Method for regenerating a positive electrode material

Abstract

The present disclosure provides a novel method capable of recovering Ni and Co from battery waste containing Ni and Co while adjusting the Ni / Co ratio. The method for regenerating a positive electrode material of the present disclosure includes a step of leaching Ni and Co from battery waste containing Ni and Co into an aqueous ammonia solution containing ammonia and ammonium sulfate. Here, in the leaching, oxygen is supplied to the aqueous ammonia solution.

Description

Technical Field

[0001] This invention relates to a method for regenerating cathode materials. It should be noted that this application claims priority to Japanese Patent Application No. 2024-216384, filed December 11, 2024, the entire contents of which are incorporated herein by reference. Background Technology

[0002] Lithium-ion rechargeable batteries are widely used in various fields, including vehicle power supplies and portable power sources. In recent years, from the perspective of the SDGs (Safety, Government, and Goods Administration), the reuse of materials from used lithium-ion rechargeable batteries is being promoted. Various metal elements are used in lithium-ion rechargeable batteries, and for the purpose of material recycling, technologies are being developed to separate the metal elements contained in used lithium-ion rechargeable batteries.

[0003] Representative examples of positive electrode active materials for lithium-ion secondary batteries used in automotive applications include lithium nickel cobalt manganese composite oxide (NCM) and lithium nickel cobalt aluminum composite oxide (NCA), both of which contain Ni and Co. Therefore, waste from lithium-ion secondary batteries using these positive electrode active materials contains Ni and Co. In Non-Patent Literature 1, a leaching solution containing ammonia and ammonium sulfate, and sodium sulfite as a reducing agent, are used to selectively separate Ni and Co from Ni, Co, Mn, and Al contained in the positive electrode waste of used lithium-ion secondary batteries.

[0004] Existing technical documents

[0005] Non-patent literature

[0006] Non-patent literature 1: Waste Management, February 2017, vol.60, pp.680-688 Summary of the Invention

[0007] In the aforementioned prior art, since Ni and Co are separated together, from a production efficiency point of view, it is advantageous to reuse Ni and Co in the manufacture of the positive electrode active material without separating them. On the other hand, conventionally used lithium nickel cobalt manganese composite oxides often use equimolar amounts of Ni, Co, and Mn (e.g., LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2, etc.). That is, the molar ratio of Ni / Co (hereinafter sometimes simply referred to as the "Ni / Co ratio") is 1. However, from the perspective of increasing battery capacity, compositions with a high nickel content (e.g., LiNi with a Ni / Co ratio of 3) have been developed in recent years. 0.6 Co 0.2 Mn 0.2 LiNi with O2 and a Ni / Co ratio of 8 0.8Co 0.1 Mn 0.1 Lithium-nickel-cobalt-manganese composite oxides (such as O2). Additionally, lithium-nickel-cobalt-aluminum composite oxides also have a high nickel content (e.g., LiNi). 0.8 Co 0.15 Al 0.05 The Ni / Co ratio of O2 is 5.3.

[0008] Therefore, there is a problem that the Ni / Co ratio in recycled lithium-ion secondary batteries can easily differ from the Ni / Co ratio in the cathode active material to be regenerated (especially the problem that the Ni / Co ratio in the cathode active material to be regenerated can easily become high). Therefore, it would be useful if there were a method that could recover Ni and Co from battery waste containing Ni and Co while adjusting the Ni / Co ratio, especially by adjusting the Ni / Co ratio in a way that increases the Ni / Co ratio.

[0009] Therefore, the purpose of this disclosure is to provide a new method for recovering Ni and Co from battery waste containing Ni and Co by adjusting the Ni / Co ratio.

[0010] The method for regenerating the cathode material disclosed herein includes a step of leaching Ni and Co from battery waste containing Ni and Co into the ammonia solution using an ammonia solution containing ammonia and ammonium sulfate. Here, oxygen is supplied to the ammonia solution during the leaching process.

