Method for manufacturing battery material

Abstract

To improve the efficiency of recovering a valuable metal from a recovery target such as a used lithium ion secondary battery.SOLUTION: The method for manufacturing disclosed herein includes: a preparation step S11 of preparing a recovery target including at least one of Ni and Co; a measurement step S12 for measuring the physical amount of the oxygen element and the reduction component in the recovery target; a determination step S13 for determining whether the physical amount ratio of the reduction component to the oxygen element is at least a threshold value based on the stoichiometric proportion of the reduction component and the oxide; a reduction component adding step S14 for adding the reduction component to the recovery target when the result of the determination in the determination step is less than the threshold value; and a heating step S15 for heating the recovery target in an inactive atmosphere. Since a valuable metal such as Ni or Co can be thus reduced to the state of a metal alone, the efficiency of recovering the valuable metal can be improved.SELECTED DRAWING: Figure 4

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. Various materials including valuable metals such as Ni and Co are used in these lithium ion secondary batteries. 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. Aluminum or the like is used for the positive electrode core. Meanwhile, carbon materials or the like are used for the negative electrode active material. Copper or the like is used for the negative electrode core. Furthermore, aluminum or the like is used for the battery case that houses these electrodes.

[0003] In recent years, development of recovery technology has been promoted to recover valuable metals from used batteries and process scraps and reuse them as battery materials. In this recovery technology, first, the object to be recovered (used batteries, process scraps, etc.) is roasted. Then, the roasted object to be recovered is subjected to acid leaching. This makes it possible to obtain a metal solution in which the metal components (Li, Ni, Co, Mn, Al, Cu, etc.) in the object to be recovered are dissolved in an acid solution. In addition, this acid leaching makes it possible to separate the carbon components in the object to be recovered. Meanwhile, various separation processes (neutralization precipitation, solvent extraction, etc.) are carried out on the metal solution after acid leaching. This makes it possible to extract the desired metal components and reuse them as battery materials.

[0004] An example of this recovery technique is disclosed in Patent Document 1. In the recovery method described in Patent Document 1, in a heating step (roasting step), battery slag (recovery target) having a positive electrode active material containing Ni and / or Co and a negative electrode active material containing graphite is heated to oxidize the graphite contained in the negative electrode active material in the battery slag to generate carbon dioxide gas. In this recovery method, the recovery target is roasted in an oxidizing atmosphere (e.g., air atmosphere). This reduces valuable metals (trivalent or tetravalent Ni ions and Co ions) in the recovery target to divalent oxides. Patent Document 1 indicates the view that such divalent oxides are easily dissolved in an acid solution in the acid leaching step. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-118594 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, as a result of the study by the present inventor, it was found that the divalent oxides of the above-mentioned valuable metals still have insufficient solubility in acid solution. If the valuable metal has low solubility in acid, not only the valuable metal but also other metal materials (such as Cu) may be dissolved in the metal solution after acid leaching. As a result, not only the separation process for separating impurities becomes complicated, but also a part of the valuable metal may be removed during the separation process. [Means for solving the problem]

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

[0008] The manufacturing method for battery materials disclosed herein includes a preparation step of preparing a recovery target containing at least one of Ni and Co, a measurement step of measuring the amounts of substance of oxygen element and reducing component contained in the recovery target, a determination step of judging whether the amount of substance ratio of the reducing component to the oxygen element is equal to or greater than a threshold based on the stoichiometric ratio of oxides of the reducing component, a reducing component addition step of adding the reducing component to the recovery target if the determination result of the determination step is less than the threshold, and a heating step of heating the recovery target under an inert atmosphere.

[0009] In the manufacturing method having the above configuration, roasting is performed in a state where a large amount of reducing components are present in the object to be recovered and oxygen element is not supplied from the outside. This rapidly promotes the transfer of oxygen element from the oxides of valuable metals (hereinafter also referred to as "valuable metal oxides") in the object to be recovered to the reducing components. As a result, the valuable metals in the object to be recovered can be reduced to the elemental metal state. Furthermore, since the elemental valuable metals have superior acid solubility compared to other metal materials, this can contribute to a significant improvement in the recovery efficiency of valuable metals. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a vertical cross-sectional view that illustrates a schematic internal structure of a lithium-ion secondary battery. [Diagram 2] FIG. 2 is a perspective view that typically shows an electrode assembly of the lithium ion secondary battery shown in FIG. [Diagram 3] FIG. 3 is a flow chart illustrating a method for producing a battery material according to one embodiment. [Figure 4] FIG. 4 is a flow chart illustrating in detail the roasting step in the production method according to one embodiment. [Diagram 5] FIG. 5 is a flow chart illustrating in detail the solvent extraction step in the production method according to one embodiment. [Figure 6] FIG. 6 shows the results of XRD analysis in the test examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the technology disclosed herein will be described with reference to the drawings. Note that matters other than those specifically mentioned in this specification and 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 field. The technology disclosed herein can be implemented based on the contents disclosed in this specification and the technical common sense in the field.

