Combined pole piece drying oven

Abstract

The invention relates to the technical field of lithium battery pole piece production, in particular to a combined type pole piece drying oven which comprises a hot air device and a heating roller assembly, the heating roller assembly comprises a plurality of heating rollers, the heating rollers are used for evenly heating pole pieces, the pole pieces sequentially surround the two heating rollers to form an s-shaped belt conveying path, and the S-shaped belt conveying path is used for conveying the pole pieces. The hot air devices are arranged on the two sides of the tape conveying path. The pole piece is heated and dried through contact heat conduction of the heating roller and the pole piece, so that the contact position of the pole piece and the heating roller is uniformly heated, and the phenomenon that an active substance at the edge of the pole piece is curled is reduced; the pole piece is heated in the inflexion state, so that different parts of the pole piece interact with each other during deformation, uneven stress is dispersed, a certain part is prevented from being excessively stressed, overall deformation is reduced, and the pole piece is not prone to bending and wrinkling.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery electrode sheet production, and more specifically, to a combined electrode sheet drying oven. Background Art

[0002] During the production of lithium batteries, the electrode sheet or separator needs to be coated, and the coated substrate needs to be dried. The coated substrate is dried through a drying process to remove the solvent and ensure the performance of the battery. This drying process is generally completed using an oven.

[0003] In existing ovens, the drying method generally uses hot air to heat the electrode sheet. After the lithium battery coater foil or electrode sheet is coated, it enters the oven for drying operations. During the drying process, due to other reasons such as the lateral wind speed or the coating layer formula, the drying efficiency of the coating layer is inconsistent, or due to the excessive volatilization of additives in the slurry, curling occurs at the blank positions on both sides of the foil or electrode sheet in the oven, resulting in material waste.

[0004] Based on this, there is an urgent need to invent a combined electrode sheet drying oven. Summary of the Invention

[0005] The purpose of the present invention is to provide a combined electrode sheet drying oven to reduce curling caused by inconsistent drying efficiency of the electrode sheet and reduce the occurrence of bending and wrinkling of the electrode sheet foil, aiming at the deficiencies of the existing technology.

[0006] To solve the above technical problems, the present application adopts the following technical solutions:

[0007] Provide a combined electrode sheet drying oven, including a hot air device and a heating roll assembly. The heating roll assembly includes a plurality of heating rolls, and the heating rolls are used to uniformly heat the electrode sheet. The electrode sheet sequentially forms an S-shaped tape running path around the heating rolls, and the hot air device is arranged on both sides of the tape running path to convey hot air to the electrode sheet.

[0008] Further, the hot air device is arranged within the wrap angle range where the electrode sheet contacts the heating roll.

[0009] Further, the hot air device includes a static pressure chamber and a plurality of air nozzles. All the air nozzles are communicated with the static pressure chamber, and the air nozzles are uniformly distributed along the outer circumference of the heating roll.

[0010] Further, the shape of the static pressure chamber matches the shape of the heating roll.

[0011] Further, the air nozzle is a slit-type air nozzle with the length direction perpendicular to the tape running direction of the electrode sheet.

[0012] Further, the heating roller is a hot oil roller, and a uniformly distributed flow channel is arranged along the roller surface of the hot oil roller. The hot oil roller is communicated with a hot oil machine through the flow channel, and the hot oil machine can control the temperature of the hot oil to control the temperature of the roller surface of the hot oil roller.

[0013] Further, the hot oil rollers are symmetrically distributed up and down.

[0014] Further, a return air cavity is arranged in the oven, and the return air cavity is arranged on both sides of the hot air device.

[0015] Further, negative pressure cavities are arranged at both the inlet and outlet of the electrode sheet in the oven.

[0016] Further, the box body of the oven is filled with a heat insulation layer.

[0017] The beneficial effects of the present invention are as follows: By setting the heating roller, the electrode sheet is heated and dried by the heat conduction of the heating roller in contact with the electrode sheet. Since the temperature of the heating roller is more uniform, the positions where the electrode sheet contacts the heating roller are uniformly heated, keeping the drying efficiency of the coating layers at each position of the electrode sheet relatively small, reducing the occurrence of curling of the active material at the edge of the electrode sheet. And because the electrode sheet forms an S-shaped tape running path around the heating roller, when the electrode sheet passes through the heating roller, different parts of the electrode sheet will have different stretchabilities due to thermal expansion in a local area. Heating the electrode sheet in a reverse curvature state can make different parts of the electrode sheet interact with each other during deformation, dispersing the uneven stress, thus avoiding excessive stress on a certain part, reducing the overall deformation, making the electrode sheet not easily bend and wrinkle. Moreover, the heating roller can provide good support when heating the electrode sheet, reducing the deformation of the electrode sheet caused by stress when the temperature is high, improving the stability and product quality in the production process. The provided hot air device can timely blow away the solvent and moisture evaporated from the heated electrode sheet, and at the same time, the hot air device can also heat the electrode sheet to improve the drying efficiency, and can reduce the size of the oven. Description of the Drawings

[0018] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments and descriptions thereof are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0019] Figure 1 It is a schematic structural diagram of the present invention.

