Method for determining compacted density of pole piece, method for preparing pole piece, and method for preparing battery

Abstract

The application provides a kind of electrode sheet compaction density determination method, electrode sheet preparation method and battery preparation method, comprising: determining the first roll pressure threshold value and the second roll pressure threshold value of a plurality of first electrode sheets;According to the first roll pressure threshold value and the second roll pressure threshold value, determine the third roll pressure threshold value;Using the first roll pressure, roll the plurality of first electrode sheets, and obtain the maximum roll pressure of the first electrode sheet;The maximum roll pressure is used to roll the plurality of first electrode sheets, and then the standard compaction density of the first electrode sheet is obtained by folding test. Simplify the calculation steps of determining the standard compaction density, and then improve the production efficiency of the battery.

Description

Technical Field

[0001] This invention relates to the technical field of secondary battery manufacturing, and in particular to a method for determining the compaction density of an electrode, an electrode manufacturing method, and a battery manufacturing method. Background Technology

[0002] In secondary battery design, the compaction density of the electrode is calculated as: electrode areal density / (electrode thickness - current collector thickness), expressed in grams per cubic centimeter (g / cm³). 3 The compaction density of the electrode is closely related to the particle morphology, particle size distribution, and specific surface area of ​​the electrode material itself, as well as factors such as the proportion of each component, coating density, and foil thickness in actual use. Optimal compaction density parameters are of great significance for improving battery capacity, rate capability, cycle life, and other performance characteristics.

[0003] Rolling the electrode can enhance the adhesion strength between the active material and the current collector, while reducing the internal porosity of the active material, thereby reducing the internal resistance of the secondary battery and improving its cycle life. Currently, calculating the compaction density of the electrode during manufacturing is quite complex. The maximum compaction density is usually determined by measuring various properties of the electrode, a cumbersome process that makes finding the optimal value difficult. Therefore, a method is needed to quickly determine the compaction density of the electrode during production, ensuring battery performance while improving production efficiency.

[0004] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for calculating compaction density, a method for preparing electrodes, and a method for preparing batteries, so as to solve the problems that the calculation process for the optimal compaction density of electrodes is cumbersome and that it is difficult to obtain the optimal compaction density of electrodes in the prior art.

[0006] To achieve the above and other related objectives, the present invention provides a method for determining the compaction density of an electrode sheet, comprising:

[0007] A first rolling pressure threshold and a second rolling pressure threshold are determined for multiple first electrodes. When multiple first electrodes are rolled with a rolling pressure greater than or equal to the first rolling pressure threshold and then folded, multiple first electrodes exhibit light transmission. When multiple first electrodes are rolled with a rolling pressure less than or equal to the second rolling pressure threshold and then folded, multiple first electrodes do not exhibit light transmission.

[0008] A third roller pressure threshold is determined based on the first roller pressure threshold and the second roller pressure threshold, wherein the third roller pressure threshold is greater than the second roller pressure threshold and less than the first roller pressure threshold;

[0009] Using the first rolling pressure, multiple first electrode sheets are subjected to rolling and folding tests. Based on the light transmission phenomenon of multiple first electrode sheets, the first rolling pressure is adjusted using a dichotomy method between the third rolling pressure threshold and the first rolling pressure threshold or the second rolling pressure threshold, until some first electrode sheets transmit light and some do not when the multiple first electrode sheets are folded after rolling. The first rolling pressure at this time is taken as the maximum rolling pressure of the first electrode sheet. The initial first rolling pressure is the third rolling pressure threshold.

[0010] The standard compaction density of the first electrode is determined by the compaction density of the first electrode that did not exhibit light transmission during a folding test after rolling multiple first electrode sheets with the maximum rolling pressure.

[0011] Optionally, adjusting the first rolling pressure using a dichotomy method between the third rolling pressure threshold and the first rolling pressure threshold or the second rolling pressure threshold, based on the light transmission phenomenon of the plurality of first electrodes, includes:

[0012] If multiple first electrode sheets exhibit light transmission, the first roller pressure is adjusted using a dichotomy method between the third roller pressure threshold and the second roller pressure threshold.

[0013] If none of the first electrodes transmit light, the first roller pressure is adjusted using a dichotomy method between the third roller pressure threshold and the first roller pressure threshold.

