Design method of negative electrode slurry kneading solid content
By calculating the specific surface area of the main material and the conductive agent, a kneading solid content prediction model was established, which solved the problem of improper solid content control in the preparation of lithium-ion battery slurry and achieved efficient slurry dispersion and improved battery performance.
Patent Information
- Application Number
- CN202511849726.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-02-13
AI Technical Summary
In the preparation of lithium-ion battery slurry, improper control of solid content during the kneading process can affect material dispersibility, conductive network formation, and coating process, leading to poor battery performance.
By calculating the specific surface area of the main material and the conductive agent, and combining the density and proportion of the adhesive, a kneading solids content prediction model is established to determine the optimal kneading solids content, ensuring that the material is fully wetted and uniformly distributed.
It significantly reduced R&D costs and time, improved process development efficiency, ensured slurry fineness <25μm, met mass production process requirements, and achieved good dispersion effect.
Smart Images
Figure CN121528356A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery manufacturing technology, and more specifically, to a design method for kneading and solidifying negative electrode slurry. Background Technology
[0002] In the preparation of lithium-ion battery slurries, the solid content during the kneading stage is a key parameter affecting slurry performance and final electrode quality. Excessive or insufficient solid content during kneading will negatively impact material dispersion, conductive network formation, coating processes, and battery performance. Therefore, achieving uniform distribution and efficient kneading of the conductive agent through reasonable solid content control, while ensuring good rheological properties, is a crucial process control point for improving electrode performance and battery consistency.
[0003] In view of this, the present invention is proposed. Summary of the Invention
[0004] The purpose of this invention is to provide a design method for kneading solids in negative electrode slurry. The kneading solids obtained by this method have better reliability, the fineness of the slurry meets the requirement of <25μm, and the dispersion effect is good.
[0005] This invention is implemented as follows: In a first aspect, the present invention provides a method for designing the solid content of a negative electrode slurry through kneading, calculated according to the following formula: Equation (1): ; Equation (2): ; In the above formula, W is the design value of kneading solid content, W0 is the theoretical empirical solid content, A is the correction coefficient, G is the solid content of the adhesive, ρ is the density of the adhesive, a is the specific surface area of the main material, b is the specific surface area of the conductive agent, x is the mass percentage of the main material in all solid raw materials for preparing the negative electrode slurry, and y is the mass percentage of the conductive agent in all solid raw materials for preparing the negative electrode slurry. When the main material is a blend of materials with different specific surface areas, then 'a' is the sum of the products of the specific surface area of each material and its mass percentage in the total main material. For example, when the main material is a blend of two materials with different specific surface areas, a = a1(specific surface area of main material 1) * L1(mass percentage of main material 1 in the total main material) + a2(specific surface area of main material 2) * L2(mass percentage of main material 2 in the total main material). When the conductive agent is a compound of materials with different specific surface areas, b is the sum of the products of the specific surface area of each material and its mass percentage in the total conductive agent. Therefore, b = b1 (specific surface area of conductive agent 1) * L3 (mass percentage of conductive agent 1 in the total conductive agent) + b2 (specific surface area of conductive agent 2) * L4 (mass percentage of conductive agent 2 in the total conductive agent). The value of A was obtained experimentally. The experimental method was as follows: multiple groups of known materials with suitable actual kneading solid content W were used. S The slurry was calculated according to formula (1) to obtain multiple sets of W0 values, and the multiple sets of W values were then used to calculate the W0 values. S The slope of the function is A, which is a linear function that is numerically fitted to W0.
[0006] In an optional embodiment, the main material is graphite, and the specific surface area of the main material is 1.37~1.45 m². 2 / g.
[0007] In an optional embodiment, the conductive agent is selected from at least one of SP and ECP. In an optional embodiment, the specific surface area of the conductive agent is 60~110 m². 2 / g.
[0008] In an optional embodiment, the main material accounts for ≥90% of the mass of the kneaded slurry, and the conductive agent accounts for 1.7~2.5% of the mass of the kneaded slurry.
[0009] In an optional embodiment, the solid content of the adhesive is 1.5-2%.
[0010] In an optional implementation, multiple sets of known materials with a suitable actual kneading solids content W S In the slurry, the different components have different solid content of adhesive, different specific surface area of main material, different proportion of main material, different specific surface area of conductive agent, or different proportion of conductive agent.
