Method for recycling electrodes

Abstract

Provided is a method for recovering an electrode that can reduce the number of steps. The method for recovering an electrode according to the present invention includes a peeling step in which an ultrasonic horn having a surface including an irradiation surface on which ultrasonic waves are irradiated, coated with a resin material, is brought into contact with an electrode having a current collector and an electrode composite attached to the current collector, and ultrasonic waves are irradiated from the irradiation surface of the ultrasonic horn, thereby peeling the electrode composite from the current collector. In the peeling step, the resin material as a transmission member is interposed between the ultrasonic horn and the electrode, and ultrasonic waves from the ultrasonic horn are irradiated onto the electrode without using water.

Description

Technical Field

[0001] This invention relates to a method for recovering electrodes. Background Technology

[0002] Patent Document 1 discloses a technique for separating and recycling the positive electrode material (active material and current collector) of a used lithium-ion secondary battery. In this technique, the positive electrode material is heat-treated and then ultrasonically treated in water, thereby separating the positive electrode material and the current collector.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-84681 Summary of the Invention

[0004] However, in Patent Document 1, water is required to function as the medium for transmitting ultrasonic waves. Therefore, ultrasonic treatment of the cathode material is required in water, which necessitates a drying process for the cathode composite material. This increases the number of steps in the recycling process and makes it more complex.

[0005] The present invention was made in view of the above, and its object is to provide an electrode recycling method that can reduce the number of processes.

[0006] The electrode recycling method of the present invention includes a stripping step, wherein an ultrasonic welding head, the surface of which is coated with a resin material including an irradiation surface for irradiating ultrasonic waves, is brought into contact with an electrode having a current collector and an electrode assembly attached to the current collector, and the ultrasonic waves are irradiated from the irradiation surface of the ultrasonic welding head, thereby stripping the electrode assembly from the current collector. In the stripping step, the resin material, which serves as a transmission component, is placed between the ultrasonic welding head and the electrode, and the ultrasonic waves from the ultrasonic welding head are irradiated onto the electrode without the use of water.

[0007] Invention Effects

[0008] According to the present invention, the number of processes can be reduced. Attached Figure Description

[0009] Figure 1 This is a flowchart illustrating the outline of the electrode recovery method according to Embodiment 1 of the present invention.

[0010] Figure 2 This is a diagram showing the schematic structure of the ultrasonic stripping device according to Embodiment 1 of the present invention.

[0011] Figure 3 This is a diagram showing the schematic structure of the ultrasonic stripping device according to Embodiment 2 of the present invention. Detailed Implementation

[0012] Hereinafter, a method for recovering electrodes according to embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, the drawings referenced in the following description are only schematic representations of shapes, sizes, and positional relationships to the extent necessary to understand the content of the present invention. That is, the present invention is not limited to the shapes, sizes, and positional relationships illustrated in the drawings. In addition, the same symbols are used to denote the same parts in the accompanying drawings.

[0013] (Implementation Method 1)

[0014] [Overview of electrode recovery methods]

[0015] First, the method for recovering the electrodes will be explained. Figure 1 This is a flowchart outlining the electrode recycling method. Figure 1 The electrode recycling method described herein is a direct recycling (reuse) method in lithium-ion battery recycling that does not restore the active material to raw materials, but regenerates it. Specifically, the method of separating the electrode coating from the current collector foil is described as a low-cost and highly efficient technique for recycling electrode coatings from high-capacity batteries (coating weight per unit area of ​​PHV or higher) where the electrode coating is thick and easily causes a difference in ultrasonic amplitude between the composite material and the current collector foil. In the electrode recycling method of the present invention, the recycled electrode coating is based on the premise of recycling only either the positive or negative electrode, and the recycled composite material is used either as a single unit or mixed with virgin active material. That is, the electrode coating recycled in the electrode recycling method of the present invention targets the process end material, thus preventing leakage of lithium (Li) and other compositional defects from the active material, and allowing it to be treated as a direct recycled product in the same way as virgin active material.

[0016] like Figure 1 As shown, firstly, the operator performs a recycling process (step S1) on the electrodes of the object to be recycled, which includes the recycling of unrecoverable process end materials, and then performs a screening process (step S2) to separate the electrodes from the workpiece.

