Stripping method and stripping device for positive electrode current collector and positive electrode composite material

Abstract

The invention provides a stripping method and stripping device for a positive electrode current collector and a positive electrode composite material, which can effectively recover the positive electrode composite material. A method for separating a positive electrode current collector and a positive electrode composite material from a positive electrode current collector, in which induction heating is performed on the positive electrode current collector to dissolve or vaporize a binder of the positive electrode composite material bonded to the positive electrode current collector.

Description

Technical Field

[0001] The invention relates to a stripping method and a stripping device for a positive electrode current collector and a positive electrode composite material. Background Art

[0002] Lithium-ion batteries and all-solid-state batteries have laminated electrodes consisting of positive and negative plates stacked with a separator. The positive electrode composite material of these batteries uses a ternary positive electrode material (NCM) composed of nickel, cobalt, and manganese. When batteries are discarded, it is desirable to recover valuable metals such as NCM. The positive electrode composite material is bonded to the aluminum material serving as the positive electrode current collector using a binder contained in the positive electrode composite material.

[0003] Conventionally, there is known a technique in which cut pieces of a positive electrode plate made of aluminum and a positive electrode composite material are placed in water, and electric pulse discharge is performed in the water to generate shock waves, thereby breaking the positive electrode plate and separating the different raw materials (for example, see Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-086495 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, if the aluminum material serving as the positive electrode current collector is separated from the positive electrode composite material by crushing the aluminum material, aluminum contamination increases during the recovery of valuable metals.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a stripping method and a stripping device capable of efficiently recovering a positive electrode composite material.

[0010] Means for solving problems

[0011] The method for peeling a positive electrode current collector and a positive electrode composite material disclosed herein peels the positive electrode composite material from the positive electrode current collector, wherein the positive electrode current collector is induction heated to dissolve or vaporize a binder of the positive electrode composite material adhered to the positive electrode current collector.

[0012] In addition, the stripping device for the positive electrode collector and the positive electrode composite material disclosed in the present invention strips the positive electrode composite material from the positive electrode collector, wherein the stripping device comprises: a container for carrying the stack of the positive electrode collector and the positive electrode composite material; and a magnetic field generating unit, which is arranged outside the container and generates induction heating on the positive electrode collector.

[0013] Effects of the Invention

[0014] The positive electrode composite material can be recovered while suppressing the breakage of the aluminum material. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a diagram schematically showing a target battery to which the battery processing method of the present invention can be applied.

[0016] Figure 2 It is a cross-sectional view schematically showing a device for separating a positive electrode current collector and a positive electrode composite material.

[0017] Figure 3 It is a schematic diagram explaining the magnetic field generating unit and the magnetic field.

[0018] Figure 4 yes Figure 3 A-A' cross-sectional view.

[0019] Figure 5 This is a flowchart showing the steps of a method for separating a positive electrode current collector and a positive electrode composite material.

[0020] Figure 6 Schematic diagram illustrating the state of the positive electrode plate being inductively heated.

[0021] Figure 7 This is a schematic diagram illustrating the state of the inductively heated positive electrode plate in the second embodiment.

[0022] Figure 8 This is a schematic diagram illustrating a magnetic field generating unit and a magnetic field in a third embodiment.

[0023] Description of reference numerals:

[0024] 10…Target battery, 11…Positive electrode plate, 12…Negative electrode plate, 13…Separator, 21…Laminated electrode, 22…Laminate, 23A, 23B…Collector tabs, 31…Positive electrode current collector, 32…Positive electrode composite material, 41…Negative electrode current collector, 42…Negative electrode composite material, 101…Peeling device, 103, 203…Magnetic field generating unit, 105…Device body, 107…Wire, 109, 209…Iron core (magnetic material), 111…Power supply device, 113…Wiring, 115…Support, 115A…Support, 120…Peeling sheet, B…Magnetic field, C1, C2, C3, C4, C5…State, D…Eddy current DETAILED DESCRIPTION

[0025] (Implementation Method 1)

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0027] [1. Structure of the target battery]

[0028] Figure 1 This figure illustrates the structure of a target battery 10, an example of a battery to which the present disclosure is applicable, and schematically shows a cross-section of the target battery 10. The target battery 10 is a secondary battery capable of both charge and discharge. The target battery 10 described in this embodiment is a laminated battery in which battery materials are enclosed in a laminate 22, and has an overall flat plate shape. The target battery 10 can be categorized as a pouch-type battery, a laminate-type battery cell, a pouch-type battery cell, a lithium-ion battery cell, or a battery module.