[0011] Based on this configuration, it is possible to recover Ni and Co from battery waste containing Ni and Co by adjusting the Ni / Co ratio. Attached Figure Description

[0012] Figure 1 The flowchart illustrates the steps of the method for regenerating the cathode material involved in this disclosure.

[0013] Figure 2 A longitudinal cross-sectional view illustrating the internal structure of an example of a lithium-ion secondary battery.

[0014] Figure 3 To show Figure 2 The diagram shows an exploded view of the electrode structure of a lithium-ion secondary battery.

[0015] Figure 4 To show Figure 2 A schematic cross-sectional view of the positive electrode of a lithium-ion secondary battery. Detailed Implementation

[0016] The embodiments disclosed herein will now be described with reference to the accompanying drawings. It should be noted that any matters required for implementing this disclosure not mentioned in this specification can be understood by those skilled in the art based on existing technology in the field. This disclosure can be implemented based on the content disclosed in this specification and common technical knowledge in the field. Furthermore, in the following drawings, components and parts that perform the same function are labeled with the same symbols. Additionally, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect actual dimensional relationships. Moreover, the numerical range represented as "A to B" in this specification includes both A and B.

[0017] It should be noted that in this specification, "secondary battery" refers to an energy storage device capable of repeated charging and discharging. Furthermore, in this specification, "lithium-ion secondary battery" refers to a secondary battery that uses lithium ions as charge carriers and achieves charging and discharging through the movement of lithium ions' charge between the positive and negative electrodes.

[0018] Figure 1 The following flowchart illustrates the steps of the method for regenerating the cathode material according to this disclosure. As a necessary step in the method for regenerating the cathode material of this disclosure, a step (hereinafter also referred to as the "leaching step") S100 is included, in which Ni and Co are leached from battery waste containing Ni and Co into the ammonia solution using an ammonia solution containing ammonia and ammonium sulfate. In this leaching step S100, oxygen is supplied to the ammonia solution during the leaching process. Additionally, as an optional step in the method for regenerating the cathode material of this disclosure, a step (hereinafter also referred to as the "Ni / Co ratio confirmation step") S10 may be included, prior to the leaching step S100; and a step (hereinafter also referred to as the "ammonium sulfate amount selection step") S20, in which the amount of ammonium sulfate is selected based on the desired molar ratio of Ni to Co. Furthermore, in the leaching step S100, Co compounds precipitate. With regard to the method for regenerating the cathode material disclosed herein, as an optional step, it may further include a step (hereinafter also referred to as the "Co separation step") S30 in which the Co compound precipitated in the leaching step S100 is dissolved in water and separated from the solid residue.

[0019] <Lithium-ion secondary batteries>

[0020] First, the method for regenerating cathode materials disclosed herein relates to the recycling of materials in secondary batteries (particularly lithium-ion secondary batteries). First, a general configuration example of a lithium-ion secondary battery will be described. Figure 2 and Figure 3 An example of the structure of a lithium-ion secondary battery is shown. Figure 2 A longitudinal cross-sectional view illustrating the internal structure of an example of a lithium-ion secondary battery. Figure 3 To illustrate Figure 2An exploded view of the electrode body of a lithium-ion secondary battery is shown. Figure 4 For along Figure 2 The diagram shows a schematic cross-sectional view of the positive electrode of a lithium-ion secondary battery along its thickness. It should be noted that the following description of the lithium-ion secondary battery is for ease of understanding and does not limit the method for regenerating the positive electrode material disclosed herein.

[0021] like Figure 2 As shown, the lithium-ion secondary battery 100 is a sealed battery in which a flat electrode 20 and a non-aqueous electrolyte (not shown) are housed inside the battery casing 30. Figure 2 As shown, the battery casing 30 consists of an outer packaging body 32 that houses the electrode body 20 and a cover 34 that seals the opening of the outer packaging body 32. The outer packaging body 32 and the cover 34 are sealed by welding, such as laser welding. Materials used for the battery casing 30 include, for example, aluminum, aluminum alloy, and resin.

