Adhesive, insulating film, battery shell and preparation method thereof, battery monomer, battery and electric equipment

Abstract

The invention relates to an adhesive, an insulating film, a battery shell, a preparation method of the battery shell, a battery monomer, a battery and electric equipment, and the adhesive comprises 60-95 wt% of acrylic resin, 3-35 wt% of an active monomer and 0.8-10 wt% of a photoinitiator. The battery shell comprises a shell body and an insulating protective film, the insulating protective film comprises a connecting layer and a base film layer, and the connecting layer is formed by photo-curing an adhesive layer and is connected with the outer surface of the side wall of the shell body. According to the adhesive, the acrylic resin is taken as a main component, the acrylic resin is matched with the active monomer and the photoinitiator with specific contents, and is cured under the irradiation of light to form a polyester three-dimensional network cross-linked body, so that relatively good adhesion can be provided for an insulating film, and the bonding strength of the insulating film and the surface of a battery shell can be improved.

Description

Adhesive, insulating film, battery shell and preparation method thereof, battery cell, battery and electrical equipment Technical Field

[0001] The present application relates to the field of battery technology, and more specifically, to an adhesive, an insulating film, a battery shell and a preparation method thereof, a battery cell, a battery, and an electrical device. Background Art

[0002] The insulation performance of the battery cell surface is an important indicator. In some solutions, the insulation performance of the battery cell surface is improved by attaching an insulating film to the surface of the battery casing. However, the bonding strength between the insulating film and the surface of the battery casing is currently low.

[0003] It should be noted that the above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art.

[0004] Summary of the Invention

[0005] In view of the above problems, the present application provides an adhesive, an insulating film, a battery shell, a battery cell, a battery and an electrical device. The adhesive can provide better adhesion to the insulating film and can improve the bonding strength between the insulating film and the surface of the battery shell.

[0006] The embodiment of the present application is implemented as follows:

[0007] In a first aspect, an embodiment of the present application provides an adhesive comprising: 60 wt% to 95 wt% of an acrylic resin, 3 wt% to 35 wt% of an active monomer, and 0.8 wt% to 10 wt% of a photoinitiator.

[0008] The adhesive provided in the embodiments of the present application has acrylic resin as its main component, and the acrylic resin is combined with a specific content of active monomer and photoinitiator. Under the irradiation of light, the photoinitiator generates free radicals, causing the acrylic resin and the active monomer to form a complex. The complex is continuously cross-linked, polymerized and cured into a film, forming a polyester three-dimensional network cross-linked body, which can provide better adhesion to the insulating film and improve the bonding strength between the insulating film and the surface of the battery shell.

[0009] In some embodiments, the adhesive comprises 60 wt% to 88 wt% of an acrylic resin, 8 wt% to 28 wt% of a reactive monomer, and 2 wt% to 8 wt% of a photoinitiator. In this embodiment, the acrylic resin, reactive monomer, and photoinitiator are used in a more suitable ratio, achieving good bonding strength, toughness, and dielectric strength.

[0010] In some embodiments, the reactive monomer includes an acrylate monomer. In this embodiment, the acrylate monomer can make the polyester three-dimensional network cross-linked body formed by photocuring have good density, and can provide the insulating film with good rigidity and toughness.

[0011] In some embodiments, the acrylate monomers include one or more of isobornyl acrylate, trimethylolpropane triacrylate, diethylene glycol diacrylate, dimethylolethane triacrylate, tripropylene glycol diacrylate, 2-ethylethyl acrylate, β-hydroxyethyl methacrylate, dipentaerythritol pentaacrylate, 2-methoxyethyl acrylate, bisphenol α dimethacrylate, 1,6-hexanediol diacrylate, and tetrahydrofuran acrylate. In this embodiment, the use of specific acrylate monomers can ensure that the three-dimensional cross-linked polyester network formed by photocuring has better density, thereby providing the insulating film with better rigidity and toughness.

[0012] In some embodiments, the photoinitiator includes one or more of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2-isopropylthioxanthone, 2-phenylbenzyl-2-dimethylamino-1-(4-morpholinobenzylphenyl)butanone, and 2-hydroxy-2-methyl-1-phenylpropanone. In this embodiment, a specific type of photoinitiator is used. The photoinitiator has a suitable UV absorption wavelength and can effectively initiate crosslinking and curing of the adhesive under UV light, thereby providing better adhesion and rigidity to the insulating film.

[0013] In some embodiments, the photoinitiator includes at least two of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2-isopropylthioxanthone, 2-phenylbenzyl-2-dimethylamino-1-(4-morpholinobenzylphenyl)butanone, and 2-hydroxy-2-methyl-1-phenylpropanone. In this embodiment, at least two specific types of photoinitiators are used. The photoinitiators can cover a wider range of UV absorption wavelengths and can better initiate crosslinking and curing of the adhesive under ultraviolet light irradiation, so that the adhesive can have a higher degree of curing under ultraviolet light irradiation, thereby providing better adhesion and rigidity for the insulating film.

[0014] In some embodiments, the photoinitiator includes 1-hydroxycyclohexyl phenyl ketone. In this embodiment, the use of at least two specific types of photoinitiators, including at least 1-hydroxycyclohexyl phenyl ketone, can better initiate crosslinking and curing of the adhesive under UV light, resulting in a higher degree of curing of the adhesive under UV light, thereby providing better adhesion and rigidity to the insulating film.

[0015] In some embodiments, the adhesive further comprises ≤5 wt% of a coupling agent. In this embodiment, the adhesive further comprises a certain amount of a coupling agent, which can provide a bridging effect and provide better adhesion and insulation withstand voltage performance for the insulating film.

[0016] In some embodiments, the coupling agent includes one or more of aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane. In this embodiment, the use of a specific type of coupling agent can effectively provide a bridging effect, effectively improving the adhesion and dielectric withstand voltage performance of the insulating film, thereby achieving higher peel strength and smaller flange lift height.

[0017] In some embodiments, the adhesive further comprises ≤10 wt % of a pigment. In this embodiment, the adhesive further comprises a certain amount of pigment, which can dye the adhesive to an appropriate degree to achieve a target color.