[0014] Optionally, the standard compaction density of the first electrode sheet is determined by using the compaction density of the first electrode sheet that did not exhibit light transmission during a folding test after rolling multiple first electrode sheets with the maximum rolling pressure, including:

[0015] The maximum compaction density of the first electrode sheet that did not exhibit light transmission during the folding test after rolling multiple first electrode sheets with the maximum rolling pressure is taken as the standard compaction density.

[0016] Alternatively, the average compaction density of the first electrode sheets that did not exhibit light transmission during a folding test after being rolled with the maximum rolling pressure is taken as the standard compaction density.

[0017] Optionally, the folding test includes:

[0018] Fold the first electrode sheet to 180 degrees in the first direction, roll it at least once using the second roller pressure, and then unfold it. If the first electrode sheet does not transmit light, fold the first electrode sheet to 180 degrees in the second direction, roll it at least once using the third roller pressure, and then unfold it to determine whether the first electrode sheet transmits light.

[0019] Optionally, determining a third roller pressure threshold based on the first roller pressure threshold and the second roller pressure threshold includes:

[0020] The average of the first and second roller pressure thresholds is used as the third roller pressure threshold.

[0021] Optionally, the first electrode is a lithium-ion battery electrode, a sodium-ion battery electrode, or a potassium-ion battery electrode.

[0022] Optionally, the plurality of first electrodes are electrodes of the same type, and the electrode surface density, current collector surface density, and current collector thickness of the plurality of first electrodes are within a preset error range.

[0023] Optionally, the shape of the first electrode can be any of the following: circular, elliptical, regular polygonal, rectangular, trapezoidal, and racetrack-shaped.

[0024] To achieve the above and other related objectives, the present invention provides a method for preparing an electrode sheet, the method comprising at least:

[0025] Based on the method for determining the compaction density of the electrode sheet, the standard compaction density of the electrode sheet for the battery to be prepared is determined:

[0026] Electrodes are prepared according to the standard compaction density.

[0027] To achieve the above and other related objectives, the present invention provides a battery manufacturing method, the battery manufacturing method comprising: producing an electrode based on the electrode manufacturing method, and further manufacturing the electrode into a battery.

[0028] As described above, the method for determining the compaction density of the electrode, the electrode preparation method, and the battery preparation method of the present invention have the following beneficial effects:

[0029] The electrode compaction density determination method, electrode preparation method, and battery preparation method of the present invention simplify the calculation steps for determining the electrode compaction density compared to the prior art which measures various properties of the electrode to determine its maximum compaction density, thereby improving the battery production efficiency. Attached Figure Description

[0030] Figure 1This is a flowchart illustrating the method for determining the compaction density of an electrode sheet provided in an embodiment of this application.

[0031] Figure 2 This is a schematic flowchart of the electrode preparation method provided in the embodiments of this application. Detailed Implementation

[0032] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0033] Please see Figures 1 to 2 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. The illustrations only show components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0034] like Figure 1 As shown, this embodiment provides a method for determining the compaction density of an electrode sheet, including:

[0035] S1: Determine a first rolling pressure threshold and a second rolling pressure threshold for multiple first electrodes. When multiple first electrodes are rolled and folded using a rolling pressure greater than or equal to the first rolling pressure threshold, all multiple first electrodes exhibit light transmission. When multiple first electrodes are rolled and folded using a rolling pressure less than or equal to the second rolling pressure threshold, none of the multiple first electrodes exhibit light transmission.

[0036] It should be noted that the light transmission phenomenon includes two situations: light transmission without breakage and light transmission with breakage.

[0037] To further ensure the uniformity of the multiple first electrodes and the reliability of the electrode compaction density calculation, the multiple first electrodes are of the same type, meaning that the current collector and coating slurry are consistent. Furthermore, the areal density of the multiple first electrodes, the areal density of the current collector, and the thickness of the current collector are within a preset error range. Preferably, the multiple first electrodes are produced in the same batch. In other possible embodiments, electrodes from different batches can also be used, as long as the coating slurry of the multiple first electrodes is consistent, and the errors between the areal density, current collector areal density, and current collector thickness are within a preset error range. The specific preset error ranges for the areal density, current collector areal density, and current collector thickness should be set according to the application scenario, and will not be elaborated here.

