Preparation method for electrode sheet, and electrode sheet, battery and electric apparatus

Abstract

A preparation method for an electrode sheet, and an electrode sheet, a battery and an electric apparatus. The preparation method comprises: on at least one surface of a current collector, preparing a film layer comprising an active material and a binding agent, so as to obtain a preformed electrode sheet; performing heating processing on a specified part of the film layer, such that the specified part is heated up to a specified temperature within a specified period of time, wherein the specified part comprises at least part of the surface of the film layer, the specified period of time is greater than or equal to 15 ms, and the specified temperature is greater than or equal to 285℃. The preparation method for an electrode sheet, and the electrode sheet, the battery and the electric apparatus as provided can improve the performance of an electrode sheet, improve the performance of a battery that uses the electrode sheet and of an electric apparatus, and prolong the service life of the battery that uses the electrode sheet and of the electric apparatus.

Description

Preparation method of pole piece, pole piece, battery and electric device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202410139945.5 filed on January 31, 2024, entitled “Method for preparing electrode, electrode, battery and electrical device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of battery technology, and more specifically, to a method for preparing a pole piece, a pole piece, a battery, and an electrical device. Background Art

[0004] Battery technology is a crucial factor in the development of the new energy industry. With the continuous deepening of battery research and the continuous increase in market demand, higher requirements are being placed on various battery performances, such as energy density, cycle life, and reliability.

[0005] As a crucial component of batteries, pole pieces provide the active materials for chemical reactions and transmit electrons, playing a key role in battery performance and lifespan. For example, the pole piece's wettability and internal resistance affect battery impedance, self-discharge, and other properties. Therefore, improving the pole piece's performance can improve battery performance and lifespan.

[0006] Summary of the Invention

[0007] The embodiments of the present application provide a method for preparing a pole piece, a pole piece, a battery, and an electrical device, which can improve the performance of the pole piece, thereby improving the performance and service life of the battery and electrical device using the pole piece.

[0008] In a first aspect, a method for preparing a pole piece is provided, comprising: preparing a film layer comprising an active material and a binder on at least one surface of a current collector to obtain a prefabricated pole piece; performing a heat treatment on a specified portion of the film layer so that the specified portion is heated to a specified temperature within a specified time, wherein the specified portion includes at least a portion of the surface of the film layer, the specified time is greater than or equal to 15 ms, and the specified temperature is greater than or equal to 285°C.

[0009] In the embodiments of the present application, during the heat treatment of designated portions of the prefabricated electrode film, by controlling the designated time to be greater than 15ms and the designated temperature to be greater than 285°C, the electrode film resistance can be reduced, facilitating the transport of lithium ions and thereby improving battery performance. For example, for positive electrode sheets, heat treatment can be used to remove residual solvents and impurities on the electrode surface, thereby reducing the resistance of the positive electrode sheet; for negative electrode sheets, heat treatment can be used to improve the degree of graphitization and graphite orientation of the electrode sheet, as well as to remove impurities on the surface of the negative electrode sheet, thereby reducing the resistance of the negative electrode sheet.

[0010] In addition, under the action of high temperature, burrs, particles, etc. generated on the surface of the prefabricated electrode due to cutting can also be ablated. On the one hand, the sharpness of the electrode surface can be reduced, thereby reducing the risk of puncture of the isolation membrane, and thus improving the K value of the battery (voltage drop per unit time); on the other hand, reducing the ablation of burrs, particles and other impurities can reduce side reactions on the electrode surface, making the SEI film on the electrode surface more stable, thereby improving the capacity and initial efficiency of the battery prepared with the electrode.

[0011] In the embodiments of the present application, increasing the temperature of the prefabricated electrode can soften or ablate the binder in the electrode, thereby removing some of the binder and increasing the porosity of the electrode. This increased porosity increases the channels for electrolyte infiltration, increasing the electrolyte infiltration rate, and thus increasing the lithium ion transmission rate, thereby improving battery performance.

[0012] In a possible implementation, the specified time is 15 ms to 150 ms, and the specified temperature is 300° C. to 900° C.

[0013] In an embodiment of the present application, the temperature of at least part of the surface of the film layer rises to 300°C to 900°C within 15ms to 150ms, and the temperature of a designated part of the film layer is rapidly increased, which can improve the production efficiency of the electrode while improving the performance of the electrode, thereby improving the performance of the battery.

[0014] In one possible implementation, a heating unit is provided relative to the surface of the film layer along the thickness direction of the prefabricated electrode, and the heating unit is used to perform heat treatment on a designated portion, wherein the distance between the heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode is 5 mm to 150 mm, and / or the temperature of the heating treatment is 1000°C to 2000°C.

[0015] In an embodiment of the present application, a heating unit is provided along the thickness direction of the prefabricated electrode, and the distance between the heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode and / or the temperature of the heating unit is controlled within a reasonable range, so that a specified portion of the film layer is heated. This allows at least a portion of the surface of the film layer to be heated to a temperature greater than or equal to 285°C in a time greater than or equal to 15ms, thereby improving the performance of the electrode and thus improving the performance of the battery.

[0016] In one possible implementation, before heating the designated portion of the film layer, the method further includes: moving the prefabricated electrode piece using a conveying unit; and heating the designated portion of the film layer, including: heating the designated portion during the movement of the prefabricated electrode piece using a heating unit, wherein the heating unit is fixedly disposed between the starting point and the end point of the movement of the prefabricated electrode piece.

[0017] In an embodiment of the present application, during the movement of the prefabricated electrode sheet, a heating unit fixedly arranged between the starting point and the end point of the movement of the prefabricated electrode sheet can be used to heat the prefabricated electrode sheet. This can improve the performance of the electrode sheet while improving production efficiency, thereby improving the performance of the battery.

[0018] In a possible implementation, the moving speed of the prefabricated pole piece is 50 m / min to 200 m / min.

[0019] In an embodiment of the present application, the prefabricated electrode sheet can be effectively heated by a heating unit while the prefabricated electrode sheet is moving at a speed of 50m / min to 200m / min. This can improve production efficiency while improving the performance of the electrode sheet, thereby improving the performance of the battery.

[0020] In one possible implementation, the heating treatment includes at least one of flame combustion heating, electromagnetic induction heating, laser heating, plasma heating, arc heating, infrared heating, electric heating, or microwave heating.

[0021] In the embodiments of the present application, the prefabricated electrode can be heated by different methods such as flame combustion heating, electromagnetic induction heating, laser heating, plasma heating, arc heating, infrared heating, electric heating or microwave heating, so that the heating method suitable for production conditions and production requirements can be flexibly selected.

[0022] In a possible implementation, the heat treatment is performed on a designated portion of the film layer, including: performing plasma heating on the designated portion to raise the temperature of the designated portion to 300° C. to 700° C. within 50 ms to 150 ms.

[0023] In an embodiment of the present application, plasma heating can be performed on a designated portion of the prefabricated electrode so that the designated portion is heated to 300° C. to 700° C. within a designated time of 50ms to 150ms, thereby improving the performance of the electrode.

[0024] In one possible implementation, the distance between the plasma heating unit and the surface of the film layer along the thickness direction of the prefabricated pole piece is 5 mm to 25 mm, and / or the plasma heating temperature is 1000°C to 1200°C, and / or the moving speed of the prefabricated pole piece is 50 m / min to 80 m / min, wherein the heating unit includes a plasma heating unit.

[0025] In an embodiment of the present application, by setting one or more of the distance between the plasma heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode, the plasma heating temperature, and the moving speed of the prefabricated electrode within a reasonable range, the prefabricated electrode can be heated to a reasonable temperature range within a reasonable time range during the plasma heating process, for example, to 300°C to 700°C within 50ms to 150ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0026] In one possible implementation, plasma heating satisfies one or more of the following conditions: (1) the flow rate of the gas to be ionized by plasma heating is 10 L / min to 100 L / min; (2) the heating power of the plasma heating unit is 500 W to 15000 W; (3) the angle between the direction of the plasma heating unit and the thickness direction of the prefabricated electrode is 0° to 60°.

[0027] During the plasma heating process, by controlling at least one of the flow rate of the gas to be ionized, the heating power of the plasma heating unit, and the angle between the orientation of the plasma heating unit and the thickness direction of the prefabricated electrode within a reasonable range, it is convenient for the designated part of the film layer to be heated to a reasonable temperature range within a reasonable time range, for example, to 300°C to 700°C within 50ms to 150ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0028] In a possible implementation, the heating treatment is performed on a designated portion of the film layer, including: arc heating the designated portion so that the temperature of the designated portion is raised to 500° C. to 900° C. within 15 ms to 50 ms.

[0029] In an embodiment of the present application, arc heating can be performed on a designated portion of the prefabricated electrode so that the designated portion is heated to 500° C. to 900° C. within a designated time of 15ms to 50ms, thereby improving the performance of the electrode.

[0030] In one possible implementation, the distance between the arc heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode is 80 mm to 150 mm, and / or the arc heating temperature is 1600°C to 2000°C, and / or the moving speed of the prefabricated electrode is 160 m / min to 200 m / min, wherein the heating unit includes an arc heating unit.

[0031] In an embodiment of the present application, by setting one or more of the distance between the arc heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode, the arc heating temperature, and the moving speed of the prefabricated electrode within a reasonable range, the prefabricated electrode can be heated to a reasonable temperature range within a reasonable time range during the arc heating process, for example, to 500°C to 900°C within 15ms to 50ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0032] In one possible implementation, the arc heating satisfies one or more of the following conditions: (1) the gas flow rate of the arc heating unit is 30L / min to 80L / min; (2) the heating power of the arc heating unit is 1000W to 8000W; (3) the angle between the direction of the arc heating unit and the thickness direction of the prefabricated electrode is 0° to 60°.

[0033] During the arc heating process, by controlling at least one of the gas flow rate of the arc heating unit, the heating power of the arc heating unit, and the angle between the direction of the arc heating unit and the thickness direction of the prefabricated electrode within a reasonable range, it is convenient for the designated part of the film layer to be heated to a reasonable temperature range within a reasonable time range, for example, heating to 500°C to 900°C within 15ms to 50ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0034] In a possible implementation, the heating treatment is performed on a designated portion of the film layer, including: performing infrared heating on the designated portion, so that the temperature of the designated portion is raised to 400° C. to 900° C. within 20 ms to 60 ms.

[0035] In an embodiment of the present application, infrared heating can be performed on a designated portion of the prefabricated electrode so that the designated portion is heated to 400° C. to 900° C. within a designated time of 20ms to 60ms, thereby improving the performance of the electrode.

[0036] In one possible implementation, the distance between the infrared heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode is 5 mm to 50 mm, and / or the infrared heating temperature is 1400°C to 1800°C, and / or the moving speed of the prefabricated electrode is 120 m / min to 160 m / min, wherein the heating unit includes an infrared heating unit.

[0037] In an embodiment of the present application, by setting one or more of the distance between the infrared heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode, the infrared heating temperature, and the moving speed of the prefabricated electrode within a reasonable range, the designated part of the film layer of the prefabricated electrode can be heated to a reasonable temperature range within a reasonable time range during the infrared heating process, for example, to 400°C to 900°C within 20ms to 60ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0038] In a possible implementation, the infrared heating satisfies the following condition: the heating power of the infrared heating unit is 1000W to 5000W.

[0039] In the embodiment of the present application, by controlling the heating power of the infrared heating unit within a reasonable range, the temperature of the infrared heating can be controlled within a reasonable range, so that during the infrared heating process of the prefabricated electrode, the specified part of the film layer can be heated to a reasonable temperature range within a reasonable time, for example, to 400°C to 900°C within 20ms to 60ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0040] In a possible implementation, the heating treatment is performed on a designated portion of the film layer, including: electrically heating the designated portion so that the temperature of the designated portion is raised to 300° C. to 700° C. within 90 ms to 150 ms.