[0018] In the second aspect, an embodiment of the present application provides an insulating film, comprising: a release layer and at least one connecting unit distributed in sequence along the thickness direction of the insulating film, the connecting unit comprising a base film layer and an adhesive layer, the base film layer being located on the side of the adhesive layer away from the release layer; wherein the adhesive layer comprises an adhesive as in the above embodiment.

[0019] An embodiment of the present application provides an insulating film, wherein the adhesive layer includes an adhesive as described in the above embodiment. The insulating film is connected to the surface of the battery shell through the adhesive layer containing the adhesive. The cross-linking agent in the adhesive layer is cured into a film under the irradiation of light, so that the insulating film and the surface of the battery shell have a high bonding strength. At the same time, the connection between the insulating film and the surface of the battery shell is achieved by using a light-curing adhesive, which is simple and convenient to use.

[0020] In some embodiments, the insulating film includes multiple connecting units. In this embodiment, the multiple connecting units configured in the insulating film can make the color of the insulating film consistent, which is helpful in covering scratches on the surface of the battery casing. In addition, the multiple connecting units configured in the insulating film means that the insulating film includes multiple base film layers. When the total thickness of the base film layers in the insulating film is constant, the multiple base film layers can reduce the thickness of each base film layer, which is helpful in improving the problem of warping of the insulating film.

[0021] In some embodiments, the total thickness of the base film layer is T1, and the total thickness of the adhesive layer is T2; wherein T2 = T1 × (50% to 150%); alternatively, T2 = T1 × (80% to 120%). In this embodiment, the adhesive layer and the base film layer meet an appropriate thickness ratio, so that the insulating film can achieve both good adhesion and insulation withstand voltage performance.

[0022] In some embodiments, the thickness of a single adhesive layer is T2'; wherein T2' is ≤ 60 μm. In this embodiment, keeping the thickness of the single adhesive layer below a certain standard facilitates faster curing of the adhesive in the adhesive layer under light irradiation. While providing good adhesion, the adhesive layer can avoid excessive thickness, which could lead to excessive performance and affect production time.

[0023] In some embodiments, the thickness of a single base film layer is T1'; wherein 25 μm ≤ T1' ≤ 80 μm; optionally, 40 μm ≤ T1' ≤ 60 μm. In this embodiment, the thickness of the single base film layer is within a certain range, while still providing good insulation and withstand voltage performance, while avoiding excessive thickness that could lead to excessive performance and affect production schedules.

[0024] In some embodiments, the total thickness of the base film layer is T1, the total thickness of the adhesive layer is T2, and the thickness of the release layer is T3; where T3 = (T1 + T2) × (10% to 50%); optionally, 20 μm ≤ T3 ≤ 50 μm. In this embodiment, the thickness of the release film meets specific standards, allowing the release layer to effectively protect the adhesive layer while avoiding excessive thickness that could result in excessive performance and affect production schedules.

[0025] In a third aspect, an embodiment of the present application provides a battery shell, comprising a shell body and an insulating protective film, wherein the insulating protective film is formed by a connecting unit as in the above embodiment, and the insulating protective film comprises a connecting layer and a base film layer, wherein the connecting layer is formed by photocuring an adhesive layer; wherein the outer surface of the side wall of the shell body is connected to the connecting layer.

[0026] In a fourth aspect, an embodiment of the present application provides a battery cell, comprising a battery housing as described in the above embodiment.

[0027] In a fifth aspect, an embodiment of the present application provides a battery, comprising a battery cell as described in the above embodiment.

[0028] In a sixth aspect, an embodiment of the present application provides an electrical device, including a battery as in the above embodiment or a battery as in the above embodiment.

[0029] In the seventh aspect, an embodiment of the present application provides a method for preparing a battery shell, comprising: providing a shell body; removing the release layer of the insulating film as in the above embodiment, leaving a connecting unit; using the connecting unit to wrap the shell body, contacting the outer surface of the side wall of the shell body through the adhesive layer, and allowing the adhesive layer to be photocured to form a connecting layer.

[0030] The above description is only an overview of the technical solutions of the embodiments of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0032] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0033] FIG2 is an exploded view of a battery provided in some embodiments of the present application;

[0034] FIG3 is an exploded view of a battery cell provided in some embodiments of the present application;

[0035] FIG4 is a schematic structural diagram of a battery housing provided in some embodiments of the present application;

[0036] FIG5 is a schematic structural diagram of a first insulating film provided in some embodiments of the present application;

[0037] FIG6 is a schematic structural diagram of a second insulating film provided in some embodiments of the present application.

[0038] 1000-vehicles;

[0039] 100-battery; 200-controller; 300-motor;

[0040] 10-box; 11-first part; 12-second part; 13-accommodation space;

[0041] 20 - battery cell; 21 - housing; 22 - electrode assembly; 23 - electrode terminal; 24 - pressure relief structure;

[0042] 211-battery housing; 212-cover;

[0043] 2110 - shell body; 2111 - shell side wall; 2112 - shell bottom wall; 2113 - insulating film; 21131 - release layer; 21132 - connecting unit; 21132a - base film layer; 21132b - adhesive layer; 2114 - insulating protective film; 21141 - connecting layer. DETAILED DESCRIPTION

[0044] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0045] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0047] In the description of the embodiments of this application, the technical terms "first," "second," etc. are used only to distinguish different objects and should not be understood to indicate or imply relative importance or to implicitly indicate the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise specifically defined.

[0048] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0049] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0050] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0051] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application.

[0052] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0053] Currently, market developments indicate that power batteries are becoming increasingly widely used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric vehicles, as well as in military equipment and aerospace. As power battery applications continue to expand, market demand is also growing.

[0054] Battery casings (such as cylindrical battery casings) are generally made of steel, which is not resistant to slight acid and alkali corrosion and is prone to aging under the use environment.

[0055] Some currently proposed technical solutions employ a pressure-sensitive adhesive insulating protective film attached to the sides of the battery casing to meet insulation requirements during battery assembly while also providing corrosion protection. However, the bonding strength between the current insulating film and the battery casing surface is low, posing a risk of interlaminar failure under harsh operating conditions.

