Coated pole piece drying and tempering process based on constant-temperature contact and variable-temperature radiation heating

Abstract

The invention relates to the technical field of pole piece manufacturing, in particular to a coated pole piece drying and tempering process based on constant-temperature contact and variable-temperature radiation heating, which comprises the following steps: unwinding a pole piece, and coating one surface of the pole piece; the coated pole piece is wound on a heating roller, a plurality of heating assemblies used for emitting heat radiation are arranged on the side, making contact with the pole piece, of the heating roller in the perimeter direction of the heating roller, the heating assemblies are divided into a plurality of temperature changing sets in sequence, the temperature of the heating assemblies under each temperature changing set is adjusted and controlled, and the heating roller and the heating assemblies conduct the baking procedure synchronously. The device has the effects that the baking efficiency and the heating uniformity of the coating material are improved, the function of segmented heating is achieved, and the risk that drying is discontinuous or the pole piece shrinkage rate exceeds the standard is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of pole piece manufacturing, and in particular to a coating pole piece drying and tempering process based on constant temperature contact and variable temperature radiation heating. Background Art

[0002] In the lithium battery production process, contact drying methods such as roller drying are usually used to dry and remove water from the battery electrodes. The roller drying method heats the coating material from the inside out by contacting the electrodes, which has high heating efficiency.

[0003] In the actual production process, since the evaporation rate and surface tension of the solvent (such as water or NMP) in the coating slurry are different at different temperatures, the electrode needs to be heated in sections so that the coating slurry can slow down the rapid volatilization of the solvent in the low temperature stage (such as the initial stage) and reduce the risk of coating cracking due to excessive capillary pressure. In the medium and high temperature stage (such as the subsequent stage), the solvent is accelerated to be completely removed to ensure uniform curing of the electrode. In the existing technology, multiple continuous heating rollers are usually used to perform contact heating on the electrode. The segmented heating of the electrode is achieved by separately regulating the temperature of each heating roller. This method has the following defects: 1. Multi-roller segmented drying requires precise coordination of roller speed and temperature. If the production line speed fluctuates, it is easy to cause discontinuous drying or excessive shrinkage of the electrode, affecting the production quality of the electrode; 2. Multi-roller segmented drying can easily cause the electrode path to be too long, and the electrode is prone to plastic deformation under the action of continuous tension, affecting the production quality of the electrode; 3. Multi-roller segmented drying requires larger equipment space, which is contrary to the trend of compact production line design and difficult to meet the requirements of energy conservation and emission reduction. Summary of the Invention

[0004] In response to the above-mentioned deficiencies in the prior art, the present application provides a coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating.

[0005] The above-mentioned invention objectives of this application are achieved through the following technical solutions:

[0006] The coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating includes the following steps:

[0007] Unwinding the electrode and performing a coating process on one surface of the electrode;

[0008] The coated electrode is wound around a heating roller, and a number of heating components for emitting heat radiation are arranged along the circumference of the heating roller from the side where the heating roller contacts the electrode. The heating components are divided into a number of variable temperature groups in sequence to regulate the temperature of the heating components under each variable temperature group, and the baking process is carried out synchronously with the heating roller.

[0009] By adopting the above technical solution, compared with the traditional multi-roller segmented drying method, this solution uses a single heating roller combined with a variable temperature heating component, which can reduce the complexity of roller speed and temperature coordination, and the heating roller heats the coating material from the inside out by contacting the electrode, and several heating components perform non-contact heating from the outer layer to the inner layer of the coating material through heat radiation, and simultaneously heats the outer and inner layers of the coating material so that the drying progress of the inner and outer layers of the coating material is close to synchronization, thereby improving the baking efficiency and heating uniformity of the coating material. In addition, through the precise and sequential temperature control of several variable temperature groups, the function of segmented heating can be achieved, and the contact drying and conveying of a single heating roller can reduce the impact of multi-roller conveying fluctuations, maintain the continuity and stability of the baking process, thereby reducing the risk of discontinuous drying or excessive electrode shrinkage. At the same time, due to the use of a single heating roller for baking, the path of the electrode is greatly shortened, reducing the time the electrode is subjected to continuous tension, reducing the risk of plastic deformation, improving the production quality and consistency of the electrode, and significantly reducing the equipment footprint, reducing energy consumption and meeting the needs of energy conservation and emission reduction.

