 8] FIG. 8 is a flowchart illustrating in detail the preparation process according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the technology disclosed herein will be described with reference to the drawings. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the technology disclosed herein can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the contents disclosed in this specification and common technical knowledge in the relevant field. Furthermore, the expression "A to B" indicating a range in this specification means not less than A and not more than B, and also encompasses the meanings of "preferably greater than A" and "preferably smaller than B."

[0012] 1. Items subject to recall The method for producing a battery material according to this embodiment produces a battery material (typically, a material for a positive electrode active material of a lithium ion secondary battery, a precursor for a positive electrode active material, or a positive electrode active material) by recovering valuable metals such as Ni and Co from a predetermined object to be recovered. An example of the object to be recovered here is a used lithium ion secondary battery. This lithium ion secondary battery will be specifically described below. FIG. 1 is a vertical cross-sectional view schematically showing the internal structure of a lithium ion secondary battery. FIG. 2 is a perspective view schematically showing an electrode body of the lithium ion secondary battery shown in FIG. 1.

[0013] As shown in FIG. 1, the lithium ion secondary battery 1 includes a case 10, an electrode assembly 20, and an electrolyte (not shown).

[0014] (1) Case The case 10 is a box-shaped container. The case 10 contains an electrode assembly 20 and an electrolyte. The case 10 is made of, for example, a metal material (such as aluminum (Al)) having a certain strength. A positive electrode terminal 12 and a negative electrode terminal 14 are attached to the case 10. The positive electrode terminal 12 and the negative electrode terminal 14 are connected to the electrode assembly 20 inside the case 10. Specifically, the positive electrode terminal 12 is connected to a positive electrode plate 30 (see FIG. 2) of the electrode assembly 20. The positive electrode terminal 12 is made of aluminum (Al) or the like. On the other hand, the negative electrode terminal 14 is connected to a negative electrode plate 40 of the electrode assembly 20. The negative electrode terminal 14 is made of copper (Cu) or the like.

[0015] (2) Electrode body The electrode body 20 is a power generating element of the lithium ion secondary battery 1. As shown in FIG. 2, the electrode body 20 includes a positive electrode plate 30, a negative electrode plate 40, and a separator 50. The electrode body 20 shown in FIG. 2 is a wound electrode body. This wound electrode body is produced by stacking the positive electrode plate 30, the negative electrode plate 40, and the separator 50 to form a long strip-shaped laminate, and then winding the laminate. However, the structure of the electrode body 20 is not particularly limited, and may be any other conventionally known structure (such as a laminated electrode body).

[0016] The positive electrode plate 30 includes a positive electrode core 32, which is a conductive metal foil, and a positive electrode active material layer 34 applied to the surface of the positive electrode core 32. The positive electrode core 32 is made of aluminum (Al) or the like. The positive electrode active material layer 34 is a composite layer containing a positive electrode active material, a conductive material, a binder, and the like. The positive electrode active material is a lithium transition metal composite oxide containing at least one of nickel (Ni) and cobalt (Co). Examples of such lithium transition metal composite oxides include lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel manganese composite oxide, lithium manganese cobalt composite oxide, lithium nickel cobalt composite oxide, and lithium nickel manganese cobalt composite oxide. The production method according to this embodiment enables efficient recovery of Ni and / or Co from a recovery target containing such a lithium transition metal composite oxide. Examples of conductive materials include carbon materials such as acetylene black and graphite. Examples of binders include resin materials such as polyvinylidene fluoride (PVdF).

[0017] On the other hand, the negative electrode plate 40 includes a negative electrode core 42, which is a conductive metal foil, and a negative electrode active material layer 44 applied to the surface of the negative electrode core 42. Copper (Cu) or the like is used for the negative electrode core 42. The negative electrode active material layer 44 is a composite layer containing a negative electrode active material, a binder, a thickener, and the like. Examples of negative electrode active materials include carbon materials such as graphite, hard carbon, and soft carbon. Other examples of negative electrode active materials include lithium titanate (LTO), silicon carbide, a composite containing carbon and silicon, and silicon oxide (SiO X Examples of binders include resin materials such as styrene butadiene rubber (SBR). Examples of thickeners include resin materials such as carboxymethyl cellulose (CMC).

[0018] The separator 50 is an insulating sheet interposed between the positive electrode plate 30 and the negative electrode plate 40. For example, a resin material such as polyethylene (PE), polypropylene (PP), polyester, cellulose, or polyamide is used for the separator 50. A heat-resistant layer containing an inorganic filler may be formed on the surface of the separator 50. Examples of such inorganic fillers include inorganic oxides such as aluminum oxide, magnesium oxide, silicon oxide, and titanium oxide; nitrides such as aluminum nitride and silicon nitride; metal hydroxides such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide; and clay minerals such as mica, talc, boehmite, zeolite, apatite, and kaolin.

[0019] (3) Electrolyte The electrolyte is present between the positive electrode plate 30 and the negative electrode plate 40. This allows charge carriers (Li ions) to move between the positive electrode plate 30 and the negative electrode plate 40. Examples of the electrolyte include a non-aqueous electrolyte solution and a gel electrolyte. Note that the electrolyte may be any electrolyte that can be used in a lithium ion secondary battery without any particular limitation, and does not limit the technology disclosed herein.

