Manufacturing method of battery material

Abstract

The invention relates to a method for manufacturing an electrode material. The purpose of the present invention is to improve the Li recovery rate when reproducing a battery material from a lithium ion secondary battery. The manufacturing method disclosed herein includes: a preparation step for preparing a lithium ion secondary battery charged to a predetermined reference SOC or more; a filling step in which the interior of the lithium ion secondary battery is filled with an aqueous medium; and a collection step in which the aqueous medium is collected from the inside of the lithium ion secondary battery. As a result, it is possible to prepare a Li solution in which Li in the negative electrode active material is eluted from the aqueous medium. Then, by collecting the Li solution, a large amount of Li can be easily recovered.

Description

Technical Field

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

[0002] Lithium-ion secondary batteries have been widely used in various fields. The lithium-ion secondary battery (hereinafter also referred to as "battery") contains various metal materials (Li, Ni, Co, Mn, Al, Cu, etc.). For example, lithium transition metal composite oxides such as lithium nickel cobalt manganese composite oxide are used in the positive electrode active material. Aluminum and the like are used in the positive electrode core. On the other hand, carbon materials and the like are used in the negative electrode active material. Copper and the like are used in the negative electrode core. In addition, aluminum and the like are also used in the battery case.

[0003] In recent years, the development of recycling technology (manufacturing method of battery materials) for recovering valuable metals (Li, Ni, Co, Mn, etc.) from used batteries and reproducing them as battery materials has been carried out. For example, in this recycling technology, the used batteries are first roasted. Then, the electrode body (black lumps) after roasting are taken out from the inside of the battery. Then, an acid leaching treatment is carried out in which the black lumps are immersed in an acid solution. Thus, an acid leaching solution in which metal components (Li, Ni, Co, Mn, Al, Cu, etc.) are dissolved in an acid solution can be prepared. Then, various separation treatments (neutralization precipitation, solvent extraction, etc.) are carried out for the acid leaching solution. Thus, the desired valuable metals are recovered and can be reproduced as battery materials.

[0004] An example of such a recycling technology is disclosed in Patent Documents 1 and 2. As described in these documents, in the prior art, it is recommended to discharge the battery before implementing the recycling process of the valuable metal. For example, Patent Document 1 shows the following view: when the lithium-ion secondary battery is discharged, Li is retained in the positive electrode active material, so the recovery rate of Li is improved.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2022-49831

[0008] Patent Document 2: Japanese Patent Application Publication No. 2021-72157 Summary of the invention

[0009] Problems to be solved by the invention

[0010] Due to the increased awareness of environmental issues in recent years, it is necessary to further improve the Li recovery rate from used lithium ion secondary batteries. In order to meet this requirement, the inventors have repeatedly studied and surprisingly found that the discharge treatment recommended in the prior art is the main reason for the reduction of Li recovery rate. Specifically, as described in patent document 1, when the lithium ion secondary battery is discharged, Li is retained in the positive electrode active material. However, in general lithium ion secondary batteries, Al is used in the positive electrode core as a component adjacent to the positive electrode active material. That is, Li and Al exist in large quantities on the positive electrode side of the battery after discharge. If roasting is performed in this state, an alloy of Li and Al (Li-Al alloy) is generated. This Li-Al alloy is difficult to dissolve in acid solution, so it is difficult to recover in acid seepage treatment. In this case, since Li is retained on the solid component (residue) side, it becomes the main reason for the reduction of Li recovery rate.

[0011] The technology disclosed herein has been accomplished to solve the above-mentioned problems, and its purpose is to improve the Li recovery rate when reproducing battery materials from lithium-ion secondary batteries.

[0012] Means for solving problems

[0013] 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.

[0014] The manufacturing method of the battery material disclosed herein includes: a preparation step, in which a lithium-ion secondary battery charged to a predetermined reference SOC or above is prepared; a filling step, in which an aqueous medium is filled inside the lithium-ion secondary battery; and a collection step, in which the aqueous medium is collected from the inside of the lithium-ion secondary battery.

[0015] In the manufacturing method of the above structure, the battery charged to a certain level or above is taken as the object of recycling. In contrast to the above-mentioned discharged battery, for the charged battery, Li is retained in the negative electrode active material. Moreover, in the manufacturing method disclosed herein, an aqueous medium is filled inside the charged battery. As a result, the Li in the negative electrode active material is dissolved in the aqueous medium. Then, by collecting the aqueous medium in which the Li is dissolved, a large amount of Li can be easily recovered. In addition, in the manufacturing method disclosed herein, Li can be recovered before the roasting treatment is implemented, so the reduction in the Li recovery rate caused by alloying can also be suppressed. As described above, according to the manufacturing method disclosed herein, a high Li recovery rate can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a longitudinal cross-sectional view schematically showing the internal structure of a lithium-ion secondary battery.

[0017] Figure 2To illustrate Figure 1 A perspective view of an electrode body of a lithium-ion secondary battery shown.

[0018] Figure 3 This is a flowchart for explaining a method for producing a battery material according to one embodiment.

[0019] Figure 4 This is a flowchart for describing in detail a preparation step in a manufacturing method according to one embodiment.

[0020] Figure 5 The present invention is a flowchart for explaining in detail the separation step in the production method according to one embodiment.

[0021] Description of Reference Numerals

[0022] 1Lithium-ion secondary battery

[0023] 10 Shell

[0024] 12 Positive terminal

[0025] 14 Negative terminal

[0026] 20 electrode body

[0027] 30 positive plate

[0028] 32 positive electrode core

[0029] 34 Positive electrode active material layer

[0030] 40 negative plate

[0031] 42 negative electrode core

[0032] 44 Negative electrode active material layer

[0033] 50 separators DETAILED DESCRIPTION

[0034] The following is a description of the implementation methods of the technology disclosed herein. It should be noted that matters other than those specifically mentioned in this specification, i.e., matters required for the implementation of the technology disclosed herein, can be understood as design matters for those 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.

