Curable adhesive for battery

Abstract

A curable adhesive for batteries according to the present invention comprises a first agent that contains a silanol condensation catalyst and a thermally conductive filler and is filled in a first container, and a second agent that contains an organic polymer having a hydrolyzable silyl group and a thermally conductive filler and is filled in a second container, the curable adhesive composition for batteries, which is obtained by mixing the first agent and the second agent, is cured after two weeks in an environment of 25 DEG C and 50% RH, the shear adhesive strength of the obtained cured product is 0.5-2.5 MPa, the elongation at maximum stress at a thickness of 2 mm of the cured product is 0.3 mm or more, and the thermal conductivity of the cured product is 1.5 W / m.K or more. According to the present invention, it is possible to provide a curable adhesive for a battery, which has an appropriate adhesive strength, high thermal conductivity, and excellent followability to expansion and contraction of a single battery.

Description

Technical Field

[0001] This invention relates to curable adhesives for batteries. Background Technology

[0002] Among thermally conductive compositions containing thermally conductive filler materials, curable and liquid thermally conductive compositions are well known, for example, filling between a heat-generating body and a heat-dissipating body, and then curing to form a solidified product, and used as a thermally conductive component such as a heat-dissipating gap filler that transfers heat released by the heat-generating body to the heat-dissipating body.

[0003] In recent years, against the backdrop of a steady increase in the production of electric vehicles (EVs), the demand for two-liquid room-temperature curing heat dissipation gap fillers for lithium-ion batteries (LiB) has been continuously increasing. In lithium-ion batteries, from a heat dissipation perspective, heat dissipation gap fillers are frequently used between various components such as battery cells, battery modules, and battery packs to fix the components and improve heat dissipation.

[0004] For example, Patent Document 1 discloses an invention relating to a thermally conductive curable composition as a high thermal conductivity thermal interface material, the thermally conductive curable composition having a first part comprising a catalyst, a mixture of ceramic fillers, a low-volatility organic liquid and water, and a second part comprising a silyl-modified reactive polymer, a low-volatility organic liquid and a mixture of ceramic fillers.

[0005] In addition, Patent Document 2 discloses a moisture-curing composition having high thermal conductivity and suitable as a gap filler, sealant or adhesive for batteries, etc., which contains in specific amounts an organic polymer with reactive silane, a specific filler, a dispersing additive, a curing catalyst and a plasticizer.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Publication No. 2022-521790

[0009] Patent Document 2: Japanese Patent Publication No. 2022-520317 Summary of the Invention

[0010] Inventions aim to solve problems.

[0011] To ensure the increasing prevalence of electric vehicles (EVs) in society, improvements in EV performance are required, including longer driving ranges and shorter charging times. On the other hand, to achieve sustainable EV development while protecting the environment, waste reduction during EV manufacturing and the recycling of used batteries are crucial, necessitating the design of battery structures that are easily reprocessable and recyclable.

[0012] To improve driving range, the battery module's casing is removed, thereby increasing battery loading efficiency, energy density, and weight reduction. However, this design approach eliminates the casing, making it difficult to mechanically secure individual cells. Therefore, a thermally conductive resin composition is needed to fix the cells to a cooling plate or similar surface, requiring improved adhesive strength from the resin composition.

[0013] On the other hand, when defective battery components are discovered during inspection after assembly in the manufacturing process of electric vehicles (EVs), or when single batteries and cooling plates are recycled from electric vehicles (EVs) that have been used up from the market, it is required that they be easily peeled off from the thermally conductive resin composition filled between the battery cells and the cooling plates.

[0014] As a thermally conductive resin composition for LiB, urethane-based resin compositions are usually used. However, urethane-based resin compositions have excessively high adhesive strength, so if peeling is desired, the following problems exist: components such as cooling plates are not strong enough and deform, and the peeled components cannot be recycled.

[0015] The issues related to shortening charging time for thermally conductive resin compositions are also evident. During rapid charging in a short time, the temperature of a single cell rises more easily than before, thus requiring improvements in two qualities of the thermally conductive resin composition. One is improved thermal conductivity to enhance the cooling efficiency of the single cell, and the other is improved conformability to the expansion and contraction of the single cell. If conformability is poor, the thermally conductive composition is prone to peeling off from the single cell, resulting in poor heat dissipation. These two countermeasures are contradictory. That is, to improve thermal conductivity, the filling rate of the thermally conductive filler material needs to be increased, but this leads to difficulty in deformation and reduced conformability.

[0016] From the perspective of achieving a balance between high thermal conductivity in the cured material and its ability to follow the expansion and contraction of the single cell, conventional thermally conductive compositions for batteries still have room for improvement.

[0017] Therefore, the objective of this invention is to provide a curable adhesive for batteries, wherein the cured product can achieve "moderate adhesive force" and, while having high thermal conductivity, also has the ability to follow the expansion and contraction of a single cell. The "moderate adhesive force" refers to the ability to fix the components forming the battery structure with appropriate adhesive force, thereby maintaining a certain strength, while also having easy peelability.

