Composite diaphragm and single battery
By designing a ceramic layer, a roller-coated modified coating, and a spray-coated modified coating on the composite separator of lithium-ion batteries, the interface problem caused by negative electrode expansion was solved, and the electrolyte retention capacity and cycle life of the battery were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2026-03-06
AI Technical Summary
During the cycling process, the pressure at the corners of lithium-ion batteries increases due to the expansion of the negative electrode material, causing interface problems that affect battery cycle life and safety, and also reduce the liquid retention rate of the separator.
A composite diaphragm is used, including a base membrane and a ceramic layer, a roller-coated modified coating, and a spray-coated modified coating on the surface of the base membrane. The coating design can store electrolyte and provide expansion space, improving adhesion and compressibility.
It enhances the electrolyte retention capacity of the battery, avoids interface problems of the electrode plates, and improves the cycle life and safety of the battery.
Smart Images
Figure CN223978039U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of battery manufacturing technology, and in particular to a composite separator and a single battery cell. Background Technology
[0002] Lithium-ion rechargeable batteries use graphite or silicon-based materials as the negative electrode. Lithium ions extracted from the positive electrode embed into the graphite or silicon-based material structure, causing both materials to expand in volume, with silicon-based materials experiencing expansion rates up to 300%. As cycling progresses, the expansion of both the negative electrode and the battery increases. Because the pressure at the corners of a wound-structure lithium-ion battery is greater than at the flat surfaces, the expansion space of the negative electrode material is limited at these locations, and the electrolyte content is also lower. With continued cycling, the electrolyte at the corners is continuously consumed, and the expansion volume of the negative electrode material itself gradually increases, leading to increasing pressure at the corners. This causes interface problems such as purple spots, black spots, and lithium plating at the negative electrode interface, affecting the battery's cycle life and safety.
[0003] The separator is a key component of lithium-ion batteries. Its unique microporous structure allows ions to pass through while isolating electrons, thus enabling the charging and discharging of lithium-ion batteries. To mitigate the increased internal pressure caused by silicon expansion and to address the issue of decreased electrolyte retention, the separator needs to possess both good electrolyte wettability and electrolyte retention properties to improve battery life.
[0004] Therefore, there is an urgent need to provide a new type of composite separator and single cell to solve the above-mentioned technical problems in the prior art. Utility Model Content
[0005] One objective of this invention is to provide a composite separator that can ensure good adhesion and compressibility while increasing the liquid retention of individual cells and improving their cycle life.
[0006] To achieve this objective, the present invention adopts the following technical solution:
[0007] The composite membrane includes a base membrane and a first coating disposed on a first surface of the base membrane. The first coating includes a first ceramic layer, a first roll-coated modified coating, and a first spray-coated modified coating. The first roll-coated modified coating is sandwiched between the first ceramic layer and the first spray-coated modified coating. The first ceramic layer is covered on the first surface. Both the first spray-coated modified coating and the first roll-coated modified coating are capable of storing electrolyte.
[0008] Optionally, the second surface of the base film is provided with a second coating, which is capable of storing electrolyte.
[0009] Optionally, the coating method for the second coating may include any one or a combination of at least two of gravure roller coating, micro-gravure roller coating, spraying, or intermittent coating.
[0010] Optionally, the second coating may include a second spray-modified coating or a second roll-coated modified coating; or, the second coating may include the second spray-modified coating and the second roll-coated modified coating, wherein the second roll-coated modified coating is sandwiched between the second surface and the second spray-modified coating.
[0011] Optionally, a second ceramic layer may be sandwiched between the second coating and the second surface.
[0012] Optionally, both the first ceramic layer and the second ceramic layer comprise inorganic ceramic particles, which include any one or a combination of at least two of boehmite, alumina, magnesium hydroxide, magnesium oxide, titanium dioxide, silicon dioxide, barium titanate, zinc oxide, nickel oxide, magnesium fluoride, zirconium oxide, cerium oxide, or barium sulfate, and the particle size of the inorganic ceramic particles is from 0.01 μm to 2 μm.
[0013] Optionally, the coating thickness of the first spray-modified coating and the second spray-modified coating is 3 μm to 6 μm, and the forming thickness after hot pressing is 1.5 μm to 3 μm.
[0014] Optionally, the roll coating thickness of the first and second roll coating modified coatings is 0.5 μm to 3 μm, and the forming thickness after hot pressing is 0.2 μm to 1.5 μm.
[0015] Optionally, the first spray-coated modified coating, the first roller-coated modified coating, the second spray-coated modified coating, and the second roller-coated modified coating may each include an inorganic modified coating, an organic modified coating, or a mixed modified coating.
