Slurry defoaming method, pole piece, battery monomer, battery pack and electric equipment

Abstract

The invention provides a slurry defoaming method, a pole piece, a battery monomer, a battery pack and electric equipment. The slurry defoaming method is applied to defoaming of battery slurry. Comprising the following steps: stirring slurry in a stirring container through a stirring assembly; in the process of adjusting the vacuum degree of the stirring container, the revolution speed of the stirring assembly is controlled according to the vacuum degree of the stirring container; wherein the absolute value of the vacuum degree of the stirring container is in positive correlation with the revolution speed of the stirring assembly. According to the slurry defoaming method provided by the invention, the defoaming time of the battery slurry can be shortened, and the defoaming efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to slurry defoaming methods, electrode sheets, battery cells, battery packs, and electrical equipment. Background Technology

[0002] During the production of battery slurry, high-speed stirring and other operations can introduce a large amount of air, forming bubbles within the slurry. These bubbles adhere to the substrate surface during the coating process and rupture during subsequent rolling and drying, resulting in insufficient slurry coating in the bubble areas or even exposure of the substrate, ultimately causing the electrode sheets to fail quality tests or be scrapped. Therefore, battery slurry must undergo defoaming treatment before coating.

[0003] In related technologies, defoaming methods for battery slurry suffer from problems such as long defoaming time and low efficiency. Summary of the Invention

[0004] The embodiments of this application provide a slurry defoaming method, an electrode, a battery cell, a battery pack, and an electrical device, which can improve the technical problems of long defoaming time and low efficiency of battery slurry.

[0005] In a first aspect, embodiments of this application provide a method for defoaming a slurry, the method being applied to defoaming a battery slurry; comprising: The slurry in the mixing container is stirred by the stirring component; During the process of adjusting the vacuum level of the stirring container, the revolution speed of the stirring component is controlled according to the vacuum level of the stirring container; The absolute value of the vacuum degree of the stirring container is positively correlated with the revolution speed of the stirring component.

[0006] By adjusting the vacuum level of the mixing container, the pressure difference between the inside and outside of the bubbles in the slurry can be controlled. When the vacuum level increases, the pressure difference between the inside and outside of the bubbles increases, and the escape force is enhanced. The revolution speed of the mixing component is controlled according to the vacuum level. When the vacuum level increases, the revolution speed increases accordingly, which can accelerate the overall convection of the slurry in the container. This makes it easier for bubbles attached to the surface of active materials or conductive agents or wrapped inside the slurry to be turned to the surface of the slurry, thus making it easier for them to come into contact with the vacuum environment and break, thereby improving the defoaming efficiency. Since the dynamic adjustment of the revolution speed only affects the overall flow of the slurry and does not generate local strong shear force, adjusting the revolution speed can not only promote the bubbles to float to the surface of the slurry, but also avoid damaging the morphology of the active material particles or the network structure formed by the conductive agent in the slurry during the mixing process. Therefore, the above solution can not only shorten the defoaming time and improve the defoaming efficiency, but also ensure the mixing quality of the slurry.

[0007] In one embodiment, the process of adjusting the vacuum level of the stirring container includes: Within a first preset time period, the stirring container is evacuated to a first vacuum level; Within a second preset time period, the vacuum in the stirring container is broken down to a second vacuum level; Alternately repeat the vacuuming and vacuum-breaking operations until the preset number of cycles is reached.

[0008] By adopting the above method, the vacuuming step can promote the escape of bubbles, and the vacuum breaking step can promote the rupture of bubbles. Repeatedly cycling the vacuuming and vacuum breaking steps can make defoaming more thorough and improve the defoaming effect.

[0009] In one embodiment, controlling the revolution speed of the stirring assembly based on the vacuum level of the stirring container during the process of adjusting the vacuum level of the stirring container includes: During the first preset time period, while the stirring container is evacuated to a first vacuum level, the revolution speed of the stirring component is gradually increased to a preset speed threshold. During the second preset time period, while the stirring container is being evacuated to a second vacuum level, the stirring component is controlled to stop rotating.

