Method for regenerating positive electrode materials

Abstract

This invention provides a novel method for efficiently recovering Ni, Co, and Mn from battery waste containing Ni, Co, and Mn. [Solution] The method for recycling positive electrode material according to the present disclosure comprises a Mn leaching step in which ammonia leaching is performed on battery waste containing Ni, Co, and Mn, under conditions that the Mn leaching rate is 70% or more, and the Mn leaching rate is 65% or more of the sum of the Ni leaching rate, Co leaching rate, and Mn leaching rate, thereby leaching Mn into the aqueous phase; and a Ni,Co leaching step in which ammonia leaching is performed on the solid residue obtained in the Mn leaching step, under conditions that the Mn leaching rate is less than 1%, thereby leaching Ni and Co into the aqueous phase.

Description

Technical Field

[0001] The present disclosure relates to a method for recycling a positive electrode material.

Background Art

[0002] Lithium-ion secondary batteries are widely used in various fields as power sources for vehicle driving, portable power sources, etc. In recent years, from the perspective of SDGs, material recycling of used lithium-ion secondary batteries has been promoted. In lithium-ion secondary batteries, various metal elements are used, and for material recycling, development of technologies for separating metal elements contained in used lithium-ion secondary batteries has been carried out.

[0003] One of the materials often used as the positive electrode active material of lithium-ion secondary batteries is a so-called ternary positive electrode active material containing Ni, Co, and Mn, that is, a lithium nickel cobalt manganese composite oxide. Therefore, waste of lithium-ion secondary batteries often contains Ni, Co, and Mn. Thus, in Non-Patent Document 1, using a leaching agent containing ammonia and ammonium sulfate and sodium sulfite as a reducing agent, Ni and Co are selectively separated from Ni, Co, Mn, and Al contained in the positive electrode waste of used lithium-ion secondary batteries.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional technology described above, Mn is separated from Ni and Co. Therefore, when regenerating lithium nickel cobalt manganese composite oxide, there is a problem in that it is necessary to add Mn to the recovered Ni and Co.

[0006] Therefore, this disclosure aims to provide a novel method for efficiently recovering Ni, Co, and Mn from battery waste containing Ni, Co, and Mn. [Means for solving the problem]

[0007] The method for recycling positive electrode material according to this disclosure comprises a Mn leaching step in which ammonia leaching is performed on battery waste containing Ni, Co, and Mn, under conditions that the Mn leaching rate is 70% or more, and the Mn leaching rate is 65% or more of the sum of the Ni leaching rate, Co leaching rate, and Mn leaching rate, thereby leaching Mn into the aqueous phase; and a Ni,Co leaching step in which ammonia leaching is performed on the solid residue obtained in the Mn leaching step, under conditions that the Mn leaching rate is less than 1%, thereby leaching Ni and Co into the aqueous phase.

[0008] With this configuration, Ni, Co, and Mn can be efficiently recovered from battery waste containing Ni, Co, and Mn. [Brief explanation of the drawing]

[0009] [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]

[0010] 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.

[0011] 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.

[0012] As shown in Figure 1, the method for recycling positive electrode material according to this disclosure comprises a Mn leaching step S101, in which ammonia leaching is performed on battery waste containing Ni, Co, and Mn, under conditions where the Mn leaching rate is 70% or more, and the Mn leaching rate is 65% or more of the sum of the Ni leaching rates, Co leaching rates, and Mn leaching rates, to leach Mn into the aqueous phase; and a Ni,Co leaching step S102, in which ammonia leaching is performed on the solid residue obtained in the Mn leaching step, under conditions where the Mn leaching rate is less than 1%, to leach Ni and Co into the aqueous phase.

[0013] <Lithium-ion rechargeable battery> First, the method for regenerating positive electrode materials described herein relates to the material recycling of secondary batteries (particularly lithium-ion secondary batteries). First, a general example of the configuration of a lithium-ion secondary battery will be described. An example of the structure of a lithium-ion secondary battery is shown in Figures 2 and 3. Figure 2 is a schematic longitudinal cross-sectional view showing the internal structure of an example of a lithium-ion secondary battery. Figure 3 is a schematic exploded view showing the electrode body of the lithium-ion secondary battery shown in Figure 2. Figure 4 is a schematic cross-sectional view along the thickness direction of the positive electrode of the lithium-ion secondary battery shown in Figure 2. Note that the following description of lithium-ion secondary batteries is for the sake of understanding and does not in any way limit the method for regenerating positive electrode materials described herein.

