Electrode sheets and their preparation methods, battery cells, batteries, and electrical devices.

Abstract

This application provides an electrode sheet and its preparation method, a battery cell, a battery, and an electrical device, belonging to the field of battery technology. The electrode sheet includes a current collector, an active material layer, a first insulating layer, and a second insulating layer. The current collector includes a main body and a tab, with the tab extending from a first end of the main body along a first direction. The main body includes a coating area and a transition area, with the transition area disposed between the coating area and the tab. The active material layer is disposed on the surface of the coating area. The first insulating layer is disposed on the end face of the main body at the first end. At least a portion of the second insulating layer is disposed on the surface of the transition area, and the second insulating layer includes a thermoplastic polymer with a volume particle size distribution D. V 50 represents the maximum particle size D of thermoplastic polymers, ranging from 6μm to 10μm. max The thickness ranges from 90μm to 110μm. The technical solution of this application is beneficial to improving the reliability of individual battery cells.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrode sheet and its preparation method, a battery cell, a battery, and an electrical device. Background Technology

[0002] With increasing environmental pollution, the new energy industry is attracting more and more attention. Within the new energy industry, battery technology is a crucial factor in its development.

[0003] The development of battery technology requires consideration of various design factors, such as energy density, cycle life, and reliability. The design of the electrodes in a battery cell is crucial to its reliability; therefore, how to provide an electrode that improves the reliability of a battery cell is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide an electrode to improve the reliability of a single battery cell.

[0005] To achieve the above objectives, this application provides an electrode sheet and its preparation method, a battery cell, a battery, and an electrical device.

[0006] In a first aspect, an electrode is provided, comprising a current collector, an active material layer, a first insulating layer, and a second insulating layer. The current collector includes a main body and an electrode tab, the electrode tab extending from a first end of the main body, the first end being one end of the main body along a first direction. The main body includes a coating region and a transition region, the transition region being disposed between the coating region and the electrode tab. The active material layer is disposed on the surface of the coating region. The first insulating layer is disposed on the end face of the main body at the first end. At least a portion of the second insulating layer is disposed on the surface of the transition region, the second insulating layer comprising a thermoplastic polymer, the thermoplastic polymer having a volume particle size distribution D. V 50 is 6μm to 10μm, and the maximum particle size D of the thermoplastic polymer is... max The size ranges from 90μm to 110μm.

[0007] This application provides an electrode sheet, which includes a current collector, an active material layer, a first insulating layer, and a second insulating layer. The current collector includes a main body and a tab, with the tab extending from a first end of the main body, which is one end of the main body along a first direction. The main body includes a coating area and a transition area, with the transition area disposed between the coating area and the tab. The coating area is provided with the active material layer. Thus, by providing the transition area, during the tab cutting process, the cutting tool can maintain a certain distance from the active material layer, reducing the shedding of the active material layer. The first insulating layer is disposed on the end face of the main body at the first end. This allows the first insulating layer to cover the end face of the first end, reducing the risk of the current collector being exposed at the end face, thereby reducing the risk of the exposed current collector contacting an electrode of opposite polarity. Furthermore, the first insulating layer can also cover burrs generated during the cutting process, reducing the risk of burrs contacting an electrode of opposite polarity. At least a portion of the second insulating layer is disposed on the surface of the transition area, and the second insulating layer comprises a thermoplastic polymer. Thus, the cutting line is located in the transition zone. During the cutting of the electrode tab, the thermoplastic polymer in the second insulating layer on the surface of the transition zone changes from a solid state to a fluid state upon heating. The fluid thermoplastic polymer flows to the end face of the first end and solidifies at the end face after cooling. The volumetric particle size distribution D of the thermoplastic polymer... V 50 is 6μm to 10μm, and the maximum particle size D of the thermoplastic polymer is... max With a particle size of 90μm to 110μm, the thermoplastic polymer is less prone to agglomeration by appropriately setting its particle size. Furthermore, the thermoplastic polymer exhibits a suitable flow path after heating, which facilitates the formation of a uniform and dense first insulating layer at the end face, thereby enabling uniform and dense coating of the end face. Therefore, the technical solution of this application embodiment can improve the reliability of the battery cell.

[0008] In one possible implementation, the volumetric particle size distribution D of the thermoplastic polymer V 50 is 7μm to 8μm, and the maximum particle size D of the thermoplastic polymer is... max The thickness is 90μm to 100μm. In this way, the thermoplastic polymer is less likely to agglomerate, and after being heated from a solid state to a fluid state, it has a more suitable flow path, which is conducive to the formation of a uniform and dense first insulating layer at the end face.

[0009] In one possible implementation, the thickness d2 of the second insulating layer is 22 μm to 48 μm; alternatively, the thickness d2 of the second insulating layer is 22 μm to 30 μm.

[0010] In the above technical solution, when the thickness d2 of the second insulating layer is not less than 22 μm, during the cutting process of the current collector with the second insulating layer, there is a greater amount of thermoplastic polymer in the second insulating layer. This allows more thermoplastic polymer to flow to the burrs and exposed end faces of the current collector after heating, which is beneficial for uniformly and densely covering the exposed end faces and burrs. When the thickness d2 of the second insulating layer does not exceed 48 μm, it helps to reduce the energy consumed during the cutting process. Optionally, the thickness d2 of the second insulating layer is 22 μm to 30 μm, which can improve the covering effect on the exposed end faces and burrs while reducing the energy consumed in cutting.

[0011] In one possible implementation, the thickness d1 of the first insulating layer is 300 nm to 1800 nm. This allows the first insulating layer to cover burrs and exposed end faces while maintaining a relatively small thickness. Optionally, the thickness d1 of the first insulating layer is 300 nm to 860 nm, which is advantageous for further reducing the thickness of the first insulating layer while still effectively covering burrs and exposed end faces.

[0012] In one possible implementation, the thermoplastic polymer has a dropping melting point of 80°C to 250°C. Thus, during the cutting of the current collector with the second insulating layer, the heat generated during cutting causes the thermoplastic polymer to change from a solid state to a fluid state. This fluidized thermoplastic polymer can flow to the exposed end face of the current collector after cutting and to the burrs generated during cutting, thereby facilitating the preparation of the first insulating layer. Optionally, the dropping melting point of the thermoplastic polymer is 80°C to 150°C, which helps to reduce the energy consumed during the cutting process.

[0013] In one possible implementation, the thermoplastic polymer material includes at least one of a crystalline thermoplastic polymer and an amorphous thermoplastic polymer; optionally, the crystalline thermoplastic polymer includes at least one of polyethylene, polypropylene, and polyamide; optionally, the amorphous thermoplastic polymer includes at least one of microcrystalline wax, polystyrene, and polymethyl methacrylate.

[0014] In the above technical solution, by using the aforementioned thermoplastic polymer, it is beneficial to form a uniform and dense coating on the end face and burrs of the exposed current collector after cutting.

[0015] In one possible implementation, the second insulating layer further includes an adhesive. The addition of the adhesive helps to increase the bond strength between the thermoplastic polymer and the current collector, reducing the risk of the second insulating layer detaching.

[0016] In one possible implementation, the mass ratio A:B of the thermoplastic polymer to the adhesive in the second insulating layer is 60:40 to 80:20; alternatively, the mass ratio A:B of the thermoplastic polymer to the adhesive in the second insulating layer is 70:30 to 80:20.

[0017] In the above technical solution, by reasonably setting the mass ratio of thermoplastic polymer and adhesive in the second insulation layer, it is beneficial to reduce the risk of the second insulation layer falling off, and at the same time, it is beneficial to form a uniform and dense first insulation layer on the exposed end face of the current collector and at the burrs.

[0018] In one possible implementation, the resistance R of the end face where the first insulating layer is provided satisfies: R ≥ 100Ω; alternatively, the resistance R of the end face where the first insulating layer is provided satisfies: R ≥ 2000Ω. By satisfying the above conditions at the end face, the risk of a short circuit in the battery cell caused by the end face contacting an electrode of opposite polarity can be reduced.