[0012] 1. Items to be recalled The method for producing a battery material according to the present embodiment produces a battery material (typically, a material for a positive electrode active material of a lithium ion secondary battery, a precursor of the positive electrode active material, or a positive electrode active material) by recovering valuable metals such as Ni and Co from a predetermined recovery target. An example of the recovery target here is a used lithium ion secondary battery. Hereinafter, this lithium ion secondary battery will be specifically described. FIG. 1 is a vertical cross-sectional view that typically shows the internal structure of a lithium ion secondary battery. FIG. 2 is a perspective view that typically shows 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. An electrode body 20 and an electrolyte are housed inside the case 10. For example, a metal material (such as aluminum (Al)) having a certain strength is used for the case 10. 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 body 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 body 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 body 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 metal foil having electrical conductivity, and a positive electrode active material layer 34 applied to the surface of the positive electrode core 32. Aluminum (Al) or the like is used for the positive electrode core 32. 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. According to the manufacturing method of this embodiment, Ni and / or Co can be efficiently recovered from a recovery target containing such a lithium transition metal composite oxide. Examples of the conductive material include carbon materials such as acetylene black and graphite. Examples of the binder 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 metal foil having electrical conductivity, and a negative electrode active material layer 44 applied to the surface of the negative electrode core 42. The negative electrode core 42 is made of copper (Cu) or the like. 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 the negative electrode active material include carbon materials such as graphite, hard carbon, and soft carbon. Other examples of the negative electrode active material include lithium titanate (LTO), silicon carbide, a composite containing carbon and silicon, and silicon oxide (SiO X) and the like. Although the details will be described later, according to the manufacturing method of this embodiment, even when a battery using such a non-carbon-based negative electrode active material is to be collected, the recovery efficiency of valuable metals can be appropriately improved. In addition, 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 collection target in the manufacturing method according to the present embodiment. However, the manufacturing method disclosed herein is not limited to only the method in which the lithium ion secondary battery 1 having the above configuration is the collection target. For example, at the manufacturing site of the lithium ion secondary battery, a part of the positive electrode plate may be cut off when the electrode body is manufactured. This cut part of the positive electrode plate (process waste material) also contains Ni and Co, and therefore may be the collection target of the manufacturing method disclosed herein. In addition, at the manufacturing site of the lithium ion secondary battery, some defect may occur in the electrode body after manufacture, making it unusable for products. Such an electrode body may also be the collection target because it contains Ni and Co. In other words, the collection target of the manufacturing method disclosed herein may be any structure that contains at least one of Ni and Co.

[0021] 2. Manufacturing method of battery materials The manufacturing method of the battery material according to the present embodiment will be described below. Fig. 3 is a flow chart for explaining the manufacturing method according to the present embodiment. Fig. 4 is a flow chart for explaining in detail the roasting step in Fig. 3. Fig. 5 is a flow chart for explaining in detail the solvent extraction step in Fig. 3.

[0022] 3, the method for producing a battery material according to this embodiment includes a roasting step S10, a sorting step S20, an acid leaching step S30, a neutralization precipitation step S40, a solvent extraction step S50, an NCM crystallization step S60, a Li crystallization step S70, and an active material production step S80. Each step will be described below.

[0023] (1) Roasting process S10 In this step, the object to be collected is heated at a predetermined temperature. This allows the liquid components (electrolyte, etc.) in the object to be collected to be removed and the resin components (binder, separator, etc.) to be carbonized. Furthermore, when a charged lithium-ion secondary battery 1 is to be collected, the function of the battery can be stopped by carrying out the roasting step S10. This allows the subsequent steps to be carried out safely.

[0024] As shown in Fig. 4, the roasting process S10 in this embodiment includes a preparation process S11, a measurement process S12, a determination process S13, a reducing component addition process S14, and a heating process S15. This can significantly improve the recovery efficiency of valuable metals such as Co and Ni. The details will be described below.

[0025] (a) Preparation step S11 In this process, a recovery target containing at least one of Ni and Co is prepared. As described above, the "recovery target" in the technology disclosed herein is not limited to completed lithium ion secondary batteries, but includes process waste materials and defective parts (electrode bodies, etc.). Details of the recovery target have already been explained, so duplicate explanations will be omitted. According to the manufacturing method of this embodiment, in addition to the above-mentioned nickel (Ni) and cobalt (Co), manganese (Mn), lithium (Li), etc. can also be recovered (manufactured).

[0026] (b) Measurement step S12 In the measurement step S12, the amounts of oxygen element (O) and reduced components contained in the collection target are measured. In this step, a part of the collection target is taken as a measurement sample, and the oxygen element and reduced components of the measurement sample are measured. This step only needs to be performed when the type of collection target is changed, and does not need to be performed for all of the collection targets prepared. This can improve production efficiency.

[0027] In this specification, the "reducing component" is not particularly limited as long as it is a component that can reduce Ni and Co in the heating step S15 described later. In the manufacturing method according to this embodiment, carbon element (C) is used as the reducing component. Carbon is particularly preferable as the reducing component because it is not easily oxidized and is stable until the heating step S15 is started. Depending on the type of the object to be recovered, various carbon materials (conductive materials, binders, negative electrode active materials, etc.) may be contained. Using these carbon materials as a source of the reducing component can contribute to reducing the cost required for recovering valuable metals.

[0028] The method for measuring the amount of the reduced component (carbon element) in the recovery target is not particularly limited, and any conventionally known measuring method can be used without particular limitation. For example, methods for measuring the amount of carbon element include thermogravimetric differential thermal analysis (TG-DTA), SEM-EDS analysis, oxygen flow combustion-non-dispersive infrared analysis, and combustion volume method.