[0014] As shown in Figure 2, the lithium-ion secondary battery 100 is a sealed battery in which a flat-shaped electrode body 20 and a non-aqueous electrolyte (not shown) are housed inside a battery case 30. As shown in Figure 2, the battery case 30 consists of an outer casing 32 that houses the electrode body 20 and a lid 34 that seals the opening of the outer casing 32. The outer casing 32 and the lid 34 are sealed by welding, such as by laser welding. For example, aluminum, aluminum alloy, or resin can be used as the material for the battery case 30.

[0015] In the illustrated example, the battery case 30 is rectangular. However, the shape of the battery case 30 is not limited to this, and it may be cylindrical, for example. Alternatively, the battery case 30 may be a laminated case having a gas barrier layer, such as an aluminum layer, and a sealant layer containing a thermoplastic resin.

[0016] The battery case 30 is equipped with a positive electrode terminal 42 and a negative electrode terminal 44 for external connection. The battery case 30 is also provided with a safety valve 36 that is set to release the internal pressure if the internal pressure of the battery case 30 rises above a predetermined level. The battery case 30 is provided with an inlet (not shown) for injecting a non-aqueous electrolyte. The positive electrode terminal 42 is electrically connected to the positive electrode current collector plate 42a. The negative electrode terminal 44 is electrically connected to the negative electrode current collector plate 44a.

[0017] 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 stacked electrode body in which a plurality of positive electrodes and a plurality of negative electrodes are alternately stacked via a separator.

[0018] 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 collecting plate 42a is joined to the positive electrode active material layer non-formation portion 52a.

[0019] 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. The positive electrode active material is typically a lithium nickel cobalt manganese-based composite oxide. 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.

[0020] The content of the positive electrode active material in the positive electrode active material layer 54 is preferably 70% by mass or more, and 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, and 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, and more preferably 0.5% by mass or more and 10% by mass or less.

[0021] As shown in FIG. 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 (here, both sides) of the negative electrode current collector 62. The negative electrode sheet 60 has a negative electrode active material layer non-formation portion 62a which is a portion where the negative electrode current collector 62 is exposed without the negative electrode active material layer 64 being formed. The negative electrode current collector plate 44a is joined to the negative electrode active material layer non-formation portion 62a.

[0022] Examples of the negative electrode current collector 62 constituting the negative electrode sheet 60 include copper foil. The negative electrode active material layer 64 contains a negative electrode active material. Examples of the negative electrode active material include carbon-based negative electrode active materials (e.g., graphite, hard carbon, soft carbon, etc.), silicon-based negative electrode active materials (e.g., silicon, silicon oxide, etc.). The negative electrode active material layer 64 may contain a binder (e.g., styrene butadiene rubber (SBR), etc.), a thickening agent, etc. (e.g., carboxymethyl cellulose (CMC), etc.).

[0023] The content of graphite 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 content of the binder 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 content of the thickening agent 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.

[0024] Examples of the separator 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.

[0025] The non-aqueous electrolyte typically contains a non-aqueous solvent and a supporting salt (or 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 a gas generating agent, a film forming agent, etc. In this embodiment, a non-aqueous electrolyte is used as the electrolyte, but the electrolyte may be a solid electrolyte.

[0026] The lithium ion secondary battery 100 is used, for example, for in-vehicle applications (i.e., as a driving power source for vehicles such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc.) and power supply applications for electronic devices.

[0027] As described above, in the positive electrode of the lithium ion secondary battery, Li, Ni, Co, and Mn are typically used as the constituent metal elements of the lithium nickel cobalt manganese-based composite oxide, which is the positive electrode active material. Al is generally used for the positive electrode current collector. Cu is generally used for the negative electrode current collector. In addition, in the lithium ion secondary battery, Li is used in the non-aqueous electrolyte. Also, Al can be used for the battery case.

[0028] The Mn leaching process S101 uses battery waste containing Ni, Co, and Mn. The Ni, Co, and Mn contained in the battery waste typically originate from lithium nickel cobalt manganese composite oxide used as a positive electrode active material. However, the Ni, Co, and Mn contained in the battery waste are not limited to these. 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 have undergone some kind of treatment (e.g., roasting).

