Separator for battery, electrode assembly, and electrochemical device
Patent Information
- Application Number
- CN202522105338.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-29
- Publication Date
- 2026-09-04
- Estimated Expiration
- 2035-09-29
AI Technical Summary
析锂现象不仅会降低电池的容量和能量密度，还可能引发电池内部短路，造成电池过热、燃烧甚至爆炸等严重的安全隐患，对电池的使用寿命和安全性能产生不良影响
[0016]本申请提出了一种用于电池的隔膜、电极组件及电化学装置，电极组件包括极片与上述的隔膜，隔膜包括第一涂层、第二涂层和基材，通过在基材的拐角区设置第一涂层，使电极组件拐角部位的极片与隔膜粘接更紧密，并且增强该处的电解液浸润能力，降低电极组件拐角部位析锂的概率，从而提高了电化学装置的使用寿命和安全性能。
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Figure CN224721083U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electrochemical energy storage technology, and in particular to separators, electrode assemblies and electrochemical devices for batteries. Background Technology
[0002] In the field of battery technology, wound cells occupy a commonly used position in various battery applications due to their structural characteristics and manufacturing process advantages. Their unique wound structure allows the battery to accommodate a larger amount of active material within a limited space, thereby improving the battery's energy density to a certain extent.
[0003] However, in the actual use of wound cells, the electrodes expand during charging and discharging, causing the distance between the separator and the electrodes to gradually increase. The structural characteristics of wound cells mean that the corners bear the greatest stress, so the change in distance between the separator and the electrodes at the corners is more significant than in other areas. Since the migration rate of lithium ions is related to the distance between the separator and the electrodes, when the distance between the separator and the electrodes increases due to electrode expansion, the migration path of lithium ions between them becomes longer, resulting in a decrease in the migration rate of lithium ions. As the battery cycle continues, in the later stages of the cycle, the electrolyte decreases due to consumption, making it more difficult for lithium ions to migrate at the corners. In this situation, lithium ions are prone to deposit on the electrode surface at the corners, forming lithium dendrites, i.e., lithium plating. Lithium plating not only reduces the battery's capacity and energy density but may also cause internal short circuits, leading to serious safety hazards such as overheating, combustion, or even explosion, adversely affecting the battery's lifespan and safety performance. Utility Model Content
[0004] The main objective of this application is to provide a separator, electrode assembly, and electrochemical device for batteries, aiming to improve the safety performance and service life of the electrochemical device.
[0005] To achieve the above objectives, the first aspect of this application provides a separator for a battery, comprising a substrate and a coating disposed on the surface of the substrate, the coating being used to bond with an electrode sheet;
[0006] The coating includes multiple first coatings and a second coating with a lower adhesive strength than the first coatings. The multiple first coatings and the second coatings are alternately arranged along the winding direction of the substrate. The first coatings are arranged in the corner area after the substrate is wound, and the second coatings are arranged in the straight area after the substrate is wound.
[0007] In some embodiments, the first coating is arranged to the left and right sides along the centerline of the corner area, and its length ranges from 15 mm to 30 mm.
[0008] In some embodiments, the length of the first coating ranges from 18 mm to 20 mm.
[0009] In some implementations, the thickness of the first coating ranges from 1.5 μm to 6 μm.
[0010] In some implementations, the thickness of the second coating is the same as the thickness of the first coating.
[0011] In some embodiments, the first coating is applied in layers, including a first sub-coating and a second sub-coating of different materials.
[0012] In some embodiments, the first sub-coating is a UCCS-B coating, and the second sub-coating includes one or more of a ceramic coating, a PE-O2 coating, and a PVDF coating.
[0013] A second aspect of this application also provides an electrode assembly comprising an electrode sheet and the aforementioned separator for a battery.
[0014] In some embodiments, the electrode includes a positive electrode and a negative electrode, and a separator for the battery is located between the positive electrode and the negative electrode. The positive electrode, the separator for the battery, and the negative electrode are stacked and wound together.
[0015] A third aspect of this application also provides an electrochemical device comprising the electrode assembly described above.
