Double-layer die head coating device for lithium ion battery

Abstract

The utility model relates to a double-layer die head coating device for a lithium ion battery, and relates to the technical field of lithium ion batteries. The device comprises an upper die cavity, a middle die cavity and a lower die cavity, and the lower die cavity and the middle die cavity are provided with independent feeding runners which are used for coating two different kinds of slurry on a base material at the same time. And through a double-layer coating technology, the problems of cracking, falling, edge effect and the like during coating of a single-layer die head are solved, and the energy density and the performance of the battery are improved.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a double-layer die coating device for lithium-ion batteries. Background Technology

[0002] The coating process is a crucial step in lithium-ion battery manufacturing, primarily aimed at applying active materials to the surfaces of the positive and negative electrode materials to enhance battery capacity and performance. However, the widely used single-layer die coating method encounters a series of problems when coating thick electrode sheets, such as cracking, peeling, and edge effects, which severely impact battery quality and performance. To address these issues, a novel coating device and technology are urgently needed.

[0003] The problems with single-layer die coating methods are primarily due to the limitations of their coating principle and structure. Specifically, single-layer dies can only use one type of slurry for coating, making it impossible to adjust the coating structure and performance as needed. Furthermore, single-layer dies cannot effectively control solvent evaporation and temperature gradients during the coating process, leading to problems such as cracking and peeling. In addition, single-layer dies cannot effectively suppress edge effects, further impacting battery performance and safety.

[0004] Therefore, based on the above problems, existing technologies need to be improved. Utility Model Content

[0005] The purpose of this application is to solve the problems in single-layer die coating and improve battery performance.

[0006] The above-mentioned technical objective of this application is achieved through the following technical solution: a double-layer die head coating device for lithium-ion batteries, comprising an upper die cavity, a middle die cavity and a lower die cavity, wherein the lower die cavity and the middle die cavity are provided with independent material supply channels for simultaneously coating the substrate with two different slurries.

[0007] By adopting the above technical solutions, the problems of cracking and peeling during single-layer die coating are solved, making the battery coating more stable and complete, thereby improving the overall performance and lifespan of the battery. It reduces battery performance degradation caused by edge issues, improving battery consistency and reliability. The coating structure and materials can be adjusted more flexibly to achieve higher energy density and increase battery range. Independent feed channels allow for the simultaneous coating of two different slurries, enriching coating possibilities and meeting diverse process requirements. The coating sequence and thickness of the two slurries can be precisely controlled as needed, improving coating accuracy and controllability.

[0008] Optionally, the feeding channel includes an upper manifold and a lower manifold. The upper manifold is located in the middle mold cavity and has an upper feed port. The lower manifold is located in the lower mold cavity and has a lower feed port.

[0009] By adopting the above technical solution, the independent setting of the upper and lower manifolds allows for the simultaneous and independent feeding of two different slurries, avoiding mutual interference and thus greatly improving coating efficiency. Continuous and stable feeding is achieved, reducing coating defects caused by feeding interruptions or instability. Independent feed inlets allow for precise control of the feeding speed and flow rate of each slurry, ensuring uniform distribution during coating and improving coating quality and consistency. It facilitates better control of coating thickness and composition to meet the performance requirements of different batteries. The feeding ratio and speed of the upper and lower slurries can be flexibly adjusted according to actual needs to adapt to different battery designs and production requirements. It also facilitates the replacement or adjustment of slurries with different properties during production to optimize battery performance.

[0010] Optionally, a first gasket is provided between the lower mold cavity and the middle mold cavity, and a second gasket is provided between the middle mold cavity and the upper mold cavity.

[0011] By adopting the above technical solution, the first and second gaskets can precisely define the distance between the lower mold cavity and the middle mold cavity, and between the middle mold cavity and the upper mold cavity, thereby effectively controlling the thickness of each coating layer and improving coating accuracy. This ensures consistent coating thickness and reduces battery performance differences caused by uneven thickness. The gaskets can also block and adjust slurry flow, reducing excessive or insufficient slurry accumulation at the edges, effectively suppressing edge effects, and making the coating edges neater and more uniform. A uniform and precise coating thickness contributes to the stable conduct of electrochemical reactions inside the battery, improving the battery's charge-discharge performance and cycle life.

[0012] Optionally, both the first gasket and the second gasket are made of stainless steel.

[0013] By adopting the above technical solutions, stainless steel exhibits excellent chemical corrosion resistance, remaining stable during long-term contact with various slurries and not easily corroded or damaged, thus extending the service life of the gaskets. This reduces gasket deformation or damage caused by corrosion, ensuring the stability and precision of the coating process. During frequent coating operations, stainless steel gaskets can withstand friction between mold cavities and slurry erosion, resisting wear and ensuring long-term dimensional and performance stability. This reduces the frequency of gasket replacement due to wear, decreasing equipment maintenance costs and downtime. The high strength of stainless steel effectively withstands the pressure during coating, maintaining the shape and position of the gasket, ensuring coating uniformity and precision. This helps maintain the structural stability of the coating equipment, improving overall equipment reliability. During coating, temperature changes may occur; stainless steel maintains its performance stability over a wide temperature range, unaffected by temperature-induced deformation or performance degradation.

