Production method for electrode active material, production method for lithium ion battery, electrode active material, and lithium ion battery

Abstract

According to the present invention, an electrode active material is produced by mixing a black mass obtained by treating used lithium ion batteries and a plurality of metal salts that each include Li, Ni, Mn, and Co as metal components such that there are a total of 20–5000 parts by weight of the metal salts per 100 parts by weight of the black mass and performing a heat treatment to cause the black mass and the metal salts to react. A lithium ion battery according to the present invention includes a positive electrode 3, a negative electrode 5, and an electrolyte, a positive electrode active material that is the principal constituent of the positive electrode 3 being formed from the electrode active material produced as described above. The present invention thereby provides an electrode active material and a lithium ion battery that, by using a black powder from a black mass directly, achieve excellent practicality and make it possible to ensure desired battery characteristics without the need to recover or purify metal salts or the like from the black mass, even when there are broad differences in the component composition of individual black masses.

Description

Electrode active material manufacturing method, lithium ion battery manufacturing method, and electrode active material and lithium ion battery

[0001] The present invention relates to a method for producing an electrode active material, a method for producing a lithium ion battery, and an electrode active material and a lithium ion battery; more particularly, to a method for producing an electrode active material using black mass, a method for producing a lithium ion battery using the electrode active material produced by this production method as a positive electrode active material, and an electrode active material and a lithium ion battery obtained by the above production method.

[0002] With the expansion of the market for portable electronic devices such as mobile phones, laptops, and tablet computers, there has been active development of secondary batteries as cordless power sources for these devices. Furthermore, against the backdrop of global warming and the depletion of petroleum resources, there has also been active development of electric vehicles and hybrid vehicles powered by secondary batteries.

[0003] Under these circumstances, secondary batteries have been developed that use alkali metal ions, such as lithium ions, as charge carriers and utilize the electrochemical reactions that accompany the transfer of electric charges. In particular, lithium ion batteries, which have a high energy density, are now widely used.

[0004] Among the components of lithium-ion batteries, electrode active materials are substances that directly contribute to the battery electrode reactions, namely, the charge and discharge reactions. They play a central role in lithium-ion batteries because they are charged and discharged by utilizing the insertion and desorption reactions of lithium ions into and from the electrode active material.

[0005] In the early stages of development of this type of lithium-ion battery, the electrode active material, especially the positive electrode active material, was LiCoO ２ However, due to the high cost of Co and the demand for higher capacity and lower cost associated with the expansion of battery applications, ternary materials in which part of the Co is replaced with Ni or Mn have attracted attention in recent years, and lithium-ion batteries using such ternary materials as the positive electrode active material have been actively researched and developed.

[0006] However, while demand for lithium-ion batteries is expected to continue to increase in the future, Li and the Co, Ni, and Mn that make up the ternary materials are all rare metals, and there is a risk that it will become difficult to secure a supply of raw materials in the future.

[0007] In recent years, attention has been focused on technology that aims to recover and recycle lithium-ion battery materials from the black powder known as "black mass" that is generated by processing used lithium-ion batteries.

[0008] For example, Patent Document 1 proposes a method for recovering and purifying valuable metals, including one or more of Ni, Mn, Co, and Li, from black mass obtained from recycling lithium-ion batteries.

[0009] In Patent Document 1, black mass is subjected to reduction acid leaching to produce an acid leaching slurry containing a pregnant acid leaching solution containing valuable metals (Ni, Mn, Co) and impurities, and insoluble matter; the insoluble matter is separated and removed from the pregnant acid leaching solution, and the pH of the pregnant acid leaching solution is then adjusted to precipitate and remove impurities from the pregnant acid leaching solution. Subsequently, an ion exchange resin is used to remove remaining impurities from the pregnant acid leaching solution, and a Li basic solution is used to regenerate the ion exchange resin and produce a mixed precipitate slurry. The pH of the pregnant acid leaching solution is then adjusted to separate the mixed precipitate containing valuable metals from a Li-containing solution. Metal salts that serve as precursors for a ternary positive electrode active material are recovered from the mixed precipitate. Furthermore, the Li-containing solution is subjected to salt decomposition and crystallization to obtain Li, a Li source. ２ CO ３ are being collected.

[0010] In this way, in Patent Document 1, a precursor of a ternary positive electrode active material containing Li and Li are obtained from black mass by a chemical process. ２ CO ３ We are trying to collect and reuse resources.

[0011] Patent Document 2 also proposes a method for extracting metals from the black mass of lithium ion batteries.

[0012] That is, in Patent Document 2, a fraction of non-metallic materials is separated from the black mass to recover a black mass containing an anode material and a cathode material, then an acid leaching is carried out by adding a gas containing sulfur dioxide and molecular oxygen as an extractant to a sulfuric acid-containing solution to dissolve the cathode material in the black mass and recover a leachate solution containing the cathode material, an initial fraction of metallic materials is separated from the leachate solution, and a main fraction containing at least one of Mn, Co, Ni, and Li is recovered.

[0013] Thus, in Patent Document 2, after removing non-metallic components from black mass by pretreatment, sulfuric acid and an extractant are used to sequentially separate and recover initial fractions of metallic materials from each leaching solution containing cathode material, thereby attempting to reuse resources.

[0014] Furthermore, Patent Document 3 proposes a method for recovering a metal group from waste batteries, waste positive electrode materials, or a mixture thereof containing a metal group consisting of at least two of Co, Ni, and Mn and impurities, the method including removing impurities from the waste batteries, waste positive electrode materials, or a mixture thereof, and then recovering the metal group as a mixture of metal salts.

[0015] In Patent Document 3, waste batteries, waste cathode material, or a mixture thereof is leached with sulfuric acid to produce a leachate, and if impurities such as Fe, Cr, Cu, F, or C are contained, the pH of the leachate is adjusted to precipitate and remove the impurities, or the impurities are separated into the solvent side by solvent extraction, and then the 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 the 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, thereby eliminating the effort of individual separation and aiming to reduce the cost of recycling the cathode material.

[0016] As described above, all of Patent Documents 1 to 3 aim to remove impurities from black mass (waste batteries, waste cathode materials) by a wet process, and then separate and recover metal salts or mixtures thereof or metal fractions, and recycle the resources to be used in the production of new batteries.

[0017] JP 2023-174586 A (Claim 11, paragraphs

[0028] to

[0029] , Figure 1, etc.) JP 2024-516955 A (Claim 1, paragraphs

[0063] to

[0066] , Figures 2a, 2b, etc.) JP 2014-156649 A (Claim 1 to 3, paragraphs

[0029] ,

[0050] )

[0018] However, in the above Patent Documents 1 to 3, the component compositions of used lithium-ion batteries vary, and the processing steps of extracting, separating, and recycling battery materials from black mass are complicated, the cost of equipment is expensive, and the recycling costs are high, making them less practical.

[0019] The present invention has been made in view of the above circumstances, and aims to provide a method for producing an electrode active material that is highly practical and can ensure desired battery characteristics by reusing resources and without the need for the laborious recovery and purification of metal salts and the like from black mass, even if the component composition of black mass varies greatly from one individual to another; a method for producing a lithium ion battery that uses the electrode active material produced by this production method as the positive electrode active material; and an electrode active material and a lithium ion battery obtained by the above production method.

[0020] The black mass described above is a black powder obtained by discharging and deactivating used lithium-ion batteries, heating and drying them to evaporate the electrolyte and other components, crushing and pulverizing them, extracting and removing unnecessary impurity elements, and then sieving the resulting material.

