Method for recycling battery pole pieces

Abstract

The invention provides a method for recycling a battery pole piece, the battery pole piece comprises a current collector and an active material layer, the active material layer is arranged on at least one surface of the current collector, and the method comprises the following steps: (1) irradiating at least one part of the battery pole piece by using a first laser beam with the wavelength of 900-1200 nm, the first irradiated battery pole piece and the first recycled active material are obtained.

Description

Technical Field

[0001] This application relates to the field of secondary battery technology, and in particular to a method for recycling battery electrodes. Background Technology

[0002] In recent years, with the rapid development of the new energy sector, the demand for rechargeable batteries has surged. During the production process of rechargeable batteries (such as electrode coating), a certain proportion of scrapped electrodes are generated. Furthermore, some electrodes also become unusable during the use of rechargeable batteries (e.g., exceeding a certain timeframe). Therefore, the scientific and effective recycling of battery electrodes for secondary production can generate significant economic, environmental, and resource benefits.

[0003] Current methods for recycling battery electrodes often result in low powder yields and / or high levels of metallic impurities such as aluminum and copper shavings in the powder. Therefore, it is necessary to develop a battery electrode recycling process that achieves higher powder yields and lower levels of metallic impurities in the powder. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a method for recycling battery electrodes, which aims to achieve a high powder yield while taking into account the low content of metal impurities in the powder.

[0005] The inventors have discovered that by adopting the technical solution of this application, the above-mentioned objectives can be achieved.

[0006] This application provides a method for recycling battery electrode sheets, wherein the battery electrode sheet includes a current collector and an active material layer, the active material layer being disposed on at least one side of the current collector, the method comprising the following steps: (1) irradiating at least a portion of the battery electrode sheet with a first laser beam having a wavelength of 900-1200 nm to obtain a first irradiated battery electrode sheet and a first recycled active material.

[0007] By using the method of this application, a high powder yield can be achieved while maintaining a low content of metal impurities in the powder.

[0008] In any embodiment, the thickness of the active material layer is 10-30 μm.

[0009] When the thickness of the active material layer is 10-30μm, a high powder yield can be achieved while maintaining a low content of metal impurities in the powder.

[0010] In any embodiment, the battery electrode is processed using a roller brush before step (1).

[0011] Before step (1), the battery electrode is processed by a roller brush, which can achieve a high powder yield while ensuring that the content of metal impurities in the powder is low.

[0012] In any embodiment, the method further includes step (2): after step (1), the first irradiated battery electrode is treated with a first brush to obtain the first brush-treated battery electrode and the second recycled active material.

[0013] Using a brush for processing can achieve a high powder yield while ensuring a low content of metal impurities in the powder.

[0014] In any embodiment, the first recovered active material is collected by a first vacuum pump, and / or the second recovered active material is collected by a second vacuum pump.

[0015] In any embodiment, the method further includes step (3): after step (2), the first brush-treated battery electrode is flipped to obtain a flipped battery electrode.

[0016] By flipping the battery electrode and processing the other side, a high powder yield can be achieved while ensuring a low content of metal impurities in the powder.

[0017] In any embodiment, the method further includes step (4): after step (3), at least a portion of the flipped battery electrode is irradiated with a second laser beam with a wavelength of 900-1200 nm to obtain a second irradiated battery electrode and a third recycled active material.

[0018] Irradiating the other side of the battery electrode with a laser beam can achieve a high powder yield while ensuring a low content of metal impurities in the powder.

[0019] In any embodiment, the method further includes step (5): after step (4), the second irradiated battery electrode is treated with a second brush to obtain the second brush-treated battery electrode and the fourth recycled active material.

[0020] Using a brush for processing can achieve a high powder yield while ensuring a low content of metal impurities in the powder.

[0021] In any embodiment, the second recycled active material is collected by a second vacuum pump.

[0022] In any embodiment, the method further includes step (6): after step (5), merging the first recovered active material and the second recovered active material.

[0023] In any embodiment, the first laser beam moves at a speed of 10-30 m / min relative to the battery electrode, and / or the second laser beam moves at a speed of 10-30 m / min relative to the flipped battery electrode.