[0038] This application embodiment does not limit the number of multiple first electrodes. Generally, more than 5 first electrodes are selected for folding tests. The more first electrodes there are, the more reliable the folding test results are. However, in actual processes, the number of first electrodes should be set according to actual needs. Furthermore, the direction of rolling, the number of rolling cycles, and the number of first electrodes should be set based on the usage scenario and are not limited to this embodiment.

[0039] For example, during each test, 5, 10, 20, 30, or 50 first electrode sheets can be selected as a group for one test. Throughout the process of confirming the compaction density of the first electrode sheets, multiple groups of first electrode sheets are needed. The number of first electrode sheets in each group can be the same or different. Preferably, each group can have up to 10 first electrode sheets, which ensures the accuracy of the compaction density while preventing the excessive workload caused by selecting too many first electrode sheets.

[0040] This application does not limit the specific implementation method for determining the first and second rolling pressure thresholds of multiple first electrodes. For example, the first and second rolling pressure thresholds of the first electrodes can be determined empirically, or they can be determined through actual testing.

[0041] The first and second rolling pressure thresholds can be determined by rolling multiple first electrodes and performing folding tests.

[0042] This application embodiment uses the method of rolling multiple first electrodes and performing a folding test to determine the first rolling pressure threshold as an example. Specifically, multiple first electrodes are rolled using a preset rolling pressure, and then the rolled first electrodes are folded. If all the folded first electrodes are translucent, the preset rolling pressure is taken as the first rolling pressure threshold. Alternatively, another set of first electrodes (multiple first electrodes) is selected, the preset rolling pressure is appropriately reduced, and the adjusted preset rolling pressure is used to roll the multiple first electrodes. The rolled first electrodes are then folded, and if all the folded first electrodes are translucent, the adjusted preset rolling pressure is taken as the first rolling pressure threshold. This application embodiment is only an example and is not limited to this. Furthermore, the method for determining the second rolling pressure threshold by rolling multiple first electrodes and performing a folding test is similar to the method for determining the first rolling pressure threshold. The difference is that when multiple first electrodes are rolled using the rolling pressure of the second rolling pressure threshold and then folded, none of the first electrodes exhibit light transmission. This application's embodiments will not elaborate further.

[0043] It should be noted that after the first electrode is coated and dried, the peel strength between the active material and the current collector is very low. At this point, it needs to be rolled to enhance the adhesion strength between the active material and the current collector, preventing the active material from leaving the current collector during electrolyte immersion and battery use. Rolling the electrode reduces the porosity of the active material, thereby reducing the battery's internal resistance and improving its cycle life.

[0044] The first electrode sheet includes, but is not limited to, lithium-ion battery electrode sheets, sodium-ion battery electrode sheets, or potassium-ion battery electrode sheets. As long as the standard compaction density of the first electrode sheet can be determined, any type of first electrode sheet is applicable and is not limited to this embodiment.

[0045] S2: Determine a third roller pressure threshold based on the first roller pressure threshold and the second roller pressure threshold, wherein the third roller pressure threshold is greater than the second roller pressure threshold and less than the first roller pressure threshold.

[0046] After determining the first and second roller pressure thresholds, a third roller pressure threshold can be arbitrarily selected between them. A relatively reasonable third roller pressure threshold is one where the differences between the third and both the first and second roller pressure thresholds are relatively large. In one possible implementation, the average of the first and second roller pressure thresholds is used as the third roller pressure threshold. It should be noted that when the third roller pressure threshold is equal to the average of the first and second roller pressure thresholds, it is determined using a bisection method between these two thresholds. In specific implementations, the third roller pressure threshold should be determined according to the specific application scenario. The third roller pressure threshold may or may not be equal to the average of the first and second roller pressure thresholds, and is not limited to this embodiment.

[0047] S3: Using the first rolling pressure, roll and fold tests are performed on multiple first electrode sheets. Based on the light transmission phenomenon of multiple first electrode sheets, the first rolling pressure is adjusted using a binary method between the third rolling pressure threshold and the first rolling pressure threshold or the second rolling pressure threshold, until some first electrode sheets transmit light and some do not when the multiple first electrode sheets are folded after rolling. The first rolling pressure at this time is taken as the maximum rolling pressure of the first electrode sheet. The initial first rolling pressure is the third rolling pressure threshold.