[0022] In the example shown, the battery casing 30 is square. However, the shape of the battery casing 30 is not limited to this; for example, it could also be cylindrical. Alternatively, the battery casing 30 could also be a laminated casing having a gas barrier layer, such as an aluminum layer, and a sealant layer containing a thermoplastic resin.

[0023] The battery casing 30 has a positive terminal 42 and a negative terminal 44 for external connection. Additionally, the battery casing 30 is equipped with a safety valve 36 configured to release internal pressure when the internal pressure rises above a predetermined level. The battery casing 30 also has an injection port (not shown) for injecting a non-aqueous electrolyte. The positive terminal 42 is electrically connected to the positive current collector 42a. The negative terminal 44 is electrically connected to the negative current collector 44a.

[0024] like Figure 2 and Figure 3 As shown, the electrode body 20 has a strip-shaped positive electrode 50 and a strip-shaped negative electrode 60 that are overlapped and wound along the length direction by two strip-shaped separator sheets 70. Therefore, in this embodiment, the electrode body 20 is a wound electrode body. However, the electrode body 20 is not limited to this, and may also be a stacked electrode body in which multiple positive electrodes and multiple negative electrodes are alternately stacked by separator sheets.

[0025] like Figure 2 and Figure 4 As shown, in the positive electrode 50, a positive active material layer 54 is formed along the length direction on one or both sides (in this case, both sides) of the positive current collector 52. The positive electrode 50 has a non-formed portion 52a of the positive active material layer, which is the portion where the positive active material layer 54 is exposed without the formation of the positive current collector 52. A positive current collector plate 42a is bonded to the non-formed portion 52a of the positive active material layer.

[0026] Examples of positive current collector 52 constituting the positive electrode sheet 50 include aluminum foil. The positive electrode active material layer 54 contains a positive electrode active material. The positive electrode active material is typically a lithium transition metal composite oxide containing Ni and Co. Examples of such positive electrode active materials include lithium nickel cobalt manganese composite oxides and lithium nickel cobalt aluminum composite oxides. The positive electrode active material layer 54 may contain conductive materials (e.g., carbon black, carbon nanotubes, etc.), binders (e.g., polyvinylidene fluoride, etc.), etc.

[0027] 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.

[0028] like Figure 3 As shown, in the negative electrode sheet 60, a negative electrode active material layer 64 is formed along the length 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 non-formed portion 62a of the negative electrode active material layer, which is the portion of the negative electrode current collector 62 exposed where the negative electrode active material layer 64 is not formed. A negative electrode current collector plate 44a is bonded to the non-formed portion 62a of the negative electrode active material layer.

[0029] Examples of negative electrode current collector 62 constituting negative electrode sheet 60 include 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 contain adhesives (e.g., styrene-butadiene rubber (SBR), tackifiers, etc.) and carboxymethyl cellulose (CMC), etc.

[0030] The content of negative electrode active material in the negative electrode active material layer 64 is preferably 90% by mass or more, more preferably 95% by mass or more and 99% by mass or less. The content of binder in the negative electrode active material layer 64 is preferably 0.1% by mass or more and 8% by mass or less, more preferably 0.5% by mass or more and 3% by mass or less. The content of tackifier in the negative electrode active material layer 64 is preferably 0.3% by mass or more and 3% by mass or less, more preferably 0.5% by mass or more and 2% by mass or less.

[0031] Examples of separators 70 include porous resin sheets such as polyethylene and polypropylene. The porous sheets can be single-layered or multi-layered. A heat-resistant layer (HRL) may also be provided on the surface of the separator 70.

[0032] In the case of non-aqueous electrolytes, typically, a non-aqueous electrolyte contains 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. The non-aqueous electrolyte may contain various additives such as gas generators and film-forming agents. Furthermore, in this embodiment, a non-aqueous electrolyte is used as the electrolyte, and the electrolyte may be a solid electrolyte.

