Method for regenerating positive electrode materials

Abstract

This disclosure provides a novel method for separating Li and Al from at least cathode waste. [Solution] The method for regenerating cathode material according to the present disclosure comprises the step of contacting at least cathode waste containing Li and Al with water in the presence of pressurized CO2 to leach Li and Al into the water.

Description

[Technical Field]

[0001] This disclosure relates to a method for regenerating cathode materials. [Background technology]

[0002] Lithium-ion secondary batteries are widely used in various fields, such as power sources for vehicle propulsion and portable power supplies. In recent years, material recycling of used lithium-ion secondary batteries has been promoted from the perspective of SDGs. Various metal elements are used in lithium-ion secondary batteries, and as an example of material recycling, the separation of metal elements contained in used lithium-ion secondary batteries is being carried out.

[0003] For example, Patent Document 1 describes how lithium-containing metals are leached from lithium-ion secondary battery waste using acid, ultimately recovering the lithium. Non-Patent Document 1 describes how Li, Ni, and Co are selectively separated from Li, Ni, Co, Mn, and Al contained in the positive electrode waste of used lithium-ion secondary batteries using a leachate containing ammonia and ammonium sulfate, and sodium sulfite as a reducing agent. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 7185090 [Non-patent literature]

[0005] [Non-Patent Document 1] Waste Management, February 2017, vol.60, p.680-688 [Overview of the project] [Problems that the invention aims to solve]

[0006] The metallic elements contained in the waste positive electrode of used lithium-ion secondary batteries are generally transition metal elements such as Ni, Co, and Mn, as well as Li, derived from the positive electrode active material, and Al, derived from the positive electrode current collector. The positive electrode active material is generally produced by mixing a lithium compound as a lithium source with a hydroxide containing transition metal elements and then calcining it. Therefore, it is desirable to recover and recycle Li and transition metal elements such as Ni, Co, and Mn separately, but conventional technology has the problem that transition metal elements such as Ni, Co, and Mn leach out at the same time as Li, increasing the subsequent separation process.

[0007] Therefore, this disclosure aims to provide a novel method capable of separating Li and Al from at least cathode waste. [Means for solving the problem]

[0008] The method for recycling cathode materials according to this disclosure comprises the step of contacting at least cathode waste containing Li and Al with water in the presence of pressurized CO2 to leach Li and Al into the water.

[0009] This configuration provides a novel method for separating Li and Al from at least the cathode waste. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a flowchart showing each step of the method for regenerating cathode material according to this disclosure. [Figure 2] Figure 2 is a schematic longitudinal cross-sectional view showing the internal structure of an example of a lithium-ion secondary battery. [Figure 3] Figure 3 is a schematic exploded view showing the configuration of the electrode body of the lithium-ion secondary battery shown in Figure 2. [Figure 4] Figure 4 is a schematic cross-sectional view of the positive electrode of the lithium-ion secondary battery shown in Figure 2. [Modes for carrying out the invention]

[0011] Embodiments relating to this disclosure will be described below with reference to the drawings. Matters not mentioned herein but necessary for the implementation of this disclosure can be understood as design matters for those skilled in the art based on prior art in the relevant field. This disclosure can be implemented based on the contents disclosed herein and common technical knowledge in the relevant field. In the following drawings, members and parts that perform the same function are denoted by the same reference numerals. Also, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships. In this specification, the numerical range expressed as "A~B" includes A and B.

[0012] In this specification, "secondary battery" refers to an energy storage device that can be repeatedly charged and discharged. Furthermore, in this specification, "lithium-ion secondary battery" refers to a secondary battery that uses lithium ions as a charge carrier and achieves charging and discharging through the transfer of charge associated with lithium ions between the positive and negative electrodes.

[0013] As shown in Figure 1, the method for regenerating cathode material according to the present disclosure includes as an essential step S101 of contacting at least cathode waste containing Li and Al with water in the presence of pressurized CO2 to leach Li and Al into the water (hereinafter also referred to as the "leaching step"). The method for regenerating cathode material according to the present disclosure may further include as an optional step S102 of removing dissolved CO2 from the water in which Li and Al have leached out and precipitating Al (hereinafter also referred to as the "defoaming step").

