Manufacturing method of battery material

Abstract

Provided is a method for producing a high-efficiency battery material having a high leaching rate of a noble metal. The production method disclosed herein includes: a preparation step of preparing at least one of Ni and Co as a target for recovery of a noble metal; a heating step in which the object to be recovered is heated at 500 DEG C or higher such that at least a portion of the noble metal is reduced to a metal elementary substance; and an ammonia leaching step in which the recovery target after the heating step is immersed in an aqueous ammonia solution in which ammonia, a pH buffer, and an oxidizing agent are mixed to obtain a metal solution containing a noble metal.

Description

Technical Field

[0001] The technology disclosed herein relates to methods for making battery materials. Background Art

[0002] Lithium-ion secondary batteries are widely used in various fields. Lithium-ion secondary batteries use various materials including precious metals such as Ni and Co. For example, the positive electrode plate of a lithium-ion secondary battery includes a positive electrode active material and a positive electrode core. The positive electrode active material uses 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. The positive electrode core generally uses aluminum and the like.

[0003] In recent years, the development of recycling technology for recycling precious metals as battery materials from used batteries, processing waste, etc. has been continuously promoted. For example, as an example of recycling technology for positive plates, Japanese Patent Application Publication No. 2022-118594 and Non-Patent Document 1 (Waste Management Volume 60, February 2017 Pages 680-688) can be cited.

[0004] Japanese Patent Application Publication No. 2022-118594 discloses a method for recovering precious metals, comprising the following steps: a heating step, in which a battery slag (recovery object) having a positive electrode active material containing Ni and / or Co and a negative electrode active material containing graphite is heated, thereby oxidizing the graphite contained in the negative electrode active material in the battery slag to generate carbon dioxide gas; an acid leaching step, in which Ni and / or Co are leached in sulfuric acid to generate a leachate; and a recovery step, in which Ni and / or Co are recovered. Japanese Patent Application Publication No. 2022-118594 discloses that the precious metals (Ni ions and Co ions) in the recovery object are reduced to divalent oxides.

[0005] Non-Patent Document 1 discloses a technique of preparing positive electrode waste by crushing positive electrode plates, etc., and subjecting the positive electrode waste to ammonia leaching. In the ammonia leaching, ammonia-ammonium sulfate is used as a leaching solution, and sodium sulfite is used as a reducing agent. Summary of the invention

[0006] As mentioned above, in conventional methods for recovering precious metals, the precious metals are heated and acid-leached in an acid solution such as sulfuric acid. However, in the case of implementing an acid leaching process, as disclosed in Japanese Patent Application Publication No. 2022-118594, the precious metals are recovered in the form of sulfates through a neutralization process and a solvent leaching process, and the recovered precious metal sulfates are used to manufacture battery materials such as positive electrode active materials. In such a recovery method, there are many processes and it is often very complicated.

[0007] An alkaline solution (particularly aqueous ammonia) is used when manufacturing the positive electrode active material. The present inventors have conducted research and found that by implementing ammonia leaching when recovering precious metals (e.g., Ni and / or Co), the positive electrode active material can be manufactured without implementing the existing neutralization process and solvent leaching process. On the other hand, in the ammonia leaching method disclosed in non-patent document 1, the dissolution rate of Co is slow, and it takes more than 240 minutes to obtain a leaching rate of more than 80%, which is not ideal from the perspective of manufacturing efficiency.

[0008] The present invention has been made in view of the above circumstances, and provides a method for producing a battery material with a high efficiency and a high leaching rate of precious metals.

[0009] In order to solve the above-mentioned problems, a method for producing a battery material having the following structure (hereinafter, also simply referred to as a “production method”) is provided.

[0010] The manufacturing method of the battery material disclosed in this article includes the following steps: a preparation step, preparing a recovery object containing at least one of Ni and Co as a precious metal; a heating step, heating the recovery object at a temperature above 500°C in a manner that at least a portion of the precious metal is reduced to a state of a metal element; and an ammonia immersion step, immersing the recovery object after the heating step in an ammonia aqueous solution prepared by mixing ammonia, a pH buffer and an oxidant to obtain a metal solution containing the precious metal.

[0011] In the manufacturing method of the above structure, by heating in a manner that at least a portion of the precious metal is reduced to a state of a metal element, a short time and high leaching rate can be achieved in the ammonia leaching process. In addition, in the manufacturing method of the above structure, since the acid leaching process is not performed, the neutralization process and the like can be omitted. Therefore, according to the above structure, a manufacturing method of a battery material with a high leaching rate of precious metals and high efficiency can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a longitudinal cross-sectional view schematically showing the internal structure of a lithium-ion secondary battery.

[0013] Figure 2 It is schematically indicated Figure 1 A perspective view of an electrode body of a lithium-ion secondary battery shown.

[0014] Figure 3 This is a flowchart illustrating a method for producing a battery material according to one embodiment.

[0015] Figure 4 This is a flowchart illustrating in detail a heating step in a production method according to one embodiment.

[0016] Figure 5This is a flowchart illustrating in detail an ammonia leaching step in a production method according to one embodiment.

[0017] Figure 6 This is a graph showing the results of XRD analysis in Example 5.

[0018] Explanation of symbols

[0019] 1Lithium-ion secondary battery

[0020] 10 Shell

[0021] 12 Positive terminal

[0022] 14 Negative terminal

[0023] 20 electrode body

[0024] 30 positive plate

[0025] 32 positive electrode core

[0026] 34 Positive electrode active material layer

[0027] 40 negative plate

[0028] 42 negative electrode core

[0029] 44 Negative electrode active material layer

[0030] 50 Isolators DETAILED DESCRIPTION

[0031] Hereinafter, the embodiments of the technology disclosed herein will be described with reference to the accompanying drawings. It should be noted that matters other than those specifically mentioned in this specification and matters required for the implementation of the technology disclosed herein can be grasped as design matters for those skilled in the art based on the prior art in this field. The technology disclosed herein can be implemented based on the contents disclosed in this specification and the technical common sense in this field.

