Peeling method for positive electrode current collector and positive electrode mixture, and peeling device

Abstract

To provide a peeling method and device for a positive electrode current collector and a positive electrode mixture that enables effective recovery of the positive electrode mixture.SOLUTION: In a peeling method for a positive electrode current collector and a positive electrode mixture, induction heating is applied to the positive electrode current collector to dissolve or vaporize a binder of the positive electrode mixture adhered to the positive electrode current collector.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for separating a positive electrode current collector from a positive electrode mixture. [Background technology]

[0002] Some lithium-ion batteries and all-solid-state batteries have laminated electrodes in which positive and negative electrodes are stacked with a separator between them. The positive electrode composite in these types of batteries uses a ternary cathode material (NCM) consisting of nickel, cobalt, and manganese. When disposing of batteries, it is desirable to recover valuable metals such as NCM. The positive electrode composite is bonded to an aluminum material serving as a positive electrode current collector by a binder contained in the positive electrode composite. Conventionally, a technique has been known in which a cut piece of a positive electrode plate made of aluminum material and a positive electrode composite is placed in water, and shock waves are generated in the water by an electric pulse discharge, thereby crushing the positive electrode plate and separating the different materials (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-086495 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the aluminum material serving as the positive electrode current collector is separated from the positive electrode composite material by a method that crushes the aluminum material, the amount of aluminum contamination increases at the stage of recovering valuable metals. The present invention has been made in view of the above circumstances, and has an object to provide a stripping method and a stripping device that can effectively recover a positive electrode mixture. [Means for solving the problem]

[0005] The method for peeling a positive electrode current collector and a positive electrode composite according to the present disclosure is a peeling method for peeling a positive electrode composite from a positive electrode current collector, in which induction heating is generated in the positive electrode current collector to dissolve or vaporize the binder of the positive electrode composite adhered to the positive electrode current collector. Furthermore, the peeling device for peeling a positive electrode current collector and a positive electrode composite material according to the present disclosure is a peeling device that peels a positive electrode composite material from a positive electrode current collector, and includes: a container in which a laminate of the positive electrode current collector and the positive electrode composite material is placed; and a magnetic field generating unit that is disposed outside the container and generates induction heating on the positive electrode current collector. [Effects of the Invention]

[0006] The positive electrode mixture can be recovered while suppressing crushing of the aluminum material. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram schematically illustrating a target battery to which the battery treatment method of the present invention can be applied. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a device for separating a positive electrode current collector and a positive electrode composite material. [Figure 3] 3A and 3B are schematic diagrams illustrating a magnetic field generating unit and a magnetic field. [Figure 4] 4 is a cross-sectional view of FIG. 3 along AA'. [Figure 5] 1 is a flowchart showing the steps of a method for separating a positive electrode current collector from a positive electrode composite material. [Figure 6] FIG. 10 is a schematic diagram illustrating the state of an induction-heated positive electrode plate. [Figure 7] 10 is a schematic diagram illustrating the state of an induction-heated positive electrode plate in the second embodiment. FIG. [Figure 8] 10 is a schematic diagram illustrating a magnetic field generating unit and a magnetic field according to the third embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] (Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [1. Target battery configuration] FIG. 1 is a diagram showing the configuration of a target battery 10 as an example of a battery to which the present disclosure is applied, and schematically shows a cross section of the target battery 10. The target battery 10 is a secondary battery capable of charging and discharging. The target battery 10 described in this embodiment is a laminated battery in which battery materials are encapsulated in a laminate material 22, and has an overall flat plate shape. The target battery 10 can be referred to as a pouch-type battery, a laminated battery cell, a pouch-type battery cell, a lithium-ion battery cell, a battery module, or the like.

[0009] The subject battery 10 is a secondary battery known as a lithium-ion battery, which has attracted attention as an electricity storage device with a high energy density. Examples of positive electrode active materials for lithium-ion batteries include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, and lithium iron phosphate. Examples of positive electrode active materials include ternary cathode materials (NCMs) containing nickel, cobalt, and manganese. Examples of negative electrode active materials for lithium-ion batteries include carbon-based materials. All-solid-state batteries, which use a solid electrolyte as the electrolyte for lithium-ion batteries, are also known.

