Diaphragm coating system

Abstract

The utility model discloses a diaphragm coating system which comprises an anilox roller and a point coating plate roller, the anilox roller is used for contacting slurry and transferring the slurry to the point coating plate roller, the point coating plate roller is used for coating a diaphragm, and the rotating speed of the anilox roller is the same as or different from that of the point coating plate roller. The anilox roller comprises a roller body and a flexible material layer, the outer surface of the roller body is cylindrical, the flexible material layer forms an annular shape, is attached to the circumferential face of the roller body and is fixedly connected with the roller body, a plurality of grooves distributed in an array mode are formed in the outer surface of the flexible material layer, and the adjacent grooves are arranged at intervals. Protrusions relative to the bottoms of the grooves are formed on the flexible material layer between the adjacent grooves, and the protrusions form grids on the outer surface of the flexible material layer. According to the diaphragm coating system disclosed by the utility model, the anilox roller and the point coating plate roller are in contact operation under different linear speeds, so that the point coating plate roller cannot be abraded, and the service life of the point coating plate roller is prolonged.

Description

Technical Field

[0001] This utility model belongs to the field of battery separator technology, and specifically relates to a separator coating system. Background Technology

[0002] With the rapid updates in electronic products and the rapid expansion of the market share of new energy electric vehicles, lithium batteries, as an important energy storage device with high energy density and long lifespan, are receiving increasing attention from manufacturers and users. One of the core components of a lithium battery is the separator, which effectively isolates the positive and negative electrodes, preventing short circuits and electrolyte immersion, thus ensuring the safety and performance stability of the lithium battery. Compared to PP or PE base films, coated films generally have better high-temperature stability, chemical stability, and higher mechanical strength and toughness. However, the coating process has a significant impact on the performance of the coated film; therefore, the lithium battery separator coating process is crucial to the performance and lifespan of lithium batteries.

[0003] With the continuous exploration of membrane coating methods, a new coating method—matrix coating—has gradually come into the public eye. Due to its controllable coating point arrangement, controllable coating coverage and thickness, it has been gradually applied to the manufacturing of new batteries.

[0004] However, as this is a new coating method, its application time in production practice is still too short, and its technological drawbacks are gradually being discovered. For example, the dot coating rollers used in this process are currently made of flexible materials due to the limitations of the coating method, while the anilox roller (which plays the role of transferring the slurry) that comes into contact with it is made of rigid materials. During the contact process, since the protrusions of the dot coating roller cannot be guaranteed to fall 100% into the grooves of the anilox roller, long-term operation will inevitably cause wear on the dot coating roller, resulting in poor coating effect. It is necessary to frequently replace the dot coating roller, which increases costs. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned technical solutions, the purpose of this utility model is to provide a diaphragm coating system.

[0006] The objective of this utility model is achieved through the following technical solution.

[0007] An anilox roller includes: a roller body and a flexible material layer. The outer surface of the roller body is cylindrical. The flexible material layer is formed in an annular shape and is attached to the circumferential surface of the roller body and fixedly connected to the roller body. The outer surface of the flexible material layer has a plurality of grooves arranged in an array. Adjacent grooves are spaced apart. Between adjacent grooves, the flexible material layer forms a protrusion relative to the bottom of the groove. The protrusion forms a grid on the outer surface of the flexible material layer.

[0008] In the above technical solution, the roller body is a cavity.

[0009] In the above technical solution, the outer diameter of the roller body is 81-106 mm, and the wall thickness of the roller body is 3-10 mm.

[0010] In the above technical solution, the thickness of the flexible material layer is 2 to 5 mm.

[0011] In the above technical solution, the flexible material layer is made of at least one of styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), ethylene-propylene-diolefin terpolymer (EPDM), polyethylene-octene copolymer (POE), thermoplastic elastomer (TPE), and poly(2,6-dimethyl-1,4-phenylene ether) (PPE).

[0012] In the above technical solution, the roller body is made of alloy steel.

[0013] In the above technical solution, the depth of each groove is 0.1 to 3 mm.

[0014] In the above technical solution, the grooves are arranged at equal intervals on the outer surface of the flexible material layer.

[0015] In the above technical solution, the shape of the cross section of each groove along the circumferential surface of the roller is one or more of quadrilaterals, triangles and hexagons.

[0016] In the above technical solution, the width of the protrusion is 100-200 μm.

[0017] A diaphragm coating system includes: an anilox roller and a dot coating roller, the anilox roller being used to contact and transfer slurry onto the dot coating roller, the dot coating roller being used to coat the diaphragm, the anilox roller and the dot coating roller rotating at the same or different speeds.