[0014] <Lithium-ion rechargeable battery> First, the method for recycling the positive electrode material of the present disclosure relates to the material recycling of secondary batteries (particularly lithium ion secondary batteries). First, a general configuration example of a lithium ion secondary battery will be described. Examples of the structure of a lithium ion secondary battery are shown in FIGS. 2 and 3. FIG. 2 is a longitudinal sectional view schematically showing the internal structure of an example of a lithium ion secondary battery. FIG. 3 is an exploded view schematically showing the electrode body of the lithium ion secondary battery shown in FIG. 2. FIG. 4 is a schematic sectional view along the thickness direction of the positive electrode of the lithium ion secondary battery shown in FIG. 2. Note that the following description of the lithium ion secondary battery is for the convenience of understanding and does not limit the method for recycling the positive electrode material of the present disclosure in any way.

[0015] As shown in FIG. 2, the lithium ion secondary battery 100 is a sealed battery in which a flat electrode body 20 and a non-aqueous electrolyte (not shown) are housed inside a battery case 30. As shown in FIG. 2, the battery case 30 is composed of an exterior body 32 that houses the electrode body 20 and a lid body 34 that seals the opening of the exterior body 32. The exterior body 32 and the lid body 34 are sealed by welding such as laser welding. As the material of the battery case 30, for example, aluminum, an aluminum alloy, a resin, etc. are used.

[0016] In the illustrated example, the battery case 30 is rectangular. However, the shape of the battery case 30 is not limited to this, and for example, it may be cylindrical. Alternatively, the battery case 30 may be a laminate case having a gas barrier layer such as an aluminum layer and a sealant layer containing a thermoplastic resin.

[0017] The battery case 30 includes a positive electrode terminal 42 and a negative electrode terminal 44 for external connection. Further, the battery case 30 is provided with a safety valve 36 that is set to release the internal pressure when the internal pressure of the battery case 30 rises above a predetermined level. The battery case 30 is provided with an injection port (not shown) for injecting a non-aqueous electrolyte. The positive electrode terminal 42 is electrically connected to a positive electrode current collector plate 42a. The negative electrode terminal 44 is electrically connected to a negative electrode current collector plate 44a.

[0018] As shown in FIGS. 2 and 3, the electrode body 20 has a form in which a long positive electrode sheet 50 and a long negative electrode sheet 60 are overlapped via two long separator sheets 70 and wound in the longitudinal direction. Therefore, in the present embodiment, the electrode body 20 is a wound electrode body. However, the electrode body 20 is not limited thereto, and may be a laminated electrode body in which a plurality of positive electrodes and a plurality of negative electrodes are alternately laminated via a separator.

[0019] As shown in FIGS. 2 and 4, in the positive electrode sheet 50, a positive electrode active material layer 54 is formed along the longitudinal direction on one side or both sides (here, both sides) of the positive electrode current collector 52. The positive electrode sheet 50 has a positive electrode active material layer non-formation portion 52a which is a portion where the positive electrode current collector 52 is exposed without the positive electrode active material layer 54 being formed. A positive electrode current collector plate 42a is joined to the positive electrode active material layer non-formation portion 52a.

[0020] Examples of the positive electrode current collector 52 constituting the positive electrode sheet 50 include aluminum foil and the like. The positive electrode active material layer 54 contains a positive electrode active material. Examples of the positive electrode active material include lithium composite metal oxides (e.g., lithium manganese-based composite oxides, lithium nickel manganese-based composite oxides, lithium nickel cobalt manganese-based composite oxides, lithium nickel cobalt aluminum-based composite oxides, etc.), lithium transition metal phosphate compounds (e.g., lithium iron phosphate, etc.). The positive electrode active material layer 54 may contain a conductive material (e.g., carbon black, carbon nanotubes, etc.), a binder (e.g., polyvinylidene fluoride, etc.), and the like.

