Battery pole piece baking device and method
The clamping module in the vacuum baking chamber alternately outputs high-frequency and low-frequency pulse voltages, combined with real-time adjustment of the temperature detection module, solves the problems of high sealing and energy consumption of the battery pole baking device, and achieves efficient and uniform battery pole baking, reducing energy consumption and shortening baking time.
Patent Information
- Application Number
- CN202510685123.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-26
- Publication Date
- 2025-08-15
AI Technical Summary
In the prior art, the sealing requirements of the battery pole baking device are strict, and high vacuum degree can easily lead to damage to the pole material structure. Traditional hot air baking has high energy consumption and low efficiency, and poor baking uniformity, resulting in over-drying of the pole edge or residual solvent in the center area.
The clamping module in the vacuum baking chamber is combined with the pulse power module. By alternately outputting high-frequency and low-frequency pulse voltages, combined with the temperature detection module, the pulse electrical signal parameters are adjusted in real time, so that the battery pole plate can generate self-heating and gradient cooling is performed in a vacuum environment.
On the premise of ensuring the structural integrity of the electrode sheet, an efficient and uniform baking effect can be achieved, energy consumption and baking time can be shortened, and large-scale battery manufacturing needs can be met.
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Figure CN120488648A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of battery production, and in particular to a device and method for baking battery pole pieces. Background Art
[0002] With the rapid development of new energy vehicles, consumer electronics, and energy storage technologies, lithium-ion batteries have become a core solution for global energy storage due to their high energy density, long cycle life, and low self-discharge rate. In the lithium battery manufacturing process, the baking of electrodes and cells is a critical step influencing battery performance and safety. The main purpose of the baking process is to remove residual moisture and organic solvents from components such as electrode materials, separators, and tabs to prevent problems such as electrolyte decomposition and gas expansion, thereby improving the battery's cycle stability and safety.
[0003] At present, the heat treatment baking solutions commonly used in the industry mainly include hot air circulation baking, vacuum baking and a multi-stage baking solution that combines the two. Among them, traditional hot air baking uses high-temperature airflow to heat the battery cell for a long time. It has the problems of high energy consumption, low efficiency and poor temperature uniformity. Specifically, the hot air oven has high energy consumption, energy utilization rate is less than 40%, and continuous heat supply is required to maintain the cavity temperature. The baking efficiency is low. When the thickness of the electrode is greater than 100μm, traditional conduction heating takes 2-4 hours to achieve deep drying. Hot air baking is also prone to over-baking of the edge of the electrode and residual solvent in the center area. Although vacuum baking can accelerate water evaporation and shorten baking time by reducing the ambient air pressure, it has strict requirements on the sealing of the equipment, and high vacuum degree can easily cause damage to the structure of the electrode material, affecting the electrochemical performance of the battery. Summary of the Invention
[0004] The purpose of this application is to provide a battery electrode baking device and method to solve the above technical problems.
[0005] In order to achieve the above objectives, this application adopts the following technical solutions: The present application provides a battery electrode baking device, comprising: a vacuum baking chamber with an operating table inside; a clamping module, arranged on the operating table, for fixing the battery electrode and electrically connected to the battery electrode; a pulse power supply module, electrically connected to the clamping module, for outputting a pulse electrical signal to the battery electrode through the clamping module to cause the battery electrode to self-heat; a temperature detection module, arranged in the vacuum baking chamber, for detecting the baking temperature of the battery electrode when it self-heats; and a control module, connected to the pulse power supply module and the temperature detection module, for calculating the temperature gradient inside the battery electrode in real time according to the signal of the temperature detection module, and dynamically adjusting the parameters of the pulse electrical signal output by the pulse power supply module.
[0006] In some technical solutions of the present application, the pulse power supply module is capable of alternately outputting high-frequency pulse voltage and low-frequency pulse voltage with a frequency of 10 Hz to 500 kHz and a duty cycle of 10 to 90%.
[0007] In some technical solutions of the present application, the high-frequency pulse voltage is 20V~80V, the frequency is 100kHz~500kHz, the duty cycle is 15%~30%, and the duration is less than or equal to 10μs.
[0008] In some technical solutions of the present application, the low-frequency pulse voltage is 5V~30V, the frequency is 10Hz~100Hz, the duty cycle is 40%~60%, and the duration is 10ms~1s.
[0009] In some technical solutions of the present application, the alternating period is that the high-frequency pulse voltage works for 1 to 4 minutes and the low-frequency pulse voltage works for 1 to 3 minutes.
[0010] In some technical solutions of the present application, the temperature detection module includes an infrared temperature measuring unit and a contact temperature measuring unit. The infrared temperature measuring unit is arranged on the inner wall of the vacuum baking cavity, and the contact temperature measuring unit is connected to the clamping module.