[0033] The lithium-ion secondary battery 100 is used, for example, for automotive applications (i.e., as a power source for vehicles such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs)) and as a power source for electronic devices.

[0034] As mentioned above, in the positive electrode of a lithium-ion secondary battery, the constituent metal elements as the positive electrode active material are typically Li, Ni, and Co. The positive electrode active material may further include Mn and Al. Al is generally used in the positive electrode current collector. Cu is generally used in the negative electrode current collector. Furthermore, Li is used in the non-aqueous electrolyte of lithium-ion secondary batteries. Additionally, Al can be used in the battery casing.

[0035] <Leaching process S100>

[0036] In the leaching process S100, battery waste containing Ni and Co is used. The Ni and Co contained in the battery waste typically originate from positive electrode active materials (especially lithium transition metal complex oxides containing Ni and Co). However, the Ni and Co contained in the battery waste are not limited to these. Furthermore, in this specification, "battery waste" includes not only used lithium-ion secondary batteries, but also components of used lithium-ion secondary batteries, defective lithium-ion secondary batteries, and components of defective lithium-ion secondary batteries. The waste may be waste that has undergone certain treatments (e.g., roasting).

[0037] Specific examples of battery waste include black powder from used lithium-ion secondary batteries (especially black powder obtained by crushing and roasting used lithium-ion secondary batteries), positive electrode waste from used lithium-ion secondary batteries, electrode body waste from used lithium-ion secondary batteries, waste from positive electrodes judged to be defective, waste from electrode bodies judged to be defective, and positive electrode active materials judged to be defective.

[0038] The waste preferably contains Ni and Co in metallic form. From this point of view, it is preferable to reductively roast the waste. As waste, blackmass obtained by crushing and reductively roasting used lithium-ion secondary batteries is preferred.

[0039] Specifically, this black powder can be obtained, for example, by crushing a lithium-ion secondary battery according to a known method, sieving it as needed, and calcining it in an atmosphere (especially inactive gas atmospheres such as argon or nitrogen) with an oxygen concentration of 400°C to 1500°C (preferably 700°C to 1000°C) and less than 5% by volume (preferably less than 1% by volume).

[0040] Battery waste may further contain elements other than Ni and Co (especially metallic elements). For example, in addition to Ni and Co, battery waste may further contain Li, Mn, Al, etc. Battery waste may further contain transition metal elements other than Ni and Co.

[0041] In the leaching process S100, an aqueous ammonia solution containing ammonia (NH3) and ammonium sulfate ((NH4)2SO4) is used as the leaching agent.

[0042] In the ammonia solution, the concentration of ammonia is not particularly limited; a higher concentration results in higher leaching capacity. Therefore, the concentration of ammonia in the ammonia solution is, for example, 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, the upper limit of the ammonia concentration is the saturation concentration of ammonia in water, which is approximately 35% by mass. From the viewpoint of leaching capacity and ease of processing, the ammonia concentration is particularly preferably 15% by mass to 25% by mass.

[0043] Typically, when leaching waste containing Ni and Co using an aqueous solution containing ammonia and ammonium sulfate, Ni and Co readily form an ammonia complex for leaching. Therefore, the molar ratio of Ni to Co in the leachate (i.e., the Ni / Co ratio) is the same as or approximately the same as the Ni / Co ratio in the waste.

[0044] In contrast, in the cathode material regeneration method of this disclosure, oxygen is supplied to the ammonia solution during leaching. This dissolves oxygen in the ammonia solution. With oxygen dissolved in the aqueous solution, a portion of the Co temporarily leached into the ammonia solution precipitates as a Co compound via ammonium sulfate. Therefore, the amount of Co dissolved in the ammonia solution decreases, and the Ni / Co ratio in the leachate increases relative to the Ni / Co ratio in the waste. Here, the amount of Co precipitated depends on the amount of ammonium sulfate in the ammonia solution. Therefore, according to the cathode material regeneration method of this disclosure, by supplying oxygen to the ammonia solution, the Ni / Co ratio can be adjusted by controlling the amount of ammonium sulfate.

