Device and method for testing dispersed state of battery slurry

Abstract

The invention provides a device and a method for testing the dispersed state of battery slurry, and belongs to the technical field of secondary batteries. Through the testing device and the testing method, the dispersed state of the battery slurry can be quickly and accurately obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of secondary batteries, and particularly relates to a test device and a test method for the dispersion state of battery slurry. Background Art

[0002] At present, secondary batteries such as lithium-ion batteries and sodium-ion batteries are everywhere in our lives, and the pursuit of the performance of secondary batteries is also increasing day by day. The quality of the battery slurry used in secondary batteries directly affects the electrical performance of the batteries. The more uniformly the components in the battery slurry are dispersed, the more thoroughly each active substance will play during charging and discharging.

[0003] At present, in the secondary battery industry, the devices and methods for testing the dispersion state of battery slurry are relatively unified. Generally, a viscometer is used to measure the viscosity of the battery slurry, and a fineness meter is used to measure the fineness of the battery slurry. However, because the battery slurry is undergoing Brownian motion, its viscosity is constantly changing and is closely related to temperature, and the position of measuring the viscosity of the sample each time is not uniform, which is prone to deviation.

[0004] Improvements have been made in related technologies. For example, patent application document CN113363470A discloses a method for quickly obtaining a suitable range of kneading solid content of slurry. This method centrifuges the slurry using different centrifugation processes, removes the separated solvents after centrifugation to obtain several groups of remaining slurries, calculates the kneading solid content of several groups of remaining slurries, and determines the suitable range of the kneading solid content of the slurry. However, this method subsequently uses the naked eye observation method to judge the quality of the kneading state, which is relatively difficult to implement and has a large error in actual operation.

[0005] Patent application document CN109839328A discloses a method for judging the dispersion effect of lithium-ion battery slurry. This judgment method realizes the judgment of the dispersion effect of lithium-ion battery slurry by measuring the standard deviation of the viscosity and the standard deviation of the density of the slurry. The specific method is to judge the dispersion effect of the positive and negative electrode slurries from two aspects: the standard deviation of the slurry viscosity and the standard deviation of the slurry density at different positions in the stirring container. However, this method requires about 10 points to test multiple groups of data for judgment, which affects the actual production efficiency.

[0006] Patent application document CN114295497A discloses a device and method for testing the state of lithium-ion battery slurry. This test method is to use a clamp to hold the slurry container and fix it under a universal testing machine; use a probe to pierce the slurry to obtain a piercing force-displacement curve. However, this method has many influencing factors of variables, and factors such as the piercing speed of the probe, the piercing time, and the size of the probe will all affect the test results. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, embodiments of the present invention provide a test device and a test method for the dispersion state of battery slurry. By using the test device to implement the test method, the dispersion state of the battery slurry can be quickly and accurately determined.

[0008] In a first aspect, embodiments of the present invention provide a test device for the dispersion state of battery slurry, including a slurry storage box and a cover body covering the top opening of the slurry storage box. The slurry storage box includes an inner box body and an outer box body. The inner box body is disposed inside the outer box body and is connected to the outer box body. A sealed first hollow chamber is formed between the inner box body and the outer box body. The cover body is disposed on the top of the slurry storage box and is detachably connected to the slurry storage box. The cover body is provided with a first perforation and a second perforation. A heating rod that can be inserted into the inner box body is disposed in the first perforation, and a thermometer that can be inserted into the inner box body is disposed in the second perforation.

[0009] The advantages and technical effects brought by the test device of the embodiments of the present invention are as follows:

[0010] (1) The test device of the embodiments of the present invention is divided into a slurry storage box and a detachable cover body, which is convenient for injecting and removing the battery slurry.

[0011] (2) In the test device of the embodiments of the present invention, the slurry storage box adopts a double-layer design of an inner box body and an outer box body, and a sealed first hollow chamber is formed between the inner box body and the outer box body, which can ensure the heat insulation of the test device, avoid the measured specific heat capacity c of the battery slurry measured in step S2 of the test method in the second aspect being too large, and thus avoid the deviation of the judgment result of the dispersion state of the battery slurry in step S3 of the test method in the second aspect.