[0021] The content of the positive electrode active material in the positive electrode active material layer 54 is preferably 70% by mass or more, more preferably 85% by mass or more and 99% by mass or less. The content of the conductive material in the positive electrode active material layer 54 is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.3% by mass or more and 15% by mass or less. The content of the binder in the positive electrode active material layer 54 is preferably 0.4% by mass or more and 15% by mass or less, more preferably 0.5% by mass or more and 10% by mass or less.

[0022] As shown in Figure 3, in the negative electrode sheet 60, a negative electrode active material layer 64 is formed along the longitudinal direction on one or both sides (in this case, both sides) of the negative electrode current collector 62. The negative electrode sheet 60 has a portion 62a where the negative electrode active material layer 64 is not formed and the negative electrode current collector 62 is exposed. A negative electrode current collector plate 44a is bonded to the portion 62a where the negative electrode active material layer is not formed.

[0023] An example of a negative electrode current collector 62 constituting the negative electrode sheet 60 is copper foil. The negative electrode active material layer 64 contains a negative electrode active material. Examples of negative electrode active materials include carbon-based negative electrode active materials (e.g., graphite, hard carbon, soft carbon, etc.) and silicon-based negative electrode active materials (e.g., silicon, silicon oxide, etc.). The negative electrode active material layer 64 may also contain a binder (e.g., styrene-butadiene rubber (SBR), etc.) and a thickener (e.g., carboxymethylcellulose (CMC), etc.).

[0024] The graphite content in the negative electrode active material layer 64 is preferably 90% by mass or more, and more preferably 95% by mass or more and 99% by mass or less. The binder content in the negative electrode active material layer 64 is preferably 0.1% by mass or more and 8% by mass or less, and more preferably 0.5% by mass or more and 3% by mass or less. The thickener content in the negative electrode active material layer 64 is preferably 0.3% by mass or more and 3% by mass or less, and more preferably 0.5% by mass or more and 2% by mass or less.

[0025] Examples of separators 70 include porous resin sheets such as polyethylene and polypropylene. The porous sheet may have a single-layer structure or a multi-layer structure. A heat-resistant layer (HRL) may be provided on the surface of the separator 70.

[0026] Non-aqueous electrolytes typically contain a non-aqueous solvent and a supporting salt (in other words, an electrolyte salt). Examples of non-aqueous solvents include carbonates (e.g., EC, ethyl methyl carbonate, dimethyl carbonate, etc.), esters, ethers, etc. Examples of supporting salts include lithium salts such as LiPF6. The concentration of the supporting salt is not particularly limited, but is preferably 0.7 mol / L to 1.3 mol / L. Non-aqueous electrolytes may also contain various additives such as gas generating agents and film-forming agents. In this embodiment, a non-aqueous electrolyte is used as the electrolyte, but the electrolyte may be a solid electrolyte.

[0027] The lithium-ion secondary battery 100 is used, for example, in automotive applications (i.e., as a power source for vehicles such as electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs)), and as a power source for electronic devices.

[0028] As described above, in lithium-ion secondary batteries, lithium (Li) is used as a constituent element of the positive electrode active material. Transition metal elements such as nickel (Ni), cosmic rayon (Co), and manganese (Mn) may also be used as constituent elements of the positive electrode active material. Al (Al) is also commonly used as a constituent element of the positive electrode active material. Thus, the positive electrode generally contains both Li and Al. In addition, lithium is used in the non-aqueous electrolyte of lithium-ion secondary batteries. Al may also be used in the battery case.

[0029] <Leaching process S101> The leaching process uses waste from the positive electrode containing Li and Al. That is, the waste used in the leaching process contains at least waste from the positive electrode containing Li and Al, and may further contain waste from the negative electrode and waste from other battery components (e.g., battery cases). The waste may have undergone some kind of treatment (e.g., roasting). Specific examples of waste include waste from positive electrodes deemed to be defective, waste from electrode bodies deemed to be defective, waste from positive electrodes removed from used lithium-ion secondary batteries, waste from electrode bodies removed from used lithium-ion secondary batteries, and black mass from used lithium-ion secondary batteries (in particular, black mass obtained by crushing and roasting used lithium-ion secondary batteries). Methods for obtaining these wastes are well known.

