Method for manufacturing battery material

Abstract

To improve the efficiency of recovering Li 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 Li; and a chlorination-heating step S12 of heating the recovery target and a non-metal chlorine compound together and generating LiCl. The LiCl is easily dissolved in water and Li can be thus easily separated from the recovery target. The technique disclosed herein can separate Li from the recovery target immediately after the chlorination-heating step S12 and the Li recovery efficiency can be significantly 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] Examples of this recovery technique are disclosed in Patent Documents 1 and 2. For example, the treatment method described in Patent Document 1 includes a leaching step in which lithium-ion battery scrap (recovery target) is leached with acid to obtain a leaching solution containing at least fluoride ions and aluminum ions, a neutralization step in which the leaching solution is neutralized to a pH range of 5.3 to 5.5 and at least a portion of the aluminum ions are removed from the leaching solution to obtain a neutralized solution, and an extraction step in which the neutralized solution is subjected to solvent extraction to extract the remaining aluminum ions from the neutralized solution. Furthermore, the treatment method described in Patent Document 1 also includes a recovery step in which valuable metals (Ni, Co, Li) are recovered from the extraction residue after the extraction step. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-164971 A [Patent Document 2] JP 2020-105598 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned conventional recovery techniques have a problem in that the recovery rate of lithium (Li) is low. Specifically, in the conventional techniques, the metal solution after acid leaching is neutralized to remove Al. Next, valuable metals other than Li (Ni, Co, Mn, etc.) are sequentially recovered using a solvent extraction method. Li is then recovered from the residual liquid after the solvent extraction. That is, in the conventional techniques, various separation processes are performed before Li is recovered. For this reason, in the conventional techniques, it is difficult to achieve a high Li recovery rate because Li is removed by a separation process before Li is recovered. [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 method for producing a battery material disclosed herein includes a preparation step of preparing a recovery target containing at least Li, and a chlorination heating step of heating the recovery target together with a non-metallic chloride compound to produce LiCl.

[0009] In the manufacturing method having the above configuration, a chlorination heating step is carried out in which the recovery target is heated in an environment in which a non-metallic chlorine compound is present. As a result, Li in the recovery target is chlorinated to generate lithium chloride (LiCl). This LiCl is easily soluble in water, so Li can be easily recovered from the recovery target. In other words, the technology disclosed herein can directly separate Li from the recovery target immediately after the chlorination heating step, which can contribute to a significant improvement in the recovery efficiency of Li. [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. 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 a valuable metal such as lithium (Li) 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. 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 metal material containing at least lithium (Li). Examples of such positive electrode active materials include lithium transition metal composite oxides such as lithium nickel composite oxide, lithium cobalt composite oxide, lithium manganese composite oxide, lithium nickel manganese composite oxide, lithium manganese cobalt composite oxide, lithium nickel cobalt composite oxide, and lithium nickel manganese cobalt composite oxide. Other examples of positive electrode active materials include lithium transition metal phosphate compounds such as lithium iron phosphate, lithium manganese phosphate, and lithium manganese iron phosphate. According to the manufacturing method of this embodiment, Li can be efficiently recovered from a recovery target containing these positive electrode active materials. In addition, in the manufacturing method according to the present embodiment, other valuable metals such as Ni, Co, and Mn can also be efficiently recovered from the recovery target. Therefore, the positive electrode active material in the recovery target is particularly preferably a lithium transition metal composite oxide containing Ni, Co, and Mn. In addition, examples of the conductive material include carbon materials such as acetylene black and graphite. In addition, 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 (SiC), a composite containing carbon and silicon, silicon oxide (SiO XExamples of the binder include resin materials such as styrene butadiene rubber (SBR). Examples of the thickener 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) also contains Li, 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 impossible to use it in a product. Such an electrode body may also be the collection target since it contains Li. In other words, the collection target of the manufacturing method disclosed herein is not particularly limited to a specific structure as long as it contains at least Li.

