Temperature control method, drying machine and storage medium

Abstract

The application provides a temperature control method, a drying machine and a storage medium. The method comprises the following steps: obtaining a surface density measurement result of a pole piece sample, the surface density measurement result being a surface density measured after the pole piece sample is dried at a drying temperature being an upper limit value of a drying temperature and for a preset time length; obtaining a surface density measurement compensation value; determining an upper limit value of a pole piece surface density according to the surface density measurement result, the surface density measurement compensation value and a preset maximum solvent content; determining a lower limit value of a drying temperature according to the upper limit value of the pole piece surface density; and setting the drying temperature between the upper limit value of the drying temperature and the lower limit value of the drying temperature. The upper limit value of the pole piece surface density is obtained through the surface density value at the upper limit value of the drying temperature and the maximum solvent content, and then the lower limit value of the drying temperature is obtained. The lower limit value can meet the surface density standard of the pole piece, and the drying temperature is adjusted accordingly, so that the temperature is prevented from being too high and the energy consumption is reduced.

Description

Technical Field

[0001] This invention relates to the field of battery electrode drying technology, specifically to a temperature control method, a dryer, and a storage medium. Background Technology

[0002] Lithium-ion batteries are high-capacity, long-life, and environmentally friendly batteries with numerous advantages, widely used in energy storage, electric vehicles, and portable electronic products. The electrode plates are the foundation of lithium-ion batteries, directly determining their electrochemical performance and safety.

[0003] The manufacturing process of lithium-ion battery electrodes includes: slurry coating, drying, compaction, and cutting or slitting. During the electrode drying process, as the solvent evaporates, the coating undergoes shrinkage, and the solid materials in the wet coating come closer together, ultimately forming a porous, dried electrode structure. In the manufacturing process of lithium-ion batteries, the highest energy consumption steps are electrode drying and solvent recovery, accounting for approximately 47% of the total energy. The excessively high drying temperature contributes to the persistently high energy consumption of the electrode manufacturing process. Summary of the Invention

[0004] The embodiments of the present invention provide a temperature control method, a dryer, and a storage medium, which can improve the technical problems of poor electrode quality and high drying energy consumption caused by high drying temperature of battery electrodes.

[0005] In a first aspect, embodiments of the present invention provide a temperature control method applied to an electrode drying equipment, the method comprising:

[0006] Obtain the areal density measurement result of the electrode sample. The areal density measurement result is the areal density of the electrode sample after drying at the upper limit of the drying temperature and for a preset time. The upper limit of the drying temperature is the critical temperature at which the electrode sample does not crack during drying.

[0007] Obtain the areal density measurement compensation value;

[0008] The upper limit of the electrode surface density is determined based on the areal density measurement results, the areal density measurement compensation value, and the preset maximum solvent content.

[0009] The lower limit of the drying temperature is determined based on the upper limit of the electrode surface density.

[0010] The drying temperature is set between the upper limit of the drying temperature and the lower limit of the drying temperature.

[0011] In embodiments of the present invention, the areal density of the electrode after drying at the upper limit of the drying temperature can be obtained when the solvent content of the electrode approaches 0. The areal density of the electrode is then corrected using an areal density measurement compensation value. This is combined with the maximum solvent content standard of the electrode to obtain the upper limit of the electrode's areal density. Based on the upper limit of the electrode's areal density, the lower limit of the electrode's drying temperature can be obtained, thus determining the minimum drying temperature for the electrode. This minimum temperature satisfies the solvent content standard of the electrode, and therefore satisfies the areal density standard. Setting the drying temperature between the upper and lower limits of the drying temperature prevents excessively high temperatures from adversely affecting the quality of the electrode, and allows for the selection of a suitable drying temperature within this range to reduce energy consumption.

[0012] In one embodiment, the drying temperature is set to the lower limit of the drying temperature.

[0013] In the embodiments of the present invention, the electrode dried at the lower limit of the drying temperature can meet the requirements of electrode solvent content, i.e. electrode areal density, while minimizing energy consumption and preventing the adverse effects of excessively high temperature on electrode quality.