[0041] In an embodiment of the present application, a designated portion of the prefabricated electrode can be electrically heated so that the designated portion is heated to 300° C. to 700° C. within a designated time of 90ms to 150ms, thereby improving the performance of the electrode.

[0042] In one possible implementation, the distance between the electric heating unit and the surface of the membrane layer along the thickness direction of the prefabricated electrode piece is 5 mm to 25 mm, and / or the electric heating temperature is 1000°C to 1300°C, and / or the moving speed of the prefabricated electrode piece is 50 m / min to 80 m / min, wherein the heating unit includes an electric heating unit.

[0043] In an embodiment of the present application, by setting at least one of the distance between the electric heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode, the electric heating temperature, and the moving speed of the prefabricated electrode within a reasonable range, the designated part of the film layer of the prefabricated electrode can be heated to a reasonable temperature range within a reasonable time range during the electric heating process, for example, to 300°C to 700°C within 90ms to 150ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0044] In a possible implementation, the electric heating satisfies the following condition: the heating power of the electric heating unit is 500W to 14000W.

[0045] In an embodiment of the present application, by controlling the heating power of the electric heating unit within a reasonable range, the electric heating temperature can be controlled within a reasonable range, so that during the electric heating process of the prefabricated electrode, the specified part of the film layer can be heated to a reasonable temperature range within a reasonable time, for example, to 300°C to 700°C within 90ms to 150ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0046] In a possible implementation, the heating treatment is performed on a designated portion of the film layer, including: performing microwave heating on the designated portion, so that the temperature of the designated portion is raised to 300° C. to 800° C. within 50 ms to 120 ms.

[0047] In an embodiment of the present application, a designated portion of the prefabricated electrode may be subjected to microwave heating so that the designated portion is heated to 300° C. to 800° C. within a designated time of 50ms to 120ms, thereby improving the performance of the electrode.

[0048] In one possible implementation, the distance between the microwave heating unit and the surface of the membrane layer along the thickness direction of the prefabricated pole piece is 5 mm to 25 mm, and / or the microwave heating temperature is 1300°C to 1800°C, and / or the moving speed of the prefabricated pole piece is 80 m / min to 120 m / min, wherein the heating unit includes a microwave heating unit.

[0049] In an embodiment of the present application, by setting at least one of the distance between the microwave heating unit and the surface of the membrane layer along the thickness direction of the prefabricated electrode, the microwave heating temperature, and the moving speed of the prefabricated electrode within a reasonable range, the designated part of the membrane layer of the prefabricated electrode can be heated to a reasonable temperature range within a reasonable time range during the microwave heating process, for example, to 300°C to 800°C within 50ms to 120ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0050] In a possible implementation, microwave heating satisfies the following condition: the heating power of the microwave heating unit is 2000W to 10000W.

[0051] In the embodiment of the present application, by controlling the heating power of the microwave heating unit within a reasonable range, the microwave heating temperature can be controlled within a reasonable range, so that during the microwave heating process of the prefabricated electrode, the specified part of the film layer can be heated to a reasonable temperature range within a reasonable time, for example, to 300°C to 800°C within 50ms to 120ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0052] In one possible implementation, the method further includes: in the process of heating the designated portion, performing hot air treatment on the designated portion using a hot air nozzle, the hot air nozzle being fixedly arranged between the moving starting point and the moving end point of the prefabricated pole piece, and the hot air nozzle and the surface of the film layer along the thickness direction of the prefabricated pole piece are arranged relative to each other.

[0053] In the embodiments of the present application, hot air treatment can be used to clean impurities and combustion decomposition products from the surface of the prefabricated electrode sheet, thereby facilitating heating of the prefabricated electrode sheet and improving the efficiency of electrode heating. Furthermore, cleaning impurities and combustion decomposition products from the surface of the prefabricated electrode sheet can reduce the resistance of the electrode sheet and increase its porosity, thereby improving its performance.

[0054] In a possible implementation, along the thickness direction of the prefabricated pole piece, the distance between the hot air nozzle and the surface of the film layer is the same as the distance between the heating unit and the surface of the film layer.

[0055] In an embodiment of the present application, along the thickness direction of the prefabricated electrode, the distance between the hot air nozzle and the surface of the film layer is set to be the same as the distance between the heating unit and the surface of the film layer, which can simplify the structure of the equipment.

[0056] In a possible implementation, the temperature of the hot air treatment is 300°C to 600°C.

[0057] In the embodiment of the present application, by controlling the temperature of the hot air treatment within a reasonable range, the prefabricated electrode can be effectively hot-air treated, reducing the impact of too low a hot air treatment temperature on the heating treatment, thereby improving the performance of the electrode; on the other hand, it can also reduce unnecessary energy consumption caused by too high a hot air treatment temperature, saving the preparation cost of the electrode.

[0058] In one possible implementation, the hot air treatment satisfies one or more of the following conditions: (1) the hot air flow rate of the hot air treatment is 50 L / min to 300 L / min; (2) the angle between the direction of the hot air nozzle and the thickness direction of the prefabricated electrode is 0° to 45°; (3) along the moving direction of the prefabricated electrode, the distance between the hot air nozzle and the heating unit is 5 mm to 15 mm.

[0059] During the hot air treatment process, by controlling at least one of the hot air flow rate, the angle of the hot air nozzle, and the distance between the hot air nozzle and the heating unit along the moving direction of the prefabricated electrode within a reasonable range, the electrode can be effectively hot-air treated, thereby improving the performance of the electrode.

[0060] In one possible implementation, the hot air treatment satisfies one or more of the following conditions: (1) the hot air flow rate of the hot air treatment is 50 L / min to 200 L / min; (2) the angle between the direction of the hot air nozzle and the thickness direction of the prefabricated electrode is 20° to 45°; (3) along the moving direction of the prefabricated electrode, the distance between the hot air nozzle and the heating unit is 8 mm to 12 mm.

[0061] In a possible implementation, before performing the heat treatment on the designated portion of the film layer, the method further includes: performing one or more of the following treatments on the prefabricated electrode sheet: drying treatment, sheet pressing treatment, or cutting treatment.

[0062] In an embodiment of the present application, the prefabricated electrode can first be subjected to one or more of the following treatments: drying, pressing, and cutting. Then, the prefabricated electrode can be heated. The production process of the electrode can be flexibly adjusted based on production requirements, production site, etc.

[0063] In a possible implementation, the designated portion includes a portion between the surface of the film layer and one-third of the thickness close to the surface of the film layer.

[0064] In an embodiment of the present application, by heating the area between the surface of the film layer and one-third of the thickness near the surface of the film layer, the degree of softening or ablation of the adhesive in the film layer can be increased, the porosity of the electrode can be increased, the infiltration rate of the electrolyte can be increased, and thus the transmission rate of lithium ions can be increased.

[0065] In a second aspect, a pole piece is provided, which is obtained according to the preparation method in the first aspect or any possible implementation of the first aspect.

[0066] In a third aspect, a battery is provided, comprising the electrode according to the second aspect.

[0067] In a fourth aspect, an electrical device is provided, comprising the battery according to the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] FIG1 is a schematic flow chart of a method for preparing a pole piece provided in an embodiment of the present application.

[0069] FIG2 is a schematic diagram of the arrangement of the heating unit according to an embodiment of the present application.

[0070] FIG3 is a schematic flow chart of a method for preparing a pole piece provided in an embodiment of the present application.

[0071] FIG4 is a schematic flow chart of a method for preparing a pole piece provided in an embodiment of the present application.

[0072] FIG5 is a schematic diagram of the arrangement of the hot air nozzle provided in an embodiment of the present application.

[0073] FIG6 is a schematic diagram of a battery cell provided in an embodiment of the present application.

[0074] FIG7 is a schematic diagram of a battery module provided in an embodiment of the present application.

[0075] 8 and 9 are schematic diagrams of the battery provided in the embodiments of the present application. DETAILED DESCRIPTION

[0076] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0077] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0078] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0079] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0080] In the description of the embodiments of the present application, the term "at least one" refers to one or more, and "plurality" refers to two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple, respectively.

[0081] Terms such as "upper," "lower," "left," "right," "inner," and "outer" are used only to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they should not be understood as limitations on this application. In addition, the terms "first," "second," and "third," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. "Perpendicular" does not mean perpendicular in the strict sense, but is within the allowable error range. "Parallel" does not mean parallel in the strict sense, but is within the allowable error range.

[0082] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0083] Unless otherwise specified, all steps of the present 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 may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0084] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0085] Battery technology is a crucial factor in the development of the new energy industry. With the continuous deepening of battery research and the continuous increase in market demand, higher requirements are being placed on various battery performances, such as energy density, cycle life, and reliability.

[0086] As a crucial component of batteries, pole pieces provide the active materials for chemical reactions and transmit electrons, playing a key role in battery performance and lifespan. For example, the pole piece's wettability and internal resistance affect battery impedance, self-discharge, and other properties. Therefore, improving the pole piece's performance can improve battery performance and lifespan.

[0087] In view of this, embodiments of the present application provide a method for preparing a pole piece, a pole piece, a battery, and an electrical device. The method comprises: preparing a film layer comprising an active material and a binder on at least one surface of a current collector to obtain a prefabricated pole piece; and heating a designated portion of the film layer to raise the temperature to a designated temperature within a designated time, wherein the designated portion includes at least a portion of the surface of the film layer, the designated time is greater than or equal to 15 milliseconds, and the designated temperature is greater than or equal to 285°C. This improves the performance of the pole piece, thereby increasing the performance and service life of the battery and electrical device using the pole piece.

[0088] The following is an exemplary introduction to the method for preparing the electrode provided in the embodiments of the present application.

[0089] [Preparation of electrode]

[0090] FIG1 is a schematic flow chart of a method for preparing a pole piece provided in an embodiment of the present application.

[0091] 110 , preparing a film layer including an active material and a binder on at least one surface of a current collector to obtain a prefabricated electrode sheet.

[0092] The electrode sheet may include a positive electrode sheet or a negative electrode sheet.

[0093] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. For example, the positive electrode film layer can be prepared on at least one surface of the positive electrode current collector.

[0094] The positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is arranged on either one or both of the two opposite surfaces of the positive electrode current collector.

[0095] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver or silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0096] The positive electrode film layer includes a positive electrode active material. As an example, the positive electrode active material may include at least one of the following materials: an olivine-structured lithium phosphate, a lithium transition metal oxide, or a modified compound thereof. However, the present application is not limited to these materials, and other traditional 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 may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi1 / 3Co1 / 3Mn1 / 3O2 (also referred to as NCM333), LiNi0.5Co0.2Mn0.3O2 (also referred to as NCM523), LiNi0.5Co0.25Mn0.25O2 (also referred to as NCM211), LiNi0.6C At least one of lithium nickel cobalt aluminum oxide (e.g., LiNi0.85Co0.15Al0.05O2) or modified compounds thereof. Examples of lithium phosphates containing an olivine structure may include, but are not limited to, lithium iron phosphate (e.g., LiFePO4 (e.g., LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, lithium iron manganese phosphate, or a carbon composite material.

[0097] The positive electrode film layer includes a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, or a fluorine-containing acrylate resin.

[0098] In some embodiments, the positive electrode film layer may further include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0099] For example, the positive electrode active material, conductive agent, binder and any other components can be dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector to obtain a prefabricated positive electrode sheet.

[0100] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector. For example, the negative electrode film layer can be prepared on at least one surface of the negative electrode current collector.

