Drying device and drying method for electrode plate

Abstract

Provided in the present application is a drying device, comprising a box body, a plurality of first infrared drying assemblies and a plurality of second infrared drying assemblies. The first infrared drying assemblies and the second infrared drying assemblies are arranged in a first drying section of the box body and are respectively arranged on two opposite sides of the first drying section of a drying channel. The first infrared drying assemblies and the second infrared drying assemblies both emit infrared radiation to dry two surfaces of an electrode plate conveyed in the drying channel, thereby greatly increasing the drying efficiency.

Description

Drying device and electrode drying method

[0001] This application claims priority to Chinese Patent Application No. 202410675833.1, filed with the Chinese Patent Office on May 28, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, specifically to a drying device and a drying method for electrode sheets. Background Technology

[0003] Current drying equipment typically uses hot air to dry electrode sheets. However, hot air drying is inefficient and slow, failing to meet the demands for drying electrode sheets at higher speeds and with greater thickness. Therefore, some related technologies use infrared drying components positioned above the electrode sheets to provide penetrating heating. However, achieving uniform heating of the electrode sheets is still difficult, leading to issues such as edge curling, warping, insufficient drying, and even cracking or sticking to the rollers. Technical issues

[0004] The purpose of this application is to provide a drying device that can reduce the difference in thermal stress on both sides of the electrode sheet, thereby improving the phenomena of electrode sheet curling, warping, insufficient drying, or even cracking or sticking to the roller caused by excessive difference in thermal stress on both sides of the electrode sheet. Technical solutions

[0005] In a first aspect, this application provides a drying apparatus for drying electrode sheets. The drying apparatus includes:

[0006] The box has a drying channel that runs through it. Electrode sheets are conveyed in the drying channel. The drying channel has a first side and a second side that are arranged opposite to each other. The box includes a first drying section that is arranged along the electrode sheet conveying direction.

[0007] Multiple first infrared drying components are disposed on the inner wall of the first drying section and located on the first side of the drying channel;

[0008] Multiple second infrared drying components are disposed on the inner wall of the first drying section and located on the second side of the drying channel.

[0009] Secondly, this application provides a method for drying an electrode sheet, using the drying apparatus provided in this application to dry the electrode sheet. The method for drying the electrode sheet includes the following steps:

[0010] The electrode sheet to be dried is conveyed to the drying channel located in the first drying section;

[0011] The electrode sheet is dried on both sides by the first infrared drying component and the second infrared drying component. Beneficial effects

[0012] The drying apparatus provided in this application has the following advantages: A first infrared drying component and a second infrared drying component emitting infrared radiation are provided in the first drying section of the chamber to dry the electrode sheets conveyed in the drying channel, greatly improving drying efficiency. Since the first infrared drying component is located on the first side of the drying channel and the second infrared drying component is located on the second side, both sides of the electrode sheets located in the drying channel can be heated by infrared radiation. This reduces the difference in thermal stress between the two sides, improving conditions such as edge curling, warping, insufficient drying, or even cracking or sticking to rollers caused by excessive heat difference between the two sides of the electrode sheets. Attached Figure Description

[0013] Figure 1 is a schematic diagram of the structure of a drying apparatus provided in some embodiments of this application;

[0014] Figure 2 is a schematic diagram of the structure of the first infrared drying component in Figure 1;

[0015] Figure 3 is a schematic diagram of the structure of the second infrared drying component in Figure 1;

[0016] Figure 4 is a partial enlarged structural diagram of region A in Figure 1;

[0017] Figure 5 is a schematic diagram of the structure of a drying apparatus provided in some embodiments of this application;

[0018] Figure 6 is a flowchart of a method for drying electrode sheets provided in some embodiments of this application;

[0019] Figure 7 is a schematic diagram of the drying device used in Figure 6;

[0020] The following are the labeling elements in the figure:

[0021] 100. Drying device; 200. Electrode sheet;

[0022] 10. Chamber; 20. First infrared drying assembly; 30. Second infrared drying assembly; 40. Third infrared drying assembly; 50. Fourth infrared drying assembly; 60. Pre-rolling assembly; 70. First control assembly; 80. Second control assembly;

[0023] 11. First drying section; 12. Second drying section; 13. Third drying section; 21. First substrate; 22. First heating layer; 31. Second substrate; 32. Second heating layer; 61. First roller; 62. Second roller;

[0024] I, Drying channel; I1, First side; I2, Second side; P1, First surface; P2, Second surface; F, Air nozzle; X, Electrode sheet conveying direction; Z, Height direction of the housing. Embodiments of the present invention

[0025] Please refer to Figures 1 and 5 together. The drying apparatus 100 provided in this application embodiment will now be described. The drying apparatus 100 provided in this application embodiment is used to dry electrode sheets 200. The drying apparatus 100 includes a housing 10, a plurality of first infrared drying components 20 and a plurality of second infrared drying components 30.

[0026] The chamber 10 includes a drying channel I that extends through it. Qualified positive or negative electrode slurry is coated onto a wide foil using a coating die to form a preliminary electrode sheet 200. The preliminary electrode sheet 200 is then conveyed into the chamber 10 for drying. The preliminary electrode sheet 200 is conveyed into and along the drying channel I within the chamber 10. The drying channel I has a first side I1 and a second side I2 that are opposite to each other. In this application, the first side I1 of the drying channel I is opposite to the first surface P1 of the electrode sheet 200, and the second side I2 of the drying channel I is opposite to the second surface P2 of the electrode sheet 200. That is, the first side I1 and the second side I2 of the drying channel I are two sides in the thickness direction of the electrode sheet 200.