[0018] Problem-solving methods

[0019] Through in-depth research, the inventors discovered that a curable adhesive for batteries with shear bond strength, elongation at maximum stress, and thermal conductivity within a specific range can solve the aforementioned problems. This curable adhesive is composed of a first agent containing a silanol condensation catalyst and a thermally conductive filler, and a second agent containing an organic polymer with hydrolyzable silane and a thermally conductive filler, thus completing the present invention.

[0020] The present invention provides the following solutions [1] to

[15] .

[0021] [1]. A curable adhesive for batteries, comprising a first agent and a second agent,

[0022] The first agent contains a silanol condensation catalyst and a thermally conductive filler material, and is filled in a first container.

[0023] The second agent contains an organic polymer with hydrolyzable silane and a thermally conductive filler material, and is filled in a second container.

[0024] The battery-grade curable adhesive composition, formed by mixing the first and second agents, was cured for two weeks at 25°C and 50% RH. The resulting cured product exhibited a shear bond strength of 0.5–2.5 MPa in a tensile shear test.

[0025] The maximum stress elongation of the cured material with a thickness of 2 mm in the tensile shear test is 0.3 mm or more.

[0026] The thermal conductivity of the cured material is above 1.5 W / m·K.

[0027] [2]. The battery curable adhesive as described in [1] above, wherein the content of the thermally conductive filler in the battery curable adhesive composition is 60-85% by volume.

[0028] The thermally conductive filler material contains a thermally conductive filler material with hydroxyl groups on its surface.

[0029] [3]. The battery curable adhesive as described in [1] or [2] above, wherein the content of the thermally conductive filler material in the battery curable adhesive composition is 60-85% by volume, and the thermally conductive filler material contains a metal hydroxide.

[0030] The total surface area of ​​the metal hydroxides is 200–1500 m² relative to 100 g of the hydrolyzable silyl organic polymer in the battery curing adhesive composition. 2 .

[0031] [4]. The battery curing adhesive as described in any of [1] to [3] above, wherein the first agent further contains an organic polymer having a hydrolyzable silane group.

[0032] [5]. The battery curing adhesive as described in any of [1] to [4] above, wherein the second agent further contains water.

[0033] [6]. The battery curing adhesive as described in any of [3] to [5] above, wherein the content of metal hydroxide in the battery curing adhesive composition is 10 to 80 by volume.

[0034] [7]. The battery curing adhesive as described in any of [3] to [6] above, wherein the metal hydroxide is aluminum hydroxide.

[0035] [8]. The battery curable adhesive as described in any of [3] to [7] above, wherein the metal hydroxide is untreated aluminum hydroxide.

[0036] [9]. The battery curable adhesive as described in any of [1] to [8] above, wherein the thermally conductive filler contains small-particle aluminum hydroxide with an average particle size of less than 20 μm.

[0037]

[10] . The battery curable adhesive as described in any of [1] to [9] above, wherein the organic polymer having hydrolyzable silane is a polyoxyethylene having hydrolyzable silane.

[0038]

[11] . The battery curable adhesive as described in any of [1] to

[10] above, wherein the organic polymer having hydrolyzable silanes has hydrolyzable silanes at the ends of the linear main chain.

[0039]

[12] . The battery curable adhesive as described in any of [1] to

[11] above, wherein the number average molecular weight (Mn) of the organic polymer having hydrolyzable silane is 1,000 to 40,000.

[0040]

[13] . The battery curing adhesive as described in any of [1] to

[12] above, wherein at least one of the first agent and the second agent further contains a plasticizer.

[0041]

[14] . The battery curing adhesive described in any of [1] to

[13] above, wherein the viscosity η1 of the first agent at 25°C and a shear rate of 1 / sec is 100 to 1000 Pa·s, and the viscosity η2 of the second agent at 25°C and a shear rate of 1 / sec is 100 to 1000 Pa·s, and the absolute value of the difference between the viscosity η1 and the viscosity η2 is less than 400 Pa·s.

[0042]

[15] . A battery structure having a structure and a plurality of battery cells disposed in said structure,

[0043] An adhesive layer is disposed between the structure and the battery cell, and between at least one of the plurality of battery cells.

[0044] The adhesive layer is a cured product of a battery-grade curable adhesive composition containing an organic polymer with hydrolyzable silane and a thermally conductive filler material. The cured product has a shear bond strength of 0.5 to 2.5 MPa in a tensile shear test, an elongation at maximum stress of 0.3 mm or more in a tensile shear test with a thickness of 2 mm, and a thermal conductivity of 1.5 W / m·K or more.

[0045]

[16] The use of the battery curable adhesive as described in any one of [1] to

[13] above as a gap material among the gap materials between individual cells, between an individual cell and a module frame, between a battery module and a battery pack frame, and between an individual cell and a battery pack frame.