[0020] The lithium-ion secondary battery 1 has been described above as an example of a material to be collected in the manufacturing method according to this embodiment. However, the manufacturing method disclosed herein is not limited to a method in which the lithium-ion secondary battery 1 having the above-described configuration is collected. For example, at a manufacturing site for lithium-ion secondary batteries, a portion of the positive electrode plate may be removed when an electrode assembly is fabricated. This removed portion of the positive electrode plate (process scrap) may also contain Ni or Co and therefore may be collected in the manufacturing method disclosed herein. Furthermore, at a manufacturing site for lithium-ion secondary batteries, some defect may occur in the electrode assembly after fabrication, rendering it unusable for a product. Such an electrode assembly may also be collected because it may contain Ni or Co. In other words, the material to be collected in the manufacturing method disclosed herein may contain at least one of Ni and Co as a valuable metal, and is not particularly limited to a specific structure.

[0021] 2. Battery material manufacturing method A method for producing a battery material according to this embodiment will be described below. Fig. 3 is a flowchart illustrating the production method according to the first embodiment. Fig. 4 is a flowchart illustrating in detail the preparation steps in Fig. 3.

[0022] First Embodiment As shown in Figure 3, the method for producing a battery material according to the first embodiment includes a preparation step S10, an acid leaching step S20, an ammine complex formation step S30, and a solid-liquid separation step S40. The method for producing a battery material disclosed herein may further include a precursor preparation step S50 and an active material formation step S60. The production method disclosed herein may further include other steps at any stage, and the remaining production process may be the same as conventional. Each step will be described below.

[0023] (1) Preparation process S10 In the preparation step S10, a recovery target containing at least one of Ni and Co as a valuable metal is prepared. Although not particularly limited, the preparation step S10 may include a recovery target preparation step S11, a heating step S12, and a sorting step S18, as shown in Fig. 4. These steps will be described in detail below.

[0024] (1-1) Collection target preparation process S11 In the collection target preparation step S11, collection targets are prepared. As described above, the "collection targets" in the technology disclosed herein may contain at least one of Ni and Co as a valuable metal. In other words, collection targets are not limited to completed lithium-ion secondary batteries, but also include process scraps and defective parts (electrode bodies, etc.). Details of collection targets have already been explained, so a duplicate explanation will be omitted.

[0025] (1-2) Heating process S12 In the heating step S12, the object to be recovered is heated at a predetermined temperature. This removes liquid components (such as electrolyte) from the object to be recovered and carbonizes resin components (such as binders and separators). Furthermore, when a charged lithium-ion secondary battery 1 is to be recovered, the heating step S12 can be performed to stop the battery's function. This allows subsequent steps to be performed safely. The method for the heating step S12 can be any technique used in conventional recovery techniques without any particular limitations, and is not a feature of the technology disclosed herein, so a detailed description will be omitted.

[0026] The heating step S12 is not essential and can be omitted as needed. For example, there are cases where the recovery target, such as process waste of the positive electrode plate 30, which does not require removal of liquid components and does not require the battery to be stopped, is prepared in the preparation step S10. In this case, valuable metals can be recovered efficiently even if the heating step S12 is omitted.

[0027] (1-3) Sorting process S18 In the sorting step S18, each component contained in the material to be collected is sorted. The sorting step S18 can be performed by a conventionally known method, such as by sieving or visual inspection. For example, if the material to be collected is a process waste of a positive electrode plate 30, the positive electrode substrate 32 may be selected from the process waste and removed from the material to be collected. If the material to be collected is an electrode assembly 20, the negative electrode plate 40 may also be removed from the material to be collected in addition to the positive electrode substrate 32. Furthermore, if the material to be collected is a lithium-ion secondary battery 1, the case 10 may also be removed from the material to be collected in addition to the positive electrode substrate 32 and negative electrode plate 40. This reduces the content of other metals (e.g., Al, Cu) in the material to be collected, which contributes to improving the recovery efficiency of valuable metals (Co, Ni).

[0028] In the sorting step S18, the objects to be collected may be crushed as needed. This can improve the efficiency of sorting each component. For example, if the objects to be collected are lithium-ion secondary batteries 1, it is advisable to crush the case 10 and the electrode assembly 20. This makes it easier to remove the case 10, the positive electrode core 32, and the negative electrode plate 40 from the objects to be collected.

[0029] Furthermore, the sorting step S18 is not intended to completely remove other metal components such as Al and Cu from the object to be recovered. As will be described in detail later, even if Al remains in the object to be recovered, valuable metals (Ni and / or Co) and Al can be sufficiently separated in a subsequent step (e.g., ammine complex formation step S30). In other words, the sorting step S18 can be omitted as needed. For example, in the case of an object to be recovered that has a low content of other metal components (such as process waste of positive electrode plate 30), valuable metals can be efficiently recovered even if the sorting step S18 is omitted.