[0029] Next, a method for measuring the amount of substance of the oxygen element in the object to be recovered will be described. First, when the chemical composition of the positive electrode active material in the object to be recovered is known in advance, it is advisable to measure the amount of substance of the metal element in the object to be recovered and calculate the amount of substance of the oxygen element based on the amount of substance of the metal element. This makes it possible to easily measure the amount of substance of the oxygen element in a valuable metal oxide (for example, a lithium transition metal composite oxide). A specific example of such a measurement procedure is as follows. First, a solution is prepared by dissolving a part of the object to be recovered (a measurement sample) in an acid. Next, an inductively coupled plasma analysis (ICP) is performed on this solution. This makes it possible to measure the total amount of substance M of the transition metal elements (Ni, Co, Mn) in the object to be recovered. Then, the chemical composition of the positive electrode active material in the object to be recovered (LiNi x Co y Mn z O δ ) is known, the ratio (x+y+z:δ) of the total amount of substance of the transition metal elements (x+y+z) to the amount of substance of O (δ) can be obtained. In this case, the amount of substance N of the oxygen element can be calculated from the ICP measurement results (total amount of substance M of the metal elements) based on the following formula (1). N = δ M / (x + y + z) (1)

[0030] The means for measuring the amount of substance of the oxygen element in the object to be recovered is not limited to the above means, and any conventionally known measuring means can be used without any particular limitation. For example, the oxygen element in the object to be recovered may be directly measured using SEM-EDS analysis, XRF analysis, etc. By using these methods, the amount of substance of the oxygen element can be measured even if the chemical composition of the positive electrode active material in the object to be recovered is unknown.

[0031] (c) Judgment step S13 In the determination step S13, it is determined whether the amount of substance ratio of the reducing component to the oxygen element is equal to or greater than a predetermined threshold value. Here, the "threshold value" in this step is set based on the stoichiometric ratio of the oxide of the reducing component. For example, when carbon element is used as the reducing component, the "oxide of the reducing component" is carbon dioxide (CO2). At this time, in order to appropriately reduce the oxide of the valuable metal in the heating step S15 described later, the threshold value is set to a value equal to or greater than the ratio (1 / 2) of the carbon element to the oxygen element in CO2. Then, in this step, it is determined whether the amount of substance ratio (C / O ratio) of the carbon element (reducing component) to the oxygen element in the recovery object is equal to or greater than 1 / 2. This makes it possible to determine whether the reducing component sufficient to reduce the valuable metal to an elemental metal is present in the recovery object. Then, when the C / O ratio is equal to or greater than 1 / 2 (YES in S13 of FIG. 4), the recovery object is subjected to the heating step S15. On the other hand, when the C / O ratio is less than 1 / 2 (NO in S13 in FIG. 4), the recovery target is subjected to a reducing component addition step S14.

[0032] As described above, the threshold value in this step may be set to a value equal to or greater than the stoichiometric ratio of the oxide of the reducing component. For example, when the reducing component is a carbon element, the threshold value may be set to 3 / 4 or more (more preferably 1 or more, even more preferably 5 / 4 or more, and particularly preferably 3 / 2 or more). This allows only the recovery target containing a large amount of the reducing component (carbon element) to be subjected to the heating step S15, thereby further promoting the reduction of the valuable metal oxide in the heating step S15.

[0033] (d) Reducing component addition step S14 In the reducing component adding step S14, when the result of the determination in the determination step S13 is less than the threshold (NO in S13 in FIG. 4), a reducing component is added to the recovery target. In this embodiment, a reducing component (carbon-containing material) is added to the recovery target whose C / O ratio is determined to be less than 1 / 2 in the determination step S13 so that the C / O ratio becomes equal to or greater than the threshold (1 / 2 or more). This allows a reducing component (carbon element) sufficient to reduce valuable metals to elemental metals to be present in the recovery target. Note that examples of the carbon-containing material include carbon materials such as graphite, hard carbon, and soft carbon. The carbon-containing material may also be a resin material such as polyolefin or polyester. These resin materials are carbonized in the early stage of the heating step S15 to generate carbon elements, and can therefore be used as a source of carbon elements.

[0034] In this step, the reducing component may be added in an amount that greatly exceeds the threshold value. For example, when the reducing component is carbon element, a carbon-containing material may be added so that the C / O ratio in the recovery target is 3 / 4 or more (more preferably 1 or more, even more preferably 5 / 4 or more, and particularly preferably 3 / 2 or more). This allows the recovery target containing a large amount of reducing component (carbon element) to be subjected to the heating step S15, thereby further promoting the reduction of valuable metal oxides in the heating step S15.

[0035] (e) Heating step S15 In the heating step S15, the recovery target is heated in an inert atmosphere. Here, in the manufacturing method according to the present embodiment, the recovery target in which the substance ratio of the reducing component to the oxygen element is adjusted to be equal to or greater than the stoichiometric ratio of the oxide of the reducing component is subjected to the heating step S15. That is, the recovery target in this embodiment is heated in a state in which a large amount of the reducing component is present. In addition, in the heating step S15 in this embodiment, the recovery target is heated in an inert atmosphere. This makes it possible to prevent the oxygen element from being supplied to the recovery target during heating. As a result, it is possible to promote the rapid transfer of the oxygen element from the valuable metal oxide (such as a lithium transition metal composite oxide) to the reducing component. For example, when carbon element is used as the reducing component, a reaction as shown in the following formula (2) occurs. This makes it possible to reduce the valuable metal in the recovery target to the state of simple metal (metal Ni, metal Co).

