Cylindrical lithium-ion battery, flattening device, and flattening method

Abstract

This application relates to a cylindrical lithium-ion battery, a flattening device, and a flattening method, belonging to the field of battery manufacturing technology. The flattening device includes a flattening mechanism, a pressure sensor, and a controller. The flattening mechanism is used to press against the tabs; the pressure sensor is used to output a feedback signal characterizing the pressure borne by the tabs; the controller is communicatively connected to the flattening mechanism and the pressure sensor, and is used to obtain a target characteristic quantity based on the feedback signal, and when the target characteristic quantity is greater than a preset reference quantity, control the flattening mechanism to perform an over-flattening protection action. The flattening device can flatten the tabs of a cylindrical lithium-ion battery, and at least a portion of the tabs forms a flattened layer, the thickness difference H of the flattened layer satisfying: H≤300μm. This cylindrical lithium-ion battery, flattening device, and flattening method can improve the problem of uneven thickness of the flattened layer formed after flattening the tabs, ensuring battery performance.

Description

Technical Field

[0001] This application relates to the field of battery manufacturing technology, specifically to a cylindrical lithium-ion battery, a flattening device, and a flattening method. Background Technology

[0002] In the field of battery manufacturing technology, especially in the manufacture of all-tab cylindrical lithium-ion batteries, the flattened layer formed after the tabs are flattened has a significant impact on battery performance. In related technologies, during the flattening process using a flattening device, the lack of real-time monitoring of the pressure exerted on the tabs can easily lead to over-flattening, meaning the flattening device applies excessive pressure to the tabs. This results in uneven thickness of the flattened layer after flattening, negatively affecting battery performance. Summary of the Invention

[0003] To address the aforementioned technical problems, embodiments of this application provide a cylindrical lithium-ion battery, a flattening device, and a flattening method, which can improve the uneven thickness of the flattened layer formed after the tabs are flattened, thus ensuring battery performance.

[0004] In a first aspect, a cylindrical lithium-ion battery is provided, wherein the daily voltage drop rate K of the cylindrical lithium-ion battery satisfies: K≤2.0mV / d; The breakdown voltage U of the cylindrical lithium-ion battery under the withstand voltage test satisfies: U≥800V; The cylindrical lithium-ion battery includes a cell formed by winding electrode sheets, wherein the electrode sheets are provided with tabs, and at least a portion of the tabs are flattened to form a flattened layer, wherein the thickness difference H of the flattened layer satisfies: H≤300μm.

[0005] The cylindrical lithium-ion battery provided in this application embodiment has its flattened layer thickness difference H strictly controlled within a certain range, that is, H satisfies: H≤300μm, which can effectively improve the problem of uneven thickness of the flattened layer formed after the tab is flattened, and ensure the performance of the battery.

[0006] According to a first aspect of this application, the electrode includes a positive electrode, a separator, and a negative electrode stacked together, wherein the positive tabs on the positive electrode and the negative tabs on the negative electrode are flattened to form different flattened layers; the flattened layers and the separator are distributed at intervals along the height direction of the electrode.

[0007] According to a first aspect of this application, the distance between the side of the flattening layer away from the diaphragm and the side of the diaphragm near the flattening layer along the height direction of the electrode sheet is A, wherein A satisfies: A≥0.1mm.

[0008] According to a first aspect of this application, a portion of the positive electrode is coated with a first coating, and a portion of the negative electrode is coated with a second coating. The distance between the smoothing layer and the first coating along the height direction of the electrode sheet is B1, and B1 satisfies: B1≥500μm; The distance between the smoothing layer and the second coating along the height direction of the electrode sheet is B2, and B2 satisfies: B2≥500μm.

[0009] Secondly, a flattening device is also provided for flattening the tabs of a cylindrical lithium-ion battery as described in the previous embodiment; The kneading device includes: A flattening mechanism is used to press against the electrode tabs; A pressure sensor is used to output a feedback signal characterizing the pressure exerted on the electrode tab; The controller is communicatively connected to the kneading mechanism and the pressure sensor. The controller is used to obtain the target characteristic value based on the feedback signal, and when the target characteristic value is greater than a preset reference value, it controls the kneading mechanism to perform an over-kneading protection action.