[0027] The housing 10 includes a first drying section 11 arranged along the conveying direction X of the electrode sheet 200. A plurality of first infrared drying components 20 are disposed on the inner wall of the first drying section 11 and located on the first side I1 of the drying channel I, with the heating surface of the first infrared drying components 20 facing the first surface P1 of the electrode sheet 200. The first infrared drying components 20 are infrared radiation modules. The wavelength of the electromagnetic waves emitted by the first infrared drying components 20 is 0.76-1000 micrometers (μm), meaning that the first infrared drying components 20 emit infrared radiation to heat and dry the first surface P1 of the electrode sheet 200. In some possible embodiments, the wavelength of the electromagnetic waves emitted by the first infrared drying components 20 is 0.76μm, 0.8μm, 1μm, 10μm, 30μm, 50μm, 100μm, 150μm, 200μm, 300μm, 500μm, 800μm, or 1000μm, etc. Multiple second infrared drying components 30 are disposed on the inner wall of the first drying section 11 and located on the second side I2 of the drying channel I. The heating surface of the first infrared drying component 20 faces the second surface P2 of the electrode sheet 200. The second infrared drying component 30 is an infrared radiation module. The wavelength of the electromagnetic waves emitted by the second infrared drying component 30 is 0.76-1000μm, that is, the second infrared drying component 30 emits infrared radiation to heat and dry the second surface P2 of the electrode sheet 200. In some possible embodiments, the wavelength of the electromagnetic waves emitted by the second infrared drying component 30 is 0.76μm, 0.8μm, 1μm, 10μm, 30μm, 50μm, 100μm, 150μm, 200μm, 300μm, 500μm, 800μm, or 1000μm, etc. It should be noted that the wavelength of the electromagnetic waves emitted by the first infrared drying component 20 and the second infrared drying component 30 is within a range, rather than a single fixed value.

[0028] Compared with related technologies, the drying apparatus 100 provided in this application is equipped with a first infrared drying component 20 and a second infrared drying component 30 emitting infrared radiation in the first drying section 11 of the housing 10. This greatly improves the drying efficiency for drying the electrode sheet 200 transported in the drying channel I. Drying the electrode sheet 200 with single hot air relies on airflow as a medium for heat transfer, requiring contact between the airflow and the electrode sheet 200, as well as airflow circulation for heat transfer. This results in low heating and drying efficiency and a slow drying speed. This application uses infrared radiation to dry the electrode sheet 200. Compared to drying with single hot air, infrared radiation can achieve penetrating heating, and its dependence on airflow is low, greatly improving both heating and drying efficiency. In this application, since the first infrared drying component 20 is disposed on the first side I1 of the drying channel I and the second infrared drying component 30 is disposed on the second side I2 of the drying channel I, both sides of the electrode sheet 200 located in the drying channel I can be heated by infrared radiation, so the difference in thermal stress on the two sides is small, which improves the phenomenon of the electrode sheet 200 curling, warping, insufficient drying or even cracking or sticking to the roller caused by the large difference in heating on the two sides of the electrode sheet 200.

[0029] Please refer to Figures 1, 2, and 4 together. In this embodiment, the wavelength of the electromagnetic wave emitted by the first infrared drying component 20 is 2.5-25 μm, specifically 2.5 μm, 3 μm, 5 μm, 8 μm, 10 μm, 11.1 μm, 12 μm, 13.6 μm, 15.5 μm, 20 μm, 22 μm, 23.5 μm, or 25 μm. The wavelength of the electromagnetic wave emitted by the second infrared drying component 30 is 2.5-25 μm, specifically 2.5 μm, 3 μm, 5 μm, 8 μm, 10 μm, 11.1 μm, 12 μm, 13.6 μm, 15.5 μm, 20 μm, 22 μm, 23.5 μm, or 25 μm. This application, through infrared absorption spectrum studies of the electrode slurry, determines that the optimal absorption wavelength range of the electrode slurry for infrared radiation is 1.5-20 μm. Therefore, the wavelengths of the electromagnetic waves emitted by the first infrared drying component 20 and the second infrared drying component 30 are both set to 2.5-25 μm, so as to improve the absorption efficiency of the electrode sheet 200 for infrared radiation, thereby achieving better heating and drying effects.

[0030] In this embodiment, the drying channel I inside the housing 10 has an inlet and an outlet. The electrode sheet 200 enters the drying channel I through the inlet and is transported to the outside of the drying channel I through the outlet.

[0031] The housing 10 also includes a second drying section 12. The first drying section 11 and the second drying section 12 are arranged and connected along the conveying direction X of the electrode sheet 200. That is, the first drying section 11 and the second drying section 12 are connected in sequence, and the drying channel I extends from the first drying section 11 into the second drying section 12. The entrance of the drying channel I is located at one end of the first drying section 11, and the second drying section 12 is connected to the end of the first drying section 11 away from the entrance. The electrode sheet 200 enters the drying channel I in the first drying section 11 through the entrance, is then conveyed to the drying channel I in the second drying section 12, and is conveyed out of the drying channel I from the outlet.