[0030] (2) Acid leaching process S20 In the acid leaching step S20, the object to be recovered is immersed in an acid solution. This dissolves valuable metals (Ni and / or Co) in the object to be recovered into the acid solution. In addition to valuable metals, other metal materials (such as Al) may also dissolve in the acid solution in the acid leaching step S20. That is, the acid solution that has undergone the acid leaching step S20 (hereinafter also referred to as the "acid leaching solution") may contain, for example, Li, Al, Cu, Co, Ni, Mn, etc. The acid leaching procedure can be any conventionally known procedure without particular limitation. For example, the pH of the acid solution used in the acid leaching step S20 is preferably −1.5 to 1.5 (more preferably −0.5 to 0.5). This allows the metal components in the object to be suitably dissolved. Specific examples of the acid solution include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid, and organic acids such as citric acid, ascorbic acid, oxalic acid, and acetic acid. In the acid leaching step S20, a reducing agent such as hydrogen peroxide can be added in addition to the acid solution. This improves the dissolution rate of the material to be recovered in the acid solution, thereby shortening the acid leaching step S20. In the acid leaching step S20, the acid leaching solution after acid leaching is preferably filtered. This allows undissolved components (such as carbon components) to be efficiently removed. The temperature of the acid solution is preferably 50°C or higher (more preferably 55°C or higher, and particularly preferably 60°C or higher). This allows the acid leaching step S20 to be shortened. The upper limit of the acid solution temperature is not particularly limited, and may be 90°C or lower, 85°C or lower, or 80°C or lower. The concentrations of Ni and Co (the sum of Ni and Co) in the acid leaching solution after the acid leaching step S20 are not particularly limited, but higher concentrations are preferable from the viewpoint of productivity. Therefore, the concentration of Ni and Co (the sum of Ni and Co) in the acid leaching solution is preferably 1.0 mol / L to 2.0 mol / L. The concentrations of Ni and Co (the sum of Ni and Co) in the acid leachate can be determined by ICP analysis.

[0031] (3) Ammine complex formation step S30 In the ammine complex formation step S30, the acid leaching solution obtained in the acid leaching step S20 is mixed with an ammonia solution. This produces an ammonia solution containing ammine complexes of valuable metals (Ni and / or Co) (hereinafter referred to as the "metal solution"). More specifically, the hydroxides of Ni and Co in the acid leaching solution typically produce ammine complexes in the ammonia solution. In this specification, the term "ammonia solution" refers to an aqueous solution containing ammonium ions in water as a solvent.

[0032] In conventional techniques, the acid leachate is neutralized by adding an alkaline solution (e.g., sodium hydroxide) dropwise to the valuable metals (Ni and / or Co) in the acid leachate, causing the Al in the acid leachate to precipitate as Al hydroxide (Al(OH)3). As the pH of the acid leachate increases, more Al in the acid leachate precipitates as hydroxide. However, if the pH becomes too high (typically above pH 6.0), some of the Ni and Co in the acid leachate also form hydroxides, which begin to precipitate as precipitates.

[0033] This embodiment is characterized in that the acid leaching solution is mixed with an ammonia solution. Valuable metals (Ni and / or Co) in the acid leaching solution produce hydroxides in the ammonia solution. By further mixing the ammonia solution, the hydroxides of the valuable metals are converted into ammine complexes of the valuable metals ([Ni(NH3)6] 2+ , [Co(NH3)6] 2+ ) is produced. The ammine complexes of the valuable metals are dissolved in the ammonia solution. Meanwhile, when Al in the acid leaching solution is mixed with the ammonia solution, it forms hydroxides and precipitates. Even when ammine complexes of valuable metals are produced, Al remains as a precipitate in the form of hydroxide without forming ammine complexes. This allows Al to be selectively precipitated as a precipitate while the valuable metals (Ni and / or Co) in the acid leaching solution remain in the solution.

[0034] The ammonia solution used in the ammine complex formation step S30 may be, for example, a commercially available product (ammonia water), or may be a solution prepared by dissolving an ammonia salt in a solvent containing at least water. Examples of ammonia salts that can be used in the ammonia solution include ammonium hydroxide (NH4OH), ammonium sulfate ((NH4)2SO4), ammonium carbonate ((NH4)2CO3), ammonium bicarbonate (NH4HCO3), ammonium chloride (NH4Cl), and ammonium fluoride (NH4F). These compounds may be used alone or in combination of two or more.

[0035] In some preferred embodiments, the ammonia solution preferably contains at least one selected from the group consisting of ammonium sulfate, ammonium chloride, and ammonium acetate. These act as so-called pH buffers for the ammonia solution. Specifically, the pH of the ammonia solution can be lowered. Lowering the pH of the ammonia solution suppresses the dissolution of Al in the ammonia solution, allowing Ni and / or Co to favorably form ammine complexes. Furthermore, according to the above-described configuration, the ammonia concentration of the ammonia solution can be increased, allowing Ni and / or Co to favorably form ammine complexes. Therefore, a metal solution containing Ni and / or Co can be selectively obtained from an acid solution containing the target metal. In other words, the recovery rate of valuable metals (Ni and / or Co) can be favorably improved. Note that it is not necessary to use the ammonia solution containing at least one selected from the group consisting of ammonium sulfate, ammonium chloride, and ammonium acetate alone; a separate ammonia solution may also be prepared. In this case, the timing of mixing in the ammine complex formation step S30 may be simultaneous or separate.

[0036] The pH adjusted in the ammine complex formation step S30 is preferably 9.5 or higher, more preferably 10.1 or higher. If the pH of the acid leaching solution is too low (typically below pH 9), the valuable metals (Ni and / or Co) in the acid leaching solution do not easily form ammine complexes. In other words, the valuable metals do not easily dissolve in the metal solution. If the pH of the metal solution is within a suitable range, the valuable metals in the metal solution will preferably form ammine complexes. In other words, Al can be more efficiently separated from the acid leaching solution. On the other hand, if the pH is too high (typically above pH 11.5) with respect to the upper limit of the pH adjusted in the ammine complex formation step S30, a portion of Al (aluminum hydroxide) will be converted into hydroxide complexes ([Al(OH)4] ― ) and begins to dissolve in the metal solution. Therefore, the pH adjusted in the ammine complex formation step S30 is preferably pH 11.5 or less, and more preferably pH 11.0 or less.

