Manufacturing method of battery material

Abstract

To collect Li with low energy from a collection target such as a used lithium ion secondary battery.SOLUTION: A manufacturing method includes: a preparation step of preparing a collection target containing lithium and a first metal element; a chloride heating step of heating the collection target together with a metal chloride and generating LiCl; and a water dissolution step of immersing the collection target after the chloride heating step in water and obtaining an Li solution in which LiCl is dissolved in the water. In the manufacturing method, a heating temperature in the chloride heating step is 1000°C or lower and the metal chloride contains a second metal element which is easier to be chlorinated than the first metal element in the collection target and harder to be chlorinated than the lithium in the chloride heating step. Thus, Li can be easily collected from the collection target with low energy of 1000°C or lower.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, in consideration of the impact on the environment, recovery technologies have been developed to recover valuable metals from used batteries and process scraps and reuse them as battery materials. An example of this recovery technology is disclosed in Patent Document 1. In the recovery technology described in Patent Document 1, lithium-containing materials such as lithium batteries are melted in a metal molten bath furnace. At this time, in the technology described in Patent Document 1, alkali metal chlorides and alkaline earth metal chlorides are added to the molten bath furnace. This generates fumed LiCl (fine particles after evaporation). It is said that this makes it possible to recover lithium from lithium-containing materials. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-507413 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the recovery technology described in Patent Document 1, the recovery target (lithium battery, etc.) and metal chloride (metal chloride) are melted and evaporated to produce LiCl fume. For this reason, the temperature of the heat treatment needs to be set at a high temperature of 1500°C or higher. In other words, since the technology described in Patent Document 1 uses a large amount of energy to recover Li, it is difficult to say that sufficient consideration is given to the impact on the environment. [Means for solving the problem]

[0006] 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.

[0007] The method for producing a battery material disclosed herein includes a preparation step of preparing a recovery target containing lithium and a first metal element, a chlorination heating step of heating the recovery target together with a metal chloride to produce LiCl, and a water dissolution step of immersing the recovery target after the chlorination heating step in water to obtain a Li solution in which LiCl is dissolved in water. In the production method disclosed herein, the heating temperature in the chlorination heating step is 1000° C. or less, and the metal chloride includes a second metal element that is more easily chlorinated than the first metal element in the recovery target and less easily chlorinated than lithium in the chlorination heating step.

[0008] In the manufacturing method having the above configuration, a chlorination heating step is carried out in which the object to be recovered is heated together with a metal chloride. The metal chloride used in the technology disclosed herein contains a second metal element that is more easily chlorinated than a first metal element (metal element other than Li) in the object to be recovered, and is less easily chlorinated than Li. When the metal chloride containing such a second metal element is heated, Li can be selectively chlorinated without chlorinating the other metal elements (first metal element) in the object to be recovered. This makes it possible to efficiently produce lithium chloride (LiCl) even by heating at a low temperature of 1000°C or less. Since this LiCl is easily dissolved in water, it can be easily separated from the object to be recovered by carrying out a water dissolution step. In other words, according to the manufacturing method disclosed herein, Li can be easily recovered with low energy. [Brief description of the drawings]

[0009] [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 data showing an example of thermodynamic equilibrium in the chlorination heating process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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.

[0011] 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.

[0012] As shown in FIG. 1, the lithium ion secondary battery 1 includes a case 10, an electrode assembly 20, and an electrolyte (not shown).

[0013] (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.

[0014] (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).

[0015] 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).

[0016] 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 X) and the like. Examples of binders include resin materials such as styrene butadiene rubber (SBR). Examples of thickeners include resin materials such as carboxymethyl cellulose (CMC).

[0017] 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.

[0018] (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.

[0019] 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. As described above, this collection target (lithium ion secondary battery 1) contains various metal elements other than lithium (Li). Here, in this specification, the metal elements other than Li in the collection target are referred to as "first metal elements." For example, when the lithium ion secondary battery 1 is the collection target, the first metal elements include Ni, Co, Mn, Al, Cu, Fe, and the like. According to the technology disclosed herein, Li can be suitably collected from the collection target containing such various metal elements.