[0036] LiNi x Co y Mn z O δ +C 1 / 2δ =Li+xNi+yCo+zMn+1 / 2δ·CO2(2)

[0037] The heating temperature in this step is preferably 600°C or higher, more preferably 650°C or higher, even more preferably 700°C or higher, and particularly preferably 750°C or higher. As the heating temperature increases, there is a tendency for the valuable metal to be more easily produced as a simple metal. On the other hand, from the viewpoint of reducing the valuable metal, the upper limit of the heating temperature is not particularly limited, and may be 1500°C or lower, 1400°C or lower, or 1300°C or lower. In consideration of reducing the cost required for the heat treatment, the upper limit of the heating temperature is preferably 1200°C or lower, more preferably 1100°C or lower, and particularly preferably 1000°C or lower.

[0038] In addition, in this process, it is preferable to heat the object to be recovered while circulating an inert gas such as argon or nitrogen. This appropriately prevents the supply of oxygen element to the object to be recovered, and further promotes the rapid reduction of valuable metals. In this specification, the "inert atmosphere" refers to a heating atmosphere containing the above-mentioned inert gas as a main component. In other words, the heating atmosphere in this process is not limited to a completely inert atmosphere in which the content of inert gas is 100% (the content of oxygen element is 0%), and may contain a very small amount of oxygen element. Specifically, the heating atmosphere in this process may have an oxygen element content of 5% or less (preferably 3% or less, more preferably .1% or less, even more preferably 0.5% or less, and particularly preferably 0.1% or less). With such a small amount, even if the oxygen element is contained in the heating atmosphere, the valuable metal in the object to be recovered can be reduced to a metal element.

[0039] (2) Sorting process S20 As shown in FIG. 3, in the manufacturing method according to the present embodiment, a roasting step S10 is performed, followed by a sorting step S20. In this step, each component included in the object to be collected after roasting is sorted using a sieve. For example, when the object to be collected is a process waste of a positive electrode plate 30, the positive electrode core 32 may be sorted using a sieve from the process waste and removed from the object to be collected. When the electrode body 20 is the object to be collected, in addition to the positive electrode core 32, the negative electrode plate 40 may also be removed from the object to be collected. Furthermore, when the lithium ion secondary battery 1 is the object to be collected, in addition to the positive electrode core 32 and the negative electrode plate 40, the case 10 may also be removed from the object to be collected. This reduces the content of impurities (Al, Cu, etc.) in the object to be collected, which contributes to improving the recovery efficiency of valuable metals (Co, Ni).

[0040] In this step, the object to be collected may be subjected to a crushing process as necessary. This can improve the efficiency of sorting each component. For example, when the object to be collected is a lithium-ion secondary battery 1, the case 10 and the electrode body 20 may be crushed. This makes it easier to remove the case 10, the positive electrode core 32, and the negative electrode plate 40 from the object to be collected.

[0041] Moreover, the sorting step S20 is not a step intended to completely remove impurities such as Al and Cu from the object to be recovered. As will be described in detail later, even if impurities remain in the object to be recovered, they can be sufficiently removed in subsequent steps (such as the acid leaching step S30 and the neutralization precipitation step S40). In other words, this step can be omitted as necessary. For example, in the case of an object to be recovered that has a low content of impurities (such as process waste of positive electrode plate 30), valuable metals can be efficiently recovered even if this step is omitted.

[0042] (3) Acid leaching process S30 Next, in the acid leaching step S30, the object to be recovered after the heating step S15 (sorting step S20) is immersed in an acid solution. As a result, valuable metals (Li, Ni, Co, Mn) in the object to be recovered are dissolved in the acid solution. In addition to valuable metals, other metal materials (Cu, Al, etc.) may also be dissolved in the acid solution in this step. That is, the solution (metal solution) after acid leaching contains metal elements such as Li, Al, Cu, Co, Ni, and Mn. The procedure for acid leaching can be any conventional procedure without particular limitation. As an example, the pH of the acid solution used in this step 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 this step, it is preferable to perform a filtration process on the metal solution after acid leaching. 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 S30 to be shortened. The upper limit of the temperature of the acid solution is not particularly limited, and may be 90°C or lower, 85°C or lower, or 80°C or lower.

[0043] Here, in the conventional recovery technology, the recovery target after roasting contained a large amount of valuable metal oxides (nickel (II) oxide, cobalt (II) oxide, etc.). For this reason, in the conventional acid leaching process, it was necessary to set conditions that could properly dissolve these oxides. However, if the acid leaching process is performed under conditions that can dissolve valuable metal oxides, there is a risk that a large amount of metal materials other than valuable metals (Cu, etc.) will also be dissolved in the acid solution. In this case, many impurities will be mixed into the metal solution after the acid leaching process, which may cause the separation process to become complicated and the recovery rate of valuable metals to decrease. In contrast, in the manufacturing method according to this embodiment, the valuable metals are reduced to the state of elemental metals (metallic nickel, metallic cobalt, etc.) in the roasting process S10. These elemental metals have higher acid solubility than other metal materials. For this reason, the acid leaching process S30 in this embodiment can properly dissolve the valuable metals before Cu dissolves.

[0044] (4) Neutralization and precipitation process S40 In this step, a neutralizing agent is added to the metal solution obtained in the acid leaching step S30. This causes the hydroxide of Al (Al(OH)3) to separate and precipitate. As a result, it is possible to remove most of the Al from the metal solution containing Li, Al, Cu, Co, Ni, Mn, etc. As the neutralizing agent used in this step, an alkaline solution with a pH of 11 to 15 (preferably pH 12 to 14) can be used. As specific examples of the neutralizing agent, sodium hydroxide solution, calcium hydroxide, ammonia, etc. are mentioned. Also in this step, it is preferable to filter the metal solution after the precipitation of Al(OH)3. This allows the Al(OH)3 to be efficiently removed from the metal solution.