[0010] Nickel, cobalt, and manganese, which are used as positive electrode active materials in lithium-ion batteries and all-solid-state batteries, are known as valuable metals and there is a demand for their recovery from used batteries.

[0011] 1, the target battery 10 has a configuration in which a laminated electrode 21 is housed in a laminate material 22. The laminate material 22 is a laminate film whose base material is a metal material such as an aluminum alloy or stainless steel. The laminate material 22 functions as an exterior body of the target battery 10 and as a seal that seals the laminated electrode 21.

[0012] The target battery 10 of this embodiment has a flat plate shape formed by bonding two sheets of laminate material 22 together, and a pair of current collecting tabs 23A, 23B for extracting power from the target battery 10 penetrate the outer casing and are exposed from the end of the target battery 10.

[0013] The laminated electrode 21 is a multilayer body in which positive electrode plates 11 and negative electrode plates 12 are stacked, and a separator 13 is disposed between each positive electrode plate 11 and negative electrode plate 12. The separator 13 is disposed between the positive electrode plate 11 and the negative electrode plate 12 to prevent a short circuit between the positive electrode plate 11 and the negative electrode plate 12.

[0014] 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.

[0015] The positive electrode plate 11 includes a rectangular plate-shaped positive electrode current collector 31, and a positive electrode composite 32 is provided 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 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 electrode terminal 11A extending from an end of the positive electrode plate 11. The positive electrode terminals 11A extending from the multiple positive electrode plates 11 constituting the stacked electrode 21 are each connected to a current collecting tab 23A.

[0016] 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. The negative electrode current collector 41 is made of, for example, copper foil. The negative electrode plate 12 has a negative electrode terminal 12A that extends from an end of the negative electrode plate 12. The negative electrode terminals 12A that extend from the multiple negative electrode plates 12 that make up the stacked electrode 21 are each connected to a current collecting tab 23B.

[0017] The current collecting tabs 23A and 23B are formed from a thin metal plate such as copper or aluminum, and pass between the two laminate materials 22 and are exposed to the outside.

[0018] If the target battery 10 is a lithium-ion battery, the laminate material 22 is filled with a liquid or gel electrolyte. The electrolyte includes, for example, an electrolyte, a solvent, and an additive. Examples of the electrolyte include lithium salts such as lithium hexafluorophosphate (LiPF6). Examples of the solvent and additive include carbonate esters such as ethylene carbonate, dimethyl carbonate, diethyl carbonate, and vinylene carbonate. These are just some examples, and the electrolyte, solvent, and additive can be selected and changed as appropriate.

[0019] When the target battery 10 is an all-solid-state battery, a solid electrolyte is disposed inside the laminate material 22. Although oxide-based electrolytes and sulfide-based electrolytes are known as solid electrolytes, the present disclosure may also be applicable to all-solid-state batteries using other materials. The solid electrolyte of the all-solid-state battery is disposed, for example, 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-circuiting between the positive electrode plate 11 and the negative electrode plate 12.

[0020] [2. Peeling device] Fig. 2 is a cross-sectional view schematically showing peeling device 101. Peeling device 101 is a device that peels positive electrode composite 32 from the upper surface of positive electrode current collector 31. Fig. 3 is a schematic diagram illustrating magnetic field generating unit 103 and the magnetic field. Fig. 4 is a cross-sectional view taken along line AA' in Fig. 3.

[0021] The peeling device 101 includes an apparatus main body 105. The apparatus main body 105 is placed on a workbench T. The apparatus main body 105 includes a support part 115A at the midpoint in the height direction. A container 102 is placed on the support part 115A, and the container 102 is filled with a liquid such as water. The apparatus main body 105 and the container 102 are made of glass. Note that the material and shape of the apparatus main body 105 and the container 102 are not particularly limited.

[0022] A magnetic field generating unit 103 is disposed 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, which is connected to a power supply device 111 via wiring 113. The electric wire 107 is routed in a groove formed in the iron core 109 (see FIGS. 3 and 4). The iron core 109 is an example of a magnetic material. A magnetic material is a member that strengthens a magnetic field or rectifies the direction of the magnetic field.