[0020] The object of collection in the manufacturing method disclosed herein is not limited to the lithium ion secondary battery 1 having the above-mentioned configuration. For example, at the manufacturing site of lithium ion secondary batteries, 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 a target of collection in the manufacturing method disclosed herein. In addition, at the manufacturing site of lithium ion secondary batteries, some defect may occur in the electrode body after manufacture, making it unusable for products. Such an electrode body may also be a target of collection since it contains Li. In other words, the object of collection in 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 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 water dissolving step S20, a Li crystallization step S30, a sorting step S40, an acid leaching step S50, a neutralization precipitation step S60, a solvent extraction step S70, an NCM 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 S12 and a chlorination heating step S14. This can significantly improve the Li recovery efficiency. This will be described in detail below.

[0025] (a) Preparation process S12 In this step, a recovery target containing lithium and a first metal element 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 (such as electrode bodies). Details of the recovery target have already been described, so duplicated 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 S14 In the chlorination heating step S14, the target to be recovered is heated together with the metal chloride. In this chlorination heating step S14, the Li in the target to be recovered is chlorinated by the chlorine element (Cl) separated from the metal chloride. This produces lithium chloride (LiCl) in the target to be recovered. This LiCl is easily dissolved in water and can be easily separated from the target to be recovered.

[0027] The "metal chloride" in the technology disclosed herein includes a second metal element that is more easily chlorinated than the first metal element in the recovery target and less easily chlorinated than Li in the chlorination heating step S14. By heating a metal chloride containing such a second metal element, Li can be selectively chlorinated without chlorinating the first metal element in the recovery target. This allows lithium chloride (LiCl) to be efficiently produced.

[0028] The second metal element in the metal chloride is preferably selected from various metal elements, taking into consideration the thermodynamic equilibrium state of each component in the target to be recovered, as shown in FIG. 6. Specifically, FIG. 6 shows data showing the thermodynamic equilibrium state when a target to be recovered containing Li, Ni, Co, Mn, Al, and Cu is heated at 927°C (1200K). The horizontal axis in FIG. 6 represents the chlorine partial pressure (log 10 P Cl2 ·atm. The vertical axis indicates the oxygen partial pressure (log 10 P O2 The thermodynamic equilibrium state shown in Figure 6 can be calculated and created using the thermodynamic data of each element and compound.

[0029] Specifically, the second metal element in the metal chloride is connected to a line that indicates the equilibrium between Li oxide and chloride (Li2O / LiCl equilibrium), a line that indicates the equilibrium between Li metal and chloride (Li / LiCl equilibrium), and a line that indicates the equilibrium between the first metal element and chloride (M / MCl 2x The equilibrium between the metal oxide and the metal chloride of the first metal element (MO x / MCl 2x It is preferable to select a metal element P that can set PO2 and PCl2 in the shaded area in FIG. 6, surrounded by the line indicating equilibrium. Then, by controlling the oxygen partial pressure in the chlorination heating step S14 as necessary, Li can be selectively chlorinated without chlorinating the first metal element in the recovery target. Examples of such second metal elements include alkaline earth metals (Ca, Mg, Ba, Sr, Ra, Be, etc.) and alkali metals (Na, K, Rb, Cs, Fr). By using the chlorides of these second metal elements as chlorine supply sources, LiCl can be more suitably produced. However, the second metal element in the technology disclosed herein is not limited to the above-mentioned elements, and is appropriately selected based on the thermodynamic equilibrium state of each component in the recovery target. As an example, as shown in FIG. 6, when the recovery target contains Li, Ni, Co, Mn, Cu, and Al, it is preferable to select an alkaline earth metal (particularly Ca or Mg) as the second metal element.

[0030] The ratio of the amount of Cl in the metal chloride to the amount of Li in the object to be recovered (Cl / Li) is preferably 1 or more. This allows Li in the object to be suitably salified. From the viewpoint of more efficiently generating LiCl, the Cl / Li ratio is preferably 2 or more, more preferably 4 or more, even more preferably 6 or more, and particularly preferably 8 or more. On the other hand, the upper limit of Cl / Li is not particularly limited, and may be 20 or less, 18 or less, 16 or less, 14 or less, or 12 or less.

[0031] The heating temperature in this step is set to 1000°C or less. According to the technology disclosed herein, LiCl can be efficiently generated even at a low heating temperature, so Li can be recovered with less energy than before. The upper limit of the heating temperature is preferably 975°C or less, more preferably 950°C or less. As the heating temperature is lowered, the energy required for Li recovery can be further reduced. On the other hand, the lower limit of the heating temperature is preferably 800°C or more, more preferably 850°C or more, even more preferably 900°C or more, and particularly preferably 925°C or more. As the heating temperature is increased, the efficiency of LiCl generation tends to improve.