[0045] (5) Solvent extraction process S50 In this step, Co, Ni, and Mn are each extracted from the metal solution using a solvent extraction method. This makes it possible to prepare a Co solution, a Ni solution, and a Mn solution. In addition, in this step, impurities (such as Al) remaining in the metal solution can also be separated. Specifically, the solvent extraction step S50 in this embodiment includes a Mn extraction step S51, a Co extraction step S52, and a Ni extraction step S53, as shown in FIG. 5. The steps are described in detail below.

[0046] (a) Mn extraction step S51 In this step, an organic solvent (first extracting liquid) that has high extractability for Mn and low extractability for Li, Al, Cu, Co, and Ni is added to the metal solution. As the first extracting liquid, a phosphate extractant or an oxime extractant can be used. A specific example of a phosphate extractant is di-2-ethylhexyl phosphoric acid (D2EHPA). Also, a specific example of an oxime extractant is 2-hydroxy-5-nonylacetophenone oxime (LIX84), 5-dodecylsalicylardoxime (LIX860), 5-nonylsalicylaldoxime (ACORGA M5640), etc. Also, the first extracting liquid may be a mixture or dilution of these extractants. Then, in this step, the metal solution and the first extracting liquid are stirred to suspend them. As a result, Mn in the metal solution is dissolved in the first extracting liquid. Then, by leaving the mixture to stand until the two liquids are separated, it is possible to obtain a Mn solution in which Mn is dissolved in the first extraction liquid, and a metal solution from which Mn has been removed.

[0047] In this step, the extracted Mn solution (first extract liquid containing Mn) may be subjected to a back extraction process. In this back extraction process, the Mn solution (organic phase) and an acidic aqueous solution are first stirred and mixed in a mixer or the like. Then, the two liquids are allowed to stand until they are separated. This makes it possible to obtain an aqueous Mn solution in which Mn is dissolved in the acidic aqueous solution. Examples of the acidic aqueous solution used in the back extraction process include sulfuric acid, hydrochloric acid, and the like (particularly sulfuric acid).

[0048] (b) Co extraction step S52 In this step, an organic solvent (second extracting liquid) that has high extractability for Co and low extractability for Li, Al, 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 second extracting liquid can be obtained. Specific examples of the second extracting liquid include phosphonic acid esters such as 2-ethylhexyl phosphonic acid 2-ethylhexyl (PC-88A). In addition, the Co solution after extraction (second extracting liquid containing Co) may also be subjected to a back extraction process. This allows an aqueous Co solution to be obtained. The procedure for the back extraction process has already been described, so a duplicate description will be omitted.

[0049] (c) Ni extraction process S53 In this step, an organic solvent (third extractant) that has high extractability for Ni and low extractability for Li, Al, 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 third extractant can be obtained. Specific examples of the third extractant include carboxylic acid extractants such as neodecanoic acid and naphthenic acid. In addition, a back extraction process may be performed on the Ni solution after extraction (third extractant containing Ni). This allows an aqueous Ni solution to be obtained. The procedure for the back extraction process has already been described, so a duplicate description will be omitted.

[0050] (6)NCM crystallization process S60 In this step, crystals of a metal compound are precipitated from each of the Co solution, Ni solution, and Mn solution. In this step, a conventionally known crystallization process can be adopted without any particular limitation. For example, when a back-extraction process is performed in each of the Mn extraction steps S51 to S53, an aqueous mixed solution is prepared by mixing the Co solution, the Ni solution, and the Mn solution. Then, the pH of this mixed solution is controlled to be alkaline. This allows crystals of a metal compound to be precipitated. In addition, in the preparation of the mixed solution, the mixing ratio of each of the Co solution, the Ni solution, and the Mn solution may be changed as necessary. Then, in the adjustment of the pH, the mixed solution is dropped into a reaction tank together with an alkaline solution (ammonia water, sodium hydroxide aqueous solution). This allows spherical NiCoMn hydroxide (NCM precursor) to be crystallized.

[0051] (7) Li crystallization process S70 In the Li crystallization step S70, crystals of a Li compound are precipitated from the metal solution after the solvent extraction step S50. In this step, any conventionally known crystallization process can be adopted without any particular limitation. For example, in this step, sodium carbonate may be added to the metal solution. This allows lithium carbonate (Li2CO3) crystals to be precipitated. The Li compound generated in this step is not limited to lithium carbonate. For example, lithium hydroxide (LiOH) may be generated as the Li compound as necessary. In the generation of 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. After that, the solvent is evaporated and removed as necessary. This allows lithium hydroxide crystals to be precipitated.

[0052] (8) Active material generation process S80 In this process, the metal compound obtained in the NCM crystallization step S60 and the Li compound obtained in the Li crystallization step S70 are used to produce a battery material (positive electrode active material). Specifically, NiCoMn hydroxide (NCM precursor) and a Li compound (such as Li2CO3) are mixed and fired. This produces a positive electrode active material (lithium transition metal composite oxide) for a lithium ion secondary battery.