[0017] Next, the operator uses an ultrasonic stripping device to perform an ultrasonic stripping process (step S3) to recover the electrode composite material from the electrode. Details of the ultrasonic stripping process will be described later.

[0018] Then, the operator performs an inspection process to check whether metallic foreign objects such as the current collector foil of the ultrasonic welding head or electrode of the ultrasonic stripping device have been mixed in (step S4). In this case, the operator performs a physical property evaluation of the recovered composite material (e.g., composition ICP / TC) and determines the blending ratio that meets the acceptance criteria for new active substances.

[0019] Next, the operator adds the target solvent (in the same composition and amount used in the mixing process) to the recovered coating compound and performs a micronization process using a ball mill (step S5).

[0020] Then, the operator performs a metering process (step S6) to measure and mix the new active material and the direct recycled material obtained through the above process.

[0021] Next, the operator performs a mixing process (step S7) to produce the coating slurry to the same specifications as the usual manufacturing process, and then performs a coating process (step S8) to apply the coating slurry to the new workpiece, thus ending the process.

[0022] Thus, this paper describes a low-cost and highly efficient technique for recycling electrode coatings from high-capacity batteries (coating weight per unit area exceeding PHV) where the electrode coating is thick and prone to differences in ultrasonic amplitude between the composite material and the current collector foil. In the electrode recycling method of this invention, the recycled electrode coating is based on the premise of recycling only either the positive or negative electrode, and the recycled composite material is used either as a single unit or mixed with virgin active material. That is, the electrode coating recycled in the electrode recycling method of this invention targets the process end material, thus preventing leakage of compositional defects such as lithium (Li) from the active material, and allowing it to be treated as a direct recycled product in the same way as virgin active material. Furthermore, since the recycled coating after ultrasonic stripping is not micronized, a micronization process is required in the mixing process or its preceding process. Moreover, for high-capacity battery active materials, the particle size distribution is already wide and the weight per unit area is thick, so even if there is slightly more agglomerate in the direct recycled product, it can prevent any impact on coating performance.

[0023] [Detailed information on the ultrasonic peeling device and ultrasonic peeling process]

[0024] Next, after a general description of the ultrasonic stripping device, the details of the ultrasonic stripping process based on the ultrasonic stripping device will be explained. Figure 2 This is a diagram showing the general structure of an ultrasonic stripping device.

[0025] Figure 2 The ultrasonic stripping device 1 shown includes: an ultrasonic probe 20; a conveying device 30 for conveying the electrode W1; a control device 40 for controlling the drive of the ultrasonic probe 20 and the conveying device 30 respectively; and a recycling mechanism 50 for recycling the electrode composite material stripped from the electrode W1.

[0026] Electrode W1 includes a current collector foil 10 serving as a current collector, and electrode composites 11 and 12 attached to the upper and lower surfaces of the current collector foil 10. Electrode composite 11 is a positive electrode, such as inorganic ceramic. Electrode composite 12 is a negative electrode, such as carbon. For example, electrode W1 is a coated electrode with a thickness of 50 μm.

[0027] The ultrasonic probe 20 has an ultrasonic welding head 21 at its front end, which is configured to scan in a direction opposite to the delivery direction P1 of the electrode W1. The ultrasonic probe 20 is constructed using a movable drive mechanism such as an arm, an ultrasonic oscillator, and a transducer, and transmits ultrasonic vibrations to the ultrasonic welding head 21. The ultrasonic probe 20 causes the ultrasonic welding head 21 to vibrate with an amplitude of 10 μm or more (frequency 40 kHz), more preferably with an amplitude of 20 μm or more (frequency 20 kHz or less). The ultrasonic welding head 21 is coated with a resin material 21a to cover the entire surface, including the irradiation surface (emission surface) from which the ultrasonic waves are irradiated. The resin material 21a is coated in a manner that prevents the ultrasonic welding head 21 from deforming or wearing. That is, the resin material 21a prevents the ultrasonic welding head 21 from being contaminated with metallic foreign matter due to wear. For example, the resin material 21a uses a PEEK material with an elongation of 20% or less and a Rockwell hardness of 120 or more. In order to ensure that the coating thickness of the ultrasonic welding head 21 based on resin material 21a follows the vibration of the ultrasonic emission source without deviation and is transmitted to the electrode W1, the coating thickness is preferably 10 mm or less, and more preferably 1 mm or less. Alternatively, the resin material 21a may not be required to coat the ultrasonic welding head 21, and may be a resin sheet or the like.