[0016] This application proposes a separator, electrode assembly, and electrochemical device for a battery. The electrode assembly includes an electrode sheet and the aforementioned separator. The separator includes a first coating, a second coating, and a substrate. By providing the first coating at the corner of the substrate, the electrode sheet at the corner of the electrode assembly is more tightly bonded to the separator, and the electrolyte wetting ability at that location is enhanced, reducing the probability of lithium plating at the corner of the electrode assembly, thereby improving the service life and safety performance of the electrochemical device. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the structure of the separator for the battery before it is wound, according to one embodiment of this application.
[0018] Figure 2 This is a schematic diagram of the structure of the substrate, the first coating, and the second coating in another embodiment of this application.
[0019] Explanation of reference numerals in the attached figures:
[0020] 100 diaphragm; 111 substrate; 112 first coating; 113 second coating; 114 corner area; 115 straight area. Detailed Implementation
[0021] The solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments in this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0022] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.
[0023] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.
[0024] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.
[0025] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a separator 100 for a battery before it is wound, according to one embodiment of this application. This embodiment provides a separator 100 for a battery, including a substrate 111 and a coating disposed on the surface of the substrate 111, the coating being used to bond with the electrode sheet;
[0026] The coating includes multiple first coatings 112 and second coatings 113 with adhesive strength less than that of the first coatings 112. The multiple first coatings 112 and second coatings 113 are alternately arranged along the winding direction of the substrate 111. The first coatings 112 are disposed in the corner area 114 after the substrate 111 is wound, and the second coatings 113 are disposed in the straight area 115 after the substrate 111 is wound.
[0027] In this embodiment, the separator 100 includes a substrate 111 and a coating. Since the separator 100 proposed in this application is used to be laminated and wound with the electrode to form a wound battery cell, the substrate 111 is also wound during the winding operation of the separator 100. The substrate 111 includes a plurality of interconnected corner regions 114 and a plurality of straight regions 115. Specifically, after winding, the corner regions 114 of the substrate 111 correspond to the corner portions of the wound battery cell, and the straight regions 115 correspond to the straight portions of the wound battery cell.
[0028] The coating is formed on the substrate 111 by coating, and includes a first coating 112 and a second coating 113. Multiple first coatings 112 and multiple second coatings 113 are alternately disposed on the substrate 111. The first coatings 112 are disposed on the corner areas 114 of the substrate 111, and the second coatings 113 are disposed on the straight areas 115 of the substrate 111. It should be noted that because the adhesion strength between the first coating 112 and the electrode is greater than that between the second coating 113 and the electrode, the adhesion between the separator 100 and the electrode is more stable at the corners where the battery cell is wound.
[0029] During the charging and discharging process of the wound battery cell, the electrodes expand, causing the distance between the separator 100 and the electrodes to gradually increase. Since the corners of the wound battery cell experience the greatest stress, the distance between the separator 100 and the electrodes in these areas also varies the most. As the distance increases, the migration rate of lithium ions decreases. As the cycling process progresses and the electrolyte gradually decreases, lithium plating easily occurs at the corners of the wound battery cell. This application addresses this issue by providing a first coating 112 in the corner region 114 of the separator 100, resulting in a tighter bond between the electrodes and the separator 100 at the corners of the wound battery cell, effectively reducing the variation in the distance between the electrodes and the separator 100 at these corners. In practical use, the first coating 112 enables the electrode at the corner to bond more tightly to the separator 100. In the later stages of the winding cell cycle, it can shorten the distance between the two, making the migration distance of lithium ions shorter, increasing the migration rate of lithium ions, avoiding excessive accumulation of lithium ions at the corner of the cell, reducing the probability of lithium plating at the corner, and thus improving the safety performance and service life of the winding cell.
[0030] like Figure 1 and Figure 2 As shown, Figure 2 This is a schematic diagram of the structure of the substrate 111, the first coating 112, and the second coating 113 in one embodiment of this application. In some embodiments, the first coating 112 is arranged to the left and right sides along the centerline of the corner area 114, and its length ranges from 15mm to 30mm.