[0029] The target battery 10 is a secondary battery known as a lithium-ion battery, which has attracted attention as a high-energy-density storage device. Examples of positive electrode active materials for lithium-ion batteries include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, and lithium iron phosphate. In addition, examples of positive electrode active materials include ternary positive electrode materials (NCMs) containing nickel, cobalt, and manganese. Examples of negative electrode active materials for lithium-ion batteries include carbon-based materials. Furthermore, all-solid-state batteries using solid electrolytes as the electrolyte for lithium-ion batteries are known.

[0030] Nickel, cobalt, and manganese, which are used as positive electrode active materials in lithium-ion batteries, all-solid-state batteries, and the like, are known as valuable metals, and their recovery from used batteries is sought.

[0031] like Figure 1 As shown, the target battery 10 has a structure in which a stacked electrode 21 is housed in a laminate 22. The laminate 22 is a laminate film having a base material made of a metal material such as aluminum alloy or stainless steel. The laminate 22 functions as a sealant that seals the outer casing of the target battery 10 and the stacked electrode 21.

[0032] The target battery 10 of this embodiment has a flat plate shape formed by laminating two laminates 22 . A pair of collector tabs 23A and 23B for extracting power from the target battery 10 penetrates the outer shell and is exposed from the end of the target battery 10 .

[0033] The laminated electrode 21 is a multilayer structure composed of positive plates 11 and negative plates 12, with separators 13 disposed between each of the positive plates 11 and negative plates 12. The separators 13 are disposed between the positive plates 11 and negative plates 12 to prevent short circuits between the positive plates 11 and negative plates 12.

[0034] The positive electrode plates 11 and the negative electrode plates 12 are alternately arranged, and one positive electrode plate 11 and one negative electrode plate 12 facing each other constitute one electrode plate pair. A stacked electrode 21 is formed by stacking a plurality of electrode plate pairs.

[0035] The positive electrode plate 11 includes a rectangular plate-shaped positive electrode current collector 31, with a positive electrode composite material 32 disposed on both sides of the positive electrode current collector 31. The positive electrode current collector 31 is an aluminum material formed into a foil or plate shape. The positive electrode composite material 32 includes, for example, a positive electrode active material, a conductive material, a conductive additive, and a binder. The positive electrode plate 11 has a positive terminal 11A extending from an end of the positive electrode plate 11. The positive terminals 11A extending from the multiple positive electrode plates 11 that constitute the stacked electrode 21 are each connected to a collector tab 23A.

[0036] The negative electrode plate 12 includes a rectangular negative electrode current collector 41. A negative electrode composite material 42 is provided on the surface of the negative electrode current collector 41 that faces the positive electrode plate 11. Copper foil, for example, is used for the negative electrode current collector 41. The negative electrode plate 12 includes a negative electrode terminal 12A extending from an end of the negative electrode plate 12. Each of the negative electrode terminals 12A extending from the plurality of negative electrode plates 12 that constitute the stacked electrode 21 is connected to a collector tab 23B.

[0037] The collector tabs 23A and 23B are formed of a thin plate-shaped metal material such as copper or aluminum, and are passed between the two laminated materials 22 to be exposed to the outside.

[0038] If the target battery 10 is a lithium-ion battery, the interior of the laminate 22 is filled with a liquid or gel electrolyte. The electrolyte includes, for example, an electrolyte, a solvent, and additives. Examples of the electrolyte include lithium salts such as lithium hexafluorophosphate (LiPF6). Examples of solvents and additives include carbonates such as ethylene carbonate, dimethyl carbonate, diethyl carbonate, and vinylene carbonate. These are examples; the electrolyte, solvent, and additives can be selected and modified as appropriate.

[0039] When the target battery 10 is an all-solid-state battery, a solid electrolyte is placed inside the laminate 22. Oxide-based electrolytes and sulfide-based electrolytes are known as solid electrolytes, but even all-solid-state batteries using other materials can be applied to the present disclosure. For example, the solid electrolyte of an all-solid-state battery is placed between the positive electrode plate 11 and the negative electrode plate 12 in place of the separator 13. In this case, the solid electrolyte not only functions as an electrolyte but also prevents short circuits between the positive electrode plate 11 and the negative electrode plate 12.

[0040] [2. Peeling device]

[0041] Figure 2 1 is a cross-sectional view schematically showing the peeling device 101 . The peeling device 101 is a device for peeling the positive electrode composite material 32 from the upper surface of the positive electrode current collector 31 . Figure 3 Schematic diagram for explaining the magnetic field generating unit 103 and the magnetic field. Figure 4 yes Figure 3 A-A' cross-sectional view.

