Method for recovering electrode materials and method for manufacturing recycled electricity storage devices

Abstract

To improve a recovery rate of an electrode material.SOLUTION: A method for recovering an electrode material includes a preparation step of preparing an electrode body 20 or an electrode sheet 21, 22 including a current collector and an electrode active material layer formed on the current collector and containing an electrode active material, a dissolution step of immersing the electrode body 20 or the electrode sheet 21 in an etching solution that dissolves the current collector, and a separation step of separating a precipitate containing the electrode active material from the etching solution in which the current collector has been dissolved.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for recovering electrode materials and a method for manufacturing a recycled electricity storage device. [Background technology]

[0002] Japanese Patent No. 6334450 discloses a method for recovering metals from recycled lithium-ion battery materials. The publication discloses acid leaching of powdered or granular lithium-ion battery scrap obtained through various processes, such as roasting, crushing, and sieving, using aqueous hydrogen peroxide. Potential metals, such as lithium, nickel, cobalt, manganese, iron, copper, and aluminum, are dissolved in the solution to obtain a leachate. The leachate is then subjected to solvent extraction to sequentially separate each metal element. The publication states that each valuable metal can be recovered by first recovering iron and aluminum, followed by manganese and copper, cobalt, and then nickel, with lithium remaining in the aqueous phase.

[0003] Furthermore, the publication proposes that, regarding manganese contained in the post-leaching solution after acid leaching, when lithium-ion battery recycled materials are subjected to acid leaching in an acid solution, the manganese contained in the lithium-ion battery recycled materials is first leached, and the resulting manganese ions in the acid solution promote the leaching of the target metals contained in the lithium-ion battery recycled materials, and then, as the target metals are leached, the manganese that was once dissolved in the acid solution precipitates and is incorporated into the residue. Taking advantage of this, it is proposed to precipitate and separate manganese in the leaching process, thereby simplifying or eliminating the recovery of manganese in the subsequent recovery process. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6334450 Summary of the Invention [Problem to be solved by the invention]

[0005] In energy storage devices such as lithium-ion secondary batteries, rare metals are contained in large amounts in the electrode materials in the electrode assembly. The process of separating and recovering the electrode materials from the electrode assembly, such as the process described in the above publication, is complicated, and it cannot be said that a technology for efficiently extracting the electrode materials from the electrode assembly has been established. In order to realize a recycling-oriented society in the future, it will be necessary to establish an efficient recycling technology for the electrode materials used in energy storage devices. [Means for solving the problem]

[0006] The electrode material recovery method disclosed herein includes a preparation step of preparing an electrode body or an electrode sheet including a current collector and an electrode active material layer formed on the current collector and containing an electrode active material; a dissolution step of immersing the electrode body or electrode sheet in an etching solution that dissolves the current collector; and a separation step of separating a precipitate containing the electrode active material from the etching solution in which the current collector has been dissolved.

[0007] According to this method for recovering electrode materials, the recovery rate of electrode materials can be improved compared to when the entire battery is scrapped and immersed in an etching solution. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a lithium ion secondary battery 10. As shown in FIG. [Figure 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a schematic diagram of the electrode body 20. As shown in FIG. [Figure 4] FIG. 4 is a flow diagram of a method for recovering an electrode material. [Figure 5] FIG. 5 is a flow diagram showing the steps of removing the electrode body 20 from the lithium ion secondary battery 10. DETAILED DESCRIPTION OF THE INVENTION

[0009] The disclosure herein is explained below. Unless otherwise specified, the disclosure herein is not intended to limit the invention described in the claims of this application. Each drawing is a schematic drawing and does not necessarily reflect the actual product. Furthermore, members and parts that perform the same function are appropriately designated by the same reference numerals, and redundant explanations will be omitted. In this specification, expressions such as "X to Y" that indicate a numerical range mean "X or more and Y or less" unless otherwise specified.

[0010] The present disclosure relates to a method for recovering electrode materials from an electrode assembly, for example, by recovering electrode materials from an electrode assembly removed from a used lithium-ion secondary battery. The electrode assembly may have, for example, a positive electrode current collector made of aluminum or an aluminum alloy and a negative electrode current collector made of copper or a copper alloy.

[0011] The electrode body to which the electrode material recovery method is applied is not limited to one removed from a used lithium-ion secondary battery. For example, it may be an electrode body obtained from an electricity storage device such as a storage battery such as a lithium-ion secondary battery, or a capacitor such as a lithium-ion capacitor or an electric double layer capacitor. Furthermore, the electrode body is not limited to one removed from a used electricity storage device, and may be an electrode body discarded as a defective product during the production of an electricity storage device. Here, a method for recovering electrode materials from an electrode body will be described using an electrode body removed from a used lithium-ion secondary battery as an example.

[0012] <Lithium-ion secondary battery 10> FIG. 1 is a perspective view of a lithium-ion secondary battery 10. FIG. 2 is a schematic longitudinal sectional view taken along line II-II in FIG. 1. FIG. 3 is a schematic view of an electrode assembly 20. FIG. 2 illustrates a state in which the interior of the lithium-ion secondary battery 10 is exposed along one wide surface of a substantially rectangular parallelepiped battery case 41. FIG. 2 also illustrates a partially cutaway partial sectional view of the electrode assembly 20. The lithium-ion secondary battery 10 illustrated in FIG. 2 is a so-called sealed battery in which the battery case 41 housing the electrode assembly 20 is sealed. In this embodiment, the battery case 41 is formed of a metal case having a substantially rectangular parallelepiped shape. In the drawings, the symbol X indicates the long side direction of the battery case 41. The symbol Y indicates the short side direction perpendicular to the long side direction. The symbol Z indicates the height direction perpendicular to the short side direction and the long side direction. The structure of the battery case 41 is not limited to this form. For example, the battery case 41 may be a cylindrical case or a so-called bag-shaped laminate case that covers the electrode body 20.