[0037] The ammonia concentration of the ammonia solution in the ammine complex formation step S30 is not particularly limited, as it can vary depending on the concentration of valuable metals (Ni and / or Co) in the acid leachate, but is preferably 10 wt% or more, and more preferably 20 wt% or more. As the ammonia concentration increases, Ni and / or Co favorably form ammine complexes, allowing for more efficient recovery of valuable metals (Ni and / or Co) from the precipitate. On the other hand, in view of the high volatility of ammonia, the upper limit of the ammonia concentration in the ammonia solution is, but is not limited to, 35 wt% or less, and preferably 30 wt% or less.

[0038] The temperature of the mixture in the ammine complex formation step S30 is not particularly limited, but is preferably 25°C or higher, more preferably 40°C or higher, and particularly preferably 60°C or higher. This allows the time for the ammine complex formation step S30 to be shortened. On the other hand, the upper limit of the temperature of the mixture is not particularly limited, but is preferably 100°C or lower, more preferably 90°C or lower, and particularly preferably 80°C or lower.

[0039] The time for the ammine complex formation step S30 is not particularly limited, as it can vary depending on, for example, the ammonia concentration in the reaction solution and the reaction temperature. However, it is preferably approximately 0.5 hours or more, more preferably 1 hour or more, and particularly preferably 2 hours or more. From the viewpoint of productivity, the time for the ammine complex formation step S30 is preferably approximately 8 hours or less, more preferably 6 hours or less, and particularly preferably 4 hours or less. Furthermore, although not particularly limited, it is preferable to perform the ammine complex formation step S30 while stirring the ammonia solution. This increases the contact area between the valuable metal (Ni and / or Co) and the ammonia solution, allowing for efficient formation of an ammine complex of the valuable metal. Therefore, the time for the ammine complex formation step S30 can be shortened.

[0040] (4) Solid-liquid separation process S40 In the solid-liquid separation step S40, precipitates (residues) in the metal solution after the ammine complex formation step S30 are removed by solid-liquid separation. This allows a metal solution containing at least one of Ni and Co to be obtained. Conventional known methods can be used for solid-liquid separation. The metal solution obtained by the solid-liquid separation step S40 is typically a solution in which valuable metals (Ni and / or Co) are dissolved in the form of ammine complexes in an ammonia solution. Since Al has been removed from the metal solution obtained by the solid-liquid separation step S40, a further step for removing Al is not required. In other words, there is no loss of valuable metals due to washing, Al extraction, or the like. The use of the metal solution is not particularly limited, but it can be suitably used, for example, as an alkaline solution in the precursor preparation step S50 described below.

[0041] As described above, the production method disclosed herein can recover a metal solution in which valuable metals (Ni and / or Co) are dissolved as ammine complexes by performing an ammine complex formation process in which an ammonia solution is mixed with an acid leachate containing the material to be recovered. Conventionally, the acid leachate that has undergone the acid leaching process is neutralized with an alkaline solution (e.g., NaOH) to separate the valuable metals (Ni and / or Co) from Al. During this process, some of the valuable metals (Ni and / or Co) may precipitate together with Al as a precipitate, resulting in a loss of valuable metals. Attempts to reduce this loss by suppressing the precipitation of valuable metals in the neutralization process have been problematic, as the pH cannot be sufficiently increased in the neutralization process, making it difficult to fully separate Al from the acid leachate. In contrast, the production method disclosed herein can effectively remove Al from the acid leachate as a precipitate by the ammine complex formation process. The valuable metals (Ni and / or Co) then form ammine complexes and are dissolved in the metal solution. Therefore, the recovery rate of the valuable metals from the object of recovery can be improved.

[0042] The method for producing a battery material disclosed herein may further include a precursor preparation step S50 and an active material production step S60, which will be described in detail below.

[0043] (5) Precursor preparation step S50 In the precursor preparation step S50, a positive electrode active material precursor (metal composite hydroxide) is prepared. In the precursor preparation step S50, a conventionally known method (e.g., crystallization method, etc.) can be used without particular limitation. For example, an aqueous solution containing a metal element source (typically a water-soluble ionic compound) is prepared. Next, the prepared aqueous solution containing the metal element source and an alkaline solution (e.g., an ammonia solution, etc.) are mixed in a reaction tank, and the mixture is stirred while controlling the pH, thereby coprecipitating and crystallizing metal composite hydroxide particles in the reaction tank. For example, various metal components obtained in the solvent extraction step can be used as the metal element source.

[0044] In some preferred embodiments, a positive electrode active material precursor (metal composite hydroxide) is preferably prepared using a metal solution obtained by performing the ammine complex formation step S30 described above as the alkaline solution in the precursor preparation step S50. The metal solution contains Ni and / or Co in an ammonia solution. Therefore, the metal solution can be used as is as the alkaline solution in the precursor preparation step S50 without further treatment, such as washing. Therefore, Co and Ni in the ammonia solution can also be crystallized as a positive electrode active material precursor. In other words, the valuable metals (Ni and / or Co) recovered from the acid leachate in the ammine complex formation step S30 can be used efficiently.