[0056] Based on this, the applicant designed an adhesive comprising specific amounts of acrylic resin, reactive monomers, and photoinitiators, and illustratively, a suitable amount of coupling agent. This adhesive is applied to the insulating film's adhesive layer, which, upon photocuring, forms a connecting layer bonded to the surface of the battery casing. This connecting layer forms a three-dimensional cross-linked polyester network, providing excellent adhesion to the insulating film and enhancing the bonding strength between the insulating film and the battery casing.

[0057] In the present application, electrical equipment can be in various forms, for example, mobile phones, portable devices, laptops, battery vehicles, electric cars, ships, spacecraft, electric toys and electric tools, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft, etc. Electric toys include fixed or mobile electric toys, for example, game consoles, electric car toys, electric ship toys and electric airplane toys, etc. Electric tools include metal cutting power tools, grinding power tools, assembly power tools and railway power tools, for example, electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers.

[0058] For the convenience of explanation, the following embodiments are described by taking a vehicle as an example of an electrical device in the embodiments of the present application.

[0059] Refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0060] In some embodiments of the present application, the battery 100 can not only serve as the operating power source of the vehicle 1000, but also serve as the driving power source of the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0061] In this application, a battery 100 refers to a single physical module that includes multiple battery cells 20 to provide higher voltage and capacity. It can be in the form of a battery pack, a battery module, etc. The battery 100 can include a housing 10 for enclosing the multiple battery cells 20. The housing 10 can prevent liquids or other foreign matter from affecting the charging or discharging of the battery cells 20.

[0062] Referring to FIG2 , FIG2 is an exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a housing 10 and a plurality of battery cells 20, wherein the plurality of battery cells 20 are housed in the housing 10. The housing 10 is used to house the battery cells 20, and the housing 10 can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, wherein the first portion 11 and the second portion 12 overlap each other, and the first portion 11 and the second portion 12 jointly define a housing space 13 for accommodating the battery cells 20. The second portion 12 can be a hollow structure with one end open, and the first portion 11 is a plate-like structure, and the first portion 11 overlaps the open side of the second portion 12 to form the housing 10 with the housing space 13; the first portion 11 and the second portion 12 can also be hollow structures with one side open, and the open side of the first portion 11 overlaps the open side of the second portion 12 to form the housing 10 with the housing space 13. Of course, the first part 11 and the second part 12 can be in various shapes, such as a cylinder, a cuboid, etc.

[0063] In the battery 100, multiple battery cells 20 can be connected in series, in parallel, or in a hybrid configuration. A hybrid configuration refers to a combination of series and parallel connections among the multiple battery cells 20. Multiple battery cells 20 can be directly connected in series, in parallel, or in a hybrid configuration, and then the entire structure of the multiple battery cells 20 is housed within the housing 10. Alternatively, multiple battery cells 20 can be first connected in series, in parallel, or in a hybrid configuration to form a module, which is then connected in series, in parallel, or in a hybrid configuration to form a complete structure housed within the housing 10. The battery 100 may also include other structures. For example, multiple battery cells 20 can be electrically connected via a busbar to enable parallel, series, or hybrid connection of the multiple battery cells 20.

[0064] The battery cell 20 is the smallest unit that makes up the battery pack 100. The battery cell 20 can be a secondary battery 100 or a primary battery 100; it can also be a lithium-sulfur battery 100, a sodium-ion battery 100, or a magnesium-ion battery 100, but is not limited thereto.

[0065] 3 , the battery cell 20 may include a housing 21 , an electrode assembly 22 , and an electrolyte, and both the electrode assembly 22 and the electrolyte are accommodated in the housing 21 .

[0066] The outer shell 21 may include a battery shell 211 and a cover 212. The battery shell 211 is a component used to cooperate with the cover 212 to form an internal sealed space of the battery cell 20, wherein the formed sealed space can be used to accommodate the electrode assembly 22, electrolyte and other components. The cover 212 refers to a component that covers the opening of the battery shell 211 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the cover 212 can be adapted to the shape of the battery shell 211 to cooperate with the battery shell 211. Functional components such as electrode terminals 23 and pressure relief structures 24 can also be provided on the cover 212. A sealing ring can be configured between the opening of the battery shell 211 and the cover 212 to achieve sealing between the battery shell 211 and the cover 212.

[0067] The battery housing 211 and the cover 212 can be selected from a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shapes of the battery housing 211 and the cover 212 can be determined according to the specific shape and size of the electrode assembly 22. The material of the battery housing 211 and the cover 212 can be selected from a variety of materials, such as but not limited to copper, iron, aluminum, stainless steel, aluminum alloy and other metals. The material of the sealing ring can be selected from a variety of materials, such as but not limited to PP (polypropylene), PC (polycarbonate), PET (polyethylene terephthalate) and other materials that are resistant to electrolyte corrosion, high toughness and fatigue resistance.

[0068] Referring to Figure 4 , an insulating protective film 2114 is attached to the surface of the battery housing 211. This insulating protective film 2114 is formed from an insulating film 2113 (see Figures 5 and 6 ) provided in an embodiment of the present application. The adhesive layer 21132b of the insulating film 2113 contains an adhesive provided in an embodiment of the present application. Prior to attaching the insulating protective film 2114, a coating may be formed on the outer surface of the battery housing 211. The coating may be made of a variety of materials, such as, but not limited to, corrosion-resistant materials such as Ni and Cr.

[0069] The electrode assembly 22 may be composed of a positive electrode sheet, a negative electrode sheet, and a separator. The battery cell 20 primarily operates by the movement of metal ions between the positive electrode sheet and the negative electrode sheet.

[0070] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the surface of the positive electrode current collector. The positive electrode current collector can be made of aluminum, and the positive electrode active material in the positive electrode active material layer can include lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganese oxide, lithium sulfur, and other positive electrode active material materials. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on the surface of the negative electrode current collector. The negative electrode current collector can be made of copper, and the negative electrode active material in the negative electrode active material layer can be carbon, silicon, and other negative electrode active material materials. In addition, the electrode assembly 22 can be a wound structure or a laminated structure, but the embodiments of the present application are not limited to this.

[0071] Next, the adhesive, insulating film 2113, battery housing 211, battery cell 20, battery 100 and electrical equipment proposed in the embodiment of the present application are described in detail.

[0072] In a first aspect, an embodiment of the present application provides an adhesive comprising: 60 wt% to 95 wt% of an acrylic resin, 3 wt% to 35 wt% of an active monomer, and 0.8 wt% to 10 wt% of a photoinitiator.