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

[0022] 3, the method for producing a battery material according to this embodiment includes a roasting step S10, a water dissolving step S20, a Mn crystallization step S30, a Li crystallization step S40, a sorting step S50, an NH3 leaching step S60, a solvent extraction step S70, an NC crystallization step S80, and an active material production step S90. 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 step S10 in this embodiment includes a preparation step S11 and a chlorination heating step S12. This can significantly improve the Li recovery efficiency. This will be specifically described below.

[0025] (a) Preparation step S11 In this process, a recovery target containing at least Li 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 lithium (Li), nickel (Ni), cobalt (Co), manganese (Mn), etc. can also be recovered (manufactured).

[0026] (b) Chloridation heating step S12 In the chlorination heating step S12, the object to be recovered is heated together with a nonmetallic chlorine compound. This causes Li in the object to be recovered to react with Cl in the nonmetallic chlorine compound to produce lithium chloride (LiCl). In addition, if the object to be recovered contains Mn, this Mn can also react with Cl to produce manganese chloride (MnCl2). On the other hand, in this step, Li and Mn are preferentially chlorinated, so metal elements (Ni, Co, Al, Cu) are hardly chlorinated.

[0027] In this specification, the term "non-metallic chlorine compound" refers to a chlorine compound that does not contain a metal element. The non-metallic chlorine compound is not particularly limited as long as it is a compound that can decompose during heating to supply Cl to Li in the recovery target, and a conventionally known compound can be appropriately selected. Examples of such non-metallic chlorine compounds include inorganic chlorine compounds such as hydrogen chloride (HCl), ammonium chloride (NH4Cl), ammonium perchlorate (NH4ClO4), perchloric acid (HClO4), chloric acid (HClO3), chlorous acid (HClO2), and hypochlorous acid (HClO). Other examples of non-metallic chlorine compounds include organic chlorine compounds such as chloromethane, dichloromethane, trichloromethane (chloroform), and tetrachloroethylene. These non-metallic chlorine compounds can supply Cl without mixing other metal elements that may become impurities into the recovery target.

[0028] In addition, the state of the nonmetallic chlorine compound is not particularly limited as long as Cl can be appropriately supplied to the object to be recovered. For example, when the nonmetallic chlorine compound is a gas, the nonmetallic chlorine compound may be mixed with a heated gas described later and then supplied into a heating furnace. When the nonmetallic chlorine compound is a liquid or solid, the mixture of the object to be recovered and the nonmetallic chlorine compound may be heated. In either case, Cl in the nonmetallic chlorine compound can be appropriately supplied to the object to be recovered.

[0029] The heating temperature in this step may be 500°C or higher, 525°C or higher, 550°C or higher, or 575°C or higher. As the heating temperature increases, LiCl tends to be more easily generated. In particular, the heating temperature is preferably 600°C or higher, more preferably 800°C or higher, and particularly preferably 900°C or higher. This improves the Li recovery rate significantly. On the other hand, from the viewpoint of LiCl generation, 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 addition, 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.

[0030] In addition, although this is not a limiting factor of the technology disclosed herein, in this process, it is preferable to heat the object to be recovered under an inert atmosphere. This can suppress the generation of metal oxides (lithium oxide (Li2O), etc.) and improve chlorination selectivity. Specific examples of the inert gas at this time include inert gases such as argon gas and nitrogen gas. In addition, the "inert atmosphere" in this specification refers to a heating atmosphere containing the above-mentioned inert gas as a main component. In other words, the "inert atmosphere" in this specification 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 trace 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). However, if the object to be recovered contains sufficient reducing components (carbon (C), etc.), LiCL can be appropriately generated even if oxygen element exceeding the above range is mixed in.

[0031] In addition, in this process, it is preferable to provide a water trap that passes the used heated gas (exhaust gas discharged from the heating furnace) through water. This allows LiCl in the exhaust gas to be collected by the water trap, further improving the Li recovery rate. The water after the exhaust gas has passed through it is preferably mixed with the Li solution prepared in the water dissolving process S20 described below. This allows Li to be recovered efficiently.