[0024] When the laser beam moves at a speed of 10-30 m / min relative to the battery electrode, the laser beam irradiates the battery electrode per unit area for a shorter time, making it less likely to cause etching and damage to the current collector. This reduces the generation of metal impurities such as aluminum and copper chips, achieving a high powder yield while maintaining a low content of metal impurities in the powder.

[0025] In any embodiment, the pulse width of the first laser beam is 10-300 ns, and / or the pulse width of the second laser beam is 10-300 ns.

[0026] Within this laser beam pulse width range, a high powder yield can be achieved while maintaining a low content of metal impurities in the powder.

[0027] In any embodiment, the power density of the first laser beam is in the range of 1×10⁻⁶. 6 -1×10 7 GW / cm 2 And / or the power density range of the second laser beam is 1×10 6 -1×10 7 GW / cm 2 .

[0028] Within this laser beam power density range, a high powder yield can be achieved while maintaining a low content of metal impurities in the powder.

[0029] In any embodiment, the pulse energy of the first laser beam is 3-50 mJ, and / or the pulse energy of the second laser beam is 3-50 mJ.

[0030] Within this laser beam pulse energy range, a high powder yield can be achieved while maintaining a low content of metal impurities in the powder.

[0031] In any embodiment, the frequency of the first laser beam is 5-500 kHz, and / or the frequency of the second laser beam is 5-500 kHz.

[0032] Within this laser beam frequency range, a high powder yield can be achieved while maintaining a low content of metal impurities in the powder. Attached Figure Description

[0033] Figure 1 This is a method for recycling battery electrodes according to one embodiment of this application.

[0034] Figure 2 A 20X metallographic photograph of the aluminum foil surface after laser de-powdering of the battery electrode is shown in one embodiment of this application.

[0035] Figure 3 The SEM results of the positive electrode active material recovered after laser de-powdering of the battery electrode sheet in one embodiment of this application are shown. Detailed Implementation

[0036] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the secondary battery, its preparation method, and its power-consuming device. However, unnecessary details may be omitted. For example, detailed descriptions of well-known facts and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0037] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0038] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0039] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0040] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0041] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0042] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0043] Current methods for recycling battery electrodes often result in low powder yields and / or high levels of metal impurities in the powder. Therefore, it is necessary to develop a battery electrode recycling process that achieves higher powder yields and lower levels of metal impurities in the powder.

[0044] Based on this, this application proposes a technical solution to solve the above-mentioned technical problems.

[0045] This application provides a method for recycling battery electrode sheets, wherein the battery electrode sheet includes a current collector and an active material layer, the active material layer being disposed on at least one side of the current collector, the method comprising the following steps: (1) irradiating at least a portion of the battery electrode sheet with a first laser beam having a wavelength of 900-1200 nm to obtain a first irradiated battery electrode sheet and a first recycled active material.

[0046] When at least a portion of the battery electrode is irradiated with a first laser beam with a wavelength of 900-1200nm, the active material layer of the electrode explodes under the instantaneous thermal action of the pulsed laser beam. The shock wave generated by the explosion causes the active material layer of the electrode to rupture and fly off from the surface of the electrode current collector. After part of the active material layer of the electrode ruptures and flies off, the pulsed laser beam continues to act on the remaining active material layer, thereby completely removing the active material layer from the surface of the electrode current collector. More than 99wt% of the active material can be separated within a separation time of as little as 1 minute.

[0047] When the laser beam wavelength is too short, to achieve separation of the active material layer from the current collector, the irradiation time per unit area of ​​the battery electrode needs to be extended. This results in an excessively long dwell time for the heated laser beam in a specific area, causing etching and damage to the current collector. Wear of the current collector generates metallic impurities such as aluminum and copper shavings, exacerbating powder removal pollution and affecting the quality of powder removal. Furthermore, these metallic impurities are non-magnetic, making them difficult to separate physically. Chemical separation methods increase costs and environmental burden. If the irradiation time per unit area of ​​the battery electrode is not extended when the laser beam wavelength is too short, the separation effect between the active material layer and the current collector is poor, resulting in low powder yield. Incomplete pyrolysis of the binder (e.g., PVDF) in the active material layer also fails to remove the binder completely, leading to an unclean surface on the recovered active material particles. Only when the surface of the recovered active material particles is clean can surface-addition and repair coating methods be performed, which is more cost-effective and easier to implement. Therefore, in this case, one or more additional processes are required, such as removing PVDF through secondary sintering. This greatly increases the process flow and cost, and also significantly increases the time required.