[0013] As shown in FIG. 1 , the lithium-ion secondary battery 10 includes an electrode assembly 20 and a battery case 41. The battery case 41 includes a case body 41a having an opening 41a1 and a sealing plate 41b that closes the opening 41a1 of the case body 41a. The case body 41a accommodates the electrode assembly 20. Internal terminals 55, 65 and external terminals 51, 61 are attached to the sealing plate 41b via a gasket 70 and an insulator 80. In this embodiment, the internal terminal 55 is connected to the positive electrode current collector foil 21a of the electrode assembly 20. The external terminal 51 is connected to the internal terminal 55 and constitutes the positive electrode terminal 50 outside the battery case 41. The internal terminal 65 is connected to the negative electrode current collector foil 22a of the electrode assembly 20. The external terminal 61 is connected to the internal terminal 65 and constitutes the negative electrode terminal 60 outside the battery case 41.

[0014] <Electrode body 20> In the electrode assembly 20, a positive electrode element 21 and a negative electrode element 22 face each other with a separator interposed therebetween. The positive electrode element 21 includes a positive electrode current collector 21a and a positive electrode active material layer 21b formed on the positive electrode current collector 21a and containing a positive electrode active material. The negative electrode element 22 includes a negative electrode current collector 22a and a negative electrode active material layer 22b formed on the negative electrode current collector 22a and containing a negative electrode active material. The positive electrode element and the negative electrode element may each be sheet-shaped. In this case, the positive electrode element may be, for example, a sheet-shaped member in which the positive electrode active material layer 21b is formed on both sides of the positive electrode current collector 21a made of metal foil with a predetermined width and thickness. The negative electrode element may be a sheet-shaped member in which the negative electrode active material layer 22b is formed on both sides of the negative electrode current collector 22a made of metal foil with a predetermined width and thickness. The sheet-shaped positive electrode element 21 is referred to as a positive electrode sheet. The sheet-like negative electrode sheet is called a negative electrode sheet.

[0015] For example, the electrode assembly 20 may be a so-called wound electrode assembly. The electrode assembly 20 is composed of a positive electrode sheet 21 as a positive electrode element, a negative electrode sheet 22 as a negative electrode element, and separator sheets 31 and 32 as separators. The positive electrode sheet 21, the first separator sheet 31, the negative electrode sheet 22, and the second separator sheet 32 ​​are each long strip-shaped members that are stacked and wound with their length and width directions aligned. The electrode assembly 20 is housed in a battery case 41 while covered with an insulating film (not shown) or the like.

[0016] <Positive electrode sheet 21> The positive electrode sheet 21 has a positive electrode current collector foil 21a of predetermined width and thickness, and positive electrode active material layers 21b containing a positive electrode active material formed on both sides thereof, except for an unformed portion 21a1 set at a constant width at one end of the width direction. A plurality of positive electrode tabs 21t are intermittently provided in the unformed portion 21a1 at predetermined positions along the longitudinal direction of the positive electrode sheet 21. Each of the plurality of positive electrode tabs 21t protrudes in the width direction of the positive electrode sheet 21. In this embodiment, the positions at which the plurality of positive electrode tabs 21t are provided are determined so that the positions of the plurality of positive electrode tabs 21t are aligned in a wound state.

[0017] For the positive electrode current collector 21a, a material having required resistance properties such as electrolyte resistance and oxidation resistance is used, taking into consideration the operating potential at the positive electrode. For example, in a lithium-ion secondary battery, aluminum or an aluminum alloy containing aluminum as the main material is generally used for the positive electrode current collector 21a. For the sheet-like positive electrode element 21, aluminum or an aluminum foil containing aluminum as the main material may be used for the positive electrode current collector 21a. For the positive electrode active material contained in the positive electrode active material layer 21b, a material that can release charge carriers during charging and absorb charge carriers during discharging is used.

[0018] For example, in a lithium-ion secondary battery, the cathode active material is a material that releases lithium ions during charging and absorbs lithium ions during discharging. Examples of the cathode active material include lithium transition metal composite materials. Various cathode active materials other than lithium transition metal composite materials have been proposed, and unless otherwise specified, the cathode active material is not limited to lithium transition metal composite materials. The cathode active material layer 21b may be formed, for example, by applying a mixture of the cathode active material, a conductive material, a binder, and the like in a solvent and drying the mixture. In this embodiment, a cathode protective layer 21p is provided on the edge of the cathode active material layer 21b on the cathode current collector foil 21a (unformed portion 21a1). The cathode protective layer 21p is a layer that protects the unformed portion 21a1 and may be a layer containing an inorganic filler (e.g., alumina).

[0019] <Negative electrode sheet 22> The negative electrode sheet 22 has a negative electrode current collector foil 22a of predetermined width and thickness, and a negative electrode active material layer 22b containing a negative electrode active material formed on both sides thereof, except for an unformed portion 22a1 set at a constant width on one edge in the width direction. In this embodiment, a plurality of negative electrode tabs 22t are intermittently provided in the unformed portion 22a1 at predetermined positions along the longitudinal direction of the negative electrode sheet 22. Each of the plurality of negative electrode tabs 22t protrudes in the width direction of the negative electrode sheet 22. In this embodiment, the positions at which the plurality of negative electrode tabs 22t are provided are determined so that the positions of the plurality of negative electrode tabs 22t are aligned in a wound state.

[0020] The negative electrode current collector 22a is made of a material having the required resistance, such as electrolyte resistance and oxidation resistance, taking into account the operating potential of the negative electrode. For example, in lithium-ion secondary batteries, copper or a copper alloy containing copper as the main material is generally used for the negative electrode current collector 22a. In the sheet-shaped negative electrode element 22, copper or a copper foil containing copper as the main material may be used for the negative electrode current collector 22a. The negative electrode active material contained in the negative electrode active material layer 22b is made of a material capable of absorbing charge carriers during charging and releasing charge carriers during discharging. For example, in lithium-ion secondary batteries, a material such as natural graphite is used, which is capable of absorbing lithium ions during charging and releasing the absorbed lithium ions during discharging. Various negative electrode active materials other than natural graphite have been proposed, and are not particularly limited. The negative electrode active material layer 22b may be made of, for example, a mixture of the negative electrode active material, a conductive material, a binder, and the like mixed in a solvent, which is applied and dried.