[0011] In some technical solutions of the present application, the vacuum baking chamber further includes a condensation recovery system, which is connected to the interior of the vacuum baking chamber and is used to cool and collect the solvent volatilized during baking when the battery poles self-heat.
[0012] In some technical solutions of the present application, the clamping module includes a positive terminal and a negative terminal, the positive terminal is connected to the positive electrode tab of the battery electrode sheet, and the negative terminal is connected to the negative electrode tab of the battery electrode sheet.
[0013] In some technical solutions of the present application, three battery electrodes can be placed on the operating table at the same time for baking, and the positive electrode tab and the negative electrode tab of each battery electrode are electrically connected to the contact temperature measurement unit respectively.
[0014] The present application also provides a method for baking a battery electrode, comprising the steps of: Pre-processing stage: Apply current to the battery electrode for pre-activation, obtain the battery electrode impedance relationship under temperature conditions of 25℃~85℃ and establish a temperature-impedance curve to detect the initial impedance of the battery electrode; Main baking stage: According to the temperature-impedance curve obtained in the pretreatment stage, high-frequency pulse voltage and low-frequency pulse voltage are applied alternately, and the baking temperature is maintained at 85±5℃ under vacuum conditions; Gradient cooling stage: reduce the high-frequency pulse voltage and low-frequency pulse voltage amplitude at a rate of 0.3~0.5℃ / min until the vacuum baking chamber temperature is less than or equal to 40℃.
[0015] In some technical solutions of the present application, in the pretreatment stage, a current of 0.1 to 0.5 C is applied to the battery electrode for pre-activation for 1 to 2 minutes.
[0016] Furthermore, in the pretreatment stage, a current of 0.1C, 0.2C, 0.3C, 0.4C or 0.5C is applied to the battery electrode for pre-activation, which lasts for 1 minute, 1.5 minutes or 2 minutes.
[0017] In some technical solutions of the present application, the vacuum degree in the main baking stage is less than or equal to 0.5 Pa, and the baking time is 8 to 12 hours.
[0018] Furthermore, the vacuum degree in the main baking stage is 0.1 Pa, 0.2 Pa, 0.3 Pa, 0.4 Pa or 0.5 Pa, and the baking time is 8 hours, 9 hours, 10 hours, 11 hours or 12 hours.
[0019] In some technical solutions of the present application, the alternating period of the high-frequency pulse voltage and the low-frequency pulse voltage is that the high-frequency pulse voltage works for 1 to 4 minutes and the low-frequency pulse voltage works for 1 to 3 minutes.
[0020] Furthermore, the alternating cycle of the high-frequency pulse voltage and the low-frequency pulse voltage is that the high-frequency pulse voltage works for 1 minute, 2 minutes, 3 minutes or 4 minutes, and the low-frequency pulse voltage works for 1 minute, 2 minutes or 3 minutes.
[0021] In some technical solutions of the present application, the high-frequency pulse voltage is 20V~80V, the frequency is 100kHz~500kHz, the duty cycle is 15%~30%, and the duration is less than or equal to 10μs.
[0022] Furthermore, the high-frequency pulse voltage is 20V, 30V, 40V, 50V, 60V, 70V or 80V, the frequency is 100kHz, 200kHz, 300kHz, 400kHz or 500kHz, the duty cycle is 15%, 20%, 25% or 30%, and the duration is 1μs, 2μs, 3μs, 4μs, 5μs, 6μs, 7μs, 8μs, 9μs or 10μs.
[0023] In some technical solutions of the present application, the low-frequency pulse voltage is 5V~30V, the frequency is 10Hz~100Hz, the duty cycle is 40%~60%, and the duration is 10ms~1s.
[0024] Furthermore, the low-frequency pulse voltage is 5V, 10V, 15V, 20V, 25V or 30V, the frequency is 10Hz, 20Hz, 30Hz, 40Hz, 50Hz, 60Hz, 70Hz, 80Hz, 90Hz or 100Hz, the duty cycle is 40%, 45%, 50%, 55% or 60%, and the duration is 10ms, 20ms, 30ms, 40ms, 50ms, 60ms, 70ms, 80ms, 90ms, 100ms, 200ms, 300ms, 400ms, 500ms, 600ms, 700ms, 800ms, 900ms or 1s.
[0025] In some technical solutions of the present application, the minimum voltage of the high-frequency pulse voltage and the low-frequency pulse voltage in the gradient cooling stage is 5~15V, and the vacuum degree is less than or equal to 0.5Pa and maintained for 1~3 hours.