[0046] Invention Effects

[0047] According to the present invention, a curable adhesive for batteries is provided, which has "moderate adhesive force" to fix the components forming the battery structure with appropriate adhesive force, thereby maintaining a certain strength, while having easy peelability and high thermal conductivity, thus providing excellent tracking of the expansion and contraction of the single cell. Attached Figure Description

[0048] Figure 1 This is a schematic diagram illustrating a container suite according to one embodiment.

[0049] Figure 2 This is a schematic diagram illustrating a container suite according to one embodiment.

[0050] Figure 3This is a cross-sectional view schematically illustrating one embodiment of the battery structure.

[0051] Figure 4 It is a three-dimensional diagram representing the typical structure of a single cell.

[0052] Figure 5 This is a cross-sectional view schematically illustrating another embodiment of the battery structure.

[0053] Figure 6 This is a cross-sectional view schematically illustrating another embodiment of the battery structure.

[0054] Figure 7 This is a cross-sectional view schematically illustrating another embodiment of the battery structure. Detailed Implementation

[0055] [Battery-grade curing adhesive]

[0056] The battery curable adhesive of the present invention comprises a first agent containing a silanol condensation catalyst and a thermally conductive filler material and being filled in a first container, and a second agent containing an organic polymer having a hydrolyzable silane group and a thermally conductive filler material and being filled in a second container.

[0057] Furthermore, the shear bond strength of the cured product cured by mixing the first agent and the second agent for batteries for 2 weeks at 25°C and 50%RH is 0.5 to 2.5 MPa in a tensile shear test, the maximum stress elongation in a tensile shear test of the cured product with a thickness of 2 mm is 0.3 mm or more, and the thermal conductivity of the cured product is 1.5 W / m·K or more.

[0058] The battery-grade curable adhesive of the present invention is stored separately as a first agent filled in a first container and a second agent filled in a second container. By storing the first and second agents separately, the polymerization and curing of the organic polymer containing hydrolyzable silanes can be inhibited during storage, thereby improving storage stability. In use, the first and second agents are mixed to form a battery-grade curable adhesive composition containing an organic polymer containing hydrolyzable silanes, a thermally conductive filler, and a silanol condensation catalyst. This composition is then cured and used as a cured product.

[0059] <Shear bond strength>

[0060] The battery-grade curable adhesive of the present invention, wherein the battery-grade curable adhesive composition formed by mixing the first agent and the second agent, after curing at 25°C and 50%RH for 2 weeks, produces a cured product with a shear bond strength of 0.5 to 2.5 MPa. Here, RH represents relative humidity.

[0061] If the shear bond strength is less than 0.5 MPa, the cured product formed by the battery-grade curing adhesive will be difficult to fix the components forming the battery structure with appropriate adhesive force. On the other hand, if the shear bond strength exceeds 2.5 MPa, the peelability of the cured product formed by the battery-grade curing adhesive from various components will decrease, making recycling and other processes difficult.

[0062] The shear bond strength of the cured material is preferably 0.6 to 1.8 MPa, more preferably 0.8 to 1.4 MPa.

[0063] In this invention, the shear bond strength can be adjusted to a desired range by the type of organic polymer with hydrolyzable silane, the type and amount of thermally conductive filler material used, etc. To achieve high thermal conductivity, even with a high filler content, as described later, a certain shear bond strength can be easily ensured by using a thermally conductive filler material with hydroxyl groups on its surface.

[0064] The aforementioned shear bond strength was determined through a tensile shear test. Specifically, it was measured on a 2mm thick cured material (test piece) formed by applying a battery-grade curable adhesive composition between two substrates and curing it for two weeks at 23°C and 50% RH. That is, it is the maximum stress measured on the stress curve obtained by applying a load (shear stress) intended to offset the substrates in opposite directions until the cured material, serving as the bond joint, fractures.

[0065] The substrate is made of cold-rolled steel sheet (SPCC) coated with cationic electrodeposition. Details of the method for determining shear bond strength are as described in the examples.

[0066] <Elongation at maximum stress>

[0067] The battery curable adhesive of the present invention, when cured by curing the battery curable adhesive composition made by mixing the first agent and the second agent for 2 weeks at 25°C and 50%RH, has an elongation of 0.3 mm or more at maximum stress in a tensile shear test.

[0068] When the maximum stress elongation of the cured material is less than 0.3 mm, its ability to follow the expansion and contraction of the single cell deteriorates. As a result, the cured material is prone to peeling off from the single cell, heat dissipation is reduced, and fast charging becomes difficult.

[0069] From the viewpoint of improving conformability, the maximum stress elongation of the cured material is preferably 0.4 mm or more, more preferably 0.5 mm or more. There is no particular limitation on the upper limit of the maximum stress elongation of the cured material, for example, it is 3 mm.