[0021] The separator sheets 31, 32 are, for example, porous resin sheets that have the required heat resistance and allow electrolytes to pass through. Various separator sheets 31, 32 have been proposed, and there is no particular limitation. The separators 31, 32 may have a functional layer, such as an adhesive layer or a heat-resistant layer (HRL), on the surface of a substrate made of a porous resin sheet. The heat-resistant layer is a layer containing, for example, an inorganic filler such as alumina, silica, boehmite, magnesia, or titania, and a binder such as PVdF. The heat-resistant layer may also function as an adhesive layer.

[0022] Here, as shown in FIG. 2, the width Ln of the negative electrode active material layer 22b is formed wider than, for example, the width Lp of the positive electrode active material layer 21b. The widths Ls of the separator sheets 31 and 32 are wider than the negative electrode active material layer 22b. That is, as shown in FIG. 2, Lp < Ln < Ls. The positive electrode sheet 21, the first separator sheet 31, the negative electrode sheet 22, and the second separator sheet 32 are aligned in the length direction and are stacked and wound in order. Here, the negative electrode active material layer 22b covers the positive electrode active material layer 21b with the separator sheets 31 and 32 interposed therebetween. The negative electrode active material layer 22b is covered with the separator sheets 31 and 32. The positive electrode tab 21t of the positive electrode current collector foil 21a and the negative electrode tab 22t of the negative electrode current collector foil 22a are provided so as to protrude from the separator sheets 31 and 32 toward opposite sides in the width direction. The positive electrode protective layer 21p faces the edge of the negative electrode sheet 22 on the side opposite to the side where the negative electrode tab 22t is provided through the separator sheets 31 and 32.

[0023] As shown in FIG. 2, the electrode body 20 is in a flat state along a plane including the winding axis WL so as to be accommodated in the case body 41a of the battery case 41. Along the winding axis WL of the electrode body 20, the positive electrode tab 21t is disposed on one side and the negative electrode tab 22t is disposed on the opposite side. Here, as an example of the electrode body 20, a wound electrode body in which the positive electrode sheet 21, the first separator sheet 31, the negative electrode sheet 22, and the second separator sheet 32 are stacked and wound is illustrated. The configuration of the electrode body 20 is not limited to such a wound electrode body. Although not shown in the figure, the electrode body 20 may be, for example, a so-called laminated electrode body in which a positive electrode sheet and a negative electrode sheet having a predetermined shape are stacked with a separator sheet interposed therebetween.

[0024] 〈Battery Case 41〉 The battery case 41 accommodates the electrode assembly 20. In this embodiment, the battery case 41 includes a case body 41a and a sealing plate 41b. The case body 41a is a bottomed member having an opening 41a1 on one side opposite the bottom. In this embodiment, the case body 41a has a generally rectangular parallelepiped shape with one side open. The sealing plate 41b is a plate material attached to the opening 41a1 of the case body 41a. In this embodiment, the case body 41a and the sealing plate 41b are each formed of aluminum or an aluminum alloy primarily containing aluminum to ensure lightweight and required rigidity. Note that, although the embodiment shown in FIG. 1 illustrates a wound-type electrode assembly 20, the structure of the electrode assembly 20 is not limited to this form. The electrode assembly 20 may have a laminated structure in which positive electrode sheets and negative electrode sheets are alternately stacked with separator sheets interposed therebetween. Furthermore, the battery case 41 may accommodate multiple electrode assemblies 20.

[0025] The battery case 41 can accommodate an electrolyte (not shown). A non-aqueous electrolyte in which a supporting salt is dissolved in a non-aqueous solvent can be used as the electrolyte. Examples of non-aqueous solvents include carbonate-based solvents such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of supporting salts include fluorine-containing lithium salts such as LiPF6.

[0026] <Case body 41a> The case body 41a has a generally rectangular parallelepiped shape with one side open. The case body 41a has a bottom surface 42 that forms a generally rectangular bottom surface, a pair of wide surface portions 43, 44 (see FIG. 2), and a pair of narrow surface portions 45, 46. The pair of wide surface portions 43, 44 each rise from a long side of the bottom surface 42. The pair of narrow surface portions 45, 46 each rise from a short side of the bottom surface 42. An opening 41a1 surrounded by the pair of wide surface portions 43, 44 and the pair of narrow surface portions 45, 46 is formed on one side of the case body 41a.

[0027] <Sealing plate 41b> The sealing plate 41b seals the opening 41a1 of the case body 41a. In this embodiment, as shown in FIG. 2, the sealing plate 41b is rectangular in plan view. In this embodiment, the sealing plate 41b is provided with a liquid inlet 41b1 and a safety valve 41b3. The liquid inlet 41b1 is closed by attaching a sealing member 41b2 after the sealing plate 41b is attached to the opening 41a1 of the case body 41a and electrolyte is injected into the case body 41a. Note that FIG. 2 shows the state in which the sealing plate 41b is assembled to the opening 41a1 of the case body 41a and welded. In FIG. 2, no sealing member is attached to the sealing plate 41b. The safety valve 41b3 is thin-walled and breaks when the pressure inside the battery case 41 exceeds a predetermined value.

[0028] A positive electrode terminal 50 and a negative electrode terminal 60 are attached to the sealing plate 41b. The positive electrode terminal 50 includes an external terminal 51 and an internal terminal 55. The negative electrode terminal 60 includes an external terminal 61 and an internal terminal 65. The internal terminals 55, 65 are each attached to the inside of the sealing plate 41b via an insulator 80. The external terminals 51, 61 are each attached to the outside of the sealing plate 41b via a gasket 70. The internal terminals 55, 65 each extend into the case body 41a. The unformed portion 21a1 of the positive electrode current collector foil 21a and the unformed portion 22a1 of the negative electrode current collector foil 22a of the electrode body 20 are attached to internal terminals 55, 65, which are attached to both sides of the long side of the sealing plate 41b, respectively.

