Positive electrode sheet, method for manufacturing the same, and battery

Abstract

This application provides a positive electrode sheet, its preparation method, and a battery. The preparation method includes the following steps: Step S1, sequentially mixing and pre-fiberizing a positive electrode active material with a binder to obtain a first intermediate; Step S2, sequentially mixing, pre-fiberizing, and second-fiberizing the first intermediate with a conductive agent to obtain a second intermediate; Step S3, calendering the second intermediate into a film and then combining it with a current collector to obtain a positive electrode sheet. In Step S1, sequentially mixing and pre-fiberizing the positive electrode active material with the binder helps to coat the surface of the positive electrode active material with the binder, thereby increasing the lubricity and reducing the hardness of the positive electrode active material. Therefore, the positive electrode sheet prepared by the method of this application has high mechanical strength, liquid absorption, uniformity, and consistency.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a positive electrode sheet, a method for preparing the same, and a battery. Background Technology

[0002] Compared to wet electrodes, dry electrode manufacturing is simpler, more flexible, and an environmentally friendly process. However, applying dry processes to positive electrodes presents significant challenges. Firstly, the inherent characteristics of positive electrode materials lead to difficulties in film formation, low strength, and poor consistency. To address these issues, Chinese patent application CN116914088A discloses a low-cost lithium battery manufacturing method. This method involves applying shear force to active materials, conductive agents, and binders at a specific temperature, causing the mixture to fibrose. The fibrous negative electrode mixture is then used to prepare a dry negative electrode. An electrolyte is added to the fibrous positive electrode mixture and mixed to obtain a semi-dry electrode, which is then assembled with the dry negative electrode to form a lithium battery. However, this method is not a fully dry electrode process. Chinese patent application CN116825972A discloses a dry electrode preparation process and its application. First, LFP (lithium iron phosphate), a conductive agent, and PTFE (polytetrafluoroethylene) are prepared. These materials are then mixed in dry powder form using a direct mixing process, shortening the existing process flow. During electrode fabrication, an ultra-high-speed disperser is used to uniformly disperse the powder using high-speed airflow shearing, thereby improving the electrode's capacity and reducing its internal resistance. However, this method is not a completely dry process. Incompletely dry methods present the problem of toxic solvents. Summary of the Invention

[0003] The main objective of this application is to provide a positive electrode sheet, its preparation method, and a battery, in order to solve the problems of difficult film formation, low strength, and poor consistency of positive electrode sheets prepared by dry methods in the prior art.

[0004] To achieve the above objectives, according to one aspect of this application, a method for preparing a positive electrode sheet is provided, the method comprising the following steps: Step S1, sequentially mixing a positive electrode active material with a binder and performing a first mixing and pre-fiberization treatment to obtain a first intermediate; Step S2, sequentially mixing the first intermediate with a conductive agent, performing a first fiberization treatment and a second fiberization treatment to obtain a second intermediate; Step S3, calendering the second intermediate into a film and then combining it with a current collector to obtain a positive electrode sheet.

[0005] Further, in step S2 above, the temperature of the second mixing is 5-19°C; and / or, the time of the second mixing is 4-25 min; and / or, the second mixing is carried out in the first mixer; and / or, the rotation speed of the second mixing is 250-1500 rpm; further, the second mixing includes a second A mixing and a second B mixing performed sequentially; the rotation speed of the second A mixing is 1100-1500 rpm; and / or, the time of the second A mixing is 2-10 min; the rotation speed of the second B mixing is 250-400 rpm; and / or, the time of the second B mixing is 2-15 min.

[0006] Further, in step S2 above, the temperature of the first fiberization treatment is 60-100°C; and / or, when the particle size of the first fiberization treatment is less than 20 μm, the first fiberization treatment is stopped; and / or, the first fiberization treatment is carried out in a first airflow shearing machine; further, the airflow shearing intensity of the first airflow shearing machine is 0.45-0.6 MPa; and / or, the rotation speed of the first airflow shearing machine is 2500-5000 rpm.

[0007] Further, in step S2 above, the temperature of the second fiberization treatment is 60-90°C; and / or, the time of the second fiberization treatment is 30-120s; and / or, the second fiberization treatment is carried out in a kneading machine; further, the rotation speed of the kneading machine is 5-35rpm.

[0008] Furthermore, after the first fiberization treatment in step S2 is completed, the product of the first fiberization treatment is first subjected to heat treatment, and then subjected to the second fiberization treatment; and / or, the heat treatment temperature is 100-200℃; and / or, the heat treatment time is 0.5-2h.

