Regenerated positive electrode material precursor, method for producing regenerated positive electrode material, and method for using regenerated positive electrode material

Abstract

A method for producing a regenerated positive electrode material precursor, which is a method for producing a regenerated positive electrode material precursor from a lithium ion secondary battery that is an object to be treated. A lithium ion secondary battery as the object to be treated is subjected to a heat treatment step, a crushing step, a classification screening step, a magnetic separation step, an acid leaching step, an iron removal step, an ion exchange step, an alkali treatment step, and a cleaning step.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a regenerated cathode material precursor and a regenerated cathode material from recycled materials recovered from lithium-ion secondary batteries as the object of treatment, and a method for using the regenerated cathode material. Background Technology

[0002] The applications of lithium-ion rechargeable batteries are rapidly expanding from the electronics to the automotive sectors. Particularly in the automotive sector, with the development of plug-in hybrid electric vehicles (PHEVs) and / or battery electric vehicles (BEVs), a surge in demand for larger batteries due to the increasing capacity of individual cells is anticipated. This surge in demand is also driven by strong requirements for CO2 emission reduction in the transportation industry. As demand for lithium-ion rechargeable batteries expands, the amount of lithium-ion rechargeable batteries reaching the end of their product lifespan is also increasing. Hereinafter, lithium-ion rechargeable batteries will also be referred to as "LIBs".

[0003] On the other hand, LIBs use expensive metal materials as their cathode materials, so reusing metal materials from LIBs that have reached the end of their product life is an important industrial issue.

[0004] For example, in Patent Document 1, impurities are removed from waste batteries, waste cathode materials, or mixtures thereof containing at least two metal groups selected from Co, Ni, and Mn, and the metal groups are recovered in the form of a mixture of metal salts. Furthermore, Patent Document 1 proposes using the recovered mixture of metal salts to manufacture cathode materials.

[0005] In addition, for example, Patent Document 2 filed by the applicant disclosed a recycled cathode material containing at least one of iron, copper, and aluminum in a specified amount.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent No. 5847742

[0009] Patent Document 2: Japanese Patent No. 7176707 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] To reuse metal materials from waste LIBs that have reached the end of their product lifespan, it is desirable to minimize the environmental impact and / or reduce the cost of reuse. However, methods such as those described in Patent Document 1 often employ complex separation processes and expensive extractants, raising concerns about the significant environmental burden and / or high costs associated with reuse.

[0012] To cite one example, the battery cells of LIBs used in automotive applications such as PHEVs and / or BEVs require robust encapsulation capable of withstanding severe mechanical shocks, immersion in all types of liquids, fire, and high temperatures. The LIB stack within the battery cell is typically disassembled into internal components (positive electrode, negative electrode, separator) and an outer casing. The method described in Patent Document 1 requires disassembling the aforementioned battery cell. Therefore, the method described in Patent Document 1 requires safety measures. Furthermore, the robust encapsulation of the LIB stack complicates the operation of mechanically removing the positive electrode active material from the battery cell. This situation becomes even more significant if the demand for such large batteries increases dramatically and the volume of waste LIBs increases.

[0013] Compared to the method described in Patent Document 1, which requires safety countermeasures for dismantling LIB battery cells, the method described in Patent Document 2 involves heat treatment of each waste LIB battery cell as a countermeasure for efficiently, automatically, and safely removing the positive electrode active material from the waste LIB battery cells. Through this heat treatment, the LIB laminate within the battery cell is rendered harmless both electrically and chemically, significantly reducing the risk.

[0014] By employing this method, positive electrode active materials can be extracted from LIB stacks in a safe and efficient manner without complex mechanical decomposition, using an electrochemically harmless method.

[0015] Furthermore, the recycled cathode material described in Patent Document 2, by containing at least one of aluminum, copper, and iron in specified amounts, implies that it can maintain a high energy density and output density even during charge-discharge cycles, thus providing substantial added value in terms of battery performance within the recycled LIB. However, the inventors conducted research and found that, depending on the contents of the recycled waste LIB, by producing a recycled cathode material with low aluminum, copper, and iron content, it is sometimes possible to improve the characteristics of batteries using recycled cathode materials.

[0016] The present invention was made under the above-described conditions, and the problem it aims to solve relates to a method for manufacturing a recycled cathode material precursor from a LIB as the object to be processed, a method for manufacturing a recycled cathode material from the recycled cathode material precursor, and a method for using the recycled cathode material to perform an activation process of assembling a LIB using the recycled cathode material and charging and discharging it. The recycled cathode material precursor has low environmental impact and low recycling cost, high safety, and low content of aluminum, copper, and iron.

[0017] Solution for solving the problem

[0018] The first invention that solves the above-mentioned problem is a method for manufacturing a recycled cathode material precursor, which is a method for manufacturing a recycled cathode material precursor from a lithium-ion secondary battery as the object to be processed, and the method includes the following steps:

[0019] The heat treatment process involves heating the lithium-ion secondary battery, which is the object to be treated, to obtain a heat-treated product.

[0020] The crushing process involves crushing the heat-treated material to obtain crushed material.

[0021] The grading and screening process involves grading and screening the above-mentioned crushed material to obtain fine-particle products;

[0022] The acid leaching process involves leaching the above-mentioned fine-particle product with acid to obtain an acid leachate.

[0023] In the iron removal process, an oxidant and an alkali are added to the above acid leaching solution to obtain the iron-removed solution.

[0024] The ion exchange process involves contacting the iron-removed solution with a chelating resin to obtain the ion-exchanged solution.

[0025] In the alkali treatment process, alkali is added to the above-mentioned ion-exchange post-liquid to generate a precipitate; and

[0026] The cleaning process involves washing the aforementioned precipitates with water to obtain the recycled cathode material precursor.

[0027] The second invention is a method for manufacturing the recycled cathode material precursor as described in the first invention, wherein...

[0028] After the above-mentioned grading and screening process, a magnetic separation process is performed to obtain magnetically adsorbed material by magnetic separation of the above-mentioned fine-particle product.

[0029] The third invention is a method for manufacturing the recycled cathode material precursor as described in the first invention, wherein...

[0030] In the above acid leaching process, sulfuric acid is used for acid leaching.

[0031] The fourth invention is a method for manufacturing the recycled cathode material precursor as described in the first invention, wherein...

[0032] In the above-mentioned iron removal process, hydrogen peroxide aqueous solution is used as an oxidant, and the oxidation-reduction potential of the above-mentioned acid leaching solution is set to 500~750mV (Ag / AgCl) to carry out the iron removal process.

[0033] The fifth invention is a method for manufacturing the recycled cathode material precursor as described in the first invention, wherein...

[0034] In the above-mentioned ion exchange process, an aminomethylphosphonic acid-based chelating resin is used as the chelating resin to remove aluminum ions.

[0035] The sixth invention is a method for manufacturing the recycled cathode material precursor as described in the first invention, wherein...

[0036] An analytical step is performed to quantitatively analyze the metal elements contained in the ion-exchange solution. If there is a difference between the results of the quantitative analysis of the metal elements contained in the ion-exchange solution and the metal composition of the target regenerated cathode material precursor, a preparation step is performed to prepare the ion-exchange solution.

[0037] The seventh invention is a method for manufacturing the recycled cathode material precursor as described in the first invention, wherein...

[0038] An analytical step is performed to quantitatively analyze the metal elements contained in the ion-exchange solution. If there is a difference between the results of the quantitative analysis of the metal elements contained in the ion-exchange solution and the metal composition of the target regenerated cathode material precursor, an addition step is performed to add metal elements that are insufficient compared to the metal composition of the target regenerated cathode material precursor.

[0039] The eighth invention is a method for manufacturing the recycled cathode material precursor as described in the sixth invention, wherein...

[0040] The aluminum content in the prepared ion exchange solution is less than 100 mg / L, the copper content is less than 1 mg / L, and the iron content is less than 1 mg / L.

[0041] The ninth invention is a method for manufacturing the recycled cathode material precursor described in the seventh invention, wherein...

[0042] The aluminum content in the ion exchange solution containing the above-mentioned metal elements is less than 100 mg / L, the copper content is less than 1 mg / L, and the iron content is less than 1 mg / L.

[0043] The tenth invention is a method for manufacturing a recycled cathode material, wherein...

[0044] A regenerated cathode material is obtained by adding a prescribed metal compound to a regenerated cathode material precursor manufactured by the manufacturing method of any one of the inventions 1 to 9, followed by calcination.

[0045] The 11th invention is a method for manufacturing the recycled positive electrode material as described in the 10th invention, wherein...

[0046] The aforementioned metal compound is selected from one or more of lithium compounds, nickel compounds, cobalt compounds, and manganese compounds.

[0047] The 12th invention is a method for using a recycled cathode material, which includes the following steps:

[0048] Assembly process, assembling a lithium-ion secondary battery having the recycled positive electrode material described in the 10th invention; and

[0049] The activation process involves charging and discharging the lithium-ion secondary batteries assembled in the above assembly process.

[0050] The effects of the invention

[0051] According to the present invention, it is possible to manufacture highly safe recycled cathode material precursors and recycled cathode materials from LIBs, which are the objects of processing, with less environmental impact and low recycling costs. Attached Figure Description

[0052] Figure 1 This is a flowchart illustrating the manufacturing process of the recycled cathode material precursor and the recycled cathode material of the present invention.