[0048] When the wavelength of the laser beam is too long, it can damage the surface morphology of the recovered active material, causing defects such as cracks. It can also break down the electrode, resulting in the generation of metallic impurities such as aluminum and copper shavings, exacerbating the powdering pollution and affecting the powdering quality. Furthermore, these metallic impurities are non-magnetic, making them difficult to separate using physical methods. Using chemical methods for separation would increase costs and further burden the environment.

[0049] Therefore, the method of this application can achieve a high powder yield while maintaining a low content of metal impurities in the powder. Furthermore, the method of this application has the advantages of high efficiency, short processing time, low cost, and environmental friendliness. In addition, the surface particle morphology of the active material recovered by the method of this application is not damaged; the surface morphology is intact, without cracks, and the particles are well dispersed, with the binder being almost completely removed.

[0050] In some embodiments, the thickness of the active material layer is 10-30 μm.

[0051] When the thickness of the active material layer is 10-30μm, the laser beam can fully act on the active material layer without damaging the current collector, thus achieving a high powder yield while ensuring a low content of metal impurities in the powder.

[0052] In some embodiments, the thickness of the active material layer is 15-25 μm. In some embodiments, the thickness of the active material layer is 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, or a range of any two of the above values ​​or a value within that range.

[0053] In some embodiments, before step (1), the battery electrode is treated with a roller brush. This can remove some impurities and make the film layer more porous, making it easier to remove powder, thereby achieving a higher powder yield while ensuring that the content of metal impurities in the powder is low.

[0054] In some embodiments, the method further includes step (2): after step (1), the first irradiated battery electrode is treated with a first brush to obtain the first brush-treated battery electrode and the second recycled active material, thereby further improving the powder yield.

[0055] Using a brush for processing can further collect the looser active material without damaging the current collector, thus achieving a higher powder yield while ensuring a lower content of metal impurities in the powder.

[0056] In some embodiments, the first recovered active material is collected by a first vacuum pump, and / or the second recovered active material is collected by a second vacuum pump.

[0057] The first and second air pumps can be the same or different, and their selection is independent of each other.

[0058] In some embodiments, the first recycled active material powder generated is collected by a first vacuum pump under negative pressure during and / or after the battery electrode is subjected to a first laser beam irradiation treatment.

[0059] In some embodiments, the current collector has an active material layer on only one surface. In some embodiments, the current collector has an active material layer on both surfaces.

[0060] When active material layers are provided on both sides of the current collector, the thickness of the two active material layers is 10-30 μm, which are independent of each other.

[0061] In some embodiments, the thicknesses of the two active material layers are independently of each other, ranging from 15 to 25 μm. In some embodiments, the thicknesses of the two active material layers are independently of each other, ranging from 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, or any range of two of the above values ​​or values ​​within that range.

[0062] When the thickness of the two active material layers is 10-30 μm, the laser beam can fully act on the active material layers without damaging the current collector, thus achieving a high powder yield while ensuring a low content of metal impurities in the powder.

[0063] In some embodiments, active material layers are provided on both sides of the current collector, and the method may include irradiating the active material layer on one side, flipping the battery electrode, and irradiating the active material layer on the other side.

[0064] In some embodiments, the method further includes step (3): after step (1), flipping the first irradiated battery electrode, or after step (2), flipping the first brush-treated battery electrode to obtain a flipped battery electrode.

[0065] By flipping the battery electrode and processing the other side, the active materials on both sides can be recovered, thus achieving a high powder yield while ensuring a low content of metal impurities in the powder.

[0066] In some embodiments, the method further includes step (4): after step (3), irradiating at least a portion of the flipped battery electrode with a second laser beam of wavelength 900-1200 nm to obtain a second irradiated battery electrode and a third recycled active material.

