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

Abstract

The embodiment of the invention provides a preparation method of a pole piece, the pole piece, a battery and an electric device, the preparation method comprises the following steps: 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; the specified part of the film layer is heated, the temperature of the specified part is increased to the specified temperature within the specified time, the specified part comprises at least part of the surface of the film layer, the specified time is larger than or equal to 15 ms, and the specified temperature is larger than or equal to 285 DEG C. According to the preparation method of the pole piece, the pole piece, the battery and the electric device provided by the embodiment of the invention, the performance of the pole piece can be improved, and the performance and the service life of the battery and the electric device using the pole piece are improved.

Description

Technical Field

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

[0002] Battery technology is an important factor in the development of the new energy industry. With the continuous in-depth research on batteries and the continuous improvement of market demand, higher requirements are put forward for various performances of batteries, such as the energy density, cycle life, reliability, etc. of the batteries.

[0003] As an important component of the battery, the pole piece provides the active material for the battery to carry out chemical reactions and conducts electrons, playing a key role in the performance and life of the battery. For example, the wetting performance, internal resistance, etc. of the pole piece affect the performance of the battery, such as impedance, self-discharge, etc. Therefore, the performance and service life of the battery can be improved by enhancing the performance of the pole piece. Summary of the Invention

[0004] The embodiments of the present application provide a method for preparing a pole piece, a pole piece, a battery, and an electrical device using the same, which can improve the performance of the pole piece, thereby improving the performance and service life of the battery and the electrical device using the pole piece.

[0005] In a first aspect, a method for preparing a pole piece is provided, including: preparing a film layer including 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 part of the film layer to raise the temperature of the specified part to a specified temperature within a specified time, where the specified part includes at least a part 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.

[0006] In the embodiments of the present application, during the process of performing a heat treatment on the specified part of the film layer of the prefabricated pole piece, by controlling the specified time to be more than 15 ms and the specified temperature to be more than 285 °C, the sheet resistance of the pole piece can be reduced, which is beneficial to the transmission of lithium ions, thereby improving the performance of the battery. For example, for the positive pole piece, the residual solvent, impurities, etc. on the surface of the pole piece can be removed by heat treatment, reducing the resistance of the positive pole piece; for the negative pole piece, the graphitization degree, the orientation degree of graphite, and the impurities on the surface of the negative pole piece can be improved by heat treatment, reducing the resistance of the negative pole piece.

[0007] In addition, under the action of high temperature, burrs, particulate matters, etc. generated on the surface of the prefabricated electrode due to cutting can be ablated. On the one hand, the sharpness of the electrode surface can be reduced, thereby reducing the risk of the separator being punctured, and further improving the K value (voltage drop per unit time) of the battery. On the other hand, the ablation of impurities such as burrs and particulate matters can reduce the 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 from the electrode.

[0008] In the embodiment of the present application, when the temperature of the prefabricated electrode rises, the binder in the electrode can be softened or ablated, so that part of the binder in the electrode can be removed, and the porosity of the electrode can be improved. The increase in porosity can increase the channels for electrolyte infiltration, improve the infiltration rate of the electrolyte, thereby increasing the transmission rate of lithium ions, and further improving the performance of the battery.

[0009] In a possible implementation, the specified time is 15 ms to 150 ms, and the specified temperature is 300 °C to 900 °C.

[0010] In the 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 15 ms to 150 ms, and the temperature of the specified part of the film layer rises rapidly, which can improve the performance of the electrode while improving the production efficiency of the electrode, thereby improving the performance of the battery.

[0011] In a possible implementation, a heating unit is arranged relative to the surface of the film layer along the thickness direction of the prefabricated electrode, and the heating unit is used to heat the specified part. 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 heat treatment is 1000 °C to 2000 °C.

[0012] In the embodiment of the present application, by arranging a heating unit along the thickness direction of the prefabricated electrode and controlling 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 within a reasonable range to heat the specified part of the film layer, at least part of the surface of the film layer can be heated such that the time is greater than or equal to 15 ms and the temperature rise is greater than or equal to 285 °C, improving the performance of the electrode, and thereby improving the performance of the battery.

[0013] In a possible implementation, before heating the specified part of the film layer, the method further includes: moving the prefabricated electrode by using a conveying unit; heating the specified part of the film layer includes: heating the specified part by using the heating unit during the movement of the prefabricated electrode, and the heating unit is fixedly arranged between the starting point and the ending point of the movement of the prefabricated electrode.

[0014] In the embodiments of the present application, during the movement of the prefabricated electrode sheet, the prefabricated electrode sheet can be heat-treated by using a heating unit fixedly arranged between the starting point and the ending point of the movement of the prefabricated electrode sheet, which can improve the performance of the electrode sheet while improving the production efficiency, thereby improving the performance of the battery.

[0015] In a possible implementation manner, the moving speed of the prefabricated electrode sheet is 50 m / min to 200 m / min.

[0016] In the embodiments of the present application, during the process of the prefabricated electrode sheet moving at a speed of 50 m / min to 200 m / min, the prefabricated electrode sheet can be effectively heated by using the heating unit, which can improve the performance of the electrode sheet while improving the production efficiency, thereby improving the performance of the battery.

[0017] In a possible implementation manner, the heat 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.

[0018] In the embodiments of the present application, the prefabricated electrode sheet can be heat-treated 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 as to flexibly select a heating method suitable for production conditions and production requirements, etc.

[0019] In a possible implementation manner, heat-treating a specified part of the film layer includes: performing plasma heating on the specified part to raise the temperature of the specified part to 300°C to 700°C within 50 ms to 150 ms.

[0020] In the embodiments of the present application, plasma heating can be performed on a specified part of the prefabricated electrode sheet so that the temperature of the specified part rises to 300°C to 700°C within a specified time of 50 ms to 150 ms, thereby improving the performance of the electrode sheet.

[0021] In a possible implementation manner, the distance between the plasma heating unit and the surface of the film layer in the thickness direction of the prefabricated electrode sheet 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 electrode sheet is 50 m / min to 80 m / min, wherein the heating unit includes a plasma heating unit.

[0022] In the embodiments of the present application, by setting one or more of the distance between the plasma heating unit and the surface of the film layer in the thickness direction of the prefabricated pole piece, the temperature of the plasma heating, and the moving speed of the prefabricated pole piece within a reasonable range, it is possible to make the specified part of the film layer reach a reasonable temperature range within a reasonable time range during the plasma heating process, for example, rise to 300°C to 700°C within 50 ms to 150 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0023] In a possible implementation manner, the plasma heating satisfies one or more of the following conditions: (1) the flow rate of the gas to be ionized for the 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 orientation of the plasma heating unit and the thickness direction of the prefabricated pole piece is 0° to 60°.

[0024] 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 pole piece within a reasonable range, it is convenient for the specified part of the film layer to reach a reasonable temperature range within a reasonable time range, for example, rise to 300°C to 700°C within 50 ms to 150 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0025] In a possible implementation manner, heating the specified part of the film layer includes: performing arc heating on the specified part to make the specified part rise to 500°C to 900°C within 15 ms to 50 ms.

[0026] In the embodiments of the present application, arc heating can be performed on the specified part of the prefabricated pole piece so that the specified part rises to 500°C to 900°C within the specified time of 15 ms to 50 ms, thereby improving the performance of the pole piece.

[0027] In a possible implementation manner, the distance between the arc heating unit and the surface of the film layer in the thickness direction of the prefabricated pole piece is 80 mm to 150 mm, and / or the temperature of the arc heating is 1600°C to 2000°C, and / or the moving speed of the prefabricated pole piece is 160 m / min to 200 m / min, where the heating unit includes an arc heating unit.

[0028] In the embodiments of the present application, by setting one or more of the distance between the arc heating unit and the surface of the film layer in the thickness direction of the prefabricated pole piece, the temperature of the arc heating, and the moving speed of the prefabricated pole piece within a reasonable range, it is possible to make the designated part of the film layer reach a reasonable temperature range within a reasonable time range during the arc heating process of the prefabricated pole piece. For example, it can be heated to 500°C - 900°C within 15 ms - 50 ms, achieving effective heating of the pole piece and improving the performance of the pole piece.

[0029] In a possible implementation manner, the arc heating satisfies one or more of the following conditions: (1) the gas flow rate of the arc heating unit is 30 L / min - 80 L / min; (2) the heating power of the arc heating unit is 1000 W - 8000 W; (3) the included angle between the orientation of the arc heating unit and the thickness direction of the prefabricated pole piece is 0° - 60°.

[0030] 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 included angle between the orientation of the arc heating unit and the thickness direction of the prefabricated pole piece within a reasonable range, it is convenient for the designated part of the film layer to reach a reasonable temperature range within a reasonable time range. For example, it can be heated to 500°C - 900°C within 15 ms - 50 ms, achieving effective heating of the pole piece and improving the performance of the pole piece.

[0031] In a possible implementation manner, heating the designated part of the film layer includes: performing infrared heating on the designated part to heat the designated part to 400°C - 900°C within 20 ms - 60 ms.

[0032] In the embodiments of the present application, infrared heating can be performed on the designated part of the prefabricated pole piece to heat the designated part to 400°C - 900°C within the designated time of 20 ms - 60 ms, thereby improving the performance of the pole piece.

[0033] In a possible implementation manner, the distance between the infrared heating unit and the surface of the film layer in the thickness direction of the prefabricated pole piece is 5 mm - 50 mm, and / or the temperature of the infrared heating is 1400°C - 1800°C, and / or the moving speed of the prefabricated pole piece is 120 m / min - 160 m / min, where the heating unit includes an infrared heating unit.

[0034] In the embodiments 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 pole piece, the temperature of the infrared heating, and the moving speed of the prefabricated pole piece within a reasonable range, it is possible to make the specified part of the film layer reach a reasonable temperature range within a reasonable time range during the infrared heating of the prefabricated pole piece, for example, reach 400°C to 900°C within 20 ms to 60 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0035] In a possible implementation manner, the infrared heating satisfies the following conditions: the heating power of the infrared heating unit is 1000 W to 5000 W.

[0036] In the embodiments 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, which is convenient for the specified part of the film layer of the prefabricated pole piece to reach a reasonable temperature range within a reasonable time during the infrared heating, for example, reach 400°C to 900°C within 20 ms to 60 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0037] In a possible implementation manner, heating the specified part of the film layer includes: electrically heating the specified part to make the specified part reach 300°C to 700°C within 90 ms to 150 ms.