[0032] The pressure in the chlorination heating step S14 is not particularly limited and can be set appropriately. As will be described in detail later, the present inventors have set the pressure at atmospheric pressure (approximately 1.0×10 5 It has been confirmed that LiCl is suitably produced even when the chlorination heating step S14 is carried out at a pressure of 1.0×10 Pa. On the other hand, the production efficiency of LiCl tends to improve as the pressure in the chlorination heating step S14 is lowered. Specifically, the pressure in the chlorination heating step S14 is 1.0×10 3 Pa or less is preferable, 7.5×10 2 Pa or less is more preferable, and 5.0×10 2 Pa or less is more preferable, and 2.5×10 2 On the other hand, the lower limit of the pressure in the chlorination heating step S14 is not particularly limited, and is preferably 1.0×10 0 Pa or more is acceptable, 5.0×10 0 Pa or more is acceptable, 1.0×101 Pa or more is acceptable, 5.0×10 1 Pa or more is also acceptable.

[0033] In addition, in this process, the object to be recovered may be heated under an inert atmosphere in order to control the oxygen partial pressure. A specific example of the heating gas used in this process is an inert gas such as argon gas. In this specification, the term "inert atmosphere" refers to a heating atmosphere containing the above-mentioned inert gas as a main component. In other words, the term "inert atmosphere" in this specification is not limited to a completely inert atmosphere in which the inert gas content is 100% (the oxygen element content 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).

[0034] In addition, in this process, it is preferable to store the object to be recovered and the metal chloride in different containers and heat them. In this case, if the container for the object to be recovered and the container for the metal chloride are connected in a manner that allows air to pass through, Li in the object to be recovered can be chlorinated. With this configuration, the contamination of the object to be recovered with the second metal element of the metal chloride can be kept to a minimum, and therefore a decrease in the recovery efficiency of valuable metals due to contamination by impurities can be prevented.

[0035] (2) Water dissolution process S20 Next, in the water dissolution step S20, the recovery target after the chlorination heating step S14 is immersed in water. As described above, the recovery target after the chlorination heating step S14 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 can be obtained. In this way, in the manufacturing method according to the present embodiment, Li can be directly separated from the recovery target immediately after the chlorination heating step S14. As a result, a Li solution containing Li with high purity can be obtained.

[0036] 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.

[0037] (3) Li crystallization process S30 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. 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.

[0038] As described above, in the production method according to this embodiment, Li can be directly recovered from the metal solution (Li solution) generated after the roasting step S10. That is, in the production 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.

[0039] (4) Sorting process S40 On the other hand, the first metal element (Ni, Co, Mn, Al, Cu, Fe, etc.) that was not converted to a chloride in the chlorination heating step S14 remains in the solid content (recovery target) after the water dissolving step S20. In contrast, in the manufacturing method according to this embodiment, valuable metals (Ni, Co, Mn) are recovered from the recovery target after the water dissolving step S20. Specifically, in this embodiment, the roasting step S10 is performed and then the sorting step S40 is performed. In this step, each member contained in the recovery target after roasting 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, in addition to the positive electrode core 32, the negative electrode plate 40 is also removed from the recovery target. Furthermore, when the lithium ion secondary battery 1 is the recovery target, in addition to the positive electrode core 32 and the negative electrode plate 40, the case 10 is also removed from the recovery target. 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, Mn). 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.

[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 S40 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 (neutralization precipitation 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.

[0042] (5) Acid leaching process S50 In the acid leaching step S50, the solid content after the water dissolving step S20 is immersed in an acid solution. This makes it possible to obtain a metal solution in which the first metal element in the object to be recovered is dissolved in the acid solution. 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 makes it possible to preferably dissolve the metal components in the object to be recovered. 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 makes it possible to efficiently remove undissolved components (such as carbon components). It is preferable to set the temperature of the acid solution to 50°C or higher (more preferably 55°C or higher, particularly preferably 60°C or higher). This makes it possible to shorten the acid leaching step S30. Moreover, the upper limit of the temperature of the acid solution is not particularly limited, and may be 90° C. or less, 85° C. or less, or 80° C. or less.

[0043] (6) Neutralization and precipitation process S60 In this step, a neutralizing agent is added to the metal solution obtained in the acid leaching step S50. 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 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. 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.