[0010] By adopting the above scheme, the revolution speed of the stirring component can be increased synchronously with the vacuum level during the vacuuming stage. This enhances the escape force of bubbles while gradually accelerating the overall convection of the slurry, continuously agitating the bubbles in the deep slurry to the surface, allowing the bubbles to fully contact the vacuum environment. During the vacuum breaking stage, controlling the revolution component to stop its revolution can prevent air from being mixed in and generating new bubbles due to the disturbance caused by stirring when the pressure rises, or prevent bubbles on the slurry surface from being re-entrained into the slurry. This ensures that the vacuum breaking step only affects the contraction and exposure of bubbles without introducing new bubbles, further improving the defoaming efficiency.

[0011] In one embodiment, the relationship between the vacuum degree x of the stirring container and the revolution speed y satisfies: y = -35x / 90, where the unit of the vacuum degree is kPa and the unit of the revolution speed is rpm.

[0012] By adopting the above scheme, the revolution speed increases proportionally and synchronously with the increase of the absolute value of vacuum. In the process of enhancing convection in response to changes in vacuum, the speed fluctuation will not be too large, and it is easy to automate the control process.

[0013] In one embodiment, the preset rotational speed threshold is less than or equal to 35 rpm, and the first vacuum degree is between -90 kPa and -60 kPa.

[0014] By adopting the above scheme, by setting the maximum value of the preset rotation speed threshold, it is possible to avoid excessive shearing force generated by excessive revolution speed, which could damage the active material particles or conductive agent network structure in the slurry and reduce the impact of the defoaming process on the slurry mixing quality. By limiting the value range of the first vacuum degree to -60KPa to -90KPa, sufficient pressure difference between the inside and outside of the bubbles can be provided during the vacuuming operation to promote bubble escape and avoid excessive negative pressure that could cause slurry splashing or component separation. This improves defoaming efficiency while ensuring the mixing quality of the slurry.

[0015] In one embodiment, the value of the first preset duration ranges from 3 minutes to 6 minutes.

[0016] It provides sufficient time for the expansion, migration, and collapse of bubbles, while avoiding excessive vacuuming time that could affect the stability of the slurry's solid content, thus balancing defoaming effect and production efficiency.

[0017] In one embodiment, the value of the second preset duration ranges from 1 minute to 3 minutes.

[0018] By adopting the above method, the pressure inside the mixing container can be steadily increased, allowing the tiny bubbles inside the slurry to gradually aggregate into larger bubbles as the pressure changes. These larger bubbles are easier to remove in the next vacuuming step. The shorter vacuum breaking time can reduce the probability of air redissolving into the slurry and reduce the introduction of new bubbles during the vacuum breaking process.

[0019] In one embodiment, the second vacuum level ranges from -30 kPa to -10 kPa.

[0020] By adopting the above scheme, the final pressure of the vacuum breaking step is controlled within a range higher than the first vacuum level. This can create a sufficient pressure difference to cause the bubbles to burst, while avoiding the large amount of air entering the mixing container and mixing into the slurry by completely restoring the mixing container to normal pressure. This can reduce the introduction of new bubbles while ensuring the defoaming effect.

[0021] In one embodiment, the preset number of cycles ranges from 3 to 6 times.

[0022] By adopting the above solution, bubbles with different adhesion strengths and depths can be gradually removed, improving the defoaming effect on stubborn bubbles, while avoiding excessive cycles that lead to excessively long production times, thus balancing the thoroughness of defoaming and production efficiency.

[0023] Secondly, embodiments of this application provide an electrode sheet comprising a current collector and a slurry layer, wherein the slurry layer is obtained by a slurry defoaming method as described in any one of the embodiments of the first aspect.

[0024] By adopting the above scheme, since the slurry is treated by the defoaming method described in any of the embodiments of this application, the number of bubbles is reduced, which can reduce vacuum and missed coating caused by residual bubbles during the coating process, and improve the quality and yield of the electrode sheet.

[0025] Thirdly, embodiments of this application provide a battery cell including an electrode as described in any one of the embodiments of the second aspect.

[0026] Fourthly, embodiments of this application provide a battery pack comprising a battery cell as described in any one of the embodiments of the third aspect.