[0032] 1. Recycling objects

[0033] The manufacturing method of the battery material involved in this embodiment is to manufacture the battery material (typically the material of the positive electrode active material of the lithium ion secondary battery, the precursor of the positive electrode active material, and the positive electrode active material) by recovering precious metals such as Ni and Co from the specified recycling object. As an example of the recycling object here, a used lithium ion secondary battery can be cited. The lithium ion secondary battery is described in detail below. Figure 1 It is a longitudinal cross-sectional view schematically showing the internal structure of a lithium-ion secondary battery. Figure 2 It is schematically indicated Figure 1 A perspective view of an electrode body of a lithium-ion secondary battery shown.

[0034] like Figure 1As shown, the lithium ion secondary battery 1 includes a case 10 , an electrode body 20 , and an electrolyte (not shown).

[0035] (1) Housing

[0036] The housing 10 is a box-shaped container. The electrode body 20 and the electrolyte are contained in the housing 10. The housing 10 is made of a metal material (aluminum (Al) or the like) having a certain strength. In addition, a positive terminal 12 and a negative terminal 14 are installed in the housing 10. The positive terminal 12 and the negative terminal 14 are connected to the electrode body 20 in the housing 10. Specifically, the positive terminal 12 is connected to the positive electrode plate 30 (see Figure 2 ) is connected. The positive terminal 12 is made of aluminum (Al) or the like. On the other hand, the negative terminal 14 is connected to the negative electrode plate 40 (see Figure 2 The negative electrode terminal 14 is made of copper (Cu) or the like.

[0037] (2) Electrode body

[0038] The electrode body 20 is a power generation element of the lithium ion secondary battery 1. Figure 2 As shown, the electrode body 20 includes a positive electrode plate 30, a negative electrode plate 40 and a separator 50. Figure 2 The electrode body 20 shown here is a wound electrode body. The wound electrode body is made 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. The structure of the electrode body 20 is not particularly limited, and can be other structures that have been known to the public (laminated electrode body, etc.).

[0039] The positive electrode plate 30 includes: a positive electrode core 32 as a conductive metal foil, and a positive electrode active material layer 34 provided on the surface of the positive electrode core 32. The positive electrode core 32 uses aluminum (Al) or the like. In addition, the positive electrode active material layer 34 is a mixture layer containing a positive electrode active material, a conductive material, a binder, etc. The positive electrode active material is a lithium transition metal composite oxide containing at least one of nickel (Ni) and cobalt (Co). As an example of the lithium transition metal composite oxide, 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, etc. can be cited. According to the manufacturing method involved in this embodiment, Ni and / or Co can be efficiently recovered from the recycling object containing such a lithium transition metal composite oxide. In addition, as a conductive material, carbon materials such as acetylene black and graphite can be cited. In addition, as a binder, resin materials such as polyvinylidene fluoride (PVdF) can be cited.

[0040] The negative electrode plate 40 includes: a negative electrode core 42 which is a conductive metal foil, and a negative electrode active material layer 44 provided on the surface of the negative electrode core 42. Copper (Cu) or the like is used for the negative electrode core 42. In addition, the negative electrode active material layer 44 is a mixed layer containing a negative electrode active material, a binder, a thickener, and the like. As an example of the negative electrode active material, carbon materials such as graphite, hard carbon, and soft carbon can be cited. In addition, as other examples of the negative electrode active material, lithium titanate (LTO), silicon carbide, a composite containing carbon and silicon, silicon oxide (SiO X ) etc. The details are described below. According to the manufacturing method involved in this embodiment, even if a battery using such a non-carbon-based negative electrode active material is used as a recycling object, the recovery efficiency of precious metals can be appropriately improved. In addition, as a binder, a resin material such as styrene-butadiene rubber (SBR) can be cited. As a thickener, a resin material such as carboxymethyl cellulose (CMC) can be cited.

[0041] In addition, the separator 50 is an insulating sheet sandwiched between the positive electrode plate 30 and the negative electrode plate 40. The separator 50 uses, for example, a resin material such as polyethylene (PE), polypropylene (PP), polyester, cellulose, polyamide, etc. In addition, a heat-resistant layer containing an inorganic filler can be formed on the surface of the separator 50. Examples of the inorganic filler 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.

[0042] (3) Electrolytes

[0043] The electrolyte is present between the positive electrode plate 30 and the negative electrode plate 40. Thus, the charge carrier (Li ion) can be moved between the positive electrode plate 30 and the negative electrode plate 40. As an example of the electrolyte, a non-aqueous electrolyte, a gel electrolyte, etc. can be cited. It should be noted that the electrolyte can be used without particular limitation for an electrolyte that can be used in a lithium ion secondary battery, and the technology disclosed herein is not limited.

[0044] As an example of a recycling object in the manufacturing method involved in the present embodiment, a lithium-ion secondary battery 1 is described above. However, the manufacturing method disclosed herein is not limited to a method in which the lithium-ion secondary battery 1 of the above-mentioned structure is used as a recycling object. For example, at the manufacturing site of a lithium-ion secondary battery, a part of the positive plate is sometimes cut off when the electrode body is made. Since the part of the cut positive plate (processing waste) also contains Ni and Co, it can become a recycling object of the manufacturing method disclosed herein. In addition, at the manufacturing site of a lithium-ion secondary battery, sometimes the electrode body after manufacture has some defects and cannot be used in the product. Since such an electrode body also contains Ni and Co, it can also become a recycling object. That is, the recycling object of the manufacturing method disclosed herein only needs to contain at least one of Ni and Co, and is not particularly limited to a specific structure.

[0045] 2. Manufacturing methods of battery materials

[0046] Hereinafter, a method for producing the battery material according to the present embodiment will be described. Figure 3 It is a flowchart explaining the manufacturing method involved in this embodiment. Figure 4 It is detailed description Figure 3 Flow chart of the heating process in .

[0047] like Figure 3 As shown, the manufacturing method of the battery material involved in this embodiment includes: a preparation step S10, a heating step S20 and an ammonia immersion step S30. The manufacturing method of the battery material disclosed herein may further include a precursor preparation step S40 and an active material generation step S50. Each step is described below.