[0028] The conveying device 30 conveys the electrode W1 while tilting and fixing it at a predetermined angle. The conveying device 30 is constructed using a winding device or the like.

[0029] The control device 40 is implemented using a processing device, i.e., a processor, with hardware such as a Field Programmable Gate Array (FPGA) or a Central Processing Unit (CPU), and a memory serving as a temporary storage area for the processor. The control device 40 centrally controls the operation of each part of the ultrasonic stripping device 1 according to the program recorded in the memory.

[0030] The recycling facility 50 recycles the electrode composite 11 and electrode composite 12 stripped from the electrode W1.

[0031] [Details of the ultrasonic peeling process]

[0032] Next, the details of the ultrasonic peeling process will be explained. For example... Figure 2As shown, in the ultrasonic stripping process, the ultrasonic probe 20, under the control of the control device 40, scans in a scanning direction opposite to the transport direction of the electrode W1, while simultaneously bringing ultrasonic waves from the irradiation surface of the ultrasonic welding head 21 into contact with and irradiating the entire electrode W1. This process peels the electrode composite 11 (positive electrode) and electrode composite 12 (negative electrode) from the electrode W1, which includes the current collector foil 10 as a current collector. Specifically, the ultrasonic probe 20 brings the ultrasonic welding head 21 into contact with the electrode W1 and irradiates the electrode W1 with ultrasonic waves from the irradiation surface of the ultrasonic welding head 21, thereby peeling the electrode composite 11 and electrode composite 12 from the current collector foil 10 dry without using water. In this case, since this becomes the starting point for the collapse of the current collector foil 10, the control device 40 causes the ultrasonic probe 20 to scan from a position at a predetermined distance from the end of the current collector foil 10, so that the ultrasonic probe 20 does not contact the end of the electrode W1, i.e., the end of the current collector foil 10. That is, in the ultrasonic stripping process, ultrasonic waves from the irradiation surface of the ultrasonic welding head 21 create a gap between the current collector foil 10 and the electrode assembly 11 or electrode assembly 12, thereby stripping the electrode assembly 11 and electrode assembly 12 from the current collector foil 10 without using water. This prevents the foil sheets of the current collector foil 10 from mixing into the stripped electrode assembly 11 and electrode assembly 12, allowing the use of higher frequency bands and greater output power. Then, the electrode assembly 11 and electrode assembly 12 stripped from the electrode W1 slide off the conveying device 30 in sheet form and are collected by the recycling mechanism 50.

[0033] According to Embodiment 1 described above, water is not used. While scanning in a direction opposite to the transport direction of electrode W1, ultrasonic waves from the irradiation surface of ultrasonic welding head 21 are irradiated onto the entire electrode W1. As a result, electrode composite 11 and electrode composite 12 are peeled off from electrode W1, which includes current collector foil 10 containing current collector. Since a drying process for drying electrode composite 11 and electrode composite 12 is not required, the number of processes can be reduced.

[0034] Furthermore, according to Embodiment 1, the ultrasonic welding head 21 is coated with resin material 21a in such a way that it covers the entire surface including the irradiation surface of the ultrasonic waves, thus preventing deformation or wear of the ultrasonic welding head 21 and preventing metal foreign matter contamination caused by wear of the ultrasonic welding head 21.

[0035] Furthermore, according to Embodiment 1, the ultrasonic stripping process can be used for process end materials (ring electrodes) or large-area coated electrodes, and can be applied to any type of battery.

[0036] Furthermore, according to Embodiment 1, without prior crushing of the electrode W1, by utilizing the phenomenon that the amplitude of the ultrasonic wave from the ultrasonic welding head 21 deviates from the amplitude of the current collector foil 10, causing interfacial peeling of the soft coating material, namely the electrode material 11 and the electrode material 12, it is possible to peel off and recover the coated electrode material 11 and the electrode material 12 from the original state of the electrode W1.