[0031] In this embodiment, a plurality of corner areas 114 are provided on the substrate 111, and a first coating 112 is provided on each corner area 114. Specifically, each segment of the first coating 112 is provided to the left and right sides along the center line of the corresponding corner area 114. The dimension of each segment of the first coating 112 in the length direction of the substrate 111 is denoted as the length of the first coating 112, and the length of the first coating is defined as A. The value of A is set in the range of 15mm to 30mm to ensure that each segment of the first coating 112 can cover the corresponding corner area 114. For example, the length A of the first coating 112 can be set to different values such as 15mm, 20mm, and 30mm according to different specifications of the wound battery cell. Taking the length A of the first coating 112 as 15mm as an example, if it is less than 15mm, the first coating 112 cannot completely cover the corner area 114 of the substrate 111, making it difficult to improve the problem of lithium plating at the corner. Taking a length A of 30mm for the first coating 112 as an example, if it is longer than 30mm, the first coating 112 will extend beyond the corner area 114 of the substrate 111, resulting in unnecessary waste of the first coating 112 and increasing production costs. Setting the length A of the first coating 112 to 20mm ensures that the first coating 112 can completely cover the corner area 114 of the substrate 111 while reducing the amount of the first coating 112 used, thus saving costs. In this embodiment, by limiting the length A of the first coating 112 to between 15mm and 30mm, the lithium plating problem at the corner of the wound battery cell can be improved while saving costs.
[0032] In another embodiment, the length A of the first coating 112 ranges from 18 mm to 20 mm. This is because, in actual production, the length A of the first coating 112 needs to be adjusted according to the number and thickness of the wound cell, aiming to ensure that the first coating 112 can cover the corner area 114 of the substrate 111, thus ensuring a stable bond between the electrode and the separator 100 at the corner of the wound cell. Specifically, the greater the number and thickness of the wound cell, the larger the area of the corner, and consequently, the greater the length A of the first coating 112. Depending on the commonly used number and thickness of wound cells, the length A of the first coating 112 can be further set to different values such as 18 mm, 19 mm, or 20 mm. Setting the length A of the first coating 112 to 18mm can reduce the amount of the first coating 112 used; setting the length A of the first coating 112 to 20mm can ensure that the first coating 112 completely covers the corner area 114 of the substrate 111; setting the length A of the first coating 112 to 19mm can achieve a balance between the two. In this embodiment, the length of the first coating 112 is further limited to 18mm to 20mm, which is more suitable for commonly used wound battery cells and improves the adaptability of the first coating 112.
[0033] like Figure 1 and Figure 2 As shown, in some embodiments, the thickness of the first coating 112 ranges from 1.5 μm to 6 μm.
[0034] In this embodiment, the thickness of the first coating 112 is denoted as B, viewed along the thickness direction of the substrate 111. The thickness B of the first coating 112 can be set in the range of 2µm to 6µm. In actual production, the thickness B of the first coating 112 can be set to different values such as 1.5µm, 4µm, and 6µm. Specifically, taking a thickness B of 1.5µm as an example, if the thickness B of the first coating 112 is less than 1.5µm, the process will be unstable, leading to a decrease in the adhesive strength of the first coating 112 and a poorer adhesion between the first coating 112 and the electrode. Taking a thickness B of 6µm as an example, if the thickness B of the first coating 112 is greater than 6µm, the first coating 112 will be too thick, increasing the thickness of the manufactured separator 100, thereby increasing the volume of the wound cell and causing a decrease in energy density. Setting the thickness B of the first coating 112 to 4µm can ensure the adhesive strength of the first coating 112 while avoiding a decrease in the energy density of the wound cell. This embodiment, by limiting the thickness B of the first coating 112 to between 1.5 μm and 6 μm, can enhance the stability of the adhesion between the electrode and the separator 100 at the corner without reducing the energy density.
[0035] like Figure 2 As shown, in a preferred embodiment, the thickness of the first coating 112 is the same as the thickness of the second coating 113. In this embodiment, since the separator 100 is made by alternately coating the first coating 112 and the second coating 113 onto the substrate 111, in order to make the surface of the separator 100 smooth, the thicknesses of the first coating 112 and the second coating 113 can be set to the same value to avoid unevenness on the surface of the separator 100, ensure the quality of the separator 100, and thus improve the overall performance of the wound cell.
