Battery cell diaphragm structure, battery cell and lithium battery
By introducing an expansion layer and an elastic layer into the cell separator structure of the lithium battery, the problem of poor contact interface between the positive and negative electrode sheets and the separator is solved, and the cycling performance and electrical capacity of the battery cell are improved.
Patent Information
- Application Number
- CN202420253614.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-02
- Publication Date
- 2025-02-28
- Estimated Expiration
- 2034-02-02
AI Technical Summary
The contact interface between the positive and negative electrode sheets and the separator under harsh working conditions is poor, resulting in poor battery circulation performance, capacity attenuation, battery expansion, lithium evolution and other problems.
A battery cell separator structure is adopted, including a substrate layer, an expansion layer and an elastic layer. The expansion layer abuts at the boundary between the substrate layer, and the elastic layer is arranged on the same side of the expansion layer to improve the interface contact between the positive and negative electrode sheets and the separator.
After the expansion layer comes into contact with the electrolyte, the gap between the diaphragm and the electrode sheet is expanded to improve interface contact, improve the cycling performance and electrical capacity of the battery cell, and ensure the overall support performance of the diaphragm structure.
Smart Images
Figure CN222546599U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of lithium batteries, and in particular relates to a battery core diaphragm structure, a battery core and a lithium battery. Background Art
[0002] In today's society, with the widespread use of electric vehicles and electronic products, lithium-ion batteries have become one of the important energy storage systems in modern society due to their advantages such as high energy density, low self-discharge, long cycle life and environmental friendliness.
[0003] However, under harsh working conditions, the contact interface between the positive and negative electrodes and the separator is poor, which leads to problems such as poor battery cycle performance and capacity decay; it also causes a series of problems such as battery expansion and lithium deposition. Utility Model Content
[0004] The purpose of the utility model is to provide a battery cell diaphragm structure, a battery cell and a lithium battery to solve the problem of poor contact interface between the existing positive and negative electrode sheets and the diaphragm.
[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:
[0006] A battery cell diaphragm structure comprises a substrate layer, an expansion layer and an elastic layer; the expansion layer is arranged on at least one side surface of the substrate layer and abuts against the boundary of the surface of the substrate layer; the elastic layer is arranged on at least one side surface of the substrate layer and is on the same side of the substrate layer as the expansion layer.
[0007] Preferably: at least one mounting position is provided in the expansion layer; the elastic layer is arranged inside the mounting position, and the bottom of the elastic layer abuts against the surface of the substrate layer.
[0008] Preferably: the mounting position is a mounting through hole, and the mounting through hole is arranged to penetrate the thickness direction of the expansion layer;
[0009] And / or, the installation position is a installation groove, and the installation groove is arranged to penetrate the expansion layer in the length direction and / or the width direction.
[0010] Preferably: the elastic layers located on two opposite surfaces of the substrate layer are staggered;
[0011] And / or, the elastic layers located on two opposite surfaces of the substrate layer are arranged symmetrically.
[0012] Preferably: the ratio of the coverage area S1 of the elastic layer on the surface of the substrate layer to the coverage area S2 of the expansion layer on the surface of the substrate layer is: S1:S2=C, C is 3% to 22%;
[0013] And / or, the ratio between the thickness H2 of the expansion layer and the thickness H1 of the substrate layer is: H2:H1=1:4 to 1:9.
[0014] Preferably: a flow hole is provided in the substrate layer; and the opening of the flow hole abuts against the surface of the expansion layer.
[0015] Preferably: the range of the pore size D of the flow hole is: D = 0.1 μm to 0.5 μm;
[0016] And / or, the flow holes account for 35% to 60% of the area of the cross section of the substrate layer where the flow holes are located.
[0017] Preferably: the expansion layer is one of a derivative of polystyrene and a derivative of polystyrene;
[0018] And / or, the elastic layer is one of polybutadiene, polyisobutylene, ethylene-vinyl acetate copolymer, and polyurethane;
[0019] And / or, the substrate layer is one of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester and natural fiber.