[0032] The drying apparatus 100 also includes a plurality of third infrared drying components 40. The plurality of third infrared drying components 40 are disposed on the inner wall of the second drying section 12 and located on the first side I1 of the drying channel I, with the heating surface of the third infrared drying component 40 facing the first surface P1 of the electrode sheet 200. The third infrared drying component 40 is configured as an infrared radiation module. The wavelength of the electromagnetic waves emitted by the third infrared drying component 40 is 0.76-1000 μm, that is, the third infrared drying component 40 emits infrared radiation to heat and dry the electrode sheet 200. In some possible embodiments, the wavelength of the electromagnetic waves emitted by the third infrared drying component 40 is 0.76 μm, 0.8 μm, 1 μm, 10 μm, 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 300 μm, 500 μm, 800 μm, or 1000 μm, etc. In this embodiment, the wavelength of the electromagnetic wave emitted by the third infrared drying component 40 is 2.5-25μm, specifically 2.5μm, 3μm, 5μm, 8μm, 10μm, 11.1μm, 12μm, 13.6μm, 15.5μm, 20μm, 22μm, 23.5μm or 25μm, etc., in order to achieve better heating and drying effects.

[0033] In this embodiment, a third infrared drying component 40 is provided only on the first side I1 of the drying channel I in the second drying section 12 of the housing 10, and no infrared drying component is provided on the second side I2 of the drying channel I in the second drying section 12. It is understood that the preliminary electrode sheet 200 formed by coating with a coating die has a relatively high solvent content, requiring heating and drying to evaporate the solvent. The entrance to the drying channel I is located at one end of the first drying section 11. When the preliminary electrode sheet 200 enters the drying channel I in the first drying section 11, both the first surface P1 and the second surface P2 of the electrode sheet 200 are subjected to infrared radiation, resulting in faster solvent evaporation and more uniform heating on both surfaces, with less difference in thermal stress. As the electrode sheet 200 dries in the first drying section 11, most of the free solvent in the electrode sheet 200 has evaporated, and the solvent content in the electrode sheet 200 decreases. The electrode sheet 200 is transported from the first drying section 11 to the second drying section 12 with less heat required for solvent evaporation. Therefore, a third infrared drying component 40 is set on the first side I1 of the drying channel I in the second drying section 12 of the housing 10, and the second side I2 of the drying channel I in the second drying section 12 saves the setting of infrared drying components, which can save energy consumption and equipment costs, and reduce the probability of the electrode sheet 200 being over-baked, resulting in strip breakage and wrinkling.

[0034] As shown in Figure 2, the first infrared drying assembly 20 of this application includes a first substrate 21 and a first heating layer 22 disposed on the first substrate 21. The first heating layer 22 includes at least one of carbon black, micro / nano graphite powder, carbon nanofibers, carbon nanotubes, and graphene. The first substrate 21 is disposed on the inner wall of the first drying section 11, and the first heating layer 22 is located on the side of the first substrate 21 closer to the electrode sheet 200. The heating surface of the first infrared drying assembly 20 faces the first surface P1 of the electrode sheet 200.

[0035] The structures of the second infrared drying assembly 30 and the third infrared drying assembly 40 are similar to those of the first infrared drying assembly 20, as shown in Figure 3. The second infrared drying assembly 30 includes a second substrate 31 and a second heating layer 32 disposed on the second substrate 31. The second heating layer 32 includes at least one of carbon black, micro / nano graphite powder, carbon nanofibers, carbon nanotubes, and graphene. The second substrate 31 is disposed on the inner wall of the first drying section 11, and the second heating layer 32 is located on the side of the second substrate 31 closest to the electrode sheet 200. The heating surface of the second infrared drying assembly 30 faces the second surface P2 of the electrode sheet 200.

[0036] When the first heating layer 22, the second heating layer 32, and the third heating layer are energized, they generate infrared radiation to dry the electrode sheet 200. The first infrared drying component 20 emits infrared radiation with a wavelength of 2.5-25 μm through the first heating layer 22, which includes at least one of carbon black, micro / nano graphite powder, carbon nanofibers, carbon nanotubes, and graphene. The second infrared drying component 30 emits infrared radiation with a wavelength of 2.5-25 μm through the second heating layer 32, which includes at least one of carbon black, micro / nano graphite powder, carbon nanofibers, carbon nanotubes, and graphene. In this embodiment, both the first heating layer 22 and the second heating layer 32 include graphene. Both the first infrared drying component 20 and the second infrared drying component 30 are graphene infrared components. Similarly, the third infrared drying component 40 is also a graphene infrared component.

[0037] Infrared lamps, as infrared radiation components, suffer from uneven heating temperature fields and significant temperature gradients, leading to uneven drying of the electrode sheet 200, resulting in over-baking, strip breakage, wrinkling, and other issues that severely affect the quality of the electrode sheet 200. Furthermore, the high center temperature of the infrared lamp poses a risk of explosion. Including a cooling device in the drying apparatus 100 would increase costs and occupy space within the housing 10. However, the first infrared drying component 20, the second infrared drying component 30, and the third infrared drying component 40 of this application are graphene infrared components. Compared to infrared lamps, graphene infrared components have a more uniform temperature field, resulting in more uniform heating of the electrode sheet 200 and thus a higher quality dried electrode sheet 200. Because of the more uniform temperature field of graphene infrared components, the occurrence of excessively high center temperatures and insufficient periphery temperatures is reduced, thereby lowering the risk of explosion, improving drying efficiency, and eliminating the need for a separate cooling device, thus reducing costs and saving space.

[0038] In this embodiment, multiple first infrared drying components 20 are spaced apart along the conveying direction X of the electrode sheet 200, and the distance L1 between two adjacent first infrared drying components 20 is 50-800 mm, as shown in Figure 4. In some possible implementations, L1 can be 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 120 mm, 150 mm, 160 mm, 180 mm, 200 mm, 250 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, or 800 mm, etc. In the height direction Z of the housing, the distance d1 of the conveying path from the first infrared drying component 20 to the electrode sheet 200 is 20-150 mm. In some possible implementations, d1 can be 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 80 mm, 100 mm, 120 mm, 130 mm, or 150 mm, etc.