[0029] Specific examples of battery waste include black mass from used lithium-ion secondary batteries (especially black mass obtained by crushing and roasting used lithium-ion secondary batteries), positive electrode waste extracted from used lithium-ion secondary batteries, electrode material waste extracted from used lithium-ion secondary batteries, positive electrode waste deemed to be defective, electrode material waste deemed to be defective, and positive electrode active material deemed to be defective.

[0030] It is more preferable that the waste contains Ni and Co as metals and Mn as a divalent oxide. From this viewpoint, it is preferable that the waste is reductively roasted. Preferably, the waste is black mass obtained by crushing and reductively 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] Battery waste may further contain elements other than Ni, Co, and Mn (especially metallic elements). For example, in addition to Ni, Co, and Mn, battery waste may further contain Li, Al, etc. Battery waste may further contain transition metal elements other than Ni, Co, and Mn. Battery waste may also further contain Cu. In particular, if the battery waste is lithium-ion secondary battery or electrode waste, the battery waste generally further contains Cu derived from the negative electrode current collector.

[0033] In the Mn leaching process S101, ammonia leaching is performed. The leaching agent used for ammonia leaching is preferably an aqueous ammonia solution containing water, ammonia (NH3), and a pH adjusting agent such as ammonium sulfate ((NH4)2SO4) or ammonium carbonate ((NH4)2CO3) (preferably ammonium sulfate).

[0034] In an aqueous ammonia solution, the concentration of ammonia is not particularly limited, but a higher concentration results in higher leaching ability. Therefore, the concentration of ammonia in the aqueous 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. 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 ability and ease of handling, an ammonia concentration of 15% by mass to 25% by mass is particularly preferred.

[0035] Ammonium sulfate and ammonium carbonate act as pH adjusters. The amount of pH adjuster in the ammonia aqueous solution is such that the pH of the ammonia aqueous solution becomes, for example, 9 to 12, preferably 10 to 11.

[0036] The ammonia aqueous solution may contain only water, ammonia, and a pH adjuster. The ammonia aqueous solution may further contain components other than water, ammonia, and a pH adjuster, within limits that do not impair the effects of the present disclosure (for example, at concentrations of less than 10% by mass, 5% by mass or less, or 1% by mass or less).

[0037] The amount of ammonia solution used is not particularly limited and may be similar to the amount used in known ammonia leaching methods. For example, the amount of ammonia solution used should be enough to completely immerse the battery waste.

[0038] The Mn leaching process S101 can be carried out, for example, as follows: First, a container is prepared. The container may be a known container used for ammonia leaching. If necessary, heating means such as a heater, temperature measuring means such as a thermometer or temperature sensor, stirring means such as a stirring blade or magnetic stirring bar are attached to the container.

[0039] The battery waste and ammonia aqueous solution are placed in a container. There is no particular order in which these are added; they may be added either first or simultaneously. Next, the leaching conditions in the Mn leaching process S101 will be described.

[0040] The leaching conditions in the Mn leaching process S101 are such that the Mn leaching rate is 70% or more, and the Mn leaching rate is 65% or more of the sum of the Ni leaching rates, Co leaching rates, and Mn leaching rates.

[0041] When ammonia leaching is performed on battery waste containing Ni, Co, and Mn, initially Mn leaches preferentially, but subsequently Mn precipitates from the leachate. This is thought to be due to the following reasons: Initially, Mn dissolves kinetically faster, while Ni and Co also dissolve gradually. Over time, the ammine complexes of Ni and Co become more stable than Mn, so the ammonium ions used to dissolve Mn are used to dissolve Ni and Co (i.e., to form ammine complexes), causing Mn to precipitate.

[0042] Therefore, before Mn precipitates, it is possible to preferentially leach Mn into the aqueous phase. According to the inventor's actual investigations, as shown in the results of the test examples described later, it was found that when ammonia leaching is performed at a low temperature for a predetermined time, it is possible to leach Mn into the aqueous phase with a high leaching rate and relatively high selectivity before Mn precipitates.

[0043] Therefore, the leaching temperature in the Mn leaching process S101 is preferably greater than 0°C and 45°C or less, and more preferably between room temperature (i.e., 25±10°C) and 45°C. In other words, the leaching temperature is more preferably between 15°C and 45°C.

