Adhesive material, adhesive composition, positive electrode sheet, secondary battery, and electric device

Abstract

This application provides an adhesive material, an adhesive composition, a positive electrode sheet, a secondary battery, and an electrical device. The adhesive material includes an adhesive comprising structural units A, B, C, and D, with at least a portion of structural units A crosslinked with at least a portion of structural units D; structural unit A is wherein each of the structural units B is independently any one or more of the following, optionally structural unit B is or structural unit C is independently any one of the following, each m1 and each m2 is independently an integer from 1 to 20, optionally m1 is independently any integer from 2 to 12, and each m2 is independently any integer from 8 to 12; structural unit D is independently any one or more of the following, n1 is independently any integer from 1 to 20, optionally n1 is any integer from 1 to 12, and further optionally n1 is any integer from 1 to 6.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an adhesive material, an adhesive composition, a positive electrode sheet, a secondary battery, and an electrical device. Background Technology

[0002] Secondary ion batteries (such as lithium-ion or sodium-ion batteries) are a type of new energy battery with advantages such as high operating voltage, high specific capacity, long charge-discharge life, and no memory effect. However, the safety of secondary ion batteries is increasingly becoming a focus of attention. During the daily manufacturing process, abnormal cells may appear, such as zero resistance during assembly short-circuit testing, low formation voltage, high self-discharge, and large module voltage difference. Disassembling finished batteries reveals that the separator corresponding to the blank edge of the positive electrode plate has been punctured. Analysis shows that metal particles generated during laser cutting sputter into the blank area, causing foreign objects to puncture the separator. This can lead to a large voltage difference in the cell, or even a short circuit and serious accidents. Furthermore, bending the tabs during cell assembly can cause the base of the tab to contact the blank edge of the positive electrode plate, also resulting in a short circuit.

[0003] To solve the above problems, placing an insulating layer on the edge of the positive electrode of the battery cell is very helpful in preventing the occurrence of the above short circuit problems. Summary of the Invention

[0004] This application provides an adhesive substance, an adhesive composition, a positive electrode sheet, a secondary battery, and an electrical device to solve the problem of poor wear resistance of the insulating adhesive at the edge of the positive electrode sheet.

[0005] The first aspect of this application provides an adhesive material, including an adhesive comprising structural unit A, structural unit B, structural unit C, and structural unit D, wherein at least a portion of structural unit A is crosslinked with at least a portion of structural unit D, wherein structural unit A is... Structural unit B is independently... Any one or more of the above, optionally, structural unit B is Each structural unit C is independently... In any one of the following, each m1 and each m2 is an independent integer from 1 to 20; optionally, each m1 is an independent integer from 2 to 12, and each m2 is an independent integer from 8 to 12; each structural unit D is an independent integer from 1 to 20. Any one or more of the following, where n1 is an arbitrary integer from 1 to 20, optionally, n1 is an arbitrary integer from 1 to 12, and further optionally, n1 is an arbitrary integer from 1 to 6.

[0006] Structural unit B is provided by acrylonitrile monomer, which is a hard monomer that can enhance the strength of the insulating adhesive layer; structural unit C is provided by acrylate monomer, which is a soft monomer that can improve the flexibility of the insulating adhesive layer and enhance the adhesion between the insulating adhesive layer and the current collector.

[0007] Structural units A and D form a three-dimensional cross-linked network through hydrogen bonding, resulting in an insulating adhesive layer with excellent abrasion resistance. This effectively isolates the base of the tab from the edge of the positive electrode plate due to bending during cell insertion, thus controlling short circuits between the tab and the positive electrode membrane. Furthermore, structural units A, C, and D are polymers of acrylic monomers, which are heat-resistant and do not readily decompose. Therefore, the resulting insulating adhesive layer prevents the current collector of the positive electrode plate from being directly cut by laser, effectively resisting metal particle splashing. Moreover, laser cutting within the insulating adhesive layer is less likely to produce molten metal beads, effectively mitigating the problem of metal particle splashing and membrane puncture caused by direct laser cutting of the current collector. Simultaneously, the three-dimensional cross-linked network further enhances resistance to laser cutting, better protecting the membrane.

[0008] In any embodiment of the first aspect of this application, at least some structural units A, at least some structural units B, at least some structural units C and at least some structural units D are linked in a chain to form a first chain structure, and at least some structural units A, at least some structural units C and at least some structural units D are linked in a chain to form a second chain structure; structural unit A in at least some of the first chain structure is crosslinked with structural unit D in at least some of the second chain structure; and structural unit D in at least some of the first chain structure is crosslinked with structural unit A in at least some of the second chain structure.

[0009] The first and second chain structures both contain structural units A and D, providing more crosslinking sites for structural units A and D, thereby further improving the density of the formed three-dimensional network and better improving the wear resistance of the adhesive material. The first chain structure also contains structural units A, B, C, and D, which makes it easier to adjust and control the strength provided by the chain structure by adjusting the content of structural units B and C. The second chain structure also contains structural units A, C, and D, and has better flexibility, allowing for more flexible adjustment of the content of structural unit C, and thus more flexible adjustment of the adhesive force of the adhesive material.

[0010] In any embodiment of the first aspect of this application, the adhesive material satisfies any one or more of the following conditions: 1) The abrasion resistance of the insulating adhesive layer formed by the adhesive material with a thickness of 3μm-7μm meets the following requirements: the test is conducted using an RCA paper tape abrasion tester, and a test area is formed by running a 55g weight on a flat surface for 300mm and 2 turns. n test points are taken in the test area with a spacing of not less than 2cm. The proportion of non-leaking points in the test area is more than 30%, where 5≤n≤100, or the area of ​​non-leaking points in the test area is more than 60% of the total area of ​​the test area; 2) The cohesive force of the insulating adhesive layer formed by the adhesive material is 620N / m-750N / m, optionally 660N / m-725N / m; 3) The Shore hardness of the insulating adhesive layer formed by the adhesive material is 45HA-80HA, optionally 50HA-65HA; 4) The adhesive force of the insulating adhesive layer formed by the adhesive material is 30N / m-90N / m, optionally 40N / m-80N / m.

[0011] In any embodiment of the first aspect of this application, the molar ratio of structural unit D to structural unit A in the adhesive is 0.5:1-5:1, optionally 0.5:1-3:1, and further optionally 1:1-3:1; optionally, the molar content of structural unit A is 4%-50%, optionally 4%-10%, and the molar content of structural unit D is 1%-50%, optionally 5%-30%, and further optionally 5%-15%. This maximizes the crosslinking of structural unit A and structural unit D to improve the wear resistance of the insulating adhesive layer formed by the adhesive material.

[0012] In any embodiment of the first aspect of this application, the molar ratio of structural unit C to structural unit B in the adhesive is 1:1-300:1, optionally 5:1-50:1; optionally, the molar content of structural unit B is 0.2%-20%, optionally 1%-5%; optionally, the molar content of structural unit C is 1%-90%, optionally 55%-90%, and further optionally 75%-80%. By controlling the ratio of structural unit B to structural unit C as described above, the adhesive strength of the adhesive material is improved as much as possible.

[0013] In any embodiment of the first aspect of this application, the adhesive material further includes insulating fillers and / or dispersants. The carboxyl groups in the adhesive material can form hydrogen bonds with the insulating fillers, thereby improving the adhesion of the formed insulating adhesive layer.

[0014] In any embodiment of the first aspect of this application, the weight ratio of insulating filler, adhesive, and dispersant is (70-90):(10-25):0.4. This approach not only reduces costs by utilizing insulating filler, but also improves the dispersion of insulating filler in the adhesive while avoiding interference with subsequent crosslinking of the adhesive, and provides sufficient adhesive to offer good bonding strength.

[0015] In any embodiment of the first aspect of this application, the insulating filler includes any one or more of the following: alumina, magnesium oxide, silicon dioxide, titanium dioxide, barium titanate, aluminum nitride, silicon nitride, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, mica, talc, boehmite, zeolite, apatite, kaolin, or glass powder. The hardness of the aforementioned insulating fillers varies, with boehmite exhibiting the most moderate hardness, which improves the stability of the insulating adhesive layer without negatively impacting the battery separator due to increased hardness.

[0016] In any embodiment of the first aspect of this application, the volume average particle size D of the insulating filler V 50≤1μm. Insulating fillers within this particle size range can be completely embedded in an insulating layer of conventional thickness, thereby effectively controlling the friction of the insulating filler on the diaphragm.

[0017] In any embodiment of the first aspect of this application, the adhesive material further includes a solvent; optionally, the solid content of the adhesive material is 20%-40%; optionally, the solvent of the adhesive material includes water; optionally, the viscosity of the adhesive material measured at 25°C and 12 rpm is 350 mPa·s-900 mPa·s.

[0018] A second aspect of this application provides an adhesive composition comprising an adhesive, the adhesive including a first adhesive and a second adhesive, wherein the first adhesive is a polymer including structural unit A, structural unit B, structural unit C, and structural unit D, and the second adhesive is a polymer including structural unit A, structural unit C, and structural unit D, wherein structural unit A is... Structural unit B is independently... Any one or more of the above, optionally, structural unit B is The structural unit C of the first adhesive and the structural unit C of the second adhesive are each independently... Each m1 and each m2 is an independent integer from 1 to 20, for example, m1 is 1, 2, 3, 4, 5, 6, 8, 10, 12, 13, 14, 15, 16, 18 or 20; alternatively, m1 is an independent integer from 2 to 12, and m2 is an independent integer from 8 to 12; the structural unit D of the first adhesive and the structural unit D of the second adhesive are each independent... n1 is each an independent integer from 1 to 20, optionally n1 is each an independent integer from 1 to 12; further optionally n1 is each an independent integer from 1 to 6.

[0019] When the adhesive composition is applied to the positive electrode sheet to prepare an insulating layer, structural unit B in the first adhesive is provided by acrylonitrile monomer, which is a hard monomer that can enhance the strength of the insulating layer; structural unit C in the first adhesive and the second adhesive is provided by acrylate monomer, which is a soft monomer that can improve the flexibility of the insulating layer and enhance the adhesion between the insulating layer and the current collector.

[0020] Meanwhile, on the one hand, structural unit A in the first adhesive and structural unit D in the second adhesive, as well as structural unit D in the first adhesive and structural unit A in the second adhesive, form a three-dimensional cross-linked network through hydrogen bonding. This results in an insulating adhesive layer with excellent wear resistance, effectively isolating the base of the electrode from the edge of the positive electrode plate caused by the bending of the electrode tab during battery cell insertion, thus effectively controlling the short circuit between the electrode tab and the positive electrode membrane. On the other hand, both the first and second adhesives in this adhesive composition are polymers of acrylic monomers. The acrylic substances in these polymers have high temperature resistance and are not easily decomposed. Therefore, the resulting insulating adhesive layer can prevent the current collector of the positive electrode plate from being directly cut by laser, effectively resisting metal particle splashing. Moreover, laser cutting in the insulating adhesive layer is less likely to produce molten metal beads, effectively mitigating the problem of metal particle splashing and membrane puncture caused by direct laser cutting of the current collector. At the same time, the aforementioned three-dimensional cross-linked network further enhances the resistance to laser cutting, better protecting the membrane.