[0038] In the embodiments of the present application, the specified part of the prefabricated pole piece can be electrically heated to make the specified part reach 300°C to 700°C within the specified time of 90 ms to 150 ms, thereby improving the performance of the pole piece.

[0039] In a possible implementation manner, the distance between the electric 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 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 an electric heating unit.

[0040] In the embodiments 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 pole piece, the temperature of the electric heating, and the moving speed of the prefabricated pole piece within a reasonable range, it is possible to make the specified part of the film layer reach a reasonable temperature range within a reasonable time range during the electric heating of the prefabricated pole piece, for example, reach 300°C to 700°C within 90 ms to 150 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0041] In a possible implementation manner, the electric heating satisfies the following conditions: the heating power of the electric heating unit is 500 W to 14000 W.

[0042] In the embodiments of the present application, by controlling the heating power of the electric heating unit within a reasonable range, the temperature of the electric heating can be controlled within a reasonable range, which is convenient for the specified part of the film layer of the prefabricated pole piece to rise to a reasonable temperature range within a reasonable time during the electric heating process, for example, rising to 300°C to 700°C within 90 ms to 150 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0043] In a possible implementation manner, heating treatment of the specified part of the film layer includes: performing microwave heating on the specified part to make the specified part rise to 300°C to 800°C within 50 ms to 120 ms.

[0044] In the embodiments of the present application, microwave heating can be performed on the specified part of the prefabricated pole piece so that the specified part rises to 300°C to 800°C within the specified time of 50 ms to 120 ms, thereby improving the performance of the pole piece.

[0045] In a possible implementation manner, the distance between the microwave heating unit and the surface of the film layer in the thickness direction of the prefabricated pole piece is 5 mm to 25 mm, and / or the temperature of the microwave heating 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.

[0046] In the embodiments of the present application, by setting at least one of the distance between the microwave heating unit and the surface of the film layer in the thickness direction of the prefabricated pole piece, the temperature of the microwave heating, and the moving speed of the prefabricated pole piece within a reasonable range, it can be ensured that during the microwave heating process of the prefabricated pole piece, the specified part of the film layer rises to a reasonable temperature range within a reasonable time range, for example, rising to 300°C to 800°C within 50 ms to 120 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0047] In a possible implementation manner, the microwave heating satisfies the following condition: the heating power of the microwave heating unit is 2000 W to 10000 W.

[0048] In the embodiments of the present application, by controlling the heating power of the microwave heating unit within a reasonable range, the temperature of the microwave heating can be controlled within a reasonable range, which is convenient for the specified part of the film layer of the prefabricated pole piece to rise to a reasonable temperature range within a reasonable time during the microwave heating process, for example, rising to 300°C to 800°C within 50 ms to 120 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0049] In a possible implementation, the method further includes: during the heating process of the specified part, hot air treatment is performed on the specified part using a hot air nozzle. The hot air nozzle is fixedly arranged between the moving starting point and the moving ending point of the prefabricated pole piece, and the hot air nozzle is disposed opposite to the surface of the film layer along the thickness direction of the prefabricated pole piece.

[0050] In the embodiments of the present application, through hot air treatment, impurities, combustion decomposition products, etc. on the surface of the prefabricated pole piece can be cleaned, facilitating the heating treatment of the prefabricated pole piece and improving the heating efficiency of the pole piece. On the other hand, by cleaning impurities, combustion decomposition products, etc. on the surface of the prefabricated pole piece, the resistance of the pole piece can be reduced, and the porosity of the pole piece can be increased, improving the performance of the pole piece.

[0051] 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.

[0052] In the embodiments of the present application, by setting the distance between the hot air nozzle and the surface of the film layer to be the same as the distance between the heating unit and the surface of the film layer along the thickness direction of the prefabricated pole piece, the structure of the device can be simplified.

[0053] In a possible implementation, the temperature of the hot air treatment is 300°C to 600°C.

[0054] In the embodiments of the present application, by controlling the temperature of the hot air treatment within a reasonable range, effective hot air treatment can be performed on the prefabricated pole piece, reducing the influence of too low hot air treatment temperature on the heating treatment, thereby improving the performance of the pole piece; on the other hand, unnecessary energy consumption caused by too high hot air treatment temperature can also be reduced, saving the preparation cost of the pole piece.

[0055] In a 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 orientation of the hot air nozzle and the thickness direction of the prefabricated pole piece is 0° to 45°; (3) along the moving direction of the prefabricated pole piece, the distance between the hot air nozzle and the heating unit is 5 mm to 15 mm.

[0056] 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 pole piece within a reasonable range, effective hot air treatment can be performed on the pole piece, thereby improving the performance of the pole piece.

[0057] In a 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 orientation 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.

[0058] In a possible implementation, before heating the specified part of the film layer, the method further includes: performing one or more of the following treatments on the prefabricated electrode: drying treatment, pressing treatment, or cutting treatment.

[0059] In the embodiment of the present application, one or more of the drying treatment, pressing treatment, and cutting treatment can be performed on the prefabricated electrode first, and then the prefabricated electrode can be heated. The production process of the electrode can be flexibly adjusted based on production requirements, production sites, etc.

[0060] In a possible implementation, the specified part includes the part between the surface of the film layer and one-third of the thickness close to the surface of the film layer.

[0061] In the embodiment of the present application, by heating the part between the surface of the film layer and one-third of the thickness close to the surface of the film layer, the degree of softening or ablation of the binder in the film layer can be increased, the porosity of the electrode can be improved, the infiltration rate of the electrolyte can be increased, and thus the lithium ion transmission rate can be increased.

[0062] In a second aspect, an electrode is provided, and the electrode is obtained according to the preparation method in the first aspect or any possible implementation of the first aspect.

[0063] In a third aspect, a battery is provided, and the battery includes the electrode in the second aspect.

[0064] In a fourth aspect, an electrical device is provided, and the electrical device includes the battery in the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 is a flowchart of the preparation method of the electrode provided by the embodiment of the present application.

[0066] Figure 2 is a schematic diagram of the setting mode of the heating unit provided by the embodiment of the present application.

[0067] Figure 3 is a flowchart of the preparation method of the electrode provided by the embodiment of the present application.

[0068] Figure 4 is a flowchart of the preparation method of the electrode provided by the embodiment of the present application.

[0069] Figure 5 It is a schematic diagram of the setting method of the hot air nozzle provided by an embodiment of the present application.

[0070] Figure 6 It is a schematic diagram of a battery cell provided by an embodiment of the present application.

[0071] Figure 7 It is a schematic diagram of a battery module provided by an embodiment of the present application.

[0072] Figure 8 and Figure 9 It is a schematic diagram of a battery provided by an embodiment of the present application. Detailed implementation manners

[0073] The following further describes the implementation manners of the present application in detail with reference to the drawings and embodiments. The detailed descriptions and drawings of the following embodiments are used to exemplarily illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0074] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 - 120 and 80 - 110 are listed for a specific parameter, ranges of 60 - 110 and 80 - 120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 - 3, 1 - 4, 1 - 5, 2 - 3, 2 - 4, and 2 - 5. In the present application, unless otherwise stated, the numerical range "a - b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0 - 5" means that all real numbers between "0 - 5" have been fully listed herein, and "0 - 5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0075] Referring to "embodiments" in this context means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears at various positions in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0076] In the description of the embodiments of the present application, the term "and / or" is merely a relationship describing associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, the character " / " in this document generally indicates that the associated objects before and after are in an "or" relationship.

[0077] In the description of the embodiments of the present application, the term "at least one" means one or more, and "a plurality" means two or more. "At least one of the following" or similar expressions refer 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 both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0078] The orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", etc. is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the present application. In addition, terms such as "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range.

[0079] If there is no special indication, "including" and "comprising" mentioned in the present application mean open-ended or can also be closed-ended. For example, "including" and "comprising" can mean that other components not listed can also be included or comprised, or it can only include or comprise the listed components.

[0080] If there is no special indication, all steps of the present application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method can include steps (a) and (b) carried out sequentially, or it can also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or it can also include steps (a), (c), and (b), or it can include steps (c), (a), and (b), etc.

[0081] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0082] Battery technology is an important factor in the development of the new energy industry. With the continuous in-depth research on batteries and the continuous improvement of market demand, higher requirements are put forward for various battery performances, such as the energy density, cycle life, reliability, etc. of the battery.

[0083] As an important component of the battery, the electrode sheet provides the active material for the battery to carry out chemical reactions and transports electrons, playing a crucial role in the performance and life of the battery. For example, the wetting performance, internal resistance, etc. of the electrode sheet affect the performance of the battery such as impedance and self-discharge. Therefore, the performance and service life of the battery can be improved by enhancing the performance of the electrode sheet.

[0084] In view of this, the embodiments of the present application provide a method for preparing an electrode sheet, an electrode sheet, a battery, and an electrical device. The preparation method includes: 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; performing a heat treatment on a specified part of the film layer to raise the temperature of the specified part to a specified temperature within a specified time, where the specified part includes at least a part 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. In this way, the performance of the electrode sheet can be improved, thereby improving the performance and service life of the battery and the electrical device using the electrode sheet.

[0085] The method for preparing the electrode sheet provided by the embodiments of the present application is exemplarily introduced as follows.

[0086] [Preparation of Electrode Sheet]

[0087] Figure 1 is a schematic flow chart of the method for preparing the electrode sheet provided by the embodiments of the present application.

[0088] 110. Prepare 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.

[0089] The electrode sheet can include a positive electrode sheet or a negative electrode sheet.

[0090] The positive electrode sheet includes a positive current collector and a positive film layer provided on at least one surface of the positive current collector. For example, a positive film layer can be prepared on at least one surface of the positive current collector.

[0091] The positive current collector has two surfaces opposite to each other in its own thickness direction, and the positive film layer is provided on any one or both of the two opposite surfaces of the positive current collector.

[0092] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum foil may be used. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (such as 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.).

[0093] The positive electrode film layer includes a positive electrode active material. By way of example, the positive electrode active material may include at least one of the following materials: lithium phosphate with an olivine structure, lithium transition metal oxide, or their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material of the battery may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of the lithium transition metal oxide 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 (which can also be abbreviated as NCM333), LiNi0.5Co0.2Mn0.3O2 (which can also be abbreviated as NCM523), LiNi0.5Co0.25Mn0.25O2 (which can also be abbreviated as NCM211), LiNi0.6Co0.2Mn0.2O2 (which can also be abbreviated as NCM622), LiNi0.8Co0.1Mn0.1O2 (which can also be abbreviated as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi0.85Co0.15Al0.05O2), or modified compounds, etc.). Examples of the lithium phosphate with an olivine structure may include, but are not limited to, lithium iron phosphate (such as LiFePO4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, or a composite material of lithium manganese iron phosphate and carbon, etc.

