An electrode sheet, its coating method, and a battery

Abstract

This invention discloses an electrode sheet, its coating method, and a battery. The electrode sheet includes a current collector and a slurry coating applied to the current collector. The slurry coating includes a heat-insulating material coating and an aqueous slurry coating. The aqueous slurry coating is applied to the current collector and covers the heat-insulating material coating. The coating method is as follows: S1: Design the slurry coating area on the current collector according to process specifications. The width of the aqueous slurry coating is w, and the heat-insulating material coating is placed on both sides of the slurry coating with a coating width of n; S2: Uniformly coat the heat-insulating material onto the heat-insulating coating area designed in step S1, with a coating thickness of h, and heat-dry; S3: Uniformly coat the aqueous slurry onto the aqueous slurry coating area designed in step S1, with a coating thickness of H, and bake, thus completing the coating of the electrode sheet. The coating method of this invention can reduce heat conduction at the edges of the coating layer, thereby solving the problem of edge curling and cracking caused by rapid drying of the edges of the aqueous electrode sheet.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to an electrode sheet, its coating method, and a battery. Background Technology

[0002] With the booming development of the energy storage, electric vehicle, and portable electronics markets, and the increasing demands for sustainable development and environmental protection, higher requirements are being placed on the storage technologies for emerging energy sources. Currently, lithium-ion batteries, which use transition metal oxides as positive electrodes and graphite as negative electrodes, and sodium-ion batteries, an emerging energy storage technology, have broad application prospects in various aspects of life.

[0003] However, sodium-ion batteries use N-methylpyrrolidone as a solvent in their manufacturing process. This organic solvent is costly, pollutes the environment, and harms human health, failing to meet the requirements of environmentally friendly development. Therefore, the development of aqueous electrodes has become a hot topic in the current development of lithium / sodium-ion batteries, and there is an urgent need to explore and develop mature and stable aqueous electrode processes.

[0004] Currently, there are literature reports on aqueous slurry processes for lithium / sodium-ion batteries. However, during the coating process, due to factors such as the lower boiling point of water compared to the oil-based solvent N-methylpyrrolidone and uneven heating of the electrode, the edges of the aqueous slurry evaporate and dry much faster than the central area, causing problems such as coating and baking edge curling and cracking. Some literature reports address these issues by using slurry additives; however, even with improvements, these problems still occur during the coating process.

[0005] Therefore, there is an urgent need to develop a new water-based electrode coating process to solve the problems of edge cracking and baking curling caused by water-based slurry in the coating process. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing an electrode sheet that improves the problems of edge curling and cracking during the coating process of aqueous slurry by coating the two edges of the current collector coating area with heat insulation material, thereby enhancing the applicability of aqueous electrode sheet technology in the manufacture of lithium / sodium ion batteries.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The present invention provides an electrode sheet comprising a current collector and a slurry coating coated on the current collector, the slurry coating comprising a thermal insulation material coating and an aqueous slurry coating, the aqueous slurry coating being coated on the current collector and covering the thermal insulation material coating.

[0009] Preferably, the width n of the thermal insulation material coating and the width w of the water-based slurry coating satisfy the following relationship: n = 0.05 ~ 0.2w.

[0010] Preferably, the heat insulation material is at least one of acrylic resin, polyurethane resin, and polyamide resin.

[0011] Preferably, the coating method of the heat insulation material and the water-based slurry is at least one of continuous coating and intermittent coating.

[0012] Preferably, the thickness H of the water-based slurry coating and the thickness h of the thermal insulation material coating satisfy the following relationship: h = 0.03 ~ 0.14H.

[0013] Preferably, the width n of the heat insulation material coating is 1 to 20 mm.

[0014] Preferably, the thickness h of the heat insulation material coating is 1 to 10 μm.

[0015] The present invention also provides a coating method for the above-mentioned electrode sheet, comprising the following steps:

[0016] S1: Design the slurry coating area of ​​the current collector according to the process specifications. The width of the water-based slurry coating is w, and the thermal insulation material coating is set on both sides of the slurry coating with a coating width of n.

[0017] S2: Apply the heat insulation material evenly to the heat insulation coating area designed in step S1, with a coating thickness of h, and then heat and dry it.

[0018] S3: Apply the aqueous slurry evenly to the aqueous slurry coating area designed in step S1, with a coating thickness of H, and perform a baking process to complete the coating of the electrode sheet.

[0019] Preferably, in step S1, the width n of the heat insulation material coating is 1 to 20 mm.

[0020] Preferably, in step S2, the thickness h of the heat-insulating coating is 1 to 10 μm.

[0021] The present invention also provides a battery comprising a positive electrode, a negative electrode, and a separator spaced between the positive electrode and the negative electrode, wherein the positive electrode and / or the negative electrode are the electrode sheets described above.