[0070] In this invention, the elongation at maximum stress can be adjusted to a desired range by the type of organic polymer with hydrolyzable silane, the type and amount of thermally conductive filler material used, etc. As described below, the elongation at maximum stress can be easily adjusted to a desired range by adjusting the sum of the surface areas of the metal hydroxide relative to 100g of the organic polymer with hydrolyzable silane to a specified range.

[0071] The elongation at maximum stress is determined by performing the same test (shear tensile strength test) on a 2 mm thick cured material using the same method described in the shear bond strength section above. The displacement at which the tensile stress reaches its maximum value is taken as the elongation at maximum stress. Furthermore, displacement refers to the amount of deformation (length: mm) along the length of the specimen from the start of the measurement until the tensile stress reaches its maximum value.

[0072] Thermal conductivity

[0073] The battery-grade curable adhesive of the present invention, comprising a battery-grade curable adhesive composition formed by mixing a first agent and a second agent, is cured at 25°C and 50% RH for two weeks, resulting in a cured product with a thermal conductivity of 1.5 W / m·K or higher. If the thermal conductivity is less than 1.5 W / m·K, it becomes difficult to dissipate heat generated by a single cell, making fast charging and other processes difficult.

[0074] The thermal conductivity mentioned above is preferably 2 W / m·K or higher, more preferably 2.5 W / m·K or higher. The higher the thermal conductivity, the better, but in practical applications, the upper limit is, for example, 5 W / m·K or lower.

[0075] In addition, by taking into account both the elongation at maximum stress and thermal conductivity mentioned above, the heat dissipation during fast charging is improved, making it a suitable curing adhesive for batteries that can be used for fast charging.

[0076] In addition, the thermal conductivity was measured according to ASTM D5470.

[0077] <Organic polymers containing hydrolyzable silanes>

[0078] The second agent of the battery-use curable adhesive of the present invention, and the battery-use curable adhesive composition formed by mixing the first agent and the second agent, contain an organic polymer having hydrolyzable silanes. Furthermore, it is preferable that the first agent also contains an organic polymer having hydrolyzable silanes. By including the first agent in an organic polymer having hydrolyzable silanes, the compositions of the first agent and the second agent are similar, thus reducing the viscosity difference between them, making it easier to achieve a uniform composition during mixing, and improving workability.

[0079] The hydrolyzable silane groups in organic polymers undergo hydrolysis by moisture or other substances to form silanol groups. These silanol groups then polycondense with each other or with the hydrolyzable silane groups to form siloxane bonds. Through this process, the organic polymer forms a cross-linked structure and cures, resulting in a rubber-like elastomer. Furthermore, a silanol group refers to a hydroxyl group (Si-OH) directly bonded to a silicon atom.

[0080] Hydrolyzable silyl groups refer to groups formed by bonding 1 to 3 hydrolyzable groups to a silicon atom. The hydrolyzable groups used in hydrolyzable silyl groups are not particularly limited and can include, for example, hydrogen atoms, halogen atoms, alkoxy groups, acyloxy groups, ketoxime ester groups, amino groups, amide groups, acid amide groups, aminooxy groups, mercapto groups, and alkenyloxy groups.

[0081] Among these, alkoxysilanes are preferred as hydrolyzable silanes due to their mild hydrolysis reaction. Examples of alkoxysilanes include trialkoxysilanes such as trimethoxysilane, triethoxysilane, triisopropoxysilane, and triphenoxysilane; dialkoxysilanes such as dimethoxymethylsilane and diethoxymethylsilane; and monoalkoxysilanes such as methoxydimethylsilane and ethoxydimethylsilane. Dialkoxysilanes are more preferred, and dimethoxymethylsilane is particularly preferred.

[0082] The main chain of the organic polymer containing hydrolyzable silanes can be linear or branched, but is preferably linear. That is, the organic polymer containing hydrolyzable silanes of the present invention preferably has hydrolyzable silanes at the ends of the linear main chain.

[0083] When using organic polymers with hydrolyzable silyl groups at the ends, the cured product tends to elongate and has improved conformability.

[0084] The terminal silylation rate of the organic polymer containing hydrolyzable silanes is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. When the terminal silylation rate is certain or higher, the curability and ductility of the battery-grade curable adhesive can be easily adjusted appropriately. Furthermore, the terminal silylation rate refers to the ratio of silylated ends to all ends of the organic polymer containing hydrolyzable silanes.

[0085] In addition, there is no particular upper limit on the terminal silylation rate, such as below 100%, and in practice it can be below 99%.

[0086] Furthermore, the terminal silylation rate of organic polymers containing hydrolyzable silyl groups is determined by... 1 Calculated by H-NMR.

[0087] The average number of hydrolyzable silane alkyl groups per molecule of an organic polymer containing hydrolyzable silane alkyl groups is preferably 1 to 3. If the number of hydrolyzable silane alkyl groups in the polymer is within this range, the curing properties and ductility of the battery-use curable adhesive are good.