[0035] 1. Lithium-ion secondary battery

[0036] The manufacturing method according to the present embodiment recycles valuable metals such as lithium (Li) from lithium ion secondary batteries to reproduce battery materials (typically, materials for positive electrode active materials of lithium ion secondary batteries). An example of a battery to be recycled is described below. Figure 1It is a longitudinal cross-sectional view schematically showing the internal structure of a lithium-ion secondary battery. Figure 2 To illustrate Figure 1 A three-dimensional diagram of an electrode body of a lithium-ion secondary battery is shown. Figure 1 As shown, the lithium ion secondary battery 1 includes an outer casing 10 , an electrode body 20 , and an electrolyte (not shown).

[0037] (1) Outer packaging

[0038] The outer packaging body is not particularly limited as long as it is a container that accommodates the electrode body and the electrolyte. Figure 1 The outer package 10 shown is a box-shaped shell. For the box-shaped outer package 10, for example, a metal material (aluminum (Al) etc.) having a certain strength is used. Figure 1 As shown, a positive terminal 12 and a negative terminal 14 are installed in the outer package 10. The positive terminal 12 and the negative terminal 14 are connected to the electrode body 20 inside the outer package 10. Specifically, the positive terminal 12 is connected to the positive electrode plate 30 (refer to Figure 2 ) is connected. Aluminum (Al) or the like is used for the positive electrode terminal 12. On the other hand, the negative electrode terminal 14 is connected to the negative electrode plate 40 of the electrode body 20. Copper (Cu) or the like is used for the negative electrode terminal 14.

[0039] Furthermore, in Figure 1 The outer package 10 shown is formed with a liquid injection hole 16. The liquid injection hole 16 is an opening that connects the inside and outside of the outer package 10. In the manufacture of the lithium ion secondary battery 1, the electrolyte is filled into the outer package 10 through the liquid injection hole 16. Then, the liquid injection hole 16 is sealed with a sealing plug 17 after the electrolyte is filled.

[0040] (2) Electrode body

[0041] 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 is a wound electrode body. The wound electrode body is formed by winding a long strip-shaped stacked body in which a positive electrode plate 30, a negative electrode plate 40 and a separator 50 are stacked. The structure of the electrode body 20 is not limited to a wound electrode body, and may be other conventionally known structures (stacked electrode body, etc.).

[0042] The positive electrode plate 30 includes: a foil-shaped positive electrode core 32, and a positive electrode active material layer 34 provided on the surface of the positive electrode core 32. For the positive electrode core 32, aluminum (Al) or the like is used. In addition, the positive electrode active material layer 34 is a composite material layer containing a positive electrode active material, a conductive material, a binder, etc. The positive electrode active material is a metal material containing at least lithium (Li). As an example of the positive electrode active material, 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 cobalt manganese composite oxide can be listed. In addition, as other examples of positive electrode active materials, lithium transition metal phosphate compounds such as lithium iron phosphate, lithium manganese phosphate, and lithium manganese iron phosphate can be listed. In addition, as will be described in detail later, the manufacturing method disclosed herein can also contribute to the improvement of the recovery rate of valuable metals other than Li (Ni, Co, Mn, etc.). Therefore, the recycling object (battery) preferably contains a lithium transition metal composite oxide containing Ni, Co, Mn, etc. In addition, as the conductive material, carbon materials such as acetylene black and graphite can be listed. As the binder, resin materials such as polyvinylidene fluoride (PVdF) can be listed.

[0043] On the other hand, the negative electrode plate 40 includes a foil-shaped negative electrode core 42, and a negative electrode active material layer 44 applied to the surface of the negative electrode core 42. For the negative electrode core 42, copper (Cu) or the like is used. In addition, the negative electrode active material layer 44 is a composite layer containing a negative electrode active material, a binder, a thickener, etc. As an example of a negative electrode active material, carbon materials such as graphite, hard carbon, and soft carbon can be listed. In addition, as other examples of negative electrode active materials, lithium titanate (LTO), silicon carbide (SiC), a composite containing carbon and silicon, silicon oxide (SiO X ) etc. In addition, as a binder, styrene butadiene rubber (SBR) etc. are used. As a thickener, carboxymethyl cellulose (CMC) etc. are used.

[0044] The separator 50 is an insulating sheet between the positive electrode plate 30 and the negative electrode plate 40. For the separator 50, for example, a resin material such as polyethylene (PE), polypropylene (PP), polyester, cellulose, polyamide, etc. is used. 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, mica, talc, boehmite, zeolite, apatite, and clay minerals such as kaolin.

[0045] (3) Electrolytes

[0046] In the lithium-ion secondary battery 1, an electrolyte is present between the positive electrode plate 30 and the negative electrode plate 40. Thus, charge carriers (Li ions) can be moved between the positive electrode plate 30 and the negative electrode plate 40. Furthermore, the form of the electrolyte is not limited to the technology disclosed herein, and a previously known form can be used without particular limitation. As an example of the form of the electrolyte, non-aqueous electrolyte, gel electrolyte, solid electrolyte, etc. can be listed.

[0047] 2. Manufacturing methods of battery materials

[0048] The manufacturing method according to this embodiment will be described below. Figure 3 This is a flowchart for explaining the manufacturing method according to the present embodiment. Figure 4 A flowchart is provided to explain the preparation process in detail. Figure 5 The following is a flow chart for explaining the separation process in detail.

[0049] like Figure 3 As shown, the manufacturing method according to the present embodiment includes a preparation step S10, a filling step S20, a collection step S30, a calcination step S40, a screening step S50, an acid seepage step S60, a separation step S70, a Li crystallization step S80, a NCM crystallization step S90, and an active material generation step S100. Each step is described below.

