A winding battery separator, a winding battery, and an electric device

Abstract

The utility model discloses the technical field of lithium battery, and proposes a kind of winding battery diaphragm, comprising: base film and coating layer, the coating layer is coated in the one side of the base film, the coating layer has at least two segments pore volume unequal regions along predetermined direction, wherein the pore volume of first coating layer is greater than the pore volume of tail coating layer. The first segment pore volume of the utility model coating layer is greater than the tail segment pore volume, and then the liquid absorption performance of first coating layer is greater than tail coating layer, after diaphragm and positive plate negative plate are wound to form the battery structure along predetermined direction, and the coating layer with great liquid absorption performance is located in the inside of battery, so that the ability of coating layer in the inside of battery structure absorbs electrolyte is stronger, so that the inner ring of battery structure can be soaked with sufficient electrolyte, to reduce the lithium precipitation phenomenon generated due to insufficient electrolyte contact in the inner ring of battery.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, and in particular to a wound battery separator, a wound battery, and an electrical device. Background Technology

[0002] The main structures in a lithium-ion battery system are the negative electrode, the separator, and the positive electrode, as well as the electrolyte filled between the negative and positive electrodes. The charging process of a lithium-ion battery involves lithium ions being extracted from the positive electrode material, migrating through the separator and electrolyte to the surface of the negative electrode material, and inserting into the crystal structure of the negative electrode material. The discharging process involves lithium ions being extracted from the crystal structure of the negative electrode material, migrating through the electrolyte and separator to the surface of the positive electrode material, and embedding into the crystal structure of the positive electrode material.

[0003] CN119812677A discloses a lithium battery separator with a gradient pore structure and its preparation method. By optimizing the pore size distribution of the separator, the flow of electrolyte and ion transport can be effectively controlled. Larger pore sizes facilitate rapid electrolyte transport, while smaller pore sizes prevent short circuits and improve the mechanical strength and heat resistance of the separator. However, in existing wound batteries, the wetting effect of the separator and electrolyte is inconsistent between the inner and outer layers of the core, which easily leads to lithium plating inside the core. The specific reason is that due to the compact structure of wound batteries, the spatial steric hindrance difference between the head and tail of the separator leads to inconsistent electrolyte wetting effects in different areas. That is, the electrolyte wetting effect of the inner layer separator of the wound battery is poor, making it prone to lithium plating, while the outer layer separator of the wound battery has sufficient contact with the electrolyte, good wetting effect, and lower risk of lithium plating.

[0004] Therefore, a wound battery separator, a wound battery, and an electrical device are proposed to solve the technical problem of inconsistent wetting effects between the inner and outer ring separators and the electrolyte in existing wound batteries, which easily leads to lithium plating inside the battery. Utility Model Content

[0005] In view of this, the present invention proposes a wound battery separator, a wound battery, and an electrical device, which have different liquid absorption rates along the winding direction of the battery, and can solve the technical problem of inconsistent wetting effects between the inner and outer separators and the electrolyte in existing wound batteries, which leads to lithium plating inside the battery.

[0006] This utility model proposes a wound battery separator and a wound battery, comprising: A base film and a coating layer, wherein the coating layer is coated on one side of the base film, and the coating layer has at least two sections with unequal pore volumes along a predetermined direction, wherein the pore volume of the first section of the coating layer is greater than the pore volume of the last section of the coating layer.

[0007] Based on the above technical solution, preferably, the coating layer has N segments of unequal pore volume regions arranged sequentially along a predetermined direction, where N is a positive integer, and the pore volumes of the N segments of unequal pore volume regions are S1, S2, ..., Sn, where S1>S2>...>Sn.

[0008] Based on the above technical solution, preferably, the pore volume S10 of the first coating layer is in the range of 0.2-0.5 ml / g, and the pore volume Sn0 of the tail coating layer is in the range of 0.01-0.05 ml / g.

[0009] Based on the above technical solution, preferably, the thickness of the coating layer is 2μm.