[0045] Therefore, in the regeneration method of the cathode material disclosed herein, the amount of ammonium sulfate can be appropriately determined based on the ratio of Ni to Co to be leached into the aqueous solution (i.e., the desired Ni / Co ratio). The more ammonium sulfate is added, the more Co is precipitated, thus the Co content in the leaching becomes smaller, and the Ni / Co ratio becomes larger.

[0046] From the viewpoint of precipitating temporarily leached Co, the amount of ammonium sulfate is preferably 5 molar times or more, more preferably 7 molar times or more, relative to the amount of Co in the battery waste. The amount of ammonium sulfate relative to the amount of Co in the battery waste can be 100 molar times or less, 50 molar times or less, or 40 molar times or less. Furthermore, the concentration of ammonium sulfate in the ammonia solution is preferably 1.2 mol / L or more, more preferably 1.4 mol / L or more. The concentration of ammonium sulfate in the ammonia solution can be 3.0 mol / L or less, or 2.5 mol / L or less.

[0047] The ammonia solution may contain only water, ammonia, and ammonium sulfate. With respect to the ammonia solution, it may further contain components other than water, ammonia, and ammonium sulfate to a extent that does not impair the effects of this disclosure (e.g., concentrations of less than 10%, 5%, or 1% by mass).

[0048] The preferred amount of ammonia solution used is the amount that completely impregnates the battery waste.

[0049] In the leaching process S100, oxygen is supplied to the ammonia solution during leaching. Oxygen supply can be achieved, for example, by introducing an oxygen-containing gas (e.g., oxygen gas, atmosphere, etc.) into the ammonia solution through bubbling. In this case, the smaller the bubbles, the more effectively the dissolved oxygen content can be increased. Alternatively, oxygen supply can be achieved, for example, by introducing oxygen into a sealed container while pressurizing it.

[0050] The leaching process S100 can be performed as follows, for example. First, a container is prepared. The container can be a known container used in ammonia leaching. Heating means such as a heater, temperature measuring means such as a thermometer and temperature sensor, stirring means such as stirring blades and magnetic stir bar are installed on the container as needed. Next, a bubbling device is prepared. The bubbling device can be a known device used in leaching. The bubbling device can be installed on the container before the battery waste and ammonia leaching solution are added, or it can be installed on the container after the battery waste and ammonia leaching solution are added.

[0051] Battery waste and an ammonia solution are added to the container. There is no particular order in which they are added; either can be added first, or simultaneously. Meanwhile, an oxygen-containing gas is supplied to the ammonia solution via a bubbling device. Preferably, the oxygen is supplied to the ammonia solution via bubbling.

[0052] The oxygen supply is preferably equimolar or more relative to the potentially oxidizable elements (especially Ni and Co) contained in the battery waste, more preferably 2 molar times or more, and even more preferably 3 molar times or more. The oxygen supply can be less than 100 molar times relative to the potentially oxidizable elements contained in the battery waste.

[0053] The leaching process S100 can be carried out at room temperature (i.e., 25±10°C) or under heating. The leaching temperature is preferably 15°C or higher, more preferably 20°C or higher. On the other hand, the leaching temperature can be 90°C or lower, 85°C or lower, or 80°C or lower.

[0054] The leaching time can be appropriately determined based on the leaching temperature. Higher leaching temperatures allow for faster leaching completion. Furthermore, by dissolving oxygen in an ammonia solution, the leaching rate of Ni and Co increases. This is attributed to the oxidation of Ni and Co. The leaching time is, for example, 1 hour or more, preferably 2 hours or more, and more preferably 4 hours or more. On the other hand, from the viewpoint of operational efficiency, the leaching time is, for example, 48 hours or less, preferably 24 hours or less, and more preferably 10 hours or less.