[0010] The flattening device provided in this application embodiment can monitor the pressure on the tab in real time during the flattening process using a pressure sensor. The controller can control the flattening mechanism to perform over-flattening protection when the target characteristic value is greater than the preset reference value (there is a risk of over-flattening), thereby reducing or removing the pressure of the flattening mechanism on the tab and preventing over-flattening. This can improve problems such as uneven thickness of the flattened layer formed after the tab is flattened, diaphragm damage, short circuit between positive and negative electrodes, and short circuit between the tab and the shell, effectively ensuring the performance of the cylindrical lithium-ion battery.

[0011] According to a second aspect of this application, the kneading mechanism includes: A flattening roller is used to press against the electrode tabs; A driving component is connected to the kneading roller, and the driving component is communicatively connected to the controller; The pressure sensor is located inside the kneading roller; or, the pressure sensor is located between the kneading roller and the drive component.

[0012] Thirdly, a kneading method is also provided, which is applied to the kneading device as described in the previous embodiment; The kneading method includes: Obtain the feedback signal output by the pressure sensor; Based on the feedback signal, the target feature quantity is obtained; If the target feature value is greater than the preset reference value, the kneading mechanism is controlled to perform an over-kneading protection action.

[0013] The flattening method provided in this application obtains the feedback signal output by a pressure sensor, then calculates the target feature value based on the feedback signal. When the target feature value is greater than a preset reference value, it determines that there is a risk of over-flattening in the current flattening process, and then controls the flattening mechanism to perform an over-flattening protection action. In this way, the pressure of the flattening mechanism on the tab can be reduced or eliminated, which can prevent over-flattening problems and improve problems such as uneven thickness of the flattened layer formed after the tab is flattened, diaphragm damage, short circuit between positive and negative electrodes, and short circuit between the tab and the shell, effectively ensuring the performance of the cylindrical lithium-ion battery.

[0014] According to a third aspect of this application, the target feature quantity includes the pressure value applied to the electrode tab; the preset reference quantity includes a preset pressure threshold; and / or, The target feature quantity includes the rate of change of pressure on the electrode; the preset reference quantity includes a preset pressure change rate threshold.

[0015] According to a third aspect of this application, the target feature quantity includes the integral value of the pressure on the electrode tab and the feed distance of the kneading mechanism; the preset reference quantity includes a preset integral threshold.

[0016] According to a third aspect of this application, the over-kneading protection action includes at least one of the following actions: issuing an alarm signal, reducing the feed speed of the kneading mechanism, stopping the kneading mechanism from continuing to feed, and controlling the kneading mechanism to retract. Attached Figure Description

[0017] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0018] Figure 1 This is a schematic diagram of the structure of a cylindrical lithium-ion battery provided as an exemplary embodiment of this application.

[0019] Figure 2 This is a schematic diagram of the structure of an electrode sheet provided for an exemplary embodiment of this application.

[0020] Figure 3 This is a schematic diagram of the structure of a kneading device provided for an exemplary embodiment of this application.

[0021] Figure 4 This is a schematic flowchart of a kneading method provided for an exemplary embodiment of this application.

[0022] Figure 5This is a schematic diagram of the controller provided as an exemplary embodiment of this application.

[0023] Reference numerals: 100-Cylindrical lithium-ion battery; 110-Casing; 120-Cell; 130-Electrode; 131-Taper; 132-Smoothing layer; 133-Positive electrode; 134-Separator; 135-Negative electrode; 136-First coating; 137-Second coating; 200-Smoothing device; 210-Smoothing mechanism; 211-Smoothing roller; 212-Driver; 220-Pressure sensor; 230-Controller; 231-Processor; 232-Memory; 233-Input device; 234-Output device. Detailed Implementation

[0024] Hereinafter, exemplary embodiments according to this application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein.

[0025] In the manufacturing of all-tab cylindrical lithium-ion batteries, the flattened layer formed after the tabs are flattened has a significant impact on battery performance. Related technologies use a flattening device to flatten the tabs, applying continuous pressure to cause the tabs to bend and form the flattened layer. During this process, due to the lack of real-time monitoring of the pressure exerted on the tabs, over-flattening can easily occur, meaning the flattening device applies excessive pressure to the tabs. This results in uneven thickness of the flattened layer after flattening, affecting battery performance.