[0020] The utility model also discloses a battery core, comprising an anode sheet, a cathode sheet and an isolation membrane arranged between the anode sheet and the cathode sheet; the isolation membrane is the battery core diaphragm structure described above.
[0021] The utility model also discloses a lithium battery, comprising the battery core.
[0022] The beneficial effect of the utility model lies in that the technical scheme adopts an expansion layer abutting the boundary on the substrate layer, which expands and fills the gap between the battery cell diaphragm structure and the electrode piece after contacting with the electrolyte during use, thereby effectively improving the interface problem between the battery cell diaphragm structure and the electrode piece, and improving the cycle performance of the battery cell during use and ensuring the electrical capacity; and the elastic layer also realizes elastic deformation under the expansion and squeezing action of the expansion layer to fill the gap between the battery cell diaphragm structure and the electrode piece again, thereby ensuring the overall supporting performance of the battery cell diaphragm structure, and can further effectively improve the interface problem between the battery cell diaphragm structure and the electrode piece, and improve the cycle performance of the battery cell during use and ensure the electrical capacity. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The following will refer to the attached Figures 1 to 5 To describe the features, advantages and technical effects of exemplary embodiments of the present utility model.
[0024] Figure 1This is a schematic structural diagram of a cell diaphragm structure according to an embodiment of the utility model;
[0025] Figure 2 This is a schematic structural diagram of a cell diaphragm structure according to an embodiment of the utility model;
[0026] Figure 3 This is a schematic structural diagram of a substrate layer of a battery cell diaphragm structure according to an embodiment of the utility model;
[0027] Figure 4 This is a structural schematic diagram of a battery cell diaphragm structure of another embodiment of the utility model;
[0028] Figure 5 The figure is a schematic structural diagram of a battery cell according to an embodiment of the utility model.
[0029] In the figure: 1-substrate layer; 11-flow hole; 111-first through hole; 112-second through hole; 101-boundary; 2-expansion layer; 21-mounting position; 3-elastic layer; 100-isolation membrane; 200-anode sheet; 300-cathode sheet. DETAILED DESCRIPTION
[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.
[0031] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.
[0032] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.
[0033] In the description of the embodiments of the present application, the term "and / or" is merely an association relationship between the related objects of a cell diaphragm structure, a cell and a lithium battery, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist at the same time, and multiple situations exist alone. In addition, the character " / " in this article generally indicates that the previous and next related objects are an "or" relationship between a cell diaphragm structure, a cell and a lithium battery.
[0034] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).
[0035] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.
[0036] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.
[0037] The following is combined with Figure 1 to Figure 5 The utility model is further described in detail, but it is not intended to limit the utility model.
[0038] like Figure 1 As shown, in one embodiment of the utility model, the battery cell diaphragm structure includes a substrate layer 1, an expansion layer 2 and an elastic layer 3; the expansion layer 2 is arranged on at least one side surface of the substrate layer 1, and abuts against the boundary 101 of the surface of the substrate layer 1; the elastic layer 3 is arranged on at least one side surface of the substrate layer 1, and is on the same side of the substrate layer 1 as the expansion layer 2. Among them, the boundary 101 is one, two, three or all of the front, back, left and right boundaries of the surface of the substrate layer 1.
[0039] The technical solution of the utility model adopts an expansion layer abutting against the boundary on the substrate layer, which expands and fills the gap between the battery cell diaphragm structure and the electrode piece after contacting with the electrolyte during use, thereby effectively improving the interface problem between the battery cell diaphragm structure and the electrode piece, and improving the cycle performance of the battery cell during use and ensuring the electrical capacity; and the elastic layer is elastically deformed under the expansion and squeezing action of the expansion layer to fill the gap between the battery cell diaphragm structure and the electrode piece again, thereby ensuring the overall supporting performance of the battery cell diaphragm structure, and can further effectively improve the interface problem between the battery cell diaphragm structure and the electrode piece, and improve the cycle performance of the battery cell during use and ensure the electrical capacity.