[0050] (1) Preparation step S10

[0051] In the preparation step S10, a lithium-ion secondary battery 1 charged to a predetermined reference SOC or above is prepared. In this step, as long as the battery charged to a reference SOC or above can be prepared, the specific steps are not particularly limited. In addition, the recycling object in the manufacturing method disclosed herein is preferably a used battery. Thereby, battery materials (typically Li) can be manufactured while reducing the burden on the environment. However, the recycling object of the manufacturing method disclosed herein is not limited to used batteries. For example, unused batteries that are considered defective and cannot be shipped during manufacturing can also be recycled.

[0052] Here, the preparation step S10 in this embodiment includes a measurement step S11, a determination step S12, and a charging step S13 (see Figure 4 ). Thus, it is possible to surely prepare a battery having a SOC higher than the reference SOC. This will be described in detail below.

[0053] (a) Measurement Step S11

[0054] In the measurement step S11, the SOC of the lithium-ion secondary battery 1 is measured. "SOC" in this specification means the depth of charge (State of Charge). Specifically, in this specification, the charging state that will become the upper limit of the operating voltage (that is, the state in which the voltage does not rise even if charging continues) is set to SOC = 100%. On the other hand, the charging state that will become the lower limit of the operating voltage (that is, the state in which the voltage does not drop even if discharging continues) is set to SOC = 0%. Moreover, in a battery with a high SOC (a fully charged battery), Li is absorbed in the negative electrode active material. On the other hand, in a battery with a low SOC (a fully discharged battery), Li is absorbed in the positive electrode active material. Furthermore, as for the specific means of SOC measurement, the previously known measurement means can be adopted without particular restriction, and is not limited to the technology disclosed herein, so the detailed description is omitted.

[0055] (b) Determination step S12

[0056] Next, in the determination step S12, it is determined whether the measured SOC is above the reference SOC. The "reference SOC" here is a threshold value indicating a state of charge in which sufficient Li is absorbed in the negative electrode active material. The reference SOC is preferably set according to the specifications (materials, dimensions, etc.) and degradation state of the recovery object (battery). Furthermore, if the reference SOC is set high, the amount of Li absorbed in the negative electrode active material increases, thereby having a tendency to improve the Li recovery rate in the collection step S30. For example, the reference SOC is preferably set to 30% or more (more preferably 35% or more, particularly preferably 40% or more). On the other hand, there is no particular limitation on the upper limit of the reference SOC, which can be 100%. However, if the reference SOC is set too high, there is a tendency for the energy and time required for Li recovery to increase due to unnecessary charging. From this point of view, the upper limit of the reference SOC is preferably set to 75% or less (more preferably 70% or less, further preferably 65% ​​or less, particularly preferably 60% or less). Then, in the determination step S12, when it is determined that the state of charge is equal to or greater than the reference SOC (Yes in S12), the preparation step S10 is terminated ( Figure 4 In this case, Figure 3 The filling step S20 shown is started. On the other hand, when the state of charge is less than the reference SOC (No in S12), the charging step S13 is performed.

[0057] (c) Charging Step S13

[0058] In the charging step S13, the lithium ion secondary battery 1 determined to be less than the reference SOC is charged until it reaches a reference SOC or above. In the manufacturing method according to the present embodiment, the preparation step S10 ( Figure 4 As described above, the preparation step S10 in the present embodiment includes the measurement step S11, the determination step S12, and the charging step S13. Thus, the battery charged to a reference SOC or higher can be reliably supplied to the filling step S20.

[0059] (2) Filling step S20

[0060] In this step, the interior of the lithium ion secondary battery 1 after the preparation step S10 is filled with an aqueous medium. In the liquid injection step S20, first, the sealing plug 17 is removed from the outer package 10 of the lithium ion secondary battery 1 (see Figure 1 ). Thus, the inside and outside of the outer packaging body 10 are connected through the injection hole 16. Then, the injection nozzle is inserted into the injection hole 16, and the aqueous medium is injected into the interior of the outer packaging body 10. Thus, the aqueous medium can be filled into the interior of the battery. Here, since the battery supplied to the filling step S20 has been charged to above the reference SOC, a large amount of Li is absorbed in the negative electrode active material. If the negative electrode active material is immersed in the aqueous medium, Li dissolves from the negative electrode active material into the aqueous medium. As a result, an aqueous medium in which a large amount of Li is dissolved (hereinafter also referred to as "Li solution") is prepared.

[0061] The "aqueous medium" in this specification refers to a liquid medium with water as the main component. As an example of the aqueous medium, water such as distilled water, ion exchange water, pure water and ultrapure water can be listed. In addition, the aqueous medium may contain components other than water as long as it does not significantly hinder the effect of the technology disclosed herein (Li dissolution from the negative electrode active material). For example, the aqueous medium may be an aqueous solution of a specified metal salt (sodium chloride, calcium chloride, lithium chloride, nitrate, organic acid, etc.). However, since these metal salts contain metal elements, they may become the cause of the increase in impurities in the separation step S70 described later. In addition, if an aqueous solution of a metal salt is used, there is a tendency for the dissolution of Li to decrease. From these viewpoints, the aqueous medium is preferably substantially free of metal salts. Specifically, the content of the metal salt relative to the total weight (100wt%) of the aqueous medium is preferably less than 0.1wt%, more preferably less than 0.05wt%, further preferably less than 0.01wt%, and particularly preferably less than 0.005wt%.

[0062] In addition, the aqueous medium may contain liquid media other than water. For example, as the aqueous medium, a mixed solution of water and an organic solvent soluble in the water (e.g., alcohol such as ethanol) can also be used. Furthermore, if the amount of Li dissolved is taken into consideration, the content of the organic solvent in the aqueous medium is preferably small. For example, the content of the organic solvent relative to the total weight (100wt%) of the aqueous medium is preferably 50wt% or less, more preferably 10wt% or less, further preferably 1wt% or less, and particularly preferably 0.1wt% or less.

