Pole piece coating system

Abstract

The utility model relates to the technical field of pole piece manufacturing, and provides a pole piece coating system, which is used for coating a coating on the surface of a base material and comprises an atomization device, at least one pair of roller groups, a blowing device, a coater, a coating back roller and a drying device which are arranged close to the base material, the atomization device, the at least one pair of roller sets, the air blowing device, the coater and the drying device are sequentially arranged in the conveying direction of the base material; each pair of roller groups comprises two conveying rollers and is used for clamping a base material between the two conveying rollers to realize conveying of the base material; the coater is arranged on the upper side of the base material, and the coating back roller is arranged on the lower side of the base material. According to the pole piece coating system provided by the utility model, the phenomenon of coating cracking in the pole piece manufacturing process can be improved, and the qualification rate of pole piece manufacturing is obviously improved.

Description

Technical Field

[0001] The utility model relates to the technical field of pole piece manufacturing, and in particular to a pole piece coating system. Background Art

[0002] Sodium-ion battery is a secondary battery (rechargeable battery) with the advantages of low price and abundant reserves. It can be used in energy storage systems, low-speed electric vehicles and other fields. The negative electrode is one of the core components of the sodium battery cell. Unlike lithium batteries, sodium ions do not form alloys with aluminum, so the negative electrode of the sodium-ion battery can use aluminum foil as the current collector. Both the positive and negative electrodes use aluminum foil as the current collector. On the one hand, the sodium-ion battery has no over-discharge characteristics and can be discharged to 0V. On the other hand, it also reduces the cost.

[0003] However, the negative electrode of the sodium-ion battery generally uses deionized water as the solvent, and the surface wetting tension of the aluminum foil is relatively small, which causes the slurry to shrink and curl during the coating process. The coated electrode is brittle and prone to cracking and falling off, which can easily lead to the performance degradation of the sodium-ion battery and the creation of safety hazards.

[0004] In addition, since the hard carbon material has sharp edges, small particle size, and large surface area, it is difficult to wet and evenly disperse in the water-based slurry, and the slurry is prone to agglomeration and sedimentation. During coating, there are obvious scratches, particles, and bubbles on the membrane surface, the electrode adhesion is poor, and it is easy to have a single-sided coating without cracking, and a single-sided reverse double process when the roller is passed.

[0005] At present, the commonly used methods to improve the cracking phenomenon of the electrode sheet during negative electrode coating are: Method 1: By adjusting the temperature, air volume, coating speed and other parameters of the oven, the negative electrode sheet is dried under reasonable parameters to improve the state of the electrode sheet. Method 2: By adding an organic solvent to the negative electrode slurry, the boiling point of the solvent in the negative electrode slurry is increased and the overall volatilization rate of the solvent is reduced. For example, the organic small molecule liquid that can be added includes N-methylpyrrolidone or ethylene carbonate, but the disadvantage of N-methylpyrrolidone is that it is difficult to recycle, and it is easy to cause environmental pollution after discharge and is harmful to the human body; ethylene carbonate is a solid crystal at room temperature with a boiling point of 248°C. It is easy to remain in the negative electrode sheet, and it will seep out or be dissolved by the electrolyte later, which will have an adverse effect on the rate performance, cycle performance and storage performance of the lithium battery. In addition, the disadvantages of the above-mentioned organic small molecule liquid also include that after being added to the negative electrode slurry, it can only play a role in the coating and baking process, and cannot improve the performance of the negative electrode slurry.

[0006] The above method for improving the cracking of the electrode piece is only to improve the cracking of the electrode piece by adjusting the solvent evaporation rate during the coating and baking process. However, due to the brittleness of the sodium ion negative electrode piece, there are still technical bottlenecks in the manufacturing process of the electrode piece, such as no cracking during single-sided coating, cracking during the single-sided reverse double-roll process, and cracking during double-sided coating.

[0007] In view of this, the present utility model is proposed. Utility Model Content

[0008] The utility model aims to provide a pole piece coating system, which can improve the coating cracking problem in the manufacturing process of the negative pole piece of the sodium ion battery.

[0009] The embodiment of the utility model is achieved as follows:

[0010] In a first aspect, the utility model provides a pole piece coating system for coating a coating on a substrate surface, the pole piece coating system comprising an atomizing device arranged close to the substrate, at least one pair of roller groups, a blowing device, a coater, a coating backing roller and a drying device;

[0011] An atomizing device, at least one pair of rollers, a blowing device, a coater and a drying device are sequentially arranged along the conveying direction of the substrate;

[0012] Each pair of rollers includes two conveying rollers, which are used to sandwich the substrate between the two conveying rollers to realize the conveying of the substrate;

[0013] The coater is arranged on the upper side of the substrate, and the coating backing roller is arranged on the lower side of the substrate.

