A drying system and drying method for battery pole pieces

Abstract

The application relates to the technical field of batteries, in particular to a drying system and a drying method for battery pole pieces, wherein the drying system comprises a first baking unit and a second baking unit; the first baking unit comprises a laser heating module, which is used for performing first laser baking on a pole piece to be dried; and the second baking unit comprises an infrared heating module, which is used for performing infrared baking on the pole piece subjected to the first laser baking. According to the technical scheme, the laser heating module and the infrared heating module are integrated in one drying system, the problem that the existing drying system cannot simultaneously consider the pole baking speed and the baking precision is solved, and the pole baking efficiency and the pole baking quality are comprehensively improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a drying system and method for battery electrodes. Background Technology

[0002] In the manufacturing process of lithium batteries, the coating process is a crucial step in the production of the positive electrode. Coating refers to the method of applying a paste-like polymer, molten polymer, or polymer solution onto a thin-film electrode to form a composite film. After coating, the coated electrode needs to be dried to a certain degree of dryness to ensure its quality and improve its lifespan and performance. Therefore, baking is a critical node in the coating process. Abnormalities such as powder shedding, scorching, incomplete drying, insufficient compaction density, inconsistent solvent evaporation, and insufficient adhesion between the slurry and foil are all directly related to the quality of the baking process.

[0003] In principle, baking is the process of transferring external heat to the coated electrode sheet. It is an energy input and output process and a process of completing heat exchange. Currently, common electrode baking methods include hot air baking, infrared baking, and laser baking. Among them, infrared baking has the disadvantage of slow baking speed, while hot air baking and laser baking have problems with baking uniformity and temperature control accuracy. Existing electrode baking methods are difficult to balance the baking speed and temperature control accuracy during the baking process. Summary of the Invention

[0004] This application provides a drying system and method for battery electrodes, which can improve the accuracy of temperature control of the electrodes during the baking process while taking into account the baking speed, thereby improving the baking quality of the electrodes.

[0005] In a first aspect, embodiments of this application provide a method for drying battery electrodes, comprising the steps of:

[0006] The electrode sheet to be dried is subjected to the first laser baking;

[0007] The electrode sheet after the first laser baking is then subjected to infrared baking to obtain a dry electrode sheet.

[0008] In one embodiment, the first laser baking includes a heating stage and a constant temperature stage. In the heating stage, the power of the laser heating module for the first laser baking is adjusted to a first threshold. When the temperature of the electrode reaches the temperature of the constant temperature stage, the power of the laser heating module for the first laser baking is reduced so that the temperature of the electrode is maintained within the temperature range of the constant temperature stage.

[0009] In one embodiment, the laser wavelength for the first laser baking is 600μm to 1080μm.

[0010] In one embodiment, the laser power of the first laser baking is 2000W to 30000W.

[0011] In one embodiment, the laser power density of the first laser baking is 120 W / cm². 2 ~160W / cm 2 .

[0012] In one embodiment, the first laser baking has a heating phase, the heating phase lasting from 0.1s to 3s.

[0013] In one embodiment, the first laser baking has a constant temperature stage, the temperature of which is 125°C to 160°C.

[0014] In one embodiment, the duration of the first laser baking is 5 to 65 seconds.

[0015] In one embodiment, the infrared wavelength of the infrared baking is 1.0 μm to 1.4 μm.

[0016] In one embodiment, the infrared power of the infrared baking is 500W to 9000W.

[0017] In one embodiment, the infrared power density of the infrared baking is 160 W / m². 2 ~200W / m 2 .

[0018] In one embodiment, the infrared baking temperature is 120°C to 145°C.

[0019] In one embodiment, the infrared baking time is 5s to 30s.

[0020] In one embodiment, after the infrared baking, the drying method further includes hot air drying of the infrared-baked electrode, wherein the temperature of the hot air drying is 70°C to 110°C and the fan frequency of the hot air drying is 16Hz to 35Hz.

[0021] In one embodiment, after the hot air drying process, the drying method further includes subjecting the hot air-dried electrode to a second laser baking.

[0022] In one embodiment, the laser wavelength for the second laser baking is 600μm to 1080μm.

[0023] In one embodiment, the laser power of the second laser baking is 500W to 1500W.

[0024] In one embodiment, the laser power density of the second laser baking is 30 W / cm². 2 ~80W / cm 2 .

[0025] In one embodiment, the second laser baking time is 5s to 65s.

[0026] In one embodiment, prior to the first laser baking, the drying method further includes unwinding the electrode to provide the electrode to be dried; and / or,

[0027] The drying method further includes winding up the obtained dried electrode sheets.

[0028] In one embodiment, after the electrode is unwound, the drying method further includes correcting the electrode's deviation and / or adjusting its tension.

[0029] In one embodiment, after the electrode is unwound and before the first laser baking, the drying method further includes applying a slurry to the electrode.

[0030] Secondly, this application also proposes a drying system for battery electrodes, comprising:

[0031] The first baking unit includes a first laser heating module, which is used to perform the first laser baking on the electrode sheet to be dried.

