Drying oven air supply system for improving coating cracking of negative electrode of lithium ion battery

Abstract

The utility model discloses a drying oven air supply system for improving coating cracking of a negative electrode of a lithium ion battery, which comprises a drying oven system, the drying oven system comprises a plurality of drying ovens connected in sequence, and each drying oven is connected with a fresh air pipeline and an exhaust pipeline. And the fresh air pipelines of the N sections of continuous drying ovens at the tail end are correspondingly connected and communicated with the exhaust pipelines of the N sections of continuous drying ovens in the middle continuously connected with the N sections of continuous drying ovens one by one. According to the utility model, high-humidity air of the middle N sections of ovens with the maximum water vapor evaporation capacity in the oven system is introduced into the tail end N sections of ovens with relatively small evaporation capacity, and the air inlet humidity of the tail end N sections of ovens is controlled by utilizing the exhaust humidity generated by the middle N sections of ovens, so that the humidity of the tail end N sections of ovens of the ovens is improved; the flexibility of the surface of the pole piece can be improved, and the problems that the pole piece is seriously dry and cracks during tape running are solved, so that the product yield can be improved to a certain extent.

Description

Technical Field

[0001] The utility model relates to the technical field of air supply control for negative electrode coating of batteries, in particular to an oven air supply system for improving the cracking of negative electrode coating of lithium-ion batteries. Background Art

[0002] With the development of the battery industry, secondary batteries are more and more widely used in various fields. The requirements of application scenarios are becoming more and more strict, the cost pressure is increasing, and the product yield has become a key concern in the industry. When producing the aqueous negative electrode of the battery, if the air supply temperature and humidity of the oven are not well controlled, the electrode sheet will have cracking problems, seriously affecting the product yield. This problem needs to be solved through systematic analysis to improve the product yield.

[0003] Among them, the negative electrode water solvent system, the humidity of the oven and its stability are important factors affecting the cracking of the electrode sheet. Under normal circumstances, the fresh air system is greatly affected by the external environment. The humidity difference between day and night is large, and the air humidity changes greatly in dry weather in autumn and winter, strong winds, rain, etc., resulting in low humidity in the oven and cracking of the electrode sheet. Generally, the low inlet air humidity in the last few sections of the oven will cause the electrode sheet to crack. Therefore, improving the inlet air humidity of the last few sections of the oven is the key research issue at present. In the prior art, generally, the electrode sheet cracking is solved by increasing costs or changing the drying conditions.

[0004] For example, Chinese Patent CN2023112594847 discloses a method of adding a plasticizer. By changing the toughness of the electrode sheet surface with the plasticizer, while reducing the surface tension of the system, the volatilization rate of the solvent during high-temperature and high-speed coating is also slowed down, thereby effectively improving the coating quality and reducing the coating cracking problem. This solution uses the method of adding additional additives, increasing the manufacturing cost of the battery, polluting the air, and it is unknown whether it will affect the monomer performance after adding.

[0005] Another example is that Chinese Patent CN2022106914580 discloses a method of "drying + blowing dry" for drying after coating, controlling the drying degree of drying and blowing dry, and the solvent volatilizes stably during the drying process, reducing the coating defects of the negative electrode sheet. In this solution, additional drying is added after the electrode sheet leaves the oven, increasing energy consumption, and the moisture brought out by blowing dry is discharged into the workshop, causing instability in the workshop environment.