[0020] Wherein: 1 - hot air device; 11 - air nozzle; 12 - static pressure cavity; 2 - heating roller assembly; 21 - heating roller; 211 - hot oil roller; 3 - tape running path; 4 - return air cavity; 5 - negative pressure cavity. Detailed Embodiments

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used in the description of the present application in this specification are only for the purpose of describing specific embodiments, and are not intended to limit the present application.

[0022] In the description of the present invention, unless otherwise clearly defined and limited, the terms "installation", "connection", "connection", and "fixation" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0023] Although the present application is disclosed above in a preferred embodiment, it is not used to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of the present application. Therefore, the protection scope of the present application should be determined by the scope defined by the claims of the present application.

[0024] The applicant found that in the existing oven, due to the difficult control of the uniform flow of the hot air blown out from the air outlet, the drying rates of the transverse parts of the pole piece perpendicular to the tape running direction are inconsistent. After the pole piece coating layer dries, it will shrink. When the drying rates are inconsistent, the shrinkage speeds of the various parts of the coating layer are different, resulting in stress and ultimately causing the edge position of the pole piece to curl.

[0025] However, in the present application, by setting a heating roller and changing the drying method of the pole piece, the pole piece is evenly heated and the drying rates at various positions are relatively consistent. Moreover, since heating is performed at the heating roller, when the pole piece is heated and dried, the stress received by the pole piece can be dispersed on the roller surface of the heating roller, reducing the occurrence of wrinkling.

[0026] Such as Figure 1As shown in the figure, the present application provides a combined pole piece drying oven, which includes a hot air device 1 and a heating roller assembly 2. The heating roller assembly 2 includes a plurality of heating rollers 21. The heating rollers 21 are used to uniformly heat the pole piece. The roller surface of the heating roller 21 can be heated. When the pole piece enters the oven, it closely adheres to the roller surface of the heating roller 21, so that the temperature of the heating roller 21 is transferred to the pole piece, thereby increasing the temperature of the pole piece, evaporating the solvent in the pole piece to achieve drying. The pole piece sequentially forms an S-shaped tape running path 3 around the heating roller 21. That is, when the pole piece bypasses the second heating roller 21 after bypassing the first heating roller 21, it selects one side different from the first heating roller 21. This way makes the pole piece form an S shape, enabling different parts of the pole piece to interact with each other during deformation, dispersing uneven stress, thus avoiding excessive stress on a certain part, reducing overall deformation, making the pole piece not easily bend and wrinkle. And after forming the S-shaped tape running path 3, it is beneficial for the pole piece to closely adhere to the heating roller 21, which can reduce the heat conduction resistance and is conducive to the heat of the heating roller 21 being conducted to the pole piece. The hot air device 1 is arranged on both sides of the tape running path 3, used to convey hot air to the pole piece, blow away the evaporated solvent, and the hot air blown by the hot air device 1 can also dry the pole piece, improving the drying efficiency of the pole piece, being beneficial to reducing the volume of the oven. And because one side of the pole piece is dried by the heating roller 21 and the other side is dried by hot air, the drying rates of the active substances on both sides of the pole piece are kept relatively consistent, which can reduce the deformation of the pole piece.

[0027] Preferably, the hot air device 1 is arranged within the wrap angle range where the pole piece contacts the heating roller 21, that is, the hot air device 1 is arranged within the range where the pole piece directly contacts and wraps the heating roller 21. This is because when the heating on both sides of the pole piece is uneven, it may increase the internal stress of the pole piece, resulting in the deformation of the pole piece, and the steam formed after the pole piece is heated by the heating roller 21 needs to be discharged in time. Through this setting, the steam on the surface of the pole piece can be quickly discharged, improving the drying efficiency, and heating both sides of the pole piece simultaneously is beneficial to the temperature uniformity during the heating of the pole piece and improves the drying efficiency.

[0028] Preferably, the hot air device 1 includes a static pressure chamber 12 and a plurality of nozzles 11. All the nozzles 11 are communicated with the static pressure chamber 12, and the nozzles 11 are evenly distributed along the outer circumference of the heating roller 21. The pressure at each position in the static pressure chamber 12 remains the same. Connecting the plurality of nozzles 11 to the same static pressure chamber 12 can keep the wind speeds of the nozzles 11 uniform, making the drying rates at each position of the pole piece uniform.

[0029] Preferably, the shape of the static pressure chamber 12 matches the shape of the heating roller 21. Setting the shape of the static pressure chamber 12 to match the shape of the heating roller 21 can keep the distances from each nozzle 11 to the pole piece the same, making the wind speeds of the nozzles 11 the same.

[0030] Preferably, the air nozzle 11 is a slit-type air nozzle 11 with its length direction perpendicular to the running direction of the pole piece. Setting the air nozzle 11 as a slit-type air nozzle 11 is beneficial to maintaining the consistency of the wind speed of the air nozzle 11 in the transverse direction and the uniformity of the drying of the pole piece.

