Homogenizing method and homogenizing system for battery slurry

Abstract

The invention relates to the technical field of battery manufacturing, and provides a battery slurry homogenizing method and a battery slurry homogenizing system.The homogenizing method comprises the steps that the specific surface area S and the particle size D of an active material are obtained; judging the formula interval of the active material according to the specific surface area S and the particle size D; and obtaining homogenate process parameters according to the formula interval, and stirring the active material according to the homogenate process parameters. The formula interval matched with the active material is determined by acquiring the specific surface area S and the particle size D of the active material, so that stirring is performed by adopting the optimal parameters suitable for the active material, and the prepared slurry has the properties of high stability, uniform viscosity and uniform dispersion.

Description

Technical Field

[0001] The present invention relates to the technical field of battery manufacturing, and in particular, to a homogenization method and a homogenization system for battery slurry. Background Art

[0002] According to industry research reports, driven by the explosive growth of downstream application scenarios such as new energy vehicles and energy storage, the global battery industry is booming, and the demand for batteries is also increasing day by day. In the production and manufacturing process of batteries, the homogenization quality and efficiency of battery slurry have a significant impact on the overall quality and output efficiency of batteries. Therefore, how to achieve faster and better homogenization of battery slurry has become a top priority.

[0003] Due to the influence of the preparation process of the active material of the battery, the physical and chemical parameters (such as particle size and specific surface area) of the active material fluctuate frequently between different batches, resulting in problems such as large viscosity fluctuations, poor dispersion effects, and abnormal fineness of the homogenized battery slurry due to excessive changes in the physical and chemical parameters of the active material when switching batches of the active material, directly affecting the production efficiency of coating and subsequent processes, and also affecting the performance of the final battery.

[0004] Therefore, there is an urgent need to provide a homogenization method and a homogenization system for battery slurry. Summary of the Invention

[0005] The present invention aims to solve at least one of the above technical problems.

[0006] The present invention provides a homogenization method for battery slurry, including: obtaining the specific surface area S and particle size D of the active material; judging the formulation interval where the active material is located according to the specific surface area S and particle size D; obtaining homogenization process parameters according to the formulation interval, and stirring the active material according to the homogenization process parameters.

[0007] In any of the above technical solutions, obtaining the specific surface area S and particle size D of the active material includes: confirming the specific surface area S and particle size D of the active material by identifying the identification code corresponding to the active material.

[0008] In any of the above technical solutions, judging the formulation interval where the active material is located according to the specific surface area S and particle size D includes: determining the particle size distribution value β according to the particle size D; judging the formulation interval where the active material is located according to the specific surface area S and the particle size distribution value β.

[0009] In any of the above technical solutions, the particle size distribution value β is determined according to the following formula:

[0010]

[0011] Among them, D90 represents the particle size corresponding to when the cumulative particle size distribution number reaches 90%; D10 represents the particle size corresponding to when the cumulative particle size distribution number reaches 10%; D50 represents the particle size corresponding to when the cumulative particle size distribution number reaches 50%.

[0012] In any of the above technical solutions, obtaining the homogenization process parameters according to the formulation range and stirring the active material according to the homogenization process parameters includes: obtaining the kneading solid content according to the formulation range; stirring the active material according to the kneading solid content.

[0013] In any of the above technical solutions, the stirring is carried out by a twin-screw extruder.

[0014] In any of the above technical solutions, stirring the active material according to the kneading solid content includes: adding a target mass of solvent according to the kneading solid content and the mass of the active material; stirring the active material and the solvent.

[0015] In any of the above technical solutions, obtaining the homogenization process parameters according to the formulation range and stirring the active material according to the homogenization process parameters further includes: obtaining the kneading solid content, stirring speed and kneading duration according to the formulation range; stirring the active material according to the kneading solid content, stirring speed and kneading duration.

[0016] In any of the above technical solutions, the stirring is carried out by a double planetary mixer.

[0017] In any of the above technical solutions, stirring the active material according to the kneading solid content, stirring speed and kneading duration includes:

[0018] Adding a target mass of solvent according to the kneading solid content and the mass of the active material;

[0019] Stirring the active material and the solvent according to the stirring speed and kneading duration.