[0094] The positive electrode film layer includes a binder. By way of example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, or fluorinated acrylate resin.

[0095] 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.

[0096] 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 current collector to obtain a prefabricated positive electrode sheet.

[0097] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided 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.

[0098] The negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode film layer is provided on either or both of the two opposite surfaces of the negative electrode current collector.

[0099] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, copper foil can be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (such as copper, copper 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.).

[0100] 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, etc. The silicon-based materials can include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, or silicon alloys. The tin-based materials can include at least one of elemental tin, tin oxides, or tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as the negative electrode active material of the battery can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0101] 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).

[0102] In some embodiments, the negative electrode film layer may further include a conductive agent. 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.

[0103] In some embodiments, the negative electrode film layer may further include other additives, such as a thickening agent (such as sodium carboxymethyl cellulose (CMC-Na)), etc.

[0104] For example, the negative electrode active material, conductive agent, binder, and thickening agent can be dissolved in deionized water to form a negative electrode slurry; then the negative electrode slurry is coated on the negative electrode current collector to obtain a prefabricated negative electrode sheet.

[0105] 120, heat treatment is performed on the designated part of the film layer to raise the temperature of the designated part to the designated temperature within the designated time.

[0106] Among them, the designated part includes at least part 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.

[0107] In the embodiments of the present application, during the heat treatment of the designated part of the prefabricated electrode sheet film layer, by controlling the designated time above 15 ms and the designated temperature above 285 °C, the sheet resistance of the electrode sheet can be reduced, which is beneficial to the transmission of lithium ions, thereby improving the performance of the battery. For example, for the positive electrode sheet, the residual solvent, impurities, etc. on the surface of the electrode sheet can be removed through heat treatment to reduce the resistance of the positive electrode sheet; for the negative electrode sheet, the graphitization degree, the orientation degree of graphite, and the impurities on the surface of the negative electrode sheet can be improved through heat treatment to reduce the resistance of the negative electrode sheet.

[0108] In addition, under the action of high temperature, the burrs, particulate matters, etc. generated on the surface of the prefabricated electrode sheet due to cutting can also be ablated. On the one hand, the sharpness of the surface of the electrode sheet can be reduced, thereby reducing the risk of the separator being pierced, and further improving the K value (voltage drop per unit time) of the battery; on the other hand, reducing the ablation of impurities such as burrs and particulate matters can reduce the side reactions on the surface of the electrode sheet, making the SEI film on the surface of the electrode sheet more stable, thereby improving the capacity and initial efficiency of the battery prepared from this electrode sheet.

[0109] In the embodiments of the present application, when the temperature of the prefabricated electrode sheet rises, the binder in the electrode sheet can be softened or ablated, thereby removing part of the binder in the electrode sheet and increasing the porosity of the electrode sheet. The increase in porosity can increase the channels for electrolyte infiltration, improve the infiltration rate of the electrolyte, thereby increasing the transmission rate of lithium ions, and further improving the performance of the battery.

[0110] In some embodiments, the designated time is 15 ms to 150 ms, and the designated temperature is 300 °C to 900 °C.

[0111] In the embodiment of the present application, the temperature of at least part of the surface of the film layer is raised to 300°C to 900°C within 15 ms to 150 ms, so that the temperature of the designated part of the film layer can be rapidly increased, which can improve the performance of the electrode sheet while improving the production efficiency, thereby improving the performance of the battery.

[0112] In some embodiments, a heating unit is disposed relative to the surface of the film layer along the thickness direction of the prefabricated electrode sheet, and the heating unit is used to heat the designated part. Wherein, the distance between the heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode sheet is 5 mm to 150 mm, and / or the temperature of the heat treatment is 1000°C to 2000°C.

[0113] When preparing the electrode sheet, a film layer including an active material and a binder is usually prepared on two surfaces in the thickness direction of the current collector. For example, Figure 2 As shown, when the film layer is prepared on two surfaces in the thickness direction of the current collector, the heating unit may include a first heating unit and a second heating unit disposed on both sides in the thickness direction of the prefabricated electrode sheet. The first heating unit and the second heating unit are disposed opposite to the surface of the film layer along the thickness direction of the prefabricated electrode sheet, that is, the first heating unit is disposed opposite to the upper surface of the prefabricated electrode sheet along its thickness direction, and the second heating unit is disposed opposite to the lower surface of the prefabricated electrode sheet along its thickness direction.

[0114] 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. Optionally, the distance between the heating unit and the surface of the film layer may also be within the range obtained by combining any two of the above values.

[0115] 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 the range obtained by combining any two of the above values.

[0116] In the embodiment of the present application, by disposing a heating unit along the thickness direction of the prefabricated electrode sheet and controlling the distance between the heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode sheet and / or the temperature of the heating unit within a reasonable range to heat the designated part of the film layer, at least part of the surface of the film layer can be rapidly heated to 300°C to 900°C, improving the performance of the electrode sheet, thereby improving the performance of the battery.

[0117] Figure 3 It is a schematic flow chart of the method for preparing the electrode sheet provided by the embodiment of the present application.

[0118] 310. Prepare a film layer including an active material and a binder on at least one surface of the current collector to obtain a prefabricated electrode sheet.

[0119] The content of step 310 can refer to the relevant descriptions in the above text, and will not be elaborated in this application.

[0120] 320. Use the transfer unit to move the prefabricated pole piece.

[0121] In some embodiments, the drive unit may include a conveyor belt, a transfer track, or Figure 2 the guide rollers shown, etc.

[0122] As an example, a film layer can be prepared on the surface of the current collector to obtain a prefabricated pole piece, and the transfer unit is used to move the prefabricated pole piece.

[0123] 330. Use the heating unit to heat a specified part during the movement of the prefabricated pole piece, so that the specified part is heated to a specified temperature within a specified time.

[0124] Among them, the specified part includes at least part 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.

[0125] The heating unit is fixedly arranged between the starting point and the ending point of the movement of the prefabricated pole piece.

[0126] In this embodiment, the prefabricated pole piece is moving, and the heating unit is stationary or immobile. For example, during the movement of the prefabricated pole piece following the transfer unit, the heating unit fixedly arranged at a certain position between the starting point and the ending point of the movement of the prefabricated pole piece is used to heat the prefabricated pole piece.

[0127] In the embodiments of the present application, during the movement of the prefabricated pole piece, the heating unit fixedly arranged between the starting point and the ending point of the movement of the prefabricated pole piece can be used to heat the prefabricated pole piece, which can improve the performance of the pole piece while improving the production efficiency, thereby improving the performance of the battery.

[0128] In some embodiments, the moving speed of the prefabricated pole piece is 50 m / min to 200 m / min.

[0129] As an example, the moving speed of the prefabricated pole piece can be 50 m / min, 80 m / min, 110 m / min, 140 m / min, 170 m / min, or 200 m / min. Optionally, the moving speed of the prefabricated pole piece can also be within the range obtained by combining any two of the above values.

[0130] In the embodiments of the present application, during the process of moving the prefabricated pole piece at a speed of 50 m / min to 200 m / min, the heating unit can be used to effectively heat the prefabricated pole piece, which can improve the performance of the pole piece while improving the production efficiency, thereby improving the performance of the battery.

[0131] In some embodiments, the heat 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.

[0132] Flame combustion heating can use a flame to burn the sample to increase the temperature of the sample.

[0133] Electromagnetic induction heating can use the method of electromagnetic induction to generate an electric current inside the object to be heated, and rely on the energy of these electric currents to achieve the heating purpose.

[0134] Laser heating can use the energy of a laser to heat an object.

[0135] Plasma heating is an electric heating method that uses the high temperature of the plasma formed by the ionization of the gas to be ionized and the energy released when free electrons and positive ions in the plasma recombine. The gas to be ionized for plasma heating can be air or inert gas (such as nitrogen, argon), etc.

[0136] Arc heating refers to the heating process that occurs when an electric current passes through some gases, such as air, to generate arc light and release heat.

[0137] Infrared heating is a heating method that heats an object through infrared rays. The heat energy can be directly transferred to the object with a lower temperature through the electromagnetic waves in the infrared region.

[0138] Electric heating relies on heating elements such as resistance wires, silicon carbide rods or silicon molybdenum rods to generate heat, and then heats the object through convection and / or radiation.

[0139] 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.

[0140] In the embodiments of the present application, one heating method can be used to heat the prefabricated pole piece. Of course, multiple mixed heating methods can also be used to heat the prefabricated pole piece.

[0141] In the embodiments of the present application, the prefabricated pole piece can be heat-treated by various 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.

[0142] In some embodiments, the heat treatment may include at least one of plasma heating, arc heating, infrared heating, electric heating, or microwave heating.

[0143] In some embodiments, heat-treating a specified part of the film layer includes: performing plasma heating on the specified part to raise the temperature of the specified part to 300°C to 700°C within 50 ms to 150 ms.

[0144] That is, during the plasma heating process, the specified time is 50 ms to 150 ms, and the specified temperature is 300°C to 700°C.

[0145] As an example, during the plasma heating process, the specified time can be 50 ms, 70 ms, 90 ms, 110 ms, 130 ms, or 150 ms. Optionally, during the plasma heating process, the specified time can also be within the range obtained by combining any two of the above values.

[0146] As an example, during the plasma heating process, the specified temperature is 300°C, 400°C, 500°C, 600°C, or 700°C. Optionally, during the plasma heating process, the specified temperature can also be within the range obtained by combining any two of the above values.

[0147] In the embodiments of the present application, plasma heating can be performed on a specified part of the prefabricated electrode sheet to raise the temperature of the specified part to 300°C to 700°C within a specified time of 50 ms to 150 ms, thereby improving the performance of the electrode sheet.

[0148] In some embodiments, the distance between the plasma heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode sheet 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 electrode sheet is 50 m / min to 80 m / min, where the heating unit includes a plasma heating unit.

[0149] As an example, the plasma heating unit can be, for example, the plasma gun of a plasma heating device. Along the thickness direction of the prefabricated electrode sheet, the distance between the plasma gun and the surface of the film layer can be 5 mm to 25 mm.

[0150] As an example, along the thickness direction of the prefabricated electrode sheet, the distance between the plasma heating unit and the surface of the film layer is 5 mm, 10 mm, 15 mm, 20 mm, 25 mm. Optionally, along the thickness direction of the prefabricated electrode sheet, the distance between the plasma heating unit and the surface of the film layer can also be within the range obtained by combining any two of the above values.

