Method for separating transition metal from Li from compound comprising Li and transition metal

Abstract

The disclosed method for separating a transition metal and Li comprises: a step for reacting a compound containing Li and a transition metal with a carboxylic acid in water to obtain a slurry containing a first solution containing Li ions and a precipitate containing a carboxylic acid transition metal salt; and a step for separating the precipitate from the first solution. The transition metal is at least one element selected from the group consisting of Ni, Co, Mn, Ti, Fe, and Cu.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of priority to Japanese Patent Application No. 2022 - 174793, filed with the Japan Patent Office on October 31, 2022, and the entire contents of the above - mentioned patent application are incorporated herein by reference. Technical field

[0003] This application relates to a method for separating transition metals from Li in a compound containing Li and transition metals. Background art

[0004] From the perspective of protecting the global environment, "manufacturing technologies" that are environmentally friendly in various aspects are desired. In the manufacture of lithium - ion secondary batteries, legal regulations regarding carbon footprint (CFP) reduction and the proportion of recycled materials used have been achieved in the European region. This trend is considered to also have an impact on the United States and China. In particular, the positive electrode materials of lithium - ion secondary batteries are mainly composed of rare metals such as Ni, Co, and Li, and it is desired to recycle them and reuse them as raw materials for positive electrode materials.

[0005] For example, in the case of recycling black mass (broken electrode materials), from the perspective of CFP, the mainstream method is wet refining rather than dry refining (Patent Documents 1 - 3).

[0006] Prior art documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2016 - 186113

[0009] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2016 - 186118

[0010] Patent Document 3: Japanese Patent Application Laid - Open No. 2021 - 504885 Summary of the invention

[0011] Problems to be solved by the invention

[0012] In the conventional wet - refining process, lithium is recovered in the form of Li 2 CO 3 , and sodium sulfate is generated as a by - product. The economic rationality of such a process is low, and it is not suitable as a recycling process.

[0013] Means for solving the problems

[0014] One aspect of the present application relates to a method for separating a transition metal from Li, the separation method comprising: reacting a compound containing Li and a transition metal with a carboxylic acid in water to obtain a slurry containing a first solution containing Li ions and a precipitate containing a carboxylic acid transition metal salt; and separating the precipitate from the first solution, wherein the transition metal is at least one selected from Ni, Co, Mn, Ti, Fe, and Cu.

[0015] Advantages of the Invention

[0016] According to the present application, it is possible to improve the economic rationality in a method for separating a transition metal from Li from a compound containing Li and a transition metal.

[0017] The novel features of the present invention are described in the scope of the appended claims. However, the present invention should be more fully understood in both its constitution and content, together with other objects and features of the present invention, from the following detailed description with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flowchart showing the steps of a method for separating a transition metal from Li according to an embodiment of the present application. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present application will be described by way of example. However, the present application is not limited to the examples described below. In the following description, specific numerical values, materials, etc. may be exemplified. However, as long as the effects of the present application can be obtained, other numerical values, materials, etc. may also be applied. It should be noted that components other than the characteristic parts of the present application may be components known in the art. In this specification, when it is described as "a range from numerical value A to numerical value B", numerical value A and numerical value B are included in the range.

[0020] In the following description, when the lower limit and the upper limit of a numerical value regarding a specific physical property, condition, etc. are exemplified, as long as the lower limit is not greater than the upper limit, any one of the exemplified lower limits can be arbitrarily combined with any one of the exemplified upper limits. When multiple materials are exemplified, unless otherwise specified, one of them can be selected and used alone, or two or more of them can be used in combination.

[0021] In addition, the present application includes combinations of matters described in two or more claims arbitrarily selected from the multiple claims described in the scope of the appended claims. That is, as long as there is no technical contradiction, matters described in two or more claims arbitrarily selected from the multiple claims described in the scope of the appended claims can be combined.

[0022] A method for separating a transition metal from Li according to an embodiment of the present application (hereinafter also referred to as "separation method (ML)") includes at least the following three steps. It should be noted that in the separation method (ML), a solution containing a carboxylic acid transition metal salt and Li ions is obtained. Therefore, the separation method (ML) is both a method for manufacturing a carboxylic acid transition metal salt and a method for manufacturing a solution containing Li ions. Hereinafter, the transition metal is sometimes represented by "M".

[0023] <First Step>

[0024] The first step is a step of reacting a compound containing Li and a transition metal (hereinafter sometimes also referred to as "compound containing LiM") with a carboxylic acid in water to obtain a slurry containing a first solution containing Li ions and a precipitate containing a carboxylic acid transition metal salt. By using a carboxylic acid in the reaction with the compound containing LiM, advantages that cannot be obtained when using inorganic acids such as sulfuric acid and nitric acid are brought about. The first advantage is that since the carboxylic acid is a weak acid, corrosion of equipment is less likely to occur compared to the case of using inorganic acids.