[0009] Further, in step S1 above, the temperature of the first mixing is 5 to 19°C; and / or, the time of the first mixing is 5 to 10 minutes; and / or, the first mixing is carried out in a second mixer, the rotation speed of the second mixer is 150 to 200 rpm.

[0010] Further, the temperature of the prefiberization treatment is 5 to 19°C; and / or, the prefiberization treatment is stopped when the particle size of the prefiberized particles is less than 20 μm; and / or, the prefiberization treatment is carried out in a second airflow shearing machine; further, the airflow shearing intensity of the second airflow shearing machine is 0.4 to 0.8 MPa; and / or, the rotation speed of the second airflow shearing machine is 3000 to 5000 rpm.

[0011] Furthermore, the calendering temperature is 100–130°C; and / or the lamination temperature is 100–130°C; and / or the lamination pressure is 6–10t.

[0012] According to another aspect of this application, a positive electrode is provided, which is prepared by the aforementioned preparation method.

[0013] According to another aspect of this application, a battery is provided, comprising a positive electrode, an electrolyte, and a negative electrode, wherein the positive electrode is the aforementioned positive electrode.

[0014] Applying the technical solution of this application, in step S1, by sequentially performing a first mixing and pre-fiberization treatment on the positive electrode active material and the binder, it is helpful to coat the surface of the positive electrode active material with the binder, thereby increasing the lubricity of the positive electrode active material and reducing its hardness. If the positive electrode active material is not mixed with the binder first, the conductive agent easily encapsulates the binder, which is not conducive to improving the dispersion uniformity of the positive electrode active material. At the same time, the binder encapsulated by the conductive agent is not easily fiberized, which is not conducive to improving the mechanical strength of the positive electrode sheet. In step S2, the first fiberization treatment and the second fiberization treatment help to increase the bonding strength between the binder and the positive electrode active material, and also help to increase the degree of fiberization of the binder, thereby helping to improve the mechanical strength of the positive electrode sheet. Therefore, the positive electrode sheet prepared by the preparation method of this application has high mechanical strength, liquid absorption, uniformity and consistency. Detailed Implementation

[0015] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the embodiments.

[0016] Terminology Explanation: NCM refers to nickel-cobalt-manganese ternary cathode material.

[0017] As analyzed in the background section of this application, the existing dry-processed positive electrode sheets have problems such as difficulty in film formation, low strength, and poor consistency. In order to solve the above problems, this application provides a positive electrode sheet, its preparation method, and a battery.

[0018] In a typical embodiment of this application, a method for preparing a positive electrode sheet is provided, the method comprising the following steps: Step S1, sequentially mixing a positive electrode active material with a binder and performing a first mixing and pre-fiberization treatment to obtain a first intermediate; Step S2, sequentially mixing the first intermediate with a conductive agent, performing a first fiberization treatment and a second fiberization treatment to obtain a second intermediate; Step S3, calendering the second intermediate into a film and then combining it with a current collector to obtain a positive electrode sheet.

[0019] In step S1, the sequential mixing and pre-fiberization of the positive electrode active material and binder helps to coat the surface of the positive electrode active material with the binder, thereby increasing the lubricity and reducing the hardness of the positive electrode active material. If the positive electrode active material is not mixed with the binder first, the conductive agent easily encapsulates the binder, which is not conducive to improving the dispersion uniformity of the positive electrode active material. At the same time, the binder encapsulated by the conductive agent is not easily fiberized, which is not conducive to improving the mechanical strength of the positive electrode sheet. In step S2, the first and second fiberization treatments help to increase the bonding strength between the binder and the positive electrode active material, and also help to increase the degree of fiberization of the binder, thereby helping to improve the mechanical strength of the positive electrode sheet. Therefore, the positive electrode sheet prepared by the preparation method of this application has high mechanical strength, liquid absorption, uniformity and consistency.

[0020] In one embodiment of this application, in step S2 above, the temperature of the second mixing is 5-19°C; and / or, the time of the second mixing is 4-25 min; and / or, the second mixing is carried out in a first mixer; and / or, the rotation speed of the second mixing is 250-1500 rpm; in one embodiment of this application, the second mixing includes a second A mixing and a second B mixing performed sequentially; the rotation speed of the second A mixing is 1100-1500 rpm; and / or, the time of the second A mixing is 2-10 min; the rotation speed of the second B mixing is 250-400 rpm; and / or, the time of the second B mixing is 2-15 min.