[0151] As an example, the temperature of plasma heating is 1000 °C, 1100 °C or 1200 °C. Optionally, the temperature of plasma heating can also be within the range obtained by combining any two of the above values.

[0152] As an example, during the plasma heating process, the moving speed of the prefabricated pole piece can be 50 m / min, 60 m / min, 70 m / min or 80 m / min. Optionally, during the plasma heating process, the moving speed of the prefabricated pole piece can also be within the range obtained by combining any two of the above values.

[0153] In the 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 pole piece, the temperature of the plasma heating, and the moving speed of the prefabricated pole piece within a reasonable range, it can be ensured 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, heated to 300 °C to 700 °C within 50 ms to 150 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0154] In some embodiments, the plasma heating satisfies one or more of the following conditions: (1) the flow rate of the gas to be ionized in the 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 orientation of the plasma heating unit and the thickness direction of the prefabricated pole piece is 0° to 60°.

[0155] As an example, the flow rate of the gas to be ionized can be 10 L / min, 40 L / min, 70 L / min or 100 L / min. Optionally, the flow rate of the gas to be ionized can also be within the range obtained by combining any two of the above values.

[0156] As an example, the heating power of the plasma heating unit can be 500 W, 4000 W, 8000 W, 12000 W or 15000 W. For another example, the heating power of the plasma heating unit can also be within the range obtained by combining any two of the above values.

[0157] As an example, the angle between the orientation of the plasma heating unit and the thickness direction of the prefabricated pole 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 pole piece can also be within the range obtained by combining any two of the above values.

[0158] During the plasma heating process, the temperature of the plasma heating can be adjusted by adjusting the flow rate of the gas to be ionized and / or the heating power of the plasma heating unit, etc., so that the temperature of the plasma heating can be controlled within a reasonable range.

[0159] 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 pole piece within a reasonable range, it is convenient for the specified part of the film layer to be heated to a reasonable temperature range within a reasonable time range, for example, heated to 300°C - 700°C within 50 ms - 150 ms, realizing effective heating of the pole piece and improving the performance of the pole piece.

[0160] In some embodiments, heating treatment of the specified part of the film layer includes: arc heating the specified part to raise the temperature of the specified part to 500°C - 900°C within 15 ms - 50 ms.

[0161] That is, during the arc heating process, the specified time is 15 ms - 50 ms, and the specified temperature is 500°C - 900°C.

[0162] In the embodiments of the present application, the specified part of the prefabricated pole piece can be arc heated to raise the temperature of the specified part to 500°C - 900°C within the specified time of 15 ms - 50 ms, thereby improving the performance of the pole piece.

[0163] In some embodiments, the distance between the arc heating unit and the surface of the film layer along the thickness direction of the prefabricated pole piece is 80 mm - 150 mm, and / or the temperature of the arc heating is 1600°C - 2000°C, and / or the moving speed of the prefabricated pole piece is 160 m / min - 200 m / min, where the heating unit includes an arc heating unit.

[0164] As an example, the arc heating unit can be an arc heating head, for example. Along the thickness direction of the prefabricated pole piece, the distance between the arc heating head and the surface of the film layer is 80 mm - 150 mm.

[0165] As an example, along the thickness direction of the prefabricated pole piece, the distance between the arc heating unit and the surface of the film layer can be 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, or 150 mm. Optionally, along the thickness direction of the prefabricated pole piece, the distance between the arc heating unit and the surface of the film layer can also be within the range obtained by combining any two of the above values.

[0166] As an example, the temperature of the arc heating can be 1600°C, 1700°C, 1800°C, 1900°C, or 2000°C. Optionally, the temperature of the arc heating can also be within the range obtained by combining any two of the above values.

[0167] 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. Optionally, the moving speed of the prefabricated pole piece can also be within the range obtained by combining any two of the above values.

[0168] In the embodiments of the present application, by setting one or more of the distance between the arc heating unit and the surface of the film layer in the thickness direction of the prefabricated pole piece, the temperature of the arc heating, and the moving speed of the prefabricated pole piece within a reasonable range, it is possible to make the specified part of the film layer reach a reasonable temperature range within a reasonable time range during the arc heating of the prefabricated pole piece, for example, rise to 500 °C to 900 °C within 15 ms to 50 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0169] In some embodiments, the arc heating satisfies one or more of the following conditions: (1) the gas flow rate of the arc heating unit is 30 L / min to 80 L / min; (2) the heating power of the arc heating unit is 1000 W to 8000 W; (3) the angle between the orientation of the arc heating unit and the thickness direction of the prefabricated pole piece is 0° to 60°.

[0170] 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. Optionally, the gas flow rate of the arc heating unit can also be within the range obtained by combining any two of the above values.

[0171] As an example, the heating power of the arc heating unit can be 1000 W, 3000 W, 5000 W, 7000 W or 8000 W. Optionally, the heating power of the arc heating unit can also be within the range obtained by combining any two of the above values.

[0172] As an example, the angle between the orientation of the arc heating unit and the thickness direction of the prefabricated pole piece can be 0°, 30° or 60°. Optionally, the angle between the orientation of the arc heating unit and the thickness direction of the prefabricated pole piece can also be within the range obtained by combining any two of the above values.

[0173] During the arc heating process, the temperature of the arc heating can be adjusted by adjusting the gas flow rate of the arc heating unit and / or the heating power of the arc heating unit, etc., so that the temperature of the arc heating can be controlled within a reasonable range.

[0174] 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 orientation of the arc heating unit and the thickness direction of the prefabricated electrode sheet within a reasonable range, it is convenient for a specified part of the film layer to be heated to a reasonable temperature range within a reasonable time range, for example, heated to 500°C to 900°C within 15 ms to 50 ms, so as to effectively heat the electrode sheet and improve the performance of the electrode sheet.

[0175] In some embodiments, heating treatment is performed on a specified part of the film layer, including: performing infrared heating on the specified part to heat the specified part to 400°C to 900°C within 20 ms to 60 ms.

[0176] That is, during the infrared heating process, the specified time is 20 ms to 60 ms, and the specified temperature is 400°C to 900°C.

[0177] As an example, during the infrared heating process, the specified time can be 20 ms, 30 ms, 40 ms, 50 ms, or 60 ms. Optionally, during the infrared heating process, the specified time can also be within the range obtained by combining any two of the above values.

[0178] As an example, during the infrared heating process, the specified temperature is 300°C, 400°C, 500°C, 600°C, or 700°C. Optionally, during the infrared heating process, the specified temperature can also be within the range obtained by combining any two of the above values.

[0179] In the embodiments of the present application, infrared heating can be performed on a specified part of the prefabricated electrode sheet to heat the specified part to 400°C to 900°C within a specified time of 20 ms to 60 ms, thereby improving the performance of the electrode sheet.

[0180] In some embodiments, the distance between the infrared heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode sheet 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 sheet is 120 m / min to 160 m / min, where the heating unit includes an infrared heating unit.

[0181] As an example, the heating unit of the infrared heating, for example, can be the heating tube of the infrared heating device. Along the thickness direction of the prefabricated electrode sheet, the distance between the heating tube of the infrared heating device and the surface of the film layer is 5 mm to 50 mm.

[0182] As an example, along the thickness direction of the prefabricated pole piece, 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. Optionally, along the thickness direction of the prefabricated pole piece, 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.

[0183] As an example, the temperature of the infrared heating is 1400 °C, 1500 °C, 1600 °C, 1700 °C or 1800 °C. Optionally, the temperature of the infrared heating can also be within the range obtained by combining any two of the above values.

[0184] As an example, during the infrared heating process, the moving speed of the prefabricated pole piece can be 120 m / min, 130 m / min, 140 m / min, 150 m / min or 160 m / min. Optionally, during the infrared heating process, the moving speed of the prefabricated pole piece can also be within the range obtained by combining any two of the above values.

[0185] In the embodiments 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 pole piece, the temperature of the infrared heating, and the moving speed of the prefabricated pole piece within a reasonable range, it is possible to make the specified part of the film layer of the prefabricated pole piece rise to a reasonable temperature range within a reasonable time range during the infrared heating process, for example, rise to 400 °C - 900 °C within 20 ms - 60 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0186] In some embodiments, the infrared heating satisfies the following condition: the heating power of the infrared heating unit is 1000 W - 5000 W.

[0187] During the infrared heating process, the temperature of the infrared heating can be adjusted by adjusting the heating power of the infrared heating unit.

[0188] As an example, the heating power of the infrared heating unit can be 1000 W, 2000 W, 3000 W, 4000 W or 5000 W. For another example, the heating power of the infrared heating unit can also be within the range obtained by combining any two of the above values.

[0189] In the embodiments 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, which is convenient for the specified part of the film layer of the prefabricated pole piece to rise to a reasonable temperature within a reasonable time during the infrared heating process, for example, rise to 400 °C - 900 °C within 20 ms - 60 ms, so as to achieve effective heating of the pole piece and improve the performance of the pole piece.

[0190] In some embodiments, heat treatment is performed on a designated part of the film layer, including: electrically heating the designated part to raise the temperature of the designated part to 300°C to 700°C within 90 ms to 150 ms.

[0191] That is, during the electric heating process, the designated time is 90 ms to 150 ms, and the designated temperature is 300°C to 700°C.

[0192] As an example, during the electric heating process, the designated time can be 90 ms, 110 ms, 130 ms, or 150 ms. Optionally, during the electric heating process, the designated time can also be within the range obtained by combining any two of the above values.

[0193] 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 can also be within the range obtained by combining any two of the above values.

[0194] In the embodiments of the present application, electric heating can be performed on a designated part of the prefabricated electrode sheet to raise the temperature of the designated part to 300°C to 700°C within a designated time of 90 ms to 150 ms, thereby improving the performance of the electrode sheet.

[0195] In some embodiments, the distance between the electric heating unit and the surface of the film layer in the thickness direction of the prefabricated electrode sheet 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 sheet is 50 m / min to 80 m / min, where the heating unit includes an electric heating unit.

[0196] As an example, the electric heating unit can be, for example, a resistance wire, a silicon carbide rod, or a silicon molybdenum rod of an electric heating device. In the thickness direction of the prefabricated electrode sheet, the distance between the resistance wire of the electric heating device and the surface of the film layer can be 5 mm to 25 mm.