[0048] After determining the third rolling pressure threshold, the first rolling pressure, initially set to the third rolling pressure threshold, is used to roll multiple first electrodes and perform a folding test. This application does not limit the specific implementation of the folding test. In one possible implementation, the folding test may include:

[0049] The first electrode is folded 180 degrees in a first direction, rolled at least once using the pressure of a second roller, and then unfolded. If the first electrode does not transmit light, it is folded 180 degrees in a second direction, rolled at least once using the pressure of a third roller, and then unfolded to determine whether the first electrode transmits light. The folding trajectory of the first electrode in the second direction is opposite to that in the first direction.

[0050] The first electrode sheet, after being rolled by the first roller, is folded 180 degrees in the first direction (forward fold) and then rolled at least once using the second roller pressure before unfolding. The second roller pressure can be set according to actual needs, and the number of times the first electrode sheet is rolled using the second roller pressure can be set to 2, 3, 4, 5, etc., as described in this embodiment. If the first electrode sheet does not transmit light after unfolding, it is folded again in the second direction (reverse fold) and rolled using the third roller pressure. The number of times this is rolled can also be set to 2, 3, 4, 5, etc., and the third roller pressure can be equal to or unequal to the second roller pressure. After unfolding using the third roller pressure, it is determined whether the first electrode sheet transmits light.

[0051] If the first electrode becomes translucent after being rolled at least once using the second roller pressure, then no further steps are performed on the first electrode.

[0052] After performing rolling and folding tests on multiple first electrodes using the first roller pressure, the multiple first electrodes may exhibit light transmission (including two situations: light transmission without breakage and breakage), or light opacity without breakage. Based on the light transmission phenomenon of the multiple first electrodes, the first roller pressure is adjusted using a dichotomy method between the third roller pressure threshold and the first roller pressure threshold, or between the third roller pressure threshold and the second roller pressure threshold.

[0053] In one possible implementation, based on the light transmission phenomenon of the multiple first electrodes, the first roller pressure is adjusted using a dichotomy method between the third roller pressure threshold and the first roller pressure threshold or the second roller pressure threshold, including:

[0054] If multiple first electrodes exhibit light transmission, the first roller pressure is adjusted using a dichotomy method between the third roller pressure threshold and the second roller pressure threshold; if none of the multiple first electrodes exhibit light transmission, the first roller pressure is adjusted using a dichotomy method between the third roller pressure threshold and the first roller pressure threshold.

[0055] For example, if multiple first electrodes exhibit light transmission, it indicates that the first rolling pressure is too high. Therefore, the first rolling pressure is adjusted using a dichotomy method between the third and second rolling pressure thresholds. Specifically, the average of the third and second rolling pressure thresholds is used to update the first rolling pressure. A new set of multiple first electrodes is then selected, and the updated first rolling pressure is used to perform rolling and folding tests on the updated first electrodes. If all the updated first electrodes exhibit light transmission, it indicates that the updated first rolling pressure is still too high. The first rolling pressure is adjusted using a dichotomy method between the updated first rolling pressure (i.e., the average of the third and second rolling pressure thresholds) and the second rolling pressure threshold. That is, the average of the updated first and second rolling pressure thresholds is selected to update the first rolling pressure again, and so on, until when multiple first electrodes are folded after rolling, some first electrodes show light transmission and some do not (do not show light transmission and do not break). The first rolling pressure at this time is taken as the maximum rolling pressure of the first electrode.

[0056] It should be noted that if none of the multiple first electrodes exhibit light transmission, the specific implementation method of adjusting the first roller pressure using the dichotomy method between the third roller pressure threshold and the first roller pressure threshold is similar to the specific implementation method of adjusting the first roller pressure using the dichotomy method between the third roller pressure threshold and the second roller pressure threshold if all of the multiple first electrodes exhibit light transmission. Therefore, the embodiments of this application will not be described in detail.