[0021] Controlling the temperature of the second mixing process within the aforementioned range helps reduce premature curing or adverse phase changes in the binder, resulting in higher fluidity of the binder during subsequent fiberization. This, in turn, improves the fiberization efficiency and uniformity of the mixture. Controlling the time of the second mixing process within the aforementioned range also helps improve mixing efficiency. The second mixing process employs a combination of high-speed and low-speed mixing. High-speed mixing helps to rapidly disperse the conductive agent, reducing its excessive accumulation on the binder surface, while low-speed mixing helps to improve the uniformity of the mixture and reduce agglomeration.

[0022] In one embodiment of this application, in step S2 above, the temperature of the first fiberization treatment is 60-100°C; and / or, when the particle size of the first fiberization treatment is less than 20 μm, the first fiberization treatment is stopped; and / or, the first fiberization treatment is carried out in a first airflow shearing machine; in one embodiment of this application, the airflow shearing intensity of the first airflow shearing machine is 0.45-0.6 MPa; and / or, the rotation speed of the first airflow shearing machine is 2500-5000 rpm.

[0023] Low-temperature fiberization treatment enhances the binder's flexibility and plasticity, making it easier to form fibrous structures through airflow shearing. Controlling the first fiberization treatment time within the aforementioned range helps improve its efficiency. The use of a first airflow shearing machine improves the consistency and repeatability of the fiberization process. Insufficient strength hinders the degree of binder fiberization, while excessive strength may damage the positive electrode active material. Controlling the airflow shearing intensity of the first airflow shearing machine within the aforementioned range helps improve the binder fiberization efficiency, forming a dense fiber network. This enhances the connection between positive electrode active material particles and also improves the mechanical strength and liquid absorption of the positive electrode sheet. Controlling the rotation speed of the first fiberization treatment within the aforementioned range helps improve the binder fiberization efficiency, allowing the binder fibers to distribute rapidly and uniformly on the surface of the positive electrode active material, forming a good bond.

[0024] In one embodiment of this application, in step S2 above, the temperature of the second fiberization treatment is 60-90°C; and / or, the time of the second fiberization treatment is 30-120s; and / or, the second fiberization treatment is carried out in a kneading machine, and in one embodiment of this application, the kneading machine is an internal mixer; in one embodiment of this application, the rotation speed of the kneading machine is 5-35rpm.

[0025] Controlling the temperature of the second fiberization process within the aforementioned range helps improve the fluidity of the binder, facilitating the movement of its internal chain segments and the fiberization process. This accelerates the crystal orientation transformation of the binder, promotes the formation of fiber structures, and thus helps improve the mechanical strength and stability of the cathode sheet. Controlling the time of the second fiberization process within the aforementioned range helps improve its efficiency. Performing the second fiberization process in a kneading machine helps promote the deep integration of binder fibers on the surface of the cathode active material, increasing the uniformity and continuity of fiberization. The differential kneading action of the kneading machine can penetrate deep into the material, further unfolding insufficiently fiberized binder particles to form a denser fiber network. The internal mixer, through staggered-speed roller kneading, causes a crystal orientation transformation in the binder that has not been sheared, gradually pulling apart the lamellar structure and extracting the fibrils within the fibers, thus increasing the degree of binder fiberization. Controlling the rotation speed of the second fiberization process within the aforementioned range helps to promote better stretching and interweaving of the binder fibers during kneading, forming a more stable fiber structure, thereby helping to improve the mechanical strength of the cathode sheet.

[0026] In one embodiment of this application, after the first fiberization treatment in step S2 is completed, the product of the first fiberization treatment is first subjected to heat treatment, and then subjected to a second fiberization treatment; and / or, the temperature of the heat treatment is 100 to 200°C; and / or, the heat treatment time is 0.5 to 2 hours.

[0027] Controlling the temperature and time of heat treatment within the above range helps to promote the melting and recrystallization of the binder, enhances the bonding force between the positive electrode active material and the binder, and enables the binder to better wrap and adhere to the positive electrode material particles in the subsequent secondary fiberization process, forming a more stable structure.

[0028] In one embodiment of this application, in step S1 above, the temperature of the first mixing is 5 to 19°C; and / or, the time of the first mixing is 5 to 10 minutes; and / or, the first mixing is carried out in a second mixer, and the rotation speed of the second mixer is 150 to 200 rpm.