[0026] To overcome the above problems, this embodiment of the application uses a pressure sensor to detect the force on the tabs and sends a feedback signal accordingly. The smoothing mechanism is then controlled based on this feedback signal. Specifically, a target characteristic value is obtained from the feedback signal. When the target characteristic value exceeds a preset reference value, an over-kneading risk is identified, and the smoothing mechanism is promptly controlled to perform an over-kneading protection action. This avoids over-kneading, resulting in a smoothed layer thickness variation of less than or equal to 300 μm, effectively improving the uneven thickness of the smoothed layer formed after tab smoothing.

[0027] The cylindrical lithium-ion battery, the kneading device, and the kneading method provided in the embodiments of this application will be described in detail below.

[0028] Figure 1 This is a schematic diagram of the structure of a cylindrical lithium-ion battery provided as an exemplary embodiment of this application. Figure 2 This is a schematic diagram of the structure of an electrode sheet provided for an exemplary embodiment of this application. Figure 1 and Figure 2As shown, the cylindrical lithium-ion battery 100 provided in this embodiment may include a housing 110 and a cell 120. The cell 120 is disposed within the housing 110, and the housing 110 protects the cell 120. The cell 120 may be formed by winding electrode sheets 130. During the winding process, blank areas on the electrode sheets 130 that are not coated with any coating may form tabs 131. Through a subsequent flattening process, at least a portion of the tabs 131 may be flattened to form a flattened layer 132. This flattened layer 132 may be used to connect a busbar, facilitating the connection of external electrical components.

[0029] The cylindrical lithium-ion battery 100 provided in this application embodiment improves the problem of uneven thickness of the flattened layer 132 formed after the tab 131 is flattened, and its excellent comprehensive performance can be reflected in the following multiple indicators. Specifically: The first parameter indicator: such as Figure 2 As shown, the thickness range H of the leveling layer 132 satisfies H≤300μm. Here, "thickness range" can be understood as the thickness difference along the height direction of the electrode 130 (refer to...). Figure 2 Along the Z-axis direction, the difference between the thickness of the thickest and thinnest parts of the leveled layer 132. It should be noted that during the leveling process, the pressure on the tab 131 may not be completely uniform, resulting in differences in the thickness of different parts of the formed leveled layer 132. The leveling device 200 of this application (…) Figure 3 As shown in the diagram (details to be provided later) and the smoothing method (details to be provided later), this thickness difference can be strictly controlled within a certain range (i.e., H≤300μm), effectively improving the problem of uneven thickness of the smoothed layer 132 formed after smoothing the tab 131. A smoothed layer 132 with uniform thickness has at least the following beneficial effects: First, when the smoothed layer 132 is subsequently welded to the busbar, it can avoid the problem of weak welding due to localized excessive thinness of the smoothed layer 132; second, the uniform thickness of the smoothed layer 132 means that the tab 131 material is uniformly compacted, and the stress distribution inside the tab 131 is more reasonable, which can improve the problem of localized stress concentration in the smoothed layer 132. These beneficial effects can play a positive role in the performance of the battery.

[0030] The second parameter is the daily voltage drop rate K of the cylindrical lithium-ion battery 100: K ≤ 2.0 mV / d. Here, "mV / d" refers to "millivolts per day". Specific testing methods for the K value are documented in relevant technical records and will not be elaborated here. A K value of no more than 2.0 mV / d means that the voltage decay of the cylindrical lithium-ion battery 100 is extremely slow, exhibiting excellent self-discharge performance and keeping capacity decay at a very low level. This parameter indirectly proves that the leveling layer 132 and the busbar have a high-quality welding structure, and indirectly indicates that the thickness of the leveling layer 132 is very uniform.