[0044] Even if the leaching temperature exceeds 45°C, shortening the leaching time can result in a Mn leaching rate of 70% or more, and this Mn leaching rate may be 65% or more of the sum of the Ni leaching rates, Co leaching rates, and Mn leaching rates. However, from the viewpoint of energy saving and ease of controlling leaching conditions, the leaching temperature is preferably within the range described above.

[0045] The leaching time can be determined appropriately depending on the leaching temperature. The higher the leaching temperature, the shorter the leaching time will be.

[0046] As an indicator of leaching temperature (°C) and leaching time (h), if the product of the leaching temperature (°C) and leaching time (h) is in the range of 70 to 250 (especially 80 to 230), the above leaching conditions are likely to be met.

[0047] From an energy-saving standpoint, the Mn leaching process S101 is preferably carried out at 25±10℃ (i.e., room temperature) for 4 to 8 hours, and more preferably at 25±10℃ (i.e., room temperature) for 4 to 6 hours.

[0048] 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, 1000 rpm or lower, or 800 rpm or lower.

[0049] By performing ammonia leaching with reference to the above, Mn can be leached into the aqueous phase. That is, the Mn leaching step S101 can be carried out. The ammonia leaching can be terminated by performing solid-liquid separation such as filtration of the filtrate. By this solid-liquid separation, a leachate (that is, an aqueous phase in which Mn has been leached) and a solid residue can be obtained.

[0050] The Mn leaching step S101 may be carried out only once or may be carried out multiple times. By carrying out the Mn leaching step S101 multiple times, more Mn can be recovered. When the Mn leaching step S101 is carried out twice, first, Mn is leached by ammonia leaching under the above conditions, then solid-liquid separation is performed, and ammonia leaching is carried out on the obtained solid residue under the above conditions using a new aqueous ammonia solution. Further, by repeating solid-liquid separation and performing ammonia leaching on the obtained solid residue under the above conditions using a new aqueous ammonia solution, the Mn leaching step S101 can be carried out three or more times.

[0051] <Ni,Co Leaching Step S102> In the Ni,Co leaching step S102, ammonia leaching is carried out on the solid residue obtained in the Mn leaching step S101 under the condition that the leaching rate of Mn is less than 1% to leach Ni and Co into the aqueous phase.

[0052] In the Ni,Co leaching step S102 as well, ammonia leaching is carried out. As the leaching agent, an aqueous ammonia solution containing water, ammonia (NH3), and a pH adjuster (e.g., ammonium sulfate, ammonium carbonate, etc., preferably ammonium sulfate) is preferred.

[0053] Regarding the specific content of this aqueous ammonia solution (e.g., ammonia concentration, pH, etc.), it is the same as the aqueous ammonia solution used in the Mn leaching step S101. The composition of the aqueous ammonia solution used in the Mn leaching step S101 may be the same as or different from the composition of the aqueous ammonia solution used in the Ni,Co leaching step S102, but from the viewpoints of ease of implementation and ease of recycling, it is preferably the same.

[0054] The amount of aqueous ammonia solution used is not particularly limited and may be similar to the amount used in known ammonia leaching methods. For example, the amount of aqueous ammonia solution used should be enough to completely immerse the solid residue.

[0055] As described above, when ammonia leaching is performed on battery waste containing Ni, Co, and Mn, initially Mn leaches preferentially, but then Mn precipitates. Therefore, at this time, the leaching rates of Ni and Co become high, and the leaching rate of Mn becomes low. Furthermore, a higher leaching temperature results in higher leaching rates of Ni and Co, which in turn leads to faster Mn precipitation and a lower Mn leaching rate.

[0056] Therefore, the leaching temperature in the Ni,Co leaching process S102 is preferably 60°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher. The leaching temperature is below the boiling point of water (i.e., below 100°C).

[0057] Even if the leaching temperature is below 60°C, the Mn leaching rate can be reduced to less than 1% by increasing the leaching time. However, from the viewpoint of production efficiency, the leaching temperature is preferably within the range mentioned above.

[0058] The leaching time can be determined according to the leaching temperature. It is preferable to select a longer leaching time when the leaching temperature is low. Furthermore, longer leaching times tend to result in higher leaching rates of Ni and Co.