[0029] Controlling the temperature of the first mixing step within the aforementioned range helps improve the stability of the binder, reducing premature melting or structural changes caused by excessively high temperatures. This facilitates the uniform distribution of the binder on the surface of the positive electrode active material, forming a good coating layer and increasing the interaction between materials. Too short a first mixing time can lead to insufficient mixing, while too long a time may cause overheating or mechanical wear, affecting material performance. Controlling the first mixing time within the aforementioned range helps improve the efficiency of the first mixing step. Controlling the rotation speed of the first mixing step within the aforementioned range helps reduce the probability of fiberization in the binder, thereby improving the uniformity of dispersion between the binder and the positive electrode active material.

[0030] In one embodiment of this application, the temperature of the pre-fiberization treatment is 5 to 19°C; and / or, the pre-fiberization treatment is stopped when the particle size of the pre-fiberized particles is less than 20 μm; and / or, the pre-fiberization treatment is carried out in a second airflow shearing machine; in one embodiment of this application, the airflow shearing intensity of the second airflow shearing machine is 0.4 to 0.8 MPa; and / or, the rotation speed of the second airflow shearing machine is 3000 to 5000 rpm.

[0031] Pre-fiberization treatment helps improve the bonding force between the binder and the positive electrode active material, thereby further improving the lubricity of the positive electrode active material and reducing its hardness. Controlling the temperature, time, and rotation speed of the pre-fiberization treatment within the aforementioned range helps control the degree of fiberization of the binder, thereby further improving the mechanical strength of the positive electrode sheet.

[0032] In order to improve the mechanical strength of the positive electrode and the uniformity and consistency of the film formation, in one embodiment of this application, the calendering temperature is 100-130°C; and / or the composite temperature is 100-130°C; and / or the composite pressure is 6-10t.

[0033] In one embodiment of this application, the current collector is a carbon-coated current collector.

[0034] In one embodiment of this application, the mass ratio of the above-mentioned positive electrode active material, binder and conductive agent is 90-95:1-4:1-5.

[0035] The positive electrode active material, binder, and conductive agent of this application can be made from raw materials commonly used in the art. Including but not limited to, the positive electrode active material is selected from any one or more of lithium iron phosphate, lithium manganese iron phosphate, and ternary NCM systems, where the ternary NCM system is any one of NCM111, NCM523, NCM622, and NCM811. The binder is polytetrafluoroethylene. The conductive agent is selected from any one or more of SP, VGCF, CNT, KS-6, and KS-15.

[0036] In another typical embodiment of this application, a positive electrode is provided, which is prepared by the aforementioned preparation method.

[0037] Since the above-mentioned positive electrode sheet is prepared using the preparation method of this application, it has high mechanical strength, liquid absorption, uniformity, and consistency. The thickness of the positive electrode active layer in the positive electrode sheet is 50 μm to 500 μm.

[0038] In another typical embodiment of this application, a battery is provided, comprising a positive electrode, an electrolyte, and a negative electrode, wherein the positive electrode is the aforementioned positive electrode.

[0039] Because the battery contains the positive electrode of this application, it has high initial efficiency and cycle stability.

[0040] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0041] Example 1

[0042] The ternary NCM811 and the binder PTFE were first mixed in a second mixer at a temperature of 16°C and a speed of 150 rpm for 10 minutes to obtain a mixed material. The mixed material was then placed in a second airflow shear mill for prefiberization treatment at a temperature of 16°C. The prefiberization treatment was stopped when the particle size of the prefiberized particles was less than 20 μm. The airflow shear strength of the second airflow shear mill was 0.45 MPa and the speed of the second airflow shear mill was 3000 rpm to obtain a first intermediate.

[0043] The first intermediate and the conductive agent SP were mixed sequentially in a first mixer for a second A mixture and a second B mixture. The temperature of the second A mixture and the second B mixture was 16°C. The speed of the second A mixture was 1100 rpm and the time of the second A mixture was 10 min. The speed of the second B mixture was 250 rpm and the time of the second B mixture was 15 min, thus obtaining the second mixed intermediate.

[0044] The second mixed intermediate was subjected to a first fiberization treatment by a first airflow shearing machine. When the particle size of the first fiberized particles was less than 20 μm, the first fiberization treatment was stopped. The temperature of the first fiberization treatment was 100℃, the airflow shearing intensity of the first airflow shearing machine was 0.45 MPa, and the rotation speed of the first airflow shearing machine was 2500 rpm, thus obtaining the first fiberized intermediate.