[0016] Optionally, the active substances in both the first and second spray-modified coatings are distributed in an island-like pattern.
[0017] Another objective of this invention is to provide a single-cell battery comprising a composite separator as described in any of the above embodiments.
[0018] Beneficial effects:
[0019] The composite separator of this invention forms a first coating on the first surface of the base film by coating a first ceramic layer onto a base film, followed by roller coating a first roller-coated modified coating onto the first ceramic layer, and finally spray coating a first spray modified coating onto the first roller-coated modified coating. Because the first surface of the base film of this composite separator is sequentially formed with the first ceramic layer, the first roller-coated modified coating, and the first spray modified coating, the high liquid absorption capacity of the first ceramic layer allows for maximum electrolyte adsorption. Simultaneously, the first roller-coated modified coating has a larger coverage area, better adhesion, and a denser coating, improving the adhesion of the first coating and preventing material shedding. Furthermore, the loose surface of the first spray modified coating makes it easily compressible, providing space for electrode expansion and preventing interface problems such as purple spots, black spots, and lithium plating on the electrodes. It also stores more electrolyte, which is beneficial for improving battery cycle life. This composite separator ensures good adhesion and compressibility while increasing the electrolyte retention capacity of individual cells, thus improving the cycle life of individual cells. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the composite diaphragm in Embodiment 1 of the present utility model.
[0021] Figure 2 This is a schematic diagram of the composite diaphragm in Embodiment 2 provided by a specific embodiment of this utility model;
[0022] Figure 3 This is a schematic diagram of the composite diaphragm in Embodiment 3 of the present invention.
[0023] Figure 4 This is a schematic diagram of the composite diaphragm in Embodiment 4 of the present invention.
[0024] In the picture:
[0025] 10. Base film; 20. First coating layer; 21. First ceramic layer; 22. First roller-coated modified coating layer; 23. First spray-coated modified coating layer; 30. Second coating layer; 31. Second spray-coated modified coating layer; 32. Second roller-coated modified coating layer; 33. Second ceramic layer. Detailed Implementation
[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.
[0027] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0029] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.
[0030] Please refer to Figures 1 to 4 In this embodiment, the composite diaphragm includes a base membrane 10 and a first coating 20 disposed on the first surface of the base membrane 10. The first coating 20 includes a first ceramic layer 21, a first roller-coated modified coating 22, and a first spray-coated modified coating 23. The first roller-coated modified coating 22 is sandwiched between the first ceramic layer 21 and the first spray-coated modified coating 23. The first ceramic layer 21 is covered on the first surface. Both the first spray-coated modified coating 23 and the first roller-coated modified coating 22 are capable of storing electrolyte.
[0031] In this embodiment, the composite separator is formed by coating a first ceramic layer 21 onto a base film 10, followed by roller coating a first roller-coated modified coating 22 onto the first ceramic layer 21, and finally spraying a first spray-coated modified coating 23 onto the first roller-coated modified coating 22, thereby forming a first coating 20 on the first surface of the base film 10. Because the first ceramic layer 21, the first roller-coated modified coating 22, and the first spray-coated modified coating 23 are sequentially disposed on the first surface of the base film 10 of this composite separator, the high liquid absorption performance of the first ceramic layer 21 allows it to absorb as much electrolyte as possible. Simultaneously, the first roller-coated modified coating 22 has a larger coverage area, better adhesion, and a denser coating, which improves the adhesion of the first coating 20 and prevents material loss. Furthermore, the loose surface of the first spray-coated modified coating 23 makes it easily compressible, providing space for electrode expansion and preventing interface problems such as purple spots, black spots, and lithium plating on the electrodes. It also stores more electrolyte, which is beneficial for improving battery cycle life. This composite separator can ensure good adhesion and compressibility, while also increasing the electrolyte retention of individual cells and improving their cycle life.
[0032] Furthermore, a second coating 30 is provided on the second surface of the base membrane 10, and the second coating 30 is capable of storing electrolyte. The presence of coatings for storing electrolyte on both the first and second surfaces of the base membrane 10 further increases the electrolyte storage capacity of the composite separator and improves the cycle life of the individual battery.
[0033] It should be noted that the coating method for the second coating 30 mentioned above includes any one or a combination of at least two of gravure roller coating, micro-gravure roller coating, spray coating, or intermittent coating. In this embodiment, the coating method used is determined by the model of the individual battery, the usage environment, and its size, which will not be elaborated here.