[0019] In one possible implementation, the second insulating layer includes a first portion and a second portion, the first portion being disposed on the surface of the transition region, and the second portion extending from the first portion along the first direction and disposed on a portion of the surface of the tab. This reduces the risk of the tab colliding with an electrode of opposite polarity.

[0020] In one possible implementation, the first insulating layer is disposed on the end faces of both ends of the region where the second portion of the tab is located, along a second direction, which is different from the first direction; alternatively, the second direction is perpendicular to the first direction. In this way, the first insulating layer can cover the end faces of the tab exposed due to cutting, reducing the risk of contact between these end faces and electrodes of opposite polarity.

[0021] In one possible implementation, the material of the first insulating layer is the same as the material of the thermoplastic polymer in the second insulating layer. This simplifies the electrode preparation steps and speeds up production.

[0022] In one possible implementation, the thermoplastic polymer in the first insulating layer is in the form of a film, and the thermoplastic polymer in the second insulating layer includes both film-like and particulate thermoplastic polymers. Thus, the first insulating layer is formed by melting and then solidifying the thermoplastic polymer in the second insulating layer. This simplifies the electrode fabrication process, allowing the first insulating layer to be formed simultaneously with cutting.

[0023] In one possible implementation, the current collector comprises a metal foil or a composite current collector; optionally, the metal foil comprises aluminum foil or copper foil; optionally, the composite current collector comprises: a polymer material base layer and a metal layer located on at least one surface of the polymer material base layer; optionally, the current collector comprises aluminum foil. This facilitates the selection of a suitable current collector according to actual needs. When the current collector comprises aluminum foil, the electrode is a positive electrode, which helps reduce the risk of overlap between the positive and negative electrodes, and improves the reliability of the battery cell. Furthermore, it also helps reduce the risk of lithium dendrites overlapping between the positive and negative electrodes.

[0024] Secondly, a method for preparing an electrode is provided, comprising: providing a current collector; coating an active material in a first region of the current collector to form an active material layer; and coating an insulating slurry in a second region of the current collector to form a second insulating layer, wherein the insulating slurry comprises a thermoplastic polymer and a binder, and the thermoplastic polymer has a volume particle size distribution D. V 50 is 6μm to 10μm, and the maximum particle size D of the thermoplastic polymer is... max The thickness is 90μm to 110μm; the current collector with the second insulating layer is cut along the cutting line, and at least part of the cutting line is located in the second region.

[0025] In the above technical solution, by setting the second insulating layer, the first insulating layer can be formed at the same time as cutting, which helps to simplify the preparation steps of the first insulating layer.

[0026] In one possible implementation, the volumetric particle size distribution D of the thermoplastic polymer V 50 is 7μm to 8μm, and the maximum particle size D of the thermoplastic polymer is... max The size is 90μm to 100μm.

[0027] In one possible implementation, the thickness d2 of the second insulating layer is 22 μm to 48 μm; alternatively, the thickness d2 of the second insulating layer is 22 μm to 30 μm.

[0028] In one possible implementation, the thermoplastic polymer has a dropping melting point of 80°C to 250°C; alternatively, the thermoplastic polymer has a dropping melting point of 80°C to 150°C.

[0029] In one possible implementation, the thermoplastic polymer material includes at least one of a crystalline thermoplastic polymer and an amorphous thermoplastic polymer; optionally, the crystalline thermoplastic polymer includes at least one of polyethylene, polypropylene, and polyamide; optionally, the amorphous thermoplastic polymer includes at least one of microcrystalline wax, polystyrene, and polymethyl methacrylate.

[0030] In one possible implementation, the mass ratio A:B of the thermoplastic polymer to the binder in the insulating slurry is 60:40 to 80:20; alternatively, in the second insulating layer, the mass ratio A:B of the thermoplastic polymer to the binder is 70:30 to 80:20.

[0031] In one possible implementation, cutting the current collector with the second insulating layer along the cutting line includes: controlling a laser processing tool to cut the current collector with the second insulating layer along the cutting line.

[0032] In the above technical solution, the current collector is cut by laser. The cutting process can generate more heat, which is beneficial for the thermoplastic polymer in the second insulating layer to become fluid and flow to the end face, thereby facilitating the formation of the first insulating layer.

[0033] Thirdly, a battery cell is provided, comprising an electrode as described in the first aspect and any possible implementation thereof, and / or an electrode prepared by a method as described in the second aspect and any possible implementation thereof.

[0034] Fourthly, a battery is provided, comprising the battery cell described in the third aspect.

[0035] Fifthly, an electrical device is provided, comprising the battery described in the fourth aspect. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the electrode sheet before the processing of the electrode tab according to an embodiment of this application;

[0038] Figure 2 This is a schematic diagram of an electrode sheet according to an embodiment of this application;

[0039] Figure 3 for Figure 2 A cross-sectional view along the AA direction;

[0040] Figure 4 for Figure 2 A cross-sectional view along the BB direction;

[0041] Figure 5 This is a schematic diagram of a method for preparing an electrode sheet according to an embodiment of this application;

[0042] Figure 6 This is a schematic diagram of a current collector according to an embodiment of this application;

[0043] Figure 7 A schematic diagram of a current collector coated with an active material layer according to an embodiment of this application;

[0044] Figure 8 This is a schematic diagram of a current collector coated with a second insulating layer according to an embodiment of this application;

[0045] Figure 9 This is a schematic diagram illustrating the current collector of the cutting line according to an embodiment of this application;

[0046] Figure 10 This is a schematic diagram of a battery cell according to an embodiment of this application;

[0047] Figure 11 This is a schematic diagram of a battery according to an embodiment of this application;

[0048] Figure 12 This is a schematic diagram of an electrical device according to an embodiment of this application;

[0049] Figure 13 This is a SEM image of the end face with a first insulating layer according to an embodiment of this application.

[0050] Figure label:

[0051] 1: Electrode; 124: Cutting line; 10: Current collector; 11: Active material layer; 121: First insulating layer; 122: Second insulating layer; 101: Main body; 102: Tab; 1011: Coated area; 1012: Transition area; 1011a: End face; 1221: First part; 1222: Second part. Detailed Implementation

[0052] The embodiments of the electrode sheet and its preparation method, battery cell, battery, and power-consuming device of this application are disclosed in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0053] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0054] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0055] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0056] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0057] Unless otherwise specified, the terms "comprising" and "including" as used in this application are open-ended. For example, "comprising" and "including" may include or include other components not listed.

[0058] Unless otherwise specified, the term "and / or" is inclusive in this application. For example, the phrase "A and / or B" means "A, B, or both A and B". More specifically, the condition "A and / or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0059] The development of battery technology must consider multiple design factors simultaneously, such as energy density, cycle life, discharge capacity, charge / discharge rate, and reliability. The design of the electrodes within a single battery cell is crucial to its reliability. Electrodes typically consist of a current collector and active material layers and insulating layers coated on different areas of the current collector. After coating the current collector with the appropriate active material and insulating layers, it needs to be cut to create the tabs. During this cutting process, dust and burrs are easily generated. These burrs may cause the electrode to overlap with an electrode of opposite polarity, leading to a short circuit.

[0060] In some processing methods, the insulating layer coated on the current collector is a ceramic coating to reduce burrs generated during the cutting process. However, this method only reduces the number of burrs; burrs will still exist after cutting. These burrs may cause the electrode to overlap with the electrode of opposite polarity, resulting in adverse effects. Furthermore, the end face of the current collector is exposed after cutting, posing a risk of overlap with the electrode of opposite polarity, which could lead to a short circuit in the battery cell and negatively impact battery reliability.