[0012] (3) The cover body of the test device of the embodiments of the present invention is provided with a first perforation and a second perforation. A heating rod that can be inserted into the inner box body is disposed in the first perforation, and a thermometer that can be inserted into the inner box body is disposed in the second perforation. The heating rod is used to heat the battery slurry in the slurry storage box, and the thermometer is used to measure the initial temperature T1 and the final temperature T2 of the battery slurry in the slurry storage box. Moreover, when the test method in the second aspect is used to test the battery slurry in different kneading states, since the positions of the heating rod and the thermometer in the test device of the embodiments of the present invention are fixed and unchanged, the deviation of the heat source position and the temperature measurement position on the test result can be excluded, making the test result of step S3 accurate and reliable.

[0013] In some embodiments, the outer box body is provided with a first vacuum pumping port communicating with the first hollow chamber.

[0014] In some embodiments, the first hollow chamber is located on the side wall and bottom of the inner box body.

[0015] In some embodiments, a bracket is provided at the bottom of the slurry storage box.

[0016] In some embodiments, a liquid level line is provided on the inner wall of the inner box body.

[0017] In some embodiments, a second hollow chamber is provided inside the cover body.

[0018] In some embodiments, a second vacuum pumping port communicating with the second vacuum chamber is provided on the outer cover body.

[0019] In some embodiments, the second hollow chamber covers the top opening of the entire slurry storage box.

[0020] In a second aspect, an embodiment of the present invention provides a method for testing the dispersion state of battery slurry, which is tested by using the testing device of the first aspect. The testing method includes the following steps:

[0021] S1. Keep the first hollow chamber in a vacuum state. Preferably, keep the second hollow chamber also in a vacuum state. In addition, add battery slurry with a mass of m into the inner box body, then cover the cover body on the top of the slurry storage box, and insert both the heating rod and the thermometer into the battery slurry.

[0022] S2. Record the initial temperature of the battery slurry as T1, then heat the battery slurry through the heating rod. The resistance of the heating rod is R, the current used to heat the heating rod is I, and the heating time is t. After heating, record the final temperature of the battery slurry as T2. Calculate the heat release energy Q according to Formula 1, and then substitute the heat release energy Q into Formula 2 to calculate the measured specific heat capacity c of the battery slurry.

[0023] Formula 1: Q = I 2 Rt,

[0024] Formula 2: Q = cm(T2 - T1),

[0025] where c is the measured specific heat capacity of the battery slurry, with the unit of J / Kg·℃,

[0026] Q is the heat release energy, with the unit of J,

[0027] m is the mass of the battery slurry, with the unit of Kg,

[0028] T1 is the initial temperature of the battery slurry, with the unit of ℃,

[0029] T2 is the final temperature of the battery slurry, with the unit of ℃,

[0030] I is the current used to heat the heating rod, with the unit of A.

[0031] R is the resistance of the heating rod, with the unit of Ω.

[0032] t is the heating time, with the unit of s.

[0033] S3. Compare the measured specific heat capacity c of the battery paste with the standard specific heat capacity c of the qualified battery paste 标 to judge the dispersion state of the battery paste.

[0034] The advantages and technical effects brought by the test method of the embodiment of the present invention are as follows:

[0035] (1) Step S1 is the preparatory work before the test. Keeping the first hollow chamber in a vacuum state is to ensure the adiabaticity of the test device, avoid the measured specific heat capacity c of the battery paste measured in step S2 being too large, and thus avoid the deviation of the judgment result of the dispersion state of the battery paste in step S3.

[0036] (2) After covering the cover in step S1, the heating rod and thermometer passing through the cover can be inserted into the battery paste, rather than suspended above the battery paste, which can avoid the final temperature T2 of the battery paste measured in step S2 being too low, and thus avoid the deviation of the judgment result of the dispersion state of the battery paste in step S3.

[0037] (3) When using the test method of the embodiment of the present invention to test battery pastes in different kneading states, since the positions of the heating rod and thermometer in step S1 remain unchanged, the influence of these external factors on the test results can be excluded, making the test results in step S3 accurate and reliable.