[0021] In any embodiment of the second aspect, the weight ratio of the first adhesive and the second adhesive is 1:2.5-1:20, optionally 1:5-1:17.5. The second adhesive provides better adhesion and flexibility to the insulating layer, while an appropriate amount of the first adhesive enhances the strength of the insulating layer, thereby better adapting to the strength of the insulating filler and the positive current collector in the adhesive composition, allowing the adhesion to be fully utilized. Furthermore, the aforementioned weight ratio controls the density of the cross-linked network in the insulating layer, providing sufficient network support for wear resistance and protection of the current collector.

[0022] In any embodiment of the second aspect, the first adhesive satisfies any one or more of the following conditions: 1) the molar content of structural unit A in the first adhesive is 5%-30%; 2) the molar content of structural unit B in the first adhesive is 5%-85%; 3) the molar content of structural unit C in the first adhesive is 5%-85%; 4) the molar content of structural unit D in the first adhesive is 5%-15%. The hardness of the first adhesive is adjusted by adjusting the content of structural units B and C to meet the hardness requirements of different designs and processing methods for the insulating adhesive layer. The content of structural units A and D is relatively small among all structural units, mainly used to form a crosslinking network with the second adhesive, while also effectively controlling their self-crosslinking in the first adhesive.

[0023] In any embodiment of the second aspect, the second adhesive satisfies any one or more of the following conditions: 1) the molar content of structural unit A in the second adhesive is 5%-10%; 2) the molar content of structural unit C in the second adhesive is 70%-85%; 3) the molar content of structural unit D in the second adhesive is 5%-20%. Structural unit C constitutes a major proportion in the second adhesive, thereby providing the second adhesive with greater flexibility and adhesion, thus improving the adhesion of the insulating adhesive layer formed by the adhesive composition to the insulating filler and the positive current collector.

[0024] In any embodiment of the second aspect, the weight-average molecular weight of the first adhesive is 500,000 to 1,500,000; further optionally, the difference in weight-average molecular weight between the first adhesive and the second adhesive is 100,000 to 1,500,000. This provides good suspending effect on the insulating filler, effectively preventing its settling and improving the adhesion of the insulating adhesive layer.

[0025] In any embodiment of the second aspect, the adhesive material further includes insulating fillers and / or dispersants. The carboxyl groups of the first adhesive and the second adhesive can form hydrogen bonds with the insulating fillers, thereby improving the adhesion of the formed insulating adhesive layer.

[0026] In any embodiment of the second aspect of this application, the weight ratio of insulating filler, adhesive, and dispersant is (70-90):(10-25):0.4. This approach not only reduces costs by utilizing insulating filler, but also improves the dispersion of insulating filler in the adhesive while avoiding interference with subsequent crosslinking of the adhesive, and provides sufficient adhesive to offer good bonding strength.

[0027] In any embodiment of the second aspect, the insulating filler comprises any one or more of alumina, magnesium oxide, silicon dioxide, titanium dioxide, barium titanate, aluminum nitride, silicon nitride, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, mica, talc, boehmite, zeolite, apatite, kaolin, or glass powder; optionally, the volume average particle size D of the insulating filler is... V 50≤1μm. Insulating fillers within this particle size range can be completely embedded in an insulating layer of conventional thickness, thereby effectively controlling the friction of the insulating filler on the diaphragm.

[0028] In any embodiment of the second aspect, the dispersant includes one or more of polyacrylate compounds, fatty alcohol polyether compounds, or polyether-modified siloxane compounds.

[0029] In any embodiment of the second aspect, the adhesive composition further includes a solvent; optionally, the solid content of the adhesive composition is 20%-40%; further optionally, the solvent of the adhesive composition includes water.

[0030] In a third aspect of this application, a positive electrode sheet is provided, comprising: a positive current collector having a positive electrode film layer region and an empty foil region on at least one side; a positive electrode film layer disposed in the positive electrode film layer region of the positive electrode current collector; and an insulating adhesive layer disposed in the empty foil region of the positive electrode current collector, wherein the insulating adhesive layer is formed using any of the adhesive substances of the first aspect described above, or cured by any of the adhesive compositions of the second aspect described above.

[0031] The insulating adhesive layer has excellent abrasion resistance, effectively isolating the base of the tab from the edge of the positive electrode plate caused by the bending of the tab during cell insertion, thus effectively controlling the short circuit between the tab and the positive electrode membrane. Simultaneously, the insulating adhesive layer prevents the current collector of the positive electrode plate from being directly cut by the laser, effectively resisting metal particle splashing. Furthermore, laser cutting within the insulating adhesive layer is less likely to produce molten metal beads, effectively mitigating the problem of metal particle splashing and rupture of the separator caused by direct laser cutting of the current collector. Moreover, the aforementioned three-dimensional cross-linked network further enhances resistance to laser cutting, better protecting the separator.

[0032] In any embodiment of the third aspect, the thickness of the insulating adhesive layer is less than or equal to the thickness of the positive electrode film layer; optionally, the thickness of the insulating adhesive layer is 3 μm-7 μm.

[0033] A fourth aspect of this application provides a method for preparing a positive electrode sheet, comprising a process of forming a positive electrode film layer and an insulating adhesive layer on at least one or both sides of a positive electrode current collector, wherein the process of forming the insulating adhesive layer comprises: mixing the components of any adhesive composition of the first aspect to form an adhesive solution; coating the adhesive solution onto the empty foil area of ​​the positive electrode current collector to obtain a preform having the adhesive solution; heating the preform having the adhesive solution to obtain an insulating adhesive layer, optionally heating at a temperature of 90°C-120°C to accelerate the solvent removal rate therein.

[0034] In any embodiment of the fourth aspect, the process of mixing the components of the adhesive composition to form a slurry includes: mixing the dispersant in the adhesive composition with water to form a first dispersion, optionally, the mixing is a first stirring, the first stirring time is 5 min-30 min, and the stirring speed is 200 rpm-400 rpm; mixing the first dispersion with the insulating filler in the adhesive composition to form a second dispersion, optionally, the mixing is a second stirring, the second stirring time is 30 min-120 min, and the stirring speed is 1200 rpm-1800 rpm; mixing the second dispersion with the first adhesive in the adhesive composition to form a third dispersion, optionally, the mixing is a third stirring, the third stirring time is 15 min-60 min, and the stirring speed is 400 rpm-700 rpm; mixing the third dispersion with the second adhesive in the adhesive composition to form a slurry, optionally, the mixing is a fourth stirring, the fourth stirring time is 5 min-30 min, and the stirring speed is 200 rpm-400 rpm.

[0035] The fifth aspect of this application provides a secondary battery, including a positive electrode sheet, wherein the positive electrode sheet includes any of the positive electrode sheets provided in the third aspect above or a positive electrode sheet prepared by any of the preparation methods provided in the fourth aspect above.

[0036] The sixth aspect of this application provides an electrical device including a secondary battery, wherein the secondary battery includes any of the secondary batteries provided in the fifth aspect above. Attached Figure Description

[0037] 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.

[0038] Figure 1 A side view of the positive electrode sheet provided in one embodiment of this application.

[0039] Figure 2This is a schematic diagram of a secondary battery according to one embodiment of this application.

[0040] Figure 3 yes Figure 2 An exploded view of a secondary battery according to an embodiment of this application is shown.

[0041] Figure 4 This is a schematic diagram of a battery module according to one embodiment of this application.

[0042] Figure 5 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0043] Figure 6 yes Figure 5 An exploded view of a battery pack according to one embodiment of this application is shown.

[0044] Figure 7 This is a schematic diagram of an electrical device that uses a secondary battery as a power source according to one embodiment of this application.

[0045] The accompanying drawings are not drawn to scale.

[0046] Explanation of reference numerals in the attached figures:

[0047] 10 Positive electrode sheet; 11 Positive current collector; 12 Positive electrode film; 13 Insulating adhesive layer;

[0048] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Secondary battery; 51 Housing; 52 Electrode assembly; 53 Top cover assembly. Detailed Implementation

[0049] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0050] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the adhesive material, adhesive composition, positive electrode sheet, secondary battery, and electrical device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically 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 for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0051] 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.

[0052] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0053] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0054] 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.

[0055] Unless otherwise specified, the terms "comprising" and "including" as used in this application are open-ended. For example, "comprising" and "including" may mean that other components not listed may also be included or contained.

[0056] Unless otherwise specified, the term "or" is inclusive in this application. For example, any of the following conditions satisfies the condition "A or B": 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).

[0057] [Adhesive material]

[0058] Vibration is unavoidable during the operation of secondary ion batteries. With vibration, the tabs in the cell also move relative to each other, resulting in internal friction. However, the wear resistance of conventional insulating adhesive layers is insufficient. The relative movement of the tabs will cause coating wear and electrode foil leakage, thus causing a short circuit inside the cell.

[0059] To address the aforementioned problems, in a first embodiment of this application, an adhesive material is provided, comprising an adhesive, wherein the adhesive includes structural unit A, structural unit B, structural unit C, and structural unit D, and at least a portion of structural unit A is crosslinked with at least a portion of structural unit D, wherein structural unit A is... Structural unit B is independently... Any one or more of the above, optionally, structural unit B is Each structural unit C is independently... In any one of the following, each m1 and each m2 is an independent integer from 1 to 20; optionally, each m1 is an independent integer from 2 to 12, and each m2 is an independent integer from 8 to 12; each structural unit D is an independent integer from 1 to 20. Any one or more of the following, where n1 is an arbitrary integer from 1 to 20, optionally, n1 is an arbitrary integer from 1 to 12, and further optionally, n1 is an arbitrary integer from 1 to 6.

[0060] In the adhesive of the above-mentioned adhesive material, structural unit B is provided by acrylonitrile monomer, which is a hard monomer that can enhance the strength of the insulating adhesive layer; structural unit C is provided by acrylate monomer, which is a soft monomer that can improve the flexibility of the insulating adhesive layer and enhance the adhesion between the insulating adhesive layer and the current collector.

