Lithium ion battery cell, ultraviolet curing cell insulating coating and preparation method and application thereof

Abstract

The embodiment of the invention provides a lithium ion battery cell, an ultraviolet curing cell insulating coating as well as a preparation method and application thereof. The ultraviolet curing cell insulating coating comprises the following raw materials in percentage by mass: 55-75% of acrylic resin; 10%-30% of a reactive diluent; 6%-9% of a photoinitiator; 4%-7% of flame retardant powder; 4%-7% of insulating powder; 0.3%-0.5% of a leveling agent; 0.2%-0.4% of a defoaming agent; 0.5%-1% of an anti-sagging auxiliary agent; 2%-3% of color paste; wherein the acrylic resin is a mixture of two-functionality aliphatic modified polyurethane acrylic resin and nine-functionality aliphatic modified polyurethane acrylic resin in a weight ratio of (3.4-4.0): 1. According to the ultraviolet curing battery cell insulating coating and the preparation method and application thereof provided by the embodiment of the invention, the contradiction that single resin cannot meet the requirements of flexibility and hardness at the same time is solved through functionality mixing, and the comprehensive performance of the coating is improved.

Description

Technical Field

[0001] This application belongs to the technical field of coatings, and particularly relates to a lithium-ion battery cell, an ultraviolet-curable insulating coating for the battery cell, its preparation method and application. Background Technology

[0002] As a core component of new energy vehicles, power batteries have always been a key area of ​​research focus. Lithium-ion battery cells in new energy vehicles have relatively high requirements for electrical insulation, typically requiring a coating with excellent insulating properties to be applied to the outer casing of the lithium-ion battery cell. Currently, the main types of coatings used for insulating and protecting the aluminum casing of lithium-ion battery cells are powder coatings and UV-cured coatings. Powder coatings have the advantage of high coating recovery rates, but their disadvantages include the need for high-temperature baking, resulting in low energy efficiency and rework rate, as the cells can only be installed and electrolyte filled after spraying. On the other hand, UV-cured coatings offer high coating utilization, but their disadvantages include high requirements for coating leveling and flow properties, which can easily lead to problems such as excessively thick or uneven coating thickness. Furthermore, the insulation performance of the aluminum casing requires a certain coating thickness, indirectly increasing the product's coating cost.

[0003] In summary, current coatings used in battery cell casings suffer from low efficiency, poor performance, and uneven coating thickness. Summary of the Invention

[0004] In view of this, the present application provides a lithium-ion battery cell, an ultraviolet-cured insulating coating for the battery cell, a method for preparing the coating, and its application, in order to solve the technical problem of poor overall performance of existing coatings for battery cell casings.

[0005] In a first aspect, embodiments of this application provide a UV-curable battery cell insulating coating, comprising the following raw materials by mass fraction: Acrylic resin 55%~75%; Reactive diluent 10%~30%; Photoinitiator 6%~9%; Flame retardant powder 4%~7%; Insulating powder 4%~7%; Leveling agent 0.3%~0.5%; Defoamer 0.2%~0.4%; Anti-sagging agent 0.5%~1%; Pigment 2%~3%; The acrylic resin is a mixture of aliphatic modified polyurethane acrylic resins, which includes a difunctional aliphatic modified polyurethane acrylic resin and a nonfunctional aliphatic modified polyurethane acrylic resin, wherein the weight ratio of the difunctional aliphatic modified polyurethane acrylic resin to the nonfunctional aliphatic modified polyurethane acrylic resin is (3.4-4.0):1.

[0006] In some embodiments, the weight ratio of the bifunctional aliphatic modified polyurethane acrylate resin to the nonfunctional aliphatic modified polyurethane acrylate resin is 3.5:1.

[0007] In some embodiments, the reactive diluent is one or more selected from monofunctional acrylate monomers, difunctional acrylate monomers, and polyfunctional acrylate monomers.

[0008] In some embodiments, the monofunctional acrylate monomer is selected from one or more of isobornyl acrylate, laurate acrylate, phenoxyethyl acrylate, cyclotrimethylolpropane methyl acetal acrylate, and tetrahydrofuran acrylate.

[0009] In some embodiments, the photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide in a weight ratio of 1:(0.8 to 1.0):0.3.

[0010] In some embodiments, the flame retardant powder is selected from one or more of aluminum hydroxide, magnesium hydroxide, ammonium polyphosphate, aluminum hypophosphite, and zinc borate.

[0011] In some embodiments, the insulating powder is selected from one or more of silicon micropowder, silicon dioxide, aluminum oxide, boron nitride, and barium sulfate.

[0012] In some embodiments, the leveling agent is a structured acrylic copolymer.

[0013] In some embodiments, the anti-sagging agent is fumed silica.