[0027] Fifthly, embodiments of this application provide an electrical device including a battery cell as described in any one of the embodiments of the third aspect or a battery pack as described in any one of the embodiments of the fourth aspect. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a flowchart of a slurry defoaming method provided in an embodiment of this application; Figure 2 This is another flowchart of the slurry defoaming method provided in the embodiments of this application; Figure 3 This is another flowchart of the slurry defoaming method provided in the embodiments of this application; Figure 4 This is another flowchart of the slurry defoaming method provided in the embodiments of this application; Figure 5 This is a schematic diagram of the structure of the electrode provided in an embodiment of this application; Explanation of reference numerals in the attached figures: 500, electrode; 501, current collector; 502, slurry layer. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0031] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0032] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0033] In related technologies, there are two main methods for defoaming battery slurry: one is to evacuate the slurry container to a certain vacuum level and maintain the container at that vacuum level for a period of time, during which a rotating agitator continuously stirs at a low speed; the other is to break the vacuum in the container to atmospheric pressure after the above-mentioned negative pressure stirring operation, and achieve defoaming through a cycle of evacuation and breaking of the vacuum. However, the defoaming time required by these two methods is usually 1 to 2 hours, which has the problems of long defoaming time, low efficiency and incomplete defoaming.

[0034] Based on this, this application provides a slurry defoaming method, an electrode, and a battery. These will be described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments.

[0035] refer to Figure 1 This application provides a method for defoaming a slurry, which is applied to the defoaming of battery slurry; including: Step 101: Stir the slurry in the mixing container using the stirring assembly; Step 102: During the process of adjusting the vacuum level of the mixing container, control the revolution speed of the mixing component according to the vacuum level of the mixing container; The absolute value of the vacuum degree of the stirring container is positively correlated with the revolution speed of the stirring component.

[0036] In this embodiment, battery slurry refers to a paste-like material used to prepare the positive and negative electrodes of a battery. It may include components such as active materials, conductive agents, binders, and / or solvents. The battery slurry is adhered to a metal current collector through processes such as coating, drying, and rolling to form the positive and negative electrode sheets of the battery. The slurry mentioned in this embodiment can be either a positive electrode slurry or a negative electrode slurry; this application does not limit the specific type and composition of the slurry. For example, the battery may be a lithium-ion battery.

[0037] A mixing container can be a vessel used for mixing and / or dispersing the components of a battery slurry. The mixing container may be equipped with a stirring paddle and a backflow mechanism to promote uniform mixing of the components. For example, the mixing container may be a planetary mixer. The mixing assembly refers to the moving parts in the mixing equipment that directly act on the slurry, and may include a drive unit, a transmission shaft, and different types of blades. The blades may include rotating blades and revolving blades. A rotating blade is a blade that rotates around its own central axis, while a revolving blade is a blade that rotates around the central axis of the equipment, not its own central axis. These blades are used to drive the slurry within the container in a circular motion, improving the uniformity of the material. For example, the blades of a rotating blade may be blade-type, dispersion disc-type, or screw-type, while the blades of a revolving blade may be frame-type, anchor-type, or planetary-type. This application does not limit the specific type and structure of the mixing container.

[0038] It is understandable that vacuum is usually expressed as a negative value, representing a relative pressure based on standard atmospheric pressure. The higher the vacuum level inside the stirred container, the lower the pressure, and correspondingly, the larger the absolute value of the negative value. Therefore, the absolute value of the vacuum level in the stirred container is positively correlated with the rotational speed of the stirring assembly; that is, the rotational speed of the stirring assembly increases as the vacuum level increases. The vacuum level can be adjusted by using a vacuum pump to evacuate the stirred container.

[0039] In the embodiments of this application, the adjustment of vacuum degree and the control of the rotation speed of stirring component can be achieved by controllers such as PLC, microcontroller or industrial control computer.

[0040] By adjusting the vacuum level of the mixing container, the pressure difference between the inside and outside of the bubbles in the slurry can be controlled. When the vacuum level increases, the pressure difference between the inside and outside of the bubbles increases, and the escape force is enhanced. The revolution speed of the mixing component is controlled according to the vacuum level. When the vacuum level increases, the revolution speed increases accordingly, which can accelerate the overall convection of the slurry in the container. This makes it easier for bubbles attached to the surface of active materials or conductive agents or wrapped inside the slurry to be turned to the surface of the slurry, thus making it easier for them to come into contact with the vacuum environment and break, thereby improving the defoaming efficiency. Since the dynamic adjustment of the revolution speed only affects the overall flow of the slurry and does not generate local strong shear force, adjusting the revolution speed can not only promote the bubbles to float to the surface of the slurry, but also avoid damaging the morphology of the active material particles or the network structure formed by the conductive agent in the slurry during the mixing process. Therefore, the above solution can not only shorten the defoaming time and improve the defoaming efficiency, but also ensure the mixing quality of the slurry.