[0044] (7) Solvent extraction process S70 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 S70 in this embodiment includes a Mn extraction step S71, a Co extraction step S72, and a Ni extraction step S73, as shown in FIG. 5. The steps will be described in detail below.

[0045] (a) Mn extraction step S71 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 extract liquid, and the first extract liquid from which Mn has been removed.

[0046] 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).

[0047] (b) Co extraction step S72 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 (metal solution 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.

[0048] (c) Ni extraction process S73 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.

[0049] (8) NCM crystallization process S80 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 S71 to S73, 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.

[0050] (9) Active material generation step S90 In this process, the metal compound obtained in the NCM crystallization process S80 and the Li compound obtained in the Li crystallization process S30 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.

[0051] 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 S14 is performed in which the recovery target is heated together with the metal chloride. The metal chloride used in the chlorination heating step S14 is a chloride of a second metal element that is more easily chlorinated than the first metal element in the recovery target and less easily chlorinated than Li. This allows Li to be selectively chlorinated without chlorinating the first metal element in the recovery target. As a result, lithium chloride (LiCl) can be efficiently produced even by heating at a low temperature of 1000°C or less. In the manufacturing method according to the present embodiment, the water dissolving step S20 is performed in which LiCl in the recovery target is dissolved in water. This allows Li to be recovered from the recovery target with low energy.

[0052] 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.

[0053] In the manufacturing method according to the embodiment described above, in addition to the roasting step S10 and the water dissolving step S20, a sorting step S40 and a Li crystallization step S30 to an active material production step S90 are performed. However, the description of the embodiment described above is not intended to limit the steps other than the roasting step S10 and the water dissolving step S20. In other words, in the manufacturing method disclosed herein, steps other than the roasting step S10 and the water dissolving step S20 can be appropriately added, deleted, or changed as necessary.

[0054] (1) Changes in the solvent extraction process For example, 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 Mn extraction step S71, a Co extraction step S72, and a Ni extraction step S73. This allows the Co solution, the Ni solution, and the Mn solution to be extracted separately. However, in the solvent extraction step S70, 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.

[0055] (2)Addition of Li separation process Also, a Li separation step may be performed on the Li solution before performing the Li crystallization step S30. 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.

[0056] (3)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 S30. 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, 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.

[0057] (4) Changes in the NCM crystallization process In the above embodiment, the NCM crystallization step S80 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 from each of the Co solution, the Ni solution, and the Mn solution individually. When stripping 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. The NCM hydroxide synthesized from the crystals of these sulfates is mixed with a Li compound and fired to produce a battery material (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. Sample Preparation In this test, six types of recovery processes with different roasting process conditions were carried out. Below, the six types of test samples (Examples 1 to 6) obtained from each recovery process are explained.

[0060] (1) Example 1 In Example 1, a mixture of a positive electrode plate and a negative electrode plate 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 used was lithium nickel cobalt manganese composite oxide (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2) was used. Meanwhile, for the negative electrode plate, a negative electrode core (Cu foil) with a layer of negative electrode active material applied to its surface was used. Graphite was used as the negative electrode active material. These positive and negative electrodes were then cut into sheets measuring 1 cm x 3 cm and prepared as the objects to be collected.

[0061] Next, in this test, a roasting process was carried out in which the recovery target was heated together with a metal chloride (CaCl2). Specifically, in the roasting process of this test, a double-structured glass tube was prepared. Next, the recovery target was placed in the inner glass tube, and the metal chloride was placed in the outer glass tube. In this test, the amount of metal chloride was adjusted so that the ratio (Cl / Li) of the amount of Cl in the metal chloride to the amount of Li in the recovery target was 10 times. Next, a decompression process was carried out so that the pressure inside the glass tube was 2.0×102 Pa. Then, the glass tube was placed in an electric furnace and the inside of the furnace was heated to 927°C. The heating rate at this time was set to 10°C / min. Then, roasting was carried out for 1 hour while maintaining the temperature inside the furnace at 927°C. Then, the temperature inside the furnace was cooled to 50°C, and the recovery target was recovered. In this test, the recovery target after heating was used as a test sample (Example 1).

[0062] (2) Example 2 In Example 2, the roasting process was carried out under the same conditions as in Example 1, except that the type of metal chloride was changed to NaCl2.

