Thermal interface material coating method for battery cells

Abstract

A thermal interface material coating method for battery cells is disclosed. According to the present invention, a coating system comprising a rotating mechanism, a slot die coater and a substrate is provided so as to be adopted for coating a TIM material onto at least one battery cell. Particularly, the substrate is a meshed plate including a plurality of pores. As such, in case of a coating fluid flow rate of a slit nozzle of the slot die coater, a rotation speed of the rotation mechanism, a thickness of the substrate, and a pore size of the substrate all having been properly designed, it is able to form a TIM film having a laterally-uniform thickness on the battery cell by using the coating system.

Claims

1. A thermal interface material coating method for battery cells, comprising the steps of: (1) providing a rotating mechanism and a slot die coater, and filling a thermal interface material (TIM) fluid in a reservoir of the slot die coater; (2) securing at least one battery cell to the rotating mechanism disposed below the slot die coater; (3) providing a substrate comprising a plurality of pores, and disposing the substrate between the battery cell and the slot die coater; (4) when driving the rotating mechanism to rotate the battery cell, operating the slot die coater to spray the TIM fluid onto the substrate through a slit nozzle; and (5) allowing the TIM fluid to flow and pass through the plurality of pores, and then dropping on to an outer surface of the battery cell, thereby forming a TIM film on the outer surface of the battery cell.

2. The thermal interface material coating method of claim 1, wherein a rotation speed of the battery cell is negative correlation to a stickiness of the TIM fluid.

3. The thermal interface material coating method of claim 1, wherein the substrate is an arc-shaped meshed plate having a curvature radius in a range between 3 mm and 50 mm.

4. The thermal interface material coating method of claim 1, wherein a slick layer is formed on a surface of the substrate and an inner surface of each of the pore, such that the supplied TIM fluid is allowed to flow on the surface of the substrate smoothly, and being also allowed to pass through said pore smoothly.

5. The thermal interface material coating method of claim 1, wherein the substrate has a thickness in a range between 0.05 mm and 100 mm, and said pore having a mesh size in a range between 10 mesh and 200 mesh.

6. The thermal interface material coating method of claim 1, wherein the battery cell is a cylindrical battery cell, and the TIM fluid being made of a thermal interface material comprising a polymer matrix and a plurality of thermal conductive filler spread in the polymer matrix.

7. The thermal interface material coating method of claim 1, wherein a scraping plate is connected to an edge of the slit nozzle, and the scraping plate distributes the TIM fluid evenly across the substrate after the slit nozzle spreads the TIM fluid onto the substrate.

8. The thermal interface material coating method of claim 1, wherein a pressing plate is disposed in the reservoir, and a pressurizing apparatus is adopted for supplying a pressing force to the pressing plate, so as to push the pressing plate at a motion speed, thereby controlling a fluid supplying rate of the slit nozzle.

9. The thermal interface material coating method of claim 8, wherein the pressurizing apparatus comprises a pneumatic-type pressurizing apparatus or mechanical-type pressurizing apparatus.

10. The thermal interface material coating method of claim 1, wherein a heating device is connected to the reservoir adopted for heating the TIM fluid stored in the reservoir.

11. A thermal interface material coating method for battery cells, comprising the steps of: (1) providing a moving mechanism and a slot die coater, and filling a thermal interface material (TIM) fluid in a reservoir of the slot die coater; (2) disposing at least one battery cell on the moving mechanism disposed below the slot die coater; (3) providing a substrate having a plurality of pores, and disposing the substrate between the battery cell and the slot die coater; (4) when moving mechanism to carry the battery cell to move along a horizontal direction, operating the slot die coater to move a slit nozzle over the substrate, so as to spray the TIM fluid onto the substrate; and (5) allowing the TIM fluid to flow and pass through the plurality of pores, and then drop on to an outer surface of the battery cell, thereby forming a TIM film on the outer surface of the battery cell.

12. The thermal interface material coating method of claim 11, wherein when operating the moving mechanism to carry the battery cell to move along the horizontal direction, the battery cell horizontally moves at a speed in a range between 1 cm/s and 30 cm/s.

13. The thermal interface material coating method of claim 11, wherein a slick is layer formed on a surface of the substrate and an inner surface of each of the pore, therefore the TIM fluid is allowed to flow on the surface of the substrate smoothly, and pass through said pore smoothly.