[0039] It should be noted that conveyor rollers (not shown) are respectively installed on the inlet and outlet sides of the drying channel I in the housing 10 to transport the electrode sheets 200 to be dried. The transport path of the electrode sheets 200 is the path formed by connecting the two conveyor rollers.

[0040] Understandably, since the first infrared drying component 20 has a high drying efficiency, the spacing of the first infrared drying component 20 is reasonably set between 50-800mm, which can save costs. It is not necessary to set too many first infrared drying components 20 to achieve efficient drying of the electrode sheet 200, and also avoid over-baking which would affect the quality of the electrode sheet 200.

[0041] Similarly, multiple third infrared drying components 40 are spaced apart along the conveying direction X of the electrode sheet 200, with a spacing of 50-800 mm between adjacent third infrared drying components 40. In some possible embodiments, the spacing between adjacent third infrared drying components 40 is 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 120 mm, 150 mm, 160 mm, 180 mm, 200 mm, 250 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, or 800 mm, etc. In the height direction Z of the housing, the distance from the third infrared drying component 40 to the conveying path of the electrode sheet 200 is 20-150 mm. In some possible implementations, the distance of the transport path from the third infrared drying component 40 to the electrode sheet 200 is 20mm, 30mm, 40mm, 50mm, 60mm, 80mm, 100mm, 120mm, 130mm or 150mm, etc.

[0042] In some possible implementations, a plurality of second infrared drying components 30 are arranged at intervals along the conveying direction X of the electrode sheet 200, and the distance L2 between two adjacent second infrared drying components 30 is greater than the distance L1 between two adjacent first infrared drying components 20. The distance L2 between two adjacent second infrared drying components 30 is 100-600 mm. In some possible implementations, L2 can be 100 mm, 120 mm, 150 mm, 160 mm, 180 mm, 200 mm, 250 mm, 300 mm, 400 mm, 500 mm, or 600 mm, as long as L2 is greater than L1.

[0043] In some possible implementations, the second infrared drying component 30 has a heating surface. In the height direction Z of the housing, the distance d2 between the heating surface of the second infrared drying component 30 and the electrode plate 200 is greater than the distance d1 between the heating surface of the first infrared drying component 20 and the electrode plate 200. The distance d2 between the heating surface of the second infrared drying component 30 and the electrode plate 200 is 30-500 mm. In some possible implementations, d2 can be 30 mm, 40 mm, 50 mm, 60 mm, 80 mm, 100 mm, 120 mm, 130 mm, 150 mm, 200 mm, 300 mm, 400 mm, or 500 mm, as long as d2 is greater than d1.

[0044] Understandably, the coating die applies electrode slurry to the first side P1 of the wide foil to form a preliminary electrode sheet 200. The first side P1 of the preliminary electrode sheet 200 contains a slurry layer with solvent and requires heating and drying. The second side P2 of the preliminary electrode sheet 200 requires less heating. The first infrared drying assembly 20 faces the first side P1 of the electrode sheet 200. When the preliminary electrode sheet 200 is conveyed into the drying channel I, the first infrared drying assembly 20 plays the primary drying role, while the second infrared drying assembly 30 plays an auxiliary drying role. This application sets the spacing L2 between two adjacent second infrared drying components 30 to be greater than the spacing L1 between two adjacent first infrared drying components 20 and / or the distance d2 of the conveying path from the second infrared drying component 30 to the electrode sheet 200 to be greater than the distance d1 of the conveying path from the first infrared drying component 20 to the electrode sheet 200. This reduces the baking temperature of the second infrared drying component 30 on the second surface P2 of the electrode sheet 200, avoiding over-baking that could cause the electrode sheet 200 to break or wrinkle. At the same time, it can reduce the heat difference between the first surface P1 and the second surface P2 of the electrode sheet 200, reduce the difference in thermal stress on the two surfaces, and prevent the electrode sheet 200 from curling, warping, or cracking.

[0045] In this embodiment, L2 equals L1 and d2 is greater than d1. In other possible implementations, L2 is greater than L1 and d2 is greater than d1, or L2 is greater than L1 and d2 is equal to d1.

[0046] In some possible embodiments, the drying apparatus 100 further includes a plurality of hot steam drying components. The nozzles F of the hot steam drying components are disposed on the inner walls of the first drying section 11 and the second drying section 12, for filling the chamber 10 with hot steam. The hot steam drying components are disposed on the first side I1 and / or the second side I2 of the drying channel I.

[0047] In this embodiment, within the first drying section 11, the air nozzle F and the first infrared drying component 20 located on the first side I1 of the drying channel I are alternately arranged, and the air nozzle F and the second infrared drying component 30 located on the second side I2 of the drying channel I are alternately arranged, as shown in Figure 1.

[0048] It should be noted that the first drying section 11 includes n connected sub-boxes, where n can be an integer greater than or equal to 2, such as 2, 3, 4, 5, 6, 7, 8, 10, etc. Optionally, the total number of first infrared drying components 20 and second infrared drying components 30 installed in each sub-box is 4 to 10. Specifically, there are 2 first infrared drying components 20 and 2 second infrared drying components 30, 5 first infrared drying components 20 and 5 second infrared drying components 30, 3 first infrared drying components 20 and 3 second infrared drying components 30, or 4 first infrared drying components 20 and 4 second infrared drying components 30, etc. The first drying section 11 is equipped with 4 air nozzles F, 2 first infrared drying components 20, and 2 second infrared drying components 30. Two air nozzles F are provided on the first side I1 of the drying channel I, and the two air nozzles F and the two first infrared drying components 20 are alternately arranged. Two air nozzles F are provided on the second side I2 of the drying channel I, and the two air nozzles F are alternately arranged with two second infrared drying components 30.

