A method for storing and using electrode paste.

Abstract

This invention provides a method for storing and using electrode slurry, belonging to the field of secondary battery technology. The electrode slurry storage method includes the following steps: freezing a first liquid electrode slurry to obtain a solid electrode slurry, and then freezing and storing the solid electrode slurry. The electrode slurry storage method of this invention, by using frozen storage for the finished electrode slurry, can ensure that the slurry does not settle during storage and transportation, greatly extending the storage time of the electrode slurry.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, specifically relating to a method for storing and using electrode slurry. Background Technology

[0002] In the manufacturing process of lithium-ion batteries, the quality of the positive and negative electrode slurries directly affects battery performance. In actual production, to maximize efficiency, more slurry than is needed for coating is produced to ensure the coating process doesn't experience material shortages. Therefore, the storage of the electrode slurry must be considered. If the electrode slurry is stored for too long, abnormal sedimentation can occur. To prevent excessively rapid sedimentation, current methods involve adding a stirring function to the slurry buffer tank to keep the electrode slurry in a flowing state.

[0003] However, adding a stirring function to the slurry buffer tank can only slow down the settling rate of the electrode slurry, but cannot fundamentally prevent settling. For example, after slow stirring in the slurry buffer tank for 48-72 hours, the electrode slurry will show obvious settling. Therefore, it is necessary to design a method for storing electrode slurry to extend the storage time and prevent settling during storage. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art. To this end, embodiments of the present invention provide a method for storing and using electrode slurry.

[0005] The electrode slurry storage method of this invention includes the following steps: freezing a first liquid electrode slurry to obtain a solid electrode slurry, and then freezing and storing the solid electrode slurry.

[0006] The advantages and technical effects of the electrode paste storage method of this invention are as follows:

[0007] The electrode slurry storage method of this invention adopts a frozen storage method for the finished electrode slurry, which can ensure that the slurry will not settle during storage and transportation, and greatly extend the storage time of the electrode slurry.

[0008] Preferably, in some embodiments, the freezing process is carried out at a temperature below -5°C.

[0009] More preferably, in some embodiments, the freezing process is performed at a temperature of -20 to -10°C.

[0010] Preferably, in some embodiments, the freezing process is performed under vacuum conditions.

[0011] More preferably, in some embodiments, the freezing process is performed under vacuum conditions of -60 kPa or less.

[0012] More preferably, in some embodiments, the freezing process is carried out under vacuum conditions of -120 to -60 kPa.

[0013] Preferably, in some embodiments, the following steps are further included between the freezing process and the cryogenic storage: cutting the solid electrode slurry, and / or vacuum packaging the solid electrode slurry.

[0014] More preferably, in some embodiments, the solid electrode slurry is first cut, and then the cut solid electrode slurry is vacuum packaged.

[0015] Preferably, in some embodiments, the frozen storage is carried out at a temperature below -5°C.

[0016] More preferably, in some embodiments, the frozen storage is carried out at a temperature of -15 to -5°C.

[0017] In addition, this embodiment of the invention also provides a method for taking electrode slurry, including the following steps: thawing the solid electrode slurry stored by the storage method of this embodiment of the invention to obtain a second liquid electrode slurry.

[0018] The advantages and technical effects of the electrode paste handling method of this invention are as follows:

[0019] The electrode slurry handling method of this embodiment is designed specifically to adapt to the electrode slurry storage method of this embodiment. No sedimentation was found in the electrode slurry obtained after thawing.

[0020] Preferably, in some embodiments, the thawing process is carried out at a temperature of 30°C or higher.

[0021] More preferably, in some embodiments, the thawing process is carried out at a temperature of 30-50°C.

[0022] Preferably, in some embodiments, the thawing process is carried out under stirring conditions of less than 40 rpm.

[0023] More preferably, in some embodiments, the thawing process is carried out under stirring conditions of 20-30 rpm.

[0024] Preferably, in some embodiments, the thawing process further includes a homogenization process: stirring the second liquid electrode slurry under vacuum conditions.

[0025] More preferably, in some embodiments, the second liquid electrode slurry is stirred under vacuum conditions of -60 kPa or less for at least 20 minutes.

[0026] Further, in some embodiments, the second liquid electrode slurry is stirred for 20-40 minutes under a vacuum of -120 to -60 kPa. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the storage and retrieval methods of the electrode slurry in Examples 1-4. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] This invention provides a method for storing electrode slurry, comprising the following steps: freezing a first liquid electrode slurry to obtain a solid electrode slurry, and then freezing and storing the solid electrode slurry.