[0041] refer to Figure 2 In one embodiment, the process of adjusting the vacuum level of the stirring vessel includes: Step 201: Within the first preset time period, evacuate the stirring container to the first vacuum level; Step 202: Within the second preset time period, break the vacuum in the stirring container to the second vacuum level; Step 203: Alternately repeat the vacuuming and vacuum breaking operations until the preset number of cycles is reached.

[0042] In this context, "vacuum breaking" refers to the operation of introducing gas into the stirring container to reduce the vacuum level. The first preset duration is a fixed time, predetermined, for a single vacuuming operation to a first vacuum level. Within this first preset duration, the absolute value of the vacuum level in the stirring container increases with time. Correspondingly, the second preset duration is a fixed time, predetermined, for a single vacuum breaking operation to a second vacuum level. Within this second preset duration, the absolute value of the vacuum level in the stirring container decreases with time. The increase or decrease of the absolute value of the vacuum level over time can be linear or non-linear. The preset number of cycles is the total number of repetitions of the combined vacuuming and vacuum breaking operations. When the preset number of cycles is reached, the vacuuming and vacuum breaking operations are stopped. In this embodiment, the defoaming duration is the sum of the time elapsed during the alternating vacuuming and vacuum breaking steps.

[0043] By adopting the above method, the vacuuming step can promote the escape of bubbles, and the vacuum breaking step can promote the rupture of bubbles. Repeatedly cycling the vacuuming and vacuum breaking steps can make defoaming more thorough and improve the defoaming effect.

[0044] refer to Figure 3 In one embodiment, during the process of adjusting the vacuum level of the stirring container, controlling the revolution speed of the stirring assembly based on the vacuum level of the stirring container includes: Step 301: During the first preset time period, while evacuating the stirring container to the first vacuum level, the revolution speed of the stirring component is gradually increased to the preset speed threshold. Step 302: During the process of breaking the vacuum in the stirring container to the second vacuum level within the second preset time period, control the stirring component to stop rotating.

[0045] In the vacuuming step, increasing the rotation speed of the stirring component is to promote the rise of air bubbles, while in the vacuum breaking step, controlling the stirring component to stop rotating is to reduce the introduction of external air bubbles during the vacuum breaking process.

[0046] By adopting the above scheme, the revolution speed of the stirring component can be increased synchronously with the vacuum level during the vacuuming stage. This enhances the escape force of bubbles while gradually accelerating the overall convection of the slurry, continuously agitating the bubbles in the deep slurry to the surface, allowing the bubbles to fully contact the vacuum environment. During the vacuum breaking stage, controlling the revolution component to stop its revolution can prevent air from being mixed in and generating new bubbles due to the disturbance caused by stirring when the pressure rises, or prevent bubbles on the slurry surface from being re-entrained into the slurry. This ensures that the vacuum breaking step only affects the contraction and exposure of bubbles without introducing new bubbles, further improving the defoaming efficiency.

[0047] In one embodiment, the relationship between the vacuum degree x of the stirring vessel and the revolution speed y satisfies: y = -35x / 90, where the unit of vacuum degree is kPa and the unit of revolution speed is rpm (revolutions per minute).

[0048] During the vacuuming process, the vacuum level x of the stirring container can be collected in real time by a sensor, and the target rotation speed y can be calculated using the formula mentioned above to achieve synchronous control of the two.

[0049] By adopting the above scheme, the revolution speed increases proportionally and synchronously with the increase of the absolute value of vacuum. In the process of enhancing convection in response to changes in vacuum, the speed fluctuation will not be too large, and it is easy to automate the control process.

[0050] In one embodiment, the preset rotation speed threshold is less than or equal to 35 rpm, and the first vacuum degree is between -60 kPa and -90 kPa.

[0051] For example, the preset speed threshold can be a value such as 10 rpm, 12 rpm, 15 rpm, 20 rpm or 35 rpm, and the first vacuum degree can be a value such as -60 kPa, -65 kPa, -70 kPa, -78 kPa, -85 kPa, -90 kPa.