[0038] (4) Step S2 is the work in the process of testing the specific heat capacity c of the battery paste. In this process, only several test data such as T1, R, I, t, and T2 need to be recorded, and then the measured specific heat capacity c of the battery paste can be calculated through Physics Formula 1 and Formula 2. It is relatively easy to execute in the actual application process and has high accuracy.

[0039] (5) Step S3 is the evaluation work of the dispersion state of the battery paste after measuring the specific heat capacity c of the battery paste. In this step, by comparing the measured specific heat capacity c of the battery paste with the standard specific heat capacity c of the qualified battery paste 标 to judge the dispersion state of the battery paste, only this set of data needs to be compared, and the production efficiency is high.

[0040] (6) The specific heat capacities of different objects are different. According to the different powders and solvents used in the battery paste, the relative magnitude relationship of the specific heat capacities of the powders and solvents can be known. Therefore, the test method in the embodiments of the present invention uses the specific heat capacity of the battery paste as an evaluation index for the dispersion state of the battery paste. In step S3, the actually measured specific heat capacity c of the battery paste is compared with the standard specific heat capacity c of the qualified battery paste. 标 After the comparison, it can be preliminarily determined whether the dispersion state of the battery paste is qualified, and how to add materials subsequently to adjust the solid-liquid ratio of the battery paste.

[0041] In some embodiments, in step S1, the second hollow chamber is also maintained in a vacuum state.

[0042] In some embodiments, in step S3, when the specific heat capacity of the solvent in the battery paste is greater than the specific heat capacity of the powder, when the actually measured specific heat capacity c of the battery paste is less than the standard specific heat capacity c of the qualified battery paste. 标 At this time, a solvent needs to be added to the battery paste, and then kneading is continued. When the actually measured specific heat capacity c of the battery paste is greater than the standard specific heat capacity c of the qualified battery paste. 标 At this time, a powder needs to be added to the battery paste, and then kneading is continued; when the actually measured specific heat capacity c of the battery paste is equal to the standard specific heat capacity c of the qualified battery paste. 标 At this time, the battery paste is qualified. Description of the Drawings

[0043] Figure 1 is a schematic three-dimensional structure diagram of the test device in the embodiments of the present invention.

[0044] Figure 2 is a front view of the test device in the embodiments of the present invention.

[0045] Figure 3 is a schematic three-dimensional structure diagram of the slurry storage box of the test device in the embodiments of the present invention.

[0046] Figure 4 is a front view of the slurry storage box of the test device in the embodiments of the present invention.

[0047] Figure 5 is a schematic three-dimensional structure diagram of the cover body of the test device in the embodiments of the present invention.

[0048] Figure 6 is a front view of the cover body of the test device in the embodiments of the present invention.

[0049] Figure 7 is another front view of the test device in the embodiments of the present invention.

[0050] Description of the Reference Numerals:

[0051] 1 - Inner box body, 2 - Outer box body, 3 - First hollow chamber, 4 - First perforation, 5 - Second perforation, 6 - Heating rod, 7 - Thermometer, 8 - First vacuum extraction port, 9 - Bracket, 10 Liquid level line, 11 - Fixing part, 12 - Sealing part, 13 - Second hollow chamber, 14 - Second vacuum extraction port. Detailed implementation manners

[0052] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0053] In a first aspect, an embodiment of the present invention provides a test device for the dispersion state of battery slurry, as Figures 1-7 shown, including a slurry storage box and a cover covering the top opening of the slurry storage box. The slurry storage box includes an inner box body 1 and an outer box body 2. The inner box body 1 is disposed inside the outer box body 2 and is connected to the outer box body 2. A sealed first hollow chamber 3 is formed between the inner box body 1 and the outer box body 2. The cover is disposed on the top of the slurry storage box and is detachably connected to the slurry storage box. The cover is provided with a first perforation 4 and a second perforation 5. A heating rod 6 that can be inserted into the inner box body 1 is disposed in the first perforation 1, and a thermometer 7 that can be inserted into the inner box body 1 is disposed in the second perforation 5.