[0026] Furthermore, the minimum voltage of the high-frequency pulse voltage and the low-frequency pulse voltage is 5V, 10V or 15V, and the vacuum degree is 0.1Pa, 0.2Pa, 0.3Pa, 0.4Pa or 0.5Pa and maintained for 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours.
[0027] Furthermore, in the gradient cooling stage, the high-frequency pulse voltage and the low-frequency pulse voltage amplitude are reduced at a rate of 0.3°C / min, 0.35°C / min, 0.4°C / min, 0.45°C / min or 0.5°C / min until the vacuum baking chamber temperature reaches 20°C, 25°C, 30°C, 35°C or 40°C. The battery electrode baking device and method provided in this application can achieve efficient and uniform baking effects while ensuring the structural integrity of the electrode material, while reducing energy consumption and production costs, and can meet the needs of large-scale battery manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 This is a schematic diagram of the front view of the battery electrode baking device provided in this application.
[0029] Figure 2 for Figure 1 Schematic diagram of the top view of the interior of the vacuum baking chamber of the battery electrode baking device.
[0030] Figure 3 for Figure 1 Schematic diagram of the structure of the clamping module and contact temperature measurement unit at A in the middle.
[0031] Figure 4 This is a temperature-impedance curve diagram of Example 1 provided in this application.
[0032] Figure 5This is a temperature-impedance curve diagram of Example 2 provided in this application.
[0033] Figure 6 This is a temperature-impedance curve diagram of Example 3 provided in this application.
[0034] Figure 7 This is a temperature-impedance curve diagram of Example 4 provided in this application.
[0035] Numbers in the figure: 1. Vacuum baking chamber; 11. Operating table; 2. Clamping module; 21. Positive terminal; 22. Negative terminal; 3. Pulse power supply module; 4. Temperature detection module; 41. Infrared temperature measurement unit; 42. Contact temperature measurement unit; 5. Battery electrode. DETAILED DESCRIPTION
[0036] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.
[0037] In the description of this application, it should be understood that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.
[0038] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to welded connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal communication between two components or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.
[0039] In this application, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.
[0040] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "upper," "lower," "left," "right," "inner," "outer," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.
[0041] In the present disclosure, a numerical range expressed using “~” means a range including the numerical values described before and after “~” as a minimum value and a maximum value, respectively.
[0042] In the numerical ranges described in stages in this disclosure, the upper limit or lower limit described in a certain numerical range may be replaced by the upper limit or lower limit of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper limit or lower limit described in a certain numerical range may be replaced by the value shown in the Examples.
[0043] Unless the context clearly indicates otherwise, when used in this specification, the terms “comprises,” “includes,” or “comprising” specify the presence of stated elements, but do not preclude the presence or addition of one or more other elements.
[0044] The present application provides a battery pole piece baking device and method, the purpose of which is to solve the problems that the existing technical solutions have strict requirements on the sealing of the device when baking the battery pole pieces, and the high vacuum degree can easily cause damage to the pole piece material structure, affecting the electrochemical performance of the battery. At the same time, the existing hot air circulation oven has high energy consumption, the energy utilization rate is less than 40%, and continuous heat supply is required to maintain the cavity temperature, and the baking efficiency is low. When the pole piece thickness is greater than 100μm, traditional conduction heating takes 2-4 hours to achieve deep drying. In addition, the baking uniformity is poor, and hot air baking can easily cause over-drying of the pole piece edge and residual solvent in the center area.
[0045] Parameter Definitions: "Frequency" determines the periodicity of the pulse; the lower the frequency, the longer the single cycle. "Voltage" determines the intensity of the pulse and is related to the impedance of the battery electrode. "Duty Cycle" balances energy output with heat dissipation requirements. A high duty cycle causes overheating, while a low duty cycle affects the heating effect. "Duty" controls the total energy output time; a longer duration increases the cumulative baking time.
[0046] In the present application, the alternating cycle of the high-frequency pulse voltage and the low-frequency pulse voltage dynamically adjusts the working states of the high-frequency pulse voltage and the low-frequency pulse voltage according to the baking temperature when the battery electrode self-heats. The dynamic adjustment of the working states of the high-frequency pulse voltage and the low-frequency pulse voltage in each alternating cycle of the high-frequency pulse voltage and the low-frequency pulse voltage includes the passage of the pulse voltage and the suspension of the passage of the pulse voltage.
[0047] The present application proposes a battery pole piece baking device, which will be described in detail below with reference to specific drawings.