[0029] The internal terminals 55, 65 are made of metal. For example, aluminum or an aluminum alloy may be used as the positive electrode internal terminal 55 in order to improve the bonding strength with the positive electrode tab 21t. For example, copper or a copper alloy may be used as the negative electrode internal terminal 65 in order to improve the bonding strength with the negative electrode tab 22t and because it has the required resistance such as electrolyte resistance and oxidation resistance.

[0030] The external terminals 51, 61 are made of metal. The metal used for the external terminals 51, 61 is appropriately selected depending on the type of external connection component, such as a bus bar. Examples of materials that can be used for the external terminals 51, 61 include aluminum, aluminum alloys, copper, and copper alloys. The external terminals 51, 61 may be formed by joining multiple metals together using dissimilar metal joining. Although not shown, a mounting hole is formed in the sealing plate 41b. An insulator 80 is attached to the inside of the mounting hole, and a gasket 70 is attached to the outside of the sealing plate 41b. One of the internal terminals 55, 65 and the external terminals 51, 61 has a shaft, which is inserted into the mounting hole with the gasket 70 and the insulator 80 interposed therebetween. The internal terminals 55, 65 and the external terminals 51, 61 are joined by the shaft inserted into the mounting hole.

[0031] The gasket 70 and the insulator 80 are preferably made of a material having excellent chemical resistance and weather resistance. In this embodiment, the gasket 70 is made of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). The material used for the gasket 70 is not limited to PFA. For example, polypropylene (PP), polyethylene (PE), polyphenylene sulfide resin (PPS), etc. may be used for the gasket 70. The insulator 80 is made of polyphenylene sulfide resin (PPS). The material used for the insulator 80 is not limited to PPS.

[0032] During manufacturing, the lithium-ion secondary battery 10 has the positive electrode terminal 50 and the negative electrode terminal 60 attached to the sealing plate 41b with the gasket 70 and the insulator 80 attached to the sealing plate 41b. Next, the positive electrode tab 21t is joined to the internal terminal 55 of the positive electrode terminal 50, and the negative electrode tab 22t is joined to the internal terminal 65 of the negative electrode terminal 60, thereby attaching the electrode body 20 to the sealing plate 41b. Next, the electrode body 20 is inserted into the case body 41a from the opening 41a1, and the sealing plate 41b is attached to the opening 41a1 (see FIG. 1) of the case body 41a. At this time, the winding axis WL (see FIG. 3) of the electrode body 20 is arranged along the long side direction X of the case body 41a. The positive electrode tab 21t of the electrode body 20 faces the narrow surface portion 45. The negative electrode tab 22t faces the narrow surface portion 46. 2, the peripheral edge of sealing plate 41b is joined to the edge of opening 41a1 of case body 41a. This joining may be achieved, for example, by continuous welding without any gaps. This welding may be achieved, for example, by laser welding.

[0033] The electrode assembly 20 is not limited to such a wound electrode assembly. As described above, the electrode assembly 20 may be a so-called stacked electrode assembly. Furthermore, a plurality of electrode assemblies 20 may be housed in the battery case 41. Various structures may be employed for the internal terminals 55, 65, the external terminals 51, 61, the gasket 70, and the insulator 80. For example, the internal terminals 55, 65, the external terminals 51, 61, the gasket 70, and the insulator 80 may have an appropriate structure depending on the structure of the electrode assembly 20 housed therein. Furthermore, one of the positive electrode terminal 50 and the negative electrode terminal 60 may be provided with a mechanism (current interrupt device (CID)) that interrupts current when internal pressure increases due to internal gas generation during overcharge.

[0034] The lithium-ion secondary battery 10 includes a battery case, terminals, an electrode assembly, and an electrolyte. The lithium-ion secondary battery 10 contains various metals, such as lithium, cobalt, manganese, nickel, copper, and aluminum. With the advancement of vehicle electrification, it is expected that a large amount of electricity storage devices such as the lithium-ion secondary battery 10 will be discarded. The electrode assembly in the lithium-ion secondary battery 10 contains a large amount of the above-mentioned metals. In particular, the electrode material contained in the electrode assembly contains rare metals such as lithium and cobalt. The electrode material is in the form of a composite material mixed with a conductive material and a binder, as described above, and is supported (adhered) to a current collector (metal foil) by the binder.

[0035] 4 is a flow diagram of a method for recovering an electrode material. The method for recovering an electrode material disclosed herein includes a preparation step S1, a dissolution step S2, and a separation step S3. As a method for manufacturing a recycled electricity storage device, the method further includes a recovery step S4 and a construction step S5.

[0036] <Preparation process S1> In the preparation step S1, for example, an electrode assembly 20 is prepared. The electrode assembly 20 prepared in the preparation step S1 includes a positive electrode current collector 21a, a positive electrode active material layer 21b formed on the positive electrode current collector 21a, a negative electrode current collector 22a, and a negative electrode active material layer 22b formed on the negative electrode current collector 22a. Here, the positive electrode current collector 21a may be aluminum or an aluminum alloy, and the negative electrode current collector 22a may be copper or a copper alloy. In the preparation step S1, an electrode sheet may be prepared. The electrode sheet may be a positive electrode sheet 21 including a positive electrode current collector 21a and a positive electrode active material layer 21b formed on the positive electrode current collector 21a. The electrode sheet may be a positive electrode sheet 21 including a negative electrode current collector 22a and a negative electrode active material layer 22b formed on the negative electrode current collector 22a. Here, the positive electrode active material layer 21b contains positive electrode active material particles. The negative electrode active material layer 22b contains negative electrode active material particles.