[0053] Figure 2 This is a schematic diagram of an example of a coin cell type lithium-ion secondary battery used in the embodiments. Detailed Implementation

[0054] The following is a reference to the manufacturing process diagram. Figure 1 The precursor for the recycled cathode material and the method for manufacturing the recycled cathode material, which are used as embodiments of the present invention, will be described. "~" indicates a value above and below a specified value. It should be noted that this embodiment will be described in the following order.

[0055] [1. Relevant insights into the invention described in the manufacturing method of this invention]

[0056] [2. Lithium-ion secondary batteries as the object of processing]

[0057] [3. Manufacturing method of recycled cathode material precursor]

[0058] (3-1. Heat treatment process)

[0059] (3-2. Crushing process)

[0060] (3-3. Grading and screening process)

[0061] (3-4. Magnetic separation process)

[0062] (3-5. Acid leaching process)

[0063] (3-6. Iron removal process)

[0064] (3-7. Ion exchange process)

[0065] (3-8. Alkali treatment process)

[0066] (3-9. Cleaning process)

[0067] [4. Manufacturing method of recycled cathode material]

[0068] (4-1. Lithium source, etc. addition process)

[0069] (4-2. Crushing and mixing process)

[0070] (4-3. Calcination process)

[0071] (4-4. Crushing process)

[0072] [5. How to use regenerated cathode materials]

[0073] (5-1. Regenerated positive electrode)

[0074] (5-2. Lithium-ion secondary battery using the recycled cathode material of the present invention)

[0075] [6. Effects of the Invention]

[0076] [1. Relevant insights into the invention described in the manufacturing method of this invention]

[0077] In order to solve the problem presented in this invention, the inventors conducted in-depth research. As a result, the following method was conceived.

[0078] As a measure to efficiently, automatically, and safely remove the positive electrode active material from waste LIB battery cells, each waste LIB battery cell undergoes heat treatment. This heat treatment renders the LIB stack within the battery cell electrically and chemically harmless, significantly reducing risk.

[0079] By mechanically / magnetically recovering the positive electrode active material from the heat-treated LIB laminate, the content of elements such as Ni, Co, and Mn in the thermal decomposition residue can be increased. The thermal decomposition residue with concentrated Ni, Co, and Mn can be converted into a mixture of Ni, Co, and Mn hydroxides (e.g., precursors of the positive electrode active material).

[0080] This method enables the extraction of positive electrode active materials from LIB stacks in a safe and efficient manner, without complex mechanical decomposition, using a harmless electrochemical process. These advantages allow for the automation of waste LIB treatment. Hereinafter, LIB stacks may be referred to simply as LIBs.

[0081] [2. Lithium-ion secondary batteries as the object of processing]

[0082] There are no particular restrictions on the LIBs that are to be processed; they can be selected appropriately according to the purpose. For example, LIBs that are defective products generated during the LIB manufacturing process can be listed; LIBs that are discarded due to equipment malfunction or equipment lifespan; and used LIBs that are discarded due to their lifespan.

[0083] A lithium-ion battery (LIB) is a secondary battery that is charged and / or discharged by the movement of lithium ions between the positive and negative electrodes. Examples of secondary batteries include a positive electrode, a negative electrode, a separator, an electrolyte (an electrolyte containing an organic solvent or a solid electrolyte), and an outer packaging container as the battery casing.

[0084] There are no particular restrictions on the shape, structure, size, and material of the LIB being processed; it can be chosen appropriately according to the purpose. Examples of LIB shapes include laminated, cylindrical, button-shaped, coin-shaped, square, and flat types.

[0085] As for the positive electrode, there are no particular restrictions as long as the positive current collector contains positive electrode material; it can be appropriately selected according to the purpose. There are also no particular restrictions on the shape of the positive electrode; it can be appropriately selected according to the purpose, for example, plate-shaped, sheet-shaped, etc.

[0086] Regarding the shape, structure, size, and material of the positive current collector, there are no particular restrictions; it can be appropriately selected according to the purpose. Examples of shapes for positive current collectors include foil. Examples of materials for positive current collectors include stainless steel, nickel, aluminum, copper, titanium, and tantalum. Among these, aluminum is the most commonly used.

[0087] The constituent components of the positive electrode material can be appropriately selected according to the purpose. For example, positive electrode materials that contain at least a positive electrode active material containing rare and valuable substances, and which also contain conductive agents and binding resins as needed, can be listed. There are no particular restrictions on the rare and valuable substances, and they can be appropriately selected according to the purpose. Cobalt, nickel and manganese (sometimes referred to as "NCM" in this invention, and sometimes cobalt, nickel and aluminum are referred to as "NCA") are often used.

[0088] As a positive electrode active material, any lithium transition metal oxide (LTMO) can be used. Examples of LTMOs include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), and lithium cobalt nickel oxide (LiCoO2). 1 / 2 Ni 1 / 2 O2), ternary materials (LiNi based on NCM) x Co y Mn z O2)(x+y+z=1 and x, y, z are respectively greater than 0 and less than 1) (hereinafter, even if it contains Li, it is also called NCM), or complexes of any combination thereof, etc.

[0089] Among them, the above-mentioned NCM contains equal amounts (x=y=z=1 / 3) of Ni, Co, and Mn in LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 When used as a cathode material in LIBs, O2 exhibits excellent Li ion extraction / intercalation characteristics, making it suitable for automotive applications.

[0090] On the other hand, Ni in ternary LTMO is useful because it provides high specific capacity in low charge / discharge current density battery cells through slow Li-ion extraction / intercalation. (LiNi) 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2 is also highly anticipated as the positive electrode active material for automotive LIBs such as BEVs and / or PHEVs.

[0091] As a conductive agent, there are no particular restrictions, and it can be appropriately selected according to the purpose. Examples include carbon black, graphite, carbon fiber, and metal carbides.

[0092] There are no particular restrictions on the type of adhesive resin; it can be selected appropriately according to the purpose. Examples include homopolymers or copolymers of vinylidene fluoride, tetrafluoroethylene, acrylonitrile, ethylene oxide, styrene-butadiene rubber, etc.

[0093] As for the negative electrode, there are no particular restrictions as long as the negative electrode current collector contains negative electrode material; it can be appropriately selected according to the purpose. There are also no particular restrictions on the shape of the negative electrode; it can be appropriately selected according to the purpose, for example, flat plates, sheet-like shapes, etc.

[0094] Regarding the shape, structure, size, and material of the negative current collector, there are no particular restrictions; it can be appropriately selected according to the purpose. Examples of shapes for negative current collectors include foil. Examples of materials for negative current collectors include stainless steel, nickel, aluminum, copper, titanium, and tantalum. Among these, copper is the most commonly used.

[0095] There are no particular restrictions on anode materials; they can be selected appropriately according to the purpose. Examples include carbon materials such as graphite and hard carbon, titanates, silicon, and their respective composites.

[0096] It should be noted that the positive and negative current collectors have a laminated structure. As a laminate, there are no particular restrictions, and it can be selected appropriately according to the purpose.

[0097] [3. Manufacturing method of recycled cathode material precursor]

[0098] (3-1. Heat treatment process)

[0099] like Figure 1 As shown, firstly, a heat treatment process is performed on the LIB, which is the object of the treatment. There are no particular limitations on the heat treatment temperature, as long as it is above the melting point of the lower-melting-point current collector (between the positive and negative electrodes) and below the melting point of the higher-melting-point current collector. It can be appropriately selected according to the purpose, preferably 670°C or higher, more preferably 670°C or higher and 1100°C or lower, further preferably 700°C or higher, and particularly preferably 700°C or higher and 900°C or lower. If the heat treatment temperature is 670°C or higher, the embrittlement of the lower-melting-point current collector is sufficiently achieved. If it is 1100°C or lower, the embrittlement of the lower-melting-point current collector, the higher-melting-point current collector, and the outer packaging container can all be suppressed, maintaining the separation efficiency of the current collector and the outer packaging container based on breakage and grading. Furthermore, when the outer packaging container of the LIB melts during the heat treatment, by placing a receiving dish for recovering the molten metal below the LIB, the metal originating from the outer packaging container can be easily separated from the electrode portion.

[0100] By performing heat treatment at a specified heat treatment temperature, for example in a laminate where the positive current collector is aluminum and the negative current collector is copper, the positive current collector formed from aluminum foil becomes embrittled, making it easier to refine into fine particles during the crushing process described later. This embrittlement of the positive current collector occurs due to melting or oxidation reactions. Furthermore, the aluminum that melts and flows off is recovered into a receiving dish. On the other hand, the negative current collector formed from copper is heat-treated at a temperature below the melting point of copper, thus enabling high-level screening without melting during the dry magnetic screening process described later. Additionally, when either the laminate or the LIB is placed in an oxygen-isolated container and heat-treated, the positive current collector formed from aluminum foil melts and becomes embrittled, making it easier to refine into fine particles during the crushing process described later. On the other hand, the negative current collector formed from copper is heat-treated under low oxygen partial pressure conditions thanks to the oxygen isolation effect of the aforementioned oxygen-isolated container and the reduction effect achieved by the negative electrode active materials such as carbon contained in the laminate and / or LIB, thus preventing embrittlement due to oxidation. Therefore, the positive current collector is finely crushed due to the crushing process, and the negative current collector also exists in the form of coarse particles after crushing. In the classification and screening process described later, it can be screened more effectively and highly.

