Method for manufacturing electrode active material, method for manufacturing electrode, method for manufacturing lithium ions, and electrode active material, lithium ion battery

Abstract

An electrode active material according to the present invention is produced by performing a heat treatment after adding a plurality of metal salts which each contain metal components that are Li, Ni, Co, and Mn or Al to black mass that is obtained by processing used lithium ion batteries, so that the black mass and the metal salts are reacted with each other. It is preferable that the addition amount of the metal salts is 10-25 parts by weight relative to 100 parts by weight of the black mass. This lithium ion battery has a positive electrode 4, a negative electrode 6, and an electrolyte 8. A positive electrode active material 3, which serves as a main body of the positive electrode 4, is formed of an electrode active material that is produced as described above. By directly using the black powder of the black mass as described above, it is possible to achieve an electrode active material, an electrode, and a lithium ion battery, which have high practicality and are capable of ensuring desired battery characteristics without requiring much time and effort such as recovery of metal salts or the like from black mass and purification of the metal salts or the like.

Description

【Technical Field】 【0001】 The present invention relates to a method for manufacturing an electrode active material, an electrode Manufacturing method , and a lithium ion Method for manufacturing, as well as electrode active material, lithium-ion battery . Specifically, it relates to a method for manufacturing an electrode active material that produces an electrode active material using black mass, an electrode using the electrode active material manufactured by this manufacturing method Manufacturing method , and a lithium ion battery in which a positive electrode active material is formed of the electrode active material A method for manufacturing a lithium-ion battery, and an electrode active material produced by the above manufacturing method. . 【Background Art】 【0002】 With the expansion of the market for portable electronic devices such as mobile phones, notebook computers, and tablet terminals, the development of secondary batteries as cordless power sources for these electronic devices has been actively carried out. In addition, against the backdrop of global warming and the depletion of oil resources, the development of electric vehicles and hybrid vehicles using secondary batteries as power sources has also been actively carried out. 【0003】 Under such circumstances, secondary batteries that use alkali metal ions such as lithium ions as charge carriers and utilize electrochemical reactions accompanying the transfer of charges have been developed. In particular, lithium ion batteries with high energy density are now widely popular. 【0004】 Among the components of a lithium ion battery, the electrode active material is a substance that directly contributes to the battery electrode reactions such as the charge reaction and the discharge reaction. Since charging and discharging are performed by utilizing the insertion reaction and the desorption reaction of lithium ions with respect to the electrode active material, it plays a central role in lithium ion batteries. 【0005】 In this type of lithium ion battery, in the initial stage of development, LiCoO2 (lithium cobaltate) was used as the electrode active material, particularly the positive electrode active material. However, due to the high cost of Co and the demands for higher capacity and lower cost accompanying the expansion of battery applications, in recent years, ternary materials in which a part of Co is replaced with Ni or Mn have attracted attention, and lithium ion batteries using such ternary materials as the positive electrode active material have been actively studied and developed. 【0006】 However, while the demand for lithium-ion batteries is expected to increase further in the future, Li and the ternary materials mentioned above—Co, Ni, and Mn—are all rare metals, and there is a risk that securing a supply of raw materials may become difficult in the future. 【0007】 Therefore, in recent years, a technology has been attracting attention that attempts to recover lithium-ion battery materials from the black powder known as "black mass," which is produced by processing used lithium-ion batteries, and recycle them. 【0008】 For example, Patent Document 1 proposes a method for recovering and refining valuable metals, including one or more of Ni, Mn, Co, and Li, from black mass obtained from the recycling of lithium-ion batteries. 【0009】 In this Patent Document 1, black mass is leached with a reducing acid to produce an acidic leaching slurry containing valuable metals (Ni, Mn, Co) and impurities, as well as insoluble substances. After separating and removing the insoluble substances from the acidic leaching slurry, the pH of the acidic leaching slurry is adjusted to precipitate and remove impurities. Next, residual impurities in the acidic leaching slurry are removed using an ion exchange resin, and the ion exchange resin is regenerated using a Li-based solution. A mixed precipitate slurry is then prepared using the Li-based solution. The pH of the acidic leaching slurry is then adjusted to separate it into a mixed precipitate containing valuable metals and a Li-containing solution. Metal salts that serve as precursors for ternary cathode active materials are recovered from the mixed precipitate, and Li2CO3, which serves as a Li source, is recovered by salt decomposition and crystallization of the Li-containing solution. 【0010】 Thus, Patent Document 1 attempts to recover a precursor of a ternary cathode active material containing Li and Li2CO3 from black mass through a chemical process, thereby reusing the resources. 【0011】 Furthermore, Patent Document 2 also proposes a method for extracting metals from the black mass of lithium-ion batteries. 【0012】 Specifically, in Patent Document 2, the non-metallic material fraction is separated from the black mass to recover the black mass containing the anode material and cathode material. Next, a gas containing sulfur dioxide and molecular oxygen is added as an extractant to a sulfuric acid-containing solution to perform acid leaching, dissolving the cathode material in the black mass and recovering the leached solution containing the cathode material. The initial fraction of metallic material is then separated from the leached solution to recover the main fraction containing at least one of Mn, Co, Ni, and Li. 【0013】 Thus, in Patent Document 2, after removing non-metallic components from black mass in a pretreatment, sulfuric acid and an extractant are used to sequentially separate and recover the initial fraction of metallic material from each leaching solution containing cathode material, thereby attempting to reuse the resource. 【0014】 Furthermore, Patent Document 3 proposes a method for recovering a group of metals consisting of at least two types of metals, Co, Ni, and Mn, and impurities, from a waste battery, waste cathode material, or mixture thereof, which includes removing impurities from the waste battery, waste cathode material, or mixture thereof, and then recovering the group of metals as a mixture of metal salts. 【0015】 In this Patent Document 3, a leachate is prepared by sulfuric acid leaching of waste batteries, waste cathode material, or mixtures thereof. If impurities such as Fe, Cr, Cu, F, and C are present, the pH of the leachate is adjusted to precipitate and remove the impurities, or they are separated into the solvent by solvent extraction. Then, impurities are removed from the leachate by solid-liquid separation, and metal salts of Co, Ni, and Mn are recovered. This makes it possible to recover waste batteries and waste cathode material as a mixture of metal salts from the leachate without separating them into individual metal salts of Mn, Co, and Ni. Therefore, the effort of individual separation is eliminated, and the cost of recycling cathode material is reduced. 【0016】 As described above, Patent Documents 1 to 3 all attempt to remove impurities from black mass (waste batteries, waste cathode material) using a wet process, then separate and recover metal salts or mixtures thereof or metal fractions (hereinafter referred to as "metal salts, etc.") and recycle them for use in the manufacture of new batteries. [Prior art documents] [Patent Documents] 【0017】 [Patent Document 1] Japanese Patent Publication No. 2023-174586 (Claim 11, paragraphs