[0010] Based on the above technical solution, preferably, the coating layer is alumina powder, and the particle size D of the alumina powder is in the range of 0.6-0.8 μm.

[0011] Based on the above technical solution, preferably, the pore size L of the alumina powder is in the range of 20-50 nm.

[0012] Based on the above technical solution, preferably, the base film is a polyethylene film.

[0013] Based on the above technical solution, preferably, the thickness of the base film is 6-9 μm.

[0014] On the other hand, the present invention also provides a wound battery, including a battery, wherein a wound battery separator as described above is wound inside the battery, and the pore volume of the wound battery separator decreases sequentially along the winding direction of the battery.

[0015] On the other hand, this utility model also provides an electrical device that uses the aforementioned wound battery to power the electrical device.

[0016] The present invention provides a wound battery separator, a wound battery, and an electrical device, which have the following advantages compared with the prior art: 1. If the pore volume of the first section of the coating is greater than that of the last section, then the liquid absorption performance of the first section of the coating is greater than that of the last section of the coating. After the separator and the positive and negative electrode plates are wound in a predetermined direction to form the cell structure, the coating with greater liquid absorption performance is located in the inner ring of the cell, which makes the coating inside the cell structure have a stronger ability to absorb electrolyte. This allows the inner ring of the cell structure to be fully wetted with electrolyte, thereby reducing the lithium plating phenomenon caused by insufficient electrolyte contact in the inner ring of the cell. 2. The pore volume S10 of the first coating layer is in the range of 0.2-0.5 ml / g. The specific surface area of ​​the first coating layer is large, and its electrolyte absorption efficiency is at least 148.1%, and the electrolyte retention rate is at least 145.8%. This limitation of the pore volume range makes it easier to absorb electrolyte, and the membrane is better wetted by electrolyte. This can significantly improve the electrolyte absorption effect of the inner ring of the cell, reduce the risk of poor wetting of the inner ring membrane, and reduce lithium plating. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a cross-sectional view of a wound battery separator according to the present invention; Figure 2 This is a cross-sectional view of a wound battery separator according to the present invention.

[0019] Reference numerals: 1. Base film; 2. Coating layer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0021] In the description of the embodiments of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this utility model based on the specific circumstances.

[0022] In the description of the embodiments of this utility model, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this utility model and simplifying the description, 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 the embodiments of this utility model.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0025] The following disclosure provides numerous different embodiments or examples for implementing various structures of the present invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0026] The technical solution is explained below. In existing wound batteries, the wetting effect of the electrolyte on the inner and outer separators of the core is inconsistent, which easily leads to lithium plating inside the core. Specifically, due to the compact structure of wound batteries, the spatial steric hindrance difference between the head and tail of the separator results in inconsistent electrolyte wetting effects in different areas. That is, the electrolyte wetting effect on the separator in the center of the wound battery is poor, making it prone to lithium plating, while the separator at the tail of the wound battery has sufficient contact with the electrolyte, resulting in good wetting and a lower risk of lithium plating.

[0027] like Figure 1As shown, this utility model provides a wound battery separator, comprising: The base film 1 and the coating layer 2 are coated on one side of the base film 1. The coating layer 2 has at least two sections with unequal pore volumes along a predetermined direction, wherein the pore volume of the first section of the coating layer 2 is greater than the pore volume of the last section of the coating layer 2.

[0028] If the pore volume of the first section of coating layer 2 is greater than that of the last section, then the liquid absorption performance of the first section of coating layer 2 is greater than that of the last section of coating layer 2. After the separator and the positive and negative electrode sheets are wound in a predetermined direction to form a cell structure, the coating layer 2 with greater liquid absorption performance is located in the inner ring of the cell, which makes the coating layer 2 inside the cell structure have a stronger ability to absorb electrolyte. This allows the inner ring of the cell structure to be fully wetted with electrolyte, thereby reducing the lithium plating phenomenon caused by insufficient electrolyte contact in the inner ring of the cell.