[0020] To achieve the second object of the present invention, the present invention also provides a homogenization system for battery slurry, including: a feeding system for feeding the active material and obtaining the specific surface area S and particle size D of the active material; a central control system for judging the formulation range where the active material is located according to the specific surface area S and particle size D of the active material and obtaining the homogenization process parameters according to the formulation range; a stirring system for stirring the active material according to the homogenization process parameters.

[0021] After adopting the technical solution of the present invention, the following technical effects can be achieved:

[0022] 1. By obtaining the specific surface area S and particle size D of the active material to determine the formulation range adapted to the active material, and thus stirring with the best parameters suitable for the active material, the prepared slurry has the properties of high stability, uniform viscosity and uniform dispersion.

[0023] 2. The control method of the homogenization process of the present invention can be used in combination with various mixers for production, thus fundamentally avoiding process abnormalities caused by switching between raw material batches. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the control method of the homogenization process of the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] In the related art, it is usually adopted to feedback the viscosity range of the slurry detected in the mixing tank to the central control unit to match the corresponding equipment parameters, and drive the mixing unit to mix the slurry; the focus of this method is to solve the problem that the slurry settles during the storage process in the buffer tank after homogenization, which will reduce the viscosity of the slurry and the overall uniformity of the slurry, and is not conducive to the subsequent coating operation. This method cannot fundamentally control the quality of the slurry. If there is a situation where the physical and chemical parameters of the raw materials fluctuate greatly and exceed the current process compatibility range, there will be no way to remedy it in the buffer tank.

[0027] In view of this, the present invention provides a control method and system for a homogenization process, which selects a suitable formula range according to the specific surface area S and particle size D of the active material to mix the slurry, so that the slurry has the characteristics of high stability, uniform viscosity and uniform dispersion after production.

[0028] Embodiment 1

[0029] As Figure 1 shown, the embodiment of the present invention provides a method for homogenizing a battery slurry, including: obtaining the specific surface area S and particle size D of the active material; judging the formula range where the active material is located according to the specific surface area S and particle size D; obtaining the homogenization process parameters according to the formula range, and mixing the active according to the homogenization process parameters.

[0030] The inventors of the present invention have found that during the homogenization process of battery slurries, the physicochemical parameters of the active materials have the greatest impact on issues such as the viscosity, dispersion uniformity, and stability of the slurries. Among them, the active materials can specifically be graphite used as the negative electrode active material or lithium iron phosphate used as the positive electrode active material, etc. Among the physicochemical parameters, the most influential ones are the particle size and specific surface area of the particles. Therefore, the formulation ranges are mainly divided according to the particle size and specific surface area of the main active materials. The present invention obtains the specific surface area S and particle size D of the active materials, and judges the formulation range where the active materials are located according to the specific surface area S and particle size D, so as to be able to dynamically adjust the process parameters according to the active materials with different physicochemical parameters, ensure the precise matching of the homogenization process parameters and the physicochemical parameters of the active materials, optimize the homogenization effect, effectively prevent the quality instability problems caused by the fluctuations of the physicochemical parameters of the active materials, and improve the quality consistency and product controllability of the slurries.

[0031] Among them, the formulation ranges are multiple ranges set after verifying the corresponding preferred process parameters in advance by using active materials with different gradients of specific surface area S and particle size D, that is, active materials with different specific surface areas S and particle sizes D each have their most suitable formulation ranges; after obtaining the specific surface area S and particle size D of the active materials, compare the obtained specific surface area S and particle size D with the set values of each formulated range to judge the formulated range where the active materials are located, and read the homogenization process parameters corresponding to this formulated range, and then stir the active materials according to this homogenization process parameter, so that the prepared slurry has an appropriate viscosity and good dispersion uniformity; the control method of the homogenization process of the present invention is applicable to various active materials and can be combined with various mixers for production, thus fundamentally avoiding the process abnormalities caused by the switching between different batches of raw materials. It should be particularly noted that when stirring the active materials, the mixer not only includes the active materials, but also other conventional components in the slurry such as binders, solvents, and conductive agents, etc., and the present invention does not limit this. And the method of the present invention is applicable to homogenizing different batches of products of the same active material.