[0014] In an optional embodiment, the atomizing device is disposed below the substrate to achieve spraying of mist droplets toward the atomizing device from below the substrate.

[0015] In an optional embodiment, the atomizing device includes a droplet generator, at least one atomizing tube, and at least one first control valve;

[0016] Each atomizing tube is located below the substrate, and each atomizing tube is provided with a plurality of atomizing holes for discharging mist droplets along the length direction;

[0017] Each atomizing tube is connected to a droplet generator, and at least one first control valve is arranged on at least one atomizing tube in a one-to-one correspondence, and is used to control the droplet flow rate in the corresponding atomizing tube.

[0018] In an optional embodiment, the extension direction of each atomization tube is perpendicular to the length direction of the substrate.

[0019] In an optional embodiment, the blowing device is disposed below the substrate to achieve blowing toward the substrate from below the substrate.

[0020] In an optional embodiment, the blowing device includes a blower, at least one air duct and at least one second control valve;

[0021] Each air duct is located below the substrate, and each air duct is provided with a plurality of air holes along the length direction;

[0022] Each air duct is connected to the fan, and at least one second control valve is arranged on at least one air duct in a one-to-one correspondence, so as to control the wind speed in the corresponding air duct.

[0023] In an optional embodiment, the extension direction of each air duct is perpendicular to the length direction of the substrate.

[0024] In an optional embodiment, the number of roller groups is 3.

[0025] In an optional embodiment, the pole piece coating system further includes a first pole piece roll and a second pole piece roll;

[0026] The first pole piece roll is arranged before the atomizing device, and is used to provide the substrate, and is used to continuously release the substrate when the coating system is working;

[0027] The second electrode roll is arranged after the drying device, and is used to continuously roll up the substrate with coating on the surface after drying.

[0028] In an optional embodiment, the electrode coating system further includes a slurry feeding device, which is used to add negative electrode slurry to the surface of the substrate from above;

[0029] The slurry delivery device is arranged before the atomization device.

[0030] The beneficial effects of the embodiments of the utility model are:

[0031] The pole piece coating system provided by the utility model can improve the phenomenon of cracking of the first surface coating that may exist when forming the second surface coating during the manufacturing process of the double-sided coated pole piece due to the arrangement of the atomizing device and the blowing device, and significantly improve the qualified rate of pole piece manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 A schematic diagram of the structure of a pole piece coating system provided in an embodiment of the utility model;

[0034] Figure 2A top view of the electrode coating system where an atomizing device is provided;

[0035] Figure 3 A top view of the pole piece coating system where a blowing device is provided.

[0036] Icons: 100-electrode coating system; 101-first electrode roll; 102-second electrode roll; 103-slurry feeding device; 120-atomizing device; 121-atomizing pipe; 122-atomizing hole; 123-first control valve; 124-droplet generator; 130-roller group; 131-transfer roller; 140-blowing device; 141-air duct; 142-air hole; 143-second control valve; 144-blower; 150-coater; 160-coating back roller; 170-drying device; 11-substrate. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0040] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the utility model product is usually placed when in use, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0041] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0042] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] like Figure 1 As shown, the embodiment of the utility model provides a pole piece coating system 100, which is used to apply a coating on the surface of a substrate 11. The pole piece coating system 100 includes an atomizing device 120 arranged close to the substrate 11, at least one pair of roller groups 130, a blowing device 140, a coater 150, a coating backing roller 160 and a drying device 170;

[0044] The atomizing device 120, at least one pair of roller groups 130, the blowing device 140, the coater 150 and the drying device 170 are sequentially arranged along the conveying direction of the substrate 11;

[0045] Each pair of rollers 130 includes two conveying rollers 131, which are used to sandwich the substrate 11 between the two conveying rollers 131 to convey the substrate 11;

[0046] The coater 150 is disposed on the upper side of the substrate 11 , and the coating backing roller 160 is disposed on the lower side of the substrate 11 .