[0088] Furthermore, as a method for determining the average number of hydrolyzable silanes in a molecule of an organic polymer containing hydrolyzable silanes, it can be based on... 1 The concentration of hydrolyzable silanes in the organic polymer determined by H-NMR and the number-average molecular weight of the polymer determined by GPC are used for calculation.

[0089] There are no particular limitations on the methods for introducing hydrolyzable silanes into organic polymers. Examples include (1) hydrosilylation by reacting a hydrolyzable silane with an organic polymer whose molecule is modified with an unsaturated group; (2) reaction of a compound with a mercapto group and a hydrolyzable silane with an organic polymer whose molecule is modified with an unsaturated group; and (3) reaction of an organic polymer with a functional group with a compound that has a functional group and a hydrolyzable silane that is reactive to that functional group. Specifically, reactions of isocyanate groups with hydroxyl groups, reactions of isocyanate groups with amino groups, and reactions of isocyanate groups with mercapto groups can be used.

[0090] Organic polymers containing hydrolyzable silyl groups are not particularly limited, and examples include, for instance, polyoxyethylene, polyoxypropylene, polyoxybutene, polytetramethylene oxide, polyoxyethylene-polyoxypropylene copolymers, polyoxypropylene-polyoxybutene copolymers, polyoxyethylene, saturated hydrocarbon polymers, polyurethanes, polychloroprene, polyisoprene, copolymers of isoprene or butadiene with acrylonitrile and / or styrene, copolymers of polybutadiene, isoprene or butadiene with acrylonitrile and styrene, (meth)acrylate polymers obtained by free radical polymerization of monomers such as ethyl (meth)acrylate and butyl (meth)acrylate, and polymers obtained by free radical polymerization of monomers such as vinyl acetate, acrylonitrile, and styrene. Vinyl polymers obtained by free radical polymerization, graft polymers obtained by polymerizing vinyl monomers in the above polymers, polysulfide polymers, nylon 6 obtained by ring-opening polymerization of ε-caprolactam, nylon 6,6 obtained by condensation polymerization of 1,6-hexanediamine and adipic acid, nylon 6,10 obtained by condensation polymerization of 1,6-hexanediamine and sebacic acid, nylon 11 obtained by condensation polymerization of ε-aminoundecanoic acid, nylon 12 obtained by ring-opening polymerization of ε-aminododecanoic acid, copolyamide polymers having two or more of the above nylon components, polycarbonate polymers manufactured by condensation polymerization of bisphenol A and carbonyl chloride, diallyl phthalate polymers, etc. It should be noted that in this specification, (meth)acrylate refers to methacrylate or acrylate.

[0091] Among these, as organic polymers, polyoxyethylene is preferred from the viewpoint of ensuring that the cured shear bond strength and elongation at maximum stress are within the desired range. That is, as an organic polymer having hydrolyzable silane, polyoxyethylene with hydrolyzable silane is preferred. Among polyoxyethylene, polypropylene is particularly preferred.

[0092] The number-average molecular weight (Mn) of the organic polymer containing hydrolyzable silane is preferably 1,000 to 70,000, more preferably 1,000 to 40,000, even more preferably 1,500 to 30,000, even more preferably 2,000 to 30,000, even more preferably 4,000 to 30,000, and even more preferably 4,000 to 20,000. If the number-average molecular weight of the organic polymer containing hydrolyzable silane is below these upper limits, the viscosity of the resulting adhesive composition is lower, and the coatability of the battery-grade curable adhesive composition is improved. Furthermore, if the number-average molecular weight of the organic polymer containing hydrolyzable silane is above these lower limits, the brittleness of the cured battery-grade curable adhesive can be suppressed, and the hardness and ductility of the cured product are improved. Additionally, the above-mentioned number-average molecular weight (Mn) refers to the total number-average molecular weight (Mn) of the adhesive composition containing organic polymers with multiple hydrolyzable silanes.

[0093] Furthermore, in this invention, the number-average molecular weight of organic polymers containing hydrolyzable silanes refers to the converted value of polystyrene determined by GPC (gel permeation chromatography). In GPC-based determinations, for example, the "ACQUITY APC system" manufactured by Waters Corporation can be used, with Shodex KF604 manufactured by Tosoh Corporation as the GPC column, tetrahydrofuran as the solvent, the column temperature set to 40°C, and the measurement performed at a flow rate of 0.3 ml / min.

[0094] Polymers containing hydrolyzable silyl groups can use commercially available products. For example, polyoxypropylene polymers with dimethoxysilyl groups at the ends of the main chain backbone can be listed as follows: Asahi Glass Co., Ltd.'s products "EXCESTAR A2410" and "EXCESTAR S4530", and KANEKA Co., Ltd.'s products "S203", "S327", "SAT350", "SAX010", and "SAX220".