[0032] In some embodiments of the present invention, obtaining the specific surface area S and particle size D of the active materials includes: confirming the specific surface area S and particle size D of the active materials by identifying the corresponding identification code of the active materials.

[0033] Preferably, the identification code is a two-dimensional code for the material information of the active material. A PDA (public display of affection, handheld terminal device) can be used to scan the two-dimensional code for the material information of the active material. Before the homogenization process, the specific surface area S and particle size D of the active material have been tested and uploaded to the ERP (Enterprise Resource Planning) system. Each active material to be fed into production has its corresponding two-dimensional code for material information, which records the physical and chemical parameters of the active material, including the specific surface area S and particle size D. By scanning the two-dimensional code for the material information corresponding to the active material with a PDA, the data of the specific surface area S and particle size D of the active material can be retrieved from the ERP system, enabling real-time acquisition of the data of the specific surface area S and particle size D of the active material, thus completing the step of obtaining the specific surface area S and particle size D of the active material. This is simple and fast, and easy to implement. Among them, the measurement of the specific surface area S and particle size D of the active material is a conventional method and will not be described in detail here. It can be the measurement carried out by the manufacturer, and the corresponding data can be directly obtained from the manufacturer, or it can be measured using instruments such as a specific surface area analyzer and a particle size analyzer. There is no limitation here.

[0034] Furthermore, only by scanning the two-dimensional code for the material information of the active material with a PDA device, the corresponding physical and chemical parameters can be automatically extracted from the ERP system. This not only enables more efficient and rapid acquisition of the data of the specific surface area S and particle size D of the active material during homogenization, greatly simplifies the production process, and reduces the operational complexity, but also is not prone to errors during the process of obtaining the specific surface area S and particle size D of the active material, further ensuring the accuracy of the selection of the formulation range. As a result, the homogenization process parameters applied during the subsequent stirring process are most suitable for this active material, making the properties of the prepared slurry better and capable of bringing better performance for subsequent application in batteries.

[0035] In some embodiments of the present invention, determining the formulation range where the active material is located based on the specific surface area S and particle size D includes: determining the particle size distribution value β according to the particle size D; and determining the formulation range where the active material is located based on the specific surface area S and the particle size distribution value β.

[0036] Preferably, for different batches of the same active material, the influence of the particle size D on the homogenization effect mainly lies in the particle size distribution. Therefore, by introducing the particle size distribution value β, the characteristics of the particle size distribution of the active material can be more precisely quantified, which is beneficial to improving the treatment effect of the slurry.

[0037] In some embodiments of the present invention, the particle size distribution value β is determined according to the following formula:

[0038]

[0039] Among them, D90 represents the particle size corresponding to when the cumulative particle size distribution number reaches 90%; D10 represents the particle size corresponding to when the cumulative particle size distribution number reaches 10%; D50 represents the particle size corresponding to when the cumulative particle size distribution number reaches 50%.

[0040] By determining the particle size distribution value β through the above formula, the deviation and its distribution range of the particle size distribution can be more comprehensively reflected, avoiding the inability to comprehensively analyze the deviation and its distribution range of the particle size distribution by only using the median particle size D50, etc., making the selected formulation interval more reasonable, facilitating the subsequent stirring, and enabling the prepared slurry to have better various properties.

[0041] In some embodiments of the present invention, according to the formulation interval, homogenization process parameters are obtained, and stirring the active material according to the homogenization process parameters includes: obtaining the kneading solid content according to the formulation interval; and stirring the active material according to the kneading solid content.