[0006] Chinese Patent CN202022624026.7 discloses that a blocking device is arranged on the air nozzle, and by moving the blocking device to change the air outlet position, the drying rate in the thinning area during the coating process can be slowed down, fundamentally solving the problem of thinning cracking caused by different coating thicknesses in the thinning area and the normal auxiliary material area and the same drying rate; without changing the original drying mode, by changing the drying state of the foil in the oven through multiple air zones, strengthening the adaptation window of the oven to the foil, it is easy to install, disassemble and clean, can be reused, and is economical and effective. However, in this solution, by changing the local air velocity and using baffles to block, in actual applications, problems such as the inconsistent position of the electrode sheet and the blocking position and the waste of working hours for shutting down and adjusting the baffle during die change may occur. Utility Model Content

[0007] The purpose of the present utility model is to overcome the deficiencies and defects of the prior art, and provide an oven air supply system for improving the cracking of the negative electrode coating of lithium-ion batteries. The exhaust air generated by the oven is used to supply other ovens, increasing the internal humidity of the subsequent several ovens. By improving the humidity of the fresh air, the stability of the fresh air and the humidity in the oven is ensured, and the toughness of the electrode sheet surface is improved, thereby solving the problem of electrode sheet cracking.

[0008] An oven air supply system for improving the cracking of the negative electrode coating of lithium-ion batteries includes an oven system. The oven system includes multiple ovens connected in sequence. Each oven is connected to a fresh air pipeline and an exhaust air pipeline. The fresh air pipelines of the last consecutive N ovens are respectively connected and communicated with the exhaust air pipelines of the middle consecutive N ovens that are continuously connected to them.

[0009] Among them, in the middle consecutive N ovens, from the entrance to the exit of the oven system, they are the first middle oven to the Nth middle oven in sequence; among the last consecutive N ovens, from the entrance to the exit of the oven system, they are the first end oven to the Nth end oven in sequence. The exhaust air pipelines of the first middle oven to the Nth middle oven are respectively connected to the fresh air pipelines of the first end oven to the Nth end oven in sequence.

[0010] Among them, the exhaust air pipelines of the last consecutive N ovens and the exhaust air pipelines of the front multiple ovens upstream of the middle consecutive N ovens are all connected to the main exhaust air pipeline.

[0011] Among them, the main exhaust air pipeline is connected to a heat exchanger for heat exchange with fresh air, and the heat exchanger is connected to the fresh air pipeline.

[0012] Among them, the fresh air pipeline includes a main fresh air pipeline for sending fresh air into the oven system, and the main fresh air pipeline is connected and communicated with the respective fresh air pipelines of each oven of the oven system.

[0013] Among them, the heat exchanger is connected to a fresh air inlet pipe for introducing external fresh air for heat exchange. The fresh air inlet pipe is connected to the fresh air discharge outlet of the dehumidifier, and the fresh air inlet of the dehumidifier is connected to a fresh air introduction pipe.

[0014] Among them, the wet air inlet of the dehumidifier is connected to the oven exhaust outlet of the heat exchanger through a pipeline.

[0015] Among them, a control valve is arranged on the pipeline. The control valve is used to control the amount of oven exhaust discharged from the heat exchanger entering the dehumidifier and the amount discharged outside the oven system.

[0016] Among them, the control valve is a three-way valve.

[0017] Among them, the control valve is connected to an exhaust pipe for discharging a part of the oven exhaust discharged from the heat exchanger outside the oven system.

[0018] The oven air supply system for improving the cracking of the negative electrode coating of lithium-ion batteries according to the present invention introduces the high-humidity air of the middle N sections of ovens with the largest water vapor evaporation amount in the oven system into the last N sections of ovens at the end of the oven system with relatively small evaporation amount. By using the exhaust humidity generated by the middle N sections of ovens, the incoming air humidity of the last N sections of ovens is controlled, and the humidity of the last N sections of ovens at the end of the oven is increased, which can improve the flexibility of the surface of the electrode sheet, solve the problems of serious drying of the electrode sheet and cracking during tape running, and thus can improve the product yield to a certain extent. Description of the Drawings

[0019] Figure 1 is a schematic diagram of the oven air supply system for improving the cracking of the negative electrode coating of lithium-ion batteries according to the present invention.

