Positive electrode slurry as well as preparation method and application thereof
By constructing a point-line-surface conductive network using a ternary composite conductive agent system, the problem of insufficient conductivity in lithium-ion battery cathode slurry was solved, resulting in improved performance of lithium-ion batteries with low internal resistance and high energy density.
Patent Information
- Application Number
- CN202511040041.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-28
- Publication Date
- 2025-11-28
AI Technical Summary
The conductivity and electrochemical performance of existing lithium-ion battery cathode slurries have not yet been maximized, resulting in high internal resistance and affecting energy density and cycle performance.
A ternary composite conductive agent system, including modified zero-dimensional conductive agents, two-dimensional conductive agents, and one-dimensional conductive agents, is adopted to improve conductivity and stability through the construction of a point-line-surface conductive network.
It significantly reduces the internal resistance of lithium-ion batteries, improves energy density and cycle performance, and extends battery life.
Smart Images
Figure CN121035147A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of lithium ion batteries, in particular to a positive electrode slurry and a preparation method and application thereof. BACKGROUND
[0002] Since the 21st century, non-renewable resources have been extensively exploited, which has led to resource scarcity and environmental problems. Research on new energy materials plays an important role in promoting sustainable development. At present, the main power lithium battery is mainly lithium iron phosphate battery, and the positive electrode slurry of the lithium ion battery positive electrode sheet mainly consists of active materials, conductive agents and binders. Since most of the positive electrode material active substances have poor conductivity and large internal resistance, a conductive agent is needed to form a conductive network to improve the conductivity between the electrode material active substance and the current collector. Therefore, the conductive agent is a key auxiliary material for lithium ion batteries, which plays an important role in improving the conductivity, rate performance and cycle performance of the battery. The composite conductive agent used in the positive electrode is mainly carbon nanotubes or graphene conductive materials introduced on the basis of carbon black conductive agent. Compared with single-component conductive agents, binary conductive networks can effectively improve the electrochemical performance of the battery, but it is still uncertain whether the conductivity has been maximized. Therefore, it is particularly important to develop a positive electrode slurry for application in a positive electrode sheet with lower resistance and higher conductivity. SUMMARY
[0003] Based on the technical problems existing in the background art, the present application provides a positive electrode slurry and a preparation method and application thereof.
[0004] The preparation method of the positive electrode slurry provided by the present application comprises the following steps:
[0005] S1, uniformly mixing PVDF and a solvent to obtain a PVDF glue solution;
[0006] S2, sequentially adding modified or unmodified conductive agent A, conductive agent B solution and modified or unmodified conductive agent C solution to the PVDF glue solution, and uniformly mixing to obtain a mixed slurry;
[0007] S3, adding positive electrode active material and solvent to the mixed slurry, and uniformly mixing to obtain a positive electrode slurry.
[0008] The positive electrode slurry prepared by the preparation method has excellent stability, reduces the viscosity rebound of the slurry, and is not prone to sedimentation during storage and coating.
[0009] Preferably, in S2, the conductive agent A is a zero-dimensional conductive agent, and the zero-dimensional conductive agent is selected from one or more of acetylene black and carbon black.
[0010] The zero-dimensional conductive agent improves the conductivity through point contact between particles.
[0011] Preferably, in S2, the preparation method of the modified conductive agent A comprises the following steps: soaking the conductive agent A in an acid solution for acid treatment, washing and drying to obtain the product; the acid treatment comprises one-time acid treatment and two-time acid treatment.
[0012] The modification treatment of the zero-dimensional conductive agent is beneficial to improve the dispersion performance and form a stable suspension slurry in a point-point contact mode with the active particulate matter, enhance the interaction between the active particles and improve the overall performance; on the other hand, it is beneficial to improve the surface activity of the zero-dimensional conductive agent and improve the conductivity of the electrode in cooperation with other conductive agents.
[0013] More preferably, the temperature of the acid treatment is 70-90℃, and the time of the acid treatment is 3-6h.
[0014] More preferably, the acid solution of the one-time acid treatment is selected from one or more of hydrochloric acid and sulfuric acid.
[0015] More preferably, the concentration of the acid solution of the one-time acid treatment is 1-3mol / L.
[0016] More preferably, the acid solution of the two-time acid treatment is selected from one or more of carboxylic acid, oxalic acid and citric acid.
[0017] More preferably, the concentration of the acid solution of the two-time acid treatment is 0.1-2mol / L.