[0073] Optionally, the adhesive includes: 60 wt% to 88 wt% of acrylic resin, 10 wt% to 20 wt% of active monomer, 2 wt% to 5 wt% of photoinitiator, ≤5 wt% of coupling agent, and ≤10 wt% of pigment.

[0074] Acrylic resin is a polymer obtained by polymerizing acrylic acid or acrylic acid derivatives as monomers, or a polymer obtained by copolymerizing acrylic acid or acrylic acid derivatives with other unsaturated compounds.

[0075] The type of acrylic resin is not limited, for example, including one or more of ARONIX M-7100, ARONIX M-8030, ARONIX M-8060, ARONIX M-90, AgiSyn 720, NeoRad P-56, allnex unsaturated polyester resin UVECOAT@9010, allnex unsaturated polyester resin UVECOAT@2100 and allnex unsaturated polyester resin UVECOAT@3005.

[0076] The content of acrylic resin in the adhesive is, for example but not limited to, any one of 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt% and 95wt% or a range between any two of them.

[0077] The reactive monomer is a material that can improve the rheological properties of the oligomer formed during the light curing process of the adhesive, and can include one or more reactive monomers with monofunctionality, difunctionality, trifunctionality, and higher functionality.

[0078] The content of the active monomer in the adhesive is, for example but not limited to, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, 31wt%, 32wt%, 33wt%, 34wt% and 35wt%, any one of the values ​​or the range between any two of them.

[0079] Photoinitiator, also known as photosensitizer or photocuring agent, is a type of compound that can absorb energy of a certain wavelength in the ultraviolet light region (250nm~420nm) or visible light region (400nm~800nm), generate free radicals, cations, etc., thereby initiating monomer polymerization, cross-linking and curing.

[0080] The content of the photoinitiator in the adhesive is, for example but not limited to, any one of 0.8wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt% and 10wt%, or a range between any two of them.

[0081] The adhesive provided in the embodiment of the present application has acrylic resin as the main component, and the acrylic resin is combined with a specific content of active monomers and photoinitiators. Under the irradiation of light, free radicals are generated by the photoinitiator, causing the acrylic resin and the active monomers to form a complex. The complex is continuously cross-linked, polymerized and solidified into a film, forming a polyester-based three-dimensional network cross-linked body, which can provide better adhesion to the insulating film 2113 and improve the bonding strength between the insulating film 2113 and the surface of the battery shell 211.

[0082] In some embodiments, the adhesive includes 60 wt % to 88 wt % of an acrylic resin, 8 wt % to 28 wt % of a reactive monomer, and 2 wt % to 8 wt % of a photoinitiator.

[0083] Optionally, the adhesive includes: 60 wt% to 88 wt% of acrylic resin, 10 wt% to 20 wt% of active monomer, and 2 wt% to 5 wt% of photoinitiator.

[0084] It should be noted that, in the embodiments of the present application, when the contents of the above components are within a specific range, if the total is less than 100%, it means that other components such as solvents and additives may also be present in the adhesive.

[0085] In this embodiment, the acrylic resin, the active monomer and the photoinitiator have a more appropriate usage ratio, and can have good bonding strength, toughness and insulation withstand voltage performance.

[0086] In some embodiments, the reactive monomer comprises an acrylate monomer.

[0087] The acrylate monomer refers to a monomer of acrylic acid or an acrylic acid derivative.

[0088] In this embodiment, the acrylate monomer can make the polyester three-dimensional network cross-linked body formed by photocuring have better density, and can provide the insulating film 2113 with better rigidity and toughness.

[0089] In some embodiments, the acrylate monomer includes one or more of isobornyl acrylate, trimethylolpropane triacrylate, diethylene glycol diacrylate, dimethylolethane triacrylate, tripropylene glycol diacrylate, 2-ethylethyl acrylate, β-hydroxyethyl methacrylate, dipentaerythritol pentaacrylate, 2-methoxyethyl acrylate, bisphenol alpha dimethacrylate, 1,6-hexanediol diacrylate, and tetrahydrofuran acrylate.

[0090] In some exemplary embodiments, the acrylate monomer includes one or more of dimethylolethane triacrylate, bisphenol α dimethacrylate, tetrahydrofuran acrylate, and diethylene glycol diacrylate.

[0091] In this embodiment, a specific type of acrylic ester monomer is used to make the polyester three-dimensional network cross-linked body formed by photocuring have better density, thereby providing the insulating film 2113 with better rigidity and toughness.

[0092] In some embodiments, the photoinitiator includes one or more of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2-isopropylthioxanthone, 2-phenylbenzyl-2-dimethylamino-1-(4-morpholinobenzylphenyl)butanone, and 2-hydroxy-2-methyl-1-phenylpropanone.

[0093] In this embodiment, a specific type of photoinitiator is used. The photoinitiator has a suitable UV absorption wavelength and can effectively initiate cross-linking and curing of the adhesive under ultraviolet light, thereby providing better adhesion and rigidity for the insulating film 2113.

[0094] In some embodiments, the photoinitiator includes at least two of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2-isopropylthioxanthone, 2-phenylbenzyl-2-dimethylamino-1-(4-morpholinobenzylphenyl)butanone, and 2-hydroxy-2-methyl-1-phenylpropanone.

[0095] In some exemplary embodiments, the photoinitiator includes at least two of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-isopropylthioxanthone, and 1-hydroxycyclohexylphenyl ketone.

[0096] In this embodiment, at least two specific types of photoinitiators are used. The photoinitiators can cover a wider UV absorption wavelength and can better initiate the cross-linking and curing of the adhesive under ultraviolet light, so that the adhesive can have a higher degree of curing under ultraviolet light, thereby providing better adhesion and rigidity for the insulating film 2113.

[0097] In some embodiments, the photoinitiator includes 1-hydroxycyclohexyl phenyl ketone. Optionally, the mass proportion of 1-hydroxycyclohexyl phenyl ketone in the photoinitiator is, for example, 80 wt% to 95 wt%, such as, but not limited to, any one of 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt% and 95 wt%, or a range between any two of the above.