[0042] The peeling device 101 includes a device body 105. The device body 105 is placed on a workbench T. The device body 105 includes a support portion 115A midway in the height direction. A container 102 is placed on the support portion 115A. The container 102 is filled with a liquid such as water. The device body 105 and the container 102 are made of glass. The material and shape of the device body 105 and the container 102 are not particularly limited.

[0043] The magnetic field generating unit 103 is arranged in the space below the container 102. The magnetic field generating unit 103 includes an iron core 109. The iron core 109 includes an electric wire 107, and the electric wire 107 is connected to the power supply device 111 via a wiring 113. The electric wire 107 is arranged in a groove formed in the iron core 109 (see Figure 3 and Figure 4 ).

[0044] The iron core 109 is an example of a magnetic body. A magnetic body is a member that strengthens a magnetic field or rectifies the direction of a magnetic field.

[0045] Furthermore, a magnetic field generator 103 is also disposed above the container 102. Although not shown, the lower magnetic field generator 103 is electrically connected to the upper magnetic field generator 103. The magnetic field generator 103 is supported by a support (eg, a clamp) not shown.

[0046] The power supply device 111 includes a transformer and generates an alternating current. It should be noted that the power supply device 111 may also generate a direct current.

[0047] When an alternating current flows through the power supply device 111, a magnetic field B is generated in the vertical direction from the magnetic field generating unit 103. Figure 2 As shown by the arrow, the magnetic field B generated by the magnetic field generating unit 103 acts in the vertical direction. The direction of the magnetic field B switches up and down according to the direction of the AC current.

[0048] More specifically, if Figure 3 As shown in FIG. 1 , according to the so-called Ampere's law, the current flowing through the wire 107 generates a magnetic field B1. The magnetic fields B1 generated by the four wires 107 overlap to generate a magnetic field B2. The magnetic field B2 is generated so as to penetrate the upper and lower magnetic field generating parts 103, and as shown in FIG. Figure 2 As shown, a magnetic field B extends in the vertical direction.

[0049] For a magnetic field generating unit 103, as Figure 4 As shown, the electric wires 107 are arranged so that the currents C1 and C2 flow in parallel and in opposite directions. This strengthens the magnetic field B at the center of the opposing electric wires 107 in one magnetic field generating unit 103. Furthermore, since the magnetic field generating units 103 are arranged so as to overlap one another, the magnetic field B is further strengthened.

[0050] The iron core 109 functions to rectify and intensify the magnetic field at the center of the opposing electric wires 107 in one magnetic field generating unit 103 .

[0051] It should be noted that the upper magnetic field generating portion 103 may also be replaced with only the iron core 109. Even if one side is the magnetic field generating portion 103 and the other side is the iron core 109, the magnetic field generating portion 103 can be replaced with the iron core 109. Figure 2 The magnetic field B is shown.

[0052] In this manner, it is possible to set appropriate strength and direction of the magnetic field during the separation of the positive electrode composite material 32 and the positive electrode current collector 31 , thereby improving the separation efficiency.

[0053] The positive electrode plate 11 to be separated is placed on the bottom of the container 102. The positive electrode plate 11 is separated from the target battery 10 described above.

[0054] [3. Peeling method]

[0055] Next, refer to Figure 5 and Figure 6 , a method for separating the positive electrode composite material 32 and the positive electrode current collector 31 will be described. Figure 5 is a flow chart showing the steps of the peeling method.

[0056] First, the positive electrode plate 11 is placed at the initial position on the bottom of the container 102 (step S1). Figure 6 As shown, the initial position is a position where the magnetic field B generated by the magnetic field generating unit 103 passes through one end of the positive electrode plate 11 in the longitudinal direction.

[0057] Next, the magnetic field generating unit 103 generates a magnetic field B (step S2). In step S2, as shown in FIG. Figure 6 As shown in state C1, when magnetic field B is generated, eddy current D flows through the positive electrode current collector 31 centered on magnetic field B, causing induction heating and raising the temperature of the positive electrode current collector 31. The positive electrode composite material 32 has low electrical conductivity and is therefore not easily induction heated.

[0058] Next, induction heating is continued for a predetermined time (step S3 ).

[0059] Then, the positive electrode plate 11 is moved by a predetermined distance so that the inductively heated portion is shifted to the right (step S4 ). To shift the inductively heated portion, the device body 105 placed on the worktable T can be moved, or the magnetic field generator 103 can be moved.

