Pole piece and pole piece drying method

Abstract

The application discloses an electrode piece and a drying method of the electrode piece. The appearance defect rate of the electrode piece is less than 0.4% when the drying speed of the electrode piece changes. The drying method comprises the following steps: a speed sensor monitors the moving speed of the electrode piece in real time; a controller compares the moving speed with a target speed, and adjusts the drying parameters of a drying device based on the comparison result. By dynamically matching the moving speed and the drying intensity, the electrode piece is uniformly dried under the variable speed working condition, the over-drying and cracking problem caused by abnormal speed reduction or shutdown is solved, and the appearance defect rate is effectively reduced to below 0.4%.

Description

Technical Field

[0001] This application relates to the field of battery manufacturing technology, specifically to an electrode sheet and a method for drying the electrode sheet. Background Technology

[0002] In the continuous production process of lithium-ion battery electrode coating, ovens are typically used to dry wet electrodes with convective hot air. In actual production, factors such as substrate joints, tension fluctuations, and upstream / downstream equipment malfunctions inevitably lead to unplanned deceleration, low-speed operation, or even temporary shutdowns of the coating conveyor belt. Ensuring uniform electrode drying quality and avoiding appearance defects due to over- or under-drying under these abnormal conditions remains a key technical challenge in this field.

[0003] In related technologies, oven drying control generally adopts a fixed open-loop control scheme that matches the normal rated production speed. Specifically, when the production line is running at a normal, uniform speed, the hot air circulation fan and exhaust fan operate at a preset constant frequency, providing a constant hot air volume and drying intensity. When the production line experiences an abnormal speed reduction or shutdown, the operating parameters of the aforementioned fans remain unchanged, resulting in a significant increase in the actual residence time of the wet electrode sheets in the oven, thus subjecting them to excessive hot air convection energy. Since the drying intensity cannot be dynamically adjusted according to the actual moving speed of the electrode sheets, the solvent on the surface of the electrode sheets evaporates too quickly while the internal solvent fails to escape synchronously, easily leading to irreversible defects such as surface dry shells, microcracks, and even coating powdering. At the same time, since speed fluctuations are often sudden, relying on manual observation and manually lowering the fan frequency or heating temperature has a significant lag, making it difficult to respond promptly to speed changes. Furthermore, if adjusting the heating temperature is used as a countermeasure, the temperature rise and fall response speed is slow and cannot adapt to millisecond-level speed changes, and sudden temperature changes may cause temperature field disturbances inside the oven, leading to new problems such as uneven drying or solvent residue.

[0004] Therefore, for the lithium electrode coating and drying process, existing technologies are insufficient to effectively prevent over-drying of the electrodes due to prolonged residence time when dealing with unplanned speed reductions, shutdowns, and speed fluctuations. This results in a persistently high rate of localized defects in the electrode appearance and increased waste. Real-world production urgently requires a control method that can adjust the drying intensity in real-time and rapidly match the actual residence time of the electrodes under abnormal operating conditions. Summary of the Invention

[0005] In view of this, this application provides an electrode sheet that at least solves the problem of high external light defect rate when the electrode sheet drying speed changes. This application also provides a method for drying the electrode sheet to obtain the aforementioned electrode sheet.

[0006] To achieve the above objectives, this application provides the following technical solution: An electrode sheet in which the local appearance defect rate is less than 0.4% when the drying speed of the electrode sheet changes.

[0007] A method for drying electrode sheets, used to dry electrode sheets to be dried, the method for drying electrode sheets includes at least the following steps: S001: Turn on the drying device to dry the electrode sheets to be dried; S002: The drying device is equipped with a speed sensor, which monitors the electrode in real time and obtains the moving speed of the electrode; S003: The controller compares the moving speed with the target speed and obtains the comparison result, and adjusts the drying parameters of the drying device for the electrode based on the comparison result.

[0008] Optionally, the drying parameters are the drying speed or drying frequency of the electrode sheet by the drying device.

[0009] Optionally, the drying device includes an air supply device and an exhaust device, and adjusting the drying parameters of the drying device for the electrode includes: synchronously adjusting the operating parameters of the air supply device and the operating parameters of the exhaust device according to a preset ratio.