[0021] Therefore, in the case of used lithium-ion batteries that use ternary materials (Ni, Mn, Co) as electrode active materials, the black mass contains the ternary materials and Li, so by mixing the black mass with a metal salt containing these ternary materials or Li and subjecting it to heat treatment, and then reacting the metal salt with the black mass to synthesize it, it is possible to produce an electrode active material at low cost without the need for processing steps such as acid leaching or extraction as in Patent Documents 1 to 3, and it is thought that this will enable resources to be effectively recycled and promote the effective use of global resources.

[0022] However, as mentioned above, black mass is obtained through various processing steps such as heating, drying, crushing, and pulverization. However, the chemical composition of used lithium-ion batteries varies widely, and the chemical composition of individual black masses varies greatly depending on the processing conditions during the manufacturing process and the production unit.

[0023] Therefore, the present inventors have conducted extensive research to obtain a highly practical electrode active material while taking into consideration the balance between resource recycling and battery characteristics, and have found that as long as the total amount of Li and the metal salts of the ternary material is within the range of 20 to 5,000 parts by weight per 100 parts by weight of black mass, it is possible to sufficiently deal with large individual differences in the component composition of black mass.

[0024] The present invention has been made based on this finding, and the method for producing an electrode active material according to the present invention is a method for producing an electrode active material using black mass obtained by treating used lithium-ion batteries, characterized in that the black mass and the metal salts are mixed together so that a total of 20 to 5,000 parts by weight of a plurality of metal salts each containing Ni, Mn, Co, and Li is contained per 100 parts by weight of the black mass, and the mixture is subjected to heat treatment, and the black mass and the metal salts are reacted to produce the electrode active material.

[0025] In this way, by freely selecting the total amount of metal salts to be mixed with the black mass within a wide range of 20 to 5,000 parts by weight per 100 parts by weight of black mass, it is possible to adequately deal with the various conditions of used lithium-ion batteries and the large individual differences in the component composition of the black mass depending on the processing conditions during the manufacturing process and the production unit, and it becomes possible to produce an electrode active material with good battery characteristics while promoting the effective recycling of resources.

[0026] In addition, in the method for producing an electrode active material of the present invention, it is preferable to vary the mixing ratio of the black mass to the total amount of the metal salts depending on the component composition of the black mass.

[0027] This allows the black mass to be mixed with an optimal range of metal salts corresponding to the component composition of the black mass and then heat-treated, thereby enabling the production of an electrode active material with good battery characteristics while promoting resource circulation, thereby ensuring a balance between resource circulation and battery characteristics.

[0028] Furthermore, in the method for producing an electrode active material of the present invention, when the black mass contains at least Ni, Mn, Co, Li, and C, and the content of the C component is less than 7.5% in terms of mass ratio, it is preferable to mix the black mass and the metal compound so that the total amount of the metal salts is 20 to 350 parts by weight per 100 parts by weight of the black mass.

[0029] In this way, when the content of the C component in the black mass is less than 7.5% in terms of mass ratio, the content of Li and ternary materials increases relatively. Therefore, even if the total amount of metal salts mixed into the black mass is limited to 20 to 350 parts by weight per 100 parts by weight of the black mass, it is possible to obtain excellent battery characteristics that are highly practical, and this is suitable for effective resource utilization.

[0030] Furthermore, in the method for producing an electrode active material of the present invention, when the black mass contains at least Ni, Mn, Co, Li, and C, and the content of the C component exceeds 25% in terms of mass ratio, it is preferable to mix the black mass and the metal salts so that the total amount of the metal salts is 700 to 5,000 parts by weight per 100 parts by weight of the black mass.

[0031] When the content of the C component in the black mass exceeds 25% in terms of mass ratio, the content of Li and ternary materials decreases relatively, and therefore, by increasing the total amount of metal salts to 700 to 5,000 parts by weight per 100 parts by weight of black mass, it becomes possible to obtain an electrode active material with good battery characteristics. In this case, although the total amount of metal salts increases, the black mass is used as effectively as possible, and this contributes to the demand for resource recycling.

[0032] Furthermore, in the method for producing an electrode active material of the present invention, it is more preferable that the total amount of the metal salts is 3,500 to 5,000 parts by weight per 100 parts by weight of the black mass.

[0033] By using 3,500 to 5,000 parts by weight of metal salts in total relative to 100 parts by weight of black mass, it is possible to produce an electrode active material with good battery capacity and cycle characteristics comparable to those obtained by synthesizing metal salts together.

[0034] In addition, the method for producing an electrode active material of the present invention preferably includes dissolving each metal powder containing each of the components in a solvent to prepare a mixed solution, treating the mixed solution to prepare a precipitate, obtaining the metal salt from the precipitate, and mixing the black mass with the metal salt.

[0035] This makes it possible to obtain highly refined, high-quality metal salts, and to produce good-quality electrode active materials.

[0036] In the method for producing an electrode active material of the present invention, the heat treatment is preferably carried out at a temperature of 650 to 950° C. for 1 to 4 hours.

[0037] By appropriately adjusting the heat treatment temperature and heat treatment time in this way, an electrode active material having the desired battery performance can be easily produced.

[0038] Furthermore, in the method for producing an electrode active material of the present invention, when the plurality of metal salts are mixed and synthesized, the plurality of metal salts have the composition formula LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O ２ It is preferable to adjust the compounding ratio and mix it with the black mass so that a metal oxide represented by the formula (hereinafter also referred to as "NMC111") can be formed.

[0039] Furthermore, the method for producing a lithium ion battery according to the present invention is a method for producing a lithium ion battery that has a positive electrode, a negative electrode, and an electrolyte, and that repeatedly charges and discharges through a battery electrode reaction using lithium ions as a charge carrier, and is characterized in that the positive electrode active material that forms the main component of the positive electrode uses an electrode active material produced by the above-mentioned production method.

[0040] Since the cathode active material is the electrode active material produced by the above-mentioned production method, it is possible to produce a novel and useful lithium-ion battery that can adequately handle large individual differences in the component composition of black mass, without the need for the effort of recovering and purifying metal salts from black mass.

[0041] In addition, in the method for manufacturing a lithium ion battery of the present invention, it is preferable that the negative electrode active material that is the main component of the negative electrode is formed of one material selected from the group consisting of lithium metal, lithium titanate, a carbon-based material, and a silicon-based oxide-based material.

[0042] Furthermore, the electrode active material according to the present invention is mainly composed of a heat-treated product containing pure black mass obtained by treating used lithium-ion batteries and a Li-based metal oxide, wherein the Li-based metal oxide is in the form of a plurality of metal salts containing Ni, Mn, Co, and Li as raw materials, respectively, and the heat-treated product is characterized in that it is heat-treated together with the black mass in a state in which the total amount of the plurality of metal salts is 20 to 5,000 parts by weight per 100 parts by weight of the black mass.

[0043] As a result, the electrode active material is obtained by heat treating the black mass with a total of 20 to 5,000 parts by weight of a plurality of metal salts per 100 parts by weight of the black mass. Therefore, even if the component compositions of the black mass vary significantly, it is possible to obtain a new and useful electrode active material at low cost through effective resource recycling.

[0044] The electrode active material of the present invention is characterized in that it has a layered rock salt crystal structure.

[0045] 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 components, and the two-dimensional diffusion of Li facilitates the battery reaction due to the insertion and desorption of Li ions, thereby making it possible to obtain the desired lithium-ion battery.

[0046] Furthermore, a lithium ion battery according to the present invention is a lithium ion battery that has a positive electrode, a negative electrode, and an electrolyte, and is repeatedly charged and discharged by a battery electrode reaction using lithium ions as a charge carrier, and is characterized in that the positive electrode active material that constitutes the main component of the positive electrode is formed from the electrode active material described above.

[0047] In addition, in the lithium ion battery of the present invention, it is preferable that the negative electrode active material that is the main component of the negative electrode is formed of one material selected from the group consisting of lithium metal, lithium titanate, carbon-based materials, and silicon-based oxide-based materials.

