Battery electrode sheet coating apparatus and coating method

Abstract

The application provides a battery pole piece coating device and a battery pole piece coating method. The battery pole piece coating device comprises: a material spraying mechanism having a plurality of material spraying ports distributed at intervals along a first direction, the plurality of material spraying ports being used to spray slurry to the surface of a current collector to form a coating layer covering the surface of the current collector; and a plurality of heating rollers distributed at intervals along the first direction, the plurality of heating rollers being arranged below the current collector along a second direction and being used to heat the coating layer. The coating device of the application forms a required coating layer on the current collector layer by layer through the plurality of material spraying ports distributed at intervals, and heats the coating layer through the plurality of heating rollers. Compared with forming the required coating layer at one time, the coating device of the application can fill holes in a previous coating layer through a subsequent coating layer, and can avoid cracking of the coating layer due to volatilization of a large amount of solvent.

Description

TECHNICAL FIELD

[0001] The present application mainly relates to the field of lithium battery production, in particular to a battery pole piece coating device and a coating method. BACKGROUND

[0002] The coating process is one of the key processes in the production of lithium ion batteries, mainly including transfer coating process and extrusion coating process. Both transfer coating process and extrusion coating process are direct contact type, which sprays slurry on the surface of the current collector through transfer roller or extrusion die, and then bakes the slurry sprayed on the surface of the current collector through an oven.

[0003] With the demand of users for higher energy density and lower cost, high area density coating technology gradually popularizes. The transfer coating process and the extrusion coating process have low coating efficiency when performing high area density coating. When drying the coating layer, the coating layer will crack due to the rapid evaporation of a large amount of solvent.

[0004] Therefore, how to improve the high area density coating efficiency and avoid coating cracking during high area density coating is a problem to be solved. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a battery pole piece coating device and a coating method, which can improve the high area density coating efficiency and avoid coating cracking during high area density coating.

[0006] The technical solution adopted by the present application to solve the above technical problem is a battery pole piece coating device, comprising: a material spraying mechanism having a plurality of material spraying ports spaced apart along a first direction, the plurality of material spraying ports being used to spray slurry on the surface of the current collector to form a coating layer covering the surface of the current collector; and a plurality of heating rollers spaced apart along the first direction, the plurality of heating rollers being arranged below the current collector along a second direction for heating the coating layer, wherein the first direction intersects the second direction.

[0007] In an embodiment of the present application, each of the material spraying ports is rectangular, the width of each of the material spraying ports decreases in turn along the first direction, and the length of each of the material spraying ports is equal to the width of the current collector.

[0008] In an embodiment of the present application, the heating temperature of the plurality of heating rollers increases in turn along the first direction.

[0009] In an embodiment of the present application, at least one of the heating rollers is arranged behind the material spraying mechanism along the first direction to preheat the current collector.

[0010] In an embodiment of the present application, the remaining heating rollers are arranged below the material spraying mechanism along the second direction.

[0011] In an embodiment of the present application, at least one of the heating rollers is arranged in front of each of the spray ports along the first direction for heating the coating layer sprayed by the corresponding spray port before the coating layer is covered.

[0012] In an embodiment of the present application, at least one of the heating rollers is arranged in front of each of the spray ports along the first direction for heating the coating layer sprayed by the corresponding spray port before the coating layer is covered.

[0013] In an embodiment of the present application, the drying unit is arranged in front of the spraying mechanism along the first direction.

[0014] In an embodiment of the present application, the drying unit is arranged in front of the spraying mechanism along the first direction.

[0015] In an embodiment of the present application, at least one of the heating rollers is arranged in front of each of the spray ports along the first direction for heating the coating layer sprayed by the corresponding spray port before the coating layer is covered.

[0016] The coating device and the coating method of the present application can form the required coating layer on the current collector layer by layer through the plurality of spaced spray ports, and heat the coating layer through the plurality of heating rollers. Compared with forming the required coating layer at one time, the coating device of the present application can fill the holes in the previous coating layer with the subsequent coating layer, and avoid cracking of the coating layer due to evaporation of a large amount of solvent. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to make the above objectives, characteristics and advantages of the present application more apparent and comprehensible, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings, in which:

[0018] Figure 1 is a structural schematic diagram of a battery pole piece coating device according to an embodiment of the present application;

[0019] Figure 2 is a bottom view of a spraying mechanism according to an embodiment of the present application;

[0020] Figure 3 is a front view of a battery pole piece coating device according to an embodiment of the present application;

[0021] Figure 4 is an exemplary flowchart of a battery pole piece coating method according to an embodiment of the present application.