[0032] The second baking unit includes an infrared heating module for infrared baking the electrode sheet that has been baked by the first laser.

[0033] In one embodiment, the first baking unit further includes a first temperature detection module for detecting the temperature of the electrode during the first laser baking process. The first laser heating module is electrically connected to the first temperature detection module, and the power of the first laser heating module is adjusted according to the detection result of the first temperature detection module; and / or,

[0034] The second baking unit further includes a second temperature detection module, which is electrically connected to the infrared heating module. The second temperature detection module is used to detect the temperature of the electrode during the infrared baking process, and the power of the infrared heating module is adjusted according to the detection result of the second temperature detection module.

[0035] In one embodiment, the drying system further includes a control module electrically connected to the first laser heating module, the infrared heating module, the first temperature detection module, and the second temperature detection module. The control module adjusts the power of the infrared heating module according to the detection result of the second temperature detection module, and adjusts the power of the first laser heating module according to the detection result of the first temperature detection module.

[0036] In one embodiment, the drying system further includes an oven and a hot air drying module, wherein the light outlets of the first laser heating module and the infrared heating module are connected to the interior of the oven, and the air outlet of the hot air drying module is connected to the interior of the oven.

[0037] In one embodiment, the drying system further includes a second laser heating module, which is located downstream of the infrared heating module.

[0038] In one embodiment, the first laser heating module, the infrared heating module, and the second laser heating module located on the same side of the electrode are arranged at equal intervals, and there are multiple hot air drying modules, which are respectively located between the first laser heating module, the infrared heating module, and the second laser heating module located on the same side of the electrode.

[0039] In one embodiment, a first laser heating module, an infrared heating module, and a second laser heating module are provided on both sides of the electrode's orientation. The first laser heating module, the infrared heating module, and the second laser heating module located on one side of the electrode's orientation are offset from the first laser heating module, the infrared heating module, and the second laser heating module located on the other side of the electrode's orientation along the orientation of the electrode.

[0040] In one embodiment, the drying system further includes an unwinding unit for supplying the electrode sheet and a winding unit for winding the electrode sheet, wherein the first laser heating module and the infrared heating module are arranged sequentially along the direction of the electrode sheet, and the first laser heating module is located upstream of the infrared heating module.

[0041] In one embodiment, the drying system further includes a tension adjustment unit and / or a web-correcting unit, the tension adjustment unit and / or the web-correcting unit being located downstream of the unwinding unit.

[0042] In one embodiment, the drying system further includes a coating unit located on both sides of the electrode orientation between the unwinding unit and the first laser heating module.

[0043] Compared with the prior art, this technical solution has at least the following technical advantages:

[0044] The drying method of this application combines laser heating and infrared heating to bake the electrode sheet sequentially, solving the problem that existing drying methods cannot simultaneously achieve baking speed and baking precision, thus comprehensively improving the baking efficiency and quality of the electrode sheet. In the technical solution of this application, during the baking process of the electrode sheet, laser heating is first used to bake the electrode sheet for the first time, which rapidly raises the temperature of the electrode sheet and causes a large amount of solvent on the surface and inside of the electrode sheet coating to evaporate quickly, shortening the time of the heating stage and the constant drying rate stage of the electrode sheet; then infrared heating is used to bake the electrode sheet for infrared baking, which enables precise control of the temperature of the electrode sheet during the deceleration drying stage. This helps to avoid excessive temperature fluctuations during the deceleration drying stage, which could lead to degradation of the binder and deterioration of the active material in the electrode sheet coating, thus improving the baking quality of the electrode sheet.

[0045] This application's technical solution integrates a laser heating module and an infrared heating module into a single drying system, solving the problem that existing drying systems cannot simultaneously achieve both baking speed and precision for electrode sheets, thus comprehensively improving the baking efficiency and quality. The inventors discovered that during the drying process of the electrode sheet, it undergoes three kinetic stages: a heating stage, a constant drying rate stage, and a decreasing drying rate stage. The heating stage primarily involves the evaporation of solvent from the electrode coating surface, which diffuses through the interface in a gas-liquid two-phase manner. Once the solvent on the electrode coating surface is completely vaporized, the constant drying rate stage begins. In this stage, solvents such as NMP and water in the electrode coating evaporate in large quantities. During this stage, solvents inside the electrode coating continuously migrate to the surface due to capillary action, accumulating and evaporating on the surface, causing the electrode coating to gradually shrink. This stage is relatively time-consuming. When the moisture content inside the coating is low, reaching a critical state, the decreasing drying rate stage begins. The drying rate in this stage is controlled by the solvent migration rate, i.e., by the particle and inter-particle distribution of the electrode coating. This stage requires high precision in controlling the baking temperature. In the technical solution of this application, during the electrode baking process, a first laser heating module is used to perform a first laser baking on the electrode. This first laser heating module enables the electrode temperature to rise rapidly, causing a large amount of solvent on the surface and inside of the electrode coating to evaporate quickly, shortening the time of the heating stage and the constant drying rate stage. Then, an infrared heating module is used to perform infrared baking on the electrode. The infrared heating module has high power adjustment precision, enabling precise control of the temperature during the deceleration drying stage of the electrode. This helps avoid excessive temperature fluctuations during the deceleration drying stage, which could lead to degradation of the binder and deterioration of the active material in the electrode coating, thus improving the baking quality of the electrode. The drying system of this application integrates the laser heating module and the infrared heating module, enabling rapid and efficient baking of the electrode with high quality. Attached Figure Description

[0046] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0047] Figure 1 This is a schematic flowchart of one embodiment of the drying method of this application;

[0048] Figure 2 This is a schematic diagram of the drying system of this application in one embodiment;

[0049] Figure 3 This is a schematic diagram of the drying system of this application in another embodiment;

[0050] Figure 4 This is a schematic diagram of the drying system of this application in another embodiment.