[0101] There are no particular restrictions on the heat treatment time; it can be appropriately selected according to the purpose, ranging from more than 1 minute to less than 5 hours, 2 hours, or 1 hour. The heat treatment time is simply the time required for the low-melting-point current collector to reach the desired temperature; a short holding time is also acceptable. If the heat treatment time is within a particularly preferred range, it is advantageous in terms of the cost of heat treatment.

[0102] There are no particular restrictions on the methods of heat treatment, and they can be appropriately selected according to the purpose. For example, the use of a heat treatment furnace can be listed. Examples of heat treatment furnaces include rotary kilns, fluidized bed furnaces, tunnel furnaces, muffle furnaces and other intermittent furnaces, blast furnaces, and stoker furnaces.

[0103] There are no particular restrictions on the atmosphere used in heat treatment, and it can be appropriately selected according to the purpose; the treatment can be carried out in air. However, it is preferable to use an atmosphere with a low oxygen concentration, from the viewpoint that metals from both the positive and negative current collectors can be recovered with high quality and high recovery rate.

[0104] As a method to achieve the aforementioned low-oxygen atmosphere, the LIB or laminate can be housed in an oxygen-isolated container and subjected to heat treatment. The material of the oxygen-isolated container is not particularly limited as long as it does not melt at the aforementioned heat treatment temperature; it can be appropriately selected according to the purpose, for example, iron and stainless steel. To release the gas pressure caused by the combustion of the electrolyte in the LIB or laminate, it is preferable to provide an opening in the oxygen-isolated container. Preferably, the opening area is 12.5% ​​or less of the surface area of ​​the outer packaging container. More preferably, the opening area is 6.3% or less of the surface area of ​​the outer packaging container. If the opening area exceeds 12.5% ​​of the surface area of ​​the outer packaging container, most of the current collector is prone to oxidation due to heat treatment. There are no particular limitations on the shape, size, or location of the opening; it can be appropriately selected according to the purpose.

[0105] As a result, as long as the LIB or laminate can be heat-treated at high temperature (e.g., 800°C) and in an oxygen-free or low-oxygen environment, it is possible to heat-treat the LIB in a heat treatment furnace, even without using the aforementioned oxygen-isolation container, by blocking the air supply or setting the supply amount to a small amount (e.g., less than 11% in terms of oxygen concentration).

[0106] Here, it is also preferable to perform qualitative and quantitative analysis of the metallic elements contained in the heat-treated product obtained through the heat treatment process, using methods such as fluorescence X-ray analysis. This is because the metallic composition of the heat-treated product can sometimes vary depending on the LIB of the treated object.

[0107] Based on the qualitative and quantitative analysis results, from the viewpoint of stabilizing the composition of the metal components of the recycled cathode material, the preferred configuration is to group heat-treated materials with the same metal composition and then transport the heat-treated materials divided into groups to the crushing process described later.

[0108] (3-2. Crushing process)

[0109] Next, a crushing process is performed to break the heat-treated material obtained from the heat treatment process. In the crushing process, it is preferable to crush the heat-treated material by impact to obtain crushed material.

[0110] Furthermore, there are no particular limitations on the crushing method, and it can be appropriately selected according to the purpose. Examples of impact-based crushing methods include: throwing a rotating impact plate to strike the material; and striking the heat-treated material with a rotating beater, which can be performed using, for example, a hammer crusher and / or a chain crusher. Additionally, methods using balls and / or rods made of ceramics and / or iron to strike the heat-treated material can be performed using ball mills and / or rod mills. Furthermore, crushing can be achieved using a twin-screw crusher with a short blade width and length that is based on compression crushing.

[0111] By utilizing impact to obtain fragments, the active material and low-melting-point current collectors are broken down. On the other hand, high-melting-point current collectors, whose morphology does not change significantly, exist in the form of foil or the like. Therefore, in the crushing process, the high-melting-point current collectors are simply cut. Compared to low-melting-point current collectors, high-melting-point current collectors are more difficult to refine into fine particles. Thus, fragments that allow for efficient separation of low-melting-point and high-melting-point current collectors in the grading and screening process described later can be obtained.

[0112] There are no particular restrictions on the crushing time, which can be appropriately selected according to the purpose. The processing time per 1 kg LIB is preferably more than 1 second and less than 30 minutes, more preferably more than 2 seconds and less than 10 minutes, and particularly preferably more than 3 seconds and less than 5 minutes. If the crushing time is less than 1 second, it may sometimes not be crushed, and if it exceeds 30 minutes, it may sometimes be over-crushed. Furthermore, it is preferable to set the maximum particle size of the crushed material to be less than 10 mm.

[0113] (3-3. Grading and screening process)

[0114] Next, as a physical screening process, a grading screening process can be performed to classify the crushed material obtained from the crushing process into coarse and fine products. There are no particular restrictions on the grading method, and it can be appropriately selected according to the purpose. For example, vibrating screens, multi-stage vibrating screens, cyclone separators, JIS Z8801 standard screens, wet vibrating worktables, pneumatic worktables, etc. can be used.

[0115] As for the grading point used in the grading and screening process, as long as it is 0.45 mm or greater, it can be appropriately selected according to the purpose. For example, a grading point of 0.6 to 2.4 mm is desirable. When the grading point exceeds 2.4 mm, the amount of metals from the outer packaging container and high melting points that are mixed into the fine-particle product sometimes increases, reducing the effectiveness of separating cobalt / nickel / manganese from the active material. On the other hand, when the grading point is less than 0.6 mm, the amount of metals from low-melting-point current collectors and active materials mixed into the coarse-particle product sometimes increases, reducing the quality of metals from high-melting-point current collectors in the coarse-particle product, and the recovery rate of cobalt / nickel / manganese from the active material in the fine-particle product is less than 60%.

[0116] Furthermore, when using a sieve as a grading method, by placing a crushing promoter, such as stainless steel balls and / or alumina balls, on the sieve and passing it through the sieve, small fragments attached to the large fragments can be separated from the large fragments, thereby achieving more efficient separation of large and small fragments. This further improves the quality of the recovered metal. It should be noted that the crushing and grading processes can also be performed simultaneously. For example, it can be carried out in a process where the heat-treated material obtained in the heat treatment process is crushed while simultaneously grading the fragments into coarse and fine products (crushing / grading).

[0117] Through the above-described fractionation, coarse-grained products can recover metals from the outer container and high-melting-point current collectors, while fine-grained products (black matter (also known as black powder)) can recover cobalt / nickel / manganese / lithium from the active material. It should be noted that the fine-grained products can be fractionated again. By utilizing this further fractionation to remove particles, for example, smaller than 150 μm, from the fine matter, the negative electrode active material content in the non-magnetic material of wet magnetic screening (hereinafter, magnetic screening is also omitted and referred to as magnetic separation) can be reduced.

[0118] (3-4. Magnetic separation process)

[0119] As a physical screening process, dry magnetic separation can be performed on crushed materials obtained through crushing or coarse-grained products obtained through grading and screening. Iron is recovered as magnetically attracted material, while metals such as copper originating from the negative electrode current collector are recovered as non-magnetically attracted material.

[0120] As a physical screening process, a wet magnetic separation process is preferred for crushed material obtained through a crushing process or fine-particle products (black matter) obtained through a grading and screening process. Cobalt and nickel are recovered in the form of magnetically attracted material. When performing magnetic separation on the fine-particle products (black matter) obtained through a grading and screening process, dry magnetic separation causes particle aggregation due to adhering moisture between particles, making it impossible to fully separate the metal particles originating from the negative electrode current collector and the fine-particle products containing more than 10% negative electrode active material particles from the cobalt / nickel particles. In this invention, the wet magnetic separation process can separate the material originating from the negative electrode active material and the metal originating from the negative electrode current collector into a non-magnetically attracted product slurry, and recover the magnetically attracted material (black matter magnetically attracted material) containing cobalt and nickel. It should be noted that manganese is not strongly magnetic at room temperature, but when it forms a composite oxide with cobalt and nickel in the LIB, cobalt and nickel are carried along during magnetic separation. Therefore, a considerable amount of manganese is also recovered during magnetic separation. The magnetic force during magnetic separation is preferably 1500~8000G.

[0121] (3-5. Acid leaching process)

[0122] Acids such as H2SO4, HCl, and HNO3 are added to the fine-particle product (black substance) obtained in the grading and screening process or the magnetic material (black substance magnetic material) obtained in the magnetic separation process to dissolve metal elements such as cobalt / nickel / manganese / lithium in the acidic solution. On the other hand, copper and carbon are removed as insoluble residues.

[0123] The specific details of the acid leaching process are not particularly limited within the range capable of leaching cobalt, nickel, and manganese. For example, while adding acid to the fine-particle product or magnetic material, heating to the temperature and maintaining the pH value described in the following embodiments for the time specified in the embodiments, the metal elements in the fine-particle product or magnetic material are heated and decomposed, causing them to dissolve in the acid solution. If the pH value changes to a value below that described in the following embodiments, the acid solution is cooled, filtered to remove undissolved residues, and the filtrate (acid leaching solution) is recovered. It should be noted that H2SO4, HCl, HNO3, etc., can be used as the acid; however, from the viewpoint of removing copper, H2SO4 is preferred in this process.