[0010] In a preferred example, the present application can be further configured as follows: a fixed mounting plate is provided on the side where the heating roller contacts the electrode, and the heating components are sequentially provided on the fixed mounting plate, and the shape of the fixed mounting plate is adapted to the shape of the heating roller so that the distance from each group of heating components to the roller surface of the heating roller is the same.

[0011] By adopting the above technical solution, the fixed mounting plate provides stable support for the heating assembly, reducing the risk of uneven heating or equipment damage due to vibration or displacement. In addition, through the shape design of the fixed mounting plate, the uniformity of the distance from each group of heating assemblies to the roller surface of the heating roller is achieved, thereby optimizing the temperature distribution and ensuring uniform heating of the electrode.

[0012] In a preferred example, the present application can be further configured as follows: the heating component includes a closed thermal conductive box, the closed thermal conductive box is filled with a thermal conductive liquid, a plurality of radiant tubes are installed in the closed thermal conductive box, the radiant tubes are located in the thermal conductive liquid and are used to heat the thermal conductive liquid, the radiant tubes are electrically connected to an external power supply through wires, the closed thermal conductive box is provided with lead holes for leading out the wires, and the lead holes are waterproofed.

[0013] By adopting the above technical solution, compared with traditional direct radiation heating, the heating component is heated in the heat-conducting liquid through the radiation tube. Due to the high thermal conductivity of the heat-conducting liquid, the heat can be quickly and evenly transferred to the entire closed heat-conducting box, so that the heat transfer efficiency of the entire closed heat-conducting box is the same, and the closed heat-conducting box can achieve uniform heating of the electrode by thermal radiation, with better heating uniformity. By adjusting the power and heating time of the radiation tube, the temperature of the heat-conducting liquid can be precisely controlled, thereby achieving precise control of the electrode baking temperature and improving the stability of segmented heating.

[0014] In a preferred example, the present application can be further configured as follows: the radiation light source in the radiation tube is at least one of infrared light, laser, ultraviolet light or microwave.

[0015] In a preferred example, the present application can be further configured as follows: the heating component includes a closed thermal conduction box, the closed thermal conduction box is filled with thermal conduction liquid, a liquid bath pipe is installed in the closed thermal conduction box, the liquid bath pipe is located in the thermal conduction liquid and is used to heat the thermal conduction liquid, both ends of the liquid bath pipe pass through the closed thermal conduction box to the outside, one end of the liquid bath pipe is a liquid inlet and the other end is a reflux port, and both the liquid inlet and the reflux port are connected to an external liquid bath supply device.

[0016] By adopting the above technical solution, the heated constant temperature liquid is transported to the liquid bath tube through the external liquid bath supply equipment, and heat is exchanged with the heat-conducting liquid in the closed thermal conductive box, thereby uniformly heating the entire closed thermal conductive box, so that the closed thermal conductive box can achieve uniform heating of the electrode by thermal radiation.

[0017] In a preferred example, the present application can be further configured as follows: the liquid bath tube is in the shape of a coil.

[0018] By adopting the above technical solution and using a coil-shaped liquid bath tube, the contact area between the liquid bath tube and the heat-conducting liquid can be increased, thereby improving the heat-conducting efficiency.

[0019] In a preferred example, the present application can be further configured as follows: the liquid bath tube adopts a harmonica tube structure.

[0020] By adopting the above technical solution, the liquid bath tube adopts the form of a harmonica tube, that is, it has multiple flow channels arranged side by side. These flow channels can be regarded as small pipes, which are used to circulate heat-conducting liquid inside. The design of the harmonica tube makes the flow of heat-conducting liquid more uniform, increases the heat exchange area, and improves the heat transfer efficiency.

[0021] In a preferred example, the present application can be further configured as follows: the heat-conducting liquid is water or heat-conducting oil.

[0022] In a preferred example, the present application can be further configured as follows: the pole pieces after baking and drying are tempered at a tempering temperature of 70-220 degrees Celsius.

[0023] By adopting the above technical solution, the tempering treatment rearranges the atomic structure inside the electrode through heating and insulation, effectively alleviating the internal stress caused by temperature gradient and uneven shrinkage during the drying process, reducing the risk of electrode deformation or cracking, and achieving stress release and uniform electrode structure.