[0063] It should be noted that the term "filling" in this specification refers to a state in which an aqueous medium exists only inside the battery (outer package). On the other hand, the term "immersion in water" in this specification refers to a state in which an aqueous medium continuously exists inside and outside the battery through the opening of the outer package (liquid injection hole 16, etc.). As will be described in detail later, it was confirmed by experiments that even if a charged battery is immersed in an aqueous medium, almost no dissolution of Li in the aqueous medium occurs. It is speculated that this is because if a charged battery is immersed in water, the voltage drops sharply due to an external short circuit, which hinders the dissolution of Li from the negative electrode active material. In the filling step in the manufacturing method disclosed herein, in order to prevent an external short circuit through the aqueous medium, the aqueous medium is only injected into the inside of the battery. As a result, the Li in the negative electrode active material can be appropriately dissolved in the aqueous solvent.

[0064] Furthermore, as for the Li in the negative electrode active material, almost all of it is dissolved out after one day from the filling of the aqueous solvent. However, from the viewpoint of making Li dissolve more reliably, in this process, it is preferred to leave the battery filled with the aqueous solvent to stand for more than one day (more preferably more than 2 days, and particularly preferably more than 3 days). On the other hand, if the manufacturing efficiency is considered, the upper limit of the standing time is preferably less than 14 days, more preferably less than 7 days, further preferably less than 5 days, and particularly preferably less than 4 days. Thus, it is possible to prevent the filling process S20 from being unnecessarily prolonged. In addition, the temperature of the aqueous medium in this process is preferably appropriately set in the range of 10°C to 40°C. Thus, the dissolution efficiency of Li can be improved.

[0065] (3) Collection process S30

[0066] In this process, an aqueous medium is collected from the inside of a lithium-ion secondary battery. As described above, the aqueous medium (Li solution) after the filling process S20 contains a large amount of Li. By collecting the Li solution, a large amount of Li can be recovered from the inside of the battery. As described above, the technology disclosed herein can achieve a high Li recovery rate when reproducing battery materials (Li) from a battery by implementing the preparation process S10, the filling process S20 and the collection process S30.

[0067] In addition, in the battery after the collection step S30, a part of Li and metal elements other than Li (Ni, Co, Mn, Al, Cu, etc.) may remain. Therefore, the manufacturing method disclosed herein may include a step of recovering valuable metals (Li, Ni, Co, Mn, etc.) from the battery after the collection step S30. An example of the step after the collection step S30 is described below.

[0068] (4) Calcination Step S40

[0069] In the manufacturing method involved in the present embodiment, a roasting step S40 is implemented to heat the battery after collecting the aqueous medium (Li solution). Among them, in the manufacturing method involved in the present embodiment, a large amount of Li can be recovered before the implementation of the roasting step S40. In addition, in the present embodiment, as a recycling object, a battery charged to a reference SOC or above (Li is retained on the negative electrode active material side) is prepared. Therefore, according to the manufacturing method involved in the present embodiment, it is possible to prevent a large amount of Li and Al from coexisting on the positive electrode side in the roasting step S40. As a result, it is possible to prevent the formation of an alloy of Li and Al (Li-Al alloy) in the roasting step S40. Thus, it is possible to more appropriately prevent a reduction in the Li recovery rate.

[0070] Furthermore, the heating temperature in this process is preferably 400°C or more, more preferably 500°C or more, further preferably 600°C or more, and particularly preferably 700°C or more. If the heating temperature in the roasting process S40 is increased, the oxygen element from the oxide of the valuable metal (transition metal composite oxide, etc.) to the carbon material (negative electrode active material, etc.) is easily transferred. As a result, the valuable metal can be reduced to a metallic state. The valuable metal in the metallic state can be easily dissolved in the acid seepage process S60 described later, so it can contribute to the improvement of manufacturing efficiency. On the other hand, from the perspective of the reduction of the valuable metal, the upper limit of the heating temperature is not particularly limited, and can be 1500°C or less, 1400°C or less, or 1300°C or less. Furthermore, if the cost required for heating is considered, the upper limit of the heating temperature is preferably 1200°C or less, more preferably 1100°C or less, and particularly preferably 1000°C or less. In addition, in this process, it is preferably implemented in an inert atmosphere such as argon and nitrogen. As a result, oxidation of the valuable metal during heating can be prevented.

[0071] (5) Screening step S50

[0072] In this step, the battery after the calcination step S40 is crushed and the components of the battery are sorted. Figure 1 In the lithium-ion secondary battery 1 shown, an electrode body 20 is contained inside the outer packaging body 10. Therefore, after the outer packaging body 10 is crushed, it is advisable to grind the electrode body 20 inside more finely. Then, the solid content after grinding is screened, and the recycling object (black agglomerate) of the sintered body of the electrode body 20 in powder form can be easily recovered. As a result, the content of impurities (Al, Cu, etc.) in the black agglomerate can be easily reduced, so the recovery efficiency of valuable metals (Li, Co, Ni, Mn, etc.) can be improved. However, the screening process S40 is not intended to completely remove impurities such as Al and Cu from the recycling object. It will be described in detail later that even if impurities are contained in the black agglomerate, the impurities can be removed by a subsequent process (acid leaching process S50, separation process S60, etc.). That is, this process can also be omitted as needed.

