Method for evaluating fluidity and processability of slurry

Abstract

The invention discloses a method for evaluating fluidity and processability of slurry, which comprises the following steps: in a coating process, acquiring a total surface density data sequence of longitudinal coating and a total surface density data sequence of transverse coating in real time; setting longitudinal and transverse surface density target values; calculating the fluctuation value of the longitudinal surface density per minute relative to the target value; calculating a fluctuation value of the transverse surface density per minute relative to a target value; comparing the longitudinal surface density fluctuation value with a preset longitudinal fluctuation threshold value; comparing the transverse surface density fluctuation value with a preset transverse fluctuation threshold value; if the longitudinal surface density fluctuation value does not exceed the preset longitudinal fluctuation threshold value, judging that the fluidity of the slurry is qualified; and if the transverse surface density fluctuation value does not exceed the preset transverse fluctuation threshold value, determining that the processing performance of the slurry is qualified. According to the invention, real-time quantitative evaluation of the fluidity and processability of the slurry in the coating process is realized, real-time data support is provided for process adjustment, and the accuracy and efficiency of quality control are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery manufacturing, and in particular to a method for evaluating slurry fluidity and processing performance. Background Art

[0002] In recent years, the lithium-ion battery market has expanded rapidly with the rapid development of new energy vehicles. This is primarily due to the increasing demand for new energy vehicles, which has driven the need for high-performance batteries. During battery manufacturing, the processability of slurry is crucial to ensuring battery consistency and safety. However, existing methods for evaluating slurry properties, such as viscosity, solids content, fineness, sedimentation rate, and rheological properties, are mostly conducted in non-real-world application scenarios. While these methods can provide some key slurry properties, they struggle to fully assess its flowability and processability during actual coating processes.

[0003] During the coating process, the slurry is subjected to high shear forces, causing changes in its viscosity, which in turn affects the coating effect. Existing evaluation methods often cannot accurately reflect the stability and processing performance of the slurry under such actual use conditions. Therefore, a method that can truly simulate the slurry under actual manufacturing conditions is needed to ensure the consistency and reliability of battery performance. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art. To achieve the above purpose, a method for evaluating slurry fluidity and processing performance is adopted to solve the problems raised in the above background technology.

[0005] A method for evaluating slurry fluidity and processing performance comprises the following steps:

[0006] S1. During the coating process, real-time data sequences of the total surface density of the longitudinal coating per minute and the total surface density data sequences of multiple transverse detection points of the transverse coating per minute are collected; and at the same time, target values ​​of the longitudinal and transverse surface densities are set;

[0007] S2. Based on the collected longitudinal total area density data and its target value, calculate the fluctuation value of the longitudinal area density relative to the target value per minute; based on the collected transverse total area density data and its target value, calculate the fluctuation value of the transverse area density relative to the target value per minute;

[0008] S3, comparing the obtained longitudinal areal density fluctuation value per minute with a preset longitudinal fluctuation threshold; and at the same time, comparing the obtained transverse areal density fluctuation value per minute with a preset transverse fluctuation threshold;

[0009] S4. If the longitudinal density fluctuation value does not exceed the preset longitudinal fluctuation threshold, the slurry fluidity is determined to be qualified; if the transverse density fluctuation value does not exceed the preset transverse fluctuation threshold, the slurry processing performance is determined to be qualified.

[0010] As a further solution of the present invention, the longitudinal fluctuation threshold is 0.5%. When the longitudinal areal density fluctuation value does not exceed 0.5%, the slurry fluidity is determined to meet the standard. This establishes a quantitative benchmark for slurry fluidity compliance and simplifies the production line determination process.

[0011] As a further solution of the present invention, the lateral fluctuation threshold is 0.5%. When the lateral surface density fluctuation value does not exceed 0.5%, the slurry processing performance is determined to meet the standard. This establishes a quantitative benchmark for slurry processing performance compliance and reduces manual evaluation errors.