[0049] The second drying section 12 includes m connected sub-boxes, where m can be 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 20, etc. Specifically, the second drying section 12 is equipped with 4 air nozzles F and 2 third infrared drying components 40. Two air nozzles F are provided on the first side I1 of the drying channel I, and the two air nozzles F and the two third infrared drying components 40 are alternately arranged. Only two air nozzles F are provided on the second side I2 of the drying channel I.

[0050] In other possible implementations, two first infrared drying components 20, one air nozzle F, and two first infrared drying components 20 are arranged in sequence, or two air nozzles F, one first infrared drying component 20, and two air nozzles F are arranged in sequence. This application is not limited to this.

[0051] In this embodiment, m satisfies the relationship that m is between n and 2n. Within the first drying section 11, i.e., within the 1-n sub-boxes, the solvent content in the electrode sheet 200 is relatively high, requiring infrared drying components to be installed on both the first side I1 and the second side I2 of the drying channel I. Within the second drying section 12, i.e., within the (n+1)-(n+m) sub-boxes, the solvent content in the electrode sheet 200 is relatively low.

[0052] The return air vent (not shown) of the hot steam drying assembly is located on the inner wall of the housing 10. In some possible embodiments, the number of return air vents is one, two, or more. In some possible embodiments, the return air vents are located in the first drying section 11 and / or the second drying section 12. This is as long as the return air vent of the hot steam drying assembly can form a hot steam circulation with the nozzle F.

[0053] The hot steam drying assembly can dry the electrode sheet 200 with hot steam, and the airflow circulation of hot steam can carry away the solvent that evaporates from the electrode sheet 200.

[0054] In some possible embodiments, the first infrared drying component 20, the second infrared drying component 30, and the third infrared drying component 40 are all equipped with a standard first temperature setting and a second temperature setting. The first temperature setting is 180℃-280℃, and in some possible embodiments, the first temperature setting is 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 250℃, or 280℃, etc. The second temperature setting is 100℃-200℃, and in some possible embodiments, the second temperature setting is 100℃, 120℃, 140℃, 160℃, 180℃, or 200℃, etc. The rated power corresponding to the first temperature setting is 70%-100%, and the rated power corresponding to the second temperature setting is 50%-80%.

[0055] From the entrance to the exit of the drying channel I, the first drying section 11 and the second drying section 12 inside the box 10 have 1, 2, 3...n, n+1...(n+m) sub-boxes.

[0056] The third infrared drying assembly 40 in the sub-chambers (n+m) / 4 to (n+m) / 2 sections near the outlet of drying channel I uses the standard second-level temperature, while the remaining first infrared drying assemblies 20 and third infrared drying assemblies 40 use the standard first-level temperature. Alternatively, the first infrared drying assemblies 20 and third infrared drying assemblies 40 in the middle section use the standard second-level temperature, while the remaining first infrared drying assemblies 20 and third infrared drying assemblies 40 use the standard first-level temperature. The number of sub-chamber sections using the standard second-level temperature is (n+m) / 4 to (n+m) / 2 sections.

[0057] The second infrared drying components 30 within the first drying section 11 all adopt the standard first-level temperature, that is, the second infrared drying components 30 in sub-boxes 1 to n all adopt the standard first-level temperature. Alternatively, along the conveying direction X of the electrode sheet 200, the second infrared drying components 30 in sub-boxes 1 to n / 2 adopt the standard first-level temperature, and the second infrared drying components 30 in sub-boxes n / 2 to n adopt the standard second-level temperature.

[0058] In some possible embodiments, the drying apparatus 100 further includes a bidirectional unwinding mechanism and a bidirectional winding mechanism (not shown). The bidirectional unwinding mechanism includes an unwinding guide shaft and an unwinding reel. The bidirectional winding mechanism includes a winding guide shaft and a winding reel. The bidirectional unwinding mechanism is used to unwind the electrode sheet 200, and the bidirectional winding mechanism is used to wind the electrode sheet 200. The bidirectional unwinding mechanism is located upstream of the housing 10, and the bidirectional winding mechanism is located downstream of the housing 10. The electrode sheet 200 is conveyed into the housing 10 via the bidirectional unwinding mechanism, and after drying, it is conveyed outside the drying channel I and wound up by the bidirectional winding mechanism.

[0059] Please refer to Figure 5, which is a schematic diagram of the structure of a drying device 100 provided in another embodiment of this application. The structure of this embodiment is largely the same as that of the embodiment in Figure 1. The difference between this embodiment and the embodiment in Figure 1 is that the specific structure of the housing 10 and the drying device 100 also include a pre-rolling assembly 60.

[0060] In this embodiment, the housing 10 further includes a third drying section 13. The first drying section 11, the second drying section 12, and the third drying section 13 are arranged and connected along the conveying direction X of the electrode sheet 200. That is, the first drying section 11, the second drying section 12, and the third drying section 13 are connected sequentially, and the drying channel I extends from within the first drying section 11 and the second drying section 12 to the third drying section 13. The inlet of the drying channel I is located at one end of the first drying section 11, the second drying section 12 is connected to the end of the first drying section 11 away from the inlet, the third drying section 13 is connected to the end of the second drying section 12 away from the first drying section 11, and the outlet of the drying channel I is located at the end of the third drying section 13 away from the second drying section 12. The electrode sheet 200 enters the drying channel I within the first drying section 11 through the inlet, is sequentially conveyed to the drying channels I within the second drying section 12 and the third drying section 13, and is then conveyed out of the drying channel I from the outlet.

