Method for preparing electrode sheet, electrode sheet, battery cell and electrical device

Abstract

A method for preparing an electrode sheet, the electrode sheet, a battery cell and an electrical device belong to the technical field of batteries. The method for preparing the electrode sheet includes: coating a slurry on a current collector to obtain a to-be-treated electrode sheet; sequentially performing a first hot pressing treatment, a vibration treatment, and a second hot pressing treatment on the to-be-treated electrode sheet to obtain a treated electrode sheet. The technical solution of the embodiment of the present application is beneficial to reducing the rebound of the electrode sheet and improving the thickness consistency of the electrode sheet.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly to a method for preparing a pole piece, a pole piece, a battery cell, and an electrical device. Background Art

[0002] With the increasing environmental pollution, the new energy industry has attracted more and more attention. In the new energy industry, the performance of batteries is an important factor related to its development.

[0003] The performance of the pole piece in the battery is crucial for the performance of the battery. In the process of preparing the pole piece, it usually includes processes such as coating and rolling, and these processes have an important impact on the performance of the pole piece such as thickness, and thus have an important impact on the energy density and electrical performance of the battery. Therefore, how to provide a method for preparing a pole piece to reduce the rebound of the pole piece and improve the thickness consistency of the pole piece is a technical problem to be solved urgently. Summary of the Invention

[0004] The present application is made in view of the above problems, and its purpose is to provide a method for preparing a pole piece to reduce the rebound of the pole piece and improve the thickness consistency of the pole piece.

[0005] To achieve the above purpose, the present application provides a method for preparing a pole piece, a pole piece, a battery cell, and an electrical device.

[0006] In a first aspect, a method for preparing a pole piece is provided, including: coating a slurry on a current collector to obtain a to-be-treated pole piece; sequentially performing a first hot pressing treatment, a vibration treatment, and a second hot pressing treatment on the to-be-treated pole piece to obtain a treated pole piece.

[0007] In an embodiment of the present application, in the process of preparing the pole piece, the slurry is coated on the current collector to obtain a to-be-treated pole piece, which is convenient for subsequent processing of the to-be-treated pole piece. The to-be-treated pole piece is subjected to a first hot pressing treatment, so that it is beneficial to deform the pole piece and facilitate compaction of the pole piece; the pole piece after the first hot pressing treatment is subjected to a vibration treatment, which is beneficial to release the stress of the pole piece and reduce the rebound of the pole piece; the pole piece after the vibration treatment is subjected to a second hot pressing treatment, which is beneficial to further compact the pole piece and further reduce the rebound of the pole piece, thereby obtaining a pole piece with high thickness consistency and small rebound.

[0008] In a possible implementation manner, the frequency of the vibration treatment is less than or equal to 60 Hz. In this way, the risk of the pole piece breaking due to vibration can be reduced.

[0009] In a possible implementation, the frequency of the vibration treatment is 20 Hz to 60 Hz. When the frequency of the vibration treatment is greater than or equal to 20 Hz, it is convenient to eliminate the stress in the electrode sheet, thereby reducing the risk of local stress concentration and reducing the springback of the thickness of the electrode sheet; when the frequency of the vibration is less than or equal to 60 Hz, the risk of the electrode sheet breaking can be reduced.

[0010] In a possible implementation, during the vibration treatment, a single roller is used to perform the vibration treatment on the electrode sheet, and the single roller is in contact with the electrode sheet. In this way, the single roller is in contact with the electrode sheet, which is convenient for performing vibration treatment on the electrode sheet; in addition, using a single roller for vibration treatment is also beneficial to reducing the risk of excessive elongation of the electrode sheet.

[0011] In a possible implementation, the temperature of the first hot pressing treatment and the temperature of the second hot pressing treatment are less than or equal to 200 °C. In this way, the first hot pressing treatment and the second hot pressing treatment have appropriate temperatures, which can reduce the adverse effects of too high temperature on the electrode sheet.

[0012] In a possible implementation, the temperature of the first hot pressing treatment is less than the temperature of the second hot pressing treatment. In this way, it is beneficial to obtain an electrode sheet with less thickness rebound.

[0013] In a possible implementation, the temperature of the first hot pressing treatment is 60 °C to 120 °C. In this way, at least part of the film layer in the electrode sheet can undergo plastic deformation, which is beneficial to reducing the springback of the thickness of the electrode sheet.

[0014] In a possible implementation, the temperature of the second hot pressing treatment is 120 °C to 200 °C. In this way, it is beneficial to make at least part of the film layer in the electrode sheet undergo plastic deformation, thereby further compressing the electrode sheet and reducing the springback of the thickness of the electrode sheet.

[0015] In a possible implementation, the pressure of the first hot pressing treatment is greater than the pressure of the second hot pressing treatment. In this way, during the first hot pressing treatment, the pressure of the first hot pressing treatment is relatively large, which is beneficial to the plastic deformation of the film layer; during the second hot pressing treatment, the pressure of the second hot pressing treatment is less than the pressure of the first hot pressing treatment. In this way, the risk of crushing the particles in the film layer can be reduced, and the risk of the infiltrating property of the electrolyte deteriorating due to the crushed particles filling the gaps between the uncrushed particles can be reduced.

[0016] In a possible implementation, the pressure of the first hot pressing treatment is 588 Mpa to 980 MPa. In this way, it is convenient to make at least part of the electrode sheet undergo plastic deformation, which is beneficial to reducing the springback of the thickness of the electrode sheet.

[0017] In a possible implementation, the pressure of the second hot pressing treatment is 392 Mpa to 588 MPa. In this way, it is beneficial for further compressing the electrode sheet and reducing the risk of particles in the film layer being crushed.

[0018] In a possible implementation, the first hot pressing treatment and / or the second hot pressing treatment include: heating the electrode sheet to be processed; performing hot pressing treatment on the heated electrode sheet to be processed. In this way, after the heating treatment, the electrode sheet has a relatively high temperature, and then the hot pressing treatment is performed on the electrode sheet, which is convenient for the electrode sheet to undergo plastic deformation, thereby facilitating the reduction of the rebound of the electrode sheet; in addition, separating the heating treatment and the hot pressing treatment is also beneficial for reducing the complexity of preparation.