[0030] The waste preferably contains at least one of Li and Al as metals, and more preferably contains both Li and Al as metals. From this viewpoint, the waste is preferably reductively roasted. The waste is preferably black mass obtained by crushing and roasting used lithium-ion secondary batteries.

[0031] Specifically, this black mass can be obtained, for example, by crushing lithium-ion secondary batteries according to a known method, sieving them if necessary, and roasting them at 400°C to 1500°C (preferably 700°C to 1000°C) in an atmosphere with an oxygen concentration of 5% by volume or less (preferably 1% by volume or less) (especially in an inert gas atmosphere such as argon gas or nitrogen gas) for 1 to 24 hours (preferably 4 to 12 hours).

[0032] The waste may further contain elements other than Li and Al (especially metallic elements). For example, in addition to Li and Al, the waste may further contain at least one transition metal element selected from the group consisting of Ni, Co, and Mn. The waste may also further contain Cu. In particular, if the waste is lithium-ion secondary battery or electrode material waste, the waste generally further contains Cu derived from the negative electrode current collector.

[0033] In the leaching process S101, the waste is brought into contact with water in the presence of pressurized CO2. This causes Li and Al to leach from the waste into the water.

[0034] Since pressurized CO2 is used, a pressure vessel is usually used in the leaching process S101. As the pressure vessel, a known pressure vessel used in chemical reactions can be used. Specific examples include autoclaves, pressurized tanks, and pressurized chambers. The pressure vessel is preferably equipped with stirring means such as a stirring blade or magnetic stirring bar. The pressure vessel is preferably equipped with heating means such as a heater. The pressure vessel is preferably equipped with temperature measuring means such as a thermometer or temperature sensor.

[0035] In the leaching step S101, at least water is used as the leachate. The water may contain other components as long as they do not impair the effects of the present disclosure. Examples of other components include ammonia and pH adjusters such as ammonium carbonate, ammonium bicarbonate, and ammonium sulfate. Preferably, the water contains ammonia and ammonium carbonate, ammonium bicarbonate, or ammonium sulfate. In this case, it is preferable that the waste further contains at least one transition metal element selected from the group consisting of Ni, Co, and Mn.

[0036] The leaching process S101 can be carried out, for example, as follows: For example, first, waste and water are placed in a pressure vessel and sealed. Next, pressurized CO2 is introduced into the pressure vessel. The introduction of pressurized CO2 into the pressure vessel can be carried out according to a known method. Specifically, for example, the pressure vessel and the carbon dioxide cylinder are connected while a booster pump, valve, pressure gauge, etc. are installed in the flow path of the liquefied CO2 / CO2 gas. CO2 is introduced into the pressure vessel from the carbon dioxide cylinder at a predetermined pressure. After the introduction of pressurized CO2, leaching is carried out for a predetermined time.

[0037] The pressure of CO2 is equal to atmospheric pressure (i.e., 1.013 × 10⁻⁶). 5The pressure is not particularly limited as long as it is higher than (Pa). Also, Li is inherently soluble in water. On the other hand, when CO2 dissolves in water, Al becomes more soluble in water. This is thought to be because the dissolution of CO2 in water locally lowers the pH and makes it acidic. Therefore, the pressure of CO2 is preferably 0.5 MPa or higher, more preferably 3 MPa or higher, even more preferably 7.38 MPa or higher, and particularly preferably 10 MPa or higher. The pressure of CO2 may be 30 MPa or less, 20 MPa or less, or 15 MPa or less.

[0038] The leaching temperature is not particularly limited and may be at room temperature (i.e., 1°C to 30°C). Leaching may also be carried out under heating. In this case, the leaching temperature is preferably 31.1°C or higher, more preferably 45°C or higher, and even more preferably 60°C or higher. The leaching temperature may be 90°C or lower, 85°C or lower, or 80°C or lower.

[0039] Furthermore, the pressurized CO2 may be in a supercritical state. In this state, the leaching of Li and Al can be promoted. Therefore, it is particularly preferable that the CO2 pressure is 7.38 MPa or higher (especially 8 MPa to 20 MPa) and the leaching temperature is 31.1°C or higher (especially 45°C to 85°C).