[0048] This makes it possible to obtain a lithium ion battery having desired battery characteristics that can be used for a variety of applications.

[0049] According to the method for producing an electrode active material of the present invention, an electrode active material is produced using black mass obtained by treating used lithium-ion batteries. The black mass and metal salts are mixed together so that the total amount of metal salts containing Ni, Mn, Co, and Li is 20 to 5,000 parts by weight per 100 parts by weight of the black mass, and the mixture is heat-treated. The black mass and metal salts are then reacted to produce the electrode active material. By freely selecting the total amount of metal salts to be mixed with the black mass from a wide range of 20 to 5,000 parts by weight per 100 parts by weight of the black mass, it is possible to produce an electrode active material with excellent practical battery characteristics, even if the state of used lithium-ion batteries varies widely or the component composition of the black mass varies greatly depending on the treatment conditions during the manufacturing process and the production unit.

[0050] Furthermore, the electrode active material can be produced simply by mixing black mass with multiple metal salts that serve as metal sources for the electrode active material and then heat treating the mixture. This eliminates the need to recover metal salts and the like from black mass, allows for the effective use of used lithium-ion batteries, and enables the production of the desired electrode active material at low cost.

[0051] Furthermore, since the mixing ratio of the black mass to the total amount of metal salts is varied depending on the component composition of the black mass, it is possible to mix the black mass with metal salts in an optimal range corresponding to the component composition of the black mass and then subject the mixture to heat treatment. This makes it possible to produce an electrode active material with good battery characteristics while promoting resource circulation, thereby ensuring a balance between resource circulation and battery characteristics.

[0052] Furthermore, when the black mass contains at least Ni, Mn, Co, Li, and C, and the content of the C component is less than 7.5% in terms of mass ratio, the black mass and the metal compounds are mixed so that the total amount of the metal salts is 20 to 350 parts by weight per 100 parts by weight of the black mass. In this case, since the amount of the Li component and the ternary material increases relatively, it is possible to obtain good battery characteristics that are highly practical even if the total amount of the metal salts mixed with the black mass is limited to 20 to 350 parts by weight per 100 parts by weight of the black mass, and this is suitable for effective resource utilization.

[0053] Furthermore, when the black mass contains at least Ni, Mn, Co, Li, and C, and the content of the C component exceeds 25% in terms of mass ratio, the black mass and the metal salts are mixed so that the total amount of the metal salts is 700 to 5,000 parts by weight per 100 parts by weight of black mass. In this case, since the amount of the Li component and the ternary material components is relatively reduced, it is possible to obtain an electrode active material with good battery characteristics by increasing the total amount of the metal salts to 700 to 5,000 parts by weight per 100 parts by weight of black mass. In this case, although the total amount of the metal salts increases, the black mass is utilized as effectively as possible, thereby contributing to the demand for resource recycling.

[0054] Furthermore, by using 3,500 to 5,000 parts by weight of the total amount of the metal salts relative to 100 parts by weight of the black mass, it is possible to produce an electrode active material having a good battery capacity and cycle characteristics that are comparable to those of a material obtained by synthesizing metal salts together.

[0055] Furthermore, after preparing a mixed solution by dissolving each metal powder containing each of the components in a solvent, the mixed solution is processed to prepare a precipitate, the metal salt is obtained from the precipitate, and the black mass and the metal salt are mixed together. This makes it possible to obtain a highly refined, high-quality metal salt, and to produce a good-quality electrode active material.

[0056] Furthermore, since the heat treatment is carried out at a temperature of 650 to 950°C for 1 to 4 hours, an electrode active material having the desired battery performance can be easily produced by appropriately adjusting the heat treatment temperature and heat treatment time.

[0057] Furthermore, the multiple metal salts are mixed with the black mass at an adjusted compounding ratio so that NMC111 can be formed when these multiple metal salts are mixed and synthesized, making it possible to obtain an electrode active material equivalent to NMC111 having a layered rock salt structure.

[0058] According to the method for producing a lithium ion battery of the present invention, a lithium ion battery having a positive electrode, a negative electrode, and an electrolyte, which repeats charge and discharge reactions through a battery electrode reaction using lithium ions as a charge carrier, and the positive electrode active material that forms the main part of the positive electrode is formed from the electrode active material produced by the above-mentioned production method, makes it possible to obtain a novel and useful lithium ion battery that can adequately handle cases where the component composition of black mass varies greatly from one another, without requiring the effort of recovering and purifying metal salts from black mass.

[0059] The electrode active material of the present invention is mainly composed of a heat-treated product containing pure black mass obtained by treating used lithium-ion batteries and a Li-based metal oxide, and the Li-based metal oxide is in the form of a plurality of metal salts, each of which contains Ni, Mn, Co, and Li as its raw material.The heat-treated product is heat-treated together with the black mass in a state in which the total of the plurality of metal salts is 20 to 5,000 parts by weight per 100 parts by weight of the black mass.Therefore, even if the component compositions of the black mass individually vary greatly, it is possible to obtain a new and useful electrode active material at low cost through effective resource recycling.

[0060] The lithium ion battery of the present invention has a positive electrode, a negative electrode, and an electrolyte, and is repeatedly charged and discharged by a battery electrode reaction using lithium ions as a charge carrier. The positive electrode active material that forms the main part of the positive electrode is formed from the electrode active material described above. Therefore, even if the component composition of black mass varies greatly from one individual to another, a novel and useful lithium ion battery can be obtained that can be sufficiently adapted to obtain the desired battery characteristics without the need for the effort of recovering and purifying metal salts from the black mass.

[0061] Furthermore, since the negative electrode active material that is the main component of the negative electrode is formed of one material selected from the group consisting of lithium metal, lithium titanate, carbon-based materials, and silicon-based oxide-based materials, it is possible to obtain a lithium-ion battery that has desired battery characteristics that can be used for a variety of applications.

[0062] The present invention relates to a lithium ion battery, and a method for manufacturing the same.

[0063] Next, an embodiment of the present invention will be described in detail.

[0064] An electrode active material according to one embodiment of the present invention is prepared by mixing 100 parts by weight of black mass obtained by treating used lithium-ion batteries with 20 to 5,000 parts by weight of a plurality of metal salts each containing Ni, Mn, Co, and Li, and then subjecting the mixture to heat treatment to cause a reaction between the black mass and the metal salts.

[0065] In this way, by freely selecting the total amount of metal salts to be mixed with the black mass within a wide range of 20 to 5,000 parts by weight per 100 parts by weight of black mass, it is possible to adequately address the individual component compositions of the black mass, even if the state of used lithium-ion batteries varies widely or the component compositions of the black mass vary significantly depending on the processing conditions during the manufacturing process or the production unit, and it becomes possible to produce an electrode active material with good battery characteristics while promoting effective recycling of resources.

[0066] Furthermore, the electrode active material can be produced simply by mixing black mass with multiple metal salts that serve as metal sources for the electrode active material and then heat treating the mixture. This eliminates the need to recover metal salts, etc. from black mass, and allows for the effective use of used lithium-ion batteries, making it possible to obtain a practical, high-capacity, high-performance electrode active material at low cost.

[0067] The method for producing the electrode active material will be described in detail below.

[0068] First, metal powders containing Li, Ni, Mn, and Co are prepared. The types of metal powders are not particularly limited, and various acid salts such as acetate compounds, nitrate compounds, carbonate compounds, and chlorides can be used. Then, these metal powders are weighed out so that the molar ratio of Li, Ni, Mn, and Co is, for example, Li:Ni:Mn:Co=1:1 / 3:1 / 3:1 / 3, and these weighed powders are dissolved in a large amount of a solvent such as pure water to prepare a mixed solution.