[0067] Irradiating the other side of the battery electrode with a laser beam can effectively recover the positive electrode active material on the other side, thereby achieving a high powder yield while ensuring a low content of metal impurities in the powder.

[0068] The first laser beam and the second laser beam can be the same or different, and the choice of the two is independent of each other.

[0069] The wavelengths of the first laser beam and the second laser beam can be the same or different, and their choices are independent of each other.

[0070] In some embodiments, the wavelengths of the first laser beam and the second laser beam are independently 900nm, 950nm, 1000nm, 1050nm, 1060nm, 1064nm, 1070nm, 1100nm, 1150nm, 1200nm, or a range of any two of the above values ​​or values ​​within that range.

[0071] In some implementations, the wavelengths of the first laser beam and the second laser beam are independently 1000-1200 nm.

[0072] A high powder yield can be achieved when the wavelengths of the first laser beam and the second laser beam are independently between 1000-1200nm.

[0073] In some implementations, the wavelengths of the first laser beam and the second laser beam are independently 900-1100 nm.

[0074] When the wavelengths of the first laser beam and the second laser beam are independently 900-1100nm, a high powder yield can be achieved while maintaining a low content of metal impurities in the powder.

[0075] In some implementations, the wavelengths of the first laser beam and the second laser beam are independently 1000-1100 nm.

[0076] When the wavelengths of the first laser beam and the second laser beam are independently 1000-1100nm, a high powder yield can be achieved while maintaining a low content of metal impurities in the powder.

[0077] In some embodiments, all portions of the battery electrode are irradiated with a first laser beam with a wavelength of 900-1200 nm and / or a second laser beam with a wavelength of 900-1200 nm. In some embodiments, at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, and at least 99.5% of the total area of ​​the battery electrode are irradiated with a first laser beam with a wavelength of 900-1200 nm and / or a second laser beam with a wavelength of 900-1200 nm.

[0078] In some embodiments, a first laser beam with a wavelength of 900-1200 nm and / or a second laser beam with a wavelength of 900-1200 nm are used to irradiate the compact portion of the surface of the battery electrode.

[0079] In this application, the “surface compact portion” of the battery electrode refers to the surface portion whose density is more than 20% higher than the overall density of the battery electrode.

[0080] Density can be measured by means known to those skilled in the art, such as GB / T3850-2015 Method for Determination of Density of Dense Sintered Metallic Materials and Hard Alloys.

[0081] In some embodiments, the method further includes step (5): after step (4), the second irradiated battery electrode is treated with a second brush to obtain a second brush-treated battery electrode and a fourth recycled active material.

[0082] Using a brush for processing can further collect the looser active material without damaging the current collector, thus achieving a higher powder yield while ensuring a lower content of metal impurities in the powder.

[0083] The first and second brushes can be the same or different; the choice between the two is independent of each other.

[0084] The treatment process using the first brush and the treatment process using the second brush can be the same or different; the choice between the two is independent of each other.

[0085] In some embodiments, the third recovered active material is collected by a third vacuum pump, and / or the fourth recovered active material is collected by a fourth vacuum pump.

[0086] The first, second, third, and fourth air pumps can be the same or different, and the selection of the four is independent of each other.

[0087] In some embodiments, the method further includes: combining the first recycled active material and / or the second recycled active material and / or the third recycled active material and / or the fourth recycled active material.

[0088] In some embodiments, when an active material layer is provided on only one surface of the current collector, the first recycled active material and the second recycled active material are combined.

[0089] In some embodiments, when active material layers are provided on both sides of the current collector, the first recycled active material, the second recycled active material, the third recycled active material, and the fourth recycled active material are combined.

[0090] In some embodiments, when active material layers are provided on both sides of the current collector, the first recycled active material and the third recycled active material are combined.

[0091] In some embodiments, when active material layers are provided on both sides of the current collector, the first recycled active material, the third recycled active material, and the fourth recycled active material are combined.

[0092] In some embodiments, when active material layers are provided on both sides of the current collector, the first recycled active material, the second recycled active material, and the third recycled active material are combined.

[0093] In some embodiments, the first laser beam moves at a speed of 10-30 m / min relative to the battery electrode, and / or the second laser beam moves at a speed of 10-30 m / min relative to the flipped battery electrode.