[0018] The use of different acid solutions in the acid treatment process is beneficial to improve the dispersibility of the conductive agent, enhance the surface activity and improve the conductivity.
[0019] Preferably, in S2, the conductive agent B is a two-dimensional conductive agent, and the two-dimensional conductive agent is selected from one or more of graphene and MXenes.
[0020] The two-dimensional conductive agent has a unique sheet structure, and the contact between the active particles and the two-dimensional conductive agent is a typical point-surface contact mode, which not only expands the contact area between the active particles and the conductive agent, but also facilitates the construction of a conductive network and improves the energy density of the lithium ion battery.
[0021] Preferably, in S2, the conductive agent C is a one-dimensional conductive agent, and the one-dimensional conductive agent is selected from one or more of carbon fibers and carbon nanotubes.
[0022] The one-dimensional conductive agent increases the contact with the electrode material particles due to its fibrous structure, greatly improves the conductivity of the electrode, and reduces the electrode resistance. The one-dimensional conductive agent has a large aspect ratio, contacts the active material particles in a point-line manner, can form a cross-linked network structure during slurry dispersion, enhances the suspension stability of the slurry, and forms a large number of conductive contact sites between the active particles, thereby reducing the contact impedance between the active particles.
[0023] Preferably, in S2, the preparation method of the modified conductive agent C comprises the following steps: mixing the conductive agent C and the modifier solution, uniformly ultrasonic dispersing, heating treatment, centrifugal drying, and obtaining.
[0024] More preferably, the modifier solution is an ethanol solution of the modifier, and the modifier is one or more selected from 1-allyl-3-methylimidazole bromide, 1-allyl-3-methylimidazole chloride, 1-ethyl-3-methylimidazole, and 1-butyl-3-methylimidazole.
[0025] The conductive agent C is modified by using the ionic liquid modifier, which can effectively improve the conductivity of the conductive agent C, thereby reducing the use amount of the conductive agent C.
[0026] More preferably, the mass fraction of the modifier in the modifier solution is 3-5 wt%.
[0027] More preferably, the mass ratio of the conductive agent C to the modifier solution is 1: (80-100).
[0028] More preferably, the ultrasonic temperature is 20-30℃, and the ultrasonic time is 0.5-1.5h.
[0029] More preferably, the heating treatment comprises heating to 70-90℃ at a heating rate of 1-10℃ / min for 2-4h.
[0030] Preferably, in S2, the mass ratio of the modified or unmodified conductive agent A, the conductive agent B, and the modified or unmodified conductive agent C is 13: (7-9): (0.3-1).
[0031] The modified or unmodified conductive agent A, the conductive agent B, and the modified or unmodified conductive agent C synergistically form a ternary composite conductive agent. The ternary composite conductive agent added between the positive active materials can reduce the battery internal resistance, and a “point-line-surface” transport conductive network can be constructed between the active particles and the conductive agent, thereby greatly improving the conductive effect.
[0032] Preferably, in S2, the conductive agent B solution is a slurry formed by mixing the conductive agent B and a solvent.
[0033] Preferably, in S2, the mass fraction of the conductive agent B in the conductive agent B solution is 1-10 wt%.
[0034] Preferably, in S2, the modified or unmodified conductive agent C solution is a slurry formed by mixing the modified or unmodified conductive agent C solution with a solvent.
[0035] Preferably, in S2, the mass fraction of the modified or unmodified conductive agent C in the modified or unmodified conductive agent C solution is 0.1-1 wt%.
[0036] In the present application, the conductive agent B and the modified or unmodified conductive agent C are added in the form of a slurry, which can be uniformly dispersed and enhance the conductivity, while direct addition is prone to agglomeration into blocks.
[0037] Preferably, in S1, the mass ratio of PVDF to the solvent is (4-7):(92-96).
[0038] Preferably, the solvent is selected from one or more of N-methylpyrrolidone and N,N-dimethylformamide.
[0039] Preferably, in S3, the positive active material is selected from one or more of lithium iron phosphate and lithium manganese iron phosphate.
[0040] Preferably, in S3, the viscosity of the positive electrode slurry is 3000-6000 mPa·s.
[0041] Preferably, in S3, the solid content of the positive electrode slurry is 57%-63%.
[0042] The present application also provides a positive electrode slurry prepared by the above preparation method.