[0042] After determining the formulation interval of the active material, homogenization process parameters such as the kneading solid content can be read. The kneading solid content is an important process parameter in the homogenization process, directly affecting the viscosity, dispersibility, and stability of the slurry. If the solid content is too low, the slurry may be too thin and have poor dispersibility; if the solid content is too high, the slurry will be too viscous and difficult to stir. Reasonably setting the kneading solid content can ensure that the viscosity of the slurry is within the optimal range. The kneading solid content can characterize the solid-liquid ratio of the slurry, which is crucial for optimizing the rheological properties, mixing uniformity, and adaptability of subsequent processing of the slurry. The kneading solid content is one of the key factors affecting the viscosity of the slurry. By setting corresponding kneading solid contents for different formulation intervals, a suitable solid content can be matched according to the parameters of the active material, thereby improving the dispersion uniformity of the slurry.

[0043] Furthermore, the inventors of the present invention found that for active materials with different particle size distributions and specific surface areas, the suitable kneading solid content will also be different. The larger the particle size and the smaller the specific surface area, the higher the suitable kneading solid content; the smaller the particle size and the larger the specific surface area, the lower the suitable kneading solid content. Therefore, by selecting different formulation intervals according to the specific surface area S and particle size D of the active material, the slurry can have the most suitable solid content, so that the viscosity of the prepared slurry is appropriate, which is beneficial for subsequent applications in batteries.

[0044] In some embodiments of the present invention, the stirring is carried out by a twin-screw extruder. The twin-screw extruder can quickly mix the active material and the solvent through the high-shear action between the screws, and can complete the dispersion and homogenization of the material relatively quickly, usually without the need for stirring for too long. Therefore, when using a twin-screw extruder for stirring, due to its high-shear working principle, only the kneading solid content needs to be determined to control the homogenization effect of the slurry. For other stirring devices whose homogenization effect is mainly affected by the kneading solid content, the kneading solid content can also be obtained to stir the active material.

[0045] In some embodiments of the present invention, stirring the active material according to the kneading solid content includes: adding a target mass of solvent according to the kneading solid content and the mass of the active material; stirring the active material and the solvent.

[0046] In the present invention, the kneading solid content satisfies the following formula relationship:

[0047]

[0048] where G 干 is the mass of the active material, and G 溶剂 is the mass of the solvent.

[0049] Specifically, the kneading solid content in the present invention refers to the ratio of the mass of the active material to the total mass of the active material and the solvent. In the actual slurry, the solid components also include a small amount of conductive agents, binders, etc., so the actual solid content of the slurry is different from the obtained kneading solid content.

[0050] In some embodiments of the present invention, obtaining the homogenization process parameters according to the formulation range and stirring the active material according to the homogenization process parameters further includes: obtaining the kneading solid content, stirring speed, and kneading duration according to the formulation range; stirring the active material according to the kneading solid content, stirring speed, and kneading duration.

[0051] In this embodiment, the homogenization process parameters include kneading solid content, stirring speed, and kneading duration. The stirring speed refers to the rotation rate of the stirring equipment during the homogenization process, and the kneading duration refers to the length of time during which the active material is mixed and stirred with the solvent or other components during the homogenization process. The kneading solid content, stirring speed, and kneading duration are all important control parameters in the homogenization process. Among them, the stirring speed directly affects the uniformity, dispersibility, viscosity, and stability of the slurry. The selection of the stirring speed is crucial for the dispersion uniformity of the slurry. Excessive speed may cause excessive shear, resulting in aggregation or fragmentation of the particles due to excessive external force, while too low speed may not effectively disperse the active material. Adjusting the stirring speed can ensure good dispersibility of the slurry during the stirring process and avoid uneven distribution of the particles in the slurry. The kneading duration determines the completion degree of the stirring process. Too long or too short kneading duration will affect the quality of the slurry. By determining the kneading duration, the homogenization process can be optimized to achieve the optimal production efficiency. The particle sizes of the active materials are different, and the requirements for the stirring speed and kneading duration are also different. Therefore, by selecting different stirring speeds and kneading durations in different formulation ranges, the uniformity of the slurry quality can be further improved, thereby making the properties of the prepared slurry better.