[0051] Figure label:

[0052] 100 Drying system 110 First laser heating module 120 Infrared heating module 130 Hot air drying module 140 Oven 150 Second laser heating module 160 roller 171 Unwinding unit 172 Rewinding unit 181 Tension Adjustment Unit 182 Correction unit 183 Coating module 200 Polaroid Detailed Implementation

[0053] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0054] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0055] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0056] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0057] Currently, common electrode baking methods include hot air baking, infrared baking, and laser baking. Among them, infrared baking has the disadvantage of slow baking speed, while hot air baking and laser baking have problems with baking uniformity and temperature control accuracy. Existing electrode baking methods are difficult to balance the baking speed and temperature control accuracy during the baking process.

[0058] To address the aforementioned technical problems, in a first aspect, this application proposes a method for drying battery electrodes.

[0059] Please refer to Figure 1 In an embodiment of this application, the drying method includes the following steps:

[0060] S10. Perform the first laser baking on the electrode sheet to be dried;

[0061] S20. The electrode sheet after the first laser baking is subjected to infrared baking to obtain a dry electrode sheet.

[0062] The drying method of this application combines laser heating and infrared heating to bake the electrode sheet sequentially, solving the problem that existing drying methods cannot simultaneously achieve baking speed and baking precision, thus comprehensively improving the baking efficiency and quality of the electrode sheet. In the technical solution of this application, during the baking process of the electrode sheet, laser heating is first used to bake the electrode sheet for the first time, which rapidly raises the temperature of the electrode sheet and causes a large amount of solvent on the surface and inside of the electrode sheet coating to evaporate quickly, shortening the time of the heating stage and the constant drying rate stage of the electrode sheet; then infrared heating is used to bake the electrode sheet for infrared baking, which enables precise control of the temperature of the electrode sheet during the deceleration drying stage. This helps to avoid excessive temperature fluctuations during the deceleration drying stage, which could lead to degradation of the binder and deterioration of the active material in the electrode sheet coating, thus improving the baking quality of the electrode sheet.

[0063] In one embodiment, the first laser baking includes a heating stage and a constant temperature stage. In the heating stage, the power of the laser heating module (corresponding to the first laser heating module 110 below) for the first laser baking is adjusted to a first threshold. In a preferred embodiment, the first threshold is the maximum power value of the laser heating module. When the temperature of the electrode reaches the temperature of the constant temperature stage, the power of the laser heating module (corresponding to the first laser heating module 110 below) for the first laser baking is reduced so that the temperature of the electrode is maintained within the temperature range of the constant temperature stage. By adjusting the power of the laser heating module (corresponding to the first laser heating module 110 below) for the first laser baking to a first threshold during the heating stage, the temperature of the electrode surface can rise rapidly, and the solvent in the electrode coating can quickly enter boiling, effectively improving the drying efficiency of the electrode. When the temperature of the electrode reaches the temperature of the constant temperature stage, the power of the laser heating module (corresponding to the first laser heating module 110 below) for the first laser baking is appropriately reduced, so that the solvent in the electrode coating evaporates slowly, which helps to avoid the coating on the electrode surface from cracking due to excessive baking temperature, thus improving the baking quality of the electrode and also saving energy.

[0064] More specifically, in one embodiment, the laser wavelength of the first laser baking is 600μm to 1080μm, specifically 600μm, 700μm, 800μm, 900μm, 1080μm or any value between them.

[0065] In one embodiment, the laser power of the first laser baking is 2000W to 30000W, specifically 2000W, 2200W, 2400W, 2600W, 2800W, 30000W or any value between them.

[0066] In one specific embodiment, the laser power density of the first laser baking is 120 W / cm². 2 ~160W / cm 2 Specifically, it can be 120W / cm 2 130W / cm 2 140W / cm 2 160W / cm 2 Or any value between them.

[0067] In one embodiment, the heating phase lasts from 0.1s to 3s, specifically 0.1s, 1s, 2s, 3s, or any value between them. By using laser heating to perform the first laser baking on the electrode, the temperature of the electrode surface can be rapidly increased, thereby allowing the solvent in the electrode coating to evaporate quickly.

[0068] The temperature during the constant-temperature stage is between 125℃ and 160℃, specifically 125℃, 130℃, 135℃, 140℃, 145℃, 160℃, or any value between them. By controlling the temperature during the constant-temperature stage within the above range, the baking efficiency of the electrode sheet can be improved while ensuring baking quality. The specific temperature of the constant-temperature stage is related to the coating thickness of the electrode sheet; the thicker the coating, the more difficult it is to dry, and the longer the constant-temperature stage will be.