[0014] Optionally, the width of the first gasket is greater than the width of the second gasket.

[0015] By adopting the above technical solution, the wider first pad can better control the distribution of the lower coating at the edges, reducing slurry accumulation or insufficiency at the edges, resulting in a smoother and more uniform lower coating edge. This helps suppress potential defects at the lower coating edge, such as cracks and peeling, improving battery reliability. When the upper coating is applied, the wider lower pad provides a more stable base, allowing the upper coating to adhere and distribute better, improving overall coating stability. The optimized coating edge structure can reduce the edge resistance of the battery during charging and discharging, improving the uniformity of current distribution, thereby enhancing battery performance and cycle life. It reduces the generation of defective products due to coating edge problems, increases production yield, and reduces production costs. Stable and optimized coating results help improve production efficiency and reduce the time spent adjusting and repairing coating defects.

[0016] Optionally, it also includes a coating roller, on which a conveying current collector is tensioned. The coating roller rotates at a uniform speed and drives the current collector to be conveyed at a uniform speed. During the conveying process, the first pad and the second pad are coated in sequence. After the first pad applies the lower coating layer to the current collector, the second pad applies the upper coating layer to the lower coating layer.

[0017] By adopting the above technical solution, the coating roller rotates at a uniform speed, driving the current collector to be conveyed at a uniform speed, which makes the coating of the slurry on the current collector more uniform and avoids local uneven thickness. This ensures the consistency of the coating of each batch of batteries, improving the overall performance and quality stability of the batteries. The continuous and stable conveying and coating process reduces downtime and adjustment time in production, greatly improving production efficiency. The first pad is coated with the lower coating layer, and the second pad is coated with the upper coating layer. This orderly coating method can precisely control the thickness and structure of each coating layer. It meets the specific requirements of different battery designs for the coating and optimizes battery performance. After the lower coating layer initially adheres to the current collector, the upper coating layer is applied immediately, which helps to enhance the adhesion between the two coating layers and between the coating layer and the current collector. This reduces the risk of coating peeling off during use and extends the battery's service life.

[0018] In summary, this application has at least the following beneficial effects:

[0019] 1. This application adopts a double-layer die head design, which can use two different slurries for coating at the same time, effectively solving the problems of cracking and peeling that occur when coating with a single-layer die head.

[0020] 2. In this application, stainless steel gaskets of different widths are preferably used. By adjusting the width of the gasket and the shape of the gasket outlet, the edge effect is suppressed, thereby further improving the performance and quality of the battery. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a double-layer die coating device for lithium-ion batteries.

[0022] Figure 2 This is a schematic diagram of the structure of the first gasket;

[0023] Figure Labels

[0024] 1. Upper mold cavity; 2. Second gasket; 3. Upper manifold; 4. Upper feed port; 5. Middle mold cavity; 6. First gasket; 7. Lower feed port; 8. Lower manifold; 9. Lower mold cavity; 10. Coating roller; 11. Upper coating layer; 12. Lower coating layer; 13. Current collector. Detailed Implementation

[0025] The present application will be further described in detail below with reference to the accompanying drawings.

[0026] In this embodiment, refer to Figure 1A dual-layer die coating apparatus for lithium-ion batteries includes an upper die cavity 1, a middle die cavity 5, and a lower die cavity 9. The lower die cavity 9 and the middle die cavity 5 are each equipped with independent feed channels to simultaneously coat the substrate with two different slurries. Specifically, the feed channels consist of an upper manifold 3 and a lower manifold 8. The upper manifold 3 is located within the middle die cavity 5 and is equipped with an upper feed inlet 4 for receiving and uniformly distributing the upper slurry; the lower manifold 8 is located within the lower die cavity 9 and is equipped with a lower feed inlet 7 for receiving and uniformly distributing the lower slurry.

[0027] During operation, the lower and upper slurries are continuously and quantitatively fed to the lower inlet 7 and upper inlet 4 through their respective feeding systems. Subsequently, the slurries are guided and pressure-divided via the upper manifold 3 or lower manifold 8 to ensure uniform coating on the current collector 13. The coating roller 10 rotates at a uniform speed, driving the current collector 13 to also be conveyed at a uniform speed. During this process, the lower coating layer 12 and the upper coating layer 11 are sequentially and uniformly coated onto the current collector 13.