[0045] The first fiberization intermediate was heat-treated at 100°C for 30 minutes to obtain a heat-treated intermediate. The heat-treated intermediate was then placed in an internal mixer for a second fiberization treatment at 90°C for 30 seconds. The internal mixer rotated at 10 rpm to obtain a second fiberization intermediate.

[0046] The second fibrous intermediate was calendered into a film at a temperature of 100℃ to obtain a self-supported film. This self-supported film was then composited with a current collector at a temperature of 100℃ and a pressure of 6t to obtain a positive electrode sheet. The thickness of the positive electrode active layer in the positive electrode sheet was 50μm, and the mass ratio of ternary NCM811, binder PTFE, and conductive agent SP was 90:4:1.

[0047] Example 2

[0048] The difference from Example 1 is that the second fiberization process takes 60 seconds, and a positive electrode sheet is finally obtained.

[0049] Example 3

[0050] The difference from Example 1 is that the second fiberization process takes 120 seconds, and a positive electrode sheet is finally obtained.

[0051] Example 4

[0052] The difference from Example 1 is that the second fiberization process takes 20 seconds, and a positive electrode sheet is finally obtained.

[0053] Example 5

[0054] The difference from Example 1 is that the rotation speed of the second A mixture is 1500 rpm and the mixing time of the second A mixture is 10 min; the rotation speed of the second B mixture is 250 rpm and the mixing time of the second A mixture is 15 min, and finally a positive electrode sheet is obtained.

[0055] Example 6

[0056] The difference from Example 1 is that the rotation speed of the second A mixture is 1100 rpm and the mixing time of the second A mixture is 10 min; the rotation speed of the second B mixture is 400 rpm and the mixing time of the second A mixture is 15 min, and finally a positive electrode sheet is obtained.

[0057] Example 7

[0058] The difference from Example 1 is that the second B mixing is omitted, the rotation speed of the second A mixing is 1100 rpm, and the time of the second A mixing is 25 min, finally obtaining the positive electrode sheet.

[0059] Example 8

[0060] The difference from Example 1 is that the airflow shearing intensity of the first airflow shearing machine is 0.45 MPa, the rotation speed of the first airflow shearing machine is 5000 rpm, and finally a positive electrode sheet is obtained.

[0061] Example 9

[0062] The difference from Example 1 is that the airflow shearing intensity of the first airflow shearing machine is 0.6 MPa, the rotation speed of the first airflow shearing machine is 2500 rpm, and the positive electrode sheet is finally obtained.

[0063] Example 10

[0064] The difference from Example 1 is that the temperature of the first fiberization treatment is 50°C, and the positive electrode sheet is finally obtained.

[0065] Example 11

[0066] The difference from Example 1 is that the heat treatment time is 2 hours, and the positive electrode sheet is finally obtained.

[0067] Example 12

[0068] The difference from Example 1 is that the heat treatment time is 20 minutes, and the positive electrode is finally obtained.

[0069] Example 13

[0070] The difference from Example 1 is that the rotation speed of the second mixer is 200 rpm, the first mixing time is 5 min, and the positive electrode sheet is finally obtained.

[0071] Example 14

[0072] The difference from Example 1 is that the second mixer rotates at 500 rpm and the first mixing time is 10 min, ultimately yielding a positive electrode sheet.

[0073] Example 15

[0074] The difference from Example 1 is that the rotation speed of the second airflow shear is 5000 rpm, and the positive electrode sheet is finally obtained.

[0075] Example 16

[0076] The difference from Example 1 is that the rotation speed of the second airflow shear is 8000 rpm, and the positive electrode sheet is finally obtained.

[0077] Comparative Example 1

[0078] The difference from Example 1 is that the second fiberization process is omitted, and the positive electrode sheet is finally obtained.

[0079] Comparative Example 2

[0080] The difference from Example 1 is that the first mixing and pre-fiberization treatment is omitted, and the positive electrode sheet is finally obtained.

[0081] Pouch cell assembly

[0082] The positive electrode, electrolyte, and negative electrode prepared in the above embodiments and comparative examples were assembled into a pouch cell. The active material in the negative electrode was graphite.

[0083] Performance testing

[0084] The self-supporting membranes prepared in the examples and comparative examples were subjected to membrane strength and tensile strength tests. Membrane strength and tensile strength: Self-supporting membranes were cut into 20mm*50mm pieces and tested using a universal tensile testing machine. The test results are shown in Table 1.