[0028] to

[0029] , Figure 1, etc.) [Patent Document 2] Japanese Patent Publication No. 2024-516955 (Claim 1, paragraphs

[0063] to

[0066] , Figure 2a, Figure 2b, etc.) [Patent Document 3] Japanese Patent Publication No. 2014-156649 (Claim 1-3, paragraphs

[0029] ,

[0050] ) [Overview of the Initiative] [Problems that the invention aims to solve] 【0018】 However, the aforementioned Patent Documents 1 to 3 were impractical because the processing steps for extracting, separating, and recycling battery materials from black mass were complicated, and the equipment required was expensive, resulting in high costs. 【0019】 This invention has been made in view of these circumstances, and provides a method for producing an electrode active material that can be obtained without the need for the time and effort of recovering and purifying metal salts etc. from black mass, and that can reuse resources to ensure desired battery characteristics, and an electrode using the electrode active material produced by this method. Manufacturing method , and lithium-ion batteries using this electrode active material as the positive electrode active material. A method for manufacturing a lithium-ion battery, and an electrode active material and lithium-ion battery produced by the above manufacturing method. The purpose is to provide. [Means for solving the problem] 【0020】 The inventors have conducted diligent research to achieve the above objective and have found that metal salts containing Li, Co, Ni, and Mn or Al, which can constitute electrode active materials, can be used in black mass. predetermined amount Add, At a specified temperature We have discovered that by performing heat treatment, black mass and metal salts react, causing the metal components to bond with the black mass, thereby obtaining a highly practical electrode active material that ensures the desired battery characteristics. 【0021】 The present invention is based on such findings, and the method for producing an electrode active material according to the present invention involves processing used lithium-ion batteries to obtain black mass, and then adding a plurality of metal salts each containing Li, Ni, Co, and Mn or Al metal components. A total of 10 to 50 parts by weight are added to 100 parts by weight of the aforementioned black mass, and heat treatment is performed at a temperature of 700 to 900°C. The present invention is characterized by producing an electrode active material by reacting the aforementioned black mass with the aforementioned metal salt. 【0022】 This eliminates the need to recover metal salts and metal components from black mass, allowing for the effective utilization of used lithium-ion batteries and enabling the acquisition of electrode active materials with desirable battery performance at a low cost and high practicality. 【0023】 Furthermore, in the method for producing the electrode active material of the present invention, it is more preferable that the amount of metal salt added is 10 to 25 parts by weight per 100 parts by weight of the black mass. 【0024】 This makes it possible to obtain an electrode active material with desirable battery performance and practical value simply by adding a small amount of a predetermined metal salt to black mass. 【0025】 Furthermore, the method for producing the electrode active material of the present invention That was, It is preferable to perform the heat treatment for 1 to 2 hours. 【0026】 Like this Hot By appropriately adjusting the processing time, electrode active materials with desired battery performance can be easily produced. 【0027】 Furthermore, in the method for manufacturing the electrode active material of the present invention, when the plurality of metal salts are synthesized by mixing these plurality of metal salts with each other, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2 (hereinafter, also referred to as "NMC111"). LiNi 0.4 Mn 0.3 Co 0.3 O2 (hereinafter, also referred to as "NMC433"). LiNi 0.5 Mn 0.2 Co 0.3 O2 (hereinafter, also referred to as "NMC523"). LiNi 0.5 Mn 0.3 Co 0.2 O2 (hereinafter, also referred to as "NMC532"). LiNi 0.6 Mn 0.2 Co 0.2 O2 (hereinafter, also referred to as "NMC622"). LiNi 0.8 Mn 0.1 Co 0.1 O2 (hereinafter, also referred to as "NMC811"). LiNi 0.8 Co 0.15 Al 0.05 O2 (hereinafter, also referred to as "NCA"), and a lithium-excess composition represented by the general formula Li 1+x Ni 2 / (3+3y) Mn 2x / (3+3y) Co 2 / (3+3y) O2 (where x > 0 and y is a positive integer) (hereinafter, also referred to as "lithium-excess NMC composition"). It is preferable to adjust the blending ratio and add it to the black mass so that one type of oxide selected from the group can be formed. 【0028】 When the plurality of metal salts are thus mixed and synthesized, by appropriately blending the respective metal components of Ni, Co, and Mn or Al so as to have a predetermined ratio, an electrode active material having desired battery performance according to various applications can be produced at low cost. 【0029】 In addition, the electrode according to the present invention is characterized by having an electrode active material manufactured by the manufacturing method described above. 【0030】 As a result, the electrode active material is manufactured using black mass directly, allowing for efficient resource recycling and enabling the acquisition of new and useful battery electrodes at low cost. 【0031】 Furthermore, the present invention related Electrode Manufacturing method teeth, It is characterized by having an electrode active material produced by the above manufacturing method, and also The electrode active material is characterized by having a layered rock salt type crystal structure. 【0032】 As a result, the electrode active material has a crystalline structure in which Li is arranged between multiple metal oxide layers containing Ni, Co, and Mn or Al. This allows the battery reaction to proceed easily through the insertion and removal of Li ions by two-dimensional diffusion of Li, making it possible to obtain the desired lithium-ion battery. The electrode active material according to the present invention is formed from a Li-based metal oxide containing black mass obtained by processing used lithium-ion batteries and putting them into direct use, wherein the Li-based metal oxide is heat-treated together with the black mass, with a total of 10 to 50 parts by weight of multiple metal salts containing Li, Ni, Co, and Mn or Al per 100 parts by weight of the black mass, and it is preferable that the total amount of the multiple metal salts per 100 parts by weight of the black mass is 10 to 25 parts by weight. Furthermore, the electrode active material of the present invention is LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O 2 Li Limited 0.4 Mn 0.3 Co 0.3 O 2 Li Limited 0.5 Mn 0.3 Co 0.2 O 2 Li Limited 0.5 Mn 0.2 Co 0.3 O 2 Li Limited 0.6 Mn 0.2 Co 0.2 O 2 Li Limited 0.8 Mn 0.1 Co 0.1 O 2 Li Limited 0.8 Co0.15 Al 0.05 O 2 , and the general formula Li 1+x Ni 2 / (3+3y) Mn 2x / (3+3y) Co 2 / (3+3y) O 2 Preferably, it is formed by one selected from the group consisting of (where x > 0 and y is a positive integer). 【0033】 The lithium-ion battery according to the present invention is a lithium-ion battery having a positive electrode, a negative electrode, and an electrolyte, which repeatedly performs charge and discharge reactions by a battery electrode reaction using lithium ions as a charge carrier, characterized in that the positive electrode active material, which is the main component of the positive electrode, is formed from an electrode active material manufactured by the manufacturing method described above. 