[0029] In order to make the absorption capacity of the diaphragm for electrolyte decrease sequentially, the coating layer 2 has N segments of unequal pore volume regions arranged sequentially along a predetermined direction, where N is a positive integer and the pore volumes of the N segments of unequal pore volume regions are S1, S2, ..., Sn, where S1>S2>...>Sn.

[0030] After the separator is wound to form the cell structure, the coating layer 2 located in the inner ring of the cell has the strongest liquid absorption performance. Along the winding direction of the cell structure, the liquid absorption performance of the coating layer 2 gradually decreases. This design corresponds precisely to the distribution of electrolyte inside the battery, ensuring that the inner ring of the cell has sufficient electrolyte to reduce lithium plating.

[0031] To ensure effective electrolyte absorption within the inner ring of the battery cell, the pore volume of the first coating layer 2 is further limited. The pore volume S10 of the first coating layer 2 ranges from 0.2 to 0.5 ml / g, and the pore volume Sn0 of the last coating layer 2 ranges from 0.01 to 0.05 ml / g.

[0032] The pore volume S10 of the first coating layer 2 ranges from 0.2 to 0.5 ml / g. The first coating layer 2 has a large specific surface area, achieving an electrolyte absorption efficiency of at least 148.1% and a electrolyte retention rate of at least 145.8%. This limited pore volume range facilitates electrolyte absorption, resulting in better electrolyte wetting of the separator. This significantly improves the electrolyte absorption effect within the inner ring of the cell, reduces the risk of poor inner ring separator wetting, and minimizes lithium plating. Since the tail-end coating layer 2 exhibits the best electrolyte wetting effect, even with a pore volume Sn0 range of 0.01 to 0.05 ml / g, lithium plating is relatively rare in this region, ensuring that the entire cell will not experience lithium plating. For the pore volume of the intermediate transition region of coating layer 2, it is only necessary to satisfy the pore volume range S10 > S2 > ... > S n-1 >Sn0.

[0033] like Figure 1 and Figure 2As shown, the unequal pore volume region of the coating layer 2 is configured in three segments and wound in a predetermined direction. In the wound diaphragm, the pore volume of the coating layer 2 is sequentially divided into high pore volume, medium pore volume, and low pore volume from the inner circle to the outer circle, thereby forming a diaphragm with progressively decreasing liquid absorption capacity. It should be noted that in this embodiment, configuring the unequal pore volume region of the coating layer 2 in three segments is only an optimal implementation method and is not considered a limitation on the technical solution. Correspondingly, the unequal pore volume region of the coating layer 2 can also be configured in three, five, six, or other multiple segments.

[0034] The liquid absorption and retention performance in the three unequal pore volume regions are shown in the table below: High porosity 0.2 148.1 145.8 Medium Hole Capacity 0.06 120.5 118.2 low pore volume 0.02 112.7 109.5 To ensure good electrolyte absorption, the coating layer 2 has a thickness of 2 μm. Limiting the thickness of coating layer 2 to 2 micrometers significantly improves battery energy density by reducing material usage and employing lightweight materials.

[0035] To achieve a gradient change in the membrane's liquid absorption capacity, coating layer 2 is made of alumina powder, with a particle size D ranging from 0.6 to 0.8 μm. This range of alumina powder balances adhesion stability and pore permeability, ensuring uniform adhesion to the membrane surface to form a protective layer without filling or clogging the membrane's micropores. Smaller particle sizes may cause localized pore blockage due to particle agglomeration, while excessively large particle sizes may reduce coating uniformity and affect the continuity of ion transport paths.

[0036] Preferably, the alumina powder has a particle size of 0.7 μm, and the battery cycle performance of the separator coated with this particle size is better than that of samples with larger particle sizes (such as 1.2 μm).