[0019] In a possible implementation, the hot pressing treatment method includes rolling treatment. Through rolling treatment, it is convenient to compress the electrode sheet.

[0020] In a possible implementation, the method further includes: after the second hot pressing treatment, performing a cooling treatment on the electrode sheet to be processed to obtain the processed electrode sheet. In this way, the electrode sheet can be quickly cooled, which is beneficial for accelerating the production rhythm.

[0021] In a possible implementation, the temperature of the cooling treatment is 20°C to 35°C. In this way, it is convenient to quickly cool the electrode sheet.

[0022] In a possible implementation, the moving speed of the electrode sheet is 10 m / min to 100 m / min. In this way, the electrode sheet has an appropriate moving speed, so that the production has an appropriate speed, which is beneficial for the preparation of the electrode sheet and the control of the production rhythm.

[0023] In a possible implementation, the electrode sheet is a negative electrode sheet.

[0024] In a possible implementation, the negative electrode sheet includes a negative electrode active material, and the negative electrode active material includes graphite.

[0025] In the above technical solution, after the negative electrode sheet is prepared, the thickness rebound of the negative electrode sheet is small and the thickness consistency of the negative electrode sheet is high. Therefore, after the negative electrode sheet is installed in the housing of the battery cell, the expansion of the negative electrode sheet is small, which is beneficial for improving the electrical performance of the battery cell.

[0026] In a second aspect, an electrode sheet is provided, and the electrode sheet is prepared according to the method in the first aspect and any one of its possible implementations.

[0027] In a third aspect, a battery cell is provided, including the electrode sheet described in the second aspect.

[0028] Fourthly, an electrical device is provided, including the battery cell described in the third aspect. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the drawings.

[0030] Figure 1 Schematic diagram of a method for preparing a pole piece according to an embodiment of the present application;

[0031] Figure 2 Schematic diagram of a pole piece according to an embodiment of the present application;

[0032] Figure 3 Schematic diagram of a method for preparing a pole piece according to an embodiment of the present application;

[0033] Figure 4 Schematic diagram of a device for preparing a pole piece according to an embodiment of the present application;

[0034] Figure 5 Schematic diagram of a battery cell according to an embodiment of the present application;

[0035] Figure 6 Schematic diagram of a battery according to an embodiment of the present application;

[0036] Figure 7 Schematic diagram of an electrical device according to an embodiment of the present application.

[0037] Reference Signs:

[0038] 2: Pole piece; 20: Current collector; 21: Membrane layer; 300: Device for preparing a pole piece; 310: First hot pressing device; 311: First heating module; 312: First hot pressing module; 320: Vibration device; 330: Second hot pressing device; 331: Second heating module; 332: Second hot pressing module; 340: Cooling device; 350: Rewinding device; 360: Unwinding device; 3: Battery cell; 31: Housing; 32: End cover assembly; 33: Electrode assembly; 33a: Tab; 322: Electrode terminal; 34: Current collecting member; 5: Battery; 6: Electrical device; 40: Motor; 30: Controller. Detailed Embodiments

[0039] The technical solutions in the embodiments of the present application will be described below with reference to the drawings.

[0040] To make the objectives, technical solutions and advantages of the embodiments of this application clearer, the following will clearly describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Apparently, the described embodiments are some but not all of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without making creative efforts shall fall within the scope of protection of this application.

[0041] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used in the description of this application in the specification are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application and the above accompanying drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description and claims of this application or the above accompanying drawings are used to distinguish different objects and not to describe a specific order or primary-secondary relationship.

[0042] The mention of "embodiment" in this application means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described in this application can be combined with other embodiments.

[0043] In the description of this application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected to", and "attached to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] The term "and / or" in this application is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally represents an "or" relationship between the associated objects before and after.

[0045] In the embodiments of the present application, the same reference numerals denote the same components, and for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only for illustrative purposes and should not constitute any limitation to the present application.

[0046] The term "a plurality of" as used in the present application refers to two or more (including two). Similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of sheets" refers to two or more sheets (including two sheets).

[0047] In the embodiments of the present application, the battery cell may be a secondary battery, which refers to a battery cell that can be activated by charging after discharging so that the active material can be reused.

[0048] The battery cell may be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium-metal battery, a sodium-metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-metal hydride battery, a nickel-cadmium battery, a lead-acid battery, etc., and the embodiments of the present application are not limited thereto.

[0049] In some implementation manners, the battery cell in the embodiments of the present application may be a metal battery. Specifically, the metal battery may include a lithium-metal secondary battery, a sodium-metal battery, a magnesium-metal battery, etc., and the embodiments of the present application are not limited thereto.

[0050] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and extracted back and forth between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, which can prevent the positive and negative electrodes from short-circuiting and at the same time allow the active ions to pass through.

[0051] In some embodiments, the positive electrode sheet may include a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material. Optionally, the positive electrode film layer further includes a conductive agent and a binder.

[0052] As an example, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0053] As an example, the positive electrode current collector can be a metal foil, a foam metal, or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. can be used. The foam metal can be foam nickel, foam copper, foam aluminum, foam alloy, or foam carbon, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0054] As an example, the positive electrode active material can include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of the lithium-containing phosphate can include, but are not limited to, at least one of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0055] In some embodiments, the negative electrode sheet can include a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material. Optionally, the negative electrode film layer includes a conductive agent and a binder.

[0056] As an example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film layer is provided on either one or both of the two opposite surfaces of the negative electrode current collector.

[0057] As an example, the negative electrode current collector can be a metal foil, a foam metal, or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. can be used. The foam metal can be foam nickel, foam copper, foam aluminum, foam alloy, or foam carbon, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0058] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode sheet and the negative electrode sheet.