【0034】 Since the positive electrode active material is formed from the electrode active material manufactured by the above-described manufacturing method, it is possible to obtain a novel and useful lithium-ion battery that contributes to resource recycling by effectively utilizing used lithium-ion batteries, without the need to recover and purify metal salts from black mass. 【0035】 Furthermore, in the lithium-ion battery of the present invention, it is preferable that the negative electrode active material, which is the main component of the negative electrode, is made of lithium metal. 【0036】 By forming the negative electrode active material with lithium metal in this way, it becomes possible to obtain a lithium-ion battery with a higher energy density compared to when carbon-based materials are used. ru. [Effects of the Invention] 【0037】 According to the electrode active material of the present invention, an electrode active material is produced by adding multiple metal salts containing Li, Ni, Co, Mn, or Al to black mass obtained by processing used lithium-ion batteries, heat-treating the mixture, and reacting the black mass with the metal salts. This eliminates the need to recover and purify metal salts from the black mass as in conventional methods, effectively utilizing resources contained in used lithium-ion batteries, and obtaining a novel and useful electrode active material with desirable battery performance at low cost and high practicality. 【0038】 Furthermore, since the amount of the metal salt added is 10 to 25 parts by weight per 100 parts by weight of the black mass, the desired electrode active material can be obtained by simply adding a small amount of the predetermined metal salt to the black mass and performing heat treatment at a temperature of 700 to 900°C for 1 to 2 hours. 【0039】 Furthermore, the multiple metal salts are added to the black mass with their blending ratios adjusted so that when these multiple metal salts are mixed and synthesized together, one oxide selected from the group consisting of NMC111, NMC433, NMC523, NMC532, NMC622, NMC811, NCA, and lithium-rich NMC compositions can be formed. This makes it possible to obtain novel and useful electrode active materials for various applications at low cost. 【0040】 According to the electrode of the present invention, since it has an electrode active material manufactured by the manufacturing method described above, resource recycling can be carried out efficiently, and it becomes possible to obtain new and useful battery electrodes at low cost. 【0041】 Furthermore, because this electrode active material has a layered rock salt crystal structure, the battery reaction involving the insertion and removal of Li ions by two-dimensional diffusion of Li proceeds easily, making it possible to obtain a desired lithium-ion battery. 【0042】 According to the lithium-ion battery of the present invention, the lithium-ion battery has a positive electrode, a negative electrode, and an electrolyte, and undergoes repeated charge-discharge reactions by a battery electrode reaction using lithium ions as a charge carrier. Since the positive electrode active material, which is the main component of the positive electrode, is formed from an electrode active material manufactured by the above-described manufacturing method, it is possible to easily and inexpensively obtain a novel and useful lithium-ion battery that contributes to the recycling of used lithium-ion batteries. 【0043】 Furthermore, since the negative electrode active material, which is the main component of the negative electrode, is made of lithium metal, it is possible to obtain a lithium-ion battery with a higher energy density compared to when the negative electrode is made of a carbon-based material. [Brief explanation of the drawing] 【0044】 [Figure 1] This is a schematic cross-sectional view showing one embodiment of the lithium-ion battery according to the present invention. [Figure 2] The secondary electron images of sample number 1 (an example of the present invention) are shown, with (a) being at a magnification of 1000x and (b) at a magnification of 5000x. [Figure 3] The secondary electron images of sample number 2 (black mass) are shown, with (a) at a magnification of 1000x and (b) at a magnification of 5000x. [Figure 4] The secondary electron images of sample number 4 (reference sample) are shown, with (a) at a magnification of 1000x and (b) at a magnification of 5000x. [Figure 5] This is a profile showing the elemental mapping analysis of sample number 1 above. [Figure 6] This is a profile showing the elemental mapping analysis of sample number 2 mentioned above. [Figure 7] This is a profile showing the elemental mapping analysis of sample number 4 mentioned above. [Figure 8] This profile shows the X-ray diffraction spectra of samples 1, 2, and 4. [Figure 9] This figure shows one example of the temperature dependence of the cycle characteristics. [Modes for carrying out the invention] 【0045】 Next, embodiments of the present invention will be described in detail. 【0046】 In one embodiment of the present invention, an electrode active material is produced by adding a plurality of metal salts containing Li, Ni, Co, and Mn or Al metal components to black mass obtained by processing spent lithium-ion batteries, heat-treating the mixture, and reacting the black mass with the metal salts. 【0047】 In this way, electrode active materials can be manufactured simply by adding multiple metal salts, which serve as the metal source for the electrode active material, to black mass and heat-treating it. This eliminates the need to recover metal salts and other materials from the black mass, allowing for the effective utilization of used lithium-ion batteries and enabling the production of low-cost, highly practical, high-capacity, and high-performance electrode active materials. 【0048】 In other words, as mentioned in the [Background Technology] section, the materials that make up lithium-ion batteries, especially the Li, Ni, Co, and Mn that make up the electrode active materials, are all rare metals, and there is a risk that securing their supply will become difficult in the future. Therefore, in recent years, attempts have been made to use "black mass" obtained by processing used lithium-ion batteries to recover useful resources and use them in the manufacture of new batteries. 【0049】 This black mass is a black powder obtained by discharging used lithium-ion batteries, heating and drying them to evaporate the electrolyte, then crushing and pulverizing them, extracting and removing unwanted impurity elements, and sieving them. 【0050】 However, although this black mass can be recycled and used in the manufacture of new batteries by separating and recovering it into metal salts and other precursors for electrode active materials, the extraction and separation processes required to recycle the raw materials were complicated, resulting in high recycling costs, low efficiency, and poor practicality. 【0051】 Therefore, in this embodiment, although trace amounts of impurities such as C, F, Si, and Al originating from lithium-ion batteries are inevitably mixed into the black mass, it contains a large amount of oxides of Ni, Co, and Mn that constitute the electrode active material. Thus, multiple metal salts containing Li, Ni, Co, and Mn or Al are added to the black mass and heat-treated, causing the black mass and metal salts to react, thereby producing a novel and useful electrode active material. 【0052】 Here, the amount of metal salt added is not particularly limited as long as it is a small amount that is suitable for the invention's objectives of cost reduction and resource recycling. For example, 10 to 25 parts by weight per 100 parts by weight of black mass is preferred. That is, if the amount of metal salt added is less than 10 parts by weight per 100 parts by weight of black mass, the black mass content will be relatively high, and it may not be possible to obtain sufficient battery performance in terms of cycle characteristics, etc. On the other hand, if the amount of metal salt added exceeds 25 parts by weight per 100 parts by weight of black mass, the amount of metal salt containing rare metals such as Co and Ni will be large, which may lead to higher costs, and moreover, as shown in the examples described later, it may actually lead to a deterioration of cycle characteristics, which is undesirable. 