[0014] In some embodiments, the defoamer comprises at least one of hydrophobic silica, wax, acrylic polymer, and vinyl polymer.

[0015] In some embodiments, the viscosity of the UV-curable battery cell insulating coating is 450–550 cps / 25°C.

[0016] Secondly, embodiments of this application provide a lithium-ion battery cell, wherein the outer shell of the lithium-ion battery cell is provided with an insulating layer, and the insulating layer is formed by coating and ultraviolet curing the ultraviolet light-cured insulating coating of the battery cell described in the first aspect.

[0017] Thirdly, according to an embodiment of this application, a method for preparing a UV-curable battery cell insulating coating as described in the first aspect includes the following steps: The bifunctional aliphatic modified polyurethane acrylic resin, the nonfunctional aliphatic modified polyurethane acrylic resin, a portion of the reactive diluent, the flame retardant powder, the insulating powder, and the anti-sagging agent are mixed according to the specified ratio, and then dispersed and ground to obtain a premixed slurry. The remaining reactive diluent, photoinitiator, leveling agent, defoamer, and colorant are added to the premixed slurry and stirred until homogeneous to obtain the UV-curable battery cell insulating coating.

[0018] In some embodiments, a method for preparing a UV-curable battery cell insulating coating as described in the first aspect includes the following steps: The bifunctional aliphatic modified polyurethane acrylic resin, the nonfunctional aliphatic modified polyurethane acrylic resin, the reactive diluent, the flame retardant powder, the insulating powder, the anti-sagging agent, the photoinitiator, the leveling agent, the defoamer, and the color paste are mixed according to the specified ratio to obtain the UV-curable battery cell insulating coating.

[0019] Fourthly, embodiments of this application provide an application of ultraviolet-cured cell insulating coating, including the application of the ultraviolet-cured cell power battery insulating coating described in the first aspect in the insulation protection of cells, busbars, and battery shells of lithium-ion power batteries, battery modules, or battery packs.

[0020] The lithium-ion battery cell, UV-curable battery cell insulating coating, preparation method and application provided in this application embodiment are as follows: the UV-curable battery cell insulating coating uses a specific ratio of functional resins as the core, and around this core, functional fillers and process aids are systematically formulated to achieve organic synergy among the components, ultimately preparing a high-performance and high-reliability UV-curable insulating coating that can fully meet the stringent requirements of lithium-ion battery cells.

[0021] Difunctional aliphatic modified polyurethane acrylic resins have longer molecular chains and lower crosslinking densities, giving the material excellent flexibility and impact resistance. Furthermore, the polar groups (such as urethane bonds) form hydrogen bonds with the substrate, enhancing interfacial adhesion. The low crosslinking structure reduces charge migration paths, making it suitable for electronic packaging or insulating coatings, significantly improving insulation performance. Nonfunctional aliphatic modified polyurethane acrylic resins have high crosslinking densities, forming a rigid three-dimensional network that resists mechanical wear and acid / alkali corrosion, providing high hardness and chemical resistance. The multifunctional groups accelerate free radical polymerization reactions, shortening curing time. When the ratio of the two components is 3.5 to 4:1, the flexibility of the difunctional resin and the rigidity of the nonafunctional resin achieve an optimal balance, avoiding brittleness (pure nonafunctional) or insufficient strength (pure difunctional). This satisfies the requirements for film flexibility, and the film passes the impact resistance test (GB / T 1732-2020, 25℃, 50cm height) and shows no significant change in film performance after acid and alkali resistance (GB / T 9274-1988, drop test - 1 day). The interfacial adhesion of the difunctional resin and the dense network of the nonafunctional resin work synergistically to achieve an adhesion grade of 0 (ISO 2409) to metal / plastic substrates (cross-cut test). Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart illustrating the preparation method of the UV-curable battery cell insulating coating provided in this application embodiment. Figure 1 ; Figure 2 This is a flowchart illustrating the preparation method of the UV-curable battery cell insulating coating provided in this application embodiment. Figure 2 . Detailed Implementation

[0024] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that the embodiments of this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the embodiments of this application with unnecessary detail.

[0025] It should also be understood that the term "and / or" as used in the specification of embodiments of this application and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0026] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0027] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0028] Furthermore, in the description of the embodiments and the appended claims of this application, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0029] In the description of embodiments in this application, references to "some embodiments" or "some embodiments" mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in some embodiments," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiments, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. "A plurality" refers to two or more.