[0055] Stirring is preferred during leaching. There is no particular limitation on the stirring speed, but 200 rpm or more is preferred, more preferably 400 rpm or more, and even more preferably 500 rpm or more. The stirring speed can be 2000 rpm or less, 1000 rpm or less, or 800 rpm or less.

[0056] Therefore, by performing ammonia leaching, Ni and Co can be leached into the aqueous phase (i.e., an aqueous ammonia solution). That is, the leaching process S100 can be performed. Ammonia leaching can be completed by performing solid-liquid separation of the filtrate, etc. Through this solid-liquid separation, a leachate (i.e., the aqueous phase from which Ni and Co are leached) and solid residue can be obtained.

[0057] Furthermore, the solid residue contained precipitated Co compounds. These Co compounds are water-soluble salts, and analysis using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) revealed the presence of both Co and S elements, thus identifying them as cobalt sulfate. The precipitated Co compounds can be separated and recovered from the solid residue by dissolving them in water.

[0058] Therefore, as Figure 1 As shown, the method for regenerating the cathode material disclosed herein may further include a Co separation step S30.

[0059] <Co Separation Process S30>

[0060] In the Co separation step S30, the Co compound precipitated in the leaching step S100 is dissolved in water and separated from the solid residue. This Co separation step S30 can be carried out according to known methods. Specifically, for example, it can be carried out by immersing the solid residue in water. Alternatively, it can be carried out by washing the solid residue with water. Co can be recovered from the water containing the dissolved Co compound according to known methods.

[0061] When the electrode waste contains Mn and Al, Mn and Al remain in the solid residue obtained in the leaching step S100. In the Co separation step S30, Mn and Al still remain in the solid residue. Therefore, in this case, Mn and Al can be separated from Co in the Co separation step S30.

[0062] Furthermore, as described above, according to the present disclosure's method for regenerating the cathode material by supplying oxygen during leaching, the Ni / Co ratio in the leachate can be adjusted by controlling the concentration of ammonium sulfate. In particular, it can be adjusted in such a way that the Ni / Co ratio in the leachate becomes higher.

[0063] Therefore, regarding the method for regenerating the cathode material disclosed herein, such as Figure 1 As shown, before the leaching step S100, a Ni / Co ratio confirmation step S10 and an ammonium sulfate amount selection step S20 may be further included.

[0064] <Ni / Co ratio verification process S10>

[0065] In the Ni / Co ratio confirmation step S10, the Ni / Co ratio of the battery waste is confirmed. When the materials used in the battery waste are clearly defined, the Ni / Co ratio can be determined accordingly. For example, if the composition of the positive electrode active material is clearly defined, and Ni and Co are not used except in the positive electrode active material, the Ni / Co ratio in the positive electrode active material can be set as the Ni / Co ratio in the battery waste.

[0066] When the materials used in battery waste are unknown, the Ni / Co ratio in the battery waste can be determined using known methods. Specifically, for example, the Ni and Co content in the waste can be determined separately using high-frequency inductively coupled plasma (ICP) emission spectroscopy analysis according to known methods. Using the obtained Ni and Co content, the Ni / Co ratio can be calculated.

[0067] <Ammonium sulfate dosage selection process S20>

[0068] In the ammonium sulfate amount selection step S20, the amount of ammonium sulfate is selected based on the desired molar ratio of Ni to Co. Specifically, based on the Ni / Co ratio obtained from the Ni / Co ratio confirmation step S10, the amount of ammonium sulfate is selected in such a way that the amount of Ni and Co in the leachate meets the desired Ni / Co ratio. The desired Ni / Co ratio is typically the Ni / Co ratio when Ni and Co are reused.

[0069] To make this selection, it is preferable to collect a portion of the battery waste as a sample and conduct preliminary experiments to determine the relationship between the amount of ammonium sulfate and the Ni / Co ratio in the ammonia solution. It is advantageous to prepare a standard curve of the amount of ammonium sulfate and the Ni / Co ratio in the ammonia solution. Therefore, this process can select the amount of ammonium sulfate based on this standard curve.