[0010] Optionally, adjusting the drying parameters of the drying device for the electrode based on the comparison result includes: the controller calculating the speed change slope according to the moving speed of the electrode, and selecting a first response mode or a second response mode to adjust the rate of change of the drying parameters according to whether the speed change slope exceeds a predetermined slope threshold, wherein the rate of change of the first response mode is less than the rate of change of the second response mode.

[0011] Optionally, adjusting the drying parameters of the drying device for the electrode sheet includes: when the speed sensor detects that the moving speed of the electrode sheet is increasing, the controller causes the drying parameters to gradually increase.

[0012] Optionally, the controller may also apply a delay filtering procedure to the moving speed detected by the speed sensor, and adjust the drying parameters of the drying device only if the speed change indicated by the moving speed continues for more than a predetermined delay period.

[0013] Optionally, it further includes: detecting whether the drying parameters have reached a preset limit value, and generating an alarm signal when the drying parameters reach the preset limit value, while adjusting the heating temperature of the drying device as a secondary compensation.

[0014] Optionally, the controller further includes: determining the speed range of the moving speed based on the moving speed, and adjusting the drying parameters to a value corresponding to the speed range based on a preset mapping relationship between the moving speed and the drying parameters.

[0015] Optionally, the speed range includes at least a normal speed range, a low speed range, and a stop range, and the mapping relationship between the preset moving speed and the drying parameters is as follows: in the normal speed range, the drying parameters of the drying device maintain the rated standard value; in the low speed range, the drying parameters of the drying device decrease linearly as the moving speed decreases; in the stop range, the drying parameters of the drying device drop to the minimum standby value.

[0016] According to the embodiments of the present invention, the electrode moving speed is collected in real time during the production process and the drying intensity is dynamically adjusted accordingly. This ensures that the drying capacity matches the actual residence time of the electrode in the drying oven, thereby effectively preventing over-drying of the electrode when abnormal speed reduction, shutdown, or speed fluctuation occurs on the production line. This avoids appearance defects such as surface dry shells, micro-cracks, and powder shedding. The local appearance defect rate of the electrode when the drying speed changes is reliably controlled to below 0.4%, significantly improving the quality consistency and production yield of the electrode. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 This is a flowchart of the electrode drying method provided in this embodiment. Detailed Implementation

[0019] This application provides an electrode sheet that at least solves the problem of high external light defect rate when the electrode sheet drying speed changes. This application also provides a method for drying the electrode sheet to obtain the aforementioned electrode sheet.

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] During the continuous coating production of lithium electrode sheets, factors such as substrate joints, abnormal tension, and upstream and downstream equipment malfunctions frequently cause unplanned deceleration, low-speed operation, and short-term emergency stops in the coating conveyor belt. Under these abnormal conditions, the residence time of the electrode sheets in the drying oven increases significantly, easily leading to appearance defects such as over-drying cracking and coating powdering. How to reduce the appearance defect rate of electrode sheets when the drying speed changes is the technical problem that this application aims to solve.

[0022] Research has revealed that in coating production lines using related technologies, when abnormal speed changes or shutdowns occur, the drying parameters of the oven remain constant. This leads to frequent appearance defects in the electrodes due to over-drying, such as dry cracks, edge cracking, and coating powdering, resulting in a persistently high scrap rate. These changes in drying speed include speed variations caused by unplanned deceleration, low-speed operation, and short-term emergency stops. The appearance defects include one or more of the following: electrode dry cracks, edge cracking, coating powdering, and areal density deviation. These defects are typical irreversible appearance and property defects caused by over-drying.

[0023] To address the aforementioned issues, this application provides an electrode sheet whose appearance defect rate is less than 0.4% in areas where the drying speed changes. Here, an appearance defect rate of less than 0.4% indicates that the area or number of electrode sheets with appearance defects in the localized area where the drying speed changes is less than 0.4% of the total area or number of electrode sheets in that localized area. By controlling the electrode drying process, the appearance defect rate in the localized area where the drying speed changes is kept below 0.4%, thereby significantly reducing the amount of waste sheets generated under abnormal operating conditions and improving batch consistency of the electrode sheets. The protection scope focuses on the specific operating condition of abnormal speed changes in the production line, precisely covering electrode over-drying defects caused by sudden speed reductions due to malfunctions, unplanned shutdowns, etc., which differs from the conventional positive matching scheme of uniform speed production speed adjustment. Simultaneously, limiting the appearance defect rate to below 0.4% significantly reduces the waste rate compared to the frequent occurrence of large-volume over-drying defects under abnormal operating conditions, reducing the loss of raw materials such as foil and slurry.