[0101] The negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is arranged on either one or both of the two opposite surfaces of the negative electrode current collector.

[0102] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy, etc.) on a polymer base layer (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0103] The negative electrode film layer includes a negative electrode active material. 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. The silicon-based material may include at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, or silicon alloys. The tin-based material may include at least one of elemental tin, tin oxide compounds, or tin alloys. However, the present application is not limited to these materials, and other traditional 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.

[0104] The negative electrode film layer includes a binder. As an example, the binder may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), or carboxymethyl chitosan (CMCS).

[0105] In some embodiments, the negative electrode film layer may further include a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, or carbon nanofibers.

[0106] In some embodiments, the negative electrode film layer may further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0107] For example, the negative electrode active material, the conductive agent, the binder and the thickener may be dissolved in deionized water to form a negative electrode slurry; and then the negative electrode slurry may be coated on a negative electrode current collector to obtain a prefabricated negative electrode sheet.

[0108] 120, performing heat treatment on a designated portion of the film layer so that the designated portion is heated to a designated temperature within a designated time.

[0109] The designated location includes at least a portion of the surface of the film layer, the designated time is greater than or equal to 15 ms, and the designated temperature is greater than or equal to 285° C.

[0110] In the embodiments of the present application, during the heat treatment of designated portions of the prefabricated electrode film, by controlling the designated time to be greater than 15ms and the designated temperature to be greater than 285°C, the electrode film resistance can be reduced, facilitating the transport of lithium ions and thereby improving battery performance. For example, for positive electrode sheets, heat treatment can be used to remove residual solvents and impurities on the electrode surface, thereby reducing the resistance of the positive electrode sheet; for negative electrode sheets, heat treatment can be used to improve the degree of graphitization and graphite orientation of the electrode sheet, as well as to remove impurities on the surface of the negative electrode sheet, thereby reducing the resistance of the negative electrode sheet.

[0111] In addition, under the action of high temperature, burrs, particles, etc. generated on the surface of the prefabricated electrode due to cutting can also be ablated. On the one hand, the sharpness of the electrode surface can be reduced, thereby reducing the risk of puncture of the isolation membrane, and thus improving the K value of the battery (voltage drop per unit time); on the other hand, reducing the ablation of burrs, particles and other impurities can reduce side reactions on the electrode surface, making the SEI film on the electrode surface more stable, thereby improving the capacity and initial efficiency of the battery prepared with the electrode.

[0112] In the embodiments of the present application, increasing the temperature of the prefabricated electrode can soften or ablate the binder in the electrode, thereby removing some of the binder and increasing the porosity of the electrode. This increased porosity increases the channels for electrolyte infiltration, increasing the electrolyte infiltration rate, and thus increasing the lithium ion transmission rate, thereby improving battery performance.

[0113] In some embodiments, the designated time is 15 ms to 150 ms, and the designated temperature is 300° C. to 900° C.

[0114] In an embodiment of the present application, the temperature of at least part of the surface of the film layer rises to 300°C to 900°C within 15ms to 150ms, and the temperature of a designated part of the film layer is rapidly increased, which can improve the performance of the electrode while improving production efficiency, thereby improving the performance of the battery.

[0115] In some embodiments, a heating unit is provided relative to the surface of the film layer along the thickness direction of the prefabricated electrode, and the heating unit is used to perform heat treatment on a designated portion, wherein the distance between the heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode is 5 mm to 150 mm, and / or the temperature of the heating treatment is 1000°C to 2000°C.

[0116] When preparing a pole piece, a film layer is usually prepared on both surfaces of the current collector in the thickness direction. For example, as shown in Figure 2, when a film layer is prepared on both surfaces of the current collector in the thickness direction, the heating unit may include a first heating unit and a second heating unit arranged on both sides of the prefabricated pole piece in the thickness direction. The first heating unit and the second heating unit are arranged opposite to the surface of the film layer along the thickness direction of the prefabricated pole piece, that is, the first heating unit is arranged opposite to the upper surface of the prefabricated pole piece in the thickness direction, and the second heating unit is arranged opposite to the lower surface of the prefabricated pole piece in the thickness direction.

[0117] As an example, the distance between the heating unit and the surface of the film layer is 5 mm, 30 mm, 60 mm, 90 mm, 120 mm or 150 mm. Alternatively, the distance between the heating unit and the surface of the film layer can also be within the range obtained by combining any two of the above values.

[0118] As an example, the temperature of the heat treatment may be 1000° C., 1200° C., 1400° C., 1600° C., 1800° C. or 2000° C. Optionally, the temperature of the heat treatment may also be within a range obtained by combining any two of the above values.

[0119] In an embodiment of the present application, a heating unit is provided along the thickness direction of the prefabricated electrode, and the distance between the heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode and / or the temperature of the heating unit is controlled within a reasonable range, so that a specified portion of the film layer is heated. This allows at least a portion of the surface of the film layer to be rapidly heated to 300°C to 900°C, thereby improving the performance of the electrode and thus improving the performance of the battery.

[0120] FIG3 is a schematic flow chart of a method for preparing a pole piece provided in an embodiment of the present application.

[0121] 310 , preparing a film layer including an active material and a binder on at least one surface of a current collector to obtain a prefabricated electrode sheet.

[0122] The content of step 310 can refer to the relevant description above, and this application will not elaborate on it here.

[0123] 320 , using a conveying unit to move the prefabricated electrode.

[0124] In some embodiments, the transmission unit may include a conveyor belt, a conveyor track, or a guide roller as shown in FIG. 2 .

[0125] As an example, a film layer may be prepared on the surface of the current collector to obtain a prefabricated electrode piece, and the prefabricated electrode piece may be moved using a conveying unit.

[0126] 330 , using a heating unit to heat a designated portion of the prefabricated electrode during its movement, so that the designated portion is heated to a designated temperature within a designated time.

[0127] The designated location includes at least a portion of the surface of the film layer, the designated time is greater than or equal to 15 ms, and the designated temperature is greater than or equal to 285° C.

[0128] The heating unit is fixedly arranged between the moving starting point and the moving end point of the prefabricated pole piece.

[0129] In this embodiment, the prefabricated electrode piece is movable, and the heating unit is fixed or stationary. For example, while the prefabricated electrode piece is moving along with the conveying unit, the prefabricated electrode piece is heated by the heating unit fixedly disposed at a position between the starting point and the end point of the movement of the prefabricated electrode piece.

[0130] In an embodiment of the present application, during the movement of the prefabricated electrode sheet, a heating unit fixedly arranged between the starting point and the end point of the movement of the prefabricated electrode sheet can be used to heat the prefabricated electrode sheet. This can improve the performance of the electrode sheet while improving production efficiency, thereby improving the performance of the battery.

[0131] In some embodiments, the moving speed of the prefabricated pole piece is 50 m / min to 200 m / min.

[0132] As an example, the moving speed of the prefabricated pole piece may be 50 m / min, 80 m / min, 110 m / min, 140 m / min, 170 m / min or 200 m / min. Alternatively, the moving speed of the prefabricated pole piece may be within the range obtained by combining any two of the above values.

[0133] In an embodiment of the present application, the prefabricated electrode sheet can be effectively heated by a heating unit while the prefabricated electrode sheet is moving at a speed of 50m / min to 200m / min. This can improve production efficiency while improving the performance of the electrode sheet, thereby improving the performance of the battery.

[0134] In some embodiments, the heating process includes at least one of flame combustion heating, electromagnetic induction heating, laser heating, plasma heating, arc heating, infrared heating, electric heating, or microwave heating.

[0135] Flame combustion heating can use flame to burn the sample to increase the temperature of the sample.

[0136] Electromagnetic induction heating can use the method of electromagnetic induction to generate electric current inside the heated object, relying on the energy of this current to achieve the purpose of heating.

[0137] Laser heating can use the energy of laser to heat objects.

[0138] Plasma heating is an electrical heating method that utilizes the high temperature of the plasma formed by the ionization of the gas to be ionized and the energy released when free electrons in the plasma recombine with positive ions. The gas to be ionized in plasma heating can be air or an inert gas (such as nitrogen or argon).

[0139] Arc heating refers to heating that occurs when an electric current passes through a gas, such as air, to generate an arc and release heat.

[0140] Infrared heating is a heating method that uses infrared radiation to electrically heat objects. Heat energy can be directly transferred to objects with lower temperatures through electromagnetic waves in the infrared region.

[0141] Electric heating relies on heating elements such as resistance wire, silicon carbon rod or silicon molybdenum rod to generate heat, and then heats the object through convection and / or radiation.

[0142] Microwave heating is a heating method that relies on an object to absorb microwave energy and convert it into heat energy, thereby increasing the temperature of the object.

[0143] In the embodiment of the present application, one heating method may be used to heat the prefabricated electrode piece, and of course, a plurality of mixed heating methods may also be used to heat the prefabricated electrode piece.

[0144] In the embodiments of the present application, the prefabricated electrode can be heated by a variety of different methods such as flame combustion heating, electromagnetic induction heating, laser heating, plasma heating, arc heating, infrared heating, electric heating or microwave heating, so that the heating method suitable for production conditions and production requirements can be flexibly selected.

[0145] In some embodiments, the heating process may include at least one of plasma heating, arc heating, infrared heating, electric heating, or microwave heating.

[0146] In some embodiments, the heat treatment is performed on a designated portion of the film layer, including: performing plasma heating on the designated portion, so that the temperature of the designated portion is raised to 300° C. to 700° C. within 50 ms to 150 ms.

[0147] That is, in the plasma heating process, the designated time is 50 ms to 150 ms, and the designated temperature is 300° C. to 700° C.

[0148] As an example, during the plasma heating process, the specified time may be 50ms, 70ms, 90ms, 110ms, 130ms, or 150ms. Alternatively, during the plasma heating process, the specified time may be within a range obtained by combining any two of the above values.

[0149] As an example, during the plasma heating process, the designated temperature is 300° C., 400° C., 500° C., 600° C., or 700° C. Optionally, during the plasma heating process, the designated temperature may also be within a range obtained by combining any two of the above values.

[0150] In an embodiment of the present application, plasma heating can be performed on a designated portion of the prefabricated electrode so that the designated portion is heated to 300° C. to 700° C. within a designated time of 50ms to 150ms, thereby improving the performance of the electrode.

[0151] In some embodiments, the distance between the plasma heating unit and the surface of the film layer along the thickness direction of the prefabricated pole piece is 5 mm to 25 mm, and / or the temperature of the plasma heating is 1000°C to 1200°C, and / or the moving speed of the prefabricated pole piece is 50 m / min to 80 m / min, wherein the heating unit includes a plasma heating unit.

[0152] As an example, the plasma heating unit may be a plasma gun of a plasma heating device. Along the thickness direction of the prefabricated pole piece, the distance between the plasma gun and the surface of the film layer may be 5 mm to 25 mm.

[0153] As an example, the distance between the plasma heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode piece is 5 mm, 10 mm, 15 mm, 20 mm, or 25 mm. Alternatively, the distance between the plasma heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode piece may also be within the range obtained by combining any two of the above values.

[0154] As an example, the temperature of plasma heating is 1000° C., 1100° C. or 1200° C. Optionally, the temperature of plasma heating may also be within a range obtained by combining any two of the above values.

[0155] As an example, during the plasma heating process, the moving speed of the prefabricated pole piece may be 50 m / min, 60 m / min, 70 m / min, or 80 m / min. Alternatively, during the plasma heating process, the moving speed of the prefabricated pole piece may also be within the range obtained by combining any two of the above values.