[0054] The test device of the embodiment of the present invention is divided into a slurry storage box and a cover covering the top opening of the slurry storage box, and the two are detachably connected, which is convenient for injecting and taking out the battery slurry.

[0055] In addition, in the test device of the embodiment of the present invention, the slurry storage box adopts a double - layer design of an inner box body and an outer box body, and a sealed first hollow chamber is formed between the inner box body and the outer box body, which can ensure the heat insulation of the test device, avoid the measured specific heat capacity c of the battery slurry measured in step S2 of the second - aspect test method from being too large, and thus avoid the deviation of the judgment result of the dispersion state of the battery slurry in step S3 of the second - aspect test method.

[0056] Furthermore, the cover of the test device of the embodiment of the present invention is provided with a first perforation and a second perforation. A heating rod that can be inserted into the inner box body is disposed in the first perforation, and a thermometer that can be inserted into the inner box body is disposed in the second perforation. The heating rod is used to heat the battery slurry in the slurry storage box, and the thermometer is used to measure the initial temperature T1 and the final temperature T2 of the battery slurry in the slurry storage box. Moreover, when the test method of the second aspect is used to test the battery slurry in different kneading states, since the positions of the heating rod and the thermometer in the test device of the embodiment of the present invention are fixed and unchanged, the influence of the deviation of the heat source position and the temperature measurement position on the test result can be excluded, making the test result of step S3 accurate and reliable.

[0057] In some embodiments, as Figure 2 , 4 , as shown in Figures 6 and 7, a first vacuum pumping port 8 communicating with the first hollow chamber 3 is provided on the outer box body 2. The first hollow chamber can be evacuated through the first vacuum pumping port. It can be understood that after the first evacuation of the first hollow chamber, during the process of maintaining the vacuum state in the first hollow chamber, multiple tests of the measured specific heat capacity c of the battery slurry can be carried out.

[0058] In some embodiments, as Figures 1-4 , as shown in Figure 7, the first hollow chamber 3 is located on the side wall and bottom of the inner box body 1, that is, a sealed first hollow chamber 3 is formed between the side wall and bottom of the inner box body 1 and the outer box body 2. In some other embodiments, the first hollow chamber 3 is only located on the side wall of the inner box body 1. In still some other embodiments, the first hollow chamber 3 is only located on the bottom of the inner box body 1. Preferably, the first hollow chamber 3 is located on the entire side wall and bottom of the inner box body 1, and this situation is more conducive to improving the heat insulation of the test device.

[0059] In some embodiments, as Figure 7 , as shown in Figure 6, a bracket 9 is provided at the bottom of the slurry storage box. The presence of the bracket can isolate the test device from the ground or the table by a certain distance, which is more conducive to improving the heat insulation of the test device.

[0060] In some embodiments, as Figure 7 , as shown in Figure 6, a liquid level line 10 is provided on the inner wall of the inner box body 1. The presence of the liquid level line can be used to measure whether the injection amount of the battery slurry is sufficient, and to avoid deviation of the test results caused by the heating rod and the thermometer not being in contact with the battery slurry but hanging above the battery slurry after the cover is closed.

[0061] In some embodiments, as Figure 5 , 6 , as shown in Figures 6 and 7, the cover body includes a fixing part 11 and a sealing part 12 provided on the top of the fixing part 11. The diameter of the fixing part 11 is slightly smaller than the top opening of the slurry storage box and can be inserted into the top opening of the slurry storage box. The diameter of the sealing part 12 is larger than the top opening of the slurry storage box and can cover the top opening of the slurry storage box to seal the top opening of the slurry storage box. A second hollow chamber 13 is provided inside the sealing part 12. The cover body also adopts an internal hollow design, which can further improve the heat insulation of the test device.

[0062] It is understandable that the test device in the embodiments of the present invention does not particularly limit the connection manner between the cover body and the slurry storage box, as long as it is convenient to open and close. In addition to the connection manners listed above, other manners can also be adopted. For example, the cover body can be set in a flat plate shape, and the cover body can be directly pressed on the top opening of the slurry storage box for sealing. Or the cover body and the top opening of the slurry storage box can be threadedly connected by providing threads thereon. Or a groove capable of accommodating the side wall of the slurry storage box can be provided at the bottom of the cover body to snap-fit the two. Or connection components can be provided on the outer walls of the cover body and the slurry storage box to connect the two, which is convenient for lifting and buckling the cover body, and so on.