[0024] The above has explained the problem of over-drying defects faced by electrodes under varying drying speed conditions. The following further describes the drying method for achieving the aforementioned low appearance defect rate. In the continuous production process of electrode coating, the production line is frequently affected by factors such as substrate joints, abnormal tension, and equipment malfunctions, often resulting in unplanned deceleration, low-speed operation, and short-term emergency stops. In related technologies, the oven drying control logic only matches fixed open-loop parameters to the normal rated line speed. Once the production line experiences a sudden abnormal speed change or shutdown, the drying parameters remain constant, leading to over-drying and cracking defects in the electrodes due to prolonged residence time. Furthermore, manual adjustment suffers from significant lag and inconsistency. How to achieve adaptive adjustment of drying parameters according to changes in the electrode's moving speed to avoid over-drying defects under abnormal conditions is another technical problem that this application aims to solve.

[0025] To address this problem, embodiments of this application provide a method for drying electrode sheets, used to dry electrode sheets to be dried. Please refer to... Figure 1 The electrode to be dried can be, for example, a wet electrode after the slurry coating process in the lithium electrode coating step, which is about to enter the oven for solvent evaporation. In other embodiments, the electrode to be dried can also be other types of battery electrodes or thin film materials that require coating drying treatment. The drying method of the electrode includes at least the following steps: First, the drying device is turned on to dry the electrode sheets to be dried. This drying device can be, for example, an oven in a coating production line, and can include multiple drying sections, each with independent drying parameters.

[0026] Then, a speed sensor is installed inside the drying unit to monitor the electrode sheets in real time and obtain their moving speed. This speed sensor can be, for example, a coating line speed encoder, capable of millisecond-level high-frequency acquisition to obtain the current conveyor belt speed in real time. By acquiring the real-time moving speed of the electrode sheets at millisecond-level high frequency, timely and accurate speed information is provided to the controller, enabling the closed-loop control logic to quickly detect changes in production line speed and adapt to speed changes caused by various sudden faults and instantaneous tension fluctuations. In addition, this speed sensor can directly read the existing servo speed signal of the production line without the need for additional detection probes. In this way, the existing servo speed signal of the production line is reused as input, eliminating the need for additional hardware sensors and mechanical structures, resulting in extremely low hardware modification costs. It can be directly adapted to various models of coating ovens on the market, demonstrating strong versatility.

[0027] Next, the controller compares the moving speed with the target speed and obtains the comparison result. Based on the comparison result, it adjusts the drying parameters of the drying device for the electrode sheets. The target speed can be, for example, the rated line speed during normal production or a pre-set reference speed value. The controller can be, for example, a Programmable Logic Controller (PLC) closed-loop main control unit. Using a PLC as the closed-loop main control unit enables fully automatic closed-loop operation, automatically adjusting drying parameters according to the line speed signal throughout the process. No manual monitoring of speed changes and manual parameter adjustments are required, eliminating human intervention errors and adapting to continuous 24-hour mass production. The comparison result can include, for example, the difference or ratio between the moving speed and the target speed, or the speed range of the moving speed relative to the target speed. By quantitatively comparing the moving speed with the target speed, a clear adjustment basis is provided to the controller, establishing a definite quantitative relationship between the adjustment amount of the drying parameters and the speed deviation, avoiding blind and arbitrary adjustments.

[0028] The aforementioned drying method uses a speed sensor within the drying unit to monitor the electrode's moving speed in real time. The controller compares this speed with a target speed and automatically adjusts drying parameters based on the comparison, forming a closed-loop linkage control system for both speed and drying parameters. This closed-loop logic allows the drying parameters to adaptively adjust to changes in the actual electrode's moving speed. This dynamically matches the drying intensity with the actual residence time of the electrode within the drying unit during abnormal speed changes or shutdowns, controlling the solvent evaporation rate from the source of convective drying and preventing over-drying. Furthermore, the fully automated operation eliminates human intervention errors, standardizes drying processes across the entire production line and shifts, and improves batch-to-batch consistency of electrode materials.