[0048] (1) Preparation step S10

[0049] In the preparation step S10, a recycling object including at least one of Ni and Co as a precious metal is prepared. As described above, the "recycling object" in the technology disclosed herein only needs to include at least one of Ni and Co as a precious metal. That is, the recycling object is not limited to the finished lithium-ion secondary battery, but also includes processing waste, defective parts (electrode bodies, etc.). It should be noted that the details of the recycling object have been described, so repeated descriptions are omitted.

[0050] (2) Heating step S20

[0051] In the heating step S20, the prepared recovery object is heated at 500°C or above. In the recovery object prepared in the preparation step S10, the precious metals (Ni, Co) exist in the state of divalent or trivalent metal ions. In the heating step S20, by heating at least 500°C or above, at least a part of these precious metals can be appropriately reduced to the state of metal elements (metal Ni, metal Co). Thereby, the recovery efficiency of the precious metals (Ni and / or Co) in the ammonia leaching step S30 described later can be improved.

[0052] In the heating step S20, when the recovery object includes Ni, it is preferred to heat at 500°C or more in such a manner that at least a portion of the Ni is reduced to a state of metallic Ni. In addition, in the heating step S20, when the recovery object includes Co, it is preferred to heat at 500°C or more in such a manner that at least a portion of the Co is reduced to a state of metallic Co. In addition, in the heating step S20, when the recovery object includes both Ni and Co, it is preferred to heat at 500°C or more in such a manner that at least a portion of these Ni and Co are reduced to a state of metallic Ni and metallic Co. It should be noted that in the manufacturing method disclosed herein, in the recovery object after calcination, as long as a portion of the precious metal is reduced to a state of a metal element, a portion thereof may also exist in a state of an oxide.

[0053] In the heating step S20, by heating the recycling object prepared as above, the liquid components (electrolyte, etc.) in the recycling object can be removed and the resin components (binder, separator, etc.) can be carbonized. In addition, when the charged lithium-ion secondary battery 1 is used as the recycling object, the function as a battery can be stopped by performing the heating step S20. Thus, the next step can be safely performed. Although not particularly limited, as Figure 4 As shown, the heating step S20 may include a measuring step S21, a determining step S22, a reducing component adding step S23, a calcining step S24, and a screening step S25. These steps will be described in detail below.

[0054] (a) Measurement step S21

[0055] In the measuring step S21, the amount of oxygen element (O) and the reducing component contained in the recycling object is measured. In the measuring step S21, a part of the recycling object can be taken as a sample for measurement, and the oxygen element and the reducing component of the sample for measurement can be measured. In addition, the measuring step S21 can be implemented only when the type of recycling object is changed, and it is not necessary to implement it for all the prepared recycling objects. Thus, the manufacturing efficiency can be improved.

[0056] It should be noted that the "reducing component" in this specification is not particularly limited as long as it is a component that can reduce Ni and Co in the calcination step S24 described later. In the manufacturing method disclosed herein, carbon element (C) can be preferably used as a reducing component. From the perspective of being less prone to oxidation and more stable until the start of the calcination step S14, it is particularly preferred to use carbon as a reducing component. In addition, depending on the type of recycling object, various carbon materials (conductive materials, binders, negative electrode active materials, etc.) are sometimes included. By using these carbon materials as a supply source of reducing components, it can help reduce the cost required for the recovery of precious metals.

[0057] The method for measuring the amount of the reducing component (carbon element) in the recovery object is not particularly limited, and the known measurement method can be used without particular limitation. For example, as a method for measuring the amount of carbon element, thermogravimetric differential thermal analysis (TG-DTA), SEM-EDS analysis, combustion oxidation-non-dispersive infrared absorption method, combustion volume method, etc. can be cited.

[0058] Next, a method for determining the amount of oxygen element in the recycling object is described. First, when the chemical composition of the positive electrode active material in the recycling object is known in advance, the amount of metal element in the recycling object can be determined, and the amount of oxygen element can be calculated based on the amount of metal element. In this way, the amount of oxygen element in a precious metal oxide (for example, a lithium transition metal composite oxide) can be easily determined. A specific example of this measurement step is as follows. First, a solution in which a part of the recycling object (the sample for measurement) is dissolved in an acid is prepared. Next, the solution is subjected to inductively coupled plasma mass spectrometry (ICP: Inductively Coupled Plasma). In this way, the total amount M of transition metal elements (Ni, Co, Mn) in the recycling object can be determined. Then, after the chemical composition of the positive electrode active material in the recycling object (LiNi x Co y Mn z O δ ), the ratio (x+y+z:δ) of the total amount of transition metal elements (x+y+z) to the amount of O (δ) can be determined. In this case, the amount of oxygen element N can be calculated from the ICP measurement result (the total amount of metal elements M) based on the following formula (1).

[0059] N = δ·M / (x+y+z) (1)

[0060] It should be noted that the method for determining the amount of oxygen in the recovered object is not limited to the above method, and a known determination method can be used without particular limitation. For example, SEM-EDS analysis, XRF analysis, etc. can be used to directly determine the oxygen in the recovered object. By using these methods, the amount of oxygen can be determined even when the chemical composition of the positive electrode active material in the recovered object is unknown.

[0061] (b) Determination step S22

[0062] In the determination step S22, it is determined whether the amount ratio of the reducing component to the oxygen element is above a predetermined threshold value. Here, the "threshold value" in this step is set based on the stoichiometric ratio of the oxide of the reducing component. For example, when carbon element (C) is used as the reducing component, the above-mentioned "oxide of the reducing component" is carbon dioxide (CO2). At this time, in the calcination step S24 described later, when at least a portion of the precious metals (Ni, Co) are to be appropriately reduced to a state of a metal element (metal Ni, metal Co), it is preferred to set the above-mentioned threshold value to a value above the ratio (1 / 2) of the carbon element to the oxygen element in CO2. In the determination step S22, it is determined whether the amount ratio (hereinafter also referred to as "C / O ratio") of the carbon element (reducing component) to the oxygen element in the recovery object is above 1 / 2. When the above-mentioned C / O ratio is above 1 / 2 ( Figure 4 On the other hand, when the C / O ratio is less than 1 / 2 ( Figure 4 If the step S22 is not performed, it is preferred to proceed to the reducing component adding step S23. Thus, the precious metal can be more appropriately reduced to a state of a metal single substance.