【0053】 Furthermore, the blending ratio of multiple metal salts is not particularly limited as long as the metal salts contain Li, Ni, Co, and Mn or Al. However, the blending ratio can be adjusted and added so that a specific lithium-containing metal oxide can be formed when the metal salts are mixed and heat-treated for synthesis. 【0054】 In other words, multiple metal salts can be added to black mass by adjusting their mixing ratios so that, when the metal salts are mixed together and heat-treated to synthesize them, for example, NMC111, NMC433, NMC523, NMC532, NMC622, NMC811, NCA, or lithium-rich NMC compositions can be formed. 【0055】 Here, the lithium-rich NMC composition is specifically Li 1.2 Ni 0.13Mn 0.54 Co 0.13 O2, Li 1.06 Ni 0.22 Mn 0.45 Co 0.22 O2, Li 1.11 Ni 0.17 Mn 0.50 Co 0.17 O2, Li 1.14 Ni 0.13 Mn 0.54 Co 0.13 O2, Li 1.17 Ni 0.095 Mn 0.57 Co 0.095 Examples include O2, etc. 【0056】 Furthermore, the types of metal salts used are not particularly limited as long as each metal salt contains Li, Ni, Co, and either Mn or Al. For example, Li2CO3 can be used as a Li source, Ni(NO3)2·6H2O as a Ni source, (CH3COO)2Mn·4H2O as a Mn source, Co(NO3)2·6H2O as a Co source, and AlCl3·6H2O as an Al source. 【0057】 Furthermore, while there are no particular limitations on the heat treatment temperature, it is generally preferable to carry it out in the range of 700°C to 900°C. At low temperatures below 700°C, sufficient crystallization may not occur, making it difficult to obtain the desired capacity density. On the other hand, at high temperatures exceeding 900°C, crystallization may proceed excessively, inhibiting the movement of Li ions and potentially leading to a deterioration of the cycle characteristics. 【0058】 Furthermore, while there are no particular restrictions on the heat treatment time, it is preferable to perform it for about 1 to 2 hours. If the heat treatment time is too short (less than 1 hour), sufficient crystallization may not occur, making it difficult to obtain the desired capacity density. On the other hand, if the heat treatment time exceeds 2 hours, crystallization may proceed excessively, inhibiting the movement of Li ions and potentially leading to a deterioration of the cycle characteristics. 【0059】 As will be clear from the examples described later, the electrode active material has a layered rock salt crystal structure. Specifically, layers of metal oxide containing Ni, Co, and Mn or Al are formed at regular intervals, with lithium layers interposed between the metal oxide layers. Li ions in the lithium layers diffuse two-dimensionally, causing insertion and desorption reactions, which then perform charging and discharging. 【0060】 Furthermore, simply adding lithium salts such as Li2CO3 to black mass and heat-treating it results in a significant deterioration of cycle characteristics compared to black mass alone, which is undesirable. In other words, to obtain the desired electrode active material, it is considered essential to add metal salts containing Ni, Co, and Mn or Al, heat-treat them, and form a metal oxide layer with appropriately improved crystallinity. 【0061】 As described above, the method for producing electrode active materials in this embodiment involves adding multiple metal salts containing Li, Ni, Co, and Mn or Al metal components to black mass obtained by processing used lithium-ion batteries, and then heat-treating the black mass and metal salts to produce electrode active materials. Therefore, unlike conventional methods, there is no need to recover metal salts or metal components from the black mass, allowing for the effective utilization of used lithium-ion batteries and enabling the production of electrode active materials with practical battery performance at a low cost. 【0062】 Next, we will describe a lithium-ion battery using the aforementioned electrode active material. 【0063】 Figure 1 is a schematic cross-sectional view showing a lithium-ion battery according to the present invention, in which the electrode active material is used as the positive electrode active material. 【0064】 This lithium-ion battery has a lid-shaped positive electrode current collector 1 made of Al or the like, which also serves as the positive electrode case, and a bottomed cylindrical negative electrode current collector 2 made of Cu or the like, which also serves as the negative electrode case. A positive electrode active material layer 3 is formed on one main surface of the positive electrode current collector 1, and the positive electrode current collector 1 and the positive electrode active material layer 3 constitute the positive electrode 4. A negative electrode active material layer 5 is formed in the center of the bottom of the negative electrode current collector 2, and the negative electrode current collector 2 and the negative electrode active material layer 5 constitute the negative electrode 6. A separator 7 made of a porous sheet or film such as a microporous membrane, woven fabric, or nonwoven fabric is placed between the positive electrode active material layer 3 and the negative electrode active material layer 5, and the internal space is filled with electrolyte 8. The positive electrode current collector 1 and the negative electrode current collector 2 are sealed together via a gasket 9. 【0065】 Furthermore, the negative electrode active material used in the negative electrode active material layer 5 is not particularly limited, and can be lithium metal, carbon-based materials such as graphite and graphene, or lithium titanate, but from the viewpoint of obtaining high energy density, lithium metal is preferred. 【0066】 Next, an example of a manufacturing method for the lithium-ion battery described above will be described in detail. 【0067】 First, the positive electrode active material is formed into an electrode shape. For example, the positive electrode active material is mixed with a conductive additive and a binder, a solvent is added to form a slurry, and this slurry is coated onto the positive electrode current collector 1 using any coating method and dried to form a positive electrode active material layer 3 on one main surface of the positive electrode current collector 1, thereby obtaining the positive electrode 4. 【0068】 Here, the conductive additive is not particularly limited, and for example, conductive carbon such as graphite, carbon black, and acetylene black, carbon fibers such as carbon nanotubes and carbon nanohorns, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyacene can be used. Furthermore, two or more types of conductive additives can be mixed and used. 【0069】 Furthermore, the binder is not particularly limited, and various resins such as polyvinylidene fluoride, polyethylene, polyhexafluoropropylene, polytetrafluoroethylene, polyethylene oxide, and carboxymethylcellulose can be used. 【0070】 Furthermore, the solvent is not particularly limited, and for example, basic solvents such as N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylformamide, propylene carbonate, diethyl carbonate, dimethyl carbonate, and γ-butyrolactone, non-aqueous solvents such as acetonitrile, tetrahydrofuran, nitrobenzene, and acetone, protic solvents such as methanol and ethanol, and even water can be used. 【0071】 Furthermore, the type of organic solvent, the mixing ratio of organic compounds to organic solvents, the type of additives and their amounts can be set arbitrarily. 【0072】 Next, a negative electrode active material layer 5 is placed in the center of the bottom of a bottomed cylindrical negative electrode current collector 2 to form a negative electrode 6. This negative electrode 6 is then impregnated with the electrolyte 8 to allow it to permeate the negative electrode 6. Furthermore, the positive electrode 4 is impregnated with the electrolyte 8, and then a separator 7 impregnated with the electrolyte 8 is placed inside the negative electrode case, after which the electrolyte 8 is injected into the internal space. Finally, a gasket 9 is placed around the periphery, and the negative electrode current collector 2 and the positive electrode current collector 1 are fixed together using a crimping machine or the like to seal the exterior, thereby manufacturing a lithium-ion battery. 