[0011] In an optional implementation, A is 0.941.
[0012] The present invention has the following beneficial effects: The method provided by this invention calculates the volume of adhesive solution required for complete wetting of the surface of the main material (e.g., graphite) and the conductive agent based on their specific surface areas. This determines the minimum amount of adhesive solution required to achieve adequate wetting, and subsequently establishes a solid content prediction model for the kneading stage based on the material's specific surface area. This model can calculate the optimal kneading solid content by inputting parameters such as the specific surface area of different materials, formulation ratios, and the solid content and density of the adhesive solution.
[0013] The advantage of the design method provided by this invention is that it eliminates the need for repeated small-scale experiments to verify the rationality of the kneading solids content for each new formulation or material combination, significantly reducing manpower, time, and material costs in the R&D process and improving process development efficiency. When the kneading solids content determined by the design method provided by this invention is used to knead the negative electrode slurry, the fineness of the slurry obtained by scraper fineness meter testing meets the requirement of <25μm, indicating good dispersion effect and meeting the requirements of mass production processes. Attached Figure Description
[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0015] Figure 1 In Example 1, multiple sets of W S The function graph obtained by fitting the W0 data; Figure 2 This is a visual image of the kneaded slurry in Example 1 after a coating has been formed on a scraper fineness gauge; Figure 3 In Example 2, multiple sets of W S The function graph obtained by fitting the W0 data; Figure 4 This is a visual image of the kneaded slurry in Example 2 after a coating has been formed on a scraper fineness gauge; Figure 5 In Example 3, multiple sets of W S The function graph obtained by fitting the W0 data; Figure 6 This is a visual image of the kneaded slurry in Example 3 after a coating has been formed on a scraper fineness gauge. Detailed Implementation
[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0017] The features and performance of the present invention will be further described in detail below with reference to embodiments.
[0018] The present invention provides a method for designing the solids content of a negative electrode slurry through kneading, which is calculated according to the following formula: Equation (1): ; Equation (2): ; In the above formula, W is the kneading solid content, W0 is the theoretical empirical solid content, A is the correction coefficient, G is the solid content of the adhesive, ρ is the density of the adhesive, a is the specific surface area of the main material, b is the specific surface area of the conductive agent, x is the mass percentage of the main material in all solid raw materials for preparing the negative electrode slurry, and y is the mass percentage of the conductive agent in all solid raw materials for preparing the negative electrode slurry. When the main material is a blend of materials with different specific surface areas, then 'a' is the sum of the products of the specific surface area of each material and its mass percentage in the total main material. When the conductive agent is a blend of materials with different specific surface areas, then b is the sum of the products of the specific surface area of each material and its mass percentage in the total conductive agent.
[0019] When the conductive agent is a blend of materials with different specific surface areas, then b is the sum of the products of the specific surface area of each material and its mass percentage in the total conductive agent. The value of A is obtained experimentally. The experimental method involves: combining multiple groups of known materials with suitable actual kneading solid content W... S The slurry was calculated according to formula (1) to obtain multiple sets of W0 values, and the multiple sets of W values were then used to calculate the W0 values. S The slope of the function is A, which is a linear function that is numerically fitted to W0.
[0020] x*(62.75*a-53.95) represents the volume of adhesive solution required for wetting the surface of the main material, and y*(2.9691*b-65.16) represents the volume of adhesive solution required for wetting the surface of the conductive agent. These two formulas are empirical formulas. In the initial kneading stage, the negative electrode graphite, conductive agent, and a portion of the CMC adhesive solution are added to a stirring device for premixing. The method provided by this invention calculates the volume of adhesive solution required for complete wetting of the surface of the main material (e.g., graphite) and the conductive agent based on their specific surface areas. Based on this, the minimum amount of adhesive solution required to achieve sufficient wetting is determined, and a solid content prediction model for the kneading stage based on the material's specific surface area is established. This model can calculate the optimal kneading solid content by inputting parameters such as the specific surface area of different materials, the formulation ratio, and the solid content and density of the adhesive solution.
[0021] The advantage of the design method provided by this invention is that it eliminates the need for repeated small-scale experiments to verify the rationality of the kneading solids content for each new formulation or material combination, significantly reducing manpower, time, and material costs in the R&D process and improving process development efficiency. When the kneading solids content determined by the design method provided by this invention is used to knead the negative electrode slurry, the fineness of the obtained slurry meets the requirement of <25μm, indicating good dispersion and compliance with mass production process requirements.