[0059] Therefore, the Ni,Co leaching process S102 is preferably carried out at a temperature of 80°C or higher for 2 hours or more (more preferably 6 hours or more, particularly preferably 10 hours or more). Alternatively, it is preferably carried out at a temperature of 70°C or higher for 4 hours or more (more preferably 9 hours or more). Alternatively, the Ni,Co leaching process S102 is preferably carried out at a temperature of 60°C or higher for 6 hours or more (more preferably 12 hours or more). The leaching time for the Ni,Co leaching process S102 may be 24 hours or less, or 48 hours or less, at any of these temperatures.

[0060] 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, 1000 rpm or lower, or 800 rpm or lower.

[0061] In ammonia leaching, Ni and Co leach out. Under the above conditions, it is preferable that the leaching rates of Ni and Co are 40% or more, and more preferable that they are 50% or more.

[0062] By performing ammonia leaching based on the above, Ni and Co can be leached into the aqueous phase. That is, the Ni, Co leaching process S102 can be carried out. Ammonia leaching can be terminated by solid-liquid separation of the filtrate, etc. This solid-liquid separation yields the leached liquid (i.e., the aqueous phase in which Ni and Co have leached) and the solid residue.

[0063] The Ni,Co leaching process S102 may be performed only once or multiple times. Performing the Ni,Co leaching process S102 multiple times allows for the recovery of more Ni and Co. When performing the Ni,Co leaching process S102 twice, Ni and Co are leached from the solid residue obtained in the Mn leaching process S101 using ammonia under the above conditions, followed by solid-liquid separation. The resulting solid residue is then subjected to ammonia leaching using a fresh aqueous ammonia solution under the above conditions. Furthermore, by repeating the process of solid-liquid separation and ammonia leaching using a fresh aqueous ammonia solution under the above conditions, the Ni,Co leaching process S102 can be performed three or more times.

[0064] As described above, all of Ni, Co, and Mn can be extracted into the aqueous phase from battery waste containing Ni, Co, and Mn. The Ni, Co, and Mn extracted into the aqueous phase can be recovered according to known methods. Here, sulfates are generally used as the Ni, Co, and Mn sources in lithium nickel cobalt manganese composite oxides. Therefore, it is advantageous to recover the Ni, Co, and Mn extracted into the aqueous phase by converting them into nickel sulfate, cobalt sulfate, and manganese sulfate according to known methods (for example, by volatilizing ammonia from the aqueous phase and adding sulfuric acid to the aqueous phase). In this case, ammonium sulfate used in the aqueous ammonia solution is SO4. 2- It can be a source and does not become an impurity, which is advantageous.

[0065] According to the cathode material regeneration method of this disclosure, Ni, Co, and Mn can be efficiently recovered from battery waste containing Ni, Co, and Mn through two-stage ammonia leaching under different conditions. Therefore, the cathode material regeneration method of this disclosure can be easily implemented. Furthermore, since Ni, Co, and Mn derived from lithium nickel cobalt manganese composite oxide can be recovered by ammonia leaching, there is no need to add new Mn when regenerating lithium nickel cobalt manganese composite oxide using the recovered metal elements. Therefore, the cathode material regeneration method of this disclosure is extremely useful in the material recycling of lithium-ion secondary batteries.

[0066] 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.

[0067] [Test Examples 1-15] 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 0.2A 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.

[0068] Next, an aqueous ammonia solution was prepared by mixing 28% by mass aqueous ammonia with ammonium sulfate ((NH4)2SO4) as a pH adjuster.

[0069] The above-mentioned roasted black muss was added to the ammonia aqueous solution. Next, while maintaining the temperature of the ammonia aqueous solution at the temperature shown in Table 1, the mixture was stirred at a stirring speed of 500 rpm for the time shown in Table 1 to allow ammonia leaching. After that, solid-liquid separation was performed by filtration to obtain the leachate and solid residue.

[0070] [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 Ni, Co, and Mn in the roasted black mass were determined. The amounts of these metals correspond to the initial amounts before ammonia leaching.

[0071] Next, ICP emission spectroscopy was performed on the leachate obtained from each test example to determine the amounts of Ni, Co, and Mn in the leachate. The leaching rates (%) of Ni, Co, and Mn were determined from the ratio (percentage) of the amounts of these metals in the leachate to the initial amounts of these metals in the roasted black mass. The ratio (%) of the leaching rate of Mn to the sum of the leaching rates of Ni, Co, and Mn was also calculated. The results are shown in Table 1.

