Heat drying process and device for electrode coating layer

Abstract

The metal substrate (2) having the slurry applied to its surface is placed in a first heating zone (11) of a drying chamber (1) and transported along its length, where self-heat is generated in the metal substrate (2). The metal substrate (2) that has passed through the first heating zone (11) is transported to a second heating zone (12) of the drying chamber (1), where self-heat is generated in the metal substrate (2) and the slurry applied to its surface. The metal substrate (2) that has passed through the second heating zone (12) is transported to a third heating zone (13) of the drying chamber (1) for sintering. The first heating zone (11) includes an AC magnetic field, and the second heating zone (12) includes an AC magnetic field and a microwave heating assembly (121). The apparatus includes a drying chamber (1) having an inlet (3) through which the metal substrate (2) enters and an outlet (4) through which the metal substrate (2) exits. The drying chamber (1) includes a first heating section (11), a second heating section (12) and a third heating section (13). A microwave heating assembly (121) and a second electromagnetic heating assembly (122) are attached to the second heating section (12). The microwave heating assembly (121) and the second electromagnetic heating assembly (122) are both installed on the upper and lower surfaces of the drying chamber (1), respectively. The microwave heating assembly (121) and the second electromagnetic heating assembly (122) are uniformly spaced apart in the second heating section (12). The process and apparatus can ensure the overall drying of the coating layer and the uniformity of the coating drying by dividing the heating sections of the drying chamber into smaller sections and uniformly heating them by combining multiple heating methods.

Description

[Technical field]

[0001] The present invention relates to a process for heating and drying an electrode coating layer and an apparatus for the process for heating and drying an electrode coating layer. [Background technology]

[0002] The market demand for power lithium battery equipment is increasing rapidly, which is of great significance in promoting the development of new energy vehicles in China. In the process of uniformly coating the slurry (a mixture of positive and negative active materials and a solvent) on the aluminum / copper foil current collector substrate, drying and forming, the coating quality has a significant impact on the battery capacity, safety and lifespan.

[0003] Chinese Patent Publication No. CN111905996A (publication date November 10, 2020) discloses a coating and drying method and a coating and drying apparatus, which includes a drying box, in which an inlet for a metal substrate enters and an outlet for the metal substrate to exit are provided, a transport path for the metal substrate is formed between the inlet and the outlet, an electromagnetic coil for forming a magnetic field is provided in the drying box, and a transport path passing through the magnetic field is formed.

[0004] However, in the above cited document, a microwave heating drying method is adopted in the front stage of the drying chamber, and a hot air drying method is adopted in the rear stage of the drying chamber. Such a compartmentalized heating method is rough and disadvantageous for the overall drying of the coating layer, which hinders the uniformity of drying of the coating layer.

[0005] Therefore, a new coating layer drying process and device are needed to solve the problem that the section heating method in the prior art is rough, which causes uneven coating on the metal substrate, making it easy to generate cracks, which is disadvantageous to the overall drying of the coating layer, and inhibits the uniformity of the coating drying. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] China Publication Bulletin CN111905996A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a coating and drying process and apparatus, which divides the heating section of the drying chamber into smaller sections and combines multiple heating methods to heat uniformly, thereby ensuring the drying of the entire coating layer and the uniformity of the coating and drying, thereby resolving the shortcomings of the prior art. [Means for solving the problem]

[0008] The process of baking and drying the coating layer includes the following steps: The metal substrate having the slurry applied thereon is conveyed along its length in a first heating zone of a drying chamber, the first heating zone being capable of inducing self-heating in the metal substrate.

[0009] Next, the metal substrate that has passed through the first heating zone is conveyed to a second heating zone of a drying chamber, where the second heating zone can cause self-heating in the metal substrate and the slurry applied to the surface of the metal substrate.

[0010] Then, the metal base material that has passed through the second heating zone is transported to the third heating zone of the drying chamber, where the drying is completed. The first heating zone includes an AC magnetic field and the second heating zone includes an AC magnetic field and a microwave heating assembly.