[0022] Optionally, the main material is graphite.
[0023] Alternatively, the specific surface area of graphite is typically between 1.37 and 1.45 m². 2 / g (e.g., 1.37 m 2 / g, 1.40 m 2 / g or 1.45m 2 / g, or any value between the two mentioned above) within the range.
[0024] Optionally, the conductive agent is selected from at least one of SP (Super-P) and ECP (Electroconductive Polymer). Optionally, the specific surface area of the conductive agent is typically 60~110 m². 2 / g (e.g., 60m) 2 / g、65m 2 / g、70m 2 / g、80m 2 / g、90m 2 / g or 110m 2 / g, or any value between the two mentioned above) within the range.
[0025] Optionally, during the design process, the adhesive solution selected is a CMC adhesive solution with a solid content of 1.5% to 2% (e.g., 1.5%, 1.8%, or 2.0%, or any value between the two mentioned above).
[0026] Optionally, during the design process, the main material accounts for ≥90% of the mass of the kneading slurry, and the conductive agent accounts for 1.7~2.5% of the mass of the kneading slurry (e.g., 1.7%, 2% or 2.5%, or any value between the two mentioned above).
[0027] Optionally, multiple groups of known materials with suitable actual kneading solids content W S In the slurry, the different components have different solid content of adhesive, different specific surface area of main material, different proportion of main material, different specific surface area of conductive agent, or different proportion of conductive agent.
[0028] Using multiple sets of known, suitable actual kneading solids slurries with different variables as experimental subjects, the calculated A value has high accuracy, resulting in a smaller error between the calculated designed kneading solids content and the actual kneading solids content, thereby improving the reliability of the method provided by this invention.
[0029] It should be noted that the more slurry groups with suitable actual kneading solids content known, the more accurate the A value will be. When substituted into the formula, the value obtained by designing the kneading solids content will be closer to the true optimal kneading solids content value.
[0030] Optionally, A is 0.941. The value of A is determined by five groups with suitable actual kneading solids content W. S The values were calculated using different slurries. It should be noted that the A value may vary slightly depending on the slurry used, but the difference is usually not significant, theoretically around 0.941.
[0031] Example 1 Provide multiple sets of known suitable practical kneading solids content W S The actual kneading solids content and the theoretical empirical solids content of the slurry were statistically analyzed. Specific data are shown in Table 1.
[0032] Table 1:
[0033] Note: The deviation in Table 1 is calculated as Deviation = W (calculated value) - Ws (actual value); Group 1 uses graphite as the main material, SP as the conductive agent, and a mixture of CMC and water as the adhesive. Group 2 differs from Group 1 only in that the water content in the adhesive is lower, resulting in a higher solid content. Group 3 differs from Group 1 only in that the main material, graphite, has a larger specific surface area. Group 4 differs from Group 1 only in that the conductive agent is SP, which has a smaller specific surface area. Group 5 differs from Group 1 only in the different proportions of the main material and the conductive agent. During the kneading process, the homogenization operation parameters are as follows: the adhesive and conductive agent are introduced into a 100L mixing tank, first dispersed at a speed of 2000±50rpm, and then rotated at 20±2rpm for 20min. Then the main material graphite is poured in, the circulating water is turned on (temperature 6-13℃), and the mixture is rotated at a speed of 10±2rpm for 10min, then rotated at 20±2rpm for 60min. After that, the material is scraped, and the mixture is dispersed at a speed of 1300±50rpm, and then rotated at 20±2rpm for 45min.
[0034] The sum of the main material and the conductive agent is less than 100% because after the slurry is initially kneaded to obtain the kneaded slurry, the remaining solids and water will be added during the process of preparing the final negative electrode slurry to achieve the final target solid content. The steps after obtaining the kneaded solid content are not within the scope of this invention, so they will not be elaborated on.
[0035] Based on the W values of multiple known slurries with suitable actual kneading solids content in Table 1 S Fit a linear function to the W0 value, such as Figure 1 As shown, the linear formula y=0.941x is obtained, and the value of A is 0.941. Based on the value of A being 0.941, the kneading solids of each known slurry group with suitable actual kneading solids are calculated using equation (2), as shown in Table 1. According to the W (calculated value) data and the actual W S The calculated deviation values are shown in Table 1. It can be seen that the absolute values of the deviation values are all less than 0.15%, indicating that the deviation is small and that the design method provided by this invention has good reliability.
