Method for producing electrode active material, electrode active material, method for producing lithium-ion battery, and lithium-ion battery

Abstract

According to the present invention, a used lithium-ion battery in which a ternary material is used as a positive electrode active material is prepared, the used lithium-ion battery is sufficiently discharged and deactivated (S1) and is disassembled (S2), and a waste positive electrode material and a waste separator are separated and the waste positive electrode material is taken out (S3). Then, the waste positive electrode material 23 is crushed and pulverized to produce a powder material and the powder material is used as a recycled material (S4). Thereafter, a plurality of metal salts containing a ternary material and Li are prepared (S5), the waste positive electrode material and the metal salts are mixed such that a total content of the metal salts with respect to 100 parts by weight of the recycled material is 35-3,500 parts by weight (S6), and heat treatment is performed at a predetermined heat treatment temperature for a predetermined time (S7) to obtain a positive electrode active material. As a result, resources are effectively used by reusing the powder material of the used lithium-ion battery, and an electrode active material and a lithium-ion battery having desired good battery characteristics and high practicality are obtained.

Description

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

[0001] The present invention relates to a method for producing an electrode active material, an electrode active material, a method for producing a lithium-ion battery, and a lithium-ion battery. More specifically, it relates to a method for producing an electrode active material by reusing a used lithium-ion battery, an electrode active material produced by this method, and a method for producing a lithium-ion battery using this electrode active material as a positive electrode active material, and a lithium-ion battery.

[0002] With the expansion of the market for portable electronic devices such as mobile phones, laptops, and tablet devices, the development of rechargeable batteries as cordless power sources for these devices is thriving. Furthermore, against the backdrop of global warming and the depletion of petroleum resources, the development of electric vehicles and hybrid vehicles powered by rechargeable batteries is also progressing rapidly.

[0003] Under these circumstances, secondary batteries are being developed that utilize alkali metal ions such as lithium ions as charge carriers and employ electrochemical reactions associated with charge transfer. In particular, lithium-ion batteries, which have a high energy density, are now widely used.

[0004] Among the components of a lithium-ion battery, the electrode active material is a substance that directly contributes to the battery electrode reactions, namely the charging and discharging reactions. Since charging and discharging are performed by utilizing the insertion and removal reactions of lithium ions into the electrode active material, it plays a central role in the lithium-ion battery.

[0005] In this type of lithium-ion battery, in the early stages of development, the electrode active material, especially the positive electrode active material, was LiCoO ２ Lithium cobalt oxide was previously used, but due to the high cost of Co and the demand for higher capacity and lower costs associated with the expansion of battery applications such as those in automobiles, ternary materials in which some of the Co is replaced with Ni or Mn have attracted attention in recent years, and lithium-ion batteries using these ternary materials as cathode active materials are being actively researched and developed.

[0006] However, while 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, technologies have been proposed to recover lithium-ion battery materials from a black powder called "black mass," which is produced by processing used lithium-ion batteries, and to recycle them. For example, Patent Document 1 discloses a method for extracting metals from the aforementioned black mass.

[0008] Specifically, in Patent Document 1, first, 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, thereby recovering the main fraction containing at least one of Mn, Co, Ni, and Li.

[0009] Thus, in Patent Document 1, 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.

[0010] Furthermore, a technology has been proposed that involves extracting only the electrode material from used lithium-ion batteries and reusing this electrode material to obtain regenerated lithium-ion batteries.

[0011] For example, Patent Document 2 proposes a method for producing a recycled cathode material precursor comprising a metal element α consisting of at least one of Ni, Co, and Mn, and a metal element β consisting of at least one of Fe, Cu, and Al, the method comprising a heat treatment step of heating a lithium-ion secondary battery, which is the object to be treated, to obtain a heat-treated product; a crushing step of crushing the heat-treated product to obtain crushed material; and a physical sorting step of performing physical sorting on the crushed material to obtain a physically treated product, in which the metal element α is concentrated in the physically treated product, wherein the content of the metal element β in the recycled cathode material precursor is 0.5 to 20% by mass.

[0012] In this Patent Document 2, a recycled cathode material precursor manufactured as described above is mixed with a predetermined amount of Li source to obtain a mixed powder, which is then calcined to produce a recycled cathode material, and a recycled lithium-ion battery is obtained using this recycled cathode material.

[0013] In other words, Patent Document 2 describes a method in which used lithium-ion batteries are heat-treated along with their cells to electrically and chemically detoxify the laminate that forms the battery body within each cell. The positive electrode active material is then mechanically and magnetically recovered from this laminate through processes such as crushing and physical sorting (classification and magnetic separation), thereby extracting the positive electrode active material from the laminate and using this positive electrode active material to obtain a regenerated lithium-ion battery.

[0014] Furthermore, Patent Document 3 proposes a method for regenerating electrodes of a lithium-ion battery, which includes the steps of treating at least one of the positive and negative electrodes of a used lithium-ion battery with a polar solvent, drying the solvent-treated electrode, and re-injecting electrolyte into the battery having the dried electrode.

[0015] This Patent Document 3 describes a method for regenerating electrodes (particularly active material particles) by treating deposits such as SEI (solid electrolyte interface) present on the electrode surface with a polar solvent. This method avoids damaging the electrodes and the use of strong acids and alkalis, thereby avoiding the generation of solid waste and providing an inexpensive, environmentally friendly recycled lithium-ion battery.

[0016] Japanese Patent Publication No. 2024-516955 (Claim 1, paragraphs

[0063] to

[0066] , Figures 2a, 2b, etc.), Japanese Unexamined Patent Publication No. 2023-4914 (Claim 12, paragraphs

[0041] to

[0043] ,

[0059] to

[0094] , Figure 1, etc.), Japanese Unexamined Patent Publication No. 2012-22969 (Claim 1, paragraphs

[0009] ,

[0011] , etc.)

[0017] However, the aforementioned Patent Document 1 involves a complicated processing step for extracting, separating, and recycling battery materials from black mass, and the equipment required is expensive, resulting in high recycling costs and poor practicality. Furthermore, if the black mass itself is reused to obtain electrode active material, such as positive electrode active material, the black mass contains electrolytes, components of the counter electrode, and impurities derived from the electrolyte. Therefore, a considerable amount of impurities are inevitably mixed into the recycled electrode active material, and it is considered that there are limitations to obtaining stable and good battery characteristics.

[0018] Furthermore, while Patent Document 2 describes the regeneration of positive electrode material precursors from used lithium-ion batteries and the use of these regenerated positive electrode material precursors to obtain lithium-ion batteries, the used lithium-ion batteries are heat-treated as a whole in the preceding process, and the regenerated positive electrode material precursors are obtained through further classification and magnetic separation processes. Therefore, similar to Patent Document 1, the manufacturing process is complicated and the recycling costs are high.

[0019] Furthermore, Patent Document 3 attempts to obtain a regenerated battery by regenerating and reusing the electrodes of a used lithium-ion battery while maintaining the shape of the coated electrodes, and does not address the degradation of the electrode active material itself.

[0020] This invention has been made in view of these circumstances, and aims to provide a method for producing an electrode active material that can effectively utilize resources by reusing powdered material from used lithium-ion batteries and obtain a highly practical electrode active material with desired good battery characteristics, an electrode active material produced by this method, a method for producing a lithium-ion battery using this electrode active material as a positive electrode active material, and a lithium-ion battery.

[0021] As mentioned above, black mass is obtained by crushing or otherwise turning the entire used lithium-ion battery into a black powder. Therefore, when reusing this black mass to produce electrode active material, such as positive electrode active material, the black mass contains impurities originating from the electrolyte and the constituent materials of the negative electrode, which is the counter electrode. As a result, in order to obtain stable and good battery characteristics, it may be necessary to increase the amount of metal salts containing Li or ternary materials (Ni, Mn, Co).

[0022] In contrast, if used lithium-ion batteries can be disassembled to extract only the electrode material (e.g., positive electrode material), and this electrode material, i.e., waste electrode material, can be crushed into a black powder and reused, then the contamination of the waste electrode material with impurities originating from the electrolyte and counter electrode (e.g., negative electrode) can be substantially avoided. As a result, even with a reduced amount of Li and metal salts added to ternary materials, stable and good battery characteristics can be obtained, enabling more effective use of resources and contributing to a further improvement in recycling efficiency.

[0023] Therefore, the inventors disassembled used lithium-ion batteries containing the above-mentioned ternary material, extracted the electrode material, and conducted intensive research. They found that by crushing any of the used waste electrode material, the waste electrode active material layer, or the metal granules mainly composed of Li or the ternary material in the waste electrode active material layer to obtain a powder, and by mixing this recycled material with a predetermined amount of metal salt containing Li and the above-mentioned ternary material and subjecting it to heat treatment, an electrode active material with good battery characteristics that have a good capacity recovery rate and are highly practical can be obtained.

[0024] The present invention is based on such findings, and the method for producing an electrode active material according to the present invention is a method for producing an electrode active material by reusing waste electrode material obtained by disassembling a used lithium-ion battery, wherein the waste electrode material comprises a waste electrode active material layer in which metal granules containing at least Ni, Mn, Co, and Li components are mixed with a coating agent, and a waste electrode current collector bonded to the waste electrode active material layer, and the recycled material is a powder obtained by crushing any of the waste electrode material, the waste electrode active material layer, and the metal granules, and the recycled material and the metal salts are mixed and heat treated so that the total amount of multiple metal salts containing Ni, Mn, Co, and Li components is 35 to 3500 parts by weight per 100 parts by weight of the recycled material, and the recycled material and the metal salts react to produce an electrode active material.

[0025] Here, "metal granules" include not only the individual metal components of the ternary material Ni, Mn, Co, and Li, as well as metal compounds containing these components, but also some impurities that inevitably become mixed in even after centrifugal separation treatment of the waste electrode active material.