[0032] (2) Water dissolution process S20 Next, in the water dissolution step S20, the recovery target after the chlorination heating step S12 is mixed with water. As described above, the recovery target after the chlorination heating step S12 contains LiCl. This LiCl is easily dissolved in water such as pure water or ion-exchanged water. As a result, in this step, a Li solution in which LiCl is dissolved in water is obtained. In this way, in the manufacturing method according to the present embodiment, Li can be easily separated from the recovery target immediately after the chlorination heating step S12. As a result, a Li solution containing high-purity Li can be obtained.

[0033] The immersion time in this step is preferably 10 minutes or more, more preferably 15 minutes or more, more preferably 20 minutes or more, and particularly preferably 25 minutes or more. This allows LiCl in the object to be recovered to be sufficiently dissolved in water. If the immersion time exceeds 30 minutes, almost all of the LiCl in the object to be recovered can be dissolved in water. Therefore, in consideration of production efficiency, the upper limit of the immersion time is preferably 120 minutes or less, more preferably 90 minutes or less, more preferably 60 minutes or less, and particularly preferably 45 minutes or less. The temperature of the water in this step is not particularly limited and can be appropriately set in the range of 10°C to 60°C.

[0034] (3) Mn precipitation step S30 In addition, when the recovery target contains Mn, MnCl2 may be generated in the chlorination heating step S12. This MnCl2 also dissolves in water, so the Li solution after the water dissolution step S20 contains Mn. In this step, this Mn is recovered from the Li solution. For example, in this step, an aqueous solution of sodium hydroxide is added to the Li solution. This causes manganese hydroxide (Mn(OH)2) to precipitate from the Li solution. Then, the Li solution can be filtered to recover the Mn.

[0035] (4) Li precipitation process S40 In this step, crystals of a Li compound are precipitated from the Li solution. In this step, any conventionally known crystallization process can be used without any particular restrictions. For example, in this step, sodium carbonate may be added to the Li solution. This allows lithium carbonate (Li2CO3) crystals to be precipitated from the Li solution. The Li compound produced in this step is not limited to lithium carbonate. For example, lithium hydroxide (LiOH) may be produced as the Li compound, as necessary. In producing this lithium hydroxide, first, the lithium carbonate precipitated from the metal solution is dissolved (or suspended) in a specified solvent. Then, calcium hydroxide is added to this solution. Thereafter, the solvent is evaporated and removed as necessary. This allows lithium hydroxide crystals to be precipitated.

[0036] As described above, in the manufacturing method according to this embodiment, Li can be recovered from the metal solution (Li solution) generated after the roasting step S10. That is, in the manufacturing method according to this embodiment, the number of steps from the completion of the roasting step S10 to the recovery of Li can be significantly reduced. As a result, a high Li recovery rate can be achieved.

[0037] (5) Sorting process S50 On the other hand, metal elements (Ni, Co, Al, Cu, etc.) that were not converted to chlorination in the roasting step S10 remain in the solid content (recovery target) after the water dissolving step S20. When other valuable metals (Ni and Co) are contained in the residual metals, it is preferable to recover these valuable metals. In contrast, in the manufacturing method according to the present embodiment, the sorting step S50 is performed on the solid content after the water dissolving step S20. In this step, each member contained in the recovery target after the water dissolving step S20 is sorted using a sieve. For example, when the process waste of the positive electrode plate 30 is the recovery target, it is preferable to sort the positive electrode core 32 from the process waste using a sieve and remove it from the recovery target. Also, when the electrode body 20 is the recovery target, it is preferable to remove the negative electrode plate 40 from the recovery target in addition to the positive electrode core 32. Furthermore, when the lithium ion secondary battery 1 is the recovery target, it is preferable to remove the case 10 from the recovery target in addition to the positive electrode core 32 and the negative electrode plate 40. This reduces the content of impurities (Al, Cu, etc.) in the objects to be recovered, which contributes to improving the recovery efficiency of valuable metals (Co, Ni). As in this embodiment, the sorting process is preferably performed after the water dissolution process. This allows LiCl attached to the objects to be removed in the sorting process (positive electrode core, negative electrode plate, case, etc.) to be recovered first.

[0038] 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.