[0098] In some exemplary embodiments, the photoinitiator includes 1-hydroxycyclohexylphenyl ketone and ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0099] In this embodiment, at least two specific types of photoinitiators are used, and at least 1-hydroxycyclohexyl phenyl ketone is contained, which can better initiate cross-linking and curing of the adhesive under ultraviolet light, so that the adhesive can have a higher degree of curing under ultraviolet light, thereby providing better adhesion and rigidity for the insulating film 2113.

[0100] In some embodiments, ≤ 5 wt % of a coupling agent is also included.

[0101] Coupling agents are a class of substances with two functional groups of different properties, one is an inorganic-philic group and the other is an organic-philic group.

[0102] The content of the coupling agent in the adhesive is, for example but not limited to, any one of 0 wt %, 1 wt %, 2 wt %, 3 wt %, 4 wt % and 5 wt %, or a range between any two of them.

[0103] In the embodiments of the present application, the content of the coupling agent in the adhesive may be 0, and it may be selected whether to add the coupling agent as needed.

[0104] In this embodiment, the adhesive further includes a certain amount of coupling agent, which can provide a bridging effect and provide the insulating film with better adhesion and insulation withstand voltage performance.

[0105] In some embodiments, the coupling agent includes one or more of aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane.

[0106] KH-550 is aminopropyltriethoxysilane, KH-560 is γ-glycidoxypropyltrimethoxysilane, and KH-570 is γ-methacryloxypropyltrimethoxysilane.

[0107] In this embodiment, a specific type of coupling agent is used to provide a better bridging effect, which can effectively provide better adhesion and insulation withstand voltage performance for the insulating film 2113, so that the insulating film 2113 has higher peel strength and smaller flange lift height.

[0108] In some embodiments, ≤ 10 wt % of pigment is also included.

[0109] Pigments can be used to dye the adhesive, thereby obtaining an insulating layer of a target color. Examples of target colors include benzidine yellow, phthalocyanine blue, permanent red, pink, sapphire, or sun-fast crimson. Examples of pigments include one or more of azo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, isoindolinoline pigments, benzimidazolone pigments, dioxazine pigments, perylene pigments, perinone pigments, anthraquinone pigments, anthrapyrimidine pigments, and indanthrene pigments.

[0110] The content of the pigment in the adhesive is, for example but not limited to, any one of 0wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% and 10wt%, or a range between any two of them.

[0111] In the embodiments of the present application, the content of pigment in the adhesive may be 0, and it may be selected whether to add pigment as needed.

[0112] In this embodiment, the adhesive further includes a certain amount of pigment, which can dye the adhesive to an appropriate degree to achieve the target color.

[0113] 5 and 6 , in the second aspect, an embodiment of the present application provides an insulating film 2113, comprising: a release layer 21131 and at least one connecting unit 21132 distributed in sequence along the thickness direction of the insulating film 2113, the connecting unit 21132 comprising a base film layer 21132a and an adhesive layer 21132b, the base film layer 21132a being located on the side of the adhesive layer 21132b away from the release layer 21131; wherein, the adhesive layer 21132b comprises an adhesive as in the above embodiment.

[0114] 5 , when there is only one connecting unit 21132 , the release layer 21131 , the adhesive layer 21132 b and the base film layer 21132 a are sequentially distributed along the thickness direction of the insulating film 2113 .

[0115] Referring to FIG. 6 , when there are n connecting units 21132 (n is an integer ≥ 2), the release layer 21131, the first connecting unit 21132, the nth connecting unit 21132, and the release layer 21131 are sequentially distributed along the thickness direction of the insulating film 2113. Taking two connecting units 21132 as an example, the release layer 21131, the first connecting unit 21132, and the second connecting unit 21132 are sequentially distributed along the thickness direction of the insulating film 2113. Specifically, within the sequentially distributed plurality of connecting units 21132, the release layer 21131 and the adhesive layer 21132b are alternately distributed, such that, along the thickness direction of the insulating film 2113, the outermost layer on one side of the plurality of connecting units 21132 is the release layer 21131, and the outermost layer on the other side is the adhesive layer 21132b, with the release layer 21131 covering the outermost adhesive layer 21132b of the plurality of connecting units 21132.

[0116] Before use, the insulating film 2113 is protected by a release layer 21131 that protects the adhesive layer 21132b located on the outermost layer of the connecting unit 21132. During use, the insulating film 2113 is removed and then connected to a target surface, such as the outer surface of the battery housing 2111, via the adhesive layer 21132b located on the outermost layer of the connecting unit 21132. The target surface is the surface protected by the insulating film 2113, such as the outer surface of the battery housing 211. The release film is a membrane-like structure that can be connected to and separated from the adhesive layer 21132b. It can be made of any material, such as, but not limited to, release film or release paper.

[0117] The base film layer 21132a is a film layer with insulating properties, such as an insulating polyester film PET.

[0118] An embodiment of the present application provides an insulating film 2113, wherein the adhesive layer 21132b includes an adhesive as described in the above embodiment. The insulating film 2113 is connected to the surface of the battery housing 211 through the adhesive layer 21132b containing the adhesive. The cross-linking agent in the adhesive layer 21132b is cured into a film under the irradiation of light, so that the insulating film 2113 and the surface of the battery housing 211 have a high bonding strength. At the same time, the insulating film 2113 is connected to the surface of the battery housing 211 by using a light-curing adhesive, which is simple and convenient to use.

[0119] In some embodiments, the insulating film 2113 includes a plurality of connection units 21132 .

[0120] In some exemplary embodiments, the insulating film 2113 includes two connecting units 21132, that is, its structure is as shown in Figure 6, including a release layer 21131, an adhesive layer 21132b, a base film layer 21132a, an adhesive layer 21132b and a base film layer 21132a distributed in sequence along the direction of the insulating film 2113.

[0121] In this embodiment, the insulating film 2113 is covered with a plurality of connecting units 21132, which makes the color of the insulating film 2113 more favorable for covering scratches on the surface of the battery housing 211; in addition, the insulating film 2113 is provided with a plurality of connecting units 21132, that is, the insulating film 2113 includes a plurality of base film layers 21132a. When the total thickness of the base film layers 21132a in the insulating film 2113 is constant, the plurality of base film layers 21132a are provided so that the thickness of a single base film layer 21132a is reduced, which is favorable for improving the problem of curling of the insulating film 2113.