[0036] The experimental group was provided, and the parameters are shown in Table 1. With an A value of 0.941, the kneaded solids content was calculated to be 67.68%. The fineness of the kneaded slurry prepared according to this kneaded solids content is shown in Table 1, and is less than 25 μm, indicating good dispersion and meeting the process requirements. The fineness of the slurry adhered to the scraper fineness gauge is as shown in Table 1. Figure 2 As shown, the coating has good uniformity.
[0037] Comparative Example 1 Homogenize the mixture according to a solid content of 70%, using the same operating parameters as in Example 1.
[0038] The test fineness was 70 μm, and its uniformity was worse than that of the experimental group in Example 1. This shows that the kneaded solid content homogenate designed according to the design method provided by the present invention has a better effect. If the solid content is significantly higher than the calculated value, the homogenization effect will be poor.
[0039] Comparative Example 2 Homogenize the mixture according to a solid content of 63%, using the same operating parameters as in Example 1.
[0040] The test fineness was 44μm, and its uniformity was worse than that of the experimental group in Example 1. This shows that the kneaded solid content homogenate designed according to the design method provided by the present invention has a better effect. If the solid content is significantly lower than the calculated value, the homogenization effect will be poor.
[0041] Example 2 This embodiment is basically the same as Embodiment 1. For any parts not mentioned, please refer to Embodiment 1.
[0042] Provide multiple sets of known suitable practical kneading solids content W S The actual kneading solids content and the theoretical empirical solids content of the slurry were statistically analyzed. Specific data are shown in Table 2.
[0043] Table 2:
[0044] Based on the W values of multiple known slurries with suitable actual kneading solids content in Table 1 S Fit a linear function to the W0 value, such as Figure 3 As shown, the linear formula y=0.9412x is obtained, and the value of A is 0.941. Based on the value of A being 0.941, the kneading solids of each known slurry group with suitable actual kneading solids are calculated using equation (2), as shown in Table 2. According to the W (calculated value) data and the actual W S The calculated deviation values are shown in Table 2. It can be seen that the absolute values of the deviation values are all less than 0.15%, indicating that the deviation is small and that the design method provided by this invention has good reliability.
[0045] The experimental group was provided, and the parameters are shown in Table 2. With an A value of 0.941, the kneaded solids content was calculated to be 67.91%. The fineness of the kneaded slurry prepared according to this kneaded solids content is shown in Table 2, and is less than 25 μm, indicating good dispersion and meeting the process requirements. The fineness of the slurry adhering to the scraper fineness gauge is as shown in Table 2. Figure 4 As shown (fineness value = scale value corresponding to the position where "dense particle stripes or rough spots just appear" in the slurry groove), it can be seen that the coating uniformity is good.
[0046] Comparative Example 3 Homogenize the mixture according to a solid content of 70%, using the same operating parameters as in Example 1.
[0047] The test fineness was 51 μm, and its uniformity was worse than that of the experimental group in Example 2. This shows that the kneaded solid content homogenate designed according to the design method provided by the present invention has a better effect. If the solid content is significantly higher than the calculated value, the homogenization effect will be poor.
[0048] Comparative Example 4 Homogenize the mixture according to a solid content of 63%, using the same operating parameters as in Example 1.
[0049] The test fineness was 70 μm, and its uniformity was worse than that of the experimental group in Example 2. This shows that the kneaded solid content homogenate designed according to the design method provided by the present invention has a better effect. If the solid content is significantly lower than the calculated value, the homogenization effect will be poor.
[0050] Example 3 This embodiment is basically the same as Embodiment 1. For any parts not mentioned, please refer to Embodiment 1.
[0051] Provide multiple sets of known suitable practical kneading solids content W S The actual kneading solids content and the theoretical empirical solids content of the slurry were statistically analyzed. Specific data are shown in Table 3.