[0039] In addition, the sorting step S50 is not a step intended to completely remove impurities such as Al and Cu from the object to be recovered. Although details will be described later, even if impurities remain in the object to be recovered, they can be sufficiently removed in subsequent steps (NH3 leaching step S60, solvent extraction step S70, etc.). 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.

[0040] (6) NH3 leaching process S60 In this process, the solid content after the water dissolving step S20 (e.g., after the sorting step S50) is immersed in an aqueous ammonia solution. As a result, among the metal elements (Ni, Co, Al, Cu) in the solid content, Ni, Co, Cu, etc. are dissolved in the aqueous ammonia solution. This makes it possible to obtain a metal solution containing Ni, Co, and Cu. On the other hand, Al, which is difficult to dissolve in an aqueous ammonia solution, remains in the solid content. This makes it possible to easily remove Al as an impurity.

[0041] (7) Solvent extraction process S70 In this step, Co and Ni are each extracted from the metal solution using a solvent extraction method. This makes it possible to obtain a Co solution and a Ni solution. In addition, in this step, impurities (Al, Cu, etc.) mixed in the metal solution can also be separated. Specifically, the solvent extraction step S70 in this embodiment includes a Co extraction step and a Ni extraction step. The steps are specifically described below.

[0042] (a) Co extraction process In this step, an organic solvent (first extracting liquid) that has high extractability for Co and low extractability for Ni, Al, and Cu 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 first extracting liquid include phosphonic acid esters such as 2-ethylhexyl 2-ethylhexyl phosphonic acid (PC-88A).

[0043] In this step, the extracted Co solution (first extract 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 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 Co solution in which Co 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).

[0044] (b)Ni extraction process In this step, an organic solvent (second extracting liquid) that has high extractability for Ni and low extractability for 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 second extracting liquid can be obtained. Specific examples of the second extracting liquid include carboxylic acid extractants such as neodecanoic acid and naphthenic acid. In addition, a back extraction process may also be performed on the Ni solution after extraction (second extracting liquid 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.

[0045] (8)NC crystallization process S80 In this step, crystals of a metal compound containing Ni and Co are precipitated. In this step, a conventionally known crystallization process can be adopted without any particular restrictions. For example, when a back-extraction process is performed in each of the Co extraction process and the Ni extraction process, an aqueous mixed solution is prepared by mixing a Co solution and a Ni solution. This allows a mixed solution containing Ni and Co to be obtained. 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 Ni and Co 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 NiCo hydroxide to be crystallized.

[0046] (9) Active material generation step S90 In this process, the Li compound, Mn compound, and NiCo compound obtained in the above-mentioned processes are used to produce a battery material (positive electrode active material). Specifically, first, the NiCo compound (NiCo hydroxide), the Mn compound (Mn(OH)2), and the Li compound (Li2CO3, etc.) are mixed in a predetermined ratio. Then, this 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] The manufacturing method of the battery material according to the present embodiment has been described above. As described above, in the roasting step S10 of the manufacturing method according to the present embodiment, the chlorination heating step S12 is carried out, in which the recovery target is heated in an environment in which a nonmetallic chlorine compound is present. As a result, Li in the recovery target is chlorinated to generate lithium chloride (LiCl). This LiCl is easily soluble in water, so that Li can be easily recovered from the recovery target. That is, according to the technology disclosed herein, Li can be directly separated from the recovery target immediately after the roasting step S10. As a result, the number of steps from the completion of the roasting step S10 to the recovery of Li can be significantly reduced, so that a high Li recovery rate can be achieved.

[0048] 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.

[0049] In the manufacturing method according to the embodiment described above, after the roasting step S10, the sorting step S50 to the active material generating step S90 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.

[0050] (1) Omission of the Mn precipitation process For example, in the manufacturing method according to the embodiment described above, since Mn is contained in the Li solution after the water dissolving step S20, the Mn precipitating step S40 is performed before the Li precipitating step S40 is performed. However, if the recovery target does not contain Mn, a Li solution containing only Li can be obtained in the water dissolving step S20. In this case, the Mn precipitating step S30 can be omitted.