[0069] In one embodiment, the first laser baking time is 5s to 65s, specifically 5s, 10s, 16s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s, 60s, 65s, or any value between them. The specific time of the first laser baking is related to the coating thickness of the electrode. The thicker the coating, the more difficult it is to dry, and the longer the first laser baking time will be. For example, compared to ternary cathodes, lithium iron phosphate electrodes have a thicker coating area, and their first laser baking time is also longer.

[0070] In one embodiment, the infrared wavelength of the infrared baking is 1.0 μm to 1.4 μm, specifically 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or any value between them.

[0071] In one embodiment, the infrared power of the infrared baking is 500W to 9000W, specifically 500W, 1000W, 2000W, 3000W, 4000W, 5000W, 6000W, 7000W, 8000W, 9000W, or any value between them. During the infrared baking process, the infrared power can be adjusted in real time according to the temperature of the electrode surface to precisely control the infrared baking temperature.

[0072] In one specific embodiment, the infrared power density of the infrared baking is 160 W / m². 2 ~200W / m 2 Specifically, it can be 160W / m 2 170W / m 2 180W / m 2 180W / m 2 190W / m 2 200W / m 2 Or any value between them.

[0073] In one embodiment, the infrared baking temperature is 120°C to 145°C, specifically 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, or any value between them. By controlling the infrared baking temperature within the above range, the baking efficiency of the electrode can be improved while ensuring baking quality.

[0074] In one embodiment, the infrared baking time is 5s to 30s, specifically 5s, 10s, 16s, 20s, 25s, 30s or any value between them; if the infrared baking time is too short, the electrode may not be dried, and if the infrared baking time is too long, the baking quality of the electrode may be affected.

[0075] In one embodiment, the drying method is performed based on the drying system 100 as described above.

[0076] In one embodiment, after the infrared baking, the drying method further includes hot air drying of the infrared-baked electrode to further dry and remove dust from the infrared-baked electrode.

[0077] The temperature of the hot air drying process is 70℃~110℃, specifically 70℃, 80℃, 90℃, 100℃, 110℃ or any value between them.

[0078] The frequency of the fan used in the hot air drying process is 16Hz to 35Hz, specifically 16Hz, 20Hz, 25Hz, 30Hz, 35Hz or any value between them.

[0079] In the later stage of electrode drying (late stage of falling-rate drying), hot air convection is used to dry the electrode, which can prevent solutes in the electrode coating from migrating to the surface of the electrode coating through capillary action. This further reduces the impact of the migration of solutes such as binders on the baking quality and further improves the baking quality of the electrode.

[0080] In one embodiment, during the first laser baking process, hot air convection is simultaneously used to dry the electrode sheet, and / or during the infrared baking process, hot air is simultaneously used to dry the electrode sheet, which can further improve the drying efficiency of the electrode sheet.

[0081] In one embodiment, after the hot air drying process, the drying method further includes subjecting the hot-air-dried electrode to a second laser baking. The second laser baking delivers energy to solutes that have migrated to the surface of the electrode coating, causing these solutes to migrate back into the electrode coating, further improving the baking quality of the electrode.

[0082] Specifically, the laser wavelength for the second laser baking is 600μm to 1080μm, and can be 600μm, 700μm, 800μm, 900μm, 1080μm or any value between them.

[0083] The laser power of the second laser baking is 500W to 1500W, specifically 500W, 800W, 1000W, 1200W, 1400W, 15000W or any value between them.

[0084] The laser power density of the second laser baking is 30 W / cm². 2 ~80W / cm 2 Specifically, it can be 30W / cm 2 40W / cm 2 50W / cm 2 60W / cm 2 70W / cm 2 80W / cm 2 Or any value between them.

[0085] The second laser baking time is 5s to 65s, specifically 5s, 10s, 16s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, 55s, 60s, 65s or any value between them.

[0086] In one embodiment, prior to the first laser baking, the drying method further includes unwinding the electrode sheet to provide an electrode sheet to be dried; and / or, the drying method further includes winding the obtained dried electrode sheet. Both ends of the electrode sheet are wound onto an unwinding unit 171 and a winding unit 172, respectively. During the baking process, the unwinding unit 171 and the winding unit 172 rotate simultaneously, continuously releasing the electrode sheet from the unwinding unit 171 and winding it onto the winding unit 172 after baking. By utilizing the rotational cooperation of the unwinding unit 171 and the winding unit 172 for electrode sheet transport, continuous baking of the electrode sheet can be achieved. The entire process is automated, greatly improving the baking efficiency of the electrode sheet and reducing labor costs.

[0087] Based on the above implementation method, in a specific embodiment, the laser action area of ​​the first laser baking is the same as that of the second laser baking. In order to avoid excessive stretching of the electrode sheet during transmission, the time of the first laser baking is the same as that of the second laser baking.