[0063] In some embodiments, as Figure 1 , 2 As shown in Figures 6 and 7, a second vacuum extraction port 14 communicating with the second hollow chamber 13 is provided on the outer cover body 12. The second hollow chamber can be evacuated through the second vacuum extraction port. It is understandable that after the second hollow chamber is evacuated for the first time, during the process of maintaining the vacuum state of the second hollow chamber, multiple tests of the measured specific heat capacity c of the battery slurry can be carried out.

[0064] In some embodiments, as Figure 5 , 6 As shown in the figure, the second hollow chamber 13 covers the entire top opening of the slurry storage box. The positions of the cover body corresponding to the top opening of the slurry storage box are all provided with a hollow structure, which is more conducive to improving the heat insulation of the test device.

[0065] In a second aspect, the embodiments of the present invention provide a method for testing the dispersion state of battery slurry, which is tested by using the test device in the first aspect. The test method includes the following steps:

[0066] S1. Keep the first hollow chamber in a vacuum state; in addition, add battery slurry with a mass of m into the inner box body, then cover the cover body on the top of the slurry storage box, and insert both the heating rod and the thermometer into the battery slurry;

[0067] S2. Record the initial temperature of the battery slurry as T1, then heat the battery slurry through the heating rod. The resistance of the heating rod is R, the current used for heating the heating rod is I, and the heating time is t. After the heating is completed, record the final temperature of the battery slurry as T2. Calculate the heat release energy Q according to Formula 1, and then substitute the heat release energy Q into Formula 2 to calculate the measured specific heat capacity c of the battery slurry;

[0068] Formula 1: Q = I 2 Rt,

[0069] Formula 2: Q = cm(T2 - T1),

[0070] Among them, c is the measured specific heat capacity of the battery slurry, with the unit of J / Kg·℃,

[0071] Q is the exothermic energy, with the unit of J,

[0072] m is the mass of the battery slurry, with the unit of Kg,

[0073] T1 is the initial temperature of the battery slurry, with the unit of ℃,

[0074] T2 is the final temperature of the battery slurry, with the unit of ℃,

[0075] I is the current used to heat the heating rod, with the unit of A,

[0076] R is the resistance of the heating rod, with the unit of Ω,

[0077] t is the heating time, with the unit of s;

[0078] S3. Compare the measured specific heat capacity c of the battery slurry with the standard specific heat capacity c of the qualified battery slurry 标 to judge the dispersion state of the battery slurry.

[0079] Step S1 of the test method in the embodiment of the present invention is the preparatory work before the test. Keeping the first hollow chamber in a vacuum state is to ensure the adiabaticity of the test device, avoid the measured specific heat capacity c of the battery slurry measured in step S2 from being too large, and thus avoid the deviation of the judgment result of the dispersion state of the battery slurry in step S3. In addition, after covering the cover body in step S1, the heating rod and thermometer passing through the cover body can be inserted into the battery slurry, rather than suspended above the battery slurry, which can avoid the final temperature T2 of the battery slurry measured in step S2 from being too low, and thus avoid the deviation of the judgment result of the dispersion state of the battery slurry in step S3. In addition, when using the test method of the embodiment of the present invention to test battery slurries in different kneading states, since the positions of the heating rod and thermometer in step S1 remain unchanged, the influence of these external influencing factors on the test results can be excluded, making the test results in step S3 accurate and reliable.

[0080] Step S2 of the test method in the embodiment of the present invention is the work during the test of the specific heat capacity c of the battery slurry. During this process, only several test data such as T1, R, I, t, and T2 need to be recorded, and then the measured specific heat capacity c of the battery slurry can be calculated through Physics Formulas 1 and 2. It is relatively easy to execute and has high accuracy in the actual application process.