[0030] The electrode slurry storage method of this invention adopts a frozen storage method for the finished electrode slurry, which can ensure that the slurry will not settle during storage and transportation, and greatly extend the storage time of the electrode slurry.

[0031] The storage method for the electrode paste in this embodiment of the invention does not particularly limit the temperature of the freezing treatment, as long as it allows the electrode paste to change from a liquid to a solid state. Specifically, the temperature can be determined based on the freezing point of the solvent used in the electrode paste. Preferably, in some embodiments, the freezing treatment is performed at a temperature below -5°C. More preferably, in some embodiments, the freezing treatment is performed at a temperature of -20 to -10°C, such as -20°C, -19°C, -18°C, -17°C, -16°C, -15°C, -14°C, -13°C, -12°C, -11°C, -10°C, etc., and this temperature range is basically suitable for electrode pastes commonly used in related technologies.

[0032] In some embodiments, the freezing process is performed under vacuum conditions. Under vacuum conditions, the freezing point of the liquid is raised, making it easier for the electrode slurry to solidify. Preferably, the freezing process is performed under vacuum conditions below -60 kPa. More preferably, the freezing process is performed under vacuum conditions of -120 to -60 kPa, such as -120 kPa, -110 kPa, -100 kPa, -90 kPa, -80 kPa, -70 kPa, and -60 kPa. When the vacuum is too low, the requirements for the vacuum equipment are higher, which is not conducive to reducing equipment costs. When the vacuum is too high, it is not conducive to raising the freezing point of the electrode slurry, requiring a lower temperature for freezing, which is not conducive to reducing energy consumption.

[0033] The electrode slurry storage method of this invention does not have a particular limitation on the freezing time, as long as the electrode slurry can be transformed from a liquid to a solid state. Specifically, the time can be set according to the set temperature and vacuum level.

[0034] Preferably, in some embodiments, the following steps are further included between the freezing treatment and the cryogenic storage: cutting the solid electrode slurry, and / or vacuum packaging the solid electrode slurry. Cutting the solid electrode slurry makes it easier to package and transport, and there is no particular limitation on the size of the cut solid electrode slurry. Vacuum packaging helps protect the solid electrode slurry from contact with the outside environment, preventing deterioration due to contact with external moisture. More preferably, in some embodiments, the solid electrode slurry is first cut, and then the cut solid electrode slurry is vacuum packaged.

[0035] The electrode slurry storage method of this invention does not particularly limit the freezing storage temperature, as long as the solid electrode slurry remains solid during storage. Preferably, in some embodiments, the freezing storage is carried out at a temperature below -5°C. More preferably, the freezing storage is carried out at a temperature of -15 to -5°C, such as -15°C, -14°C, -13°C, -12°C, -11°C, -10°C, -9°C, -8°C, -7°C, -6°C, -5°C, etc. When the temperature is too low, the anti-settling effect will not be significantly improved; instead, it will increase energy consumption, which is not conducive to cost reduction and efficiency improvement. When the temperature is too high, the freezing treatment requires too long a time, which is not conducive to preventing electrode slurry sedimentation during the freezing treatment.

[0036] In addition, this embodiment of the invention also provides a method for taking electrode slurry, including the following steps: thawing the solid electrode slurry stored by the storage method of this embodiment of the invention to obtain a second liquid electrode slurry.

[0037] After thawing, the frozen solid electrode slurry can be used to obtain the second liquid electrode slurry. No sedimentation was found, and it can be used in the subsequent coating process.

[0038] Preferably, in some embodiments, the thawing process is performed at a temperature above 30°C. This temperature condition is more conducive to rapid thawing and improves production efficiency. Preferably, the thawing process is performed at a temperature of 30-50°C, such as 30°C, 33°C, 36°C, 40°C, 43°C, 46°C, or 50°C. When the temperature is too low, the thawing time is too long, which is not conducive to improving production efficiency. When the temperature is too high, further cooling of the electrode slurry is required before subsequent coating work, which is not conducive to reducing electrode slurry settling and also not conducive to improving work efficiency.

[0039] Preferably, in some embodiments, the thawing process is performed under stirring conditions below 40 rpm. Low-speed stirring helps the slurry thaw quickly while minimizing the introduction of outside air. More preferably, the thawing process is performed under stirring conditions of 20-30 rpm, such as 20 rpm, 22 rpm, 24 rpm, 26 rpm, 28 rpm, and 30 rpm. When the stirring speed is too low, it is not conducive to the rapid thawing of the solid slurry. When the stirring speed is too high, it is not conducive to the slurry being in a relatively stable state, and air is easily mixed into the slurry during the impact and collision with the stirring paddle.