[0061] The drying apparatus 100 also includes a fourth infrared drying component 50 and a pre-rolling component 60. Multiple fourth infrared drying components 50 and pre-rolling components 60 are disposed on the inner wall of the third drying section 13. The pre-rolling component 60 is located near the outlet of the third drying section 13, and the fourth infrared drying components 50 are located on the side of the pre-rolling component 60 away from the outlet, that is, the fourth infrared drying components 50 are located in the portion of the third drying section 13 near the second drying section 12, as shown in Figure 5.

[0062] The fourth drying section is located on the first side I1 of the drying channel I within the third drying section 13. The fourth infrared drying component 50 is an infrared radiation module. The wavelength of the electromagnetic waves emitted by the fourth infrared drying component 50 is 0.76-1000μm. In some possible embodiments, the wavelength of the electromagnetic waves emitted by the fourth infrared drying component 50 is 0.76μm, 0.8μm, 1μm, 10μm, 30μm, 50μm, 100μm, 150μm, 200μm, 300μm, 500μm, 800μm, or 1000μm, etc. In this embodiment, the wavelength of the electromagnetic wave emitted by the fourth infrared drying component 50 is 2.5-25μm, specifically 2.5μm, 3μm, 5μm, 8μm, 10μm, 11.1μm, 12μm, 13.6μm, 15.5μm, 20μm, 22μm, 23.5μm or 25μm, etc., in order to achieve better heating and drying effects.

[0063] The pre-rolling assembly 60 includes a first roller 61 and a second roller 62 arranged opposite to each other. The first roller 61 is located on the first side I1 of the drying channel I, and the second roller 62 is located on the second side I2 of the third drying channel I. There is a gap between the first roller 61 and the second roller 62. The electrode sheet 200, after being dried in the first drying section 11 and the second drying section 12, is conveyed to the drying channel I in the third drying section 13. The electrode sheet 200 passes through the gap between the first roller 61 and the second roller 62 and is rolled by the first roller 61 and the second roller 62. After being dried by the first infrared drying assembly 20, the second infrared drying assembly 30, the third infrared drying assembly 40 and the fourth infrared drying assembly 50, the electrode sheet 200 is still at a high temperature. At this time, it is pre-rolled by the pre-rolling assembly 60, which is located in the housing 10 and between the fourth infrared drying assembly 50 and the outlet. The electrode sheet 200 is compacted, and the processing performance is improved. Pre-rolling the electrode sheet 200 reduces the probability of rebound during subsequent rolling processes, thereby reducing the pressure on the rollers. Furthermore, pre-rolling the electrode sheet 200 reduces the frequency of coating tape breakage, broadens the standards for edge control of the coated electrode sheet 200, and lowers the defect rate of the electrode sheet 200.

[0064] In this embodiment, the electromagnetic power emitted by the second infrared drying component 30 is lower than the electromagnetic power emitted by the first infrared drying component 20.

[0065] Specifically, the first infrared drying component 20 heats the ambient temperature above the electrode sheet 200 to a first temperature T1. The second infrared drying component 30 heats the ambient temperature below the electrode sheet 200 to a second temperature T2. Because the electromagnetic power emitted by the second infrared drying component 30 is lower than that emitted by the first infrared drying component 20, the second temperature T2 is lower than the first temperature T1. In some possible embodiments, the second power is 5% to 60% lower than the first power. The second power is 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60% lower than the first power. In some possible embodiments, the second temperature T2 is 5% to 60% lower than the first temperature T1. The second temperature T2 is 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60% lower than the first temperature T1.

[0066] Since the second surface P2 of the electrode sheet 200 in its initial form requires less heating, a second infrared drying component 30 with lower power is set to heat the ambient temperature under the electrode sheet 200 to a lower second temperature T2. This can avoid over-baking, which can cause phenomena such as breakage and wrinkling of the electrode sheet 200. At the same time, it can reduce the heat difference between the first surface P1 and the second surface P2 of the electrode sheet 200, reduce the difference in thermal stress between the two surfaces, and prevent the electrode sheet 200 from curling, warping, or cracking.

[0067] It should be noted that both the first infrared drying component 20 and the second infrared drying component 30 employ the first temperature setting. In this embodiment, the first temperature T1 of the first infrared drying component 20 is the standard first temperature setting, and the second temperature T2 of the second infrared drying component 30 is 5% to 60% lower than the standard first temperature setting. In some possible implementations, the first infrared drying component 20 employs the first temperature setting, and the second infrared drying component 30 employs the second temperature setting. The first temperature T1 of the first infrared drying component 20 is the standard first temperature setting, and the second temperature T2 of the second infrared drying component 30 is 5% to 60% lower than the standard second temperature setting.

[0068] In some possible implementations, because the rated power of the first infrared drying component 20 and the second infrared drying component 30 is different, the electrical power of the electromagnetic waves emitted by the second infrared drying component 30 is lower than that emitted by the first infrared drying component 20. Alternatively, in other possible implementations, the drying device 100 distributes / controls the electrical power of the electromagnetic waves emitted by the first infrared drying component 20 and the second infrared drying component 30 to be the same or different by providing a power distributor or control component.

[0069] In this embodiment, the drying apparatus 100 further includes a first control component 70 and a second control component 80. The first control component 70 is electrically connected to the first infrared drying component 20. The first control component 70 controls the electrical power of the electromagnetic waves emitted by the first infrared drying component 20, causing the first infrared drying component 20 to heat the ambient temperature above the electrode sheet 200 to a first temperature T1. The second control component 80 is electrically connected to the second infrared drying component 30. The second control component 80 controls the electrical power of the electromagnetic waves emitted by the second infrared drying component 30, causing the second infrared drying component 30 to heat the ambient temperature below the electrode sheet 200 to a second temperature T2. The second electrical power is lower than the first electrical power, causing the second temperature T2 to be lower than the first temperature T1.