[0053] The manufacturing method of the battery material according to the present embodiment has been described above. As described above, in the manufacturing method according to the present embodiment, the roasting step S10 is performed in a state in which a large amount of reducing components are present in the recovery target and oxygen elements are not supplied from the outside. This causes the oxide of the valuable metal in the recovery target to be rapidly reduced to the state of an elemental metal. Since the elemental metal of this valuable metal has high acid solubility, it can be easily dissolved in the acid solution in the acid leaching step S30 before impurities such as Cu dissolve. This can reduce impurities in the metal solution, which can contribute to improving the recovery rate of valuable metals such as Co and Ni.

[0054] 3. Other embodiments An 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 in which various configurations are modified. Other examples of the embodiment of the technology disclosed herein will be described below.

[0055] (1) Each process after the roasting process In the manufacturing method according to the embodiment described above, after the roasting step S10, the sorting step S20 to the active material generating step S80 are performed. However, the description of the embodiment described above is not intended to limit the steps after the roasting step. In other words, in the manufacturing method disclosed herein, the steps after the roasting step can be appropriately added, deleted, or changed as necessary.

[0056] (a) Omission of the solvent extraction process For example, according to the manufacturing method disclosed herein, the solvent extraction step S50 can be omitted. Specifically, as described above, the technology disclosed herein can suppress the dissolution of Cu in the acid leaching step S30. Therefore, the metal solution after acid leaching mainly contains Li, Al, Ni, Co, and Mn. If Al can be properly separated from such a metal solution and Li can be recovered separately, the solution can contain valuable metals (Ni, Co, Mn) at high purity. In this case, the mixture of valuable metals used in the NCM crystallization step S60 can be obtained without performing the solvent extraction step S50. Note that Al can be sufficiently separated from the metal solution by the above-mentioned neutralization precipitation step S40. On the other hand, the following means can be given as an example of a means for recovering Li. First, when performing the roasting step S10, a non-metallic chlorine compound (such as HCl) is added to the recovery target and roasted. As a result, Li in the recovery target reacts with the non-metallic chlorine compound to generate LiCl. Next, a water leaching step is performed in which the recovery target after roasting is immersed in water. Since the LiCl is a water-soluble compound, Li can be recovered simply by bringing the object to be recovered into contact with water.

[0057] (b) Changes in the solvent extraction process In addition, the specific processing procedure in the solvent extraction step S50 can be changed as appropriate. For example, the solvent extraction step S50 in the above embodiment includes a Mn extraction step S51, a Co extraction step S52, and a Ni extraction step S53. This allows the Co solution, the Ni solution, and the Mn solution to be extracted separately. However, in the solvent extraction step S50, multiple valuable metals may be extracted simultaneously. For example, an organic solvent that has high extractability for Ni and Co and low extractability for Li, Al, and Cu may be added to the metal solution after Mn extraction. This allows Ni and Co to be extracted simultaneously. By extracting multiple valuable metals simultaneously in this way, it is possible to improve production efficiency by shortening the process.

[0058] (c) Addition of Li separation process The metal solution after the solvent extraction step S50 may be subjected to a Li separation step. Specifically, the metal solution after the solvent extraction step S50 contains Li as a main component. However, this metal solution may contain Cu that could not be removed in the acid leaching step S30 and Al that could not be removed in the neutralization precipitation step S40 in addition to Li. The Li separation step is a step of removing Cu and Al from this metal solution. This allows a high-purity Li compound to be obtained in the Li crystallization step S70. The means for preparing the Li solution is not particularly limited, and it is preferable to appropriately adopt a conventionally known means such as a solvent extraction method or an ion exchange method.

[0059] (d) Addition of Li enrichment process Furthermore, a Li concentration step may be carried out on the metal solution after the Li separation step. In this Li concentration step, the Li solution is heated to evaporate the solvent. This makes it possible to obtain a high-concentration Li solution, thereby improving the crystallization efficiency in the Li crystallization step S70. This Li concentration step may also be carried out on a metal solution that has not been subjected to the Li separation step. For example, if impurities (Cu, Al) are sufficiently removed between the acid leaching step S30 and the solvent extraction step S50, it is possible to carry out only the Li concentration step without carrying out the Li separation step. Even in this case, a high-concentration Li solution can be obtained.

[0060] (e) Changes in the NCM crystallization process In the above embodiment, the NCM crystallization step S60 is performed on the mixed solution obtained by mixing the Co solution, the Ni solution, and the Mn solution. This allows NiCoMn hydroxide to be crystallized as a metal compound containing Co, Ni, and Mn. However, in the NCM crystallization step, metal compounds may be crystallized individually from each of the Co solution, the Ni solution, and the Mn solution. When back extraction is performed with sulfuric acid as in the above embodiment, crystals of manganese sulfate (MnSO4) can be precipitated from the Mn solution by removing the solvent and cooling as necessary. Furthermore, crystals of cobalt sulfate (CoSO4) are precipitated from the Co solution. And, crystals of nickel sulfate (NiSO4) are precipitated from the Ni solution. A battery material (positive electrode active material) can be produced by mixing the NCM precursor synthesized from the crystals of these sulfates with a Li compound and firing the mixture.