[0031] The third parameter is the breakdown voltage U of the cylindrical lithium-ion battery 100 under a withstand voltage test (commonly known as a Hipot test), which must be U ≥ 800V. The Hipot test is generally used to verify the insulation strength between the positive and negative electrodes inside the battery. Specific test methods are documented in relevant technologies and will not be elaborated here. A breakdown voltage U of not less than 800V indicates that the insulating medium inside the cylindrical lithium-ion battery 100 can withstand a strong electric field without being damaged. In the flattening process of the tab 131, improper process control can lead to over-flattening, damaging the battery and severely weakening the insulating medium's ability to withstand high voltage, resulting in a decrease in the breakdown voltage U. Therefore, U ≥ 800V indirectly proves that the flattening process of this application successfully avoids the above-mentioned problems, ensuring that the cylindrical lithium-ion battery 100 has an extremely high breakdown voltage and improving the overall safety performance of the cylindrical lithium-ion battery 100.

[0032] It should be noted that the above three indicators are interrelated. If the cylindrical lithium-ion battery 100 has an excessively crumpled structure, the thickness difference H of the flattened layer 132 cannot meet the requirement of H≤300μm. This will also lead to an excessively high K value (failing to meet K≤2.0mV / d) and an excessively low breakdown voltage U (failing to meet U≥800V). Conversely, if the thickness of the flattened layer 132 of the cylindrical lithium-ion battery 100 is uniform (the thickness difference H meets the requirement of H≤300μm), it is beneficial to achieve a lower K value (K≤2.0mV / d) and a higher breakdown voltage U value (U≥800V).

[0033] like Figure 2 As shown, the electrode 130 may include a positive electrode 133, a separator 134, and a negative electrode 135 stacked together. The positive tabs on the positive electrode 133 and the negative tabs on the negative electrode 135 are flattened to form different flattened layers 132 (distributed at opposite ends of the electrode 130 along the Z-axis). The flattened layers 132 and the separator 134 are along the height direction of the electrode 130 (reference). Figure 2 The Z-axis spacing in the middle is arranged so that the diaphragm 134 can be prevented from being directly squeezed and damaged by the tab 131 during the kneading process, and the positive electrode 133 and the negative electrode 135 can be prevented from contacting and short-circuiting.

[0034] like Figure 2 As shown, the distance A along the height direction of the electrode 130 is between the side of the leveling layer 132 away from the diaphragm 134 and the side of the diaphragm 134 close to the leveling layer 132. If A is too small, the diaphragm 134 will be too close to the leveling layer 132. During the leveling process, the leveling layer 132 will easily come into contact with the diaphragm 134, causing wrinkles or even tears at the end of the diaphragm 134, which will seriously damage the insulation performance of the diaphragm 134 and increase the risk of short circuit.

[0035] Therefore, in this embodiment, A is limited to the following range: A ≥ 0.1 mm. This effectively improves the aforementioned problems caused by A being too small. At the same time, since A is limited to ≥ 0.1 mm, the insulation performance of the diaphragm 134 can be guaranteed, which is also beneficial to achieving the aforementioned breakdown voltage U satisfying: U ≥ 800 V.

[0036] In one embodiment, A can be 0.15mm, 0.3mm, 0.5mm or 1.0mm.

[0037] like Figure 2 As shown, a portion of the positive electrode 133 is coated with a first coating 136, and a portion of the negative electrode 135 is coated with a second coating 137. In practical applications, typically the area of ​​the positive electrode 133 used for subsequent formation of the positive electrode tab is not coated with the first coating 136, while other areas are coated with the first coating 136. Similarly, the area of ​​the negative electrode 135 used for subsequent formation of the negative electrode tab is not coated with the second coating 137, while other areas are coated with the second coating 137. The specific materials of the first coating 136 and the second coating 137 are described in related technologies and will not be repeated here.

[0038] like Figure 2 As shown, taking the flattened layer 132 formed by the negative electrode tab of the negative electrode 135 as an example, the distance between the flattened layer 132 and the second coating 137 along the height direction of the electrode 130 is B2. If B2 is too small, during the flattening process, the second coating 137 is subjected to pressure, and the active material particles inside it may migrate to the flattened layer 132, or the flattened layer 132 may come into contact with the second coating 137, which may cause a short circuit in the battery and pose a safety risk.

[0039] Therefore, in this application embodiment, B2 is limited to the following range: B2≥500μm, which can effectively improve the problem caused by the aforementioned B2 being too small.