[0025] The carboxylic acid can be used in the form of an aqueous carboxylic acid solution. The concentration of the aqueous carboxylic acid solution is not particularly limited. For example, from the viewpoints of improving the utilization rate of the carboxylic acid and enhancing the reactivity with the compound containing LiM, it is preferably used in the form of an aqueous carboxylic acid solution with a concentration of 0.2 mol / L to 0.6 mol / L. That is, in the step of obtaining the slurry, it is preferable to add the carboxylic acid to the compound containing LiM in water in the form of an aqueous carboxylic acid solution with a concentration of 0.2 mol / L to 0.6 mol / L.

[0026] From the viewpoint of promoting the formation of the precipitate containing the carboxylic acid transition metal salt, it is preferable to adjust the pH of the first solution to 5 or less. If the pH of the first solution further increases, the carboxylic acid transition metal salt gradually dissolves, and there is a tendency for the separation efficiency to decrease. The pH of the first solution can be adjusted to 0.5 or more and 5 or less, or can also be adjusted to 1 or more and 5 or less, or 3 or more and 5 or less.

[0027] When the compound containing LiM is, for example, LiMO 2 , and the carboxylic acid is, for example, formic acid, it is speculated that the reaction proceeds as follows. The reaction proceeds while generating hydrogen, and a formate of M is generated from LiMO 2 . However, the following chemical formula is an example, and a reaction that does not follow the following chemical formula may also occur.

[0028] HCOOH → H ＋ +COOH –

[0029] 2HCOOH+Ni 2+→Ni(COOH) 2 +H 2

[0030] Preferably, the precipitate containing the transition metal carboxylate is precipitated in such a manner that the median diameter (hereinafter referred to as "D50") at 50% cumulative volume of the volume-based particle size distribution is 4 μm or more, and further 6 μm or more. Thereby, in the following second step (filtration), the filterability can be improved and the separation efficiency is enhanced.

[0031] In order to generate the precipitate with an appropriate D50, in the step of obtaining the slurry, it is preferable to precipitate while stirring the compound containing LiM in water at 90 °C or lower. If the water temperature (i.e., the reaction temperature) becomes higher, there is a tendency for D50 to become smaller. From the same viewpoint, in the step of obtaining the slurry, it is preferable to precipitate the precipitate while stirring the compound containing LiM in water at 200 - 500 rpm.

[0032] The compound containing LiM can be an electrode material recovered from a secondary battery. As the compound containing LiM, for example, a broken electrode material called black mass can be used. In this case, the black mass can be mixed with a carboxylic acid in water.

[0033] The secondary battery containing the compound containing LiM as the electrode material can be a lithium-ion secondary battery, a lithium metal secondary battery, a all-solid-state battery, etc. For example, after performing a prescribed treatment on the secondary battery, it is crushed, and magnetic separation and screening are carried out to recover the electrode material.

[0034] The secondary battery can be, for example, an in-vehicle battery, a battery mounted in home appliances or laptop computers, etc., and is a used secondary battery that has been discarded due to its lifespan and then recycled. Alternatively, it can also be a defective secondary battery generated during the manufacturing process. The shape of the secondary battery is not particularly limited. For example, it can be a cylindrical, square, button-type, coin-type, soft-pack type secondary battery, etc.

[0035] The composite metal compound that can be used as the compound containing LiM can include composite metal oxides, composite metal sulfides, composite metal fluorides, composite metal hydrofluorides, composite metal polyanion compounds, etc. The crystal structure of the composite metal compound is not particularly limited, and examples include layered rock salt type, spinel type, olivine type, perovskite type, etc.

[0036] Among them, the method of the present application is useful when the composite metal compound is a composite metal oxide. Therefore, it is desirable that the main component of the compound containing LiM is a composite metal oxide. The so-called main component composite metal oxide is, for example, a composite metal oxide that accounts for 50% by mass or more, further 60% by mass or more, or 70% by mass or more, or 80% by mass or more of the compound containing LiM.

[0037] The transition metal M includes at least one selected from Ni, Co, Mn, Ti, Fe, and Cu. Among them, the method of the present application is useful when the proportion of Ni in the composite metal compound among the metal elements other than Li is high. The proportion of Ni in the composite metal compound among the metal elements other than Li can be 50 atomic% or more, can also be 60 atomic% or more, can also be 70 atomic% or more, or can also be 80 atomic% or more.