[0040] To promote the leaching of Li and Al, stirring is preferable during leaching. The stirring speed is not particularly limited, but is preferably 200 rpm or higher, more preferably 300 rpm or higher, and even more preferably 400 rpm or higher. The stirring speed may be 2000 rpm or lower, or 1000 rpm or lower.

[0041] The leaching time is not particularly limited and may be determined as appropriate depending on the amount of water, the amount of waste, the leaching temperature, the CO2 pressure, etc. To ensure that CO2 is sufficiently dissolved in the water, the leaching time is preferably 2 hours or more, more preferably 3 hours or more. From the viewpoint of work efficiency, the leaching time is preferably 24 hours or less, more preferably 12 hours or less, and even more preferably 6 hours or less.

[0042] As described above, the leaching process S101 can be performed. The leaching process S101 allows for the extraction of Li and Al from the waste at a high rate (in other words, solid-liquid extraction). Therefore, the leaching process S101 yields water containing Li and Al (i.e., leachate). Note that CO2 is dissolved in this water.

[0043] Here, if the waste further contains at least one transition metal element selected from the group consisting of Ni, Co, and Mn, these transition metal elements hardly remain in the leachate but remain in the solid phase. This is thought to be because even if these transition metal elements dissolve when CO2 dissolved in water becomes carbonate ions, they form carbonates and remain in the solid phase. As described in Non-Patent Literature 1, if the water (i.e., the leachate) contains ammonia and ammonium carbonate, these transition metal elements dissolve in the leachate, but it is thought that this dissolution of CO2 promotes carbonate formation. Therefore, according to the method of this disclosure, Li and Al can be selectively leached with high selectivity from waste containing at least one transition metal element selected from the group consisting of Ni, Co, and Mn, as well as Li and Al.

[0044] Therefore, from another perspective, the cathode material recycling method of this disclosure can be applied as a method for separating at least one transition metal element selected from the group consisting of Ni, Co, and Mn from at least cathode waste containing Li and Al and at least one transition metal element selected from the group consisting of Ni, Co, and Mn.

[0045] <Defoaming process S102> The defoaming step S102 removes dissolved CO2 from the water containing leached Li and Al, causing Al to precipitate. This Al precipitation is thought to be due to a change in pH caused by the removal of CO2 from the water. This step can be carried out, for example, by placing the water containing leached Li and Al under reduced pressure to remove CO2 from the water.

[0046] The depressurization operation can be carried out according to known methods. For example, the depressurization operation can be carried out by introducing water containing leached Li and Al into a depressurization vessel or vacuum vessel and using a vacuum pump or the like. Alternatively, for example, the depressurization operation can be carried out using a rotary evaporator.

[0047] The pressure in the defoaming process S102 is atmospheric pressure (i.e., 1.013 × 10⁻⁶). 5 It is not particularly limited as long as it is lower than (Pa). The pressure is preferably 1 × 10⁻⁶. 4 Pa or less, fer 1 × 10 3 It is less than or equal to Pa. This pressure is 1 × 10⁻⁶. -1 It can be Pa or higher.

[0048] The time in the degassing step S102 may be appropriately determined according to the pressure, for example, 5 minutes to 24 hours, preferably 10 minutes to 6 hours, and more preferably 20 minutes to 2 hours.

[0049] By removing CO2 from the water, Al compounds can be precipitated. On the other hand, Li remains in the water. Therefore, Li and Al can be separated. Specifically, known solid-liquid separation methods (e.g., filtration) can be used to separate the solid component containing Al from the water containing Li.

[0050] From solids containing Al, Al can be recovered in the form of a desired aluminum compound or as metallic Al according to known methods. From water containing Li, Li can be recovered in the form of a desired lithium compound or as metallic Li according to known methods.