[0069] On the other hand, a precipitant solution is prepared by dissolving a precipitant such as citric acid in a large amount of solvent such as pure water.

[0070] Then, the mixed solution and the precipitant solution are mixed to form a precipitate, which is then filtered to remove the supernatant, and the resulting precipitate is thoroughly washed and dried to obtain a metal salt.

[0071] Next, the black mass and the metal salt are mixed so that the total content of the metal salt is 20 to 5,000 parts by weight per 100 parts by weight of the black mass, and the mixture is heat-treated at a predetermined heat treatment temperature for a predetermined time, and then allowed to cool naturally to room temperature, thereby producing the above-mentioned electrode active material.

[0072] The total content of the metal salts is set to 20 to 5,000 parts by weight per 100 parts by weight of black mass for the following reasons.

[0073] As described above, black mass is obtained by treating used lithium-ion batteries (hereinafter referred to as "material to be treated"). However, the component composition of the material to be treated varies depending on the material, and the component composition of black mass varies significantly depending on the processing conditions in the black mass production process and the production unit. That is, some black masses contain a high content of Li and the above-mentioned ternary materials, while others contain a low content. Therefore, in order to effectively utilize black mass to recycle resources and obtain a practical electrode active material, it is desirable to set the content of metal salts within a wide range so as to accommodate the component composition of each black mass.

[0074] If the total metal salt content is less than 20 parts by weight per 100 parts by weight of black mass, sufficient battery capacity cannot be obtained even if the black mass contains a considerable amount of ternary material or Li component because the total metal salt content is too low, so at least 20 parts by weight is necessary.On the other hand, if the total metal salt content exceeds 5,000 parts by weight per 100 parts by weight of black mass, the total metal salt content is so large that good battery characteristics can be obtained even if the black mass contains only a small amount of ternary material or Li component, but there is a risk that the demand for recycling effective resources will not be met.

[0075] Therefore, in this embodiment, even if the component composition of black mass varies greatly from one to another, the total content of metal salts is set to 20 to 5000 parts by weight per 100 parts by weight of black mass, from the viewpoint of ensuring practical battery characteristics while effectively reusing resources.

[0076] By varying the mixing ratio of the black mass and the total amount of metal salts depending on the component composition of the black mass, it is possible to ensure a balance between resource circulation and battery characteristics, and it is possible to produce an electrode active material with good battery characteristics while promoting resource circulation.

[0077] Furthermore, as a result of intensive research by the present inventors, it was found that although black mass contains a certain amount of base metals such as Al, Cu, and Fe, the variation in the component composition of black mass is related to the interrelationship between the ternary material (Ni, Mn, Co) and Li component used in one electrode active material, and the C component widely used in the other electrode active material. That is, when the content of the C component is low, the total content of the ternary material and Li component tends to increase relatively, and when the content of the C component is high, the total content of the ternary material and Li component tends to decrease relatively.

[0078] When the C component content in the black mass is less than 7.5 mass%, the contents of the ternary material and Li component are high, so the total metal salt content is preferably 20 to 350 parts by weight per 100 parts by weight of black mass. That is, even when the C component content in the black mass is less than 7.5 mass%, if the total metal salt content is less than 20 parts by weight per 100 parts by weight of black mass, the metal salt content will be relatively low, as described above, and sufficient battery capacity may not be obtained. On the other hand, in this case, because the black mass contains a large amount of ternary material and Li component, a content of 350 parts by weight per 100 parts by weight of black mass is sufficient, and a content of more than 350 parts by weight per 100 parts by weight of black mass may actually result in a decrease in battery capacity.

[0079] Therefore, when the content of the C component in the black mass is less than 7.5 mass%, it is preferable to mix the black mass and the metal salts so that the total content of the metal salts is 20 to 350 parts by weight per 100 parts by weight of the black mass, as described above.

[0080] Furthermore, when the content of the C component in the black mass exceeds 25 mass%, the total content of the metal salts is preferably 700 to 5,000 parts by weight, more preferably 3,500 to 5,000 parts by weight, per 100 parts by weight of the black mass. That is, when the content of the C component in the black mass exceeds 25 mass%, the contents of the ternary material and the Li component in the black mass are relatively reduced. Therefore, if the total content of the metal salts is less than 700 parts by weight per 100 parts by weight of the black mass, sufficient battery capacity may not be obtained. Meanwhile, in this case, although the battery capacity can be improved by increasing the total content of the metal salts, if the total content exceeds 5,000 parts by weight per 100 parts by weight of the black mass, the effect of promoting the recycling of resources may be reduced.

[0081] Therefore, when the content of component C in the black mass exceeds 25 mass%, it is preferable to mix the black mass and the metal salt so that the total content of the metal salt is 700 to 5,000 parts by weight per 100 parts by weight of the black mass.

[0082] In particular, it is more preferable from the viewpoint of improving battery characteristics that the total content of metal salts is 3,500 to 5,000 parts by weight per 100 parts by weight of black mass. By increasing the total content of metal salts in this way, it is possible to improve the battery capacity and obtain cycle characteristics that are comparable to those in the case where an electrode active material is produced using metal salts alone, thereby achieving both recycling of resources and battery characteristics.

[0083] The heat treatment temperature is not particularly limited, but is usually preferably in the range of 650°C to 950°C. If the heat treatment temperature is low, below 650°C, sufficient crystallization may not occur, making it difficult to obtain the desired capacity density. On the other hand, if the heat treatment temperature is high, above 950°C, crystallization may proceed excessively, inhibiting the movement of Li ions and resulting in deterioration of cycle characteristics.

[0084] The heat treatment time is not particularly limited, but is preferably about 1 to 4 hours. A heat treatment time of less than 1 hour may result in insufficient crystallization, making it difficult to obtain the desired capacity density. On the other hand, a heat treatment time of more than 4 hours may result in excessive crystallization, inhibiting the movement of Li ions and potentially deteriorating cycle characteristics.

[0085] As will be apparent from the examples described later, this electrode active material has a layered rock-salt crystal structure. That is, metal oxide layers containing Ni, Co, and Mn are formed at regular intervals, and lithium layers are interposed between the metal oxide layers. Li ions in the lithium layers diffuse two-dimensionally, causing insertion and desorption reactions, thereby carrying out charge and discharge.

[0086] As described above, according to the method for producing an electrode active material in this embodiment, an electrode active material is produced using black mass obtained by treating used lithium-ion batteries. The black mass and the metal salts are mixed together so that a total of 20 to 5,000 parts by weight of a plurality of metal salts containing Ni, Mn, Co, and Li is mixed with 100 parts by weight of the black mass, and the mixture is heat-treated. The black mass and the metal salts are then reacted to produce the electrode active material. Therefore, even if the state of used lithium-ion batteries varies widely or the component composition of the black mass varies significantly depending on the processing conditions during the manufacturing process and the production unit, the individual component compositions of the black mass can be adequately addressed, and it is possible to produce an electrode active material having good battery characteristics while promoting effective recycling of resources.

[0087] Furthermore, the electrode active material can be produced simply by mixing black mass with multiple metal salts that serve as metal sources for the electrode active material and then heat treating the mixture. This eliminates the need to recover metal salts, etc. from black mass, and allows for the effective use of used lithium-ion batteries, making it possible to obtain a practical, high-capacity, high-performance electrode active material at low cost.

[0088] Furthermore, since the mixing ratio of the black mass to the total amount of metal salts is varied depending on the component composition of the black mass, a balance between resource circulation and battery characteristics can be ensured, and it becomes possible to produce an electrode active material with good battery characteristics while promoting resource circulation.

[0089] Next, a lithium ion battery using the electrode active material will be described.