【0073】 Furthermore, the electrolyte 8 is interposed between the positive electrode 4 and the opposing negative electrode 6 to transport charge carriers between the two electrodes. As such an electrolyte 8, an electrolyte solution obtained by dissolving an electrolyte salt in an organic solvent, a polymer-based electrolyte solution obtained by adding a polymer such as polyethylene oxide to this, or an ionic liquid-based electrolyte solution obtained by dissolving an electrolyte salt using an ionic liquid such as 1-ethyl-3-methylimidazolium tetrafluoroborate can be used. 【0074】 Here, various lithium salts such as LiPF6, LiClO4, LiBF4, F2LiNO4S2, C4F9LiO3S, LiN(CF3SO2)2, LiCF3SO3, C4F9LiO3S, F2LiNO4S2, Li(CF3SO2)2C, LiH2PO4, LiCl, and (CH3CO)2Li can be used as the electrolyte salt. 【0075】 Furthermore, as organic solvents, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, dimethoxyethane, and mixtures thereof can be used. 【0076】 Furthermore, solid electrolytes may be used as the electrolyte. Both inorganic and polymeric solid electrolytes can be used. An example of an inorganic solid electrolyte is Li7La3Zr2O 12 Oxide-type solid electrolytes such as (La,Ti)TiO3 and Li 10 GeP2S 12 Examples of sulfide-based solid electrolytes include polypyridene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-ethylene copolymer, and various other copolymers. 【0077】 Thus, the lithium-ion battery described above has a positive electrode 4, a negative electrode 6, and an electrolyte 8, and is a lithium-ion battery that repeatedly undergoes charge and discharge reactions by a battery electrode reaction using lithium ions as a charge carrier. Since the positive electrode active material 3, which is the main component of the positive electrode 4, is formed from an electrode active material manufactured by the above-described manufacturing method, it is possible to easily obtain a new and useful lithium-ion battery that contributes to resource recycling by effectively utilizing used lithium-ion batteries at low cost. 【0078】 It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. For example, although a cylindrical lithium-ion battery has been described in this embodiment, it goes without saying that the battery shape is not particularly limited, and it can be applied to prismatic, sheet, coin-type, etc. Also, the casing method is not particularly limited, and metal cases, molded resin, aluminum laminate film, etc. may be used. 【0079】 Next, specific embodiments of the present invention will be described. [Examples] 【0080】 [Sample preparation] (Sample number 1) First, we procured black char from Kawashima Co., Ltd. We also prepared powders of Li2CO3 as a Li source, Ni(NO3)2·6H2O as a Ni source, (CH3COO)2Mn·4H2O as a Mn source, and Co(NO3)2·6H2O as a Co source. 【0081】 Then, Li2CO3, Ni(NO3)2·6H2O, (CH3COO)2Mn·4H2O, and Co(NO3)2·6H2O were weighed and mixed in a mortar and pestle so that the mixing ratio of Li, Ni, Mn, and Co would be Li:Ni:Mn:Co = 3:1:1:1 in terms of molar ratio when the above metal salts are mixed and synthesized. This yielded a mixture of metal salts. 【0082】 Next, 25 parts by weight of the above mixture were added to 100 parts by weight of black mass, and the mixture was heat-treated at 800°C for 1 hour, after which it was allowed to cool to room temperature. This mixture was then sieved using a stainless steel mesh with a mesh size of 75 μm to prepare the powder sample (electrode active material) of sample number 1. 【0083】 Next, 2.7 g of the above sample and 6 g of N-methyl-2-pyrrolidone (hereinafter referred to as "NMP") were mixed and stirred for 120 seconds using a stirring and defoaming device (Kurabo Industries Ltd., Mazelstar). Then, 0.15 g of conductive carbon (Lion Corporation, EC-600-JD) as a conductive additive was added, and the mixture was stirred for another 360 seconds using the same stirring and defoaming device to obtain the stirred product. 【0084】 Next, an NMP solution was prepared by dissolving 5 wt% polyvinylidene fluoride in NMP. Then, 3.0 g of the NMP solution was added to the stirred mixture and stirred for 360 seconds using the stirring and degassing apparatus, followed by stirring for another 180 seconds, then stirring for another 360 seconds, and finally degassing for 90 seconds to obtain the coating solution. 【0085】 Next, using the doctor blade method, the coating solution was applied to the Al substrate to form a coating film with a thickness of 300 μm, and then dried at a temperature of 100°C for 8 hours. This created a positive electrode in which the Al substrate served as the positive electrode current collector and the sample described above served as the positive electrode active material. 【0086】 Next, lithium metal was placed on a Cu substrate, and a negative electrode was fabricated with the Cu substrate as the negative electrode current collector and the lithium metal as the main negative electrode active material. Then, a separator made of polypropylene was interposed between the positive and negative electrodes, and a carbonate-based electrolyte was injected between the positive and negative electrodes, thereby fabricating the flat cell (experimental simple cell) of sample number 1. 【0087】 When this flat cell was charged at a C rate of 0.1C until it reached 4.6V, and then discharged to 2.0V, the battery capacity (initial value) was 124.1mAh / g. 【0088】 (Sample number 2) The black mass manufactured by Kawashima Co., Ltd., used in sample number 1, was used as the powder sample for sample number 2. Using this powder sample, a flat cell for sample number 2 was prepared using the same method and procedure as for sample number 1. 【0089】 When this flat cell was charged and discharged using the same method and procedure as for sample number 1, the battery capacity (initial value) was 93.7 mAh / g. 【0090】 (Sample number 3) Powder sample No. 3 was prepared using the same method and procedure as for sample No. 1, except that only 25 parts by weight of Li2CO3 was added to 100 parts by weight of black mass. 【0091】 Then, using this powder sample, a flat cell for sample number 3 was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the battery capacity (initial value) was 115.8 mAh / g. 【0092】 (Sample number 4) NMC111 (LiNi) manufactured by MTI Corporation. 1 / 3 Mn 1 / 3 Co 1 / 3 O2) was procured and used as sample number 4, the powder sample (reference sample). 【0093】 Then, using this powder sample, a flat cell for sample number 4 was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the battery capacity (initial value) was 101.2 mAh / g. 【0094】 [Evaluation of the sample] For each of the powder samples, numbers 1, 2, and 4, imaging and elemental mapping analysis were performed using a SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray Spectrometry) (FlexSEM 1000 II, Hitachi High-Tech Corporation). Furthermore, the samples were irradiated with characteristic X-rays (Kα), and the X-ray diffraction spectra were measured. 【0095】 Figure 2 shows secondary electron images of sample number 1, acquired at an accelerating voltage of 5.0 kV. (a) was acquired at a magnification of 1000x, and (b) at a magnification of 5000x. 【0096】 Figure 3 shows the secondary electron image of sample number 2 (black mass) acquired using the same method and procedure as sample number 1, and Figure 4 shows the secondary electron image of sample number 4 (NMC111) acquired using the same method and procedure as sample number 1. 【0097】 In other words, as is clear from Figure 4, sample number 4 is dispersed almost uniformly as spherical to roughly rectangular aggregates with a particle size of about 1 μm. 【0098】 On the other hand, as is clear from Figure 3, sample number 2 shows an irregular dispersion of aggregates of fine particles and submicron particles measuring several micrometers in size. 