[0037] The preparation step S1 may include removing the electrode assembly 20 from an electricity storage device 10 having a battery case 41 that houses the electrode assembly 20. FIG. 5 is a flow diagram showing a step of removing the electrode assembly 20 from a lithium-ion secondary battery 10. (A) in FIG. 5 shows a lithium-ion secondary battery 10 as an electricity storage device. The lithium-ion secondary battery 10 may be, for example, a used lithium-ion secondary battery 10 collected from an electric vehicle. (B) and (C) in FIG. 5 show a step of removing the electrode assembly 20 from the lithium-ion secondary battery 10. As shown in FIG. 5, the electrode assembly 20 may be, for example, obtained by cutting the battery case 41 and separating it from the sealing plate 41b. In the step of removing the electrode assembly 20 from the lithium-ion secondary battery 10, the battery case 41 may be cut and the electrode assembly 20 may be removed. Cutting the battery case 41 may be achieved, for example, by cutting using a water jet. The water jet can smoothly cut the battery case 41 and terminal parts made of thin aluminum or copper. It also produces little cutting debris, and any debris that does occur can be collected with water. Even if a fire breaks out using the water jet, the fire can be quickly extinguished by immersing the battery case 41 in a water tank, allowing the battery case 41 to be cut safely.

[0038] In (B) of FIG. 5, the top surface portion and the bottom surface portion 42 of the battery case 41 of the lithium-ion secondary battery 10, to which the sealing plate 41b is joined, may be separated. At this time, the terminal components (internal terminals 55, 65 in the embodiment shown in FIG. 2) connecting the sealing plate 41b and the electrode assembly 20 may be cut, and the electrode assembly 20 may be separated from the battery case 41. For example, the top surface portion and the bottom surface portion 42 may be realized by water jet cutting, as described above. Once the top surface portion and the bottom surface portion 42 are cut from the battery case 41, as shown in (B), the electrode assembly 20 is obtained in a state where it is fitted into the cylindrical side surface of the battery case 41, which is composed of a pair of wide side surfaces 43, 44 and a pair of narrow side surfaces 45, 46. Then, as shown in (C), the electrode assembly 20 may be pushed out from the cylindrical side surface of the battery case 41. According to this method, the electrode assembly 20 does not fall apart, and is removed in a state in which the positive electrode sheet 21, the first separator sheet 31, the negative electrode sheet 22, and the second separator sheet 32 ​​are integrated together. In this way, the electrode assembly 20 is preferably prepared in a state in which the positive electrode sheet 21, the first separator sheet 31, the negative electrode sheet 22, and the second separator sheet 32 ​​are integrated together.

[0039] In this way, the electrode assembly 20 can be smoothly removed by cutting the top and bottom surfaces of the battery case 41 and the terminals connecting the electrode assembly 20 to the battery case 41 and pushing the electrode assembly 20 out from the cylindrical side circumferential surface. In the embodiment shown in FIG. 5, the battery case 41 is a rectangular case, but even when a cylindrical case is used, the electrode assembly 20 can be removed by cutting the case and terminals. The same applies when a bag-shaped laminate film is used as the battery case 41, and the electrode assembly 20 can be removed by cutting the laminate film and terminals. In this embodiment, the electrode assembly 20 is a wound electrode assembly, and is obtained in a state where a strip-shaped electrode sheet is wound together with a separator.

[0040] FIG. 5(D) shows a step in which the electrode sheets 21 and 22 are separated from the electrode assembly 20. In the preparation step S1, electrode sheets may be prepared as needed. When electrode sheets are prepared in the preparation step S1, the electrode assembly 20 may be separated into the positive electrode sheet 21, the negative electrode sheet 22, and the separators 31 and 32, as shown in FIG. 5(D), to prepare the positive electrode sheet 21 and the negative electrode sheet 22. When the electrode assembly 20 is a wound electrode assembly, the positive electrode sheet 21 and the negative electrode sheet 22 may be separated by unwinding the electrode assembly. Even when the electrode assembly 20 is separated into the positive electrode sheet 21 and the negative electrode sheet 22, the electrode material to be recovered is contained in the electrode active material layer and can be handled in a state where it is collected on the current collector. This improves workability. Furthermore, because the separators 31 and 32 are separated, processing after the dissolution step is also simplified.

[0041] The electrode body 20 may be a laminated electrode body. When the electrode body 20 is a laminated electrode body, the positive electrode current collectors 21a of the multiple positive electrode sheets 21 are grouped together and joined to the positive electrode terminal 50. Furthermore, the negative electrode current collectors 22a of the multiple negative electrode sheets 22 are grouped together and joined to the negative electrode terminal 60. Therefore, in a laminated electrode body, the sheet group of positive electrode sheets 21 joined to the positive electrode terminal 50 and the sheet group of negative electrode sheets 22 joined to the negative electrode terminal 60 can be separated from each other in a grouped state.

[0042] In this way, in the preparation step S1, an electrode body or an electrode sheet including an electrode active material layer formed on a current collector may be prepared.

[0043] <Crushing process S1a> After the preparation step S1 and before the dissolving step S2, a crushing step may be included in which the electrode body 20 or the electrode sheets 21, 22 are crushed. In this case, the electrode body 20 or the electrode sheets 21, 22 may be cut to the required size using a water jet. Crushing the electrode body 20 or the electrode sheets 21, 22 makes it easier for the etching solution to spread throughout, which is expected to speed up the processing in the dissolving step.

[0044] <Dissolution process S2> The dissolving step S2 is a step of immersing the electrode assembly 20 or electrode sheets 21, 22 prepared in the preparing step S1 in an etching solution that dissolves the current collector. Here, a liquid capable of dissolving the current collector of the electrode assembly or electrode sheet is preferably used as the etching solution. The inventors have found that, for example, when the positive electrode current collector is made of aluminum or an aluminum alloy and the negative electrode current collector is made of copper or a copper alloy, lithium hydroxide (LiOH), sodium hydroxide (NaOH), ferric chloride solution (FeCl3), phosphoric acid, hydrochloric acid, hydrobromic acid, hydrofluoric acid, nitric acid, hydroiodic acid, ammonia water, etc. may be used as the etching solution. To accelerate the reaction, acids may be mixed together, alkalis may be mixed together, or hydrogen peroxide may be added as an oxidation accelerator. The inventors have found that lithium hydroxide, sodium hydroxide, and ferric chloride solution are preferred from the viewpoints of functionality, availability, and relative safety. Among these, sodium hydroxide does not readily dissolve some of the metals in the positive electrode active material particles, allowing the quality of the recovered positive electrode active material particles to be maintained at a high level. According to the inventor's findings, the use of lithium hydroxide or sodium hydroxide allows for approximately 95% recovery of the positive electrode active material particles. The etching solution may be any one of lithium hydroxide (LiOH), sodium hydroxide (NaOH), ferric chloride solution (FeCl3), phosphoric acid, hydrochloric acid, hydrobromic acid, hydrofluoric acid, nitric acid, hydroiodic acid, and aqueous ammonia, or a mixture thereof. The etching solution may also contain desired additives.