[0029] In some embodiments, the drying parameters mentioned above can be the drying speed or frequency of the drying device on the electrode sheets. Specifying the drying parameters as drying speed or drying frequency allows the controller to directly adjust the fan operating frequency to change the hot air convection intensity, rather than prioritizing temperature adjustment. Compared to temperature regulation, variable frequency fan frequency adjustment achieves millisecond-level response, perfectly matching instantaneous speed changes on the production line and overcoming the industry-wide shortcoming of slow response in traditional temperature control methods. When the drying parameter is drying speed, this drying speed represents the hot air convection intensity of the drying device on the electrode sheets, which can be changed by adjusting the fan operating frequency. Directly controlling the hot air convection intensity corresponding to the drying speed by adjusting the fan operating frequency has a much faster response speed than temperature control methods that adjust the heating element temperature, adapting to instantaneous speed change conditions. When the drying parameter is drying frequency, this drying frequency represents the operating frequency of the fans in the drying device, including the operating frequency of the hot air circulation fan and / or the operating frequency of the exhaust fan. By directly using the fan operating frequency as the control object for drying parameters, frequency conversion regulation can achieve millisecond-level response with no control lag, and can adapt to the instantaneous changes in production line speed more quickly compared with traditional temperature regulation methods.

[0030] When the aforementioned drying parameters are drying speed or drying frequency, the drying device includes an air supply device and an exhaust device. When adjusting the drying parameters of the drying device for the electrodes, the operating parameters of the air supply device and the exhaust device can be synchronously adjusted according to a preset ratio. The air supply device can be, for example, a variable frequency hot air circulation fan for each zone of the oven, and the exhaust device can be, for example, a variable frequency exhaust fan for the oven. Using variable frequency fans as the actuators for the air supply and exhaust devices supports continuous and smooth frequency adjustment, providing a hardware foundation for synchronous adjustment according to a preset ratio. The preset ratio can be, for example, a fixed ratio between the hot air supply frequency and the exhaust frequency. This fixed ratio can be predetermined during the pre-process calibration stage based on the oven structure and the target negative pressure value. By pre-calibrating the fixed ratio between the air supply frequency and the exhaust frequency, when speed changes trigger fan frequency adjustments, the air supply and exhaust can be synchronously adjusted downwards or upwards according to a determined ratio, ensuring that the negative pressure in the oven cavity does not drift due to changes in air volume and maintaining a balanced and stable drying environment. In other words, the aforementioned synchronous adjustment refers to the simultaneous adjustment of the operating parameters of the air supply device and the exhaust device according to a preset ratio. That is, when the fan frequency of the air supply device decreases, the fan frequency of the exhaust device decreases synchronously according to the same ratio; when the fan frequency of the air supply device increases, the fan frequency of the exhaust device increases synchronously according to the same ratio. This dual-fan synchronous frequency adjustment avoids the problem of unstable negative pressure in the drying oven caused by unilateral air adjustment, ensuring a balanced internal air pressure environment under any speed change condition, thus improving the drying effect on the electrode sheets.

[0031] The basic process of the controller adjusting drying parameters based on comparison results has been explained above. The selection of response modes during the adjustment process will be further described below. In some embodiments, when adjusting the drying parameters of the drying device for the electrodes based on comparison results, the controller calculates the slope of the speed change according to the moving speed of the electrodes, and selects either a first response mode or a second response mode to adjust the rate of change of the drying parameters based on whether the slope of the speed change exceeds a predetermined slope threshold. The rate of change in the first response mode is less than that in the second response mode. By calculating the slope of the speed change and comparing it with the predetermined slope threshold, the controller distinguishes between a slow, abnormal deceleration of the production line and a sudden emergency stop, and selects different response modes accordingly to adjust the rate of change of the drying parameters. This allows the control system to match differentiated frequency modulation response strategies to different types of speed change characteristics, avoiding frequent vibrations of the fan during slow deceleration and ensuring that the drying parameters can quickly follow the speed change during an emergency stop.

[0032] Specifically, the aforementioned speed change slope is calculated by the controller based on the rate of change of the electrode's moving speed over time. For example, the controller can perform differential calculations on the moving speed within consecutive sampling periods to obtain the speed change slope. By obtaining the speed change slope through differential calculations of the moving speed, the severity of speed changes on the production line can be quantitatively characterized, providing a quantitative basis for distinguishing different types of abnormal operating conditions. The aforementioned predetermined slope threshold can be preset during the pre-process calibration stage based on the speed fluctuation characteristics of the production line. This allows for flexible setting of the judgment boundary to distinguish between slow deceleration and emergency stop based on the speed fluctuation characteristics of different production lines and operating conditions, improving the adaptability of the control strategy to different production scenarios.