[0063] It should be noted that, as described above, the threshold value in the determination step S22 can be set to a value greater than the stoichiometric ratio of the oxide of the reducing component. For example, when the reducing component is carbon, the threshold value can be set to 3 / 4 or more (more preferably 1 or more, further preferably 5 / 4 or more, and particularly preferably 3 / 2 or more). Thus, only the recovery object containing a large amount of reducing components (carbon elements) can be supplied to the calcining step S24. Therefore, in the calcining step S24, the reduction of the noble metal oxide can be further promoted, and most of the noble metal can be made into a single metal.

[0064] (c) Reducing Component Adding Step S23

[0065] The reducing component adding step S23 is preferably performed when the determination result of the determination step S22 is less than the threshold value ( Figure 4In the case of S22 (No). In the reducing component adding step S23, a reducing component is added to the recycling object. For example, for the recycling object determined as having a C / O ratio less than 1 / 2 in the determination step S22, it is preferred to add a reducing component (carbon-containing material) in such a way that the C / O ratio becomes above a threshold value (above 1 / 2). Thereby, the precious metal can be more appropriately reduced to a state of a metal element. It should be noted that as the carbon-containing material here, carbon materials such as graphite, hard carbon, and soft carbon can be cited. In addition, the carbon-containing material can be a resin material such as polyolefins and polyesters. Since these resin materials produce carbon elements during the initial carbonization of the calcination step S24, they can be used as a supply source of carbon elements.

[0066] It should be noted that in the reducing component adding step S23, a reducing component in an amount far exceeding the above threshold value can be added. For example, when the reducing component is carbon, the carbon-containing material can be added in such a manner that the C / O ratio in the recovery object becomes 3 / 4 or more (more preferably 1 or more, further preferably 5 / 4 or more, and particularly preferably 3 / 2 or more). In this way, the recovery object containing a large amount of reducing components (carbon elements) can be supplied to the calcining step S24, so the reduction of the precious metal oxide in the calcining step S24 can be further promoted.

[0067] (d) Calcination step S24

[0068] In the calcination step S24, the recovery object is calcined (heated) at a temperature of 500°C or above. Thus, at least a portion of the precious metal (Ni and / or Co) can be reduced to a state of a metal element, and the recovery rate of the precious metal can be appropriately improved. For example, in the calcination step S24, when the recovery object is calcined at a temperature of 500°C or above, a reaction as shown in the following formula (2) occurs. Thus, at least a portion of the precious metal (e.g., Ni, Co) in the recovery object can be reduced to a state of a metal element (metal Ni, metal Co).

[0069] LiNi x Co y Mn z O δ +C 1 / 2δ =Li+xNi+yCo+zMn+1 / 2δ·CO2 (2)

[0070] The heating temperature in the calcination step S24 (more specifically, the temperature in the heating furnace) only needs to be above 500°C. As the heating temperature rises, there is a tendency to easily generate a metal single substance of the precious metal. As described above, in the manufacturing method disclosed herein, as long as at least a portion of the precious metal is reduced to a state of a metal single substance. In order to make the precious metal dissolve more efficiently in the ammonia leaching step S30 described later, it is preferred that most of the precious metal is reduced to a state of a metal single substance. From this point of view, the heating temperature is preferably above 650°C, may be above 700°C, or may be above 750°C. On the other hand, from the point of view of the reduction of the precious metal, the upper limit of the heating temperature is not particularly limited, and may be below 1500°C, may be below 1400°C, or may be below 1300°C. It should be noted that, from the perspective of reducing the cost required for the calcination step S24, the upper limit of the heating temperature is preferably below 1200°C, more preferably below 1100°C, and particularly preferably below 1000°C. The calcination time in the calcination step S24 varies depending on the amount of the recovery target, etc., and therefore cannot be determined in general. The calcination time in the calcination step S24 is, for example, preferably 1 to 12 hours, and more preferably 2 to 8 hours.

[0071] Although not particularly limited, it is preferred that the calcination step S24 heats the recovery object under an inert atmosphere. In this way, it is possible to prevent the supply of oxygen to the recovery object being heated, and it is possible to more appropriately reduce at least a portion of the noble metal oxide (lithium transition metal composite oxide, etc.) to a state of a metal single substance. Specifically, the calcination step S24 preferably heats the recovery object under the circulation of an inert gas such as argon or nitrogen. It should be noted that the "inert atmosphere" in this specification refers to a heating atmosphere containing the above-mentioned inert gas as the main component. That is, it is not limited to a completely inert atmosphere with an inert gas content of 100% (oxygen content of 0%), but also includes a heating atmosphere with an oxygen content of less than 5% (preferably less than 3%, more preferably less than 1%, further preferably less than 0.5%, and particularly preferably less than 0.1%).

[0072] Although not particularly limited, it is preferred that in the calcination step S24, calcination is performed in a manner in which the metal single substance of the noble metal is more advantageous than the oxide of the noble metal in the noble metal. The state of the noble metal can be confirmed, for example, by X-ray diffraction (XRD) analysis. Therefore, in the XRD analysis of the noble metal, when the ratio of the peak of the metal single substance from the noble metal to the peak of the oxide of the noble metal is greater than 1, it can be said that the metal single substance of the noble metal is more advantageous than the oxide of the noble metal in the noble metal. Specifically, for example, in the case of Ni, in the X-ray diffraction using a Mo ray source, the peak of Ni oxide (NiO) is confirmed to be around 19°, and the peak of metal Ni is confirmed to be around 20°. If the ratio of the peak of metal Ni to the peak of Ni oxide (metal Ni / Ni oxide) is greater than 1, it is a state in which metal Ni is more advantageous than Ni oxide.