[0014] In one embodiment, before obtaining the areal density measurement result of the electrode sample, the method further includes:

[0015] Obtain the initial drying temperature;

[0016] The electrode sample is dried under first drying conditions, which include: a drying temperature of the initial drying temperature and a drying time of the preset time; and the solvent content of the electrode sample is measured when it is determined that the dried electrode sample has not cracked.

[0017] The electrode sample is dried under a second drying condition, which includes: a drying temperature of the initial drying temperature + t1 and a drying time of the preset time; and the solvent content of the electrode sample is measured when it is determined that the dried electrode sample has not cracked.

[0018] The electrode sample is dried under a third drying condition, which includes: a drying temperature of the initial drying temperature + t1 + t2, and a drying time of the preset time; and the solvent content of the electrode sample is measured when it is determined that the dried electrode sample has not cracked.

[0019] This process continues until the solvent content is less than a preset value, and the drying temperature for this drying is determined as the upper limit of the drying temperature, where t1 and t2 are greater than 0.

[0020] The method for obtaining the areal density measurement results of the electrode sample includes:

[0021] Obtain the areal density measurement results of the electrode sample after drying at the upper limit of the drying temperature and the preset time.

[0022] In embodiments of the present invention, the drying temperature of the electrode sample is continuously increased to achieve a preset value for the solvent content of the electrode sample. This preset value allows the solvent content in the electrode sample to approach 0. The drying temperature at which the required solvent content is achieved without cracking is determined as the upper limit of the electrode drying temperature. At this upper limit of the drying temperature, the solvent content in the resulting electrode sample approaches 0. Therefore, the electrode sample surface density obtained based on the surface density value measured at this time is the surface density of the electrode foil and powder, thereby making the upper limit of the electrode surface density obtained based on the surface density value measured at this time and the maximum solvent content more accurate.

[0023] In one embodiment, the difference in drying temperature between two consecutive drying conditions is the same or gradually decreases.

[0024] In one embodiment, obtaining the areal density measurement result of the electrode sample after drying at the upper limit of the drying temperature and the preset time includes:

[0025] Obtain the areal density measurement results of different regions of the electrode sample after drying at the upper limit of the drying temperature and the preset time;

[0026] The average of the areal density measurement results of different regions of the electrode sample is determined as the areal density measurement result of the electrode sample.

[0027] In an embodiment of the present invention, by obtaining the areal density measurement results of different regions of the electrode sample and taking the average value as the areal density measurement result of the electrode sample, the accuracy of the areal density measurement result of the electrode sample can be improved.

[0028] In one embodiment, obtaining the areal density measurement compensation value includes:

[0029] The weight and dimensions of the electrode sample after drying at the upper limit of the drying temperature and for a preset drying time are obtained.

[0030] Based on the weighing and dimensions, determine the standard areal density of the electrode sample;

[0031] Based on the standard areal density and the areal density measurement results, the areal density measurement compensation value is determined.

[0032] In an embodiment of the present invention, the standard areal density of the electrode sample is calculated by weighing the sample, and the areal density measurement result is compared with it to correct the error of the areal density measurement result, thereby making the areal density of the electrode foil and powder obtained based on the areal density measurement result more accurate.

[0033] In one embodiment, determining the upper limit of the electrode surface density based on the surface density measurement result, the surface density measurement compensation value, and the preset maximum solvent content includes:

[0034] The upper limit of the electrode surface density is calculated based on Equation 1.

[0035] Formula 1: cw max = ,in, 箔材 The surface density of the foil for the electrode sheet. The areal density measurement result is given, and 'a' is the areal density measurement compensation value. This is the preset maximum solvent content.

[0036] In an embodiment of the present invention, the surface density of the foil and powder of the electrode can be obtained by measuring the surface density at the upper limit of the drying temperature and the surface density measurement compensation value. Then, combined with the maximum solvent content of the electrode, the upper limit of the electrode surface density can be obtained.