[0026] Furthermore, in the method for producing the electrode active material of the present invention, it is preferable to mix the recycled material and the metal salts so that the total amount of the plurality of metal salts is 350 to 3500 parts by weight per 100 parts by weight of the recycled material, and then subject the mixture to heat treatment.

[0027] This makes it possible to obtain electrode active materials with better battery characteristics while ensuring recycling efficiency.

[0028] Furthermore, the present invention's method for producing an electrode active material is characterized by impregnating the waste electrode material with a solvent of the same type as the solvent contained in the coating agent and heating it to separate the waste electrode active material layer from the waste electrode current collector, and using the waste electrode active material layer as a recycled material.

[0029] In this case, since the recycled material does not contain the waste electrode current collector, it is possible to obtain an electrode active material with even better battery characteristics. Furthermore, as described above, since the waste electrode material is impregnated in a solvent and heated to separate the waste electrode active material layer from the waste electrode current collector, it is possible to effectively suppress the separation of metal components in the waste electrode active material layer without causing mechanical damage.

[0030] Furthermore, in the method for producing the electrode active material of the present invention, it is preferable that the coating agent includes an aqueous coating agent, in which case an aqueous coating agent containing carboxymethylcellulose (hereinafter referred to as "CMC") and styrene-butadiene copolymer (hereinafter referred to as "SBR") can be preferably used.

[0031] Furthermore, in the method for producing the electrode active material of the present invention, it is also preferable that the coating agent includes a solvent-based coating agent. In this case, polyvinylidene fluoride (hereinafter referred to as "PVDF") can be preferably used as a binder, and N-methyl-2-pyrrolidone (hereinafter referred to as "NMP") can be preferably used as a solvent.

[0032] Furthermore, the present invention's method for producing electrode active material is characterized in that, after separating the waste electrode material into the waste electrode active material layer and the waste electrode current collector, the waste electrode active material layer is subjected to centrifugal separation to recover the metal granules, and the recycled material mainly consists of the metal granules.

[0033] In this case, since the recycled material does not contain impurities such as binders and conductive additives contained in the coating agent, it becomes possible to obtain an electrode active material with better battery characteristics.

[0034] Furthermore, in the method for producing the electrode active material of the present invention, it is preferable to dissolve each metal powder containing each component that forms the metal salt in a solvent to prepare a mixed solution, then process the mixed solution to produce a precipitate, obtain the metal salt from the precipitate, and mix the recycled material with the metal salt.

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

[0036] Further, in the method for producing an electrode active material of the present invention, it is preferable to perform the heat treatment at a temperature of 650 to 1100°C for 0.5 to 12 hours.

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

[0038] Further, in the method for producing an electrode active material of the present invention, when the plurality of metal salts are synthesized by mixing these plurality of metal salts, for example, the composition formula is LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O ２ (hereinafter, also referred to as "NMC111"), and the general formula LiNi ｘ Mn ｙ Co ｚ O ２ (where x>0, y>0, z>0, x + y + z = 1), and the general formula Li(Li ｐ Ni ｑ Mn ｒ Co ｓ )O ２ (where p>0, q>0, r>0, s>0, p + q + r + s = 1), it is preferable to adjust the blending ratio so that any of the metal oxides represented by can be formed and mix it with the recycled material.

[0039] Further, as a result of the inventors' intensive research, even when only a predetermined amount of Li salt is added without adding a plurality of metal salts containing the above ternary system material, it is possible to obtain excellent battery characteristics with high practicality. Thus, it has been found that an electrode active material that can contribute to the effective utilization of resources at a lower cost without adding rare metals such as expensive Co, Ni, and Mn can be produced.

[0040] In other words, the method for producing an electrode active material according to the present invention is a method for producing an electrode active material by reusing waste electrode material obtained by disassembling a used lithium-ion battery, wherein the waste electrode material comprises a waste electrode active material layer in which the above-mentioned metal granules and coating agent are mixed, and a waste electrode current collector bonded to the waste electrode active material layer, and the recycled material is a powder obtained by crushing any of the waste electrode material, the waste electrode active material layer, and the metal granules, and the recycled material and the metal salt are mixed and heat treated so that the amount of metal salt containing Li component is 4.8 to 480 parts by weight per 100 parts by weight of the recycled material, and the recycled material and the metal salt are reacted to produce an electrode active material.

[0041] Furthermore, in the method for producing the electrode active material of the present invention, it is preferable to mix the recycled material and the metal salt so that the amount of the metal salt is 24 to 480 parts by weight per 100 parts by weight of the recycled material, and then subject the mixture to heat treatment.

[0042] This makes it possible to obtain an electrode active material with good battery characteristics while ensuring a better recycling effect by adding only Li salt to the recycled material.

[0043] Furthermore, the present invention provides a method for producing an electrode active material, characterized by impregnating the waste electrode material with a solvent contained in a coating agent and heating it to separate the waste electrode active material layer from the waste electrode current collector, and using the waste electrode active material layer as the recycled material.

[0044] Even when only Li salts are added in this way, by using the waste electrode active material layer as a recycled material, a highly practical electrode active material with good battery characteristics can be obtained.

[0045] Furthermore, in the method for producing the electrode active material of the present invention, it is preferable to dissolve a metal powder containing a Li component in a solvent to prepare a Li-containing solution, then process the Li-containing solution to produce a precipitate, obtain the metal salt from the precipitate, and mix the recycled material with the metal salt.

[0046] Furthermore, in the method for producing the electrode active material of the present invention, it is preferable to perform the heat treatment at a temperature of 650 to 1100°C for 0.5 to 12 hours.

[0047] Furthermore, the electrode active material according to the present invention is an electrode active material formed by reusing waste electrode material obtained by disassembling a used lithium-ion battery, wherein the waste electrode material has a waste electrode active material layer in which the above-mentioned metal granules and coating agent are mixed, and a waste electrode current collector bonded to the waste electrode active material layer, and the recycled material is formed from powder obtained by crushing any of the waste electrode material, the waste electrode active material layer, and the metal granules, and the total amount of multiple metal salts containing Ni, Mn, Co, and Li is 35 to 3500 parts by weight per 100 parts by weight of the recycled material.

[0048] Furthermore, it is preferable that the electrode active material of the present invention contains a total of 350 to 3500 parts by weight of the plurality of metal salts per 100 parts by weight of the recycled material.

[0049] Furthermore, the electrode active material according to the present invention is an electrode active material formed by reusing waste electrode material obtained by disassembling a used lithium-ion battery, wherein the waste electrode material has a waste electrode active material layer in which the above-mentioned metal granules and coating agent are mixed, and a waste electrode current collector bonded to the waste electrode active material layer, and the recycled material is formed from powder obtained by crushing any of the waste electrode material, the waste electrode active material layer, and the metal granules, and is characterized in that a metal salt containing Li is contained in an amount of 4.8 to 480 parts by weight per 100 parts by weight of the recycled material.

[0050] Furthermore, the electrode active material of the present invention preferably contains 24 to 480 parts by weight of the metal salt per 100 parts by weight of the recycled material.

[0051] Furthermore, the present invention relates to a method for manufacturing a lithium-ion battery, which has 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, characterized in that the positive electrode active material, which is the main component of the positive electrode, is formed from the electrode active material manufactured by the above manufacturing method, and the method includes a step of manufacturing the positive electrode using an aqueous or solvent-based coating agent.

[0052] This makes it possible to manufacture lithium-ion batteries with good battery characteristics at low cost, regardless of the type of coating agent used.

[0053] Furthermore, 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 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, which is the main component of the positive electrode, is formed of the above-mentioned electrode active material.

[0054] Since the positive electrode active material is formed from the electrode active material described above, it becomes possible to obtain a novel and useful lithium-ion battery that promotes the effective utilization of resources by using used lithium-ion batteries.

[0055] 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 one selected from the group consisting of lithium metal, lithium titanate, carbon-based materials, and silicon oxide-based materials.

[0056] Furthermore, although the present invention contains 25 claims, these inventions have the same or corresponding special technical features and are related in a way that forms a single general inventive concept, thus satisfying the requirement of unity of invention.

[0057] According to the method for producing electrode active materials and the electrode active material of the present invention, the waste electrode material comprises a waste electrode active material layer in which the above-mentioned metal granules and coating agent are mixed, and a waste electrode current collector bonded to the waste electrode active material layer. The recycled material is made from pulverized material obtained by crushing any of the waste electrode material, the waste electrode active material layer, and the metal granules. The recycled material and the metal salts are mixed and heat-treated so that the total amount of multiple metal salts containing Ni, Mn, Co, and Li components is 35 to 3500 parts by weight, preferably 350 to 3500 parts by weight, per 100 parts by weight of the recycled material, and the recycled material and the metal salts are reacted to produce an electrode active material. Therefore, compared to the case in which black mass is used directly, impurities originating from the electrolyte and the constituent materials of the counter electrode are not mixed in, and an electrode active material with excellent battery characteristics and high practicality can be obtained.

[0058] Furthermore, it is also possible to produce an electrode active material by mixing the recycled material and the metal salt containing Li in an amount of 4.8 to 480 parts by weight, preferably 24 to 480 parts by weight, with respect to 100 parts by weight of the recycled material, and then heat-treating the mixture to react the recycled material and the metal salt. In this case, good battery characteristics can be obtained by adding only the Li salt without adding multiple metal salts containing ternary materials, thereby eliminating the need to add expensive rare metals such as Co, Ni, and Mn, and making it possible to obtain an electrode active material with good battery characteristics at a lower cost.