[0072] [Table 1]

[0073] From the results in Table 1, it can be seen that when the leaching temperature is low and the leaching time is short, the leaching rate of Mn is high, and when the leaching temperature is high and the leaching time is long, the leaching rate of Mn is low and the leaching rates of Ni and Co are high.

[0074] Therefore, it is clear that by a two-stage leaching method that involves performing a Mn leaching step in which ammonia leaching is carried out on battery waste containing Ni, Co, and Mn, under conditions where the Mn leaching rate is 70% or more and the Mn leaching rate is 65% or more of the sum of the Ni leaching rates, Co leaching rates and Mn leaching rates, and then performing a Ni,Co leaching step in which ammonia leaching is carried out on the solid residue obtained in the Mn leaching step under conditions where the Mn leaching rate is less than 1%, thereby leaching Ni and Co into the aqueous phase, it is possible to efficiently recover Ni, Co, and Mn from battery waste containing Ni, Co, and Mn. Thus, it is clear that by the cathode material recycling method of this disclosure, it is possible to efficiently recover Ni, Co, and Mn from battery waste containing Ni, Co, and Mn.

[0075] Test examples 7, 8, 11, 12, and 13 satisfy the above leaching conditions for the Mn leaching process. Test examples 1, 2, 3, and 6 satisfy the above leaching conditions for the Ni,Co leaching process.

[0076] 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 technologies described in the claims include various modifications and changes to the specific examples described above.

[0077] In other words, the method for regenerating the cathode material of this disclosure is as described in the following sections [1] to [7]. [1] A Mn leaching process in which ammonia leaching is performed on battery waste containing Ni, Co and Mn, under conditions that the Mn leaching rate is 70% or more, and the Mn leaching rate is 65% or more of the sum of the Ni leaching rate, the Co leaching rate and the Mn leaching rate, to leach Mn into the aqueous phase, and Ni,Co leaching step: In the solid residue obtained in the above Mn leaching step, ammonia leaching is performed under conditions where the Mn leaching rate is less than 1% to leach Ni and Co into the aqueous phase. A method for regenerating positive electrode material that includes the following features. [2] The method according to item [1], wherein the ammonia leaching in the Mn leaching step and the Ni,Co leaching step is carried out using an aqueous ammonia solution containing water, ammonia, and ammonium sulfate. [3] The method according to item [1] or [2], wherein the Mn leaching step is performed multiple times. [4] The method according to any one of items [1] to [3], wherein the Ni,Co leaching step is performed multiple times. [5] The method according to any one of items [1] to [4], wherein the leaching temperature in the Mn leaching step is greater than 0°C and 45°C or less, and the leaching temperature in the Ni,Co leaching step is 60°C or more and less than 100°C. [6] The method according to any one of items [1] to [5], wherein the Mn leaching step is carried out at a leaching temperature of 25 ± 10°C for 4 to 8 hours. [7] The method according to any one of items [1] to [6], wherein the Ni,Co leaching step S102 is carried out at a leaching temperature of 80°C or higher for 2 hours or more. [Explanation of Symbols]

[0078] 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. A Mn leaching process is performed on battery waste containing Ni, Co, and Mn, under the condition that the Mn leaching rate is 70% or more, and the Mn leaching rate is 65% or more of the sum of the Ni leaching rate, Co leaching rate, and Mn leaching rate, to leach Mn into the aqueous phase, and Ni, Co leaching step: In the solid residue obtained in the above Mn leaching step, ammonia leaching is performed under conditions where the Mn leaching rate is less than 1% to leach Ni and Co into the aqueous phase. A method for regenerating positive electrode material that includes the following features.

2. The method according to claim 1, wherein the ammonia leaching in the Mn leaching step and the Ni,Co leaching step is carried out using an aqueous ammonia solution containing water, ammonia, and ammonium sulfate.

3. The method according to claim 1, wherein the Mn leaching step is performed multiple times.

4. The method according to claim 1, wherein the Ni,Co leaching step is performed multiple times.

5. The method according to claim 1, wherein the leaching temperature in the Mn leaching step is greater than 0°C and 45°C or less, and the leaching temperature in the Ni,Co leaching step is 60°C or more and less than 100°C.

6. The method according to claim 1, wherein the Mn leaching step is performed at a leaching temperature of 25 ± 10°C for 4 to 8 hours.

7. The method according to claim 1, wherein the Ni,Co leaching step S102 is carried out at a leaching temperature of 80°C or higher for 2 hours or more.

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