[0023] Furthermore, a magnetic field generating unit 103 is also disposed above the container 102. Although not shown in the figure, the lower magnetic field generating unit 103 and the upper magnetic field generating unit 103 are electrically connected. The magnetic field generating unit 103 is supported by a support (e.g., a clamp) not shown.

[0024] The power supply device 111 includes a transformer and generates an alternating current. However, the power supply device 111 may also generate a direct current. When an alternating current is applied by the power supply device 111, a magnetic field B is generated in the vertical direction from the magnetic field generating unit 103. The magnetic field B generated by the magnetic field generating unit 103 acts in the vertical direction, as shown by the arrow in Figure 2. The direction of the magnetic field B switches between up and down depending on the direction of the alternating current.

[0025] More specifically, as shown in Fig. 3, a magnetic field B1 is generated according to Ampere's law by the current flowing through the electric wires 107. The magnetic fields B1 generated from the four electric wires 107 overlap each other to generate a magnetic field B2. The magnetic field B2 is generated so as to penetrate the upper and lower magnetic field generating units 103, and further becomes a magnetic field B extending in the vertical direction as shown in Fig. 2. 4, for one magnetic field generating unit 103, the electric wires 107 are arranged so that the currents C1 and C2 flow in parallel and in opposite directions to each other. 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 each other vertically, the magnetic field B is further strengthened.

[0026] The iron core 109 functions to rectify and strengthen the magnetic field at the center of the opposing electric wires 107 in one magnetic field generating unit 103 . The upper magnetic field generating unit 103 may be replaced simply with only the iron core 109. Even if one is the magnetic field generating unit 103 and the other is the iron core 109, the magnetic field B shown in FIG. In this way, the strength and direction of the magnetic field can be set appropriately for separating positive electrode composite material 32 from positive electrode current collector 31, thereby improving the efficiency of separation.

[0027] The positive electrode plate 11 to be peeled is placed on the bottom of the container 102. The positive electrode plate 11 is in a state separated from the target battery 10 described above.

[0028] [3. Peeling method] 5 and 6, a method for separating positive electrode composite 32 from positive electrode current collector 31 will be described. Fig. 5 is a flowchart showing the procedure of the separation method.

[0029] First, the positive electrode plate 11 is placed at an initial position on the bottom of the container 102 (step S1). The initial position is a position where the magnetic field B generated by the magnetic field generating unit 103 penetrates one end of the positive electrode plate 11 in the longitudinal direction, as shown in FIG.

[0030] Next, magnetic field B is generated by magnetic field generating unit 103 (step S2). In step S2, as shown in state C1 in Fig. 6, when magnetic field B is generated, eddy current D flows in positive electrode current collector 31 around magnetic field B, causing induction heating and increasing the temperature of positive electrode current collector 31. Positive electrode composite 32 has low electrical conductivity and is therefore not easily induction heated.

[0031] Next, induction heating is continued for a predetermined time (step S3). Thereafter, the positive electrode plate 11 is moved by a predetermined distance so that the induction-heated portion is shifted to the right (step S4). When shifting the induction-heated portion, the device main body 105 placed on the workbench T may be moved, or the magnetic field generating unit 103 may be moved.

[0032] When induction heating is continued for a predetermined time in state C1 of Fig. 6 , the positive electrode composite 32 of the positive electrode current collector 31 peels off from the induction heated portion, generating peeled pieces 120, as shown in state C2 of Fig. 6 . The binder contained in the positive electrode composite 32 evaporates due to the heat, and the positive electrode composite 32 and the positive electrode current collector 31 are peeled off. The specified time is predetermined to be a time that can effectively peel the positive electrode mixture 32 from the positive electrode current collector 31 by dissolving or vaporizing the binder of the positive electrode mixture 32, and that does not crush the positive electrode current collector 31.