[0057] For ease of understanding, the following embodiments of this application illustrate the method for determining the maximum rolling pressure of the first electrode sheet using specific examples. In each group, five first electrodes are selected, and the first and second rolling pressure thresholds for each first electrode sheet are 3 × 10⁻⁶. 6 Newton and 1×10 6 Newton, the selected third roller pressure threshold is 2×10 6 Newtons. The second and third roller pressures used in the folding test were both 25 Newtons, and the number of roller presses was twice. Specifically, as an example, the surface density of the current collector was selected as 36.625 ± 2 g / m³. 2 The current collector thickness is 15±1 micrometers, and the electrode surface density is 500±7.5 g / m². 2 The first electrode was tested, and in subsequent calculations, the current collector surface density was set at 36.625 g / m². 2The current collector thickness is calculated to be 15 micrometers. After the first electrode sheet is rolled with the first roller pressure, it is cut into squares with a side length of 4 centimeters. The cut square electrode sheets are weighed and the electrode sheet thickness is measured, and then a folding test is performed. The compaction density = electrode sheet surface density / (electrode sheet thickness - current collector thickness), electrode sheet surface density = (electrode sheet mass - current collector mass) / electrode sheet area, and current collector mass = current collector surface density * electrode sheet area. The specific implementation is as follows:

[0058] The first roller pressure of the first electrode sheet in the first batch adopts the third roller pressure threshold, namely 2×10. 6 The second and third rolling pressures used in the folding test were both 25 Newtons, and the rolling was performed twice. The rolling parameters of the first batch of first electrode sheets are shown in Table 1.

[0059] Table 1: Parameters after the first batch of rolling

[0060]

[0061] As shown in Table 1 above, all the first electrode sheets in the first batch broke after the folding test. This indicates that the first rolling pressure was too high. Therefore, the average value between the first rolling pressure and the second rolling pressure threshold used in the first batch was taken as the first rolling pressure for the second batch of first electrode sheets, i.e., 1.5 × 10⁻⁶. 6 The second and third rolling pressures used in the folding test were both 25 Newtons, and the number of rolling cycles was 2. The rolling parameters of the first electrode sheet in the second batch are shown in Table 2.

[0062] Table 2: Parameters after the second batch of rolling

[0063]

[0064] As shown in Table 2 above, the first electrode sheets of the second batch did not break after the folding test and were opaque. This indicates that the first rolling pressure was too low. Therefore, the average value between the first rolling pressure and the third rolling pressure threshold used in the second batch was taken as the first rolling pressure for the first electrode sheets of the third batch. That is, the third rolling pressure threshold for the first electrode sheets of the third batch was set to 1.75 × 10⁻⁶. 6 The second and third rolling pressures used in the folding test were both 25 Newtons, and the number of rolling cycles was 2. The rolling parameters of the first electrode sheet in the third batch are shown in Table 3.

[0065] Table 3: Parameters after the third batch of rolling

[0066]

[0067] As shown in Table 3 above, the first electrode sheets of the third batch did not break after the folding test and were opaque. This indicates that the first rolling pressure was too low. Therefore, the average value between the first rolling pressure and the third rolling pressure threshold used in the third batch was taken as the first rolling pressure of the first electrode sheets of the fourth batch. That is, the third rolling pressure threshold of the first electrode sheets of the fourth batch was set to 1.875 × 10⁻⁶. 6 The second and third rolling pressures used in the folding test were both 25 Newtons, and the number of rolling cycles was 2. The rolling parameters of the first electrode sheet in the fourth batch are shown in Table 4.

[0068] Table 4: Parameters after the 4th batch of rolling

[0069]

[0070] As shown in Table 4 above, all the first electrode sheets in the fourth batch broke after the folding test. This indicates that the first rolling pressure was too high. Therefore, the average of the first rolling pressure used in the fourth batch and the first rolling pressure used in the third batch was taken as the first rolling pressure of the first electrode sheets in the fifth batch. That is, the third rolling pressure threshold for the first electrode sheets in the fifth batch was set to 1.813 × 10⁻⁶. 6 The pressure used in the folding test was 25 Newtons (taken as three decimal places). The second and third roller pressures were both 25 Newtons, and the number of roller pressures was 2. The roller pressure parameters of the first electrode sheet of the fifth batch are shown in Table 5.