[0052] In some embodiments of the examples of the present invention, the stirring is carried out using a double planetary mixer. The double planetary mixer stirs at a relatively low speed through two planetary stirring cutters. Due to its relatively low shear force, the mixing process of the materials in the mixer usually takes a longer time to achieve the desired uniformity and dispersibility. Therefore, when using a double planetary mixer for stirring, in addition to the influence of the kneading solid content, both the kneading duration and the stirring speed have a greater impact. Therefore, it is necessary to comprehensively consider the kneading solid content, stirring speed, and kneading duration to ensure that the materials are fully stirred within a suitable time. This method is also applicable to other stirring devices whose homogenization effect is affected by the kneading solid content, stirring speed, and kneading duration. The specific homogenization process parameters required are adaptively set according to the specific stirring device used and will not be listed one by one here.

[0053] In some embodiments of the examples of the present invention, stirring the active material according to the kneading solid content, stirring speed, and kneading duration includes: adding a target mass of solvent according to the kneading solid content and the mass of the active material; stirring the active material and the solvent according to the stirring speed and the kneading duration.

[0054] Examples:

[0055] A double planetary mixer was used for stirring, the active material was graphite (Anhui Keda New Materials Co., Ltd., KD-1), the solvent was deionized water and NMP (N-methylpyrrolidone), wherein NMP (N-methylpyrrolidone) was added at 0.8% of the total weight of the solvent, and the corresponding formula intervals were determined for different batches of graphite according to their specific surface area β values ​​and the corresponding homogenization process parameters were matched for homogenization treatment to obtain slurry. The homogenization process parameters corresponding to each formula interval are shown in Table 1 below, and the specific graphite specific surface area, β value and corresponding slurry viscosity extreme difference of each embodiment are shown in Table 2 below:

[0056] Table 1 Correspondence between formulation intervals and homogenization process parameters

[0057] Scheme Setting Specific Surface Area β Value Kneading Solid Content Stirring Speed Kneading Duration Interval 1 >1.6 ＜1.43 68％ 25 rpm 90 min Interval 2 1.5-1.6 1.43-1.55 68.8％ 35 rpm 70 min Interval 3 1.3-1.5 1.55-1.60 69％ 25 rpm 60 min Interval 4 <1.3 ＞1.60 69.5％ 25 rpm 70 min

[0058] Comparative Example:

[0059] A double planetary mixer was used for stirring. The active material was graphite (Anhui Keda New Materials Co., Ltd., KD-1). The solvents were deionized water and NMP (N-methylpyrrolidone). NMP (N-methylpyrrolidone) was added at 0.8% of the total weight of the solvent. Different batches of graphite were homogenized with a kneading solid content of 68%, a stirring speed of 30 rpm and a kneading time of 60 min to obtain a slurry. The specific graphite specific surface area, β value and corresponding slurry viscosity of each comparative example are shown in Table 2 below.

[0060] The test method for testing the viscosity of the slurry obtained in the examples and comparative examples is as follows:

[0061] The test was conducted using a Brookfield rotational viscometer with a 64# rotor, and the slurry viscosity value was read based on the test results. The viscosity described here is a quick characterization of the viscosity consistency improvement effect, and the viscosity is defined as the difference between the slurry viscosity and the viscosity standard under different schemes.

[0062] Table 2 Specific surface area of ​​each embodiment and viscosity of slurry

[0063]

[0064]

[0065] It can be seen from Table 2 that after the automatic adaptive adjustment of the scheme of the present invention, the difference in slurry viscosity between the embodiments is small, while the difference in slurry viscosity between the comparative examples is increased. The slurry viscosity consistency is greatly improved by adopting the scheme of the present invention, avoiding process abnormalities caused by viscosity fluctuations due to differences between raw material batches; in terms of slurry stability, the extreme difference of static solid content is tested, which is greatly reduced after the scheme is activated, indicating that the slurry dispersion consistency is improved.

[0066] Embodiment 2

[0067] An embodiment of the present invention provides a control system for a homogenization process, which is used to implement the homogenization method in the first embodiment, including: a feeding system for feeding active materials and obtaining the specific surface area S and particle size D of the active materials; a central control system for judging the formula interval where the active materials are located according to the specific surface area S and particle size D of the active materials and obtaining homogenization process parameters according to the formula interval; and a stirring system for stirring the active materials according to the homogenization process parameters.