[0156] In an embodiment of the present application, by setting one or more of the distance between the plasma heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode, the plasma heating temperature, and the moving speed of the prefabricated electrode within a reasonable range, it is possible to ensure that during the plasma heating process, the specified part of the film layer is heated to a reasonable temperature range within a reasonable time range, for example, to 300°C to 700°C within 50ms to 150ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0157] In some embodiments, plasma heating satisfies one or more of the following conditions: (1) the flow rate of the gas to be ionized by plasma heating is 10 L / min to 100 L / min; (2) the heating power of the plasma heating unit is 500 W to 15000 W; (3) the angle between the direction of the plasma heating unit and the thickness direction of the prefabricated electrode is 0° to 60°.

[0158] As an example, the flow rate of the gas to be ionized may be 10 L / min, 40 L / min, 70 L / min or 100 L / min. Alternatively, the flow rate of the gas to be ionized may also be within a range obtained by combining any two of the above values.

[0159] As an example, the heating power of the plasma heating unit may be 500 W, 4000 W, 8000 W, 12000 W or 15000 W. For another example, the heating power of the plasma heating unit may also be within the range obtained by combining any two of the above values.

[0160] As an example, the angle between the orientation of the plasma heating unit and the thickness direction of the prefabricated electrode piece can be 0°, 30°, or 60°. For another example, the angle between the orientation of the plasma heating unit and the thickness direction of the prefabricated electrode piece can also be within the range obtained by combining any two of the above values.

[0161] During the plasma heating process, the plasma heating temperature can be adjusted by adjusting the flow rate of the gas to be ionized and / or the heating power of the plasma heating unit, so that the plasma heating temperature can be controlled within a reasonable range.

[0162] During the plasma heating process, by controlling at least one of the flow rate of the gas to be ionized, the heating power of the plasma heating unit, and the angle between the orientation of the plasma heating unit and the thickness direction of the prefabricated electrode within a reasonable range, it is convenient for the designated part of the film layer to be heated to a reasonable temperature range within a reasonable time range, for example, to 300°C to 700°C within 50ms to 150ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0163] In some embodiments, the heating treatment is performed on a designated portion of the film layer, including: arc heating the designated portion to raise the temperature of the designated portion to 500° C. to 900° C. within 15 ms to 50 ms.

[0164] That is, during the arc heating process, the specified time is 15 ms to 50 ms, and the specified temperature is 500° C. to 900° C.

[0165] In an embodiment of the present application, arc heating can be performed on a designated portion of the prefabricated electrode so that the designated portion is heated to 500° C. to 900° C. within a designated time of 15ms to 50ms, thereby improving the performance of the electrode.

[0166] In some embodiments, the distance between the arc heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode is 80 mm to 150 mm, and / or the arc heating temperature is 1600°C to 2000°C, and / or the moving speed of the prefabricated electrode is 160 m / min to 200 m / min, wherein the heating unit includes an arc heating unit.

[0167] As an example, the arc heating unit may be an arc heating head. Along the thickness direction of the prefabricated electrode sheet, the distance between the arc heating head and the surface of the film layer is 80 mm to 150 mm.

[0168] As an example, along the thickness direction of the prefabricated electrode sheet, the distance between the arc heating unit and the surface of the film layer may be 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, or 150 mm. Alternatively, along the thickness direction of the prefabricated electrode sheet, the distance between the arc heating unit and the surface of the film layer may also be within the range obtained by combining any two of the above values.

[0169] As an example, the temperature of the arc heating may be 1600° C., 1700° C., 1800° C., 1900° C. or 2000° C. Optionally, the temperature of the arc heating may also be within a range obtained by combining any two of the above values.

[0170] As an example, the moving speed of the prefabricated pole piece is 160 m / min, 170 m / min, 180 m / min, 190 m / min or 200 m / min. Alternatively, the moving speed of the prefabricated pole piece may also be within the range obtained by combining any two of the above values.

[0171] In an embodiment of the present application, by setting one or more of the distance between the arc heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode, the arc heating temperature, and the moving speed of the prefabricated electrode within a reasonable range, the prefabricated electrode can be heated to a reasonable temperature range within a reasonable time range during the arc heating process, for example, to 500°C to 900°C within 15ms to 50ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0172] In some embodiments, arc heating satisfies one or more of the following conditions: (1) the gas flow rate of the arc heating unit is 30L / min to 80L / min; (2) the heating power of the arc heating unit is 1000W to 8000W; (3) the angle between the direction of the arc heating unit and the thickness direction of the prefabricated electrode is 0° to 60°.

[0173] As an example, the gas flow rate of the arc heating unit can be 30 L / min, 40 L / min, 50 L / min, 60 L / min, 70 L / min or 80 L / min. Alternatively, the gas flow rate of the arc heating unit can also be within the range obtained by combining any two of the above values.

[0174] As an example, the heating power of the arc heating unit may be 1000 W, 3000 W, 5000 W, 7000 W or 8000 W. Optionally, the heating power of the arc heating unit may also be within the range obtained by combining any two of the above values.

[0175] As an example, the angle between the direction of the arc heating unit and the thickness direction of the prefabricated electrode piece can be 0°, 30° or 60°. Alternatively, the angle between the direction of the arc heating unit and the thickness direction of the prefabricated electrode piece can also be within the range obtained by combining any two of the above values.

[0176] During the arc heating process, the arc heating temperature can be adjusted by adjusting the gas flow rate of the arc heating unit and / or the heating power of the arc heating unit, so that the arc heating temperature can be controlled within a reasonable range.

[0177] During the arc heating process, by controlling at least one of the gas flow of the arc heating unit, the heating power of the arc heating unit, and the angle between the direction of the arc heating unit and the thickness direction of the prefabricated electrode within a reasonable range, it is convenient for the designated part of the film layer to be heated to a reasonable temperature range within a reasonable time range, for example, to 500°C to 900°C within 15ms to 50ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0178] In some embodiments, the heat treatment is performed on the designated portion of the film layer, including: performing infrared heating on the designated portion to raise the temperature of the designated portion to 400° C. to 900° C. within 20 ms to 60 ms.

[0179] That is, during the infrared heating process, the designated time is 20 ms to 60 ms, and the designated temperature is 400° C. to 900° C.

[0180] As an example, during the infrared heating process, the specified time may be 20ms, 30ms, 40ms, 50ms or 60ms. Alternatively, during the infrared heating process, the specified time may also be within a range obtained by combining any two of the above values.

[0181] As an example, during the infrared heating process, the designated temperature is 300° C., 400° C., 500° C., 600° C., or 700° C. Optionally, during the infrared heating process, the designated temperature may also be within a range obtained by combining any two of the above values.

[0182] In an embodiment of the present application, infrared heating can be performed on a designated portion of the prefabricated electrode so that the designated portion is heated to 400° C. to 900° C. within a designated time of 20ms to 60ms, thereby improving the performance of the electrode.

[0183] In some embodiments, the distance between the infrared heating unit and the surface of the film layer along the thickness direction of the prefabricated pole piece is 5 mm to 50 mm, and / or the infrared heating temperature is 1400°C to 1800°C, and / or the moving speed of the prefabricated pole piece is 120 m / min to 160 m / min, wherein the heating unit includes an infrared heating unit.

[0184] As an example, the infrared heating unit may be a heating tube of an infrared heating device. Along the thickness direction of the prefabricated electrode, the distance between the heating tube of the infrared heating device and the surface of the film layer is 5 mm to 50 mm.

[0185] As an example, along the thickness direction of the prefabricated electrode sheet, the distance between the infrared heating unit and the surface of the film layer can be 5 mm, 14 mm, 23 mm, 32 mm, 41 mm, or 50 mm. Alternatively, along the thickness direction of the prefabricated electrode sheet, the distance between the infrared heating unit and the surface of the film layer can also be within the range obtained by combining any two of the above values.

[0186] As an example, the temperature of infrared heating is 1400° C., 1500° C., 1600° C., 1700° C. or 1800° C. Optionally, the temperature of infrared heating may also be within a range obtained by combining any two of the above values.

[0187] As an example, during the infrared heating process, the moving speed of the prefabricated pole piece may be 120 m / min, 130 m / min, 140 m / min, 150 m / min, or 160 m / min. Alternatively, during the infrared heating process, the moving speed of the prefabricated pole piece may be within the range obtained by combining any two of the above values.

[0188] In an embodiment of the present application, by setting one or more of the distance between the infrared heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode, the infrared heating temperature, and the moving speed of the prefabricated electrode within a reasonable range, the designated part of the film layer of the prefabricated electrode can be heated to a reasonable temperature range within a reasonable time range during the infrared heating process, for example, to 400°C to 900°C within 20ms to 60ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0189] In some embodiments, the infrared heating satisfies the following conditions: the heating power of the infrared heating unit is 1000W to 5000W.

[0190] During the infrared heating process, the temperature of the infrared heating can be adjusted by adjusting the heating power of the infrared heating unit.

[0191] As an example, the heating power of the infrared heating unit may be 1000 W, 2000 W, 3000 W, 4000 W or 5000 W. For another example, the heating power of the infrared heating unit may also be within the range obtained by combining any two of the above values.

[0192] In the embodiment of the present application, by controlling the heating power of the infrared heating unit within a reasonable range, the temperature of the infrared heating can be controlled within a reasonable range, so that during the infrared heating process of the prefabricated electrode, the specified part of the film layer can be heated to a reasonable temperature range within a reasonable time, for example, to 400°C to 900°C within 20ms to 60ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0193] In some embodiments, the heating treatment is performed on a designated portion of the film layer, including: electrically heating the designated portion so that the temperature of the designated portion is raised to 300° C. to 700° C. within 90 ms to 150 ms.

[0194] That is, in the electric heating process, the designated time is 90 ms to 150 ms, and the designated temperature is 300° C. to 700° C.

[0195] As an example, during the electric heating process, the specified time may be 90ms, 110ms, 130ms or 150ms. Alternatively, during the electric heating process, the specified time may also be within a range obtained by combining any two of the above values.

[0196] As an example, during the electric heating process, the designated temperature is 300° C., 400° C., 500° C., 600° C., or 700° C. Optionally, during the electric heating process, the designated temperature may also be within a range obtained by combining any two of the above values.

[0197] In an embodiment of the present application, a designated portion of the prefabricated electrode can be electrically heated so that the designated portion is heated to 300° C. to 700° C. within a designated time of 90ms to 150ms, thereby improving the performance of the electrode.

[0198] In some embodiments, the distance between the electric heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode piece is 5 mm to 25 mm, and / or the electric heating temperature is 1000°C to 1300°C, and / or the moving speed of the prefabricated electrode piece is 50 m / min to 80 m / min, wherein the heating unit includes an electric heating unit.

[0199] As an example, the electric heating unit may be a resistance wire, silicon carbon rod or silicon molybdenum rod of an electric heating device. Along the thickness direction of the prefabricated electrode, the distance between the resistance wire of the electric heating device and the surface of the film layer may be 5 mm to 25 mm.

[0200] As an example, the distance between the electric heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode sheet is 5 mm, 10 mm, 15 mm, 20 mm, or 25 mm. Alternatively, the distance between the electric heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode sheet may also be within the range obtained by combining any two of the above values.

[0201] As an example, the temperature of the electric heating is 1000° C., 1150° C. or 1300° C. Optionally, the temperature of the electric heating may also be within a range obtained by combining any two of the above values.

[0202] As an example, during the electric heating process, the moving speed of the prefabricated electrode piece may be 50 m / min, 60 m / min, 70 m / min, or 80 m / min. Alternatively, during the electric heating process, the moving speed of the prefabricated electrode piece may also be within the range obtained by combining any two of the above values.