[0052] By adopting the above scheme, by setting the maximum value of the preset rotation speed threshold, it is possible to avoid excessive shearing force generated by excessive revolution speed, which could damage the active material particles or conductive agent network structure in the slurry and reduce the impact of the defoaming process on the slurry mixing quality. By limiting the value range of the first vacuum degree to -60KPa to -90KPa, sufficient pressure difference between the inside and outside of the bubbles can be provided during the vacuuming operation to promote bubble escape and avoid excessive negative pressure that could cause slurry splashing or component separation. This improves defoaming efficiency while ensuring the mixing quality of the slurry.

[0053] In one embodiment, the preset rotation speed threshold and the value of the first vacuum degree can be adjusted according to the specific type of battery slurry.

[0054] For example, when the battery slurry is a low-viscosity slurry such as negative electrode graphite slurry, the slurry has strong fluidity and low resistance to bubble escape. The preset speed threshold and the first vacuum degree can be appropriately reduced. Reducing the preset speed threshold can reduce the splashing of the slurry during the stirring process and reduce the new bubbles introduced by stirring. Reducing the first vacuum degree can shorten the time required for the vacuuming process while meeting the defoaming requirements of the slurry, thereby improving the defoaming efficiency and reducing the energy consumption of the equipment.

[0055] For example, when the battery slurry is a high-viscosity, high-solids slurry such as a ternary high-nickel slurry, the air bubbles formed by the air entrained during the slurry preparation process are usually small. These bubbles have a small surface area, weak buoyancy, poor slurry fluidity, and high bubble migration resistance. By increasing the vacuum level, the internal and external pressure difference of the micro bubbles can be effectively increased, causing the micro bubbles to merge into larger bubbles, which then break or float. Increasing the revolution speed can enhance the overall convection of the slurry, allowing the slurry in each area of ​​the stirring container to participate in the defoaming process, reducing the residue of local bubbles, and improving the defoaming efficiency.

[0056] In one embodiment, the first preset duration ranges from 3 minutes to 6 minutes.

[0057] Understandably, the first preset time can be adjusted according to the type and viscosity of the slurry. When the slurry viscosity is low or the solid content is low, the bubbles escape faster during the vacuuming step, so the first preset time can be shortened to shorten the time of the entire defoaming process and improve production efficiency. When the slurry viscosity is high and the solid content is high, the first preset time can be extended to make defoaming more thorough.

[0058] For example, the first preset duration can be 3 minutes, 3.5 minutes, 5 minutes, 5.5 minutes, or 6 minutes, etc.

[0059] The above approach provides sufficient time for the expansion, migration, and rupture of bubbles, while avoiding excessive vacuuming time that could affect the stability of the slurry's solid content, thus balancing defoaming effect and production efficiency.

[0060] In one embodiment, the second preset duration ranges from 1 minute to 3 minutes.

[0061] The second preset time can also be adjusted according to the type and viscosity of the slurry. Since low-viscosity slurries can be more thoroughly defoamed during the vacuuming process, rapid vacuum breaking is less likely to cause severe splashing and can shorten defoaming time. Therefore, for low-viscosity slurries, the second preset time can be appropriately shortened to reduce defoaming time and improve production efficiency. However, for high-viscosity, high-solids-content slurries, if the vacuum breaking speed is too fast, it will impact the slurry, affecting its uniformity. Furthermore, the incoming air is easily trapped by the slurry, forming new bubbles and leading to incomplete defoaming. Therefore, for high-viscosity slurries, the second preset time can be extended, allowing air to enter the mixing container relatively slowly, resulting in more thorough defoaming.

[0062] For example, the second preset duration can be 1 minute, 1 minute 15 seconds, 1.5 minutes, 2 minutes, 3 minutes, etc.

[0063] By adopting the above method, the pressure inside the mixing container can be steadily increased, allowing the tiny bubbles inside the slurry to gradually aggregate into larger bubbles as the pressure changes. These larger bubbles are easier to remove in the next vacuuming step. The shorter vacuum breaking time can reduce the probability of air redissolving into the slurry and reduce the introduction of new bubbles during the vacuum breaking process.

[0064] In one embodiment, the second vacuum level ranges from -30 kPa to -10 kPa.

[0065] For example, the second vacuum level can be -30 kPa, -25 kPa, -20 kPa, -16 kPa, -10 kPa, etc.