[0059] Furthermore, by impregnating the waste electrode material with a solvent of the same type as the solvent contained in the coating agent and heating it, separating the waste electrode active material layer from the waste electrode current collector, and using the waste electrode active material layer as recycled material, it becomes possible to obtain an electrode active material with even better battery characteristics because the recycled material does not contain the waste electrode current collector. In addition, since the waste electrode material is impregnated with a solvent and heated to separate the waste electrode active material layer from the waste electrode current collector, mechanical damage does not occur, and the separation of metal components in the waste electrode active material layer from the waste electrode active material layer can be effectively suppressed.

[0060] Furthermore, if the waste electrode material is separated into the waste electrode active material layer and the waste electrode current collector, and then the waste electrode active material layer is subjected to centrifugal separation to recover the metal granules, and these metal granules are used as the main component of the recycled material, it is possible to avoid the inclusion of impurities such as coating agents and conductive additives, thereby obtaining an electrode active material with even better battery characteristics.

[0061] Furthermore, by dissolving each metal powder containing the components that form the metal salt in a solvent to prepare a mixed solution, processing the mixed solution to produce a precipitate, and obtaining the metal salt from the precipitate, and then mixing the recycled material with the metal salt, it becomes possible to obtain a highly refined, high-quality metal salt, thereby enabling the production of a high-quality electrode active material.

[0062] Furthermore, by performing the heat treatment at a temperature of 650 to 1100°C for 0.5 to 12 hours, the heat treatment temperature and time can be appropriately adjusted, making it possible to easily produce electrode active materials with desired battery performance.

[0063] According to the lithium-ion battery manufacturing method and lithium-ion battery of the present invention, it is possible to obtain a novel and useful lithium-ion battery that promotes the effective utilization of resources by utilizing used lithium-ion batteries, regardless of the type of coating agent.

[0064] Furthermore, in the lithium-ion battery of the present invention, since the negative electrode active material, which is the main component of the negative electrode, is made of one selected from the group consisting of lithium metal, lithium titanate, carbon-based materials, and silicon oxide-based materials, it is possible to obtain a lithium-ion battery with desired battery characteristics.

[0065] This is a schematic cross-sectional view showing one embodiment of the lithium-ion battery according to the present invention. This is an enlarged cross-sectional view of part A in Figure 1. This is a manufacturing process diagram showing a first embodiment of the method for manufacturing a positive electrode active material as an electrode active material according to the present invention. This is a schematic cross-sectional perspective view showing the state of removing waste positive electrode material from a used lithium-ion battery. This is a manufacturing process diagram showing a second embodiment of the method for manufacturing a positive electrode active material as an electrode active material according to the present invention. This is a manufacturing process diagram showing a third embodiment of the method for manufacturing a positive electrode active material as an electrode active material according to the present invention. This is a manufacturing process diagram showing a fourth embodiment of the method for manufacturing a positive electrode active material as an electrode active material according to the present invention.

[0066] Next, embodiments of the present invention will be described in detail with reference to the drawings.

[0067] Figure 1 is a schematic cross-sectional view showing a lithium-ion battery (cylindrical type) according to the present invention, in which the positive electrode active material is formed of the electrode active material. Figure 2 is an enlarged cross-sectional view of part A in Figure 1.

[0068] As shown in Figure 1, this lithium-ion battery has a convex positive electrode terminal 1 made of Al or the like, and a bottomed cylindrical negative electrode case 2 made of Cu or the like that also serves as the negative electrode terminal. The negative electrode case 2 houses multiple sets of battery body parts 6, each consisting of a positive electrode 3, a separator 4, and a negative electrode 5, in a stacked arrangement. 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, 9 and a gasket 10.

[0069] As shown in Figure 2, the positive electrode 3 has positive electrode active material layers 13a and 13b, mainly composed of ternary metal oxides such as NMC111, 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 composed of lithium metal or carbon-based materials, formed on both main surfaces of a negative electrode current collector 14 made of Cu foil or the like. The separator 4 is made 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 these battery body parts 6 is filled with electrolyte 11.

[0070] The following describes in detail the manufacturing method of the positive electrode active material, which is the main component of the positive electrode active material 13, and then explains the manufacturing method of the lithium-ion battery described above.

[0071] (First Embodiment) This positive electrode active material is manufactured by reusing waste positive electrode material (used positive electrode material) obtained by disassembling used lithium-ion batteries.

[0072] This waste positive electrode material comprises a waste positive electrode active material layer (used positive electrode active material layer) which is a mixture of metal granules mainly composed of Ni, Mn, Co, and Li and a coating agent, and a waste positive electrode current collector (used positive electrode current collector) which is bonded to the waste positive electrode active material layer.

[0073] In this first embodiment, waste cathode material is used as recycled material, and the waste cathode material and metal salts are mixed and heat-treated so that the total content of multiple metal salts containing ternary materials (Ni, Mn, Co) and Li components is 35 to 3500 parts by weight per 100 parts by weight of the recycled material, and the waste cathode material and metal salts are reacted to produce a cathode active material.

[0074] Thus, in this first embodiment, since waste positive electrode material is used as recycled material and black mass obtained by crushing used lithium-ion batteries along with the cells is not used, impurities originating from used electrolytes, separators, and counter electrodes (negative electrodes) do not get mixed into the positive electrode active material, making it possible to obtain good battery characteristics.

[0075] The reason for setting the total metal salt content to 35 to 3500 parts by weight per 100 parts by weight of recycled material is as follows:

[0076] If the total amount of metal salts is less than 35 parts by weight per 100 parts by weight of recycled material, the total amount of metal salts will be insufficient, and it will not be possible to secure a sufficient capacity density compared to lithium-ion batteries manufactured by conventional methods, and the battery capacity will not be fully restored. On the other hand, if the total amount of metal salts exceeds 3,500 parts by weight per 100 parts by weight of recycled material, the total amount of metal salts containing rare metals will be high, leading to increased costs and potentially making it impossible to adequately utilize the reuse of valuable resources.

[0077] Therefore, in this first embodiment, the total content of metal salts is set to 35 to 3500 parts by weight per 100 parts by weight of recycled material. Furthermore, from the viewpoint of further restoring capacity density and ensuring good battery characteristics, 350 to 3500 parts by weight per 100 parts by weight of recycled material is preferable.

[0078] Figure 3 is a manufacturing process diagram showing a first embodiment of the method for producing a positive electrode active material as an electrode active material according to the present invention.

[0079] First, a used lithium-ion battery using a ternary material as the positive electrode active material is prepared. Then, in step S1, this used lithium-ion battery is fully discharged to deactivate it, in step S2, the used lithium-ion battery is disassembled, and in step S3, the waste positive electrode material and waste separator are separated, and the waste positive electrode material is extracted from the lithium-ion battery. Figure 4 is a schematic cross-sectional perspective view showing the state of extracting the positive electrode material and other components from a used lithium-ion battery.

[0080] The negative electrode case 22 of the used lithium-ion battery lithium 21 contains multiple sets of battery body parts 26, each set consisting of a waste positive electrode material 23, a waste separator 24, and a waste negative electrode material 25, arranged in a stacked manner. The waste positive electrode material 23, waste separator 24, and waste negative electrode material 25 are then removed from this used lithium-ion battery. A cutting tool such as a cutter is then inserted between the waste positive electrode material 23 and the waste separator 24 to separate them.

[0081] Next, in step S4 (Figure 3), the waste cathode material 23 is crushed and pulverized using a pulverizer to obtain a powder material that is blackened to a size of approximately 20 to 100 μm.

[0082] Next, in step S5, metal salts are prepared. Specifically, first, metal powders containing Li, Ni, Mn, and Co are prepared. Here, the type of metal powder is not particularly limited, and various metal salts such as acetate compounds, nitrate compounds, carbonate compounds, and chlorides can be used. Then, these metal powders are weighed out so that, for example, Li, Ni, Mn, and Co are in molar ratios of Li:Ni,Mn,Co = 1:1 / 3:1 / 3:1 / 3, and these weighed materials are dissolved in a large amount of solvent such as pure water to prepare a mixed solution. Meanwhile, a precipitating agent such as citric acid is dissolved in a large amount of solvent such as pure water to prepare a precipitating agent solution.

[0083] Then, the mixed solution and the precipitating agent solution are mixed to produce a precipitate, the precipitate is filtered to remove the supernatant, the obtained precipitate is thoroughly washed and dried to obtain a metal salt.

[0084] Next, in step S6, the waste cathode material and the metal salt are mixed so that the total content of the metal salt is 35 to 3500 parts by weight, preferably 350 to 3500 parts by weight, per 100 parts by weight of the waste cathode material to obtain a mixture.

[0085] Then, in step S7, the mixture is heat-treated at a predetermined heat treatment temperature for a predetermined time, and then allowed to cool naturally until it reaches room temperature, thereby producing the above-mentioned positive electrode active material using recycled waste positive electrode material.

[0086] While the heat treatment temperature is not particularly limited, it is generally preferable to perform it in the range of 650°C to 1100°C. At temperatures below 650°C, sufficient crystallization may not occur, making it difficult to obtain the desired capacity density. On the other hand, at temperatures exceeding 1100°C, crystallization may proceed excessively, inhibiting the movement of Li ions and potentially leading to a deterioration of the cycle characteristics.

[0087] Furthermore, while there are no particular limitations on the heat treatment time, it is preferable to carry it out for approximately 0.5 to 12 hours. If the heat treatment time is too short (less than 0.5 hours), sufficient crystallization may not occur, making it difficult to obtain the desired capacity density. On the other hand, if the heat treatment time exceeds 12 hours, crystallization may proceed excessively, inhibiting the movement of Li ions and potentially leading to a deterioration of the cycle characteristics.