[0024] In summary, this application includes at least one of the following beneficial technical effects:

[0025] 1. Compared with the traditional multi-roller segmented drying method, this solution uses a single heating roller combined with a variable temperature heating component, which can reduce the complexity of roller speed and temperature coordination. The heating roller heats the coating material from the inside out by contacting the electrode. Several heating components perform non-contact heating from the outer layer of the coating material to the inner layer through heat radiation, and heat the outer and inner layers of the coating material at the same time, so that the drying progress of the inner and outer layers of the coating material is close to synchronization, thereby improving the baking efficiency and heating uniformity of the coating material. In addition, through the precise and sequential temperature control of several variable temperature groups, the function of segmented heating can be achieved, and the contact drying and conveying of a single heating roller can reduce the impact of multi-roller conveying fluctuations, maintain the continuity and stability of the baking process, thereby reducing the risk of discontinuous drying or excessive electrode shrinkage. At the same time, due to the use of a single heating roller for baking, the path of the electrode is greatly shortened, reducing the time the electrode is subjected to continuous tension, reducing the risk of plastic deformation, improving the production quality and consistency of the electrode, and significantly reducing the equipment footprint, reducing energy consumption and meeting the needs of energy conservation and emission reduction.

[0026] 2. Compared with traditional direct radiation heating, this heating component heats the heat-conducting liquid through the radiation tube. Due to the high thermal conductivity of the heat-conducting liquid, the heat can be quickly and evenly transferred to the entire closed thermal box, so that the heat transfer efficiency of the entire closed thermal box is the same, and the closed thermal box can achieve uniform heating of the electrode by thermal radiation, with better heating uniformity. By adjusting the power and heating time of the radiation tube, the temperature of the heat-conducting liquid can be precisely controlled, thereby achieving precise control of the electrode baking temperature and improving the stability of segmented heating.

[0027] 3. The heated constant temperature liquid can also be transported to the liquid bath tube through an external liquid bath supply device to exchange heat with the heat-conducting liquid in the closed thermal box, thereby uniformly heating the entire closed thermal box, so that the closed thermal box can achieve uniform heating of the electrode by heat radiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of part of the equipment structure when applying the electrode coating and drying process based on contact heating and variable temperature control in this application;

[0029] Figure 2 It is a schematic diagram of the structure of the heating component in this application;

[0030] Figure 3 This is a schematic diagram of the structure of the heating assembly in this application after partially removing the closed heat conduction box;

[0031] Figure 4 This is a schematic structural diagram of a liquid bath tube in one embodiment of the present application;

[0032] Figure 5This is a schematic structural diagram of a liquid bath tube in another embodiment of the present application;

[0033] Figure 6 yes Figure 5 Schematic diagram of the cross-sectional structure of the liquid bath tube shown;

[0034] Reference numerals: 1, pole piece; 2, heating roller; 3, heating assembly; 31, closed heat conduction box; 32, radiation tube; 33, wire; 34, lead hole; 35, liquid bath tube; 4, fixed mounting plate. DETAILED DESCRIPTION

[0035] The following description of exemplary embodiments of the present application is made in conjunction with the accompanying drawings, including various details of the embodiments of the present application to facilitate understanding. These details should be considered as merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0036] It should be noted that the terms "first," "second," and the like in the present invention are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than that illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure.

[0037] In this document, the term "and / or" simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document, unless otherwise specified, generally indicates an "or" relationship between the related objects.

[0038] Please refer to the following Figure 1 To the attached Figure 6 The present invention describes the coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating.

[0039] Reference Figures 1 to 6 The electrode coating and drying process based on contact heating and variable temperature control includes the following steps:

[0040] The electrode 1 is unwound and a coating process is performed on one surface of the electrode 1. The coated electrode 1 is wound around a heating roller 2. A plurality of heating components 3 for emitting heat radiation are arranged along the circumference of the heating roller 2 from the side where the heating roller 2 contacts the electrode 1. The plurality of heating components 3 are divided into a plurality of variable temperature groups in sequence to regulate the temperature of the heating components 3 under each variable temperature group, and the baking process is performed synchronously with the heating roller 2.