[0033] Induction heating for a predetermined time is repeated while shifting the position of the positive electrode plate 11 until it reaches state C3 in Fig. 6, and each time it is induction heated by eddy current D generated by magnetic field B. The predetermined interval is determined in advance so that the part where peeled piece 120 has been generated does not overlap with the part to be induction heated next.

[0034] If the positive electrode plate 11 has not been 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 generating unit 103 penetrates the other end of the positive electrode plate 11 in the longitudinal direction.

[0035] By repeating the operations of steps S3 and S4, positive electrode composite material 32 is peeled from left to right as shown in state C3 in FIG.

[0036] If the positive electrode plate 11 has been moved to the end position (step S5: YES), induction heating is continued for a predetermined time (step S6), causing the binder at the interface between the positive electrode composite 32 and the positive electrode current collector 31 to vaporize over the entire longitudinal direction of the positive electrode plate 11, thereby generating peeled pieces 120.

[0037] Next, the supply of current from 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).

[0038] Finally, the content of container 102 is passed through a sieve with meshes of several millimeters to separate positive electrode composite 32 from positive electrode current collector 31 (step S8). Positive electrode composite 32 becomes peeled pieces 120 and is peeled off from positive electrode current collector 31, but some may remain attached. In this case, the remaining positive electrode composite 32 is peeled off with tweezers or the like. By the above operation, positive electrode composite material 11 can be peeled off without crushing the aluminum material that constitutes positive electrode current collector 31.

[0039] The AC frequency is set to be short and the waveform to be a pulse waveform. This, together with the cooling effect of the water filled in the container 102, prevents the eddy current D from flowing for a long time, which would cause the positive current collector 31 to be overheated and shattered. If the positive current collector 31 were to be shattered, there is a risk of increased aluminum contamination during recovery of the positive electrode composite 32. Furthermore, since the positive current collector 31 is induction-heated by the eddy current flowing in it, if the area through which the eddy current flows is reduced due to the positive current collector 31 being shattered, there is a risk of insufficient induction heating. In this embodiment, a pulse current is applied to the magnetic field generating unit 103 by the power supply device 111, so that contamination of aluminum can be suppressed and the binder can be efficiently vaporized by induction heating. The output time and output value of the pulse current can be appropriately controlled.

[0040] (Embodiment 2) Next, the second embodiment will be described with reference to FIG. Fig. 7 is a schematic diagram showing an induction-heated positive electrode plate 11 in embodiment 2. In Fig. 7, the same components as those in Fig. 6 are given the same reference numerals, and the description thereof will be omitted. The delamination device 101 according to the second embodiment includes a plurality of magnetic field generating units 103 shown in FIG. 2 arranged at predetermined intervals in the horizontal direction.

[0041] As shown in state C4 in Figure 7, magnetic fields B are simultaneously generated by multiple magnetic field generating units 103 for the positive electrode plate 11 placed in the initial position. The spacing between the magnetic fields B, i.e., the spacing between the multiple magnetic field generating units 103, is set to a degree that does not affect adjacent magnetic fields B. Each magnetic field B generates an eddy current D.

[0042] By simultaneously inductively heating the positive electrode current collector 31 at a plurality of locations, peeled pieces 120 are generated at each location. Next, as shown in state C5 in FIG. 7, the positive electrode plate 11 is shifted by a predetermined distance, and induction heating is generated in the area where no peeled pieces 120 have formed. In this way, by generating induction heating at a plurality of locations, the positive electrode current collector 31 and the positive electrode composite material 32 can be separated from each other in a short time.

[0043] (Embodiment 3) Next, a third embodiment will be described with reference to FIG. 8 is a schematic diagram illustrating the magnetic field generating unit 203 and the magnetic field B1 according to embodiment 3. The same components as those in FIG. 3 are given the same reference numerals and descriptions thereof will be omitted. The magnetic field generating unit 203 in the third embodiment includes an electric wire 107 wound around an iron core 209. The magnetic field generating unit 203 functions as a rod-shaped electromagnet and generates a magnetic field B1, thereby further strengthening the magnetic field B1.

[0044] [Configuration supported by the above embodiment] The above embodiment supports the following configurations.