[0012] As a further solution of the present invention: the longitudinal fluctuation threshold is 0.2%; when the longitudinal surface density fluctuation value does not exceed 0.2%, the slurry fluidity is judged to be excellent, thereby improving the slurry fluidity control accuracy and optimizing the coating uniformity.

[0013] As a further solution of the present invention, the longitudinal fluctuation threshold is 0.1%. When the longitudinal surface density fluctuation value does not exceed 0.1%, the slurry fluidity is judged to be excellent. This achieves high-stability slurry flow control and reduces the risk of coating defects.

[0014] As a further solution of the present invention, the plurality of transverse detection points in S1 is 12, and the transverse total surface density data sequence is obtained by summing the surface density data of the 12 detection points. Multi-point detection improves the representativeness of the transverse surface density data and enhances the reliability of the determination.

[0015] As a further solution of the present invention, the lateral fluctuation threshold is 0.2%. When the lateral surface density fluctuation value does not exceed 0.2%, the slurry processing performance is judged to be excellent. This improves the control accuracy of the lateral distribution of the slurry and ensures the consistency of the coating width.

[0016] As a further solution of the present invention, the lateral fluctuation threshold is 0.1%. When the lateral surface density fluctuation value does not exceed 0.1%, the slurry processing performance is judged to be excellent. This achieves ultra-precision coating process control and meets the process requirements of high-end products.

[0017] As a further solution of the present invention: adding a comprehensive judgment condition in S4;

[0018] When the vertical density fluctuation value does not exceed 0.5% and the horizontal density fluctuation value does not exceed 0.5%, the overall quality of the coating process is judged to be qualified. Build a multi-dimensional quality assessment system to comprehensively monitor the stability of the coating process.

[0019] As a further solution of the present invention: the conditions for judging the comprehensive quality as excellent are: the longitudinal surface density fluctuation value does not exceed 0.2% and the transverse surface density fluctuation value does not exceed 0.2%. Establishing lean coating process standards to promote product quality upgrades.

[0020] Compared with the prior art, the present invention has the following technical effects:

[0021] The above-mentioned technical solution is adopted to collect the longitudinal total surface density sequence and transverse total surface density sequence (including multiple detection points) every minute during the coating process in real time, and set the longitudinal and transverse surface density target values; based on the collected data and the target values, the fluctuation value of the longitudinal / transverse surface density relative to the target is calculated respectively per minute; the fluctuation value is compared with the preset threshold value: if the longitudinal fluctuation value is ≤0.5%, the slurry fluidity is judged to be qualified; if the transverse fluctuation value is ≤0.5%, the slurry processing performance is judged to be qualified. The core is to establish a closed-loop monitoring process of dynamic data collection, fluctuation quantification, threshold judgment, and performance correlation. Real-time quantitative evaluation of slurry fluidity and processing performance during the coating process is realized, providing immediate data support for process adjustment, and significantly improving the accuracy and efficiency of quality control. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings:

[0023] Figure 1 This is a schematic diagram of the steps of the evaluation method disclosed in the embodiment of the present application. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Example 1: Please refer to Figure 1 In an embodiment of the present invention, a method for evaluating slurry fluidity and processing performance includes the following steps:

[0026] S1. During the coating process, real-time data sequences of the total surface density of the longitudinal coating per minute and the total surface density data sequences of multiple transverse detection points of the transverse coating per minute are collected; and at the same time, target values ​​of the longitudinal and transverse surface densities are set;

[0027] Specifically, the total area density data sequence of longitudinal coating is: Z(t)1, Z(t)2, Z(t)3, ..., Z(t)n;

[0028] The total area density data sequence of multiple transverse detection points of transverse coating is: H(t)1, H(t)2, H(t)3, ..., H(t)n;

[0029] The target value of vertical surface density is: Z; the target value of horizontal surface density is: H;

[0030] S2. Based on the collected longitudinal total area density data and its target value, calculate the fluctuation value of the longitudinal area density relative to the target value per minute; based on the collected transverse total area density data and its target value, calculate the fluctuation value of the transverse area density relative to the target value per minute;