[0124] Various methods can be used for filtration, such as membrane filters, filter paper, and centrifugation. Cross-flow filtration is also preferred.

[0125] (3-6. Iron removal process)

[0126] The process involves adding an oxidant to the recovered filtrate (acid leachate), adjusting the redox potential of the filtrate, and then adding an alkaline solution to generate a precipitate of ferric hydroxide, thereby removing iron.

[0127] As the oxidant added to the filtrate (acid leachate), known oxidants can be used. Examples include oxygen, ozone, metal oxides, oxyacids or their salts (e.g., potassium permanganate), halogens, etc. However, from the viewpoint of ease of use and cost, an aqueous solution of hydrogen peroxide is preferred. Furthermore, as the redox potential of the filtrate, it is preferable to set the upper limit to 750 mV (Ag / AgCl, the redox potential is the same in this specification, so it will not be described hereafter), 700 mV, or 650 mV, and the lower limit to 500 mV, 550 mV, or 600 mV.

[0128] Next, a known alkaline solution can be used as the added alkaline solution. For example, it can be an aqueous solution of an alkali metal hydroxide (sodium hydroxide aqueous solution and / or potassium hydroxide aqueous solution). Sodium hydroxide aqueous solution is exemplified in this specification. The concentration of the alkaline solution can be 0.5 to 10 mol / L. Then, the pH of the filtrate is adjusted to 3 to 5.5 to form a precipitate of ferric hydroxide, and the ferric hydroxide is aged at the liquid temperature described in the examples described later for a specified time. The filtrate and the ferric hydroxide precipitate are then filtered, and the filtrate (the liquid after iron removal) is recovered.

[0129] Various methods can be used for filtration, such as membrane filters and filter paper. Cross-flow filtration is also preferred.

[0130] (3-7. Ion exchange process)

[0131] The process involves contacting the recovered filtrate (after iron removal) with a specified chelating resin to perform ion exchange, thereby selectively adsorbing / removing aluminum and copper ions to obtain the filtrate (after ion exchange).

[0132] There are many different types of chelating resins with ion exchange capabilities. The inventors conducted research and concluded that, for the selective adsorption / removal of aluminum and copper ions from the aforementioned filtrate (after iron removal), an aminomethylphosphonic acid-based chelating resin, for example, with a styrene-divinylbenzene copolymer as the matrix and containing aminomethylphosphonic acid groups, is suitable. As a commercially available product, "IRC747UPS manufactured by DuPont Organo" is a preferred example.

[0133] The aminomethylphosphonic acid-based chelating resins are available in Na and H forms. However, when using the Na form, there is a concern that the pH of the filtrate may rise after ion exchange, leading to unexpected precipitation of metal hydroxides. Therefore, when using the Na form, it is preferable to pre-set the pH of the filtrate to below 3.

[0134] The following is an example of the content of each metal element in the ion-exchange liquid (or the regenerated cathode material precursor described later).

[0135] Regarding aluminum, the upper limit can be set at 100 mg / L, 50 mg / L, or 10 mg / L.

[0136] Regarding copper, the upper limit can be set at 1 mg / L, 0.1 mg / L, or 0.02 mg / L.

[0137] Regarding iron, the upper limit can be set at 1 mg / L, 0.5 mg / L, or 0.2 mg / L.

[0138] (3-8. Alkali treatment process)

[0139] The process involves mixing the obtained filtrate (after ion exchange) with an alkaline solution to adjust the pH to 9-14, causing metal elements such as cobalt, nickel, manganese, and lithium in the filtrate to precipitate as hydroxides. This process can also be collectively referred to as a wet metallurgical process, encompassing the preceding acid leaching step and this step.

[0140] For example, add 0.5–10 mol / L of NaOH aqueous solution to the recovered filtrate as an alkaline solution to adjust the pH of the filtrate to 11–12, forming a hydroxide precipitate. After the alkali addition is complete, filter the filtrate to recover the hydroxide precipitate.

[0141] (3-9. Cleaning process)

[0142] The process involves precipitating and washing the recovered hydroxide to obtain a precursor for the recycled cathode material.

[0143] For example, the recovered hydroxide precipitate is heated at 20°C to 200°C for 0.1 to 48 hours for strong heat drying to obtain a dried product. The dried product is then pulverized to obtain a powder. An equal to 10 times the amount (by weight) of water is added to the powder to obtain a slurry. The obtained slurry is filtered to recover the hydroxide precipitate.

[0144] Various filtration methods can be used, such as membrane filters and filter paper. Cross-flow filtration is also preferred.

[0145] The recovered hydroxide precipitate is heated at 20°C to 200°C for 0.1 to 48 hours and then dried to obtain the regenerated cathode material precursor of the present invention.

[0146] The resulting recycled cathode material precursor is a solid. In the following processes, the recycled cathode material precursor can be processed in a solid state or made into a slurry. Even when made into a slurry, the recycled cathode material precursor contained in the slurry remains a solid and does not change.

[0147] It should be noted that the salts remaining in the hydroxide precipitate can be removed by cleaning after the calcination process in "(4-3)" of "4. Manufacturing method of regenerated cathode material" described later.

[0148] It is also preferable to perform qualitative and quantitative analysis of the metal elements contained in the obtained recycled cathode material precursor of the present invention. This is because: sometimes the metal composition contained in the recycled cathode material precursor varies due to the different LIBs being processed; and the metal composition contained in the recycled cathode material precursor varies due to the process conditions up to this point.

[0149] For example, ICP analysis and / or fluorescence X-ray analysis can be performed on the metal elements contained in the ion-exchange solution. If the composition of the metal elements contained in the ion-exchange solution differs from the metal composition of the target regenerated cathode material, a formulation process and / or an addition process can be performed on the ion-exchange solution.

[0150] Specifically, regarding the discrepancy between the quantitative analysis results of the ion-exchange post-liquid and the metal composition of the target regenerated cathode material precursor, a process can be implemented to adjust the composition of the metal elements contained in the ion-exchange post-liquid (e.g., appropriately adjusting ion-exchange post-liquids from different LIBs with different metal compositions to obtain an ion-exchange post-liquid with the target metal composition), or an addition process can be implemented to add insufficient metal elements to the ion-exchange post-liquid. Of course, these processes can also be combined.

[0151] [4. Manufacturing method of recycled cathode material]

[0152] (4-1) Lithium source addition process

[0153] The process of adding lithium sources, etc., involves adding a predetermined amount of lithium source, nickel source, cobalt source, manganese source, etc., to the recycled cathode material precursor when the composition of the metal elements that function as the target cathode material in the recycled cathode material differs from the composition of the metal elements in the recycled cathode material of the present invention. However, manganese deficiency is rare in the recycled cathode material precursor.

[0154] Examples of lithium sources include lithium carbonate, lithium hydroxide, lithium nitrate, and lithium chloride.

[0155] Examples of nickel sources include nickel carbonate, nickel hydroxide, nickel nitrate, nickel chloride, and nickel sulfate.

[0156] Examples of cobalt sources include cobalt carbonate, cobalt hydroxide, cobalt nitrate, cobalt chloride, and cobalt sulfate.

[0157] Examples of manganese sources include manganese carbonate, manganese hydroxide, manganese nitrate, manganese chloride, and manganese sulfate.

[0158] The amount of lithium source, etc., added should be only the amount required to form the composition of the recycled cathode material that enables the desired battery characteristics to be obtained when the obtained recycled cathode material is made into a battery. The amount of lithium added is preferably 0.2 times or more and 2.0 times or less (moles) relative to the total amount (moles) of the metal elements contained in the recycled cathode material precursor that function as cathode materials.

[0159] (4-2) Crushing and mixing process

[0160] A mixture containing a specified amount of lithium source, etc., can be pulverized for homogenization.

[0161] The mixture containing a specified amount of lithium source, etc., is pulverized to obtain a pulverized mixture. The pulverization can be performed using, for example, a disc mill, mixer mill, bead mill, vibratory mill, ball mill, planetary ball mill, or grinding mill.

[0162] (4-3) Calcination process

[0163] The above mixture obtained by calcination yields the regenerated cathode material of the present invention. The calcination holding temperature is preferably 650°C to 900°C. The calcination holding time is preferably 0.1 hours to 20 hours, more preferably 0.5 hours to 8 hours. For example, an alumina crucible can be used, and calcination can be carried out under holding conditions of 600°C for 1 hour, followed by 900°C for 4 hours. In the regenerated cathode material obtained after calcining the regenerated cathode material precursor, iron, copper, and aluminum undergo oxide formation. Specifically, iron, copper, and aluminum, which are mostly hydroxides in the regenerated cathode material precursor, become oxides in the regenerated cathode material.

[0164] (4-4) Crushing process

[0165] By using a disc mill or similar device to pulverize the obtained recycled cathode material, it can be made into finer particles.

[0166] It should be noted that the finely granulated recycled cathode material can also be cleaned, and then the calcination process can be carried out again after the cleaning process.

[0167] The resulting regenerated cathode material of the present invention contains: lithium, nickel, cobalt and manganese; 0.01% by mass and 1.5% by mass of aluminum; and less than 1% by mass of copper and iron, which can exhibit the same level of specific capacity as LIBs using conventional cathode materials, and can achieve cycle characteristics that are almost as good as those of LIBs using conventional cathode materials.