[0071] Table 5: Parameters after the 5th batch of rolling

[0072]

[0073] As shown in Table 5 above, the first electrode sheets in the fifth batch did not break after the folding test, but they were translucent. This indicates that the first rolling pressure was too high. Therefore, the average of the first rolling pressure used in the fifth batch and the first rolling pressure used in the third batch was taken as the first rolling pressure of the first electrode sheets in the sixth batch. That is, the threshold value of the third rolling pressure of the first electrode sheets in the sixth batch was set to 1.782 × 10⁻⁶. 6 The pressure of the second and third rollers used in the folding test was 25 Newtons (taken as three decimal places). The number of roller presses was 2 times. The roller press parameters of the first electrode sheet of the 6th batch are shown in Table 6.

[0074] Table 6: Parameters after the 6th batch of rolling

[0075]

[0076] As shown in Table 6 above, the first electrode sheets of the 6th batch did not break after the folding test and were opaque. This indicates that the first rolling pressure was too low. Therefore, the average of the first rolling pressure used in the 6th batch and the first rolling pressure used in the 5th batch was taken as the first rolling pressure of the first electrode sheets of the 7th batch. That is, the third rolling pressure threshold for the first electrode sheets of the 7th batch was set to 1.800 × 10⁻⁶. 6 The pressure used in the folding test was 25 Newtons (taken as three decimal places). The second and third roller pressures were both 25 Newtons, and the number of roller pressures was 2. The roller pressure parameters of the first electrode sheet of the 7th batch are shown in Table 7.

[0077] Table 7: Parameters after rolling of the 7th batch

[0078]

[0079] As shown in Table 7 above, the first electrode sheets of the 7th batch did not break after the folding test and were opaque. This indicates that the first rolling pressure was too low. Therefore, the average of the first rolling pressure used in the 7th batch and the first rolling pressure used in the 5th batch was taken as the first rolling pressure of the first electrode sheets of the 8th batch. That is, the third rolling pressure threshold for the first electrode sheets of the 8th batch was set to 1.806 × 10⁻⁶. 6 The pressure used in the folding test was 25 Newtons (taken as three decimal places). The second and third rolling pressures were both 25 Newtons, and the number of rolling cycles was 2. The rolling parameters of the first electrode sheet in the 8th batch are shown in Table 8.

[0080] Table 8: Parameters after the 8th batch of rolling

[0081]

[0082] As shown in Table 8 above, the first electrode sheets of the 8th batch did not break after the folding test, but they were opaque. This indicates that the first rolling pressure was too high. Therefore, the average of the first rolling pressure used in the 8th batch and the first rolling pressure used in the 7th batch was taken as the first rolling pressure of the first electrode sheets of the 9th batch. That is, the third rolling pressure threshold for the first electrode sheets of the 9th batch was set to 1.803 × 10⁻⁶. 6 The pressure used in the folding test was 25 Newtons (taken as three decimal places). The second and third roller pressures were both 25 Newtons, and the number of roller pressures was 2. The roller pressure parameters of the first electrode sheet of the 9th batch are shown in Table 9.

[0083] Table 9: Parameters after rolling of the 9th batch

[0084]

[0085] As shown in Table 9 above, after the folding test, some of the first electrode sheets in the 9th batch did not break but were translucent, while others did not break and were not translucent. The first rolling pressure at this point is taken as the maximum rolling pressure; that is, the maximum rolling pressure is the first rolling pressure used in the 9th batch.

[0086] S4: Determine the standard compaction density of the first electrode sheet by using the maximum rolling pressure to measure the compaction density of the first electrode sheet that did not exhibit light transmission during the folding test after rolling multiple first electrode sheets.

[0087] Specifically, determining the standard compaction density of the first electrode sheet by measuring the compaction density of the first electrode sheet that did not exhibit light transmission during the folding test after rolling multiple first electrode sheets with the maximum rolling pressure, includes:

[0088] The maximum compaction density of the first electrode sheet that did not transmit light or break during the folding test after rolling multiple first electrode sheets with the maximum rolling pressure is taken as the standard compaction density.

[0089] Taking the above embodiment as an example, referring to Table 9, electrode 2 and electrode 4 are neither broken nor translucent. The calculated compaction density of electrode 2 is 2.406 g / cm³. 3 The compaction density of electrode 4 is calculated to be 2.413 g / cm³. 3 After comparison, the compaction density of electrode 4 was taken as the standard compaction density of the electrode.

[0090] Alternatively, the average compaction density of the first electrode sheets that did not exhibit light transmission during a folding test after being rolled with the maximum rolling pressure is taken as the standard compaction density.