[0095] Thermally conductive filler material

[0096] The first agent and the second agent of the battery curable adhesive of the present invention, and the battery curable adhesive composition formed by mixing the first agent and the second agent, contain a thermally conductive filler material.

[0097] The content of thermally conductive filler in the battery curable adhesive composition is preferably 60-85% by volume, more preferably 65-80% by volume, and even more preferably 70-80% by volume. Furthermore, the content of thermally conductive filler in both the first and second agents is also preferably within this range.

[0098] When the content of thermally conductive filler material is above these lower limits, the thermal conductivity and heat dissipation of the cured product are improved. On the other hand, when the content of thermally conductive filler material is below these upper limits, the ductility of the cured product is improved, and its ability to follow the expansion and contraction of the single cell is more easily improved.

[0099] The thermally conductive filler material is preferably one containing hydroxyl groups on its surface. If a thermally conductive filler material with hydroxyl groups is used, the organic polymer containing the aforementioned hydrolyzable silane readily reacts with the thermally conductive filler material, increasing the interfacial strength between the organic polymer and the thermally conductive filler material, thereby improving the ductility of the cured product.

[0100] Examples of thermally conductive filler materials with hydroxyl groups on their surface include metal oxides and metal hydroxides.

[0101] Examples of metal oxides include aluminum oxide, magnesium oxide, and zinc oxide, with aluminum oxide being the preferred choice. Examples of metal hydroxides include aluminum hydroxide, magnesium hydroxide, and zinc hydroxide, with aluminum hydroxide being the preferred choice.

[0102] The metal oxides and metal hydroxides are preferably untreated. This is because if surface treatment is performed, the number of hydroxyl groups on the surface decreases, making it more difficult to react with organic polymers. Therefore, untreated alumina is preferred as the metal oxide, and untreated aluminum hydroxide is preferred as the metal hydroxide. Furthermore, in this invention, it is acceptable to use a surface-treated thermally conductive filler material. Surface treatment is performed, for example, by reacting a surface treatment agent such as a silane coupling agent with the surface of the thermally conductive filler material.

[0103] The content of thermally conductive filler with hydroxyl groups on its surface is preferably 50% by mass or more, more preferably 80% by mass or more, further preferably 95% by mass or more, and even more preferably 100% by mass, relative to the total amount of thermally conductive filler in the battery curable adhesive composition. Furthermore, in each of the first and second agents, the content of thermally conductive filler with hydroxyl groups is also preferably within such a range relative to the total amount of thermally conductive filler.

[0104] In the above-mentioned thermally conductive filler materials containing hydroxyl groups, from the viewpoint of improving the shear bond strength and elongation at maximum stress of the cured product, the thermally conductive filler material preferably contains a metal hydroxide.

[0105] In the battery-grade curable adhesive composition, the sum of the surface areas of the aforementioned metal hydroxides is preferably 200 to 1500 m² relative to 100 g of the organic polymer containing hydrolyzable silane. 2 By making the sum of the surface areas of the above metal hydroxides 200–1500 m² 2 The shear bond strength and elongation at maximum stress of the cured product are easily improved. The sum of the surface areas of the metal hydroxide is preferably 300–1200 m². 2 More preferably 500-1000m 2 Furthermore, in both the first and second agents, the sum of the surface areas of the aforementioned metal hydroxides relative to 100g of the hydrolyzable silyl organic polymer is preferably within such a range.

[0106] The sum of the surface areas of the above-mentioned metal hydroxides relative to 100g of the organic polymer having hydrolyzable silyl groups can be determined by the method described in the examples.

[0107] The thermally conductive filler material preferably contains small-particle-size aluminum hydroxide with an average particle size of 20 μm or less. By containing small-particle-size aluminum hydroxide with an average particle size of 20 μm or less, the sum of the surface areas of the metal hydroxides can be easily adjusted to the aforementioned range, and the ductility of the cured product can be easily improved. The average particle size of the small-particle-size aluminum hydroxide is preferably 15 μm or less, more preferably 10 μm or less, and more preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 5 μm or more. In addition, two or more types of small-particle-size aluminum hydroxide with different average particle sizes can also be used together.

[0108] In addition, in this specification, the average particle size is the value of the median diameter (D50) measured by a laser diffraction / scattering particle size distribution measuring device.

[0109] Thermally conductive filler materials can also contain large-particle aluminum hydroxide with an average particle size greater than 20 μm.

[0110] In the battery-grade curable adhesive composition, the ratio (volume%) of small-particle-size aluminum hydroxide to the total amount of aluminum hydroxide is preferably 10 to 100% by volume, more preferably 25 to 100% by volume. Furthermore, in both the first and second agents, the ratio (volume%) of small-particle-size aluminum hydroxide to the total amount of aluminum hydroxide is also preferably within this range.