[0094] The speed at which the first laser beam moves relative to the battery electrode and the speed at which the second laser beam moves relative to the battery electrode can be the same or different; the choice between the two is independent of each other.

[0095] When the laser beam moves at a speed of 10-30 m / min relative to the battery electrode, the laser beam irradiates the battery electrode per unit area for a shorter time, making it less likely to cause etching and damage to the current collector. This reduces the generation of metal impurities such as aluminum and copper chips, achieving a high powder yield while maintaining a low content of metal impurities in the powder.

[0096] The moving speed of the first laser beam relative to the battery electrode and the moving speed of the second laser beam relative to the battery electrode are independently 10 m / min, 11 m / min, 12 m / min, 13 m / min, 14 m / min, 15 m / min, 16 m / min, 17 m / min, 18 m / min, 19 m / min, 20 m / min, 21 m / min, 22 m / min, 23 m / min, 24 m / min, 25 m / min, 26 m / min, 27 m / min, 28 m / min, 29 m / min, 30 m / min, or any two of the above values ​​or values ​​within that range.

[0097] In some embodiments, the pulse width of the first laser beam is 10-300 ns, and / or the pulse width of the second laser beam is 10-300 ns.

[0098] The pulse width range of the first laser beam and the pulse width range of the second laser beam can be the same or different, and the choice of the two is independent of each other.

[0099] The pulse width range of the first laser beam and the pulse width range of the second laser beam are independently 10ns, 20ns, 30ns, 40ns, 50ns, 60ns, 70ns, 80ns, 90ns, 100ns, 110ns, 120ns, 130ns, 140ns, 150ns, 160ns, 170ns, 180ns, 190ns, 200ns, 210ns, 220ns, 230ns, 240ns, 250ns, 260ns, 270ns, 280ns, 290ns, 300ns, or any two of the above values ​​or values ​​within that range.

[0100] Within this laser beam pulse width range, it can efficiently separate active materials without damaging the current collector, achieving a high powder yield while maintaining a low content of metal impurities in the powder.

[0101] In some embodiments, the power density of the first laser beam is in the range of 1×10⁻⁶. 6 -1×10 7 GW / cm 2 And / or the power density range of the second laser beam is 1×10 6 -1×10 7 GW / cm 2 .

[0102] The power density range of the first laser beam and the power density range of the second laser beam can be the same or different, and their selection is independent of each other.

[0103] In some embodiments, the power density range of the first laser beam and the power density range of the second laser beam are independently 1×10⁻⁶. 6 1.5×10 6 2×10 6 2.5×10 6 3×10 6 3.5×10 6 4×10 6 4.5×10 6 5×10 6 5.5×10 6 6×10 6 6.5×10 6 7×10 6 7.5×10 6 8×10 6 8.5×10 6 9×10 6 9.5×10 6 1×10 7 GW / cm 2, or a range consisting of any two of the above values ​​or values ​​within that range.

[0104] Within this laser beam power density range, it can efficiently separate active materials without damaging the current collector, achieving a high powder yield while maintaining a low content of metal impurities in the powder.

[0105] In some embodiments, the power density range of the first laser beam and the power density range of the second laser beam are independently 5 × 10⁻⁶. 6 Up to 1×10 7 GW / cm 2 .

[0106] When the power density range of the first laser beam and the power density range of the second laser beam are independently 5×10 6 Up to 1×10 7 GW / cm 2 At that time, a high powder yield can be achieved.

[0107] In some embodiments, the power density range of the first laser beam and the power density range of the second laser beam are independently 1×10⁻⁶. 6 Up to 5×10 6 GW / cm 2 .

[0108] When the power density range of the first laser beam and the power density range of the second laser beam are independently 1×10 6 Up to 5×10 6 GW / cm 2 At the same time, it can achieve a high powder yield while ensuring a low content of metal impurities in the powder.

[0109] In some embodiments, the pulse energy of the first laser beam is 3-50 mJ, and / or the pulse energy of the second laser beam is 3-50 mJ.

[0110] The pulse energy of the first laser beam and the pulse energy of the second laser beam can be the same or different, and the choice between the two is independent of each other.