[0030] The first aspect of this application provides a UV-curable battery cell insulating coating, comprising the following raw materials by mass fraction: Acrylic resin 55%~75%; Reactive diluent 10%~30%; Photoinitiator 6%~9%; Flame retardant powder 4%~7%; Insulating powder 4%~7%; Leveling agent 0.3%~0.5%; Defoamer 0.2%~0.4%; Anti-sagging agent 0.5%~1%; Pigment 2%~3%; The acrylic resin is a mixture of aliphatic modified polyurethane acrylic resin, which includes a difunctional aliphatic modified polyurethane acrylic resin and a nonfunctional aliphatic modified polyurethane acrylic resin. The weight ratio of the difunctional aliphatic modified polyurethane acrylic resin to the nonfunctional aliphatic modified polyurethane acrylic resin is (3.4~4.0):1.

[0031] The UV-curable battery cell insulating coating provided in this application uses a specific ratio of functional resins as its core, and around this core, functional fillers and process aids are systematically formulated to create a profound synergistic effect among the components. Ultimately, a high-performance, high-reliability UV-curable insulating coating that can fully meet the stringent requirements of lithium-ion battery cells is successfully prepared.

[0032] In applications, acrylic resin mixtures account for 55% to 75% of the total mass, forming the framework and key to the performance balance of the entire coating system. As a film-forming substance, it serves as the matrix of the coating. Aliphatic modification provides excellent resistance to yellowing and aging, ensuring stable appearance and performance of the battery over long-term use. Polyurethane acrylate combines the excellent abrasion resistance, toughness, and high adhesion of polyurethane with the good curing speed of acrylate. Among them, bifunctional resins provide flexibility, elongation, and adhesion. Low functionality, longer molecular chains, and fewer crosslinking points result in a looser network structure after curing, making the coating flexible and able to adapt to the slight expansion and contraction of the battery cell without cracking. Nonfunctional resins provide high crosslinking density, hardness, chemical resistance, and rapid curing speed. High functionality acts like multiple "handles," forming a dense three-dimensional network structure, giving the coating high hardness, abrasion resistance, and excellent insulation strength. Using high-functionality resins alone results in a coating that is too brittle and prone to cracking; using low-functionality resins alone results in a coating that is too soft and not abrasion-resistant. By mixing the resins in a specific ratio of (3.4 to 4.0):1, an optimal balance between hardness and flexibility is achieved. The bifunctional resin acts as the "soft segment," while the nonafunctional resin acts as the "hard segment." During the curing process, they interweave to form an interpenetrating network structure, resulting in a coating that is both hard and wear-resistant, yet possesses sufficient toughness, low internal stress, and strong adhesion.

[0033] In applications, reactive diluents are used to reduce system viscosity, facilitating application and filler dispersion. They also participate in the curing reaction, becoming part of the cross-linking network; they are non-volatile and environmentally friendly. Reactive diluents effectively reduce the viscosity of high-viscosity resins (especially nine-functional resins), making them easier to process. Their functionality matches that of the resin, working together to build a complete curing network, adjusting the cross-linking density of the final coating, and thus fine-tuning its flexibility. Furthermore, suitable viscosity helps to uniformly disperse solid fillers such as flame-retardant powders and insulating powders, preventing sedimentation and agglomeration.

[0034] In applications, photoinitiators absorb ultraviolet light energy to generate active free radicals, which initiate a polymerization reaction between the double bonds of acrylic resin and diluent, achieving a rapid transformation of the coating from a liquid to a solid state. The type and amount of initiator are matched with the resin system. Its high efficiency ensures that even with high filler content, ultraviolet light can fully initiate deep curing, avoiding the phenomenon of surface drying while the interior remains dry, and guaranteeing consistent overall performance.

[0035] In applications, flame-retardant powders interrupt the combustion chain reaction through mechanisms such as endothermic decomposition, release of flame-retardant gases, and formation of a carbonized layer, thereby achieving flame retardancy and improving battery safety. Insulating powders (such as silicon micropowder and alumina): These are excellent insulators themselves, filling the polymer network and significantly improving the coating's volume resistivity and breakdown voltage strength. Together, they constitute the core safety function of the coating—insulation and flame retardancy. Their addition amounts are carefully designed (8%~14% total) to ensure functionality without excessively disrupting the continuity and mechanical properties of the resin matrix. The resin acts as a "binder," firmly encapsulating these functional powders together to form a dense and robust functional coating. Many flame-retardant powders (such as aluminum hydroxide and alumina) also possess excellent insulation properties, while insulating powders (such as boron nitride) may also have thermally conductive and flame-retardant effects. The two complement each other, jointly enhancing the coating's safety protection level.

[0036] In application, leveling agents (such as structured acrylic copolymers) reduce the surface tension of the coating, making it easier to spread on the substrate and form a smooth, even film, avoiding defects such as orange peel and pinholes. Defoamers inhibit the formation of bubbles during production and coating, and promote the collapse of existing bubbles, preventing pinholes in the coating. Anti-sagging agents (such as fumed silica) impart a certain thixotropic property to the coating by forming a three-dimensional network structure (viscous when standing, thinner when sheared). Low viscosity during application facilitates leveling, and viscosity recovers after application, preventing sagging on vertical surfaces. These three agents work synergistically to ensure excellent applicability of the coating. Anti-sagging agents, in combination with defoamers, prevent sagging while avoiding the trapping of bubbles due to excessive thixotropic structure. Leveling agents ultimately ensure the smoothness of the coating on a macroscopic level. Their combined action results in a defect-free, uniformly thick insulating coating, which is the foundation for consistent insulation performance.