[0122] 5 and 6 , in some embodiments, the total thickness of the base film layer 21132a is T1, and the total thickness of the adhesive layer 21132b is T2; wherein, T2 = T1×(50% to 150%); optionally, T2 = T1×(80% to 120%).

[0123] As an example, the ratio of T1 and T2 is expressed as a percentage, such as but not limited to any point value of 50%, 60%, 70%, 80%, 90%, 100%, 110% and 120%, or a range of values ​​between any two.

[0124] In this embodiment, the adhesive layer 21132b and the base film layer 21132a satisfy a suitable thickness ratio, so that the insulating film 2113 can have both good adhesion and insulation withstand voltage performance.

[0125] 5 and 6 , in some embodiments, the thickness of the single adhesive layer 21132 b is T2 ′; wherein T2 ′ is ≤ 60 μm.

[0126] As an example, the thickness T2' of the single adhesive layer 21132b is, for example but not limited to, any one of 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm and 60 μm, or a range between any two of them.

[0127] In this embodiment, the thickness of the single adhesive layer 21132b is below a certain standard, which is conducive to the adhesive in the adhesive layer 21132b to cure faster under the irradiation of light. While the adhesive layer 21132b can provide better adhesion, it avoids the adhesive layer 21132b being too thick, resulting in excess performance and affecting the production rhythm.

[0128] 5 and 6 , in some embodiments, the thickness of the single-layer base film layer 21132 a is T1 ′; wherein, 25 μm ≤ T1 ′ ≤ 80 μm; optionally, 40 μm ≤ T1 ′ ≤ 60 μm.

[0129] As an example, the thickness T1' of the single-layer base membrane layer 21132a is any point value of 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 55μm, 60μm, 65μm, 70μm, 75μm and 80μm, or a range value between any two of them.

[0130] In this embodiment, the thickness of the single-layer base film layer 21132a is within a certain range. While the base film layer 21132a can exert good insulation and voltage resistance performance, it avoids the base film layer 21132a being too thick to cause excess performance and affect the production rhythm.

[0131] 5 and 6 , in some embodiments, the total thickness of the base film layer 21132a is T1, the total thickness of the adhesive layer 21132b is T2, and the thickness of the release layer 21131 is T3; wherein, T3 = (T1 + T2) × (10% to 50%); optionally, 20 μm ≤ T3 ≤ 50 μm.

[0132] As an example, the ratio of T3 to (T1+T2) is expressed as a percentage, such as but not limited to any one of 10%, 20%, 30%, 40% and 10%, or a range between any two of them.

[0133] As an example, the thickness T3 of the release layer 21131 is, for example but not limited to, any one of 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm and 50 μm, or a range between any two of them.

[0134] In this embodiment, the thickness of the release film meets specific standards, so that the release layer 21131 can better protect the adhesive layer 21132b, while avoiding the release film being too thick to cause excess performance and affect the production rhythm.

[0135] Referring to Figure 4, in the third aspect, an embodiment of the present application provides a battery shell 211, including a shell body 2110 and an insulating protective film 2114, the insulating protective film 2114 is formed by a connecting unit 21132 as in the above embodiment, the insulating protective film 2114 includes a connecting layer 21141 and a base film layer 21132a, the connecting layer 21141 is formed by photocuring of an adhesive layer 21132b; wherein, the outer surface of the side wall of the shell body 2110 is connected to the connecting layer 21141.

[0136] The shell body 2110 includes a shell side wall 2111 and a shell bottom wall 2112 that are connected to each other. The connection between the shell side wall 2111 and the shell bottom wall 2112 has, for example, a connecting weld.

[0137] The shell sidewall 2111 is an annular sidewall formed by a circle around the central axis of the battery shell 211. It is a hollow structure with openings at both ends. The internal cavity is used to accommodate the electrode assembly 22, electrolyte, and other components. The top opening is used to mate with the cover 212, and the bottom opening is used to mate with the shell bottom wall 2112. The shape of the shell sidewall 2111 is not limited. In a cross section perpendicular to the central axis of the battery shell 211, the sidewall shape can be, for example, but not limited to, circular, rectangular, hexagonal, etc., for example, circular.

[0138] The bottom wall 2112 is a thin-walled structure at the bottom of the battery housing 211. The bottom wall 2112 has a shape corresponding to the opening at the bottom of the side wall 2111 and is used to close the opening at the bottom of the side wall 2111.

[0139] In the embodiment of the present application, the insulating protective film 2114, for example, covers at least a portion of the outer surface of the shell sidewall 2111. Optionally, the insulating protective film 2114 can also cover the connecting weld by folding or other means, or even cover at least a portion of the outer surface of the shell bottom wall 2112.

[0140] In a fourth aspect, an embodiment of the present application provides a battery cell 20 , comprising a battery housing 211 as described in the above embodiment.

[0141] In a fifth aspect, an embodiment of the present application provides a battery 100 comprising a battery cell 20 as described in the above embodiment.

[0142] In a sixth aspect, an embodiment of the present application provides an electrical device, comprising a battery 100 as in the above embodiment or a battery 100 as in the above embodiment.

[0143] According to some embodiments of the present application, the adhesive includes an acrylic resin, an active monomer, a photoinitiator, a coupling agent and a pigment; wherein the active monomer includes one or more of dimethylolethane triacrylate, bisphenol α dimethacrylate, tetramethylene acrylate and diethylene glycol diacrylate, the photoinitiator includes at least two of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, 2-isopropylthioxanthone and 1-hydroxycyclohexyl phenyl ketone, and the coupling agent includes one or more of KH-550, KH-560 and KH-570.

[0144] According to some embodiments of the present application, a method for preparing an adhesive is provided, comprising: heating and stirring an acrylic resin at a heating temperature of 50°C to 60°C; adding an active monomer to the mixture and stirring and mixing uniformly, then sequentially adding a photoinitiator and a pigment, and stirring and mixing uniformly again; grinding the mixture to a fineness of ≤5 μm, adding a coupling agent, and stirring and mixing uniformly to obtain an adhesive.