[0047] Roller group 130 Roller group 130 Roller group 130 The pole piece coating system 100 provided in this embodiment has the following working process:

[0048] (1) Application of the first coating

[0049] like Figure 1 As shown, the substrate 11 is transferred from left to right by at least one pair of rollers 130, and slurry is injected onto the upper surface of the substrate 11. After being processed by the coater 150 and the coating back roller 160, a negative electrode slurry coating layer with a thick target surface density is formed on the surface of the substrate 11. Then, the substrate 11 enters the drying device 170 and is dried at 50 to 90° C. until the electrode weight loss rate is 0.1 to 3% (i.e., the drying degree is 80 to 95%, not completely dried), and then is sent out of the drying device 170 to form a substrate 11 with a first surface coating.

[0050] (2) Application of the second coating

[0051] The substrate 11 with the first surface coating is turned over (i.e., the uncoated side faces upward and the coated side faces downward) as for the first section of the system, and after the end of the substrate 11 is mounted on at least one pair of roller groups 130, the substrate 11 is moved from left to right, and the slurry is injected to the uncoated side to repeat the operation of step (1) so that the uncoated side is coated. During this process, the atomizing device 120 and the blowing device 140 are turned on, and the atomizing device 120 (with a pressure of 0.1 to 10 MPa) first wets the first surface coating to prevent the coating from cracking during the rolling process, and then the blowing device 140 (with a pressure of 0.1 to 10 MPa) is used to preliminarily dry the first surface coating, and then it is processed by the coater 150 and the coating back roller 160, and finally enters the drying device 170 to be dried at 50 to 90° C. to form a pole piece with coatings on both sides, and the pole piece weight loss rate is 0.1 to 2%.

[0052] During the single-sided coating process of the negative electrode of the sodium-ion battery, excessive wetting of the electrode can easily cause the slurry on the surface of the electrode to stick to the foil, and the electrode is prone to wrinkling and cracking during the double-sided coating process. Excessive wetting of the electrode on one side can easily cause the weight loss rate of the finished electrode to be too high, and the surface density of the electrode fluctuates greatly. Excessive drying of the electrode on one side can make the electrode brittle, resulting in cracking during the roller during the double-sided coating process, and cracking due to excessive drying of the electrode during the double-sided coating drying process.

[0053] The pole piece coating system 100 provided by the utility model adds an atomizing device 120 and a blowing device 140 on the basis of a conventional coating system, thereby improving the phenomenon of cracking of the first surface coating that may exist when forming the second surface coating during the manufacturing process of the double-sided coated pole piece, and significantly improving the qualified rate of pole piece manufacturing.

[0054] Optionally, the electrode coating system 100 further includes a first electrode roll 101 and a second electrode roll 102; the first electrode roll 101 is arranged before the atomizing device 120, and is used to provide the substrate 11, and when the coating system is working, it is used to continuously release the substrate 11. The second electrode roll 102 is arranged after the drying device 170, and is used to continuously roll up the substrate 11 with a coating on the surface after drying.

[0055] Initially, the substrate 11 with no coating on the surface is rolled up on the first pole piece roll 101. During the formation of the first surface coating, the first pole piece roll 101 and the substrate 11 synchronously release the substrate with no coating on the surface onto the substrate 11. After the first surface coating is formed on the surface of the substrate 11, it is rolled up onto the second pole piece roll 102. Before applying the second surface coating, the first pole piece roll 101 and the second pole piece roll 102 are exchanged. When applying the second surface coating, the second pole piece roll 102 and the roller group 130 continuously release the pole piece with the first surface coating on the surface and convey it to the right for applying the second surface coating.

[0056] Optionally, the electrode coating system 100 further includes a slurry feeding device 103 , which is used to add negative electrode slurry to the surface of the substrate 11 from above; the slurry feeding device 103 is arranged before the coater 150 .

[0057] like Figure 2 and Figure 3 As shown,

[0058] The atomizing device 120 is disposed below the substrate 11 to spray mist droplets from below to the substrate 11, thereby ensuring that the first surface coating can be uniformly wetted. The blowing device 140 is disposed below the substrate 11 to blow air from below to the substrate 11.

[0059] Optionally, the atomization device 120 includes a droplet generator 124, at least one atomization tube 121 and at least one first control valve 123; each atomization tube 121 is located below the substrate 11, and each atomization tube 121 is provided with a plurality of atomization holes 122 for discharging droplets along the length direction; each atomization tube 121 is connected to the droplet generator 124, and at least one first control valve 123 is arranged one-to-one on at least one atomization tube 121 for controlling the droplet flow rate in the corresponding atomization tube 121.

[0060] The specific setting of the atomizing device 120 can achieve uniform wetting of the first surface coating, especially the setting of the first control valve 123, which can adjust the flow rate according to the required wetting degree of the first surface coating, thereby further ensuring that the obtained negative electrode sheet coating has no cracks.