[0037] Furthermore, according to Embodiment 1, since the adhesiveness of the electrode composite 11 and the electrode composite 12 is retained, they can be recycled in sheet form without being micronized, and the scattering loss of the electrode composite 11 and the electrode composite 12 as coating materials can be reduced.

[0038] Furthermore, according to Embodiment 1, the electrode material, which is the main target of processes such as poor coating, can be separately removed from the state of electrode W1 to serve as positive and negative electrodes, namely electrode material 11 and electrode material 12.

[0039] (Implementation Method 2)

[0040] Next, implementation method 2 will be described. Figure 3 This is a diagram showing the schematic structure of the ultrasonic stripping device involved in Embodiment 2. Figure 3 In the ultrasonic stripping device 1A shown, the ultrasonic probe 20 is fixed in position and also includes a conveying device 100.

[0041] The ultrasonic probe 20 is configured such that the ultrasonic welding head 21 contacts the electrode W1 conveyed by the conveying device 100, and the ultrasonic waves from the irradiation surface of the ultrasonic welding head 21 contact the electrode W1.

[0042] The conveying device 100 conveys the electrode W1 in a certain direction, conveys the pre-recovery coated roll 60 before recycling, and conveys the electrode W1 to the irradiation surface of the ultrasonic welding head 21 of the ultrasonic probe 20 and irradiates it, while conveying it to the post-recovery coated roll 70.

[0043] In the ultrasonic stripping apparatus 1A configured as described above, the ultrasonic probe 20, under the control of the control device 40, brings the ultrasonic waves from the irradiation surface of the ultrasonic welding head 21 into contact with and irradiates the electrode W1 as a whole, thereby stripping the electrode composite 11 (positive electrode) and electrode composite 12 (negative electrode) from the electrode W1 in a dry manner without the use of water. In this case, a brush or clamping roller can be provided at the stripping points of the electrode composite 11 (positive electrode) and electrode composite 12 (negative electrode), and the electrode composite 11, which is lifted from the current collector foil 10, is stripped using a sharp angle caused by the winding of the conveying device 100.

[0044] According to Embodiment 2 described above, by irradiating the entire electrode W1 with ultrasonic waves from the irradiation surface of the ultrasonic welding head 21, the electrode assembly 11 and electrode assembly 12 are peeled off from the electrode W1 containing the current collector foil 10. Therefore, a drying process for drying the electrode assembly 11 and electrode assembly 12 is not required, thus reducing the number of processes.

[0045] Further effects or variations can be readily derived by those skilled in the art. The invention is not limited to the specific details and representative embodiments shown and described above. Therefore, various modifications can be made without departing from the spirit or scope of the general invention as defined by the appended claims and their equivalents.

[0046] While several embodiments of this application have been described in detail above with reference to the accompanying drawings, these are merely illustrative. The present invention can be implemented in the manner described in the disclosure section of the present invention, as well as in other manner with various modifications and alterations based on the knowledge of those skilled in the art.

[0047] Symbol Explanation

[0048] 1. 1A - Ultrasonic stripping device; 10 - Current collector foil; 11, 12 - Electrode composite material; 20 - Ultrasonic probe; 21 - Ultrasonic welding head; 21a - Resin material; 30, 100 - Conveying device; 40 - Control device; 50 - Recycling mechanism; 60 - Coated roll before recycling; 70 - Coated roll after recycling; W1 - Electrode.

Claims

1. A method for recovering electrodes, characterized in that, include: The peeling process involves contacting an ultrasonic welding head, whose surface, including the irradiation surface for irradiating ultrasonic waves, is coated with a resin material, with an electrode having a current collector and an electrode assembly attached to the current collector, and irradiating the electrode assembly with ultrasonic waves from the irradiation surface of the ultrasonic welding head, thereby peeling the electrode assembly from the current collector. In the stripping process, the resin material, which serves as a transfer component, is placed between the ultrasonic welding head and the electrode, and water is not used to irradiate the electrode with ultrasonic waves from the ultrasonic welding head.

2. The electrode recovery method according to claim 1, characterized in that, In the stripping process, ultrasonic waves from the ultrasonic welding head are irradiated onto the electrode from a position at a predetermined distance from the end of the electrode.

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