[0018] The use of anilox rollers in reducing diaphragm defects.

[0019] Compared with existing technologies, the beneficial effects are:

[0020] 1. The outer surface of the anilox roller is made of a flexible material layer, which allows the anilox roller and the dotting roller to contact and run at different linear speeds without causing wear on the dotting roller, thus extending the service life of the dotting roller and reducing the cost caused by frequent replacement of the dotting roller. At the same time, in the existing technology, during the wear process of the dotting roller, the debris generated by the wear of the dotting roller will mix into the slurry, resulting in increased impurities and contamination of the slurry. This risk can be minimized.

[0021] 2. In the existing technology, when using a metal anilox roller, in order to minimize the wear of the dot coating roller, the linear speeds of the metal anilox roller and the dot coating roller must be kept as consistent as possible. This results in a very small adjustable range for the amount of slurry transferred by the dot coating roller when the amount of liquid carried by the metal anilox roller is constant. However, in this invention, when the amount of liquid carried by the anilox roller is constant, the amount of slurry transferred by the dot coating roller can be adjusted by adjusting the ratio of the linear speeds of the dot coating roller and the anilox roller, thereby achieving the purpose of adjusting the coating effect, improving operability, and broadening the process conditions.

[0022] 3. The outer surface of the anilox roller is made of a flexible material layer, which keeps the shape of the bumps on the dot coating roller in good condition, resulting in good consistency of the coating dots on the diaphragm and thus greatly improving the performance of the diaphragm. Attached Figure Description

[0023] Figure 1 This is a cross-sectional view of the anilox roller in Example 1;

[0024] Figure 2 This is a partial schematic diagram of the outer surface of the anilox roller in Example 1;

[0025] Figure 3 The appearance of the diaphragm in Example 3;

[0026] Figure 4 The thickness test results are from Example 3;

[0027] Figure 5 The results are from the weight test in Example 3.

[0028] Among them, 1: flexible material layer, 2: roller body, 3: groove, 4: protrusion. Detailed Implementation

[0029] The anilox roller of this utility model will now be described in detail with reference to the accompanying drawings.

[0030] The base film used in the following implementation is a PE film with a thickness of 9μm, and the width of the base film is greater than the width of the dot-coating roller coating.

[0031] The preparation method of the conventional dotting slurry in the following examples is as follows: PVDF powder, purified water, and dispersant are mixed and stirred in a planetary mixer for 60 minutes until homogeneous (rotation speed 2000 r / min, revolution speed 40 r / min), then milled for 15 minutes. Thickener, binder, and wetting agent are then added and stirred in a planetary mixer for 25 minutes until homogeneous (rotation speed 1300 r / min, revolution speed 40 r / min) to obtain the conventional dotting slurry. The ratio of dispersant, wetting agent, PVDF powder, purified water, thickener, and binder by mass is 0.5:2.5:16:47:16:18. The binder is styrene-butyl methacrylate, the dispersant is ammonium polyacrylate, the thickener is hydroxymethyl cellulose, and the wetting agent is polyoxyethylene ether.

[0032] Example 1

[0033] like Figure 1 As shown, an anilox roller includes: a roller body 2 and a flexible material layer 1. The roller body 2 is a cavity, and its outer surface is cylindrical. The flexible material layer 1 is annular and attached to the circumferential surface of the roller body 2 and fixedly connected to it. The outer surface of the flexible material layer 1 is formed with a pattern as shown in the figure. Figure 2 The array shown has multiple grooves 3 (grooves 3 are laser-engraved), which are arranged at equal intervals on the outer surface of the flexible material layer 1. The outer diameter of the roller body 2 is 94mm, the wall thickness of the roller body 2 is 5mm, the thickness of the flexible material layer 1 is 3mm, the material of the flexible material layer 1 is TPE-U, and the material of the roller body 2 is alloy steel.

[0034] Each groove 3 has a depth of 2 mm. The cross-sectional shape of each groove 3 along the circumferential surface of the roller body 2 is rhomboid. Adjacent grooves 3 are spaced apart, and a flexible material layer 1 forms a protrusion 4 relative to the bottom of the groove 3 between adjacent grooves 3. The protrusion 4 forms a grid on the outer surface of the flexible material layer 1. The width of the protrusion 4 is 200 μm.