[0061] Optionally, the diameter of the atomization holes 122 is 1 mm, and the distance between adjacent atomization holes 122 in the length direction is 4 mm. In addition, the atomization holes 122 are evenly distributed along the circumference of the atomization tube 121, and the distance between adjacent atomization holes 122 in the circumferential direction is 2 mm.

[0062] Optionally, the extension direction of each atomization tube 121 is perpendicular to the length direction of the substrate 11 .

[0063] Optionally, the number of atomization tubes 121 is, for example, 3.

[0064] Optionally, the blowing device 140 includes a fan 144, at least one air duct 141 and at least one second control valve 143; each air duct 141 is located below the substrate 11, and each air duct 141 is provided with a plurality of air holes 142 along the length direction; each air duct 141 is connected to the fan 144, and at least one second control valve 143 is arranged one-to-one on at least one air duct 141 for controlling the wind speed in the corresponding air duct 141.

[0065] The specific setting of the blowing device 140 can achieve uniform drying of the first surface coating, especially the setting of the second control valve 143, which can adjust the flow rate according to the required dryness of the first surface coating, thereby further ensuring that the obtained negative electrode sheet coating is free of cracks.

[0066] Optionally, the diameter of the air holes 142 is 1.5 mm, and the distance between adjacent air holes 142 is 4 mm. In addition, the air holes 142 are evenly distributed along the circumference of the air duct 141, and the distance between adjacent air holes 142 in the circumferential direction is 2 mm.

[0067] Optionally, the extension direction of each air duct 141 is perpendicular to the length direction of the substrate 11 .

[0068] Optionally, the number of the air ducts 141 is, for example, 3.

[0069] Optionally, the number of roller sets 130 is three.

[0070] Example 1

[0071] Negative electrode slurry preparation:

[0072] S1. Prepare the materials according to the following weight proportions: 95.5 parts of hard carbon, 1 part of conductive agent, 1.5 parts of dispersant, and 2 parts of binder; the conductive agent is Super P, the dispersant is sodium carboxymethyl cellulose (CMC), and the binder is styrene-butadiene rubber.

[0073] S2, mixing dispersant CMC and water evenly to obtain glue solution I, the solid content of glue solution I is 1.2%;

[0074] S3, after the conductive agent dry powder and the hard carbon powder are respectively baked at 100° C. in vacuum for 6 hours to ensure that the moisture content is less than 500 ppm, the conductive agent is first added to the mixer, and then the hard carbon powder is added to the mixer three times and stirred evenly to obtain dry powder I;

[0075] S4. Add 65% glue solution I and appropriate amount of water to dry powder I and stir evenly to obtain slurry II. The solid content of the slurry is 67.5%;

[0076] S5, adding the remaining glue solution I to the slurry II and stirring evenly, then adding water to adjust the solid content to obtain slurry III, the solid content of the slurry is 54.5%;

[0077] S6. Evenly mix the binder and slurry III to obtain a final negative electrode slurry.

[0078] Pole coating:

[0079] (1) First surface coating: The substrate 11 is placed between the roller group 130 and moves from left to right. The substrate 11 is coated with slurry on its surface by the coater 150 and then sent to the drying mechanism. The substrate is dried at 70° C. until the electrode weight loss rate is 1.0%. The electrode is then sent out of the drying mechanism to obtain an electrode with a first surface coating.

[0080] (2) Second side coating: The electrode with the first side coating is turned over to the head end of the system, and the atomizing device 120 and the blowing device 140 are turned on to carry out the second side coating, wherein the pressure of the atomizing device 120 is 0.3 MPa, the air pressure of the blowing system is 0.33 MPa, and the drying temperature is 80°C to obtain the negative electrode electrode. The weight loss rate of the obtained negative electrode electrode is 0.4%.

[0081] Whether the electrode is cracked and the qualified rate are shown in Table 1.

[0082] Example 2

[0083] This embodiment is basically the same as Embodiment 1, except that:

[0084] The pressure of the atomizing device 120 is 0.5 MPa, the air pressure of the blowing system is 0.5 MPa, and the drying temperature is 85° C. to obtain a negative electrode sheet, and the weight loss rate of the obtained negative electrode sheet is 0.4%.

[0085] Whether the electrode is cracked and the qualified rate are shown in Table 1.

[0086] Comparative Example 1

[0087] This comparative example is basically the same as Example 1, except that the atomizing device 120 and the blowing device 140 are turned on.

[0088] Whether the electrode is cracked and the qualified rate are shown in Table 1.