[0197] As an example, in the thickness direction of the prefabricated electrode sheet, the distance between the electric heating unit and the surface of the film layer is 5 mm, 10 mm, 15 mm, 20 mm, or 25 mm. Optionally, in the thickness direction of the prefabricated electrode sheet, the distance between the electric heating unit and the surface of the film layer can also be within the range obtained by combining any two of the above values.

[0198] As an example, the electric heating temperature is 1000°C, 1150°C, or 1300°C. Optionally, the electric heating temperature can also be within the range obtained by combining any two of the above values.

[0199] As an example, during the electrothermal process, the moving speed of the prefabricated pole piece can be 50 m / min, 60 m / min, 70 m / min, or 80 m / min. Optionally, during the electrothermal process, the moving speed of the prefabricated pole piece can also be within the range obtained by combining any two of the above values.

[0200] In the embodiments of the present application, by setting one or more of the distance between the electrothermal unit and the surface of the film layer in the thickness direction of the prefabricated pole piece, the electrothermal temperature, and the moving speed of the prefabricated pole piece within a reasonable range, it is possible to cause the specified part of the film of the prefabricated pole piece to rise to a reasonable temperature range within a reasonable time range during the electrothermal process, for example, to rise to 300°C to 700°C within 90 ms to 150 ms, achieving effective heating of the pole piece and improving the performance of the pole piece.

[0201] In some embodiments, the electrothermal heating satisfies the following condition: the heating power of the electrothermal unit is 500 W to 14000 W.

[0202] During the electrothermal process, the electrothermal temperature can be adjusted by adjusting the heating power of the electrothermal unit.

[0203] As an example, the heating power of the electrothermal unit can be 500 W, 4000 W, 8000 W, 12000 W, or 14000 W. Optionally, the heating power of the electrothermal unit can also be within the range obtained by combining any two of the above values.

[0204] In the embodiments of the present application, by controlling the heating power of the electrothermal unit within a reasonable range, the electrothermal temperature can be controlled within a reasonable range, facilitating the specified part of the film layer of the prefabricated pole piece to rise to a reasonable temperature range within a reasonable time during the electrothermal process, for example, to rise to 300°C to 700°C within 90 ms to 150 ms, achieving effective heating of the pole piece and improving the performance of the pole piece.

[0205] In some embodiments, heating treatment of the specified part of the film layer includes: performing microwave heating on the specified part to cause the specified part to rise to 300°C to 800°C within 50 ms to 120 ms.

[0206] That is, during the microwave heating process, the specified time is 50 ms to 120 ms, and the specified temperature is 300°C to 800°C.

[0207] As an example, during the microwave heating process, the specified time can be 50 ms, 70 ms, 90 ms, 110 ms, or 120 ms. Optionally, during the microwave heating process, the specified time can also be within the range obtained by combining any two of the above values.

[0208] As an example, during microwave heating, the specified temperatures are 300°C, 400°C, 500°C, 600°C, 700°C, or 800°C. Optionally, during microwave heating, the specified temperature can also be within the range obtained by combining any two of the above values.

[0209] In the embodiments of the present application, microwave heating can be performed on a specified part of the prefabricated pole piece, so that the specified part is heated to 300°C to 900°C within a specified time of 50 ms to 120 ms, thereby improving the performance of the pole piece.

[0210] In some embodiments, the distance between the microwave 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 microwave heating is 1300°C to 1800°C, and / or the moving speed of the prefabricated pole piece is 80 m / min to 120 m / min, where the heating unit includes a microwave heating unit.

[0211] As an example, the heating unit for 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.

[0212] As an example, along the thickness direction of the prefabricated pole piece, the distance between the microwave heating unit and the surface of the film layer can be 5 mm, 10 mm, 15 mm, 20 mm, or 25 mm. Optionally, along the thickness direction of the prefabricated pole piece, the distance between the microwave heating unit and the surface of the film layer can also be within the range obtained by combining any two of the above values.

[0213] As an example, the temperature of the microwave heating is 1300°C, 1400°C, 1500°C, 1600°C, 1700°C, or 1800°C. Optionally, the temperature of the microwave heating can also be within the range obtained by combining any two of the above values.

[0214] As an example, during the microwave heating process, the moving speed of the prefabricated pole piece can be 80 m / min, 90 m / min, 100 m / min, 110 m / min, or 120 m / min. Optionally, during the microwave heating process, the moving speed of the prefabricated pole piece can also be within the range obtained by combining any two of the above values.

[0215] In the embodiments of the present application, by setting one or more of the distance between the microwave heating unit and the surface of the film layer along the thickness direction of the prefabricated pole piece, the temperature of the microwave heating, and the moving speed of the prefabricated pole piece within a reasonable range, it is possible to make the specified part of the film layer reach a reasonable temperature range within a reasonable time range during the microwave heating process of the prefabricated pole piece. For example, it can reach 300°C to 800°C within 50 ms to 120 ms, achieving effective heating of the pole piece and improving the performance of the pole piece.

[0216] In some embodiments, the microwave heating satisfies the following conditions: the heating power of the microwave heating unit is 2000W to 10000W.

[0217] During the microwave heating process, the temperature of the microwave heating can be adjusted by adjusting the heating power of the microwave heating unit.

[0218] As an example, the heating power of the microwave heating unit can be 2000W, 4000W, 6000W, 8000W, or 10000W. Optionally, the heating power of the microwave heating unit can also be within the range obtained by combining any two of the above values.

[0219] In the embodiments of the present application, by controlling the heating power of the microwave heating unit within a reasonable range, the temperature of the microwave heating can be controlled within a reasonable range, facilitating the specified part of the film layer of the prefabricated pole piece to reach a reasonable temperature range within a reasonable time during the microwave heating process. For example, it can reach 300°C to 800°C within 50 ms to 120 ms, achieving effective heating of the pole piece and improving the performance of the pole piece.

[0220] Figure 4 It is a schematic flow chart of the method for preparing a pole piece provided by the embodiments of the present application.

[0221] 410. Prepare a film layer including an active material and a binder on at least one surface of the current collector to obtain a prefabricated pole piece.

[0222] 420. Perform a heating treatment on the specified part of the film layer to make the specified part reach a specified temperature within a specified time.

[0223] Among them, the specified part includes at least part of the surface of the film layer, the specified part includes at least part 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.

[0224] The content of step 410 and step 420 can refer to the relevant descriptions in the above text, and the present application will not elaborate here.

[0225] 430. During the process of performing the heating treatment on the specified part, perform a hot air treatment on the specified part using a hot air nozzle.

[0226] The hot air nozzle is fixedly arranged between the moving starting point and the moving ending point of the prefabricated pole piece, and the hot air nozzle is oppositely arranged with respect to the surface of the film layer along the thickness direction of the prefabricated pole piece.

[0227] 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 ending point of the prefabricated pole piece.

[0228] As an example, during the movement of the prefabricated pole piece, heat treatment and hot air treatment can be simultaneously performed on the prefabricated pole piece.

[0229] In the embodiment of the present application, through hot air treatment, impurities, combustion decomposition products, etc. on the surface of the prefabricated pole piece can be cleaned, which is convenient for heat treatment of the prefabricated pole piece and can improve the efficiency of pole piece heating. On the other hand, through hot air treatment, cleaning impurities, combustion decomposition products, etc. on the surface of the prefabricated pole piece can reduce the resistance of the pole piece and increase the porosity of the pole piece, thereby improving the performance of the pole piece.

[0230] In some embodiments, along the thickness direction of the prefabricated pole piece, the distance between the surface of the hot air nozzle and the film layer is the same as the distance between the surface of the heating unit and the film layer.

[0231] For example, Figure 5 Shown is an example of the setting of the hot air nozzle. The hot air nozzle can be arranged after the heating unit for heat treatment. Optionally, the hot air nozzle can also be arranged before the heating unit for heat treatment.

[0232] In the embodiment of the present application, setting the distance between the surface of the hot air nozzle and the film layer to be the same as the distance between the surface of the heating unit and the film layer along the thickness direction of the prefabricated pole piece can simplify the structure of the equipment.

[0233] In some embodiments, the temperature of the hot air treatment is 300°C to 600°C.

[0234] As an example, the temperature of the hot air treatment can be 300°C, 400°C, 500°C or 600°C. For another example, the temperature of the hot air treatment can also be within the range obtained by combining any two of the above values.

[0235] In the embodiment of the present application, by controlling the temperature of the hot air treatment within a reasonable range, effective hot air treatment can be performed on the prefabricated pole piece, reducing the influence of too low hot air treatment temperature on heat treatment, thereby being able to improve the performance of the pole piece; on the other hand, it can also reduce the unnecessary energy consumption caused by too high hot air treatment temperature and save the preparation cost of the pole piece.

[0236] 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 orientation 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.

[0237] 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.

[0238] In this embodiment, by adjusting the hot air flow rate, the temperature of the hot air treatment can be adjusted. By controlling the temperature of the hot air treatment within a reasonable range, effective hot air treatment can be performed on the prefabricated electrode.

[0239] As an example, the angle between the orientation of the hot air nozzle and the thickness direction of the prefabricated electrode can be 0, 15°, 30°, or 45°. Optionally, the angle between the orientation of the hot air nozzle and the thickness direction of the prefabricated electrode can also be within the range obtained by combining any two of the above values.

[0240] In this embodiment, by controlling the angle between the orientation of the hot air nozzle and the thickness direction of the prefabricated electrode within a reasonable range, effective hot air treatment can be performed on the prefabricated electrode.

[0241] As an example, along the moving direction of the prefabricated electrode, the distance between the hot air nozzle and the heating unit can be 5 mm, 10 mm, or 15 mm. For another example, along the moving direction of the prefabricated electrode, the distance between the hot air nozzle and the heating unit can also be within the range obtained by combining any two of the above values.

[0242] In this embodiment, by controlling the distance between the hot air nozzle and the heating unit along the moving direction of the prefabricated electrode within a reasonable range, effective hot air treatment can be performed on the prefabricated electrode.

[0243] 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, effective hot air treatment can be performed on the prefabricated electrode, thereby improving the performance of the electrode.

[0244] 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 orientation of the hot air nozzle and the thickness direction of the prefabricated electrode sheet is 20° to 45°; (3) along the moving direction of the prefabricated electrode sheet, the distance between the hot air nozzle and the heating unit is 8 mm to 12 mm.

[0245] Controlling the distance between the hot air nozzle and the heating unit along the moving direction of the prefabricated electrode sheet, and / or the angle of the hot air nozzle within the above ranges facilitates the installation of the hot air nozzle and can reduce the excessive occupation of equipment space by the installation of the hot air nozzle.