[0043] A positive electrode sheet, comprising: a current collector and a positive electrode material layer located on the surface of the current collector, and the positive electrode material layer is formed by coating and drying the above positive electrode slurry or the positive electrode slurry prepared by the above preparation method.
[0044] A lithium ion battery comprising the above positive electrode sheet.
[0045] The lithium ion battery provided by the present application has a lower lithium ion battery internal resistance and a higher lithium ion battery cycle performance. The lower internal resistance can effectively improve the energy density of the lithium ion battery and reduce energy loss; the high capacity retention rate can improve the stability of the battery and prolong the service life of the battery.
[0046] The present application has the following advantages:
[0047] The present application first prepares a PVDF glue solution, then a certain amount of modified or unmodified conductive agent A, conductive agent B, modified or unmodified conductive agent C is added in the PVDF glue solution in turn, a certain amount of positive active material is added after uniform stirring, the final positive electrode slurry with designed solid content is obtained after viscosity adjustment, the positive electrode slurry is coated on the current collector to obtain a positive electrode tab, the slurry properties and tab physical properties are studied, and finally a lithium ion soft package battery is prepared, which has excellent cycle performance. BRIEF DESCRIPTION OF DRAWINGS
[0048] Figure 1 The 24h slurry viscosity rebound schematic diagram of the positive electrode slurry prepared in the present application example 2 and comparative example 1.
[0049] Figure 2 The peeling strength of the positive electrode tab corresponding to the positive electrode slurry prepared in the present application example 2 and comparative example 1.
[0050] Figure 3 The EIS test result graph of the soft package battery corresponding to the positive electrode slurry prepared in the present application example 2 and comparative example 1 after formation.
[0051] Figure 4 The capacity retention rate of the soft package battery corresponding to the positive electrode slurry prepared in the present application example 2 and comparative example 1. DETAILED DESCRIPTION
[0052] The technical solutions of the present application are described in detail through specific examples.
[0053] The materials, reagents and the like used in the following examples and comparative examples can be obtained from commercial channels unless otherwise specified.
[0054] Example 1
[0055] A preparation method of a positive electrode slurry, comprising the following steps:
[0056] S1, 52 parts of PVDF and 921 parts of NMP are added in a slurry mixer, and the glue is beaten for 2h to obtain a PVDF glue solution;
[0057] S2, 13 parts of modified carbon black SP, 207 parts of 4wt% graphene NMP solution and 77 parts of 0.4wt% modified carbon nanotube NMP solution are added in the PVDF glue solution in turn, mixed for 40min to obtain a mixed slurry;
[0058] S3, 3000 parts of LiFePO4 are added in the mixed slurry, stirred in the slurry mixer for 2h, then NMP is added to adjust the slurry viscosity to 5000 mPa·s, and a positive electrode slurry is obtained.
[0059] The preparation method of the modified carbon black SP comprises the following steps: first soaking the carbon black SP in 2 mol / L hydrochloric acid in an 80℃ water bath for one-time acid treatment for 1h, washing and drying, then soaking in 1 mol / L carboxylic acid in an 80℃ water bath for two-time acid treatment for 3h, and washing and drying.
[0060] The preparation method of the modified carbon nanotube comprises the following steps: mixing 1 part of carbon nanotube and 100 parts of 4wt% 1-allyl-3-methyl imidazole bromide ethanol solution, ultrasonic dispersion at 25℃ for 1h, heating treatment at a temperature increasing rate of 3℃ / min to 80℃ for 3h, and centrifugal drying.
[0061] Example 2
[0062] The preparation method of the positive electrode slurry comprises the following steps:
[0063] S1, adding 52 parts of PVDF and 921 parts of NMP in a slurry mixer, and glueing for 2h to obtain a PVDF glue solution;
[0064] S2, sequentially adding 13 parts of the modified carbon black SP, 200 parts of 4wt% graphene NMP solution and 154 parts of 0.4wt% modified carbon nanotube NMP solution into the PVDF glue solution, mixing for 40min to obtain a mixed slurry;
[0065] S3, adding 3000 parts of LiFePO4 into the mixed slurry, stirring in the slurry mixer for 2h to mix uniformly, then adding NMP to adjust the slurry viscosity to 5000 mPa·s to obtain the positive electrode slurry.
[0066] The preparation method of the modified carbon black SP comprises the following steps: first soaking the carbon black SP in 2 mol / L hydrochloric acid in an 80℃ water bath for one-time acid treatment for 1h, washing and drying, then soaking in 1 mol / L carboxylic acid and 0.1 mol / L citric acid mixed acid in an 80℃ water bath for two-time acid treatment for 3h, and washing and drying.