[0061] To further improve the reliability of individual battery cells, an insulating layer comprising a thermoplastic polymer is coated on a specific area of ​​the current collector. The cutting line is located in the area containing the insulating layer. During the cutting of the current collector to prepare the tab, the thermoplastic polymer in the insulating layer changes from a solid to a fluid state upon heating, flowing to the end face of the cut current collector and solidifying at the end face upon cooling to form a new insulating layer. This new insulating layer at the end face can cover the burrs generated during cutting and the exposed end face after cutting; however, the uniformity and density of the newly formed insulating layer are relatively poor, resulting in a limited improvement in the reliability of the individual battery cells.

[0062] In view of this, this application provides an electrode. In this electrode, a specific area of ​​the current collector is coated with an insulating layer, and the volume particle size distribution D of the thermoplastic polymer in the insulating layer is... V 50 represents the maximum particle size D of thermoplastic polymers, ranging from 6μm to 10μm. maxThe particle size is 90μm to 110μm. This gives the thermoplastic polymer a suitable particle size, which can reduce the agglomeration of the thermoplastic polymer during the coating of the insulating layer. During the cutting of the tabs, the thermoplastic polymer changes from a solid state to a fluid state, and has a suitable flow path, which is conducive to forming a uniform and dense insulating coating layer at the end face, thereby improving the reliability of the battery cell.

[0063] [Extreme Film]

[0064] Figure 1 This is a schematic diagram of the electrode sheet before the electrode tab is processed according to an embodiment of this application. Figure 2 This is a schematic diagram of an electrode sheet according to an embodiment of this application. Figure 3 for Figure 2 A cross-sectional view along the AA direction. Figure 4 for Figure 2 A cross-sectional view along the BB direction.

[0065] Combination Figure 1 and Figure 2 As shown, Figure 1 This is a schematic diagram of the electrode sheet before the tab is processed. Figure 2 This is a schematic diagram showing the electrode after the tabs have been processed. (Example:) Figure 1 As shown, the black dashed line 124 is the cutting line for cutting the tabs. After cutting along the cutting line 124, the result is as follows: Figure 2 Electrode 1 is shown.

[0066] Combination Figures 1 to 4 As shown, the electrode 1 includes a current collector 10, an active material layer 11, a first insulating layer 121, and a second insulating layer 122.

[0067] The current collector 10 has two opposing surfaces along its thickness direction, and the active material layer 11 can be disposed on at least one of the opposing surfaces along the thickness direction of the current collector 10. For example, as Figure 3 and Figure 4 As shown, active material layers 11 are provided on both opposite surfaces of the current collector 10 along its thickness direction.

[0068] The thickness direction of the current collector 10 can be Figure 3 and Figure 4 The z-direction is shown.

[0069] The current collector 10 includes a main body 101 and a tab 102, wherein the tab 102 extends from a first end of the main body 101, and the first end of the main body 101 is one end of the main body 101 along a first direction.

[0070] The first direction is parallel to the plane where the current collector 10 is located, and the first direction is the direction in which the tab 102 protrudes relative to the main body 101. For example, the first direction is... Figure 2y direction in .

[0071] The main body 101 includes a coating area 1011 and a transition area 1012, with the transition area 1012 disposed between the coating area 1011 and the tab 102.

[0072] An active material layer 11 is disposed on the surface of the coating area 1011. For example, such as... Figure 3 and Figure 4 As shown, the active material layer 11 is disposed on two surfaces of the current collector 10 in the thickness direction. In some embodiments, the active material layer 11 may be disposed on one of the two surfaces of the current collector 10 in the thickness direction.

[0073] The first insulating layer 121 is disposed on the end face 1011a of the main body 101 at the first end.

[0074] The end face 1011a of the main body 101 at the first end is a surface parallel to the thickness direction of the current collector 10. For example, as Figure 3 As shown, end face 1011a is a surface parallel to the x and z directions.

[0075] The end face 1011a of the main body 101 at the first end can be formed through the following process: (Refer to...) Figure 1 As shown, during the cutting process of the current collector 10, it is cut along the cutting line 124, and the end face 1011a is the cut end face of the transition zone 1012. After cutting, the current collector 10 at the end face 1011a is exposed, and burrs may be generated.

[0076] By providing a first insulating layer 121 at the end face 1011a, the first insulating layer 121 can cover the burrs generated during the cutting process, reducing the risk of burrs overlapping with electrodes of opposite polarity. For example, after assembling electrode 1 with electrodes of opposite polarity (e.g., electrode 1 is a positive electrode, and the electrode of opposite polarity is a negative electrode) into an electrode assembly by winding or stacking, and then assembling the electrode assembly with the end cap assembly and the housing into a battery cell, the burrs may overlap with the electrodes of opposite polarity. By providing the first insulating layer 121, the first insulating layer 121 can cover the burrs, thereby reducing the risk of burrs overlapping with electrodes of opposite polarity.

[0077] By providing a first insulating layer 121 at the end face 1011a, the first insulating layer 121 can cover the exposed end face 1011a of the current collector 10 after cutting, thereby reducing the risk of the end face 1011a colliding with an electrode of opposite polarity. For example, if the electrode 1 is a positive electrode, the provision of the first insulating layer 121 can reduce the risk of internal short circuit of the battery cell caused by the electrode 1 colliding with the negative electrode.

[0078] At least a portion of the second insulating layer 122 is disposed on the surface of the transition region 1012. That is, the surface of the transition region 1012 is provided with the second insulating layer 122, and other areas of the current collector 10 besides the transition region 1012 may also be provided with the second insulating layer 122. By providing the second insulating layer 122 in the transition region 1012, it is beneficial to reduce the risk of the electrode 1 overlapping with an electrode 1 of opposite polarity.

[0079] The second insulating layer 122 comprises a thermoplastic polymer, the thermoplastic polymer having a volume particle size distribution D V 50 represents the maximum particle size D of thermoplastic polymers, ranging from 6μm to 10μm. max The median particle size is 90 μm to 110 μm. For example, the median particle size D of thermoplastic polymers... V 50 has a particle size of 6 μm and a maximum particle size of D. max It is 90μm; for example, D V 50 is 8μm, D max It is 100μm; for example, D V 50 is 10μm, D max It is 110 μm. As long as D V 50 and D max The above conditions must be met; the embodiments of this application include, but are not limited to, these.

[0080] Optionally, the volumetric particle size distribution D of the thermoplastic polymer V 50 and maximum particle size D max Correspondingly. For example, due to limitations in the preparation process of thermoplastic polymers, the volumetric particle size distribution D of thermoplastic polymers... V When 50 is 6 μm, the maximum particle size D of the thermoplastic polymer is... max It is 90μm.

[0081] Thermoplastic polymers can refer to polymers that soften upon heating, solidify upon cooling, and can soften again. For example, when heated to a certain temperature, thermoplastic polymers change from solid particles to a flowable state, and when cooled, they can become layered or film-like thermoplastic polymers.

[0082] When heated to a certain temperature, the thermoplastic polymer in the second insulating layer 122 changes from a solid state to a fluid state. Thus, during the cutting process of the current collector 10 with the second insulating layer 122, the fluid thermoplastic polymer can flow to the burrs and exposed end faces 1011a. After the temperature drops, the fluid thermoplastic polymer solidifies at the burrs and exposed end faces 1011a, thereby covering the burrs and exposed end faces 1011a, which can reduce the risk of the burrs and exposed end faces 1011a overlapping with electrodes of opposite polarity.

[0083] Volumetric particle size distribution Dv 50 can refer to the particle size corresponding to a sample when the cumulative volume distribution percentage reaches 50%.

[0084] When the particle size of the thermoplastic polymer is too small, the distribution of the thermoplastic polymer is uneven when it is prepared into a slurry and coated onto the current collector 10, and the thermoplastic polymer is prone to agglomeration. After the slurry forms the second insulating layer 122, during the die-cutting process, the agglomerated thermoplastic polymer has a long flow path in the flow state, which is not conducive to the formation of a uniform and dense first insulating layer 121 at the end face 1011a.

[0085] When the particle size of the thermoplastic polymer is too large, the large particle size thermoplastic polymer has a long flow path after changing from solid to fluid state, which is not conducive to the formation of a uniform and dense first insulating layer 121 at the end face 1011a.