[0111] In some embodiments, the pulse energy of the first laser beam and the pulse energy of the second laser beam are independently 3mJ, 4mJ, 5mJ, 6mJ, 7mJ, 8mJ, 9mJ, 10mJ, 15mJ, 20mJ, 25mJ, 30mJ, 35mJ, 40mJ, 45mJ, 50mJ, or a range of any two of the above values ​​or values ​​within that range.

[0112] Within this laser beam pulse energy range, it can efficiently separate active materials without damaging the current collector, achieving a high powder yield while maintaining a low content of metal impurities in the powder.

[0113] In some implementations, the pulse energy of the first laser beam and the pulse energy of the second laser beam are 3-5 mJ, which are independent of each other.

[0114] When the pulse energy of the first laser beam and the pulse energy of the second laser beam are independently 3-5 mJ, a high powder yield can be achieved while ensuring a low content of metal impurities in the powder.

[0115] In some embodiments, the frequency of the first laser beam is 5-500 kHz, and / or the frequency of the second laser beam is 5-500 kHz.

[0116] The frequencies of the first laser beam and the second laser beam can be the same or different, and their selection is independent of each other.

[0117] In some embodiments, the frequencies of the first laser beam and the second laser beam are independently 5 kHz, 10 kHz, 15 kHz, 20 kHz, 25 kHz, 30 kHz, 35 kHz, 40 kHz, 45 kHz, 50 kHz, 55 kHz, 60 kHz, 65 kHz, 70 kHz, 75 kHz, 80 kHz, 85 kHz, 90 kHz, 95 kHz, 100 kHz, 150 kHz, 200 kHz, 250 kHz, 300 kHz, 350 kHz, 400 kHz, 450 kHz, 500 kHz, or a range of any two of the above values ​​or values ​​within that range.

[0118] Within this laser beam frequency range, it can efficiently separate active materials without damaging the current collector, achieving a high powder yield while maintaining a low content of metal impurities in the powder.

[0119] In some embodiments, the diameter of the laser spot when the first laser beam reaches the surface of the battery electrode after being focused is 1-10 μm, and / or the diameter of the laser spot when the second laser beam reaches the surface of the battery electrode after being focused is 1-10 μm.

[0120] The diameter of the laser spot when the first laser beam reaches the surface of the battery electrode after being focused, and the diameter of the laser spot when the second laser beam reaches the surface of the battery electrode after being focused, can be the same or different; the choice between the two is independent of each other.

[0121] In some embodiments, the diameter of the laser spot when the first laser beam reaches the surface of the battery electrode after being focused, and the diameter of the laser spot when the second laser beam reaches the surface of the battery electrode after being focused, are independently 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, or a range of any two of the above values ​​or a value within that range.

[0122] Within this spot diameter range, it can efficiently separate active materials without damaging the current collector, achieving a high powder yield while maintaining a low content of metal impurities in the powder.

[0123] In some embodiments, the aluminum foil and / or aluminum shavings recovered in the method are collected and briquetted.

[0124] In some embodiments, the method for recycling battery electrodes in this application does not involve flattening the battery electrodes.

[0125] The battery electrodes that need to be recycled may have aged after being soaked in electrolyte, resulting in low surface strength and poor tensile strength. Flattening these electrodes can easily cause them to break, leading to interruptions in powder removal and unstable production capacity. Furthermore, the fracture interface will produce metallic impurities such as aluminum shavings and powder, which exacerbate powder removal contamination and negatively impact powder removal quality. The recycling method in this application does not involve flattening the battery electrodes. Therefore, it is applicable not only to scrapped electrodes that have not yet been assembled into cells on the production line (i.e., battery electrodes that have been soaked in electrolyte), but also to battery electrodes removed from cells that have aged after being soaked in electrolyte. This method has a wide range of applications, achieving a high powder yield while maintaining low metal impurity content in the powder, and features continuous process, stable production capacity, and high efficiency.

[0126] In some embodiments, the method for recycling battery electrodes of this application is carried out in a closed environment. If it is not carried out in a closed environment, on the one hand, dust impurities will be introduced into the active material obtained after de-powdering; on the other hand, if the laser polarizer is covered with dust, the wavelength and projected area cannot be guaranteed, which will affect the accuracy and thus affect the de-powdering rate and impurity content.