[0111] Furthermore, from the viewpoint of improving the shear bond strength and elongation at maximum stress of the cured product, the content of metal hydroxide in the battery curable adhesive composition is preferably 10 to 80% by volume, more preferably 15 to 75% by volume. Additionally, the content of metal hydroxide in both the first and second agents is also preferably within such ranges.

[0112] From the viewpoint of improving the thermal conductivity of the cured product, the thermally conductive filler material preferably contains alumina. Furthermore, the thermally conductive filler material is more preferably composed of both aluminum hydroxide and alumina. In this way, the sum of the surface areas of the aforementioned metal hydroxide relative to 100g of the organic polymer containing hydrolyzable silanes can be easily adjusted to the aforementioned range, making it easier to achieve a good balance between improving the thermal conductivity, adhesive strength, and ductility of the cured product.

[0113] When the battery-use curable adhesive composition contains aluminum oxide, its content is preferably 10 to 70% by volume, more preferably 20 to 60% by volume. Furthermore, when the first and second agents each contain aluminum oxide, the aluminum oxide content is also preferably within this range.

[0114] There is no particular limitation on the average particle size of alumina, for example, it is 0.1 to 200 μm, preferably 0.5 to 150 μm, and more preferably 1 to 100 μm. In addition, alumina with different average particle sizes can also be used as alumina.

[0115] <Plasticizers>

[0116] At least one of the first agent and the second agent in the battery curable adhesive of the present invention, and the battery curable adhesive composition formed by mixing the first agent and the second agent, preferably contain a plasticizer. By containing a plasticizer, the ductility of the adhesive is easily improved, and the viscosity is easily reduced, resulting in good workability, etc.

[0117] Specifically, examples of plasticizers include organic ester plasticizers such as monobasic and polybasic organic esters, organic phosphoric acid plasticizers such as organic phosphoric acid plasticizers and organic phosphorous acid plasticizers, sulfonamides, epoxidized soybean oil, and other epoxy plasticizers. Furthermore, organic ester plasticizers are preferred among the aforementioned plasticizers.

[0118] Examples of monobasic organic acid esters include diol esters obtained by reacting a diol with a monobasic organic acid. Examples of diols include triethylene glycol, tetraethylene glycol, and tripropylene glycol. Examples of monobasic organic acids include butyric acid, isobutyric acid, hexanoic acid, 2-ethylbutyric acid, heptanoic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, decanoic acid, and benzoic acid.

[0119] Examples of the aforementioned polybasic organic acid esters include ester compounds formed from polybasic organic acids and straight-chain or branched alcohols with 4 to 8 carbon atoms. Examples of the aforementioned polybasic organic acids include adipic acid, sebacic acid, and azelaic acid.

[0120] Examples of organic ester plasticizers include triethylene glycol di-2-ethylpropionate, triethylene glycol di-2-ethylbutyrate, triethylene glycol di-2-ethylhexanoate, triethylene glycol dioctanoate, triethylene glycol di-n-octanoate, triethylene glycol di-n-heptanoate, tetraethylene glycol di-n-heptanoate, dibutyl sebacate, dioctyl azelate, dibutyl carbitol adipate, ethylene glycol di-2-ethylbutyrate, 1,3-propanediol di-2-ethylbutyrate, 1,4-butanediol di-2-ethylbutyrate, and diethylene glycol di-2-ethylbutyrate. Diethylene glycol di-2-ethylhexanoate, dipropylene glycol di-2-ethylbutyrate, triethylene glycol di-2-ethylvalerate, tetraethylene glycol di-2-ethylbutyrate, diethylene glycol dioctanoate, diethylene glycol dibenzoate, dipropylene glycol dibenzoate, dihexyl adipate, dioctyl adipate, hexylcyclohexyl adipate, mixtures of heptyl adipate and nonyl adipate, diisononyl adipate, diisodecyl adipate, heptylnonyl adipate, dibutyl sebacate, oil-modified sebacate glycol, and mixtures of phosphate esters and adipates, etc. Other organic ester plasticizers besides these can also be used. Other adipates besides those mentioned above can also be used.

[0121] Examples of organophosphate plasticizers include tributoxyethyl phosphate, isodexylphenyl phosphate, and triisopropyl phosphate.

[0122] The plasticizer described above is preferably a diester plasticizer as shown in formula (1) or formula (2).

[0123]

[0124] In the above formula (1), R1 and R2 each represent an organogroup with 2 to 10 carbon atoms, R3 represents ethylene, isopropylidene, or n-propylidene, and p represents an integer from 3 to 10. In the above formula (1), R1 and R2 are preferably organogroups with 5 to 10 carbon atoms, and more preferably organogroups with 6 to 10 carbon atoms.