[0040] In some embodiments, the expansion layer 2 is one of polystyrene or a derivative of polystyrene; the elastic layer 3 is a combination of one or more of polybutadiene, polyisobutylene, ethylene-vinyl acetate copolymer, and polyurethane. This structure can effectively ensure the expansion sensitivity when in contact with the electrolyte through one of polystyrene or a derivative of polystyrene, thereby increasing the speed of gap adjustment; and through a combination of one or more of polybutadiene, polyisobutylene, ethylene-vinyl acetate copolymer, and polyurethane, the amplitude and sensitivity of the elastic deformation of the expansion and compression can be increased, thereby increasing the speed of gap adjustment. The substrate layer 1 is a combination of one or more of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, and natural fiber. The structure can improve the support stability of the battery cell diaphragm structure through one or more of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester and natural fiber, and can also effectively play the role of separating the pole pieces on both sides, thereby ensuring the performance and stability of the battery cell diaphragm structure. Figure 2 As shown, the thickness H1 of the substrate layer 1 has a value range of: H1 = 6 μm to 38 μm, preferably 10 μm to 25 μm.
[0041] Specifically, in some embodiments, Figure 2As shown, at least one mounting position 21 is provided in the expansion layer 2; the elastic layer 3 is provided inside the mounting position 21, and the bottom of the elastic layer 3 abuts against the surface of the substrate layer 1. This structure can effectively ensure that the elastic layer 3 can also quickly elastically deform during the expansion of the expansion layer 2 by providing the elastic layer 3 inside the expansion layer 2, thereby quickly improving the interface problem between the cell diaphragm structure and the pole piece. Among them, in some embodiments, the mounting position 21 is a mounting through hole, which is provided in the thickness direction of the expansion layer 2; and the elastic layer 3 is connected to the inner wall of the mounting through hole; that is, the gap between the cell diaphragm structure and the pole piece can be better filled by the expansion layer 2 with the largest possible coverage area, thereby improving the cycle performance of the cell during use and ensuring the electrical capacity. In other embodiments, the mounting position 21 is a mounting groove, which is arranged to penetrate the length direction and / or width direction of the expansion layer 2; and the elastic layer 3 is connected to the inner wall of the mounting groove; that is, the expansion layer 2 is divided into a plurality of strip-shaped or grid-shaped structures by the mounting groove and the elastic layer 3, which is beneficial to increase the contact coverage area between the electrolyte and the expansion layer 2, thereby increasing the expansion deformation of the expansion layer 2, and further reducing the gap between the battery cell diaphragm structure and the electrode as much as possible.
[0042] Specifically, in some embodiments, Figure 1 and 2 As shown, the expansion layer 2 and the elastic layer 3 are respectively arranged on two opposite surfaces of the substrate layer 1. This structure can adjust the gap between the anode sheet and the cathode sheet respectively through the expansion layer 2 and the elastic layer 3 on the upper and lower surfaces of the substrate layer 1, thereby effectively improving the cycle performance of the battery cell during use and ensuring the electrical capacity. Figure 2 As shown, the thickness H2 of the expansion layer 2 located on the upper surface of the substrate layer 1 is equal to the thickness H2 of the expansion layer 2 located on the lower surface of the substrate layer 1 .
[0043] In some embodiments, such as Figure 2 As shown, the elastic layers 3 located on two opposite surfaces of the substrate layer 1 are staggered; the staggered elastic layers 3 can avoid extrusion damage to the substrate layer 1 at the same thickness position during elastic deformation, thereby improving the protection of the substrate layer 1 and ensuring the stability of the battery cell diaphragm structure. In other embodiments, such as Figure 4 As shown, the elastic layers 3 located on two opposite surfaces of the substrate layer 1 are symmetrically arranged; the symmetrically arranged elastic layers 3 can improve the uniformity of the structural deformation of the battery cell diaphragm structure during the expansion deformation process, and ensure the uniformity of the flow of the electrolyte, thereby improving the use stability of the battery cell diaphragm structure.