[0036] It is understandable that, such as Figure 2 As shown in the diagram, since both the upper and lower surfaces of the substrate 111 need to be coated with the first coating 112 and the second coating 113, in other embodiments, the thickness of the first coating 112 and the second coating 113 on the upper surface of the substrate 111 is the same, and the thickness of the first coating 112 and the second coating 113 on the lower surface of the substrate 111 is the same. However, the thickness of the first coating 112 and the second coating 113 on the upper surface of the substrate 111 can be different from the thickness of the first coating 112 and the second coating 113 on the lower surface of the substrate 111, as long as the upper and lower surfaces of the diaphragm 100 are flat.
[0037] like Figure 2 As shown, in some embodiments, the thickness of the substrate 111 is defined as C, and the value of C ranges from 3 μm to 20 μm.
[0038] In this embodiment, the thickness of the substrate 111 is denoted as C, viewed along its thickness direction. The thickness C can be set between 3µm and 20µm. In actual production, the thickness C of the substrate 111 can be set to different values such as 3µm, 10µm, and 20µm, depending on the specifications of the battery being produced. Specifically, taking a thickness C of 3µm as an example, if the thickness C is less than 3µm, the substrate 111 is too thin, resulting in poor safety performance of the wound cell in needle penetration, short circuit, and hot box tests. Taking a thickness C of 20µm as an example, if the thickness C is greater than 20µm, the substrate 111 is too thick, increasing the thickness of the separator 100 and increasing the weight and volume of the wound cell, leading to a decrease in energy density. Setting the thickness C of the substrate 111 to 10µm not only ensures the safety performance of the separator 100 but also avoids a decrease in energy density. In this embodiment, by limiting the thickness C of the substrate 111 to between 3µm and 20µm, the energy density of the wound battery cell can be avoided while ensuring the safety performance of the separator 100.
[0039] In some embodiments, the first coating 112 is a layered coating, including a first sub-coating and a second sub-coating of different materials. In some embodiments, the first sub-coating is a UCCS-B coating, and the second sub-coating includes one or more of a ceramic coating, a PE-O2 coating, and a PVDF coating.
[0040] In this embodiment, the first coating 112 includes a first sub-coating and a second sub-coating, and the first and second sub-coatings are made of different materials. For example, the first sub-coating can be a UCCS-B coating, and the second sub-coating can be a ceramic coating, a PE-O2 coating, or a PVDF coating. In another embodiment, the second sub-coating can also be formed by interleaving a ceramic coating and a PE-O2 coating. In other embodiments, the second sub-coating can also be formed by interleaving a PE-O2 coating and a PVDF coating. It is understood that in other embodiments not described, the first sub-coating or the second sub-coating can be formed by interleaving one or more of the UCCS-B coating, ceramic coating, PE-O2 coating, and PVDF coating. Since the first coating 112 is composed of interleaving a first sub-coating and a second sub-coating, this creates multiple pores inside the first coating 112, thereby enhancing the electrolyte wetting ability of the first coating 112. Specifically, the first coating 112 can adsorb electrolyte and provide the adsorbed electrolyte to the corner of the wound cell, further reducing the probability of lithium plating at the corner.
[0041] Furthermore, in other embodiments, such as Figure 2 As shown, both the upper and lower surfaces of the substrate 111 need to be coated with the first coating 112, and the composition of the first coating 112 on the upper and lower surfaces can be different. For example, on the upper surface of the substrate 111, the first sub-coating is a UCCS-B coating, and the second sub-coating is a PE-O2 coating and a PVDF coating with intermittent mixing; on the lower surface of the substrate 111, the first sub-coating is a UCCS-B coating, and the second sub-coating is a ceramic coating.
[0042] By adjusting the material of the first coating 112 on the upper and lower surfaces of the substrate 111, the size and arrangement density of the pores inside the first coating 112 can be adjusted, thereby adjusting the liquid retention capacity of the first coating 112 according to the battery specifications to be produced.
[0043] This application further proposes an electrode assembly including electrode sheets and the aforementioned separator 100 for a battery. The specific structure of the separator 100 is as described in the above embodiments. Since the electrode assembly adopts all the technical solutions of all the above embodiments, it has at least all the technical effects brought about by the technical solutions of the above embodiments, and will not be described in detail here. Specifically, the electrode assembly is the aforementioned wound cell, the electrode sheets include positive electrode sheets and negative electrode sheets, the separator 100 is located between the positive electrode sheets and the negative electrode sheets, and the positive electrode sheets, separator 100 and negative electrode sheets are stacked and wound together to form a wound cell.