[0041] During the working process, auxiliary heating is performed by dividing into multiple temperature-variable groups, and the heating temperature is increased in sequence. In the low-temperature stage, the rapid volatilization of the solvent is slowed down to reduce the risk of cracking of the coating. In the medium and high-temperature stage, the thorough removal of the solvent is accelerated to ensure uniform curing of the electrode 1 and complete the segmented heating of the electrode 1. Compared with the traditional multi-roller segmented drying method, this solution adopts a single heating roller 2 combined with a heating component 3 that can change the temperature, which can reduce the complexity of the roller speed and temperature coordination, and the heating roller 2 heats the coating material from the inside to the outside by contacting the electrode 1. Several heating components 3 perform non-contact heating from the outer layer of the coating material to the inner layer through heat radiation, and heat the outer and inner layers of the coating material at the same time to make the coating material The drying progress of the inner and outer layers is close to synchronization, thereby improving the baking efficiency and heating uniformity of the coating material, and through the precise temperature control in sequence of several variable temperature groups, the function of segmented heating can be realized, and the contact drying and conveying of the single heating roller 2 can reduce the influence of multi-roller conveying fluctuations, maintain the continuity and stability of the baking process, thereby reducing the risk of discontinuous drying or excessive shrinkage of the electrode 1. At the same time, due to the use of a single heating roller 2 for baking, the path of the electrode 1 is greatly shortened, reducing the time that the electrode 1 is subjected to continuous tension, reducing the risk of plastic deformation, improving the production quality and consistency of the electrode 1, and greatly reducing the equipment footprint, reducing energy consumption and meeting the needs of energy conservation and emission reduction.

[0042] Preferably, when setting the heating assembly 3, a fixed mounting plate 4 is set on the side where the heating roller 2 contacts the pole piece 1, and the heating assemblies 3 are sequentially set on the fixed mounting plate 4. The shape of the fixed mounting plate 4 is adapted to the shape of the heating roller 2 so that the distance from each group of heating assemblies 3 to the roller surface of the heating roller 2 is the same, wherein the fixed mounting plate 4 provides stable support for the heating assembly 3, reduces the risk of uneven heating or equipment damage due to vibration or displacement, and achieves uniformity of the distance from each group of heating assemblies 3 to the roller surface of the heating roller 2 through the shape design of the fixed mounting plate 4, thereby optimizing the temperature distribution and ensuring uniform heating of the pole piece 1.

[0043] In one embodiment, the heating assembly 3 includes a closed heat-conducting box 31, which contains a heat-conducting liquid. A plurality of radiation tubes 32 are installed in the closed heat-conducting box 31. The radiation tubes 32 are located in the heat-conducting liquid and are used to heat the heat-conducting liquid. The radiation tubes 32 are electrically connected to an external power supply through wires 33. The closed heat-conducting box 31 is provided with lead holes 34 for leading out the wires 33, and the lead holes 34 are waterproofed. Compared with traditional direct radiation heating, the heating assembly 3 is heated in the heat-conducting liquid through the radiation tubes 32. Due to the high thermal conductivity of the heat-conducting liquid, heat can be quickly and evenly transferred to the entire closed heat-conducting box 31, so that the heat transfer efficiency of the entire closed heat-conducting box 31 is the same, thereby enabling the closed heat-conducting box 31 to achieve uniform heating of the electrode 1 by thermal radiation, with better heating uniformity. By adjusting the power and heating time of the radiation tubes 32, the temperature of the heat-conducting liquid can be precisely controlled, thereby achieving precise control of the baking temperature of the electrode 1 and improving the stability of the segmented heating.

[0044] Specifically, the radiation light source in the radiation tube 32 is at least one of infrared light, laser, ultraviolet light or microwave.

[0045] In another embodiment, the heating component 3 includes a closed thermal conductive box 31, which is filled with thermal conductive liquid. A liquid bath pipe 35 is installed in the closed thermal conductive box 31, and the liquid bath pipe 35 is located in the thermal conductive liquid and is used to heat the thermal conductive liquid. Both ends of the liquid bath pipe 35 pass through the closed thermal conductive box 31 to the outside, one end of the liquid bath pipe 35 is a liquid inlet and the other end is a reflux port. The liquid inlet and the reflux port are both connected to an external liquid bath supply device (not shown in the figure). The heated constant temperature liquid is transported to the liquid bath pipe 35 through the external liquid bath supply device, and heat exchange is performed with the thermal conductive liquid in the closed thermal conductive box 31, thereby uniformly heating the entire closed thermal conductive box 31, so that the closed thermal conductive box 31 can achieve uniform heating of the electrode 1 by thermal radiation.

[0046] Furthermore, the shape of the liquid bath tube 35 is a coil. By adopting the coil-shaped liquid bath tube 35 , the contact area between the liquid bath tube 35 and the heat transfer liquid can be increased, thereby improving the heat transfer efficiency.

[0047] Furthermore, the liquid bath tube 35 adopts a harmonica tube structure. The liquid bath tube 35 adopts the form of a harmonica tube, that is, it has multiple flow channels arranged side by side. These flow channels can be regarded as small pipes, which are used to circulate heat-conducting liquid inside. The design of the harmonica tube makes the flow of the heat-conducting liquid more uniform, increases the heat exchange area, and improves the heat transfer efficiency.