[0067] The preparation method of the modified carbon nanotube comprises the following steps: mixing 1 part of carbon nanotube and 100 parts of 4wt% 1-allyl-3-methyl imidazole bromide ethanol solution, ultrasonic dispersion at 25℃ for 1h, heating treatment at a temperature increasing rate of 3℃ / min to 80℃ for 3h, and centrifugal drying.
[0068] Example 3
[0069] The preparation method of the positive electrode slurry comprises the following steps:
[0070] S1, adding 52 parts of PVDF and 921 parts of NMP in a slurry mixer, and glueing for 2h to obtain a PVDF glue solution;
[0071] S2. Add 13 parts of modified carbon black SP, 192 parts of 4wt% graphene NMP solution, and 231 parts of 0.4wt% carbon nanotube NMP solution to the PVDF adhesive in sequence, mix for 40 min, and obtain a mixed slurry.
[0072] S3. Add 3000 parts of LiFePO4 to the mixed slurry, stir in the mixing machine for 2 hours to mix evenly, and then add NMP to adjust the slurry viscosity to 5000 mPa·s to obtain the positive electrode slurry.
[0073] The method for preparing modified carbon black SP includes the following steps: first, soaking the carbon black SP in 2 mol / L hydrochloric acid in an 80°C water bath for a first acid treatment of 1 h, washing and drying, then soaking it in 1 mol / L carboxyacetic acid in an 80°C water bath for a second acid treatment of 3 h, washing and drying, and the modified carbon black SP is obtained.
[0074] The method for preparing modified carbon nanotubes includes the following steps: mixing 1 part of carbon nanotubes and 100 parts of 4wt% ethanol solution of 1-allyl-3-methylimidazole bromide, ultrasonically dispersing at 25℃ for 1 h, heating to 80℃ at a heating rate of 3℃ / min for 3 h, and centrifuging and drying to obtain the modified carbon nanotubes.
[0075] Example 4
[0076] A method for preparing a positive electrode slurry includes the following steps:
[0077] S1. Add 52 parts PVDF and 921 parts NMP to the mixing machine and apply the adhesive for 2 hours to obtain PVDF adhesive solution;
[0078] S2. Add 13 parts of modified carbon black SP, 207 parts of 4wt% NMP solution of graphene, and 77 parts of 0.4wt% NMP solution of carbon nanotubes to the PVDF adhesive in sequence, mix for 40 min to obtain a mixed slurry;
[0079] S3. Add 3000 parts of LiFePO4 to the mixed slurry, stir in the mixing machine for 2 hours to mix evenly, and then add NMP to adjust the slurry viscosity to 5000 mPa·s to obtain the positive electrode slurry.
[0080] The method for preparing modified carbon black SP includes the following steps: first, soaking the carbon black SP in 2 mol / L hydrochloric acid in an 80°C water bath for a first acid treatment of 1 h, washing and drying, then soaking it in 1 mol / L carboxyacetic acid in an 80°C water bath for a second acid treatment of 3 h, washing and drying, and the modified carbon black SP is obtained.
[0081] Example 5
[0082] A method for preparing a positive electrode slurry includes the following steps:
[0083] S1, 52 parts of PVDF and 921 parts of NMP were added into a slurry mixer, and glue was beaten for 2h to obtain a PVDF glue solution;
[0084] S2, 13 parts of carbon black SP, 207 parts of 4wt% graphene NMP solution, and 77 parts of 0.4wt% modified carbon nanotube NMP solution were sequentially added into the PVDF glue solution, mixed for 40min to obtain a mixed slurry;
[0085] S3, 3000 parts of LiFePO4 were added into the mixed slurry, stirred in the slurry mixer for 2h to mix uniformly, then NMP was added to adjust the slurry viscosity to 5000 mPa·s to obtain a positive electrode slurry.
[0086] The preparation method of the modified carbon nanotube comprises the following steps: 1 part of carbon nanotube and 100 parts of 4wt% 1-allyl-3-methylimidazole bromide ethanol solution are mixed, ultrasonic dispersion is carried out at 25℃ for 1h, heating treatment is carried out at a heating rate of 3℃ / min to 80℃ for 3h, and centrifugal drying is carried out.