[0022] REFERENCE NUMERALS

[0023] current collector 10 first spray port 111

[0024] first surface 11 second material spraying port 112

[0025] second surface 12 third material spraying port 113

[0026] coating layer 20 heating roller 120

[0027] first coating layer 21 first heating roller 121

[0028] second coating layer 22 second heating roller 122

[0029] third coating layer 23 third heating roller 123

[0030] coating device 100 fourth heating roller 124

[0031] material spraying mechanism 110 drying unit 130 DETAILED DESCRIPTION

[0032] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0033] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application, however, can be practiced in a variety of ways beyond the specific embodiments described herein, and the present application is not limited to the specific embodiments described herein.

[0034] As used in the present application and in the claims, the indefinite articles "a", "an", and "the" and / or "at least one" do not exclude a plurality, and "a plurality" is equivalent to "multiple", unless the context clearly indicates otherwise. The terms "comprises", "comprising", "includes", "including" and the like can be used herein to indicate the inclusion of a step or element with regard to a process, method, article or apparatus that comprises, has, or includes, but do not preclude the presence or addition of one or more other steps or elements.

[0035] In addition, it should be noted that the use of "first", "second", and the like, with regard to a certain feature or element, is merely intended for convenience of distinguishing that certain feature or element from another feature or element, and does not imply that the certain feature or element is more important than the other feature or element. In addition, the terms "comprise", "comprising", "include", "including", and the like, used in the present application, are intended to be inclusive, and not to exclude, other steps, elements, and the like. In addition, although the terms "first", "second", and the like can be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another. Thus, a "first" element discussed above could be termed a "second" element without departing from the scope of the present application. Furthermore, the terms "comprise", "comprising", "include", "including", and the like, as used herein, are specifically intended to be inclusive and not exclusive. That is, these terms are used in their broadest sense to encompass the presence of stated elements or integers, but not preclude the presence or addition of one or more other elements or integers.

[0036] Flowcharts are used in this application to illustrate the operations performed by systems according to embodiments of the application. It should be understood that the operations in the figures need not necessarily be performed in the order shown. Rather, various steps can be handled in different order or simultaneously. Further, or additional operations can be added or removed from the processes, and some steps can be omitted or combined.

[0037] Next, the battery electrode sheet coating device and the coating method according to embodiments of the application will be described with specific examples.

[0038] Figure 1 is a structural schematic diagram of a battery electrode sheet coating device according to an embodiment. As shown in Figure 1 , the coating device 100 includes a material spraying mechanism 110 and a heating roller 120. The material spraying mechanism 110 is arranged above the current collector 10 along the second direction D2, and the heating roller 120 is arranged below the current collector 10 along the second direction D2. When the coating device 100 is working, the heating roller 120 drives the current collector 10 to transport along the first direction D1 by rolling. When the current collector 10 moves along the first direction D1, the material spraying mechanism 110 sprays the slurry to the surface of the current collector 10 along the second direction D2 towards the material spraying mechanism 110 to form a coating layer 20 covering the surface of the current collector, and the heating roller 120 below the current collector 10 heats the coating layer 20 covering the surface of the current collector. It should be noted that "the coating layer covers the surface of the current collector" means that the coating layer covers at least part of the surface, rather than only covering the entire surface.

[0039] Specifically, referring to a bottom view schematic diagram of the material spraying mechanism according to an embodiment shown in Figure 2 , Figure 2 schematically represents the case of observing the material spraying mechanism 110 along the second direction D2 in Figure 1 . As shown in Figure 2 , the material spraying mechanism 100 has a plurality of first material spraying ports 111, second material spraying ports 112 and third material spraying ports 113 distributed along the first direction D1 at intervals. In combination with Figure 1 , when the coating device 100 is working, the slurry is sprayed out from the first material spraying ports 111, the second material spraying ports 112 and the third material spraying ports 113 and coated on the first surface 11 of the first current collector 110. The first material spraying ports 111, the second material spraying ports 112 and the third material spraying ports 113 are rectangular, the size along the width direction D3 of the current collector 10 is W1, and the sizes along the first direction D1 are L1, L2 and L3 respectively. The size W1 is the same as the size of the current collector 110 along the width direction D3, and the sizes L1, L2 and L3 are related to the flow rates of the slurry sprayed by the first material spraying ports 111, the second material spraying ports 112 and the third material spraying ports 113, which will be described later. In some embodiments, the size W1 can be different from the size of the current collector 110 along the width direction D3.