[0061] (2) Reducing components used in the roasting process In addition, the detailed conditions in the roasting step S10 can also be changed as appropriate. For example, in the manufacturing method according to the above embodiment, carbon element is used as the reducing component. However, as described above, the reducing component is not particularly limited as long as it is a component that can reduce Ni and Co in the heating step. Examples of reducing components other than carbon element (C) include metallic reducing components such as lithium (Li), cesium (Cs), potassium (K), barium (Ba), strontium (Sr), calcium (Ca), sodium (Na), magnesium (Mg), aluminum (Al), titanium (Ti), zirconium (Zr), and manganese (Mn). It is preferable that these metallic reducing components are present in the recovery target in the form of sulfite or the like. For example, when calcium sulfite (CaSO3) is used as the reducing component, valuable metals are reduced to elemental metals in the heating step, and calcium oxide (CaO) is generated. In this case, the threshold value in the determination step is set to a value equal to or greater than the stoichiometric ratio (1 / 1) of CaO. This allows the valuable metals in the object to be recovered to be appropriately reduced to the state of elemental metal. In the measurement step S12, examples of a means for measuring the metal-based reducing components include ICP, SEM-EDS analysis, and XRF analysis. The reducing components to be determined in the determination step S13 and the reducing components to be added in the reducing component addition step S14 may be the same or different. For example, if it is determined in the determination step S13 that the carbon element (C) is insufficient, calcium sulfite (CaSO3) may be added in the reducing component addition step S14. Even in this case, the valuable metals can be appropriately reduced to the state of elemental metal in the heating step S15.

[0062] [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.

[0063] 1. Sample preparation (Example 1) In this test, a mixture of positive and negative electrode plates was used as the object to be recovered, and the roasting process was carried out on the object to be recovered. Specifically, the positive electrode plate used was a positive electrode core (Al foil) with a positive electrode active material layer applied to its surface. 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. On the other hand, a negative electrode plate was used in which a negative electrode active material layer was applied to the surface of a negative electrode core (Cu foil). In addition, a carbon material (graphite) was used as the negative electrode active material. Then, this mixture of positive and negative electrode plates was crushed, and the powder was sieved through a sieve with 500 μm openings to prepare a test sample.

[0064] Next, a part of the test sample was taken and dissolved in sulfuric acid. Then, ICP was performed on the solution to measure the total amount of Ni, Co, and Mn, M. The composition of the positive electrode active material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 Based on the total amount of substance M, the amount of substance N of the oxygen element was set to twice the total amount of substance M (N=2M). In this test, a thermogravimetric differential thermal analysis (TG-DTA) was also performed on a part of the test sample. In this thermogravimetric differential thermal analysis, the test sample was heated in an air atmosphere at 800°C. In this analysis, the heating rate from room temperature (20°C) to 800°C was set to 5°C / min. This allowed the amount of carbon in the test sample to be measured. Next, it was examined whether the measured amount of substance ratio (C / O ratio) of oxygen element to carbon element was equal to or greater than the stoichiometric ratio (1 / 2) of CO2. As a result, in Example 1, the C / O ratio was equal to or greater than 1 / 2.

[0065] Next, in Example 1, the test sample was roasted under an inert atmosphere. Specifically, the test sample was placed in an electric furnace, and the temperature inside the furnace was raised to 600°C while supplying Ar gas. The temperature rise rate was set to 5°C / min. Then, roasting was performed for 5 hours while maintaining the temperature inside the furnace at 600°C. Thereafter, the temperature inside the furnace was cooled to 50°C, and the test sample was collected.

[0066] (Examples 2 to 8) In Examples 2 to 8, at least one of the conditions of the heating temperature, the heating atmosphere, and the substance amount ratio (C / O) of the test sample was changed from Example 1. The conditions of each example are shown in Table 1. In Examples 2 to 8, the preparation of the test sample and the roasting process were carried out in the same manner as in Example 1 above, except for the conditions shown in Table 1.

[0067] 2.Evaluation Test (1)XRD analysis X-ray diffraction (XRD) analysis using a Mo radiation source was performed on the test sample after roasting to evaluate the state of Ni element in the test sample. Specifically, as shown in FIG. 6 (XRD chart of Example 3), peaks are confirmed near 19° and 20° in the test sample after roasting. Among these, a peak (NiO peak) derived from Ni oxide can be confirmed near 19°. On the other hand, a peak (Ni peak) derived from metal element Ni can be confirmed near 20°. In this test, the peak intensity ratio (Ni / NiO) of the Ni peak to the NiO peak was calculated. When this peak intensity ratio was less than 1, it was evaluated that a NiO-dominant sample was produced. On the other hand, when the peak intensity ratio was 1 or more, it was evaluated that a Ni-dominant sample was produced. The results are shown in Table 1.

[0068] In addition, the XRD analysis also evaluated the state of each of Ni and Co in the test sample. Specifically, in the above XRD chart, a sample in which only a NiO peak was confirmed was deemed to be "NiO occupying the majority ("NiO" in Table 1)". In addition, when both a NiO peak and a Ni peak were confirmed, it was deemed to be "NiO and Ni mixed ("NiO+Ni" in Table 1)". And, when only a Ni peak was confirmed, it was deemed to be "Ni occupying the majority ("Ni" in Table 1)". In addition, the state of the remaining metal element (Co) in the test sample after roasting was analyzed according to the same procedure as the above Ni state evaluation. The results are shown in Table 1.