[0034] This embodiment also provides a single-cell battery, which includes the composite separator described in any of the embodiments herein. Specifically, the single-cell battery can be a nickel-metal hydride battery, a nickel-cadmium battery, a lead-acid (or lead-acid) battery, a lithium-ion battery, a polymer lithium-ion battery, etc. The single-cell battery can also be a primary lithium-ion battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery, or a magnesium-ion battery, etc., which will not be elaborated here. This single-cell battery has the beneficial effects of the battery cover described in any of the above embodiments, which will not be elaborated here.
[0035] Specifically, when the composite separator is used in this single-cell battery, while ensuring the adhesion performance of the first coating 20, it not only provides space for the expansion of the electrode, avoiding interface problems such as purple spots, black spots, and lithium plating on the electrode, but also stores more electrolyte, which is beneficial to improving the battery's cycle life. The composite separator used in this single-cell battery can ensure good adhesion and compressibility, while increasing the electrolyte retention capacity of the single-cell battery and improving its cycle life.
[0036] Example 1
[0037] Specifically, such as Figure 1 As shown, the second coating 30 in this embodiment includes the second spray-coated modified coating 31 and the second roll-coated modified coating 32, with the second roll-coated modified coating 32 sandwiched between the second surface and the second spray-coated modified coating 31. The second coating 30, through the second roll-coated modified coating 32, increases adhesion and coating density, improving the adhesion effect of the second coating 30 and preventing material loss. Furthermore, the second spray-coated modified coating 31 improves the compressibility of the second coating 30, providing greater space for electrode expansion and storing more electrolyte, thus improving battery cycle life.
[0038] Furthermore, a second ceramic layer 33 is sandwiched between the second coating 30 and the second surface. The second ceramic layer 33 can provide the second coating 30 with higher liquid absorption performance, and can adsorb as much electrolyte as possible, thereby increasing the electrolyte storage capacity of the second coating 30 and the composite separator, and thus improving the cycle performance of the single cell.
[0039] In this embodiment, both the first ceramic layer 21 and the second ceramic layer 33 contain inorganic ceramic particles. These inorganic ceramic particles include any one or a combination of at least two of the following: boehmite, alumina, magnesium hydroxide, magnesium oxide, titanium dioxide, silicon dioxide, barium titanate, zinc oxide, nickel oxide, magnesium fluoride, zirconium oxide, cerium oxide, or barium sulfate. The particle size of these inorganic ceramic particles is 0.01 μm to 2 μm. Coating the surface of the base membrane 10 with the first ceramic layer 21 and the second ceramic layer 33 can effectively improve the thermal stability, shrinkage, and liquid absorption of the composite separator, thereby enhancing the safety and electrochemical performance of the individual battery. In this embodiment, the inorganic ceramic particles in the first ceramic layer 21 and the second ceramic layer 33 are boehmite, and the inorganic ceramic particles are a mixture of particles with varying sizes, providing a low-density, high-porosity ceramic coating that improves the liquid absorption rate of the composite separator.
[0040] Furthermore, the coating thickness of the first spray-modified coating 23 and the second spray-modified coating 31 is 3μm to 6μm, and the forming thickness after hot pressing is 1.5μm to 3μm. Because the first spray-modified coating 23 and the second spray-modified coating 31 need to allow more space for the expansion of the electrode sheet, they need to be made relatively thick. After hot pressing, their thickness will decrease by 50%, becoming half of the coating thickness, which will not be elaborated further here.
[0041] Preferably, the roll coating thickness of the first roll-coated modified coating 22 and the second roll-coated modified coating 32 is 0.5 μm to 3 μm, and the forming thickness after hot pressing is 0.2 μm to 1.5 μm. Since the thickness change of the first roll-coated modified coating 22 and the second roll-coated modified coating 32 is small after compression, no space needs to be reserved for negative electrode expansion. Therefore, the thickness after roll coating is small, and after hot pressing, its thickness will decrease by 50%, becoming half of the roll coating thickness. Further details are omitted here.
[0042] It should be noted that the aforementioned first spray-coated modified coating 23, first roller-coated modified coating 22, second spray-coated modified coating 31, and second roller-coated modified coating 32 respectively include inorganic modified coatings, organic modified coatings, or mixed modified coatings. Inorganic modified coatings include zirconia coatings, alumina coatings, or boehmite coatings; organic modified coatings include PVDF coatings or PMMA coatings; and mixed modified coatings include PVDF mixed with ceramic fillers (silica, titanium dioxide, alumina, zirconia, etc.) and PVDF mixed with other organic polymer matrices (such as PAN, PMMA, PEO-b-PMMA, HTPB-g-MPEG), which will not be elaborated here.
[0043] Specifically, the active materials in both the first spray-modified coating 23 and the second spray-modified coating 31 are distributed in an island-like pattern. The loose, island-like surface of the first and second spray-modified coatings makes them easier to compress, providing greater space for electrode expansion and storing more electrolyte, thus improving battery cycle life.