[0066] By adopting the above scheme, the final pressure of the vacuum breaking step is controlled within a range higher than the first vacuum level. This can create a sufficient pressure difference to cause the bubbles to burst, while avoiding the large amount of air entering the mixing container and mixing into the slurry by completely restoring the mixing container to normal pressure. This can reduce the introduction of new bubbles while ensuring the defoaming effect.

[0067] In one embodiment, the preset number of cycles ranges from 3 to 6 times.

[0068] By adopting the above solution, bubbles with different adhesion strengths and depths can be gradually removed, improving the defoaming effect on stubborn bubbles, while avoiding excessive cycles that lead to excessively long production times, thus balancing the thoroughness of defoaming and production efficiency.

[0069] In one embodiment, the stirring assembly includes a revolution blade with a spiral structure on the side of the revolution blade facing the bottom of the stirring container.

[0070] By adopting the above scheme, the spiral structure of the orbiting paddle can generate an upward thrust during its revolution, which will turn the slurry at the bottom of the mixing container upward and form a more thorough convection circulation with the upper slurry. This avoids the presence of air bubbles in the bottom slurry due to inadequate mixing. The pushing effect of the spiral structure is relatively gentle and will not generate strong local shear force. While enhancing the overall fluidity of the slurry, it can also protect the active substances and conductive agent network structure in the slurry.

[0071] The embodiments of this application are further illustrated below with reference to specific examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application.

[0072] Example 1 refer to Figure 4 The defoaming method for slurry provided in Example 1 includes: Step 401: Evacuate the cylinder of the mixing tank within 5 minutes to achieve and maintain a vacuum level of -90 kPa. During the evacuation process, adjust the rotation speed of the orbiting paddle so that the relationship between the vacuum level x and the orbiting speed y of the mixing container satisfies: y = -35x / 90.

[0073] The unit for vacuum is kPa, and the unit for revolution speed is rpm. When the vacuum of the cylinder reaches -90 kPa, the revolution speed reaches 35 rpm.

[0074] Step 402: Control the orbiting propeller to stop orbiting and break the vacuum in the cylinder within 1 minute to achieve a vacuum level of -20 kPa.

[0075] Step 403: Repeat steps 401 to 402 five times alternately.

[0076] The defoaming time in Example 1 is approximately 30 minutes.

[0077] Comparative Example 1 The defoaming method for the slurry in Comparative Example 1 includes: Step 501: Evacuate the cylinder body of the mixing tank. When the vacuum degree reaches -90KPa, stop evacuating the tank body to maintain a negative pressure state. Step 502: Control the propeller to revolve at a speed of 15 rpm for 1.5 hours, and then restore the cylinder to normal pressure.

[0078] The defoaming time for Comparative Example 1 was approximately 90 minutes.

[0079] Comparative Example 2 The defoaming method for the slurry in Comparative Example 2 includes: Step 601: Evacuate the cylinder body of the mixing tank. When the vacuum degree reaches -90KPa, stop evacuating the tank body to maintain a negative pressure state. Step 602: Under negative pressure, control the orbiting propeller to orbit at a speed of 15 rpm for 10 minutes; Step 603: Devastate the cylinder to atmospheric pressure.

[0080] Step 604, repeat steps 601 to 603 5 times.

[0081] The defoaming time for Comparative Example 2 was approximately 60 minutes.

[0082] The same slurry was defoamed using the above examples and comparative examples, and then coated to form electrode sheets of the same specifications. During the coating stage, the electrode sheet area was found to be greater than 1 mm². 2 The number of bubble regions was determined to obtain the number of bubble regions per 1000m of electrode sheet per unit width. Then, a die-cutting and marking machine was used to mark the areas larger than 1mm² on the electrode sheet. 2 The number of bubble regions was marked to obtain the number of bubble regions on every 500 electrode sheets. The detection and marking results are shown in Table 1.

[0083] Table 1

[0084] As can be seen from the data in Table 1, the number of bubble regions in the electrode sheets made from the slurry treated by the slurry defoaming method of Example 1 is less than the number of bubble regions in the electrode sheets made from the slurry treated by the methods of Comparative Examples 1 and 2. The slurry defoaming method provided in this application not only has a short defoaming time but also a good defoaming effect, which can effectively reduce the number of bubble regions on the electrode sheets and improve the yield of the electrode sheets.

[0085] refer to Figure 5 Secondly, embodiments of this application provide an electrode 500, including a current collector 501 and a slurry layer 502, wherein the slurry layer 502 is obtained by a slurry defoaming method as described in any one of the embodiments of the first aspect.