[0037] In one embodiment, determining the lower limit of the drying temperature based on the upper limit of the electrode surface density includes:

[0038] The electrode sample is dried at a drying temperature T1 lower than the upper limit of the drying temperature and for a set drying time, and the areal density of the dried electrode sample is obtained.

[0039] If the areal density of the electrode sample obtained at the drying temperature T1 is less than the upper limit of the electrode areal density, the electrode sample is dried at a drying temperature T2 lower than the drying temperature T1 and at the set drying time, and the areal density of the dried electrode sample is obtained.

[0040] This process continues until the areal density of the electrode sample is equal to or greater than the upper limit of the electrode areal density. The drying temperature of the drying process that is closest to the upper limit of the electrode areal density and does not exceed the upper limit of the electrode areal density is then determined as the lower limit of the drying temperature.

[0041] In an embodiment of the present invention, the upper limit of the areal density of the electrode sample is reached by continuously reducing the drying temperature of the electrode sample. This upper limit of the areal density is the highest value of the solvent content of the electrode, which corresponds to the lowest drying temperature of the electrode sample, thereby obtaining the lower limit of the drying temperature of the electrode.

[0042] In one embodiment, the difference between two consecutive drying temperatures below the upper limit of the drying temperature is the same or gradually decreases.

[0043] Secondly, embodiments of the present invention provide a dryer, including a processor and a memory, wherein the memory stores computer-readable instructions, and the processor is used to invoke the computer-readable instructions to execute the temperature control method described above.

[0044] Thirdly, embodiments of the present invention provide a storage medium comprising a stored program, wherein the temperature control method described above is executed by a processor during program execution. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention, 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a flowchart of a method for obtaining the drying temperature of battery electrodes provided in an embodiment of the present invention;

[0047] Figure 2 This is a block diagram of a dryer provided in an embodiment of the present invention.

[0048] Among them, 100 is the dryer, 101 is the processor, and 102 is the memory. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention and are not intended to limit the present invention. In the present invention, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0050] Please see Figure 1 One embodiment of this application provides a temperature control method applied to an electrode drying equipment, the method comprising:

[0051] Step S1: Obtain the areal density measurement result of the electrode sample. The areal density measurement result is the areal density of the electrode sample after drying at the upper limit of the drying temperature and for a preset drying time. The upper limit of the drying temperature is the critical temperature at which the electrode sample does not crack during drying.

[0052] Step S2: Obtain the areal density measurement compensation value;

[0053] Step S3: Determine the upper limit of the electrode surface density based on the areal density measurement results, the areal density measurement compensation value, and the preset maximum solvent content;

[0054] Step S4: Determine the lower limit of the drying temperature based on the upper limit of the electrode surface density;

[0055] Step S5: Set the drying temperature between the upper limit of the drying temperature and the lower limit of the drying temperature.

[0056] It should be noted that the electrode sample refers to the coated electrode. The electrode sample used in this invention is an electrode to be dried obtained through the same coating process. The same coating process means that the coating parameters are the same, such as the die coating gap, slurry pump speed, and coating speed. Solvent content refers to the mass percentage of solvent in the electrode. The preset maximum solvent content of the electrode is the production requirement standard, that is, the maximum solvent content of the electrode required for production, which can be adjusted according to production needs. The upper limit of the drying temperature of the electrode is the critical temperature at which the solvent content is minimized and cracking does not occur during double-sided drying of the electrode.

[0057] It should be noted that the areal density measurement process is easily affected by the characteristics of the electrode material and density, which can easily lead to inaccurate measurement results. The accuracy of the areal density measurement can be corrected by obtaining the areal density measurement compensation value.

[0058] In one embodiment, the drying temperature is set to the lower limit of the drying temperature.

[0059] It's understandable that setting the drying temperature to the lower limit of the drying temperature saves more energy while still meeting the requirements for electrode solvent content. A gentler drying temperature can also improve electrode quality, such as peel strength, resistance, and conductivity.