【0099】 In contrast, sample number 1, with a small amount of metal salt mixture added (25 parts by weight per 100 parts by weight of black mass), was found to be closer to sample number 2 (Figure 3) than to sample number 4 (Figure 4), as shown in Figure 2. 【0100】 Figure 5 shows the elemental mapping analysis profile for sample number 1, with the horizontal axis representing the acceleration voltage (keV) and the vertical axis representing the count number (au). Table 1 shows the mass fraction (mass%), standard deviation σ (%), and molar concentration (mol%) of each metal component in sample number 1. Note that in Table 1, element C in Figure 5 is excluded from the composition elements because it includes the carbon tape used to fix the sample. 【0101】 [Table 1] 【0102】 Figure 6 shows the elemental mapping analysis profile for sample number 2, with the horizontal axis representing the acceleration voltage (keV) and the vertical axis representing the count number (au). Table 2 shows the mass fraction (mass%), standard deviation σ (%), and molar concentration (mol%) of each metal component in sample number 2. As with Table 1, element C is excluded from the composition. 【0103】 [Table 2] 【0104】 Figure 7 shows the elemental mapping analysis profile for sample number 4, with the horizontal axis representing the acceleration voltage (keV) and the vertical axis representing the count number (au). Table 3 shows the mass fraction (mass%), standard deviation σ (%), and molar concentration (mol%) of each metal component in sample number 4. As with Table 1, element C is excluded from the composition. 【0105】 [Table 3] 【0106】 As shown in Figure 6 and Table 2, sample number 2, like the electrode active material of the present invention, mainly consists of Ni, Mn, and Co components. However, among these components, Ni was found to be the most abundant, followed by Mn, and Co was the least abundant. Furthermore, the standard deviation σ of each detected component was 0.09% or less, indicating small variation. This revealed that the electrode active material of the present invention contained F, which is unnecessary for the present invention, and also contained a small amount of Al. 【0107】 On the other hand, as shown in Figure 7 and Table 3, sample number 4 contains small amounts of Al and Si components, but the Ni, Mn, and Co components are in approximately equal amounts, and the composition formula is roughly (LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 It was found that the mixture was formulated in the molar ratio shown in O2). 【0108】 In contrast, as shown in Figure 5 and Table 1, sample number 1, like sample number 2, was mainly composed of Ni, Mn, and Co, with Ni being the most abundant, followed by Mn, and Co being the least abundant. Furthermore, the F component detected in sample number 2 was not detected. 【0109】 In other words, since sample number 1 had a small amount of metal salt mixture added (25 parts by weight per 100 parts by weight of black mass), the elemental analysis results were found to be closer to those of sample number 2 (Table 2) than to those of sample number 4 (Table 3). 【0110】 Although Li (Li) is a light element and therefore could not be detected by SEM-EDX, this does not particularly affect the sample evaluation, as the purpose of elemental analysis is to confirm the composition of the metal oxide. 【0111】 Figure 8 shows the X-ray diffraction spectrum profiles for each powder sample (sample numbers 1, 2, and 4), with the horizontal axis representing the diffraction angle 2θ (°) and the vertical axis representing the diffraction intensity (au). 【0112】 Sample No. 4 is known to have a layered rock salt crystal structure, and since the profiles of Sample No. 1 and Sample No. 2 are similar to those of Sample No. 4, it is considered that all of Sample No. 1, 2, and 4 have a layered rock salt crystal structure, and it has been confirmed that they have a crystal structure suitable for electrode active materials for lithium-ion batteries. 【0113】 Next, for each sample numbered 1 to 4, the cycle characteristics were evaluated by repeating the charge-discharge cycle 100 times within a voltage range of 2.0V to 4.6V. 【0114】 Table 4 shows the measurement results. 【0115】 [Table 4] 【0116】 Sample No. 2 had a low initial capacity density of 93.7 mAh / g, and after 100 cycles, the capacity density decreased to 23.2 mAh / g. In other words, after 100 charge-discharge cycles, the capacity density decreased to about 25% of the initial value, indicating that sufficient cycle characteristics could not be obtained. 【0117】 Sample No. 3 initially had a higher capacity density of 115.8 mAh / g than Sample No. 4. However, because it was simply black mass with added Li and heat treatment, the degradation of cycle characteristics became significant after 25 cycles, and it was found that after 100 cycles, the capacity density dropped to 3.9 mAh / g, which is about 3% of the initial value. 【0118】 In contrast, sample number 1 had a high initial capacity density of 124.1 mAh / g, and after 50 cycles, its capacity density was 64.7 mAh / g, maintaining 52% of the initial value. Even after 100 cycles, its capacity density was 44.6 mAh / g, maintaining 36% of the initial value, demonstrating better cycle characteristics compared to samples 2 and 3. [Examples] 【0119】 In this Example 2, several samples were prepared with different amounts of metal salt added, and their respective properties were evaluated. 【0120】 [Sample preparation] (Sample number 1a) Powder sample 1a was prepared using the same method and procedure as sample 1, except that 10 parts by weight of a metal salt mixture was added to 100 parts by weight of black mass. 【0121】 Then, using this powder sample, a flat cell of sample number 1a was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the battery capacity (initial value) was 121.8 mAh / g. 【0122】 (Sample number 1b) Powder sample 1b was prepared using the same method and procedure as sample 1, except that 50 parts by weight of a metal salt mixture was added to 100 parts by weight of black mass. 【0123】 Then, using this powder sample, a flat cell of sample number 1b was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the battery capacity (initial value) was 106.4 mAh / g. 【0124】 (Sample number 1c) Sample No. 1c was prepared using the same method and procedure as for Sample No. 1, except that 75 parts by weight of a metal salt mixture was added to 100 parts by weight of black mass. 【0125】 Then, using this powder sample, a flat cell of sample number 1c was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the battery capacity (initial value) was 88.5 mAh / g. 【0126】 [Evaluation of the sample] For each sample (sample numbers 1a to 1c), the cycle characteristics were evaluated by repeating the charge-discharge cycle 100 times within a voltage range of 2.0V to 4.6V. 【0127】 Table 5 shows the measurement results. Note that Table 5 also includes the cycle characteristics of sample number 1. 【0128】 [Table 5] 【0129】 Sample number 1b had a high amount of metal salt mixture added (50 parts by weight per 100 parts by weight of black mass), which resulted in increased costs. Furthermore, it was found that the capacity density after 100 cycles was 29.7 mAh / g, which was less than 30% of the initial value. 【0130】 Sample No. 1c had an excessive amount of metal salt mixture added (75 parts by weight per 100 parts by weight of black mass), which, like sample No. 1b, resulted in higher costs. Furthermore, the initial capacity density was low at 88.5 mAh / g, and after 100 cycles, the capacity density fell to 11.7 mAh / g, which was less than 15% of the initial value. 【0131】 In contrast, sample number 1a, with an added amount of metal salt mixture of 10 parts by weight per 100 parts by weight of black mass, had a high initial capacity density of 121.8 mAh / g. Even after 100 cycles, the capacity density remained at 41.8 mAh / g, which is approximately 34% of the initial value. This indicates that it can obtain good cycle characteristics almost identical to those of sample number 1. 