[0044] Example 2
[0045] Please refer to Figure 2 The only difference from Embodiment 1 is that the second coating 30 in Embodiment 2 includes a second roll-coated modified coating 32. Furthermore, a second ceramic coating is also provided between the second roll-coated modified coating 32 and the base film 10. Compared to Embodiment 1, by omitting the second spray-coated modified coating 31, production costs can be reduced while ensuring the liquid retention and adhesion properties of the composite diaphragm; however, the compressibility is lower, which will not be elaborated here.
[0046] Example 3
[0047] Please refer to Figure 3 The only difference from Example 2 is that the second ceramic coating is omitted in Example 3. This reduces the production cost while ensuring the bonding performance of the composite diaphragm. However, the electrolyte storage capacity is reduced compared to the composite diaphragm in Example 2, which will not be elaborated here.
[0048] Example 4
[0049] Please refer to Figure 4 The only difference from Example 3 is that the second coating 30 in Example 4 is changed from including only the second roller-coated modified coating 32 to including only the second spray-coated modified coating 31. Compared with the composite diaphragm in Example 3, its electrolyte storage capacity is increased, but the adhesion performance of the second coating 30 is reduced, which will not be described in detail here.
[0050] Those skilled in the art can select the structure of the composite separator in Examples 1 to 4 according to specific needs, such as the performance requirements and production cost requirements of a single battery cell, which will not be elaborated here.
[0051] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make various obvious changes, readjustments, and substitutions without departing from the protection scope of this utility model. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.
Claims
1. A composite separator, characterized by, The base film (10) and a first coating layer (20) disposed on a first surface of the base film (10), the first coating layer (20) comprising a first ceramic layer (21), a first roll-coated modification coating layer (22) and a first spray-coated modification coating layer (23), the first roll-coated modification coating layer (22) being sandwiched between the first ceramic layer (21) and the first spray-coated modification coating layer (23), the first ceramic layer (21) being disposed on the first surface, and the first spray-coated modification coating layer (23) and the first roll-coated modification coating layer (22) being capable of storing electrolyte.
2. The composite separator of claim 1, wherein A second surface of the base film (10) is provided with a second coating layer (30) capable of storing electrolyte.
3. The composite separator of claim 2, wherein, The coating method of the second coating layer (30) comprises any one or a combination of at least two of gravure roll coating, microgravure roll coating, spray coating or intermittent coating.
4. The composite separator of claim 3, wherein The second coating layer (30) comprises a second spray-coated modification coating layer (31) or a second roll-coated modification coating layer (32); or the second coating layer (30) comprises the second spray-coated modification coating layer (31) and the second roll-coated modification coating layer (32), the second roll-coated modification coating layer (32) being sandwiched between the second surface and the second spray-coated modification coating layer (31).
5. The composite separator of claim 4, wherein, A second ceramic layer (33) is further sandwiched between the second coating layer (30) and the second surface.
6. The composite separator of claim 5, wherein, The first ceramic layer (21) and the second ceramic layer (33) each comprise inorganic ceramic particles, the inorganic ceramic particles comprising any one of boehmite, alumina, magnesium hydroxide, magnesium oxide, titanium dioxide, silicon dioxide, titanium oxide, barium titanate, zinc oxide, nickel oxide, magnesium fluoride, zirconium oxide, cerium oxide or barium sulfate, the inorganic ceramic particles having a particle size of 0.01 μm to 2 μm.
7. The composite separator according to any one of claims 4-6, wherein, The spray coating thickness of the first spray-coated modification coating layer (23) and the second spray-coated modification coating layer (31) is 3 μm to 6 μm, and the formed thickness after hot pressing is 1.5 μm to 3 μm.
8. The composite separator of any one of claims 4-6, wherein, The roll coating thickness of the first roll-coated modification coating layer (22) and the second roll-coated modification coating layer (32) is 0.5 μm to 3 μm, and the formed thickness after hot pressing is 0.2 μm to 1.5 μm.
9. The composite separator of any one of claims 4-6, wherein, The first spray-coated modification coating layer (23), the first roll-coated modification coating layer (22), the second spray-coated modification coating layer (31) and the second roll-coated modification coating layer (32) each comprise an inorganic modification coating layer, an organic modification coating layer or a hybrid modification coating layer.
10. The composite separator of any one of claims 4-6, wherein, The active substances of the first spray-coated modification coating layer (23) and the second spray-coated modification coating layer (31) are each distributed in island shape.
11. A single cell characterized by The composite separator comprises the composite separator according to any one of claims 1-10. The composite separator comprises the composite separator according to any one of claims 1-10.