[0090] FIG. 1 is a schematic cross-sectional view showing a lithium ion battery (cylindrical type) according to the present invention, and FIG. 2 is an enlarged cross-sectional view of part A in FIG. 1. In this embodiment, the present electrode active material is used as a positive electrode active material.

[0091] As shown in Fig. 1, this lithium-ion battery has a convex positive electrode terminal 1 made of Al or the like, and a cylindrical negative electrode case 2 with a bottom made of Cu or the like that also serves as a negative electrode terminal. The negative electrode case 2 houses a plurality of battery main bodies 6, each of which includes a positive electrode 3, a separator 4, and a negative electrode 5, in a stacked configuration. The positive electrode 3 is electrically connected to the positive electrode terminal 1 via a positive electrode support member 7, and the negative electrode 5 is electrically connected to the negative electrode terminal (negative electrode case 2). The positive electrode terminal 1 and the negative electrode case 2 are electrically insulated by insulating plates 8 and 9 and a gasket 10. The internal space of the battery main body 6 is filled with an electrolyte (electrolytic solution).

[0092] As shown in Fig. 2, the positive electrode 3 has positive electrode active material layers 13a and 13b formed on both main surfaces of a positive electrode current collector 12 made of Al foil or the like. The negative electrode 5 has negative electrode active material layers 15a and 15b, mainly made of a carbon-based material or lithium metal, formed on both main surfaces of a negative electrode current collector 14 made of Cu foil or the like. The separator 4 is formed of a porous sheet or film such as a microporous membrane, woven fabric, or nonwoven fabric, and is interposed between the positive electrode 3 and the negative electrode 5. The internal space of the battery body 6 is filled with an electrolyte 11.

[0093] The negative electrode active material used in the negative electrode active material layer 15 is not particularly limited, and may be a carbon-based material such as lithium metal, graphite, or graphene, or lithium titanate, and may be appropriately selected as needed in consideration of the desired energy density, cost, and the like.

[0094] Next, an example of a method for manufacturing the lithium ion battery will be described in detail.

[0095] 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, and a solvent is added to form a slurry. The slurry is then applied to the positive electrode current collector 12 by any coating method and dried to form positive electrode active material layers 13 a and 13 b on both main surfaces of the positive electrode current collector 12, thereby obtaining the positive electrode 3.

[0096] The conductive additive is not particularly limited, and examples thereof include conductive carbons such as graphite, carbon black, acetylene black, carbon nanotubes, and carbon nanohorns, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyacene. Two or more types of conductive additives can also be mixed and used.

[0097] The binder is not particularly limited, and various resins such as polyvinylidene fluoride (PVDF), polyethylene, polyhexafluoropropylene, polytetrafluoroethylene, polyethylene oxide, and carboxymethyl cellulose can be used.

[0098] Furthermore, the solvent is not particularly limited, and examples of the solvent that can be used include basic solvents such as N-methyl-2-pyrrolidone (NMP), 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 water.

[0099] The type of organic solvent, the blending ratio of the organic compound to the organic solvent, the type and amount of additives, etc. can be set as desired.

[0100] Next, using the same method and procedure as for the positive electrode 3, negative electrode active material layers 15a, 15b are formed on both main surfaces of the negative electrode current collector 14, thereby producing the negative electrode 5. The negative electrode 5 is impregnated with an electrolytic solution 11 to soak the negative electrode 5 with the electrolyte 11, and the positive electrode 3 is further impregnated with the electrolyte 11. Next, the separator 4 impregnated with the electrolyte 11 is placed in the negative electrode case 2, and the electrolyte 11 is then injected into the internal space. Then, a gasket 10 is placed around the periphery, and the negative electrode case 2 and the positive electrode support member 7 are fixed together using a crimping machine or the like to seal the exterior, thereby producing a lithium-ion battery.

[0101] The electrolyte 11 is interposed between the positive electrode 3 and the negative electrode 5, which is the counter electrode, and transports charge carriers between the two electrodes. Examples of such electrolyte 11 include an electrolyte solution in which an electrolyte salt is dissolved in an organic solvent, a polymer-based electrolyte solution in which a polymer such as polyethylene oxide is added to this, and an ionic liquid-based electrolyte solution in which an ionic liquid such as 1-ethyl-3-methylimidazolium tetrafluoroborate is used and an electrolyte salt is dissolved therein.

[0102] Here, the electrolyte salt is, for example, LiPF ６ , LiClO ４ , LiBF ４ , F ２ LiNO ４ S ２ , C ４ F ９ LiO ３ S, LiN (CF ３ SO ２ )２ , LiCF ３ SO ３ , C ４ F ９ LiO ３ S, F ２ LiNO ４ S ２ , Li(CF ３ SO ２ ) ２ C, LiH ２ P.O. ４ , LiCl, (CH ３ CO) ２ Various lithium salts such as Li can be used.

[0103] As the organic solvent, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, dimethoxyethane, and mixed solvents thereof can be used.

[0104] Furthermore, a solid electrolyte may be used for the electrolyte 11. Either an inorganic solid electrolyte or a polymer solid electrolyte may be used. Examples of inorganic solid electrolytes include Li ７ La ３ Zr ２ O 12 Ya(La,Ti)TiO ３ oxide-type solid electrolytes such as Li 10 GeP ２ S 12 Examples of the polymer-based solid electrolyte include various copolymers such as polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer, and vinylidene fluoride-ethylene copolymer.

[0105] As described above, the lithium ion battery has the positive electrode 3, the negative electrode 5, and the electrolyte 11, and repeats charge and discharge reactions through a battery electrode reaction using lithium ions as a charge carrier. The positive electrode active material that constitutes the main part of the positive electrode 3 is formed from the electrode active material produced by the above-mentioned production method. Therefore, it is possible to easily obtain, at low cost, a new and useful lithium ion battery that is safe, has a long life, and contributes to the effective recycling of used lithium ion batteries.

[0106] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. In the above-described embodiment, the compounding ratio of the plurality of metal salts mixed into the black mass is adjusted so that NMC111 can be formed when the metal salts are mixed and heat-treated to synthesize them. However, the metal salts may contain Li, Ni, Mn, and Co, and for example, NMC433 (LiNi 0.4 Mn 0.3 Co 0.3 ), NMC622 (LiNi 0.6 Mn 0.2 Co 0.２ ) and NMC811 (LiNi 0.8 Mn 0.1 Co 0.1 It goes without saying that the desired effects described above can be achieved even if the blending ratio is adjusted so that the above-mentioned mixture can be formed.

[0107] In the above embodiment, a precipitate is prepared from a mixed solution in which each metal powder is dissolved in a solvent, and the precipitate is then washed and dried to obtain the metal salts. However, it is also possible to simply mix multiple powdered metal salts with black mass.

[0108] Furthermore, although the above embodiment has been described with reference to a cylindrical lithium ion battery, the battery shape is not particularly limited, and it can also be applied to a square, sheet, coin, etc. Furthermore, the packaging method is not particularly limited, and a metal case, molded resin, aluminum laminate film, etc. may be used.

[0109] Next, examples of the present invention will be described in detail.

[0110] [Sample Preparation] (Sample No. 1) Black mass was procured from Kawashima Co., Ltd. 100 parts by weight of black mass was mixed with 20 parts by weight of metal salts so that the compounding ratio of Li, Ni, Mn, and Co was Li:Ni:Mn:Co=1:1 / 3:1 / 3:1 / 3 in molar ratio when these metal salts were mixed and synthesized, and the mixture was heat-treated to prepare a powder sample of Sample No. 1.