[0040] Preferably, in some embodiments, the thawing process further includes a homogenization process: stirring the second liquid electrode slurry under vacuum conditions. During the stirring process, external air is inevitably introduced into the second liquid electrode slurry, which can cause air bubbles and pits in the appearance of the slurry in subsequent coating processes. Therefore, vacuuming is preferably used during stirring to reduce air bubbles in the slurry, thereby reducing appearance abnormalities in subsequent coating processes. Furthermore, the homogenization process also facilitates the mixing of the second liquid electrode slurry with other slurries that have not undergone frozen storage. After mixing, the properties of the finished slurry tend to be more consistent, reducing subtle differences in viscosity, temperature, and solid content. Vacuuming helps reduce air bubbles generated during mixing, further reducing appearance abnormalities in subsequent coating processes.

[0041] More preferably, the second liquid electrode slurry is stirred under a vacuum condition of -60 kPa or lower for at least 20 minutes. This vacuum condition facilitates thorough mixing of the second liquid electrode slurry with other slurries that have not undergone cryogenic storage, reducing air bubbles generated during mixing and thus minimizing appearance abnormalities in subsequent coating processes. Even more preferably, the second liquid electrode slurry is stirred under a vacuum condition of -120 to -60 kPa, such as -120 kPa, -110 kPa, -100 kPa, -90 kPa, -80 kPa, -70 kPa, or -60 kPa, for 20-40 minutes, such as 20 minutes, 25 minutes, 30 minutes, 35 minutes, or 40 minutes.

[0042] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0043] Example 1

[0044] Under normal operating conditions, the positive electrode material (NCM811), conductive agent (acetylene black), and binder (PVDF) are mixed evenly at a mass ratio of 95:3:2, and then dispersed in an NMP solution and stirred evenly to obtain a lithium battery electrode slurry. The overall solid content of the electrode slurry is 64% ± 3%, and the total mass of the electrode slurry is 100 kg. Figure 1 As shown, the prepared electrode slurry is transferred to a freezing tank via a conveying pipeline. The temperature in the freezing tank is set to -15℃, the vacuum degree to -90KPa, and the cooling time to 2 hours, at which point the electrode slurry is completely solid. The solid electrode slurry is then dispersed into cubes of approximately 5cm*5cm*5cm in a cutting machine. The cut electrode slurry is then vacuum-packed on a coating machine and subsequently transferred to a -10℃ storage room. When needed, the solid electrode slurry is unpacked and placed in a thawing tank. The tank temperature is set to 40℃, the rotation speed is 25rpm, and stirring is performed for 2 hours until the electrode slurry is completely thawed. Finally, the electrode slurry is transferred to a finished product tank, a -90KPa vacuum is applied, the rotation speed is 25rpm, and stirring is performed for 30 minutes before being discharged.

[0045] Example 2

[0046] Under normal operating conditions, the positive electrode material (NCM811), conductive agent (acetylene black), and binder (PVDF) are mixed evenly at a mass ratio of 95:3:2, and then dispersed in an NMP solution and stirred evenly to obtain a lithium battery electrode slurry. The overall solid content of the electrode slurry is 64% ± 3%, and the total mass of the electrode slurry is 100 kg. Figure 1As shown, the prepared electrode slurry is transferred to a freezing tank via a conveying pipeline. The temperature in the freezing tank is set to -20℃, the vacuum degree to -60KPa, and the cooling time to 2 hours, at which point the electrode slurry is completely solid. The solid electrode slurry is then dispersed into cubes of approximately 5cm*5cm*5cm in a cutting machine. The cut electrode slurry is then vacuum-packed on a coating machine and transferred to a -15℃ storage room. When needed, the solid electrode slurry is unpacked and placed in a thawing tank. The tank temperature is set to 40℃, the rotation speed is 25rpm, and stirring is performed for 2 hours until the electrode slurry is completely thawed. Finally, the electrode slurry is transferred to a finished product tank, a -90KPa vacuum is applied, the rotation speed is 25rpm, and stirring is performed for 30 minutes before being discharged.