[0031] Specifically, the fluctuation value ΔZ(t) of the longitudinal areal density relative to the target value per minute and the fluctuation value ΔH(t) of the transverse areal density relative to the target value per minute are calculated based on the data in step S1;

[0032] S3, comparing the obtained longitudinal areal density fluctuation value per minute with a preset longitudinal fluctuation threshold; and at the same time, comparing the obtained transverse areal density fluctuation value per minute with a preset transverse fluctuation threshold;

[0033] Specifically, the relationship between the total area density data and time H(t), Z(t) is compared with the preset total area density data fluctuation value range ΔH(t), ΔZ(t). If it exceeds the total area density data fluctuation value range ΔH(t), ΔZ(t), it means that the coating transverse and longitudinal capabilities have changed;

[0034] S4. If the longitudinal density fluctuation value does not exceed the preset longitudinal fluctuation threshold, the slurry fluidity is determined to be qualified; if the transverse density fluctuation value does not exceed the preset transverse fluctuation threshold, the slurry processing performance is determined to be qualified.

[0035] In this embodiment, the longitudinal fluctuation threshold is 0.5%; when the longitudinal surface density fluctuation value does not exceed 0.5%, it is determined that the slurry fluidity meets the standard.

[0036] In this embodiment, the lateral fluctuation threshold is 0.5%; when the lateral surface density fluctuation value does not exceed 0.5%, it is determined that the slurry processing performance meets the standard.

[0037] In this embodiment, the longitudinal fluctuation threshold is 0.2%. When the longitudinal surface density fluctuation value does not exceed 0.2%, the slurry fluidity is judged to be excellent. This improves the slurry fluidity control accuracy and optimizes the coating uniformity.

[0038] In this embodiment, the longitudinal fluctuation threshold is 0.1%. When the longitudinal surface density fluctuation value does not exceed 0.1%, the slurry fluidity is judged to be excellent. This achieves highly stable slurry flow control and reduces the risk of coating defects.

[0039] In the specific implementation steps, during the coating process, the longitudinal surface density fluctuation ΔZ(t)=(Z(t)-Z) / Z is analyzed, and the longitudinal coating ΔZ(t)≤0.5%; among them, ΔZ(t)=0.2% or ΔZ(t)=0.1% is preferred, indicating that the slurry has good fluidity;

[0040] In this embodiment, the plurality of transverse detection points in S1 is 12, and the transverse total surface density data sequence is obtained by summing the surface density data of the 12 detection points. Multi-point detection improves the representativeness of the transverse surface density data and enhances the reliability of the determination.

[0041] In this embodiment, the lateral fluctuation threshold is 0.2%. When the lateral surface density fluctuation value does not exceed 0.2%, the slurry processing performance is judged to be excellent. This improves the lateral distribution control accuracy of the slurry and ensures the consistency of the coating width.

[0042] In this embodiment, the lateral fluctuation threshold is 0.1%. When the lateral surface density fluctuation value does not exceed 0.1%, the slurry processing performance is judged to be excellent. This achieves ultra-precision coating process control and meets the process requirements of high-end products.

[0043] In the specific implementation steps, during the coating process, the longitudinal surface density fluctuation ΔH(t)=(H(t)-H) / H is analyzed, and the longitudinal coating ΔH(t)≤0.5%; among them, ΔH(t)=0.2% or ΔH(t)=0.1% is preferred, indicating that the slurry has good processability;

[0044] In this embodiment, a comprehensive judgment condition is added in S4;

[0045] When the vertical density fluctuation value does not exceed 0.5% and the horizontal density fluctuation value does not exceed 0.5%, the overall quality of the coating process is judged to be qualified. Build a multi-dimensional quality assessment system to comprehensively monitor the stability of the coating process.

[0046] In this embodiment, the conditions for judging the comprehensive quality as excellent are: the longitudinal surface density fluctuation value does not exceed 0.2% and the transverse surface density fluctuation value does not exceed 0.2%. Establish lean coating process standards to promote product quality upgrades.