[0059] In some embodiments, the separator is a separator membrane. The present application does not particularly limit the type of the separator membrane, and any well-known porous structure separator membrane with good chemical stability and mechanical stability can be selected.

[0060] As an example, the main material of the separator membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics.

[0061] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive electrode plate and the negative electrode plate, and simultaneously functions to transport ions and isolate the positive and negative electrodes.

[0062] In some embodiments, the battery cell further includes an electrolyte, and the electrolyte functions to conduct ions between the positive and negative electrodes. The present application does not specifically limit the type of the electrolyte, and it can be selected according to requirements. The electrolyte can be liquid, gel-like, or solid.

[0063] In some embodiments, the electrode assembly is provided with electrode tabs, and the electrode tabs can lead the current out of the electrode assembly. The electrode tabs include a positive electrode tab and a negative electrode tab.

[0064] In some embodiments, the battery cell can include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), or an aluminum-plastic film, etc.

[0065] The battery mentioned in the embodiments of the present application can include one or more battery cells to provide a single physical module with higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, parallel, or in a hybrid connection through a busbar component.

[0066] In some embodiments, the battery can be a battery pack, and the battery pack can include a box body and battery cells, and the battery cells or battery modules are accommodated in the box body.

[0067] In some embodiments, the box body can be a part of the chassis structure of a vehicle. For example, a part of the box body can become at least a part of the floor of the vehicle, or a part of the box body can become at least a part of the crossbeam and longitudinal beam of the vehicle.

[0068] In some embodiments, the battery can be used in an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0069] The performance of the electrode sheet in a battery cell has an important impact on the performance of the battery cell. For example, the thickness consistency of the electrode sheet and the springback of the thickness of the electrode sheet have an important impact on the energy density and electrical performance of the battery cell. In the process of preparing the electrode sheet, usually, a slurry is coated on a current collector, and after drying, an electrode sheet is obtained. The electrode sheet includes a current collector and a film layer provided on the surface of the current collector; then, the electrode sheet is cold-pressed to obtain an electrode sheet with a certain compaction density. However, the electrode sheet after cold pressing has more thickness springback and poor thickness consistency of the electrode sheet, which is not conducive to improving the performance of the electrode sheet.

[0070] In view of this, the embodiments of the present application provide a method for preparing an electrode sheet. After coating a slurry on a current collector to obtain an electrode sheet, the electrode sheet is sequentially subjected to a first hot pressing treatment, a vibration treatment, and a second hot pressing treatment to improve the thickness consistency of the electrode sheet and reduce the thickness springback of the electrode sheet.

[0071] Figure 1 It is a schematic diagram of a method for preparing an electrode sheet according to an embodiment of the present application. In the embodiments of the present application, for example, in combination with Figure 1 as shown, the method 100 for preparing an electrode sheet includes the following steps.

[0072] Step 110, coating a slurry on a current collector to obtain a to-be-treated electrode sheet.

[0073] The to-be-treated electrode sheet may refer to a current collector with a film layer after the coating (and optionally drying) process. The to-be-treated electrode sheet has not undergone the first hot pressing treatment, the vibration treatment, and the second hot pressing treatment.

[0074] In step 110, after coating the slurry on the current collector and passing through the drying process, a film layer can be obtained, and then a to-be-treated electrode sheet can be obtained. Figure 2 It is a schematic diagram of an electrode sheet according to an embodiment of the present application. For example, as Figure 2 shown, the to-be-treated electrode sheet 2 includes a current collector 20 and a film layer 21 provided on the surface of the current collector 20.

[0075] The film layer 21 is provided on at least one surface along the thickness direction of the current collector 20. As an example, as Figure 2 shown, film layers 21 are provided on both surfaces along the thickness direction of the current collector 20. As another example, a film layer 21 is provided on one surface along the thickness direction of the current collector 20, and no film layer 21 is provided on the other surface.

[0076] The current collector can be a positive current collector or a negative current collector. When the current collector is a positive current collector, the slurry is a positive slurry, which may include a positive active material, a binder, and a conductive agent. When the current collector is a negative current collector, the slurry is a negative slurry, which may include a negative active material, a binder, and a conductive agent.

[0077] Step 120: Subject the electrode to be processed to a first hot pressing treatment, a vibration treatment, and a second hot pressing treatment in sequence to obtain a processed electrode.

[0078] The hot pressing treatment may refer to a process of heating the electrode and applying pressure to the heated electrode.

[0079] The vibration treatment may refer to using a vibration device to process the electrode to cause the electrode to vibrate, thereby releasing the stress in the electrode.

[0080] During the first hot pressing treatment and the second hot pressing treatment, part of the electrode may undergo plastic deformation, which is beneficial to reducing the thickness rebound of the processed electrode and is also beneficial to obtaining an electrode with a relatively uniform thickness.

[0081] The treatment conditions of the first hot pressing treatment and the treatment conditions of the second hot pressing treatment may be the same or different. For example, the temperature and pressure of the first hot pressing treatment are the same as the temperature and pressure of the second hot pressing treatment. For another example, at least one of the temperature and pressure of the first hot pressing treatment is different from the temperature and pressure of the second hot pressing treatment.

[0082] In step 120, a vibration treatment is also provided between the first hot pressing treatment and the second hot pressing treatment. Through the vibration treatment, the stress of the electrode after the first hot pressing treatment can be released, which is beneficial to reducing the problem of excessive local stress of the electrode, reducing the risk of electrode cracking, and at the same time is also beneficial to reducing the rebound of the electrode after the second hot pressing treatment.

[0083] In addition, compared with performing the vibration treatment after the second hot pressing treatment, the method of performing the vibration treatment between the first hot pressing treatment and the second hot pressing treatment in the embodiments of the present application is more beneficial to controlling the performance such as the compaction density of the electrode.