[0061] Meanwhile, structural units A and D form a three-dimensional cross-linked network through hydrogen bonding, giving the resulting insulating adhesive layer excellent wear resistance. This effectively isolates the base of the tab from the edge of the positive electrode plate due to bending during cell insertion, thus controlling short circuits between the tab and the positive electrode membrane. Furthermore, structural units A, C, and D are polymers of acrylic monomers, which are heat-resistant and do not easily decompose. Therefore, the resulting insulating adhesive layer prevents the current collector of the positive electrode plate from being directly cut by laser, effectively resisting metal particle splashing. Moreover, laser cutting within the insulating adhesive layer is less likely to produce molten metal beads, effectively mitigating the problem of metal particle splashing and membrane puncture caused by direct laser cutting of the current collector. Simultaneously, the three-dimensional cross-linked network further enhances resistance to laser cutting, better protecting the membrane.

[0062] In some embodiments, at least some structural units A, at least some structural units B, at least some structural units C and at least some structural units D are linked in a chain to form a first chain structure, and at least some structural units A, at least some structural units C and at least some structural units D are linked in a chain to form a second chain structure; structural unit A in at least some of the first chain structure is crosslinked with structural unit D in at least some of the second chain structure; and structural unit D in at least some of the first chain structure is crosslinked with structural unit A in at least some of the second chain structure.

[0063] The first and second chain structures both contain structural units A and D, providing more crosslinking sites for structural units A and D, thereby further improving the density of the formed three-dimensional network and better improving the wear resistance of the adhesive material. The first chain structure also contains structural units A, B, C, and D, which makes it easier to adjust and control the strength provided by the chain structure by adjusting the content of structural units B and C. The second chain structure also contains structural units A, C, and D, and has better flexibility, allowing for more flexible adjustment of the content of structural unit C, and thus more flexible adjustment of the adhesive force of the adhesive material.

[0064] In some embodiments of this application, the adhesive material satisfies any one or more of the following conditions: 1) The abrasion resistance of the insulating adhesive layer with a thickness of 5 μm formed by the adhesive material meets the following requirements: the test is conducted using an RCA paper tape abrasion tester, and a test area is formed by running a 55g weight on a flat surface for 300 mm and 2 turns. n test points are taken in the test area with a spacing of not less than 2 cm between the test points. The proportion of non-leaking points in the test area is more than 30%, where 5 ≤ n ≤ 100, or the area of ​​non-leaking points in the test area is more than 60% of the total area of ​​the test area; 2) The cohesive force of the insulating adhesive layer formed by the adhesive material is 620 N / m-750 N / m, optionally 660 N / m-725 N / m; 3) The Shore hardness of the insulating adhesive layer formed by the adhesive material is 45 HA-80 HA, optionally 50 HA-65 HA; 4) The adhesive force of the insulating adhesive layer formed by the adhesive material is 30 N / m-90 N / m, optionally 40 N / m-80 N / m.

[0065] The test method for the above cohesion is as follows:

[0066] The adhesive material was prepared into a slurry and coated onto the carbonized layer of the carbonized copper foil. After drying, a sample sheet was obtained, with one side being the copper foil side and the other side being the adhesive layer formed by the adhesive material. The sample sheet was then cut into strips 2 cm wide and 6 cm long. The copper foil side of the strip was then bonded to a hard substrate (steel plate) using 3M-55230H double-sided tape (ensuring no air bubbles during bonding). 3M-55230H double-sided tape was then bonded to the adhesive side of the fixed strip, and a copper foil strip of the same size as the double-sided tape was placed over the tape (ensuring no air bubbles during bonding). The double-sided tape used in both applications was the same size, resulting in the test sample.

[0067] Manually peel the copper foil and double-sided adhesive from the first end of the test sample at a 180° angle, extending it 1 cm beyond the first end (i.e., the second end) of the entire test sample. Use one clamp of the tensile testing machine to fix the first end (hard substrate, carbon-coated copper foil, adhesive layer); use the other clamp of the tensile testing machine to fix the second end.

[0068] The tensile testing machine was set to a tensile speed of 50 mm / min and a test tensile length of 100 mm. The peel force data obtained during the test is the cohesive force of the coating material.

[0069] The above-mentioned hardness test method is as follows: The hardness of the surface of the insulating adhesive layer is tested using a Shore A hardness tester.

[0070] The test method for the above adhesion is as follows:

[0071] Specifically:

[0072] Take the positive electrode sheet to be tested. The positive electrode sheet should be in good condition; defective products are not allowed. Cut a sample with an insulating adhesive layer from the positive electrode sheet, 20mm wide and 100-160mm long, using a blade. Attach the special double-sided adhesive tape NITTO.NO5000NS to the steel plate, with a tape width of 10mm and a length of 90-150mm. Fix a paper tape with the same width as the sample and a length 80-200mm longer than the sample onto the double-sided adhesive, with a wrinkle-like adhesive layer on the paper tape. Attach the cut sample to the wrinkle-like adhesive layer, with the insulating adhesive layer facing down. Then, roll the sample surface three times in the same direction using a 3kg roller to obtain the test sample. The test sample is fixed on the testing machine. The end of the steel plate without the electrode attached is secured with the lower clamp. The paper tape is folded upwards and secured with the upper clamp. The sample axis is aligned with the direction of the applied force. The testing machine is loaded at a peeling speed of 10 mm / min until the sample breaks. The test is then stopped, and the maximum load force is recorded as F (in N). The sample width L = 20 mm. The peel strength f1 (in N / m) is calculated according to f1 = F / L. The peel strength is the adhesive force.

[0073] In some embodiments of this application, the molar ratio of structural unit D to structural unit A in the adhesive is 0.5:1-5:1, for example: 0.5:1, 1:1, 1.1:1, 2:1, 2.1:1, 2.2:1, 2.5:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.2:1, 3.5:1, 3.8:1, 4:1, 4.5:1 or 5:1, optionally 0.5:1-3:1, and further optionally 1:1-3:1; optionally, the molar content of structural unit A is... The content of structural unit A and structural unit D is 4%-50%, such as 4%, 4.5%, 4.8%, 5%, 5.3%, 5.5%, 6%, 6.2%, 6.4%, 6.8%, 7%, 10%, 15%, 20%, 30%, 40%, or 50%, and can be selected as 4%-10%. The molar content of structural unit D is 1%-50%, such as 1%, 4%, 5%, 6%, 8%, 10%, 13%, 14%, 15%, 20%, 30%, 40%, or 50%, and can be selected as 5%-30%, and further selected as 5%-15%. This maximizes the cross-linking of structural unit A and structural unit D to improve the wear resistance of the insulating adhesive layer formed by the adhesive material.

[0074] In some embodiments of this application, the molar ratio of structural unit C to structural unit B in the adhesive is 1:1-300:1, for example: 1:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 60:1, 100:1, 150:1, 200:1, 250:1, 280:1, 290:1, or 300:1; optionally, it is 5:1-50:1; the molar content of structural unit B is 0.2%-20%, for example, 0.2%. The percentages of structural unit B and structural unit C can be 0.25%, 0.5%, 1%, 1.5%, 2%, 2.1%, 2.5%, 3%, 3.5%, 5%, 10%, 11%, 13%, 15%, or 20%, optionally from 1% to 5%. Alternatively, the molar content of structural unit C can be 1% to 90%, such as 5%, 10%, 20%, 30%, 40%, 45%, 50%, 55%, 58%, 60%, 68%, 70%, 75%, 77%, 78%, 80%, 85%, or 90%, optionally from 55% to 90%, and further optionally from 75% to 80%. By controlling the ratio of structural unit B and structural unit C as described above, the adhesive strength of the binder can be improved as much as possible.

[0075] In some embodiments of this application, the adhesive material further includes insulating fillers and / or dispersants. The use of insulating fillers reduces costs, and dispersants promote the dispersion of insulating fillers in the adhesive. Moreover, the carboxyl groups of the structural unit A can form hydrogen bonds with the insulating fillers, thereby improving the adhesion of the formed insulating adhesive layer.

[0076] In some embodiments of this application, the ratio of insulating filler, adhesive, and dispersant can refer to the composition of conventional adhesives. In some embodiments, the weight ratio of insulating filler, adhesive, and dispersant is (70-90):(10-25):0.4. This approach can reduce costs by utilizing insulating filler, while the dispersant can improve the dispersion of the insulating filler in the adhesive, avoid hindering subsequent cross-linking of the adhesive, and provide sufficient adhesive to offer good bonding strength.

[0077] The insulating filler can be a commonly used insulating filler in adhesives. Considering that the adhesive composition is used in the positive electrode sheet and needs to withstand laser radiation, the insulating filler can be an inorganic material that does not soften or melt at temperatures above 600°C, typically above 700°C, such as above 900°C, and can insulate the positive and negative electrodes. It should also be heat-resistant and electrochemically stable.

[0078] In some embodiments, the insulating filler includes any one or more of the following: alumina, magnesium oxide, silicon dioxide, titanium dioxide, barium titanate, aluminum nitride, silicon nitride, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, mica, talc, boehmite, zeolite, apatite, kaolin, or glass powder. The hardness of the aforementioned insulating fillers varies, with boehmite exhibiting the most moderate hardness, which improves the stability of the insulating adhesive layer without negatively impacting the battery separator due to increased hardness.

[0079] In some embodiments, to further improve the dispersion of the insulating filler in the adhesive while avoiding the impact of excessively large filler particle size on the diaphragm, optionally, the D of the insulating filler... V 50. Particle size ≤ 1 μm. Insulating fillers within this particle size range can be completely embedded in an insulation layer of conventional thickness, thus effectively controlling friction between the insulating filler and the diaphragm. The Dv50 mentioned above represents the volume average particle size, which refers to the particle size corresponding to a cumulative volume distribution percentage of 50% of the material. Its testing method can refer to standard GB / T 19077-2016, and is determined using a laser particle size analyzer (e.g., Malvern Master Size 3000).

[0080] The dispersant used in the adhesive material of this application can be selected from conventional dispersants that are beneficial for dispersing insulating fillers. In some embodiments, the dispersant includes one or more of polyacrylate compounds, fatty alcohol polyether compounds, and polyether-modified siloxane compounds, such as Chemadd-6004 from Yueyang Kaimen Waterborne Additives Co., Ltd., and Elaecpure LW-10 from Dow Chemical. When the adhesive material does not contain solvent, its packaging and transportation are more convenient; when it contains solvent, its use is more convenient. Different solid content results in different viscosities, different coatability, and different curing conditions for the adhesive material. Those skilled in the art can select the solid content according to the construction requirements. In some embodiments, the solid content of the adhesive material is optionally 20%-40% to improve construction and curing efficiency. Optionally, the viscosity of the adhesive material measured at 25°C and 12 rpm is 550 mPa·s.

[0081] In some embodiments, to save costs and improve the safety of the operating environment, the solvent for the adhesive material may optionally include water, i.e., an aqueous adhesive.