[0040] Referring toFigure 3 FIG. 1 shows a front view of a battery electrode sheet coating device according to an embodiment. A first heating roller 121, a second heating roller 122, a third heating roller 123, and a fourth heating roller 124 are spaced along a first direction D1 and are arranged below the current collector 10 along a second direction D2. The heating rollers are in contact with the second surface 12 of the current collector 10, and the heating rollers are rotatable about their own axes, so that the heating rollers drive the current collector 10 to move along the first direction D1 while the heating rollers also heat the coating on the first surface 11.

[0041] In particular, referring to FIG. 1, Figure 3 As shown in FIG. 1, the first heating roller 121 is arranged behind the material spraying mechanism 110 along the first direction D1, where "behind" means that the projection of the first heating roller 121 on the current collector 10 along the second direction D2 does not overlap with the projection of the material spraying mechanism 110 on the current collector 10 along the second direction D2, and the projection of the first heating roller 121 along the first direction D1 is on the right side of the projection of the material spraying mechanism 110. In this way, the first heating roller 121 preheats the current collector 10 before the current collector 10 moves below the material spraying mechanism 110. It can be understood that the number of heating rollers used to preheat the current collector is not limited to one, for example, it can be any natural number equal to or greater than 2. Figure 3

[0042] When the current collector 10 moves to the left along the first direction D1 below the first material spraying port 111, the material spraying mechanism 110 sprays slurry through the first material spraying port 111 to the first surface 11 of the current collector 10 to form a first coating layer 21. Because the first heating roller 121 preheats the current collector 10, the solvent in the first coating layer 21 is more easily volatilized. As the current collector 10 continues to move to the left along the first direction D1, when the current collector 10 moves below the second material spraying port 112, the material spraying mechanism 110 sprays slurry through the second material spraying port 112 to the current collector 10 to form a second coating layer 22, which covers the first coating layer 21 on the left side of the second material spraying port 112 along the first direction D1. Similarly, as the current collector 10 continues to move to the left along the first direction D1, when the current collector 10 moves below the third material spraying port 113, the material spraying mechanism 110 sprays slurry through the third material spraying port 113 to the current collector 10 to form a third coating layer 23, which covers the second coating layer 22 on the left side of the third material spraying port 113 along the first direction D1.

[0043] As shown in FIG. 1, Figure 3 ​As shown, the second heating roller 122 is arranged before the first spray port 111 along the first direction D1 and after the second coating layer 22 starts to cover the first coating layer 21 (as shown by the dashed line B). In other words, the second heating roller 122 is located between the dashed line A and the dashed line B along the first direction D1 for heating the first coating layer 21 before the first coating layer 21 is covered by the second coating layer 22. In this way, the holes in the first coating layer 21 due to solvent evaporation can be filled by the subsequent second coating layer 22. It is understood that the number of heating rollers for heating the first coating layer 21 before the first coating layer 21 is covered by the second coating layer 22 is not limited to one. The number of heating rollers can be increased according to requirements. Figure 2 In one embodiment, the number of heating rollers can be increased according to requirements.

[0044] Similarly to the second heating roller, the third heating roller 123 is arranged before the second spray port 112 along the first direction D1 and after the third coating layer 23 starts to cover the second coating layer 22 (as shown by the dashed line C). In other words, the third heating roller 123 is located between the dashed line B and the dashed line C along the first direction D1 for heating the second coating layer 22 before the second coating layer 22 is covered by the third coating layer 23. In this way, the holes in the second coating layer 22 due to solvent evaporation can be filled by the subsequent third coating layer 23. It is understood that the number of heating rollers for heating the second coating layer 22 before the second coating layer 22 is covered by the third coating layer 23 is not limited to one. The number of heating rollers can be increased according to requirements. Figure 2 It is understood that because the first coating layer 21 is covered by the second coating layer 22, the third heating roller 123 inevitably also heats the first coating layer 21 when heating the second coating layer 22. By arranging the third heating roller 123, the temperature of the first coating layer 21 can be maintained, which is conducive to the continuous evaporation of the solvent in the first coating layer 21. With continued reference to Figure 3 As shown, the fourth heating roller 124 is arranged before the third spray port 113 along the first direction D1 for heating the third coating layer 23.