[0020] Figure 2 is a schematic connection diagram of the exhaust air pipeline of one middle oven and the fresh air pipeline of one end oven of the oven air supply system for improving the cracking of the negative electrode coating of lithium-ion batteries according to the present invention. Detailed Description of the Invention

[0021] The following further describes the present invention in detail with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] The oven air supply system for improving the cracking of the negative electrode coating of lithium-ion batteries according to the present invention changes the connection mode of multiple ovens in the oven system and their incoming air and exhaust air systems, so that the exhaust air in the high-humidity area of the middle oven is supplied to the incoming air of the low-humidity area at the end, thereby realizing the stability of the incoming air humidity of multiple ovens at the end of the oven system. By stabilizing the humidity of multiple ovens at the end, the technical problem of electrode sheet cracking is solved.

[0023] Please refer to Figures 1 to 2 as shown Figure 1 and Figure 2 which shows an oven air supply system with 14 sections of ovens, an oven air supply system for improving the cracking of the lithium-ion negative electrode coating, including an oven system 100. The oven system includes multiple sections of ovens connected in sequence. Each section of the oven is connected to a fresh air duct and an exhaust duct. The fresh air ducts of the last consecutive N sections of ovens are respectively connected and communicated with the exhaust ducts of the middle consecutive N sections of ovens that are continuously connected to them one by one.

[0024] Please see Figure 1 and 2 as shown. Among the middle consecutive N sections of ovens, from the inlet to the outlet of the oven system, they are the first middle oven to the Nth middle oven in sequence, such as Figure 1 and Figure 2 the 5th oven to the 9th oven in Figure 1 and Figure 2 ; among the last consecutive N sections of ovens, from the inlet to the outlet of the oven system, they are the first last oven to the Nth last oven in sequence, such as

[0025] Figure 1 and 2 which shows an oven system with 14 sections of ovens. Please see Figure 1 and 2 as shown. The high-humidity and high-temperature exhaust air discharged from the exhaust duct 40 of the 5th middle oven is introduced into the air inlet duct 11 of the 14th last oven, which is the last section of the end. After mixing with the fresh air of the 14th last oven, it enters the heating system of the 14th last oven to provide drying fresh air for the 14th last oven for drying the electrode sheet. Through the above design, it can be realized that most of the fresh air of the 14th last oven is the exhaust air of the 5th middle oven, and a small part is the outside fresh air, thus increasing the inlet air humidity of the 14th last oven and effectively solving the problem of electrode sheet cracking.

[0026] Based on the same design principle, connect the exhaust duct 39 of the 6th middle oven with the fresh air and duct 12 of the 13th last oven (as shown in Figure 2) Connect the exhaust duct 38 of the 7th oven in the middle to the fresh air and duct 13 of the 12th oven at the end, connect the exhaust duct 37 of the 8th oven in the middle to the fresh air and duct 14 of the 11th oven at the end, and connect the exhaust duct 36 of the 9th oven in the middle to the fresh air and duct 15 of the 10th oven at the end. Through such a design, most of the high-temperature and high-humidity air discharged from the constant drying area where the middle N ovens are located can be used in the drying area where the N ovens at the end are located, and a small part of the outside fresh air is used. This can not only ensure the drying effect and effectively solve the problem of the cracking of the electrode sheet, but also save 25% of the energy consumption as proved by experiments.

[0027] Specifically, it can be designed by matching the exhaust air temperature, exhaust air speed, and inlet air speed at different positions of the oven (as shown in the following table) to conform to the coating drying temperature curve under normal circumstances, introducing the wet air into the relatively dry oven area, and additionally through exhaust air heat exchange, dehumidification, and controlling the humidity of the overall furnace inlet air to balance the humidity in the oven, ensure the surface toughness of the electrode sheet after it exits the oven, and prevent over-drying or bending and cracking.

[0028] Parameter setting of the extrusion coater

[0029] Vehicle speed: 80 m / min; negative copper foil

[0030]

[0031] The oven involved in the table is the A coating oven, which refers to the oven for drying the negative electrode after single-sided coating of the slurry.