[0203] In an embodiment of the present application, by setting one or more of the distance between the electric heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode, the electric heating temperature, and the moving speed of the prefabricated electrode within a reasonable range, the prefabricated electrode can be heated to a reasonable temperature range within a reasonable time range during the electric heating process, for example, to 300°C to 700°C within 90ms to 150ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0204] In some embodiments, the electric heating satisfies the following conditions: the heating power of the electric heating unit is 500W to 14000W.

[0205] During the electric heating process, the electric heating temperature can be adjusted by adjusting the heating power of the electric heating unit.

[0206] As an example, the heating power of the electric heating unit may be 500 W, 4000 W, 8000 W, 12000 W or 14000 W. Optionally, the heating power of the electric heating unit may also be within the range obtained by combining any two of the above values.

[0207] In an embodiment of the present application, by controlling the heating power of the electric heating unit within a reasonable range, the electric heating temperature can be controlled within a reasonable range, so that during the electric heating process of the prefabricated electrode, the specified part of the film layer can be heated to a reasonable temperature range within a reasonable time, for example, to 300°C to 700°C within 90ms to 150ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0208] In some embodiments, the heating treatment is performed on the designated portion of the film layer, including: performing microwave heating on the designated portion, so that the temperature of the designated portion is raised to 300° C. to 800° C. within 50 ms to 120 ms.

[0209] That is, during the microwave heating process, the designated time is 50 ms to 120 ms, and the designated temperature is 300°C to 800°C.

[0210] As an example, during microwave heating, the specified time may be 50 ms, 70 ms, 90 ms, 110 ms, or 120 ms. Alternatively, during microwave heating, the specified time may be within a range obtained by combining any two of the above values.

[0211] As an example, during microwave heating, the designated temperature is 300° C., 400° C., 500° C., 600° C., 700° C., or 800° C. Alternatively, during microwave heating, the designated temperature may be within a range obtained by combining any two of the above values.

[0212] In an embodiment of the present application, a designated portion of the prefabricated electrode may be subjected to microwave heating so that the designated portion is heated to 300° C. to 900° C. within a designated time of 50ms to 120ms, thereby improving the performance of the electrode.

[0213] In some embodiments, the distance between the microwave heating unit and the surface of the membrane layer along the thickness direction of the prefabricated pole piece is 5 mm to 25 mm, and / or the microwave heating temperature is 1300°C to 1800°C, and / or the moving speed of the prefabricated pole piece is 80 m / min to 120 m / min, wherein the heating unit includes a microwave heating unit.

[0214] As an example, the heating unit of microwave heating can be a microwave generator of a microwave heating device, such as a magnetron. Along the thickness direction of the prefabricated pole piece, the distance between the microwave generator and the surface of the film layer is 5 mm to 25 mm.

[0215] As an example, along the thickness direction of the prefabricated electrode piece, the distance between the microwave heating unit and the surface of the membrane layer can be 5 mm, 10 mm, 15 mm, 20 mm, or 25 mm. Alternatively, along the thickness direction of the prefabricated electrode piece, the distance between the microwave heating unit and the surface of the membrane layer can also be within the range obtained by combining any two of the above values.

[0216] As an example, the temperature of microwave heating is 1300° C., 1400° C., 1500° C., 1600° C., 1700° C. or 1800° C. Optionally, the temperature of microwave heating may also be within the range obtained by combining any two of the above values.

[0217] As an example, during the microwave heating process, the moving speed of the prefabricated electrode piece may be 80 m / min, 90 m / min, 100 m / min, 110 m / min, or 120 m / min. Alternatively, during the microwave heating process, the moving speed of the prefabricated electrode piece may also be within the range obtained by combining any two of the above values.

[0218] In an embodiment of the present application, by setting one or more of the distance between the microwave heating unit and the surface of the membrane layer along the thickness direction of the prefabricated electrode, the microwave heating temperature, and the moving speed of the prefabricated electrode within a reasonable range, the designated part of the membrane layer of the prefabricated electrode can be heated to a reasonable temperature range within a reasonable time range during the microwave heating process, for example, to 300°C to 800°C within 50ms to 120ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0219] In some embodiments, microwave heating satisfies the following conditions: the heating power of the microwave heating unit is 2000W to 10000W.

[0220] During the microwave heating process, the microwave heating temperature can be adjusted by adjusting the heating power of the microwave heating unit.

[0221] As an example, the heating power of the microwave heating unit may be 2000 W, 4000 W, 6000 W, 8000 W or 10000 W. Alternatively, the heating power of the microwave heating unit may also be within the range obtained by combining any two of the above values.

[0222] In the embodiment of the present application, by controlling the heating power of the microwave heating unit within a reasonable range, the microwave heating temperature can be controlled within a reasonable range, so that during the microwave heating process of the prefabricated electrode, the specified part of the film layer can be heated to a reasonable temperature range within a reasonable time, for example, to 300°C to 800°C within 50ms to 120ms, thereby achieving effective heating of the electrode and improving the performance of the electrode.

[0223] FIG4 is a schematic flow chart of a method for preparing a pole piece provided in an embodiment of the present application.

[0224] 410 , preparing a film layer including an active material and a binder on at least one surface of a current collector to obtain a prefabricated electrode sheet.

[0225] 420, performing a heat treatment on a designated portion of the film layer so that the designated portion is heated to a designated temperature within a designated time.

[0226] The designated portion includes at least a portion of the surface of the film layer, the designated portion includes at least a portion of the surface of the film layer, the designated time is greater than or equal to 15 ms, and the designated temperature is greater than or equal to 285° C.

[0227] The contents of step 410 and step 420 can refer to the relevant description above, and this application will not elaborate on them here.

[0228] 430. During the heating process of the designated portion, a hot air nozzle is used to perform hot air treatment on the designated portion.

[0229] The hot air nozzle is fixedly arranged between the moving starting point and the moving end point of the prefabricated pole piece, and the hot air nozzle is arranged opposite to the surface of the film layer along the thickness direction of the prefabricated pole piece.

[0230] In the embodiment of the present application, the hot air nozzle and the heating unit are respectively arranged at different positions between the moving starting point and the moving end point of the prefabricated electrode.

[0231] As an example, during the movement of the prefabricated pole piece, the prefabricated pole piece may be subjected to heating treatment and hot air treatment at the same time.

[0232] In the embodiments of the present application, hot air treatment can be used to clean impurities and combustion decomposition products on the surface of the prefabricated electrode sheet, thereby facilitating heating of the prefabricated electrode sheet and improving the efficiency of electrode heating. Furthermore, hot air treatment can be used to clean impurities and combustion decomposition products on the surface of the prefabricated electrode sheet, thereby reducing the resistance of the electrode sheet and increasing its porosity, thereby improving its performance.

[0233] In some embodiments, along the thickness direction of the prefabricated pole piece, the distance between the hot air nozzle and the surface of the film layer is the same as the distance between the heating unit and the surface of the film layer.

[0234] For example, Figure 5 shows an example of a hot air nozzle arrangement. The hot air nozzle can be arranged after the heating unit for the heat treatment. Alternatively, the hot air nozzle can also be arranged before the heating unit for the heat treatment.

[0235] In an embodiment of the present application, along the thickness direction of the prefabricated electrode, the distance between the hot air nozzle and the surface of the film layer is set to be the same as the distance between the heating unit and the surface of the film layer, which can simplify the structure of the equipment.

[0236] In some embodiments, the temperature of the hot air treatment is 300°C to 600°C.

[0237] As an example, the temperature of the hot air treatment may be 300° C., 400° C., 500° C., or 600° C. For another example, the temperature of the hot air treatment may also be within the range obtained by combining any two of the above values.

[0238] In the embodiment of the present application, by controlling the temperature of the hot air treatment within a reasonable range, the prefabricated electrode can be effectively hot-air treated, reducing the impact of too low a hot air treatment temperature on the heating treatment, thereby improving the performance of the electrode; on the other hand, it can also reduce unnecessary energy consumption caused by too high a hot air treatment temperature, saving the preparation cost of the electrode.

[0239] In some embodiments, the hot air treatment satisfies one or more of the following conditions: (1) the hot air flow rate of the hot air treatment is 50 L / min to 300 L / min; (2) the angle between the direction of the hot air nozzle and the thickness direction of the prefabricated electrode is 0° to 45°; (3) along the moving direction of the prefabricated electrode, the distance between the hot air nozzle and the heating unit is 5 mm to 15 mm.

[0240] As an example, the hot air flow rate of the hot air treatment can be 50 L / min, 100 L / min, 150 L / min, 200 L / min, 250 L / min or 300 L / min. Optionally, the hot air flow rate of the hot air treatment can also be within the range obtained by combining any two of the above values.

[0241] In this embodiment, the temperature of the hot air treatment can be adjusted by adjusting the hot air flow rate. By controlling the temperature of the hot air treatment within a reasonable range, the prefabricated electrode can be effectively hot-air treated.

[0242] As an example, the angle between the direction of the hot air nozzle and the thickness direction of the prefabricated pole piece can be 0, 15°, 30°, or 45°. Alternatively, the angle between the direction of the hot air nozzle and the thickness direction of the prefabricated pole piece can also be within the range obtained by combining any two of the above values.

[0243] In this embodiment, by controlling the angle between the direction of the hot air nozzle and the thickness direction of the prefabricated pole piece within a reasonable range, the prefabricated pole piece can be effectively hot-air treated.

[0244] As an example, along the moving direction of the prefabricated electrode sheet, the distance between the hot air nozzle and the heating unit may be 5 mm, 10 mm, or 15 mm. For another example, along the moving direction of the prefabricated electrode sheet, the distance between the hot air nozzle and the heating unit may also be within the range obtained by combining any two of the above values.

[0245] In this embodiment, by controlling the distance between the hot air nozzle and the heating unit along the moving direction of the prefabricated electrode piece within a reasonable range, the prefabricated electrode piece can be effectively subjected to hot air treatment.

[0246] During the hot air treatment process, by controlling at least one of the hot air flow rate, the angle of the hot air nozzle, and the distance between the hot air nozzle and the heating unit along the moving direction of the prefabricated electrode within a reasonable range, the prefabricated electrode can be effectively hot-air treated, thereby improving the performance of the electrode.

[0247] In some embodiments, the hot air treatment satisfies one or more of the following conditions: (1) the hot air flow rate of the hot air treatment is 50 L / min to 200 L / min; (2) the angle between the direction of the hot air nozzle and the thickness direction of the prefabricated electrode is 20° to 45°; (3) along the moving direction of the prefabricated electrode, the distance between the hot air nozzle and the heating unit is 8 mm to 12 mm.

[0248] Controlling the distance between the hot air nozzle and the heating unit along the moving direction of the prefabricated electrode and / or the angle of the hot air nozzle within the above range facilitates the installation of the hot air nozzle and can reduce excessive occupation of equipment space by the installation of the hot air nozzle.

[0249] On the other hand, controlling the hot air flow rate of the hot air treatment between 50L / min and 200L / min can reduce the energy consumption of the hot air treatment while meeting the temperature requirement of the hot air treatment to effectively perform hot air treatment on the prefabricated electrode.

[0250] In some embodiments, before the designated portion of the film layer is heated, the prefabricated electrode is subjected to one or more of the following treatments: drying, pressing, or cutting.

[0251] Generally speaking, after a film layer is formed on at least one surface of the current collector, the electrode is subjected to different treatments in a sequential order based on production requirements, such as drying, pressing, and cutting. In this case, when a certain treatment is performed, the other treatments preceding it can be considered completed. For example, when cutting is performed, the drying and pressing processes can be considered completed.

[0252] The drying process can remove the solvent and moisture in the film layer (slurry).