[0028] The implementation principle of Example 1 is as follows: a double-layer die head design is used to achieve double-layer coating of the anode and cathode plates. The independent feeding channels ensure independent and uniform coating of the two slurries, thereby solving the problems encountered by single-layer dies when coating thick plates, such as cracking and peeling. At the same time, the double-layer structure design improves the energy density and performance of the battery.

[0029] Example 2

[0030] The difference in this embodiment is that a first gasket 6 and a second gasket 2 are respectively provided between the lower mold cavity 9 and the middle mold cavity 5, and between the middle mold cavity 5 and the upper mold cavity 1, and the width of the first gasket 6 is greater than the width of the second gasket 2. This design aims to suppress edge effects that may occur during the coating process. By adjusting the width of the gaskets, the coating width can be changed, thereby reducing the accumulation of slurry at the edges and making the coating more uniform.

[0031] Implementation principle: By adjusting the widths of the first pad 6 and the second pad 2, precise control over the widths of the lower and upper coating layers is achieved. A lower coating width wider than the upper layer helps reduce the adverse effects of edge effects on battery performance. Simultaneously, the pads also protect the die head and adjust the shape of the coating edges, further improving coating quality and battery performance.

[0032] Example 3

[0033] Based on Example 1 or Example 2, this example further illustrates a preferred option for the gasket material. Specifically, both the first gasket 6 and the second gasket 2 are made of stainless steel. Stainless steel has good corrosion resistance and wear resistance, ensuring the long-term stable use of the gasket. At the same time, stainless steel has moderate hardness, which will not damage the die head.

[0034] Implementation principle: Stainless steel gaskets not only ensure precise control of coating width, but also provide a stable coating environment, reducing the frequency of equipment maintenance and replacement, thereby reducing production costs.

[0035] Example 4

[0036] Based on Example 1, Example 2, or Example 3, this example describes in detail the selection and formulation of the slurry during the coating process. Specifically, the lower layer slurry can be formulated with a high solids content and easily volatile solvents, while the upper layer slurry uses a formula with a low solids content and difficult-to-evaporate solvents.

[0037] Implementation Principle: By rationally adjusting the ratio and properties of the upper and lower slurries, the coating advantages of a double-layer die can be fully utilized. The lower slurry evaporates rapidly, forming a stable underlying structure, while the solvent in the upper slurry evaporates more slowly, reducing cracking caused by excessively rapid surface drying. This design also effectively reduces the temperature difference between the upper and lower coatings, decreases binder buoyancy, and improves coating adhesion strength, thereby enhancing battery performance.

[0038] Example 5

[0039] Building upon Example 4, this example further illustrates how to optimize the coating effect by adjusting the gasket shape. For instance, different gasket outlet shapes, such as arc-shaped, serrated, or other non-linear shapes, can be used to change the distribution of the slurry on the current collector 13, thereby further optimizing the uniformity and adhesion of the coating.

[0040] Implementation principle: By changing the shape of the gasket outlet, the flow and distribution of the slurry during the coating process can be controlled, thereby reducing coating unevenness and improving coating quality and battery performance. This method is particularly suitable for applications requiring high-precision coating.

[0041] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A double-layer die coater for a lithium ion battery, characterized by comprising: The application relates to a coating device for coating a substrate with two different slurries, comprising an upper die cavity (1), a middle die cavity (5) and a lower die cavity (9), wherein the lower die cavity (9) and the middle die cavity (5) are provided with independent feeding channels for simultaneously coating the substrate with two different slurries; a first gasket (6) is arranged between the lower die cavity (9) and the middle die cavity (5), and a second gasket (2) is arranged between the middle die cavity (5) and the upper die cavity (1).

2. The double-layer die coater for a lithium-ion battery according to claim 1, wherein The feeding channels comprise an upper manifold (3) and a lower manifold (8), the upper manifold (3) is arranged in the middle die cavity (5), the upper manifold (3) is provided with an upper feeding port (4), the lower manifold (8) is arranged in the lower die cavity (9), and the lower manifold (8) is provided with a lower feeding port (7).

3. The double-layer die coater for a lithium ion battery according to claim 1, wherein The first gasket (6) and the second gasket (2) are both made of stainless steel.

4. The double-layer die coater for a lithium ion battery according to claim 1, wherein The width of the first gasket (6) is greater than that of the second gasket (2).

5. The double-layer die coater for a lithium-ion battery according to claim 1, wherein The coating device further comprises a coating roller (10), the coating roller (10) can be used to tension and transmit a current collector (13), the coating roller (10) rotates at a uniform speed and drives the current collector (13) to be uniformly transported, the first gasket (6) and the second gasket (2) are sequentially coated in the transportation process, the first gasket (6) coats a lower coating layer (12) on the current collector (13), and the second gasket (2) coats an upper coating layer (11) on the lower coating layer (12).

Images