[0051] As described above, the method of this disclosure allows for the selective recovery of Li and Al with high selectivity. Furthermore, the method of this disclosure is advantageous because it can be implemented with a small number of steps. The method of this disclosure can also be applied as a method for producing Li, comprising a leaching step S101 and a defoaming step S102. Alternatively, the method of this disclosure can be applied as a method for producing Al, comprising a leaching step S101 and a defoaming step S102. Moreover, the transition metal element compounds such as Ni, Co, and Mn remaining in the solid phase can be used directly as raw materials for the cathode active material. Thus, the method of this disclosure is extremely useful in the material recycling of lithium-ion secondary batteries.

[0052] The following describes in detail some test examples relating to this disclosure, but this disclosure is not intended to be limited to those shown in such examples.

[0053] [Comparative Example 1] First, the roasted black mass of the leaching sample was prepared using the following procedure: Lithium nickel cobalt manganese composite oxide (LiNi) was placed on an aluminum (Al) foil. 0.6 Co 0.2 Mn 0.2 A positive electrode having a positive electrode active material layer containing O2 was crushed. The crushed positive electrode material was sieved through a 500 μm mesh sieve to produce positive electrode powder. A negative electrode having a negative electrode active material layer containing graphite on a copper foil was also crushed. The crushed negative electrode material was sieved through a 500 μm mesh sieve to produce negative electrode powder. The obtained positive electrode powder and negative electrode powder were mixed to obtain black mass. This black mass was roasted at 750°C for 6 hours in a low-oxygen atmosphere to obtain roasted black mass in which most of the metal was reduced.

[0054] Next, an aqueous leachate was prepared by mixing 28% by mass aqueous ammonia with ammonium sulfate ((NH4)2SO4) as a pH adjuster.

[0055] The above-mentioned roasted black trout was added to the aqueous leaching agent. Next, the aqueous leaching agent was stirred at a stirring speed of 500 rpm for 3 hours while maintaining the temperature at 80°C to allow leaching to occur. After that, solid-liquid separation was performed by filtration to obtain the leached liquid and leached residue.

[0056] [Comparative Example 2] In the preparation of the aqueous leachate, ammonium carbonate ((NH4)2CO3) was used instead of ammonium sulfate, except that the leachate and leachate residue were obtained by the same method as in Comparative Example 1.

[0057] [Comparative Example 3] Except for changing the ammonia leaching time from 3 hours to 6 hours, the leachate and leaching residue were obtained in the same manner as in Comparative Example 1.

[0058] [Example 1] Roasted black muss and an aqueous leaching agent were obtained in the same manner as in Comparative Example 1. The aqueous leaching agent and roasted black muss were placed in a pressure vessel, and the pressure vessel was further filled with CO2 gas to a pressure of 10 MPa. Next, ammonia leaching was carried out by stirring at a temperature of 80°C and a stirring speed of 500 rpm for 3 hours. After the pressure in the pressure vessel was returned to atmospheric pressure, solid-liquid separation was performed by filtration to obtain the leached liquid and leached residue.

[0059] [Evaluation of leaching rate] One g of roasted black mass used as a leaching sample was dissolved in acid, and high-frequency inductively coupled plasma (ICP) emission spectroscopy was performed on the solution. From the analysis results, the amounts of Li, Al, Ni, Co, and Mn in the roasted black mass were determined. The amounts of these metals correspond to the initial amounts before ammonia leaching.

[0060] Next, ICP emission spectroscopy was performed on the leachates obtained in each example and comparative example to determine the amounts of Li, Al, Ni, Co, and Mn in the leachates. The leaching rates of Li, Al, Ni, Co, and Mn were determined from the ratio (percentage) of the amount of these metals in the leachate to the initial amount of these metals in the roasted black mass. The results are shown in Table 1.

[0061]

Table 1

[0062] From the results in Table 1, it can be seen that by contacting the waste containing Li and Al with water in the presence of pressurized CO2, Li and Al can be leached at a high leaching rate. Also, from the results in Table 1, it can be seen that by contacting the waste containing Li and Al with water in the presence of pressurized CO2, Ni, Co and Mn can be separated from Li and Al with high selectivity. Therefore, according to the method for regenerating the positive electrode material of the present disclosure, it can be seen that by carrying out the leaching step S101, at least Li and Al can be separated from the waste of the positive electrode.