[0086] By setting the particle size of the thermoplastic polymer appropriately, it is beneficial to reduce the agglomeration of the thermoplastic polymer during the preparation process, and to form a uniform and dense first insulating layer 121 at the end face 1011a.

[0087] This application provides an electrode 1, which includes a current collector 10, an active material layer 11, a first insulating layer 121, and a second insulating layer 122. The current collector 10 includes a main body 101 and a tab 102, with the tab 102 extending from a first end of the main body 101, which is one end of the main body 101 along a first direction. The main body 101 includes a coating area 1011 and a transition area 1012, with the transition area 1012 disposed between the coating area 1011 and the tab 102. The coating area 1011 is provided with the active material layer 11. Thus, by providing the transition area 1012, during the cutting of the tab 102, the cutting tool can maintain a certain distance from the active material layer 11, reducing the shedding of the active material layer 11. A first insulating layer 121 is disposed on the end face 1011a at the first end of the main body 101. This allows the first insulating layer 121 to cover the end face 1011a at the first end, reducing the risk of the current collector 10 being exposed at the end face 1011a, thereby reducing the risk of the exposed current collector 10 at the end face 1011a contacting an electrode of opposite polarity. Furthermore, the first insulating layer 121 can also cover burrs generated during the cutting process, reducing the risk of burrs contacting an electrode of opposite polarity. At least a portion of a second insulating layer 122 is disposed on the surface of the transition region 1012. The second insulating layer 122 comprises a thermoplastic polymer. Thus, with the cutting line located in the transition region 1012, during the cutting of the tab 102, the thermoplastic polymer in the second insulating layer 122 on the surface of the transition region 1012 changes from a solid state to a fluid state upon heating. The fluid thermoplastic polymer flows to the end face 1011a at the first end and solidifies at the end face 1011a after cooling. Volumetric particle size distribution D of thermoplastic polymers V 50 is 6μm to 10μm, and the maximum particle size D of the thermoplastic polymer is... max With a particle size of 90μm to 110μm, the thermoplastic polymer is less prone to agglomeration by appropriately setting its particle size. Furthermore, after heating, the thermoplastic polymer exhibits a suitable flow path, which facilitates the formation of a uniform and dense first insulating layer 121 at the end face 1011a, thereby enabling uniform and dense coating of the end face. Therefore, the technical solution of this application embodiment can improve the uniformity and density of the first insulating layer 121, thereby further improving the reliability of the battery cell.

[0088] In some embodiments, the volumetric particle size distribution D of the thermoplastic polymer V 50 is 7μm to 8μm, and the maximum particle size D of the thermoplastic polymer is... max The thickness is 90μm to 100μm. In this way, the thermoplastic polymer is not prone to agglomeration, and after being heated from a solid state to a fluid state, it has a more suitable flow path, which is conducive to the formation of a uniform and dense first insulating layer 121 at the end face.

[0089] In some embodiments, the thickness d2 of the second insulating layer 122 is 22 μm to 48 μm. For example, d2 is 22 μm, 25 μm, 30 μm, 40 μm, 45 μm, 48 μm or any value within the above range.

[0090] The thickness d2 of the second insulating layer 122 refers to the thickness of one side surface of the current collector 10. In the electrode 1, the total thickness of the second insulating layer 122 along the thickness direction of the electrode 1 is 44 μm to 96 μm.

[0091] The thickness d2 of the second insulating layer 122 is the average thickness of the second insulating layer 122 along the thickness direction of the current collector 10. For example, the thickness d2 is the average of the maximum and minimum dimensions in the first direction.

[0092] When the thickness d2 of the second insulating layer 122 is not less than 22 μm, during the cutting process of the current collector 10 provided with the second insulating layer 122, there is a large amount of thermoplastic polymer in the second insulating layer 122. As a result, the large amount of thermoplastic polymer can flow to the burrs and the exposed end face 1011a of the current collector 10 after being heated, which is beneficial to uniformly and densely cover the exposed end face 1011a and the burrs.

[0093] When the thickness d2 of the second insulating layer 122 does not exceed 48 μm, it is beneficial to reduce the energy consumed during the cutting process.

[0094] Optionally, the thickness d2 of the second insulating layer 122 is 20μm to 30μm, which can improve the coverage of the exposed end face 1011a and burrs while reducing the energy consumed in cutting.

[0095] The thickness d2 of the second insulating layer 122 can be measured by taking an image of the electrode 1 along the thickness direction of the electrode 1 using a scanning electron microscope, and measuring the thickness d2 of the second insulating layer 122 based on the obtained image.

[0096] Optionally, the thickness of the second insulating layer 122 is 20 μm to 50 μm, for example, 20 μm, 50 μm or any value within the above range.

[0097] In some embodiments, the thickness d1 of the first insulating layer 121 is 300 nm to 1800 nm. For example, d1 can be 300 nm, 400 nm, 500 nm, 800 nm, 1000 nm, 1500 nm, 1800 nm or any value within the above range.

[0098] The smaller the thickness d1 of the first insulating layer 121, the smaller the space occupied by the electrode 1, which is beneficial to improving the volumetric energy density of the battery cell. By setting the thickness d1 of the first insulating layer 121 to 300nm~1800nm, the first insulating layer 121 can better cover burrs and exposed end faces 1011a with a smaller thickness, which is beneficial to further improving the performance of the battery cell.

[0099] The thickness d1 of the first insulating layer 121 is the average thickness of the first insulating layer 121 along the first direction. For example, the thickness d1 is the average of the maximum and minimum dimensions in the first direction.

[0100] The thickness d1 of the first insulating layer 121 can be measured by taking an image of the end face 1011a of the electrode 1 using a scanning electron microscope and measuring the thickness d1 of the first insulating layer 121 from the obtained image.

[0101] Optionally, the thickness d1 of the first insulating layer 121 is 300 nm to 860 nm. This is beneficial for better covering of burrs and exposed end faces 1011a while further reducing the thickness of the first insulating layer 121.

[0102] Optionally, the thickness d1 of the first insulating layer 121 is 200 nm to 2000 nm. For example, d1 can be 200 nm, 2000 nm, or any value within the above range.

[0103] In some embodiments, the dropping melting point of the thermoplastic polymer is 80°C to 250°C. For example, the dropping melting point of the thermoplastic polymer is 80°C, 100°C, 150°C, 200°C, 250°C, or any value within the above range.

[0104] The thermoplastic polymer has a dropping melting point of not less than 80°C, which reduces the risk of the thermoplastic polymer melting or flowing due to heating of the electrode 1 during other processing. The thermoplastic polymer has a dropping melting point of not more than 250°C, which reduces the risk that the thermoplastic polymer cannot be transformed into a flowable state during the cutting process, thereby reducing the risk that the first insulating layer 121 cannot be formed at the end face 1011a.

[0105] The dropping melting point of a thermoplastic polymer is the temperature at which the thermoplastic polymer changes from a solid or semi-solid state to a liquid state.

[0106] During the process of cutting the current collector 10 with the second insulating layer 122, the thermoplastic polymer changes from solid to fluid under the action of the heat generated by the cutting. The fluid thermoplastic polymer can flow to the end face 1011a of the current collector 10 exposed after cutting and the burrs generated by cutting, thereby facilitating the preparation of the first insulating layer 121.

[0107] Optionally, the thermoplastic polymer has a dropping melting point of 80°C to 150°C, which helps to reduce the energy consumed in the cutting process.

[0108] Optionally, the thermoplastic polymer has a dropping melting point of 150°C to 250°C, which can reduce the risk that the thermoplastic polymer may become fluid due to other factors during the process of uncutterd current collector 10.

[0109] In some embodiments, the thermoplastic polymer material includes at least one of crystalline thermoplastic polymer and amorphous thermoplastic polymer; optionally, the crystalline thermoplastic polymer includes at least one of polyethylene, polypropylene, and polyamide; optionally, the amorphous thermoplastic polymer includes at least one of microcrystalline wax, polystyrene, and polymethyl methacrylate.