[0060] In one embodiment, before obtaining the areal density measurement result of the electrode sample, the method further includes:

[0061] Obtain the initial drying temperature;

[0062] The electrode sample is dried under first drying conditions, which include: a drying temperature of the initial drying temperature and a drying time of the preset time; and the solvent content of the electrode sample is measured when it is determined that the dried electrode sample has not cracked.

[0063] The electrode sample is dried under a second drying condition, which includes: a drying temperature of the initial drying temperature + t1 and a drying time of the preset time; and the solvent content of the electrode sample is measured when it is determined that the dried electrode sample has not cracked.

[0064] The electrode sample is dried under a third drying condition, which includes: a drying temperature of the initial drying temperature + t1 + t2, and a drying time of the preset time; and the solvent content of the electrode sample is measured when it is determined that the dried electrode sample has not cracked.

[0065] This process continues until the solvent content is less than a preset value, and the drying temperature for this drying is determined as the upper limit of the drying temperature, where t1 and t2 are greater than 0.

[0066] The method for obtaining the areal density measurement results of the electrode sample includes:

[0067] Obtain the areal density measurement results of the electrode sample after drying at the upper limit of the drying temperature and the preset time.

[0068] It should be noted that the preset solvent content is the preset solvent content value of the dried electrode sample. At this solvent content, it can be considered that the solvent in the electrode has completely evaporated, that is, the solvent content in the electrode can be considered to be at its minimum. In this invention, the preset solvent content can be a range or a single value. For example, the preset value can be less than or equal to 0.1%, meaning that the solvent percentage reaches less than or equal to 0.1%, which is considered to have reached the preset value. For example, it can be 0, meaning that the solvent content is 0, which is considered to have reached the preset value. In one embodiment, the difference in drying temperature between two adjacent drying conditions is the same or gradually decreases.

[0069] It is understood that the difference between two adjacent drying temperatures, such as t1 and t2, can be the same or different. For example, if the difference between two adjacent drying temperatures is the same, it could be 0.5℃, 0.6℃, 0.8℃, 1℃, 1.5℃, or 2℃. If the difference between two adjacent drying temperatures is different, it can be larger initially and then smaller, such as increasing by 2℃ each time, increasing a certain number of times (e.g., 3 times), and then increasing by 0.5℃ each time. By first increasing the temperature by a large increment and then decreasing the increment, the determined upper limit of the drying temperature can be made closer to the theoretical value.

[0070] It is understandable that the obtained areal density measurement results of the electrode sample can be used to measure the areal density of the electrode sample when the upper limit of the drying temperature is obtained during the initial drying process, or the areal density of the electrode sample obtained after drying at the upper limit of the drying temperature and a preset time can be obtained by taking another electrode sample.

[0071] It should be noted that the first, second, and third drying conditions can be operated simultaneously or sequentially. After obtaining the drying temperature that meets the upper limit of the drying temperature, further operations can be performed to obtain a more precise value. The electrode samples used under different drying conditions, such as the first, second, and third drying conditions, are not the same electrode.

[0072] In one embodiment, obtaining the areal density measurement result of the electrode sample after drying at the upper limit of the drying temperature and the preset time includes:

[0073] Obtain the areal density measurement results of different regions of the electrode sample after drying at the upper limit of the drying temperature and the preset time;

[0074] The average of the areal density measurement results of different regions of the electrode sample is determined as the areal density measurement result of the electrode sample.

[0075] It is understandable that the areal density measurement results of different regions of the electrode sample can be obtained by taking multiple samples at different locations on the electrode sample and measuring the areal density value separately.

[0076] In one embodiment, obtaining the areal density measurement compensation value includes:

[0077] The weight and dimensions of the electrode sample after drying at the upper limit of the drying temperature and for a preset drying time are obtained.

[0078] Based on the weighing and dimensions, determine the standard areal density of the electrode sample;

[0079] Based on the standard areal density and the areal density measurement results, the areal density measurement compensation value is determined.