14. The thermal interface material coating method of claim 11, wherein the battery cell is selected from a group consisting of prismatic battery cell and pouch battery cell, and the TIM fluid being made of a thermal interface material comprising a polymer matrix and a plurality of thermal conductive filler spread in the polymer matrix.

15. The thermal interface material coating method of claim 11, wherein the substrate comprises a thickness in a range between 0.05 mm and 100 mm, and the pore comprises a mesh size in a range between 10 mesh and 200 mesh.

16. The thermal interface material coating method of claim 11, wherein a scraping plate is connected to an edge of the slit nozzle.

17. The thermal interface material coating method of claim 11, wherein the scraping plate distributes the TIM fluid evenly across the substrate after the slit nozzle supplies the TIM fluid onto the substrate.

18. The thermal interface material coating method of claim 11, wherein a pressing plate is disposed in the reservoir, and a pressurizing apparatus being adopted for supplying a pressing force to the pressing plate, so as to push the pressing plate by a motion speed, thereby controlling a fluid supplying rate of the slit nozzle.

19. The thermal interface material coating method of claim 18, wherein the pressurizing apparatus comprises pneumatic-type pressurizing apparatus or mechanical-type pressurizing apparatus.

20. The thermal interface material coating method of claim 11, wherein a heating device is connected to the reservoir adopted for heating the TIM fluid stored in the reservoir.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention as well as a preferred mode of use and advantages thereof will be best understood by referring to the following detailed description of an illustrative embodiment in conjunction with the accompanying drawings, wherein:

[0036] FIG. 1 shows a perspective view of a conventional cylindrical battery cell;

[0037] FIG. 2 shows a perspective view of a conventional prismatic battery cell;

[0038] FIG. 3 shows a perspective view of a conventional pouch battery cell;

[0039] FIG. 4 shows the first perspective view of a thermal interface material coating system for battery cells according to the present invention;

[0040] FIG. 5 shows the second perspective view of the thermal interface material coating system;

[0041] FIG. 6 shows an exploded view of the thermal interface material coating system;

[0042] FIG. 7 shows the first sectional view of the thermal interface material coating system;

[0043] FIG. 8 shows the first flowchart of the thermal interface material coating method according to the present invention;

[0044] FIG. 9 shows the second cross sectional view of the thermal interface material coating system; and

[0045] FIG. 10 shows the second flowchart of the thermal interface material coating method according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] To more clearly describe a thermal interface material coating method according to the present invention, embodiments of the present invention will be described in detail with reference to the attached drawings hereinafter.

First Example

[0047] In an embodiment, the method utilizes a rotating mechanism, a slot die coater and an arc-shaped meshed plate to coat a thermal interface material (TIM) film on at least one battery cell. In other words, the method utilizes a TIM coating system comprising one rotating mechanism, one slot die coater and one arc-shaped meshed plate to achieve coating a TIM film on at least one battery cell.

[0048] With reference to FIG. 4, there is shown the first perspective view of the thermal interface material coating system is shown for the battery cells according to the present invention. FIG. 5 shows the second perspective view of the thermal interface material coating system. FIG. 6 shows an exploded view of the thermal interface material coating system, and FIG. 7 shows the first sectional view of the thermal interface material coating system.

[0049] FIG. 8 shows the first flowchart of a thermal interface material (TIM) coating method according to the present invention. As shown in FIGS. 4-8, the TIM coating method firstly proceeds with step S1 to provide a rotating mechanism 11 and a slot die coater 12, and fill a thermal interface material (TIM) fluid in a reservoir 121 of the slot die coater 12. Then the method proceeds with step 2 for securing at least one battery cell B1 to the rotating mechanism 11, therefore the battery cell B1 is disposed below the slot die coater 12. In step S3, a substrate 13 comprising a plurality of pores is provided and disposed between the battery cell B1 and the slot die coater 12.

[0050] In another embodiment, the substrate 13 is an arc-shaped meshed plate having a curvature radius in a range between 3 mm and 50 mm. Moreover, the battery cell B1 is a cylindrical battery cell, therefore the curvature radius of the arc-shaped meshed plate (i.e., substrate 13) is designed to match the radius of the cylindrical battery cell. On the other hand, the substrate 13 comprises a thickness in a range between 0.05 mm and 100 mm, and the pore comprises a mesh size in a range between 10 mesh and 200 mesh. U.S. mesh size is defined as the number of openings in one square inch of a screen. For example, a 36 mesh comprises 36 openings per square inch while a 150 mesh comprises 150 openings per square inch.