[0045] Lithium hydroxide, sodium hydroxide, and ferric chloride solutions dissolve aluminum and copper well. Therefore, they can dissolve the positive electrode current collector 21a made of aluminum or an aluminum alloy and the negative electrode current collector 22a made of copper or a copper alloy. When the positive electrode current collector 21a or the negative electrode current collector 22a dissolves, the positive electrode active material layer 21b or the negative electrode active material layer 22b loses its shape. The positive electrode active material particles and the negative electrode active material particles remain. In the dissolution step S2, when the electrode assembly 20 is immersed in an etching solution, the positive electrode active material particles, the negative electrode active material particles, and the separators 31 and 32 contained in the electrode assembly 20 remain undissolved in the etching solution. In the dissolution step, the temperature is preferably adjusted to an appropriate level to promote the reaction of the etching solution. For example, when NaOH is used as the etching solution, the temperature is preferably adjusted to approximately 90°C. Furthermore, in the dissolution step, the etching solution is appropriately stirred to increase the reaction rate. In the dissolution process, the etching solution should be used at an appropriate concentration so as to exhibit the required performance. The temperature and concentration of the etching solution should be set appropriately by conducting tests in advance.

[0046] According to the inventor's findings, in the dissolving step, the positive electrode sheet 21 and the negative electrode sheet 22 are preferably immersed in an etching solution while being separated in advance. In this case, the positive electrode active material particles contained in the positive electrode sheet 21 remain in the etching solution after the positive electrode sheet 21 is immersed. Furthermore, the negative electrode active material particles remain in the etching solution after the negative electrode sheet 22 is immersed. In this case, the positive electrode sheet 21 and the negative electrode sheet 22 are preferably prepared in a separated state in the preparation step. In the dissolving step S2, an etching solution that can dissolve the positive electrode current collector 21a but does not easily dissolve the positive electrode active material particles is preferably selected according to the positive electrode current collector 21a and the positive electrode active material particles of the positive electrode sheet 21. Furthermore, an etching solution that can dissolve the negative electrode current collector 22a but does not easily dissolve the negative electrode active material particles is preferably selected according to the negative electrode current collector 22a and the negative electrode active material particles of the negative electrode sheet 22. In this way, by immersing the positive electrode sheet 21 and the negative electrode sheet 22 in the etching solution while they are separated, it is possible to select an appropriate etching solution for each. Furthermore, because the positive electrode active material particles and the negative electrode active material particles are separated, the recovery rate of the active material particles in the subsequent process is improved. For example, when the positive electrode sheet 21 and the negative electrode sheet 22 are separated in advance, lithium hydroxide or sodium hydroxide is preferably used as the etching solution for etching the positive electrode current collector 21a of the positive electrode sheet 21.

[0047] <Separation process S3> The separation step S3 is a step of separating a precipitate containing materials constituting the active material layer from the etching solution in which the current collector has been dissolved. For example, when the electrode body 20 is dissolved in the etching solution in the dissolution step S2, the positive electrode active material particles, the negative electrode active material particles, and the separators 31 and 32 contained in the electrode body 20 remain without dissolving in the etching solution. In the separation step S3, for example, it is preferable to separate a precipitate containing the positive electrode active material particles and the negative electrode active material particles from the etching solution recovered in the dissolution step S2.

[0048] The precipitate may be separated by, for example, filtration. When the positive electrode sheet 21 and the negative electrode sheet 22 are immersed in the etching solution while separated, an etching solution containing the positive electrode active material particles remaining dissolved therein and an etching solution containing the negative electrode active material particles remaining dissolved therein are obtained. In this case, in the separation step, the precipitate containing the positive electrode active material particles may be separated from the etching solution containing the positive electrode active material particles remaining dissolved therein. Furthermore, the precipitate containing the negative electrode active material particles may be separated from the etching solution containing the negative electrode active material particles remaining dissolved therein.

[0049] <Recovery process S4> This is a process for recovering an electrode material containing at least one of a positive electrode active material and a negative electrode active material from the precipitate. For example, the separated precipitate can be further dried and the binder can be burned off to obtain positive electrode active material particles and negative electrode active material particles. The positive electrode active material particles and negative electrode active material particles may be further separated into particle agglomerates by crushing and separating them based on size, specific gravity, etc. Note that the more stages of classification are performed, the higher the recovery rate can be. The precipitate can be dried, for example, using a vacuum dryer. The drying conditions should be set so that the resin material used as the binder melts and disappears, for example, by drying at 180°C for approximately 120 minutes while vacuuming. According to the inventor's findings, this process can produce a dry powder with an average particle size of approximately 2.0 mm. This can be further crushed to obtain a powder with particles of 15 μm or less.

[0050] When the electrode assembly 20 including the positive electrode sheet 21 and the negative electrode sheet 22 is dissolved together, the dried powder contains positive electrode active material particles (lithium transition metal composite material) and negative electrode active material particles (graphite). Of these, the positive electrode active material particles (lithium transition metal composite material) have a higher specific gravity than the negative electrode active material particles (graphite), and therefore can be separated using a classifier based on the difference in specific gravity.