[0073] (6) Acid seepage step S60

[0074] Next, in the acid seepage step S60, the electrode body (black mass) after the collection step S30 (here, after the screening step S50) is immersed in an acid solution. In this way, an acid seepage solution in which the metal components (Li, Ni, Co, Mn, Cu, Al, etc.) in the black mass are dissolved in the acid solution can be prepared. On the other hand, the carbon in the black mass is not dissolved in the acid solution, so it precipitates as a residue. In this way, the carbon can be removed. Furthermore, as far as the acid seepage step is concerned, the conventionally known steps can be adopted without particular restrictions. As an example, the pH of the acid solution is preferably -1.5 to 1.5 (more preferably -0.5 to 0.5). In this way, the metal components in the black mass can be suitably dissolved. Furthermore, as specific examples of the acid solution, inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and organic acids such as citric acid, ascorbic acid, oxalic acid, and acetic acid can be listed. In addition, in this step, it is preferred to filter the acid seepage solution after the acid seepage. Thus, undissolved carbon can be removed efficiently. Furthermore, it is preferred that the temperature of the acid solution is 50°C or higher (more preferably 55°C or higher, particularly preferably 60°C or higher). Thus, the time required for the acid seepage step S60 can be shortened. In addition, there is no particular limitation on the upper limit of the temperature of the acid solution, and it can be 90°C or lower, 85°C or lower, or 80°C or lower.

[0075] (7) Separation step S70

[0076] As described above, the acid leaching solution obtained in the acid leaching step S60 contains Li, Al, Cu, Co, Ni, Mn, etc. In the separation step S70, these metal components are separated individually. Thus, each valuable metal can be recovered from the acid leaching solution. In the separation step S70, any conventionally known processing technology that can be used for metal extraction can be used without particular limitation. For example, in the separation step S70 of the present embodiment, Figure 5 As shown, a neutralization precipitation step S71, a Mn extraction step S72, a Co extraction step S73, a Ni extraction step S74, and a Li separation step S75 are performed.

[0077] (a) Neutralization and precipitation step S71

[0078] In this process, a neutralizing agent is added to the acid exudate obtained in the acid exudation process S60. As a result, a precipitate containing Al hydroxide (Al(OH)3) is precipitated in the acid exudate. As a result, most of the Al in the acid exudate can be removed. Furthermore, as a neutralizing agent used in this process, an alkaline solution with a pH of 11 to 15 (preferably pH 12 to 14) can be used. Furthermore, as specific examples of the alkaline solution, sodium hydroxide aqueous solution, calcium hydroxide, ammonia, etc. can be listed. In addition, in this process, it is also preferred to filter the acid exudate to separate the precipitate. As a result, Al(OH)3 can be efficiently removed from the acid exudate.

[0079] (b) Mn extraction step S72

[0080] In the Mn extraction process S72, Mn is extracted from the acid leaching solution. For example, in this process, it is appropriate to add an organic solvent (first extracting solution) having high extractability for Mn and low extractability for Li, Al, Cu, Co, and Ni to the acid leaching solution. Then, the acid leaching solution and the first extracting solution are stirred to make them suspended. Thus, the Mn in the acid leaching solution is dissolved in the first extracting solution. Then, the two liquids are left to stand until they are separated. Thus, a Mn solution in which Mn is dissolved in the first extracting solution and an acid leaching solution in which Mn is removed can be obtained. Furthermore, as the first extracting solution, a phosphate-based extracting agent, an oxime-based extracting agent, etc. can be used. As specific examples of phosphate-based extracting agents, di(2-ethylhexyl) phosphate (D2EHPA) and the like can be cited. Specific examples of oxime extractants include 2-hydroxy-5-nonylacetophenone oxime (LIX84), 5-dodecyl salicylaldehyde oxime (LIX860), 5-nonyl salicylaldehyde oxime (ACORGA M5640), etc. The first extractant may be a mixture of these extractants diluted therein.

[0081] In addition, in this process, the Mn solution after extraction (the first extract containing Mn) can be subjected to a back extraction treatment. In the back extraction treatment, first, the Mn solution (organic phase) and the acidic aqueous solution are stirred and mixed. Then, the two liquids are left to stand until they are separated. Thus, an aqueous Mn solution in which Mn is dissolved in the acidic aqueous solution can be obtained. Furthermore, as the acidic aqueous solution used in the back extraction treatment, sulfuric acid, hydrochloric acid, etc. (especially sulfuric acid) can be listed.

[0082] (c) Co extraction step S73

[0083] In the Co extraction step S73, Co is extracted from the acid leaching solution. Specifically, in this step, it is appropriate to add an organic solvent (second extracting solution) having high extractability for Co and low extractability for Li, Al, Cu, and Ni to the acid leaching solution. Thus, Co can be separated from the acid leaching solution, and a Co solution in which Co is dissolved in the second extracting solution can be obtained. Furthermore, as a specific example of the second extracting solution, phosphonic acid esters such as 2-ethylhexylphosphonic acid 2-ethylhexyl ester (PC-88A) can be cited. In addition, even for the extracted Co solution (the second extracting solution containing Co), a back extraction process can be implemented. Thus, an aqueous Co solution can be obtained.

[0084] (d) Ni extraction step S74

[0085] In the Ni extraction process S74, Ni is extracted from the acid leaching solution. Specifically, in this process, an organic solvent (third extracting solution) having high extractability for Ni and low extractability for Li, Al, and Cu is added to the acid leaching solution. Thus, Ni can be separated from the acid leaching solution, and a Ni solution in which Ni is dissolved in the third extracting solution can be obtained. Furthermore, as a specific example of the third extracting solution, carboxylic acid extractants such as neodecanoic acid and cyclohexane acid can be listed. In addition, even for the Ni solution after extraction (the third extracting solution containing Ni), a reverse extraction process can be implemented. Thus, an aqueous Ni solution can be obtained.