[0045] As described above, in the precursor preparation step S50, crystallization is performed while controlling the pH of the mixed solution. During this process, an alkaline solution (e.g., an aqueous NH3 solution or an aqueous NaOH solution) can be added dropwise to the reaction vessel to adjust the pH. The amounts of Ni and Co in the metal solution obtained in the ammine complex formation step S30 can be determined by ICP analysis. Therefore, depending on the composition of the desired positive electrode active material, Ni, Co, or other metal components such as Mn may be added. These metal components may be added in the form of metal sulfates, hydrates, or the like.

[0046] (6) Active material generation step S60 In the active material production step S60, a battery material (positive electrode active material) is produced using the metal compound obtained in the precursor production step S50 and a Li compound (e.g., Li2CO3). For example, the positive electrode active material precursor (metal composite hydroxide) obtained in the precursor production step S50 is mixed with the Li compound, and the mixture is fired. This allows the production of a positive electrode active material (lithium transition metal composite oxide) for a lithium ion secondary battery.

[0047] In the manufacturing method according to the above-described embodiment, in addition to the preparation step S10, the acid leaching step S20, the ammine complex formation step S30, and the solid-liquid separation step S40, a precursor preparation step S50 and an active material formation step S60 are also performed. However, the description of the above-described embodiment is not intended to limit the steps other than the preparation step S10, the acid leaching step S20, the ammine complex formation step S30, and the solid-liquid separation step S40. In other words, in the manufacturing method disclosed herein, steps other than the preparation step S10, the acid leaching step S20, the ammine complex formation step S30, and the solid-liquid separation step S40 can be added, deleted, or modified as needed.

[0048] 3. Other Embodiments One embodiment of the technology disclosed herein has been described above. Note that the technology disclosed herein is not limited to the above embodiment, and includes other embodiments with various configuration changes. Other examples of the embodiment of the technology disclosed herein will be described below.

[0049] In the manufacturing method according to the above-described embodiment, a technique for recovering valuable metals (Ni and / or Co) from a target to be recovered has been described. However, in some embodiments, the target to be recovered may further contain Li. In this case, Li can be recovered (produced) in addition to the valuable metals in the target to be recovered.

[0050] <Second embodiment> When the target to be recovered includes Li, the following embodiment can be cited as an example of a means for recovering Li. FIG. 5 is a flowchart illustrating a method for producing a battery material according to a second embodiment. FIG. 6 is a flowchart illustrating in detail the solvent extraction step S70 according to the second embodiment. As shown in FIG. 5, the second embodiment includes a solid-liquid separation step S40, a solvent extraction step S70, and a Li crystallization step S80. Note that other than this point, the second embodiment may be the same as the above embodiment, and as this has already been explained, a duplicated description will be omitted. Specific explanations will be given below.

[0051] (7) Solvent extraction step S70 In the solvent extraction step S70, valuable metals (Ni and / or Co) are extracted from the metal solution using a solvent extraction method. The solvent extraction step S70 can also separate other metal components (such as Li) from the metal solution. Specifically, as shown in FIG. 6, the solvent extraction step S70 in this embodiment includes a Co extraction step S71 and a Ni extraction step S72. This allows the preparation of a Co solution and a Ni solution. However, in the solvent extraction step S70, steps can be added, modified, or deleted as appropriate depending on the metal components contained in the metal solution. A detailed explanation is provided below.

[0052] (7-1) Co extraction process S71 In the Co extraction step S71, an organic solvent (first extracting liquid) with high extractability for Co but low extractability for Li, Cu, and Ni is added to the metal solution. This separates Co from the metal solution, and a Co solution in which Co is dissolved in the first extracting liquid can be obtained. Specific examples of the second extracting liquid include phosphonate esters such as 2-ethylhexyl 2-ethylhexylphosphonate (PC-88A). The first extracting liquid may also be a mixture or dilution of these extractants. Then, in the Co extraction step S71, the metal solution and the first extracting liquid are stirred and suspended. This dissolves the Co in the metal solution in the first extracting liquid. The two liquids are then allowed to stand until they separate, thereby obtaining a Co solution in which Co is dissolved in the first extracting liquid and a metal solution from which Co has been removed.

[0053] In the Co extraction step S71, the extracted Co solution (first extract solution containing Co) may be subjected to a back-extraction process. In this back-extraction process, the Co solution (organic phase) and an acidic aqueous solution are first stirred and mixed using a mixer or the like. The mixture is then left to stand until the two liquids separate. This allows an aqueous Co solution to be obtained. The acidic aqueous solution used in the back-extraction process may be sulfuric acid, hydrochloric acid, or the like (particularly sulfuric acid).

[0054] (7-2)Ni extraction process S72 In the Ni extraction step S72, an organic solvent (second extraction liquid) with high extractability for Ni and low extractability for Li and Cu is added to the metal solution. This separates Ni from the metal solution, and a Ni solution in which Ni is dissolved in the second extraction liquid can be obtained. Specific examples of the third extraction liquid include carboxylic acid extractants such as neodecanoic acid and naphthenic acid. Furthermore, a back-extraction process may also be performed on the extracted Ni solution (second extraction liquid containing Ni). This allows an aqueous Ni solution to be obtained. The back-extraction process procedure has already been described, so a repeated description will be omitted.