[0051] The method subsequently proceeds with step S4. In step S4, the rotating mechanism 11 is driven to rotate the battery cell B1, and the slot die coater 12 moves the slit nozzle 122 over the substrate 13 to spray the TIM fluid onto the substrate 13. As shown in FIG. 7 shows, a scraping plate 123 is connected to an edge of the slit nozzle 122, and the scraping plate 123 helps distribute the TIM fluid evenly across the substrate 13 immediately after the slit nozzle 122 sprays the TIM fluid onto the substrate 13. Next, in step S5, the TIM fluid flows and passes through the plurality of pores, and drops onto an outer surface of the battery cell B1 to form a TIM film on the outer surface of the battery cell B1.

[0052] In order to form a TIM film having a laterally-uniform thickness on the battery cell B1, the rotating mechanism 11 is driven to rotate the battery cell B1 at a rotation speed, and the rotation speed is negative correlation to a stickiness of the TIM fluid. In other words, the higher stickiness the TIM fluid has, the slower the battery cell B1 rotates. The rotation speed of the battery cell B1 can be determined by the formula *R=V, where R is the radius of the battery cell B1, is the angular velocity of the rotating mechanism, and V is the tangent speed.

[0053] In another embodiment, a slick layer is formed on the surface of the substrate, and the inner surface of each pore is also provided with the slick layer thereon. Therefore, the TIM fluid is allowed to pass the substrate 13 through the pores smoothly. Moreover, the slick layer comprises, in weight percent, 6-68% polymer and 5-40% inorganic material. The polymer can be poly (methyl methacrylate) (PMMA), polyamide (PA), polystyrene (PS), polyethylene (PE), polypropylene (PP), polyimide (PI), polyurethane (PU), polypyrrole (PPy), polylactic acid (PLA), fluorocarbon resin, epoxy resin, or a combination of any two or more of the foregoing. On the other hand, said inorganic material can be graphite particles, boron nitride particles, carbon black, activated carbon, fullerenes, graphene, or a combination of any two or more of the foregoing.

[0054] As shown in FIGS. 4-7 show, in the case that a coating fluid flow rate of a slit nozzle of the slot die coater 12, a rotation speed of the rotation mechanism 11, a thickness of the substrate 13, and a pore size of the substrate 13 all are properly designed, it is able to use the TIM coating system to form a TIM film comprising a laterally-uniform thickness on the cylindrical battery cell B1. After cylindrical battery cells B1 is coated with the TIM film, further assembly of the cylindrical battery cells B1 can form a battery module, and then at least one battery module and a battery management circuit are integrated to form a battery pack.

[0055] TIM fluid comprises a thermal interface material such as a polymer matrix and a plurality of thermal conductive filler distributed in the polymer matrix. According to the disclosures of the China patent, publication No. CN101351755A, the thermal conductive filler can be metal oxide particles, nitride particles, carbide particles, diboride particles, graphite particles, or metal particles. In addition, it can further mix a ceramic filler into the thermal interface material, and the ceramic filler can be alumina, magnesium oxide, zinc oxide, zirconium oxide, aluminum nitride, boron nitride, or silicon nitride. Moreover, it can also further mix a carbon-based filler into the thermal interface material, and the carbon-based filler can be graphite, graphene, silicon carbide, tungsten carbide, carbon nanotubes, graphite, carbon black.

[0056] As shown in FIGS. 4-7 show, a pressing plate 12P is disposed inside the reservoir 121, and a pressurizing apparatus 124 is adopted for supplying a pressing force to the pressing plate 12P, so as to push the pressing plate 12P at a given speed, thereby controlling a fluid supplying rate of the slit nozzle 122. In another embodiment, the pressurizing apparatus 124 can be pneumatic-type pressurizing apparatus, shown in FIG. 7, or a mechanical-type pressurizing apparatus. Moreover, a heating device 15 is connected to the reservoir 121 for heating the TIM fluid contained in the reservoir 121.

Second Example

[0057] In another embodiment, the method utilizes a moving mechanism, a slot die coater and an arc-shaped meshed plate to coat a thermal interface material (TIM) film on at least one battery cell. In other words, the method utilizes a TIM coating system comprising one moving mechanism, one slot die coater and one arc-shaped meshed plate to achieve coating a TIM film on at least one battery cell. With reference to FIG. 9, sectional view of the thermal interface material coating system for battery cells according to the present invention is provided. FIG. 10 shows the second flowchart of the thermal interface material coating method according to the present invention.