[0044] like Figure 2 As shown, specifically, the upper surface of the separator 100 is in contact with the positive electrode of the electrode assembly, and the lower surface of the separator 100 is in contact with the negative electrode of the electrode assembly. The separator 100 includes a substrate 111, a first coating 112, and a second coating 113. When the positive electrode, the negative electrode, and the separator are stacked and wound together, since the first coating 112 is provided on the corner areas 114 of both the upper and lower surfaces of the substrate 111, the positive and negative electrodes will adhere more tightly to the separator 100 at the corners of the electrode assembly under the action of the first coating 112. Since the adhesion of the first coating 112 is greater than that of the second coating 113, the change in distance between the positive and negative electrode plates at the corners of the electrode assembly will be smaller in the later stages of the cycle due to the adhesion of the first coating 112. The distance between the positive and negative electrode plates is the distance for lithium ion migration. Therefore, by setting the first coating 112, the rate of lithium ion migration can be increased in the later stages of the cycle, reducing the possibility of lithium ion deposition at the corners of the electrode assembly, thereby improving the problem of lithium plating at the corners of the electrode assembly and further improving the safety performance and service life of the electrode assembly.
[0045] This application further proposes an electrochemical device including the above-described electrode assembly, wherein the electrochemical device may be a wound lithium battery.
[0046] In summary, this application proposes a separator 100, an electrode assembly, and an electrochemical device for a battery. The electrode assembly includes an electrode and a separator 100. The separator 100 includes a first coating 112, a second coating 113, and a substrate 111. By providing the first coating 112 at the corner area 114 of the substrate 111, the electrode at the corner of the electrode assembly is more tightly bonded to the separator 100, and the electrolyte wetting ability at that location is enhanced, reducing the probability of lithium plating at the corner of the electrode assembly, thereby improving the service life and safety performance of the electrochemical device.
[0047] The above description is only a part or preferred embodiment of this application. Neither the text nor the drawings should limit the scope of protection of this application. All equivalent structural transformations made using the content of this application's specification and drawings under the overall concept of this application, or direct / indirect applications in other related technical fields, are included within the scope of protection of this application.
Claims
1. A separator for a battery, characterized in that, It includes a substrate and a coating disposed on the surface of the substrate, the coating being used to bond with an electrode sheet; The coating includes a plurality of first coatings and a second coating with a less adhesive force than the first coatings. The plurality of first coatings and second coatings are alternately arranged along the winding direction of the substrate. The first coatings are disposed in the corner area after the substrate is wound, and the second coatings are disposed in the straight area after the substrate is wound.
2. The separator for a battery according to claim 1, characterized in that, The first coating is arranged on both sides of the centerline of the corner area, and its length ranges from 15mm to 30mm.
3. The separator for a battery according to claim 2, characterized in that, The length of the first coating ranges from 18 mm to 20 mm.
4. The separator for a battery according to claim 3, characterized in that, The thickness of the first coating ranges from 1.5 μm to 6 μm.
5. The separator for a battery according to claim 4, characterized in that, The thickness of the second coating is the same as the thickness of the first coating.
6. The separator for a battery according to any one of claims 1 to 5, characterized in that, The first coating is applied in layers, including a first sub-coating and a second sub-coating of different materials.
7. The separator for a battery according to claim 6, characterized in that, The first sub-coating is a UCCS-B coating, and the second sub-coating includes one or more of a ceramic coating, a PE-O2 coating, and a PVDF coating.
8. An electrode assembly, characterized in that, Includes electrode sheets and the separator for a battery as described in any one of claims 1 to 7.
9. The electrode assembly according to claim 8, characterized in that, The electrode includes a positive electrode and a negative electrode, and the separator for the battery is located between the positive electrode and the negative electrode. The positive electrode, the separator for the battery, and the negative electrode are stacked and wound together.
10. An electrochemical device, characterized in that, Includes the electrode assembly as described in claim 8 or 9.