[0060] exist Figure 6 In state C1, when the induction heating is continued for a specified time, as Figure 6As shown in state C2, the positive electrode composite material 32 of the positive electrode current collector 31 is separated at the induction-heated portion, generating a separation sheet 120. The binder contained in the positive electrode composite material 32 evaporates due to heat, thereby separating the positive electrode composite material 32 from the positive electrode current collector 31.

[0061] The predetermined time is predetermined to be a time sufficient to allow the binder of the positive electrode mixture 32 to dissolve or vaporize, thereby effectively separating the positive electrode mixture 32 from the positive electrode current collector 31 and preventing the positive electrode current collector 31 from being broken.

[0062] The induction heating for a predetermined time is repeated while shifting the position of the positive electrode plate 11 until the positive electrode plate 11 reaches the predetermined position. Figure 6 In state C3, induction heating is performed each time by the eddy current D generated by the magnetic field B. The predetermined interval is predetermined so that the portion where the peeling piece 120 is generated does not overlap with the portion to be induction heated next.

[0063] If the positive electrode plate 11 has not moved to the end position (step S5 : No), the operations of steps S3 and S4 are repeated. The end position is the position where the magnetic field B generated by the magnetic field generator 103 passes through the other end of the positive electrode plate 11 in the longitudinal direction.

[0064] If the actions of steps S3 and S4 are repeated, Figure 6 As shown in state C3 , the positive electrode composite material 32 is peeled from left to right.

[0065] When the positive electrode plate 11 has reached the final position (step S5: Yes), induction heating is continued for a predetermined time (step S6). This vaporizes the binder at the interface between the positive electrode composite material 32 and the positive electrode current collector 31 along the entire longitudinal direction of the positive electrode plate 11, generating a release sheet 120.

[0066] Next, the supply of current by the power supply device 111 is stopped, and the generation of the magnetic field B by the magnetic field generating unit 103 is stopped (step S7 ).

[0067] Finally, the contents of the container 102 are placed on a sieve with a mesh size of several millimeters to separate the positive electrode composite material 32 from the positive electrode current collector 31 (step S8). The positive electrode composite material 32 forms a release sheet 120 and is peeled off from the positive electrode current collector 31, but some of it may remain attached. In this case, the remaining positive electrode composite material 32 is peeled off using tweezers or the like.

[0068] By the above-described operation, the positive electrode composite material 32 can be peeled off without breaking the aluminum material constituting the positive electrode current collector 31 .

[0069] It should be noted that the frequency of the alternating current is relatively short and is set in a manner such that the waveform becomes a pulse waveform. In this way, the cooling effect generated by the water filled in the container 102 can suppress the eddy current D from flowing for a long time, and the positive electrode collector 31 from being overheated and thus breaking the positive electrode collector 31. Assuming that the positive electrode collector 31 is broken, the contamination of aluminum in the recovery of the positive electrode composite material 32 may increase. In addition, since the positive electrode collector 31 is inductively heated by the eddy current flowing through it, when the positive electrode collector 31 is broken and the area through which the eddy current flows is reduced, it may not be possible to fully perform inductive heating.

[0070] In this embodiment, since a pulse current is passed through the magnetic field generating unit 103 by the power supply device 111 , it is possible to suppress aluminum contamination and efficiently vaporize the binder by induction heating.

[0071] It should be noted that the pulse current can appropriately control the output time and output value.

[0072] (Implementation Method 2)

[0073] Next, use Figure 7 Implementation method 2 will be described.

[0074] Figure 7 Schematic diagram showing the positive electrode plate 11 being inductively heated in Embodiment 2. Figure 7 In, with Figure 6 The same configuration is denoted by the same reference numerals, and description thereof will be omitted.

[0075] The peeling device 101 in the second embodiment includes a plurality of Figure 2 The magnetic field generating unit 103 is shown.

[0076] like Figure 7 As shown in state C4, multiple magnetic field generators 103 simultaneously generate magnetic fields B for the positive electrode plate 11 placed in the initial position. The intervals between the magnetic fields B, that is, the intervals between the multiple magnetic field generators 103, are separated to such an extent that they do not affect other adjacent magnetic fields B. Each magnetic field B generates an eddy current D.

[0077] By induction heating of the positive electrode current collector 31 at multiple locations simultaneously, the separation piece 120 is generated at each location.

[0078] Then, if Figure 7 As shown in state C5 , the positive electrode plate 11 is shifted by a predetermined distance, and induction heating is generated in a portion where no separation piece 120 is generated.

[0079] By generating induction heating at multiple locations in this manner, the positive electrode current collector 31 and the positive electrode composite material 32 can be separated in a short time.