[0055] The specific processing procedure in the solvent extraction step S70 can be modified as appropriate. For example, the solvent extraction step S70 in the above-described embodiment includes a Co extraction step and a Ni extraction step. This allows for separate extraction of Co and Ni solutions. However, in the solvent extraction step S70, Ni and Co may be extracted simultaneously. This shortens the process steps, thereby improving production efficiency. The valuable metals (Ni and / or Co) obtained in the solvent extraction step S70 can be used, for example, as a metal element source in the precursor preparation step S50, but is not limited thereto.

[0056] (8) Li crystallization process S80 In the Li crystallization step S80, crystals of a Li compound are precipitated from the metal solution after the solvent extraction step S70. In the Li crystallization step S80, any conventionally known crystallization process can be used without particular limitation. For example, in the Li crystallization step S80, sodium carbonate can be added to the metal solution. This allows lithium carbonate (Li2CO3) crystals to be precipitated. The Li compound produced in the Li crystallization step S80 is not limited to lithium carbonate. For example, lithium hydroxide (LiOH) may be produced as the Li compound, if necessary. In producing this lithium hydroxide, first, the lithium carbonate precipitated from the metal solution is dissolved (or suspended) in a predetermined solvent. Then, calcium hydroxide is added to this solution. Then, the solvent is evaporated and removed as necessary. This allows lithium hydroxide crystals to be precipitated. The Li compound crystals precipitated in the Li crystallization step S80 can be used, for example, in the active material production step S60, but are not limited thereto.

[0057] In some embodiments, the metal solution after the solvent extraction step S70 may be subjected to a Li separation step. The Li separation step is a step in which other metal components (Cu, etc.) are further removed from the metal solution to prepare a high-concentration Li solution. This allows a high-purity Li compound to be obtained in the Li crystallization step S80. The method for preparing the Li solution is not particularly limited, and it is preferable to appropriately adopt a conventionally known method such as a solvent extraction method or an ion exchange method. Instead of the Li concentration step, only solvent evaporation may be performed. In this case, a high-concentration Li solution can also be obtained.

[0058] In some embodiments, a Li concentration step may be performed on the metal solution after the Li separation step. In this Li concentration step, the Li solution is heated to evaporate the solvent. This allows a highly concentrated Li solution to be obtained, thereby improving the crystallization efficiency in the Li crystallization step S80. Note that this Li concentration step may also be performed on a metal solution that has not been subjected to the Li separation step. In this case, a highly concentrated Li solution can also be obtained.

[0059] <Third embodiment> The method for producing a battery material according to the second embodiment has been described above. However, the means for recovering Li is not limited to this. Another example of a Li recovery method when the recovery target includes Li is as follows: FIG. 7 is a flowchart illustrating a method for producing a battery material according to a third embodiment. FIG. 8 is a flowchart illustrating in detail the preparation step S110 according to the third embodiment. As shown in FIGS. 7 and 8, the third embodiment includes a preparation step S110 including a recovery target preparation step S11, a chlorination heating step S14, a water dissolution step S16, and a sorting step S18, instead of the preparation step S10. Note that other aspects may be similar to the above-described embodiment, and have already been described, so repeated description will be omitted. Furthermore, the recovery target preparation step S11 and the sorting step S18 may also be similar to the above-described embodiment, and description thereof will be omitted here. Specific descriptions will be provided below.

[0060] (1-4) Chloridation heating step S14 In the chlorination heating step S14, the object to be recovered is heated together with a non-metallic chlorine compound (e.g., HCl). As a result, Li in the object to be recovered reacts with the non-metallic chlorine compound to produce lithium chloride (LiCl). This LiCl is easily dissolved in water such as pure water or ion-exchanged water. Therefore, it can be easily separated from the object to be recovered in the water dissolution step S16 described below.

[0061] (1-5) Water dissolution process S16 In the water dissolution step S16, the object to be recovered after the chlorination heating step S14 is immersed in water. This allows for the production of a Li solution in which LiCl is dissolved in water. The Li solution obtained in the water dissolution step S16 can be used to precipitate Li compound crystals by the same means as in the Li crystallization step S80 described above, but is not limited to this. The Li compound crystals thus obtained can be used, for example, as the Li compound in the active material production step S60 (see FIG. 7).

[0062] Note that the recovery target (typically, metal components other than Li) that were not salified in the chlorination heating step S14 remains as a solid content after the water dissolution step S16. In this embodiment, the solid content (recovery target) after the water dissolution step S16 can be subjected to the sorting step S18, acid leaching step S20, ammine complex formation step S30, and solid-liquid separation step S40 according to the above-described embodiments. In this embodiment, Li in the recovery target is recovered in advance of the acid leaching step S20 by the chlorination heating step S14 and the water dissolution step S16. That is, the metal solution obtained in the solid-liquid separation step S40 does not contain Li. Therefore, this metal solution can be used directly in the precursor preparation step S50 without undergoing the solvent extraction step. As a result, in this embodiment, Li is recovered (produced) from the recovery target while the valuable metals (Ni and / or Co) contained in the metal solution can be efficiently utilized.

[0063] [Test example] Test examples relating to the technology disclosed herein will be described below. Note that the contents of the test examples described below are not intended to limit the technology disclosed herein.