[0052] Table 3:
[0053] Based on the W values of multiple known slurries with suitable actual kneading solids content in Table 3... S Fit a linear function to the W0 value, such as Figure 5 As shown, the linear formula y = 0.9413x is obtained, and the value of A is 0.941. Based on the value of A of 0.941, the kneading solids content of each known slurry group with suitable actual kneading solids content is calculated using equation (2), as shown in Table 3. Based on the W (calculated value) data and the actual W... S The calculated deviation values are shown in Table 3. It can be seen that the absolute values of the deviation values are all less than 0.15%, which is small, proving that the design method provided by this invention has good reliability.
[0054] The experimental group was provided, and the parameters are shown in Table 3. With an A value of 0.941, the kneaded solids content was calculated to be 0.941%. The fineness of the kneaded slurry prepared according to this kneaded solids content is shown in Table 3, which is less than 25 μm, indicating good dispersion and meeting the process requirements. The fineness of the slurry adhering to the scraper fineness gauge is as shown in Table 3. Figure 6 As shown, the coating has good uniformity.
[0055] Comparative Example 5 Homogenize the mixture according to a solid content of 70%, using the same operating parameters as in Example 1.
[0056] The test fineness was 60 μm, and its uniformity was worse than that of the experimental group in Example 3. This shows that the kneaded solid content homogenate designed according to the design method provided by the present invention has a better effect. If the solid content is significantly higher than the calculated value, the homogenization effect will be poor.
[0057] Comparative Example 6 Homogenize the mixture according to a solid content of 63%, using the same operating parameters as in Example 1.
[0058] The test fineness was 44 μm, and its uniformity was worse than that of the experimental group in Example 3. This shows that the kneaded solid content homogenate designed according to the design method provided by the present invention has a better effect. If the solid content is significantly lower than the calculated value, the homogenization effect will be poor.
[0059] In summary, the design method provided by the embodiments of the present invention eliminates the need for repeated small-scale experiments to verify the rationality of the kneading solids content for each new formulation or material combination, significantly reducing manpower, time, and material costs in the R&D process and improving process development efficiency. When the kneading solids content determined according to the design method provided by the present invention is used to knead the negative electrode slurry, the fineness of the obtained slurry meets the requirement of <25μm, indicating good dispersion and meeting the requirements of mass production processes; the design method provided by the present invention has excellent reliability.
[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for designing the solid content of a negative electrode slurry through kneading, characterized in that, include: Calculate using the following formula: Equation (1): ; Equation (2): ; In the above formula, W is the design value of kneading solid content, W0 is the theoretical empirical solid content, A is the correction coefficient, G is the solid content of the adhesive, ρ is the density of the adhesive, a is the specific surface area of the main material, b is the specific surface area of the conductive agent, x is the mass percentage of the main material in all solid raw materials for preparing the negative electrode slurry, and y is the mass percentage of the conductive agent in all solid raw materials for preparing the negative electrode slurry. When the main material is a blend of materials with different specific surface areas, then 'a' is the sum of the products of the specific surface area of each material and its mass percentage in the total main material. When the conductive agent is a compound of materials with different specific surface areas, then b is the sum of the products of the specific surface area of each material and its mass percentage in the total conductive agent; The value of A was obtained experimentally. The experimental method was as follows: multiple groups of known materials with suitable actual kneading solid content W were used. S The slurry was calculated according to formula (1) to obtain multiple sets of W0 values, and the multiple sets of W values were then used to calculate the W0 values. S The slope of the function is A, which is a linear function that is numerically fitted to W0.
2. The design method according to claim 1, characterized in that, The main material is graphite.
3. The design method according to claim 2, characterized in that, The specific surface area of the main material is 1.37~1.45 m². 2 / g.
4. The design method according to claim 1, characterized in that, The conductive agent is selected from at least one of SP and ECP.
5. The design method according to claim 4, characterized in that, The specific surface area of the conductive agent is 60~110 m². 2 / g.
6. The design method according to claim 1, characterized in that, The main material accounts for ≥90% of the mass of the kneaded slurry, and the conductive agent accounts for 1.7~2.5% of the mass of the kneaded slurry.
7. The design method according to claim 1, characterized in that, The solid content of the adhesive solution is 1.5-2%.
8. The design method according to claim 1, characterized in that, Multiple groups of known materials have a suitable actual kneading solid content W S In the slurry, the different components have different solid content of adhesive, different specific surface area of main material, different proportion of main material, different specific surface area of conductive agent, or different proportion of conductive agent.
9. The design method according to claim 8, characterized in that, A is 0.941.