[0089] Comparative Example 2

[0090] This comparative example is basically the same as Example 1, except that the blowing device 140 is not turned on.

[0091] During the second-side coating process, the pressure of the atomizing device 120 was set to 0.3 MPa and the drying temperature was set to 85° C. to obtain a negative electrode sheet, and the weight loss rate of the obtained negative electrode sheet was 0.4%.

[0092] Whether the electrode is cracked and the qualified rate are shown in Table 1.

[0093] Comparative Example 3

[0094] This comparative example is basically the same as Example 1, except that the atomizing device 120 is not turned on.

[0095] The air pressure of the blowing system is 0.33 MPa and the drying temperature is 85° C. to obtain a negative electrode sheet, and the weight loss rate of the obtained negative electrode sheet is 0.4%.

[0096] Whether the electrode is cracked and the qualified rate are shown in Table 1.

[0097] Table 1: The pole pieces obtained in each embodiment and comparative example

[0098]

[0099] In Examples 1 and 2, a blowing device 140 and an atomizing device 120 are added during the coating process, in Comparative Example 1, there is no blowing device 140 and an atomizing device 120, in Comparative Example 2, there is only an atomizing device 120, and in Comparative Example 3, there is only a blowing device 140. By comparing Examples 1 and 2 with the comparative examples, it can be seen that adding the blowing device 140 and the atomizing device 120 at the same time can significantly improve the coating cracking phenomenon and improve the coating qualification rate.

[0100] In summary, the coating system provided by the utility model, due to the arrangement of the atomizing device 120 and the blowing device 140, can avoid the possible cracking of the first surface coating when forming the second surface coating during the manufacturing process of the double-sided coated electrode, thereby significantly improving the qualified rate of electrode manufacturing.

[0101] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pole piece coating system, characterized in that: Used to apply a coating on the surface of a substrate, the pole piece coating system comprises an atomizing device arranged close to the substrate, at least one pair of roller groups, a blowing device, a coater, a coating backing roller and a drying device; The atomizing device, the at least one pair of rollers, the blowing device, the coater and the drying device are sequentially arranged along the conveying direction of the substrate; Each pair of the roller groups includes two conveying rollers, which are used to sandwich the substrate between the two conveying rollers to realize the conveying of the substrate; The coater is arranged on the upper side of the substrate, and the coating back roller is arranged on the lower side of the substrate.

2. The pole piece coating system according to claim 1, characterized in that: The atomizing device is arranged below the substrate to spray mist droplets from below the substrate to the substrate.

3. The pole piece coating system according to claim 2, characterized in that: The atomizing device comprises a droplet generator, at least one atomizing pipe and at least one first control valve; Each of the atomizing tubes is located below the substrate, and each of the atomizing tubes is provided with a plurality of atomizing holes for discharging mist droplets along the length direction; Each of the atomizing tubes is connected to the droplet generator, and the at least one first control valve is arranged on the at least one atomizing tube in a one-to-one correspondence, and is used to control the droplet flow rate in the corresponding atomizing tube.

4. The pole piece coating system according to claim 3, characterized in that: The extending direction of each atomizing tube is perpendicular to the length direction of the substrate.

5. The pole piece coating system according to claim 1, characterized in that: The blowing device is arranged below the substrate to blow air toward the substrate from below the substrate.

6. The pole piece coating system according to claim 5, characterized in that: The blowing device includes a blower, at least one air duct and at least one second control valve; Each of the air ducts is located below the substrate, and each of the air ducts is provided with a plurality of air holes along the length direction; Each of the air ducts is connected to the fan, and the at least one second control valve is arranged on the at least one air duct in a one-to-one correspondence, and is used to control the wind speed in the corresponding air duct.

7. The pole piece coating system according to claim 6, characterized in that: The extension direction of each of the air ducts is perpendicular to the length direction of the substrate.

8. The pole piece coating system according to claim 1, characterized in that: The number of the roller groups is 3.

9. The pole piece coating system according to claim 1, characterized in that: The pole piece coating system also includes a first pole piece roll and a second pole piece roll; The first pole piece roll is arranged before the atomizing device, and is used to provide the substrate, and is used to continuously release the substrate when the coating system is working; The second pole piece roll is arranged after the drying device, and is used for continuously rolling up the substrate with coating on the surface after drying.

10. The pole piece coating system according to claim 1, characterized in that: The electrode coating system further includes a slurry feeding device, which is used to add negative electrode slurry to the surface of the substrate from above; The slurry delivery device is arranged before the atomization device.

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