[0084] In the embodiments of the present application, during the preparation of the electrode, a slurry is coated on the current collector to obtain the electrode to be processed, which is convenient for subsequent processing of the electrode to be processed. Subject the electrode to be processed to a first hot pressing treatment. In this way, it is beneficial to cause the electrode to deform and facilitate compaction of the electrode; subject the electrode after the first hot pressing treatment to a vibration treatment, which is beneficial to releasing the stress of the electrode and reducing the rebound of the electrode; subject the electrode after the vibration treatment to a second hot pressing treatment, which is beneficial to further compact the electrode and further reduce the rebound of the electrode, thereby obtaining an electrode with high thickness consistency and small rebound.

[0085] In some embodiments, the frequency of the vibration treatment is less than or equal to 60 Hz. When the vibration frequency is less than or equal to 60 Hz, the risk of the electrode breaking the belt can be reduced.

[0086] In some embodiments, the frequency of the vibration treatment is 20 Hz to 60 Hz.

[0087] The frequency of the vibration treatment can be 20 Hz, 30 Hz, 40 Hz, 50 Hz, 60 Hz, or any value within the above range.

[0088] When the frequency of the vibration treatment is greater than or equal to 20 Hz, it is convenient to eliminate the stress in the electrode sheet, thereby reducing the risk of local stress concentration and reducing the springback of the thickness of the electrode sheet; when the frequency of the vibration is less than or equal to 60 Hz, the risk of the electrode sheet breaking can be reduced.

[0089] Optionally, the frequency of the vibration treatment is 20 Hz to 50 Hz. In this way, the electrode sheet can be treated at a relatively low frequency to reduce or eliminate the stress concentration of the electrode sheet and reduce the springback of the thickness of the electrode sheet.

[0090] In some embodiments, during the vibration treatment, a single roller is used to perform the vibration treatment on the electrode sheet, and the single roller is in contact with the electrode sheet.

[0091] The single roller can refer to one roller. Using a single roller to perform the vibration treatment on the electrode sheet can mean selecting one roller to perform the vibration treatment on the electrode sheet and the roller is in contact with the electrode sheet. In this way, compared with using two opposite rollers to perform the vibration treatment on the electrode sheet while clamping the electrode sheet, the excessive elongation of the electrode sheet can be reduced, so that the prepared electrode sheet can have an elongation rate similar to that of the electrode sheet obtained after cold pressing treatment. That is to say, in this embodiment, using a single roller for vibration treatment is beneficial to reducing the springback of the thickness of the electrode sheet and obtaining an electrode sheet with a suitable elongation rate.

[0092] In some embodiments, the temperature of the first hot pressing treatment and the temperature of the second hot pressing treatment are less than or equal to 200 °C.

[0093] The temperature of the first hot pressing treatment is less than or equal to 200 °C, and the temperature of the second hot pressing treatment is less than or equal to 200 °C. For example, the temperature of the first hot pressing treatment is 200 °C, and the temperature of the second hot pressing treatment is 200 °C. For another example, the temperature of the first hot pressing treatment is 80 °C, and the temperature of the second hot pressing treatment is 180 °C.

[0094] The film layer on the current collector includes a binder. At a relatively high temperature, the binder may partially fail, thereby affecting the bonding performance of the binder. By setting the temperature of the first hot pressing treatment and the temperature of the second hot pressing treatment to be less than or equal to 200 °C, it is beneficial to reduce the influence on the binder.

[0095] In the above embodiments, the first hot pressing treatment and the second hot pressing treatment have appropriate temperatures, which can reduce the adverse effects of too high temperature on the film layer on the current collector.

[0096] In some embodiments, the temperature of the first hot pressing treatment is lower than that of the second hot pressing treatment.

[0097] Compared with the electrode sheet during the first hot pressing treatment, during the second hot pressing treatment, the electrode sheet has a higher temperature, which is conducive to further compressing the electrode sheet and reducing the thickness rebound of the electrode sheet.

[0098] In the above embodiments, the temperature of the first hot pressing treatment is lower than that of the second hot pressing treatment, which is conducive to obtaining an electrode sheet with less rebound.

[0099] In some embodiments, the temperature of the first hot pressing treatment is 60°C to 120°C.

[0100] The temperature of the first hot pressing treatment can be 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or any value within the above range.

[0101] When the temperature of the first hot pressing treatment is greater than or equal to 60°C, it is convenient to cause plastic deformation of part of the electrode sheet, which is conducive to reducing the springback of the electrode sheet; when the temperature of the first hot pressing treatment is less than or equal to 120°C, it is conducive to compressing the electrode sheet without affecting the performance of the film layer.

[0102] In the above embodiments, by setting the temperature of the first hot pressing treatment to 60°C to 120°C, at least part of the film layer in the electrode sheet can undergo plastic deformation, which is conducive to reducing the thickness springback of the electrode sheet and at the same time is conducive to reducing the adverse impact on the performance of the film layer.

[0103] In some embodiments, the temperature of the second hot pressing treatment is 120°C to 200°C.

[0104] The temperature of the second hot pressing treatment can be 120°C, 130°C, 140°C, 150°C, 160°C, 180°C, 200°C or any value within the above range.

[0105] When the temperature of the second hot pressing treatment is greater than or equal to 120°C, it is conducive to causing plastic deformation of at least part of the film layer in the electrode sheet, so that the electrode sheet can be further compressed and the thickness springback of the electrode sheet can be reduced; when the temperature of the second hot pressing treatment is less than or equal to 200°C, it is conducive to reducing the adverse impact on the performance of the film layer.

[0106] In some embodiments, the pressure of the first hot pressing treatment is greater than that of the second hot pressing treatment.

[0107] During the first hot pressing process, the pressure of the first hot pressing process is relatively high, which is beneficial to the plastic deformation of the film layer; during the second hot pressing process, the pressure of the second hot pressing process is less than that of the first hot pressing process. In this way, the risk of crushing the particles in the film layer can be reduced, and thus the risk of the wettability of the electrolyte deteriorating due to the crushed particles filling the gaps between the uncrushed particles can be reduced.

[0108] In some embodiments, the pressure of the first hot pressing process is 588 Mpa to 980 MPa.