[0253] The electrode sheets are usually loose after drying. If used directly, the film layer of the electrode sheet will easily fall off and be damaged after being soaked by the electrolyte. Therefore, the dried electrode sheets can be pressed using a roller machine or a tablet press, such as cold pressing.

[0254] The cutting process may include at least one of a pre-slitting process, a die-cutting process, or a slitting process.

[0255] To ensure production efficiency, multiple strips are usually coated on the current collector during coating, leaving the current collector uncoated with active material on both sides of the strip. Pre-slitting is usually performed first to separate the multiple strips into individual strips.

[0256] Die cutting refers to cutting out the shape of the pole ears on both sides of the pole strip.

[0257] The slitting process refers to slitting from the middle of the pole strip to form a pole piece with a pole ear on one side.

[0258] In an embodiment of the present application, the prefabricated electrode can first be subjected to one or more of the following treatments: drying, pressing, and cutting. Then, the prefabricated electrode can be heated. The production process of the electrode can be flexibly adjusted based on production requirements, production site, etc.

[0259] In some embodiments, the designated portion includes a portion between the surface of the film layer and one-third of the thickness close to the surface of the film layer.

[0260] That is, the designated portion may be a portion between the surface of the film layer and one third of the thickness close to the surface of the film layer.

[0261] In an embodiment of the present application, by heating the area between the surface of the film layer and one-third of the thickness near the surface of the film layer, the degree of softening or ablation of the adhesive in the film layer can be increased, the porosity of the electrode can be increased, the infiltration rate of the electrolyte can be increased, and thus the transmission rate of lithium ions can be increased.

[0262] FIG6 is a schematic diagram of a battery cell provided in an embodiment of the present application.

[0263] The battery cell 600 generally includes a positive electrode sheet, a negative electrode sheet, an electrolyte, a separator, etc. During the battery charge and discharge process, active ions are embedded in and out of the positive electrode sheet and the negative electrode sheet.

[0264] The positive electrode sheet and the negative electrode sheet can be obtained by the preparation method of the electrode sheet provided in the embodiment of the present application. The content of the electrode sheet can be referred to the relevant description above, and this application will not elaborate on it here.

[0265] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0266] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0267] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, or lithium tetrafluorooxalatophosphate.

[0268] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone, or diethyl sulfone.

[0269] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0270] The separator is placed between the positive and negative electrodes to prevent short circuits between the positive and negative electrodes while allowing ions to pass through. This application does not specifically limit the type of separator; for example, it can be a porous structure separator with good chemical and mechanical stability.

[0271] In some embodiments, the material of the separator can include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, or polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0272] In some embodiments, the outer packaging of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the battery cell can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, or polybutylene succinate.

[0273] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square, or any other shape.

[0274] Figure 7 shows an example battery module 700. Referring to Figure 7 , in the battery module 700, multiple battery cells 700 may be arranged sequentially along the length of the battery module 700. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells 600 may be secured together using fasteners.

[0275] In one embodiment, the battery module 700 may further include a housing having an accommodation space, and the plurality of battery cells 600 may be accommodated in the accommodation space.

[0276] In one embodiment, the battery modules 700 may be assembled into a battery. The battery may contain one or more battery modules 700. The specific number may be selected by those skilled in the art based on the application and capacity of the battery.

[0277] Figures 8 and 9 illustrate an example battery 800. Referring to Figures 8 and 9, battery 800 may include a battery box and multiple battery modules 700 disposed within the box. The battery box includes an upper box body 801 and a lower box body 802. The upper box body 801 can be placed over the lower box body 802 to form an enclosed space for accommodating the battery modules 700. The multiple battery modules 700 can be arranged in any manner within the battery box.

[0278] It should be understood that in other embodiments, the battery 800 is also referred to as a battery pack. The battery cells 600 may be first assembled into the battery module 700, and the battery 800 may be composed of the battery module 700. Alternatively, the battery 800 may be directly assembled from the battery cells 600, omitting the intermediate battery module 700.

[0279] In addition, the present application also provides an electrical device, which includes at least one of the battery cell 600, battery module 700, or battery 800 provided in the present application. The battery cell 600, battery module 700, or battery 800 can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, or an energy storage system.

[0280] The electric device may select the battery cell 600 , the battery module 700 or the battery 800 according to its usage requirements.

[0281] As an example, the electric device may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the electric device's requirements for high power and high energy density of secondary batteries, a battery pack or battery module may be used.

[0282] As another example, the power-consuming device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be lightweight and thin, and may use a secondary battery as a power source.

[0283] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0284] [Examples 1-20 and Comparative Examples 1-3]

[0285] Example 1

[0286] (1) Preparation of positive electrode sheet

[0287] The positive electrode active material, lithium nickel cobalt manganese oxide (nickel, cobalt, and manganese molar ratio of 8:1:1), the conductive agent, carbon black, and the binder, polyimide, were weighed in a mass ratio of 97:1:2 and dissolved in N-methylpyrrolidone (NMP) solvent. The mixture was thoroughly stirred and mixed to produce a positive electrode slurry. The slurry was then evenly coated on both sides of a 13μm thick positive electrode current collector aluminum foil along its thickness. After drying, cold pressing, and cutting, a positive electrode sheet with a total thickness of 140μm and a width of 100mm was obtained.

[0288] (2) Preparation of negative electrode sheet

[0289] The negative electrode active material artificial graphite, conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) were weighed according to a mass ratio of 95:1:2:2 and dissolved in solvent deionized water. The mixture was mixed evenly to prepare a negative electrode slurry. The negative electrode slurry was evenly coated on both sides of the negative electrode current collector copper foil with a thickness of 8 μm along its thickness direction. After drying, cold pressing, and cutting, a prefabricated negative electrode sheet with a total thickness of 70 μm and a width of 105 μm was obtained.

[0290] The prefabricated negative electrode sheet is placed on a conveying unit so that the conveying unit drives the prefabricated negative electrode sheet to move, and the prefabricated negative electrode sheet passes through a plasma heating unit to heat the prefabricated negative electrode sheet, so that the temperature of the film surface of the prefabricated negative electrode sheet reaches 300° C. at 50 ms. The plasma heating temperature is 1000° C., the moving speed of the prefabricated negative electrode sheet is 80 m / min, the distance between the plasma gun of the plasma heating unit and the film surface along the thickness direction of the prefabricated negative electrode sheet is 25 mm, the flow rate of the ionized gas to be ionized during plasma heating is 10 L / min, the heating power of the plasma heating unit is 500 W, and the angle between the direction of the plasma gun of the heating unit and the thickness direction of the prefabricated negative electrode sheet is 60°.

[0291] (3) Preparation of battery cells

[0292] The positive electrode sheet, polyethylene separator, and heat-treated negative electrode sheet are stacked in order so that the separator is located between the positive electrode sheet and the negative electrode sheet and can isolate the positive electrode sheet from the negative electrode sheet; the stacked components are then wound to obtain an electrode assembly; the electrode assembly is placed in a shell, dried, and then injected with an 11% by mass LiPF6 electrolyte, wherein the volume ratio of the organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in the electrolyte is 3:7; and after processes such as formation and standing, a battery cell is obtained.

[0293] Example 2

[0294] Compared to Example 1, Example 2 changed the heating time (specified time) of the prefabricated negative electrode sheet during the heating process. Specifically, the surface temperature of the film layer of the prefabricated negative electrode sheet reached 300°C at 150ms. Accordingly, the moving speed of the prefabricated negative electrode sheet during the heating process was changed to 50m / min.

[0295] Example 3

[0296] Compared with Example 1, Example 3 changes the heating temperature (specified temperature) of the prefabricated negative electrode sheet during the heating process, that is, the temperature of the film surface of the prefabricated negative electrode sheet reaches 700°C at 50ms. Accordingly, compared with Example 1, the heating temperature of the negative electrode sheet can be matched by adjusting some parameters of plasma heating: the plasma heating temperature is adjusted to 1200°C, the distance between the plasma gun of the plasma heating unit and the film surface along the thickness direction of the prefabricated negative electrode sheet is adjusted to 5mm, the flow rate of the ionized gas to be heated in the plasma heating is adjusted to 100L / min, the heating power of the plasma heating unit is adjusted to 15000W, and the angle between the direction of the plasma gun of the heating unit and the thickness direction of the prefabricated negative electrode sheet is adjusted to 0°.

[0297] Example 4

[0298] Compared to Example 3, Example 4 changes the heating time (specified time) of the prefabricated negative electrode sheet during the heating process. That is, the temperature of the film surface of the negative electrode sheet reaches 700°C at 200ms. Accordingly, compared to Example 3, the heating time of the negative electrode sheet can be matched by adjusting some parameters of the plasma heating: the plasma heating temperature is adjusted to 1100°C, and the moving speed of the prefabricated negative electrode sheet is adjusted to 25m / min.

[0299] Example 5

[0300] Compared with Example 1, Example 5 changes the heating treatment method of the prefabricated negative electrode sheet, as well as the heating time (specified time) and heating temperature (specified temperature) of the prefabricated negative electrode sheet during the heating treatment. That is, in Example 5, during the movement of the prefabricated negative electrode sheet, the prefabricated negative electrode sheet passes through the arc heating unit to heat the prefabricated negative electrode sheet, so that the temperature of the film surface of the prefabricated negative electrode sheet reaches 500°C at 15ms. Among them, the arc heating temperature is 1600°C, the moving speed of the prefabricated negative electrode sheet is 200m / min, the distance between the arc heating head of the arc heating unit and the film surface along the thickness direction of the prefabricated negative electrode sheet is 150mm, the gas flow rate of the arc heating is 30L / min, the heating power of the arc heating unit is 1000W, and the angle between the direction of the arc heating unit and the thickness direction of the prefabricated negative electrode sheet is 60°.

[0301] Example 6

[0302] Compared to Example 5, Example 6 changed the heating time (specified time) of the prefabricated negative electrode sheet during the heating process. Specifically, the surface temperature of the film layer of the prefabricated negative electrode sheet reached 500°C at 50ms. Accordingly, the moving speed of the prefabricated negative electrode sheet during the heating process was changed to 160m / min.

[0303] Example 7

[0304] Compared with Example 5, Example 7 changes the heating temperature (specified temperature) of the prefabricated negative electrode sheet during the heating process, that is, the temperature of the film surface of the prefabricated negative electrode sheet reaches 900°C at 15ms. Accordingly, compared with Example 5, the heating temperature of the prefabricated negative electrode sheet can be matched by adjusting some parameters of the arc heating: the arc heating temperature is adjusted to 2000°C, the distance between the arc heating head of the arc heating unit and the film surface along the thickness direction of the prefabricated negative electrode sheet is adjusted to 80mm, the flow rate of the gas to be ionized during arc heating is adjusted to 80L / min, the heating power of the arc heating unit is adjusted to 8000W, and the angle between the direction of the arc gun of the heating unit and the thickness direction of the prefabricated negative electrode sheet is adjusted to 0°.

[0305] Example 8

[0306] Compared with Example 1, Example 8 changes the method of heating the prefabricated negative electrode sheet, as well as the heating time (specified time) and heating temperature (specified temperature) of the prefabricated negative electrode sheet during the heating process. That is, in Example 8, during the movement of the prefabricated negative electrode sheet, the prefabricated negative electrode sheet passes through the infrared heating unit to heat the prefabricated negative electrode sheet, so that the temperature of the film surface of the prefabricated negative electrode sheet reaches 400°C at 20ms. Among them, the infrared heating temperature is 1400°C, the moving speed of the prefabricated negative electrode sheet is 160m / min, the distance between the heating tube of the infrared heating unit and the film surface along the thickness direction of the prefabricated negative electrode sheet is 50mm, and the heating power of the infrared heating unit is 1000W.