[0070] Optionally, the drying device 100 also includes a third control component, a fourth control component, and multiple temperature sensors. The first control component 70, the second control component 80, the third control component, and the fourth control component are electrically connected to the first infrared drying component 20, the second infrared drying component 30, the third infrared drying component 40, and the fourth infrared drying component 50, respectively, thereby achieving independent control. The first control component 70, the second control component 80, the third control component, and the fourth control component are each an independent electrical control cabinet. Temperature sensors are installed at the drying components to receive temperature signals.

[0071] Please refer to Figures 6 and 7 together. This application embodiment also provides a method for drying an electrode sheet 200, using the drying apparatus 100 of this application embodiment to dry the electrode sheet 200. The drying method for the electrode sheet 200 includes the following steps:

[0072] Step S1: The electrode sheet 200 to be dried is conveyed to the drying channel I located in the first drying section 11;

[0073] Step S2: The two opposing sides of the electrode sheet 200 are dried by the first infrared drying component 20 and the second infrared drying component 30.

[0074] In this embodiment, the electrode sheet 200 is dried using the drying apparatus 100 shown in FIG. 7. The drying method of the electrode sheet 200 is described in detail below.

[0075] Step S1: The electrode sheet 200 to be dried is transported to the drying channel I located in the first drying section 11.

[0076] In some possible implementations, in step S1, the electrode sheet 200 to be dried is conveyed to the drying channel I of the first drying section 11 via a bidirectional unwinding mechanism.

[0077] Step S2: The two opposing sides of the electrode sheet 200 are dried by the first infrared drying component 20 and the second infrared drying component 30.

[0078] In this application, the first side I1 and the second side I2 of the drying channel I are the two sides in the thickness direction of the electrode sheet 200. The first infrared drying component 20 emits infrared radiation to heat and dry the first surface P1 of the electrode sheet 200. The first infrared drying component emits electromagnetic waves with a wavelength of 0.76-1000 μm. In some possible embodiments, the wavelength of the electromagnetic waves emitted by the first infrared drying component 20 is 0.76 μm, 0.8 μm, 1 μm, 10 μm, 30 μm, 50 μm, 100 μm, 150 μm, 200 μm, 300 μm, 500 μm, 800 μm, or 1000 μm, etc. The second infrared drying component 30 emits electromagnetic waves with a wavelength of 0.76-1000 μm. The second infrared drying component 30 emits infrared radiation to heat and dry the second surface P2 of the electrode sheet 200. In some possible implementations, the wavelength of the electromagnetic waves emitted by the second infrared drying component 30 is 0.76μm, 0.8μm, 1μm, 10μm, 30μm, 50μm, 100μm, 150μm, 200μm, 300μm, 500μm, 800μm or 1000μm, etc.

[0079] The distance between the first infrared drying component 20 and the electrode plate 200 is 20-150 mm, and the distance between the second infrared drying component 30 and the electrode plate 200 is greater than the distance between the first infrared drying component 20 and the electrode plate 200.

[0080] Using the drying method of electrode sheet 200 provided in this embodiment, since the first infrared drying component 20 is disposed on the first side I1 of the drying channel I and the second infrared drying component 30 is disposed on the second side I2 of the drying channel I, both sides of the electrode sheet 200 located in the drying channel I can be heated by infrared radiation, so the difference in thermal stress on the two sides is small, which improves the phenomenon of electrode sheet 200 curling, warping, insufficient drying or even cracking or sticking to rollers caused by excessive heat difference on the two sides of the electrode sheet 200.

[0081] In some possible implementations, the following steps may be included before step S1:

[0082] Step R1: Electrode material forms electrode slurry;

[0083] Specifically, the electrode material can be either a positive electrode material or a negative electrode material. In some possible embodiments, the positive electrode material includes at least one of lithium iron phosphate, lithium manganese oxide, lithium manganese iron phosphate, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, and lithium-rich manganese-based materials. The negative electrode material includes at least one of graphite, silicon carbide, silicon oxide, lithium titanium salt, and lithium niobium salt.

[0084] In step R2, the electrode slurry is added to the coating device and coated onto a wide foil through the coating die to form an electrode sheet 200 in its preliminary form.

[0085] The preliminary electrode sheet 200 is to be dried. That is, after steps R1-R2, steps S1-S2 are performed.

[0086] In some possible implementations, the following steps may be included after step S2:

[0087] Step S3: The electrode sheet 200 is conveyed from the first drying section 11 to the drying channel I in the second drying section 12;

[0088] Step S4: The electrode sheet 200 is dried by the third infrared drying component 40;

[0089] Step S5: The electrode sheet 200 is conveyed from the second drying section 12 to the drying channel I in the third drying section 13;

[0090] Step S6: The electrode sheet 200 is dried by the fourth infrared drying component 50;

[0091] In step S7, the electrode sheet 200 continues to be conveyed to the outside of the drying channel I.

[0092] In some possible implementations, in step S7, the electrode sheet 200 is conveyed to the outside of the drying channel I and wound up by a bidirectional winding mechanism.

[0093] The above is a description of the embodiments of this application.