[0070] Alternatively, to make this selection, it is advantageous to conduct preliminary experiments on battery waste with various Ni / Co ratios and to pre-database the relationship between the Ni / Co ratio in the battery waste and the amount of ammonium sulfate, as well as the Ni / Co ratio leached into the aqueous solution. The process can then select the amount of ammonium sulfate based on this database.

[0071] The amount of ammonium sulfate can also be selected by utilizing standard curves or databases to create programs and then using those programs.

[0072] The leaching process S100 is performed based on the selected amount of ammonium sulfate, thereby obtaining a leachate containing Ni and Co at the desired Ni / Co ratio. According to known methods, Ni and Co can be separated from the leachate at the desired Ni / Co ratio. Alternatively, the leachate containing Ni and Co at the desired Ni / Co ratio can be directly used in the manufacture of positive electrode active materials.

[0073] According to the cathode material regeneration method disclosed herein, Ni and Co can be recovered from battery waste containing Ni and Co while adjusting the Ni / Co ratio. Specifically, Ni and Co can be recovered while adjusting the Ni / Co ratio to increase it. Furthermore, the cathode material regeneration method of this disclosure is easy to implement. Additionally, the leaching rate of Ni and Co is increased according to the cathode material regeneration method of this disclosure. Therefore, even when the Ni / Co ratio in the battery waste differs from the Ni / Co ratio of the cathode active material to be regenerated, the cathode active material can be efficiently manufactured using Ni and Co recovered from the battery waste. Therefore, the cathode material regeneration method of this disclosure is very useful in the material recycling of lithium-ion secondary batteries.

[0074] The embodiments involved in this disclosure will be described in detail below, but it is not intended to limit this disclosure to the embodiments shown.

[0075] [Comparative Examples 1-5]

[0076] First, prepare the calcined black powder for the leaching sample according to the following steps. The sample will be coated with an aluminum (Al) foil containing a lithium nickel cobalt manganese composite oxide (LiNi). 0.6 Co 0.2 Mn 0.2 The positive electrode with an active material layer containing O2 was crushed. The crushed positive electrode was passed through a sieve with a pore size of 500 μm to prepare positive electrode powder. Separately, the negative electrode with a graphite-containing active material layer on copper foil was crushed. The crushed negative electrode was passed through a sieve with a pore size of 500 μm to prepare negative electrode powder. The obtained positive and negative electrode powders were mixed to obtain black powder. This black powder was calcined at 750 °C for 6 hours under a low-oxygen atmosphere to obtain calcined black powder with most of the metal reduced. 1 g of this calcined black powder was dissolved in acid and subjected to high-frequency inductively coupled plasma (ICP) emission spectroscopy analysis. Based on the analysis results, the amounts of Ni and Co in the calcined black powder were determined.

[0077] Next, ammonia solution with a mass concentration of 28% was mixed with ammonium sulfate ((NH4)2SO4) as a pH adjuster to prepare an ammonia solution. At this time, the concentration of ammonium sulfate was as shown in Table 1.

[0078] Here, the theoretical maximum concentrations of Ni and Co in the ammonia solution are defined as those obtained when Ni and Co in the calcined black powder are completely dissolved in the ammonia solution. Amounts of calcined black powder corresponding to the theoretical maximum concentrations shown in Table 1 were measured. The measured calcined black powder was added to the ammonia solution. The ammonia solution was stirred at 500 rpm for 6 hours while maintaining the temperature at 25°C to perform ammonia leaching. Then, solid-liquid separation was performed by filtration to obtain the leachate and solid residue.

[0079] [Examples 1-4]

[0080] After the measured calcined black powder was added to the ammonia solution, oxygen was immediately supplied to the ammonia solution at a rate of 0.4 mol / min. Otherwise, ammonia leaching was carried out in the same manner as described above.