[0082] [Adhesive Composition]

[0083] In a second embodiment of this application, an adhesive composition is provided, comprising an adhesive, wherein the adhesive includes a first adhesive and a second adhesive, the first adhesive being a polymer including structural unit A, structural unit B, structural unit C, and structural unit D, and the second adhesive being a polymer including structural unit A, structural unit C, and structural unit D.

[0084] Wherein, structural unit A is

[0085] Structural unit B is independently... Any one or more of the above, optionally, structural unit B is The structural unit C of the first adhesive and the structural unit C of the second adhesive are each independently... Each m1 and each m2 is an independent integer from 1 to 20, for example, m1 is 1, 2, 3, 4, 5, 6, 8, 10, 12, 13, 14, 15, 16, 18 or 20; alternatively, m1 is an independent integer from 2 to 12, and m2 is an independent integer from 8 to 12; the structural unit D of the first adhesive and the structural unit D of the second adhesive are each independent... n1 can be any integer from 1 to 20 independently, for example, n1 can be 1, 2, 3, 4, 5, 6, 8, 10, 12, 13, 14, 15, 16, 18 or 20. Alternatively, n1 can be any integer from 1 to 12 independently; further alternatively, n1 can be any integer from 1 to 6 independently.

[0086] When the adhesive composition is applied to the positive electrode sheet to prepare an insulating layer, structural unit B in the first adhesive is provided by acrylonitrile monomer, which is a hard monomer that can enhance the strength of the insulating layer; structural unit C in the first adhesive and the second adhesive is provided by acrylate monomer, which is a soft monomer that can improve the flexibility of the insulating layer and enhance the adhesion between the insulating layer and the current collector.

[0087] Meanwhile, on the one hand, structural unit A in the first adhesive and structural unit D in the second adhesive, as well as structural unit D in the first adhesive and structural unit A in the second adhesive, form a three-dimensional cross-linked network through hydrogen bonding. This results in an insulating adhesive layer with excellent wear resistance, effectively isolating the base of the electrode from the edge of the positive electrode plate caused by the bending of the electrode tab during battery cell insertion, thus effectively controlling the short circuit between the electrode tab and the positive electrode membrane. On the other hand, both the first and second adhesives in this adhesive composition are polymers of acrylic monomers. The acrylic substances in these polymers have high temperature resistance and are not easily decomposed. Therefore, the resulting insulating adhesive layer can prevent the current collector of the positive electrode plate from being directly cut by laser, effectively resisting metal particle splashing. Moreover, laser cutting in the insulating adhesive layer is less likely to produce molten metal beads, effectively mitigating the problem of metal particle splashing and membrane puncture caused by direct laser cutting of the current collector. At the same time, the aforementioned three-dimensional cross-linked network further enhances the resistance to laser cutting, better protecting the membrane.

[0088] In some embodiments of this application, to further improve the overall performance of the insulating layer formed by the adhesive composition, the weight ratio of the first adhesive and the second adhesive can be selected as 1:2.5-1:20, for example, 1:17.5, 2:17.5, 4:17.5, 1:5, 2:12.5, 2:15, or 1:10; or 1:5-1:17.5. The amount of the second adhesive is relatively larger than that of the first adhesive. The first adhesive provides better adhesion and flexibility to the insulating layer, while the appropriate amount of the second adhesive increases the strength of the insulating layer, thereby better adapting to the strength of the insulating filler and the positive current collector in the adhesive composition, so that the adhesion is fully utilized; moreover, the above weight ratio is used to control the density of the crosslinking network of the insulating layer, providing sufficient network support for wear resistance and protection of the current collector.

[0089] The first and second adhesives in the adhesive composition of this application can both be polymerized from acrylic monomers and acrylic derivative monomers corresponding to the above-mentioned structural units. Different contents of each structural unit result in different properties of the adhesives. To adjust the properties of each adhesive and to achieve better synergy between the two adhesives, in some embodiments of this application, the first adhesive is a copolymer. Optionally, the first adhesive satisfies any one or more of the following conditions: 1) the molar content of structural unit A in the first adhesive is 5%-30%; 2) the molar content of structural unit B in the first adhesive is 5%-85%, optionally 5%-55%; 3) the molar content of structural unit C in the first adhesive is 5%-85%, optionally 35%-85%; 4) the molar content of structural unit D in the first adhesive is 5%-15%. The hardness of the first adhesive is adjusted by utilizing the contents of structural units B and C to meet the hardness requirements of the insulating adhesive layer for different designs and processing methods. The contents of structural units A and D are relatively small among all structural units, mainly used to form a crosslinking network with the second adhesive, while also effectively controlling their self-crosslinking in the first adhesive.

[0090] In some embodiments of this application, the second adhesive is a copolymer, and optionally the second adhesive satisfies any one or more of the following conditions: 1) the molar content of structural unit A in the second adhesive is 5%-10%; 2) the molar content of structural unit C in the second adhesive is 70%-85%; 3) the molar content of structural unit D in the second adhesive is 5%-20%. Structural unit C constitutes a major proportion in the second adhesive, thereby providing the second adhesive with greater flexibility and adhesion, thus improving the adhesion of the insulating adhesive layer formed by the adhesive composition to the insulating filler and the positive electrode current collector.

[0091] The first and second adhesives in the adhesive composition of this application bond insulating fillers and a substrate. Due to gravity, the insulating fillers tend to settle in the adhesive solution formed by the adhesive composition. Severe settling can affect the adhesion of the insulating adhesive layer to the substrate. In some embodiments of this application, the weight-average molecular weight of the first adhesive is 500,000 to 1,500,000. The first adhesive with this weight-average molecular weight has a high viscosity, thus providing good suspension for the insulating fillers, effectively preventing settling and improving the adhesion of the insulating adhesive layer.

[0092] The second adhesive has better flexibility and flowability, but its suspending effect on the insulating filler is not as good as that of the first adhesive. However, the second adhesive also has the characteristics of conventional polymers, namely, its viscosity increases with increasing molecular weight. In some embodiments, the second adhesive is still used to provide sufficient flowability for the adhesive composition, facilitating application. Further optionally, the difference in weight-average molecular weight between the first and second adhesives is 0-1,500,000. This difference can be the difference when the weight-average molecular weight of the first adhesive is greater than that of the second adhesive, or it can be the difference when the weight-average molecular weight of the first adhesive is less than that of the second adhesive.

[0093] In some embodiments, the adhesive material further includes insulating fillers and / or dispersants. The use of insulating fillers in the adhesive compositions of this application reduces the cost of the composition, and the dispersant promotes the dispersion of the insulating fillers in the adhesive; in addition, carboxyl groups can form hydrogen bonds with the insulating fillers, thereby improving the adhesion of the formed insulating adhesive layer.

[0094] The ratio of insulating filler, adhesive, and dispersant can be referenced from the composition of conventional adhesive compositions. In some embodiments, the weight ratio of insulating filler, adhesive, and dispersant is (70-90):(10-25):0.4. This approach can reduce costs by utilizing insulating filler, while the dispersant can improve the dispersion of the insulating filler in the adhesive, avoid hindering subsequent crosslinking of the adhesive, and provide sufficient adhesive strength.

[0095] The insulating filler can be a commonly used insulating filler in adhesives. Considering that the adhesive composition is used in the positive electrode sheet and needs to withstand laser radiation, the insulating filler can be an inorganic material that does not soften or melt at temperatures above 600°C, typically above 700°C, such as above 900°C, and can insulate the positive and negative electrodes. It should also be heat-resistant and electrochemically stable.

[0096] In some embodiments, the insulating filler includes any one or more of the following: alumina, magnesium oxide, silicon dioxide, titanium dioxide, barium titanate, aluminum nitride, silicon nitride, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, mica, talc, boehmite, zeolite, apatite, kaolin, or glass powder. The hardness of each of the above insulating fillers varies, with boehmite exhibiting the most moderate hardness, which improves the stability of the insulating adhesive layer without negatively impacting the battery separator due to increased hardness.

[0097] In some embodiments, to further improve the dispersion of the insulating filler in the adhesive while avoiding the impact of excessively large filler particle size on the diaphragm, optionally, the D of the insulating filler... V50. Particle size ≤ 1 μm. Insulating fillers within this particle size range can be completely embedded in an insulation layer of conventional thickness, thereby effectively controlling the friction of the insulating filler on the diaphragm.

[0098] The dispersant used in the adhesive composition of this application may be selected from conventional dispersants that are beneficial for dispersing insulating fillers. In some embodiments, the dispersant includes one or more of polyacrylate compounds, fatty alcohol polyether compounds, and polyether-modified siloxane compounds, such as Chemadd-6004 from Yueyang Kaimen Waterborne Additives Co., Ltd., and Elaecpure LW-10 from Dow Chemical.

[0099] In some embodiments, the adhesive composition further includes a solvent; when the solvent is not included, the packaging and transportation of the adhesive composition are more convenient; when the solvent is included, the use of the adhesive composition is more convenient. Different solid content results in different viscosities, different coatability, and different curing conditions in the adhesive composition. Those skilled in the art can select the solid content according to the application requirements. In some embodiments, the solid content of the adhesive composition is optionally 20%-40% to improve application and curing efficiency. In some embodiments, to save costs and improve the safety of the operating environment, the solvent of the adhesive composition may further optionally include water, i.e., a water-based adhesive.

[0100] In some embodiments, the abrasion resistance, cohesion, hardness and adhesion of the adhesive composition also meet the requirements of the above-mentioned adhesive substances, which will not be elaborated here.

[0101] The first and second adhesives used in the adhesive composition of this application can be prepared by referring to prior art preparation methods or using known materials. To facilitate implementation of this application by those skilled in the art, the following preparation methods are provided for reference.

[0102] First binder: At 10℃-30℃, the surfactant is dissolved in water, and monomers ACH2=CHCOOH, B CH2=CHCN, and C CH2=CHCOO(CH2) are added sequentially. m1 CH3 and monomer DCH2=CHCOO(CH2) n1OH groups and a chain transfer agent (such as n-dodecyl mercaptan) are mixed evenly, and nitrogen gas is introduced during the process for deoxygenation protection to form a pre-emulsion. The pre-emulsion is heated to 80℃-90℃ to obtain the pre-emulsion. A surfactant (such as dialkyl sulfosuccinate salt M-30S) is dissolved in deionized water and added to a reaction vessel with stirring. Nitrogen gas is used for deoxygenation protection, and the temperature is raised to 80℃-90℃ to obtain a reactive surfactant solution. An ammonium persulfate solution is prepared with deionized water as the first initiator solution. The pre-emulsion and the first initiator solution are simultaneously and continuously added dropwise to the reactive surfactant solution in the reaction vessel. After the addition is complete, the temperature is maintained to obtain an acrylate copolymer seed solution. An ammonium persulfate solution is prepared with deionized water as the second initiator solution. The concentration of the second initiator solution is greater than that of the first initiator solution. The second initiator solution is added dropwise to the acrylate copolymer seed solution for 100-150 minutes. After the addition is complete, the temperature is maintained for 1-3 hours to obtain the acrylate copolymer solution. The acrylic (ester) copolymer solution in the reactor was cooled to 60℃-70℃ and allowed to cool naturally to room temperature. Vacuum was then applied under reduced pressure until the vacuum level in the reactor was below 0.09 MPa. This vacuum was maintained for 10-50 minutes, then the pressure was released to atmospheric pressure. The mixture was filtered to obtain an aqueous adhesive emulsion. The pH was then adjusted to 7-8.