[0037] In application, the colorant is a blue-white paste, matching the color of the battery cell. It provides color for product identification, differentiation, or masking. Some pigments in the colorant may also absorb or reflect ultraviolet light, potentially indirectly affecting the curing depth, requiring coordination with a photoinitiator system. The amount added must be controlled to avoid affecting the electrical and mechanical properties of the coating.

[0038] In applications, the weight ratio of the difunctional aliphatic modified polyurethane acrylate resin to the nonfunctional aliphatic modified polyurethane acrylate resin can be any value within the range of (3.4:1), such as 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, or 4.0:1. In a preferred embodiment, the weight ratio of the difunctional aliphatic modified polyurethane acrylate resin to the nonfunctional aliphatic modified polyurethane acrylate resin is 3.5:1. When the ratio of the two components is 3.5:1, the flexibility of the difunctional resin and the rigidity of the nonfunctional resin achieve the optimal balance, avoiding brittleness or insufficient strength, satisfying the flexibility of the paint film, and passing the impact resistance test of GB / T 1732-2020 at 25℃ and a height of 50cm. After acid and alkali resistance test of GB / T 9274-1988 (drop method - 1 day), the performance of the paint film showed no significant change. The interfacial adhesion of the difunctional resin and the dense network of the nonfunctional resin work synergistically to achieve an adhesion (cross-cut test) of 0 grade (ISO 2409) to metal / plastic substrates.

[0039] In some embodiments, the reactive diluent is one or more selected from monofunctional acrylate monomers, difunctional acrylate monomers, and polyfunctional acrylate monomers. This provides great formulation flexibility, allowing for precise adjustment of the crosslinking network structure of the coating according to the final performance requirements. Monofunctional acrylate monomers primarily reduce viscosity, providing flexibility and adhesion, but reduce crosslinking density. Difunctional acrylate monomers balance dilution effect and crosslinking contribution, and are commonly used diluents. Polyfunctional acrylate monomers significantly increase crosslinking density, increasing coating hardness, chemical resistance, and curing speed, but may increase brittleness. By blending monomers of different functionalities, the hardness, flexibility, reaction rate, etc., of the coating can be fine-tuned without compromising the performance of the core resin system, achieving effective performance improvement.

[0040] In some embodiments, the monofunctional acrylate monomer is selected from one or more of isobornyl acrylate, laurate acrylate, phenoxyethyl acrylate, cyclotrimethylolpropane methyl acetal acrylate, and tetrahydrofuran acrylate. These are not ordinary monofunctional monomers; each possesses a unique molecular structure that imparts unique properties to the coating. Isobornyl acrylate has a rigid alicyclic structure, significantly improving the coating's hardness, heat resistance, and hydrophobicity. Laurate acrylate has long-chain alkyl groups, providing excellent flexibility, internal plasticizing effect, and low shrinkage. Phenoxyethyl acrylate contains benzene rings and ether bonds, exhibiting strong adhesion, low shrinkage, and good compatibility. Cyclotrimethylolpropane methyl acetal acrylate has a cyclic structure, resulting in fast curing speed, low volume shrinkage, and high hardness. Tetrahydrofuran acrylate contains ether bonds, providing good dilution effect, resulting in a flexible cured film with excellent adhesion. This selection goes beyond simple dilution and is an optimization tailored to the requirements of high adhesion, low shrinkage, and heat resistance in battery cell insulating coatings. For example, the use of isoborneol acrylate can enhance heat resistance, while the use of phenoxyethyl acrylate can improve adhesion to metal / plastic battery cell casings.

[0041] In some embodiments, the photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (819) in a weight ratio of 1:(0.8-1.0):0.3. This achieves simultaneous and efficient surface and deep curing. 1173 is a classic pyrolysis initiator with a short absorption wavelength, mainly generating free radicals in the surface region irradiated by ultraviolet light, achieving rapid surface curing. TPO and 819 are acylphosphine oxide initiators with longer absorption wavelengths and better penetration of ultraviolet light, effectively initiating deep curing of the coating. The combination of TPO and 819 covers a wider long-wave ultraviolet absorption range, allowing ultraviolet light to penetrate coatings containing a large amount of solid fillers (flame retardant powder, insulating powder), avoiding poor curing of the underlying layer due to fillers blocking ultraviolet light. 1173 ensures rapid surface drying and prevents oxygen inhibition, while TPO / 819 ensures rapid follow-up at deeper layers. These are all low yellowing index initiators, meeting the appearance requirements of battery cells. This compounding solution effectively solves the technical challenges of UV curing in thick coating and high filler content systems.