[0110] The dropping point of a crystalline thermoplastic polymer can refer to its melting point. The dropping point of an amorphous thermoplastic polymer can refer to its glass transition temperature.

[0111] In the above technical solution, by using the aforementioned thermoplastic polymer, it is beneficial to form a uniform and dense coating on the exposed end face 1011a and burrs of the cut current collector 10. Furthermore, the aforementioned thermoplastic polymer has high insulation and voltage resistance; when the electrode 1 is immersed in the electrolyte, the thermoplastic polymer will not undergo an electrochemical reaction with the electrolyte.

[0112] In some embodiments, the material of the second insulating layer 122 further includes an adhesive.

[0113] The adhesive in the second insulating layer 122 facilitates the bonding of the thermoplastic polymer to the transition region 1012, which can reduce the risk of the second insulating layer 122 falling off from the transition region 1012.

[0114] In some embodiments, in the second insulating layer 122, the mass ratio A:B of the thermoplastic polymer to the adhesive is 60:40 to 80:20. For example, A:B is 60:40, 70:30, 75:25, 80:20, or any value within the above range.

[0115] In the above technical solution, by reasonably setting the mass ratio of thermoplastic polymer and adhesive in the second insulating layer 122, it is beneficial to reduce the risk of the second insulating layer 122 falling off, and at the same time, it is beneficial to form a uniform and dense first insulating layer 121 on the exposed end face 1011a of the current collector 10 and at the burrs.

[0116] Optionally, in the second insulating layer 122, the mass ratio A:B of the thermoplastic polymer to the adhesive is 70:30 to 80:20.

[0117] In some embodiments, the resistance R of the end face 1011a on which the first insulating layer 121 is provided satisfies: R ≥ 100Ω. For example, R is 100Ω, 500Ω, or 1000Ω.

[0118] When the resistance of end face 1011a is greater than 100Ω, even in some extreme cases where end face 1011a is connected to an electrode with opposite polarity, the battery cell will not experience an internal short circuit due to the resistance of end face 1011a. This can reduce the risk of fire or even explosion caused by internal short circuit.

[0119] Optionally, the resistance R of the end face 1011a with the first insulating layer 121 satisfies: R ≥ 2000Ω. For example, R can be 200Ω, 5000Ω, or infinite. This can further reduce the risk of internal short circuits in individual battery cells.

[0120] In some embodiments, the second insulating layer 122 includes a first portion 1221 and a second portion 1222. The first portion 1221 is disposed on the surface of the transition region 1012, and the second portion 1222 extends from the first portion 1221 along a first direction and is disposed on a portion of the surface of the tab 102. This reduces the risk of the tab 102 colliding with an electrode of opposite polarity.

[0121] A portion of the second insulating layer 122 is provided in a certain area of ​​the tab 102, while other areas are not provided with the second portion 1222. This facilitates the welding of the tab 102 and the subsequent use of the battery cell.

[0122] In some embodiments, along a second direction, the end faces 1222a of the region where the second portion 1222 of the tab 102 is provided with a first insulating layer 121 at both ends, and the second direction is different from the first direction.

[0123] When the electrode 1 includes multiple tabs 102, the second direction can be the arrangement direction of the multiple tabs 102. For example, as Figure 2 As shown, the second direction is the x-direction.

[0124] During the process of cutting the current collector 10 along the cutting line 124 to prepare the tab 102, the cutting tool passes through the area of ​​the second part 1222. After cutting, the end face 1222a of this area along the second direction is exposed. By providing a first insulating layer 121 at this end face 1222a, the risk of this end face 1222a overlapping with an electrode of opposite polarity can be reduced.

[0125] The first insulating layer 121 provided on the end faces 1222a at both ends of the region of the second part 1222 is formed during the cutting of the current collector 10.

[0126] Optionally, the second direction is perpendicular to the first direction. This facilitates the cutting of the tab 102.

[0127] In some embodiments, the material of the first insulating layer 121 is the same as the material of the thermoplastic polymer in the second insulating layer 122. This simplifies the preparation steps of the electrode 1.

[0128] For example, an active material layer 11 and a second insulating layer 122 are first prepared on the current collector 10, and a first insulating layer 121 is prepared simultaneously during the cutting process. In this way, the tab 102 can be generated in a single cutting step, and the first insulating layer 121 can be prepared at the same time.

[0129] In some embodiments, the thermoplastic polymer in the first insulating layer 121 is in the form of a film, and the thermoplastic polymer in the second insulating layer 122 includes both film-like and particulate thermoplastic polymers. Thus, the first insulating layer 121 is formed by melting and then solidifying the thermoplastic polymer in the second insulating layer 122. In this way, the thermoplastic polymer in the second insulating layer 122 becomes fluid and flows to the end face 1011a, where it solidifies to form the first insulating layer 121. This simplifies the preparation steps of the electrode 1, allowing the first insulating layer 121 to be formed simultaneously with the cutting and preparation of the electrode tab 102.

[0130] In the second insulating layer 122, at least some particulate thermoplastic polymer is retained; in the first insulating layer 121, the thermoplastic polymer is in the form of a film and has almost no particulate shape.

[0131] Particulate thermoplastic polymers can take on various shapes, such as spheres, rods, and sheets. Here, "particulate thermoplastic polymer" refers to a thermoplastic polymer that is not in a fluid state, but rather in a solid state.

[0132] Before the second insulating layer 122 is cut, the thermoplastic polymer in the second insulating layer 122 is in granular form. During the cutting process of the second insulating layer 122, part of the thermoplastic polymer in the second insulating layer 122 changes from solid to fluid (for example, the thermoplastic polymer near the cutting line 124 becomes fluid), while the other part of the thermoplastic polymer remains solid granules.

[0133] In some embodiments, the current collector 10 comprises a metal foil or a composite current collector. This allows for the selection of the material of the current collector 10 according to actual needs.

[0134] Alternatively, the metal foil may include aluminum foil or copper foil.

[0135] Optionally, the composite current collector includes: a polymer material base layer and a metal layer located on at least one surface of the polymer material base layer.

[0136] Optionally, the current collector includes aluminum foil. In this way, electrode 1 is a positive electrode, which helps reduce the risk of overlap between the positive and negative electrodes, and improves the reliability of the battery cell. Furthermore, it also helps reduce the risk of lithium dendrites from precipitating on the positive and negative electrodes overlapping.

[0137] The above text combined Figures 1 to 4 The technical solution for the electrode sheet has been explained. The following section will combine... Figure 5 The preparation method of the electrode is described. The parts corresponding to the electrode can be referred to above, and will not be repeated here.

[0138] [Preparation methods for electrode sheets]

[0139] Figure 5 This is a schematic diagram of a method for preparing an electrode sheet according to an embodiment of this application. Method 200 can be used to prepare the electrode sheet 1 in the above embodiment. Method 200 includes the following steps.

[0140] Step 210, provide current collector 10.

[0141] Figure 6 This is a schematic diagram of a current collector according to an embodiment of this application. For example, such as... Figure 6 As shown, the current collector 10 is in the shape of a sheet or a rectangle. The shape and size of the current collector 10 can be set according to actual needs, and the embodiments of this application include, but are not limited to, these.

[0142] Step 220: Coat the first region of the current collector 10 with an active material to form an active material layer 11.

[0143] Figure 7 This is a schematic diagram of a current collector coated with an active material layer according to an embodiment of this application. Figure 7 As shown, an active material is coated in the first region of the current collector 10 to obtain a current collector 10 with an active material layer 11.

[0144] The first region of the current collector 10 can be a region set according to actual needs. In the embodiment of this application, the first region corresponds to the coating area 1011 of the main body portion 101 of the electrode 1.

[0145] Step 230: Apply insulating paste to the second region of the current collector 10 to form a second insulating layer 122.

[0146] The insulating paste includes thermoplastic polymers and binders, and the volumetric particle size distribution D of the thermoplastic polymers is... V 50 represents the maximum particle size D of thermoplastic polymers, ranging from 6μm to 10μm. max The size ranges from 90μm to 110μm.