[0051] (2) Omission of processes after the NH3 leaching process In the manufacturing method according to the embodiment described above, valuable metals such as Ni and Co are recovered by carrying out the NH3 leaching step S60 to the NCM crystallization step S80. However, if the object to be recovered does not contain Ni or Co, the steps after the NH3 leaching step can be omitted. In addition, the steps after the NH3 leaching step may be appropriately changed depending on the type of metal element contained in the object to be recovered.

[0052] (3) Changes in the solvent extraction process In addition, the specific processing procedure in the solvent extraction step S70 can be changed as appropriate. For example, the solvent extraction step S70 in the above embodiment includes a Co extraction step and a Ni extraction step. This allows the Co solution and the Ni solution to be extracted separately. However, in the solvent extraction step S70, Ni and Co may be extracted simultaneously. Specifically, an organic solvent that has high extractability for Ni and Co and low extractability for Al and Cu may be added to the metal solution. By extracting Ni and Co simultaneously in this way, the manufacturing efficiency can be improved by shortening the process.

[0053] (4) Omission of the solvent extraction process In addition, in the manufacturing method according to the above embodiment, a lithium ion secondary battery is used as the object to be recovered. Such an object to be recovered contains Cu derived from the negative electrode core, etc. Therefore, in addition to Ni and Co, Cu is mixed into the metal solution generated in the NH3 leaching step S60. In this case, it is preferable to remove Cu from the metal solution by performing the solvent extraction step S70 as in the above embodiment. On the other hand, when a recovery object that does not contain Cu (such as a process waste material of a positive electrode plate) is used, Cu is not mixed into the metal solution generated in the NH3 leaching step S60. In this case, the solvent extraction step S70 can be omitted, and the NC crystallization step S80 can be performed on the metal solution obtained in the NH3 leaching step S60.

[0054] (5)Addition of Li separation process Furthermore, a Li separation step may be performed on the Li solution before performing the Li precipitation step S40. Specifically, the Li solution contains Li as a main component. However, this Li solution may contain other metal components (Cu, Al, etc.). The Li separation step is a step of removing impurities from the Li solution. This makes it possible to obtain a high-purity Li compound in the Li crystallization step S40. 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.

[0055] (6)Addition of Li enrichment process In addition, a Li concentration step may be performed on the Li 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 S40. This Li concentration step may be performed on a metal solution that has not been subjected to a Li separation step. For example, if impurities have been sufficiently removed in the water dissolution step S20 or the Mn precipitation step S30, only the Li concentration step may be performed without performing the Li separation step. Even in this case, a high-concentration Li solution can be obtained.

[0056] (7) Changes in the NC crystallization process In the above embodiment, the NC crystallization step S80 is performed on the mixed solution containing Ni and Co. This allows the crystallization of a metal compound (NiCo hydroxide) containing Ni and Co. However, metal compounds may be crystallized from each of the Co solution and the Ni solution separately. For example, when back extraction is performed with sulfuric acid as in the above embodiment, crystals of cobalt sulfate (CoSO4) can be precipitated from the Co solution by removing the solvent and cooling as necessary. Also, crystals of nickel sulfate (NiSO4) are precipitated from the Ni solution. The NC crystallized product synthesized from the crystals of these sulfates is calcined together with a Li compound and a Mn compound to produce a battery material (positive electrode active material).

[0057] In the above embodiment, NiCo hydroxide is crystallized from a mixed solution containing Ni and Co. However, a metal compound containing Ni, Co, and Mn (NiCoMn hydroxide) may be generated as a precursor of the positive electrode active material. Specifically, manganese hydroxide (Mn(OH)2) obtained in the Mn precipitation step S30 is added to a mixed solution containing Ni and Co. This makes it possible to obtain a mixed solution containing Ni, Co, and Mn. Then, by carrying out a crystallization process on this mixed solution, a metal compound containing Ni, Co, and Mn (NiCoMn hydroxide) can be generated. This NiCoMn hydroxide is calcined together with a Li compound to generate a positive electrode active material.

[0058] [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.