[0064] <Test Example 1: Study of pH during neutralization precipitation process> (Example 1) In this test, the positive electrode plate was used as the object to be recovered, and the following process was carried out on the object to be recovered. Specifically, the positive electrode plate used was a positive electrode core (Al foil) on the surface of which a positive electrode active material layer was applied. The positive electrode active material in this test was lithium nickel cobalt manganese composite oxide (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2) was used. The positive electrode plate was crushed and sieved through a 500 μm mesh sieve to obtain powder, which was used as a test sample. When the test sample powder was analyzed by ICP, the mass ratio of Al to the total amount of Ni and Co in the sample was found to be 4 wt%.

[0065] Next, the test sample was mixed with a mixture (pH 0) of sulfuric acid (H2SO4) (concentration 2 mol / L) as an acid solution and hydrogen peroxide (H2O2) (concentration 0.6 mol / L) as a reducing agent. The acid solution was then stirred at 600 rpm for 6 hours while maintaining the temperature at 80°C. After stirring, the acid leachate was filtered, and the resulting acid leachate was analyzed by ICP to measure the amounts of Al, Ni, and Co. The ICP measurement results indicated that the concentrations of Ni and Co (the sum of Ni and Co) in the acid leachate were 1.0 mol / L.

[0066] The acid leachate obtained above was maintained at 25°C and stirred at 600 rpm while an ammonia (NH3) solution with an ammonia concentration of 28 wt% was added dropwise to the acid leachate (corresponding to the "Alkaline Solution" column in Table 1). When the pH of the acid leachate reached 4.2, the addition of the ammonia solution was stopped. After the addition was stopped, stirring was continued at 600 rpm for 10 minutes, and it was confirmed that the pH was not changing. The metal solution and precipitate were then separated into solid and liquid by filtration.

[0067] (Examples 2 to 5) In Examples 2 to 5, the dropping of the ammonia solution was stopped when the pH reached the value shown in Table 1. Other than this, the same procedures as in Example 1 were carried out.

[0068] (Example 6, Example 7) In Examples 6 and 7, the acid leaching solution obtained above was maintained at 80° C., and the dropwise addition of the ammonia solution was stopped when the pH reached the values ​​shown in Table 1. Other than this, the same procedures were carried out as in Example 1.

[0069] (Example 8) In Example 8, 2 mol / L of ammonium sulfate ((NH4)2SO4) was added as a pH buffer before the addition of the ammonium solution. The same ammonia solution as used in Example 1 was then added dropwise, and the addition of the ammonia solution was stopped when the pH of the acid leachate reached 10.1. The rest of the procedure was the same as in Example 1.

[0070] (Examples 9 to 15) In Examples 9 to 15, instead of the ammonia solution, a 10 wt% sodium hydroxide (NaOH) solution was added dropwise to the acid leaching solution (corresponding to the "Alkaline solution" column in Table 1). The addition of the sodium hydroxide solution was stopped when the pH reached the values ​​shown in Table 1. Other than this, the same procedures as in Example 1 were carried out.

[0071] In all of Examples 1 to 15, precipitates were observed at the end of the dropwise addition of the alkaline solution (ammonia solution or sodium hydroxide solution).

[0072] [Residual rate in metal solution] The residual rates of valuable metals (Ni, Co) and Al in the metal solution for each example were calculated. Specifically, the metal solution was first subjected to ICP to measure the amounts of Ni, Co, and Al in the metal solution. Then, the residual rates of Ni and Co and Al in the metal solution for each example, compared to the acid leachate (i.e., before titration), were calculated based on the following formulas (1) and (2). Note that the higher the residual rates of Ni and Co in the metal solution, the more Ni and Co that had leached into the acid leachate before the addition of the alkaline solution (ammonia solution or sodium hydroxide solution) were dissolved in the metal solution. Therefore, the higher the residual rates of Ni and Co in the metal solution, the better the results of this test example. On the other hand, the lower the residual rate of Al in the metal solution, the better the separation of Al in the acid leachate (typically precipitated as a precipitate). Therefore, the lower the residual rate of Al in the metal solution, the better the results of this test example. The results are shown in Table 1. Ni and Co remaining rate in metal solution (%) = {(amount of Ni in metal solution + amount of Co in metal solution) / (amount of Ni in acid leachate + amount of Co in acid leachate) × 100 ... (1) Al residual rate in metal solution (%) = (Amount of Al in metal solution / Amount of Al in acid leachate) × 100 (2)

[0073] [Table 1]

[0074] As shown in the results in Table 1, in Examples 9 to 15, in which a sodium hydroxide (NaOH) solution was used as the alkaline solution, the residual rates of Al and Ni and Co in the metal solution decreased as the pH increased. This is thought to be because Al in the acid leaching solution was precipitated as aluminum hydroxide, while Ni and Co in the acid leaching solution also formed hydroxides and were similarly precipitated. On the other hand, in Examples 1 to 5, in which an ammonia (NH3) solution was used as the alkaline solution, the residual Al rate in the metal solution decreased as the pH increased, as in Examples 9 to 15. Regarding Ni and Co, the residual Ni and Co rates in the metal solution decreased in Examples 3 and 4, in which the pH of the metal solution was 6.0 and 9.0, respectively. This is thought to be because Ni and Co in the acid leachate formed hydroxides and precipitated as the pH increased. However, in Example 5, in which the pH of the metal solution was 11.0, the residual Ni and Co rates in the metal solution increased again. This is thought to be because the hydroxides of Ni and Co in the acid leachate further formed ammine complexes with ammonia ions in the ammonia solution. This is thought to result in Ni and Co dissolving in the metal solution as ammine complexes. Furthermore, because the hydroxide of Al does not form ammine complexes, it is thought to be suitably separated as hydroxide in Example 5 as well. That is, by mixing an ammonia solution with the acid leachate from which the recovery target containing valuable metals (Ni and / or Co) has been leached, and generating an ammine complex of the valuable metal (Ni and / or Co), Al can be suitably separated and a metal solution containing the valuable metal can be suitably obtained.