[0103] Second binder: At 10℃-30℃, the surfactant is dissolved in water, and monomers ACH2=CHCOOH and CCH2=CHCOO(CH2) are added sequentially. m1 CH3, monomer D CH2=CHCOO(CH2) n1OH groups and a chain transfer agent (such as n-dodecyl mercaptan) are mixed evenly, and nitrogen gas is introduced during the process for deoxygenation protection to form a pre-emulsion. The pre-emulsion is heated to 80℃-90℃ to obtain the pre-emulsion. A surfactant (such as dialkyl sulfosuccinate salt M-30S) is dissolved in deionized water and added to a reaction vessel with stirring. Nitrogen gas is used for deoxygenation protection, and the temperature is raised to 80℃-90℃ to obtain a reactive surfactant solution. An ammonium persulfate solution is prepared with deionized water as the first initiator solution. The pre-emulsion and the first initiator solution are simultaneously and continuously added dropwise to the reactive surfactant solution in the reaction vessel. After the addition is complete, the temperature is maintained to obtain an acrylate copolymer seed solution. An ammonium persulfate solution is prepared with deionized water as the second initiator solution. The concentration of the second initiator solution is greater than that of the first initiator solution. The second initiator solution is added dropwise to the acrylate copolymer seed solution for 100-150 minutes. After the addition is complete, the temperature is maintained for 1-3 hours to obtain the acrylate copolymer solution. The acrylic (ester) copolymer solution in the reactor was cooled to 60℃-70℃ and allowed to cool naturally to room temperature. Vacuum was then applied under reduced pressure until the vacuum level in the reactor was below 0.09 MPa. This vacuum was maintained for 10-50 minutes, then the pressure was released to atmospheric pressure. The mixture was filtered to obtain an aqueous adhesive emulsion. The pH was then adjusted to 7-8.

[0104] [Rechargeable Battery]

[0105] Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be recharged after being discharged to activate the active materials and continue to be used.

[0106] Typically, a secondary battery consists of a positive electrode, a negative electrode, a separator, and an electrolyte. During charging and discharging, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing active ions to pass through. The electrolyte, also located between the positive and negative electrodes, mainly conducts the active ions.

[0107] The above-described adhesive composition can be considered for application in secondary batteries where adhesive is required, or for use as a raw material for separators. In some embodiments, it is applied to the positive electrode.

[0108] [Positive electrode plate]

[0109] like Figure 1 As shown, the positive electrode 10 typically includes a positive current collector 11 and a positive electrode film 12 disposed on at least one side of the positive current collector 11, the positive electrode film 12 including a positive electrode active material.

[0110] As an example, the positive current collector 11 has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer 12 is disposed on either or both of the two opposite surfaces of the positive current collector 11.

[0111] like Figure 1 As shown, in addition to the positive electrode film layer 12, the positive electrode current collector 11 also has an empty foil area around the positive electrode film layer 12. In some embodiments of this application, the positive electrode sheet 10 further includes an insulating adhesive layer 13 disposed in the empty foil area of ​​the positive electrode current collector 11. The insulating adhesive layer 13 is formed by curing the adhesive composition provided in any of the above embodiments. The specific location of the insulating adhesive layer 13 in the empty foil area can refer to the prior art, for example, avoiding the root of the tab.

[0112] The insulating adhesive layer 13 in the positive electrode 10 is formed by curing the adhesive composition described above in this application. On the one hand, structural unit A in the first adhesive and structural unit D in the second adhesive, as well as structural unit D in the first adhesive and structural unit A in the second adhesive, form a three-dimensional cross-linked network through hydrogen bonding. This gives the insulating adhesive layer better anti-wear performance and can effectively isolate the electrode root from the edge of the positive electrode caused by the bending of the electrode tab when the battery cell is installed, thus effectively controlling the short circuit between the electrode tab and the positive electrode membrane. On the other hand, both the first adhesive and the second adhesive in this adhesive composition are polymers of acrylic monomers. The acrylic substances in them have high temperature resistance and are not easily decomposed. Therefore, the insulating adhesive layer can prevent the current collector of the positive electrode from being directly cut by the laser, effectively resisting metal particle splashing. Moreover, laser cutting in the insulating adhesive layer is less likely to produce metal molten beads, effectively alleviating the problem of metal particle splashing and membrane puncture caused by direct laser cutting of the current collector. At the same time, the above-mentioned three-dimensional cross-linked network further enhances the resistance to laser cutting and better protects the membrane.

[0113] Furthermore, the carboxyl groups of the first and second adhesives can form hydrogen bonds with the insulating filler, thereby improving the adhesion of the insulating layer. Structural unit B in the first adhesive is provided by acrylonitrile monomers, which are hard monomers that enhance the strength of the insulating layer; structural unit C in both the first and second adhesives is provided by acrylate monomers, which are soft monomers that improve the flexibility of the insulating layer and enhance the adhesion between the insulating layer and the current collector.

[0114] The thickness of the insulating adhesive layer 13 of the positive electrode sheet 10 can be based on the conventional thickness of the insulating adhesive layer, or the thickness can be set according to the design requirements of the battery. In some embodiments, the thickness of the insulating adhesive layer 13 is less than or equal to the thickness of the positive electrode film layer 12. Optionally, the thickness of the insulating adhesive layer 13 is 3μm-7μm. This can both protect the positive electrode current collector 11 and avoid increasing the cell volume due to excessive thickness of the insulating adhesive layer 12.

[0115] The formation process of the above-mentioned insulating adhesive layer can refer to conventional techniques, such as coating. In some embodiments, the process of forming the insulating adhesive layer includes: mixing an adhesive composition to form an adhesive solution; coating the adhesive solution onto the empty foil area of ​​the positive electrode current collector to obtain a preform with the adhesive solution; heating the preform with the adhesive solution to obtain an insulating adhesive layer, optionally at a temperature of 90°C-120°C to accelerate the solvent removal rate.

[0116] In some embodiments, to improve the uniformity of mixing of the components in the adhesive composition, the process of mixing the adhesive composition to form a slurry includes:

[0117] The dispersant in the adhesive composition is mixed with water to form a first dispersion. Optionally, the mixing is a first stirring, the stirring time is 5 min-30 min, and the stirring speed is 200 rpm-400 rpm.

[0118] The first dispersion is mixed with the insulating filler in the adhesive composition to form a second dispersion. Optionally, the mixing is carried out by a second stirring, and the stirring time is 30 min-120 min and the stirring speed is 1200 rpm-1800 rpm.

[0119] The second dispersion is mixed with the first adhesive in the adhesive composition to form a third dispersion. Optionally, the mixing is carried out by a third stirring, the stirring time is 15 min-60 min, and the stirring speed is 400 rpm-700 rpm.

[0120] The third dispersion is mixed with the second adhesive in the adhesive composition to form a glue solution. Optionally, the mixing is a fourth stirring, the stirring time is 5 min-30 min, and the stirring speed is 200 rpm-400 rpm.

[0121] In the above process, the mixing time and speed do not need to be adjusted according to the mixed objects, and the mixing effect of each component is improved by stirring.

[0122] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0123] In some embodiments, the positive electrode active material may be a known battery positive electrode active material. As an example, when the secondary battery is a lithium-ion secondary battery, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0124] When the secondary battery is a sodium-ion secondary battery, as an example, the positive electrode active material of the sodium-ion secondary battery may include at least one of the following materials: sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds. However, this application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials for sodium-ion batteries may also be used.

[0125] As an optional technical solution in this application, the transition metal in the sodium transition metal oxide can be at least one selected from Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. For example, the sodium transition metal oxide is Na. x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0 < x ≤ 1.

[0126] As an optional technical solution in this application, the polyanionic compound can be a compound containing sodium ions, transition metal ions, or a tetrahedral (YO4) structure. n- A class of compounds with anionic units. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si; n represents (YO4). n- The price state.

[0127] Polyanionic compounds can also contain sodium ions, transition metal ions, or tetrahedral (YO4) ions. n- A class of compounds containing anionic units and halide anions. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y can be at least one of P, S, and Si, and n represents (YO4). n- The valence state; the halogen can be at least one of F, Cl and Br.

[0128] Polyanionic compounds can also be sodium-containing tetrahedral (YO4) compounds. n- Anionic unit, polyhedral unit (ZO) y ) m+ And a class of compounds with optional halide anions. Y can be at least one of P, S, and Si, and n represents (YO4). n- The valence state; Z represents a transition metal, which can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; m represents (ZO) y ) m+ The valence state; the halogen can be at least one of F, Cl and Br.

[0129] Polyanionic compounds include, for example, NaFePO4, Na3V2(PO4) (sodium vanadium phosphate, abbreviated as NVP), Na4Fe3(PO4)2(P2O7), NaM'PO4F (M' is one or more of V, Fe, Mn and Ni), and Na3(VO4) y )2(PO4)2F 3-2y At least one of (0≤y≤1).

[0130] Prussian blue compounds can be a class of compounds containing sodium ions, transition metal ions, and cyanide ions (CN-). The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Examples of Prussian blue compounds include Na. a Me b Me' c (CN)6, wherein Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 < a ≤ 2, 0 < b < 1, 0 < c < 1.

[0131] In some embodiments, the positive electrode film layer may optionally include an adhesive. As an example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0132] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0133] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0134] [Negative electrode plate]

[0135] The negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0136] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0137] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0138] In some embodiments, the negative electrode active material may be a 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. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials 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.

[0139] In some embodiments, the negative electrode film layer may optionally include an adhesive. As an example, the adhesive may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0140] In some embodiments, the negative electrode film may optionally include a conductive agent. As an example, 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.

[0141] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0142] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0143] [Electrolytes]

[0144] The electrolyte acts as a conductor of ions between the positive and negative electrodes. This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or entirely solid.

[0145] In some embodiments, the electrolyte is liquid and includes an electrolyte salt and a solvent.