[0127] Figure 1This application illustrates a method for recycling battery electrodes according to one embodiment, wherein the waste battery electrodes are first processed using a roller brush, then one side of the electrode is irradiated with a laser and mechanically rubbed with a brush, the separated active material is collected using a dust collector, and the aluminum foil generated in the process is also collected; subsequently, a conveyor belt transports the electrode to an electrode flipping mechanism, the other side of the electrode is processed in the same way, the collected active material is combined, and the generated aluminum foil is pressed into a block.

[0128] Battery electrodes can be either positive or negative electrodes.

[0129] In the case of a positive electrode sheet, the active material layer may include positive electrode active materials known in the art for use in batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0130] In the case of the negative electrode sheet, the active material layer may include negative electrode active materials known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0131] In some embodiments, the current collector may be a metal foil or a composite current collector. For example, aluminum foil or copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0132] Example

[0133] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0134] I. Preparation Method

[0135] Example 1

[0136] The waste battery cells were physically discharged. After full discharge, the battery packs were disassembled and sorted to obtain the positive electrode sheets. The active material layers on both sides of the positive electrode sheets were 20 μm thick. The positive electrode sheets were then processed using a roller brush, followed by a fiber pulsed laser with a single pulse energy of 5 mJ, a frequency of 50 kHz, a pulse width of 30 ns, a wavelength of 1064 nm, and a power density of 5 × 10⁻⁶. 6 GW / cm 2 After being focused, the pulsed laser beam reaches the upper surface of the positive electrode with a spot diameter of 3 μm. The pulsed laser beam irradiates the electrode surface at a scanning speed of 20 m / min, cleaning the entire electrode surface to obtain an irradiated battery electrode and a first recycled active material. The first recycled active material is collected using a vacuum pump. Then, the irradiated battery electrode is treated with a brush to obtain a brush-treated battery electrode and a second recycled active material, which is also collected using a vacuum pump. Next, the electrode is flipped, and the laser beam irradiation and brush treatment steps are repeated, collecting a third and fourth recycled active material using a vacuum pump. The first, second, third, and fourth recycled active materials are combined to obtain the final active material.

[0137] Examples 2-5 and Comparative Examples 1-3

[0138] The main differences between Examples 2-5 and Comparative Examples 1-3 and Example 1 are shown in Table 1 below.

[0139] II. Testing Methods

[0140] 1. Determination of powder yield

[0141] Powder yield = final active material mass / (initial mass of recycled electrode * (1 - current collector mass percentage in recycled electrode)), where the current collector mass percentage can be found in the relevant parameter table of recycled electrode.

[0142] 2. Determination of metallic impurity content

[0143] The content of metal impurities in the final active material is determined by ICP testing.

[0144] III. Analysis of Test Results for Each Embodiment and Comparative Example

[0145] Each example and comparative example was prepared according to the above method, and various parameters were measured. The results are shown in Table 1 below.

[0146] Table 1. Parameters of the Examples and Comparative Examples

[0147]

[0148] from Figure 2It can be seen that the battery electrode recycling method of this application can thoroughly separate the current collector from the active material layer. After laser powder removal, the active material layer is almost invisible on the surface of the aluminum foil, and there is no obvious etching or wear, which indicates that the powder yield is high and the content of metal impurities in the powder is low.

[0149] from Figure 3 It can be seen that the battery electrode recycling method of this application does not damage the morphology of the recovered positive electrode active material particles. The SEM detection results show that the surface morphology is intact and no cracks are found; the particle dispersion is good and the PVDF is basically removed by thermal decomposition. According to the above, the battery electrode to be recycled in Examples 1-5 includes a current collector and an active material layer. The active material layer is disposed on at least one side of the current collector. The method for recycling the battery electrode includes the following steps: (1) irradiating at least a portion of the battery electrode with a first laser beam with a wavelength of 900-1200nm to obtain a first irradiated battery electrode and a first recycled active material.

[0150] As can be seen from the comparison between Examples 1-5 and Comparative Examples 1-3, the method of this application can achieve a high powder yield while maintaining a low content of metal impurities in the powder.