[0059] 1. First test In this test, the positive electrode plate was used as the recovery target, and the roasting process was carried out on the recovery target. 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 / 3O2) was used. This positive electrode plate was then cut into a 2 cm x 4 cm sheet to serve as a test sample.

[0060] Next, in this test, the test sample was heated together with a nonmetallic chlorine compound. Specifically, the test sample was placed in a crucible and housed in an electric furnace. Then, the temperature inside the furnace was raised to 600°C while supplying a mixed gas of HCl gas and Ar gas. A water trap was placed in the exhaust pipe of the electric furnace, and the exhaust gas after heating was passed through water. The temperature rise rate in this process was set to 5°C / min. The supply amount of the mixed gas was set to 4.2L / min. Then, roasting was performed for 1 hour 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. The mixed gas was continued to be supplied into the furnace until the sample was collected.

[0061] Next, in this test, the test sample after roasting was immersed in water for 30 minutes, and the water was filtered to obtain a Li solution. Then, water recovered from the water trap of the electric furnace was added to this Li solution. Next, 30 wt% NaOH aqueous solution was dropped until the pH of the Li solution became 11. Then, Mn was removed from the Li solution by recovering the precipitate (Mn(OH)2). Next, 10 wt% Na2CO3 aqueous solution was added to the Li solution to precipitate lithium carbonate (Li2CO3). Then, all the precipitated Li2CO3 was collected and the amount of Li was measured by ICP. Then, the recovery rate of Li was calculated based on the following formula (1). Note that the "Li amount before roasting" in formula (1) is the amount of Li obtained by analyzing the reference sample cut out from the positive plate by ICP. Li recovery rate = (Li mass of precipitated Li2CO3 / Li mass of positive electrode plate before roasting) × 100 (1)

[0062] As a result of the above-mentioned test, a very high Li recovery rate of 90% or more was surprisingly confirmed. Although details are omitted, it has been confirmed that when Li is recovered from the residual liquid after neutralization precipitation and solvent extraction as in Patent Document 1, the Li recovery rate is about 20 to 60%. From this, it was found that by heating the recovery target together with a non-metallic chlorine compound in the roasting process to generate LiCl, it is possible to contribute to a significant improvement in the Li recovery efficiency. This is believed to be because it is possible to omit the multiple separation steps as in the conventional technology and directly separate Li from the recovery target immediately after the roasting process.

[0063] 2. Second test In the second test, the Li recovery rate was measured for two samples in which the heating temperature in the chlorination heating step was different. In addition, in this test, the recovery rates of metals other than Li were also measured. The details are explained below.

[0064] 1. Sample Preparation (1) Sample 1 For sample 1, a Li solution was obtained under the same conditions as in the first test. That is, for sample 1, the positive plate was roasted at 600°C together with a nonmetallic chlorine compound (HCl gas). Then, the roasted positive plate was immersed in water for 30 minutes to obtain a Li solution. In this test, water recovered from the water trap of the electric furnace was also added to the Li solution.

[0065] (2) Sample 2 For sample 2, a Li solution was obtained under the same conditions as for sample 1 (first test), except that the heating temperature was changed to 927°C.

[0066] 2.Evaluation Test In this test, the elements contained in the Li solution of each sample were analyzed by ICP. Specifically, ICP analysis was performed on the water (Li solution) in which the test sample was immersed, without pretreatment to separate specific elements, targeting Li, Ni, Co, Mn, and Al. Then, based on the measurement results, the water leaching rate of each of the above-mentioned elements was calculated. This water leaching rate was calculated based on the following formula (2). As with the above formula (1), the "atomic weight before roasting" is the atomic weight obtained by ICP analysis of a reference sample cut out from the positive plate. The water leaching amount of each element in Samples 1 and 2 is shown in Table 1. Water leaching rate = (atomic weight in Li solution / atomic weight in positive plate before roasting) x 100 (2)

[0067] [Table 1]

[0068] As shown in Table 1, a high Li recovery rate of over 90% was confirmed in both Samples 1 and 2. On the other hand, when comparing Sample 1 and Sample 2, Sample 2 had a higher Li recovery rate. This demonstrated that a heating temperature of 900°C or higher is suitable for the chlorination heating process. It was also confirmed that the Li solution after water leaching contained mainly Li and Mn, with almost no Ni, Co, or Al.