[0086] (e) Li separation step S75

[0087] As described above, the acid leaching solution after the Ni extraction step S64 has removed Ni, Co and Mn, so Li, Al and Cu become the main components. In this step, Cu and Al are removed from the acid leaching solution. In addition, there is no particular limitation on the means for removing Cu and Al, and conventionally known means such as solvent extraction method and ion exchange method can be appropriately adopted. Moreover, it is appropriate to mix the acid leaching solution after the Li separation step S75 with the Li solution obtained in the collection step S30. As a result, the Li recovery rate in the Li crystallization step S80 described later can be further improved.

[0088] (8) Li precipitation step S80

[0089] In this process, Li compounds are precipitated from the aqueous medium (Li solution) collected in the collection process S30. For example, in this process, it is appropriate to add sodium carbonate to the Li solution. As a result, crystals of lithium carbonate (Li2CO3) are precipitated. As described above, in the manufacturing method involved in the present embodiment, by implementing the filling process S20 and the collection process S30, a large amount of Li in the battery can be recovered. Furthermore, the Li remaining in the battery after the collection process S30 is recovered in the Li separation process S75. Then, the Li precipitation process S80 in the present embodiment precipitates the Li recovered in the collection process S30 and the Li separation process S75. As a result, a very high Li recovery rate (for example, more than 85%) can be achieved.

[0090] (9) NCM crystallization step S90

[0091] On the other hand, the valuable metals (Ni, Co, Mn) other than Li recovered in the separation step S70 become the materials of the precursor (NCM precursor) of the positive electrode active material. Specifically, in this step, a mixed solution of Co solution, Ni solution and Mn solution is prepared. Then, the pH of the mixed solution is controlled to be alkaline. As a result, crystals of NiCoMn hydroxide (NCM precursor) are precipitated. Furthermore, in the preparation of the mixed solution, it is advisable to change the mixing ratios of the Co solution, Ni solution and Mn solution as needed. Then, in the adjustment of pH, it is advisable to drip the mixed solution into the reaction tank together with an alkaline solution (ammonia water, sodium hydroxide aqueous solution).

[0092] (10) Active Material Generation Step S100

[0093] In this step, the NCM precursor obtained in the NCM crystallization step S90 and the Li compound obtained in the Li crystallization step S70 are used to generate a positive electrode active material. Specifically, the NCM precursor (NiCoMn hydroxide) and the Li compound (lithium carbonate) are mixed and sintered. Thus, a positive electrode active material (lithium transition metal composite oxide) for a lithium ion secondary battery can be manufactured.

[0094] 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 of the above-mentioned structure, a filling step of filling the interior of the battery charged to above the reference SOC with an aqueous medium is implemented. Thus, a Li solution in which Li in the negative electrode active material is dissolved in the aqueous medium can be prepared. By collecting the Li solution, a large amount of Li can be easily recovered. As described above, according to the manufacturing method involved in the present embodiment, a high Li recovery rate can be easily achieved.

[0095] 3. Other Implementation Methods

[0096] An embodiment of the technology disclosed herein has been described above. The technology disclosed herein is not limited to the above-described embodiment, and also includes other embodiments in which various configurations are changed. Other embodiments of the technology disclosed herein will be described below.

[0097] (1) About the process after the collection process

[0098] In the manufacturing method involved in the above-mentioned embodiment, after the collection step S30 is implemented, the roasting step S40 to the active material generation step S100 are implemented. However, the above-mentioned embodiment is not intended to limit the steps after the collection step S30 is implemented. That is, in the manufacturing method disclosed herein, the steps after the collection step can be added, deleted, or changed as needed.

[0099] For example, in the manufacturing method involved in the above-mentioned embodiment, various valuable metals (Li, Ni, Co, Mn) are recovered from the battery after the collection step S30 by implementing the roasting step S40 to the NCM crystallization step S90. However, the technology disclosed herein only needs to be able to efficiently recover Li from the lithium-ion secondary battery, so the roasting step S40 to the NCM crystallization step S90 is not necessarily implemented. For example, in the manufacturing method disclosed herein, a sufficient amount of Li can be recovered only by collecting the aqueous medium (Li solution) in which Li is dissolved. Therefore, the manufacturing method disclosed herein can use Li in the Li solution and transition metals (Ni, Co, Mn, etc.) that are not recycled materials to manufacture positive electrode active materials (lithium transition metal composite oxides).

[0100] In addition, the various separation treatments implemented in the separation step S70 are not limited to the above-mentioned neutralization precipitation step S71 to Li separation step S75. For example, a battery using lithium nickel manganese composite oxide as a positive electrode active material contains almost no cobalt (Co). In the case of such a battery as a recycling object, the Co extraction step S73 can be omitted. In addition, in the case where almost all of the Li in the battery can be recovered by using the filling step S20 and the collection step S30, the Li separation step S75 can also be omitted. As described above, the steps after the collection step S30 can be appropriately changed according to the constituent elements of the recycling object (battery) and are not limited to a specific step.

[0101] (2) For recycling objects

[0102] In addition, the recycling object in the manufacturing method disclosed herein is not limited to Figure 1 and Figure 2The lithium-ion secondary battery 1 shown in . For example, in the above-mentioned embodiment, an aluminum box-shaped shell is used as an outer package. However, the shape and material of the outer package are not limited to the technology disclosed herein. For example, the outer package can be a laminated outer package. The laminated outer package is formed by making two laminated films face each other in a state of clamping an electrode body and fusing the outer peripheral edge portions of the pair of laminated films. When such a laminated outer package is adopted, it is preferable to fill the outer package with an aqueous medium using a syringe or the like. Thereby, the aqueous medium can be easily filled into the battery.

[0103] [Test example]

[0104] Hereinafter, test examples related to the technology disclosed herein will be described. Note that the contents of the test examples described below are not intended to limit the technology disclosed herein.