[0058] As shown in FIG. 9 and FIG. 10, the method firstly proceeds with step S1a to provide a moving mechanism 11a and a slot die coater 12, and then to fill a thermal interface material (TIM) fluid in a reservoir 121 of the slot die coater 12. Then, the method proceeds with step S2a for disposing at least one battery cell B2 on the moving mechanism 11a that is disposed below the slot die coater 12. In step S3a, a substrate 13 comprising a plurality of pores is provided, and is disposed between the battery cell B2 and the slot die coater 12. The substrate 13 comprises a thickness in a range between 0.05 mm and 100 mm, and the pore has a mesh size in a range between 10 mesh and 200 mesh.

[0059] The method subsequently proceeds with step S4a. In step S4a, the moving mechanism 11a is driven to move battery cell B2 along a horizontal direction, and the slot die coater 12 moves a slit nozzle 122 over the substrate 13 to spray the TIM fluid onto the substrate 13. As shown in FIG. 9, a scraping plate 123 connected to an edge of the slit nozzle 122, and the scraping plate 123 helps distribute the TIM fluid evenly across the substrate 13 immediately after the slit nozzle 122 sprays the TIM fluid onto the substrate 13. In addition, there is a slick layer formed on the surface of the substrate 13, and the inner surface of each pore is also provided with the slick layer thereon. Therefore the TIM fluid is allowed to pass the substrate 13 through the pores smoothly. In step S5a, the TIM fluid flows and passes through the plurality of pores, and then drops onto an outer surface of the battery cell B2, so as to form a TIM film on the outer surface of the battery cell B2.

[0060] It is worth mentioning that, when the moving mechanism 11a t moves battery cell B2 along the horizontal direction, the battery cell B2 horizontally move at a speed in a range between 1 cm/s and 30 cm/s. As explained in more detail below, the mathematical formula Q=A*V1=V2*t*W may be used to determine a suitable motion speed for the battery cell B2 and a coating weight for the TIM fluid, where Q is the coating weight, A is a cross-sectional area of the slit nozzle 122, V1 is the fluid supplying rate of the slit nozzle 122, V2 is the motion speed, t is a thickness of the TIM film formed on the battery cell B2, and W is a coating width. Therefore, when a coating fluid flow rate of a slit nozzle of the slot die coater, a moving speed of the battery cell B2, a thickness of the substrate 13, and a pore size of the substrate 13 all are properly designed, it is able to form a TIM film having a laterally-uniform thickness on the battery cell B2 by using the coating system.

[0061] As shown in FIG. 9, the battery cell B2 can be a prismatic battery cell or a pouch battery cell. After completing the TIM coating process, multiple battery cells B2 coated with the TIM film thereon can be further assembled to form a battery module, and then at least one battery module and a battery management circuit are integrated to form a battery pack.

[0062] TIM fluid comprises a thermal interface material, such as a polymer matrix and a plurality of thermal conductive filler distributed in the polymer matrix. According to the disclosures of the China patent, publication No. CN101351755A, the thermal conductive filler can be metal oxide particles, nitride particles, carbide particles, diboride particles, graphite particles, or metal particles. In addition, it can further mix a ceramic filler into the thermal interface material, and the ceramic filler can be alumina, magnesium oxide, zinc oxide, zirconium oxide, aluminum nitride, boron nitride, or silicon nitride. Moreover, it can also further mix a carbon-based filler into the thermal interface material, and the carbon-based filler can be graphite, graphene, silicon carbide, tungsten carbide, carbon nanotubes, graphite, carbon black.

[0063] Moreover, as shown in FIG. 9, a pressing plate 12P is disposed in the reservoir 121, and a pressurizing apparatus 124 is adopted for providing a pressing force to the pressing plate 12P to push the pressing plate 12P at a motion speed, thereby controlling a fluid supplying rate of the slit nozzle 122. In another embodiment, the pressurizing apparatus 124 can be an pneumatic-type pressurizing apparatus (as shown in FIG. 9) or a mechanical-type pressurizing apparatus. Moreover, a heating device 15 is connected to the reservoir 121 for heating the TIM fluid stored in the reservoir 121.

[0064] Therefore, through the above descriptions, all embodiments of the thermal interface material coating method for battery cells according to the present invention have been introduced completely and clearly. Moreover, the above description is made on embodiments of the present invention. However, the embodiments are not intended to limit the scope of the present invention, and all equivalent implementations or alterations within the spirit of the present invention still fall within the scope of the present invention.