[0087] Comparative Example 1
[0088] A preparation method of a positive electrode slurry comprises the following steps:
[0089] S1, 52 parts of PVDF and 921 parts of NMP were added into a slurry mixer, and glue was beaten for 2h to obtain a PVDF glue solution;
[0090] S2, 13 parts of modified carbon black SP, 215 parts of 4wt% graphene NMP solution were sequentially added into the PVDF glue solution, mixed for 40min to obtain a mixed slurry;
[0091] S3, 3000 parts of LiFePO4 were added into the mixed slurry, stirred in the slurry mixer for 2h to mix uniformly, then NMP was added to adjust the slurry viscosity to 5000 mPa·s to obtain a positive electrode slurry.
[0092] The preparation method of the modified carbon black SP comprises the following steps: the carbon black SP is first soaked in 2mol / L hydrochloric acid in a 80℃ water bath for one-time acid treatment for 1h, washed and dried, then soaked in 1mol / L carboxylic acid in a 80℃ water bath for two-time acid treatment for 3h, and washed and dried.
[0093] Comparative Example 2
[0094] A preparation method of a positive electrode slurry comprises the following steps:
[0095] S1, 52 parts of PVDF and 921 parts of NMP were added into a slurry mixer, and glue was beaten for 2h to obtain a PVDF glue solution;
[0096] S2. Add 13 parts of modified carbon black SP and 77 parts of 0.4 wt% modified carbon nanotube NMP solution to the PVDF adhesive in sequence, mix for 40 min to obtain a mixed slurry;
[0097] S3. Add 3000 parts of LiFePO4 to the mixed slurry, stir in the mixing machine for 2 hours to mix evenly, and then add NMP to adjust the slurry viscosity to 5000 mPa·s to obtain the positive electrode slurry.
[0098] The method for preparing modified carbon black SP includes the following steps: first, soaking the carbon black SP in 2 mol / L hydrochloric acid in an 80°C water bath for a first acid treatment of 1 h, washing and drying, then soaking it in 1 mol / L carboxyacetic acid in an 80°C water bath for a second acid treatment of 3 h, washing and drying, and the modified carbon black SP is obtained.
[0099] The method for preparing modified carbon nanotubes includes the following steps: mixing 1 part of carbon nanotubes and 100 parts of 4wt% ethanol solution of 1-allyl-3-methylimidazole bromide, ultrasonically dispersing at 25℃ for 1 h, heating to 80℃ at a heating rate of 3℃ / min for 3 h, and centrifuging and drying to obtain the modified carbon nanotubes.
[0100] The above-mentioned positive electrode slurry was coated onto aluminum foil and dried in an oven at 85°C to obtain the positive electrode sheet. The positive electrode sheet was then assembled with the negative electrode sheet, separator, and electrolyte to form a pouch cell.
[0101] The film resistance of the positive electrode corresponding to the above positive electrode slurry was tested at a pressure of 19.29 MPa. The test results are shown in Table 1.
[0102] Table 1
[0103] Group Resistance (Ω) Conductivity (S / mm) Resistivity (Ω·mm) Example 1 0.184 0.0038 260.33 Example 2 0.159 0.0042 236.25 Example 3 0.172 0.0041 242.85 Example 4 0.201 0.0035 285.21 Example 5 0.198 0.0036 279.45 Comparative Example 1 0.210 0.0034 295.17 Comparative Example 2 0.211 0.0033 300.56
[0104] As can be seen from the data in Table 1, the positive electrode sheet made from the positive electrode slurry prepared in this invention has lower film resistance and higher conductivity, which can effectively improve the energy density of lithium-ion batteries.
[0105] like Figure 1 As shown, Figure 1 This is a schematic diagram showing the viscosity rebound of the positive electrode slurry prepared in Example 2 and Comparative Example 1 of the present invention after 24 hours. Figure 1 It can be concluded that the viscosity rebound of the positive electrode slurry prepared by the present invention is significantly less than that of the positive electrode slurry prepared by Comparative Example 1. The positive electrode slurry prepared by the present invention is not prone to sedimentation during storage, thus maintaining the stability of the slurry. In addition, it can maintain a stable viscosity during coating, ensuring a more uniform distribution of the slurry on the electrode.
[0106] like Figure 2 As shown, Figure 2The peeling strength of the positive electrode tab corresponding to the positive electrode slurry prepared in Example 2 and Comparative Example 1 of the present application. As shown in Figure 2 It can be seen that the positive electrode tab corresponding to the positive electrode slurry prepared in Example 2 has higher peeling strength, which helps the stability and life of the battery.