[0088] In this first embodiment, waste cathode material is used as recycled material, and the recycled material (waste cathode material) and multiple metal salts containing each component of a ternary material (Ni, Mn, Co) and Li are mixed and heat-treated so that the total content of each metal salt is 35 to 3500 parts by weight, preferably 350 to 3500 parts by weight, per 100 parts by weight of the recycled material (waste cathode material). The recycled material and metal salts are reacted to produce a positive electrode active material. Compared to the case where black mass is used directly, impurities originating from the electrolyte and counter electrode components are not mixed in, and a positive electrode active material with excellent battery characteristics and high practicality can be obtained. The lithium-ion battery can then be manufactured using the above positive electrode active material as follows.

[0089] First, the positive electrode active material is mixed with a conductive additive and a binder, and a solvent is added to form a slurry to obtain a coating agent. Then, this coating agent is applied to both main surfaces of the positive electrode current collector 12 using any coating method and dried to form positive electrode active material layers 13a and 13b on both main surfaces of the positive electrode current collector 12, thereby obtaining the positive electrode 3.

[0090] 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.

[0091] Furthermore, the binder is not particularly limited; for water-based coatings, CMC / SBR and polyethylene oxide can be used, and for solvent-based coatings, fluororesins such as PVDF, polyhexafluoropropylene, and polytetrafluoroethylene can be used.

[0092] Furthermore, the solvent is not particularly limited, and for example, basic solvents such as pure water, NMP, dimethyl sulfoxide, dimethylformamide, propylene carbonate, diethyl carbonate, dimethyl carbonate, and γ-butyrolactone, non-aqueous solvents such as acetonitrile, tetrahydrofuran, nitrobenzene, and acetone, and protic solvents such as methanol and ethanol can be used.

[0093] 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.

[0094] Next, negative electrode active material layers 15a and 15b are formed on both main surfaces of the negative electrode current collector 14 to obtain the negative electrode 5. The negative electrode 5 is impregnated with the electrolyte 11 to allow the electrolyte 11 to permeate the negative electrode 5, and the positive electrode 3 is also impregnated with the electrolyte 11. Furthermore, a separator 4 impregnated with the electrolyte 11 is interposed between the positive electrode 3 and the negative electrode 5. Multiple sets of battery body parts 6, each consisting of the positive electrode 3, separator 4, and negative electrode 5, are stacked and housed in the negative electrode case 2, and then the electrolyte 11 is injected into the internal space. Finally, a gasket 10 is placed around the periphery, and the negative electrode case 2 and the positive electrode terminal 1 are fixed together using a crimping machine or the like to seal the exterior, thereby manufacturing a lithium-ion battery.

[0095] Furthermore, the electrolyte 11 is interposed between the positive electrode 3 and its opposing electrode, the negative electrode 5, to transport charge carriers between the two electrodes. As such an electrolyte 11, 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 ionic liquid such as 1-ethyl-3-methylimidazolium tetrafluoroborate in an electrolyte salt can be used.

[0096] Here, the electrolyte salt is, for example, LiPF ６ LiClO４ 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 PO ４ , LiCl, (CH ３ CO) ２ Various lithium salts, such as Li, can be used.

[0097] Furthermore, as organic solvents, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, dimethoxyethane, and mixtures thereof can be used.

[0098] Furthermore, a solid electrolyte may be used as the electrolyte. Both inorganic and polymeric solid electrolytes can be used. For example, 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 sulfide-based solid electrolytes include polypyridene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-ethylene copolymer, and various other copolymers.

[0099] Thus, this lithium-ion battery has a positive electrode 3, a negative electrode 5, and an electrolyte 11, and is a lithium-ion battery that repeatedly charges and discharges through 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 3, is formed from an electrode active material manufactured by the above-described manufacturing method, it contributes to the recycling of waste positive electrode material from used lithium-ion batteries, and makes it possible to easily obtain a lithium-ion battery with good battery characteristics at low cost.

[0100] (Second Embodiment) In the first embodiment described above, waste cathode material was used as the recycled material. In this second embodiment, the waste cathode current collector is peeled off from the waste cathode material to separate it into a waste cathode active material layer and a waste cathode current collector. The waste cathode active material layer is used as the recycled material, thereby minimizing the inclusion of impurities originating from the waste cathode current collector and obtaining an electrode active material with better battery characteristics. Figure 5 is a manufacturing process diagram showing the second embodiment of the cathode active material according to the present invention.

[0101] That is, similar to the first embodiment, after the used lithium-ion battery is sufficiently discharged and deactivated, the lithium-ion battery is disassembled, the waste positive electrode material 23 and the waste separator 24 are separated, and the waste positive electrode material 23 is removed (steps S11 to S13).

[0102] Furthermore, since the waste positive electrode material 23 has a coating agent applied to both main surfaces of the waste positive electrode current collector, and the waste positive electrode current collector and the waste positive electrode active material layer are joined together, in step S14 the waste positive electrode current collector is peeled off from the waste positive electrode active material layer, separating the waste positive electrode active material layer from the waste positive electrode current collector, and obtaining the waste positive electrode active material layer.

[0103] Specifically, the waste positive electrode active material layer can be separated from the waste positive electrode current collector by impregnating it with a solvent of the same type as the solvent contained in the coating agent—for example, pure water if the coating agent is water-based—and heating it to about 80°C. Alternatively, if the coating agent is solvent-based, the waste positive electrode active material layer can be separated from the waste positive electrode current collector by impregnating it with the solvent and heating it to about 130°C.

[0104] After thoroughly drying the waste positive electrode active material layer obtained in this manner, in the following step S15, the waste positive electrode active material layer is crushed, the waste positive electrode active material layer is turned into a black powder, and a powder is obtained.

[0105] Then, in step S16, similar to the first embodiment, a ternary material and a plurality of metal salts containing Li salt are prepared, and then in step S17, the waste cathode active material layer and the metal salts are mixed so that the total content of the metal salts is 35 to 3500 parts by weight, preferably 350 to 3500 parts by weight, per 100 parts by weight of the waste cathode active material layer, and in the following step S18, similar to the first embodiment, the mixture is subjected to a predetermined heat treatment, thereby enabling the production of a cathode active material using the waste cathode active material layer as a recycled material.

[0106] Furthermore, a regenerated lithium-ion battery can be obtained using the same method and procedure as in the first embodiment described above.

[0107] Thus, in this second embodiment, the waste positive electrode active material layer is used as a recycled material, and therefore, no substances derived from the waste positive electrode current collector (for example, aluminum, etc.) are mixed into the recycled material, making it possible to obtain a positive electrode active material and a lithium-ion battery using the same that have even better battery characteristics.

[0108] (Third Embodiment) In the second embodiment described above, powdered waste positive electrode active material was used as the recycled material. However, since the powdered waste positive electrode active material contains binders and conductive additives derived from the coating agent as impurities, in this third embodiment, powdered metal granules obtained by removing such impurities as much as possible are used as the recycled material.

[0109] Figure 6 is a manufacturing process diagram showing a third embodiment of the positive electrode active material according to the present invention.

[0110] That is, similar to the second embodiment, after the used lithium-ion battery is sufficiently discharged and deactivated, the lithium-ion battery is disassembled, the waste positive electrode material 23 and waste separator 24 are separated, the waste positive electrode material 23 is removed, and then the waste positive electrode current collector and waste positive electrode active material layer are separated, and the waste positive electrode active material layer is crushed and turned into black powder to obtain a powder (steps S21 to S25).

[0111] Then, in step S26, a centrifugal separation process is performed. Specifically, the rotation speed is set to 5000 to 8000 rpm and centrifugal separation is performed for about 15 to 25 minutes, after which the supernatant liquid is discarded. This process is repeated several times to recover metal granules that have been thoroughly dried and from which conductive additives, binders, and other components have been removed as much as possible.

[0112] In the following step S27, similar to the first embodiment, a ternary material and a plurality of metal salts containing Li salt are prepared. Then, in step S28, the metal granules and metal salts are mixed so that the total content of metal salts is 35 to 3500 parts by weight, preferably 350 to 3500 parts by weight, per 100 parts by weight of metal granules. In the following step S29, similar to the first embodiment, the mixture is subjected to a predetermined heat treatment, thereby enabling the production of a positive electrode active material using recycled metal powder granules.

[0113] Furthermore, a regenerated lithium-ion battery can be obtained using the same method and procedure as in the first embodiment described above.

[0114] In this third embodiment, the recycled material is a powdered metal granule from which components such as conductive additives and binders have been removed as much as possible. Therefore, it is possible to avoid as much as possible the contamination of the recycled material with conductive additives and binders derived from coatings, and thus obtain a positive electrode active material and a lithium-ion battery using the same that have even better battery characteristics.

[0115] (Fourth Embodiment) In the first to third embodiments described above, a ternary material and multiple metal salts containing Li are added to the recycled material to produce a positive electrode active material. However, in this fourth embodiment, only Li salt is added to the waste positive electrode active material layer as recycled material, thereby obtaining an electrode active material with good battery characteristics without separately adding rare metals such as Ni, Co, and Mn. Figure 7 is a manufacturing process diagram showing the fourth embodiment of the positive electrode active material according to the present invention.

[0116] That is, similar to the second embodiment, after the used lithium-ion battery is sufficiently discharged and deactivated, the lithium-ion battery is disassembled, the waste positive electrode material 23 and waste separator 24 are separated, the waste positive electrode material 23 is taken out, and the waste positive electrode material is further separated into a waste positive electrode current collector and a waste positive electrode active material layer, and then the waste positive electrode active material layer is crushed and turned into a black powder to obtain a powder (steps S31 to S35).

[0117] Then, in step S36, the powdered material of the positive electrode active material layer is reused, and Li-containing metal powder, i.e., Li salt, is added to the waste positive electrode active material layer in an amount of 4.8 to 480 parts by weight per 100 parts by weight of the waste positive electrode active material layer. The waste positive electrode active material layer and the Li salt are then mixed, and then heat treatment is performed in step S37 to produce the positive electrode active material.