[0068] Specifically, before the active materials enter the feeding system, after being detected by the incoming inspection center, various physical and chemical parameters are uploaded to the ERP system. After the active materials reach the feeding system, the material information QR code is first scanned by PDA. After scanning, the physical and chemical parameters of the active materials are uploaded to the central control system through the MES (Manufacturing Execution System) system. Multiple formula intervals covering different specific surface areas S and particle sizes D are set in the central control system. After transmitting the specific surface area S and particle size D to the central control system, the central control system first determines the corresponding particle size distribution value β, and then reads the particle size distribution value β set for each formula interval stored in the central control system 设定 and the specific surface area S, and judges the formula interval where the active materials are located by comparison to select the formula interval most matching the active materials. The formula interval has pre-matched homogenization process parameters. After the central control system reads the corresponding homogenization process parameters, the homogenization process parameters are transmitted to the stirring system, and the stirring system stirs according to the homogenization process parameters, so that the prepared slurry has appropriate viscosity and good dispersion uniformity, thereby fundamentally avoiding process anomalies caused by switching between raw material batches. Among them, the homogenization process parameters can include kneading solid content, or can include kneading solid content, stirring speed and kneading time at the same time.

[0069] In some embodiments of the embodiment of the present invention, the homogenization system further includes a solvent addition system for adding a solvent to the stirring system.

[0070] In some embodiments of the embodiment of the present invention, the stirring system includes a twin-screw extruder or a double planetary mixer.

[0071] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for homogenizing battery slurry, characterized in that: include: Obtain the specific surface area S and particle size D of the active material; Determine the formulation interval of the active material according to the specific surface area S and the particle size D; The homogenization process parameters are obtained according to the recipe interval, and the active material is stirred according to the homogenization process parameters.

2. The homogenization method according to claim 1, characterized in that The determining of the formulation interval of the active material according to the specific surface area S and the particle size D includes: Determine the particle size distribution value β based on the particle size D; The formulation interval of the active material is determined according to the specific surface area S and the particle size distribution value β.

3. The homogenization method according to claim 2, characterized in that: The particle size distribution value β is determined according to the following formula: Among them, D90 represents the particle size corresponding to 90% of the cumulative particle size distribution number; D10 represents the particle size corresponding to 10% of the cumulative particle size distribution number; and D50 represents the particle size corresponding to 50% of the cumulative particle size distribution number.

4. The homogenization method according to claim 1, characterized in that: The obtaining of homogenization process parameters according to the recipe interval and stirring the active material according to the homogenization process parameters comprises: Obtaining kneaded solid content according to the formula interval; The active material is stirred according to the kneaded solid content.

5. The homogenization method according to claim 4, characterized in that: The stirring is carried out by using a twin-screw extruder.

6. The homogenization method according to claim 4, characterized in that: The stirring of the active material according to the kneaded solid content comprises: Adding a target mass of solvent according to the mass of the kneaded solid content and the mass of the active material; The active material and the solvent are stirred.

7. The homogenization method according to claim 1, characterized in that: The obtaining of homogenization process parameters according to the formula interval, and stirring the active material according to the homogenization process parameters further comprises: According to the formula interval, the kneading solid content, stirring speed and kneading time are obtained; The active material is stirred according to the kneading solid content, the stirring speed and the kneading time.

8. The homogenization method according to claim 7, characterized in that: The stirring is carried out by using a double planetary mixer.

9. The homogenization method according to claim 7, characterized in that: The stirring of the active material according to the kneading solid content, the stirring speed and the kneading time comprises: Adding a target mass of solvent according to the mass of the kneaded solid content and the mass of the active material; The active material and the solvent are stirred according to the stirring rotation speed and the kneading time.

10. A battery slurry homogenization system, characterized in that: The homogenization system comprises: A feeding system, wherein the feeding system is used to feed active materials and obtain the specific surface area S and particle size D of the active materials; A central control system, the central control system is used to determine the formulation interval of the active material according to the specific surface area S and the particle size D of the active material, and to obtain homogenization process parameters according to the formulation interval; A stirring system is used to stir the active material according to the homogenization process parameters.

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