[0145] In the seventh aspect, an embodiment of the present application provides a method for preparing a battery shell 211, including: providing a shell body 2110; removing the release layer 21131 of the insulating film 2113 as in the above embodiment, leaving the connecting unit 21132; using the connecting unit 21132 to encapsulate the shell body 2110, contacting the outer surface of the side wall of the shell body 2110 through the adhesive layer 21132b, and allowing the adhesive layer 21132b to be photocured to form a connecting layer 21141.

[0146] In some embodiments, the release layer 21131 is removed, and the insulating film 2113 is illuminated to remove the remaining connection units 21132 after the release layer 21131 is removed. The connection units 21132 are then cut, and the shell body 2110 is then coated with the connection units 21132. The shell body 2110 is then left to cure, thereby obtaining the battery shell 211 provided in the embodiments of the present application.

[0147] In some embodiments, the release layer 21131 is removed, and the remaining connection units 21132 are cut from the insulating film 2113. The shell body 2110 is coated with the connection units 21132, and then the connection units 21132 are illuminated. The shell body 2110 is then left to cure, thereby obtaining the battery shell 211 provided in the embodiments of the present application.

[0148] Those skilled in the art will understand that, in the above-mentioned preparation method, the writing order of each step does not mean a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0149] The irradiation can be performed first and then the film coating can be performed, or the film coating can be performed first and then the irradiation. For example, the irradiation can be performed first and then the film coating can be performed.

[0150] Optionally, the irradiation process utilizes ultraviolet light, illustratively including the following conditions: a UV light source is selected from a UV LED, and a wavelength of 365 nm, 385 nm, or 405 nm is selected based on the absorption band of the photoinitiator in the adhesive layer 21132 b. The UV activation energy is selected from 500 mJ / cm² to 10,000 mJ / cm², and the activation time is 0.1 s to 10 s. Furthermore, the UV activation energy is selected from 1,000 mJ / cm² to 6,000 mJ / cm², and the activation time is 1 s to 6 s.

[0151]

[0152] Some specific embodiments are listed below to better illustrate the present application.

[0153] The outer surface of the shell sidewall 2111 of the shell body 2110 is coated with the insulating film 2113 as shown in FIG. 5 , so that the insulating film 2113 of the above embodiment forms the insulating protective film 2114 of the above embodiment.

[0154] The insulating film 2113 includes a release layer 21131, an adhesive layer 21132b, and a base film layer 21132a, arranged sequentially along the thickness direction. Adhesive layer 21132b is 50 μm thick and made of adhesive. Base film layer 21132a is 50 μm thick and made of insulating polyester film (PET).

[0155] During the light curing process, the conditions are as follows:

[0156] The light source is UVLED, the absorption band is 370nm, the UV activation energy is 4500mJ / cm2, and the activation time is 3s.

[0157] The types of adhesive components in each embodiment and comparative example are shown in Table 1, and the amounts of adhesive components in each embodiment and comparative example are shown in Table 2. The acrylic resin used in each embodiment and comparative example is: model UVECOAT@2100, name allnex unsaturated polyester resin.

[0158] Table 1. Component types of adhesives in various embodiments and comparative examples

[0159]

[0160] Table 2. Component dosage of adhesives in various examples and comparative examples

[0161]

[0162] In addition, Comparative Example 2 provides an adhesive comprising 10 wt % of acrylic acid, 15 wt % of methyl acrylate, 17 wt % of methyl methacrylate, 25 wt % of butyl acrylate, 30 wt % of ethyl acetate, 0.5 wt % of benzoyl peroxide, and 2.5 wt % of sodium dodecylbenzenesulfonate.

[0163] The performance of the insulating protective films of the battery cases of the embodiments and comparative examples was tested.

[0164] The detection method is as follows:

[0165] 1. Anti-flaring and warping performance

[0166] Bend the insulating film 90° and attach it to the aluminum shell of the battery cell. The bending length is 4mm. Observe the degree of warping and measure the height of the warping edge.

[0167] 2. Adhesion

[0168] Testing was performed according to the GB / T 9286-1998 method. An insulating protective film was adhered to the surface of a 150 x 100 mm aluminum plate and placed on a horizontal, rigid surface. A grid knife was used to cut perpendicular to the sample, ensuring that all cuts penetrated the substrate surface. An equal number of cuts were then made at 90° angles to the original cut lines to form a grid. The surface was then brushed several times with a soft brush. Transparent tape was applied over the grid, flattened, and removed. The adhesion of the insulating protective film was determined using the adhesion grading chart, and the 180° peel strength was recorded.

[0169] 3. Shear strength

[0170] Standard aluminum sheets with insulating protective film were overlapped with structural adhesive and tested according to GB / T 7124 method.

[0171] 4. Aging test

[0172] Place a standard aluminum sheet with an insulating protective film under 85°C / 85% humidity conditions for 1000 hours, and test the shear strength of the insulating protective film after aging. Record this as the shear strength after aging.

[0173] 5. Insulation withstand voltage test

[0174] Cut the insulating protective film into 5×5cm rectangular strips and stick them on the surface of the aluminum plate. Use an insulation withstand voltage tester to perform a 2700V, 60s withstand voltage test. If the leakage current is ≤0.1mA, it passes and the result is expressed as "OK"; if the leakage current is greater than 0.1mA, it fails and the result is expressed as "NG".

[0175] The test results are shown in Tables 3 and 4 below:

[0176] Table 3. Performance test results of the insulating protective films of various embodiments

[0177]

[0178] Table 4. Performance test results of the insulating protective films of various comparative examples

[0179]

[0180] According to Tables 1 to 4, a brief analysis is as follows:

[0181] In Examples 1 to 3, the components of the adhesive meet the appropriate types and amounts. Compared with Comparative Example 2, the peel strength, shear strength and shear strength after aging of the insulating protective film are significantly improved.

[0182] In Examples 3 through 6 and Comparative Example 1, the acrylic resin content in the adhesive varied, while the mass ratios of the other components remained consistent. Compared to Example 3, Example 4 and Comparative Example 1 had lower acrylic resin content, resulting in Example 3 exhibiting higher peel strength, shear strength, aged shear strength, and dielectric withstand voltage performance. Furthermore, Examples 5 and 6 had higher acrylic resin content, resulting in Example 3 exhibiting higher dielectric withstand voltage performance.