[0246] On the other hand, controlling the hot air flow rate of the hot air treatment between 50 L / min and 200 L / min can reduce the energy consumption of the hot air treatment while meeting the temperature requirements of the hot air treatment to effectively perform the hot air treatment on the prefabricated electrode sheet.

[0247] In some embodiments, before heating the designated part of the film layer, the following treatments are performed on the prefabricated electrode sheet: one or more of drying treatment, pressing treatment, or cutting treatment.

[0248] Generally speaking, after preparing the film layer on at least one surface of the current collector, the electrode sheet is subjected to different treatments in sequence according to production requirements, for example, drying treatment, pressing treatment, and cutting treatment are performed in sequence. In this case, when performing a certain treatment, it can be considered that the other treatments before this treatment have been completed. For example, when performing the cutting treatment, it can be considered that the drying treatment and the pressing treatment have been completed.

[0249] The drying treatment can remove the solvent and moisture in the film layer (slurry).

[0250] The electrode sheet after the drying treatment is usually relatively loose. If used directly, the film layer of the electrode sheet is likely to peel off and be damaged after being infiltrated by the electrolyte. Therefore, a roller press or a tablet press can be used to perform a pressing treatment on the dried electrode sheet, such as cold pressing treatment.

[0251] The cutting treatment can include at least one of pre-slitting treatment, die-cutting treatment, or slitting treatment.

[0252] To ensure production efficiency, multiple electrode strips are usually coated on the current collector during coating, and there are current collectors without coated active materials on both sides of the electrode strips. Generally, pre-slitting treatment is first performed to cut the multiple electrode strips into single electrode strips.

[0253] The die-cutting treatment refers to cutting out the shape of the tab on both sides of the electrode strip.

[0254] The slitting treatment refers to slitting from the middle of the electrode strip to form an electrode sheet with a tab on one side.

[0255] 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.

[0256] 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.

[0257] 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.

[0258] 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.

[0259] Figure 6 A schematic diagram of a battery cell provided in an embodiment of the present application.

[0260] 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 released from the positive electrode sheet and the negative electrode sheet.

[0261] 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.

[0262] 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.

[0263] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0264] 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.

[0265] In some embodiments, the solvent may include at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl 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, sulfolane, dimethyl sulfone, methyl ethyl sulfone or diethyl sulfone.

[0266] In some embodiments, the electrolyte may further include additives. For example, the additives may include anode film-forming additives, cathode film-forming additives, and may also include additives that can improve certain battery performances, such as additives for improving the overcharge performance of the battery, additives for improving the high-temperature or low-temperature performance of the battery, etc.

[0267] The separator is disposed between the positive electrode plate and the negative electrode plate, mainly functioning to prevent short circuit between the positive and negative electrodes, and at the same time allowing ions to pass through. There is no particular limitation on the type of the separator in this application. For example, it can be a porous structure separator with good chemical stability and mechanical stability.

[0268] In some embodiments, the material of the separator may 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.

[0269] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch soft package. The material of the soft package can be plastic. As plastics, polypropylene, polybutylene terephthalate or polybutylene succinate, etc. can be listed.

[0270] There is no particular limitation on the shape of the battery cell in this application, and it can be cylindrical, square or any other arbitrary shape.

[0271] Figure 7 is a battery module 700 as an example. Refer to Figure 7 , in the battery module 700, a plurality of battery cells 700 can be arranged in sequence along the length direction of the battery module 700. Of course, they can also be arranged in any other arbitrary manner. Further, the plurality of battery cells 600 can be fixed by fasteners.

[0272] In one embodiment, the battery module 700 may further include a housing having an accommodation space, and a plurality of battery cells 600 are accommodated in the accommodation space. ]

[0273] In one embodiment, the above battery module 700 can also be assembled into a battery. The number of battery modules 700 included in the battery can be one or more. Those skilled in the art can select the specific number according to the application and capacity of the battery.

[0274] Figure 8 and Figure 9 is a battery 800 as an example. Referring to Figure 8 and Figure 9 , the battery 800 may include a battery box and a plurality of battery modules 700 disposed in the battery box. The battery box includes an upper box body 801 and a lower box body 802. The upper box body 801 can cover the lower box body 802 and form a closed space for accommodating the battery modules 700. The plurality of battery modules 700 can be arranged in the battery box in any manner.

[0275] It should be understood that in some other embodiments, the above battery 800 is also referred to as a battery pack. The battery cells 600 can first form battery modules 700, and the battery 800 is composed of battery modules 700. It is also possible to directly form the battery 800 from the battery cells 600, omitting the intermediate form of the battery module 700.

[0276] 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 by the present application. The battery cell 600, battery module 700, or battery 800 can be used as the power supply of the electrical device or as the energy storage unit of the electrical device. The electrical device can include mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, or energy storage systems, etc., but is not limited thereto.

[0277] The electrical device can select the battery cell 600, battery module 700, or battery 800 according to its usage requirements.

[0278] As an example, the electrical device can be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the electrical device for secondary batteries, a battery pack or a battery module can be used.

[0279] As another example, the electrical device can be a mobile phone, a tablet computer, a laptop computer, etc. This device usually requires thin and light, and a secondary battery can be used as the power supply.

[0280] The embodiments of the present application will be described below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation of the present application. For those technologies or conditions not specified in the embodiments, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0281] [Examples 1-20 and Comparative Examples 1-3]

[0282] Example 1

[0283] (1) Preparation of the positive electrode plate

[0284] The positive electrode active material lithium nickel cobalt manganese oxide (molar ratio of nickel, cobalt and manganese is 8:1:1), conductive agent carbon black, and binder polyimide are weighed according to a mass ratio of 97:1:2 and dissolved in the solvent N-methylpyrrolidone (NMP). After fully stirring and mixing evenly, a positive electrode slurry is obtained. Subsequently, the positive electrode slurry is evenly coated on both sides of the positive electrode current collector aluminum foil with a thickness of 13 μm along its thickness direction. After drying, cold pressing and cutting, a positive electrode plate with a total thickness of 140 μm and a width of 100 mm is obtained.

[0285] (2) Preparation of the negative electrode plate

[0286] The negative electrode active material artificial graphite, conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) are weighed according to a mass ratio of 95:1:2:2 and dissolved in deionized water as the solvent. After mixing evenly, a negative electrode slurry is prepared; the negative electrode slurry is 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 plate with a total thickness of 70 μm and a width of 105 μm is obtained.

[0287] The prefabricated negative electrode plate is placed on the conveying unit so that the conveying unit drives the prefabricated negative electrode plate to move, and the prefabricated negative electrode plate passes through the plasma heating unit to perform heat treatment on the prefabricated negative electrode plate, so that the temperature of the film layer surface of the prefabricated negative electrode plate reaches 300 °C at 50 ms. Among them, the temperature of the plasma heating is 1000 °C, the moving speed of the prefabricated negative electrode plate is 80 m / min, the distance between the plasma gun of the plasma heating unit and the film layer surface along the thickness direction of the prefabricated negative electrode plate is 25 mm, the flow rate of the gas to be ionized by the plasma heating is 10 L / min, the heating power of the plasma heating unit is 500 W, and the angle between the orientation of the plasma gun of the heating unit and the thickness direction of the prefabricated negative electrode plate is 60°.

[0288] (3) Preparation of the battery cell

[0289] The above-mentioned positive electrode plate, polyethylene separator, and heat-treated negative electrode plate are stacked in sequence, such that the separator is between the positive electrode plate and the negative electrode plate and can isolate the positive electrode plate from the negative electrode plate; then the stacked components are wound to obtain an electrode assembly; the electrode assembly is disposed in a housing, and after drying, an LiPF6 electrolyte with a mass fraction of 11% is injected, wherein the volume ratio of the organic solvent ethylene carbonate (EC) to ethyl methyl carbonate (EMC) in the electrolyte is 3:7; after processes such as formation and standing, a battery cell is obtained.

[0290] Example 2

[0291] Compared with Example 1, Example 2 changes the heating-up time (specified time) of the prefabricated negative electrode plate during the heat treatment, that is, the temperature of the film layer surface of the prefabricated negative electrode plate reaches 300 °C at 150 ms. Correspondingly, the moving speed of the prefabricated negative electrode plate during the heat treatment changes to 50 m / min.

[0292] Example 3

[0293] Compared with Example 1, Example 3 changes the heating-up temperature (specified temperature) of the prefabricated negative electrode plate during the heat treatment, that is, the temperature of the film layer surface of the prefabricated negative electrode plate reaches 700 °C at 50 ms. Correspondingly, compared with Example 1, some parameters of the plasma heating can be adjusted to match the heating-up temperature of the negative electrode plate: the temperature of the plasma heating is adjusted to 1200 °C, the distance between the plasma gun of the plasma heating unit and the film layer surface along the thickness direction of the prefabricated negative electrode plate is adjusted to 5 mm, the flow rate of the gas to be ionized for the plasma heating is adjusted to 100 L / min, the heating power of the plasma heating unit is adjusted to 15000 W, and the angle between the orientation of the plasma gun of the heating unit and the thickness direction of the prefabricated negative electrode plate is adjusted to 0°.

[0294] Example 4

[0295] Compared with Example 3, Example 4 changes the heating-up time (specified time) of the prefabricated negative electrode plate during the heat treatment, that is, the temperature of the film layer surface of the negative electrode plate reaches 700 °C at 200 ms. Correspondingly, compared with Example 3, some parameters of the plasma heating can be adjusted to match the heating-up time of the negative electrode plate: the temperature of the plasma heating is adjusted to 1100 °C, and the moving speed of the prefabricated negative electrode plate is adjusted to 25 m / min.

[0296] Example 5

[0297] Compared with Example 1, in Example 5, the way of heat treatment for the prefabricated negative electrode sheet and the temperature rise time (specified time) and temperature rise temperature (specified temperature) of the prefabricated negative electrode sheet during the heat treatment process are changed. 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 for heat treatment so that the temperature of the film layer surface of the prefabricated negative electrode sheet reaches 500 °C at 15 ms. Among them, the temperature of the arc heating is 1600 °C, the moving speed of the prefabricated negative electrode sheet is 200 m / min, the distance between the arc heating head of the arc heating unit and the film layer surface along the thickness direction of the prefabricated negative electrode sheet is 150 mm, the gas flow rate of the arc heating is 30 L / min, the heating power of the arc heating unit is 1000 W, and the included angle between the orientation of the arc heating unit and the thickness direction of the prefabricated negative electrode sheet is 60°.