[0042] In some embodiments, the flame retardant powder is selected from one or more of aluminum hydroxide, magnesium hydroxide, ammonium polyphosphate, aluminum hypophosphite, and zinc borate. This encompasses flame retardants with different mechanisms of action, achieving synergistic flame retardancy.

[0043] Aluminum hydroxide / magnesium hydroxide is an endothermic decomposition type, which lowers the system temperature through endothermic decomposition and releases water vapor to dilute flammable gases. Ammonium polyphosphate is an expansion-to-char type, which generates phosphoric acid substances under thermal action to promote charring of the substrate and form an expansion insulation layer. Aluminum hypophosphite works on a gas-phase mechanism, capturing free radicals in the gas phase and interrupting the combustion chain reaction with high efficiency. Zinc borate is multifunctional, combining the functions of charring, smoke suppression, and promoting carbon layer formation. By compounding flame retardant powders with different mechanisms, a multi-layered and more efficient fire barrier can be constructed to achieve synergistic flame retardancy and significantly improve the thermal safety performance of the battery.

[0044] In some embodiments, the insulating powder is selected from one or more of silica powder, silica, alumina, boron nitride, and barium sulfate. This provides basic insulation performance while also considering other properties. Silica powder / silica is low in cost, has good insulation properties, and is chemically stable. In addition to excellent insulation, alumina has high thermal conductivity, which helps to evenly dissipate heat generated by the battery cell and avoid localized overheating. Boron nitride is an excellent insulating and thermally conductive filler that can significantly improve the thermal conductivity of the coating. Barium sulfate has a high density, which helps to improve the settling properties of the filler, and it has low oil absorption and minimal impact on viscosity.

[0045] In some embodiments, the leveling agent is a structured acrylic copolymer. Such leveling agents eliminate pinholes by reducing surface tension, while their specific molecular structure is well-compatible with the system yet moderately incompatible, forming a monolayer on the coating surface. This promotes uniform leveling of the coating, resulting in a mirror-like smooth film. A smooth coating has an aesthetically pleasing appearance and, more importantly, ensures uniform coating thickness, thereby guaranteeing consistent insulation performance and preventing insulation weaknesses caused by localized thinning.

[0046] In some embodiments, the anti-sagging agent is fumed silica. Fumed silica nanoparticles impart strong thixotropic properties to the coating by forming a three-dimensional hydrogen bond network in the coating system. That is, the viscosity is high when at rest, preventing filler sedimentation and sagging on vertical surfaces; when subjected to shear forces (such as stirring or coating), the network is disrupted, the viscosity decreases, and application is facilitated.

[0047] In some embodiments, the defoamer comprises at least one of hydrophobic silica, wax, acrylic polymer, and vinyl polymer. These substances have lower surface tension and can effectively disrupt the bubble film walls, promoting bubble coalescence and rupture. In particular, hydrophobic silica particles can serve as nucleation sites for bubble collapse.

[0048] In some embodiments, the viscosity of the UV-cured battery cell insulating coating is 450–550 cps / 25°C. This viscosity range directly reflects the process performance. Too low a viscosity leads to sagging and makes coating thickness difficult to control. Too high a viscosity results in poor leveling, making coating difficult and prone to defects such as orange peel. 450–550 cps / 25°C is an optimized range that ensures excellent workability when used in conjunction with anti-sagging agents (fumed silica) and leveling agents. It is suitable for common coating processes (such as slot coating and spraying) and ensures stable filler suspension without settling. It forms a uniform coating thickness, providing a foundation for consistent insulation performance.

[0049] Secondly, embodiments of this application provide a lithium-ion battery cell, wherein the outer shell of the lithium-ion battery cell is provided with an insulating layer, which is formed by coating and curing the ultraviolet light-cured insulating coating of the battery cell described in the first aspect.

[0050] Thirdly, embodiments of this application provide a method for preparing a UV-curable battery cell insulating coating as described in the first aspect, such as... Figure 1 As shown, it includes the following steps: S10. Mix the bifunctional aliphatic modified polyurethane acrylic resin, the nonfunctional aliphatic modified polyurethane acrylic resin, a portion of reactive diluent, flame retardant powder, insulating powder, and anti-sagging agent according to the formula ratio, and disperse and grind them to obtain a premixed slurry. S20. Add the remaining reactive diluent, photoinitiator, leveling agent, defoamer and color paste to the premixed slurry, stir and mix evenly to obtain UV-curable battery cell insulating coating.