[0040] Similarly, for the flattened layer 132 formed by the positive tab of the positive electrode 133, the distance between the flattened layer 132 and the first coating 136 along the height direction of the electrode 130 is B1. If B1 is too small, during the flattening process, the first coating 136 is subjected to pressure, and the active material particles inside it may migrate to the flattened layer 132, or the flattened layer 132 may come into contact with the first coating 136, which may cause a short circuit in the battery and pose a safety risk.

[0041] Therefore, in this application embodiment, B1 is limited to the following range: B1 ≥ 500 μm, which can effectively improve the problem caused by the aforementioned excessively small B1.

[0042] In one embodiment, B1 can be selected from 500μm, 600μm, 1000μm, etc.

[0043] In one embodiment, B2 can be selected from 500μm, 600μm, 1000μm, etc.

[0044] Figure 3 This is a schematic diagram of the structure of a kneading device provided for an exemplary embodiment of this application. Figure 3 As shown, the kneading device 200 provided in this application embodiment can be used to knead the tabs 131 of the cylindrical lithium-ion battery 100 described in the foregoing embodiment, so that the cylindrical lithium-ion battery 100 can meet the above-mentioned multiple performance parameters.

[0045] like Figure 3 As shown, the kneading device 200 may include a kneading mechanism 210, a pressure sensor 220, and a controller 230. Figure 5 (As shown in the diagram). The function of the kneading mechanism 210 is to press against the aforementioned tab 131, causing the tab 131 to form a kneaded layer 132. The pressure sensor 220 can detect the pressure on the tab 131 during the kneading process and output a feedback signal characterizing the pressure borne by the tab 131. The controller 230 is communicatively connected to the kneading mechanism 210 and the pressure sensor 220. The controller 230 can send control commands to the kneading mechanism 210 to control the kneading mechanism 210 to perform the kneading action.

[0046] It should be noted that after receiving the feedback signal output by the pressure sensor 220, the controller 230 can obtain the target characteristic quantity (which may include pressure value, pressure change rate, integral value of pressure and feed distance, etc., which will be described in detail later) based on the feedback signal. The controller 230 internally stores preset reference values, which are pre-set thresholds representing the safety boundary of the kneading process. The preset reference values ​​correspond to the target characteristic quantities, that is, the preset reference values ​​may correspond to preset pressure thresholds, preset pressure change rate thresholds, preset integral thresholds, etc. (which will be described in detail later). The controller 230 compares the target feature quantity with the preset reference quantity. If the target feature quantity is greater than the preset reference quantity, the controller 230 will determine that there is a risk of over-kneading in the current kneading process, that is, the pressure applied to the tab 131 is too large, which may lead to problems such as uneven thickness of the kneading layer 132, damage to the diaphragm 134, short circuit between the positive and negative electrodes, and short circuit between the tab 131 and the housing 110. At this time, the controller 230 will control the kneading mechanism 210 to perform over-kneading protection actions, such as issuing an alarm signal, reducing the feed speed of the kneading mechanism 210, stopping the kneading mechanism 210 from continuing to feed, and controlling the kneading mechanism 210 to retract.

[0047] In other words, the flattening device 200 provided in this application embodiment can monitor the pressure on the tab 131 in real time during the flattening process using a pressure sensor. Furthermore, when the target feature quantity is greater than a preset reference quantity (there is a risk of over-flattening), the controller 230 can control the flattening mechanism 210 to perform an over-flattening protection action, reducing or removing the pressure of the flattening mechanism 210 on the tab 131. This can prevent over-flattening problems and improve issues such as uneven thickness of the flattened layer 132 formed after flattening the tab 131, damage to the separator 134, short circuit between the positive and negative electrodes, and short circuit between the tab 131 and the shell 110. This effectively ensures the performance of the cylindrical lithium-ion battery 100.

[0048] like Figure 3 As shown, the kneading mechanism 210 may include a kneading roller 211 and a drive member 212. The kneading roller 211 is typically responsible for direct contact with the tab 131 and for pressing against the tab 131. The drive member 212 is connected to the kneading roller 211 and can provide linear feed motion to the kneading roller 211, driving the kneading roller 211 to perform kneading operations on the tab 131.

[0049] In one embodiment, the drive unit 212 may include a cylinder, an electric cylinder, a hydraulic cylinder, etc.

[0050] In one embodiment, the drive member 212 and the kneading wheel 211 can be connected by transmission through components such as gears and lead screws.