[0048] like Figure 1 and Figure 2 As shown, an embodiment of the present application provides a battery electrode baking device, including a vacuum baking cavity 1, which is provided with an operating table 11 inside; a clamping module 2, which is arranged on the operating table 11, and is used to fix the battery electrode 5 and is electrically connected to the battery electrode 5; a pulse power supply module 3, which is electrically connected to the clamping module 2, and is used to output a pulse electrical signal to the battery electrode 5 through the clamping module 2, so that the battery electrode 5 self-heats; a temperature detection module 4, which is arranged in the vacuum baking cavity 1, and is used to detect the baking temperature of the battery electrode 5 when it self-heats; and a control module, which is connected to the pulse power supply module 3 and the temperature detection module 4, and is used to calculate the temperature gradient inside the battery electrode 5 in real time according to the signal of the temperature detection module 4, and dynamically adjust the pulse electrical signal parameters output by the pulse power supply module 3.
[0049] Specifically, the vacuum baking chamber 1 also includes a condensation recovery system, which is connected to the interior of the vacuum baking chamber and is used to cool and collect solvent volatilized during the self-heating baking of the battery electrode 5. The clamping module 2 includes a positive terminal 21 and a negative terminal 22. The positive terminal 21 is connected to the positive electrode tab of the battery electrode 5, and the negative terminal 22 is connected to the negative electrode tab of the battery electrode 5.
[0050] Furthermore, the control module can alternately output high-frequency pulse voltage and low-frequency pulse voltage with a frequency of 10Hz to 500kHz and a duty cycle of 10 to 90%. The high-frequency pulse voltage is 20V to 80V, a frequency of 100kHz to 500kHz, a duty cycle of 15% to 30%, and a duration of less than or equal to 10μs; the low-frequency pulse voltage is 5V to 30V, a frequency of 10Hz to 100Hz, a duty cycle of 40% to 60%, and a duration of 10ms to 1s. The alternating cycle of the high-frequency pulse voltage and the low-frequency pulse voltage is 1 to 4 minutes for the high-frequency pulse voltage and 1 to 3 minutes for the low-frequency pulse voltage.
[0051] Figure 2 As shown in , regarding the structure of the battery electrode 5, as an example, three battery electrodes 5 can be placed on the operating table 11 at the same time for baking operation, and the positive electrode tab and the negative electrode tab of each battery electrode 5 are electrically connected to the contact temperature measurement unit 4 respectively.
[0052] like Figure 3 As shown, the structure of the temperature detection module 4 , as an example, includes an infrared temperature measuring unit 41 and a contact temperature measuring unit 42 . The infrared temperature measuring unit 41 is arranged on the inner wall of the vacuum baking cavity 1 , and the contact temperature measuring unit 42 is connected to the clamping module 2 .
[0053] The present application also provides a method for baking a battery electrode, comprising the steps of: Pre-processing stage: Apply current to the battery electrode for pre-activation, obtain the battery electrode impedance relationship under temperature conditions of 25℃~85℃ and establish a temperature-impedance curve to detect the initial impedance of the battery electrode; Main baking stage: According to the temperature-impedance curve obtained in the pretreatment stage, high-frequency pulse voltage and low-frequency pulse voltage are applied alternately, and the baking temperature is maintained at 85±5℃ under vacuum conditions; Gradient cooling stage: reduce the high-frequency pulse voltage and low-frequency pulse voltage amplitude at a rate of 0.3~0.5℃ / min until the vacuum baking chamber temperature is less than or equal to 40℃.
[0054] In this embodiment, temperatures of 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 70°C, 80°C, and 85°C are selected to establish a temperature-impedance curve.
[0055] In this embodiment, during the pretreatment stage, a current of 0.1 to 0.5 C is applied to the battery electrode for pre-activation for 1 to 2 minutes; preferably, a current of 0.1 C, 0.2 C, 0.3 C, 0.4 C or 0.5 C is applied for pre-activation for 1 minute, 1.5 minutes or 2 minutes.
[0056] In this embodiment, the vacuum degree in the main baking stage is less than or equal to 0.5 Pa, and the baking time is 8 to 12 hours; preferably, the vacuum degree in the main baking stage is 0.1 Pa, 0.2 Pa, 0.3 Pa, 0.4 Pa or 0.5 Pa, and the baking time is 8 hours, 9 hours, 10 hours, 11 hours or 12 hours.
[0057] Furthermore, the alternating cycle is that the high-frequency pulse voltage works for 1 to 4 minutes, and the low-frequency pulse voltage works for 1 to 3 minutes; preferably, the high-frequency pulse voltage works for 1 minute, 2 minutes, 3 minutes or 4 minutes, and the low-frequency pulse voltage works for 1 minute, 2 minutes or 3 minutes.