[0051] Furthermore, if the positive electrode sheet 21 and the negative electrode sheet 22 are separated in advance and dissolved in the etching solution, the process of separating the positive electrode active material particles and the negative electrode active material particles becomes unnecessary or simple, improving the recovery rate of the positive electrode active material particles and the negative electrode active material particles. Furthermore, the aluminum dissolved in the etching solution can be precipitated as, for example, aluminum hydroxide, regenerated, and reused for electrode terminal components, etc. The Bayer process, which is a highly reliable and economical alumina production method, can be used to precipitate aluminum. The copper dissolved in the etching solution can be regenerated by electrolysis and reused for electrode terminal components, etc.

[0052] The recovered positive electrode active material particles may contain dissolved Li when dissolved in an etching solution. Therefore, it is recommended to mix a predetermined amount of LiCO3 or the like with the particles, stir the mixture, and then bake it. The baking conditions are, for example, 850°C and approximately 40 minutes. This allows the recovered positive electrode active material particles to be regenerated as a positive electrode active material.

[0053] <Construction process S5> The electrode materials, such as the positive electrode active material particles and the negative electrode active material particles, recovered in the separation process can be recycled and can be used as materials for constructing an electricity storage device. The method for manufacturing a recycled electricity storage device disclosed herein preferably includes a construction process for constructing an electricity storage device using the electrode materials. In this way, recycling of the electrode materials is expected to make effective use of resources in electricity storage devices and reduce material costs.

[0054] As described above, the electrode material recovery method disclosed herein includes a preparation step S1, a dissolution step S2, and a separation step S3. In the preparation step S1, an electrode assembly 20 or an electrode sheet 21, 22 including current collectors 21a, 22a and electrode active material layers 21b, 22b formed on the current collectors 21a, 22a is prepared. In the dissolution step S2, the electrode assembly 20 or the electrode sheet 21, 22 is immersed in an etching solution. The etching solution is preferably a liquid that dissolves the current collectors 21a, 22a. The etching solution is preferably a liquid that dissolves the current collectors 21a, 22a of the electrode assembly 20 or the electrode sheet 21, 22 but does not dissolve the electrode active material contained in the electrode active material layers 21b, 22b. In this case, in the dissolution step S2, the electrode assembly 20 or the electrode sheet 21, 22 is immersed in the etching solution to dissolve the current collectors 21a, 22a, leaving the electrode material in the etching solution. In this case, the etching solution only needs to dissolve the current collectors 21a and 22a, compared to when the entire battery is scrapped and immersed in the etching solution, so the etching process proceeds more quickly and the recovery rate of the electrode material is improved.

[0055] More preferably, the electrode body 20 is disassembled into a positive electrode sheet 21 and a negative electrode sheet 22, and the positive electrode sheet 21 and the negative electrode sheet 22 are separated. Next, the positive electrode sheet 21 and the negative electrode sheet 22 are individually crushed. The finer the crushing, the shorter the processing time for the dissolution step S2. Next, the crushed electrode sheets are immersed in an etching solution to dissolve the current collector. The precipitate is then recovered (filtered), dried, pulverized, and classified. By separating and processing the positive electrode sheet 21 and the negative electrode sheet 22 in this manner, the recovery rate of the positive electrode active material particles and the negative electrode active material particles can be improved. According to the inventor's findings, it is possible to achieve a recovery rate of the electrode material of, for example, 95% or more.

[0056] The invention disclosed herein has been described in various ways. Unless otherwise specified, the embodiments described herein do not limit the present invention. Furthermore, the embodiments of the invention disclosed herein can be modified in various ways, and each component and each process described herein can be omitted or combined as appropriate, unless a particular problem arises.

[0057] As described above, this specification includes the disclosures set forth in the following sections.

[0058] Section 1: a preparation step of preparing an electrode body or an electrode sheet including a current collector and an electrode active material layer formed on the current collector and containing an electrode active material; a dissolving step of immersing the electrode body or the electrode sheet in an etching solution that dissolves the current collector; a separation step of separating a precipitate containing the electrode active material from the etching solution in which the current collector has been dissolved; A method for recovering an electrode material, comprising:

[0059] Section 2: In the preparing step, an electrode sheet is prepared, the electrode sheet is a positive electrode sheet having a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector and containing a positive electrode active material, In the dissolving step, an etching solution that dissolves the positive electrode current collector is used, In the separation step, a precipitate containing the positive electrode active material is separated from the etching solution in which the positive electrode current collector has been dissolved. Item 1. A method for recovering an electrode material.

[0060] Section 3: Item 3. The method for recovering an electrode material according to Item 2, wherein the positive electrode current collector is aluminum or an aluminum alloy.

[0061] Section 4: In the preparing step, an electrode sheet is prepared, the electrode sheet is a negative electrode sheet having a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector and containing a negative electrode active material, In the dissolving step, an etching solution that dissolves the negative electrode current collector is used, In the separation step, a precipitate containing the negative electrode active material is separated from the etching solution in which the negative electrode current collector has been dissolved. Item 1. A method for recovering an electrode material.

[0062] Section 5: Item 5. The method for recovering an electrode material according to Item 4, wherein the negative electrode current collector is copper or a copper alloy.

[0063] Item 6: In the preparing step, an electrode body is prepared, The electrode body is a positive electrode current collector; a positive electrode active material layer formed on the positive electrode current collector and containing a positive electrode active material; a negative electrode current collector; a negative electrode active material layer formed on the negative electrode current collector and containing a negative electrode active material; It has In the dissolving step, an etching solution that dissolves the electrode body, the positive electrode current collector, and the negative electrode current collector is used, In the separation step, a precipitate containing the positive electrode active material and the negative electrode active material is separated from the etching solution in which the positive electrode current collector and the negative electrode current collector have been dissolved. Item 1. A method for recovering an electrode material.

[0064] Section 7: Item 7. The method for recovering an electrode material according to Item 6, wherein the positive electrode current collector is aluminum or an aluminum alloy, and the negative electrode current collector is copper or a copper alloy.

[0065] Section 8: 8. The method for recovering an electrode material according to any one of items 1 to 7, wherein the etching solution is at least one of lithium hydroxide and an aqueous solution of sodium hydroxide.