[0147] Figure 8This is a schematic diagram of a current collector coated with a second insulating layer according to an embodiment of this application. Figure 8 As shown, an insulating paste is coated on the second region of the current collector 10 to obtain a current collector 10 with a second insulating layer 122.

[0148] The size of the second region can be set according to actual needs. In the embodiment of this application, the second region corresponds to the transition region 1012 of the main body portion 101 of the electrode 1 and the region of the tab 102 where the second insulating layer 122 is provided.

[0149] Step 240: Cut the current collector 10 with the second insulating layer 122 along the cutting line 124, with at least a portion of the cutting line 124 located in the second region.

[0150] Figure 9 This is a schematic diagram illustrating the current collector for the cutting line according to an embodiment of this application. Figure 9 As shown, the current collector 10 is cut along the cutting line 124, thereby obtaining... Figures 2 to 4 Electrode 1 is shown.

[0151] In the above technical solution, by setting the second insulating layer 122, the first insulating layer 121 can be formed simultaneously with the cutting process, which simplifies the preparation steps of the first insulating layer 121. The electrode 1 prepared by the above method, when applied to a battery cell, can improve the reliability of the battery cell.

[0152] In some embodiments, the volumetric particle size distribution D of the thermoplastic polymer V 50 is 7μm to 8μm, and the maximum particle size D of the thermoplastic polymer is... max The size is 90μm to 100μm.

[0153] In some embodiments, the thickness d2 of the second insulating layer 122 is 22 μm to 48 μm; optionally, d2 is 22 μm to 30 μm.

[0154] In some embodiments, the dropping melting point of the thermoplastic polymer is 80°C to 250°C; alternatively, the dropping melting point of the thermoplastic polymer is 80°C to 150°C.

[0155] In some embodiments, the thermoplastic polymer material includes at least one of crystalline thermoplastic polymer and amorphous thermoplastic polymer; optionally, the crystalline thermoplastic polymer includes at least one of polyethylene, polypropylene, and polyamide; optionally, the amorphous thermoplastic polymer includes at least one of microcrystalline wax, polystyrene, and polymethyl methacrylate.

[0156] In some embodiments, the mass ratio A:B of the thermoplastic polymer to the binder in the insulating slurry is 60:40 to 80:20; optionally, in the second insulating layer 122, the mass ratio A:B of the thermoplastic polymer to the binder is 70:30 to 80:20.

[0157] In some embodiments, step 240 includes controlling a laser processing tool to cut the current collector 10, which is provided with the second insulating layer 122, along the cutting line. As an example, the laser processing tool has a power of 200W, a frequency of 200kHz, and a feed rate of 30m / min.

[0158] In this embodiment, the laser operating parameters can be adjusted according to the melting point of the thermoplastic polymer, the thickness of the second insulating layer 122, etc. For example, if the melting point of the thermoplastic polymer is high or the second insulating layer 122 is thick, the power or frequency can be increased, or the feed rate can be decreased. Alternatively, cutting parameters suitable for all situations (e.g., suitable for thermoplastic polymers with various melting points) can be selected to cut the current collector 10.

[0159] In the above technical solution, laser cutting is used, which generates more heat during the cutting process. This helps the thermoplastic polymer in the second insulating layer 122 to become fluid and flow to the end face 1011a, thereby facilitating the formation of the first insulating layer 121.

[0160] [Positive electrode plate]

[0161] In this embodiment, the electrode 1 can be a positive electrode. The positive electrode includes a positive current collector and a positive electrode film layer disposed on the positive current collector.

[0162] The positive electrode current collector can be a metal foil or a composite current collector. For example, the positive electrode current collector can be an aluminum foil.

[0163] Composite current collectors may include a polymeric material substrate and a metal layer formed on at least one surface of the polymeric material substrate. Composite current collectors can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0164] The positive electrode film includes a positive electrode active material. This positive electrode active material can be any known battery-grade positive electrode active material. For example, it could be lithium iron phosphate, ternary materials, or lithium-rich manganese-based materials.

[0165] The positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0166] The positive electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0167] [Negative electrode plate]

[0168] In this embodiment, the electrode 1 can be a negative electrode. The negative electrode includes a negative current collector and a negative electrode film layer disposed on the negative current collector.

[0169] The negative electrode current collector can be a metal foil or a composite current collector. The negative electrode current collector can be copper foil. Composite current collectors can be formed by depositing metallic materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) onto a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0170] The negative electrode film layer includes a negative electrode active material. The negative electrode active material can be any negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0171] The negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0172] [Electrolytes]

[0173] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel-like, or entirely solid.

[0174] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0175] The electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0176] Solvents may include at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0177] The electrolyte may also optionally include negative electrode film-forming additives, positive electrode film-forming additives, and performance additives that can improve certain battery performance, such as performance additives that improve battery overcharge performance, battery high temperature or low temperature performance, etc.

[0178] [Isolation membrane]

[0179] The separator is used to separate the positive electrode and the negative electrode. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0180] The material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film; there are no particular restrictions. When the separator is a multi-layer composite film, the materials of each layer can be the same or different; there are no particular restrictions.

[0181] Positive electrode, negative electrode and separator can be made into electrode assembly by winding process or stacking process.

[0182] [Battery cell]

[0183] This application provides a battery cell including the electrode 1 in the above embodiments.

[0184] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. The battery cell can be a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery, a magnesium-ion battery, etc.

[0185] Figure 10 This is a schematic diagram of a battery cell according to an embodiment of this application. For example, such as... Figure 10As shown, the battery cell 3 is a square battery cell. The battery cell 3 includes a housing 31, an end cap assembly 32, and an electrode assembly 33 disposed in the housing 31.

[0186] The electrode assembly 33 can be manufactured by a winding process or a stacking process from a positive electrode sheet, a negative electrode sheet, and a separator. In some embodiments, the positive electrode sheet is electrode sheet 1 in the embodiments of this application.

[0187] End cap assembly 32 includes electrode terminals 322, such as... Figure 10 As shown, the end cap assembly 32 includes two electrode terminals 322, one of which is a positive electrode terminal and the other is a negative electrode terminal.

[0188] The battery cell 3 also includes a current collector 34, which is used to connect the tab 331 of the electrode assembly 33 and the electrode terminal 322. For example, in the case that the electrode 1 in this embodiment is a positive electrode, one current collector 34 is used to connect the positive electrode tab (which may also be the tab 102 of the electrode 1) and the positive electrode terminal, and another current collector 34 is used to connect the negative electrode tab and the negative electrode terminal.

[0189] In some embodiments, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0190] [Battery]

[0191] This application provides a battery, including the battery cell described in the above embodiments. Figure 11 This is a schematic diagram of a battery according to an embodiment of this application. Figure 11 As shown, battery 5 may include multiple battery cells (not shown in the figure).

[0192] Battery cells 3 can be directly assembled into battery 5, or they can be first assembled into battery modules, and then multiple battery modules can be assembled into battery 5.

[0193] [Electrical appliances]

[0194] This application provides an electrical device, including the battery described in the above embodiments.

[0195] Figure 12 This is a schematic diagram of an electrical device according to an embodiment of this application. Figure 12 As shown, this application provides an electrical device 6, which includes the battery in the above embodiment.

[0196] Alternatively, the electrical device may also be an energy storage device, a lighting device, a spacecraft, etc., as is the case in the embodiments of this application.

[0197] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0198] [Example]

[0199] Example 1

[0200] The electrode in Example 1 has the following characteristics: Figure 2 The structure is shown. In Example 1, the volumetric particle size distribution D of the thermoplastic polymer in the second insulating layer is... V 50 has a particle size of 6 μm and a maximum particle size D. max The thickness of the first insulating layer is 90 μm, and the thermoplastic polymer material is microcrystalline wax with a dropping melting point of 80℃. The thickness d2 of the second insulating layer is 30 μm, and the thickness d1 of the first insulating layer is 860 nm. In the second insulating layer, the mass ratio A:B of the thermoplastic polymer is 80:20.