[0058] Furthermore, the high-frequency pulse voltage is 20V~80V, the frequency is 100kHz~500kHz, the duty cycle is 15%~30%, and the duration is less than or equal to 10μs; preferably, the high-frequency pulse voltage is 20V, 30V, 40V, 50V, 60V, 70V or 80V, the frequency is 100kHz, 200kHz, 300kHz, 400kHz or 500kHz, the duty cycle is 15%, 20%, 25% or 30%, and the duration is 1μs, 2μs, 3μs, 4μs, 5μs, 6μs, 7μs, 8μs, 9μs or 10μs.
[0059] Further, the low-frequency pulse voltage is 5V~30V, the frequency is 10Hz~100Hz, the duty cycle is 40%~60%, and the duration is 10ms~1s; preferably, the low-frequency pulse voltage is 5V, 10V, 15V, 20V, 25V or 30V, the frequency is 10Hz, 20Hz, 30Hz, 40Hz, 50Hz, 60Hz, 70Hz, 80Hz, 90Hz or 100Hz, the duty cycle is 40%, 45%, 50%, 55% or 60%, and the duration is 10ms, 20ms, 30ms, 40ms, 50ms, 60ms, 70ms, 80ms, 90ms, 100ms, 200ms, 300ms, 400ms, 500ms, 600ms, 700ms, 800ms, 900ms or 1s.
[0060] In this embodiment, during the gradient cooling stage, the amplitudes of the high-frequency pulse voltage and the low-frequency pulse voltage are reduced at a rate of 0.3°C / min, 0.35°C / min, 0.4°C / min, 0.45°C / min or 0.5°C / min until the vacuum baking chamber temperature reaches 20°C, 25°C, 30°C, 35°C or 40°C.
[0061] In this embodiment, the minimum voltage of the high-frequency pulse voltage and the low-frequency pulse voltage in the gradient cooling stage is 5~15V, and the vacuum degree is less than or equal to 0.5Pa and maintained for 1~3 hours; preferably, the minimum voltage of the high-frequency pulse voltage and the low-frequency pulse voltage is 5V, 10V or 15V, and the vacuum degree is 0.1Pa, 0.2Pa, 0.3Pa, 0.4Pa or 0.5Pa and maintained for 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours.
[0062] The present application provides a battery electrode baking device and method, which can achieve efficient and uniform baking effects while ensuring the structural integrity of the electrode material, while reducing energy consumption and production costs to meet the needs of large-scale battery manufacturing.
[0063] Example 1 Pretreatment stage: Apply 0.5C current to the tab for pre-activation for 1 minute. By continuously extending the pre-activation time, the self-heating temperature of the tab reaches the set value, and the tab impedance relationship under different temperature conditions (25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 70℃, 80℃, 85℃) is obtained, and the temperature-impedance curve is established. Figure 4 , the initial detection impedance is 10mΩ, Figure 4 The impedance of the medium temperature-impedance curve decreases by 12% from 25℃ to 45℃.
[0064] Main baking stage: the temperature is maintained at 85±5℃; High-frequency pulse voltage 80V, frequency 500kHz, duty cycle 30%, duration 10μs; Low-frequency pulse voltage 30V, frequency 100Hz, duty cycle 60%, duration 1s; The alternating cycle of the high-frequency pulse voltage and the low-frequency pulse voltage is 3 minutes for the high-frequency pulse voltage and 1 minute for the low-frequency pulse voltage, with a total duration of 8 hours, and the vacuum degree is less than or equal to 0.5Pa.
[0065] Gradient cooling: reduce the pulse voltage from 80 V to 10 V at a rate of 0.5 °C / min, and simultaneously cool to 40 °C and maintain the pressure for 1 hour.
[0066] Example 2: Pretreatment stage: Apply 0.2C current to the tab for pre-activation for 2 minutes to obtain the tab impedance relationship under different temperature conditions (25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 70℃, 80℃, 85℃), and use this to establish the temperature-impedance curve. Figure 5 , the initial impedance of the test is 15mΩ, Figure 5 The impedance of the medium temperature-impedance curve decreases by 7% from 25℃ to 50℃.
[0067] Main baking stage: the temperature is maintained at 85±5℃; High-frequency pulse voltage 50V, frequency 200kHz, duty cycle 20%, duration 8μs; Low-frequency pulse voltage 5V, frequency 10Hz, duty cycle 40%, duration 10ms; The alternating cycle of the high-frequency pulse voltage and the low-frequency pulse voltage is 1 minute for the high-frequency pulse voltage and 3 minutes for the low-frequency pulse voltage, with a total duration of 10 hours, and the vacuum degree is less than or equal to 0.5Pa.