[0011] According to this method, the metal substrate coated with the slurry is introduced into the first heating section, where the metal substrate generates self-heat to heat and dry the slurry from the inside to the outside. Therefore, the efficiency of electromagnetic heating is high, the temperature rise rate is fast, and the specified heating target can be completed within a few seconds, saving the drying time. After the first heating section heats up the metal substrate by electromagnetic heating, evaporation pores are gradually formed at the interface between the coating layer and the metal substrate. This accelerates the evaporation and dissipation of water vapor or solvent gas, greatly improves the drying efficiency, saves energy, and improves the efficiency of lithium replenishment due to the generation of micropores. When the metal substrate enters the second heating section, the slurry coated on the metal substrate is heated together with the metal substrate. Therefore, cracking of the coated slurry caused by heating only the metal substrate and raising the temperature quickly is avoided, and the temperature is raised more slowly to dry the coated slurry, so that the coated slurry is dried uniformly.

[0012] The sum of the longitudinal distances of the first heating section and the second heating section is less than half the longitudinal distance of the third heating section, and the longitudinal distance of the first heating section is less than or equal to the longitudinal distance of the second heating section.

[0013] Furthermore, the third heating section includes a hot air circulation drying section. In this way, the temperature rise of the slurry on the metal substrate and its surface can be made more gradual, and the cracking of the slurry caused by the temperature rise curve being too steep can be prevented, while the problem of the drying chamber being too long due to the temperature rise being too slow can be prevented.

[0014] The transport speed of the metal base material in the drying chamber is a speed at which the metal base material can be transported 0.5 to 1.5 times the distance in the longitudinal direction of the drying chamber per unit of time (per hour).

[0015] The metal substrate is baked in the drying chamber for 1 to 2 minutes.

[0016] Meanwhile, an apparatus for heating and drying a coating layer using the above method includes a drying chamber having an inlet for a metal substrate and an outlet for the metal substrate, the drying chamber including a first heating section, a second heating section and a third heating section, a microwave heating assembly and a second electromagnetic heating assembly are attached to the second heating section, the microwave heating assembly and the second electromagnetic heating assembly are both installed on the upper and lower surfaces of the drying chamber, respectively, and the microwave heating assembly and the second electromagnetic heating assembly are uniformly spaced apart in the second heating section.

[0017] Further, the first heating section includes a first electromagnetic heating assembly installed on each of the upper and lower surfaces of the drying chamber, and the maximum consumption The power is the maximum of all secondary electromagnetic heating assemblies. consumption The total power is less than or equal to:

[0018] According to this structure, the metal substrate body is heated by using the first heating section, and the preheating and predrying processes are performed, so that problems of uneven heating and cracks caused by too fast temperature rise can be avoided.

[0019] Further, a hot air circulation drying assembly is installed in the third heating section. The hot air circulation drying assembly includes a nozzle and a circulation filtering system, the circulation filtering system is installed on the upper surface of the drying chamber and communicates with the nozzle through an air passage and an air pipe. Effect of the Invention

[0020] In the above structure in which the microwave heating assembly and the second electromagnetic heating assembly are uniformly spaced apart in the second heating section, the heating and drying of the metal substrate coated with the slurry can be fully guaranteed. The second electromagnetic heating assembly causes the metal substrate body to self-heat, and the microwave heating assembly heats the metal substrate body and the slurry coated on its surface together. This avoids the rapid rise in the temperature inside the metal substrate and the slow rise in temperature near the outside when only the metal substrate is heated, and the entire substrate is heated more uniformly, further preventing the coated slurry from cracking.

[0021] 1. In the present invention, the heating zone of the drying chamber is divided into smaller sections to ensure the entire coating (layer) is dried and the coating is dried uniformly. 2. In the present invention, the efficiency of electromagnetic heating is high, the heating time is fast, and the specified heating target can be completed within a few seconds, saving the drying time. 3. In the present invention, the metal substrate coated with the slurry is first preheated and predried, and then heated from the inside and outside at the same time, which fully guarantees the heating and drying of the metal substrate coated with the slurry. The second electromagnetic heating assembly allows the metal substrate body to self-heat, and the microwave heating assembly heats the metal substrate body and the slurry coated on its surface together, so that the whole is heated more uniformly, which further avoids cracking of the coated slurry. 4. In the present invention, in the first heating section, after the metal substrate is heated by electromagnetic heating, evaporation pores are gradually formed at the interface between the coating layer and the metal substrate, thereby accelerating the evaporation and dissipation of water vapor or solvent gas, greatly improving the drying efficiency, and saving energy. 5. The present invention improves the efficiency of lithium replenishment by generating micropores through electromagnetic heating. [Brief description of the drawings]

[0022] [Figure 1] FIG. 2 is a cross-sectional view of the heating and drying device of the present invention taken along the direction in which the metal substrate travels. [Diagram 2] FIG. 2 is a vertical cross-sectional view of the heating and drying device of the present invention shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The embodiments described below are only some of the embodiments of the present invention, and are not all of the embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative creation belong to the scope of protection of the present invention.