[0033] When the slope of the speed change does not exceed a predetermined slope threshold, the first response mode is selected to adjust the drying parameters. The first response mode corresponds to a situation such as a slow, abnormal speed reduction in the production line. In this case, the first response mode, with its smaller rate of change, matches the adjustment speed of the drying parameters to the slowness of the speed change, preventing frequent vibrations in the fan frequency due to excessively rapid response, protecting the fan equipment, and maintaining the stability of the drying operation. When the slope of the speed change exceeds a predetermined slope threshold, the second response mode is selected to adjust the drying parameters. The second response mode corresponds to a situation such as a sudden, emergency stop in the production line. In this case, the second response mode, with its larger rate of change, allows the drying parameters to quickly follow the rapid speed change, promptly reducing the drying intensity and preventing over-drying of the electrodes due to continuous high-intensity baking during the emergency stop.

[0034] The drying parameter adjustment mentioned above mainly involves the response during the speed decrease phase. The following further explains the drying parameter recovery logic during the speed recovery phase. In some embodiments, when adjusting the drying parameters of the drying device for the electrode sheets, when the speed sensor detects that the electrode sheet's moving speed is in a recovery state, the controller gradually increases the drying parameters. This recovery state refers to the state where the moving speed detected by the speed sensor gradually increases towards the normal rated speed after experiencing a decrease or shutdown. By detecting the recovery trend of the moving speed, the controller can determine that the production line fault has been resolved and normal production is resuming, thereby triggering the drying parameter recovery logic. The aforementioned gradual recovery means that the drying parameters smoothly increase along with the recovery of the moving speed, rather than immediately and abruptly reverting the drying parameters to the rated value when the speed recovers. The smooth increase in drying parameters avoids the impact of sudden changes in airflow on electrode sheet drying, prevents uneven drying or fluctuations in the drying of the electrode sheets due to sudden changes in airflow, and ensures a seamless transition between the drying quality of the electrode sheets during the production recovery phase and the normal production state. In this way, when the moving speed of the electrode is increasing, the fan frequency smoothly increases with the speed, avoiding fluctuations in electrode drying caused by sudden changes in air volume, ensuring that electrode drying quickly returns to the standard state after production resumes, and maintaining drying consistency.

[0035] Furthermore, in some embodiments, to avoid frequent switching of the fan's operating frequency due to small instantaneous speed fluctuations on the production line, the controller can also apply a delay filtering program to the moving speed detected by the speed sensor, and adjust the drying parameters of the drying device only when the speed change indicated by the moving speed continues for more than a predetermined delay period. This delay filtering program can be, for example, a time-domain filtering process applied to the speed signal, including but not limited to moving average filtering, low-pass digital filtering, etc. This delay filtering program is used to filter out instantaneous speed fluctuation noise caused by mechanical vibration, minor tension fluctuations, etc., on the production line. By eliminating high-frequency noise components in the speed signal through filtering, the controller responds only to real, continuous speed changes, avoiding false triggering caused by signal noise.

[0036] The aforementioned predetermined delay period can be pre-set based on the speed fluctuation characteristics of the production line and the allowable switching frequency of the blower equipment. Only when the speed change indicated by the moving speed exceeds the predetermined delay period will the controller recognize the speed change as a genuine abnormal condition rather than a momentary fluctuation, and then adjust the drying parameters accordingly. In this way, anti-vibration hysteresis protection is achieved for small momentary speed fluctuations in the production line, preventing the blower from frequently switching between high and low frequencies due to minute momentary speed fluctuations, protecting the blower equipment, extending its service life, and ensuring the stability of drying operation.

[0037] The adaptive control logic for drying parameters within their normal adjustment range has been explained above. The following section further describes the handling method when drying parameters reach their adjustment limits. In some embodiments, the drying method further includes: detecting whether the drying parameters have reached a preset limit value, generating an alarm signal when the drying parameters reach the preset limit value, and simultaneously adjusting the heating temperature of the drying device as a secondary compensation. This preset limit value can be, for example, the minimum allowable value of the fan operating frequency, i.e., the lower limit value of the fan frequency reduction adjustment. When the drying parameter (such as the fan frequency) drops to this limit value, the fan can no longer reduce its frequency. Setting the preset limit value as a safety boundary for drying parameter adjustment prevents the fan frequency from dropping too low, affecting the normal operation of the fan or the uniformity of the temperature field inside the drying oven, thus ensuring the safe operation of the equipment.