[0035] Example 2

[0036] A conventional anilox roller includes: a roller body, which is a cavity, with a cylindrical outer surface. The outer surface of the roller body has multiple grooves arranged in an array (the grooves are laser-engraved). In this embodiment, the arrangement of the grooves on the roller body is the same as the arrangement of grooves 3 on the flexible material layer 1 in Embodiment 1. In this embodiment, the outer diameter of the roller body is 94 mm, the wall thickness is 5 mm, and the material of the roller body is alloy steel. In this embodiment, the depth of each groove is 2 mm. The cross-sectional shape of all grooves along the circumferential surface of the roller body is rhomboid. The interval between the sides of every two adjacent grooves (equivalent to the width of the "protrusion 4" in Embodiment 1) is 200 μm.

[0037] Example 3

[0038] Using the anilox roller of Example 1 and the conventional anilox roller of Example 2 on the same coating machine, conventional dot coating slurry was applied to the base film to verify the wear of the dot coating roller:

[0039] Prepare two dot coating rollers, a and b, of identical material, model, and specifications, and two 30kg containers of standard dot coating slurry. Weigh the two rollers before coating; roller a weighs 3100g, and roller b weighs 3103g.

[0040] In Example 2, the conventional anilox roller is used in conjunction with dot coating roller a, and in Example 1, the anilox roller is used in conjunction with dot coating roller b (the method of using the anilox roller and dot coating roller b is conventional, as detailed in CN116174260A). Figure 1 As shown), during coating, the coating machine speed is set to 100 m / min. The linear speeds of the anilox roller in Example 1, the conventional anilox roller in Example 2, dot coating roller a, and dot coating roller b are all 100 m / min.

[0041] First, take a 30kg bucket of conventional dot coating slurry and apply it using the conventional anilox roller and dot coating roller a of Example 2, with a coating length of 100,000 meters; then take another 30kg bucket of conventional dot coating slurry and apply it using the anilox roller and dot coating roller b of Example 1, with a coating length of 100,000 meters.

[0042] After coating, dot coating rollers a and b were ultrasonically cleaned (ultrasonicated at a frequency of 30kHz for 10 minutes), dried, and weighed. The weight of dot coating roller a was 3078g, the weight of dot coating roller b was 3099g, the wear loss of dot coating roller a was 22g, and the wear loss of dot coating roller b was 4g. The anilox roller of Example 1 has a significant effect on improving the wear of dot coating rollers.

[0043] Defect inspection was performed on the diaphragms coated by dot coating rollers a and b, respectively. The presence of impurities was observed, and it was identified whether they were particles from the dot coating rollers. The appearance of the impurities was as follows: Figure 3 As shown, the number of impurities in the diaphragm coated by dot coating roller a was 23, while the number of impurities in the diaphragm coated by dot coating roller b was 1. This indicates that using the anilox roller of Example 1 for dot coating can effectively reduce impurities caused by wear of the dot coating roller.

[0044] Samples were taken from the 99,000-100,000 m section of the diaphragm coated by dot-coating rollers a and b, respectively, to test the uniformity of diaphragm thickness and weight. For thickness testing: 10 transverse strips of the diaphragm coated by rollers a and b were taken from each strip, and 10 test points were measured on each strip (these 10 test points were in the same location on each strip). The thickness at each test point was obtained, and the unit of thickness was μm. For weight testing: 10 transverse strips of the diaphragm coated by rollers a and b were taken from each strip, and 3 test areas were measured on each strip (each test area was the same size). The weight of each test area (weight of diaphragm per square meter) was obtained, and the unit of weight was g / m². The thickness test results are as follows: Figure 4 As shown ( Figure 4 The unit of the vertical axis is μm, and the weight test results are as follows: Figure 5 As shown ( Figure 5 The unit of the vertical axis is g / m².

[0045] Depend on Figure 4 and Figure 5 It can be visually observed that in the 99000m-100000m range, the dot-coating roller b ( Figure 4 and Figure 5 The uniformity of diaphragm thickness and weight obtained by the "b roller" is better than that of the dot-coating roller (a roller). Figure 4 and Figure 5 (The anilox roller in Example 1 can improve the coating effect.)

[0046] Example 4

[0047] Prepare two dot coating rollers, c and d, that are identical in material, model, and specifications, and set up the first and second groups of experiments.

[0048] Group 1: Using the conventional anilox roller of Example 2 in combination with dot coating roller d, conventional dot coating slurry is applied on the coating machine: the speed of the coating machine is set to 100m / min, the linear speed of the dot coating roller d and the conventional anilox roller is 100m / min, the coverage rate is set to 20%, and the coating length is 500m.