[0201] Examples 2-5

[0202] The difference between Examples 2-5 and Example 1 lies in the volumetric particle size distribution D of the thermoplastic polymer in the second insulating layer. V 50 and maximum particle size D max They are different. Specific parameters are shown in Table 1.

[0203] Examples 6-9

[0204] The difference between Examples 6-9 and Example 1 is that the thickness of the second insulating layer is different. Accordingly, as the thickness of the second insulating layer changes, the thickness of the first insulating layer and the resistance of the end face also change.

[0205] Examples 10-12

[0206] The difference between Examples 10-12 and Example 1 lies in the materials of the thermoplastic polymers. Consequently, the dropping melting points of the thermoplastic polymers are different. In this example, PTFE is polytetrafluoroethylene.

[0207] Examples 13-14

[0208] The difference between Examples 13-14 and Example 1 is that the mass ratio of thermoplastic polymer to binder is different in the second insulating layer.

[0209] Comparative Example 1

[0210] The difference between Comparative Example 1 and Example 1 is that the material of the second insulating layer does not include thermoplastic polymers, and the material in the second insulating layer includes boehmite.

[0211] Comparative Examples 2-3

[0212] The difference between Comparative Examples 2-3 and Example 12 is that the volumetric particle size distribution D of the thermoplastic polymer in the second insulating layer is... V 50 and maximum particle size D max different.

[0213] Comparative Examples 4-6

[0214] The difference between Comparative Examples 4-6 and Example 1 lies in the volumetric particle size distribution D of the thermoplastic polymer in the second insulating layer. V 50 and maximum particle size D max different.

[0215] Table 1. Parameters of the Examples and Comparative Examples

[0216]

[0217]

[0218] Table 2. Experimental results for comparative and example cases.

[0219]

[0220] [Preparation of battery cells]

[0221] (1) Prepare the slurry for the second insulating coating.

[0222] The thermoplastic polymer and binder were mixed in a certain proportion, and a solvent was added and stirred until homogeneous. The viscosity of the slurry was approximately 3000 mPa·s. The binder was polyvinylidene fluoride (PVDF), and the solvent was N-methylpyrrolidone. Specific thermoplastic polymers and their ratios to binders are shown in Table 1.

[0223] (2) Coating and drying

[0224] When the positive electrode active slurry is coated onto the aluminum foil, an active material layer is prepared; the above-mentioned insulating coating slurry is then coated onto the aluminum foil with a coating width of 3 mm. After drying in an oven at 100°C, the thickness of the second insulating layer after drying is shown in Table 1. Here, the thickness of the second insulating layer refers to the thickness of the second insulating layer on one side of the current collector.

[0225] (3) Laser die cutting

[0226] The above products are die-cut. See Table 1 for specific process parameters.

[0227] (4) Manufacturing battery cells

[0228] The above-mentioned positive electrode sheet is assembled together with other battery components: negative electrode sheet, separator, and electrolyte to form a lithium-ion battery cell.

[0229] [Confirmation of the first insulating layer]

[0230] A scanning electron microscope (SEM) was used to observe the end face to check for the presence of a first insulating layer. Furthermore, the thickness of the first insulating layer could be observed through images taken with the scanning electron microscope.

[0231] [Confirmation of the second insulating layer]

[0232] The surface of the electrode was observed using a scanning electron microscope to check for the presence of a second insulating layer. The electrode was then cut open, and the cross-section was photographed using a scanning electron microscope. The thickness of the second insulating layer was then determined based on the photographs.

[0233] [Full Charge Anode Test]

[0234] Use the laser-cut end face to overlap the fully charged anode and observe whether it catches fire.

[0235] [After immersion in electrolyte, perform a full-charge anode test.]

[0236] After the cut electrode sheet is immersed in electrolyte at 70℃ for 7 days, the cut end face is fully charged with the anode and observed to see if it catches fire.

[0237] [Slurry Performance Testing]

[0238] During the preparation of the coating slurry for the second insulating layer, observe whether the polymer particles in the slurry agglomerate.

[0239] [Testing the resistance at the terminal face]

[0240] The resistance of the end face can be measured with an ohmmeter.

[0241] For example, one end of the ohmmeter is connected to the tab of the positive electrode in the embodiment (specifically, the part of the tab that is not coated with the second insulating layer), and the other end is connected to the tab of the negative electrode, with the end faces of the negative electrode overlapping the positive electrode.

[0242] [Particle size testing of thermoplastic polymers]

[0243] The volumetric particle size distribution of thermoplastic polymers can be determined using a particle size analyzer-laser diffraction method. Specifically, refer to standard GB / T19077-2016, using a laser diffraction scattering particle size analyzer, and perform measurements according to the manufacturer's instructions. For example, before preparing the slurry for the second insulating layer, take an appropriate amount of thermoplastic polymer and test the average volumetric particle size of the material using a Malvern 2000 (MasterSizer2000) laser particle size analyzer. Take an appropriate amount of the sample to be tested (the sample concentration should be 8-12% opacity), add 20 ml of deionized water, and simultaneously incubate for 5 minutes (53 kHz / 120 W) to ensure complete dispersion of the sample. Then, measure the sample according to GB / T19077-2016 / ISO 13320:2009.

[0244] For example, scanning electron microscopy can be used to test the electrode to obtain an image of the region of the second insulating layer of the electrode. A region of a specific size is selected, and based on the quantity and size of the thermoplastic polymer in the image, the volumetric particle size distribution Dv50 and the maximum particle size D of the thermoplastic polymer are calculated. max .

[0245] [Confirmation of the dropping melting point of thermoplastic polymers]

[0246] The dropping melting point of thermoplastic polymers can be determined according to GB / T8026-2014. For example, a cooled temperature sensor is vertically immersed in the sample, allowing the sample to adhere to the sensor. Then, the sample is placed in a test tube and heated at the required rate to begin melting. The melting point is determined by the temperature of the sensor at which the first drop of sample falls onto it.

[0247] For example, the dropping point of a thermoplastic polymer can be determined based on the specific type of thermoplastic polymer. As an example, for crystalline thermoplastic polymers, the dropping point refers to the melting point of the crystalline thermoplastic polymer; for amorphous thermoplastic polymers, the dropping point refers to the glass transition temperature of the amorphous thermoplastic polymer.

[0248] [Mass ratio of thermoplastic polymer to binder]

[0249] The mass ratio of thermoplastic polymer to binder can be obtained based on the mass of thermoplastic polymer and binder added during the preparation process.

[0250] Figure 13 This is a SEM image of the end face with a first insulating layer according to an embodiment of this application. (In conjunction with...) Figure 13 As shown, a first insulating layer 121 is provided at the end face of the electrode.

[0251] As shown in Examples 1-14 and Comparative Example 1, a first insulating layer is provided at the end face of the electrode. After the end face of the electrode overlaps with the fully charged anode, no fire will occur. Thus, the technical solution of this application can improve the reliability of the battery cell.

[0252] Combining Examples 1-5 and Comparative Example 6, as well as Examples 12 and Comparative Examples 2-3, by setting the volume particle size distribution D of the thermoplastic polymer in the second insulating layer... V 50 has a particle size of 6μm to 10μm and a maximum particle size D. max With a thickness of 90μm to 110μm, the thermoplastic polymer in the slurry will not agglomerate during the preparation of the second insulating layer, which facilitates the preparation of the second insulating layer.