[0051] like Figure 3 As shown, the pressure sensor 220 is positioned between the drive member 212 and the kneading roller 211. In practical applications, the drive member 212 drives the kneading roller 211 to apply pressure to the tab 131. The pressure applied by the kneading roller 211 to the tab 131 is approximately equal to the forward thrust of the drive member 212 pushing the kneading roller 211. Therefore, by placing the pressure sensor 220 between the drive member 212 and the kneading roller 211, the pressure applied by the kneading roller 211 to the tab 131 can be obtained by detecting the thrust of the drive member 212 on the kneading roller 211. In this way, the controller 230 can quickly and accurately obtain feedback signals, which helps the controller 230 to determine in a timely and accurate manner whether there is a risk of over-kneading in the current kneading process.

[0052] In one embodiment, the pressure sensor 220 can also be disposed within the kneading roller 211. For example, the pressure sensor 220 can be embedded in or attached to the load-bearing structure inside the kneading roller 211. After the kneading roller 211 applies pressure to the tab 131, the kneading roller 211 receives the same reaction force. The pressure sensor 220 can directly detect the pressure of the kneading roller 211 on the tab 131 by detecting the reaction force. The detection result is not easily affected by other frictional forces, inertia, etc. In this way, the controller 230 can obtain feedback signals more accurately, which is beneficial for the controller 230 to determine in a timely and accurate manner whether there is a risk of over-kneading in the current kneading process.

[0053] Figure 4 This is a schematic flowchart illustrating a kneading method provided for an exemplary embodiment of this application. Figure 4 As shown, the kneading method provided in this application embodiment is applied to the kneading device described in the previous embodiment, and the kneading method includes: S410: Acquire the feedback signal output by the pressure sensor.

[0054] S420: Obtain the target feature quantity based on the feedback signal.

[0055] S430: If the target feature value is greater than the preset reference value, control the kneading mechanism to perform over-kneading protection action.

[0056] The flattening method provided in this application obtains the feedback signal output by a pressure sensor, then calculates the target feature value based on the feedback signal. When the target feature value is greater than a preset reference value, it determines that there is a risk of over-flattening in the current flattening process, and then controls the flattening mechanism to perform an over-flattening protection action. In this way, the pressure of the flattening mechanism on the tab can be reduced or eliminated, which can prevent over-flattening problems and improve problems such as uneven thickness of the flattened layer formed after the tab is flattened, diaphragm damage, short circuit between positive and negative electrodes, and short circuit between the tab and the shell, effectively ensuring the performance of the cylindrical lithium-ion battery.

[0057] It should be understood that after performing steps S410, S420 and S430, the thickness range H of the kneaded layer can meet the aforementioned condition: H≤300μm, and the thickness of the kneaded layer is more uniform and reliable.

[0058] In one embodiment, before step S410, a robotic arm can be used to place the core in the flattening station, and then the flattening mechanism can be driven to feed the core. In this way, the pressure sensor can monitor the contact pressure between the flattening mechanism and the tab in real time.

[0059] In one embodiment, the target characteristic quantity may include the pressure value experienced by the tab; correspondingly, the preset reference quantity includes a preset pressure threshold. It should be noted that when the pressure value experienced by the tab exceeds the preset pressure threshold, it can be considered that the pressure locally experienced by the tab has exceeded the reasonable deformation range of the metal foil. Therefore, it can be determined that there is a risk of over-kneading in the current flattening process.

[0060] In one embodiment, the preset pressure threshold can range from 100N to 300N.

[0061] In one embodiment, the target characteristic quantity may include the rate of change of pressure on the tab, i.e., the increase in pressure per unit time; correspondingly, the preset reference quantity includes a preset pressure change rate threshold. It should be noted that during normal kneading, as the tab is gradually compacted, the resistance increases, the pressure rises steadily, and the rate of pressure change remains within a reasonable range. However, when there is a risk of over-kneading, the normal flow of the tab material will be suddenly obstructed, and this obstruction will cause a sudden change in the rate of pressure change on the tab. Therefore, when the rate of pressure change on the tab is greater than the preset pressure change rate threshold, it can be determined that there is a risk of over-kneading in the current kneading process.