[0073] (e) Screening step S25

[0074] In the screening step S25, the various components included in the recycling object after calcination (heating) are screened with a sieve. For example, when the processing waste of the positive electrode plate 30 is the recycling object, the positive electrode core 32 can be screened from the processing waste with a sieve and removed from the recycling object. In addition, when the electrode body 20 is the recycling object, in addition to the positive electrode core 32, the negative electrode plate 40 can also be removed from the recycling object. In addition, when the lithium-ion secondary battery 1 is the recycling object, in addition to the above-mentioned positive electrode core 32 and negative electrode plate 40, the shell 10 can also be removed from the recycling object. This reduces the content of other metal components (Al, Cu, etc.) in the recycling object, so it can help improve the recovery efficiency of precious metals (Co, Ni).

[0075] It should be noted that in the screening step S25, the recycling object may be crushed as needed. This can improve the efficiency of screening each component. For example, when the lithium-ion secondary battery 1 is the recycling object, the shell 10 and the electrode body 20 can be crushed. This makes it easy to remove the shell 10, the positive electrode core 32 and the negative electrode plate 40 from the recycling object.

[0076] In addition, the screening step S25 is not a step for intentionally completely removing other metal components such as Al from the recycling object. The details are described below, but when other metal components remain in the recycling object, the precious metals (Ni and / or Co) can be fully separated from other metal components in the next step (ammonia leaching step S30). That is, this step can also be appropriately omitted as needed. For example, when the recycling object has a low content of other metal components (processing waste of the positive plate 30, etc.), even if this step is omitted, the precious metals can be efficiently recovered.

[0077] (3) Ammonia leaching step S30

[0078] In the ammonia leaching step S30, the recovery object after the heating step S20 is immersed in an ammonia solution. Thus, a metal solution in which the precious metals (Ni and / or Co) in the recovery object are dissolved in the ammonia solution is obtained. In the manufacturing method disclosed herein, as the ammonia solution, a substance mixed with ammonia, a pH buffer and an oxidant is used. In addition to the above-mentioned precious metal components, the recovery object after the heating step S20 may also include Li from the positive electrode active material, Al from the positive electrode core 32 or the shell 10, etc. For example, since Al is not easily soluble in an ammonia solution, it remains as a solid component. In addition, in the manufacturing method disclosed herein, the heating step S20 is implemented in a manner that at least a portion of the precious metal becomes a metal single substance. Thus, in the ammonia leaching step S30, a high leaching rate can be achieved in a shorter time than before. That is, by implementing the ammonia leaching step S30 on the precious metal that at least a portion of which becomes a metal single substance in the heating step S20, the precious metal (Ni and / or Co) as the recovery object can be easily separated from other metal components (such as Al, etc.). Although not particularly limited, Figure 5 As shown, the ammonia immersion step S30 may include a preparation step S31 and an immersion step S32. Specific descriptions are given below.

[0079] (a) Preparation Step S31

[0080] In the preparation step S31, ammonia, a pH buffer and an oxidant are mixed to prepare an ammonia solution. The pH of the ammonia solution is preferably 8.0 to 11.0, and more preferably 9.0 to 10.0. In addition, the concentration of ammonia in the ammonia solution is preferably 5 wt% to 35 wt%, and more preferably 15 wt% to 30 wt%. Thus, the precious metal can be appropriately dissolved.

[0081] A pH buffer refers to a compound having the function of maintaining the pH of a solution at a specified value even when added to the extent that an acid or base is present. In other words, a pH buffer can, for example, control the pH of an aqueous ammonia solution to below 11. By making the aqueous ammonia solution contain a pH buffer, the pH of the aqueous ammonia solution can be made not to exceed 11 and become the range of ammonia concentration as described above. Thus, the precious metal can be properly dissolved. The pH buffer is not particularly limited as long as it can exert the buffering property of pH in an aqueous ammonia solution. For example, as a pH buffer, ammonium salts, amino acids, organic acid salts, borates, amine compounds, etc. can be cited. The pH buffer can be used alone or in combination of two or more. Among them, as a pH buffer, an ammonium salt is preferred. As specific examples of ammonium salts, ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium nitrate, etc. can be cited. The pH buffer is more preferably ammonium sulfate or ammonium chloride.

[0082] Although not particularly limited, the concentration of the pH buffer in the aqueous ammonia solution is preferably 0.5 mol / L or more, and may be 1 mol / L or more, or 2 mol / L or more. Thus, it is possible to exert excellent pH buffering properties. The upper limit of the concentration of the pH buffer is not particularly limited, and may be, for example, 5 mol / L or less, or 4.5 mol / L or less. Thus, for example, the consumption of reagents in the precursor production step S40 described later can be reduced.

[0083] The oxidant is a compound that oxidizes other substances. In the manufacturing method disclosed herein, in the heating step S20, at least a portion of the noble metal is reduced to a state of a metal single substance. Specifically, Co and Ni are present in the recovery object after calcination in a state of less than 2 valences, more preferably in a state of metal Co and metal Ni. In order to dissolve the Co and / or Ni in an aqueous ammonia solution in a state of metal ions, it is necessary to increase the valence. Therefore, in the manufacturing method disclosed herein, the aqueous ammonia solution contains an oxidant. The oxidant is not particularly limited as long as it can oxidize the noble metal. For example, as an oxidant, peroxide, permanganic acid or its salt, nitric acid or its salt, etc. can be cited. The oxidant can be used alone or in combination of two or more. Among them, as an oxidant, hydrogen peroxide, potassium permanganate, nitric acid, potassium nitrate, sodium peroxide, and manganese oxide can be preferably used.

[0084] Although not particularly limited, the concentration of the oxidant in the aqueous ammonia solution is preferably 0.1 mol / L or more, more preferably 0.5 mol / L or more. Thus, the excellent noble metal can be properly oxidized. The upper limit of the concentration of the oxidant is not particularly limited, for example, it can be 3 mol / L or less, or it can be 2 mol / L or less.

[0085] (b) Immersing step S32

[0086] In the impregnation step S32, the recovery object after the heating step S20 is immersed in the above-mentioned prepared ammonia solution. As described above, by making at least a portion of the precious metal a metal element, the solubility in the ammonia solution can be improved. Therefore, in the manufacturing method disclosed herein, a high leaching rate can be achieved even for a shorter time than before. In addition, since Al and the like contained in the recovery object are not easily soluble in the ammonia solution, only the target precious metals (here Ni and Co) can be selectively dissolved in the ammonia solution.