[0118] The reason for setting the Li salt content to 4.8 to 480 parts by weight per 100 parts by weight of the recycled waste cathode active material layer is as follows.

[0119] If the Li salt content is less than 4.8 parts by weight per 100 parts by weight of the waste positive electrode active material layer, the Li salt content will be insufficient, and a sufficient capacity density cannot be secured compared to lithium-ion batteries manufactured by conventional methods, making it impossible to fully recover the battery capacity. On the other hand, if the Li salt content exceeds 480 parts by weight per 100 parts by weight of the waste positive electrode active material layer, the content of the Li component, which is a rare metal, will be excessive, which is undesirable, and the battery characteristics will tend to deteriorate.

[0120] Therefore, in this fourth embodiment, the Li salt content is set to 4.8 to 480 parts by weight, preferably 24 to 480 parts by weight, per 100 parts by weight of the waste positive electrode active material layer.

[0121] Furthermore, the Li salt is not particularly limited, and various metal salts such as the acetate compound, nitrate compound, carbonate compound, and chloride described in the first embodiment above can be used.

[0122] Subsequently, a regenerated lithium-ion battery can be obtained using the same method and procedure as in the first embodiment described above.

[0123] Thus, in this fourth embodiment, by adding only Li salt without adding ternary materials, good battery characteristics can be obtained, and there is no need to add rare metals such as Ni and Co, which further contributes to the effective use of resources.

[0124] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. In the fourth embodiment described above, powdered waste cathode active material is used as the recycled material, but good battery characteristics can be obtained in the same way as in the fourth embodiment by using powdered waste cathode material or metal granules as the recycled material.

[0125] Furthermore, in the first to third embodiments described above, the mixing ratio of the multiple metal salts mixed into the recycled material is adjusted so that NMC111 can be formed when the metal salts are mixed together and heat-treated for synthesis. However, the metal salts only need to contain Li, Ni, Mn, and Co, and the general formula LiNi includes NMC111. ｘ Mn ｙ Co ｚ O ２ A ternary metal oxide represented by (where x > 0, y > 0, z > 0, x + y + z = 1), for example, NMC433 (LiNi 0.4 Mn 0.3 Co 0.3 O ２ ), NMC523 (LiNi 0.５ Mn 0.２ Co 0.3 O ２ ), NMC622 (LiNi 0.6 Mn 0.2 Co 0.２ O ２ ) and NMC811 (LiNi 0.8 Mn 0.1 Co 0.1 O ２ ), and furthermore, the general formula Li(Li ｐ Ni ｑ Mn ｒ Co ｓ ) O ２It goes without saying that the desired effects described above are achieved even if the blending ratio is adjusted so that any of the lithium-rich ternary metal oxides represented by (where p > 0, q > 0, r > 0, s > 0, and p + q + r + s = 1) can be formed.

[0126] Furthermore, even when only a Li salt is added, as in the fourth embodiment, similar effects can be achieved with ternary or lithium-rich ternary compositions other than NMC111.

[0127] Furthermore, in the above embodiment, a precipitate is prepared from a mixed solution obtained by dissolving each metal powder in a solvent, and this precipitate is washed and dried to obtain a metal salt. However, it is also possible to simply mix multiple powdered metal salts with the recycled material.

[0128] Furthermore, although the above embodiment described a cylindrical lithium-ion battery, it goes without saying that the battery shape is not particularly limited and can be applied to prismatic, sheet, coin-type, etc. Also, the casing method is not particularly limited and may be an aluminum laminate film or molded resin.

[0129] Next, embodiments of the present invention will be specifically described. In each of the following embodiments, NMC111 is fabricated as an example of a lithium-ion battery and its cycle characteristics are evaluated. However, as described above, lithium-ion batteries with good cycle characteristics can also be obtained using other ternary materials and lithium-excess materials.

[0130] [Sample Preparation] (Sample No. 1) First, the composition formula LiMn 1 / 3 Co 1 / 3 Ni 1 / 3 O ２ A lithium-ion battery containing a positive electrode active material layer primarily composed of (MNC111) was procured from Fujifilm Wako Pure Chemical Industries and prepared. The positive electrode of this lithium-ion battery is manufactured using a water-based coating agent.

[0131] Then, the lithium-ion battery was repeatedly charged and discharged more than 3,000 times to deactivate it, and this was used as a used lithium-ion battery. Next, this lithium-ion battery was disassembled, and the used spent cathode material, used separator, and used anode material were taken out of the anode case. Further, a cutter knife was sandwiched between the used cathode material and the used separator to peel and separate the used cathode material and the used separator, and the used cathode material was pulverized to produce a blackened powder material, which was used as a recycled material.

[0132] Next, as the Ni source, (CH ３ COO) ２ Ni·4H ２ O (molecular weight: 248.84), as the Mn source, (CH ３ COO) ２ Mn·4H ２ O, (molecular weight: 245.09), as the Co source, (CH ３ COO) ２ Co·4H ２ O (molecular weight: 249.08), and as the Li source, CH ３ COOLi·2H ２ O (molecular weight: 102.02) were prepared for each metal salt. Then, the metal salts were mixed so that the mixing ratio of Li, Ni, Mn, and Co would be Li:Ni:Mn:Co = 1:1 / 3:1 / 3:1 / 3 in terms of molar ratio when these metal salts were synthesized, and a mixture was obtained.

[0133] That is, 82.95 g of (CH ３ COO) ２ Ni·4H ２ O, 81.70 g of (CH ３ COO) ２ Mn·4H ２ O, 83.03 g of (CH ３ COO) ２ Co·4H ２ O, and 107.12 g of CH ３ COOLi·2H ２ O were each weighed, and these weighed substances (total 354.80 g) were dissolved in 2,000 g of pure water to prepare a mixed solution.

[0134] On the other hand, citric acid monohydrate ((HOOCCH ２ ) ２C(OH)COOH・H ２ A citric acid aqueous solution was prepared by dissolving (molecular weight 210.14) in 2000 g of pure water.

[0135] Next, the above mixed solution and the above citric acid aqueous solution were mixed to prepare 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 the metal salt.

[0136] Next, the waste cathode material and metal salts were mixed so that the total content of metal salts was 35 g per 100 g of waste cathode material as a recycled material, and the mixture was heat-treated at 1000°C for 2 hours, after which it was allowed to cool naturally to room temperature. This mixture was then sieved using a stainless steel mesh with a mesh size of 75 μm to produce the powder sample (cathode active material) of sample number 1.

[0137] Next, the powder sample was mixed with an appropriate amount of conductive carbon as a conductive additive in water and stirred. Then, CMC / SBR as a binder was mixed into this stirred mixture and stirred again in water to obtain a water-based coating agent.

[0138] Next, using the doctor blade method, a water-based coating agent was applied to the Al substrate to form a coating film with a thickness of 300 μm. This film was then dried at a temperature of 100°C for 8 hours to produce a positive electrode in which the Al substrate served as the positive electrode current collector and the powder sample was used as the positive electrode active material.

[0139] Next, lithium metal was coated onto a Cu substrate, and a negative electrode was fabricated using the Cu substrate as the negative electrode current collector and 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.

[0140] 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 capacity density (initial value) was 81.2mAh / g.

[0141] (Sample No. 2) Sample No. 2 was prepared using the same method and procedure as Sample No. 1, except that the waste cathode material and metal salt were mixed so that the total content of metal salt was 175 parts by weight per 100 parts by weight of waste cathode material.

[0142] Then, using this powder sample, a flat cell for sample number 2 was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the capacity density (initial value) was 92.7 mAh / g.

[0143] (Sample No. 3) Powder sample No. 3 was prepared using the same method and procedure as for sample No. 1, except that the waste cathode material and metal salt were mixed so that the total content of the metal salt was 350 parts by weight per 100 parts by weight of waste cathode material.

[0144] 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 capacity density (initial value) was 99.7 mAh / g.

[0145] (Sample No. 4) Powder sample No. 4 was prepared using the same method and procedure as for sample No. 1, except that the waste cathode material and metal salt were mixed so that the total content of the metal salt was 700 parts by weight per 100 parts by weight of waste cathode material.

[0146] 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 capacity density (initial value) was 113.5 mAh / g.

[0147] (Sample No. 5) Powder sample No. 5 was prepared using the same method and procedure as for sample No. 1, except that the waste cathode material and metal salt were mixed so that the total content of the metal salt was 3500 parts by weight per 100 parts by weight of waste cathode material.

[0148] Then, using this powder sample, a flat cell for sample number 5 was prepared using the same method and procedure as for sample number 1, and when charging and discharging was performed, the capacity density (initial value) was 124.6 mAh / g.

[0149] (Sample No. 6) The waste cathode material used as recycled material in Samples No. 1 to 5 above was used as the powder sample for Sample No. 6, and a flat cell for Sample No. 6 was prepared using this powder sample in the same manner and procedure as for Sample No. 1.

[0150] When this flat cell was charged and discharged using the same method and procedure as for sample number 1, the capacity density (initial value) was 78.3 mAh / g.

[0151] (Sample No. 7) The lithium-ion battery (NMC111) procured and prepared as Sample No. 1 was used as the powder sample for Sample No. 7. Using the same method and procedure as for Sample No. 1, a flat cell for Sample No. 7 was fabricated using this powder sample, and when it was charged and discharged, the capacity density (initial value) was 148.3 mAh / g.

[0152] [Sample Evaluation] For each sample from sample numbers 1 to 7, the cycle characteristics were evaluated by repeating the charge and discharge cycle 100 times within a voltage range of 2.0V to 4.6V.

[0153] Table 1 shows the metal salt content (parts by weight) for samples 1 to 5, the initial volume density for samples 1 to 7, the volume density after each cycle (mAh / g), and the volume recovery rate (%) after 100 cycles for sample 7, respectively.