[0081] Step S3 of the test method in the embodiment of the present invention is the evaluation work of the dispersion state of the battery slurry after measuring the specific heat capacity c of the battery slurry. This step judges the dispersion state of the battery slurry by comparing the measured specific heat capacity c of the battery slurry with the standard specific heat capacity c of the qualified battery slurry标 By making a comparison, the dispersion state of the battery slurry can be determined. Only this set of data needs to be compared, and the production efficiency is high.

[0082] It should be understood that the specific heat capacities of different objects are different. According to the different powders and solvents used in the battery slurry, the relative magnitude relationship between the specific heat capacities of the powder and the solvent can be known. Therefore, the test method in the embodiments of the present invention uses the specific heat capacity of the battery slurry as an evaluation index for the dispersion state of the battery slurry. In step S3, the actually measured specific heat capacity c of the battery slurry is compared with the standard specific heat capacity c of the qualified battery slurry. 标 After the comparison, it can be preliminarily determined whether the dispersion state of the battery slurry is qualified and how to add materials subsequently to adjust the solid-liquid ratio of the battery slurry. It should be understood that the standard specific heat capacity c of the qualified battery slurry 标 can be obtained by testing the specific heat capacity of the qualified battery slurry using the testing device of the first aspect.

[0083] In some embodiments, in step S1, the second hollow chamber is also maintained in a vacuum state. This can further improve the heat insulation of the testing device.

[0084] In some embodiments, in step S3, when the specific heat capacity of the solvent in the battery slurry is greater than the specific heat capacity of the powder, when the actually measured specific heat capacity c of the battery slurry is less than the standard specific heat capacity c of the qualified battery slurry 标 it is necessary to add solvent to the battery slurry and then continue kneading. When the actually measured specific heat capacity c of the battery slurry is greater than the standard specific heat capacity c of the qualified battery slurry 标 it is necessary to add powder to the battery slurry and then continue kneading; when the actually measured specific heat capacity c of the battery slurry is equal to the standard specific heat capacity c of the qualified battery slurry 标 the battery slurry is qualified.

[0085] In other embodiments, in step S3, when the specific heat capacity of the solvent in the battery slurry is less than the specific heat capacity of the powder, when the actually measured specific heat capacity c of the battery slurry is greater than the standard specific heat capacity c of the qualified battery slurry 标 it is necessary to add solvent to the battery slurry and then continue kneading. When the actually measured specific heat capacity c of the battery slurry is less than the standard specific heat capacity c of the qualified battery slurry 标 it is necessary to add powder to the battery slurry and then continue kneading; when the actually measured specific heat capacity c of the battery slurry is equal to the standard specific heat capacity c of the qualified battery slurry 标 the battery slurry is qualified.

[0086] The present invention will be described in detail below with reference to the embodiments and the drawings.

[0087] The test object of each of the following examples uses this self-made slurry: Under normal operating conditions, 5 Kg of the negative electrode main material graphite and 0.03 Kg of the conductive agent SP are evenly mixed and placed in a stirring tank. 3.5 kg of water and 0.055 Kg of the thickening agent sodium carboxymethyl cellulose (CMC) are mixed evenly, and then more than 45% of the above solution by total mass is added to the stirring tank. Pre-kneading is carried out for 10 min at a dispersion speed of 8 m / s, and then kneading is carried out for 40 min at a linear speed of 12 m / s to obtain the kneaded slurry 1. Subsequently, the remaining 55% of the solution by mass is added, and dispersion is carried out for 80 min at a linear speed of 18 m / s. At this time, 0.23 Kg of the binder styrene-butadiene polymer (SBR) is added and dispersion is carried out for 30 min at a linear speed of 8 m / s. The slurry production is completed and can be discharged to obtain the finished slurry 2.