[0080] (Implementation Method 3)

[0081] Next, use Figure 8 Implementation method 3 will be described.

[0082] Figure 8 Schematic diagram illustrating the magnetic field generating unit 203 and the magnetic field B2 in the third embodiment. Figure 3 The same configuration is denoted by the same reference numerals, and description thereof will be omitted.

[0083] The magnetic field generating unit 203 in the third embodiment includes the electric wire 107 wound around the iron core 209. The magnetic field generating unit 203 functions as a rod-shaped electromagnet and generates the magnetic field B2. This can further enhance the magnetic field B2.

[0084] [Configurations supported by the above-mentioned embodiments]

[0085] The above-mentioned embodiment supports the following configurations.

[0086] (Configuration 1) A method for separating a positive electrode current collector and a positive electrode composite material, wherein the method comprises induction heating the positive electrode current collector to dissolve or vaporize a binder of the positive electrode composite material adhered to the positive electrode current collector.

[0087] According to Configuration 1, the positive electrode current collector has greater conductivity than the positive electrode composite material, allowing the induction current to flow more easily, thereby selectively heating only the positive electrode current collector. Therefore, the positive electrode composite material can be recovered while suppressing breakage of the positive electrode current collector.

[0088] (Configuration 2) The method for separating a positive electrode current collector and a positive electrode composite material according to Configuration 1, wherein a pulse current is passed through the magnetic field generating unit that generates the induction heating.

[0089] According to Configuration 2, the eddy current generated in the aluminum material does not flow for a long time due to the magnetic field generated by the magnetic field generating unit. Therefore, it is possible to suppress the aluminum material from being broken due to overheating.

[0090] (Configuration 3) The peeling method according to Configuration 1 or 2, wherein the portion where the induction heating occurs is moved.

[0091] According to Configuration 3, the positive electrode composite material can be continuously peeled off with high efficiency.

[0092] (Configuration 4) The method for separating a positive electrode current collector and a positive electrode composite material according to Configuration 1 or 2, wherein induction heating is applied to the positive electrode current collector at a plurality of locations.

[0093] According to Configuration 4, the positive electrode composite material can be peeled off simultaneously at a plurality of locations, and thus the efficiency is high.

[0094] (Composition 5) A device for stripping a positive electrode collector and a positive electrode composite material, which strips the positive electrode composite material from the positive electrode collector, wherein the stripping device comprises: a container on which a stack of the positive electrode collector and the positive electrode composite material is placed; and a magnetic field generating unit, which is arranged outside the container and generates induction heating on the positive electrode collector.

[0095] According to the configuration 5, the same action and effect as the configuration 1 are achieved.

[0096] (Configuration 6) The device for separating a positive electrode current collector and a positive electrode composite material according to Configuration 5, wherein the magnetic field generating portion is arranged on one side of the positive electrode current collector, and the magnetic field generating portion or the magnetic body is arranged on the other side of the positive electrode current collector, with the positive electrode current collector interposed therebetween.

[0097] According to Configuration 6, the magnetic field can be further enhanced.

Claims

1. A method for stripping a positive electrode current collector and a positive electrode composite material, wherein the positive electrode composite material is stripped from the positive electrode current collector, The positive electrode current collector is induction heated to dissolve or vaporize a binder of the positive electrode composite material adhered to the positive electrode current collector.

2. The method for peeling a positive electrode current collector and a positive electrode composite material according to claim 1, wherein: A pulse current is passed through the magnetic field generating portion that generates the induction heating.

3. The method for peeling a positive electrode current collector and a positive electrode composite material according to claim 1 or 2, wherein: The site where the induction heating is generated is moved.

4. The method for peeling a positive electrode current collector and a positive electrode composite material according to claim 1 or 2, wherein: Induction heating is generated at multiple locations on the positive electrode current collector.

5. A device for stripping a positive electrode current collector and a positive electrode composite material, which strips the positive electrode composite material from the positive electrode current collector, wherein: The device for stripping the positive electrode current collector and the positive electrode composite material comprises: a container for placing a stack of the positive electrode current collector and the positive electrode composite material; and The magnetic field generating unit is disposed outside the container and generates induction heating on the positive electrode current collector.

6. The device for separating a positive electrode current collector and a positive electrode composite material according to claim 5, wherein: The magnetic field generating portion is disposed on one side of the positive electrode current collector, and the magnetic field generating portion or the magnetic body is disposed on the other side of the positive electrode current collector, with the positive electrode current collector interposed therebetween.

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