[0080] It is understood that weighing the electrode sample can be done using a high-precision balance, such as an analytical balance. In one embodiment, determining the upper limit of the electrode's areal density based on the areal density measurement result, the areal density measurement compensation value, and the preset maximum solvent content includes:

[0081] The upper limit of the electrode surface density is calculated based on Equation 1.

[0082] Formula 1: cw max = ,in, 箔材 The surface density of the foil for the electrode sheet. The areal density measurement result is given, and 'a' is the areal density measurement compensation value. This is the preset maximum solvent content.

[0083] Understandable. The areal density of the electrode sample after drying at the upper limit of the drying temperature, including the areal density of the electrode foil and powder. The areal density of the powder and the solvent.

[0084] In one embodiment, determining the lower limit of the drying temperature based on the upper limit of the electrode surface density includes:

[0085] The electrode sample is dried at a drying temperature T1 lower than the upper limit of the drying temperature and for a set drying time, and the areal density of the dried electrode sample is obtained.

[0086] If the areal density of the electrode sample obtained at the drying temperature T1 is less than the upper limit of the electrode areal density, the electrode sample is dried at a drying temperature T2 lower than the drying temperature T1 and at the set drying time, and the areal density of the dried electrode sample is obtained.

[0087] This process continues until the areal density of the electrode sample is equal to or greater than the upper limit of the electrode areal density. The drying temperature of the drying process that is closest to the upper limit of the electrode areal density and does not exceed the upper limit of the electrode areal density is then determined as the lower limit of the drying temperature.

[0088] It should be noted that the set drying time can be the same as or different from the preset time. The areal density of the dried electrode sample can be obtained based on the areal density measurement results, areal density compensation value, and surface area, or it can be obtained by weighing. The electrode samples used at different drying temperatures, such as drying temperature T1 and drying temperature T2, are not the same electrode.

[0089] In one embodiment, the difference between two consecutive drying temperatures below the upper limit of the drying temperature is the same or gradually decreases.

[0090] It is understandable that the difference between two adjacent drying temperatures, such as T1-T2, can be the same or different. For example, if the difference between two adjacent drying temperatures is the same, it could be 0.5℃, 0.6℃, 0.8℃, 1℃, 1.5℃, or 2℃. If the difference between two adjacent drying temperatures is different, it can be larger initially and then smaller, such as decreasing by 2℃ each time, decreasing a certain number of times (e.g., 3 times), and then decreasing by 0.5℃ each time. By first decreasing the temperature by a large increment and then gradually reducing the increment, the determined lower limit of the drying temperature can be made closer to the theoretical value.

[0091] It should be noted that drying temperatures T1, T2, etc. can be operated simultaneously or sequentially. After obtaining the drying temperature that satisfies the requirement that the areal density of the dried electrode sample is equal to or greater than the upper limit of the areal density of the electrode, further operations can be performed to obtain a more accurate value.

[0092] Secondly, please refer to Figure 2 An embodiment of the present invention provides a dryer 100, including a processor 101 and a memory 102. The memory 102 stores computer-readable instructions, and the processor 101 is used to call the computer-readable instructions to execute the temperature control method described above.

[0093] Thirdly, embodiments of the present invention provide a storage medium comprising a stored program, wherein the temperature control method described above is executed by a processor during program execution.

[0094] The embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. 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 the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A temperature control method, characterized in that, The method, applied to electrode drying equipment, includes: Obtain the areal density measurement result of the electrode sample. The areal density measurement result is the areal density of the electrode sample after drying at the upper limit of the drying temperature and for a preset time. The upper limit of the drying temperature is the critical temperature at which the electrode sample does not crack during drying. Obtain the areal density measurement compensation value; The upper limit of the electrode surface density is determined based on the areal density measurement results, the areal density measurement compensation value, and the preset maximum solvent content. The lower limit of the drying temperature is determined based on the upper limit of the electrode surface density. The drying temperature is set between the upper limit of the drying temperature and the lower limit of the drying temperature.