[0085] The assembled pouch cells were tested at 25°C for initial efficiency at 0.2C and capacity retention after 100 cycles at 0.5C. The test results are shown in Table 1.

[0086] Table 1

[0087]

[0088] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0089] In step S1, the sequential mixing and pre-fiberization of the positive electrode active material and binder helps to coat the surface of the positive electrode active material with the binder, thereby increasing the lubricity and reducing the hardness of the positive electrode active material. If the positive electrode active material is not mixed with the binder first, the conductive agent easily encapsulates the binder, which is not conducive to improving the dispersion uniformity of the positive electrode active material. At the same time, the binder encapsulated by the conductive agent is not easily fiberized, which is not conducive to improving the mechanical strength of the positive electrode sheet. In step S2, the first and second fiberization treatments help to increase the bonding strength between the binder and the positive electrode active material, and also help to increase the degree of fiberization of the binder, thereby helping to improve the mechanical strength of the positive electrode sheet. Therefore, the positive electrode sheet prepared by the preparation method of this application has high mechanical strength, liquid absorption, uniformity and consistency.

[0090] The above are merely embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a positive electrode sheet, characterized in that, The preparation method includes the following steps: Step S1: The positive electrode active material and the binder are sequentially subjected to a first mixing and pre-fiberization treatment to obtain a first intermediate. Step S2: The first intermediate and the conductive agent are sequentially subjected to a second mixing, a first fiberization treatment, and a second fiberization treatment to obtain a second intermediate; Step S3: After the second intermediate is calendered into a film, it is combined with the current collector to obtain the positive electrode sheet.

2. The preparation method according to claim 1, characterized in that, In step S2, the temperature of the second mixing is 5-19°C; and / or, the time of the second mixing is 4-25 min; and / or, the second mixing is carried out in the first mixer; and / or, the rotation speed of the second mixing is 250-1500 rpm. Preferably, the second mixing includes a second A mixing and a second B mixing performed sequentially; the rotation speed of the second A mixing is 1100-1500 rpm; and / or, the time of the second A mixing is 2-10 min; the rotation speed of the second B mixing is 250-400 rpm; and / or, the time of the second B mixing is 2-15 min.

3. The preparation method according to claim 1 or 2, characterized in that, In step S2, the temperature of the first fiberization treatment is 60–100°C; and / or, when the particle size of the first fiberization treatment is less than 20 μm, the first fiberization treatment is stopped; and / or, the first fiberization treatment is carried out in a first airflow shearing machine; preferably, the airflow shearing intensity of the first airflow shearing machine is 0.45–0.6 MPa; and / or, the rotation speed of the first airflow shearing machine is 2500–5000 rpm.

4. The preparation method according to any one of claims 1 to 3, characterized in that, In step S2, the temperature of the second fiberization treatment is 60-90°C; and / or, the time of the second fiberization treatment is 30-120 seconds; and / or, the second fiberization treatment is carried out in a kneading machine; preferably, the rotation speed of the kneading machine is 5-35 rpm.

5. The preparation method according to any one of claims 1 to 4, characterized in that, After the first fiberization process in step S2 is completed, the product of the first fiberization process is first subjected to heat treatment, and then the second fiberization process is performed. And / or, the temperature of the heat treatment is 100 to 200°C; and / or, the time of the heat treatment is 0.5 to 2 hours.

6. The preparation method according to any one of claims 1 to 5, characterized in that, In step S1, the temperature of the first mixing is 5-19°C; and / or, the time of the first mixing is 5-10 min; and / or, the first mixing is carried out in a second mixer, the rotation speed of the second mixer is 150-200 rpm.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The temperature of the pre-fiberization treatment is 5–19°C; and / or, the pre-fiberization treatment is stopped when the particle size of the pre-fiberized particles is less than 20 μm. And / or, the pre-fiberization treatment is carried out in a second airflow shearing machine; preferably, the airflow shearing intensity of the second airflow shearing machine is 0.4 to 0.8 MPa; and / or, the rotational speed of the second airflow shearing machine is 3000 to 5000 rpm.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The calendering temperature is 100–130°C; and / or the composite temperature is 100–130°C; and / or the composite pressure is 6–10t.

9. A positive electrode plate, characterized in that, The positive electrode sheet is prepared by the preparation method according to any one of claims 1 to 8.

10. A battery comprising a positive electrode, an electrolyte, and a negative electrode, characterized in that, The positive electrode is the positive electrode as described in claim 9.

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