[0154]

[0155] Sample number 6 represents the cycle characteristics of waste cathode material extracted from a used lithium-ion battery. After 100 cycles, the capacity density was 49.9 mAh / g, and the capacity recovery rate was 47.8%, which was low, below 50%.

[0156] In contrast, samples 1 to 5 showed good volume densities of 55.6 to 96.4 mAh / g after 100 cycles, and their volume recovery rates compared to sample 7 were 53.3 to 92.4%, achieving over 50%. In particular, when the total metal salt content was 350 parts by weight or more, the volume recovery rate was good at over 65%, and when the total metal salt content was 3500 parts by weight, the volume recovery rate was 92.4%, indicating that excellent volume recovery rates and cycle characteristics exceeding 90% were obtained.

[0157] [Sample Preparation] (Sample No. 11) Waste cathode material was extracted from a used lithium-ion battery using the same method and procedure as in Example 1.

[0158] Next, the waste cathode material was impregnated with pure water and heated to 80°C to separate the waste cathode active material layer from the waste cathode current collector. The separated waste cathode active material layer was then placed in a drying container and dried at 80°C for 24 hours. After that, the dried waste cathode active material layer was pulverized to produce a black powder, and this powder, i.e., the waste cathode active material layer, was used as the recycled material. Furthermore, a metal salt capable of forming NMC111 after synthesis was prepared using the same method and procedure as in Example 1.

[0159] Next, the waste cathode active material layer and metal salts were mixed so that the total content of metal salts was 35 g per 100 g of the waste cathode active material layer. The mixture was then heat-treated at 1000°C for 2 hours and allowed to cool naturally to room temperature. This mixture was then sieved using a stainless steel mesh with a mesh size of 75 μm to produce the powder sample (cathode active material) of sample number 11. Subsequently, a flat cell of sample number 11 was prepared using the same method and procedure as in Example 1.

[0160] 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 initial capacity density was 98.8mAh / g.

[0161] (Sample No. 12) Sample No. 12 was prepared using the same method and procedure as Sample No. 11, except that the waste cathode active material layer and metal salt were mixed so that the total content of metal salt was 175 parts by weight per 100 parts by weight of waste cathode active material layer.

[0162] Then, using this powder sample, a flat cell for sample number 12 was prepared using the same method and procedure as for sample number 11, and when charging and discharging was performed, the capacity density (initial value) was 125.6 mAh / g.

[0163] (Sample No. 13) Sample No. 13 was prepared using the same method and procedure as Sample No. 11, except that the waste cathode active material layer and metal salt were mixed so that the total content of the metal salt was 350 parts by weight per 100 parts by weight of the waste cathode active material layer.

[0164] Then, using this powder sample, a flat cell for sample number 13 was prepared using the same method and procedure as for sample number 11, and when charging and discharging was performed, the capacity density (initial value) was 138.6 mAh / g.

[0165] (Sample No. 14) Sample No. 14 was prepared using the same method and procedure as Sample No. 11, except that the waste cathode active material layer and metal salt were mixed so that the total content of metal salt was 700 parts by weight per 100 parts by weight of waste cathode active material layer.

[0166] Then, using this powder sample, a flat cell for sample number 14 was prepared using the same method and procedure as for sample number 11, and when charging and discharging was performed, the capacity density (initial value) was 146.7 mAh / g.

[0167] (Sample No. 15) Sample No. 15 was prepared using the same method and procedure as Sample No. 11, except that the waste cathode active material layer and metal salt were mixed so that the total content of metal salt was 3500 parts by weight per 100 parts by weight of the waste cathode active material layer.

[0168] Then, using this powder sample, a flat cell for sample number 15 was prepared using the same method and procedure as for sample number 11, and when charging and discharging was performed, the capacity density (initial value) was 144.5 mAh / g.

[0169] (Sample No. 16) The waste cathode active material layer used as recycled material in Samples No. 11 to 15 was used as the powder sample for Sample No. 16, and a flat cell for Sample No. 16 was prepared using this powder sample in the same manner and procedure as for Sample No. 1.

[0170] When this flat cell was charged and discharged using the same method and procedure as for sample number 11, the capacity density (initial value) was 95.4 mAh / g.

[0171] [Sample Evaluation] For each sample from sample numbers 11 to 16, the cycle characteristics were evaluated by repeating the charge and discharge cycle 100 times within a voltage range of 2.0V to 4.6V.

[0172] Table 2 shows the metal salt content (parts by weight) for samples 11-15, the initial volume density for samples 11-16 and sample 7 (reiterated), the volume density after each cycle (mAh / g), and the volume recovery rate (%) after 100 cycles for sample 7, respectively.

[0173]

[0174] Sample No. 16 represents the cycle characteristics of the waste positive electrode active material layer extracted from a used lithium-ion battery. Since it does not contain Al derived from the waste positive electrode current collector, the capacity density after 100 cycles was 60.1 mAh / g and the capacity recovery rate was 57.6%, which is better than Sample No. 6 (Example 1). However, for Samples No. 11 to 15, the capacity density after 100 cycles was 65.6 to 98.5 mAh / g and the capacity recovery rate was 62.9 to 94.8%, indicating that the capacity density and capacity recovery rate were further improved compared to Example 1.

[0175] Thus, in this Example 2, which uses a recycled waste positive electrode active material layer, it was confirmed that better cycle characteristics can be obtained compared to Example 1, which uses recycled waste positive electrode material, because it does not contain Al derived from the waste positive electrode current collector. Furthermore, as is clear from the comparison between sample number 14 and sample number 15, when the total content of metal salts was 700 parts by weight per 100 parts by weight of the waste positive electrode active material layer, the capacity recovery rate was improved compared to when it was 3500 parts by weight. Therefore, it was found that adding too much metal salt may actually lead to a decrease in characteristics.

[0176] [Sample Preparation] (Sample No. 21) Using the same method and procedure as in Example 2, waste cathode material was removed from a used lithium-ion battery, the waste cathode current collector was peeled off from the waste cathode material, the waste cathode active material layer was removed, and this waste cathode active material layer was crushed into a black powder to obtain a powder.

[0177] Next, the powder was subjected to centrifugal separation at a rotation speed of 6000 rpm for 20 minutes, and the supernatant liquid containing SBR, CMC, and conductive carbon in the coating agent was discarded to recover the metal granules. This process was repeated twice. The recovered material was then placed in a drying container and dried at a temperature of 80°C for 24 hours, and these metal granules were used as recycled material. Furthermore, a metal salt capable of forming NMC111 after synthesis was prepared using the same method and procedure as in Example 1.

[0178] Next, the aforementioned metal granules and metal salts were mixed so that the total content of metal salts was 35 g per 100 g of metal granules. The mixture was heat-treated at 1000°C for 2 hours, and then allowed to cool naturally to room temperature. This mixture was then sieved using a stainless steel mesh with a mesh size of 75 μm to produce the powder sample (positive electrode active material) of sample number 21. Subsequently, a flat cell of sample number 21 was prepared using the same method and procedure as in Example 1.

[0179] 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 capacity density (initial value) was 106.9mAh / g.

[0180] (Sample No. 22) Sample No. 22 was prepared using the same method and procedure as Sample No. 21, except that the metal granules and metal salt were mixed so that the total content of the metal salt was 175 parts by weight per 100 parts by weight of the metal granules.

[0181] Then, using this powder sample, a flat cell for sample number 22 was prepared using the same method and procedure as for sample number 21, and when charging and discharging was performed, the capacity density (initial value) was 123.6 mAh / g.

[0182] (Sample No. 23) Sample No. 23 was prepared using the same method and procedure as Sample No. 21, except that the metal granules and metal salt were mixed so that the total content of the metal salt was 350 parts by weight per 100 parts by weight of the metal granules.

[0183] Then, using this powder sample, a flat cell for sample number 23 was prepared using the same method and procedure as for sample number 21, and when charging and discharging was performed, the capacity density (initial value) was 137.4 mAh / g.

[0184] (Sample No. 24) Sample No. 24 was prepared using the same method and procedure as Sample No. 21, except that the metal granules and metal salt were mixed so that the total content of the metal salt was 700 parts by weight per 100 parts by weight of the metal granules.

[0185] Then, using this powder sample, a flat cell for sample number 24 was prepared using the same method and procedure as for sample number 21, and when charging and discharging was performed, the capacity density (initial value) was 146.7 mAh / g.

[0186] (Sample No. 25) Sample No. 25 was prepared using the same method and procedure as Sample No. 21, except that the metal granules and metal salt were mixed so that the total content of the metal salt was 3500 parts by weight per 100 parts by weight of the metal granules.

[0187] Then, using this powder sample, a flat cell for sample number 25 was prepared using the same method and procedure as for sample number 21, and when charging and discharging was performed, the capacity density (initial value) was 135.1 mAh / g.

[0188] (Sample No. 26) The metal granules used as recycled material in Samples No. 21 to 25 were used as the powder sample for Sample No. 26, and a flat cell for Sample No. 26 was prepared using this powder sample in the same manner and procedure as for Sample No. 21.

[0189] When this flat cell was charged and discharged using the same method and procedure as for sample number 21, the capacity density (initial value) was 101.6 mAh / g.

[0190] [Sample Evaluation] For each sample from sample numbers 21 to 26, the cycle characteristics were evaluated by repeating the charge and discharge cycle 100 times within a voltage range of 2.0V to 4.6V.

[0191] Table 3 shows the metal salt content (parts by weight) for samples 21-25, the initial volume density of samples 21-26 and sample 7 (reiterated), the volume density after each cycle (mAh / g), and the volume recovery rate (%) after 100 cycles for sample 7.