[0031] Preferably, the heating roller 21 is a hot oil roller 211. Uniformly distributed flow channels are arranged along the roller surface of the hot oil roller 211. The hot oil roller 211 is connected to a hot oil machine through the flow channels. The hot oil machine can control the temperature of the hot oil to control the temperature of the roller surface of the hot oil roller 211. Uniformly distributed flow channels are arranged on the surface of the hot oil roller 211, and the temperature and flow rate of the hot oil in the flow channels are controlled by the hot oil machine, so that the temperature of the roller surface of the hot oil roller 211 can be kept uniform, and the pole piece can be uniformly heated after passing through the hot oil roller 211.

[0032] Preferably, the hot oil rollers 211 are symmetrically distributed up and down. This distribution is beneficial to the layout of the hot air device 1 and the convenience of connecting with external devices.

[0033] Preferably, a return air chamber 4 is arranged in the oven, and the return air chamber 4 is arranged on both sides of the hot air device 1. The air blown out from the air nozzle 11 flows through the surface of the pole piece and then enters the return air chamber 4 for treatment, which is beneficial to maintaining the circulating flow of the gas in the oven. Arranging the return air chamber 4 on both sides of the hot air device 1 is beneficial.

[0034] Preferably, negative pressure chambers are arranged at both the pole piece inlet and outlet of the oven. The negative pressure chambers can extract gas to keep the inside of the oven under negative pressure, preventing the air in the oven from flowing into the room and causing heat to overflow and conduct into the room.

[0035] Preferably, the box body of the oven is filled with a heat insulation layer. The setting of the heat insulation layer can reduce the heat exchange between the box body of the oven and the outside world, reduce the outflow of heat, and play an energy-saving and environmental protection role. The material of the heat insulation layer can be selected as aluminum silicate, which has good heat insulation performance and good heat resistance at the same time.

[0036] Specific working principle: The pole piece enters the oven through the oven inlet and the negative pressure chamber, and the pole piece is wound around the heating roller 21 along the s-shaped running path 3. The temperature of the heating roller 21 rises, and the temperature and flow rate of the hot oil in the flow channels of the heating roller 21 are controlled by the hot oil machine to control the uniformity of the temperature of the surface of the heating roller 21. After the pole piece contacts the heating roller 21, the temperature rises to achieve drying. At the same time, the air nozzle 11 of the hot air device 1 blows hot air at a section within the wrap angle of the pole piece and the heating roller 21, so that the steam of the solvent evaporated by the pole piece is blown away from the surface of the pole piece. At the same time, the hot air dries the surface of the pole piece. After passing through the surface of the pole piece, the hot air enters the return air chamber 4, and after being processed, it re-enters the air nozzle 11 to blow hot air. After the pole piece is dried, it leaves the oven through the negative pressure chamber and the oven outlet.

[0037] The foregoing description has shown and described several preferred embodiments of the present invention. However, as previously mentioned, it should be understood that the present invention is not limited to the forms disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept herein through the above teachings or the skills or knowledge in the relevant field. Any alterations and changes made by those skilled in the art that do not depart from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A combined pole piece drying oven, characterized in that: The invention comprises a hot air device (1) and a heating roller assembly (2), wherein the heating roller assembly (2) comprises a plurality of heating rollers (21), wherein the heating rollers (21) are used to uniformly heat the pole pieces, and the pole pieces sequentially surround the heating rollers (21) to form an S-shaped belt path (3), and the hot air device (1) is arranged on both sides of the belt path (3) to transport hot air to the pole pieces.

2. The combined pole piece drying oven according to claim 1, characterized in that: The hot air device (1) is arranged within the wrap angle range of the contact between the pole piece and the heating roller (21).

3. The combined pole piece drying oven according to claim 2, characterized in that: The hot air device (1) comprises a static pressure chamber (12) and a plurality of air nozzles (11); all of the air nozzles (11) are connected to the static pressure chamber (12), and the air nozzles (11) are evenly distributed along the periphery of the heating roller (21).

4. The combined pole piece drying oven according to claim 3 is characterized in that: The shape of the static pressure chamber (12) matches the shape of the heating roller (21).

5. The combined pole piece drying oven according to claim 3 is characterized in that: The air nozzle (11) is a slit-type air nozzle (11) whose length direction is perpendicular to the pole piece running direction.

6. The combined pole piece drying oven according to claim 1, characterized in that: The heating roller (21) is a hot oil roller (211), and a uniformly distributed flow channel is arranged along the roller surface of the hot oil roller (211). The hot oil roller (211) is connected to a hot oil machine through the flow channel. The hot oil machine can control the hot oil temperature and thus control the roller surface temperature of the hot oil roller (211).

7. The combined pole piece drying oven according to claim 6, characterized in that: The hot oil rollers (211) are symmetrically distributed up and down.

8. The combined pole piece drying oven according to claim 2, characterized in that: A return air chamber (4) is provided in the oven, and the return air chamber (4) is provided on both sides of the hot air device (1).

9. The combined pole piece drying oven according to claim 1, characterized in that: Negative pressure chambers (5) are provided at the pole piece inlet and outlet of the oven.

10. The combined pole piece drying oven according to claim 1, characterized in that: The box body of the oven is filled with a heat-insulating layer.

Images