[0088] Example 1

[0089] The dispersion state of the kneaded slurry 1 is tested by using the test device of the first aspect and the test method of the second aspect. The specific implementation method is as follows:

[0090] The test device is 5 cm long, 4 cm wide, and 5 cm high. Both the slurry storage box and the cover are designed with double layers. Both the inner and outer layers are made of ordinary polytetrafluoroethylene material, and the middle area is designed to be evacuated to ensure heat insulation. 1000 g of the kneaded slurry 1 is selected and placed in the inner box of the slurry storage box. The temperature of the slurry is at room temperature of 25 °C, ensuring that the kneaded slurry 1 evenly covers the bottom of the box, and then the cover is covered. After covering the cover, the heating rod penetrated through the cover is inserted into the kneaded slurry 1 to contact the slurry, and the thermometer is also inserted into the kneaded slurry 1. Record the initial temperature of the kneaded slurry 1 as T1, and then set the temperature of the heating rod to the constant current heating mode, with the current being 1 A, the resistance wire selected as 100 Ω, and the heating time being 10 min. After the heating is completed, record the final temperature of the kneaded slurry 1 as T2. According to Formula 1, the heat release energy Q can be obtained, and the heat release energy Q is brought into Formula 2 for calculation to obtain the measured specific heat capacity c of the kneaded slurry 1. Compare the measured specific heat capacity c of the kneaded slurry 1 with the standard specific heat capacity c of the qualified kneaded slurry 1 标 to determine whether the kneaded slurry 1 needs to add powder or solvent for further kneading.

[0091] Formula 1: Q = I 2 Rt,

[0092] Formula 2: Q = cm(T2 - T1),

[0093] where c is the measured specific heat capacity of the battery slurry, with the unit of J / Kg·°C,

[0094] Q is the heat release energy, with the unit of J,

[0095] m is the mass of the battery slurry, with the unit of Kg.

[0096] T1 is the initial temperature of the battery slurry, with the unit of °C.

[0097] T2 is the final temperature of the battery slurry, with the unit of °C.

[0098] I is the current used to heat the heating rod, with the unit of A.

[0099] R is the resistance of the heating rod, with the unit of Ω.

[0100] t is the heating time, with the unit of s.

[0101] For the kneaded slurry 1, T1 = 25 °C, T2 = 65 °C, Q = 60000 J, c = 1.5×10 3 J / Kg·°C, the standard specific heat capacity c of the kneaded slurry 1 标 ranges from 2.2×10 3 J / Kg·°C to 2.4×10 3 J / Kg·°C. Since c is less than c 标 , it is determined that water needs to be added to continue kneading.

[0102] Example 2

[0103] The dispersion state of the finished slurry 2 is tested by using the testing device of the first aspect and the testing method of the second aspect. The specific implementation method is as follows:

[0104] The testing device is 5 cm long, 4 cm wide and 5 cm high. Both the slurry storage box and the cover are designed with double layers. The inner and outer layers are made of ordinary polytetrafluoroethylene, and the middle area is designed to be evacuated to ensure heat insulation. Select 1000 g of the finished slurry 2 and place it in the inner box of the slurry storage box. The temperature of the slurry is at room temperature of 25 °C. Ensure that the finished slurry 2 evenly covers the bottom of the box, and then cover the cover. After covering the cover, the heating rod penetrated through the cover is inserted into the finished slurry 2 to contact the slurry, and the thermometer is also inserted into the finished slurry 2 in the same way. Record the initial temperature of the finished slurry 2 as T1, and then set the temperature of the heating rod to the constant current heating mode. The current is 1 A, the resistance wire is selected as 100 Ω, and the heating time is 10 min. After the heating is completed, record the final temperature of the finished slurry 2 as T2. According to Formula 1, the heat release energy Q can be obtained, and the heat release energy Q is brought into Formula 2 for calculation to obtain the measured specific heat capacity c of the finished slurry 2. Compare the measured specific heat capacity c of the finished slurry 2 with the standard specific heat capacity c 标 of the qualified finished slurry 2. By comparing their magnitudes, the quality situation of the finished slurry 2 can be preliminarily judged. If c is higher than the upper limit of the range of c 标 , it means that too much solvent is added, which is likely to cause poor kneading state of the slurry and too large particle size during subsequent discharging, resulting in difficulty in sieving; if c is lower than c 标If it is lower than the lower limit of the range, it means that there is too much powder material, resulting in weak kneading effect, large load on the stirring equipment, high mechanical wear, and prone to cracking and unstable surface density during coating due to too little solvent.