[0105] 1. Preparation of test batteries

[0106] In this test, a predetermined test battery was prepared and Li was recovered from the test battery. The materials of the test battery used in this test are described below. First, in the test battery of this test, lithium nickel cobalt manganese composite oxide (LiNi) was used as the positive electrode active material. 1 / 3 Co 1 / 3 Mn 1 / 3 O2). For the positive electrode core, aluminum foil was used. On the other hand, for the negative electrode active material, graphite was used. For the negative electrode core, copper foil was used. Moreover, for the separator, a separator of a 3-layer structure of PP / PE / PE was used. In addition, for the outer packaging, an aluminum square shell was used. That is, the main components of the test battery in this test are Li, Ni, Co, Mn, Cu, Al, and C. In addition, 3V-class batteries were prepared in Test Examples 1 to 10, and 4.1V-class batteries were prepared in Test Examples 11 to 13.

[0107] 2. Li recovery steps

[0108] In this test, 13 test cases with different recovery steps were set up. The recovery steps in each case are described below.

[0109] (1) Test Example 1

[0110] In Test Example 1, first, the test battery is discharged until SOC=0% (battery residual capacity: 0.2Ah). Then, the discharged battery is heated (calcined) at 800°C. Then, the calcined electrode body (black lumps) is collected by sieving after crushing the outer packaging body. In addition, the Al components (positive electrode core, etc.) obtained during sieving are collected as Al components. Then, acid leaching is performed by immersing the black lumps in sulfuric acid. Thus, an acid leaching solution containing metal elements in the black lumps is obtained. Next, a neutralization precipitation is performed by dropping NaOH into the acid leaching solution in such a manner that the pH becomes 3 to 5. Thus, a precipitate is generated in the acid leaching solution. Then, solid-liquid separation is used to collect the acid leaching solution from which the precipitate has been removed.

[0111] (2) Test Example 2

[0112] In Test Example 2, the test battery discharged under the same conditions as in Test Example 1 was immersed in water. Specifically, after removing the sealing plug of the discharged battery, it was immersed (immersed in water) in 20L of an aqueous medium (5wt% sodium chloride aqueous solution) for 7 days. Then, the battery was lifted and the aqueous medium was collected. Then, for the recovered battery, roasting, acid seepage and neutralization precipitation were carried out under the same conditions as in Test Example 1, thereby collecting the acid seepage liquid and the Al component.

[0113] (3) Test Example 3

[0114] In Test Example 3, the interior of the test battery discharged under the same conditions as in Test Example 1 was filled with an aqueous medium. Specifically, the sealing plug of the discharged battery was removed, 100 mL of an aqueous medium (5 wt% sodium chloride aqueous solution) was injected into the outer package and then left to stand for 7 days. Then, the outer package was sucked to collect the aqueous medium. Then, for the battery with the aqueous medium in the outer package removed, roasting, acid exudation and neutralization precipitation were carried out under the same conditions as in Test Examples 1 and 2, thereby collecting the acid exudate and the Al component.

[0115] (4) Test Example 4

[0116] In Test Example 4, the aqueous medium filled in the battery was changed to pure water. Then, the other steps and conditions were set to be the same as those in Test Example 3, and the aqueous medium, the acid permeate, and the Al member were collected.

[0117] (5) Test Example 5

[0118] In Test Example 5, the test battery was charged to SOC = 20% (remaining capacity: 2.2 Ah). Then, the battery was filled with an aqueous solvent (pure water) in the same manner as in Test Example 4. Then, the aqueous medium, acid effluent, and Al member were collected in the same manner as in Test Examples 3 and 4.

[0119] (6) Test Example 6

[0120] In Test Example 6, except that the test battery was charged to SOC=40% (remaining capacity: 4.2 Ah), the aqueous medium, the acid seepage liquid, and the Al member were collected in the same procedure as in Test Examples 4 and 5.

[0121] (7) Test Example 7

[0122] In Test Example 7, the test battery was charged until SOC = 60% (remaining capacity: 6.2 Ah). Then, the test battery was immersed in an aqueous solvent (sodium chloride aqueous solution) in the same manner as in Test Example 2. Then, the aqueous medium, acid seepage liquid, and Al component were collected in the same manner as in Test Example 2.

[0123] (8) Test Example 8

[0124] In Test Example 8, the test battery was charged until SOC = 60% (remaining capacity: 6.2 Ah). Then, the battery was filled with an aqueous solvent (pure water) in the same manner as in Test Examples 4 to 6. Then, the aqueous medium, acid effusion, and Al component were collected in the same manner as in Test Examples 4 to 6.

[0125] (9) Test Example 9

[0126] In Test Example 9, the test battery was charged until SOC = 60% (remaining capacity: 6.2 Ah). Then, the battery was filled with an aqueous solvent in the same manner as in Test Examples 4 to 6. However, in Test Example 9, the aqueous solvent filled in the battery was changed to a 5 wt% sodium chloride aqueous solution. Then, the aqueous medium, the acid effluent, and the Al component were collected in the same manner as in Test Examples 4 to 6.

[0127] (10) Test Example 10

[0128] As described above, in Test Examples 10 to 12, 4.1V class batteries were used as test batteries. In Test Example 10, the test battery was charged until SOC = 100% (remaining capacity: 10.2 Ah). Then, as in Test Examples 4 to 6 and 8, the battery was filled with an aqueous solvent (pure water). Then, the aqueous medium, the acid effluent, and the Al component were collected in the same manner as in Test Examples 4 to 6 and 8.

[0129] (11) Test Example 11

[0130] In Test Example 11, first, the test battery was charged to SOC = 60% (remaining capacity: 6.2 Ah). Then, in Test Example 11, the charged battery was baked without filling with an aqueous solvent or soaking in water, as in Test Example 1. Then, the acid leaching liquid and the Al component were recovered in the same procedure as in Test Example 1.