[0048] It should be noted that in the above embodiment, the closed heat-conducting box 31 can be made of metals such as copper and aluminum, or metal alloys such as aluminum alloys and titanium alloys to ensure sufficient thermal conductivity, as well as the lightness and sturdiness of the closed heat-conducting box 31. The heat-conducting liquid in the closed heat-conducting box 31 is water or heat-conducting oil, and technicians can choose according to actual drying conditions.

[0049] Furthermore, after the baking process is completed, the baked and dried electrode 1 is tempered at a temperature of 70-220 degrees Celsius. The tempering treatment rearranges the internal atomic structure of the electrode 1 through heating and insulation, effectively alleviating the internal stress caused by temperature gradient and uneven shrinkage during the drying process, reducing the risk of deformation or cracking of the electrode 1, and achieving stress release and uniform structure of the electrode 1.

[0050] Experimental control group

[0051]

[0052] Table 1

[0053] Table 1 shows the data of two experimental groups with a coating width of 500 mm, a lithium iron phosphate system, a positive electrode slurry, and a slurry solid content of 65%; and a conventional multi-roller method and the present application scheme were used on a heated roller with a diameter of 2 m and a 750 mm extrusion coater. It can be concluded that the drying process of the present invention has higher drying efficiency and significantly reduced energy consumption compared to the traditional process.

[0054] The above specific embodiments do not constitute a limitation on the scope of protection of this application. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application shall be included within the scope of protection of this application.

Claims

1. The coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating is characterized by: The following steps are involved: Unwinding the electrode (1) and performing a coating process on a surface of the electrode (1); The coated electrode (1) is wound around a heating roller (2), and a plurality of heating components (3) for emitting heat radiation are arranged along the circumference direction of the heating roller (2) from the side where the heating roller (2) contacts the electrode (1). The plurality of heating components (3) are divided into a plurality of temperature-variable groups in sequence to regulate the temperature of the heating components under each temperature-variable group, and the baking process is performed synchronously with the heating roller (2).

2. The coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating according to claim 1, characterized in that: A fixed mounting plate (4) is provided on the side of the heating roller (2) contacting the electrode (1), and the heating components (3) are sequentially arranged on the fixed mounting plate (4). The shape of the fixed mounting plate (4) is adapted to the shape of the heating roller (2) so that the distance between each group of heating components (3) and the roller surface of the heating roller (2) is the same.

3. The coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating according to claim 1, characterized in that: The heating assembly (3) includes a closed heat-conducting box (31), wherein the closed heat-conducting box (31) is filled with a heat-conducting liquid, wherein a plurality of radiation tubes (32) are installed in the closed heat-conducting box (31), wherein the radiation tubes (32) are located in the heat-conducting liquid and are used to heat the heat-conducting liquid, wherein the radiation tubes (32) are electrically connected to an external power supply via a wire (33), and wherein the closed heat-conducting box (31) is provided with a lead hole (34) for leading out the wire (33), and the lead hole (34) is waterproofed.

4. The coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating as claimed in claim 3, characterized in that: The radiation light source in the radiation tube (32) is at least one of infrared light, laser, ultraviolet light or microwave.

5. The coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating according to claim 1, characterized in that: The heating assembly (3) comprises a closed heat-conducting box (31), wherein the closed heat-conducting box (31) is filled with heat-conducting liquid, and a liquid bath pipe (35) is installed in the closed heat-conducting box (31), wherein the liquid bath pipe (35) is located in the heat-conducting liquid and is used to heat the heat-conducting liquid, wherein both ends of the liquid bath pipe (35) pass through the closed heat-conducting box (31) to the outside, wherein one end of the liquid bath pipe (35) is a liquid inlet and the other end is a reflux port, wherein both the liquid inlet and the reflux port are connected to an external liquid bath supply device.

6. The coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating as claimed in claim 5, characterized in that: The shape of the liquid bath tube (35) is a coil.

7. The coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating as claimed in claim 5, characterized in that: The liquid bath tube (35) adopts the harmonica tube structure.

8. The coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating according to claim 3 or 5, characterized in that: The heat transfer liquid is water or heat transfer oil.

9. The coating electrode drying and tempering process based on constant temperature contact and variable temperature radiation heating as claimed in claim 1, characterized in that: The pole piece (1) after baking and drying is subjected to tempering treatment, and the tempering temperature is 70-220 degrees Celsius.

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