[0038] The compound containing LiM can be a composite metal compound containing Ni and a transition metal other than Ni. The composite metal oxide can further contain at least one third metal selected from Fe, Ti, Co, and Mn on the basis of containing Ni. In this case, the third metal can be separated from Li together with Ni.

[0039] The carboxylic acid can be either an aliphatic carboxylic acid or an aromatic carboxylic acid. Examples of the carboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid, behenic acid, acrylic acid, methacrylic acid, oleic acid, benzoic acid, cinnamic acid, naphthoic acid, salicylic acid, mandelic acid, resorcylic acid, maleic acid, phthalic acid, pyromellitic acid, resorcylic acid, succinic acid, glutaric acid, adipic acid, oxalic acid, maleic acid, fumaric acid, tartaric acid, citric acid, etc.

[0040] <Second step>

[0041] The second advantage of using a carboxylic acid in the dissolution of the compound containing LiM is that a carboxylic acid transition metal salt can be obtained in a state separated from Li ions. If the carboxylic acid transition metal salt is dissolved in an inorganic acid, for example, it can be recovered as a raw material for a new electrode material (positive electrode active material). On the other hand, most of the Li ions are separated in a state dissolved in the first solution that does not contain inorganic acid root anions such as sulfate ions and nitrate ions.

[0042] The second step is a step of separating the precipitate from the first solution. For example, the precipitate can be separated by filtration to separate the first solution as a filtrate from the precipitate. At this time, most of the transition metals are contained in the precipitate, and most of the Li ions are dissolved in the first solution. The third advantage of using a carboxylic acid in the dissolution of a compound containing LiNi is that almost all Li ions can be easily separated as the first solution by filtration. In addition, the fourth advantage is that inorganic acid root anions are not contained in the first solution. That is, by-products such as sulfates and nitrates are not generated.

[0043] The obtained transition metal carboxylate salts include nickel carboxylate, cobalt carboxylate, manganese carboxylate, titanium carboxylate, etc. If these salts are dissolved in sulfuric acid and the carboxylate anions are removed, sulfates can be obtained. For example, nickel sulfate, cobalt sulfate, manganese sulfate, etc. are useful as raw materials for electrode materials (positive active materials).

[0044] <Third Step>

[0045] The separation method (ML) may further include a step of purifying the first solution with an ion exchange resin to obtain a high-concentration Li solution. Since Li ions are not adsorbed on the cation exchange resin, the Li ion concentration can be increased as long as the first solution is passed through the cation exchange resin. In addition, since inorganic strong acids such as sulfuric acid and nitric acid are not used, the carboxylate anions can be removed by passing the first solution through the anion exchange resin. By using the cation exchange resin and the anion exchange resin, a concentrated lithium hydroxide solution can be obtained. By drying the concentrated lithium hydroxide solution, LiOH•H 2 O can be obtained. Since the ion exchange resin can be regenerated, LiOH•H 2 O can be obtained at low cost. LiOH•H 2 O is useful as a raw material for electrode materials (positive active materials).

[0046] Figure 1 is a flowchart summarizing the separation method (ML) of the transition metal and Li in the above-mentioned first step to the third step.

[0047] According to the separation method (ML), when the value obtained by dividing the amount of Li in the first solution by the sum of the amount of Li in the first solution and the amount of Li in the precipitate is set as C1, the Li recovery rate expressed as a percentage of C1×100 can be set to 85% or more, and further can be set to 90% or more or 93% or more.

[0048] According to the separation method (ML), when the value obtained by dividing the amount of transition metal in the precipitate by the total of the amount of transition metal in the first solution and the amount of transition metal in the precipitate is defined as C2, the recovery rate of the transition metal in terms of the percentage represented by C2×100 can be set to 80% or more, and further can be set to 85% or more or 90% or more.

[0049] It should be noted that the amounts of Li and transition metal in the first solution and the precipitate can be measured by inductively coupled plasma (ICP) analysis.

[0050] (Appendix)

[0051] The following technology is disclosed by the above description.

[0052] (Technology 1)

[0053] A method for separating transition metal and Li, the separation method comprising:

[0054] A step of reacting a compound containing Li and a transition metal with a carboxylic acid in water to obtain a slurry containing a first solution containing Li ions and a precipitate containing a carboxylic acid transition metal salt; and

[0055] A step of separating the precipitate from the first solution,

[0056] The above transition metal is at least one selected from Ni, Co, Mn, Ti, Fe, and Cu.

[0057] (Technology 2)

[0058] According to the method for separating transition metal and Li described in Technology 1, wherein the pH of the first solution is 5 or less.