[0037] like Figure 2 As shown, a layer of high-porosity alumina powder is mainly coated in the high-porosity region. The pore volume distribution of the alumina powder is 0.2-0.5 ml / g. The high-porosity alumina has a rich pore structure and a large specific surface area, making it easier for electrolyte to enter and providing strong electrolyte wetting ability. This can significantly improve the rate at which the inner ring diaphragm of the wound cell absorbs electrolyte and reduce the risk of poor wetting of the inner ring diaphragm. For the medium-porosity region, the pore volume of the coated alumina powder is slightly reduced, ranging from 0.05-0.2 ml / g. The electrolyte wetting pressure in the middle winding area begins to weaken, and the medium-porosity alumina coating can meet the liquid absorption requirements of the diaphragm. The corresponding low-porosity region is coated with alumina powder of conventional pore volume, ranging from 0.01-0.05 ml / g.

[0038] To ensure the liquid absorption and retention rate of the alumina powder, the pore size L of the alumina powder is in the range of 20-50 nm. Limiting the pore size range of the alumina powder ensures the mechanical strength and liquid absorption and retention rate of the coating layer 2 formed by the alumina powder.

[0039] Base film 1 is a polyethylene film. Alumina powder significantly improves the wettability of separators with polymer-based base films.

[0040] The thickness of base film 1 is 6-9 μm.

[0041] On the other hand, the present invention also provides a wound battery, including a battery, wherein the aforementioned wound battery separator is wound inside the battery, and the pore volume of the wound battery separator decreases sequentially along the winding direction of the battery.

[0042] Specifically, in a wound battery, the aforementioned separator is located between the positive and negative electrode plates and is assembled together by a winding machine, so that adjacent positive and negative electrode plates are isolated by the separator, forming a wound cell structure. The separator located in the inner ring of the wound cell structure has a larger pore volume, which can reduce the technical problem of poor electrolyte wetting effect in the inner ring of the wound cell structure, which may lead to lithium plating.

[0043] On the other hand, this utility model also provides an electrical device that uses the aforementioned wound battery to power the device. The electrical device can be any electrical device that can use lithium-ion batteries, such as electric vehicles, aircraft, flying vehicles, mobile phones, tablets, handheld game consoles, portable digital devices (e.g., digital cameras), smart home devices, and smart wearables (e.g., smart bracelets, smartwatches, smart glasses).

[0044] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A wound battery separator, characterized in that, include: A base film (1) and a coating layer (2), wherein the coating layer (2) is coated on one side of the base film (1), and the coating layer (2) has at least two sections with unequal pore volumes along a predetermined direction, wherein the pore volume of the first section of the coating layer (2) is greater than the pore volume of the last section of the coating layer (2).

2. The wound battery separator as described in claim 1, characterized in that, The coating layer (2) has N segments of unequal pore volume regions arranged sequentially along a predetermined direction, where N is a positive integer and the pore volumes of the N segments of unequal pore volume regions are S1, S2, ..., Sn, where S1>S2>...>Sn.

3. The wound battery separator as described in claim 2, characterized in that, The pore volume S10 of the first coating layer (2) ranges from 0.2 to 0.5 ml / g, and the pore volume Sn0 of the tail coating layer (2) ranges from 0.01 to 0.05 ml / g.

4. The wound battery separator as described in claim 3, characterized in that, The coating layer (2) has a thickness of 2 μm.

5. The wound battery separator as described in claim 4, characterized in that, The coating layer (2) is alumina powder, and the particle size D of the alumina powder is in the range of 0.6-0.8 μm.

6. The wound battery separator as described in claim 5, characterized in that, The pore size L of the alumina powder is in the range of 20-50 nm.

7. The wound battery separator as described in claim 1, characterized in that, The base film (1) is a polyethylene film.

8. The wound battery separator as described in claim 7, characterized in that, The thickness of the base film (1) is 6-9 μm.

9. A wound battery, characterized in that, The battery includes a wound battery separator as described in any one of claims 1-8, wherein the pore volume of the wound battery separator decreases sequentially along the winding direction of the battery.

10. An electrical appliance, characterized in that, The device is powered by the wound battery as described in claim 9.

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