[0146] In some embodiments, the electrolyte salt for lithium-ion secondary batteries may include one or more 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, or lithium tetrafluorooxalate phosphate. The electrolyte salt for sodium-ion secondary batteries may include one or more of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium hexafluoroarsenate (NaAsF6), sodium trifluoroacetate (CF3COONa), sodium trifluoromethanesulfonate (CF3NaO3S, NaOTf), or sodium tetraphenylborate (NaBPh4).

[0147] In some embodiments, the solvent may be selected from 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.

[0148] In some embodiments, the electrolyte may optionally include additives. As examples, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0149] [Isolation membrane]

[0150] In some embodiments, the secondary battery also includes a separator. 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.

[0151] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0152] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0153] In some implementations, the secondary battery includes a single secondary battery cell, or a battery module and a battery pack.

[0154] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0155] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0156] This application does not impose any particular limitation on the shape of the secondary battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 2 The example shown is a square-structured secondary battery cell 5.

[0157] In some implementations, refer to Figure 3 The outer packaging may include a housing 51 and a cover plate 53. The housing 51 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be placed over the opening to close the receiving cavity. The positive electrode, negative electrode, and separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery cell 5 can be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0158] In some implementations, the secondary battery cells can be assembled into a battery module. The number of secondary battery cells contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0159] Figure 4 This is battery module 4, used as an example. (See reference...) Figure 4 In battery module 4, multiple secondary battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple secondary battery cells 5 can be fixed in place using fasteners.

[0160] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple secondary battery cells 5 are received.

[0161] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0162] Figure 5 and Figure 6 This is battery pack 1 as an example. (See reference...) Figure 5 and Figure 6 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0163] In addition, this application also provides an electrical device, which includes the secondary battery provided in this application. The secondary battery can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0164] As the electrical device, a single secondary battery cell, a battery module, or a battery pack can be selected according to its usage requirements.

[0165] Figure 7 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0166] [Example]

[0167] 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.

[0168] The first adhesive (structural unit B is) The preparation process of ) is as follows:

[0169] At an operating temperature of 20°C, 5.4 g of the reactive surfactant M-30S, a dialkyl sulfosuccinate salt containing a double bond group, was dissolved in 62 g of deionized water. Monomers A (CH2=CHCOOH), B (CH2=CHCN), and C (CH2=CHCOO(CH2)) were added sequentially. m1 CH3 and monomer D CH2=CHCOO(CH2) n1 0.058 g of chain transfer agent n-dodecyl mercaptan was mixed at 350 rpm for 25 min to form a pre-emulsion under nitrogen protection at a flow rate of 110 mL / min. The pre-emulsion was then heated to 85 °C at a rate of 2 °C / min and held for 30 min to obtain the pre-emulsion. 3.8 g of a dialkyl sulfosuccinate salt M-30S containing a double bond group of reactive surfactant was dissolved in 61.3 g of deionized water and added to the reactor. The mixture was heated to 88 °C at a rate of 2 °C / min under nitrogen protection at a flow rate of 100 mL / min and held for 30 min to obtain the reactive surfactant solution. 3.5 g of ammonium persulfate solution was prepared using deionized water as the first initiator solution. The pre-emulsion and the first initiator solution were simultaneously and continuously added dropwise to the reactive surfactant solution in the reactor. The addition was completed over 160 min, and the mixture was held at this temperature for 0.5 h to obtain the seed solution. A 1.0 g ammonium persulfate initiator solution was prepared using deionized water as the second initiator solution. This second initiator solution was added dropwise to the seed solution over 120 min. After the addition was complete, the solution was kept at this temperature for 2 h to obtain an acrylic (ester) copolymer solution. The acrylic (ester) copolymer solution in the reactor was cooled to 65°C at a rate of 2°C / min and held at this temperature for 30 min. It was then allowed to cool naturally to room temperature. Vacuum was applied under reduced pressure until the vacuum level in the reactor was below 0.09 MPa, and this was maintained for 30 min. The pressure was then released to atmospheric pressure, and the solution was filtered through a 300-mesh filter to obtain a second binder emulsion with a solid content of 50%. The pH was then adjusted to 7-8. The solid content of this first binder was 15%.

[0170] The composition of the first adhesive 1 to the first adhesive 21 is recorded in Table 1-1 by adjusting the composition or amount of each monomer.

[0171] First adhesive 22 (structural unit B is) The preparation process of ) is as follows:

[0172] At a working temperature of 20℃, 5.4g of the reactive surfactant dialkyl sulfosuccinate salt M-30S containing a double bond group was dissolved in 62g of deionized water, and monomers A (CH2=CHCOOH), B (styrene), and C (CH2=CHCOO(CH2)) were added sequentially. m1 CH3 and monomer D CH2=CHCOO(CH2)n1 0.058 g of chain transfer agent n-dodecyl mercaptan was mixed at 350 rpm for 25 min to form a pre-emulsion under nitrogen protection at a flow rate of 110 mL / min. The pre-emulsion was then heated to 85 °C at a rate of 2 °C / min and held for 30 min to obtain the pre-emulsion. 3.8 g of a dialkyl sulfosuccinate salt M-30S containing a double bond group of reactive surfactant was dissolved in 61.3 g of deionized water and added to the reactor. The mixture was heated to 88 °C at a rate of 2 °C / min under nitrogen protection at a flow rate of 100 mL / min and held for 30 min to obtain the reactive surfactant solution. 3.5 g of ammonium persulfate solution was prepared using deionized water as the first initiator solution. The pre-emulsion and the first initiator solution were simultaneously and continuously added dropwise to the reactive surfactant solution in the reactor. The addition was completed over 160 min, and the mixture was held at this temperature for 0.5 h to obtain the seed solution. A 1.0 g ammonium persulfate initiator solution was prepared using deionized water as the second initiator solution. This second initiator solution was added dropwise to the seed solution over 120 min. After the addition was complete, the solution was kept at this temperature for 2 h to obtain an acrylic (ester) copolymer solution. The acrylic (ester) copolymer solution in the reactor was cooled to 65°C at a rate of 2°C / min and held at this temperature for 30 min. It was then allowed to cool naturally to room temperature. Vacuum was applied under reduced pressure until the vacuum level in the reactor was below 0.09 MPa, and this was maintained for 30 min. The pressure was then released to atmospheric pressure, and the solution was filtered through a 300-mesh filter to obtain a second binder emulsion with a solid content of 50%. The pH was then adjusted to 7-8. The solid content of this first binder was 15%.

[0173] First adhesive 23 (structural unit B is) The preparation process of ) is as follows:

[0174] At an operating temperature of 20°C, 5.4g of the reactive surfactant M-30S, a dialkyl sulfosuccinate salt containing a double bond group, was dissolved in 62g of deionized water. Monomer A (CH2=CHCOOH), monomer B (methyl methacrylate), and monomer C (CH2=CHCOO(CH2)) were added sequentially. m1 CH3 and monomer D CH2=CHCOO(CH2) n10.058 g of chain transfer agent n-dodecyl mercaptan was mixed at 350 rpm for 25 min to form a pre-emulsion under nitrogen protection at a flow rate of 110 mL / min. The pre-emulsion was then heated to 85 °C at a rate of 2 °C / min and held for 30 min to obtain the pre-emulsion. 3.8 g of a dialkyl sulfosuccinate salt M-30S containing a double bond group of reactive surfactant was dissolved in 61.3 g of deionized water and added to the reactor. The mixture was heated to 88 °C at a rate of 2 °C / min under nitrogen protection at a flow rate of 100 mL / min and held for 30 min to obtain the reactive surfactant solution. 3.5 g of ammonium persulfate solution was prepared using deionized water as the first initiator solution. The pre-emulsion and the first initiator solution were simultaneously and continuously added dropwise to the reactive surfactant solution in the reactor. The addition was completed over 160 min, and the mixture was held at this temperature for 0.5 h to obtain the seed solution. A 1.0 g ammonium persulfate initiator solution was prepared using deionized water as the second initiator solution. This second initiator solution was added dropwise to the seed solution over 120 min. After the addition was complete, the solution was kept at this temperature for 2 h to obtain an acrylic (ester) copolymer solution. The acrylic (ester) copolymer solution in the reactor was cooled to 65°C at a rate of 2°C / min and held at this temperature for 30 min. It was then allowed to cool naturally to room temperature. Vacuum was applied under reduced pressure until the vacuum level in the reactor was below 0.09 MPa, and this was maintained for 30 min. The pressure was then released to atmospheric pressure, and the solution was filtered through a 300-mesh filter to obtain a second binder emulsion with a solid content of 50%. The pH was then adjusted to 7-8. The solid content of this first binder was 15%.

[0175] First adhesive 24 (structural unit C is lauryl methacrylate CH3CH2=CHCOO(CH2)) 12 The preparation process of CH3 is as follows:

[0176] At an operating temperature of 20°C, 5.4 g of the reactive surfactant M-30S, a dialkyl sulfosuccinate salt containing a double bond group, was dissolved in 62 g of deionized water. Monomers A (CH2=CHCOOH), B (CH2=CHCN), and C (CH3CH2=CHCOO(CH2)) were added sequentially. 12 CH3 and monomer D CH2=CHCOO(CH2) n10.058 g of chain transfer agent n-dodecyl mercaptan was mixed at 350 rpm for 25 min to form a pre-emulsion under nitrogen protection at a flow rate of 110 mL / min. The pre-emulsion was then heated to 85 °C at a rate of 2 °C / min and held for 30 min to obtain the pre-emulsion. 3.8 g of a dialkyl sulfosuccinate salt M-30S containing a double bond group of reactive surfactant was dissolved in 61.3 g of deionized water and added to the reactor. The mixture was heated to 88 °C at a rate of 2 °C / min under nitrogen protection at a flow rate of 100 mL / min and held for 30 min to obtain the reactive surfactant solution. 3.5 g of ammonium persulfate solution was prepared using deionized water as the first initiator solution. The pre-emulsion and the first initiator solution were simultaneously and continuously added dropwise to the reactive surfactant solution in the reactor. The addition was completed over 160 min, and the mixture was held at this temperature for 0.5 h to obtain the seed solution. A 1.0 g ammonium persulfate initiator solution was prepared using deionized water as the second initiator solution. This second initiator solution was added dropwise to the seed solution over 120 min. After the addition was complete, the solution was kept at this temperature for 2 h to obtain an acrylic (ester) copolymer solution. The acrylic (ester) copolymer solution in the reactor was cooled to 65°C at a rate of 2°C / min and held at this temperature for 30 min. It was then allowed to cool naturally to room temperature. Vacuum was applied under reduced pressure until the vacuum level in the reactor was below 0.09 MPa, and this was maintained for 30 min. The pressure was then released to atmospheric pressure, and the solution was filtered through a 300-mesh filter to obtain a second binder emulsion with a solid content of 50%. The pH was then adjusted to 7-8. The solid content of this first binder was 15%.