[0044] In some embodiments, the ratio of the coverage area S1 of the elastic layer 3 on the surface of the substrate layer 1 to the coverage area S2 of the expansion layer 2 on the surface of the substrate layer 1 is: S1: S2 = C, where C is 3% to 22%; further, preferably, C = (5% to 12%). The relationship between the mass M1 of the elastic layer 3 and the mass M2 of the expansion layer 2 is: M1: M2 = (3% to 22%); further preferably, M1: M2 = (5% to 12%). This structure can effectively ensure the range of expansion or deformation by reasonably designing the elastic layer 3 and the expansion layer 2, avoiding the impact on the pole piece, thereby improving the stability of use.
[0045] Specifically, in some embodiments, Figure 2 As shown, the ratio between the thickness H2 of the expansion layer 2 and the thickness H1 of the substrate layer 1 is: H2:H1=1:4 to 1:9; further preferably, D=(4-7). This structure can ensure the stability of the battery cell and can also improve the energy density of the battery cell. If the expansion layer 2 of the electrolyte is too thin, the filling effect will be poor. If the expansion layer 2 of the electrolyte is too thick, the thickness of the battery cell will increase, reducing the energy density of the battery cell.
[0046] Specifically, in some embodiments, Figure 2 As shown, the substrate layer 1 is provided with a flow hole 11; the opening of the flow hole 11 abuts against the surface of the expansion layer 2. The porous structure of the structure can make the electrolyte and the expansion layer 2 better contact, thereby ensuring the orderly expansion phenomenon. Figure 2 and 3 As shown, the flow hole 11 includes at least one first through hole 111 and at least one second through hole 112; the first through hole 111 is arranged along the thickness direction of the substrate layer 1; the second through hole 112 is arranged along the length direction and / or width direction of the substrate layer 1; and the first through hole 111 is connected to the at least one second through hole 112. Further, as Figure 3 As shown, the first through hole 111 located in the upper half of the substrate layer 1 is not connected to the first through hole 111 located in the lower half of the substrate layer 1; thereby achieving a separation effect and avoiding short circuits between the electrodes. Figure 3 As shown, the aperture D of the first through hole 111 or the aperture D of the second through hole 112 has a value range of: D = 0.1 μm to 0.5 μm; preferably, D = 0.1 μm to 0.4 μm. And the area ratio of the first through hole 111 or the second through hole 112 to the cross-section of the substrate layer 1 where it is located is 35% to 60%, preferably, S3 = 45% to 55%. In other words, the porosity of the first through hole 111 or the second through hole 112 reaches 45% to 55%, thereby ensuring the maximum circulation and diversion of the electrolyte, thereby improving the energy density of the battery cell.
[0047] The utility model also provides a battery cell, such as Figure 5 As shown, the battery cell includes an anode sheet 200, a cathode sheet 300 and an isolation membrane 100 arranged between the anode sheet 200 and the cathode sheet 300; the isolation membrane 100 is the above-mentioned composite isolation membrane structure, and the specific structure of the composite isolation membrane structure refers to the above-mentioned embodiment. Since the present battery cell adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.
[0048] The anode sheet 200 includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode current collector; the positive electrode current collector includes a positive electrode coating area and a positive electrode tab connected to the positive electrode coating area, the positive electrode coating area is coated with a positive electrode active material layer, and the positive electrode tab is not coated with the positive electrode active material layer. The cathode sheet 300 includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode current collector; the negative electrode current collector includes a negative electrode coating area and a negative electrode tab connected to the negative electrode coating area, the negative electrode coating area is coated with a negative electrode active material layer, and the negative electrode tab is not coated with a negative electrode active material layer.
[0049] The utility model also proposes a lithium battery, which includes a battery cell. The specific structure of the battery cell refers to the above embodiment. Since the battery adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.