[0253] Combining Examples 1-5 and Comparative Examples 4-5, by setting the maximum particle size D of the thermoplastic polymer in the second insulating layer... max With a particle size of 90μm to 110μm, during the process of cutting the current collector to prepare the electrode tab, the thermoplastic polymer changes from a solid state to a fluid state. The fluidized thermoplastic polymer has a suitable flow path, facilitating its flow to the end face and coating it to form a uniform first insulating layer. Thus, when the electrode is fully charged with the anode, no fire occurs; whereas in Comparative Examples 4-5, only some locations do not ignite. Furthermore, after the electrode is immersed in electrolyte, no fire occurs when the electrode is fully charged with the anode; while in Comparative Examples 4-5, only some locations do not ignite. Therefore, appropriately setting the particle size of the thermoplastic polymer is beneficial to improving the density of the first insulating layer, thereby improving its adhesion to the end face. Therefore, by appropriately setting the maximum particle size D of the thermoplastic polymer in the second insulating layer... max This helps to improve the uniformity and density of the first insulating layer, further enhancing the reliability of the battery cell.

[0254] In conjunction with Examples 6-9, by reasonably setting the thickness of the second insulating layer, a first insulating layer with a suitable thickness can be obtained after cutting.

[0255] In conjunction with Examples 10-12, the thermoplastic polymer in the second insulating layer can be a variety of materials.

[0256] In conjunction with Examples 13-14, the thermoplastic polymer and binder in the second insulating layer can be appropriately set to suit a variety of different mass ratios.

[0257] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. An electrode sheet, characterized in that, include: Current collector, active material layer, first insulating layer and second insulating layer, The current collector includes a main body and an electrode tab. The electrode tab extends from a first end of the main body, which is one end of the main body along a first direction. The main body includes a coating area and a transition area, and the transition area is disposed between the coating area and the electrode tab. The active material layer is disposed on the surface of the coating area; The first insulating layer is disposed on the end face of the main body at the first end; At least a portion of the second insulating layer is disposed on the surface of the transition region, the second insulating layer comprising a thermoplastic polymer having a volume particle size distribution D. V 50 is 6μm~10μm, and the maximum particle size D of the thermoplastic polymer is... max The size ranges from 90μm to 110μm.

2. The electrode sheet according to claim 1, characterized in that, The volume particle size distribution D of the thermoplastic polymer V 50 is 7μm~8μm, and the maximum particle size D of the thermoplastic polymer is... max The size is 90μm~100μm.

3. The electrode sheet according to claim 1 or 2, characterized in that, The thickness d2 of the second insulating layer is 22μm~48μm.

4. The electrode sheet according to claim 3, characterized in that, The thickness d2 of the second insulating layer is 22μm~30μm.

5. The electrode sheet according to claim 1 or 2, characterized in that, The thickness d1 of the first insulating layer is 300nm~1800nm.

6. The electrode sheet according to claim 5, characterized in that, The thickness d1 of the first insulating layer is 300nm~860nm.

7. The electrode sheet according to claim 1 or 2, characterized in that, The thermoplastic polymer has a dropping melting point of 80℃ to 250℃.

8. The electrode sheet according to claim 7, characterized in that, The thermoplastic polymer has a dropping melting point of 80℃ to 150℃.

9. The electrode sheet according to claim 1 or 2, characterized in that, The thermoplastic polymer material includes at least one of crystalline thermoplastic polymers and amorphous thermoplastic polymers.

10. The electrode sheet according to claim 9, characterized in that, The crystalline thermoplastic polymer includes at least one of polyethylene, polypropylene, and polyamide.

11. The electrode sheet according to claim 9, characterized in that, The amorphous thermoplastic polymer includes at least one of microcrystalline wax, polystyrene, and polymethyl methacrylate.

12. The electrode sheet according to claim 1 or 2, characterized in that, The second insulating layer also includes an adhesive.

13. The electrode sheet according to claim 12, characterized in that, In the second insulating layer, the mass ratio A:B of the thermoplastic polymer to the adhesive is 60:40 to 80:

20.

14. The electrode sheet according to claim 13, characterized in that, In the second insulating layer, the mass ratio A:B of the thermoplastic polymer to the adhesive is 70:30 to 80:

20.

15. The electrode sheet according to claim 1 or 2, characterized in that, The resistance R of the end face with the first insulating layer satisfies: R≥100Ω.

16. The electrode sheet according to claim 15, characterized in that, The resistance R of the end face with the first insulating layer satisfies: R≥2000Ω.

17. The electrode sheet according to claim 1 or 2, characterized in that, The second insulating layer includes a first portion and a second portion, the first portion being disposed on the surface of the transition region, and the second portion extending from the first portion along the first direction and disposed on a portion of the surface of the tab.

18. The electrode sheet according to claim 17, characterized in that, Along the second direction, the end faces of both ends of the region where the second part of the electrode is disposed are provided with the first insulating layer, and the second direction is different from the first direction.

19. The electrode according to claim 18, characterized in that, The second direction is perpendicular to the first direction.

20. The electrode sheet according to claim 1 or 2, characterized in that, The material of the first insulating layer is the same as the material of the thermoplastic polymer in the second insulating layer.

21. The electrode sheet according to claim 1 or 2, characterized in that, The thermoplastic polymer in the first insulating layer is in the form of a film, and the thermoplastic polymer in the second insulating layer includes both film-form thermoplastic polymers and granular thermoplastic polymers.

22. The electrode sheet according to claim 1 or 2, characterized in that, The current collector includes a metal foil or a composite current collector.

23. The electrode sheet according to claim 22, characterized in that, The metal foil includes aluminum foil or copper foil.

24. The electrode sheet according to claim 22, characterized in that, The composite current collector includes: a polymer material base layer and a metal layer located on at least one surface of the polymer material base layer.

25. The electrode sheet according to claim 22, characterized in that, The current collector includes aluminum foil.

26. A method for preparing an electrode sheet according to any one of claims 1-25, characterized in that, include: Provide current collectors; An active material is coated onto the first region of the current collector to form an active material layer; An insulating slurry is coated on the second region of the current collector to form a second insulating layer. The insulating slurry comprises a thermoplastic polymer and a binder, wherein the volumetric particle size distribution D of the thermoplastic polymer is... V 50 is 6μm~10μm, and the maximum particle size D of the thermoplastic polymer is... max The thickness is 90μm~110μm; A current collector having the second insulating layer cut along a cutting line, at least a portion of which is located in the second region.

27. The method according to claim 26, characterized in that, The volume particle size distribution D of the thermoplastic polymer V 50 is 7μm~8μm, and the maximum particle size D of the thermoplastic polymer is... max The size is 90μm~100μm.

28. The method according to claim 26 or 27, characterized in that, The thickness d2 of the second insulating layer is 22μm~48μm.

29. The method according to claim 28, characterized in that, The thickness d2 of the second insulating layer is 22μm~30μm.

30. The method according to claim 26 or 27, characterized in that, The thermoplastic polymer has a dropping melting point of 80℃ to 250℃.

31. The method according to claim 30, characterized in that, The thermoplastic polymer has a dropping melting point of 80℃ to 150℃.

32. The method according to claim 26 or 27, characterized in that, The thermoplastic polymer material includes at least one of crystalline thermoplastic polymers and amorphous thermoplastic polymers.

33. The method according to claim 32, characterized in that, The crystalline thermoplastic polymer includes at least one of polyethylene, polypropylene, and polyamide.

34. The method according to claim 32, characterized in that, The amorphous thermoplastic polymer includes at least one of microcrystalline wax, polystyrene, and polymethyl methacrylate.

35. The method according to claim 26 or 27, characterized in that, In the insulating slurry, the mass ratio A:B of the thermoplastic polymer to the binder is 60:40 to 80:

20.

36. The method according to claim 35, characterized in that, In the insulating slurry, the mass ratio A:B of the thermoplastic polymer to the binder is 70:30 to 80:

20.

37. The method according to claim 26 or 27, characterized in that, The current collector having the second insulating layer cut along the cutting line includes: The laser processing tool is controlled to cut the current collector with the second insulating layer along the cutting line.

38. A single battery cell, characterized in that, The electrode includes the electrode as described in any one of claims 1-25, and / or the electrode prepared by the method as described in any one of claims 26-37.

39. A battery, characterized in that, Includes the battery cell as described in claim 38.

40. An electrical device, characterized in that, Includes the battery as described in claim 39.

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