[0094] The drying apparatus provided in this application embodiment is equipped with a first infrared drying component and a second infrared drying component that emit infrared radiation in the first drying section of the chamber. This significantly improves the drying efficiency by drying the electrode sheets conveyed within the drying channel. Because the first infrared drying component is located on the first side of the drying channel and the second infrared drying component is located on the second side, both sides of the electrode sheets within the drying channel are heated by infrared radiation. This reduces the difference in thermal stress between the two sides, improving the problems of edge curling, warping, insufficient drying, or even cracking or sticking to rollers caused by excessive heat difference between the two sides of the electrode sheets. This application embodiment also provides a method for drying electrode sheets that effectively improves the problems of edge curling, warping, insufficient drying, or even cracking or sticking to rollers caused by excessive heat difference between the two sides of the electrode sheets.

Claims

1. A drying device (100) configured to dry electrode sheets (200), the drying device (100) comprising: a box (10) having a drying channel (I) extending through the box (10), the electrode sheets (200) being conveyed in the drying channel (I), the drying channel (I) having a first side (I1) and a second side (I2) oppositely arranged, the box (10) comprising a first drying section (11) arranged along a conveying direction (X) of the electrode sheets (200); a plurality of first infrared drying assemblies (20) arranged on an inner wall of the first drying section (11) and located at the first side (I1) of the drying channel (I); and a plurality of second infrared drying assemblies (30) arranged on the inner wall of the first drying section (11) and located at the second side (I2) of the drying channel (I). 2.The drying device (100) according to claim 1, wherein the box (10) further comprises a second drying section (12), the first drying section (11) and the second drying section (12) are arranged along the conveying direction (X) of the electrode sheets (200) and connected; and the drying device (100) further comprises a plurality of third infrared drying assemblies (40) arranged on an inner wall of the second drying section (12) and located at the first side (I1) of the drying channel (I). 3.The drying device (100) according to claim 2, wherein the box (10) further comprises a third drying section (13) connected to an end of the second drying section (12) away from the first drying section (11); and the drying device (100) further comprises a pre-rolling assembly (60) arranged on an inner wall of the third drying section (13), the pre-rolling assembly (60) comprising a first roller (61) and a second roller (62) oppositely arranged, the first roller (61) being located at the first side (I1) of the drying channel (I), the second roller (62) being located at the second side (I2) of the drying channel (I), and the first roller (61) and the second roller (62) having a gap therebetween. The wavelength of electromagnetic waves emitted by the first infrared drying assemblies (20), the wavelength of electromagnetic waves emitted by the second infrared drying assemblies (30), and the wavelength of electromagnetic waves emitted by the third infrared drying assemblies (40) are all 2.5-25 microns. The first infrared drying assemblies (20) are arranged at intervals along the conveying direction (X) of the electrode sheets (200), and the interval between two adjacent first infrared drying assemblies (20) is 50-800 millimeters. The distance from the first infrared drying assemblies (20) to the conveying path of the electrode sheets (200) is 20-150 millimeters. ​ ​ 4. The drying apparatus (100) according to claim 2, wherein ​ 5. The drying apparatus (100) according to claim 2, wherein ​ ​ 6. The drying apparatus (100) according to claim 5, wherein A plurality of the second infrared drying assemblies (30) are arranged at intervals along the conveying direction (X) of the electrode sheet (200), and the interval between two adjacent second infrared drying assemblies (30) is greater than the interval between two adjacent first infrared drying assemblies (20). And / or, the distance from the second infrared drying assembly (30) to the conveying path of the electrode sheet (200) is greater than the distance from the first infrared drying assembly (20) to the conveying path of the electrode sheet (200).

7. The drying apparatus (100) according to any one of claims 1 to 6, wherein The first infrared drying assembly (20) comprises a first substrate (21) and a first heating layer (22) arranged on the first substrate (21), and the first heating layer (22) comprises at least one of carbon black, micro-nano graphite powder, carbon nanofiber, carbon nanotube and graphene. The first substrate (21) is arranged on the inner wall of the first drying section (11), and the first heating layer (22) is located on the side of the first substrate (21) close to the electrode sheet (200). The second infrared drying assembly (30) comprises a second substrate (31) and a second heating layer (32) arranged on the second substrate (31), and the second heating layer (32) comprises at least one of carbon black, micro-nano graphite powder, carbon nanofiber, carbon nanotube and graphene. The second substrate (31) is arranged on the inner wall of the first drying section (11), and the second heating layer (32) is located on the side of the second substrate (31) close to the electrode sheet (200).

8. The drying apparatus (100) according to claim 1, wherein The electric power of the electromagnetic wave emitted by the second infrared drying assembly (30) is lower than the electric power of the electromagnetic wave emitted by the first infrared drying assembly (20).

9. The drying apparatus (100) according to claim 8, wherein The electric power of the electromagnetic wave emitted by the second infrared drying assembly (30) is 5% to 60% lower than the electric power of the electromagnetic wave emitted by the first infrared drying assembly (20).

10. A drying method of an electrode sheet, which uses the drying device (100) of any one of claims 1-9 to dry the electrode sheet (200), comprising the following steps: Conveying the electrode sheet (200) to be dried to the drying channel (I) in the first drying section (11); Drying the opposite two sides of the electrode sheet (200) by the first infrared drying assembly (20) and the second infrared drying assembly (30).

11. The method of drying an electrode sheet according to claim 10, wherein, In the step of drying the opposite two sides of the electrode sheet (200) by the first infrared drying assembly (20) and the second infrared drying assembly (30), the distance from the first infrared drying assembly (20) to the electrode sheet (200) is 20-150 mm, and the distance from the second infrared drying assembly (30) to the electrode sheet (200) is greater than the distance from the first infrared drying assembly (20) to the electrode sheet (200).

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