[0049] Group 2: Using the anilox roller of Example 1 paired with dot coating roller c (dot coating roller c weighs 3150g before coating), conventional dot coating slurry was applied on a coating machine to verify the coating effect when the speed of the coating machine, the linear speed of the dot coating roller c, and the linear speed of the anilox roller are the same and different: During the coating process, the linear speed of the dot coating roller c and the speed of the coating machine were always kept at 100m / min. The linear speed of the anilox roller was set to 50m / min, 60m / min, 70m / min, 80m / min, 90m / min, 100m / min, 110m / min, 120m / min, 130m / min, 140m / min, and 150m / min, respectively. The coverage rate was set to 20%, and 500m were coated at each anilox roller linear speed.

[0050] After coating, the coating thickness (separator thickness - base film thickness) and coating amount (weight of coating on each square meter of separator) of the diaphragm coated at the linear speed of each anilox roller in the second group were tested. The test results are shown in Table 1. It can be seen from Table 1 that when the linear speed of the dot coating roller c is kept constant, the coating thickness and coating amount are improved when the linear speed of the anilox roller is increased.

[0051] In existing technologies, the speed of conventional anilox rollers must be consistent with that of the dotting plate rollers; otherwise, the dotting plate rollers will be damaged when they come into contact. Compared to conventional anilox rollers, which can only be used in dotting applications at the same linear speed as the dotting plate rollers, this invention broadens the process conditions of the equipment and makes the operation simpler.

[0052] Table 1

[0053]

[0054] After coating, the coating thickness and coating amount of the first group of coated diaphragms were tested, and the test results are shown in Table 2.

[0055] Table 2

[0056]

[0057] After coating, the dot coating roller c was ultrasonically cleaned (ultrasonicated at a frequency of 30kHz for 10 minutes), dried, and weighed to be 3148g. The weight loss of the dot coating roller c after coating was 2g, indicating that the wear of the dot coating roller was also relatively small even with the expansion of process conditions.

[0058] This invention ensures that the contact between the anilox roller and the dotting roller is soft while maintaining normal liquid flow. Even if the protrusions of the dotting roller come into contact with the anilox roller, the dotting roller will not be damaged, thus increasing its service life. The anilox roller and the dotting roller can operate at different linear speeds during operation, which broadens the process conditions and greatly improves the adjustability of the equipment.

[0059] The above description of the present utility model is exemplary. It should be noted that, without departing from the core of the present utility model, any simple modifications, alterations, or other equivalent substitutions that can be made by those skilled in the art without creative effort fall within the protection scope of the present utility model.

Claims

1. A diaphragm coating system, characterized in that, include: An anilox roller and a dot-coating roller are used to contact the slurry and transfer it to the dot-coating roller. The dot-coating roller is used to coat the diaphragm. The anilox roller and the dot-coating roller have the same or different rotation speeds. The anilox roller includes a roller body (2) and a flexible material layer (1). The outer surface of the roller body (2) is cylindrical. The flexible material layer (1) is formed into an annulus and attached to the circumferential surface of the roller body (2) and fixedly connected to the roller body (2). The outer surface of the flexible material layer (1) has a plurality of grooves (3) arranged in an array. Adjacent grooves (3) are spaced apart. Between adjacent grooves (3), the flexible material layer (1) forms a protrusion (4) relative to the bottom of the groove (3). The protrusion (4) forms a grid on the outer surface of the flexible material layer (1).

2. The diaphragm coating system according to claim 1, characterized in that, The roller body (2) is a cavity.

3. The diaphragm coating system according to claim 2, characterized in that, The outer diameter of the roller body (2) is 81~106mm, and the wall thickness of the roller body (2) is 3~10mm.

4. The diaphragm coating system according to claim 1, characterized in that, The thickness of the flexible material layer (1) is 2~5mm.

5. The diaphragm coating system according to claim 1, characterized in that, The depth of each groove (3) is 0.1~3mm.

6. The diaphragm coating system according to claim 5, characterized in that, The grooves (3) are arranged at equal intervals on the outer surface of the flexible material layer (1).

7. The diaphragm coating system according to claim 6, characterized in that, The shape of the cross section of each groove (3) along the circumferential surface of the roller (2) is one or more of quadrilaterals, triangles and hexagons.

8. The diaphragm coating system according to claim 1, characterized in that, The width of the protrusion (4) is 100~200μm.

9. The diaphragm coating system according to claim 2, characterized in that, The roller body (2) is made of alloy steel.

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