[0062] In one embodiment, the preset pressure change rate threshold can be in the range of 50 N / s to 80 N / s.

[0063] In one embodiment, the target characteristic quantity may include the integral value of the pressure on the electrode and the feed distance of the kneading mechanism, that is, the sum of the work done by the pressure applied by the kneading head of the kneading mechanism over each small distance of advance. Correspondingly, the preset reference quantity includes a preset integral threshold. It should be noted that the integral value of the pressure on the electrode and the feed distance of the kneading mechanism represents the cumulative mechanical energy applied to the electrode from the start of kneading to the current moment. Under normal circumstances, as the kneading mechanism feeds smoothly, the electrode is uniformly compacted, and this integral value will show a steady increase. However, as the electrode is over-compacted, and there is a risk of over-kneading, the excessive pressure energy (the integral value of the pressure on the electrode and the feed distance of the kneading mechanism) will accumulate to a large value. Therefore, if the integral value of the pressure on the electrode and the feed distance of the kneading mechanism is greater than the preset integral threshold, it can be determined that there is a risk of over-kneading in the current kneading process.

[0064] It should be noted that in practical applications, the three target characteristic quantities and their corresponding preset reference quantities can be applied individually or in combination. When applied in combination, they can be combined in an "AND" relationship, meaning that when all three simultaneously satisfy the condition that the target characteristic quantity is greater than the preset reference quantity, the kneading mechanism is controlled to perform an over-kneading protection action; or they can be combined in an "OR" relationship, meaning that when any one of the three satisfies the condition that the target characteristic quantity is greater than the preset reference quantity, the kneading mechanism is controlled to perform an over-kneading protection action. Applying them in combination can effectively avoid misjudgment based on a single indicator and improve the accuracy of over-kneading risk assessment.

[0065] It should be noted that the aforementioned over-kneading protection action may include at least one of the following actions: issuing an alarm signal, reducing the feed speed of the kneading mechanism, stopping the kneading mechanism from continuing to feed, and controlling the retraction of the kneading mechanism.

[0066] It should be understood that issuing an alarm signal can alert staff to the risk of over-kneading during the kneading process, facilitating timely intervention and inspection. Reducing the feed speed of the kneading mechanism can decrease the pressure exerted on the electrode tabs, thus mitigating the risk of over-kneading. Stopping the kneading mechanism from continuing to feed will stop applying pressure to the electrode tabs, preventing further deformation of the tabs. Controlling the retraction of the kneading mechanism can proactively release the pressure already applied to the electrode tabs, quickly eliminating the risk of over-kneading.

[0067] It should be noted that the above-mentioned various protective actions can be selected and executed according to the severity of the over-kneading risk. For example, if the pressure value only slightly exceeds the preset pressure threshold, an alarm signal can be issued, and / or the feed speed of the kneading mechanism can be reduced; if an abnormally high pressure change rate is detected, the kneading mechanism can be stopped from continuing to feed, and the kneading mechanism can be subsequently controlled to retract. This protection mechanism, which coordinates multiple protective actions, can take into account both the continuity of the production process and the reliability of the kneaded layer as much as possible.

[0068] Figure 5 This is a schematic diagram of the controller provided as an exemplary embodiment of this application. Figure 5 As shown, the controller 230 includes one or more processors 231 and memory 232.

[0069] The processor 231 may be a central processing unit (CPU) or other form of processing unit with data processing capabilities and / or instruction execution capabilities, and may control other components in the controller 230 to perform desired functions.

[0070] The memory 232 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 231 may execute the program instructions to implement the control methods and / or other desired functions of the various embodiments of this application described above. Various contents such as input signals, signal components, and noise components may also be stored in the computer-readable storage medium.

[0071] In one example, controller 230 may also include input device 233 and output device 234, which are interconnected via a bus system and / or other forms of connection mechanism (not shown).

[0072] When the controller is a standalone device, the input device 233 can be a communication network connector for receiving the acquired input signals from the first device and the second device.

[0073] In addition, the input device 233 may also include, for example, a keyboard, a mouse, etc.

[0074] The output device 234 can output various information to the outside, including determined distance information, direction information, etc. The output device 234 may include, for example, a display, a speaker, a printer, and a communication network and its connected remote output devices, etc.