[0183] In Examples 3 and 7-10, the active monomer content in the adhesive varied, while the mass ratios of the other components remained consistent. Compared to Example 3, Examples 7 and 8 contained lower amounts of active monomer, resulting in Example 3 exhibiting lower flange lift heights, higher peel strength, higher shear strength, and higher shear strength after aging. Examples 9 and 10 contained higher amounts of active monomer, resulting in Example 3 exhibiting lower flange lift heights. Furthermore, compared to Examples 7-10, Example 3 and Examples 8-9 all exhibited higher edge pressure resistance.

[0184] In Example 3 and Examples 11 to 14, the photoinitiator content in the adhesive varied, while the mass ratios of the other components remained consistent. Compared to Example 3, Examples 11 and 12 contained lower levels of photoinitiator, resulting in Example 3 exhibiting lower flange lift heights, higher peel strength, higher shear strength, higher shear strength after aging, and higher edge pressure resistance. In Examples 13 and 14, the photoinitiator content was higher, resulting in Example 3 exhibiting lower flange lift heights. Furthermore, compared to Examples 3 and 11 to 14, Example 3 and Examples 12 to 13 all exhibited higher edge pressure resistance.

[0185] In Examples 3, 15, and 16, the coupling agent content in the adhesive varied, while the mass ratios of the other components remained consistent. Compared to Example 3, Examples 15 and 16 contained higher amounts of coupling agent, resulting in Example 3 exhibiting higher peel strength, higher shear strength, and higher shear strength after aging. Furthermore, compared to Example 1, Examples 3 and 15 exhibited higher edge pressure resistance.

[0186] In Example 3, Example 17 and Example 19, the adhesives of Example 17 and Example 19 only use one photoinitiator, and the peel strength, shear strength and shear strength after aging of the insulating protective film in Example 3 are higher.

[0187] In Example 3, Example 18 and Example 20, the adhesives of Example 18 and Example 20 do not contain a coupling agent, the peel strength and insulation withstand voltage performance of the insulating protective film in Example 3 are higher, and the height of the flange warping is lower.

[0188] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. An adhesive, wherein: include: 60wt% to 95wt% of acrylic resin, 3wt% to 35wt% of active monomer and 0.8wt% to 10wt% of photoinitiator.

2. The adhesive according to claim 1, wherein include: 60wt% to 88wt% of the acrylic resin, 8wt% to 28wt% of the active monomer and 2wt% to 8wt% of the photoinitiator.

3. The adhesive according to claim 1 or 2, wherein: The active monomers include acrylic ester monomers.

4. The adhesive according to claim 3, wherein: The acrylic ester monomers include one or more of isobornyl acrylate, trimethylolpropane triacrylate, diethylene glycol diacrylate, dimethylolethane triacrylate, tripropylene glycol diacrylate, 2-ethylethyl acrylate, β-hydroxyethyl methacrylate, dipentaerythritol pentaacrylate, 2-methoxyethyl acrylate, bisphenol α dimethacrylate, 1,6-hexanediol diacrylate and tetrahydrofuran acrylate.

5. The adhesive according to any one of claims 1 to 4, wherein The photoinitiator includes one or more of ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, 2-isopropylthioxanthone, 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone and 2-hydroxy-2-methyl-1-phenylacetone.

6. The adhesive according to claim 5, wherein: The photoinitiator includes at least two of the 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, the 2,4,6-trimethylbenzoyldiphenylphosphine oxide, the 1-hydroxycyclohexylphenyl ketone, the 2-isopropylthioxanthone, the 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone and the 2-hydroxy-2-methyl-1-phenylpropanone.

7. The adhesive according to claim 5 or 6, wherein: The photoinitiator includes the 1-hydroxycyclohexyl phenyl ketone.

8. The adhesive according to any one of claims 1 to 7, wherein Also includes: ≤5wt% coupling agent.

9. The adhesive according to claim 8, wherein: The coupling agent includes one or more of aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane.

10. The adhesive according to claim 9, wherein: Also includes: ≤10wt% pigment.

11. An insulating film, wherein: include: A release layer and at least one connection unit sequentially distributed along the thickness direction of the insulating film, wherein the connection unit comprises a base film layer and an adhesive layer, and the base film layer is located on a side of the adhesive layer away from the release layer; Wherein, the adhesive layer comprises the adhesive as described in any one of claims 1 to 10.

12. The insulating film according to claim 11, wherein The insulating film includes a plurality of the connection units.

13. The insulating film according to claim 11 or 12, wherein The total thickness of the base film layer is T1, and the total thickness of the adhesive layer is T2; Wherein, T2 = T1 × (50% to 150%); Optionally, T2=T1×(80% to 120%).

14. The insulating film according to any one of claims 11 to 13, wherein The thickness of the single adhesive layer is T2'; Among them, T2'≤60μm.

15. The insulating film according to any one of claims 11 to 14, wherein The thickness of the single-layer base film layer is T1'; Among them, 25μm≤T1'≤80μm; Optionally, 40 μm≤T1′≤60 μm.

16. The insulating film according to any one of claims 11 to 15, wherein The total thickness of the base film layer is T1, the total thickness of the adhesive layer is T2, and the thickness of the release layer is T3; Wherein, T3 = (T1 + T2) × (10% to 50%); Optionally, 20 μm ≤ T3 ≤ 50 μm.

17. A battery casing, wherein: The invention comprises a shell body and an insulating protective film, wherein the insulating protective film is formed by the connecting unit according to any one of claims 11 to 16, the insulating protective film comprises a connecting layer and the base film layer, and the connecting layer is formed by light curing the adhesive layer; Wherein, the outer surface of the side wall of the shell body is connected to the connecting layer.

18. A battery cell, wherein: Comprising the battery casing as claimed in claim 17.

19. A battery, wherein: Comprising the battery cell as claimed in claim 18.

20. An electrical device, wherein: Comprising the battery as claimed in claim 18 or the battery as claimed in claim 19.

21. A method for preparing a battery shell, wherein: include: providing a shell body; The insulating film according to any one of claims 11 to 16 is subjected to the step of removing the release layer, so that the connecting unit remains; The shell body is coated with the connecting unit, the shell body is in contact with the outer surface of the side wall of the shell body through the adhesive layer, and the adhesive layer is photocured to form a connecting layer.

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