[0038] The aforementioned alarm signals can be displayed or prompted via a Human Machine Interface (HMI) to notify maintenance personnel that the production line is in an extreme abnormal operating condition, requiring manual intervention to troubleshoot the fault. In extreme cases where drying parameters are adjusted to their limits, the alarm signal, linked to the HMI, will alert maintenance personnel to the equipment malfunction, guiding them to promptly investigate the root cause of the production line abnormality and preventing the malfunction from persisting for an extended period and causing wider product defects.

[0039] The aforementioned adjustment of the drying device's heating temperature as a secondary compensation refers to further fine-tuning the oven heating temperature to assist in reducing the drying intensity after the fan frequency adjustment has reached its limit. In extreme cases where the fan frequency adjustment channel is saturated, this secondary compensation method of fine-tuning the heating temperature provides the system with additional margin for drying intensity control, ensuring that even under extreme conditions, the drying intensity on the electrodes can be further reduced to prevent over-drying. Thus, when the drying parameters reach their limit and still cannot match the current speed conditions, an alarm signal is generated to indicate equipment failure, and the secondary compensation adjustment of the heating temperature is activated, forming a dual protection mechanism of fan frequency adjustment and heating temperature adjustment. This abnormal alarm closed loop ensures that the system still has additional drying control measures under extreme conditions, preventing uncontrolled drying after a single control channel (fan frequency) becomes saturated.

[0040] The above explanation illustrates the method of real-time adjustment of drying parameters based on comparison results. As another implementation, the controller can also determine the speed range of the moving speed and, based on a preset mapping relationship between moving speed and drying parameters, adjust the drying parameters to the values ​​corresponding to that speed range. By dividing continuous moving speeds into discrete speed ranges and adjusting the drying parameters to values ​​matching the corresponding speed ranges based on a preset mapping relationship, partitioned quantitative control between drying parameters and moving speeds is achieved. This partitioned mapping method makes the control logic clear and the execution highly deterministic. The controller can directly look up the corresponding drying parameter values ​​according to the speed range, reducing real-time calculations and improving control response efficiency.

[0041] The aforementioned speed range divides the range of moving speed values ​​into several discrete segments. This speed range can be pre-established during the pre-process calibration stage based on production line characteristics and electrode drying process requirements. Establishing speed range division standards through pre-process calibration enables the control system to perform precise zone control based on pre-calibrated process data during operation, avoiding complex real-time process calculations and improving system reliability and consistency. The pre-defined mapping relationship between moving speed and drying parameters can be stored in the human-machine formula storage unit, forming a one-to-one mapping database between line speed and fan frequency. Pre-storing the mapping relationship in database form in the human-machine formula storage unit facilitates flexible switching and unified management of different production lines and different process formulas, while also supporting continuous optimization and updates of the mapping relationship based on actual production experience.

[0042] For example, the aforementioned speed range includes at least a normal speed range, a low speed range, and a shutdown range. The preset mapping relationship between the moving speed and the drying parameters is as follows: within the normal speed range, the drying parameters of the drying device maintain the rated standard value; within the low speed range, the drying parameters of the drying device decrease linearly as the moving speed decreases; within the shutdown range, the drying parameters of the drying device decrease to the minimum standby value. The speed range is further refined into three levels: normal speed range, low speed range, and shutdown range, each corresponding to a drying parameter control strategy of rated standard value, linear decrease, and minimum standby value, respectively, achieving refined coverage of all operating conditions. This three-level zone control strategy provides clear control rules for the drying parameters under three typical operating conditions: normal production, abnormal speed reduction, and complete shutdown, taking into account both the standard drying requirements under normal operating conditions and the over-drying protection requirements under abnormal operating conditions.

[0043] Within the normal speed range, the drying parameters of the drying device remain at their rated standard values. The normal speed range, for example, corresponds to the normal rated line speed range of the production line. During normal, uniform production, the fan maintains its rated standard frequency, and the drying oven maintains its standard drying airflow to meet the drying requirements of conventional electrode sheets, ensuring drying quality and production efficiency at rated capacity.