[0131] (12) Test Example 12

[0132] In Test Example 12, the test battery was discharged until SOC=0%. Next, in Test Example 12, the battery was filled with an aqueous solvent (pure water) as in Test Examples 4 to 6 and 8. After the aqueous medium in the battery was collected, calcination, acid leaching and neutralization precipitation were performed as in the other test examples, thereby collecting the acid leaching liquid and the Al member. In Test Example 12, the heating temperature during calcination was lowered to 400°C.

[0133] (13) Test Example 13

[0134] In Test Example 13, the aqueous medium, the acid permeate, and the Al member were recovered in the same procedure as in Test Example 12 except that the test battery was charged to SOC=60% (remaining capacity: 6.2 Ah).

[0135] 3. Evaluation test

[0136] In this test, the amount of Li (g) contained in the samples (aqueous medium, acid seepage liquid, Al component) collected in each test example was measured. It should be noted that the amount of Li (g) in the aqueous medium was measured using a high-frequency inductively coupled plasma method (ICP: Inductively Coupled Plasma). It should be noted that the amount of Li (g) in the acid seepage liquid was measured by ICP after acid seepage. Moreover, the "amount of Li (g) in the acid seepage liquid" is regarded as the "amount of Li in the black mass (BM)". In addition, the amount of Li (g) in the precipitate was measured by ICP after the precipitate was dissolved with acid. The measurement results are shown in Table 1.

[0137] In this test, the amount of Li in the Al component was regarded as the "waste Li amount". On the other hand, the total amount of Li in the aqueous medium and the amount of Li in the BM was regarded as the "recovered Li amount". In addition, the ratio (%) of the recovered Li amount relative to the total Li amount (the total amount of Li used in the test battery in design) was calculated as the "Li recovery rate". The results are shown in Table 1.

[0138] [Table 1]

[0139]

[0140] As shown in Table 1, in Test Examples 6, 8 to 10, and 13, a very high Li recovery rate of 85% or more was achieved. It can be seen from this that if an aqueous medium is filled in a battery charged to a certain level or more, a large amount of Li is dissolved in the aqueous medium. It can also be seen that if the aqueous medium is recovered, the Li recovery rate can be significantly improved.

[0141] In addition, it was confirmed that in the acid leaching of Test Examples 1 to 11, the metal components in the black agglomerates were fully dissolved 4 hours after the black agglomerates were mixed with sulfuric acid. On the other hand, in Test Examples 12 and 13, it took about 12 hours for the metal components to be fully dissolved. It is speculated that this is because in Test Examples 12 and 13, the metal materials in the black agglomerates were not fully reduced due to the low calcination temperature, and a large amount of metal oxides remained.

[0142] The above is a detailed description of the technology disclosed herein, which is merely an example and does not limit the patent claims. The technology described in the patent claims includes various technical solutions that have been modified and changed from the specific examples illustrated above. That is, the technology disclosed herein includes the forms described in the following items 1 to 6.

[0143] <Project 1>

[0144] A method for manufacturing a battery material, comprising: a preparation step, in which a lithium-ion secondary battery charged to a predetermined reference SOC or above is prepared; a filling step, in which an aqueous medium is filled inside the lithium-ion secondary battery; and a collection step, in which the aqueous medium is collected from the inside of the lithium-ion secondary battery.

[0145] <Project 2>

[0146] A method for manufacturing a battery material according to Item 1, wherein the preparation step comprises: a measurement step, wherein the SOC of the lithium-ion secondary battery is measured; a determination step, wherein it is determined whether the measured SOC is above the reference SOC; and a charging step, wherein the lithium-ion secondary battery whose measured SOC is less than the reference SOC is charged to a level above the reference SOC.

[0147] <Project 3>

[0148] The method for producing a battery material according to item 1 or 2, wherein the reference SOC is set within a range of 20% to 100%.

[0149] <Item 4>

[0150] The method for manufacturing a battery material according to any one of items 1 to 3, further comprising: a roasting step, wherein the lithium-ion secondary battery after the collection step is heated; a screening step, wherein the electrode body is recovered from the inside of the lithium-ion secondary battery after the roasting step; and an acid seepage step, wherein the electrode body is immersed in an acid solution.

[0151] <Item 5>

[0152] The method for producing a battery material according to any one of items 1 to 4, wherein in the filling step, the lithium ion secondary battery filled with the aqueous medium is left to stand for one day or more.

[0153] <Item 6>

[0154] The method for producing a battery material according to any one of items 1 to 5, wherein the aqueous medium contains substantially no metal salt.

Claims

1. A method for manufacturing a battery material, comprising: a preparation step, wherein the lithium ion secondary battery is prepared to be charged to a predetermined reference SOC or above; a filling step, wherein an aqueous medium is filled in the interior of the lithium ion secondary battery; and A collecting step, wherein the aqueous medium is collected from the interior of the lithium ion secondary battery.

2. The method for producing a battery material according to claim 1, wherein: The preparation process includes: a measuring step, wherein the SOC of the lithium-ion secondary battery is measured; a determination step of determining whether the measured SOC is equal to or greater than the reference SOC; and The charging step includes charging the lithium ion secondary battery whose measured SOC is less than the reference SOC until the SOC becomes equal to or higher than the reference SOC.

3. The method for producing a battery material according to claim 1, wherein: The reference SOC is set within a range of 20% to 100%.

4. The method for manufacturing a battery material according to claim 1, further comprising: A roasting step, wherein the lithium-ion secondary battery after the collection step is heated; a screening step of recovering an electrode body from the interior of the lithium ion secondary battery after the calcining step; and The acid seepage step includes immersing the electrode body in an acid solution.

5. The method for producing a battery material according to claim 1, wherein: In the filling step, the lithium ion secondary battery filled with the aqueous medium is left to stand for one day or more.

6. The method for producing a battery material according to claim 1, wherein: The aqueous medium is substantially free of metal salts.

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