[0307] Example 9

[0308] Compared to Example 8, Example 9 changed the heating time (specified time) of the prefabricated negative electrode sheet during the heating process. Specifically, the surface temperature of the film layer of the prefabricated negative electrode sheet reached 400°C at 60ms. Accordingly, the moving speed of the prefabricated negative electrode sheet during the heating process was changed to 120m / min.

[0309] Example 10

[0310] Compared to Example 8, Example 10 changes the heating temperature (specified temperature) of the prefabricated negative electrode sheet during the heating process. That is, the temperature of the film surface of the prefabricated negative electrode sheet reaches 900°C at 20ms. Accordingly, compared to Example 8, the heating temperature of the prefabricated negative electrode sheet can be matched by adjusting certain infrared heating parameters: the infrared heating temperature is adjusted to 1800°C, the distance between the heating lamps of the infrared heating unit and the film surface along the thickness direction of the prefabricated negative electrode sheet is adjusted to 5mm, and the heating power of the infrared heating unit is adjusted to 5000W.

[0311] Example 11

[0312] Compared with Example 1, Example 11 changes the method of heating the prefabricated negative electrode sheet, as well as the heating time (specified time) and heating temperature (specified temperature) of the prefabricated negative electrode sheet during the heating process. That is, in Example 11, during the movement of the prefabricated negative electrode sheet, the prefabricated negative electrode sheet passes through the electric heating unit to perform infrared heating treatment on the prefabricated negative electrode sheet, so that the temperature of the film surface of the prefabricated negative electrode sheet reaches 300°C at 90ms. Among them, the electric heating temperature is 1000°C, the moving speed of the prefabricated negative electrode sheet is 80m / min, the distance between the resistance wire of the electric heating unit and the film surface along the thickness direction of the prefabricated negative electrode sheet is 25mm, and the heating power of the infrared heating unit is 500W.

[0313] Example 12

[0314] Compared to Example 11, Example 12 changed the heating time (specified time) of the prefabricated negative electrode sheet during the heating process. Specifically, the surface temperature of the film layer of the prefabricated negative electrode sheet reached 300°C at 150ms. Accordingly, the moving speed of the prefabricated negative electrode sheet during the heating process was changed to 50m / min.

[0315] Example 13

[0316] Compared to Example 11, Example 13 changes the heating temperature (specified temperature) of the prefabricated negative electrode sheet during the processing process. That is, the temperature of the film surface of the prefabricated negative electrode sheet reaches 700°C at 90ms. Accordingly, compared to Example 11, some parameters of the electric heating can be adjusted to match the heating temperature of the prefabricated negative electrode sheet: the electric heating temperature is adjusted to 1300°C, the distance between the resistance wire of the electric heating unit and the film surface along the thickness direction of the prefabricated negative electrode sheet is adjusted to 5mm, and the heating power of the electric heating unit is adjusted to 14000W.

[0317] Example 14

[0318] Compared with Example 1, Example 14 changes the method of heating the prefabricated negative electrode plate, as well as the heating time (specified time) and heating temperature (specified temperature) of the prefabricated negative electrode plate during the heating process. That is, in Example 13, during the movement of the prefabricated negative electrode plate, the prefabricated negative electrode plate is passed through the magnetron of the microwave heating unit to perform microwave heating on the prefabricated negative electrode plate, so that the temperature of the film surface of the prefabricated negative electrode plate reaches 300°C at 50ms. The microwave heating temperature is 1300°C, the movement speed of the prefabricated negative electrode plate is 120m / min, the distance between the magnetron of the microwave heating unit and the film surface along the thickness direction of the prefabricated negative electrode plate is 25mm, and the heating power of the microwave heating unit is 2000W.

[0319] Example 15

[0320] Compared to Example 14, Example 15 changed the temperature rise time (specified time) during the heating process of the prefabricated negative electrode sheet. Specifically, the surface temperature of the film layer of the prefabricated negative electrode sheet reached 300°C at 120ms. Accordingly, the moving speed of the prefabricated negative electrode sheet during the heating process was changed to 80m / min.

[0321] Example 16

[0322] Compared to Example 14, Example 16 changes the heating temperature (specified temperature) of the prefabricated negative electrode plate during the heating process. That is, the temperature of the film surface of the prefabricated negative electrode plate reaches 800°C at 50ms. Accordingly, compared to Example 14, the heating temperature of the prefabricated negative electrode plate can be matched by adjusting certain microwave heating parameters: the microwave heating temperature is adjusted to 1800°C, the distance between the magnetron of the microwave heating unit and the film surface along the thickness direction of the prefabricated negative electrode plate is adjusted to 5mm, and the heating power of the microwave heating unit is adjusted to 10,000W.

[0323] Example 17

[0324] Compared with Example 1, Example 17 adds a hot air treatment for the prefabricated negative electrode sheet. The hot air treatment temperature is 300°C, the hot air flow rate is 50 L / min, the angle between the hot air nozzle and the thickness direction of the prefabricated negative electrode sheet is 45°, the distance between the hot air nozzle and the heating unit along the movement direction of the prefabricated negative electrode sheet is 5 mm, and along the thickness direction of the prefabricated negative electrode sheet, the distance between the hot air nozzle and the film surface is the same as the distance between the heating unit and the film surface.

[0325] Example 18

[0326] Compared with Example 17, Example 18 changes the temperature of the hot air treatment to 600° C. Accordingly, the hot air flow rate of the hot air treatment is adjusted to 300 L / min to match the temperature adjustment of the hot air treatment.

[0327] Example 19

[0328] Compared with Example 17, in Example 19, the angle between the direction of the hot air nozzle and the thickness direction of the prefabricated negative electrode sheet is adjusted to 0°.

[0329] Example 20

[0330] Compared with Example 17, in Example 20, the distance between the hot air nozzle and the heating unit along the moving direction of the prefabricated negative electrode sheet is adjusted to 15 mm.

[0331] Comparative Example 1

[0332] Compared with Example 1, the negative electrode sheet was not subjected to heat treatment in Comparative Example 1. That is, in Comparative Example 1, neither the positive electrode sheet nor the negative electrode sheet was subjected to heat treatment.

[0333] Comparative Example 2

[0334] Compared to Example 1, Comparative Example 2 changes the heating temperature of the prefabricated negative electrode sheet during the heating process. Specifically, in Comparative Example 2, the positive electrode sheet is not heated; instead, during the movement of the prefabricated negative electrode sheet, the prefabricated negative electrode sheet is passed through a plasma heating unit for heating, such that the surface temperature of the film layer of the prefabricated negative electrode sheet reaches 250°C at 50ms. Accordingly, compared to Example 1, the heating temperature of the negative electrode sheet can be matched by adjusting certain plasma heating parameters: the plasma heating temperature is adjusted to 800°C, the flow rate of the ionized gas to be heated during the plasma heating is adjusted to 8L / min, the heating power of the plasma heating unit is adjusted to 400W, and the angle between the orientation of the plasma gun of the heating unit and the thickness direction of the negative electrode sheet is adjusted to 70°.

[0335] Comparative Example 3

[0336] Compared to Example 1, Comparative Example 3 changes the heating time and temperature during the heating process of the prefabricated negative electrode sheet. Specifically, in Comparative Example 3, the positive electrode sheet is not heated; while the negative electrode sheet is moving, it passes through a plasma heating unit for heating, with the film surface temperature of the prefabricated negative electrode sheet reaching 80°C at 10ms. Accordingly, the heating time and temperature of the negative electrode sheet can be matched by adjusting certain plasma heating parameters: the plasma heating temperature is adjusted to 1200°C, the movement speed of the negative electrode sheet is adjusted to 200 m / min, the distance between the plasma heating unit's plasma gun and the film surface along the thickness direction of the sheet is adjusted to 5 mm, the flow rate of the ionized gas to be heated during the plasma heating is adjusted to 100 L / min, the heating power of the plasma heating unit is adjusted to 15,000 W, and the angle between the orientation of the plasma gun of the heating unit and the thickness direction of the sheet is adjusted to 0°.

[0337] The parameter settings for preparing the negative electrode sheets in the specific embodiments and comparative examples are shown in Tables 1 to 7.

[0338] Table 1 Parameter settings for Examples 1 to 4

[0339] Table 2 Parameter settings of Examples 5 to 7

[0340] Table 3 Parameter settings of Examples 8 to 10

[0341] Table 4 Parameter settings of Examples 11 to 13

[0342] Table 5 Parameter settings of Examples 14 to 16

[0343] Table 6 Parameter settings of Example 17 and Example 20

[0344] Table 7 Parameter settings of Comparative Examples 1 to 3

[0345] In Tables 1 to 7, T1 is the specified temperature, and t is the specified time. That is, the surface of the film reaches the specified temperature of T1 at the specified time t. T2 is the temperature of the heating treatment, V is the speed of the prefabricated negative electrode sheet, D is the distance between the heating unit and the surface of the film along the thickness direction of the prefabricated negative electrode sheet, L1 is the flow rate of the ionized gas for plasma heating or the flow rate of the gas for arc heating, P is the heating power of the heating unit under different heating methods, α is the angle between the orientation of the heating unit and the thickness direction of the prefabricated negative electrode sheet. T3 is the temperature of the hot air treatment, L2 is the hot air flow rate of the hot air treatment, β is the angle between the orientation of the hot air nozzle and the thickness direction of the prefabricated negative electrode sheet, d1 is the distance between the hot air nozzle and the heating unit along the direction of movement of the prefabricated negative electrode sheet, and d2 is the distance between the hot air nozzle and the surface of the film along the thickness direction of the prefabricated negative electrode sheet.

[0346] The negative electrode sheets and battery cells obtained in Examples 1 to 20 and Comparative Examples 1 to 3 were subjected to the following performance tests:

[0347] (1) Electrode resistance

[0348] Use a Yuanneng Technology Sheet Resistor Tester to test the sheet resistance. Cut small discs with a diameter of 10 mm from the left, center, and right sides of the electrode. Turn on the Yuanneng Technology Sheet Resistor Tester indicator, place the small disc in the appropriate position on the probe, click the "Start" button, and wait for the display to stabilize before reading. Test two positions on each disc. Calculate the average of the six measurements to obtain the sheet resistance for that electrode.

[0349] (2) Electrolyte absorption time of the electrode

[0350] Fix the electrode on a clean glass plate, use a capillary with an inner diameter of 0.3mm to absorb the electrolyte at a height of 3mm (the electrolyte composition includes EC, DMC and EMC with a volume ratio of 3:2:1, and 1mol / L lithium salt LiPF6), then vertically contact the capillary with the electrode to allow the electrode to absorb the electrolyte, and measure the time it takes for the electrode to completely absorb the electrolyte.

[0351] (3) Battery cell capacity

[0352] The battery cells were charged at a constant current of 1C to the charge cut-off voltage (about 4.2V) at 25°C. After being left at 25°C for 1 hour, they were discharged at a constant current of 1C to the discharge cut-off voltage (about 2.5V), and the discharged capacity was recorded.

[0353] (4) First effect of battery cells

[0354] At 25°C, charge the battery cells for the first time using a 1C constant current to the charge cutoff voltage (approximately 4.2V) and record the charged capacity. After standing at 25°C for 1 hour, discharge the cells using a 1C constant current to the discharge cutoff voltage (approximately 2.5V) and record the discharged capacity. Calculate the ratio of the first discharge capacity to the first charge capacity.