[0298] Example 6

[0299] Compared with Example 5, in Example 6, the temperature rise time (specified time) of the prefabricated negative electrode sheet during the heat treatment process is changed, that is, the temperature of the film layer surface of the prefabricated negative electrode sheet reaches 500 °C at 50 ms. Correspondingly, the moving speed of the prefabricated negative electrode sheet during the heat treatment process changes to 160 m / min.

[0300] Example 7

[0301] Compared with Example 5, in Example 7, the temperature rise temperature (specified temperature) of the prefabricated negative electrode sheet during the heat treatment process is changed, that is, the temperature of the film layer surface of the prefabricated negative electrode sheet reaches 900 °C at 15 ms. Correspondingly, compared with Example 5, some parameters of the arc heating can be adjusted to match the temperature rise temperature of the prefabricated negative electrode sheet: the temperature of the arc heating is adjusted to 2000 °C, the distance between the arc heating head of the arc heating unit and the film layer surface along the thickness direction of the prefabricated negative electrode sheet is adjusted to 80 mm, the flow rate of the gas to be ionized for the arc heating is adjusted to 80 L / min, the heating power of the arc heating unit is adjusted to 8000 W, and the included angle between the orientation of the arc heating gun of the heating unit and the thickness direction of the prefabricated negative electrode sheet is adjusted to 0°.

[0302] Example 8

[0303] Compared with Example 1, Example 8 changed the way of heat treatment of the prefabricated negative electrode sheet, as well as the temperature rise time (specified time) and temperature rise temperature (specified temperature) of the prefabricated negative electrode sheet during the heat treatment 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 for heat treatment, so that the temperature of the film layer surface of the prefabricated negative electrode sheet reaches 400 °C at 20 ms. Among them, the temperature of the infrared heating is 1400 °C, the moving speed of the prefabricated negative electrode sheet is 160 m / min, the distance between the heating tube of the infrared heating unit and the film layer surface in the thickness direction of the prefabricated negative electrode sheet is 50 mm, and the heating power of the infrared heating unit is 1000 W.

[0304] Example 9

[0305] Compared with Example 8, Example 9 changed the temperature rise time (specified time) of the prefabricated negative electrode sheet during the heat treatment process, that is, the temperature of the film layer surface of the prefabricated negative electrode sheet reaches 400 °C at 60 ms. Accordingly, the moving speed of the prefabricated negative electrode sheet during the heat treatment process changes to 120 m / min.

[0306] Example 10

[0307] Compared with Example 8, Example 10 changed the temperature rise temperature (specified temperature) of the prefabricated negative electrode sheet during the heat treatment process, that is, the temperature of the film layer surface of the prefabricated negative electrode sheet reaches 900 °C at 20 ms. Accordingly, compared with Example 8, some parameters of the infrared heating can be adjusted to match the temperature rise temperature of the prefabricated negative electrode sheet: the temperature of the infrared heating is adjusted to 1800 °C, the distance between the heating lamp tube of the infrared heating unit and the film layer surface in the thickness direction of the prefabricated negative electrode sheet is adjusted to 5 mm, and the heating power of the infrared heating unit is adjusted to 5000 W.

[0308] Example 11

[0309] Compared with Example 1, Example 11 changed the way of heat treatment of the prefabricated negative electrode sheet, as well as the temperature rise time (specified time) and temperature rise temperature (specified temperature) of the prefabricated negative electrode sheet during the heat treatment 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 for infrared heat treatment, so that the temperature of the film layer surface of the prefabricated negative electrode sheet reaches 300 °C at 90 ms. Among them, the temperature of the electric heating is 1000 °C, the moving speed of the prefabricated negative electrode sheet is 80 m / min, the distance between the resistance wire of the electric heating unit and the film layer surface in the thickness direction of the prefabricated negative electrode sheet is 25 mm, and the heating power of the infrared heating unit is 500 W.

[0310] Example 12

[0311] Compared with Example 11, Example 12 changed the heating-up time (specified time) of the prefabricated negative electrode sheet during the heat treatment, that is, the temperature of the film layer surface of the prefabricated negative electrode sheet reached 300 °C at 150 ms. Accordingly, the moving speed of the prefabricated negative electrode sheet during the heat treatment changed to 50 m / min.

[0312] Example 13

[0313] Compared with Example 11, Example 13 changed the heating-up temperature (specified temperature) of the prefabricated negative electrode sheet during the treatment, that is, the temperature of the film layer surface of the prefabricated negative electrode sheet reached 700 °C at 90 ms. Accordingly, compared with Example 11, some parameters of the electric heating can be adjusted to match the heating-up temperature of the prefabricated negative electrode sheet: the temperature of the electric heating is adjusted to 1300 °C, the distance between the resistance wire of the electric heating unit and the film layer surface along the thickness direction of the prefabricated negative electrode sheet is adjusted to 5 mm, and the heating power of the electric heating unit is adjusted to 14000 W.

[0314] Example 14

[0315] Compared with Example 1, Example 14 changed the heating treatment method of the prefabricated negative electrode sheet, as well as the heating-up time (specified time) and heating-up temperature (specified temperature) of the prefabricated negative electrode sheet during the heat treatment. That is, in Example 13, during the movement of the prefabricated negative electrode sheet, the prefabricated negative electrode sheet was passed through the magnetron of the microwave heating unit to perform microwave heating treatment on the prefabricated negative electrode sheet, so that the temperature of the film layer surface of the prefabricated negative electrode sheet reached 300 °C at 50 ms. Among them, the temperature of the microwave heating is 1300 °C, the moving speed of the prefabricated negative electrode sheet is 120 m / min, the distance between the magnetron of the microwave heating unit and the film layer surface along the thickness direction of the prefabricated negative electrode sheet is 25 mm, and the heating power of the microwave heating unit is 2000 W.

[0316] Example 15

[0317] Compared with Example 14, Example 15 changed the heating-up time (specified time) of the prefabricated negative electrode sheet during the heat treatment, that is, the temperature of the film layer surface of the prefabricated negative electrode sheet reached 300 °C at 120 ms. Accordingly, the moving speed of the prefabricated negative electrode sheet during the heat treatment changed to 80 m / min.

[0318] Example 16

[0319] Compared with Example 14, Example 16 changes the heating-up temperature (specified temperature) during the heat treatment of the prefabricated negative electrode sheet, that is, the temperature of the film layer surface of the prefabricated negative electrode sheet reaches 800 °C at 50 ms. Correspondingly, compared with Example 14, some parameters of the microwave heating can be adjusted to match the heating-up temperature of the prefabricated negative electrode sheet: the temperature of the microwave heating is adjusted to 1800 °C, the distance between the magnetron of the microwave heating unit and the film layer surface along the thickness direction of the prefabricated negative electrode sheet is adjusted to 5 mm, and the heating power of the microwave heating unit is adjusted to 10000 W.

[0320] Example 17

[0321] Compared with Example 1, Example 17 adds a hot air treatment to the prefabricated negative electrode sheet. Among them, the temperature of the hot air treatment is 300 °C, the hot air flow rate of the hot air treatment is 50 L / min, the included angle between the orientation of 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 moving 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 layer surface is the same as the distance between the heating unit and the film layer surface.

[0322] Example 18

[0323] Compared with Example 17, Example 18 changes the temperature of the hot air treatment and adjusts the temperature of the hot air treatment to 600 °C. Correspondingly, the hot air flow rate of the hot air treatment is adjusted to 300 L / min to match the adjustment of the temperature of the hot air treatment.

[0324] Example 19

[0325] Compared with Example 17, Example 19 adjusts the included angle between the orientation of the hot air nozzle and the thickness direction of the prefabricated negative electrode sheet to 0°.

[0326] Example 20

[0327] Compared with Example 17, Example 20 adjusts the distance between the hot air nozzle and the heating unit along the moving direction of the prefabricated negative electrode sheet to 15 mm.

[0328] Comparative Example 1

[0329] Compared with Example 1, in Comparative Example 1, the negative electrode sheet is not heat-treated. That is, neither the positive electrode sheet nor the negative electrode sheet in Comparative Example 1 is heat-treated.

[0330] Comparative Example 2

[0331] Compared with Example 1, Comparative Example 2 changed the heating temperature of the prefabricated negative electrode sheet during the heat treatment process. That is, in Comparative Example 2, the positive electrode sheet was not heat-treated; during the movement of the prefabricated negative electrode sheet, the prefabricated negative electrode sheet was passed through the plasma heating unit to perform heat treatment on the prefabricated negative electrode sheet, so that the temperature of the film layer surface of the prefabricated negative electrode sheet reached 250 °C at 50 ms. Correspondingly, compared with Example 1, some parameters of the plasma heating can be adjusted to match the heating temperature of the negative electrode sheet: the temperature of the plasma heating is adjusted to 800 °C, the flow rate of the gas to be ionized by the plasma heating is adjusted to 8 L / min, the heating power of the plasma heating unit is adjusted to 400 W, 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 °.

[0332] Comparative Example 3

[0333] Compared with Example 1, Comparative Example 3 changed the heating time and heating temperature during the heat treatment process of the prefabricated negative electrode sheet. That is, in Comparative Example 3, the positive electrode sheet was not heat-treated; during the movement of the negative electrode sheet, the prefabricated negative electrode sheet was passed through the plasma heating unit to perform heat treatment on the prefabricated negative electrode sheet, and the temperature of the film layer surface of the prefabricated negative electrode sheet reached 80 °C at 10 ms. Correspondingly, some parameters of the plasma heating can be adjusted to match the heating time and heating temperature of the negative electrode sheet: the temperature of the plasma heating is adjusted to 1200 °C, the moving speed of the negative electrode sheet is adjusted to 200 m / min, the distance between the plasma gun of the plasma heating unit and the film layer surface along the thickness direction of the electrode sheet is adjusted to 5 mm, the flow rate of the gas to be ionized by the plasma heating is adjusted to 100 L / min, the heating power of the plasma heating unit is adjusted to 15000 W, and the angle between the orientation of the plasma gun of the heating unit and the thickness direction of the electrode sheet is adjusted to 0 °.

[0334] For the parameter settings of preparing the negative electrode sheet in specific examples and comparative examples, please refer to Tables 1 to 7.