[0109] The pressure of the first hot pressing process can be 588 Mpa, 688 Mpa, 750 Mpa, 850 Mpa, 980 Mpa or any value within the above range.

[0110] By setting the pressure of the first hot pressing process to be 588 Mpa to 980 MPa, it is convenient to make at least part of the electrode sheet undergo plastic deformation, which is beneficial to reducing the springback of the thickness of the electrode sheet.

[0111] In some embodiments, the pressure of the second hot pressing process is 392 Mpa to 588 MPa.

[0112] The pressure of the second hot pressing process can be 392 Mpa, 450 Mpa, 500 Mpa, 588 Mpa or any value within the above range.

[0113] By setting the pressure of the second hot pressing process to be 392 Mpa to 588 MPa, it is beneficial to further compact the electrode sheet and reduce the risk of the particles in the film layer being crushed.

[0114] In some embodiments, the first hot pressing process and / or the second hot pressing process includes: heating the electrode sheet to be processed; performing hot pressing on the heated electrode sheet to be processed.

[0115] During the first hot pressing process and the second hot pressing process, the electrode sheet can be heated by a heating device first, and then the electrode sheet can be compacted by a hot pressing device.

[0116] In the above embodiments, after the heating process, the electrode sheet has a relatively high temperature, and then the electrode sheet is hot pressed, which is convenient for the electrode sheet to undergo plastic deformation, thus being beneficial to reducing the rebound of the electrode sheet; in addition, separating the heating process and the hot pressing process is also beneficial to reducing the complexity of preparation.

[0117] In some embodiments, the heating method includes at least one of oven heating, spray gun heating or hot pressing device heating. By the above methods, it is convenient to heat the current collector provided with the film layer to a suitable temperature.

[0118] As an example, the pole piece is heat-treated by heating in an oven. Specifically, the heating temperature of the oven can be set to the temperature of the first hot pressing treatment or the second hot pressing treatment. During the heat treatment process, the pole piece passes through the inside of the oven, so that the temperature of the pole piece is increased to a certain extent.

[0119] As an example, after the heat treatment, the temperature of the pole piece is the same as or basically close to the heating temperature of the oven.

[0120] As an example, the pole piece is heated by a flame spray gun so that the pole piece reaches a relatively high temperature. The set temperature of the flame spray gun can be the temperature of the first hot pressing treatment or the second hot pressing treatment.

[0121] As an example, a heating component is provided in the hot pressing device, and the pole piece can be heated while being roll-pressed.

[0122] In some embodiments, the hot pressing treatment method includes a roll pressing treatment. Through the roll pressing treatment, it is convenient to compact the pole piece.

[0123] In some embodiments, the method for preparing the pole piece further includes: after the second hot pressing treatment, cooling the to-be-treated pole piece to obtain the treated pole piece. In this way, the pole piece can be quickly cooled, which is beneficial to accelerating the production rhythm.

[0124] After the second hot pressing treatment of the pole piece, the temperature of the pole piece is relatively high, so it is necessary to cool the pole piece, which is convenient for putting the pole piece into the housing of the battery cell and is beneficial to accelerating the production rhythm.

[0125] In some embodiments, the temperature of the cooling treatment is 20°C to 35°C. In this way, it is convenient to quickly cool the pole piece.

[0126] In some embodiments, the cooling treatment method includes at least one of air cooling and natural cooling. The above methods are convenient for cooling the pole piece and are beneficial to reducing the complexity of pole piece cooling.

[0127] As an example, cooling is carried out by air cooling. Specifically, a blowing device can be set at a corresponding position to cool the pole piece.

[0128] In some embodiments, the moving speed of the pole piece is 10 m / min to 100 m / min. In this way, the pole piece has a suitable moving speed, so that the production has a suitable speed, which is beneficial to the preparation of the pole piece and the control of the production rhythm.

[0129] The moving speed of the pole piece can be 10 m / min, 30 m / min, 50 m / min, 60 m / min, 80 m / min, 100 m / min or any value within the above range.

[0130] In some embodiments, the electrode sheet is a negative electrode sheet.

[0131] During the charge and discharge process of the battery, active ions are inserted into the negative electrode sheet, and the negative electrode sheet expands; and when there is a certain thickness resilience in the negative electrode sheet, the risk of failure of the negative electrode sheet is greater. Therefore, adopting the above preparation method for the negative electrode sheet can reduce the thickness resilience and expansion of the negative electrode sheet, which is beneficial to reducing the risk of failure of the negative electrode sheet.

[0132] In some embodiments, the negative electrode sheet includes a negative electrode active material, and the negative electrode active material includes graphite.

[0133] In the above technical solution, after the negative electrode sheet is prepared, the thickness resilience of the negative electrode sheet is small and the thickness consistency of the negative electrode sheet is high. Thus, after the negative electrode sheet is installed in the housing of the battery cell, the expansion of the negative electrode sheet is small, which is beneficial to improving the electrical performance of the battery cell.

[0134] In some embodiments, the volume average particle size Dv50 of the graphite is 5 μm to 20 μm. In this way, it is convenient to prepare an electrode sheet with a relatively high tap density.

[0135] In some embodiments, the slurry further includes a binder, and the binder includes at least one of polyvinylidene fluoride, polyacrylate, acrylic acid, and styrene-butadiene rubber. As an example, the binder includes polyvinylidene fluoride. As another example, the binder includes polyacrylate.

[0136] In some embodiments, the slurry further includes a conductive agent, and the conductive agent includes at least one of conductive carbon black, carbon nanotubes, and Ketjen black.

[0137] In some embodiments, the slurry further includes a thickening agent and a solvent. The thickening agent may include sodium carboxymethylcellulose, and the solvent may include N-methylpyrrolidone.

[0138] Figure 3 It is a schematic diagram of a method for preparing an electrode sheet according to an embodiment of the present application. As Figure 3 shown, the method 100 for preparing the electrode sheet includes the following steps.