[0111] That is, as a Ni source, (CH ３ COO) ２ Ni・4H ２ O (molecular weight: 248.84), as a Mn source (CH ３ COO) ２ Mn 4H ２ O, (molecular weight: 245.09), as a Co source (CH ３ COO) ２ Co・4H ２ O (molecular weight: 249.08), CH as a Li source ３ COOLi 2H ２ Each metal powder of 0 (molecular weight: 102.02) was prepared.

[0112] And (CH ３ COO) ２ Ni・4H ２ 82.95 g of O, (CH ３ COO) ２ Mn 4H ２ 81.70 g of O, (CH ３ COO) ２ Co・4H ２ 83.03 g of O, CH ３ COOLi 2H ２ 107.12 g of each of O was weighed out, and these weighed items (total 354.80 g) were dissolved in 2000 g of pure water to prepare a mixed solution.

[0113] On the other hand, citric acid monohydrate ((HOOCCH ２ ) ２ C(OH)COOH・H ２ O) (molecular weight 210.14) was dissolved in 2000 g of pure water to prepare an aqueous citric acid solution.

[0114] Next, the mixed solution and the citric acid aqueous solution were mixed to produce a precipitate, which was then filtered through a paper filter to remove the supernatant. The precipitate was then washed three times and dried to obtain a metal salt (NMC111). 20 g of the metal salt was mixed with 100 g of black mass, heat-treated at 800°C for 1 hour, and then allowed to cool naturally to room temperature. The mixture was then sieved using a stainless steel mesh with 75 μm openings to produce a powder sample (electrode active material) designated Sample No. 1.

[0115] Next, 2.7 g of the powder sample was mixed with 6 g of N-methyl-2-pyrrolidone (hereinafter referred to as "NMP") and stirred for 120 seconds using a stirring and defoaming apparatus (Kurabo Industries, Ltd., Mazerustar). Thereafter, 0.15 g of conductive carbon (Lion Corporation, EC-600-JD) as a conductive additive was added to the mixture, and the mixture was further stirred for 360 seconds using the stirring and defoaming apparatus to obtain a mixed product.

[0116] Next, an NMP solution was prepared by dissolving 5 wt % polyvinylidene fluoride in NMP. 3.0 g of the MNP solution was added to the stirred mixture, and the mixture was stirred for 360 seconds using the stirring and degassing device, followed by 180 seconds, another 360 seconds, and then degassed for 90 seconds to obtain a coating solution.

[0117] Next, the coating solution was applied onto an Al substrate using a doctor blade method to form a coating film with a thickness of 300 μm, and then dried at a temperature of 100° C. for 8 hours. As a result, a positive electrode was produced in which the Al substrate was used as a positive electrode current collector and the powder sample was used as a positive electrode active material.

[0118] Next, lithium metal was placed on a Cu substrate, and the Cu substrate was used as a negative electrode current collector, and a negative electrode was fabricated using lithium metal as the main negative electrode active material. A separator made of polypropylene was then interposed between the positive electrode and the negative electrode, and a carbonate-based electrolyte solution was further injected between the positive electrode and the negative electrode, thereby fabricating a flat cell (simple experimental cell) of Sample No. 1.

[0119] This flat cell was charged at a C rate of 0.1 C up to 4.6 V and then discharged down to 2.0 V, and the capacity density (initial value) was 90.3 mAh / g.

[0120] (Sample No. 2) A powder sample of Sample No. 2 was prepared in the same manner and procedure as Sample No. 1, except that black mass and metal salts were mixed so that the total content of metal salts was 35 parts by weight per 100 parts by weight of black mass.

[0121] Then, using this powder sample, a flat cell of sample number 1 was prepared in the same manner and procedure as sample number 1, and charge and discharge were carried out, resulting in a capacity density (initial value) of 96.8 mAh / g.

[0122] (Sample No. 3) A powder sample of Sample No. 3 was prepared in the same manner and procedure as Sample No. 1, except that black mass and metal salts were mixed so that the total content of metal salts was 175 parts by weight per 100 parts by weight of black mass.

[0123] Then, using this powder sample, a flat cell of sample number 3 was prepared in the same manner and procedure as sample number 1, and charge and discharge were carried out, resulting in a capacity density (initial value) of 122.2 mAh / g.

[0124] (Sample No. 4) A powder sample of Sample No. 4 was prepared in the same manner and procedure as Sample No. 1, except that black mass and metal salts were mixed so that the total content of metal salts was 350 parts by weight per 100 parts by weight of black mass.

[0125] Then, using this powder sample, a flat cell of sample number 4 was prepared in the same manner and procedure as sample number 1, and charge and discharge were carried out, resulting in a capacity density (initial value) of 141.3 mAh / g.

[0126] (Sample No. 5) A powder sample of Sample No. 5 was prepared in the same manner and procedure as Sample No. 1, except that black mass and metal salts were mixed so that the total content of metal salts was 700 parts by weight per 100 parts by weight of black mass.

[0127] Then, using this powder sample, a flat cell of sample number 5 was prepared in the same manner and procedure as sample number 1, and charge and discharge were carried out, and the capacity density (initial value) was 129.5 mAh / g.

[0128] (Sample No. 6) A powder sample of Sample No. 6 was prepared in the same manner and procedure as Sample No. 1, except that black mass and metal salts were mixed so that the total content of metal salts was 3,500 parts by weight per 100 parts by weight of black mass.

[0129] Then, using this powder sample, a flat cell of sample number 6 was prepared in the same manner and procedure as sample number 1, and charge and discharge were carried out, resulting in a capacity density (initial value) of 127.3 mAh / g.

[0130] (Sample No. 7) A powder sample of Sample No. 7 was prepared in the same manner and procedure as Sample No. 1, except that black mass and metal salts were mixed so that the total content of metal salts was 5,000 parts by weight per 100 parts by weight of black mass.

[0131] Then, using this powder sample, a flat cell of sample number 7 was prepared in the same manner and procedure as sample number 1, and charge and discharge were carried out, resulting in a capacity density (initial value) of 120.7 mAh / g.

[0132] (Sample No. 8) The black mass manufactured by Kawashima Co., Ltd., used in Sample Nos. 1 to 7 above, was used as a powder sample for Sample No. 8, and a flat cell for Sample No. 8 was prepared using this powder sample in the same manner and procedure as Sample No. 1.

[0133] When this flat cell was charged and discharged in the same manner and procedure as in Sample No. 1, the capacity density (initial value) was 88.7 mAh / g.

[0134] (Sample No. 9) The metal salt (NMC111) prepared in Sample No. 1 was used as a powder sample of Sample No. 9, and a flat cell of Sample No. 9 was prepared using this powder sample in the same manner and procedure as Sample No. 1. Charge and discharge were performed, and the capacity density (initial value) was 144.3 mAh / g.

[0135] [Sample Evaluation] (Component Composition of Sample No. 8 (Black Mass Sample)) The component composition of Sample No. 8 (Black Mass Sample) was measured using an ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry) (iCAP PRO XP, manufactured by Thermo Fisher Scientific).

[0136] Table 1 shows the element types and their mass ratios (mass%).

[0137]

[0138] As shown in Table 1, the black mass sample of sample number 8 contained 32.2 mass% of Ni component, 12.8 mass% of Co component, and 18.1 mass% of Mn component, and it was confirmed that the ternary material was contained in a considerable amount of 63.1 mass% in total, while the C component was only 7.2 mass%.

[0139] (Identification of Crystal Structure) For each of the powder samples of Sample Nos. 4, 8 (black mass), and 9 (NMC111), an X-ray diffraction spectrum was measured by irradiating characteristic X-rays (Kα) using a SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-ray Spectrometry) (FlexSEM 1000 II, manufactured by Hitachi High-Tech Corporation).