[0051] This ensures thorough dispersion of the filler, improving coating uniformity and performance. Uneven dispersion of solid fillers such as flame retardant powder and insulating powder can lead to agglomeration points in the coating, creating insulation weaknesses and significantly reducing the coating's voltage withstand strength (insulation) and density. Using a portion (not all) of the reactive diluent with the resin and filler initially results in a higher initial viscosity of the slurry. High-speed dispersion and grinding at this high viscosity applies greater shear force to the filler aggregates, effectively breaking them up and achieving uniform dispersion at the nano / micro level. This lays a solid foundation for forming a uniform, defect-free cured coating. It also avoids degradation of sensitive components, ensures storage stability and curing efficiency, and protects sensitive components such as photoinitiators and defoamers. High-speed dispersion and grinding processes generate significant heat and intense mechanical impact. If the photoinitiator is added initially, localized high temperatures may cause partial decomposition or pre-reaction, reducing the final product's curing efficiency and even affecting storage stability. Adding it in the second step under low-speed stirring provides gentler conditions and effectively avoids this problem. Adding the reactive diluent in stages ensures effective grinding and dispersion at high viscosity in stage S10, while the final usable viscosity (450~550 cps) is precisely adjusted by adding the remaining diluent in stage S20. The leveling agent and defoamer are added in the second step to maximize their effectiveness and prevent them from being damaged or failing under prolonged high-speed shearing.

[0052] In some embodiments, such as Figure 2 As shown, the method for preparing the UV-curable battery cell insulating coating as described in the first aspect includes the following steps: S10. Mix the difunctional aliphatic modified polyurethane acrylic resin, the nonafunctional aliphatic modified polyurethane acrylic resin, the reactive diluent, flame retardant powder, insulating powder, anti-sagging agent, photoinitiator, leveling agent, defoamer, and colorant according to the specified ratio to obtain the UV-curable battery cell insulating coating. The simplified process and significantly improved production efficiency are the most prominent advantages of this method. All raw materials are added at once and mixed evenly, greatly shortening production time and reducing equipment usage and operational steps. It eliminates complex steps such as grinding, transferring, and step-by-step feeding, making it ideal for continuous, large-scale production.

[0053] Fourthly, embodiments of this application provide an application of ultraviolet-cured cell insulating coating, including the application of the ultraviolet-cured cell power battery insulating coating described in the first aspect in the insulation protection of cells, busbars, and battery shells of lithium-ion power batteries, battery modules, or battery packs.

[0054] The raw materials used in the following examples are: The acrylic resin is a mixture of modified difunctional aliphatic polyurethane acrylic (Zhancheng New Materials aliphatic polyurethane S2082) and modified nonfunctional aliphatic polyurethane acrylic (Zhancheng New Materials aliphatic polyurethane S2083) resins; the photoinitiator is a mixture of photoinitiator 1173, photoinitiator TPO and photoinitiator XBPO; the flame retardant powder is Sutebao P3001S; the insulating powder is Xuanzhu Technology PSI-531; the leveling agent is EFKA FL 3750; the reactive diluent is a mixture of cyclotrimethylolpropane methyl acetal acrylate (CTFA) and tetrahydrofuran acrylate; the anti-sagging additive is Degussa AEROSIL R972 hydrophobic fumed silica; the defoamer is TEGO923; and the color paste is blue and white paste.

[0055] Example 1 The UV-curable battery cell insulating coating is prepared by mixing difunctional aliphatic modified polyurethane acrylic resin, nonfunctional aliphatic modified polyurethane acrylic resin, reactive diluent, flame retardant powder, insulating powder, anti-sagging agent, photoinitiator, leveling agent, defoamer, and color paste according to the specified ratio. The mixture comprises a difunctional aliphatic modified polyurethane acrylic resin and a nonfunctional aliphatic modified polyurethane acrylic resin in a weight ratio of 3.4:1; a photoinitiator composition of photoinitiator 1173: photoinitiator TPO: photoinitiator XBPO = 1:0.8:0.3; a reactive diluent composition of CTFA: tetrahydrofuran acrylate = 1:1; 4% flame retardant powder; 4% insulating powder; and 2.5% color paste.

[0056] Example 2 The process is basically the same as in Example 1, except that the acrylic resin is a mixture of modified difunctional aliphatic polyurethane acrylic resin and modified nonfunctional aliphatic polyurethane acrylic resin in a weight ratio of 3.5:1; the photoinitiator consists of photoinitiator 1173: photoinitiator TPO: photoinitiator XBPO = 1:0.875:0.3; the reactive diluent consists of CTFA: tetrahydrofuran acrylate = 1:1; flame retardant powder 5%; and insulating powder 5%.