[0068] Gradient cooling: reduce the pulse voltage from 50 V to 5 V at a rate of 0.3 °C / min, and simultaneously cool to 40 °C and maintain the pressure for 2 hours.
[0069] Example 3: Pretreatment stage: Apply a small current of 0.3C to the tab for pre-activation for 1.5 minutes to obtain the tab impedance relationship under different temperature conditions (25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 70℃, 80℃, 85℃), and use this to establish the temperature-impedance curve. Figure 6 , the initial impedance of the test is 12mΩ, Figure 6 The impedance of the medium temperature-impedance curve decreases by 9% from 25℃ to 45℃.
[0070] Main baking stage: the temperature is maintained at 85±5℃; High-frequency pulse voltage 60V, frequency 300kHz, duty cycle 25%, duration 9μs; Low-frequency pulse voltage 20V, frequency 50Hz, duty cycle 50%, duration 500ms; The alternating cycle of the high-frequency pulse voltage and the low-frequency pulse voltage is 2 minutes for the high-frequency pulse voltage and 1 minute for the low-frequency pulse voltage, with a total duration of 9 hours, and the vacuum degree is less than or equal to 0.5Pa.
[0071] Gradient cooling: reduce the pulse voltage from 60 V to 10 V at a rate of 0.4 °C / min, and simultaneously cool to 40 °C and maintain the pressure for 1.5 hours.
[0072] Example 4: Pretreatment stage: Apply 0.4C current to the tab for pre-activation for 1 minute to obtain the tab impedance relationship under different temperature conditions (25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 70℃, 80℃, 85℃), and use this to establish the temperature-impedance curve. Figure 7 , the initial impedance of the test is 18mΩ, Figure 7 The impedance of the medium temperature-impedance curve decreases by 15% from 25℃ to 55℃.
[0073] Main baking stage: the temperature is maintained at 85±5℃; High-frequency pulse voltage 80V, frequency 100kHz, duty cycle 25%, duration 9μs; The low-frequency pulse voltage is 25V, the frequency is 80Hz, the duty cycle is 55%, and the duration is 800ms.
[0074] The alternating cycle of the high-frequency pulse voltage and the low-frequency pulse voltage is 4 minutes for the high-frequency pulse voltage and 2 minutes for the low-frequency pulse voltage, with a total duration of 12 hours, and the vacuum degree is less than or equal to 0.5Pa.
[0075] Gradient cooling: reduce the pulse voltage from 80V to 15V at a rate of 0.5℃ / min, and simultaneously cool to 40℃ and maintain the pressure for 3 hours.
[0076] Comparative Example 1: Traditional high-temperature baking (without pulse assistance) Pretreatment stage: no current pre-activation, directly loaded into the oven, and no detection of initial impedance and temperature correlation.
[0077] Main baking stage: constant temperature baking, vacuum baking at 95℃, vacuum degree less than or equal to 10Pa, no pulse application, lasting 24 hours.
[0078] Cooling stage: natural cooling, turning off the heating and letting it stand until the temperature reaches 40°C, which takes 8 hours, without pulse amplitude control.
[0079] Comparative Example 2: Single Frequency Pulse Baking (No High and Low Frequency Coordination) Pretreatment stage: DC pre-charging only, applying 0.2C current for 1 minute, and no temperature-impedance model was established.
[0080] Main baking stage: single high-frequency pulse voltage 80V, 200kHz, duty cycle 30%; no low-frequency coordination, temperature 85℃, vacuum degree less than or equal to 1Pa, baking for 12 hours.
[0081] Cooling stage: Rapid cooling, forced cooling at a rate of 1.2℃ / min, and the pulse voltage dropped sharply to 0V.
[0082] like Figures 4 to 7 As shown in the figure, the temperature-impedance curve established in the pretreatment stage is used to adjust the pulse voltage parameters of the main baking stage in real time. When the impedance is detected to drop to a certain threshold, the control module in the pulse power supply module automatically switches the high-frequency / low-frequency pulse voltage mode, or adjusts the duty cycle and voltage to optimize the heating efficiency and uniformity. The effect of the vacuum environment on heat conduction. Under vacuum, the heat loss of the electrode may be reduced, so temperature control is more critical. The temperature-impedance relationship helps predict the heat generation characteristics of the electrode at different temperature stages, thereby adjusting the alternating cycle and energy input of the high-frequency / low-frequency pulse voltage to avoid overheating or insufficient heating.