[0045] (Configuration 1) A method for peeling a positive electrode composite from a positive electrode current collector, the method comprising generating induction heating on the positive electrode current collector to dissolve or vaporize a binder of the positive electrode composite bonded to the positive electrode current collector. According to the first aspect, the positive electrode current collector has a higher electrical conductivity than the positive electrode composite material, and therefore an induced current flows more easily through the positive electrode current collector, so that only the positive electrode current collector can be selectively induction heated. As a result, the positive electrode composite material can be recovered while suppressing crushing of the positive electrode current collector.

[0046] (Configuration 2) The method for separating the positive electrode current collector and the positive electrode composite according to Configuration 1, wherein a pulse current is passed through a magnetic field generating unit that generates the induction heating. According to configuration 2, the magnetic field generated by the magnetic field generating unit prevents eddy currents from flowing in the aluminum material for a long period of time, thereby preventing the aluminum material from being broken down due to excessive heating.

[0047] (Configuration 3) The peeling method according to Configuration 1 or 2, wherein the location where the induction heating occurs is moved. According to the third aspect, the positive electrode mixture can be peeled off continuously and efficiently.

[0048] (Configuration 4) The method for separating a positive electrode current collector from a positive electrode composite according to Configuration 1 or 2, wherein induction heating is generated at a plurality of locations on the positive electrode current collector. According to the fourth aspect, the positive electrode composite material can be peeled off at multiple locations simultaneously, which is efficient.

[0049] (Configuration 5) A peeling device for peeling a positive electrode composite from a positive electrode current collector, the device comprising: a container in which a laminate of the positive electrode current collector and the positive electrode composite is placed; and a magnetic field generating unit that is disposed outside the container and generates induction heating on the positive electrode current collector. According to the fifth configuration, the same functions and effects as those of the first configuration are achieved.

[0050] (Configuration 6) The device for peeling off a positive electrode current collector and a positive electrode composite according to claim 5, wherein the magnetic field generating unit is disposed on one side of the positive electrode current collector, and the magnetic field generating unit or a magnetic body is disposed on the other side. According to configuration 6, the magnetic field can be further strengthened. [Explanation of symbols]

[0051] 10...target battery, 11...positive electrode plate, 12...negative electrode plate, 13...separator, 21...laminated electrode, 22...laminate material, 22A, 22B...current collecting tab, 31...positive electrode current collector, 32...positive electrode composite, 41...negative electrode current collector, 42...negative electrode composite, 101...peeling device, 103, 203...magnetic field generating unit, 105...container, 107...electric wire, 109, 209...iron core (magnetic material), 111...power supply unit, 113...wiring, 115...support stand, 115A...support part, 120...peeled piece, B...magnetic field, C1, C2, C3, C4, C5...state, D...eddy current.

Claims

1. A method for peeling a positive electrode current collector and a positive electrode composite material, which peels a positive electrode composite material from a positive electrode current collector, comprising: A method for separating a positive electrode current collector and a positive electrode mixture, comprising: generating induction heating on the positive electrode current collector to dissolve or vaporize a binder of the positive electrode mixture adhered to the positive electrode current collector.

2. The method for separating the positive electrode current collector and the positive electrode mixture according to claim 1 , wherein a pulse current is passed through the magnetic field generating unit that generates the induction heating.

3. The method for separating the positive electrode current collector from the positive electrode mixture according to claim 1 or 2, wherein the location where the induction heating occurs is moved.

4. The method for separating a positive electrode current collector from a positive electrode mixture according to claim 1 or 2, wherein induction heating is generated at a plurality of locations on the positive electrode current collector.

5. A peeling device that peels a positive electrode composite from a positive electrode current collector, a container in which a laminate of the positive electrode current collector and the positive electrode composite is placed; a magnetic field generating unit disposed outside the container and configured to generate induction heating on the positive electrode current collector, A device for peeling off the positive electrode current collector and positive electrode composite material.

6. The positive electrode current collector is sandwiched between the magnetic field generating unit and the magnetic field generating unit or the magnetic body. The device for separating a positive electrode current collector and a positive electrode mixture according to claim 5 .

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