[0192]

[0193] Sample No. 26 represents the cycle characteristics of metal granules obtained by centrifugation treatment of the waste positive electrode active material layer. Since it does not contain Al derived from the waste positive electrode current collector and impurities such as CMC and SBR are removed as much as possible, the capacity density after 100 cycles was 64.3 mAh / g and the capacity recovery rate was 61.6%, which was higher than that of Sample No. 16 (Example 2). In Samples No. 21 to 25, the capacity density after 100 cycles was 69.8 to 94.6 mAh / g, showing further improvement in capacity density. In particular, in Sample No. 24, which contained 700 parts by weight of metal granules per 100 weight of recycled material, a capacity recovery rate of 90.7% was achieved, securing a capacity recovery rate of over 90%. Furthermore, as is clear from the comparison between sample number 24 and sample number 25, similar to Example 2, when 700 parts by weight of metal salt were included per 100 parts by weight of metal granules, the volume recovery rate was improved compared to when 3500 parts by weight were included. Therefore, it was found that adding an excessive amount of metal salt may actually lead to a decrease in properties.

[0194] [Sample Preparation] (Sample No. 31) Using the same method and procedure as in Example 2, waste cathode material was removed from a used lithium-ion battery, the waste cathode current collector was peeled off from the waste cathode material, the waste cathode active material layer was removed, this waste cathode active material layer was crushed into a black powder to produce a powder material, and this powder material, i.e., the waste cathode active material layer, was used as the recycled material.

[0195] And then, CH ３ COOLi・2H ２ 107.12 g of oxygen was weighed and dissolved in 2000 g of pure water to prepare an aqueous solution containing lithium.

[0196] On the other hand, citric acid monohydrate ((HOOCCH ２ ) ２ C(OH)COOH・H ２ A citric acid solution was prepared by dissolving O) in 2000 g of pure water.

[0197] Next, the above-mentioned Li-containing aqueous solution and the above-mentioned citric acid aqueous solution were mixed to prepare a precipitate, which was then filtered through a paper filter to remove the supernatant. After that, the precipitate was washed three times and dried to obtain a purified Li salt.

[0198] Next, the waste cathode active material layer and Li salt were mixed so that the Li salt content was 4.8 g per 100 g of the waste cathode active material layer, and the mixture was heat-treated at 1000°C for 2 hours, after which it was allowed to cool naturally 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 (cathode active material) of sample number 31. Subsequently, a flat cell of sample number 31 was prepared using the same method and procedure as in Example 1.

[0199] 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 capacity density (initial value) was 99.3mAh / g.

[0200] (Sample No. 32) A powder sample of sample No. 32 was prepared using the same method and procedure as sample No. 31, except that the waste cathode active material layer and Li salt were mixed so that the Li salt content was 24 parts by weight per 100 parts by weight of the waste cathode active material layer.

[0201] Then, using this powder sample, a flat cell for sample number 32 was prepared using the same method and procedure as for sample number 31, and when charging and discharging was performed, the capacity density (initial value) was 115.4 mAh / g.

[0202] (Sample No. 33) A powder sample of sample No. 33 was prepared using the same method and procedure as sample No. 31, except that the waste cathode active material layer and Li salt were mixed so that the Li salt content was 48 parts by weight per 100 parts by weight of the waste cathode active material layer.

[0203] Then, using this powder sample, a flat cell for sample number 33 was prepared using the same method and procedure as for sample number 31, and when charging and discharging was performed, the capacity density (initial value) was 129.8 mAh / g.

[0204] (Sample No. 34) Sample No. 34 was prepared using the same method and procedure as Sample No. 31, except that the waste cathode active material layer and Li salt were mixed so that the Li salt content was 96 parts by weight per 100 parts by weight of the waste cathode active material layer.

[0205] Then, using this powder sample, a flat cell for sample number 34 was prepared using the same method and procedure as for sample number 31, and when it was charged and discharged, the capacity density (initial value) was 139.6 mAh / g.

[0206] (Sample No. 35) Sample No. 35 was prepared using the same method and procedure as Sample No. 11, except that the waste cathode active material layer and Li salt were mixed so that the Li salt content was 480 parts by weight per 100 parts by weight of the waste cathode active material layer.

[0207] Then, using this powder sample, a flat cell for sample number 35 was prepared using the same method and procedure as for sample number 31, and when charging and discharging was performed, the capacity density (initial value) was 121.5 mAh / g.

[0208] [Sample Evaluation] For each sample from sample numbers 31 to 35, the cycle characteristics were evaluated by repeating the charge and discharge cycle 100 times within a voltage range of 2.0V to 4.6V.

[0209] Table 4 shows the Li salt content (parts by weight) of samples 31-35, the initial volume density of samples 31-35 and sample 7 (reiterated), the volume density after each cycle (mAh / g), and the volume recovery rate (%) after 100 cycles for sample 7.

[0210]

[0211] As is clear from Table 4, samples 31 to 35 showed good results, with a capacity density of 63.7 to 89.5 mAh / g after 100 cycles and a capacity recovery rate of 61.1 to 85.8%. In other words, although the capacity recovery rate was slightly lower compared to Example 2, in which a waste cathode active material layer was mixed with multiple ternary metal salts, it was found that the capacity recovery rate improved when the Li salt content was 96 parts by weight or less per 100 parts by weight of the waste cathode active material layer, compared to Example 1, in which the waste cathode material was recycled. In other words, it was confirmed that the addition of Li salt is effective in improving capacity density and capacity recovery, and that the battery characteristics improve with the addition of Li salt alone, thus effectively reducing the use of rare metals. Furthermore, as is clear from the comparison between sample number 34 and sample number 35, when the Li salt content was 96 parts by weight per 100 parts by weight of the waste positive electrode active material layer, the volume recovery rate was improved compared to when 480 parts by weight were included. Therefore, it was found that adding an excessive amount of Li salt may actually lead to a decrease in performance.

[0212] In Example 2 described above, the waste positive electrode active material layer of a lithium-ion battery using a water-based coating agent was reused as the material, and a regenerated lithium-ion battery was fabricated using the water-based coating agent. In Example 5, however, the waste positive electrode active material layer of a lithium-ion battery using a solvent-based coating agent was reused as the material, and a regenerated lithium-ion battery was fabricated using the solvent-based coating agent. The characteristics were evaluated using the same method and procedure as in Example 2.

[0213] Specifically, first, a lithium-ion battery containing a positive electrode active material layer mainly composed of MNC111 was procured and prepared. This lithium-ion battery was manufactured using a solvent-based coating agent consisting of PVDF as the binder and MNP as the solvent.

[0214] This lithium-ion battery was discharged and deactivated using the same method and procedure as in Example 1, then disassembled, and the waste positive electrode material, waste separator, and waste negative electrode material were removed from the negative electrode case.

[0215] Next, the waste cathode material was impregnated with MNP and heated to 135°C to separate the waste cathode active material layer from the waste cathode current collector. The separated waste cathode active material layer was then placed in a drying container and dried at 80°C for 24 hours. After that, the dried waste cathode active material layer was pulverized to produce a black powder, and this powder, i.e., the waste cathode active material layer, was used as the recycled material. Furthermore, a metal salt capable of producing NMC111 after synthesis was obtained using the same method and procedure as in Example 1.

[0216] Next, the waste cathode active material layer and the metal salt were mixed so that the metal salt content was 35 g per 100 g of the waste cathode active material layer. The mixture was then heat-treated at 1000°C for 2 hours and allowed to cool naturally to room temperature. This mixture was then sieved using a stainless steel mesh with a mesh size of 75 μm to produce the powder sample (cathode active material) designated as sample number 41.

[0217] Next, the powder sample was stirred in NMP with an appropriate amount of conductive carbon to obtain a stirred material. Then, an NMP solution was prepared by dissolving 5 wt% PVDF in NMP. An appropriate amount of the NMP solution was added to the stirred material, and the stirring process was performed three times at predetermined intervals. After that, a degassing treatment was performed, thereby obtaining a solvent-based coating agent.

[0218] Subsequently, the positive and negative electrodes were prepared using the same method and procedure as in Example 1, except that this solvent-based coating agent was used, and a flat cell of sample number 41 was fabricated.

[0219] 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 initial capacity density was 95.2mAh / g.

[0220] (Sample No. 42) Sample No. 42 was prepared using the same method and procedure as Sample No. 41, except that the waste cathode active material layer and metal salt were mixed so that the total content of metal salt was 175 parts by weight per 100 parts by weight of waste cathode active material layer.

[0221] Then, using this powder sample, a flat cell for sample number 42 was prepared using the same method and procedure as for sample number 41, and when charging and discharging was performed, the capacity density (initial value) was 122.1 mAh / g.

[0222] (Sample No. 43) Powder sample No. 43 was prepared using the same method and procedure as sample No. 41, except that the waste cathode active material layer and metal salt were mixed so that the total content of metal salt was 350 parts by weight per 100 parts by weight of waste cathode active material layer.

[0223] Then, using this powder sample, a flat cell for sample number 43 was prepared using the same method and procedure as for sample number 41, and when charging and discharging was performed, the capacity density (initial value) was 135.3 mAh / g.

[0224] (Sample No. 44) Powder sample No. 44 was prepared using the same method and procedure as sample No. 41, except that the waste cathode active material layer and metal salt were mixed so that the total content of metal salt was 700 parts by weight per 100 parts by weight of waste cathode active material layer.

[0225] Then, using this powder sample, a flat cell for sample number 44 was prepared using the same method and procedure as for sample number 41, and when charging and discharging was performed, the capacity density (initial value) was 143.7 mAh / g.

[0226] (Sample No. 45) Powder sample No. 45 was prepared in the same manner and procedure as sample No. 41, except that the waste cathode active material layer and metal salt were mixed so that the total content of metal salt was 3500 parts by weight per 100 parts by weight of waste cathode active material layer.