[0063] (3) Example 3 In Example 3, the roasting process was carried out under the same conditions as in Example 1, except that the metal chloride was changed to MgCl2.

[0064] (4) Example 4 In Example 4, the roasting step was carried out under the same conditions as in Example 1, except that no metal chloride was used.

[0065] (5) Example 5 In Example 5, the roasting step was carried out under the same conditions as in Example 1, except that the heating temperature was reduced to 727°C.

[0066] (6) Example 6 In Example 6, the roasting step was carried out under the same conditions as in Example 1, except that heating was carried out without reducing the pressure inside the glass tube (at atmospheric pressure).

[0067] 2.Evaluation Test In this test, the test samples of Examples 1 to 6 were immersed in water for 30 minutes to obtain Li solutions, and the Li solutions were then filtered to remove solids. Then, ICP was performed on the filtered Li solutions to measure the amount of Li in the Li solutions. The recovery rate of each element was calculated based on the following formula. The measurement results are shown in Table 1. In the formula, the "amount of metal element before roasting" is the amount of metal element obtained by analyzing the reference sample before roasting with ICP. Recovery rate = (amount of metal element in Li solution / amount of metal element before roasting) x 100

[0068] [Table 1]

[0069] As a result of the above-mentioned tests, a high Li recovery rate of 70% or more was confirmed in Examples 1, 3, 5, and 6. This shows that if an appropriate metal chloride is selected in the roasting process, Li can be suitably recovered even when a low-temperature heat treatment of 927°C or less is performed.

[0070] 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.

[0071] <Item 1> A preparation step of preparing a recovery target containing lithium and a first metal element; a chlorination heating step of heating the recovery target together with a metal chloride to produce LiCl; a water dissolving step in which the recovery target after the chlorination heating step is immersed in water to obtain a Li solution in which the LiCl is dissolved in the water; Including, The heating temperature in the chlorination heating step is 1000° C. or less, The metal chloride comprises a second metal element which is more easily chlorinated than a first metal element in the recovery target and less easily chlorinated than the lithium in the chlorination heating step.

[0072] <Item 2> 2. The method for producing a battery material according to item 1, wherein the first metal element includes at least one selected from the group consisting of Ni, Co, Mn, Al, Cu, and Fe.

[0073] <Item 3> 3. The method for producing a battery material according to item 1 or 2, wherein the second metal element includes at least one selected from the group consisting of Ca, Mg, Ba, Sr, Ra, and Be.

[0074] <Item 4> 4. The method for producing a battery material according to any one of items 1 to 3, wherein the heating temperature is 800° C. or higher.

[0075] <Item 5> 5. The method for producing a battery material according to any one of items 1 to 4, wherein the chlorination heating step is carried out in a reduced pressure environment of 500 Pa or less.

[0076] <Item 6> 6. The method for producing a battery material according to any one of items 1 to 5, further comprising a Li precipitation step of precipitating crystals of a Li compound from the Li solution.

[0077] <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 solid material obtained after the water dissolution step in an acid solution to obtain a metal solution in which the first metal element is dissolved in the acid solution. [Explanation of symbols]

[0078] 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 lithium and a first metal element; a chlorination heating step of heating the recovery target together with a metal chloride to generate LiCl; 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; Including, The heating temperature in the chlorination heating step is 1000° C. or less, The metal chloride includes a second metal element that is more easily chlorinated than a first metal element in the recovery target and is less easily chlorinated than the lithium in the chlorination heating step.

2. The method for producing a battery material according to claim 1 , wherein the first metal element includes at least one selected from the group consisting of Ni, Co, Mn, Al, Cu, and Fe.

3. The method for producing a battery material according to claim 2 , wherein the second metal element includes at least one selected from the group consisting of Ca, Mg, Ba, Sr, Ra, and Be.

4. The method for producing a battery material according to claim 1 , wherein the heating temperature is 800° C. or higher.

5. The chlorination heating step is 5.0×10 ２ The method for producing a battery material according to claim 1 , wherein the method is carried out in a reduced pressure environment of 0.1 Pa or less.

6. The method for producing a battery material according to claim 1 , further comprising a Li precipitation step of precipitating crystals of a Li compound from the Li solution.

7. The method for producing a battery material according to claim 1 , further comprising an acid leaching step of immersing the solid material obtained after the water dissolution step in an acid solution to obtain a metal solution in which the first metal element is dissolved in the acid solution.

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