[0047] Example 3

[0048] Under normal operating conditions, the negative electrode material (graphite), conductive agent (SP), binder (MAC350HC), and dispersant (JSR-104A) are mixed uniformly at a mass ratio of 96:1:1.4:1.6, and then dispersed in pure water and stirred evenly to obtain a lithium battery electrode slurry with a solid content of 53% ± 3%, and a total mass of 100 kg. Figure 1 As shown, the prepared electrode slurry is transferred to a freezing tank via a conveying pipeline. The temperature in the freezing tank is set to -10℃, the vacuum degree to -90KPa, and the cooling time to 2 hours, at which point the electrode slurry is completely solid. The solid electrode slurry is then dispersed into cubes of approximately 5cm*5cm*5cm in a cutting machine. The cut electrode slurry is then vacuum-packed on a coating machine and transferred to a -5℃ storage room. When needed, the solid electrode slurry is unpacked and placed in a thawing tank. The tank temperature is set to 35℃, the rotation speed is 25rpm, and stirring is performed for 2 hours until the electrode slurry is completely thawed. Finally, the electrode slurry is transferred to a finished product tank, a -90KPa vacuum is applied, the rotation speed is 25rpm, and stirring is performed for 30 minutes before being discharged.

[0049] Example 4

[0050] Under normal operating conditions, the negative electrode material (graphite), conductive agent (SP), binder (MAC350HC), and dispersant (JSR-104A) are mixed uniformly at a mass ratio of 96:1:1.4:1.6, and then dispersed in pure water and stirred evenly to obtain a lithium battery electrode slurry with a solid content of 53% ± 3%, and a total mass of 100 kg. Figure 1As shown, the prepared electrode slurry is transferred to a freezing tank via a conveying pipeline. The temperature in the freezing tank is set to -10℃, the vacuum degree to -120KPa, and the cooling time to 1.5h. At this point, the electrode slurry is completely solid. The solid electrode slurry is then dispersed into cubes of approximately 5cm*5cm*5cm in a cutting machine. The cut electrode slurry is then vacuum-packed on a coating machine and transferred to a -5℃ storage room. When needed, the solid electrode slurry is unpacked and placed in a thawing tank. The tank temperature is set to 35℃, the rotation speed is 25rpm, and stirring is performed for 2h until the electrode slurry is completely thawed. Finally, the electrode slurry is transferred to a finished product tank, a -90KPa vacuum is applied, the rotation speed is 25rpm, and stirring is performed for 30min before being discharged.

[0051] Example 5

[0052] Under normal operating conditions, the positive electrode material (NCM811), conductive agent (acetylene black), and binder (PVDF) are mixed evenly at a mass ratio of 95:3:2, and then dispersed in an NMP solution and stirred evenly to obtain a lithium battery electrode slurry. The overall solid content of the electrode slurry is 64% ± 3%, and the total mass of the electrode slurry is 100 kg. The finished electrode slurry is transferred to a freezing tank through a conveying pipeline. The temperature in the freezing tank is set to -15℃, the vacuum degree is -90 kPa, and the cooling time is 2 hours. At this time, the electrode slurry is completely solid. The solid electrode slurry is vacuum-packed on a coating machine and then transferred to a storage room at -10℃. When needed, the outer packaging of the solid electrode slurry is unpacked and placed in a thawing tank. The tank temperature is set to 40℃, the rotation speed is 25 rpm, and the stirring is carried out for 2 hours until the electrode slurry is completely thawed. Finally, the electrode slurry is transferred to a finished product tank, a -90 kPa vacuum is drawn, the rotation speed is set to 25 rpm, and the stirring is carried out for 30 minutes before being discharged.

[0053] Example 6

[0054] Under normal operating conditions, the positive electrode material (NCM811), conductive agent (acetylene black), and binder (PVDF) are mixed evenly at a mass ratio of 95:3:2, and then dispersed in an NMP solution and stirred evenly to obtain a lithium battery electrode slurry. The overall solid content of the electrode slurry is 64% ± 3%, and the total mass of the electrode slurry is 100 kg. The finished electrode slurry is transferred to a freezing tank through a conveying pipeline. The temperature in the freezing tank is set to -15℃, the vacuum degree is -90 kPa, and the cooling time is 2 hours, at which point the electrode slurry is completely solid. The solid electrode slurry is then dispersed into cubes of approximately 5 cm * 5 cm * 5 cm in a cutting machine. After cutting, it is packaged and then transferred to a storage room at -10℃ for storage. When needed, the solid electrode slurry is unpacked and placed in a thawing tank. The tank temperature is set to 40℃, the rotation speed is 25 rpm, and the electrode slurry is stirred for 2 hours until it is completely thawed. Finally, the electrode slurry was transferred to the finished product tank, a vacuum of -90 kPa was drawn, the revolution speed was turned on at 25 rpm, and the mixture was stirred for 30 minutes before being discharged.