[0059] (Technology 3)

[0060] According to the method for separating transition metal and Li described in Technology 1 or 2, wherein the precipitate is precipitated in such a manner that the median diameter at the cumulative volume of 50% in the volume-based particle size distribution becomes 4 μm or more.

[0061] (Technology 4)

[0062] According to the method for separating transition metal and Li described in any one of Technologies 1 to 3, wherein in the step of obtaining the slurry, the precipitate is precipitated while stirring the compound containing Li and the transition metal in water at 90° C. or lower at 200 to 500 rpm.

[0063] (Technology 5)

[0064] The method for separating a transition metal from Li according to any one of Technologies 1 to 4, wherein, in the step of obtaining the slurry, the carboxylic acid is added to the compound containing Li and the transition metal in the water in the form of an aqueous carboxylic acid solution having a concentration of 0.2 mol / L to 0.6 mol / L.

[0065] (Technology 6)

[0066] The method for separating a transition metal from Li according to any one of Technologies 1 to 5, wherein the compound containing Li and the transition metal is a composite metal oxide containing Li and the transition metal.

[0067] (Technology 7)

[0068] The method for separating a transition metal from Li according to any one of Technologies 1 to 6, wherein the compound containing Li and the transition metal is an electrode material recovered from a secondary battery.

[0069] (Technology 8)

[0070] The method for separating a transition metal from Li according to any one of Technologies 1 to 7, further comprising a step of purifying the first solution with an ion exchange resin to obtain a high-concentration Li solution.

[0071] (Technology 9)

[0072] The method for separating a transition metal from Li according to any one of Technologies 1 to 8, wherein formic acid is used as the carboxylic acid.

[0073] (Technology 10)

[0074] The method for separating a transition metal from Li according to any one of Technologies 1 to 9, wherein when the value obtained by dividing the amount of Li in the first solution by the sum of the amount of Li in the first solution and the amount of Li in the precipitate is set as C1, the Li recovery rate in terms of the percentage represented by C1×100 is 85% or more.

[0075] (Technology 11)

[0076] The method for separating a transition metal from Li according to any one of Technologies 1 to 10, wherein when the value obtained by dividing the amount of the transition metal in the precipitate by the sum of the amount of the transition metal in the first solution and the amount of the transition metal in the precipitate is set as C2, the transition metal recovery rate in terms of the percentage represented by C2×100 is 80% or more.

[0077] Although the present invention has been described with reference to the presently preferred embodiments, such disclosure should not be construed in a limiting sense. Various modifications and changes will be apparent to those skilled in the art belonging to the technical field of the present invention upon reading the above disclosure. Therefore, the scope of the appended claims should be construed to include all modifications and changes without departing from the true spirit and scope of the present invention.

[0078] [Examples]

[0079] Hereinafter, the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited to the following examples.

[0080] 《Example 1》

[0081] <First Step>

[0082] As a compound containing LiM, LiNi 0.8 Co 0.1 Mn 0.1 O 2 was prepared. 10 g of LiNi 0.8 Co 0.1 Mn 0.1 O 2 was added to 100 mL of water and stirred to disperse it. The stirring speed and water temperature were controlled as shown in Table 1. Thereafter, an aqueous formic acid solution with a concentration of 0.3 mol / L was added dropwise to the dispersion until pH = 3, causing LiNi 0.8 Co 0.1 Mn 0.1 O 2 to react with formic acid, and a slurry containing a first solution containing Li ions and a precipitate was prepared.

[0083] <Second Step>

[0084] Then, the precipitate was separated from the first solution (filtrate) by suction filtration. The precipitate was analyzed by X-ray diffraction (XRD), and as a result, the formation of nickel formate was confirmed as the main component. Since the D50 of the obtained precipitate was a sufficiently large value of 5.3 μm, the filterability was good.

[0085] [Evaluation]

[0086] The Li content, Ni content, and Co content in the first solution and the precipitate were analyzed by inductively coupled plasma (ICP) analysis, respectively.

[0087] When the value obtained by dividing the Li content in the first solution by the sum of the Li content in the first solution and the Li content in the precipitate was set as C1, the Li recovery rate expressed as C1 × 100 (%) was calculated.

[0088] When the value obtained by dividing the amount of Ni in the precipitate by the sum of the amount of Ni in the first solution and the amount of Ni in the precipitate is defined as C21, the Ni recovery rate expressed as C21 × 100 (%) is determined.

[0089] When the value obtained by dividing the amount of Co in the precipitate by the sum of the amount of Co in the first solution and the amount of Co in the precipitate is defined as C22, the Co recovery rate expressed as C22 × 100 (%) is determined.