[0168] [5. How to use regenerated cathode materials]

[0169] (5-1) Regenerated positive electrode

[0170] The regenerated positive electrode of the present invention includes the regenerated positive electrode material of the present invention as the positive electrode active material, and further includes conductive agents, binding resins and other components as needed.

[0171] (5-2) Lithium-ion secondary battery using the regenerated cathode material of the present invention

[0172] The LIB of the present invention is a LIB having a positive electrode, a negative electrode and a separator, wherein the positive electrode contains the recycled positive electrode material of the present invention.

[0173] Using the recycled cathode material of the present invention, the LIB of the present invention can be manufactured by a known LIB manufacturing method.

[0174] [6. Effects of the Invention]

[0175] As explained above, according to the present invention, the LIB, which is the object of treatment, is subjected to heat treatment, crushing treatment, and classification treatment, which are environmentally friendly and cost-effective, to recover fine particulate products (black substances). Furthermore, by performing environmentally friendly and cost-effective treatments on the fine particulate products (black substances), such as magnetic separation treatment, acid leaching treatment, iron removal treatment, ion exchange treatment, alkali treatment, and washing treatment, high-quality recycled cathode material precursors with low contents of any of iron, copper, and aluminum can be manufactured.

[0176] The aforementioned effects mean that multiple LIBs can be processed simultaneously. That is, if multiple LIBs are subjected to a heat treatment process together, followed by the aforementioned processes, it means that recycled cathode material precursors and / or recycled cathode materials can be manufactured. Furthermore, this manufacturing process achieves lower environmental impact and lower recycling costs, while ensuring higher safety.

[0177] With the rapid popularization of LIBs in recent years, and given the current situation where their reuse has become a topic of discussion, the advantages of this invention are considered to be significant.

[0178] Example

[0179] The present invention will now be described in more detail with reference to embodiments. However, the present invention is not limited to these embodiments.

[0180] In addition, in Examples 1 and 2, as regenerated cathode materials manufactured by the manufacturing method of the present invention, two types of regenerated cathode materials were manufactured: "regenerated cathode material (without composition adjustment)" in which the regenerated cathode material precursor is calcined without composition adjustment, and "regenerated cathode material (with composition adjustment)" in which the regenerated cathode material precursor is calcined after composition adjustment.

[0181] In addition, in Comparative Examples 1 to 3, three comparative example materials were prepared: a "regenerated cathode material (conventional type)" manufactured using conventional manufacturing methods; a "commercially available cathode material" prepared from commercially available cathode material (in which recalcination was performed at 900°C for 4 hours in air); and a "reproduced product of commercially available cathode material" manufactured by the manufacturing method of the present invention from a solution obtained by dissolving commercially available cathode material in acid (sulfuric acid).

[0182] (Example 1) Regenerated cathode material (no composition adjustment)

[0183] <Heat Treatment Process>

[0184] A battery pack (approximately 75 kg) of LIB (Library Intake) was subjected to heat treatment at a temperature of 800°C (heated for 1 hour and held for 2 hours) to obtain a heat-treated product. An intermittent combustion furnace from ECO-SYSTEM Akita Co., Ltd. was used as the heat treatment apparatus. During this heat treatment, the furnace atmosphere was initially set to atmospheric conditions, but the heat treatment was performed with the air supply cut off.

[0185] <Crushing Process>

[0186] Next, as a crushing device, a hammer crusher (Makino pendulum hammer crusher HC-20-3.7, manufactured by Makino Sangyo Co., Ltd.) was used to crush the heat-treated material (LIB that has undergone heat treatment) obtained in the above heat treatment process at 50Hz (38m / second circumferential speed of the hammer) and with the wire mesh at the outlet having a grate-type opening of 30mm×200mm, to obtain crushed LIB material.

[0187] <Grading and Screening Process>

[0188] Next, the LIB fragments were sieved using a 1.2mm mesh sieve (200mm diameter, manufactured by Tokyo Wire Mesh Co., Ltd.) to separate the fragments into oversize (coarse product) and undersize (fine product). The fine product (black substance) from the undersize was then used to obtain the fine product (black substance) of Example 1. The composition of the fine product (black substance) is shown in Table 1. Hereinafter, the composition table is obtained through ICP analysis. ICP analysis was performed using an iCAP6300Duo manufactured by Thermo Fisher Scientific (the same applies to ICP analysis below).

[0189] <Magnetic Separation Process>

[0190] Wet magnetic separation was performed on the fine-particle product (black substance) of Example 1 using a drum-type magnetic separator with a magnetic force of 1500G, a drum speed of 45rpm, a solid-liquid ratio of 10%, and a slurry feed rate of 100ml / min to recover the magnetically adsorbed material (black substance magnetic adsorbed material) of Example 1. The composition of the magnetically adsorbed material (black substance magnetic adsorbed material) is shown in Table 1. In Table 1, when attempting to compare the composition of the fine-particle product (black substance) and the magnetically adsorbed material (black substance magnetic adsorbed material), the content (mass%) of nickel, cobalt, and manganese increased in the magnetically adsorbed material compared to the fine-particle product.

[0191] [Table 1]

[0192]

[0193] <Acid leaching process>

[0194] 250g of the recovered magnetic material (black magnetic material) from Example 1 was placed in a 5000mL upright beaker, and 750mL of ion-exchanged water was added. The mixture was stirred using a magnetic stirrer with a heater while maintaining the liquid temperature at 45°C. A 50% by weight sulfuric acid solution was added to maintain pH 1 for acid leaching. The endpoint was defined as the point at which the pH change was less than 0.02 per hour. After cooling the acid leachate, insoluble residues were removed using No. 5C filter paper, and the filtrate (acid leachate) was recovered. The composition of the filtrate (acid leachate) is shown in Table 2.

[0195] <Iron Removal Process>

[0196] An oxidant (hydrogen peroxide aqueous solution) was added to the above filtrate (acid leaching solution) to adjust the redox potential to 634 mV (Ag / AgCl). Then, an alkaline solution was added to the filtrate with adjusted redox potential to adjust the pH to 4.42, generating ferric hydroxide precipitate. The filtrate was then kept at 40°C for 12 hours to mature the ferric hydroxide. After filtration, the filtrate (acid leaching solution) and the ferric hydroxide precipitate were separated, and the filtrate (after iron removal) was recovered. The composition of the filtrate (after iron removal) is shown in Table 2.

[0197] <Ion Exchange Process>

[0198] A 150 mL UPS of AmberSepIRC747 UPS manufactured by DuPont Organo, used as a chelating resin, was packed into a vinyl chloride column with an inner diameter of 40 mm to serve as an ion exchange column. The above-mentioned filtrate (after iron removal) adjusted to pH 2.90 with the addition of 50% by weight sulfuric acid solution was passed into the column at a flow rate of 25.0 mL / min (SV=10) to remove aluminum ions, yielding the filtrate (after ion exchange). The composition of the filtrate (after ion exchange) is shown in Table 2.

[0199] [Table 2]

[0200]

[0201] <Alkali Treatment Process>

[0202] The resulting filtrate (after ion exchange) was mixed with an aqueous solution of approximately 7.5% NaOH by mass, and the pH was adjusted to 11.3 to precipitate the hydroxide. No. 5C filter paper was then used to recover the hydroxide.

[0203] <Cleaning Process>

[0204] Sufficient ion-exchange water was added to the hydroxide recovered by the filter paper to wash away water-soluble salts. Then, it was dried in a vacuum thermostat at 85°C to obtain a precursor sample of the regenerated cathode material.

[0205] <Pulverizing Process>

[0206] The obtained regenerated cathode material precursor sample was pulverized using a disc mill to obtain pulverized material.

[0207] <Lithium Addition Process>

[0208] Lithium, in an amount equivalent to 1.0 molar, is added as lithium carbonate relative to the total amount (moles) of the metal elements that function as the positive electrode material contained in the pulverized precursor, and the mixture is then mixed using a mortar and pestle.

[0209] <Calcination Process>

[0210] The mixture was placed in an alumina crucible and calcined in an atmospheric atmosphere at 600°C for 1 hour, followed by 900°C for 4 hours, to obtain a recycled cathode material sample.

[0211] <Pulverizing Process>

[0212] The obtained regenerated cathode material sample was crushed using a mortar and pestle.

[0213] The obtained regenerated cathode material samples were decomposed by acid using a mixture of HCl and HNO3, and then subjected to compositional analysis using ICP-AES (SPECTRO GREEN, Hitachi High Technology Co., Ltd.).

[0214] The composition of the regenerated cathode material samples, expressed as mass % by the constituent elements, is shown in Table 3.

[0215] The composition, expressed in moles per 100g, is shown in Table 4.

[0216] The molar ratios of the specified elements, determined from the molar number per 100g, are shown in Table 5. It should be noted that MCN represents the total molar number of Mn, Co, and Ni, while MCNCuFeAl is obtained by adding the individual molar numbers of Cu, Fe, and Al to the total molar number of Mn, Co, and Ni.

[0217] It should be noted that the following regenerated cathode materials (with composition adjustments), regenerated cathode materials (conventional types), commercially available cathode materials, and replicas of commercially available cathode materials are also listed in the above tables.

[0218] (Example 2) Regenerated cathode material (with composition adjustments)

[0219] <Adding a process>

[0220] In Example 1 above, the composition of the filtrate (post-ion exchange liquid) obtained in the ion exchange process was analyzed. As a result, in order to adjust the cobalt and nickel content, which was insufficient compared to the manganese, cobalt, and nickel content in the commercially available cathode material used in Comparative Example 2, sulfuric acid solutions of cobalt hydroxide and nickel hydroxide were added to adjust the composition.