[0087] The impregnation time in the impregnation process S32 is preferably more than 10 minutes, more preferably more than 30 minutes, further preferably more than 60 minutes, and particularly preferably more than 110 minutes. Thus, the Ni and / or Co in the recovery object can be fully dissolved in the ammonia solution. In the manufacturing method disclosed herein, if the impregnation time exceeds 120 minutes, almost all of the Ni and / or Co in the recovery object can be dissolved in the ammonia solution. Therefore, from the perspective of manufacturing efficiency, the upper limit of the impregnation time is preferably less than 180 minutes, more preferably less than 150 minutes.

[0088] The temperature of the ammonia solution in the immersion step S32 is not particularly limited. For example, the temperature of the ammonia solution is preferably 50°C or more (more preferably 55°C or more, particularly preferably 60°C or more). This can shorten the ammonia immersion step S30. In addition, the upper limit of the temperature of the ammonia solution is not particularly limited, and may be 90°C or less, 85°C or less, or 80°C or less. Although not particularly limited, it is preferred that the immersion step S32 be performed under stirring.

[0089] As described above, in the manufacturing method disclosed herein, by making at least a portion of the precious metal a metal element in the heating step S20, it can be appropriately dissolved in an ammonia solution. In the existing method, Co and Ni are recovered in the form of sulfates via an acid leaching step, a neutralization step, a cleaning step, and a solvent extraction step after the heating step. On the other hand, according to the manufacturing method disclosed herein, only the ammonia leaching step S30 is implemented after the heating step S20, so that Co, Ni and other metal components can be separated. In the manufacturing method disclosed herein, since the acid leaching step is not implemented, there is no need to implement the neutralization step. In addition, since the separated Ni and Co are present in the ammonia solution, the solution can be directly used to implement the step of making the positive active material precursor described later (precursor preparation step S40). That is, according to the manufacturing method disclosed herein, a high leaching rate of precious metals can be achieved, and the number of steps from the completion of the heating step S20 to the precursor preparation step S40 can be greatly reduced.

[0090] (4) Precursor production step S40

[0091] In the precursor preparation step S40, the metal solution obtained in the ammonia leaching step S30 is used to precipitate the positive electrode active material precursor (metal composite hydroxide). Generally speaking, in the process of preparing the precursor of the positive electrode active material, an alkaline solution (especially ammonia water) is added to the dissolved solution of the metal sulfate, and the pH is controlled while stirring, so that the particles of the metal composite hydroxide are coprecipitated and crystallized in the reaction tank. The metal solution after the ammonia leaching step S30 contains Ni and / or Co in the form of an ammonia complex in the ammonia solution. Therefore, the metal solution obtained in the ammonia leaching step S30 can be directly used in the precursor preparation step S40. By adjusting the pH of the metal solution while stirring, the positive electrode active material precursor (metal composite hydroxide) can be crystallized.

[0092] In the precursor preparation step S40, the pH of the metal solution can be controlled to be about 9 to 13. In the precursor preparation step S40, in order to control the pH, the metal solution can be stirred while adding an alkaline solution (such as sodium hydroxide, sodium carbonate) as needed. It should be noted that the amount of Ni and Co in the metal solution obtained in the ammonia leaching step S30 can be obtained by ICP analysis. Therefore, Ni, Co or other metal components such as Mn can be added according to the composition of the target positive electrode active material. The metal component can be added in the form of metal sulfates, hydrates, etc.

[0093] (5) Active Material Generation Step S50

[0094] In the active material generation step S50, the positive electrode active material precursor (metal composite hydroxide) obtained in the precursor preparation step S40 and the Li compound (e.g., lithium carbonate) are used to generate a battery material (positive electrode active material). For example, the positive electrode active material precursor prepared above is mixed with the Li compound, and the mixture is calcined. In this way, the positive electrode active material (lithium transition metal composite oxide) of the lithium ion secondary battery can be manufactured.

[0095] The above is a description of the manufacturing method of the battery material involved in the present embodiment. As described above, in the manufacturing method involved in the present embodiment, the heating step S20 is implemented in such a way that a part of the precious metals contained in the recovery object is a metal single substance by heating the recovery object at above 500°C. As a result, the precious metals (Ni and / or Co) are appropriately dissolved in the ammonia solution in the ammonia leaching step S30. Therefore, even if the leaching process is short, the recovery rate of the precious metals can be improved. In addition, in the manufacturing method disclosed herein, since the acid leaching process is not implemented like the existing method, the precursor of the positive electrode active material can be prepared without implementing the neutralization process and the solvent extraction process. According to this manufacturing method, the recovery rate of the precious metals can be improved, and the manufacturing process can be greatly shortened.

[0096] 3. Other Implementation Methods

[0097] An embodiment of the technology disclosed herein has been described above. It should be noted that the technology disclosed herein is not limited to the above-described embodiment, and also includes other embodiments in which various configurations are changed. Other examples of the embodiments of the technology disclosed herein will be described below.

[0098] In the manufacturing method involved in the above-mentioned embodiment, the recovery of Ni and / or Co as precious metals is described. However, in the manufacturing method disclosed herein, in addition to the above-mentioned nickel (Ni) and cobalt (Co), lithium (Li) can also be recovered (manufactured) as needed. That is, the description related to the above-mentioned embodiment does not limit each process. In the manufacturing method disclosed herein, each process can be appropriately added, deleted, or changed as needed.

[0099] As an example of a method for recovering Li, the following method can be cited. First, when implementing the heating step S20, a chlorination roasting step of adding a non-metallic chlorine compound (HCl, etc.) to the recovery object for roasting is implemented. Thus, the Li in the recovery object reacts with the non-metallic chlorine compound to generate LiCl. Next, a water immersion step of immersing the roasted recovery object in water is implemented. Since the above-mentioned LiCl is a water-soluble compound, Li can be recovered only by contacting the recovery object with water.