[0140] FIG. 3 shows the X-ray diffraction spectrum profiles of the powder samples Nos. 4, 8, and 9, with the horizontal axis representing the diffraction angle 2θ (°) and the vertical axis representing the diffraction intensity (a.u.).

[0141] It is known that sample number 9, NMC111, has a layered rock-salt type crystal structure, and since the profiles of sample numbers 4 and 8 are similar to that of sample number 9, it is believed that sample numbers 4, 8, and 9 all have a layered rock-salt type crystal structure, and it was confirmed that they have a crystal structure suitable for an electrode active material for a lithium-ion battery.

[0142] (Cycle Characteristics) Each of the samples Nos. 1 to 9 was charged and discharged 100 times in a voltage range of 2.0 V to 4.6 V, and the cycle characteristics were evaluated.

[0143] Table 2 shows the metal salt content (parts by weight) of Sample Nos. 1 to 9, the initial capacity density, and the capacity density (mAh / g) after each cycle.

[0144]

[0145] Sample No. 8 was a black mass sample, and had an initial capacity density of 88.7 mAh / g, a capacity density of 61.1 mAh / g after 50 cycles, and a capacity density of 55.4 mAh / g after 100 cycles.

[0146] Sample No. 9 was an NMC111 sample, and the initial capacity density was 144.3 mAh / g. The capacity density after 50 cycles was 85.1 mAh / g, which was 58% of the initial value, and the capacity density after 100 cycles was 80.3 mAh / g, which was 55% of the initial value.

[0147] In contrast, Samples 1 to 7 had initial capacity densities of 90.3 to 141.3 mAh / g, which were higher than that of Sample 8 (black mass sample). As can be seen from Samples 1 to 7, the capacity density was improved by mixing 20 to 5,000 parts by weight of black mass with 100 parts by weight of metal salt. The cycle characteristics were also comparable, with the capacity densities after 50 cycles being 53 to 69% of the initial value, and even after 100 cycles being 48 to 66% of the initial value, demonstrating that the cycle characteristics were comparable to those of Sample 9 (NMC111).

[0148] As is clear from Example 1, in black mass with a high content of ternary materials, the initial capacity density increases as the metal salt content increases when the total metal salt content is 350 parts by weight or less, and the initial capacity density tends to decrease when the total metal salt content exceeds 350 parts by weight. Therefore, it was found that a metal salt content of 20 to 350 parts by weight per 100 parts by weight of black mass is preferable. In particular, as shown in Sample No. 4, when the total metal salt content is 350 parts by weight, the initial capacity density is large at 141.3 mAh / g, and the cycle characteristics are such that a capacity density of 54% of the initial value can be maintained after 50 cycles, and a capacity density of 50% of the initial value can be maintained even after 100 cycles, demonstrating excellent battery characteristics comparable to those of Sample No. 9 (NMC111).

[0149] That is, by mixing black mass with metal salts in the range of 20 to 5,000 parts by weight per 100 parts by weight of black mass and then heat treating the mixture, it is possible to obtain a lithium ion battery with highly practical and desirable battery characteristics. Furthermore, when the content of C component in the black mass is less than 7.5 mass%, the total content of metal salts is preferably 20 to 350 parts by weight per 100 parts by weight of black mass, and it has been confirmed that this makes it possible to obtain a lithium ion battery with good battery characteristics while effectively recycling resources.

[0150] [Sample Preparation] (Sample No. 11) Black mass was procured from Envipro Holdings, Inc. 100 parts by weight of black mass was mixed with 20 parts by weight of metal salts in a manner similar to that of Sample No. 1 (Example 1) so that the compounding ratio of Li, Ni, Mn, and Co was Li:Ni:Mn:Co=1:1 / 3:1 / 3:1 / 3 in molar ratios when these metal salts were mixed and synthesized. The mixture was then heat-treated to prepare a powder sample of Sample No. 11. This powder sample was then used to prepare a flat cell of Sample No. 11.

[0151] This flat cell was charged at a C rate of 0.1 C up to 4.6 V and then discharged down to 2.0 V, and the capacity density (initial value) was 11.7 mAh / g.

[0152] (Sample No. 12) A powder sample was prepared in the same manner and procedure as Sample No. 11, except that black mass and metal salts were mixed so that the total content of metal salts was 35 parts by weight per 100 parts by weight of black mass. This powder sample was used to prepare a flat cell of Sample No. 12.

[0153] When this flat cell was charged and discharged in the same manner and procedure as in sample number 11, the capacity density (initial value) was 16.8 mAh / g.

[0154] (Sample No. 13) A powder sample was prepared in the same manner and procedure as Sample No. 11, except that black mass and metal salts were mixed so that the total content of metal salts was 175 parts by weight per 100 parts by weight of black mass. This powder sample was used to prepare a flat cell of Sample No. 13.

[0155] When this flat cell was charged and discharged in the same manner and procedure as for sample number 11, the capacity density (initial value) was 38.3 mAh / g.

[0156] (Sample No. 14) A powder sample was prepared in the same manner and procedure as Sample No. 11, except that black mass and metal salts were mixed so that the total content of metal salts was 350 parts by weight per 100 parts by weight of black mass. This powder sample was used to prepare a flat cell of Sample No. 14.

[0157] When this flat cell was charged and discharged in the same manner and procedure as for sample number 14, the capacity density (initial value) was 66.8 mAh / g.

[0158] (Sample No. 15) A powder sample was prepared in the same manner and procedure as Sample No. 11, except that black mass and metal salts were mixed so that the total content of metal salts was 700 parts by weight per 100 parts by weight of black mass. This powder sample was used to prepare a flat cell of Sample No. 15.

[0159] When this flat cell was charged and discharged in the same manner and procedure as for sample number 15, the capacity density (initial value) was 81.6 mAh / g.

[0160] (Sample No. 16) A powder sample was prepared in the same manner and procedure as Sample No. 11, except that black mass and metal salts were mixed so that the total content of metal salts was 3,500 parts by weight per 100 parts by weight of black mass. This powder sample was used to prepare a flat cell of Sample No. 16.

[0161] When this flat cell was charged and discharged in the same manner and procedure as for sample No. 11, the capacity density (initial value) was 118.7 mAh / g.

[0162] (Sample No. 17) A powder sample was prepared in the same manner and procedure as Sample No. 11, except that black mass and metal salts were mixed so that the total content of metal salts was 5,000 parts by weight per 100 parts by weight of black mass. This powder sample was used to prepare a flat cell of Sample No. 17.

[0163] When this flat cell was charged and discharged in the same manner and procedure as for sample No. 11, the capacity density (initial value) was 129.8 mAh / g.

[0164] (Sample No. 18) The black mass manufactured by Envipro Holdings, Inc., used in Sample Nos. 11 to 17 above, was used as a powder sample for Sample No. 18, and a flat cell for Sample No. 18 was prepared using this powder sample in the same manner and procedure as for Sample No. 11.

[0165] When this flat cell was charged and discharged in the same manner and procedure as for sample No. 11, the capacity density (initial value) was 8.1 mAh / g.

[0166] [Evaluation of Samples] (Component Composition of Sample No. 18 (Black Mass Sample)) As in Example 1, the component composition of Sample No. 18 (black mass sample) was measured using ICP-OES.

[0167] Table 3 shows each element type and its mass fraction (mass%).

[0168]

[0169] As shown in Table 3, the black mass sample of sample number 18 contained 4.9 mass% Ni, 4.7 mass% Co, and 4.2 mass% Mn, with a total of only 13.8 mass% of ternary materials, while the C content was high at 30.5 mass%. In other words, it was confirmed that the black mass sample of sample number 18 contained more C and less ternary materials than the black mass manufactured by Kawashima Co., Ltd. (Table 1: sample number 8) used in Example 1.