[0045] With reference to Figure 3 As shown, in one embodiment, the second heating roller 122, the third heating roller 123, and the fourth heating roller 124 can also not be arranged in the manner shown in Figure 3 For example, the second heating roller 122, the third heating roller 123, and the fourth heating roller 124 are arranged below the spray mechanism 110 along the second direction D2, without limiting the positional relationship between the heating rollers and the spray ports. In this way, heating the coating layers by the heating rollers can avoid the coating layers from cracking due to the evaporation of a large amount of solvent.

[0046] As Figure 3As shown, the first coating 21, the second coating 22 and the third coating 23 form an ascending ladder structure along the first direction D1, and the total thickness of the coatings in the second direction D2 increases in turn. In view of the change of the total thickness of the coatings, in an embodiment, the temperatures of the first heating roller 121, the second heating roller 122, the third heating roller 123 and the fourth heating roller 124 increase in turn to ensure the uniformity and higher temperature of the coatings in the second direction D2. In this way, it is beneficial to promote the volatilization of the solvent. In some embodiments, the temperatures of the first heating roller 121, the second heating roller 122, the third heating roller 123 and the fourth heating roller 124 are 90°C, 100°C, 110°C and 120°C respectively. In other embodiments, in view of the fact that the time required for the heat of the heating rollers to be transferred from the current collector to the uppermost coating (e.g. the third coating 123 in Figure 3 some embodiments, the flow rates of the slurry sprayed by the first spray port 111, the second spray port 112 and the third spray port 113 gradually decrease, and in this way, it is beneficial to ensure the uniformity and higher temperature of the coatings in the second direction D2.

[0047] As shown in Figure 2 some embodiments, the sizes L1, L2 and L3 of the first spray port 111, the second spray port 112 and the third spray port 113 along the first direction D1 gradually decrease, for example, in some embodiments, the sizes L1, L2 and L3 are 3mm, 2mm and 1mm respectively. The above design of the sizes L1, L2 and L3 can achieve the purpose of gradually decreasing the flow rates of the slurry sprayed by the first spray port 111, the second spray port 112 and the third spray port 113. It should be understood that the number of spray ports in the present application is not limited to Figure 2 three, and the specific number of spray ports can be set according to requirements.

[0048] Returning to Figure 1 some embodiments, the coating device 100 further comprises a drying unit 130. The drying unit 130 is arranged in front of the spraying mechanism 110 along the first direction D1, and the drying unit 130 can be used to dry the coating 20, in combination with Figure 3 As shown, the coating 20 comprises the first coating 21, the second coating 22 and the third coating 23, and before the coating 20 enters the drying unit 130, the plurality of heating rollers have heated the coating, and the solvent in the coating has been volatilized. Therefore, even if the areal density of the coating 20 is high (e.g. equal to or greater than 25mg / cm 2 ), the coating 20 will not crack after being dried by the drying unit 130. The drying unit 130 can be an oven.

[0049] The coating device in the above embodiments of the present application forms the required coating layer on the current collector layer by layer through the plurality of spaced spray ports, and heats the coating layer through the plurality of heating rollers. Compared with forming the required coating layer at one time, the coating device of the present application can fill the holes in the previous coating layer with the subsequent coating layer, and avoid cracking of the coating layer due to evaporation of a large amount of solvent.

[0050] Another aspect of the present application also provides a battery pole piece coating method. Referring to Figure 4 the example flowchart of the battery pole piece coating method of an embodiment. The coating method of this embodiment includes the following steps:

[0051] Step S210: providing a current collector;

[0052] Step S220: spraying slurry on the surface of the current collector using a spraying mechanism to form a coating layer covering the surface of the current collector;

[0053] Step S230: heating the coating layer using a plurality of heating rollers.

[0054] The above steps S210 to S230 are described in detail below.