[0044] Furthermore, within the low-speed range, the drying parameters of the drying device decrease linearly as the conveyor speed decreases. The low-speed range can, for example, correspond to the operating range of an abnormally low-speed reduction in the production line. The lower the conveyor speed, the more synchronously and linearly the hot air circulation fan frequency and exhaust fan frequency decrease, reducing the hot air convection intensity and solvent exhaust volume, thus reducing the drying capacity per unit time. This matches the drying intensity with the increased residence time of the electrode sheets in the furnace due to the speed reduction, preventing over-drying. This linear reduction maintains a definite quantitative correspondence between the drying parameters and the speed, avoiding abrupt or step-like adjustments.

[0045] Correspondingly, during the shutdown period, the drying parameters of the drying equipment are reduced to the lowest standby value. The shutdown period could correspond to a complete production line shutdown. When the production line is completely shut down, the hot air fan and exhaust fan simultaneously reduce to the lowest standby frequency, maintaining only a weak hot air circulation to ensure a uniform temperature field within the furnace, completely stopping high-intensity drying and preventing the static electrode sheets from continuously baking and cracking. Simultaneously, the reduced fan frequency operation decreases unnecessary hot air circulation and exhaust energy consumption, avoids long-term full-frequency idle operation of the fans, extends fan lifespan, and reduces production line electricity and equipment maintenance costs.

[0046] 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.

[0047] 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.

[0048] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0049] 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.

[0050] It should be understood that the qualifiers “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” used in the description of the embodiments of this application are only used to more clearly illustrate the technical solutions and are not intended to limit the scope of protection of this application.

[0051] 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. An electrode sheet, characterized in that, The local appearance defect rate is less than 0.4% when the drying speed of the electrode changes.

2. A method for drying electrode sheets, characterized in that, The method for drying electrodes to be dried includes at least the following steps: S001: Turn on the drying device to dry the electrode sheets to be dried; S002: The drying device is equipped with a speed sensor, which monitors the electrode in real time and obtains the moving speed of the electrode; S003: The controller compares the moving speed with the target speed and obtains the comparison result, and adjusts the drying parameters of the drying device for the electrode based on the comparison result.

3. The method for drying the electrode sheet according to claim 2, characterized in that, The drying parameters are the drying speed or drying frequency of the electrode sheet by the drying device.

4. The method for drying the electrode sheet according to claim 3, characterized in that, The drying device includes an air supply device and an exhaust device. Adjusting the drying parameters of the drying device for the electrode sheet includes: synchronously adjusting the operating parameters of the air supply device and the operating parameters of the exhaust device according to a preset ratio.

5. The method for drying the electrode sheet according to claim 2, characterized in that, The adjustment of the drying parameters of the drying device for the electrode based on the comparison results includes: the controller calculates the slope of the speed change according to the moving speed of the electrode, and selects a first response mode or a second response mode to adjust the rate of change of the drying parameters according to whether the slope of the speed change exceeds a predetermined slope threshold, wherein the rate of change of the first response mode is less than the rate of change of the second response mode.

6. The method for drying the electrode sheet according to claim 2, characterized in that, The adjustment of the drying parameters of the drying device for the electrode includes: when the speed sensor detects that the moving speed of the electrode is in an increasing state, the controller causes the drying parameters to gradually increase.

7. The method for drying the electrode sheet according to claim 6, characterized in that, The controller also applies a delay filtering procedure to the moving speed detected by the speed sensor, and adjusts the drying parameters of the drying device only if the speed change indicated by the moving speed continues for more than a predetermined delay period.

8. The method for drying the electrode sheet according to claim 2, characterized in that, Also includes: The system detects whether the drying parameters have reached the preset limit value, and generates an alarm signal when the drying parameters reach the preset limit value, while adjusting the heating temperature of the drying device as a secondary compensation.

9. The method for drying the electrode sheet according to claim 2, characterized in that, Also includes: The controller determines the speed range of the moving speed based on the moving speed, and adjusts the drying parameters to the value corresponding to the speed range based on the preset mapping relationship between the moving speed and the drying parameters.

10. The method for drying the electrode sheet according to claim 9, characterized in that, The speed range includes at least a normal speed range, a low speed range, and a stop range. The mapping relationship between the preset moving speed and the drying parameters is as follows: in the normal speed range, the drying parameters of the drying device maintain the rated standard value; in the low speed range, the drying parameters of the drying device decrease linearly as the moving speed decreases; in the stop range, the drying parameters of the drying device drop to the minimum standby value.

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