[0139] Step 111: Coating the negative electrode slurry on the negative electrode current collector, and after drying, obtaining a to-be-treated negative electrode sheet. Wherein, the to-be-treated negative electrode sheet includes a current collector and a negative electrode film layer disposed on the surface of the current collector.

[0140] Step 121: Performing a first hot pressing treatment on the to-be-treated negative electrode sheet.

[0141] Step 122: Performing a vibration treatment on the negative electrode sheet that has undergone the first hot pressing treatment.

[0142] Step 123: Perform a second hot pressing process on the negatively charged electrode sheet that has undergone a vibration process.

[0143] Step 130: Cool the electrode sheet that has undergone the second hot pressing process.

[0144] Figure 4 This is a schematic diagram of the device for preparing an electrode sheet according to an embodiment of the present application. In an embodiment of the present application, for example, as Figure 4 shown, the electrode sheet preparation device 300 includes: a coating device (not shown in the figure), a first hot pressing device 310, a vibration device 320, and a second hot pressing device 330.

[0145] The coating device is used to coat the slurry on the current collector to obtain an electrode sheet to be processed. The electrode sheet to be processed includes a current collector and a film layer provided on the surface of the current collector.

[0146] Optionally, the electrode sheet preparation device 300 further includes a drying device. The drying device is used to dry the current collector after coating the slurry to obtain a film layer.

[0147] The first hot pressing device 310 is used to perform a heating process and a hot pressing process on the electrode sheet to be processed. For example, the first hot pressing device 310 includes a first heating module 311 and a first hot pressing module 312. The first heating module 311 is used to perform a heating process on the electrode sheet, and the first hot pressing module 312 is used to perform a hot pressing process on the heated electrode sheet. Among them, the first hot pressing module 312 can be a pressing roller, and the first heating module 311 can be an oven. A heating plate is provided in the oven, and the electrode sheet is located between the two heating plates to facilitate the heating plate to perform a heating process on the electrode sheet.

[0148] The vibration device 320 is used to perform a vibration process on the electrode sheet to be processed. For example, the vibration device 320 is a single roller, that is, a separate roller. The single roller contacts the electrode sheet and does not apply pressure or hardly applies pressure to the electrode sheet.

[0149] The second hot pressing device 330 is used to perform a heating process and a hot pressing process on the electrode sheet to be processed that has undergone a vibration process. For example, the second hot pressing device 330 includes a second heating module 331 and a second hot pressing module 332. The second heating module 331 is used to perform a heating process on the electrode sheet, and the second hot pressing module 332 is used to perform a hot pressing process on the heated electrode sheet. Among them, the second hot pressing module 332 can be a pressing roller, and the second heating module 331 can be an oven.

[0150] In the embodiments of the present application, the coating device is arranged to facilitate coating the slurry on the current collector, thereby facilitating obtaining the electrode sheet to be processed and facilitating subsequent processing of the electrode sheet; through the arrangement of the first hot pressing device 310, the vibrating device 320, and the second hot pressing device 330, it is convenient to press the electrode sheet to have a suitable compaction density, and the thickness rebound of the electrode sheet is small and the thickness consistency is high.

[0151] In some embodiments, the electrode sheet preparation device 300 may further include a cooling device 340 for cooling the electrode sheet after the second hot pressing treatment. Among them, the cooling device 340 may be an air cooling device.

[0152] In some embodiments, the electrode sheet preparation device 300 may further include a winding device 350 for winding the cooled electrode sheet.

[0153] In some embodiments, the electrode sheet preparation device 300 may further include an unwinding device 360 for unwinding the electrode sheet to facilitate the first hot pressing treatment of the electrode sheet.

[0154] The embodiments of the present application provide an electrode sheet obtained according to the electrode sheet preparation method of any of the above embodiments.

[0155] In some embodiments, the electrode sheet is a negative electrode sheet.

[0156] In some embodiments, the compaction density of the electrode sheet is 1.4 g / cm 3 ~1.8 g / cm 3 .

[0157] The embodiments of the present application provide a battery cell including the positive electrode sheet in any of the above embodiments.

[0158] The embodiments of the present application do not particularly limit the shape of the battery cell, and it may be cylindrical, square or any other shape. The battery cell may be a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery, a magnesium-ion battery, etc.

[0159] Figure 5 It is a schematic diagram of a battery cell according to an embodiment of the present application. For example, as Figure 5 shown, the battery cell 3 is a square battery cell. The battery cell 3 includes a housing 31, an end cap assembly 32, and an electrode assembly 33 disposed in the housing 31.

[0160] The electrode assembly 33 may be made of a positive electrode sheet, a negative electrode sheet, and a separator through a winding process or a stacking process.

[0161] The end cap assembly 32 includes electrode terminals 322. For example, as Figure 5 shown, the end cap assembly 32 includes two electrode terminals 322, one of which is a positive electrode terminal and the other is a negative electrode terminal.

[0162] The battery cell 3 further includes a current collecting member 34 for connecting the tab 33a of the electrode assembly 33 and the electrode terminal 322.

[0163] In some embodiments, the battery cells can be assembled into a battery module. The number of battery cells included in the battery module can be one or more, and those skilled in the art can select the specific number according to the application and capacity of the battery module.

[0164] The embodiment of the present application provides a battery including the battery cell in the above embodiment. Figure 6 It is a schematic diagram of the battery according to an embodiment of the present application. As Figure 6 shown, the battery 5 can include a plurality of battery cells (not shown in the figure).

[0165] The battery cells 3 can directly form the battery 5, or can first form a battery module, and then a plurality of battery modules form the battery 5.

[0166] The embodiment of the present application provides an electrical device including the battery described in the above embodiment.