[0069] (2) Recovery rate in acid leaching The roasted test sample was subjected to acid leaching, and the leaching rate of each metal element (Ni, Co, Cu) was calculated. Specifically, the roasted test sample was first added to 1 mol / L sulfuric acid (H2SO4). Then, the temperature of the acid solution was maintained at room temperature (25°C) and the stirring process was continued for 6 hours at a stirring speed of 500 rpm. Next, the dissolved metal solution was filtered, and then ICP was performed on the dissolved solution. As a result, the amounts of Ni, Co, and Cu in the metal solution were measured. Then, the leaching rate of each metal element was calculated based on the following formula (3). Note that the "amount of substance before acid leaching" in formula (3) is a value calculated by measuring and grasping the amount of substance per 1 g by ICP analysis and multiplying it by the weight of the sample added to the acid. Leaching rate = (amount of substance in metal solution / amount of substance before acid leaching) x 100 (3)

[0070] [Table 1]

[0071] As shown in Table 1, in Example 6, the leaching rate of Ni and Co was significantly decreased. This is because most of the valuable metals in the recovery target were oxidized as a result of roasting in an air atmosphere, and were difficult to dissolve in the acid solution at a low temperature of 25 ° C. In contrast, in Example 7, the leaching rate of Ni and Co was significantly improved compared to Example 6. As a result of analyzing the sample of Example 7, it was found that most of the valuable metals (Ni, Co) were reduced to the state of elemental metals. From this, it was found that roasting in a situation where there are many reducing components (carbon) in the recovery target and oxygen elements are not supplied from the outside can contribute to improving the recovery rate of Ni and Co. In addition, as a result of comparing Examples 1 to 3, Example 5, and Example 8, it was confirmed that the proportion of elemental metals in the recovery target after roasting increases as the heating temperature increases, and the leaching rate in acid leaching tends to improve.

[0072] Although the technology disclosed herein has been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. In other words, the technology disclosed herein includes the embodiments described in the following items 1 to 8.

[0073] <Item 1> A preparation step of preparing a recovery target containing at least one of Ni and Co; a measuring step of measuring the amounts of oxygen element and reduced components contained in the recovery target; a determination step of determining whether or not the substance amount ratio of the reducing component to the oxygen element is equal to or greater than a threshold value based on a stoichiometric ratio of an oxide of the reducing component; a reducing component adding step of adding the reducing component to the recovery object when the determination result of the determining step is less than the threshold value; a heating step of heating the recovery target under an inert atmosphere; A method for producing a battery material comprising the steps of:

[0074] <Item 2> 2. The method for producing a battery material according to item 1, wherein the reducing component is a carbon element, and the threshold value is a value equal to or greater than the stoichiometric ratio of CO2.

[0075] <Item 3> 3. The method for producing a battery material according to item 1 or 2, wherein the heating step heats the target to be recovered at 650°C to 1000°C.

[0076] <Item 4> 4. The method for producing a battery material according to any one of items 1 to 3, wherein the heating step heats the target to be recovered under an argon atmosphere or a nitrogen atmosphere.

[0077] <Item 5> 5. The method for producing a battery material according to any one of items 1 to 4, wherein the measuring step measures amounts of substances of metal elements in the target to be recovered, and calculates an amount of substance of the oxygen element based on the amounts of substances of the metal elements.

[0078] <Item 6> 6. The method for producing a battery material according to any one of items 1 to 5, wherein the target to be recovered includes at least one selected from the group consisting of a lithium nickel composite oxide, a lithium cobalt composite oxide, a lithium nickel manganese composite oxide, a lithium manganese cobalt composite oxide, a lithium nickel cobalt composite oxide, and a lithium nickel manganese cobalt composite oxide.

[0079] <Item 7> 7. The method for producing a battery material according to any one of items 1 to 6, further comprising an acid leaching step of immersing the object to be recovered after the heating step in an acid solution.

[0080] <Item 8> 8. The method for producing a battery material according to item 7, wherein the temperature of the acid solution in the acid leaching step is 15°C to 50°C. [Explanation of symbols]

[0081] 1. Lithium-ion secondary battery 10 Cases 12 Positive terminal 14 Negative terminal 20 Electrode body 30 Positive plate 32 Positive electrode core 34 Cathode active material layer 40 Negative 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; a measuring step of measuring the amounts of oxygen element and reduced components contained in the recovery target; a determination step of determining whether or not the substance amount ratio of the reducing component to the oxygen element is equal to or greater than a threshold value based on a stoichiometric ratio of an oxide of the reducing component; a reducing component adding step of adding the reducing component to the recovery object when the determination result of the determining step is less than the threshold value; a heating step of heating the recovery target under an inert atmosphere; A method for producing a battery material comprising the steps of:

2. The reducing component is carbon element, and the threshold value is CO ２ The method for producing a battery material according to claim 1 , wherein the ratio of the stoichiometric ratio of the total amount of the lithium ions is equal to or greater than the stoichiometric ratio of the total amount of the lithium ions.

3. The method for producing a battery material according to claim 1 , wherein the heating step heats the recovery target at 650° C. to 1000° C.

4. The method for producing a battery material according to claim 1 , wherein the heating step heats the target to be recovered under an argon atmosphere or a nitrogen atmosphere.

5. The method for producing a battery material according to claim 1 , wherein the measuring step comprises measuring amounts of substance of metal elements in the target to be recovered, and calculating the amount of substance of the oxygen element based on the amounts of substance of the metal elements.

6. 2. The method for producing a battery material according to claim 1, wherein the target to be recovered includes at least one selected from the group consisting of a lithium nickel composite oxide, a lithium cobalt composite oxide, a lithium nickel manganese composite oxide, a lithium manganese cobalt composite oxide, a lithium nickel cobalt composite oxide, and a lithium nickel manganese cobalt composite oxide.

7. The method for producing a battery material according to any one of claims 1 to 6, further comprising an acid leaching step of immersing the target to be recovered after the heating step in an acid solution.

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