[0221] <Alkali Treatment Process>

[0222] The resulting composition-adjusting solution was mixed with an aqueous solution of approximately 7.5% NaOH by mass to adjust the pH to 11.3, causing the hydroxide to precipitate. No. 5C filter paper was then used to recover the hydroxide.

[0223] <Cleaning Process>

[0224] Sufficient ion-exchange water was added to the hydroxide recovered by the filter paper to wash away water-soluble salts. Then, it was dried in a vacuum thermostat at 85°C to obtain a precursor sample of the regenerated cathode material.

[0225] <Pulverizing Process>

[0226] The obtained regenerated cathode material precursor sample was pulverized using a disc mill to obtain pulverized material.

[0227] <Lithium Addition Process>

[0228] Lithium, in an amount equivalent to 1.1 moles of the metal elements that function as the positive electrode material in the pulverized precursor, is added as lithium carbonate and mixed using a mortar and pestle.

[0229] Otherwise, the same procedures as in Example 1 were performed to obtain the recycled cathode material of this example. The resulting sample was subjected to compositional analysis in the same manner as in Example 1.

[0230] (Comparative Example 1) Regenerated cathode material (conventional type)

[0231] The iron removal process and the ion exchange process were not performed. Otherwise, the same process as that for the regenerated cathode material in Example 1 was performed to obtain the regenerated cathode material (conventional type) of this example. The composition analysis of the obtained sample was performed in the same manner as in Example 1.

[0232] (Comparative Example 2) Commercially available cathode materials

[0233] Commercially available conventional cobalt-nickel-manganese cathode materials (LiNi) 1 / 3 Co 1 / 3 Mn 1 / 3 O2, PLB-H1, manufactured by Gelon LIBGroup Ltd.

[0234] The cobalt-nickel-manganese cathode material was calcined again in air at 900°C for 4 hours to obtain a commercially available cathode material. The obtained sample was subjected to compositional analysis in the same manner as in Example 1.

[0235] (Comparative Example 3) Replicas of commercially available cathode materials

[0236] A commercially available, conventional cobalt-nickel-manganese cathode material was dissolved in acid. The resulting solution was subjected to the same alkali treatment, cleaning, pulverizing, calcining, and pulverizing processes as in Example 1, thereby obtaining a replica of the commercially available cathode material. The resulting sample was subjected to compositional analysis as in Example 1.

[0237] [Table 3]

[0238]

[0239] [Table 4]

[0240]

[0241] [Table 5]

[0242]

[0243] 2. Manufacturing of lithium-ion secondary batteries

[0244] <The Manufacturing of the Positive Electrode>

[0245] As positive electrode active materials, the positive electrode materials obtained in Examples 1, 2 and Comparative Examples 1 to 3 above were prepared, including acetylene black (DENKA BLACK, manufactured by DENKA Corporation) as a conductive additive, polyvinylidene fluoride (KF polymer F #9130, manufactured by KUREHA Corporation) as a binder, and N-methylpyrrolidone as a solvent.

[0246] Then, each positive electrode material was mixed with acetylene black and polyvinylidene fluoride in a ratio of 80:10:10 (mass%) to prepare a mixture. N-methylpyrrolidone was added to the mixture to obtain a slurry. The amount of N-methylpyrrolidone added to the mixture was set as the mass ratio of mixture:N-methylpyrrolidone = 1:1.25.

[0247] After mixing the obtained slurry for 10 minutes, the slurry was applied to an aluminum foil (t 20μm) serving as the current collector for the positive electrode material using a Baker-type applicator. Then, the slurry and aluminum foil were dried together in a dryer at 100°C. The dried aluminum foil and the coated positive electrode material were pressed at 4t and then punched into a diameter of φ15mm to serve as the positive electrode.

[0248] <The Manufacturing of the Negative Electrode>

[0249] The following materials were prepared: graphite (CGB-10, manufactured by Nippon Graphite Industries, Ltd.) as the negative electrode active material, acetylene black (DENKA BLACK, manufactured by DENKA Corporation) as the conductive additive, carboxymethyl cellulose (Cellogen 7A, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.) and styrene-butadiene rubber (TRD2001, manufactured by JSR Corporation) as the binder, and pure water as the solvent.

[0250] Then, the graphite, acetylene black, carboxymethyl cellulose, and styrene-butadiene rubber were mixed in a ratio of 90:5:2.5:2.5 (mass%). Distilled water was added to this mixture to obtain a slurry. The amount of distilled water added to this mixture was set at a mass ratio of 1:1.6 (mixture:distilled water).

[0251] The obtained slurry was stirred in a mixer for 10 minutes, and then coated onto a copper foil (t 20 μm) of graphite current collector, which served as the negative electrode material, using a Baker-type applicator. The copper foil and the coated negative electrode material were then dried together in a dryer at 100°C. The dried copper foil and the coated negative electrode material were pressed at 4t, and then punched into a diameter of φ15 mm to serve as the negative electrode.

[0252] Assembly of Lithium-ion Secondary Batteries

[0253] Inside a glove box filled with pure argon gas, a CR2032 coin cell is used, such as... Figure 2 As shown, the following components are stacked in sequence: 1. Positive current collector (made of stainless steel), 2. Positive electrode (a product coated with positive electrode material on an aluminum foil current collector), 3. Spacer, 4. Negative electrode (a product coated with negative electrode material on a copper foil current collector), 5. Spacer, 6. Washer, 7. and 8. Negative current collector (made of stainless steel).

[0254] Then, full cells of lithium-ion secondary batteries using the positive electrode materials obtained in Examples 1, 2 and Comparative Examples 1-3 were assembled by riveting together the stainless steel positive electrode current collector and negative electrode current collector.

[0255] It should be noted that the separator is made of porous polypropylene (#2500, manufactured by Celgard LLC) with a diameter of φ19mm, and the electrolyte is 1mol / L LiPF6 as the solute and ethylene carbonate + diethyl carbonate (volume ratio 1:1) as the solvent.

[0256] In the case of a full cell, the assumed specific capacity of the conventional positive electrode material and the recycled positive electrode material is set to 140 mAh / g or 150 mAh / g, depending on the range of cell voltage variation during charge and discharge. Additionally, the assumed specific capacity of graphite as the negative electrode material is set to 340 mAh / g. The ratio of negative electrode capacity to positive electrode capacity (NP ratio) is set to 1.2. It should be noted that the assumed specific capacity of the positive electrode material used in the full cell is explicitly stated each time.

[0257] Next, following the same procedure as with the full-cell lithium-ion secondary batteries described above, half-cells of lithium-ion secondary batteries using the cathode materials obtained in Examples 1, 2, and Comparative Examples 1-3 were assembled. The half-cells were identical to the full-cells except that the graphite anode was replaced with a lithium foil with a diameter of 15 mm and a diameter of 0.2 mm. In the case of half-cells, the expected specific capacity of the conventional cathode material and the recycled cathode material was set to 140 mAh / g or 150 mAh / g, depending on the potential variation range of the cathode. It should be noted that the expected specific capacity of the cathode material used in the half-cells was also explicitly stated each time.

[0258] 3. Charge and discharge test of lithium-ion secondary batteries

[0259] For the half-cells and full-cells of the manufactured lithium-ion secondary batteries, charge-discharge tests based on cycle tests were performed as described below to determine the charge-discharge specific capacity and coulombic efficiency (charge-discharge efficiency, hereinafter abbreviated as efficiency) of each cathode material obtained in Examples 1, 2, and Comparative Examples 1-3. In both half-cells and full-cells, the performance of the battery cell was evaluated by dividing the capacity measured during charging and discharging by the mass of the regenerated cathode material within the battery cell to obtain the cathode reference specific capacity.

[0260] <Charging and Discharging Tests in Positive Half-Cells>

[0261] (Rate test of positive half cell)

[0262] Under the following conditions, charging and discharging of the positive electrode, i.e., lithium ion desorption and insertion, were performed, and the specific capacity and coulombic efficiency were measured.

[0263] (1) Regenerated cathode material (without composition adjustment), (2) Regenerated cathode material (with composition adjustment), (3) Regenerated cathode material (conventional type), (4) Commercially available cathode material, (5) Replica of commercially available cathode material. The intended specific capacity of the cathode material is 140 mAh / g (based on the mass of the cathode material).

[0264] Test temperature: 25℃

[0265] Positive electrode potential range: 3.0V~4.2V vsLi / Li +

[0266] Current densities: 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, 10C, 0.1C (where 1C = 140mA / g (based on the mass of the cathode material)).

[0267] Cycle count: 5 times at each current density

[0268] The following are the measurement items.

[0269] (I) Specific capacity at 0.1C, first cycle, during charging (lithium ion depletion).

[0270] This value represents the amount of lithium ions removed during the initial extraction process from the cathode material.

[0271] (II) Specific capacity at 0.1C, first cycle, discharge (lithium-ion intercalation).

[0272] This value represents the amount of lithium ions inserted during the process of initially drawing lithium ions from the cathode material and then returning them to the cathode material.

[0273] (III) Coulomb efficiency at 0.1C, first cycle, charging and discharging.