[0088] In one embodiment, after the electrode is unwound and before the first laser baking, the drying method further includes coating the electrode with a slurry. The specific coating thickness of the slurry depends on the type of electrode and is not limited thereto in this application.

[0089] In one embodiment, after the electrode is unwound, the drying method further includes correcting the electrode and / or adjusting its tension to improve the accuracy of electrode feeding (unwinding) and rewinding, and to prevent it from becoming loose or shifting.

[0090] Secondly, this application also proposes a drying system 100 for battery electrode 200.

[0091] Please see Figure 2 , Figure 3 and Figure 4 In this embodiment of the application, the drying system 100 includes a first baking unit and a second baking unit; the first baking unit includes a first laser heating module 110, which is used to perform a first laser baking on the electrode 200 to be dried; the second baking unit includes an infrared heating module 120, which is used to perform infrared baking on the electrode 200 that has undergone the first laser baking.

[0092] This application's technical solution integrates the laser heating module 110 and the infrared heating module 120 into a single drying system 100, solving the problem that existing drying systems 100 cannot simultaneously achieve both baking speed and baking precision for the electrode 200, thus comprehensively improving the baking efficiency and quality of the electrode 200. The inventors discovered that during the drying process of the electrode 200, it undergoes three kinetic stages: a heating stage, a constant drying rate stage, and a decreasing drying rate stage. The heating stage mainly involves the evaporation of solvent on the surface of the electrode 200 coating, which diffuses through the interface in a gas-liquid two-phase manner. When the solvent on the surface of the electrode 200 coating is completely vaporized, it enters the constant drying rate stage. In this stage, solvents such as NMP and water in the electrode 200 coating evaporate in large quantities. During this stage, the solvent inside the coating migrates to the surface due to capillary action and accumulates and evaporates on the surface, causing the coating to gradually shrink. This stage takes a relatively long time. When the moisture content inside the electrode 200 coating is low and reaches the critical state, the electrode 200 enters the falling rate drying stage. The drying rate of the electrode 200 in this stage is controlled by the solvent migration rate, that is, by the distribution of particles and gaps in the electrode 200 coating. This stage requires high precision in controlling the baking temperature. In the technical solution of this application, during the baking process of the electrode 200, the first laser heating module 110 can be used to perform a first laser baking on the electrode 200. The first laser heating module 110 can rapidly raise the temperature of the electrode 200, causing a large amount of solvent on the surface and inside of the electrode 200 coating to evaporate quickly, shortening the time of the heating stage and the constant drying rate stage of the electrode 200. Then, the infrared heating module 120 is used to perform infrared baking on the electrode 200. The infrared heating module 120 has high power adjustment accuracy and can achieve precise control of the temperature of the electrode 200 during the deceleration drying stage. This helps to avoid excessive temperature fluctuations during the deceleration drying stage, which could lead to degradation of the binder and deterioration of the active material in the coating of the electrode 200, thus improving the baking quality of the electrode 200. The drying system 100 of this application first utilizes the characteristics of rapid heating, small footprint and easy adjustment of the laser heating module to preheat the electrode sheet, and then uses the infrared heating module to further bake the electrode sheet. The infrared heating module can fine-tune the baking temperature of the electrode sheet, realize precise control of the baking temperature of the electrode sheet, and comprehensively improve the baking efficiency and baking quality of the electrode sheet.

[0093] In some embodiments, the first baking unit further includes a first temperature detection module, which is used to detect the temperature of the electrode 200 during the first laser baking process. The first laser heating module 110 is electrically connected to the first temperature detection module, and the power of the first laser heating module 110 is adjusted according to the detection result of the first temperature detection module. In a specific embodiment, the first temperature detection module can be an infrared camera, an infrared thermal imager, a thermocouple, or a temperature sensor, etc., and is specifically used to detect the temperature of the coating surface of the electrode 200 during the first laser baking process. Of course, the first temperature detection module can also be other types of temperature detection modules, and this application does not limit it.

[0094] In the middle and late stages of the first laser baking phase, the internal and external temperatures of the electrode 200 coating both reach preset values, and the electrode 200 enters the constant drying rate stage. The solvent in the electrode 200 coating evaporates slowly, which can appropriately reduce the power of the first laser heating module 110. This application sets up a first temperature detection module to monitor the temperature of the electrode 200 coating in real time. When the electrode 200 enters the constant drying rate stage, it can promptly feed this information back to the first laser heating module 110, so that the power of the first laser heating module 110 can be appropriately reduced. This is beneficial to improving the baking quality of the electrode 200 and also has an energy-saving effect.

[0095] To further improve the temperature control accuracy during the infrared baking stage, in some embodiments, the second baking unit further includes a second temperature detection module electrically connected to the infrared heating module 120. The second temperature detection module is used to detect the temperature of the electrode 200 during the infrared baking process, and the power of the infrared heating module 120 is fine-tuned based on the detection result of the second temperature detection module. In one specific embodiment, the second temperature detection module can be an infrared camera, an infrared thermal imager, a thermocouple, or a temperature sensor, etc., and is specifically used to detect the temperature of the coating surface of the electrode 200 during the infrared baking process. Of course, the second temperature detection module can also be other types of temperature detection modules, and this application does not limit it.