[0047] Example 2:

[0048] The slurry was mixed with lithium iron phosphate, superconducting carbon black, graphene (5% purity), and PVDF in a ratio of 96.8%: 0.7%: 0.5%: 2% by weight using a main screw. The side feed solid content was 72%, and the slurry solid content was 62%. The dispersion time was 2 hours, the orbital speed was 20 rpm, and the rotation speed was 1300 rpm. The viscosity, surface density standard deviation, and capacity standard deviation of the slurry were calculated.

[0049] During the coating process, the longitudinal coating surface density data is collected every minute, and the transverse and longitudinal surface density data of the A process batch are collected after the coating is started. The fluidity and processing performance of the slurry are evaluated by the fluctuation of the transverse and longitudinal surface density.

[0050] ① Disperse the slurry for 2 hours - start coating for 0-10 minutes (time period 1-10) The surface density fluctuation is shown in the table below:

[0051]

[0052] Result analysis: The fluctuation of the positive electrode's longitudinal surface density per minute is greater than 0.5%, indicating that the longitudinal coating ability is poor and the slurry fluidity is poor; the fluctuation of the positive electrode's transverse surface density is greater than 0.5%, indicating that the transverse coating ability needs to be improved and the slurry processing performance is poor;

[0053] ② Disperse the slurry for 2 hours - start coating 2:00-2:10 (time period 1-10) The surface density fluctuation is shown in the table below:

[0054]

[0055] Result analysis: The positive electrode longitudinal surface density fluctuated by more than 0.5% per hour, indicating that the longitudinal coating ability was poor and the slurry fluidity was poor; the positive electrode transverse surface density fluctuated by more than 0.5%, indicating that the transverse coating ability needs to be improved and the slurry processing performance is poor;

[0056] Example 3: Slurry mixing: lithium iron phosphate: superconducting carbon black: graphene (purity 5%): PVDF ingredients were mixed in a ratio of 96.8%: 0.7%: 0.5%: 2% using a main screw, with a side feed solid content of 72% and a slurry solid content of 62%. The dispersion time was 3 hours, the revolution was 20 rpm, and the rotation was 1300 rpm. The viscosity, surface density standard deviation, and capacity standard deviation of the slurry were calculated. During the coating process, the longitudinal coating surface density data was collected every minute, and the transverse and longitudinal surface density data of the B process batch were collected. The fluidity and slurry processing performance of the slurry were evaluated by the transverse and longitudinal surface density fluctuations.

[0057] ① Disperse the slurry for 3 hours - start coating for 0-12 minutes (time period 1-10). The surface density fluctuation is shown in the table below:

[0058]

[0059] Result analysis: The vertical surface density fluctuation of the positive electrode is less than 0.2% per minute, indicating that the vertical coating ability is good and the slurry fluidity is good; the horizontal surface density fluctuation of the positive electrode is mostly less than 0.5%, indicating that the horizontal coating ability is good and the slurry processability is good;

[0060] ② Disperse the slurry for 3 hours - start coating 2:00-2:10 (time period 1-10) The surface density fluctuation is shown in the following table:

[0061]

[0062] Result analysis: The vertical surface density of the positive electrode fluctuated ≤0.2% per hour, indicating good vertical coating ability and good slurry fluidity; the horizontal surface density of the positive electrode fluctuated ≤0.5% for most of the time, indicating good horizontal coating ability and good slurry processing performance;

[0063] The capacity standard deviation results of Example 2 and Example 3 are as follows:

[0064] Case Example 2 Example 3 Coating viscosity 4937 4079 Standard deviation of surface density 1.732 1.032 Capacity standard deviation 634.0 307.3

[0065] Result analysis: As the dispersion time increases, the slurry viscosity decreases, the fluidity and stability of the slurry improve, and the standard deviation of the surface density and capacity decreases. Therefore, the fluidity and processing performance of the slurry can be judged by the fluctuations of the horizontal and vertical surface density during the production process.