[0227] Then, using this powder sample, a flat cell for sample number 45 was prepared using the same method and procedure as for sample number 41, and when it was charged and discharged, the capacity density (initial value) was 141.2 mAh / g.

[0228] (Sample No. 46) The waste cathode active material layer used as recycled material in Samples No. 41 to 45 was used as the powder sample for Sample No. 46, and a flat cell for Sample No. 46 was prepared using this powder sample in the same manner and procedure as for Sample No. 41.

[0229] When this flat cell was charged and discharged using the same method and procedure as for sample number 41, the capacity density (initial value) was 91.2 mAh / g.

[0230] [Sample Evaluation] For each sample from sample numbers 41 to 46, the cycle characteristics were evaluated by repeating the charge and discharge cycle 100 times within a voltage range of 2.0V to 4.6V.

[0231] Table 5 shows the metal salt content (parts by weight) of samples 41-46, the initial volume density of samples 41-46 and sample 7 (reiterated), the volume density after each cycle (mAh / g), and the volume recovery rate (%) after 100 cycles for sample 7.

[0232]

[0233] Sample No. 46 represents the cycle characteristics of a waste positive electrode active material layer extracted from a used lithium-ion battery. After 100 cycles, the capacity density was 57.8 mAh / g, and the capacity recovery rate was low at 55.4%, similar to Sample No. 16 (Example 2) which used a water-based coating agent.

[0234] In contrast, samples 41 to 45 showed a capacity density of 61.1 to 97.3 mAh / g after 100 cycles, and a capacity recovery rate of 58.6 to 93.3%, indicating that a good capacity recovery rate can be obtained even when the cathode is fabricated using a solvent-based coating agent.

[0235] In other words, regardless of the type of coating agent, it was confirmed that adding a ternary material and a metal salt containing Li to the waste positive electrode active material layer of used lithium-ion batteries improves the capacity recovery rate and allows for the acquisition of good cycle characteristics. Furthermore, as is clear from the comparison between sample number 44 and sample number 45, similar to Examples 2 and 3, when 700 parts by weight of metal granules were included per 100 parts by weight of recycled material, the capacity recovery rate was improved compared to when 3500 parts by weight were included. Therefore, it was found that even when using a solvent-based coating agent, adding an excessive amount of metal salt may actually lead to a decrease in characteristics.

[0236] By using waste cathode material, waste cathode active material layer, or metal granules obtained by centrifuging the waste cathode active material layer from used lithium-ion batteries as recycled materials, and adding a predetermined amount of ternary material and Li salt, or Li salt alone, good battery characteristics can be obtained while effectively utilizing resources.

[0237] 3 Positive electrode 5 Negative electrode 11 Electrolyte 13a, 13b Positive electrode active material layer (electrode active material) 15a, 15b Negative electrode active material layer 23 Waste positive electrode material

Claims

1. A method for producing an electrode active material, comprising: recycling waste electrode material obtained by disassembling a used lithium-ion battery to produce an electrode active material, wherein the waste electrode material comprises a waste electrode active material layer having a mixture of metal granules containing at least Ni, Mn, Co, and Li components and a coating agent, and a waste electrode current collector bonded to the waste electrode active material layer, wherein the recycled material is a powder obtained by crushing any of the waste electrode material, the waste electrode active material layer, and the metal granules, and the recycled material and the metal salts are mixed and heat-treated so that the total amount of multiple metal salts containing Ni, Mn, Co, and Li components is 35 to 3500 parts by weight per 100 parts by weight of the recycled material, and the recycled material and the metal salts react to produce an electrode active material.

2. The method for producing an electrode active material according to claim 1, characterized in that the recycled material and the metal salts are mixed and heat-treated such that the total amount of the plurality of metal salts is 350 to 3500 parts by weight per 100 parts by weight of the recycled material.

3. A method for producing an electrode active material according to claim 1 or 2, characterized in that the waste electrode material is impregnated with a solvent of the same type as the solvent contained in the coating agent and heated to separate the waste electrode active material layer from the waste electrode current collector, and the waste electrode active material layer is used as a recycled material.

4. The method for producing an electrode active material according to claim 1 or 2, characterized in that the coating agent includes an aqueous coating agent.

5. The method for producing an electrode active material according to claim 4, characterized in that the aqueous coating agent contains carboxymethylcellulose and a styrene-butadiene copolymer.

6. The method for producing an electrode active material according to claim 1 or 2, characterized in that the coating agent includes a solvent-based coating agent.

7. The method for producing an electrode active material according to claim 6, characterized in that the solvent-based coating agent contains polyvinylidene fluoride and N-methyl-2-pyrrolidone.

8. A method for producing an electrode active material according to claim 1 or 2, characterized in that, after separating the waste electrode material into the waste electrode active material layer and the waste electrode current collector, the waste electrode active material layer is subjected to centrifugal separation to recover the metal granules, and the metal granules are used as the recycled material.

9. A method for producing an electrode active material according to claim 1 or 2, characterized in that each metal powder containing each component forming the metal salt is dissolved in a solvent to prepare a mixed solution, the mixed solution is treated to produce a precipitate, the metal salt is obtained from the precipitate, and the recycled material and the metal salt are mixed.

10. The method for producing an electrode active material according to claim 1 or 2, characterized in that the heat treatment is carried out at a temperature of 650 to 1100°C for 0.5 to 12 hours.

11. When the plurality of metal salts are synthesized by mixing these plurality of metal salts with each other, the composition formula is LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O ２ The general formula LiNi ｘ Mn ｙ Co ｚ O ２ (where x > 0, y > 0, z > 0, x + y + z = 1) represents a metal oxide, and the general formula Li(Li ｐ Ni ｑ Mn ｒ Co ｓ )O ２ (where p > 0, q > 0, r > 0, s > 0, p + q + r + s = 1) is adjusted so that any one of the metal oxides represented can be formed, and the mixing ratio is adjusted to be mixed with the recycled material. The method for producing an electrode active material according to claim 1 or claim 2.

12. A method for producing an electrode active material by reusing waste electrode material obtained by disassembling a used lithium-ion battery, wherein the waste electrode material comprises a waste electrode active material layer having a mixture of metal granules containing at least Ni, Mn, Co, and Li components and a coating agent, and a waste electrode current collector adhered to the waste electrode active material layer, wherein the recycled material is a powder obtained by crushing any of the waste electrode material, the waste electrode active material layer, and the metal granules, and the recycled material and the metal salt are mixed and heat-treated so that the amount of metal salt containing Li component is 4.8 to 480 parts by weight per 100 parts by weight of the recycled material, and the recycled material and the metal salt are reacted to produce an electrode active material.

13. The method for producing an electrode active material according to claim 12, characterized in that the recycled material and the metal salt are mixed so that the amount of the metal salt is 24 to 480 parts by weight per 100 parts by weight of the recycled material, and then heat-treated.

14. A method for producing an electrode active material according to claim 12 or 13, characterized in that the waste electrode material is impregnated with a solvent of the same type as the solvent contained in the coating agent and heated to separate the waste electrode active material layer from the waste electrode current collector, and the waste electrode active material layer is used as the recycled material.

15. A method for producing an electrode active material according to claim 12 or 13, characterized in that a metal powder containing Li is dissolved in a solvent to produce a Li-containing solution, the Li-containing solution is treated to produce a precipitate, the metal salt is obtained from the precipitate, and the recycled material and the metal salt are mixed.

16. The method for producing an electrode active material according to claim 12 or 13, characterized in that the heat treatment is carried out at a temperature of 650 to 1100°C for 0.5 to 12 hours.

17. An electrode active material formed by reusing waste electrode material obtained by disassembling a used lithium-ion battery, wherein the waste electrode material comprises a waste electrode active material layer containing metal granules mainly composed of at least Ni, Mn, Co, and Li and a coating agent, and a waste electrode current collector adhered to the waste electrode active material layer, and the recycled material is formed from powder obtained by crushing any of the waste electrode material, the waste electrode active material layer, and the metal granules, and the total amount of multiple metal salts each containing Ni, Mn, Co, and Li is contained in the recycled material in an amount of 35 to 3500 parts by weight per 100 parts by weight.

18. The electrode active material according to claim 17, characterized in that the total amount of the plurality of metal salts is contained in 350 to 3500 parts by weight per 100 parts by weight of the recycled material.

19. An electrode active material formed by reusing waste electrode material obtained by disassembling a used lithium-ion battery, wherein the waste electrode material has a waste electrode current collector bonded mainly to at least Ni, Mn, Co, and Li, the recycled material is formed from powder obtained by crushing K, and a metal salt containing Li is contained in an amount of 4.8 to 480 parts by weight per 100 parts by weight of the recycled material.

20. The electrode active material according to claim 19, characterized in that the metal salt is contained in an amount of 24 to 480 parts by weight per 100 parts by weight of the recycled material.

21. 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, 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 17, and the method includes a step of manufacturing the positive electrode using an aqueous or solvent-based coating agent.

22. A lithium-ion battery having a positive electrode, a negative electrode, and an electrolyte, which repeatedly charges and discharges 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 of the electrode active material described in claim 17 or claim 18.

23. The lithium-ion battery according to claim 22, characterized in that the negative electrode active material, which is the main component of the negative electrode, is formed of one selected from the group consisting of lithium metal, lithium titanate, carbon-based materials, and silicon oxide-based materials.

24. A lithium-ion battery having a positive electrode, a negative electrode, and an electrolyte, which repeatedly charges and discharges 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 of the electrode active material described in claim 19 or claim 20.

25. The lithium-ion battery according to claim 24, characterized in that the negative electrode active material, which is the main component of the negative electrode, is formed of one selected from the group consisting of lithium metal, lithium titanate, carbon-based materials, and silicon oxide-based materials.

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