[0096] During the infrared baking process, as the drying process progresses, the composition of the electrode 200 coating and the surrounding environment will change, and the optimal baking temperature required for the electrode 200 coating will also change accordingly. In the above embodiment, the second temperature detection module can monitor the temperature of the electrode 200 coating in real time and promptly feed this information back to the infrared heating module 120, so that the power of the infrared heating module 120 can be adjusted appropriately in time to avoid the quality of the electrode 200 coating being damaged due to excessively high baking temperature, or the baking efficiency of the electrode 200 coating being affected due to excessively low baking temperature.

[0097] Based on the above embodiments, in some embodiments, the drying system 100 further includes a control module, which is electrically connected to the first laser heating module 110, the infrared heating module 120, the first temperature detection module, and the second temperature detection module. The control module adjusts the power of the infrared heating module 120 according to the detection result of the second temperature detection module, and adjusts the power of the first laser heating module 110 according to the detection result of the first temperature detection module.

[0098] Specifically, the control module has a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The output terminal of the first temperature detection module is electrically connected to the first input terminal of the control module, the first output terminal of the control module is electrically connected to the first laser heating module 110, the output terminal of the second temperature detection module is electrically connected to the second input terminal of the control module, and the second output terminal of the control module is electrically connected to the infrared heating module 120. During the first laser baking process, the first temperature detection module promptly feeds back the temperature data of the electrode 200 coating surface to the control module, and the control module adjusts the power of the first laser heating module 110 according to the temperature data. Similarly, during the infrared baking process, the second temperature detection module promptly feeds back the temperature data of the electrode 200 coating surface to the control module, and the control module adjusts the power of the infrared heating module 120 according to the temperature data.

[0099] In one embodiment, the drying system 100 further includes an oven 140 and a hot air drying module 130. The light outlets of the first laser heating module 110 and the infrared heating module 120 are connected to the interior of the oven 140, and the air outlet of the hot air drying module 130 is connected to the interior of the oven 140. The size of the oven 140 can be adjusted according to actual conditions, and this application does not impose any particular limitation on it. In one specific embodiment, the air frequency of the hot air drying module 130 is 16 to 35, specifically 16, 20, 25, 30, 35, or any value between them.

[0100] The hot air drying module 130 can be one or more. When there is only one hot air drying module 130, preferably, the hot air drying module 130 is located downstream of the infrared heating module 120. The infrared heating module 120 is used to further dry and remove dust from the infrared-baked electrode 200. In the later stage of drying the electrode 200 (later stage of the slow-down drying phase), hot air convection is used to dry the electrode 200, which can prevent solutes in the electrode coating from migrating to the surface of the electrode coating through capillary action, further reducing the impact of the migration of solutes such as binders on the baking quality. When there are multiple hot air drying modules 130, they can be evenly arranged along the direction of the electrode 200, so that the gas in the oven 140 is evenly convectioned, which can improve the baking uniformity and baking rate of the electrode 200.

[0101] Please refer to Figure 4 In some embodiments, the drying system 100 further includes a second laser heating module 150, which is located downstream of the infrared heating module 120. More specifically, the second laser heating module 150 is also located downstream of the hot air drying module 130. The second laser heating module 150 is used to perform a second laser baking on the electrode 200 that has undergone infrared baking and hot air convection drying. The second laser baking delivers energy to the solutes that have migrated to the surface of the electrode coating, causing these solutes to migrate back into the coating of the electrode 200, thereby further improving the baking quality of the electrode 200.

[0102] Based on the above embodiments, in one embodiment, the number of hot air drying modules 130 is multiple, and the multiple hot air drying modules 130 are respectively disposed between the first laser heating module 110, the infrared heating module 120 and the second laser heating module 150 located on the same side of the electrode 200. For example, the number of hot air drying modules 130 is not less than two, at least one hot air drying module 130 is disposed between the first laser heating module 110 and the infrared heating module 120, and at least one hot air drying module 130 is disposed between the infrared heating module 120 and the second laser heating module 150. The specific number of hot air drying modules 130 can be adjusted according to the actual situation, and this application does not make a specific limitation.

[0103] In one specific embodiment, the first laser heating module 110, the infrared heating module 120, the second laser heating module 150, and the plurality of hot air drying modules 130 are arranged at equal intervals along the direction of the electrode 200.

[0104] Since both sides of the electrode 200 are coated with a paste, meaning both sides of the electrode 200 need to be baked, in order to improve baking efficiency and baking uniformity, in one embodiment, please refer to... Figure 2 The electrode 200 is provided with the first laser heating module 110, the infrared heating module 120 and the second laser heating module 150 on both sides to bake the two sides (the first side and the second side) of the electrode 200 respectively.

[0105] Correspondingly, the first temperature detection module includes a first temperature sensor and a second temperature sensor. The first temperature sensor is electrically connected to the first laser heating module on one side of the electrode 200 to measure the temperature of the first side surface of the electrode 200 during the first laser baking process. The second temperature sensor is electrically connected to the second laser heater 112 on the other side of the electrode 200 to measure the temperature of the second side surface of the electrode 200 during the first laser baking process.