[0057] Example 3 The process is basically the same as in Example 1, except that the acrylic resin is a mixture of modified difunctional aliphatic polyurethane acrylic resin and modified nonfunctional aliphatic polyurethane acrylic resin in a weight ratio of 3.5:1; the photoinitiator consists of photoinitiator 1173: photoinitiator TPO: photoinitiator XBPO = 1:1:0.3; the reactive diluent consists of CTFA: tetrahydrofuran acrylate = 1:1; flame retardant powder 5%; insulating powder 5%; and color paste 2.5%.

[0058] Example 4 The process is basically the same as in Example 1, except that the acrylic resin is a mixture of modified difunctional aliphatic polyurethane acrylic resin and modified nonfunctional aliphatic polyurethane acrylic resin in a weight ratio of 3.8:1; the photoinitiator consists of photoinitiator 1173: photoinitiator TPO: photoinitiator XBPO = 1:0.8:0.3; the reactive diluent consists of CTFA: tetrahydrofuran acrylate = 1:1; flame retardant powder 5%; and insulating powder 6%.

[0059] Example 5 The process is basically the same as in Example 1, except that the acrylic resin is a mixture of modified difunctional aliphatic polyurethane acrylic resin and modified nonfunctional aliphatic polyurethane acrylic resin in a weight ratio of 4.0:1; the photoinitiator consists of photoinitiator 1173: photoinitiator TPO: photoinitiator XBPO = 1:1:0.3; the reactive diluent consists of CTFA: tetrahydrofuran acrylate = 1:1; flame retardant powder 6%; and insulating powder 8%.

[0060] The raw material mass fractions of the UV-curable battery insulating coating provided in Examples 1-5 are shown in Table 1.

[0061] Table 1. Proportion of each raw material component in Examples 1-5

[0062] Comparative Example 1 The process is basically the same as in Example 1, except that the acrylic resin is a mixture of modified difunctional aliphatic polyurethane acrylic resin and modified nonfunctional aliphatic polyurethane acrylic resin in a weight ratio of 3:1; the photoinitiator consists of photoinitiator 1173: photoinitiator TPO: photoinitiator XBPO = 1:0.8:0.3; the reactive diluent consists of CTFA: tetrahydrofuran acrylate = 1:1; flame retardant powder 4%; and insulating powder 4%.

[0063] Comparative Example 2 The process is basically the same as in Example 1, except that the acrylic resin is a mixture of modified difunctional aliphatic polyurethane acrylic resin and modified nonfunctional aliphatic polyurethane acrylic resin in a weight ratio of 3.5:1; the photoinitiator consists of photoinitiator 1173: photoinitiator TPO: photoinitiator XBPO = 1:0.8:0.3; the reactive diluent consists of CTFA: tetrahydrofuran acrylate = 1:1; flame retardant powder 1%; and insulating powder 2%.

[0064] Comparative Example 3 The process is basically the same as in Example 1, except that the acrylic resin is a mixture of modified difunctional aliphatic polyurethane acrylic resin and modified nonfunctional aliphatic polyurethane acrylic resin in a weight ratio of 3.5:1; the photoinitiator consists of photoinitiator 1173: photoinitiator TPO: photoinitiator XBPO = 1:0.8:0.3; the reactive diluent consists of CTFA: tetrahydrofuran acrylate = 1:1; flame retardant powder 8%; and insulating powder 12%.

[0065] Comparative Example 4 The process is basically the same as in Example 1, except that the acrylic resin is a mixture of modified difunctional aliphatic polyurethane acrylic resin and modified nonfunctional aliphatic polyurethane acrylic resin in a weight ratio of 4.5:1; the photoinitiator consists of photoinitiator 1173: photoinitiator TPO: photoinitiator XBPO = 1:0.8:0.3; the reactive diluent consists of CTFA: tetrahydrofuran acrylate = 1:1; flame retardant powder 5%; and insulating powder 5%.

[0066] The raw material mass fractions of the UV-curable battery insulating coatings provided in Comparative Examples 1-4 are shown in Table 2.

[0067] Table 2. Proportion of each raw material component in Comparative Examples 1-4

[0068] The UV-curable insulating coatings for power batteries obtained in Examples 1-5 and Comparative Examples 1-4 were sprayed according to the process listed in Table 3. The resulting coating films were tested using standard testing methods. The coatings provided in Examples 1-5 showed that the shear adhesion could reach ≥10MPa, the insulation resistance was >10GΩ, the withstand voltage was greater than DC 6100V, the impact resistance was ≥5J, the flexibility met the requirement of bending a 32mm radius shaft rod 180°, and it was resistant to water, acid, and alkali. The test results are listed in Tables 4 and 5.