[0081] [Leaching Rate Evaluation]

[0082] ICP-C was used to analyze the leachates obtained in each embodiment and comparative example, and the concentrations of Ni and Co were determined based on the analysis results. Based on this, the molar ratio of Ni to Co in the leachate was calculated.

[0083] [Table 1]

[0084]

[0085] In Comparative Examples 1-4, where oxygen bubbling was not performed during leaching, the Ni / Co ratio in the calcined black powder was approximately the same as that in the leachate. In Comparative Example 5, where oxygen bubbling was not performed during leaching, the amount of calcined black powder increased, while the Ni / Co ratio decreased slightly. This is believed to be due to insufficient leaching time.

[0086] On the other hand, in Examples 1-4 where oxygen bubbling was performed during leaching, the Ni / Co ratio in the leachate increased depending on the amount of ammonium sulfate. Therefore, it can be seen that the cathode material regeneration method according to this disclosure can recover Ni and Co from battery waste containing Ni and Co while adjusting the Ni / Co ratio to increase it. Furthermore, a comparison between Comparative Example 5 and Examples 2-4 shows that oxygen bubbling increases the leaching rate of Ni and Co.

[0087] The specific examples of this disclosure have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations to the specific examples illustrated above.

[0088] That is, the method for regenerating the cathode material disclosed herein is as follows [1] to [7].

[0089] [1] A regeneration method for a positive electrode material, the positive electrode material regeneration method comprising: a step of leaching Ni and Co from battery waste containing Ni and Co into the ammonia solution using an ammonia solution containing ammonia and ammonium sulfate, wherein oxygen is supplied to the ammonia solution during the leaching.

[0090] [2] According to the method of item [1], wherein the amount of ammonium sulfate is more than 5 molar times relative to the amount of Co in the battery waste.

[0091] [3] The method according to item [1] or [2], wherein the concentration of ammonia in the ammonia solution is 15% by mass or more, and the concentration of ammonium sulfate is 1.2 mol / L or more.

[0092] [4] The method according to any one of items [1] to [3], wherein, during the leaching, oxygen is supplied to the ammonia solution by bubbling.

[0093] [5] The method according to any one of items [1] to [4], wherein the battery waste contains Ni and Co in metallic form.

[0094] [6] The method according to any one of items [1] to [5] further comprises: a step of confirming the molar ratio of Ni to Co in the battery waste prior to the leaching step; and a step of selecting the amount of ammonium sulfate according to the desired molar ratio of Ni to Co.

[0095] [7] The method according to any one of items [1] to [6], wherein a Co compound is precipitated in the leaching process, the method further comprising the steps of dissolving the precipitated Co compound in water and separating it from the solid residue.

Claims

1. A regeneration method, which is a method for regenerating a positive electrode material, the method for regenerating the positive electrode material comprising: The process of leaching Ni and Co from battery waste containing Ni and Co into the ammonia solution using an aqueous solution containing ammonia and ammonium sulfate. In the leaching process, oxygen is supplied to the ammonia solution.

2. The method according to claim 1, wherein, The amount of ammonium sulfate is more than 5 molar times the amount of Co in the battery waste.

3. The method according to claim 1, wherein, In the ammonia solution, the concentration of ammonia is 15% by mass or more, and the concentration of ammonium sulfate is 1.2 mol / L or more.

4. The method according to claim 1, wherein, In the leaching process, oxygen is supplied to the ammonia solution by bubbling.

5. The method according to claim 1, wherein, The battery waste contains Ni and Co in metallic form.

6. The method of claim 1, further comprising: The process includes confirming the molar ratio of Ni to Co in the battery waste prior to the leaching process; and selecting the amount of ammonium sulfate based on the desired molar ratio of Ni to Co.

7. The method according to claim 1, wherein, In the leaching process, a Co compound precipitates out, and the method further includes the steps of dissolving the precipitated Co compound in water and separating it from the solid residue.

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