[0106] The second temperature detection module includes a third temperature sensor and a fourth temperature sensor. The third temperature sensor is electrically connected to the infrared heater 121 on one side of the electrode 200 to measure the temperature of the first side surface of the electrode 200 during the infrared baking process. The fourth temperature sensor is electrically connected to the infrared heater 122 on the other side of the electrode 200 to measure the temperature of the second side surface of the electrode 200 during the infrared baking process.

[0107] Please refer to Figure 4 Furthermore, the first laser heating module 110, the infrared heating module 120, and the second laser heating module 150 located on one side of the electrode 200 are staggered from the first laser heating module 110, the infrared heating module 120, and the second laser heating module 150 located on the other side of the electrode 200 along the direction of the electrode 200. Specifically, during the drying process of the electrode 200, the two laser heating modules 110 successively bake the upper and lower surfaces of the same section of the electrode 200, then the two infrared heating modules 120 successively bake the upper and lower surfaces of the same section of the electrode 200, and then the two second laser heating modules 150 successively bake the upper and lower surfaces of the same section of the electrode 200. This avoids the situation where the baking temperature of a local section of the electrode 200 is too high, and improves the baking efficiency of the electrode 200 while taking into account the baking quality of the electrode 200.

[0108] Please continue reading. Figure 2 and Figure 3In one embodiment, the drying system 100 further includes an unwinding unit 171 for supplying the electrode 200 and a winding unit 172 for winding the electrode 200. The first laser heating module 110 and the infrared heating module 120 are arranged sequentially along the direction of the electrode 200, with the first laser heating module 110 located upstream of the infrared heating module 120. One end of the electrode 200 is wound onto the unwinding unit 171, and the other end is wound onto the winding unit 172. During the baking process of the electrode 200, the unwinding unit 171 rotates to release the electrode 200. After the electrode 200 is coated with slurry, it is baked sequentially by the first laser heating module 110 and the infrared heating module 120. After baking, the winding unit 172 rotates to wind the dried electrode 200 onto the winding unit 172.

[0109] More specifically, during the baking process of the electrode 200, the unwinding unit 171 and the rewinding unit 172 rotate simultaneously. The electrode 200 is continuously unwound from the unwinding unit 171 and successively conveyed to the corresponding positions of the first laser heating module 110 and the infrared heating module 120 for baking, and then rewound onto the rewinding unit 172 after baking. By utilizing the rotational coordination of the unwinding unit 171 and the rewinding unit 172 for conveying the electrode 200, continuous baking of the electrode 200 can be achieved. The entire process is automated, greatly improving the baking efficiency of the electrode 200 and reducing labor costs.

[0110] Understandably, the drying system 100 also includes a coating module 183, which is disposed between the winding unit 172 and the first laser heating module 110. After the electrode 200 is released from the unwinding unit 171, the coating module 183 applies a slurry (coating) to the surface of the electrode 200. Then, the electrode 200 is successively baked by the first laser heating module 110, the infrared heating module 120, the hot air drying module, and the second laser heating module 150. After baking, the dried electrode 200 is wound onto the winding unit 172 as the winding unit 172 rotates.

[0111] Based on the above embodiments, in one embodiment, a plurality of rollers 160 are sequentially arranged on the direction of the electrode 200 located between the unwinding unit 171 and the winding unit 172. During the baking process of the electrode 200, the rollers 160 are located below the electrode 200 to support the electrode 200. The rollers 160 rotate as the electrode 200 is conveyed.

[0112] Please see Figure 2 and Figure 3In one embodiment, the drying system 100 further includes a tension adjustment unit 181 and / or a deviation correction unit 182, wherein the tension adjustment unit 181 and / or the deviation correction unit 182 are located downstream of the unwinding unit 171. During the electrode drying process, the adjustment unit and / or the deviation correction unit 182 improve the accuracy of the electrode 200 during feeding and winding, preventing it from becoming loose or shifting.

[0113] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for drying battery electrode sheets, wherein the solvent for drying the battery electrode sheets is an NMP solvent system, characterized in that, The method for drying the battery electrode includes the following steps: The electrode to be dried is subjected to a first laser baking, wherein the laser wavelength for the first laser baking is 600μm~1080μm and the laser power density for the first laser baking is 120 W / cm². 2 ~160W / cm 2 ; The electrode sheet after the first laser baking is then subjected to infrared baking. The infrared wavelength of the infrared baking is 1.0 μm to 1.4 μm, and the infrared power density of the infrared baking is 160 W / m². 2 ~200W / m 2 ; The infrared-baked electrode sheet is then subjected to hot air drying. The electrode sheet after hot air drying is subjected to a second laser baking, with a laser power density of 30 W / cm². 2 ~80W / cm 2 Dry electrode sheets are obtained; The drying process of the electrode includes a heating stage, a constant drying rate stage, and a deceleration drying stage, which are performed sequentially. The first laser baking is used to dry the electrode during the heating stage and the constant drying rate stage; the infrared baking is used to dry the electrode during the deceleration drying stage. The first laser baking includes a heating stage and a constant temperature stage. In the heating stage, the power of the laser heating module for the first laser baking is adjusted to a first threshold. When the temperature of the electrode reaches the temperature of the constant temperature stage, the power of the laser heating module for the first laser baking is reduced so that the temperature of the electrode is maintained within the temperature range of the constant temperature stage.