[0177] Table 1-1

[0178]

[0179] The molecular weights in Table 1-1 are weight-average molecular weights rounded to the nearest ten thousand. The test method can be found in standard GB / T21863-2008, and the determination can be performed using an ultra-high performance polymer chromatograph.

[0180] The preparation process of the second adhesive is as follows:

[0181] At an operating temperature of 20°C, 4.2 g (4.2%) of the reactive surfactant M-30S, a dialkyl sulfosuccinate salt containing a double bond group, was dissolved in 58 g (116%) of deionized water. Monomer A CH2=CHCOOH and monomer CCH2=CHCOO(CH2) were added sequentially. m1 CH3, monomer D CH2=CHCOO(CH2) n10.048 g (0.096%) of OH chain transfer agent n-dodecyl mercaptan was mixed at 300 rpm for 30 min to form a pre-emulsion. The pre-emulsion was then heated to 85 °C at a rate of 2 °C / min and held for 30 min to obtain the pre-emulsion solution. 2.8 g (2.8%) of the reactive surfactant dialkyl sulfosuccinate salt M-30S containing a double bond group was dissolved in 51.3 g (102.6%) of deionized water and added to the reactor. The mixture was heated to 86 °C at a rate of 2 °C / min at 300 rpm under nitrogen deoxygenation protection and held for 30 min to obtain the reactive surfactant solution. 3g (0.15wt%) of ammonium persulfate solution was prepared using deionized water as the first initiator solution. The pre-emulsion and the first initiator solution were simultaneously and continuously added dropwise to the reactive surfactant solution in the reactor. The addition was completed over 150 minutes, and the mixture was kept at this temperature for 0.5 hours to obtain the acrylic (ester) copolymer seed solution. 1.0g (0.1wt%) of ammonium persulfate initiator solution was prepared using deionized water as the second initiator solution. This second initiator solution was added dropwise to the acrylic (ester) copolymer seed solution over 120 minutes. After the addition was completed, the mixture was kept at this temperature for 2 hours to obtain the acrylic (ester) copolymer solution. The acrylic (ester) copolymer in the reactor was cooled to 65°C at a decreasing rate of 2°C / min, held at this temperature for 30 minutes, and then allowed to cool naturally to room temperature. Vacuum was applied under reduced pressure until the vacuum level in the reactor was below 0.09 MPa, maintained for 30 minutes, and then the pressure was released to atmospheric pressure. The mixture was then filtered through a 300-mesh filter cloth to obtain a second binder emulsion with a solid content of 50%. The pH was then adjusted to 7-8.

[0182] The composition of the second adhesive was adjusted by changing the composition and amount of each monomer, and the compositions of the second adhesive 1 to the second adhesive 12 are recorded in Table 1-2.

[0183] Table 1-2

[0184]

[0185] The molecular weights in Table 1-2 are weight-average molecular weights rounded to the nearest ten thousand. The test method can be found in standard GB / T21863-2008, and the determination can be performed using an ultra-high performance polymer chromatograph.

[0186] Example 1

[0187] Add the dispersant to deionized water and stir at 300 rpm for 15 min to obtain the first dispersion;

[0188] Add the insulating filler to the first dispersion above, and disperse and stir at 1500 rpm for 75 min to obtain the second dispersion;

[0189] The first adhesive emulsion was added to the second dispersion and dispersed and stirred at 1500 rpm for 60 min to obtain the third dispersion.

[0190] The second adhesive emulsion was added to the third dispersion and dispersed at 500 rpm for 60 minutes to obtain the adhesive solution. The specific substances and amounts of the dispersant, insulating filler, first adhesive, and second adhesive are recorded in Table 2.

[0191] Examples 2 to 47:

[0192] The corresponding adhesive solution was prepared according to the process of Example 1. The specific substances and amounts of the dispersant, insulating filler, first adhesive (dry matter) and second adhesive (dry matter) used in each example are recorded in Table 2.

[0193] Comparative Example 1

[0194] Add the dispersant to deionized water and stir at 300 rpm for 15 min to obtain the first dispersion;

[0195] Add the insulating filler to the first dispersion above, and disperse and stir at 1500 rpm for 75 min to obtain the second dispersion;

[0196] The first adhesive emulsion was added to the above dispersion and stirred at 1500 rpm for 60 minutes to obtain the adhesive solution. The specific substances and amounts of the dispersant, insulating filler, and first adhesive are recorded in Table 2.

[0197] Comparative Example 2

[0198] Add the dispersant to deionized water and stir at 300 rpm for 15 min to obtain the first dispersion;

[0199] Add the insulating filler to the first dispersion above, and disperse and stir at 1500 rpm for 75 min to obtain the second dispersion;

[0200] The second adhesive emulsion was added to the second dispersion and stirred at 1500 rpm for 60 minutes to obtain the adhesive solution.

[0201] The specific substances and amounts of the dispersant, insulating filler, and second adhesive are recorded in Table 2.

[0202] The dispersant used in all examples and comparative examples was Chemadd-6004 from Yueyang Kaimen Waterborne Additives Co., Ltd., with a mass fraction of 0.4 parts.

[0203]

[0204]

[0205]

[0206] Viscosity test: The rotational viscosity of the adhesive was tested at 25℃ and 12 rpm, and the results are recorded in Table 3.

[0207] Abrasion resistance test: The above adhesives were applied to 13μm aluminum foil using a 5μm scraper and then dried in a 100℃ oven to prepare the insulating adhesive layer to be tested.

[0208] RCA paper tape abrasion tester (BGD 530, BGD Precision Instruments (Guangzhou) Co., Ltd.); Test principle: The motor drives the paper tape to pass through a region of the test sample surface at a constant speed and applies a certain pressure to wear down the test surface; Test method: 5μm thick insulating adhesive layer to be tested, 55g weight and flat surface are used to run the tape for 300mm (2 turns), and the number of points that are not missed in the test area (a total of 10 points are tested) is recorded in Table 3. At the same time, the area of ​​the missed points is recorded, and the proportion of the area of ​​the area of ​​the points that are not missed to the total area of ​​the test area is calculated.

[0209] Evaluation criteria: Under the same pressure, the longer the paper conveyor belt passes through the un-polished aluminum foil, the more wear-resistant it is; or under the same conveyor belt length, the more un-polished foil points are tested, the more wear-resistant it is.

[0210] Cohesion test:

[0211] The adhesive material was prepared into a slurry and coated onto the carbonized layer of the carbonized copper foil. After drying, a sample sheet was obtained, with one side being the copper foil side and the other side being the adhesive layer formed by the adhesive material. The sample sheet was then cut into strips 2 cm wide and 6 cm long. The copper foil side of the strip was then bonded to a hard substrate (steel plate) using 3M-55230H double-sided tape (ensuring no air bubbles during bonding). 3M-55230H double-sided tape was then bonded to the adhesive side of the fixed strip, and a copper foil strip of the same size as the double-sided tape was placed over the tape (ensuring no air bubbles during bonding). The double-sided tape used in both applications was the same size, resulting in the test sample.

[0212] Manually peel the copper foil and double-sided adhesive from the first end of the test sample at a 180° angle, extending it 1 cm beyond the first end (i.e., the second end) of the entire test sample. Use one clamp of the tensile testing machine to fix the first end (hard substrate, carbon-coated copper foil, adhesive layer); use the other clamp of the tensile testing machine to fix the second end.

[0213] The tensile testing machine was set to a tensile speed of 50 mm / min, and the test tensile length was 100 mm. The peel force data obtained during the test is the cohesive force of the coating material. The results are recorded in Table 3.

[0214] Hardness testing: The hardness of the insulating adhesive layer surface was tested using a Shore A hardness tester. The results are recorded in Table 3.

[0215] Adhesion strength test:

[0216] The above adhesive solutions were applied to 13μm aluminum foil using a 5μm doctor blade and then dried in a 100℃ oven to prepare the insulating adhesive layer to be tested.

[0217] Cut a sample with an insulating adhesive layer, 20 mm wide and 100-160 mm long, using a blade. Apply NITTO NO5000NS double-sided adhesive tape, 20 mm wide and 90-150 mm long, to a steel plate. Fix a paper tape, 80-200 mm longer than the sample and the same width as the sample, onto the double-sided adhesive tape, with a wrinkle-like adhesive layer on top. Place the cut sample onto the wrinkle-like adhesive layer, insulating adhesive side down, and then roll it three times in the same direction using a 3 kg roller to obtain the test sample. The test sample was fixed on the testing machine. The end of the steel plate without the electrode attached was secured with the lower clamp, and the paper tape was folded upwards and secured with the upper clamp. The axis of the sample was aligned with the direction of the applied force. The testing machine was loaded with a peeling speed of 10 mm / min until the sample broke. The test was then stopped, and the maximum load force was recorded as F (in N). The sample width L = 20 mm. The peel strength f1 (in N / m) was calculated according to f1 = F / L. The peel strength is the adhesive force. The results are recorded in Table 3.

[0218] Heat resistance test: Thermogravimetric analysis was performed on the test coating samples using TG-DSC technology, and the thermal decomposition temperature was recorded in Table 3.

[0219] Table 3

[0220]

[0221]

[0222] As can be seen from the comparison of the various embodiments and comparative examples, the wear resistance of the insulating adhesive layer formed by the adhesive composition of this application is significantly better than that of the first adhesive 1 or the second adhesive 1 when used alone; moreover, the viscosity of the first adhesive 1 is too high, which is not conducive to construction when used alone and the adhesion is too low; the viscosity of the second adhesive 1 is too low, which affects the construction performance and thus affects the film formation effect.

[0223] The comparison of Examples 2, 4 and 5, and Examples 1, 6 to 9 shows that when the content of structural unit B in the first adhesive increases and the content of structural unit C decreases, that is, when the content of hard monomer structural units in the first adhesive increases, the adhesive force of the corresponding adhesive composition decreases.

[0224] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An adhesive substance comprising an adhesive, wherein, The adhesive includes structural unit A, structural unit B, structural unit C and structural unit D, with at least a portion of structural unit A crosslinked with at least a portion of structural unit D; Wherein, the structural unit A is ; Each of the structural units B is independently... , , or Any one or more of the following; Each of the structural units C is independently... or In any of the following, m1 is an independent integer from 2 to 12, and m2 is 11; Each of the structural units D is independently... Any one or more of the following, n1 is an independent integer from 1 to 20; At least some of the structural unit A, at least some of the structural unit B, at least some of the structural unit C, and at least some of the structural unit D are connected in a chain-like manner to form a first chain structure. At least some of the structural unit A, at least some of the structural unit C and at least some of the structural unit D are linked together in a chain to form a second chain structure, wherein the second chain structure does not include the structural unit B; At least a portion of structural unit A in the first chain structure is crosslinked with at least a portion of structural unit D in the second chain structure; At least a portion of structural unit D in the first chain structure is crosslinked with at least a portion of structural unit A in the second chain structure. In the adhesive, the molar ratio of structural unit D to structural unit A is 0.5:1-5:1, and the molar content of structural unit A is 4%-50%. In the adhesive, the molar ratio of structural unit C to structural unit B is 1:1-300:1, and the molar content of structural unit B is 0.2%-20%.