2. The temperature control method according to claim 1, characterized in that, Before obtaining the areal density measurement results of the electrode sample, the method further includes: Obtain the initial drying temperature; The electrode sample is dried under first drying conditions, which include: a drying temperature of the initial drying temperature and a drying time of the preset time; and the solvent content of the electrode sample is measured when it is determined that the dried electrode sample has not cracked. The electrode sample is dried under a second drying condition, which includes: a drying temperature of the initial drying temperature + t1 and a drying time of the preset time; and the solvent content of the electrode sample is measured when it is determined that the dried electrode sample has not cracked. The electrode sample is dried under a third drying condition, which includes: a drying temperature of the initial drying temperature + t1 + t2, and a drying time of the preset time; and the solvent content of the electrode sample is measured when it is determined that the dried electrode sample has not cracked. This process continues until the solvent content is less than a preset value, and the drying temperature for this drying is determined as the upper limit of the drying temperature, where t1 and t2 are greater than 0. The method for obtaining the areal density measurement results of the electrode sample includes: Obtain the areal density measurement results of the electrode sample after drying at the upper limit of the drying temperature and the preset time.

3. The temperature control method according to claim 2, characterized in that, The difference in drying temperature between two consecutive drying conditions is the same or gradually decreases.

4. The temperature control method according to claim 2 or 3, characterized in that, The step of obtaining the areal density measurement results of the electrode sample after drying at the upper limit of the drying temperature and the preset time includes: Obtain the areal density measurement results of different regions of the electrode sample after drying at the upper limit of the drying temperature and the preset time; The average of the areal density measurement results of different regions of the electrode sample is determined as the areal density measurement result of the electrode sample.

5. The temperature control method according to claim 4, characterized in that, The acquisition of the areal density measurement compensation value includes: The weight and dimensions of the electrode sample after drying at the upper limit of the drying temperature and for a preset drying time are obtained. Based on the weighing and dimensions, determine the standard areal density of the electrode sample; Based on the standard areal density and the areal density measurement results, the areal density measurement compensation value is determined.

6. The temperature control method according to claim 1, characterized in that, The step of determining the upper limit of the electrode surface density based on the surface density measurement results, the surface density measurement compensation value, and the preset maximum solvent content includes: The upper limit of the electrode surface density is calculated based on Equation 1. Formula 1: cw max = ,in, 箔材 The surface density of the foil for the electrode sheet. The areal density measurement result is given, and 'a' is the areal density measurement compensation value. This is the preset maximum solvent content.

7. The temperature control method according to claim 1, characterized in that, The step of determining the lower limit of the drying temperature based on the upper limit of the electrode surface density includes: The electrode sample is dried at a drying temperature T1 lower than the upper limit of the drying temperature and for a set drying time, and the areal density of the dried electrode sample is obtained. If the areal density of the electrode sample obtained at the drying temperature T1 is less than the upper limit of the electrode areal density, the electrode sample is dried at a drying temperature T2 lower than the drying temperature T1 and at the set drying time, and the areal density of the dried electrode sample is obtained. This process continues until the areal density of the electrode sample is equal to or greater than the upper limit of the electrode areal density. The drying temperature of the drying process that is closest to the upper limit of the electrode areal density and does not exceed the upper limit of the electrode areal density is then determined as the lower limit of the drying temperature.

8. The temperature control method according to claim 7, characterized in that, The difference between two consecutive drying temperatures below the upper limit of the drying temperature is the same or gradually decreases.

9. A dryer, characterized in that, The device includes a processor and a memory, wherein the memory stores computer-readable instructions, and the processor is used to invoke the computer-readable instructions to execute the temperature control method as described in any one of claims 1 to 8.

10. A storage medium, characterized in that, The storage medium includes a stored program, wherein, when the program is executed, the temperature control method according to any one of claims 1 to 8 is executed by a processor.

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