[0069] 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.

[0070] <Item 1> A preparation step of preparing a recovery target containing at least Li; a chlorination heating step of heating the target to be recovered together with a non-metallic chlorine compound to generate LiCl; A method for producing a battery material comprising the steps of:

[0071] <Item 2> 2. The method for producing a battery material according to item 1, wherein the nonmetallic chlorine compound comprises at least one selected from the group consisting of hydrogen chloride, ammonium chloride, ammonium perchlorate, perchloric acid, chloric acid, hypochlorous acid, chloromethane, dichloromethane, trichloromethane, and tetrachloroethylene.

[0072] <Item 3> 3. The method for producing a battery material according to item 1 or 2, wherein the chlorination heating step heats the target to be recovered at 500°C to 1000°C.

[0073] <Item 4> 4. The method for producing a battery material according to any one of items 1 to 3, wherein the chlorination heating step heats the recovery target under an inert atmosphere.

[0074] <Item 5> 5. The method for producing a battery material according to any one of items 1 to 4, wherein the target to be recovered includes at least one selected from the group consisting of lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel manganese composite oxide, lithium manganese cobalt composite oxide, lithium nickel cobalt composite oxide, lithium nickel manganese cobalt composite oxide, lithium iron phosphate, lithium manganese phosphate, and lithium manganese iron phosphate.

[0075] <Item 6> 6. The method for producing a battery material according to any one of items 1 to 5, further comprising a water dissolving step of immersing the recovery target after the chlorination heating step in water to obtain a Li solution in which the LiCl is dissolved in the water.

[0076] <Item 7> 7. The method for producing a battery material according to item 6, further comprising a Li precipitation step of precipitating a crystal of a Li compound from the Li solution.

[0077] <Item 8> 8. The method for producing a battery material according to item 6 or 7, wherein the recovery target contains at least one of Ni and Co, and the method further comprises an NH3 leaching step of immersing the solid obtained after the water dissolution step in an aqueous ammonia solution to obtain a metal solution containing at least one of the Ni and the Co.

[0078] <Item 9> 4. The method for producing a battery material according to item 3, wherein the chlorination heating step heats the recovery target at 900° C. or higher. [Explanation of symbols]

[0079] 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 Li; a chlorination heating step of heating the recovery target together with a nonmetallic chlorine compound to generate LiCl; A method for producing a battery material comprising the steps of:

2. 2. The method for producing a battery material according to claim 1, wherein the nonmetallic chlorine compound contains at least one selected from the group consisting of hydrogen chloride, ammonium chloride, ammonium perchlorate, perchloric acid, chloric acid, hypochlorous acid, chloromethane, dichloromethane, trichloromethane, and tetrachloroethylene.

3. The method for producing a battery material according to claim 1 , wherein the chlorination heating step heats the recovery target at 500° C. to 1000° C.

4. The method for producing a battery material according to claim 1 , wherein the chlorination heating step heats the recovery target in an inert atmosphere.

5. 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 lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel manganese composite oxide, lithium manganese cobalt composite oxide, lithium nickel cobalt composite oxide, lithium nickel manganese cobalt composite oxide, lithium iron phosphate, lithium manganese phosphate, and lithium manganese iron phosphate.

6. The method for producing a battery material according to any one of claims 1 to 5, further comprising a water dissolving step of immersing the recovery target after the chlorination heating step in water to obtain a Li solution in which the LiCl is dissolved in the water.

7. The method for producing a battery material according to claim 6 , further comprising a Li precipitation step of precipitating crystals of a Li compound from the Li solution.

8. The object to be recovered contains at least one of Ni and Co, and the solid matter obtained after the water dissolution step is immersed in an aqueous ammonia solution to obtain a metal solution containing at least one of the Ni and Co. ３ The method for producing the battery material according to claim 6, further comprising a leaching step.

9. The method for producing a battery material according to claim 3 , wherein the chlorination heating step heats the recovery target at 900° C. or higher.

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