[0091] Taking the above embodiment as an example, referring to Table 9, electrode 2 and electrode 4 are neither broken nor translucent. The calculated compaction density of electrode 2 is 2.406 g / cm³. 3 The compaction density of electrode 4 is calculated to be 2.413 g / cm³. 3 The average of the two values ​​is 2.4095 g / cm³. 3 As the standard compaction density of the electrode sheet.

[0092] In other possible implementations, the maximum rolling pressure can be used to roll and fold a new batch of first electrodes (the number of electrodes can be increased appropriately to improve accuracy), and the compaction density of the first electrodes that do not break or transmit light after the folding test can be used to determine the standard compaction density. The embodiments of this application are not limited to this.

[0093] It should be further explained that, in order to facilitate the calculation of areal density, the first electrode can be set to a standard shape. For example, the shape of the first electrode can be any of the following: circle, ellipse, regular polygon, rectangle, trapezoid and racetrack shape. Any shape of the first electrode is applicable as long as it facilitates the calculation of areal density, and is not limited to this embodiment.

[0094] like Figure 2 As shown, this embodiment provides a method for preparing an electrode, the method comprising:

[0095] S91: Determine the standard compaction density of the electrode sheet of the battery to be prepared.

[0096] S92: Prepare electrode sheets according to the standard compaction density.

[0097] The method for determining the standard compaction density of the electrode sheet to be prepared is achieved through the electrode sheet compaction density determination method provided in the above embodiments of this application. The content and effects of this method will not be repeated in the embodiments of this application.

[0098] After determining the standard compaction density of the electrode to be manufactured, the electrode thickness is obtained based on the standard compaction density and the electrode compaction density calculation formula. The rolling pressure of the electrode is then determined based on the electrode thickness. The electrode is then manufactured according to the rolling pressure. This application does not limit the specific implementation method of obtaining the rolling pressure of the electrode based on the electrode thickness; for example, it can be set based on experience. After the electrode is manufactured, a folding test can be performed to further ensure the reliability of the electrode. The specific folding test method is consistent with the folding test method in the above embodiments and will not be repeated.

[0099] This embodiment also provides a battery manufacturing method, which includes: producing an electrode based on the electrode manufacturing method, and further manufacturing the electrode into a battery. In summary, the present invention provides a method for determining the compaction density of an electrode, an electrode manufacturing method, and a battery manufacturing method, comprising: determining a first rolling pressure threshold and a second rolling pressure threshold for a plurality of first electrodes, wherein when the plurality of first electrodes are rolled with a rolling pressure greater than or equal to the first rolling pressure threshold and then subjected to a folding test, all the plurality of first electrodes exhibit light transmission; when the plurality of first electrodes are rolled with a rolling pressure less than or equal to the second rolling pressure threshold and then subjected to a folding test, none of the plurality of first electrodes exhibit light transmission; and determining a third rolling pressure threshold based on the first rolling pressure threshold and the second rolling pressure threshold, wherein the third rolling pressure threshold is greater than the second rolling pressure threshold and less than the first rolling pressure threshold. The method involves using a first rolling pressure to perform rolling and folding tests on multiple first electrodes. Based on the light transmittance of the multiple first electrodes, the first rolling pressure is adjusted using a dichotomy method between a third rolling pressure threshold and either the first or second rolling pressure threshold, until some first electrodes exhibit light transmittance and others do not during the folding test after rolling. This first rolling pressure is then taken as the maximum rolling pressure of the first electrodes, initially set at the third rolling pressure threshold. The standard compaction density of the first electrode is determined by using the compaction density of the first electrode that did not exhibit light transmittance during the folding test after rolling with the maximum rolling pressure. This invention's method for determining electrode compaction density, electrode preparation method, and battery preparation method, compared to the prior art which determines the maximum compaction density by measuring various properties of the electrode, simplifies the calculation steps for determining the standard compaction density, thereby improving battery production efficiency. The above embodiments are merely illustrative of the principles and effects of the invention and are not intended to limit the invention. Anyone skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. A method for determining the compaction density of an electrode sheet, characterized in that, include: A first rolling pressure threshold and a second rolling pressure threshold are determined for a plurality of first electrodes. When the plurality of first electrodes are rolled with a rolling pressure greater than or equal to the first rolling pressure threshold and then folded, the plurality of first electrodes exhibit light transmission. When the plurality of first electrodes are rolled with a rolling pressure less than or equal to the second rolling pressure threshold and then folded, the plurality of first electrodes do not exhibit light transmission. The plurality of first electrodes are electrodes of the same type. A third roller pressure threshold is determined based on the first roller pressure threshold and the second roller pressure threshold, wherein the third roller pressure threshold is greater than the second roller pressure threshold and less than the first roller pressure threshold; Using the first rolling pressure, multiple first electrode sheets are subjected to rolling and folding tests. Based on the light transmission phenomenon of multiple first electrode sheets, the first rolling pressure is adjusted using a dichotomy method between the third rolling pressure threshold and the first rolling pressure threshold or the second rolling pressure threshold, until some first electrode sheets transmit light and some do not when the multiple first electrode sheets are folded after rolling. The first rolling pressure at this time is taken as the maximum rolling pressure of the first electrode sheet. The initial first rolling pressure is the third rolling pressure threshold. The standard compaction density of the first electrode is determined by measuring the compaction density of the first electrode that did not exhibit light transmission during a folding test after rolling multiple first electrode sheets with the maximum rolling pressure.