[0022] The beneficial effects of this invention are as follows: This invention provides an electrode sheet that solves the problems of edge curling and cracking during the coating process by coating both sides of the slurry coating area with a heat-insulating material coating. The coating method of this invention can reduce the heat conduction at the edge of the coating layer, thereby solving the problem of edge curling and cracking caused by rapid drying of the edge of the aqueous electrode sheet. This coating method is simple to operate, highly practical, and has a more significant improvement effect than existing slurry additive solutions. It is not affected by the operating environment, and the improved aqueous slurry coating process can provide solutions and process support for optimizing the lithium / sodium ion battery manufacturing process, thereby improving the overall application performance of aqueous electrodes for lithium / sodium ion batteries. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the coating process of an electrode sheet according to an embodiment of the present invention.

[0024] Among them, 1-current collector, 2-slurry coating, 21-thermal insulation material coating, 22-water-based slurry coating, n-width of thermal insulation material coating, and w-width of water-based slurry coating. Detailed Implementation

[0025] To make the technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] According to a first aspect of the present invention, an electrode sheet is provided, comprising a current collector and a slurry coating coated on the current collector, the slurry coating comprising a thermal insulation material coating and an aqueous slurry coating, the aqueous slurry coating being coated on the current collector and covering the thermal insulation material coating.

[0027] In one embodiment of the present invention, the width n of the heat insulation material coating and the width w of the water-based slurry coating satisfy the following relationship: n = 0.05~0.2w, preferably n = 0.1~0.15w. The reason for satisfying this relationship is that during the coating process, when the water-based slurry is applied to the current collector, the edges are heated more than the center, and because the boiling point of water in the water-based slurry is lower than that of oil-based solvents, the evaporation rate is faster, easily causing problems such as edge curling and cracking during baking. Therefore, when the coating widths satisfy the above relationship, the problems of edge curling and cracking during electrode baking can be effectively solved.

[0028] In one embodiment of the present invention, the heat insulation material is at least one of acrylic resin, polyurethane resin, and polyamide resin.

[0029] In one embodiment of the present invention, the coating method of the thermal insulation material and the water-based slurry is at least one of continuous coating and intermittent coating.

[0030] In one embodiment of the present invention, the thickness H of the aqueous slurry coating and the thickness h of the heat insulation material coating satisfy the following relationship: h = 0.03 to 0.14H, preferably h = 0.06 to 0.10H. When the thickness of the aqueous slurry coating and the thickness of the heat insulation material coating satisfy the above relationship, the heat conduction at the edge of the coating layer can be reduced, thereby solving the problem of edge curling and cracking caused by rapid drying of the electrode sheet edge.

[0031] In one embodiment of the present invention, the width n of the heat insulation material coating is 1 to 20 mm, specifically 1 mm, 3 mm, 5 mm, 7 mm, 9 mm, 10 mm, 12 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, or 20 mm. The width of the coating is controlled within the above range because setting the width of the coating too large is not conducive to electron conduction and affects the dynamic performance of the battery cell.

[0032] In one embodiment of the present invention, the thickness h of the heat insulation material coating is 1 to 10 μm, specifically 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. The thickness of the coating is controlled within the above range because if the thickness is too large, the compaction density of the coating area at the edge of the electrode will differ significantly from that outside the area, affecting the performance of the battery cell; if the thickness is too small, the heat insulation effect will be too poor.

[0033] According to a second aspect of the present invention, the present invention also provides a coating method for the above-mentioned electrode sheet, comprising the following steps:

[0034] S1: Design the slurry coating area of ​​the current collector according to the process specifications. The width of the water-based slurry coating is w, and the thermal insulation material coating is set on both sides of the slurry coating with a coating width of n.

[0035] S2: Apply the heat insulation material evenly to the heat insulation coating area designed in step S1, with a coating thickness of h, and then heat and dry it.

[0036] S3: Apply the aqueous slurry evenly to the aqueous slurry coating area designed in step S1, with a coating thickness of H, and perform a baking process to complete the coating of the electrode sheet.

[0037] In one embodiment of the present invention, in step S1, the width n of the heat insulation material coating is 1 to 20 mm, specifically 1 mm, 3 mm, 5 mm, 7 mm, 9 mm, 10 mm, 12 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, or 20 mm. Within the above range, the electron conduction ability and cell dynamic performance in the electrode are the best.

[0038] In one embodiment of the present invention, in step S2, the thickness h of the heat insulation coating is 1 to 10 μm, specifically 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. Within the above range, the cell performance and heat insulation effect are the best.

[0039] According to a third aspect of the present invention, the present invention also provides a battery comprising a positive electrode, a negative electrode, and a separator spaced between the positive electrode and the negative electrode, wherein the positive electrode and / or the negative electrode is an electrode sheet as described above.

[0040] The present invention will be further described below through specific embodiments.

[0041] Example 1

[0042] like Figure 1 As shown in the diagram, this embodiment provides a schematic diagram of an electrode sheet coating process, including a current collector 1 and a slurry coating 2 coated on the current collector 1. The slurry coating 2 includes a heat-insulating material coating 21 and an aqueous slurry coating 22. The aqueous slurry coating 22 is coated on the current collector 1 and covers the heat-insulating material coating 21. The specific coating method steps are as follows:

[0043] S1: Design the slurry coating area for the current collector according to the process specifications. The width of the water-based slurry coating is w = 100 mm. The thermal insulation material coating is set on both sides of the slurry coating, and the coating width is n = 15 mm.