[0107] As shown in Figure 3 , Figure 3 The EIS test result graph of the soft pack battery corresponding to the positive electrode slurry prepared in Example 2 and Comparative Example 1 of the present application after formation. As shown in Figure 3 It can be seen that the soft pack battery corresponding to Example 2 of the present application has lower impedance after formation.
[0108] As shown in Figure 4 , Figure 4 The capacity retention rate of the soft pack battery corresponding to the positive electrode slurry prepared in Example 2 and Comparative Example 1 of the present application. As shown in Figure 4 It can be seen that the soft pack battery corresponding to Example 2 of the present application has higher capacity retention rate.
[0109] In summary, the positive electrode slurry provided by the present application has excellent conductivity and stability, and the corresponding lithium ion battery has higher capacity retention rate, prolonging the service life of the battery.
[0110] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art within the technical scope disclosed by the present application, according to the technical scheme and the inventive concept of the present application, makes equivalent replacement or change, should be covered in the protection scope of the present application.
Claims
1. A method for preparing a positive electrode slurry, characterized in that, Includes the following steps: S1. Mix PVDF and solvent evenly to obtain PVDF adhesive solution; S2. Add the modified or unmodified conductive agent A, conductive agent B solution, and modified or unmodified conductive agent C solution to the PVDF adhesive solution in sequence, mix evenly, and obtain a mixed slurry. S3. Add the positive electrode active material and solvent to the mixed slurry, mix evenly, and obtain the positive electrode slurry; In S2, conductive agent A is a zero-dimensional conductive agent, conductive agent B is a two-dimensional conductive agent, and conductive agent C is a one-dimensional conductive agent.
2. The preparation method according to claim 1, characterized in that, In S2, the method for preparing the modified conductive agent A includes the following steps: immersing the conductive agent A in an acid solution for acid treatment, washing and drying to obtain the product; the acid treatment includes a primary acid treatment and a secondary acid treatment.
3. The preparation method according to claim 2, characterized in that, The acid solution for the primary acid treatment is selected from one or more of hydrochloric acid and sulfuric acid; the concentration of the acid solution for the primary acid treatment is 1-3 mol / L; the acid solution for the secondary acid treatment is selected from one or more of carboxyacetic acid, oxalic acid, and citric acid; the concentration of the acid solution for the secondary acid treatment is 0.1-2 mol / L.
4. The preparation method according to claim 1, characterized in that, The preparation method of the modified conductive agent C in S2 includes the following steps: mixing the conductive agent C and the modifier solution, ultrasonically dispersing them evenly, heating them, and centrifuging and drying them to obtain the final product.
5. The preparation method according to claim 4, characterized in that, The modifier solution is an ethanol solution of the modifier, and the modifier is selected from one or more of 1-allyl-3-methylimidazole bromide, 1-allyl-3-methylimidazole chloride, 1-ethyl-3-methylimidazole, and 1-butyl-3-methylimidazole; the mass fraction of the modifier in the modifier solution is 3-5 wt%; the mass ratio of the conductive agent C to the modifier solution is 1:(80-100); the heat treatment includes heating to 70-90℃ at a heating rate of 1-10℃ / min and reacting for 2-4 hours.
6. The preparation method according to claim 1, characterized in that, In S2, the zero-dimensional conductive agent is selected from one or more of acetylene black and carbon black; the one-dimensional conductive agent is selected from one or more of carbon fiber and carbon nanotube; the two-dimensional conductive agent is selected from one or more of graphene and MXenes; the mass ratio of the modified or unmodified conductive agent A, conductive agent B, and modified or unmodified conductive agent C is 13:(7-9):(0.3-1).
7. The preparation method according to claim 1, characterized in that, In S1, the mass ratio of PVDF to solvent is (4-7):(92-96).
8. The preparation method according to claim 1, characterized in that, In S3, the positive electrode active material is selected from one or more of lithium iron phosphate and lithium manganese iron phosphate; the viscosity of the positive electrode slurry is 3000-6000 mPa·s.
9. A positive electrode slurry, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.
10. A positive electrode plate, characterized in that, include: The current collector and a positive electrode material layer located on the surface of the current collector, wherein the positive electrode material layer is formed by coating and drying the positive electrode slurry as described in claim 9 or the positive electrode slurry prepared by any one of the preparation methods of claims 1-8.