[0069] Table 3 Construction techniques of Examples 1-5 and Comparative Examples 1-4

[0070] Table 4-1 Detection data from Examples 1-5

[0071] Table 4-2 Detection data from Examples 1-5

[0072] Table 5-1 Detection data of Comparative Examples 1–4

[0073] Table 5-2 Detection data of Comparative Examples 1-4

[0074] As can be seen from Tables 4-1 and 4-2, Examples 1 to 5 can all meet the standard requirements for basic performance. The coating film obtained by reasonably combining acrylic resin, photoinitiator, flame retardant powder, insulating powder and other components according to the claims is tested by standard test methods. The shear adhesion can reach ≥10MPa, the insulation resistance is >10GΩ, the withstand voltage is greater than DC 6100V, the impact resistance is ≥5J, the flexibility meets the requirement of bending a 32mm radius shaft rod 180°, and the water resistance, acid resistance and alkali resistance all meet the requirements.

[0075] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0076] The above-described embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them. Although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of the embodiments of this application.

Claims

1. An ultraviolet light-cured cell insulation coating, characterized by, The raw materials include the following mass fractions: acrylic resin 55%~75%; active diluent 10%~30%; photoinitiator 6%~9%; flame-retardant powder 4%~7%; insulating powder 4%~7%; leveling agent 0.3%~0.5%; defoaming agent 0.2%~0.4%; anti-sagging aid 0.5%~1%; color paste 2%~3%; The acrylic resin is a mixture of aliphatic modified polyurethane acrylic resins, which includes a two-functionality aliphatic modified polyurethane acrylic resin and a nine-functionality aliphatic modified polyurethane acrylic resin, and the weight ratio of the two-functionality aliphatic modified polyurethane acrylic resin to the nine-functionality aliphatic modified polyurethane acrylic resin is (3.4~4.0):

1.

2. The ultraviolet light-cured cell insulation coating of claim 1, wherein, The weight ratio of the two-functionality aliphatic modified polyurethane acrylic resin to the nine-functionality aliphatic modified polyurethane acrylic resin is 3.5:

1.

3. The ultraviolet light-cured cell insulation coating of claim 1, wherein, The active diluent is one or more selected from monofunctional acrylate monomers, bifunctional acrylate monomers, and multifunctional acrylate monomers.

4. The ultraviolet light-cured cell insulation coating of claim 4, wherein, The monofunctional acrylate monomer is one or more selected from isobornyl acrylate, lauryl acrylate, phenoxyethyl acrylate, cyclotrimethylolpropane formal acrylate, and tetrahydrofurfuryl acrylate.

5. The ultraviolet light-cured cell insulation coating of claim 1, wherein, The photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, and phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide, and the weight ratio is 1:(0.8~1.0):0.

3.

6. The ultraviolet light-cured cell insulation coating of claim 1, wherein, The flame-retardant powder is one or more selected from aluminum hydroxide, magnesium hydroxide, ammonium polyphosphate, aluminum hypophosphite, and zinc borate; and / or, The insulating powder is one or more selected from silicon powder, silicon dioxide, aluminum oxide, boron nitride, and barium sulfate; and / or, The leveling agent is a structured acrylic copolymer; and / or, The anti-sagging aid is fumed silica; and / or, The defoaming agent contains at least one of hydrophobic silica, wax, acrylic polymer, and vinyl polymer.

7. The ultraviolet light-cured cell insulation coating of claim 1, wherein, The viscosity of the ultraviolet light curing cell insulation paint is 450~550 cps / 25°C.

8. A lithium-ion battery cell, characterized in that, The shell of the lithium ion battery cell is provided with an insulation layer formed by coating and ultraviolet light curing of the ultraviolet light curing cell insulation paint according to any one of claims 1 to 7.

9. A method of making the ultraviolet light curable cell insulation coating of any one of claims 1 to 7, characterized by, The method includes the following steps: The two-functionality aliphatic modified polyurethane acrylic resin, the nine-functionality aliphatic modified polyurethane acrylic resin, part of the active diluent, the flame-retardant powder, the insulating powder, and the anti-sagging aid are mixed, dispersed, and ground according to the proportions to obtain a premixed paste; The remaining active diluent, the photoinitiator, the leveling agent, the defoaming agent, and the color paste are added to the premixed paste, and stirred and mixed uniformly to obtain the ultraviolet light curing cell insulation paint. Or, The two-functionality aliphatic modified polyurethane acrylic resin, the nine-functionality aliphatic modified polyurethane acrylic resin, the active diluent, the flame-retardant powder, the insulating powder, the anti-sagging aid, and the photoinitiator, the leveling agent, the defoaming agent and the color paste are mixed in proportion to obtain the ultraviolet curing battery cell insulation coating.

10. Use of an ultraviolet light-cured cell insulation coating, characterized in that, The application of the ultraviolet curing battery cell insulation coating in the insulation protection of the lithium ion power battery, the battery cell, the busbar and the battery shell of the battery module or the battery pack.

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