[0044] S2: Apply the heat insulation material evenly to the heat insulation coating area designed in step S1, with a coating thickness of h = 2 μm, and then heat and dry it.

[0045] S3: Apply the water-based slurry evenly to the water-based slurry coating area designed in step S1, with a coating thickness of H = 20 μm, and then perform a baking process to complete the coating of the electrode sheet.

[0046] During the coating process, in this embodiment, after the heat insulation material coating and the water-based slurry coating are applied to the current collector as required and then baked, no cracking or curling occurs at the edges of the water-based slurry coating.

[0047] Example 2

[0048] The difference between this embodiment and Embodiment 1 is that the size and thickness of the coating areas for each material are different when coating the electrode sheet. The specific coating method steps are as follows:

[0049] S1: Design the slurry coating area of ​​the current collector according to the process specifications. The width of the water-based slurry coating is w = 120 mm. The heat insulation material coating is set on both sides of the slurry coating, and the coating width is n = 12 mm.

[0050] S2: Apply the heat insulation material evenly to the heat insulation coating area designed in step S1, with a coating thickness of h = 4 μm, and then heat and dry it.

[0051] S3: Apply the water-based slurry evenly to the water-based slurry coating area designed in step S1, with a coating thickness of H = 50 μm, and then perform a baking process to complete the coating of the electrode sheet.

[0052] During the coating process, in this embodiment, after the heat insulation material coating and the water-based slurry coating are applied to the current collector as required and then baked, no cracking or curling occurs at the edges of the water-based slurry coating.

[0053] Comparative Example 1

[0054] The difference between this comparative example and Example 1 is that the slurry coating in this comparative example is coated only with an aqueous slurry coating.

[0055] During the coating process, when the water-based slurry coating was directly applied to the current collector as required and then baked, the edges of the water-based slurry coating cracked and curled severely.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Comparative Example 1 is that additives are added to the water-based slurry coating in this comparative example.

[0058] During the coating process, when the water-based slurry coating containing additives was directly applied to the current collector and then baked as required, slight cracking and curling appeared at the edges of the water-based slurry coating containing additives.

[0059] In the comparative examples described above, different coating methods resulted in varying degrees of cracking and curling at the edges of the aqueous slurry coating during electrode baking. However, when the method of this invention was used, no cracking or curling occurred at the edges of the aqueous slurry coating. This is because the coating edges are heated more than the center, and because the boiling point of water in the aqueous slurry is lower than that of oil-based solvents, the evaporation rate is faster, easily causing edge curling and cracking during baking. This invention improves the coating process by adding a layer of heat-insulating material. By applying a layer of heat-insulating material to the edge of the designed coating width on the current collector, the thermal conductivity of the coating layer at the edge is reduced, ensuring that the drying rate of the edge slurry layer is consistent with the surrounding area. This reduces the solvent evaporation rate and minimizes edge curling and cracking problems during electrode baking.

[0060] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. An electrode sheet, characterized in that, The device includes a current collector and a slurry coating applied to the current collector. The slurry coating includes a thermal insulation material coating and an aqueous slurry coating. The aqueous slurry coating is applied to the current collector and covers the thermal insulation material coating. In the width direction of the current collector, the width of the water-based slurry coating is w, and the thermal insulation material coating is disposed on both sides of the water-based slurry coating, with the width of the thermal insulation material coating on each side being n. The water-based slurry coating is located in the middle of the current collector, and the width n of the thermal insulation material coating and the width w of the water-based slurry coating satisfy the relationship: n = 0.05~0.2w; the thermal insulation material is at least one of acrylic resin, polyurethane resin, and polyamide resin; the thickness H of the water-based slurry coating and the thickness h of the thermal insulation material coating satisfy the relationship: h = 0.03~0.14H; the width n of the thermal insulation material coating is 1~20mm; and the thickness h of the thermal insulation material coating is 1~10μm.

2. The electrode sheet according to claim 1, characterized in that, The coating method for the thermal insulation material and the water-based slurry is at least one of continuous coating and intermittent coating.

3. A coating method for an electrode sheet according to any one of claims 1 to 2, characterized in that, The process includes the following steps: S1: Design the slurry coating area for the current collector according to the process specifications. The width of the water-based slurry coating is w, and the heat insulation material coating is placed on both sides of the slurry coating with a coating width of n; S2: Apply the heat insulation material evenly to the heat insulation coating area designed in step S1 with a coating thickness of h, and then heat and dry it; S3: Apply the water-based slurry evenly to the water-based slurry coating area designed in step S1 with a coating thickness of H, and then perform a baking process to complete the coating of the electrode sheet.

4. A battery comprising a positive electrode, a negative electrode, and a separator spaced between the positive electrode and the negative electrode, characterized in that, The positive electrode and / or the negative electrode are the electrode sheets according to any one of claims 1 to 2.

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