【0132】 From the above, it was found that the amount of metal salt added is not particularly limited, but 10 to 25 parts by weight per 100 parts by weight of black mass is preferable. [Examples] 【0133】 In this Example 3, multiple samples were prepared using different heat treatment temperatures, and their respective characteristics were evaluated. 【0134】 [Sample preparation] (Sample number 1d) Powder sample 1d was prepared using the same method and procedure as sample 1, except that the heat treatment temperature was 700°C. 【0135】 Then, using this powder sample, a flat cell of sample number 1d was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the battery capacity (initial value) was 110.7 mAh / g. 【0136】 (Sample number 1e) Powder sample 1e was prepared using the same method and procedure as sample 1, except that the heat treatment temperature was 900°C. 【0137】 Then, using this powder sample, a flat cell of sample number 1e was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the battery capacity (initial value) was 112.4 mAh / g. 【0138】 (Sample number 1f) Powder sample 1e was prepared using the same method and procedure as sample 1, except that the heat treatment temperature was 1000°C. 【0139】 Then, using this powder sample, a flat cell of sample number 1f was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the battery capacity (initial value) was 82.1 mAh / g. 【0140】 (Sample number 1g) A powder sample of sample number 1g was prepared using the same method and procedure as sample number 1, except that the heat treatment temperature was 1100°C. 【0141】 Then, using this powder sample, a flat cell of sample number 1g was prepared using the same method and procedure as for sample number 1, and when it was charged and discharged, the battery capacity (initial value) was 82.3mAh / g. 【0142】 [Evaluation of the sample] For each sample from sample numbers 1d to 1g, the cycle characteristics were evaluated by repeating the charge-discharge cycle 100 times within the voltage range of 2.0V to 4.6V. 【0143】 Figure 9 shows the temperature dependence of the cycle characteristics, with the horizontal axis representing the number of cycles and the vertical axis representing the capacity density (mAh / g). In the figure, ○ indicates the cycle characteristics of sample number 1d (heat treatment temperature: 700°C), □ indicates sample number 1e (heat treatment temperature: 900°C), ■ indicates sample number 1f (heat treatment temperature: 1000°C), and × indicates sample number 1g (heat treatment temperature: 1100°C). Note that ● indicates the cycle characteristics of sample number 1 (heat treatment temperature: 800°C). 【0144】 As is clear from Figure 9, samples 1f and 1g were subjected to excessively high heat treatment temperatures of 1000°C and 1100°C, respectively. As a result, their initial battery capacity was low, and their cycle characteristics deteriorated significantly, dropping drastically after about 20 cycles. This is likely because the excessively high heat treatment temperature led to excessive crystallization, inhibiting the insertion and removal reactions of Li ions. 【0145】 In contrast, samples 1d and 1e were treated at temperatures of 700°C and 900°C, respectively, which are suitable temperatures for crystallization, and it was found that they exhibited good cycle characteristics, similar to sample 1. 【0146】 From the above, it was found that a heat treatment temperature of 700 to 900°C is preferable. [Examples] 【0147】 In this Example 4, multiple samples were prepared with different heat treatment times, and their respective characteristics were evaluated. 【0148】 [Sample preparation] (Sample number 1h) Powder sample 1h was prepared using the same method and procedure as sample 1, except that the heat treatment time was set to 0.5 hours. 【0149】 Then, using this powder sample, a flat cell of sample number 1h was prepared using the same method and procedure as sample number 1, and when charging and discharging was performed, the battery capacity (initial value) was 117.6 mAh / g. 【0150】 (Sample number 1i) Sample No. 1i was prepared using the same method and procedure as Sample No. 1, except that the heat treatment time was set to 1 hour. 【0151】 Then, using this powder sample, a flat cell of sample number 1i was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the battery capacity (initial value) was 121.3 mAh / g. 【0152】 (Sample number 1j) Sample No. 1j was prepared using the same method and procedure as Sample No. 1, except that the heat treatment time was set to 4 hours. 【0153】 Then, using this powder sample, a flat cell of sample number 1j was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the battery capacity (initial value) was 109.2 mAh / g. 【0154】 [Evaluation of the sample] For each sample from sample numbers 1h to 1j, the cycle characteristics were evaluated by repeating the charge-discharge cycle 100 times within the voltage range of 2.0V to 4.6V. 【0155】 Table 6 shows the measurement results. Note that Table 6 also includes the cycle characteristics of sample number 1. 【0156】 [Table 6] 【0157】 Sample number 1h had a capacity density of 37.4 mAh / g after 100 cycles, which was about 32% of the initial value. This is likely because the crystallization did not proceed sufficiently due to the short heat treatment time of 0.5 hours. 【0158】 Sample number 1j had a capacity density of 29.3 mAh / g after 100 cycles, which was about 27% of the initial value. This was because the heat treatment time was too long at 4.0 hours, causing excessive crystallization. + This is thought to be because the insertion and elimination reactions were inhibited. 【0159】 In contrast, sample number 1i underwent a heat treatment time of 2 hours, and it was found that it obtained almost the same cycle characteristics as sample number 1 (heat treatment time: 1 hour). 【0160】 Based on the above, it was found that a heat treatment time of 1 to 2 hours is preferable. [Examples] 【0161】 In this Example 5, multiple samples were prepared with different metal source ratios, and their respective properties were evaluated. 【0162】 [Sample preparation] (Sample number 11) Similar to sample number 1, powders of Li2CO3 as the Li source, Ni(NO3)2·6H2O as the Ni source, (CH3COO)2Mn·4H2O as the Mn source, and Co(NO3)2·6H2O as the Co source were prepared. Then, these Li2CO3, Ni(NO3)2·6H2O, (CH3COO)2Mn·4H2O, and Co(NO3)2·6H2O were weighed and mixed in a mortar and pestle so that when these multiple metal salts were mixed and synthesized, the mixing ratio of Li, Ni, Mn, and Co would be Li:Ni:Mn:Co = 1:0.4:0.3:0.3 in molar terms. A mixture of metal salts was thus prepared. Sample number 11 was prepared using the same method and procedure as sample number 1. 【0163】 Subsequently, using this powder sample, a flat cell for sample number 11 was prepared using the same method and procedure as for sample number 1, and when charged and discharged, the battery capacity (initial value) was 116.7 mAh / g (sample name: NMC443). 【0164】 (Sample number 12) A mixture of metal salts was prepared by weighing Li2CO3, Ni(NO3)2·6H2O, (CH3COO)2Mn·4H2O, and Co(NO3)2·6H2O, respectively, and mixing them in a mortar and pestle, so that the mixing ratio of Li, Ni, Mn, and Co would be Li:Ni:Mn:Co = 1:0.5:0.3:0.2 when the multiple metal salts were mixed and synthesized together. Then, the powder sample for sample number 12 was prepared using the same method and procedure as for sample number 1. 【0165】 Subsequently, using this powder sample, a flat cell for sample number 12 was prepared using the same method and procedure as for sample number 1, and when charged and discharged, the battery capacity (initial value) was 119.4 mAh / g (sample name: NMC523). 【0166】 (Sample number 13) A mixture of metal salts was prepared by weighing Li2CO3, Ni(NO3)2·6H2O, (CH3COO)2Mn·4H2O, and Co(NO3)2·6H2O, and mixing them in a mortar, so that the mixing ratio of Li, Ni, Mn, and Co would be Li:Ni:Mn:Co = 1:0.6:0.2:0.2 when the multiple metal salts were mixed together. Then, powder sample No. 13 was prepared using the same method and procedure as sample No. 1. 