[0083] The battery pole piece includes a metal current collector and an active material body. The present invention applies a specific pattern of high-frequency pulse voltage and low-frequency pulse voltage to the battery pole piece or pole group to be baked. The high-frequency pulse voltage generates a high-frequency pulse current, and the low-frequency pulse voltage generates a low-frequency pulse current. The high-frequency pulse current and the low-frequency pulse current have different conduction paths in the battery pole piece. The self-heating effect of the internal impedance of the battery pole piece is used to achieve three-dimensional heating from the inside out. Due to the skin effect, the high-frequency current mainly flows through the surface of the metal current collector, generating surface heat, while the low-frequency current can penetrate deeper into the active material body, generating deep heat. This forms a coordinated heating between the inside and outside, breaking through the heat conduction bottleneck of traditional external heating methods.
[0084] The impedance of the metal current collector increases with increasing temperature, while the impedance of the active material body decreases with increasing temperature. The impedance drop measured during the initial low-temperature stage of pretreatment reflects the temperature dependence of the active material body. As the temperature continues to rise to the critical value (55°C), the actual impedance is dominated by the contact impedance and the metal current collector impedance, and shows an overall upward trend. The baking temperature during the main baking stage of this application was maintained at 85±5°C. The actual resistance is that the impedance of the metal current collector is large, while the impedance of the active material body is small, so the pulse voltage is high frequency and high voltage and low frequency and low voltage. Therefore, the temperature-impedance relationship helps determine at what temperature it is more effective to use high-frequency current or low-frequency current. That is, at higher temperatures, the impedance of the current collector increases, and the high-frequency current parameters need to be adjusted to maintain sufficient surface heating. At high temperatures, the impedance of the active material decreases, and low-frequency current is more effective because the current can more easily penetrate and generate heat using the lower body resistance.
[0085] The comparative data of the battery pole pieces treated by the baking device and method of the present application and the battery pole pieces treated by the conventional heat treatment baking method of Examples 1 to 2 are shown in Table 1 below: Table 1 Battery electrode test data
[0086] From the comparative data of the above-mentioned Examples 1 to 4 and Comparative Examples 1 to 2, it can be seen that the moisture residue in the examples is significantly lower than that in the comparative examples, indicating that alternating application of high-frequency / low-frequency pulse voltage and vacuum gradient cooling can effectively improve the moisture removal efficiency. The high-frequency pulse voltage (short duration) destroys the binding force between moisture and the electrode, and the low-frequency pulse voltage (long duration) promotes moisture migration. The vacuum environment accelerates evaporation to achieve efficient dehydration; the baking time of the examples is compressed to 1 / 2~1 / 3 relative to the comparative example, and the unit dehydration energy consumption is reduced by more than 50%. The directional energy transfer of high-frequency / low-frequency pulse voltage heating reduces heat loss, and the vacuum environment lowers the boiling point and shortens the mass transfer path, which can save energy and shorten the baking time; the electrode oxidation rate of the examples is reduced by 50% relative to the comparative example, which is attributed to the low-temperature main baking (85±5°C) and precise temperature control of high-frequency / low-frequency pulse voltage, which avoids the oxidation of the battery electrode caused by traditional high-temperature baking and ensures the structural integrity of the battery electrode.
[0087] The present application provides a battery electrode baking device which fixes the battery electrode to be baked on an operating table 11 of a vacuum baking chamber 1 through a clamping module 2 to provide a vacuum environment. The pulse power supply module 3 provides a pulse voltage to the battery electrode to cause the battery electrode to self-heat. The temperature detection module 4 detects the baking temperature of the battery electrode self-heating and sends it to the pulse power supply module 3 in real time, and then dynamically adjusts the pulse voltage to a high-frequency pulse voltage or a low-frequency pulse voltage.
[0088] The present application provides a method for baking battery pole pieces, which only requires short-term high power in the high-frequency pulse stage and high duty cycle in the low-frequency pulse stage to maintain temperature, and the vacuum environment accelerates evaporation to achieve efficient dehydration. The comprehensive energy consumption is reduced by 40% to 60% compared with traditional hot air baking, and the efficiency is higher and the energy utilization rate is better. Under the premise of ensuring the structural integrity of the battery pole piece, the traditional baking time can be compressed to 1 / 2 to 1 / 3, and the moisture control accuracy can be improved to about 5ppm, and the residual moisture content is maintained at 22±6ppm, which greatly shortens the baking time and residual solvents such as pole piece moisture. At the same time, the skin effect of high-frequency current and the deeper penetration of low-frequency current can avoid the problem of poor baking temperature uniformity caused by local internal resistance deviation, which in turn leads to local over-baking or moisture residue.
[0089] The above description of the embodiments disclosed herein is intended to enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to be construed in the widest manner consistent with the principles and novel features disclosed herein.