[0170] (Cycle Characteristics) Each of Samples 11 to 18 was charged and discharged 100 times in a voltage range of 2.0 V to 4.6 V, and the cycle characteristics were evaluated.

[0171] Table 4 shows the metal content (parts by weight), the initial capacity density, and the capacity density (mAh / g) after each cycle for Sample Nos. 11 to 18. Note that Table 4 also lists Sample No. 9 (NMC111) from Example 1.

[0172]

[0173] Sample No. 18 is a black mass sample, and the total content of the ternary materials is only 13.8 mass %, so as described above, the initial capacity density was found to be extremely low at 8.1 mAh / g.

[0174] As is clear from samples 11 to 17, the initial value of the capacity density increases as the metal salt content increases, and the battery characteristics are improved.

[0175] In particular, samples 15 to 17, in which the total content of metal salts was 700 to 5,000 parts by weight per 100 parts by weight of black mass, showed an improved initial capacity density of 81.6 to 129.8 mAh / g, demonstrating that increasing the content of metal salts improved the battery characteristics.

[0176] Of these, sample No. 16 had a large initial capacity density of 118.7 mAh / g, and the cycle characteristics showed that it was possible to maintain a capacity density of 57% of the initial value after 50 cycles and 52% of the initial value even after 100 cycles. Furthermore, sample No. 17 had an even improved initial capacity density of 129.8 mAh / g, and the cycle characteristics showed that it was possible to maintain a capacity density of about 57% of the initial value both after 50 cycles and after 100 cycles.

[0177] Thus, it was confirmed that samples 16 and 17, in which the total metal salt content was 3,500 to 5,000 parts by weight per 100 parts by weight of black mass, were able to obtain sufficient capacity density and cycle characteristics comparable to those of sample 9 (NMC111).

[0178] From the above, it was found that even when the content of ternary materials in the black mass is low and the content of component C exceeds 25 mass%, battery performance can be improved compared to black mass alone by mixing black mass with metal salts in a range of 20 to 5,000 parts by weight per 100 parts by weight of black mass and then heat-treating the mixture. In this case, a total metal salt content of 700 to 5,000 parts by weight per 100 parts by weight of black mass is preferred, as this improves battery performance to a level that is practical. Furthermore, a more preferred range of total metal salt content is 3,500 to 5,000 parts by weight per 100 parts by weight of black mass. This allows battery performance comparable to that of metal salts alone, even when the content of ternary materials in the black mass is low. It was found that a lithium-ion battery with good battery performance can be obtained while recycling resources to the greatest extent possible.

[0179] By mixing black mass and a metal salt so that 20 to 5,000 parts by weight of the metal salt is used for 100 parts by weight of the black mass obtained from used lithium ion batteries and then subjecting the mixture to heat treatment, a new and useful electrode active material can be produced for a wide range of component compositions of black mass without the need for the effort of recovering the metal salt or metal material, and a lithium ion battery using this electrode active material can be obtained.

[0180] 3 Positive electrode active material (electrode active material) 4 Positive electrode 5 Negative electrode active material 6 Negative electrode 8 Electrolyte

Claims

1. A method for producing an electrode active material using black mass obtained by treating used lithium-ion batteries, comprising: mixing the black mass and metal salts so that a total of 20 to 5,000 parts by weight of a plurality of metal salts containing Ni, Mn, Co, and Li is contained per 100 parts by weight of the black mass; subjecting the mixture to heat treatment; and reacting the black mass with the metal salts to produce the electrode active material.

2. The method for producing an electrode active material according to claim 1, wherein the mixing ratio of the black mass to the total amount of metal salts is varied depending on the component composition of the black mass.

3. The method for producing an electrode active material according to claim 1 or 2, wherein the black mass contains at least Ni, Mn, Co, Li, and C, and when the content of the C component is less than 7.5% in terms of mass ratio, the black mass and the metal salts are mixed so that the total amount of the metal salts is 20 to 350 parts by weight per 100 parts by weight of the black mass.

4. The method for producing an electrode active material according to claim 1 or 2, characterized in that the black mass contains at least Ni, Mn, Co, Li, and C, and when the content of the C component exceeds 25% in terms of mass ratio, the black mass and the metal salts are mixed so that the total amount of the metal salts is 700 to 5,000 parts by weight per 100 parts by weight of the black mass.

5. The method for producing an electrode active material according to claim 4, wherein the total amount of said metal salts is 3,500 to 5,000 parts by weight per 100 parts by weight of said black mass.

6. A method for producing an electrode active material according to claim 1 or 2, characterized in that a mixed solution is prepared by dissolving each metal powder containing each component in a solvent, the mixed solution is treated to prepare a precipitate, and the metal salt is obtained from the precipitate, and the black mass and the metal salt are mixed.

7. The method for producing an electrode active material according to claim 1 or 2, wherein the heat treatment is carried out at a temperature of 650 to 950°C.

8. The method for producing an electrode active material according to claim 1 or 2, wherein the heat treatment is carried out for 1 to 4 hours.

9. When the plurality of metal salts are mixed and synthesized, the composition formula is LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O ２ 3. The method for producing an electrode active material according to claim 1, wherein the compounding ratio is adjusted and the black mass is mixed so as to form a metal oxide represented by the formula:

10. A method for manufacturing a lithium ion battery having a positive electrode, a negative electrode, and an electrolyte, which is repeatedly charged and discharged by a battery electrode reaction using lithium ions as a charge carrier, wherein the positive electrode active material that forms the main component of the positive electrode is an electrode active material manufactured by the manufacturing method described in claim 1 or claim 2.

11. A method for manufacturing a lithium ion battery according to claim 10, characterized in that the negative electrode active material that forms the main part of the negative electrode is formed of one material selected from the group consisting of lithium metal, lithium titanate, carbon-based materials, and silicon oxide-based materials.

12. An electrode active material comprising primarily a heat-treated material containing pure black mass obtained by treating used lithium-ion batteries and Li-based metal oxides, wherein the Li-based metal oxides are in the form of multiple metal salts containing Ni, Mn, Co, and Li as raw materials, respectively, and wherein the heat-treated material is heat-treated together with the black mass in a state where the total amount of the multiple metal salts is 20 to 5,000 parts by weight per 100 parts by weight of the black mass.

13. The electrode active material according to claim 12, characterized in that the crystalline structure is a layered rock salt type.

14. An electrode active material according to claim 12 or 13, characterized in that the black mass contains at least Ni, Mn, Co, Li, and C, and when the content of the C component is less than 7.5% in terms of mass ratio, the heat-treated product is heat-treated together with the black mass in a state where the total amount of the metal salts is 20 to 350 parts by weight per 100 parts by weight of the black mass.

15. An electrode active material according to claim 12 or 13, characterized in that the black mass contains at least Ni, Mn, Co, Li, and C, and when the content of the C component exceeds 25% in terms of mass ratio, the heat-treated product is heat-treated in a state in which the total amount of the metal salts is contained in an amount of 700 to 5,000 parts by weight per 100 parts by weight of the black mass.

16. The electrode active material according to claim 15, wherein the heat-treated product is heat-treated in a state in which the total amount of the metal salts is 3,500 to 5,000 parts by weight per 100 parts by weight of the black mass.

17. A lithium ion battery having a positive electrode, a negative electrode, and an electrolyte, which is repeatedly charged and discharged by a battery electrode reaction using lithium ions as a charge carrier, wherein the positive electrode active material that forms the main part of the positive electrode is formed from the electrode active material described in claim 12 or claim 13.

18. The lithium ion battery according to claim 17, wherein the main negative electrode active material of the negative electrode is formed of one material selected from the group consisting of lithium metal, lithium titanate, carbonaceous materials, and silicon oxide-based materials.

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