2. The method for determining the compaction density of the electrode sheet according to claim 1, characterized in that: The step of adjusting the first rolling pressure using a dichotomy method between the third rolling pressure threshold and the first rolling pressure threshold or the second rolling pressure threshold, based on the light transmission phenomenon of multiple first electrodes, includes: If multiple first electrode sheets exhibit light transmission, the first roller pressure is adjusted using a dichotomy method between the third roller pressure threshold and the second roller pressure threshold. If none of the first electrodes transmit light, the first roller pressure is adjusted using a dichotomy method between the third roller pressure threshold and the first roller pressure threshold.

3. The method for determining the compaction density of the electrode sheet according to claim 1, characterized in that: The standard compaction density of the first electrode sheet is determined by measuring the compaction density of the first electrode sheet that did not exhibit light transmission during a folding test after rolling multiple first electrode sheets with the maximum rolling pressure, including: The maximum compaction density of the first electrode sheet that did not exhibit light transmission during the folding test after rolling multiple first electrode sheets with the maximum rolling pressure is taken as the standard compaction density. Alternatively, the average compaction density of the first electrode sheets that did not exhibit light transmission during a folding test after being rolled with the maximum rolling pressure is taken as the standard compaction density.

4. The method for determining the compaction density of the electrode sheet according to any one of claims 1-3, characterized in that: The folding test includes: Fold the first electrode sheet to 180 degrees in the first direction, roll it at least once using the second roller pressure, and then unfold it. If the first electrode sheet does not transmit light, fold the first electrode sheet to 180 degrees in the second direction, roll it at least once using the third roller pressure, and then unfold it to determine whether the first electrode sheet transmits light.

5. The method for determining the compaction density of the electrode sheet according to claim 1, characterized in that: Determining a third roller pressure threshold based on the first roller pressure threshold and the second roller pressure threshold includes: The average of the first and second roller pressure thresholds is used as the third roller pressure threshold.

6. The method for determining the compaction density of the electrode sheet according to claim 1, characterized in that: The first electrode is a lithium-ion battery electrode, a sodium-ion battery electrode, or a potassium-ion battery electrode.

7. The method for determining the compaction density of the electrode sheet according to claim 1, characterized in that, The plurality of first electrodes are of the same type, and the electrode surface density, current collector surface density, and current collector thickness of the plurality of first electrodes are within a preset error range.

8. The method for determining the compaction density of the electrode sheet according to claim 7, characterized in that: The shape of the first electrode is any of the following: circular, elliptical, regular polygonal, rectangular, trapezoidal, and racetrack-shaped.

9. A method for preparing an electrode, characterized in that: The electrode preparation method includes at least the following: Based on the method for determining the compaction density of the electrode sheet as described in any one of claims 1 to 8, the standard compaction density of the electrode sheet of the battery to be prepared is determined. Electrodes are prepared according to the standard compaction density.

10. A method for preparing a battery, characterized in that: The battery manufacturing method includes: producing an electrode based on the electrode manufacturing method as described in claim 9, and further manufacturing the electrode into a battery.

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