[0105] For the finished slurry 2, T1 = 25 °C, T2 = 45 °C, Q = 60000 J, c = 3×10 3 J / Kg·°C, the standard specific heat capacity c of the finished slurry 2 标 The range is 3.5×10 3 J / Kg·°C - 3.8×10 3 J / Kg·°C, c is lower than the lower limit of the range of c 标 If it is lower than the lower limit of the range, it means that there is too much powder material, resulting in weak kneading effect, large load on the stirring equipment, high mechanical wear, and prone to cracking and unstable surface density during coating due to too little solvent.

[0106] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0107] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A battery slurry dispersion state testing device, characterized in that: It includes a slurry storage box and a cover body covering the top opening of the slurry storage box, the slurry storage box includes an inner box body and an outer box body, the inner box body is arranged inside the outer box body and is interconnected with the outer box body, a closed first hollow chamber is formed between the inner box body and the outer box body, the cover body is arranged on the top of the slurry storage box and is detachably connected to the slurry storage box, a first through hole and a second through hole are arranged on the cover body, a heating rod that can be inserted into the inner box body is arranged in the first through hole, and a thermometer that can be inserted into the inner box body is arranged in the second through hole.

2. The testing device according to claim 1, characterized in that: The outer box body is provided with a first vacuum port communicating with the first hollow chamber.

3. The testing device according to claim 1, characterized in that: The first hollow chamber is located on the side wall and the bottom of the inner box body.

4. The testing device according to claim 1, characterized in that: A bracket is arranged at the bottom of the slurry storage box.

5. The testing device according to claim 1, characterized in that: A liquid level line is arranged on the inner wall of the inner box body.

6. The testing device according to any one of claims 1 to 5, characterized in that: A second hollow chamber is disposed in the cover body.

7. The testing device according to claim 6, characterized in that: The cover body is provided with a second vacuum port communicating with the second hollow chamber.

8. The testing device according to claim 6, characterized in that: The second hollow chamber covers the entire top opening of the slurry storage box.

9. A method for testing the dispersion state of battery slurry, characterized in that: The test device according to any one of claims 1 to 8 is used for testing, and the test method comprises the following steps: S1. Maintain the first hollow chamber in a vacuum state, preferably, maintain the second hollow chamber in a vacuum state; in addition, add a battery slurry with a mass of m into the inner box, and then cover the top of the slurry storage box with the cover, and insert the heating rod and the thermometer into the battery slurry; S2. Record the initial temperature of the battery slurry as T1, then heat the battery slurry through the heating rod, the resistance of the heating rod is R, the current used to heat the heating rod is I, the heating time is t, and after the heating is completed, record the final temperature of the battery slurry as T2, calculate the exothermic energy Q according to formula 1, and then substitute the exothermic energy Q into formula 2 to calculate the measured specific heat capacity c of the battery slurry; Formula 1: Q = I 2 Rt, Formula 2: Q = cm(T2-T1), Where c is the specific heat capacity of the battery slurry, in J / Kg·℃, Q is the heat release energy, the unit is J, m is the mass of battery slurry, in kg, T1 is the initial temperature of the battery slurry, in °C, T2 is the final temperature of the battery slurry, in °C, I is the current used to heat the heating rod, in A, R is the resistance of the heating rod, in Ω, t is the heating time, in seconds; S3. Compare the measured specific heat capacity c of the battery slurry with the standard specific heat capacity c of the qualified battery slurry 标 The comparison is performed to determine the dispersion state of the battery slurry.

10. The testing method according to claim 9, characterized in that: In the case where the specific heat capacity of the solvent of the battery slurry is greater than the specific heat capacity of the powder, when the measured specific heat capacity c of the battery slurry is less than the standard specific heat capacity c of the qualified battery slurry 标 When the specific heat capacity c of the battery slurry is greater than the standard specific heat capacity c of the qualified battery slurry, a solvent needs to be added to the battery slurry, and then the kneading is continued. 标 When the measured specific heat capacity c of the battery slurry is equal to the standard specific heat capacity c of the qualified battery slurry, the powder needs to be added to the battery slurry and then kneading is continued; when the measured specific heat capacity c of the battery slurry is equal to the standard specific heat capacity c of the qualified battery slurry 标 , the battery slurry is qualified.

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