[0055] Comparative Example 1

[0056] Under normal operating conditions, the positive electrode material (NCM811), conductive agent (acetylene black), and binder (PVDF) are mixed evenly at a mass ratio of 95:3:2, and then dispersed in an NMP solution and stirred evenly to obtain a lithium battery electrode slurry. The overall solid content of the electrode slurry is 64% ± 3%, and the total mass of the electrode slurry is 100 kg. The electrode slurry is then placed under normal slow stirring at a revolution speed of 25 rpm.

[0057] Comparative Example 2

[0058] Under normal operating conditions, the negative electrode material (graphite), conductive agent (SP), binder (MAC350HC), and dispersant (JSR-104A) are mixed evenly at a mass ratio of 96:1:1.4:1.6, and then dispersed in pure water and stirred evenly to obtain a lithium battery electrode slurry with a solid content of 53% ± 3% and a total mass of 100 kg. The electrode slurry is then placed under normal slow stirring at a revolution speed of 25 rpm.

[0059] After freezing and storing the electrode slurries of Examples 1-6 for 10 days, the solid content difference between the upper and lower layers of the liquid slurry in the finished product tank was tested after thawing. The difference was <0.3%, indicating that the slurry had not settled and met the requirements for electrode slurry in subsequent coating processes. Currently, after freezing and storing the electrode slurries of Examples 1-6 for 30 days, the solid content difference between the upper and lower layers after thawing is still <0.3%. In contrast, the electrode slurries of Comparative Examples 1-2, without freezing and normal slow stirring for 10 days, showed a solid content difference >2% between the upper and lower layers, indicating that the slurry had settled and did not meet the requirements for electrode slurry in subsequent coating processes. Therefore, it can be seen that the storage method of freezing the electrode slurry in Examples 1-6 can ensure that the slurry does not settle during storage and transportation, greatly extending the storage time of the electrode slurry.

[0060] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0061] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for storing electrode paste, characterized in that, Includes the following steps: The first liquid electrode slurry is frozen to obtain a solid electrode slurry, and then the solid electrode slurry is frozen and stored; wherein the freezing is performed under vacuum conditions; between the freezing and the freezing storage, the following steps are also included: first, the solid electrode slurry is cut, and then the cut solid electrode slurry is vacuum packaged.

2. The method for storing electrode paste according to claim 1, characterized in that, The freezing process is carried out at temperatures below -5°C.

3. The method for storing electrode paste according to claim 2, characterized in that, The freezing process is carried out at a temperature of -20 to -10°C.

4. The method for storing electrode paste according to claim 1 or 2, characterized in that, The freezing process is carried out under vacuum conditions of -60 kPa or less.

5. The method for storing electrode paste according to claim 4, characterized in that, The freezing process is carried out under vacuum conditions of -120 to -60 kPa.

6. The method for storing electrode paste according to claim 1 or 2, characterized in that, The frozen storage is carried out at a temperature below -5°C.

7. The method for storing electrode paste according to claim 6, characterized in that, The frozen storage is carried out at a temperature of -15 to -5°C.

8. A method for taking electrode paste, characterized in that, Includes the following steps: The solid electrode slurry stored by any one of the storage methods described in claims 1-7 is thawed to obtain a second liquid electrode slurry.

9. The method for taking electrode paste according to claim 8, characterized in that, The thawing process is carried out at a temperature above 30°C.

10. The method for taking electrode paste according to claim 9, characterized in that, The thawing process is carried out at a temperature of 30-50℃.

11. The method for taking electrode paste according to claim 8, characterized in that, The thawing process is carried out under stirring conditions of less than 40 rpm.

12. The method for taking electrode paste according to claim 11, characterized in that, The thawing process is carried out under stirring conditions of 20-30 rpm.

13. The method for taking the electrode paste according to any one of claims 8-12, characterized in that, The thawing process also includes a homogenization process: the second liquid electrode slurry is stirred under vacuum conditions.

14. The method for taking electrode paste according to claim 13, characterized in that, The second liquid electrode slurry is stirred under vacuum conditions of -60 kPa or less for at least 20 minutes.

15. The method for taking electrode paste according to claim 14, characterized in that, The second liquid electrode slurry was stirred for 20-40 minutes under a vacuum of -120 to -60 kPa.

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