[0100] In addition, the detailed conditions in the heating process S20 can also be appropriately changed. For example, in the manufacturing method involved in the above-mentioned embodiment, carbon element is used as a reducing component. However, as mentioned above, the reducing component is not particularly limited as long as it is a component that can reduce Ni and Co in the calcination process S24. As reducing components other than carbon element (C), lithium (Li), cesium (Cs), potassium (K), barium (Ba), strontium (Sr), calcium (Ca), sodium (Na), magnesium (Mg), aluminum (Al), titanium (Ti), zirconium (Zr), manganese (Mn) and other metal-based reducing components can be cited. These metal-based reducing components are preferably present in the recovery object in the form of sulfites or the like. For example, if calcium sulfite (CaSO3) is used as a reducing component, then in the heating process S20, at least a portion of the precious metal is reduced to a metal element and calcium oxide (CaO) is generated at the same time. In this case, the threshold value in the determination process S22 is set to a value above the stoichiometric ratio (1 / 1) of CaO. Thus, the precious metals in the recovery object can be appropriately reduced to the state of a metal single substance. It should be noted that in the determination step S21, as a method for determining the reducing components of the metal system, ICP, SEM-EDS analysis, XRF analysis, etc. can be cited. In addition, the reducing component used as the determination object in the determination step S22 and the reducing component added in the reducing component adding step S23 can be the same or different. For example, when it is determined that the carbon element (C) is insufficient in the determination step S22, calcium sulfite (CaSO3) can be added in the reducing component adding step S23. Even in this case, the precious metal can be appropriately reduced to the state of a metal single substance in the calcination step S24.

[0101] [Test example]

[0102] Hereinafter, test examples related to the technology disclosed herein will be described. It should be noted that the contents of the test examples described below are not intended to limit the technology disclosed herein.

[0103] 1. Sample Preparation

[0104] (Example 1) In this experiment, the positive electrode plate was used as the recycling object, and the test sample was prepared according to the following steps. First, the positive electrode plate to be recycled was prepared. As the positive electrode plate, a material with a positive electrode active material layer coated on the surface of the positive electrode core (Al foil) was used. It should be noted that the positive electrode active material in this experiment was prepared as lithium nickel cobalt manganese composite oxide (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2). Then, the positive electrode plate was crushed and passed through a sieve with an aperture of 500 μm to prepare a powder.

[0105] Next, a portion of the powder prepared above was taken and dissolved in sulfuric acid. Then, ICP was performed on the solution to measure the total mass M of Ni, Co and Mn. 1 / 3 Co 1 / 3 Mn 1 / 3 O2), and the amount of twice the total amount M is taken as the amount N of oxygen element (N=2M). In addition, in this experiment, thermogravimetric differential thermal analysis (TG-DTA) is performed on a part of the powder prepared above. In this thermogravimetric differential thermal analysis, the powder is heated in an atmosphere of 800°C. It should be noted that in this analysis, the heating rate from room temperature (20°C) to 800°C is set to 5°C / min. The carbon content in the powder prepared above is thereby determined. Then, mixed graphite is added to the powder in such a manner that the measured amount ratio (C / O ratio) of oxygen element to carbon element becomes greater than the stoichiometric ratio (1 / 2) of CO2, and the test sample of Example 1 is prepared.

[0106] Next, the test sample was heated in an inert atmosphere. Specifically, in Example 1, the test sample was placed in an electric furnace, and the temperature in the furnace was raised to 150°C while supplying Ar gas. It should be noted that the heating rate at this time was set to 5°C / min. Then, heating was performed for 5 hours while maintaining the temperature in the furnace at 150°C. Thereafter, the sample of Example 1 was recovered after the temperature in the furnace was cooled to 50°C.

[0107] Then, the recovered sample was subjected to ammonia leaching. Specifically, first, 28 wt% ammonia (NH3), 2 mol / L ammonium sulfate ((NH4)2SO4) as a pH buffer, and 0.5 mol / L hydrogen peroxide (H2O2) as an oxidant were mixed to prepare an ammonia solution. Next, the heated sample was added to the ammonia solution. The ammonia solution was stirred at a stirring speed of 500 rpm for 2 hours while the temperature of the ammonia solution was maintained at 80°C.

[0108] (Examples 2 to 7) In Examples 2 to 7, the furnace temperature was changed as shown in Table 1. Except for this, the same procedure as in Example 1 was followed to obtain samples of Examples 2 to 7. Then, the samples of Examples 2 to 7 were leached with ammonia.

[0109] (Examples 8 and 9) In Examples 8 and 9, the furnace temperature was changed as shown in Table 1. Except for this, the same procedure as in Example 1 was followed to obtain samples of Examples 8 and 9. Then, the samples of Examples 8 and 9 were subjected to ammonia leaching with the concentration of the pH buffer changed as shown in Table 1.

[0110] (Example 10) In Example 10, no mixed graphite was added. In addition, the temperature in the furnace was changed as shown in Table 1. Except for this, the same procedure as in Example 1 was followed to obtain a sample of Example 10. Then, the sample of Example 10 was impregnated with ammonia.

[0111] 2. Evaluation test

[0112] (1) XRD analysis

[0113] The heated test samples of each example were subjected to X-ray diffraction (XRD) analysis using a Mo ray source to evaluate the state of the Ni element in the test samples. The results are shown in Table 1. In addition, the XRD chart of Example 5 is shown in Figure 6 . It should be explained, such as Figure 6 As shown, when no peak from the positive electrode active material is confirmed near 8° and peaks are confirmed near 19° and 20°, respectively, it is evaluated that at least a portion of the Ni element after calcination becomes a metal single substance ("oxide + metal single substance" in Table 1). In addition, when no peak from the positive electrode active material is confirmed near 8° and only a peak is confirmed near 20°, it is evaluated that most of the Ni element after calcination becomes a metal single substance ("metal single substance" in Table 1). In addition, when a peak from the positive electrode active material is confirmed near 8° or a peak is confirmed only near 19°, it is evaluated that all the Ni elements exist in the state of oxides ("oxides" in Table 1).

[0114] In addition, the state of the Co element in the test sample was also subjected to XRD analysis in the same procedure as the above-mentioned evaluation of the state of Ni. The results are shown in Table 1.