[0335] Table 1 Parameter Settings of Examples 1 to 4

[0336]

[0337] Table 2 Parameter Settings of Examples 5 to 7

[0338]

[0339] Table 3 Parameter Settings of Examples 8 to 10

[0340]

[0341]

[0342] Table 4 Parameter Settings of Examples 11 to 13

[0343]

[0344] Table 5 Parameter Settings of Examples 14 to 16

[0345]

[0346] Table 6 Parameter Settings of Examples 17 and 20

[0347]

[0348] Table 7 Parameter Settings of Comparative Examples 1 to 3

[0349]

[0350] In Tables 1 to 7, T1 is the specified temperature, t is the specified time, that is, the surface of the film layer reaches the specified temperature T1 at the specified time t. T2 is the temperature of the heat treatment, V is the moving speed of the prefabricated negative electrode sheet, D is the distance between the heating unit and the surface of the film layer along the thickness direction of the prefabricated negative electrode sheet, L1 is the flow rate of the gas to be ionized for plasma heating or the gas flow rate for arc heating, P is the heating power of the heating unit under different heating methods, and 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 moving direction of the prefabricated negative electrode sheet, and d2 is the distance between the hot air nozzle and the surface of the film layer along the thickness direction of the prefabricated negative electrode sheet.

[0351] Perform the following performance tests on the negative electrode sheets and battery cells obtained in Examples 1 to 20 and Comparative Examples 1 to 3:

[0352] (1) Resistance of the electrode sheet

[0353] Use the membrane resistance tester of Yuanneng Technology to test the membrane resistance. Cut small round pieces with a diameter of 10 mm at the left, middle, and right of the electrode sheet respectively. Turn on the indicator light of the electrode sheet resistance tester of Yuanneng Technology, place the small round piece at the appropriate position of the "probe" of the electrode sheet resistance tester, click the "Start" button, wait for the reading to be stable, and then read it. Each small round piece is tested at two positions, and finally calculate the average value of the six measurements, which is the resistance of the electrode sheet.

[0354] (2) Electrolyte absorption time of the electrode sheet

[0355] Fix the electrode on a clean glass plate. After sucking 3 mm height of electrolyte (the electrolyte composition includes EC, DMC and EMC with a volume ratio of 3:2:1, and 1 mol / L lithium salt LiPF6) using a capillary with an inner diameter of 0.3 mm, make the capillary contact the electrode vertically so that the electrode absorbs the electrolyte, and measure the time when the electrode finishes absorbing the electrolyte.

[0356] (3) Battery single - cell capacity

[0357] Charge the battery single - cell at a constant current of 1C to the charge cut - off voltage (about 4.2 V) at 25°C. After leaving it standing for 1 h at 25°C, discharge it at a constant current of 1C to the discharge cut - off voltage (about 2.5 V), and record the discharged capacity.

[0358] (4) Battery single - cell first - cycle efficiency

[0359] Charge the battery single - cell for the first time at a constant current of 1C to the charge cut - off voltage (about 4.2 V) at 25°C, and record the charged capacity; after leaving it standing for 1 h at 25°C, discharge it at a constant current of 1C to the discharge cut - off voltage (about 2.5 V), and record the discharged capacity. Calculate the ratio of the first - discharge capacity to the first - charge capacity.

[0360] (5) Battery single - cell K value

[0361] Charge the battery single - cell to 20% of its capacity, then record the open - circuit voltage OCV1 of the battery single - cell. Subsequently, transfer it to stand still at 25°C for 48 h, and measure the open - circuit voltage OCV2 of the battery single - cell again. The K value is (OCV1 - OCV2) / 48, with the unit of mV / h. Among them, when charging, the charging capacity of the first full - charge of the battery single - cell can be used as the capacity of the battery single - cell, and when discharging, the discharging capacity of the first full - discharge can be used as the capacity of the battery single - cell.

[0362] The performance test results of the electrodes and battery single - cells in the above Examples 1 to 20 and Comparative Examples 1 to 3 are shown in Table 8 in detail.

[0363] Table 8 Performance test results of electrodes and battery single - cells in different examples and comparative examples

[0364]

[0365]

[0366] The negative electrode sheets prepared in Examples 1 to 20 have a lower sheet resistance than those in Comparative Examples 1 to 3, and the liquid absorption time of the electrolyte is less than that in Comparative Examples 1 to 3. The capacities and initial coulombic efficiencies of the battery monomers prepared from the negative electrode sheets in Examples 1 to 20 are higher than those of the battery monomers prepared from the negative electrode sheets in Comparative Examples 1 to 3, and the K values of the battery monomers prepared from the negative electrode sheets in Examples 1 to 20 are lower than those of the battery monomers prepared from the negative electrode sheets in Comparative Examples 1 to 3.

[0367] In Examples 1 to 4, Examples 5 to 7, Examples 8 to 10, Examples 11 to 13, and Examples 14 to 16, plasma heating, arc heating, infrared heating, electric heating, and microwave heating methods were respectively adopted.

[0368] In the embodiments of the present application, by performing a heat treatment on the prefabricated negative electrode sheet, the sheet resistance of the negative electrode sheet can be reduced, which is beneficial to the transmission of lithium ions, thereby improving the performance of the battery. For example, the graphitization degree, the orientation degree of graphite, and the removal of impurities on the surface of the negative electrode sheet can be improved through the heat treatment, reducing the resistance of the negative electrode sheet.

[0369] Under the action of high temperature, burrs, particulate matters, etc. generated by cutting 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 the separator being pierced, and further improving the K value (voltage drop per unit time) of the battery; on the other hand, the ablation of impurities such as burrs and particulate matters can reduce the 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 coulombic efficiency of the battery monomer prepared from the negative electrode sheet.

[0370] In the embodiments of the present application, when the temperature of the prefabricated negative electrode sheet rises, the binder in the electrode sheet can be softened or ablated, thereby removing part of the binder in the electrode sheet and increasing the porosity of the electrode sheet. The increase in porosity can increase the channels for electrolyte infiltration in the electrode sheet, improve the infiltration rate of the electrolyte, and thus increase the transmission rate of lithium ions, further improving the performance of the battery.

[0371] Compared with Example 1, in the process of heat-treating the prefabricated negative electrode sheet in Examples 17 to 20, hot air treatment was also performed on the prefabricated negative electrode sheet. The negative electrode sheets prepared in Examples 17 to 20 have a lower sheet resistance than that of Example 1, and the liquid absorption time of the electrolyte is less than that of Example 1. The capacities and initial coulombic efficiencies of the battery monomers prepared from the negative electrode sheets in Examples 17 to 20 are higher than those of the battery monomers prepared from the negative electrode sheets in Example 1, and the K values of the battery monomers prepared from the negative electrode sheets in Examples 17 to 20 are slightly lower than those of the battery monomers prepared from the negative electrode sheets in Example 1.

[0372] 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.

[0373] 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, Including: 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; Performing a heat treatment on a specified part of the film layer to raise the temperature of the specified part to a specified temperature within a specified time, where the specified part includes at least part 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, wherein The specified time is 15 ms to 150 ms, 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 arranged relative to the surface of the film layer along the thickness direction of the prefabricated electrode sheet, and the heating unit is used to perform the heat treatment on the specified part, where the distance between the heating unit and the surface of the film layer along the thickness direction of the prefabricated electrode sheet is 5 mm to 150 mm, and / or The temperature of the heat treatment is 1000 °C to 2000 °C.

4. The preparation method according to claim 3, characterized in that, Before performing the heat treatment on the specified part of the film layer, the method further includes: moving the prefabricated electrode sheet by a conveying unit; The performing the heat treatment on the specified part of the film layer includes: Using the heating unit to perform the heat treatment on the specified part during the movement of the prefabricated electrode sheet, and the heating unit is fixedly arranged between the starting point and the ending point of the movement of the prefabricated electrode sheet.

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

6. The preparation method according to any one of claims 1 to 5, characterized in that, The heat 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 performing the heat treatment on the specified part of the film layer includes: performing plasma heating on the specified part to raise the temperature of the specified part to 300 °C to 700 °C within 50 ms to 150 ms.

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 sheet 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 electrode sheet is 50 m / min to 80 m / min, where the heating unit includes the plasma 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 for the 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 included angle between the orientation of the plasma heating unit and the thickness direction of the prefabricated electrode sheet is 0° to 60°.

10. The preparation method according to any one of claims 3 to 6, characterized in that, The performing the heat treatment on the specified part of the film layer includes: performing arc heating on the specified part to raise the temperature of the specified part 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 sheet is 80 mm to 150 mm, and / or The temperature of the arc heating 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 30 L / min to 80 L / min; (2) The heating power of the arc heating unit is 1000 W to 8000 W; (3) The angle between the orientation of the arc heating unit and the thickness direction of the prefabricated pole piece 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 part of the film layer includes: performing infrared heating on the designated part to raise the temperature of the designated part to 400°C to 900°C within 20 ms to 60 ms.

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 pole piece is 5 mm to 50 mm, and / or, The temperature of the infrared heating 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 satisfies the following condition: the heating power of the infrared heating unit is 1000 W to 5000 W.

16. The preparation method according to any one of claims 3 to 6, characterized in that, The heating treatment of the designated part of the film layer includes: performing electric heating on the designated part to raise the temperature of the designated part to 300°C to 700°C within 90 ms to 150 ms.

17. The preparation method according to claim 16, wherein The distance between the electric 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 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 satisfies the following condition: the heating power of the electric heating unit is 500 W to 14000 W.

19. The preparation method according to any one of claims 3 to 6, characterized in that, The heating treatment of the designated part of the film layer includes: performing microwave heating on the designated part to raise the temperature of the designated part 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 pole piece is 5 mm to 25 mm, and / or, The temperature of the microwave heating 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 satisfies the following condition: the heating power of the microwave heating unit is 2000 W to 10000 W.

22. The preparation method according to any one of claims 1 to 21, characterized in that, The method further includes: During the heating treatment of the designated part, hot air treatment is performed on the designated part by using a hot air nozzle, the hot air nozzle is fixedly arranged between the moving starting point and the moving ending point of the prefabricated pole piece, and the hot air nozzle is oppositely arranged with the surface of the film layer along the thickness direction of the prefabricated pole piece.

23. The preparation method according to claim 22, wherein 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.

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 50 L / min to 300 L / min; (2) The angle between the orientation 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.

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 50 L / min to 200 L / min; (2) The angle between the orientation 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 heating the designated part of the film layer, the method further includes: Performing one or more of the following treatments on the prefabricated electrode: drying treatment, tablet pressing treatment or cutting treatment.

28. The preparation method according to any one of claims 1 to 27, characterized in that, The designated part includes the part 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 electrode is prepared by the preparation method according to any one of claims 1 to 28.

30. A battery, characterized in that, The battery includes the electrode according to claim 29.

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

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