[0167] Figure 7 It is a schematic diagram of the electrical device according to an embodiment of the present application. As Figure 7 shown, the present application provides an electrical device 6 including the battery in the above embodiment. The electrical device 6 can be a vehicle, and the vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A motor 40, a controller 30 and a battery 5 can be arranged inside the vehicle. The controller 30 is used to control the battery 5 to supply power to the motor 40. For example, the battery 5 can be arranged at the bottom, the front end or the rear end of the vehicle. The battery 5 can be used for power supply of the vehicle. For example, the battery 5 can be used as the operating power source of the vehicle for the vehicle's circuit system, such as for the working power requirements during the start, navigation and operation of the vehicle. In another embodiment of the present application, the battery 5 can not only be used as the operating power source of the vehicle, but also be used as the driving power source of the vehicle to replace or partially replace fuel or natural gas to provide driving power for the vehicle.

[0168] Optionally, the electrical device can also be an energy storage device, a lighting device, a spacecraft, etc., and the embodiments of the present application include but are not limited to this.

[0169] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0170] [Example]

[0171] Example 1

[0172] In Example 1, the preparation method of the electrode sheet is as follows.

[0173] (1) Dissolve sodium carboxymethylcellulose in water to prepare an aqueous solution of sodium carboxymethylcellulose with a concentration of 1.3 wt%.

[0174] (2) Mix graphite powder and conductive carbon black in a stirrer at a rotation speed of 15 rpm and stir for 5 min.

[0175] (3) Mix the materials mixed in step (2) with the aqueous solution of sodium carboxymethylcellulose and stir in a stirrer at a rotation speed of 20 rpm for 20 min to obtain a mixed slurry.

[0176] (4) Add polyacrylate to the mixed slurry and mix and stir in a stirrer at a stirring speed of 20 rpm for 20 min to obtain a negative electrode slurry. Among them, the graphite powder, conductive carbon black, sodium carboxymethylcellulose, binder polyacrylate and solvent NMP are mixed according to a mass ratio of 93:3:2:2:75.

[0177] (5) Coat the negative electrode slurry on the negative electrode current collector and dry it, and successively perform the first hot pressing treatment, vibration treatment, second hot pressing treatment, and cooling treatment; the treatment conditions of the first hot pressing treatment are: heat with an oven, set the oven temperature to 80 °C, perform rolling after heating, the hot pressing rolling force is 784 Mpa, and the moving speed of the electrode sheet is 80 m / min; the treatment conditions of the vibration treatment are: perform vibration treatment with a single roller, and the vibration frequency is 20 Hz; the treatment conditions of the second hot pressing treatment are: heat with an oven, the oven temperature is 180 °C, perform rolling after heating, the hot pressing rolling force is 392 Mpa, and the moving speed of the electrode sheet is 80 m / min; the treatment conditions of the cooling treatment are: cool by air cooling, and the temperature of the cooling treatment is 25 °C; continuously monitor the thickness of the negative electrode sheet during the treatment process to confirm the thickness rebound of the electrode sheet.

[0178] Example 2

[0179] The difference between Example 2 and Example 1 is that: the temperature of the first hot pressing treatment is 60 °C, and the temperature of the second hot pressing treatment is 120 °C.

[0180] Example 3

[0181] The difference between Example 3 and Example 1 is that: the temperature of the first hot pressing treatment is 100 °C, and the temperature of the second hot pressing treatment is 200 °C.

[0182] Example 4

[0183] Example 4 is different from Example 1 in that the temperature of the first hot pressing treatment is 120 °C and the temperature of the second hot pressing treatment is 120 °C.

[0184] Example 5

[0185] Example 5 is different from Example 1 in that the pressure of the first hot pressing treatment is 588 Mpa and the pressure of the second hot pressing treatment is 588 Mpa.

[0186] Example 6

[0187] Example 6 is different from Example 1 in that the pressure of the first hot pressing treatment is 980 Mpa and the pressure of the second hot pressing treatment is 490 Mpa.

[0188] Example 7

[0189] Example 7 is different from Example 1 in that the frequency of the vibration treatment is 40 Hz.

[0190] Example 8

[0191] Example 8 is different from Example 1 in that the frequency of the vibration treatment is 60 Hz.

[0192] Comparative Example 1

[0193] (1) Dissolve sodium carboxymethyl cellulose in water to prepare an aqueous sodium carboxymethyl cellulose solution with a concentration of 1.3 wt%.

[0194] (2) Mix graphite powder and conductive carbon black in a stirrer at a rotation speed of 15 rpm for 5 minutes.

[0195] (3) Mix the materials mixed in step (2) with the aqueous sodium carboxymethyl cellulose solution and stir in a stirrer at a rotation speed of 20 rpm for 20 minutes to obtain a mixed slurry.

[0196] (4) Add polyacrylate to the mixed slurry and mix and stir in a stirrer at a stirring speed of 20 rpm for 20 minutes to obtain a negative electrode slurry.

[0197] (5) Mix graphite powder, conductive carbon black, sodium carboxymethyl cellulose, binder polyacrylate and solvent NMP in a mass ratio of 93:3:2:2:75.

[0198] (6) Coat the negative electrode slurry on the negative electrode current collector and perform cold pressing treatment at room temperature. The treatment temperature is 20-25 °C and the pressure is 1176 Mpa; continuously monitor the thickness of the negative electrode plate during the treatment process to confirm the thickness rebound of the plate.

[0199] Comparative Example 2

[0200] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 did not undergo vibration treatment.

[0201] [Test on thickness uniformity of the electrode sheet]

[0202] An infrared laser thickness gauge was used to continuously monitor the thickness of the negative electrode sheet. Specifically, scanning was started from one end of the edge of the film area of the electrode sheet to the other end of the edge of the film area (the film area can refer to the area coated with the active material), and the thickness of the electrode sheet was taken every 3 mm.

[0203] [Test on thickness rebound of the electrode sheet]

[0204] An infrared laser thickness gauge was used to test the thickness of the electrode sheet processed by the method of the embodiment of the present application and the thickness of the electrode sheet after being placed for 48 h after processing. Specifically, scanning can be started from one end of the edge of the film area of the electrode sheet to the other end of the edge of the film area (the film area can refer to the area coated with the active material), the thickness of the electrode sheet was taken every 3 mm, and the average value of the obtained multiple thickness values was taken to obtain the relevant data of the thickness rebound of the electrode sheet.