[0024] In the description of the present invention, the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", and "outer" is based on the orientation or positional relationship shown in the drawings, and is merely for convenience and simplification of the description of the present invention, and does not indicate or imply that the devices or elements shown have a specific orientation and must be configured and operated in a specific orientation, and should not be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are merely for explanation, and should not be understood as indicating or implying relative importance. In the description of the present invention, the terms "mounted", "connected", and "connected" should be understood broadly unless otherwise clearly specified and limited.

[0025] In addition, the technical features according to different embodiments of the present invention described below can be combined with each other as long as they are not inconsistent with each other.

[0026] Example 1 The process of baking and drying the coating layer includes the following steps:

[0027] The metal substrate 2 with the slurry applied on its surface is placed in the first heating section 11 of the drying chamber 1 and transported along its longitudinal direction. In the first heating section 11, the metal substrate 2 can generate its own heat.

[0028] Next, the metal substrate 2 that has passed through the first heating section 11 is transported to the second heating section 12 of the drying chamber 1. In the second heating section 12, self-heating can be caused in the metal substrate 2 and the slurry applied to the surface thereof.

[0029] Then, the metal substrate 2 that has passed through the second heating section 12 is transported to the third heating section 13 of the drying chamber 1, where the drying is completed.

[0030] The first heating section 11 is equipped with an AC magnetic field and the second heating section 12 includes an AC magnetic field and a microwave heating assembly 121 .

[0031] In this manner, the metal substrate 2 having the slurry applied thereon is placed in the first heating section 11, where self-heat is generated in the metal substrate 2, thereby heating and drying the slurry from the inside to the outside. When the metal substrate 2 enters the second heating section 12, the slurry applied to the metal substrate 2 is heated together with the metal substrate 2, so that cracking of the applied slurry caused by a rapid increase in temperature due to heating only the metal substrate 2 is avoided, and the temperature is increased more slowly to dry the applied slurry, thereby drying it uniformly.

[0032] The sum of the longitudinal distances of the first heating section 11 and the second heating section 12 is less than half the longitudinal distance of the third heating section 13, and the longitudinal distance of the first heating section 11 is less than the longitudinal distance of the second heating section 12.

[0033] The third heating section 13 includes a hot air circulating drying section, and the baking temperature in the hot air circulating drying section is 140°C.

[0034] In this way, the temperature rise of the metal substrate 2 and the slurry on its surface can be made more gradual, and the cracking of the slurry caused by the temperature rise curve being too steep can be prevented. At the same time, the problem of the drying chamber 1 being too long due to the temperature rise being too slow can be prevented.

[0035] The transport speed of the metal base material 2 in the drying chamber 1 is such that the metal base material 2 is transported over a longitudinal distance that is 0.5 to 1.5 times the longitudinal distance of the drying chamber 1 per unit time. The metal base material 2 is baked in the drying chamber 1 for 1 to 2 minutes.

[0036] Example 2 This embodiment uses the method in embodiment 1, as shown in FIG. 1 and FIG. An apparatus for heating and drying a coating layer using the above method includes a drying chamber 1 having an inlet 3 through which a metal substrate 2 enters and an outlet 4 through which the metal substrate 2 exits, the drying chamber 1 including a first heating section 11, a second heating section 12 and a third heating section 13, a microwave heating assembly 121 and a second electromagnetic heating assembly 122 attached to the second heating section 12, the microwave heating assembly 121 and the second electromagnetic heating assembly 122 both being disposed on the upper and lower surfaces of the drying chamber 1, and the microwave heating assembly 121 and the second electromagnetic heating assembly 122 being uniformly disposed at intervals in the second heating section 12.