[0066] Beneficial effects:

[0067] The fluidity and processing performance of the slurry are evaluated by real-time monitoring of the density changes in the horizontal and vertical directions every minute during the coating process;

[0068] ① Accurate and real-time evaluation of the performance of slurry in actual application;

[0069] ② According to the fluctuation of the horizontal and vertical density, the fluidity and consistency of the slurry under different process conditions can be judged, and the processing performance of the slurry can be evaluated at the same time;

[0070] ③ Continuously monitor the production process, which plays a good monitoring role in the lithium-ion battery manufacturing process and has broad application prospects.

[0071] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. It is intended that all variations within the meaning and range of equivalents of the claims be embraced herein, and any reference signs in the claims should not be construed as limiting the claims to which they relate.

[0072] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for evaluating slurry fluidity and processing performance, characterized in that: The following steps are involved: S1. During the coating process, real-time data sequences of the total surface density of the longitudinal coating per minute and the total surface density data sequences of multiple transverse detection points of the transverse coating per minute are collected; and at the same time, target values ​​of the longitudinal and transverse surface densities are set; S2. Based on the collected longitudinal total area density data and its target value, calculate the fluctuation value of the longitudinal area density relative to the target value per minute; based on the collected transverse total area density data and its target value, calculate the fluctuation value of the transverse area density relative to the target value per minute; S3, comparing the obtained longitudinal areal density fluctuation value per minute with a preset longitudinal fluctuation threshold; and at the same time, comparing the obtained transverse areal density fluctuation value per minute with a preset transverse fluctuation threshold; S4. If the longitudinal density fluctuation value does not exceed the preset longitudinal fluctuation threshold, the slurry fluidity is determined to be qualified; if the transverse density fluctuation value does not exceed the preset transverse fluctuation threshold, the slurry processing performance is determined to be qualified.

2. The method for evaluating slurry fluidity and processing performance according to claim 1, characterized in that: The longitudinal fluctuation threshold is 0.5%; when the longitudinal surface density fluctuation value does not exceed 0.5%, it is determined that the slurry fluidity meets the standard.

3. The method for evaluating slurry fluidity and processing performance according to claim 1, characterized in that: The lateral fluctuation threshold is 0.5%; when the lateral surface density fluctuation value does not exceed 0.5%, it is determined that the slurry processing performance meets the standard.

4. The method for evaluating slurry fluidity and processing performance according to claim 2, wherein: The longitudinal fluctuation threshold is 0.2%; when the longitudinal surface density fluctuation value does not exceed 0.2%, the slurry fluidity is judged to be excellent.

5. The method for evaluating slurry fluidity and processing performance according to claim 4, characterized in that: The longitudinal fluctuation threshold is 0.1%; when the longitudinal surface density fluctuation value does not exceed 0.1%, the slurry fluidity is determined to be excellent.

6. The method for evaluating slurry fluidity and processing performance according to claim 1, characterized in that: The number of the plurality of transverse detection points in S1 is 12, and the total transverse surface density data sequence is obtained by summing the surface density data of the 12 detection points.

7. The method for evaluating slurry fluidity and processing performance according to claim 3, characterized in that: The lateral fluctuation threshold is 0.2%; when the lateral surface density fluctuation value does not exceed 0.2%, the slurry processing performance is judged to be excellent.

8. The method for evaluating slurry fluidity and processing performance according to claim 7, characterized in that: The lateral fluctuation threshold is 0.1%; when the lateral surface density fluctuation value does not exceed 0.1%, the slurry processing performance is determined to be excellent.

9. The method for evaluating slurry fluidity and processing performance according to claim 1, characterized in that: Adding comprehensive judgment conditions in S4; When the longitudinal surface density fluctuation value does not exceed 0.5% and the transverse surface density fluctuation value does not exceed 0.5%, the overall quality of the coating process is judged to be qualified.

10. The method for evaluating slurry fluidity and processing performance according to claim 9, characterized in that: The conditions for judging the comprehensive quality as excellent are: the longitudinal surface density fluctuation value does not exceed 0.2% and the transverse surface density fluctuation value does not exceed 0.2%.

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