[0086] The electrode provided in this application embodiment can be a positive electrode or a negative electrode. The specific specifications of the electrode can be set according to actual needs, and this application embodiment does not limit them.

[0087] By adopting the above scheme, since the slurry is treated by the defoaming method described in any of the embodiments of this application, the number of bubbles is reduced, which can reduce vacuum and missed coating caused by residual bubbles during the coating process, and improve the quality and yield of the electrode sheet.

[0088] Thirdly, embodiments of this application provide a battery cell including an electrode as described in any one of the examples in the second aspect.

[0089] The battery cell includes an electrode assembly. The positive and negative electrode sheets, along with the separator, can be formed into the electrode assembly by winding and / or stacking. The slurry for the positive and / or negative electrode sheets is defoamed using the defoaming methods described in the above embodiments.

[0090] Fourthly, embodiments of this application provide a battery pack comprising a battery cell as described in any one of the embodiments of the third aspect.

[0091] The battery pack of this application embodiment may include one or more battery cells, which can be connected in series and / or in parallel to form a battery module. The battery pack may include components such as a housing, battery module, battery management system and heat dissipation system.

[0092] The battery pack has all the beneficial effects of the aforementioned individual battery cells, which will not be repeated here.

[0093] Fifthly, embodiments of this application provide an electrical device including a battery cell as described in any one of the embodiments of the third aspect or a battery pack as described in any one of the embodiments of the fourth aspect.

[0094] In some embodiments of this application, the electrical equipment can be one of the following: smart wearable devices, mobile communication devices, transportation equipment, and power tools.

[0095] The electrical device has all the beneficial effects of the aforementioned battery pack, which will not be elaborated further in this application.

[0096] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for defoaming slurry, characterized in that, include: The slurry in the mixing container is stirred by the stirring component; During the process of adjusting the vacuum level of the stirring container, the revolution speed of the stirring component is controlled according to the vacuum level of the stirring container; The absolute value of the vacuum degree of the stirring container is positively correlated with the revolution speed of the stirring component.

2. The slurry defoaming method according to claim 1, characterized in that, The process of adjusting the vacuum level of the stirring container includes: Within a first preset time period, the stirring container is evacuated to a first vacuum level; Within a second preset time period, the vacuum in the stirring container is broken down to a second vacuum level; Alternately repeat the vacuuming and vacuum-breaking operations until the preset number of cycles is reached.

3. The slurry defoaming method according to claim 2, characterized in that, The process of adjusting the vacuum level of the stirring container, and controlling the revolution speed of the stirring assembly based on the vacuum level of the stirring container, includes: During the first preset time period, while the stirring container is evacuated to a first vacuum level, the revolution speed of the stirring component is gradually increased to a preset speed threshold. During the second preset time period, while the stirring container is being evacuated to a second vacuum level, the stirring component is controlled to stop rotating.

4. The method for defoaming slurry according to any one of claims 1 to 3, characterized in that, The relationship between the vacuum degree x of the stirring container and the revolution speed y satisfies: y = -35x / 90, where the unit of the vacuum degree is kPa and the unit of the revolution speed is rpm.

5. The slurry defoaming method according to claim 3, characterized in that, The preset speed threshold value ranges from less than or equal to 35 rpm, and the first vacuum degree ranges from -90 kPa to -60 kPa.

6. The slurry defoaming method according to claim 3, characterized in that, The first preset duration ranges from 3 minutes to 6 minutes.

7. The slurry defoaming method according to claim 3, characterized in that, The second preset duration ranges from 1 minute to 3 minutes.

8. The slurry defoaming method according to claim 3, characterized in that, The second vacuum level ranges from -30 kPa to -10 kPa.

9. The slurry defoaming method according to claim 3, characterized in that, The preset number of cycles ranges from 3 to 6.

10. An electrode sheet (500), characterized in that, It includes a current collector (501) and a slurry layer (502), wherein the slurry layer (502) is obtained by the slurry defoaming method as described in any one of claims 1 to 9.

11. A single battery cell, characterized in that, Includes the electrode (500) as described in claim 10.

12. A battery pack, characterized in that, Includes the battery cell as described in claim 11.

13. An electrical appliance, characterized in that, Includes the battery pack as described in claim 12.

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