2. The drying method as described in claim 1, characterized in that, The drying method includes at least one of the following features (1)-(7): (1) The laser power of the first laser baking is 2000W~30000W; (2) The heating phase lasts for 0.1s to 3s; (3) The temperature during the constant temperature stage is 125°C to 160°C; (4) The time for the first laser baking is 5s~65s; (5) The infrared power of the infrared baking is 500W~9000W; (6) The infrared baking temperature is 120°C to 145°C; (7) The infrared baking time is 5s~30s.

3. The drying method according to any one of claims 1-2, characterized in that, The temperature of the hot air drying process is 70℃~110℃, and the fan frequency of the hot air drying process is 16Hz~35Hz.

4. The drying method as described in claim 1, characterized in that, The drying method further includes at least one of the following features (1)-(3): (1) The laser wavelength of the second laser baking is 600 μm~1080 μm; (2) The laser power of the second laser baking is 500 W to 1500 W; (3) The time for the second laser baking is 5s~65s.

5. The drying method as described in claim 1, characterized in that, Prior to the first laser baking, the drying method further includes unwinding the electrode to provide the electrode to be dried; and / or, The drying method further includes winding up the obtained dried electrode sheets.

6. The drying method as described in claim 5, characterized in that, After the electrode is unwound, the drying method further includes correcting the electrode's deviation and / or adjusting its tension.

7. The drying method as described in claim 5, characterized in that, After the electrode is unwound and before the first laser baking, the drying method further includes applying a slurry to the electrode.

8. A drying system for battery electrodes adapted to the drying method according to any one of claims 1-7, characterized in that, include: The first baking unit includes a first laser heating module, which is used to perform the first laser baking on the electrode sheet to be dried. The second baking unit includes an infrared heating module for infrared baking the electrode sheet that has been subjected to the first laser baking. A hot air drying module is located downstream of the infrared heating module to dry and remove dust from the infrared-baked electrode sheets. The second laser heating module is located downstream of the hot air drying module and is used to perform a second laser baking on the electrode sheet that has passed through the hot air drying module. The drying process of the electrode includes a heating stage, a constant drying rate stage, and a deceleration drying stage, which are performed sequentially. The first laser baking is used to dry the electrode during the heating stage and the constant drying rate stage; the infrared baking is used to dry the electrode during the deceleration drying stage.

9. The drying system as described in claim 8, characterized in that, The first baking unit further includes a first temperature detection module, which is used to detect the temperature of the electrode during the first laser baking process. The first laser heating module is electrically connected to the first temperature detection module, and the power of the first laser heating module is adjusted according to the detection result of the first temperature detection module; and / or, The second baking unit further includes a second temperature detection module, which is electrically connected to the infrared heating module. The second temperature detection module is used to detect the temperature of the electrode during the infrared baking process, and the power of the infrared heating module is adjusted according to the detection result of the second temperature detection module.

10. The drying system as described in claim 9, characterized in that, The drying system further includes a control module, which is electrically connected to the first laser heating module, the infrared heating module, the first temperature detection module, and the second temperature detection module. The control module adjusts the power of the infrared heating module according to the detection result of the second temperature detection module, and adjusts the power of the first laser heating module according to the detection result of the first temperature detection module.

11. The drying system as described in claim 8, characterized in that, The drying system also includes an oven, with the light outlets of the first laser heating module and the infrared heating module connected to the interior of the oven, and the air outlet of the hot air drying module connected to the interior of the oven.

12. The drying system as described in claim 8, characterized in that, The first laser heating module, the infrared heating module, and the second laser heating module, located on the same side of the electrode, are arranged at equal intervals. There are multiple hot air drying modules, which are respectively located between the first laser heating module, the infrared heating module, and the second laser heating module, which are arranged adjacent to each other on the same side of the electrode.

13. The drying system as described in claim 8, characterized in that, The first laser heating module, the infrared heating module, and the second laser heating module are provided on both sides of the electrode's orientation. The first laser heating module, the infrared heating module, and the second laser heating module located on one side of the electrode's orientation are offset from the first laser heating module, the infrared heating module, and the second laser heating module located on the other side of the electrode's orientation along the orientation of the electrode.

14. The drying system as described in claim 8, characterized in that, The drying system further includes an unwinding unit for supplying the electrode sheet and a winding unit for winding the electrode sheet. The first laser heating module and the infrared heating module are arranged sequentially along the direction of the electrode sheet, with the first laser heating module located upstream of the infrared heating module.

15. The drying system as described in claim 14, characterized in that, The drying system further includes a tension adjustment unit and / or a web correction unit, wherein the tension adjustment unit and / or the web correction unit are located downstream of the unwinding unit.

16. The drying system as described in claim 14, characterized in that, The drying system also includes a coating unit, which is located on both sides of the electrode orientation between the unwinding unit and the first laser heating module.

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