[0032] Among them, the external circulating air can be designed to recycle the exhaust air. The external exhaust air of the oven exchanges heat with the fresh air through a heat exchanger to increase the temperature of the fresh air.

[0033] In addition, the external exhaust air and fresh air of the oven are combined in a certain proportion and then pass through a dehumidifier to control the humidity of the fresh air entering the heat exchanger. The proportion of fresh air and exhaust air can be adjusted according to the different external humidities in the four seasons. On the premise of ensuring the inlet air humidity, the energy consumption loss can be reduced as much as possible.

[0034] Specifically, further preferably, in some embodiments, the exhaust ducts of the continuous N ovens at the end (such as the exhaust duct 31 of the 14th oven at the end, the exhaust duct 32 of the 13th oven at the end, the exhaust duct 33 of the 12th oven at the end, the exhaust duct 34 of the 11th oven at the end, the exhaust duct 35 of the 10th oven at the end) and the exhaust ducts of the multiple front ovens upstream of the continuous N ovens in the middle (such as the exhaust duct 44 of the 1st oven at the front, the exhaust duct 43 of the 2nd oven at the front, the exhaust duct 42 of the 3rd oven at the front, the exhaust duct 41 of the 4th oven at the front) are all connected to the main exhaust duct 102.

[0035] In some embodiments, the total exhaust air duct 102 is connected to a heat exchanger 50 for heat exchange with fresh air, and the heat exchanger is connected to a fresh air pipeline. Further preferably, in some embodiments, the fresh air pipeline includes a total fresh air duct 101 for sending fresh air into the oven system, and the total fresh air duct is connected and communicated with the respective fresh air ducts of each section of the oven in the oven system (such as Figure 1 the fresh air duct 11 of the 14th section of the oven, the fresh air duct 12 of the 13th section of the oven, the fresh air duct 13 of the 12th section of the oven, the fresh air duct 14 of the 11th section of the oven, the fresh air duct 15 of the 10th section of the oven, the fresh air duct 16 of the 9th section of the oven, the fresh air duct 17 of the 8th section of the oven, the fresh air duct 18 of the 7th section of the oven, the fresh air duct 19 of the 6th section of the oven, the fresh air duct 20 of the 5th section of the oven, the fresh air duct 21 of the 4th section of the oven, the fresh air duct 22 of the 3rd section of the oven, the fresh air duct 23 of the 2nd section of the oven, the fresh air duct 24 of the 1st section of the oven shown in

[0036] In some embodiments, the heat exchanger 50 is connected to a fresh air inlet duct 103 for introducing external fresh air for heat exchange. The fresh air inlet duct is connected to the fresh air discharge outlet of a dehumidifier 60. The fresh air inlet of the dehumidifier is connected to a fresh air introduction pipe 104, and the fresh air introduction pipe is connected to a fresh air fan 80.

[0037] In some embodiments, the wet air inlet of the dehumidifier 60 is connected to the oven exhaust outlet of the heat exchanger 50 through a pipeline 105. Further preferably, in some embodiments, a control valve 70 is arranged on the pipeline, and the control valve 70 is used to control the amount of oven exhaust discharged from the heat exchanger 50 entering the dehumidifier 70 and the amount discharged outside the oven system.

[0038] In some embodiments, the control valve 70 is a three-way valve. The three-way valve 70 is preferably designed as an electric valve or an automatic control valve, and can be remotely controlled to open or close as needed, or the valve opening can be adjusted as needed to control the amount of oven exhaust discharged or the amount entering the dehumidifier. Among them, the control valve is connected to an exhaust duct 106 for discharging a part of the oven exhaust discharged from the heat exchanger outside the oven system, and the exhaust duct can be connected to an exhaust fan 90.