[0274] This value indicates the extent to which detached lithium ions return to the cathode material during the initial detachment and insertion of lithium ions in the cathode material.

[0275] (IV) Specific capacity at 0.1C, 3rd cycle, discharge (lithium-ion intercalation).

[0276] This value represents the reversible amount of lithium ions that can be processed in the cathode material when the current density is lowest, the repeated deintercalation and intercalation of lithium ions in the cathode material are slow and stabilized to a certain extent.

[0277] (V) 10C, 3rd cycle, specific capacity during discharge (lithium-ion intercalation).

[0278] This value represents the reversible lithium-ion throughput of the cathode material at the highest current density, indicating its responsiveness to high-speed charging and discharging.

[0279] (VI) Specific capacity during the third cycle of discharge (lithium-ion intercalation) at 0.1C after the second stage of the 10C test.

[0280] This value represents the reversible amount of lithium ions that can be processed in the cathode material after 35 charge-discharge cycles in which the current density is varied from 0.1C to 10C, under conditions where the repeated de-entry and insertion of lithium ions in the cathode material are sufficiently slow and stabilized.

[0281] The rate test results of the positive electrode half-cell are recorded in Table 6.

[0282] The results in Table 6 show that the conventional recycled cathode material with a high aluminum content (Comparative Example 1) has low specific capacity and coulombic efficiency. In contrast, the recycled cathode materials (Examples 1 and 2) with reduced aluminum content have specific capacity and coulombic efficiency values ​​close to those of the commercially available cathode material replica (Comparative Example 3). Furthermore, the recycled cathode material (Example 2) with adjusted lithium, nickel, and cobalt composition has specific capacity and coulombic efficiency roughly comparable to those of the commercially available cathode material (Comparative Example 2) and the commercially available cathode material replica (Comparative Example 3), achieving values ​​higher than these values ​​depending on the specific component.

[0283] [Table 6]

[0284]

[0285] <Charge and discharge test of full battery>

[0286] (A) (Rate test of full cell)

[0287] Under the following conditions, charge and discharge are performed at a constant current density.

[0288] (1) Regenerated cathode material (without composition adjustment), (2) Regenerated cathode material (with composition adjustment), (3) Regenerated cathode material (conventional type), (4) Commercially available cathode material, (5) Replica of commercially available cathode material. The intended specific capacity of the cathode material is 140 mAh / g (based on the mass of the cathode material).

[0289] Test temperature: 25℃

[0290] Battery cell voltage range: 2.5V~4.2V (initial charge: 0V~4.2V)

[0291] Current densities: 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, 10C, 0.1C (where 1C = 140mA / g (based on the mass of the cathode material)).

[0292] Cycle count: 5 times at each current density

[0293] The following are the measurement items.

[0294] (I) Specific capacity at 0.1C, first cycle, during charging

[0295] This value represents the amount of lithium ions removed from the cathode material during the initial charging process of the full battery.

[0296] (II) Specific capacity at 0.1C, first cycle, and discharge

[0297] This value represents the amount of lithium ions inserted into the cathode material during the process of the entire battery being initially charged and then discharged.

[0298] (III) Coulombic efficiency at 0.1C, first cycle, charging and discharging

[0299] This value indicates the extent to which lithium ions released during charging return to the cathode material during the initial charging and discharging process of the full battery.

[0300] (IV) Specific capacity at 0.1C, 3rd cycle, and discharge

[0301] This value represents the reversible amount of lithium ions that can be processed in the cathode material when the current density is lowest, the repeated charging and discharging of the full cell is slow, and the process is stabilized to a certain extent.

[0302] (V) 10C, 3rd cycle, specific capacity during discharge

[0303] This value represents the reversible amount of lithium ions that the cathode material can handle during charging and discharging at the highest current density, indicating its responsiveness to high-speed charging and discharging.

[0304] (VI) Specific capacity at 0.1C discharge in the second stage after the 10C charge-discharge test.

[0305] This value represents the reversible amount of lithium ions that can be transferred from the cathode material after 35 charge-discharge cycles in which the current density is varied from 0.1C to 10C, under conditions of repeated slow and stable charging and discharging of the full cell.

[0306] The results of the full-cell rate test are recorded in Table 7.

[0307] The results in Table 7 show that the conventional recycled cathode material with a high aluminum content (Comparative Example 1) has low specific capacity and coulombic efficiency. In contrast, the recycled cathode materials (Examples 1 and 2) with reduced aluminum content exhibit specific capacity and coulombic efficiency values ​​close to those of commercially available cathode materials (Comparative Example 2) and replicas of commercially available cathode materials (Comparative Example 3). In particular, the recycled cathode material (Example 2) with adjusted nickel and cobalt composition was found to have specific capacity and coulombic efficiency comparable to the cathode materials of Comparative Examples 2 and 3 that used virgin materials.

[0308] [Table 7]

[0309]

[0310] (B) (Cyclic test of full cell)

[0311] After the full-cell rate test, charge and discharge cycles of a specified number of cycles are performed at a constant current density under the following conditions.

[0312] Test temperature: 25℃

[0313] Battery cell voltage range: 2.5V~4.2V

[0314] Current density: 2C (280mA / g (based on the mass of the cathode material))

[0315] Number of loops: 500

[0316] The following are the measurement items.

[0317] (I) Specific capacity during the first cycle and discharge

[0318] This value represents the amount of lithium ions removed from the cathode material during the initial discharge of a full battery in a real-world charging and discharging cycle, where a current density of 2C is required to complete a full charge or discharge of the battery in 30 minutes.

[0319] (II) Specific capacity at the 200th cycle and discharge

[0320] This value represents the amount of lithium ions removed from the cathode material after 200 cycles of charge-discharge at a current density of 2C for the entire battery. In lithium-ion secondary batteries, performance is envisioned as a phase throughout the product's lifespan, from the initial stable period to the mid-term.

[0321] (III) Maintenance of discharge specific capacity at the 200th cycle, with the 1st cycle as the baseline

[0322] This value represents the cycle durability of a full battery after 200 charge-discharge cycles, from the initial to the middle stage of its lifespan.

[0323] (IV) Specific capacity at the 500th cycle and discharge

[0324] This value represents the amount of lithium ions removed from the cathode material after 500 charge-discharge cycles at a current density of 2C for a full cell. As a product, its performance is envisioned at the end of its lifespan.

[0325] (V) Discharge capacity retention rate at the 500th cycle, with the 1st cycle as the baseline.

[0326] This value represents the cycle durability of a full battery after 500 charge-discharge cycles, up to the end of its lifespan.

[0327] The results of the full-cell cycle test are recorded in Table 8.

[0328] According to the results in Table 8, the specific capacity retention rate of the conventional recycled cathode material with a high aluminum content (Comparative Example 1) is comparable to that of other cathode materials, but its specific capacity is lower. In contrast, the recycled cathode materials (Examples 1 and 2) that achieved a reduction in aluminum content have increased specific capacity and higher specific capacity retention rate compared to conventional recycled cathode materials. In particular, the recycled cathode material (Example 2) with adjusted nickel and cobalt composition showed the same specific capacity and retention rate as commercially available cathode materials (Comparative Example 2) and replicas of commercially available cathode materials (Comparative Example 3), demonstrating cycle durability comparable to cathode materials using virgin materials.

[0329] [Table 8]

[0330]

[0331] <Charging and Discharging Tests in Positive Half-Cells at High Potential>

[0332] (Rate test of positive electrode half cell at high potential)

[0333] If the cathode material undergoes lithium-ion deintercalation / intercalation at a high potential, its specific capacity increases, and the energy density of the entire battery increases. Conversely, if the cathode material is exposed to a high potential, i.e., a highly oxidizing atmosphere, stable operation becomes difficult. In this experiment, we evaluated the specific capacity and operational stability of the cathode material during charge and discharge at high potentials.

[0334] Under the following conditions, charging and discharging of the positive electrode, i.e., lithium ion desorption and insertion, were performed, and the specific capacity and coulombic efficiency were measured.

[0335] (1) Regenerated cathode material (without composition adjustment), (2) Regenerated cathode material (with composition adjustment), (3) Regenerated cathode material (conventional type), (4) Commercially available cathode material, (5) Replica of commercially available cathode material. The intended specific capacity of the cathode material is 150 mAh / g (based on the mass of the cathode material).

[0336] Test temperature: 25℃

[0337] Positive electrode potential range: 3.0V~4.5V vsLi / Li +

[0338] Current densities: 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, 10C, 0.1C (where 1C = 150mA / g (based on the mass of the cathode material)).

[0339] Cycle count: 5 times at each current density

[0340] The following are the measurement items.

[0341] (I) Specific capacity at 0.1C, first cycle, during charging (lithium-ion depletion)

[0342] (II) Specific capacity at 0.1C, first cycle, discharge (lithium-ion intercalation)

[0343] (III) Coulombic efficiency at 0.1C, first cycle, charging and discharging

[0344] (IV) Specific capacity at 0.1C, 3rd cycle, discharge (lithium-ion intercalation)

[0345] (V) 10C, 3rd cycle, specific capacity during discharge (lithium-ion intercalation)

[0346] (VI) Specific capacity during the third cycle of discharge (lithium-ion intercalation) at 0.1C after the second stage of the 10C test.

[0347] The rate test results of the positive electrode half-cell at high potential are recorded in Table 9.