2. The adhesive material according to claim 1, wherein, The structural unit B is or .

3. The adhesive material according to claim 1 or 2, wherein, n1 is any integer from 1 to 12.

4. The adhesive material according to claim 1 or 2, wherein, n1 is any integer from 1 to 6.

5. The adhesive material according to claim 1 or 2, wherein, The adhesive material satisfies any one or more of the following conditions: 1) The abrasion resistance of the insulating adhesive layer with a thickness of 3μm-7μm formed by the adhesive material meets the following requirements: The test is conducted using an RCA paper tape abrasion tester. A test area is formed by running a 55g weight on a flat surface for 300mm and 2 turns. n test points are taken in the test area with a spacing of not less than 2cm between the test points. The percentage of no leaks in the test area is more than 30%, where 5≤n≤100, or the area of ​​no leaks in the test area is more than 60% of the total area of ​​the test area. 2) The cohesive strength of the insulating adhesive layer formed by the adhesive material is 620 N / m - 750 N / m; 3) The Shore hardness of the insulating adhesive layer formed by the adhesive material is 45 HA - 80 HA; 4) The adhesive force of the insulating adhesive layer formed by the adhesive material is 30 N / m - 90 N / m.

6. The adhesive material according to claim 5, wherein, The cohesive strength of the insulating adhesive layer formed by the adhesive material is 660 N / m - 725 N / m.

7. The adhesive material according to claim 5, wherein, The insulating adhesive layer formed by the adhesive material has a Shore hardness of 50 HA - 65 HA.

8. The adhesive material according to claim 5, wherein, The adhesive strength of the insulating adhesive layer formed by the adhesive material is 40 N / m - 80 N / m.

9. The adhesive material according to claim 1 or 2, wherein, In the adhesive, the molar ratio of structural unit D to structural unit A is 0.5:1-3:

1.

10. The adhesive material according to claim 9, wherein, In the adhesive, the molar ratio of structural unit D to structural unit A is 1:1 to 3:

1.

11. The adhesive material according to claim 1 or 2, wherein, In the adhesive, the molar content of structural unit A is 4%-10%.

12. The adhesive material according to claim 1 or 2, wherein, In the adhesive, the molar content of the structural unit D is 5%-30%.

13. The adhesive material according to claim 1 or 2, wherein, In the adhesive, the molar content of the structural unit D is 5%-15%.

14. The adhesive material according to claim 1 or 2, wherein, In the adhesive, the molar ratio of structural unit C to structural unit B is 5:1-50:

1.

15. The adhesive material according to claim 1 or 2, wherein, In the adhesive, the molar content of structural unit B is 1%-5%.

16. The adhesive material according to claim 1 or 2, wherein, In the adhesive, the molar content of the structural unit C is 1%-90%.

17. The adhesive material according to claim 16, wherein, In the adhesive, the molar content of the structural unit C is 55%-90%.

18. The adhesive material according to claim 17, wherein, In the adhesive, the molar content of the structural unit C is 75%-80%.

19. The adhesive material according to claim 1 or 2, wherein, The adhesive material also includes insulating fillers and / or dispersants.

20. The adhesive material according to claim 19, wherein, The weight ratio of the insulating filler, the adhesive and the dispersant is (70-90):(10-25):0.

4.

21. The adhesive material according to claim 19, wherein, The insulating filler includes any one or more of the following: alumina, magnesium oxide, silicon dioxide, titanium dioxide, barium titanate, aluminum nitride, silicon nitride, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, mica, talc, boehmite, zeolite, apatite, kaolin, or glass powder.

22. The adhesive material according to claim 19, wherein, The volume average particle size D of the insulating filler V 50≤1μm.

23. The adhesive material according to claim 1 or 2, wherein, The adhesive material also includes a solvent.

24. The adhesive material according to claim 23, wherein, The solid content of the adhesive is 20%-40%.

25. The adhesive material according to claim 23, wherein, The solvent for the adhesive material includes water.

26. The adhesive material according to claim 23, wherein, The viscosity of the adhesive material measured at 25°C and 12 rpm was 350 mPa. s-900 mPa s.

27. An adhesive composition comprising an adhesive, wherein, The adhesive includes a first adhesive and a second adhesive. The first adhesive is a polymer, comprising structural unit A, structural unit B, structural unit C, and structural unit D. The second adhesive is a polymer, comprising structural unit A, structural unit C, and structural unit D, but excluding structural unit B. Wherein, the structural unit A is ; Each of the structural units B is independently... , , or Any one or more of the following; The structural unit C of the first adhesive and the structural unit C of the second adhesive are each independently... or ; m1 can be any integer from 2 to 12 independently, and m2 is 11; The structural unit D of the first adhesive and the structural unit D of the second adhesive are each independently... , n1 is an independent integer from 1 to 20. The first adhesive satisfies the following conditions: 1) The molar content of structural unit A in the first adhesive is 5%-30%; 2) The molar content of structural unit B in the first adhesive is 5%-85%; 3) The molar content of the structural unit C in the first adhesive is 5%-85%; 4) The molar content of the structural unit D in the first adhesive is 5%-15%. The second adhesive satisfies the following conditions: 1) The molar content of structural unit A in the second adhesive is 5%-10%; 2) The molar content of the structural unit C in the second adhesive is 70%-85%; 3) The molar content of the structural unit D in the second adhesive is 5%-20%.

28. The adhesive composition according to claim 27, wherein, The structural unit B is or .

29. The adhesive composition according to claim 27 or 28, wherein, n1 can be any integer from 1 to 12 independently.

30. The adhesive composition according to claim 29, wherein, n1 can be any integer from 1 to 6 independently.

31. The adhesive composition according to claim 27 or 28, wherein, The weight ratio of the first adhesive to the second adhesive is 1:2.5-1:

20.

32. The adhesive composition according to claim 31, wherein, The weight ratio of the first adhesive to the second adhesive is 1:5 to 1:17.

5.

33. The adhesive composition according to claim 27 or 28, wherein, The weight-average molecular weight of the first adhesive is 500,000 to 1,500,000.

34. The adhesive composition according to claim 33, wherein, The difference in weight-average molecular weight between the first adhesive and the second adhesive is 100,000 to 1,500,000.

35. The adhesive composition according to claim 27 or 28, wherein, The adhesive composition further includes insulating fillers and / or dispersants.

36. The adhesive composition according to claim 35, wherein, The weight ratio of the insulating filler, the adhesive and the dispersant is (70-90):(10-25):0.

4.

37. The adhesive composition according to claim 35, wherein, The insulating filler includes any one or more of the following: alumina, magnesium oxide, silicon dioxide, titanium dioxide, barium titanate, aluminum nitride, silicon nitride, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, mica, talc, boehmite, zeolite, apatite, kaolin, or glass powder.

38. The adhesive composition according to claim 37, wherein, The volume average particle size D of the insulating filler V 50≤1μm.

39. The adhesive composition according to claim 35, wherein, The dispersant includes one or more of polyacrylate compounds, fatty alcohol polyether compounds, or polyether-modified siloxane compounds.

40. The adhesive composition according to claim 27 or 28, wherein, The adhesive composition also includes a solvent.

41. The adhesive composition according to claim 40, wherein, The adhesive composition has a solid content of 20%-40%.

42. The adhesive composition according to claim 40, wherein, The solvent in the adhesive composition includes water.

43. A positive electrode plate, comprising: Positive current collector (11), wherein at least one side of the positive current collector (11) has a positive electrode film region and an empty foil region; A positive electrode film layer (12) is disposed in the positive electrode film layer region of the positive electrode current collector (11); An insulating adhesive layer (13) is disposed in the empty foil area of ​​the positive current collector (11), wherein the insulating adhesive layer (13) is formed using any one of claims 1 to 26, or cured by any one of claims 27 to 42.

44. The positive electrode sheet according to claim 43, wherein, The thickness of the insulating adhesive layer (13) is less than or equal to the thickness of the positive electrode film layer (12).

45. The positive electrode sheet according to claim 43, wherein, The thickness of the insulating adhesive layer (13) is 3μm-7μm.

46. ​​A method for preparing a positive electrode sheet, comprising a process of disposing a positive electrode film layer and an insulating adhesive layer on at least one or both sides of a positive electrode current collector (11), wherein, The process of setting the insulating adhesive layer (13) includes: The components of the adhesive substance according to any one of claims 1 to 26 or the adhesive composition according to any one of claims 27 to 42 are mixed to form an adhesive solution; The adhesive is applied to the empty foil area of ​​the positive electrode current collector to obtain a preform with the adhesive. The preform containing the adhesive solution is heated to obtain the insulating adhesive layer.

47. The preparation method according to claim 46, wherein, The heating temperature is 90℃-120℃.

48. The preparation method according to claim 46, wherein, The process of mixing the components of the adhesive composition to form a slurry includes: The dispersant in the adhesive composition is mixed with water to form a first dispersion; The first dispersion is mixed with the insulating filler in the adhesive composition to form a second dispersion; The second dispersion is mixed with the first adhesive in the adhesive composition to form a third dispersion; The third dispersion is mixed with the second adhesive in the adhesive composition to form the adhesive solution.

49. The preparation method according to claim 48, wherein, The mixing that forms the first dispersion is the first stirring, and the stirring time is 5 min-30 min and the stirring speed is 200 rpm-400 rpm.

50. The preparation method according to claim 48, wherein, The mixing that forms the second dispersion is a second stirring, the stirring time being 30 min-120 min and the stirring speed being 1200 rpm-1800 rpm.

51. The preparation method according to claim 48, wherein, The mixing that forms the third dispersion is a third stirring, the third stirring time being 15 min-60 min and the stirring speed being 400 rpm-700 rpm.

52. The preparation method according to claim 48, wherein, The mixing process to form the adhesive solution is a fourth stirring process, which lasts for 5-30 minutes and at a speed of 200-400 rpm.

53. A secondary battery, comprising a positive electrode, wherein, The positive electrode sheet includes the positive electrode sheet according to any one of claims 43 to 45, or the positive electrode sheet obtained by the preparation method according to any one of claims 46 to 52.

54. An electrical device comprising a secondary battery, wherein, The secondary battery includes the secondary battery as described in claim 53.

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