[0037] The first heating section 11 is provided with first electromagnetic heating assemblies 111 located on the upper and lower surfaces of the drying chamber 1. consumption The power is the maximum of all the second electromagnetic heating assemblies 122. consumption The total power is less than or equal to:

[0038] With this structure, the metal substrate 2 body is heated by the first heating section 11, and preheating and predrying are performed, thereby avoiding problems of uneven heating and cracking caused by too fast temperature rise.

[0039] A hot air circulation drying assembly 131 is installed in the third heating section 13, and the hot air circulation drying assembly 131 includes a nozzle 1311 and a circulation filtration system 132. The circulation filtration system 132 is installed on the upper surface of the drying chamber 1 and communicates with the nozzle 1311 via an air passage and an air duct.

[0040] With this structure, the microwave heating module 121 and the second electromagnetic heating module 122 are uniformly arranged at intervals in the second heating section 12, which can fully guarantee the heating and drying of the metal substrate 2 on which the slurry is applied. The second electromagnetic heating module 122 causes the body of the metal substrate 2 to self-heat, and the microwave heating module 121 heats the body of the metal substrate 2 and the slurry applied to its surface together, which avoids the internal temperature rising rapidly and the temperature rise at positions closer to the outside being slower due to the heating of only the metal substrate 2, and instead heats the entire substrate more uniformly, further preventing the applied slurry from cracking.

[0041] The beneficial effects of the present invention are as follows: 1. In the present invention, the heating zone of the drying chamber 1 is divided into smaller sections to ensure the entire coating layer is dried and the coating is dried uniformly.

[0042] 2. The present invention avoids cracking of the applied slurry due to rapid increase in temperature by heating only the metal substrate 2.

[0043] 3. The present invention first preheats and pre-dries the metal substrate 2, and then heats it from both the inside and the outside at the same time, thereby fully ensuring the heating and drying of the metal substrate 2 coated with the slurry. The second electromagnetic heating assembly 122 makes the metal substrate 2 body self-heat, and the microwave heating assembly 121 heats the metal substrate 2 body and the slurry coated on its surface together, so that the entire metal substrate 2 is heated more uniformly, and cracks in the coated slurry are further avoided.

[0044] The above examples are merely illustrative and do not limit the embodiments. Those skilled in the art can make modifications or alterations to other different forms based on the above description. It is not necessary to cover all the embodiments here. Any obvious changes or variations derived in this way are still within the scope of protection of the present invention. [Explanation of symbols]

[0045] 1, drying chamber; 11, first heating section; 111, first electromagnetic heating assembly; 12, second heating section; 121, microwave heating assembly; 122, second electromagnetic heating assembly; 13, third heating section; 131, hot air circulation drying assembly; 1311, air nozzle; 132, circulation filtration system; 2, metal substrate; 3, inlet; 4, outlet

Claims

1. The metal substrate (2) having the slurry applied to its surface is introduced into a first heating section (11) of a drying chamber (1) and conveyed along its longitudinal direction; generating self-heat in the metal substrate (2) in the first heating section (11) using a first electromagnetic heating assembly (111); The metal substrate (2) that has passed through the first heating section (11) is transported to a second heating section (12) of the drying chamber (1); generating self-heat in the metal substrate (2) and the slurry applied to the surface of the metal substrate (2) using a microwave heating assembly (121) and a second electromagnetic heating assembly (122) in the second heating section (12); conveying the metal substrate (2) that has passed through the second heating section (12) to a third heating section (13) of the drying chamber (1) for baking using a hot air circulation drying assembly (131); The maximum power consumption of the first electromagnetic heating assembly (111) is equal to or less than the sum of the maximum power consumption of the second electromagnetic heating assembly (122); the sum of the longitudinal distances of the first heating section (11) and the second heating section (12) is equal to or less than half the longitudinal distance of the third heating section (13); The longitudinal distance of the first heating section (11) is equal to or less than the longitudinal distance of the second heating section (12); A process for heating and drying an electrode coating layer, comprising:

2. The conveying speed of the metal substrate (2) in the drying chamber (1) is a speed at which the metal substrate (2) can be conveyed a distance of 0.5 to 1.5 times the longitudinal distance of the drying chamber (1) per unit time. The process for heating and drying the electrode coating layer according to claim 1 .

3. The baking time of the metal substrate (2) in the drying chamber (1) is 1 min to 2 min. The process for heating and drying the electrode coating layer according to claim 2 .

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