[0050] Among them, lithium battery refers to a cup, trough or other container or part of a composite container that contains electrolyte solution and metal electrodes to generate current, and is a device that can convert chemical energy into electrical energy; the battery has positive and negative electrodes. Principle: In chemical batteries, the direct conversion of chemical energy into electrical energy is the result of spontaneous oxidation, reduction and other chemical reactions inside the battery, which are carried out on two electrodes respectively. The negative electrode active material is composed of a reducing agent with a relatively negative potential and stable in the electrolyte, such as active metals such as zinc, cadmium, lead and hydrogen or hydrocarbons. The positive electrode active material is composed of an oxidizing agent with a relatively positive potential and stable in the electrolyte, such as metal oxides such as manganese dioxide, lead dioxide, nickel oxide, oxygen or air, halogens and their salts, oxygen-containing acids and their salts, etc. The electrolyte is a material with good ionic conductivity, such as an aqueous solution of acid, alkali, salt, organic or inorganic non-aqueous solution, molten salt or solid electrolyte.
[0051] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.
[0052] According to the disclosure and teaching of the above description, the technicians in the field of the utility model can also change and modify the above implementation. Therefore, the utility model is not limited to the above specific implementation, and any obvious improvement, replacement or modification made by the technicians in this field on the basis of the utility model belongs to the protection scope of the utility model. In addition, although some specific terms are used in this specification, these terms are only for the convenience of explanation and do not constitute any limitation to the utility model.
Claims
1. A battery cell diaphragm structure, characterized in that: It includes a substrate layer, an expansion layer and an elastic layer; the expansion layer is arranged on at least one side surface of the substrate layer and abuts against the boundary of the surface of the substrate layer; the elastic layer is arranged on at least one side surface of the substrate layer and is on the same side of the substrate layer as the expansion layer.
2. The battery cell diaphragm structure according to claim 1, characterized in that: At least one installation position is arranged in the expansion layer; the elastic layer is arranged inside the installation position, and the bottom of the elastic layer abuts against the surface of the substrate layer.
3. The battery cell diaphragm structure according to claim 2, characterized in that: The mounting position is a mounting through hole, and the mounting through hole is arranged to penetrate the thickness direction of the expansion layer; And / or, the installation position is a installation groove, and the installation groove is arranged to penetrate the expansion layer in the length direction and / or the width direction.
4. The battery cell diaphragm structure according to claim 1, characterized in that: The elastic layers located on two opposite surfaces of the substrate layer are staggered; And / or, the elastic layers located on two opposite surfaces of the substrate layer are arranged symmetrically.
5. The battery cell diaphragm structure according to claim 1, characterized in that: The ratio of the coverage area S1 of the elastic layer on the surface of the substrate layer to the coverage area S2 of the expansion layer on the surface of the substrate layer is: S1:S2=C, where C is 3% to 22%; And / or, the ratio of the thickness H2 of the expansion layer to the thickness H1 of the substrate layer is: H2:H1=1:4 to 1:
9.
6. The battery cell diaphragm structure according to any one of claims 1 to 5, characterized in that: The base material layer is provided with flow holes; the openings of the flow holes abut against the surface of the expansion layer.
7. The battery cell diaphragm structure according to claim 6, characterized in that: The value range of the pore diameter D of the flow hole is: D = 0.1 μm to 0.5 μm; And / or, the flow holes account for 35% to 60% of the area of the cross section of the substrate layer where the flow holes are located.
8. The battery cell diaphragm structure according to claim 1, characterized in that: The expansion layer is one of a derivative of polystyrene and a derivative of polystyrene; And / or, the elastic layer is one of polybutadiene, polyisobutylene, ethylene-vinyl acetate copolymer, and polyurethane; And / or, the substrate layer is one of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester and natural fiber.
9. A battery cell, characterized in that: It comprises an anode sheet, a cathode sheet and an isolation membrane arranged between the anode sheet and the cathode sheet; the isolation membrane is the battery cell diaphragm structure according to any one of claims 1 to 8.
10. A lithium battery, characterized in that: Comprising the battery cell as claimed in claim 9.