【0167】 Subsequently, using this powder sample, a flat cell for sample number 13 was prepared using the same method and procedure as for sample number 1, and when charged and discharged, the battery capacity (initial value) was 126.8 mAh / g (sample name: NMC622). 【0168】 (Sample number 14) A mixture of metal salts was prepared by weighing Li2CO3, Ni(NO3)2·6H2O, (CH3COO)2Mn·4H2O, and Co(NO3)2·6H2O, and mixing them in a mortar, so that the mixing ratio of Li, Ni, Mn, and Co would be Li:Ni:Mn:Co = 1:0.8:0.1:0.1 when the multiple metal salts were mixed together. Then, the powder sample for sample number 14 was prepared using the same method and procedure as for sample number 1. 【0169】 Subsequently, using this powder sample, a flat cell for sample number 14 was prepared using the same method and procedure as for sample number 1, and when charged and discharged, the battery capacity (initial value) was 132.8 mAh / g (sample name: NMC811). 【0170】 (Sample number 15) Instead of (CH3COO)2Mn·4H2O as the Mn source, AlCl3·6H2O was prepared as the Al source. Then, Li2CO3, Ni(NO3)2·6H2O, Co(NO3)2·6H2O, and AlCl3·6H2O were weighed out and mixed in a mortar so that the mixing ratio of Li, Ni, Co, and Al would be Li:Ni:Co:Al = 1:0.8:0.15:0.05 when the multiple metal salts are mixed and synthesized together. A mixture of metal salts was then prepared, and sample number 15 was prepared using the same method and procedure as sample number 1. 【0171】 Subsequently, using this powder sample, a flat cell for sample number 15 was prepared using the same method and procedure as for sample number 1, and when charged and discharged, the battery capacity (initial value) was 130.6 mAh / g (sample name: NCA). 【0172】 (Sample number 16) A mixture of metal salts was prepared by weighing Li2CO3, Ni(NO3)2·6H2O, (CH3COO)2Mn·4H2O, and Co(NO3)2·6H2O, respectively, and mixing them in a mortar, so that the mixing ratio of Li, Ni, Mn, and Co would be Li:Ni:Mn:Co = 1.2:0.13:0.54:0.13 when the multiple metal salts were mixed together. Then, the powder sample for sample number 16 was prepared using the same method and procedure as for sample number 1. 【0173】 Subsequently, using this powder sample, a flat cell of sample number 16 was prepared using the same method and procedure as sample number 1, in which the positive electrode active material was formed with a lithium-rich composition. When charging and discharging was performed, the battery capacity (initial value) was 187.6 mAh / g (sample name: LR-NMC). 【0174】 (Evaluation of the sample) For each sample from sample numbers 11 to 16, the cycle characteristics were evaluated by repeating the charge-discharge cycle 100 times within the voltage range of 2.0V to 4.6V. 【0175】 Table 7 shows the measurement results. 【0176】 [Table 7] 【0177】 As is clear from Table 7, samples 11-16 maintained a capacity of 55.2-88.7 mAh / g even after 50 cycles, achieving 44-51% of their initial battery capacity. 【0178】 From the above, it was found that even if the mixing ratio of each metal component is varied according to the application, a low-cost and highly practical lithium-ion battery can be obtained. [Industrial applicability] 【0179】 By adding a predetermined metal salt to black mass obtained from used lithium-ion batteries, a novel and useful electrode active material can be produced using black mass without the need to recover the metal salt or metal material separately. [Explanation of symbols] 【0180】 3 Cathode active material (electrode active material) 4 Positive electrode 5 Negative electrode active material 6 negative electrode 8 Electrolyte (electrolyte)

Claims

[Claim 1] A method for producing an electrode active material, characterized by adding a total of 10 to 50 parts by weight of multiple metal salts containing Li, Ni, Co, and Mn or Al, respectively, to black mass obtained by processing used lithium-ion batteries, and then heat-treating the black mass at a temperature of 700 to 900°C to react the black mass with the metal salts to produce an electrode active material. [Claim 2] The method for producing an electrode active material according to claim 1, characterized in that the amount of the metal salt added is 10 to 25 parts by weight per 100 parts by weight. [Claim 3] A method for producing an electroactive material according to claim 1 or 2, characterized in that the heat treatment is performed for 1 to 2 hours. [Claim 4] When the plurality of metal salts are synthesized by mixing these plurality of metal salts, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O ２ 、LiNi 0.4 Mn 0.3 Co 0.3 O ２ 、LiNi 0.5 Mn 0.3 Co 0.2 O ２ 、LiNi 0.5 Mn 0.2 Co 0.3 O ２ 、LiNi 0.6 Mn 0.2 Co 0.2 O ２ 、LiNi 0.8 Mn 0.1 Co 0.1 O ２ 、LiNi 0.8 Co 0.15 Al 0.05 O ２ 、and one oxide selected from the group of lithium-excess composition represented by the general formula Li 1＋ｘ Ni 2 / （3+3ｙ） Mn 2x / （3+3ｙ） Co 2 / （3+3ｙ） O ２ (where x > 0 and y is a positive integer) can be formed, and the mixing ratio is adjusted and added to the black mass. The method for producing an electrode active material according to claim 1 or claim 2. [Claim 5] A method for manufacturing an electrode, characterized by having an electrode active material produced by the manufacturing method described in claim 1 or claim 2. [Claim 6] The method for manufacturing an electrode according to claim 5, characterized in that the electrode active material has a layered rock salt crystal structure. [Claim 7] A method for manufacturing a lithium-ion battery having a positive electrode, a negative electrode, and an electrolyte, and which undergoes repeated charge-discharge reactions by a battery electrode reaction using lithium ions as a charge carrier, A method for manufacturing a lithium-ion battery, characterized in that the positive electrode active material, which is the main component of the positive electrode, is formed from an electrode active material manufactured by the manufacturing method described in claim 1 or claim 2. [Claim 8] The method for manufacturing a lithium-ion battery according to claim 7, characterized in that the negative electrode active material, which is the main component of the negative electrode, is formed of at least one selected from the group consisting of lithium metal, graphite, graphene, and lithium titanate. [Claim 9] Formed from a Li-based metal oxide containing black mass obtained by processing used lithium-ion batteries and putting them directly into use, The Li-based metal oxide is an electrode active material characterized by being heat-treated together with the black mass, with a total of 10 to 50 parts by weight of multiple metal salts each containing Li, Ni, Co, and Mn or Al per 100 parts by weight of the black mass. [Claim 10] The electrode active material according to claim 9, characterized in that the plurality of metal salts are contained in total in an amount of 10 to 25 parts by weight per 100 parts by weight of the black mass. [Claim 11] The Li-based metal oxides include LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O 2 , LiNi 0.4 Mn 0.3 Co 0.3 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , LiNi 0.5 Mn 0.2 Co 0.3 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 , LiNi 0.8 Mn 0.1 Co 0.1 O 2 , LiNi 0.8 Co 0.15 Al 0.05 O 2 , and the general formula Li 1+x Ni 2 / (3+3y) Mn 2x / (3+3y) The electrode active material according to claim 9 or 10, characterized in that it is formed of one selected from the group consisting of Co 2 / (3+3y) O 2 (where x>0 and y is a positive integer). [Claim 12] A lithium-ion battery having a positive electrode, a negative electrode, and an electrolyte, which repeatedly undergoes charge and discharge reactions through a battery electrode reaction using lithium ions as a charge carrier, A lithium-ion battery characterized in that the positive electrode active material, which is the main component of the positive electrode, is formed of the electrode active material described in claim 9 or claim 10. [Claim 13] The lithium-ion battery according to claim 12, characterized in that the negative electrode active material, which is the main component of the negative electrode, is formed of at least one selected from the group consisting of lithium metal, graphite, graphene, and lithium titanate.

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