[0355] (5) Battery cell K value

[0356] Charge the battery cell to 20% of its capacity, then record the cell voltage (OCV1). Afterwards, allow the cell to rest at 25°C for 48 hours, and again measure the cell voltage (OCV2). The K value is (OCV1 - OCV2) / 48, expressed in mV / h. When charging, the cell's initial full charge capacity is used as the cell capacity. When discharging, the cell's initial full discharge capacity is used as the cell capacity.

[0357] The performance test results of the electrode sheets and battery cells of the above-mentioned Examples 1 to 20 and Comparative Examples 1 to 3 are detailed in Table 8.

[0358] Table 8 Performance test results of pole pieces and battery cells in different embodiments and comparative examples

[0359] The negative electrode sheets prepared in Examples 1 to 20 have lower sheet resistance than that of Comparative Examples 1 to 3, and the electrolyte absorption time is shorter than that of Comparative Examples 1 to 3. The capacity and first efficiency of the battery cells prepared using the negative electrode sheets in Examples 1 to 20 are higher than those of the battery cells prepared using the negative electrode sheets in Comparative Examples 1 to 3, and the K value of the battery cells prepared using the negative electrode sheets in Examples 1 to 20 is lower than that of the battery cells prepared using the negative electrode sheets in Comparative Examples 1 to 3.

[0360] Examples 1 to 4, Examples 5 to 7, Examples 8 to 10, Examples 11 to 13, and Examples 14 to 16 respectively adopt plasma heating, arc heating, infrared heating, electric heating, and microwave heating as heating methods.

[0361] In the embodiments of the present application, heat treatment of the prefabricated negative electrode sheet can reduce the sheet resistance of the negative electrode sheet, facilitate lithium ion transmission, and thus improve battery performance. For example, heat treatment can improve the degree of graphitization and graphite orientation of the negative electrode sheet, remove impurities on the surface of the negative electrode sheet, and reduce the resistance of the negative electrode sheet.

[0362] Under the action of high temperature, burrs, particles, etc. generated by cutting of the prefabricated negative electrode sheet can also be ablated. On the one hand, the sharpness of the surface of the negative electrode sheet can be reduced, thereby reducing the risk of puncture of the isolation membrane, and thus improving the K value of the battery (voltage drop per unit time); on the other hand, reducing the ablation of burrs, particles and other impurities can reduce side reactions on the surface of the negative electrode sheet, making the SEI film on the surface of the negative electrode sheet more stable, thereby improving the capacity and initial efficiency of the battery cell prepared by the negative electrode sheet.

[0363] In the embodiments of the present application, increasing the temperature of the prefabricated negative electrode plate can soften or ablate the binder in the plate, thereby removing some of the binder and increasing the plate's porosity. This increased porosity increases the number of channels for electrolyte infiltration in the plate, increasing the electrolyte infiltration rate, thereby increasing the lithium ion transmission rate and, consequently, improving battery performance.

[0364] Compared with Example 1, Examples 17 to 20 also perform hot air treatment on the prefabricated negative electrode sheets during the heat treatment process. The negative electrode sheets prepared in Examples 17 to 20 have a sheet resistance that is substantially lower than that of Example 1, and the electrolyte absorption time is substantially shorter than that of Example 1. The capacity and first efficiency of the battery cells prepared from the negative electrode sheets in Examples 17 to 20 are substantially higher than those of the battery cells prepared from the negative electrode sheets in Example 1, and the K value of the battery cells prepared from the negative electrode sheets in Examples 17 to 20 is slightly lower than the K value of the battery cells prepared from the negative electrode sheets in Example 1.

[0365] This is because hot air treatment can further clean impurities, combustion decomposition products, etc. on the surface of the prefabricated negative electrode, improve the cleanliness of the surface of the electrode, and then reduce the resistance of the electrode, increase the porosity of the surface of the electrode, thereby increasing the electrolyte absorption rate (reducing the absorption time), and then increasing the lithium ion transmission rate and improving the performance of the battery.

[0366] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing a pole piece, characterized in that: include: preparing a film layer including an active material and a binder on at least one surface of a current collector to obtain a prefabricated electrode sheet; A specified portion of the film layer is subjected to heat treatment so that the specified portion is heated to a specified temperature within a specified time, wherein the specified portion includes at least a portion of the surface of the film layer, the specified time is greater than or equal to 15 ms, and the specified temperature is greater than or equal to 285°C.

2. The preparation method according to claim 1, characterized in that The specified time is 15ms to 150ms, and the specified temperature is 300°C to 900°C.

3. The preparation method according to claim 1 or 2, characterized in that A heating unit is provided relative to the surface of the film layer along the thickness direction of the prefabricated electrode piece, and the heating unit is used to heat the designated portion, wherein the distance between the heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode piece is 5 mm to 150 mm, and / or, The temperature of the heating treatment is 1000°C to 2000°C.

4. The preparation method according to claim 3, characterized in that Before performing heat treatment on the designated portion of the film layer, the method further comprises: moving the prefabricated electrode piece by using a conveying unit; The heating treatment of the designated portion of the film layer comprises: The heating unit is used to perform the heating treatment on the designated portion during the movement of the prefabricated electrode piece. The heating unit is fixedly arranged between the movement starting point and the movement end point of the prefabricated electrode piece.

5. The preparation method according to claim 4, characterized in that The moving speed of the prefabricated pole piece is 50m / min to 200m / min.

6. The preparation method according to any one of claims 1 to 5, characterized in that The heating treatment includes at least one of flame combustion heating, electromagnetic induction heating, laser heating, plasma heating, arc heating, infrared heating, electric heating or microwave heating.

7. The preparation method according to any one of claims 3 to 6, characterized in that The heating treatment of the designated portion of the film layer includes: performing plasma heating on the designated portion, so that the temperature of the designated portion is raised to 300° C. to 700° C. within 50ms to 150ms.

8. The preparation method according to claim 7, characterized in that The distance between the plasma heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode piece is 5 mm to 25 mm, and / or, The plasma heating temperature is 1000° C. to 1200° C., and / or, The moving speed of the prefabricated electrode is 50m / min to 80m / min, wherein the heating unit includes the plasma Sub-heating unit.

9. The preparation method according to claim 7 or 8, characterized in that The plasma heating satisfies one or more of the following conditions: (1) The flow rate of the gas to be ionized by the plasma heating is 10 L / min to 100 L / min; (2) The heating power of the plasma heating unit is 500W to 15000W; (3) The angle between the direction of the plasma heating unit and the thickness direction of the prefabricated electrode is 0° to 60°.

10. The preparation method according to any one of claims 3 to 6, characterized in that The heating treatment of the designated portion of the film layer includes: arc heating the designated portion to raise the temperature of the designated portion to 500° C. to 900° C. within 15 ms to 50 ms.

11. The preparation method according to claim 10, characterized in that: The distance between the arc heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode piece is 80 mm to 150 mm, and / or, The arc heating temperature is 1600° C. to 2000° C., and / or, The moving speed of the prefabricated pole piece is 160 m / min to 200 m / min, wherein the heating unit includes the arc heating unit.

12. The preparation method according to claim 10 or 11, characterized in that: The arc heating satisfies one or more of the following conditions: (1) The gas flow rate of the arc heating unit is 30L / min to 80L / min; (2) The heating power of the arc heating unit is 1000W to 8000W; (3) The angle between the direction of the arc heating unit and the thickness direction of the prefabricated electrode is 0° to 60°.

13. The preparation method according to any one of claims 3 to 6, characterized in that The heating treatment of the designated portion of the film layer includes: performing infrared heating on the designated portion, so that the temperature of the designated portion is raised to 400° C. to 900° C. within 20ms to 60ms.

14. The preparation method according to claim 13, characterized in that The distance between the infrared heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode is 5 mm to 50 mm, and / or, The infrared heating temperature is 1400° C. to 1800° C., and / or, The moving speed of the prefabricated pole piece is 120 m / min to 160 m / min, wherein the heating unit includes the infrared heating unit.

15. The preparation method according to claim 13 or 14, characterized in that: The infrared heating meets the following conditions: the heating power of the infrared heating unit is 1000W to 5000W.

16. The preparation method according to any one of claims 3 to 6, characterized in that The heating treatment of the designated portion of the film layer includes: electrically heating the designated portion so that the temperature of the designated portion is raised to 300° C. to 700° C. within 90ms to 150ms.

17. The preparation method according to claim 16, characterized in that The distance between the electric heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode piece is 5 mm to 25 mm, and / or, The temperature of the electric heating is 1000°C to 1300°C, and / or, The moving speed of the prefabricated pole piece is 50 m / min to 80 m / min, wherein the heating unit includes the electric heating unit.

18. The preparation method according to claim 16 or 17, characterized in that: The electric heating meets the following conditions: the heating power of the electric heating unit is 500W to 14000W.

19. The preparation method according to any one of claims 3 to 6, characterized in that The heating treatment of the designated portion of the film layer includes: performing microwave heating on the designated portion, so that the temperature of the designated portion is raised to 300° C. to 800° C. within 50 ms to 120 ms.

20. The preparation method according to claim 19, characterized in that The distance between the microwave heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode piece is 5 mm to 25 mm, and / or, The microwave heating temperature is 1300° C. to 1800° C., and / or, The moving speed of the prefabricated pole piece is 80 m / min to 120 m / min, wherein the heating unit includes the microwave heating unit.

21. The preparation method according to claim 19 or 20, characterized in that: The microwave heating meets the following conditions: the heating power of the microwave heating unit is 2000W to 10000W.

22. The preparation method according to any one of claims 1 to 21, characterized in that The method further comprises: During the process of performing the heating treatment on the designated portion, the designated portion is subjected to hot air treatment using a hot air nozzle, the hot air nozzle is fixedly arranged between the moving starting point and the moving end point of the prefabricated electrode, and the hot air nozzle is arranged relative to the surface of the film layer along the thickness direction of the prefabricated electrode.

23. The preparation method according to claim 22, characterized in that Along the thickness direction of the prefabricated electrode sheet, the distance between the hot air nozzle and the surface of the film layer is the same as the distance between the heating unit and the surface of the film layer.

24. The preparation method according to claim 22 or 23, characterized in that: The temperature of the hot air treatment is 300°C to 600°C.

25. The preparation method according to any one of claims 22 to 24, characterized in that The hot air treatment satisfies one or more of the following conditions: (1) The hot air flow rate of the hot air treatment is 50L / min to 300L / min; (2) The angle between the direction of the hot air nozzle and the thickness direction of the prefabricated electrode is 0° to 45°; (3) Along the moving direction of the prefabricated electrode, the distance between the hot air nozzle and the heating unit is 5mm~15mm.

26. The preparation method according to claim 25, characterized in that The hot air treatment satisfies one or more of the following conditions: (1) The hot air flow rate of the hot air treatment is 50L / min to 200L / min; (2) The angle between the direction of the hot air nozzle and the thickness direction of the prefabricated electrode is 20° to 45°; (3) Along the moving direction of the prefabricated electrode, the distance between the hot air nozzle and the heating unit is 8 mm to 12 mm.

27. The preparation method according to any one of claims 1 to 26, characterized in that Before heat-treating the designated portion of the film layer, the method further comprises: The prefabricated electrode is subjected to one or more of the following treatments: drying, pressing or cutting.

28. The preparation method according to any one of claims 1 to 27, characterized in that The designated portion includes a portion between the surface of the film layer and one-third of the thickness close to the surface of the film layer.

29. A pole piece, characterized in that: The pole piece is prepared according to the preparation method according to any one of claims 1 to 28.

30. A battery, characterized in that: The battery comprises the pole piece according to claim 29.

31. An electrical device, characterized in that: The electrical device comprises the battery according to claim 30.

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