[0090] The results are shown in Table 1. It should be noted that in Table 1 below, A1 corresponds to Example 1, A2 to A5 correspond to Examples 2 to 5 described later. In addition, B1 corresponds to Comparative Example 1 described later.

[0091] [Table 1]

[0092]

[0093] 《Example 2》

[0094] Except that the concentration, stirring speed, and water temperature of the aqueous formic acid solution are controlled as shown in Table 1 in the first step, the same separation operation as in Example 1 is performed, and the same evaluation is carried out. The results are shown in Table 1. The D50 of the obtained precipitate is a sufficiently large value of 5.8 μm, so the filterability is good.

[0095] 《Example 3》

[0096] Except that the aqueous formic acid solution is added dropwise to the first solution until the pH = 5 in the first step, the same separation operation as in Example 1 is performed, and the same evaluation is carried out. The results are shown in Table 1. The D50 of the obtained precipitate is a sufficiently large value of 6.3 μm, so the filterability is good.

[0097] 《Example 4》

[0098] Except that the concentration, stirring speed, and water temperature of the aqueous formic acid solution are controlled as shown in Table 1 in the first step, the same separation operation as in Example 1 is performed, and the same evaluation is carried out. The results are shown in Table 1. The D50 of the obtained precipitate is small, and good filterability cannot be obtained.

[0099] 《Example 5》

[0100] Except that the aqueous formic acid solution is added dropwise to the first solution until the pH = 5 in the first step, the same separation operation as in Example 4 is performed, and the same evaluation is carried out. The results are shown in Table 1. The D50 of the obtained precipitate is small, and good filterability cannot be obtained.

[0101] 《Comparative Example 1》

[0102] In the first step, an aqueous formic acid solution was added dropwise until the pH of water reached pH = 6. As a result, no precipitate was formed even after 3 days.

[0103] As shown in Table 1, it can be understood that in Examples 1 to 5, the recovery rates of both the transition metal (M) and Li are greater than 90%. In addition, it can be understood that the D50 of the precipitate can be controlled within a desired range according to the conditions of the step for obtaining the slurry.

[0104] Industrial applicability

[0105] The method for separating a transition metal from Li in a compound containing Li and a transition metal according to the present application is particularly useful as a process for recovering an electrode material for a secondary battery, has a low treatment cost, a small environmental burden, and excellent economic rationality.

Claims

1. A method for separating a transition metal from Li, the method comprising: a step of reacting a compound containing Li and a transition metal with a carboxylic acid in water to obtain a slurry containing a first solution containing Li ions and a precipitate containing a carboxylic acid transition metal salt; and a step of separating the precipitate from the first solution, The transition metal is at least one selected from the group consisting of Ni, Co, Mn, Ti, Fe and Cu.

2. The method for separating transition metals from Li according to claim 1, in, The pH of the first solution is 5 or less.

3. The method for separating transition metal and Li according to claim 1, in, The precipitate is precipitated so that the median diameter at 50% of the cumulative volume of the volume-based particle size distribution becomes 4 μm or more.

4. The method for separating transition metals from Li according to claim 1, in, In the step of obtaining the slurry, the precipitate is precipitated while the compound containing Li and the transition metal is stirred at 200 rpm to 500 rpm in water at 90° C. or lower.

5. The method for separating transition metals from Li according to claim 1, in, In the step of obtaining the slurry, the carboxylic acid is added to the compound containing Li and the transition metal in the water in the form of a carboxylic acid aqueous solution having a concentration of 0.2 mol / L to 0.6 mol / L.

6. The method for separating transition metal and Li according to claim 1, in, The compound containing Li and a transition metal is a composite metal oxide containing Li and a transition metal.

7. The method for separating transition metal and Li according to claim 1, in, The compound containing Li and a transition metal is an electrode material recovered from a secondary battery. 8 . The method for separating a transition metal and Li according to claim 1 , further comprising the step of purifying the first solution with an ion exchange resin to obtain a high-concentration Li solution.

9. The method for separating transition metal and Li according to claim 1, in, Formic acid was used as the carboxylic acid.

10. The method for separating a transition metal and Li according to any one of claims 1 to 9, in, When a value obtained by dividing the amount of Li in the first solution by the total amount of Li in the first solution and the amount of Li in the precipitate is defined as C1, the Li recovery rate expressed as a percentage expressed as C1×100 is 85% or more.

11. The method for separating a transition metal and Li according to any one of claims 1 to 9, in, When C2 is a value obtained by dividing the amount of transition metal in the precipitate by the sum of the amount of transition metal in the first solution and the amount of transition metal in the precipitate, the recovery rate of the transition metal expressed as a percentage by C2×100 is 80% or more.

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