[0075] Of course, for the sake of simplicity, Figure 5 Only some of the components of the controller 230 relevant to this application are shown in this illustration; components such as buses, input / output interfaces, etc., are omitted. In addition, the controller 230 may include any other suitable components depending on the specific application.

[0076] The computer program product can be written in any combination of one or more programming languages ​​to perform the operations of the embodiments of this application. The programming languages ​​include object-oriented programming languages ​​such as Java and C++, as well as conventional procedural programming languages ​​such as C or similar languages. The program code can be executed entirely on the user's computing device, partially on the user's computing device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0077] The computer-readable storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof.

[0078] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0079] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0080] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0081] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A cylindrical lithium-ion battery, characterized in that, The daily voltage drop rate K of the cylindrical lithium-ion battery satisfies: K≤2.0mV / d; The breakdown voltage U of the cylindrical lithium-ion battery under the withstand voltage test satisfies: U≥800V; The cylindrical lithium-ion battery includes a cell formed by winding electrode sheets, wherein the electrode sheets are provided with tabs, and at least a portion of the tabs are flattened to form a flattened layer, wherein the thickness difference H of the flattened layer satisfies: H≤300μm.

2. The cylindrical lithium-ion battery according to claim 1, characterized in that, The electrode includes a positive electrode, a separator, and a negative electrode stacked together. The positive tabs on the positive electrode and the negative tabs on the negative electrode are flattened to form different flattened layers. The flattened layers and the separator are distributed at intervals along the height direction of the electrode.

3. The cylindrical lithium-ion battery according to claim 2, characterized in that, The distance between the side of the flattening layer away from the diaphragm and the side of the diaphragm close to the flattening layer along the height direction of the electrode sheet is A, and A satisfies: A≥0.1mm.

4. The cylindrical lithium-ion battery according to claim 2, characterized in that, A portion of the positive electrode is coated with a first coating, and a portion of the negative electrode is coated with a second coating. The distance between the smoothing layer and the first coating along the height direction of the electrode sheet is B1, and B1 satisfies: B1≥500μm; The distance between the smoothing layer and the second coating along the height direction of the electrode sheet is B2, and B2 satisfies: B2≥500μm.

5. A kneading and leveling device, characterized in that, Used to flatten the tabs of a cylindrical lithium-ion battery as described in any one of claims 1 to 4; The kneading device includes: A flattening mechanism is used to press against the electrode tabs; A pressure sensor is used to output a feedback signal characterizing the pressure exerted on the electrode tab; The controller is communicatively connected to the kneading mechanism and the pressure sensor. The controller is used to obtain the target characteristic value based on the feedback signal, and when the target characteristic value is greater than a preset reference value, it controls the kneading mechanism to perform an over-kneading protection action.

6. The kneading and leveling device according to claim 5, characterized in that, The kneading mechanism includes: A flattening roller is used to press against the electrode tabs; A driving component is connected to the kneading roller, and the driving component is communicatively connected to the controller; The pressure sensor is located inside the kneading roller; or, the pressure sensor is located between the kneading roller and the drive component.

7. A method for kneading and smoothing, characterized in that, Applied to the kneading and leveling device as described in claim 5 or 6; The kneading method includes: Obtain the feedback signal output by the pressure sensor; Based on the feedback signal, the target feature quantity is obtained; If the target feature value is greater than the preset reference value, the kneading mechanism is controlled to perform an over-kneading protection action.

8. The kneading method according to claim 7, characterized in that, The target feature quantity includes the pressure value experienced by the electrode tab; the preset reference quantity includes a preset pressure threshold; and / or, The target feature quantity includes the rate of change of pressure on the electrode tab; the preset reference quantity includes a preset pressure change rate threshold.

9. The kneading method according to claim 7, characterized in that, The target feature quantity includes the integral value of the pressure on the electrode tab and the feed distance of the kneading mechanism; the preset reference quantity includes a preset integral threshold.

10. The kneading method according to claim 7, characterized in that, The over-kneading protection action includes at least one of the following actions: issuing an alarm signal, reducing the feed speed of the kneading mechanism, stopping the kneading mechanism from continuing to feed, and controlling the kneading mechanism to retract.

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