[0075] In Example 6, where the solution temperature was maintained at 80°C, ammine complexes of Ni and Co were successfully produced, and good results were also obtained in the separation of Al. In Example 7, where the pH of the metal solution was 12.1, good results were obtained in terms of the residual rate of Ni and Co in the metal solution, but the residual rate of Ni and Co in the metal solution was 0.9%, which was slightly higher than in Example 6, where the pH of the metal solution was 11.0. This is because a portion of the Al hydroxide precipitated was converted into a hydroxide complex ([Al(OH)4]) that was soluble in the metal solution. ―In Example 8, in which ammonium sulfate was added to the acid leaching solution in addition to the ammonia solution, very good results were obtained for both the Ni, Co and Al residual rates in the metal solution. This is thought to be because the addition of ammonium sulfate made it possible to increase the ammonia concentration while keeping the pH of the metal solution at 10.1, thereby enabling the formation of Ni and Co ammine complexes while favorably precipitation of Al.

[0076] The technology disclosed herein has been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. In other words, the technology disclosed herein encompasses the aspects described in items 1 to 7 below.

[0077] <Item 1> a preparation step of preparing a recovery target containing at least one of Ni and Co; an acid leaching step of immersing the recovery target in an acid solution to obtain an acid leaching solution; an ammine complex formation step of mixing an ammonia solution containing ammonium ions with the acid leaching solution to form a metal solution containing an ammine complex of at least one of the Ni and Co; A solid-liquid separation step of obtaining the metal solution by solid-liquid separation. Manufacturing methods for battery materials.

[0078] <Item 2> Item 2. The method for producing a battery material according to item 1, wherein the ammonia solution contains at least one selected from the group consisting of ammonium sulfate, ammonium chloride, and ammonium acetate.

[0079] <Item 3> 3. The method for producing a battery material according to item 1 or 2, wherein the pH of the ammonia solution is adjusted to 9.5 to 11.5 and the ammine complex-forming step is carried out.

[0080] <Item 4> 4. The method for producing a battery material according to any one of items 1 to 3, wherein the ammine complex-forming step is carried out by adjusting the temperature of the ammonia solution to 25 to 100°C.

[0081] <Item 5> 5. A method for producing a battery material according to any one of items 1 to 4, further comprising a precursor preparation step of preparing a positive electrode active material precursor using the metal solution.

[0082] <Item 6> 6. The method for producing a battery material according to any one of items 1 to 5, wherein the object to be recovered includes Li.

[0083] <Item 7> 7. The method for producing a battery material according to any one of items 1 to 6, further comprising a solvent extraction step of extracting at least one of the Ni and the Co from the metal solution.

[0084] <Item 8> The above preparation process is a chlorination heating step of heating the recovery target together with a non-metallic chlorine compound to produce LiCl; 8. The method for producing a battery material according to item 6 or 7, further comprising a water dissolution step of immersing the object to be recovered after the chlorination heating step in water to obtain a Li solution in which the LiCl is dissolved in the water. [Explanation of symbols]

[0085] 1. Lithium-ion secondary battery 10 cases 12 Positive terminal 14 Negative terminal 20 Electrode body 30 positive electrode plate 32 Positive electrode core 34 Cathode active material layer 40 negative electrode plate 42 negative electrode core 44 Negative electrode active material layer 50 Separator

Claims

1. a preparation step of preparing a recovery target containing at least one of Ni and Co; an acid leaching step of immersing the recovery target in an acid solution to obtain an acid leaching solution; an ammine complex formation step of mixing an ammonia solution containing ammonium ions with the acid leaching solution to form a metal solution containing an ammine complex of at least one of the Ni and the Co; a solid-liquid separation step of obtaining the metal solution by solid-liquid separation, The pH of the metal solution is adjusted to 9.5 to 11.5, and the ammine complex formation step is carried out. Manufacturing methods for battery materials.

2. The method for producing a battery material according to claim 1 , wherein the ammonia solution contains at least one selected from the group consisting of ammonium sulfate, ammonium chloride, and ammonium acetate.

3. 3. The method for producing a battery material according to claim 1, wherein the ammine complex formation step is carried out at a temperature of the ammonia solution of 25 to 100°C.

4. The method for producing a battery material according to claim 1 or 2, further comprising a precursor preparation step of preparing a positive electrode active material precursor using the metal solution.

5. The method for producing a battery material according to claim 1 or 2, wherein the object to be recovered includes Li.

6. The method for producing a battery material according to claim 5 , further comprising a solvent extraction step of extracting at least one of the Ni and the Co from the metal solution.

7. The preparation step includes: a chlorination heating step of heating the recovery target together with a non-metal chlorine compound to generate LiCl; The method for producing a battery material according to claim 5 , further comprising a water dissolving step of immersing the target to be recovered after the chlorination heating step in water to obtain a Li solution in which the LiCl is dissolved in the water.

Images