[0066] Section 9: 8. The method for recovering an electrode material according to any one of items 1 to 7, wherein the etching solution is an aqueous solution of iron chloride.

[0067] Section 10: 7. The electrode material recovery method according to claim 6, wherein the preparing step includes removing the electrode assembly from an electricity storage device having a case that houses the electrode assembly.

[0068] Section 11: The preparing step includes: removing the electrode assembly from an electricity storage device having a case that houses the electrode assembly; further comprising separating the positive electrode sheet from the electrode assembly. Item 2. A method for recovering an electrode material.

[0069] Section 12: The preparing step includes: removing the electrode assembly from an electricity storage device having a battery case that houses the electrode assembly; further comprising separating the negative electrode sheet from the electrode assembly. Item 4. The method for recovering electrode materials.

[0070] Section 13: the battery case has an opening, and a lid that covers the opening and has an electrode terminal attached thereto, the electrode terminal being partly connected to the electrode body inside the battery case; a bottom plate facing the lid; Equipped with The preparing step includes: forming a pair of openings by separating the lid and the bottom plate from the battery case; pushing the electrode body from one of the pair of openings toward the other, and removing the electrode body from the battery case; Item 13. The method for recovering an electrode material according to any one of items 10 to 12, comprising:

[0071] Section 14: Item 14. The electrode material recovery method according to Item 13, wherein in the preparing step, the lid and the bottom plate are separated from the battery case by a water jet.

[0072] Section 15: Item 15. The method for recovering an electrode material according to any one of items 1 to 14, further comprising a crushing step of crushing the electrode body or the electrode sheet after the preparation step and before the dissolution step.

[0073] Section 16: a preparation step of preparing an electrode body or an electrode sheet including a current collector and an electrode active material layer formed on the current collector and containing an electrode active material; a dissolving step of immersing the electrode body or the electrode sheet in an etching solution that dissolves the current collector; a separation step of separating a precipitate containing the electrode active material from the etching solution in which the current collector has been dissolved; a recovery step of recovering an electrode material containing at least one of the positive electrode active material and the negative electrode active material from the precipitate; a construction step of constructing an electricity storage device using the electrode material; A method for manufacturing a recycled electricity storage device, comprising: [Explanation of symbols]

[0074] 10 Lithium-ion secondary battery (energy storage device) 20 Electrode body 21 Positive electrode sheet (positive electrode element, electrode sheet) 21a Positive electrode current collector foil (positive electrode current collector, current collector) 21a1 Unformed part 21a1) Unformed part 21b Positive electrode active material layer (electrode active material layer) 21p positive electrode protective layer 21t Positive electrode tab 22 negative element 22 negative electrode sheet (negative electrode element, electrode sheet) 22a Negative electrode current collector foil (negative electrode current collector, current collector) 22a1 Unformed part 22b Negative electrode active material layer (electrode active material layer) 22t negative electrode tab 31, 32 Separator sheet (separator) 41 Battery case 41a Case body 41a1 opening 41b Sealing plate 41b1 Liquid injection hole 41b2 Sealing member 41b3 Safety valve 42 Bottom part 43,44 Wide surface section 45,46 Narrow side part 50 Positive terminal 51 External terminal 55 Internal terminal 60 Negative terminal 61 External terminal 65 Internal terminal 70 Gasket 80 insulator S1 Preparation process S2 Melting process S21a Crushing process S3 separation process S4 Recovery process S5 construction process WL winding shaft

Claims

1. A method for manufacturing a battery comprising: preparing an electrode assembly including a positive electrode current collector, a positive electrode active material layer formed on the positive electrode current collector and containing a positive electrode active material, a negative electrode current collector, and a negative electrode active material layer formed on the negative electrode current collector and containing a negative electrode active material; a dissolving step of immersing the electrode body in an etching solution that dissolves the positive electrode current collector and the negative electrode current collector; a separation step of separating a precipitate containing the positive electrode active material and the negative electrode active material from the etching solution in which the positive electrode current collector and the negative electrode current collector have been dissolved; a recovery step of recovering an electrode material including the positive electrode current collector and the negative electrode current collector from the precipitate; Including, The recovery method for an electrode material includes drying the separated precipitate, crushing and classifying particle agglomerates, and separating them into positive electrode active material particles and negative electrode active material particles based on the difference in specific gravity.

2. 2. The method for recovering an electrode material according to claim 1, wherein the positive electrode current collector is made of aluminum or an aluminum alloy, and the negative electrode current collector is made of copper or a copper alloy.

3. 2. The method for recovering an electrode material according to claim 1, wherein the etching solution is at least one of lithium hydroxide and an aqueous solution of sodium hydroxide.

4. 2. The method for recovering an electrode material according to claim 1, wherein the etching solution is an aqueous solution of iron chloride.

5. The method for recovering an electrode material according to claim 1 , wherein the preparing step includes removing the electrode assembly from an electricity storage device having a battery case that houses the electrode assembly.

6. the battery case has an opening, and a lid that covers the opening and has an electrode terminal attached thereto, the electrode terminal being partly connected to the electrode body inside the battery case; a bottom plate facing the lid; Equipped with The preparing step includes: forming a pair of openings by separating the lid and the bottom plate from the battery case; pushing the electrode body from one of the pair of openings toward the other, and removing the electrode body from the battery case in a state where the lid and the bottom plate are separated; The method for recovering an electrode material according to claim 5, comprising:

7. The method for recovering an electrode material according to claim 6 , wherein the preparing step includes separating the lid and the bottom plate from the battery case by a water jet.

8. The method for recovering an electrode material according to claim 1 , further comprising a crushing step of crushing the electrode body after the preparing step and before the dissolving step.

9. A method comprising the steps of: a preparation step, a dissolution step, a separation step, and a recovery step according to any one of claims 1 to 8; a construction step of constructing an electricity storage device using the electrode material recovered in the recovery step; A method for manufacturing a recycled electricity storage device, comprising:

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