[0063] 〔Example 2〕 The leachate obtained in Example 1 was defoamed using a vacuum pump. Specifically, the leachate was transferred to a vacuum container, and the inside of the vacuum container was depressurized to about 10 3 Pa using a vacuum pump, and defoaming was carried out for 30 minutes. At this time, the generation of bubbles was confirmed from the leachate. Therefore, it was confirmed that CO2 was being released from the leachate. Also, precipitation of solids was observed in the leachate. Solid-liquid separation was carried out by filtration, and the precipitate was recovered. This precipitate was dissolved in an acid, and ICP emission spectroscopic analysis was performed to determine the metal content. The results are shown in Table 2.

[0064]

Table 2

[0065] [[ID=2,7]] From the results in Table 2, it can be seen that by removing the dissolved CO2 from the leachate, Al can be precipitated, and thereby Li and Al can be separated. Therefore, it can be seen that by carrying out the defoaming step S102, Li and Al can be separated.

[0066] As described above, specific examples of the present disclosure have been described in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

[0067] In other words, the method for regenerating the cathode material of this disclosure is as described in the following sections [1] to [9]. [1] A step of contacting at least cathode waste containing Li and Al with water in the presence of pressurized CO2 to leach Li and Al into the water. A method for regenerating positive electrode material. [2] The method according to item [1], wherein the water comprises ammonia and ammonium carbonate or ammonium sulfate. [3] The method according to item [1] or [2], wherein the pressurized CO2 is in a supercritical state. [4] The method according to any one of items [1] to [3], wherein the pressure of the pressurized CO2 is 8 MPa to 20 MPa, the leaching temperature is 45°C to 85°C, and the leaching time is 2 hours or more. [5] The method according to any one of items [1] to [4], wherein the waste further comprises at least one transition metal element selected from the group consisting of Ni, Co, and Mn. [6] The method according to any one of items [1] to [5], wherein the waste contains Li and Al as metals. [7] The method according to any one of items [1] to [6], wherein the waste is black mass obtained by crushing and roasting used lithium-ion secondary batteries. [8] The method according to any one of the claims [1] to [7], further comprising the step of removing dissolved CO2 from the water from which Li and Al have leached and precipitating Al. [9] The method according to item [8], wherein the step of precipitating Al includes placing the water in which Li and Al have leached under reduced pressure. [Explanation of Symbols]

[0068] 20 Electrode body 30 Battery Cases 32 Exterior 34 Lid 36 Safety valve 42 Positive terminal 42a Positive electrode current collector plate 44 Negative terminal 44a Negative current collector plate 50 positive electrode 52 Positive electrode current collector 52a Portion where positive electrode active material layer is not formed 54 Cathode active material layer 60 negative electrode 62 Negative electrode current collector 62a Part where negative electrode active material layer is not formed 64 Negative electrode active material layer 70 Separators 100 Lithium-ion rechargeable batteries

Claims

1. At least cathode waste containing Li and Al is processed using pressurized CO2. ２ A process of bringing the mixture into contact with water in the presence of a substance, thereby leaching Li and Al into the water. A method for regenerating positive electrode material.

2. The method according to claim 1, wherein the water comprises ammonia and ammonium carbonate or ammonium sulfate.

3. The aforementioned PressCO ２ The method according to claim 1, wherein the substance is in a supercritical state.

4. The aforementioned PressCO ２ The method according to claim 1, wherein the pressure is 8 MPa to 20 MPa, the leaching temperature is 45°C to 85°C, and the leaching time is 2 hours or more.

5. The method according to claim 1, wherein the waste further comprises at least one transition metal element selected from the group consisting of Ni, Co, and Mn.

6. The method according to claim 1, wherein the waste contains Li and Al as metals.

7. The method according to claim 1, wherein the waste is black mass obtained by crushing and roasting used lithium-ion secondary batteries.

8. From the water from which Li and Al have leached, dissolved CO ２ The method according to claim 1, further comprising the step of precipitating Al except for the following.

9. The method according to claim 8, wherein the step of precipitating Al includes placing the water in which Li and Al have leached under reduced pressure.

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