Claims
1. A battery pole piece baking device, characterized in that: include: A vacuum baking chamber (1) is provided with an operating table (11) therein; A clamping module (2), arranged on the operating table (11), for fixing the battery electrode (5) and electrically connecting to the battery electrode (5); A pulse power module (3) is electrically connected to the clamping module (2) and is used to output a pulse electrical signal to the battery electrode (5) via the clamping module (2), thereby causing the battery electrode (5) to self-heat; A temperature detection module (4) is arranged in the vacuum baking cavity (1) and is used to detect the baking temperature of the battery electrode (5) when it is self-heated; and a control module connected to the pulse power module (3) and the temperature detection module (4), for calculating the temperature gradient inside the battery electrode (5) in real time based on the signal from the temperature detection module (4), and dynamically adjusting the parameters of the pulse electrical signal output by the pulse power module (3).
2. The battery pole piece baking device according to claim 1, characterized in that: The pulse power supply module (3) is capable of alternately outputting a high-frequency pulse voltage and a low-frequency pulse voltage with a frequency of 10 Hz to 500 kHz and a duty cycle of 10% to 90%.
3. The battery pole piece baking device according to claim 2, characterized in that: The parameters of the high-frequency pulse voltage are 20V~80V, frequency 100kHz~500kHz, duty cycle 15%~30%, and duration less than or equal to 10μs; the parameters of the low-frequency pulse voltage are 5V~30V, frequency 10Hz~100Hz, duty cycle 40%~60%, and duration 10ms~1s; the alternating period of the high-frequency pulse voltage and the low-frequency pulse voltage is that the high-frequency pulse voltage works for 1~4 minutes, and the low-frequency pulse voltage works for 1~3 minutes.
4. The battery pole piece baking device according to claim 1, characterized in that: The temperature detection module (4) comprises an infrared temperature measurement unit (41) and a contact temperature measurement unit (42); the infrared temperature measurement unit (41) is arranged on the inner wall of the vacuum baking cavity (1); and the contact temperature measurement unit (42) is connected to the clamping module (2).
5. The battery pole piece baking device according to claim 1, characterized in that: The vacuum baking cavity (1) further comprises a condensation recovery system, which is in communication with the interior of the vacuum baking cavity (1) and is used for cooling and collecting solvent volatilized during baking of the battery pole piece (5) when it generates self-heat.
6. The battery pole piece baking device according to claim 1, characterized in that: The clamping module (2) comprises a positive terminal (21) and a negative terminal (22), wherein the positive terminal (21) is used to connect to the positive electrode tab of the battery electrode, and the negative terminal (22) is used to connect to the negative electrode tab of the battery electrode.
7. A method for baking a battery electrode, characterized in that: Applicable to the battery electrode baking device according to any one of claims 1 to 6, the method comprising: Pre-processing stage: applying current to the battery electrode for pre-activation, obtaining the battery electrode impedance relationship under the temperature conditions of 25°C to 85°C and establishing a temperature-impedance curve, and detecting the initial impedance of the battery electrode; Main baking stage: according to the temperature-impedance curve, high-frequency pulse voltage and low-frequency pulse voltage are applied alternately, and the baking temperature is maintained at 85±5°C under vacuum conditions; Gradient cooling stage: reduce the amplitude of the high-frequency pulse voltage and the low-frequency pulse voltage at a rate of 0.3~0.5℃ / min until the temperature of the vacuum baking chamber is less than or equal to 40℃.
8. The battery pole piece baking method according to claim 7, characterized in that: During the pretreatment stage, a current of 0.1 to 0.5 C is applied to the battery electrode for pre-activation for 1 to 2 minutes.
9. The battery pole piece baking method according to claim 7, characterized in that: In the main baking stage, the vacuum degree of the vacuum baking chamber is less than or equal to 0.5 Pa, and the baking time is 8 to 12 hours; The alternating cycle of the high-frequency pulse voltage and the low-frequency pulse voltage is 1 to 4 minutes for the high-frequency pulse voltage and 1 to 3 minutes for the low-frequency pulse voltage; The high-frequency pulse voltage is 20V~80V, the frequency is 100kHz~500kHz, the duty cycle is 15%~30%, and the duration is less than or equal to 10μs; The low-frequency pulse voltage is 5V~30V, the frequency is 10Hz~100Hz, the duty cycle is 40%~60%, and the duration is 10ms~1s.
10. The battery pole piece baking method according to claim 7, characterized in that: In the gradient cooling stage, the lowest voltage of the high-frequency pulse voltage and the low-frequency pulse voltage is 5-15V. When the temperature of the vacuum baking cavity is less than or equal to 40°C, the vacuum baking cavity is maintained at a vacuum degree less than or equal to 0.5Pa for 1-3 hours.