[0151] A comparison of Examples 1, 3-5 with Example 2 shows that a higher powder yield can be achieved when the wavelength of the first laser beam and / or the second laser beam is 1000-1200nm.

[0152] As can be seen from the comparison between Examples 1-4 and Example 5, when the wavelength of the first laser beam and / or the second laser beam is 900-1100nm, a high powder yield can be achieved while ensuring a low content of metal impurities in the powder.

[0153] As can be seen from the comparison between Examples 1 and 3-4 and Examples 2 and 5, when the wavelength of the first laser beam and / or the second laser beam is 1000-1100nm, a high powder yield can be achieved while ensuring a low content of metal impurities in the powder.

[0154] A comparison of Examples 1 and 4-5 with Examples 2-3 shows that when the power density range of the first laser beam and / or the second laser beam is 5×10⁻⁶, 6 Up to 1×10 7 GW / cm 2 At that time, a high powder yield can be achieved.

[0155] A comparison of Examples 1-3 and Examples 4-5 shows that when the power density range of the first laser beam and / or the second laser beam is 1×10⁻⁶, 6 Up to 5×10 6 GW / cm 2At the same time, it can achieve a high powder yield while ensuring a low content of metal impurities in the powder.

[0156] As can be seen from the comparison between Examples 1-4 and Example 5, when the pulse energy of the first laser beam and / or the second laser beam is 3-5 mJ, a high powder yield can be achieved while ensuring a low content of metal impurities in the powder.

[0157] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for recycling battery electrode sheets, the battery electrode sheet comprising a current collector and an active material layer, the active material layer being disposed on at least one side of the current collector, the method comprising the following steps: (1) Irradiate at least a portion of the battery electrode with a first laser beam of wavelength 900-1200nm to obtain a first irradiated battery electrode and a first recycled active material.

2. The method according to claim 1, wherein the thickness of the active material layer is 10-30 μm.

3. The method according to claim 1 or 2, wherein the battery electrode is treated with a roller brush before step (1).

4. The method according to any one of claims 1-3, wherein the method further comprises step (2): after step (1), the first irradiated battery electrode is treated with a first brush to obtain a first brush-treated battery electrode and a second recycled active material.

5. The method according to any one of claims 1-4, wherein the first recovered active material is collected by a first vacuum pump, and / or the second recovered active material is collected by a second vacuum pump.

6. The method according to any one of claims 1-5, wherein the method further comprises step (3): after step (1), flipping the first irradiated battery electrode, or after step (2), flipping the first brush-treated battery electrode to obtain a flipped battery electrode.

7. The method according to claim 6, wherein the method further comprises step (4): after step (3), irradiating at least a portion of the flipped battery electrode with a second laser beam of wavelength 900-1200 nm to obtain a second irradiated battery electrode and a third recycled active material.

8. The method according to claim 7, wherein the method further comprises step (5): after step (4), the second irradiated battery electrode is treated with a second brush to obtain a second brush-treated battery electrode and a fourth recycled active material.

9. The method according to claim 7 or 8, wherein the third recovered active material is collected by a third vacuum pump, and / or the fourth recovered active material is collected by a fourth vacuum pump.

10. The method according to any one of claims 1-9, wherein the first laser beam moves at a speed of 10-30 m / min relative to the battery electrode, and / or the second laser beam moves at a speed of 10-30 m / min relative to the flipped battery electrode.

11. The method according to any one of claims 1-10, wherein the pulse width range of the first laser beam is 10-300 ns, and / or the pulse width range of the second laser beam is 10-300 ns.

12. The method according to any one of claims 1-11, wherein the power density of the first laser beam is in the range of 1×10⁻⁶. 6 -1×10 7 GW / cm 2 And / or the power density range of the second laser beam is 1×10 6 -1×10 7 GW / cm 2 .

13. The method according to any one of claims 1-12, wherein the pulse energy of the first laser beam is 3-50 mJ, and / or the pulse energy of the second laser beam is 3-50 mJ.

14. The method according to any one of claims 1-13, wherein the frequency of the first laser beam is 5-500 kHz, and / or the frequency of the second laser beam is 5-500 kHz.

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