[0039] From the above description, it can be seen that the oven air supply system for improving the cracking of the negative electrode coating of lithium-ion batteries in the embodiments of the present invention realizes using the wet air discharged from the upstream section of the oven as the fresh air in the downstream section of the oven by changing the air supply structure of the air duct, improving the internal humidity in the downstream section of the oven, and realizing the improvement of the cracking of the electrode sheet and its emission reduction by controlling the humidity of the incoming air, so as to solve the problem of the cracking of the electrode sheet.

[0040] The foregoing has shown and described the basic principles, main features and advantages of the present utility model. For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above-mentioned exemplary embodiments, and without departing from the spirit or basic features of the present utility model, the present utility model can be implemented in other specific forms;

[0041] Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes that fall within the meaning and scope of the equivalent elements of the claims in the present utility model.

[0042] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An oven air supply system for improving the cracking of the negative electrode coating of a lithium-ion battery, characterized in that, The invention comprises an oven system, wherein the oven system comprises a plurality of ovens connected in sequence, each oven section is connected to a fresh air duct and an exhaust duct, and the fresh air ducts of the N consecutive oven sections at the end are respectively connected and communicated with the exhaust ducts of the N consecutive oven sections in the middle.

2. The oven air supply system for improving the cracking of the negative electrode coating of a lithium-ion battery according to claim 1, wherein, In the described N-section continuous intermediate ovens, from the inlet to the outlet of the oven system, it is the first section intermediate oven to the N-section intermediate oven in sequence; in the described N-section continuous terminal ovens, from the inlet to the outlet of the oven system, it is the first section terminal oven to the N-section terminal oven in sequence, and the exhaust ducts from the first section intermediate oven to the N-section intermediate oven are connected one-to-one to the fresh air ducts from the first section terminal oven to the N-section terminal oven in sequence.

3. The oven air supply system for improving the cracking of the negative electrode coating of a lithium-ion battery according to claim 1, wherein, The exhaust ducts of the terminal continuous N-section ovens and the exhaust ducts of the front-end multi-section ovens upstream of the intermediate continuous N-section ovens are both connected to the main exhaust duct.

4. The oven air supply system for improving the cracking of the negative electrode coating of a lithium-ion battery according to claim 3, characterized in that, The total exhaust duct is connected to a heat exchanger for performing heat exchange with fresh air, and the heat exchanger is connected to the fresh air pipeline.

5. The oven air supply system for improving the cracking of the negative electrode coating of a lithium-ion battery according to claim 4, wherein, The fresh air pipeline includes a main fresh air duct for supplying fresh air to the oven system. The main fresh air duct is connected to and communicates with the respective fresh air ducts of each oven in the oven system.

6. The oven air supply system for improving coating cracking of lithium-ion battery negative electrodes according to claim 4, characterized in that: The heat exchanger is connected to a fresh air inlet pipe for introducing external fresh air for heat exchange, the fresh air inlet pipe is connected to a fresh air outlet of a dehumidifier, and the fresh air inlet of the dehumidifier is connected to a fresh air inlet pipe.

7. The oven air supply system for improving coating cracking of lithium ion battery negative electrodes according to claim 6, characterized in that: The wet air inlet of the dehumidifier is connected to the oven exhaust outlet of the heat exchanger through a pipeline.

8. The oven air supply system for improving coating cracking of lithium-ion battery negative electrodes according to claim 7, characterized in that: A control valve is arranged on the pipeline, and the control valve is used to control the amount of oven exhaust air discharged from the heat exchanger entering the dehumidifier and the amount discharged outside the oven system.

9. The oven air supply system for improving the cracking of the negative electrode coating of a lithium-ion battery according to claim 8, characterized in that, The control valve is a three-way valve.

10. The oven air supply system for improving coating cracking of lithium-ion battery negative electrodes according to claim 8, characterized in that: The control valve is connected to an exhaust pipe for discharging part of the oven exhaust air discharged from the heat exchanger out of the oven system.

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