[0348] As shown in Table 9, the conventional recycled cathode material with a high aluminum content (Comparative Example 1) still exhibits a lithium-ion depletion ratio of 4.5 V vs Li / Li even when the lithium-ion depletion reaches 4.5 V vs Li / Li. +At high potentials, the specific capacity and coulombic efficiency are also low. The specific capacity and coulombic efficiency of the recycled cathode materials (Examples 1 and 2) with reduced aluminum content are close to those of commercially available cathode materials (Comparative Example 2) and replicas of commercially available cathode materials (Comparative Example 3). In particular, the recycled cathode material (Example 2) with adjusted nickel and cobalt composition showed performance comparable to that of the cathode materials using virgin materials in Comparative Examples 2 and 3. That is, it was determined that by reducing the aluminum content, the recycled cathode material can stably perform lithium-ion desorption and insertion with high specific capacity even at high potentials.

[0349] [Table 9]

[0350]

[0351] <Charge and discharge test of full cell at high cell voltage>

[0352] (A) (Rate test of a full cell at high cell voltage)

[0353] When a full battery is charged and discharged at a high voltage, its energy storage capacity (energy density) increases. However, in the cathode material, more lithium ions are released, exposing it to a high potential, i.e., a highly oxidizing atmosphere, making it difficult for the full battery to operate stably. Therefore, it is necessary to evaluate the specific capacity and operational stability of a full battery during high-voltage charge and discharge.

[0354] Under the following conditions, charge and discharge are performed at a constant current density.

[0355] (1) Regenerated cathode material (without composition adjustment), (2) Regenerated cathode material (with composition adjustment), (3) Regenerated cathode material (conventional type), (4) Commercially available cathode material, (5) Replica of commercially available cathode material. The intended specific capacity of the cathode material is 150 mAh / g (based on the mass of the cathode material).

[0356] Test temperature: 25℃

[0357] Battery cell voltage range: 2.5V~4.4V (initial charge: 0V~4.4V)

[0358] Current densities: 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, 10C, 0.1C (where 1C = 150mA / g (based on the mass of the cathode material)).

[0359] Cycle count: 5 times at each current density

[0360] The following are the measurement items.

[0361] (I) Specific capacity at 0.1C, first cycle, during charging

[0362] (II) Specific capacity at 0.1C, first cycle, and discharge

[0363] (III) Coulombic efficiency at 0.1C, first cycle, charging and discharging

[0364] (IV) Specific capacity at 0.1C, 3rd cycle, and discharge

[0365] (V) 10C, 3rd cycle, specific capacity during discharge

[0366] (VI) Specific capacity at 0.1C discharge in the second stage after the 10C charge-discharge test.

[0367] The rate test results of the full cell at high cell voltage are recorded in Table 10.

[0368] According to the results in Table 10, conventional recycled cathode materials with high aluminum content (Comparative Example 1) exhibited low specific capacity and coulombic efficiency even at high cell voltages. It was confirmed that recycled cathode materials (Examples 1 and 2) that achieved aluminum content reduction achieved specific capacity and initial coulombic efficiency values ​​close to those of commercially available cathode materials and their replicas, even under high cell voltage charge-discharge conditions.

[0369] [Table 10]

[0370]

[0371] (B) (Cyclic test of full cell at high cell voltage)

[0372] After rate testing at high voltage (2.5V~4.4V) for the full cell, charge and discharge at a specified number of cycles and high cell voltage are performed under the following conditions with constant current density.

[0373] Test temperature: 25℃

[0374] Battery cell voltage range: 2.5V~4.4V

[0375] Current density: 2C (300mA / g (based on the mass of the cathode material))

[0376] Number of loops: 500

[0377] The following are the measurement items.

[0378] (I) Specific capacity during the first cycle and discharge

[0379] (II) Specific capacity at the 200th cycle and discharge

[0380] (III) Maintenance of discharge specific capacity at the 200th cycle, with the 1st cycle as the baseline

[0381] (IV) Specific capacity at the 500th cycle and discharge

[0382] (V) Discharge capacity retention rate at the 500th cycle, with the 1st cycle as the baseline.

[0383] The results of the high-voltage cycle test of the full cell at the end of its lifespan, after 500 charge-discharge cycles, are recorded in Table 11.

[0384] According to the results in Table 11, the specific capacity and retention rate of the conventional recycled cathode material with high aluminum content (Comparative Example 1) were lower than those of other cathode materials. The recycled cathode materials with reduced aluminum content (Examples 1 and 2) showed increased specific capacity and higher specific capacity retention rate compared to conventional recycled cathode materials. In particular, the recycled cathode material with adjusted nickel and cobalt composition (Example 2), although initially having a low specific capacity, showed a slow increase in specific capacity through repeated charge-discharge cycles, demonstrating extremely high cycle stability. In the commercially available cathode material (Comparative Example 2), the specific capacity tended to increase up to 200 cycles, and a phenomenon different from the test at the normal voltage of 2.5V to 4.4V was observed in the high voltage cycling test (2.5V to 4.2V). Although the specific capacity of the recycled cathode material with reduced aluminum content after 500 cycles was lower than that of the commercially available cathode material, it was higher than that of the replica of the commercially available cathode material (Comparative Example 3), and the specific capacity retention rate after 500 cycles was also not low. That is, it can be seen that even under high voltage charging and discharging, the recycled cathode material with reduced aluminum content exhibits cycle durability comparable to that of cathode materials using virgin materials.

[0385] [Table 11]

[0386]

[0387] Explanation of reference numerals in the attached figures

[0388] 1: Positive current collector

[0389] 2: Positive electrode

[0390] 3: Separator

[0391] 4: Gasket

[0392] 5: Negative electrode

[0393] 6: Spacers

[0394] 7: Washers

[0395] 8: Negative current collector

[0396] 10: Lithium-ion secondary batteries.

Claims

1. A method for manufacturing a recycled cathode material precursor, comprising the following steps: (The method is based on a lithium-ion secondary battery as the object of processing.) The heat treatment process involves heating a lithium-ion secondary battery, which is the object to be treated, to obtain a heat-treated product. The crushing process involves crushing the heat-treated material to obtain crushed material. The grading and screening process involves grading and screening the crushed material to obtain fine-particle products. The acid leaching process involves leaching the fine-particle product with acid to obtain an acid leachate. In the iron removal process, an oxidant and an alkali are added to the acid leaching solution to obtain an iron-removed solution. The ion exchange process involves contacting the iron-removed liquid with a chelating resin to obtain the ion-exchanged liquid. In the alkali treatment step, alkali is added to the ion-exchange post-liquid to generate a precipitate; and The cleaning process involves washing the precipitate with water to obtain a recycled cathode material precursor.

2. The method for manufacturing the recycled cathode material precursor according to claim 1, wherein, After the grading and screening process, a magnetic separation process is performed to obtain magnetically adsorbed material by magnetic separation of the fine-particle product.

3. The method for manufacturing the recycled cathode material precursor according to claim 1, wherein, In the acid leaching process, sulfuric acid is used for the acid leaching process.

4. The method for manufacturing the recycled cathode material precursor according to claim 1, wherein, In the iron removal process, hydrogen peroxide aqueous solution is used as an oxidant, and the redox potential of the acid leaching solution is set to 500~750mV (Ag / AgCl) to carry out the iron removal process.

5. The method for manufacturing the recycled cathode material precursor according to claim 1, wherein, In the ion exchange process, an aminomethylphosphonic acid-based chelating resin is used as the chelating resin to remove aluminum ions.

6. The method for manufacturing the recycled cathode material precursor according to claim 1, wherein, An analytical step is performed to quantitatively analyze the metal elements contained in the ion-exchange liquid. If there is a difference between the results of the quantitative analysis of the metal elements contained in the ion-exchange liquid and the metal composition of the target regenerated cathode material precursor, a preparation step is performed to prepare the ion-exchange liquid.

7. The method for manufacturing the recycled cathode material precursor according to claim 1, wherein, An analytical step is performed to quantitatively analyze the metal elements contained in the ion-exchange liquid. If there is a difference between the results of the quantitative analysis of the metal elements contained in the ion-exchange liquid and the metal composition of the target regenerated cathode material precursor, an addition step is performed to add metal elements that are insufficient compared to the metal composition of the target regenerated cathode material precursor.

8. The method for manufacturing the recycled cathode material precursor according to claim 6, wherein, The prepared ion-exchange solution contains less than 100 mg / L of aluminum, less than 1 mg / L of copper, and less than 1 mg / L of iron.

9. The method for manufacturing the recycled cathode material precursor according to claim 7, wherein, The aluminum content in the ion exchange solution containing the aforementioned metal elements is less than 100 mg / L, the copper content is less than 1 mg / L, and the iron content is less than 1 mg / L.

10. A method for manufacturing a recycled cathode material, wherein, A regenerated cathode material is obtained by adding a specified metal compound to a regenerated cathode material precursor manufactured by the manufacturing method of any one of claims 1 to 9 and then calcining it.

11. The method for manufacturing the recycled cathode material according to claim 10, wherein, The metal compound is selected from one or more of lithium compounds, nickel compounds, cobalt compounds, and manganese compounds.

12. A method for using a recycled cathode material, comprising the following steps: Assembly process, assembling a lithium-ion secondary battery having the recycled positive electrode material as described in claim 10; and The activation process involves charging and discharging the lithium-ion secondary battery assembled in the assembly process.

Images