[0055] In combination with Figure 1 shown in step S210, the current collector 10 is provided, and the current collector 10 is transported along the first direction D1 by the heating roller 120. The current collector 10 can be a positive electrode current collector or a negative electrode current collector.

[0056] In combination with Figure 3 shown in step S220, the slurry is sprayed on the first surface 11 of the current collector 10 using the spraying mechanism 110 to form a coating layer 20 covering the first surface 11. The slurry can be lithium iron phosphate slurry.

[0057] In step S230, the coating layer 20 covering the first surface 11 is heated using a plurality of heating rollers 120, so that part of the solvent in the coating layer 20 is volatilized, and cracking of the coating layer due to volatilization of a large amount of solvent when the coating layer is heated by the subsequent drying unit is avoided.

[0058] Referring to Figure 3 In an embodiment, at least one heating roller is provided in front of each spray port of the spraying mechanism 110 along the first direction D1 to heat the slurry sprayed by the corresponding spray port before the slurry is covered.

[0059] Other details of the coating method of the present application can be referred to the description of the coating device above, which will not be expanded here. The coating method of the present application can improve the high area density coating efficiency and avoid cracking of the coating layer during high area density coating.

[0060] Having described the basic concepts, it is obvious that the above-described application discloses only an example for the skilled in the art and does not limit the present application. Although not explicitly described, the skilled in the art can make various modifications, improvements and corrections to the present application. Such modifications, improvements and corrections are suggested in the present application, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of the present application.

[0061] Meanwhile, specific words are used in the present application to describe the embodiments of the present application. As "one embodiment", "an embodiment", and / or "some embodiments" mean a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that the "one embodiment" or "one alternative embodiment" mentioned in the present specification twice or more does not necessarily mean the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be properly combined.

[0062] Some embodiments use numbers to describe components, quantities of attributes, and it should be understood that such numbers used in the description of the embodiments are modified by the modifier "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicates that the stated number can vary by ±20%. Accordingly, numerical parameters in the specification and claims are approximations, and the approximations can vary depending on the desired characteristics of the individual embodiments. In some embodiments, numerical parameters are provided as approximations, and the approximations can vary depending on the desired characteristics of the individual embodiments. In some embodiments, numerical parameters should be considered in the context of the number of significant digits and accurate measurement of the number. Although the numerical ranges and parameters in some embodiments of the present application are approximations, such numerical ranges and parameters are set forth in a manner that is as precise as practicable.

Claims

1. A battery electrode coating apparatus, characterized in that, include: The spraying mechanism has a plurality of spray nozzles spaced apart along a first direction. The plurality of spray nozzles are used to spray slurry onto the surface of the current collector to form a coating covering the surface of the current collector. Each spray nozzle is rectangular, the width of each spray nozzle decreases sequentially along the first direction, and the length of each spray nozzle is equal to the width of the current collector. as well as Multiple heating rollers are spaced apart along the first direction and disposed below the current collector along the second direction for heating the coating. The heating temperature of the multiple heating rollers increases sequentially along the first direction. At least one heating roller is disposed in front of each nozzle along the first direction for heating the coating before it is covered by the coating sprayed from the corresponding nozzle. The first direction intersects the second direction.

2. The coating apparatus as described in claim 1, characterized in that, At least one of the heating rollers is disposed behind the spraying mechanism along the first direction to preheat the current collector.

3. The coating apparatus as described in claim 2, characterized in that, The remaining heating roller is positioned below the spraying mechanism along the second direction.

4. The coating apparatus as described in claim 3, characterized in that, At least one of the remaining heating rollers is provided in front of each of the nozzles along the first direction for heating the coating before it is covered by the coating sprayed from the corresponding nozzle.

5. The coating apparatus as described in claim 1, characterized in that... Also includes: The drying unit is disposed in front of the spraying mechanism along the first direction.

6. A method for coating battery electrodes, characterized in that, The coating method, using the coating apparatus as described in any one of claims 1-5, comprises: Provide current collectors; The spraying mechanism is used to spray a slurry onto the surface of the current collector to form a coating covering the surface of the current collector; and The coating is heated using the plurality of heating rollers.

7. The coating method as described in claim 6, characterized in that, At least one heating roller is provided in front of each of the nozzles along the first direction to heat the coating before it is covered by the coating sprayed from the corresponding nozzle.

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