[0115] In addition, in this test, in Examples 3 to 10 where no peak from the positive electrode active material was confirmed near 8°, the peak intensity ratio of the metal Ni peak to the Ni oxide peak (metal Ni / Ni oxide) was calculated. The results are shown in Table 1. It should be noted that when the peak intensity ratio (metal Ni / Ni oxide) is less than 1, it is evaluated that a sample dominated by Ni oxide is generated, and when the peak intensity ratio is greater than 1, it is evaluated that a sample dominated by metal Ni is generated.

[0116] (2) Leaching rate in ammonia leaching

[0117] ICP analysis was performed on the test samples of each example after ammonia leaching, and the leaching rates of Ni and Co in each example were calculated. Specifically, first, the metal solution in which the samples of each example were dissolved was filtered. Next, ICP was performed on the filtrate to measure the respective amounts of Ni and Co contained in the filtrate. Then, based on the following formula (3), the leaching rates of each metal element were calculated. It should be noted that the "amount of substance before ammonia leaching" in formula (3) is a value estimated by measuring the amount of substance per 1g through ICP analysis and multiplying it by the weight of the sample added to ammonia.

[0118] Leaching rate = (amount of substance in filtrate / amount of substance before ammonia leaching) × 100 (3)

[0119] [Table 1]

[0120]

[0121] As shown in Table 1, in Examples 3 to 10 where the calcination temperature is 500°C or higher, at least a portion of Ni is converted into a metal element, and at least a portion of Co is converted into a metal element. In addition, it is known that by ammonia leaching, a leaching rate of Ni of 71% or higher and a leaching rate of Co of 67% or higher are achieved. That is, by heating the recovery object at 500°C or higher in such a manner that at least a portion of the precious metal is reduced to a state of a metal element, and immersing the heated recovery object in an ammonia solution mixed with ammonia, a pH buffer and an oxidant, a method for manufacturing a battery material with a high leaching rate of precious metals and high efficiency can be achieved.

[0122] The above is a detailed description of the technology disclosed in this article, but these are only examples and do not limit the scope of the patent claims. The technology described in the scope of the patent claims includes various deformations and changes of the specific examples illustrated above. That is, the technology disclosed in this article includes the following items 1 to 8.

[0123] <Item 1> A method for manufacturing a battery material, comprising the following steps: a preparation step of preparing a recovery object containing at least one of Ni and Co as a precious metal; a heating step of heating the recovery object at a temperature above 500°C in such a manner that at least a portion of the precious metal is reduced to a state of a single metal; and an ammonia immersion step of immersing the recovery object after the heating step in an ammonia solution prepared by mixing ammonia, a pH buffer and an oxidant to obtain a metal solution containing the precious metal.

[0124] <Item 2> The method for producing a battery material according to Item 1, wherein the concentration of the pH buffer is 0.5 mol / L or more.

[0125] <Item 3> A method for manufacturing a battery material according to Item 1 or Item 2, wherein the heating step includes: a reducing component adding step, in which the reducing component is added in such a manner that the amount of the reducing component relative to the amount of the oxygen element contained in the recycling object becomes above a threshold value of the stoichiometric ratio based on the oxide of the reducing component.

[0126] <Item 4> The method for producing a battery material according to Item 3, wherein the reducing component is carbon, and the threshold value is a value greater than or equal to the stoichiometric ratio of CO 2 .

[0127] <Item 5> The method for producing a battery material according to any one of Items 1 to 4, wherein the heating step is performed by heating the recycling object at 650°C to 1000°C.

[0128] <Item 6> The method for producing a battery material according to any one of Items 1 to 5, wherein the heating step is performed in such a way that the ratio of a peak derived from a metal single substance of the precious metal to a peak derived from an oxide of the precious metal becomes 1 or more in an XRD analysis of the precious metal.

[0129] <Item 7> The method for producing a battery material according to any one of Items 1 to 6, further comprising: a step of preparing a positive electrode active material precursor using the metal solution in the ammonia leaching step.

[0130] <Item 8> A method for manufacturing a battery material according to any one of Items 1 to 7, wherein the recycling object comprises at least one selected from lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel manganese composite oxide, lithium manganese cobalt composite oxide, lithium nickel cobalt composite oxide, and lithium nickel manganese cobalt composite oxide.

Claims

1. A method for manufacturing a battery material, comprising the following steps: A preparation step of preparing a recovery target including at least one of Ni and Co as a precious metal; A heating step of heating the recovery object at a temperature of 500° C. or higher so that at least a portion of the precious metal is reduced to a state of a single metal; as well as In the ammonia immersion step, the object to be recovered after the heating step is immersed in an ammonia aqueous solution obtained by mixing ammonia, a pH buffer and an oxidant to obtain a metal solution containing the precious metal.

2. The method for producing a battery material according to claim 1, wherein: The concentration of the pH buffer is above 0.5 mol / L.

3. The method for producing a battery material according to claim 1, wherein: The heating process comprises: The reducing component adding step adds the reducing component so that the amount of the reducing component relative to the amount of the oxygen element contained in the recovery object becomes equal to or greater than a threshold value of a stoichiometric ratio based on an oxide of the reducing component.

4. The method for producing a battery material according to claim 3, wherein: The reducing component is carbon element, and the threshold value is a value greater than the stoichiometric ratio of CO 2 .

5. The method for producing a battery material according to claim 1, wherein: The heating step is to heat the recycling object at 650°C to 1000°C.

6. The method for producing a battery material according to claim 1, wherein: The heating step is to perform calcination so that the ratio of a peak derived from a metal single substance of the precious metal to a peak derived from an oxide of the precious metal in an XRD analysis of the precious metal becomes 1 or more.

7. The method for producing a battery material according to claim 1, wherein: The method further comprises the following step: using the metal solution in the ammonia leaching step to prepare a positive electrode active material precursor.

8. The method for producing a battery material according to claim 1, wherein: The recycling object includes at least one selected from lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel manganese composite oxide, lithium manganese cobalt composite oxide, lithium nickel cobalt composite oxide, and lithium nickel manganese cobalt composite oxide.

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