[0205] [Test on elongation rate of the electrode sheet]

[0206] The electrode sheet was scribed along the running direction of the electrode sheet, and the spacing between the scribes was 100 mm. After the electrode sheet was prepared, the change in the spacing between the scribes was observed. The elongation rate can be obtained by the following method: elongation rate = (spacing between the scribes of the processed electrode sheet - spacing between the scribes of the electrode sheet before processing) / spacing between the scribes of the electrode sheet before processing.

[0207] Table 1 Experimental parameters of examples and comparative examples

[0208]

[0209] Table 2 Experimental results of examples and comparative examples

[0210]

[0211] Combined with Examples 1-8 and Comparative Example 1, compared with the method of only processing the electrode sheet by cold pressing, the method of hot pressing treatment and vibration treatment can effectively reduce the springback of the electrode sheet and improve the thickness uniformity of the electrode sheet; combined with Examples 1-8 and Comparative Example 2, by performing vibration treatment between the first hot pressing treatment and the second hot pressing treatment, the springback of the electrode sheet can be further reduced.

[0212] As shown in Examples 1-4, when the temperature of the first hot pressing treatment is 60°C to 120°C and the temperature of the second hot pressing treatment is 120°C to 200°C, it is beneficial to obtain a pole piece with less thickness rebound and better thickness uniformity; as shown in Examples 1-3 and Example 4, setting the temperature of the second hot pressing treatment to be higher than that of the first hot pressing treatment is beneficial to obtain a pole piece with even less thickness rebound.

[0213] As shown in Example 1 and Examples 5-6, when the pressure of the first hot pressing treatment is 588 Mpa to 980 MPa and the pressure of the second hot pressing treatment is 392 Mpa to 588 MPa, it is beneficial to obtain a pole piece with less thickness rebound and better thickness uniformity, and the pressure of the second hot pressing treatment being less than that of the first hot pressing treatment is beneficial to reducing the risk of particle breakage in the film layer.

[0214] As shown in Example 1 and Examples 7-8, setting the frequency of the vibration treatment at 20 Hz to 60 Hz can reduce the thickness rebound of the pole piece, and the pole piece will not break the tape.

[0215] As shown in Examples 1-8, using a single roller to perform vibration treatment on the pole piece is beneficial to the processing and treatment of the pole piece. For example, it can reduce the risk of diagonal lines appearing in the area where the insulating layer of the pole piece is coated, and further reduce the risks such as the pole piece being difficult to cut due to inaccurate positioning during the cutting process and the offset of the die-cutting position. In addition, compared with using a pair of rollers for vibration treatment, using a single roller to perform vibration treatment on the pole piece can reduce the excessive extension of the pole piece, the pole piece has an appropriate elongation rate, and the risk of the pole piece breaking the tape is reduced. In Example 1, the elongation rate is about 1.7%, and in Example 6, the elongation rate is 1.8% (not shown in the table); while using a pair of rollers for treatment, the elongation rate can reach 3.1%, and the risk of the pole piece breaking the tape increases.

[0216] It should be noted that this application is not limited to the above embodiments. The above embodiments are only examples, and embodiments with the same structure and the same function and effect as the technical idea within the scope of the technical solution of this application are all included in the technical scope of this application. In addition, within the scope of not departing from the gist of this application, various deformations that those skilled in the art can think of applied to the embodiments, and other ways constructed by combining some constituent elements in the embodiments are also included in the scope of this application.

Claims

1. A method for preparing a pole piece, characterized in that: include: Applying the slurry on the current collector to obtain a pole piece to be processed; The electrode piece to be processed is subjected to a first hot pressing treatment, a vibration treatment, and a second hot pressing treatment in sequence to obtain a processed electrode piece; During the vibration treatment, a single roller is used to perform the vibration treatment on the pole piece, and the single roller is in contact with the pole piece; The frequency of the vibration processing is less than or equal to 60 Hz.

2. The method according to claim 1, characterized in that The frequency of the vibration treatment is 20 Hz to 60 Hz.

3. The method according to claim 1, characterized in that The temperature of the first hot pressing treatment and the temperature of the second hot pressing treatment are less than or equal to 200°C.

4. The method according to claim 1, characterized in that: The temperature of the first heat pressing process is lower than the temperature of the second heat pressing process.

5. The method according to claim 1, characterized in that The temperature of the first hot pressing treatment is 60°C to 120°C.

6. The method according to claim 1, characterized in that The temperature of the second hot pressing treatment is 120°C to 200°C.

7. The method according to claim 1, characterized in that The pressure of the first hot pressing treatment is greater than the pressure of the second hot pressing treatment.

8. The method according to claim 1, characterized in that The pressure of the first hot pressing treatment is 588 MPa to 980 MPa.

9. The method according to claim 1, characterized in that: The pressure of the second hot pressing treatment is 392 MPa to 588 MPa.

10. The method according to claim 1, characterized in that The first hot pressing treatment and / or the second hot pressing treatment comprises: Performing a heating treatment on the electrode to be processed; The electrode to be processed after the heating treatment is subjected to hot pressing treatment.

11. The method according to claim 1, characterized in that: The method further comprises: After the second hot pressing treatment, the electrode sheet to be treated is cooled to obtain the treated electrode sheet.

12. The method according to claim 11, characterized in that The temperature of the cooling treatment is 20°C to 35°C.

13. The method according to claim 1, characterized in that The moving speed of the pole piece is 10m / min to 100m / min.

14. The method according to any one of claims 1 to 13, characterized in that The pole piece is a negative pole piece.

15. The method according to claim 14, characterized in that The negative electrode plate includes a negative electrode active material, and the negative electrode active material includes graphite.

16. A pole piece, characterized in that: Prepared according to the method according to any one of claims 1-15.

17. A battery cell, characterized in that: Comprising a pole piece as claimed in claim 16.

18. An electrical device, characterized in that: Comprising the battery cell as claimed in claim 17.

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