[0125]

[0126] In formula (2) above, R4 and R5 each represent a hydrocarbon group with 3 to 10 carbon atoms, and R6 represents a hydrocarbon group with 2 to 10 carbon atoms. Preferably, R4 and R5 in formula (2) each have 4 to 9 carbon atoms, more preferably 6 to 9 carbon atoms. The hydrocarbon groups of R4 and R5 are preferably alkyl groups. The alkyl group can be straight-chain or branched. R6 preferably has 4 to 9 carbon atoms, more preferably 5 to 8 carbon atoms. The hydrocarbon group of R6 is preferably an aliphatic hydrocarbon group, more preferably an unsaturated aliphatic hydrocarbon group. R6 can be straight-chain, branched, or cyclic, but preferably cyclic.

[0127] The plasticizers mentioned above preferably include triethylene glycol di-2-ethylhexanoate (3GO), diisononyl 1,2-cyclohexanedicarboxylate (DINCH), triethylene glycol di-2-ethylbutyrate (3GH), or triethylene glycol di-2-ethylpropionate. More preferably, the plasticizers mentioned above include triethylene glycol di-2-ethylhexanoate (3GO) or triethylene glycol di-2-ethylbutyrate (3GH), or diisononyl 1,2-cyclohexanedicarboxylate (DINCH), and even more preferably, triethylene glycol di-2-ethylhexanoate or diisononyl 1,2-cyclohexanedicarboxylate.

[0128] From the viewpoint of reducing the viscosity of the first agent, the second agent, and the composition obtained by mixing them, the molecular weight of the plasticizer is preferably less than 1000, more preferably less than 500, and even more preferably 50 or more, more preferably 100 or more. Further, the molecular weight of the plasticizer is preferably 50 or more and less than 1000, more preferably 100 or more and less than 500. When the structural formula is known, the molecular weight of the plasticizer is the molecular weight calculated from the structural formula; when the structural formula is unknown, it can be determined using a mass spectrometry device (GC-MS or LC-MS).

[0129] The content of plasticizer in the battery-grade curable adhesive composition is preferably 10 to 200 parts by weight, more preferably 100 to 160 parts by weight, relative to 100 parts by weight of the organic polymer having hydrolyzable silane. When the amount of plasticizer is above these lower limits, the viscosity of the composition decreases and workability improves. When the amount of plasticizer is below these upper limits, since the amount of organic polymer can be above a certain value, it can be ensured that the reaction point with the thermally conductive filler is above a certain level, and the shear bond strength can be easily improved.

[0130] In addition, the content of plasticizer in each of the first and second agents is preferably within the above-mentioned range.

[0131] <Silanol Condensation Catalyst>

[0132] The first agent of the battery-grade curable adhesive of the present invention, and the battery-grade curable adhesive composition formed by mixing the first agent and the second agent, preferably contain a silanol condensation catalyst. Furthermore, it is preferable that the second agent does not contain a silanol condensation catalyst. This is because, as described below, the second agent is preferably a water-containing formulation; in this case, if a silanol condensation catalyst is further mixed in, the organic polymer with hydrolyzable silanes will undergo a condensation reaction during storage, resulting in reduced storage stability.

[0133] Examples of organotin compounds that can be used as catalysts for silanol condensation include dibutyltin dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin phthalate, bis(dibutyltin laurate) oxide, bis(acetylacetone) dibutyltin, bis(monoester maleic acid) dibutyltin, tin octoate, dibutyltin octoate, dioctyltin oxide, dioctyltin dineodecanate, dioctyltin distearate, bis(triethoxysilicic acid) dibutyltin, bis(bistriethoxysilicic acid) oxide, dibutyltinoxybisethoxysilicic acid, and 1,1,3,3-tetrabutyl-1,3-dilauryloxycarbonyl-distanoxane, as well as organotitanium compounds such as tetra-n-butoxytitanate and tetraisopropoxytitanate. These silanol condensation catalysts can be used alone or in combination of two or more. Regarding the silanol condensation catalyst, dibutyltin dilaurate is preferred in the above description.

[0135] The content of the silanol condensation catalyst in the battery-use curable adhesive composition is preferably 1 to 10 parts by weight, more preferably 1 to 5 parts by weight, relative to 100 parts by weight of an organic polymer containing hydrolyzable silanes. The content of the silanol condensation catalyst in the first agent is also preferably within this range.

[0136] When the content of silanol condensation catalyst is above these lower limits, the curing speed can be increased; when the content of silanol condensation catalyst is below these upper limits, the decrease in the storage stability of the composition can be suppressed.

[0137] <Adhesion Accelerator>

[0138] The first agent of the battery-grade curable adhesive of the present invention, and the battery-grade curable adhesive composition formed by mixing the first agent and the second agent, preferably contain an adhesion promoter. Furthermore, from the viewpoint of preserving stability, it is preferable that the second agent does not contain an adhesion promoter.

[0139] Adhesion accelerators can further improve the adhesion of cured products of battery-grade curable adhesive compositions.

[0140] Aminosilane coupling agents are preferred as adhesion promoters. Specifically, examples of aminosilane coupling agents include 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N,N'-bis-[3-(trimethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(triethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(methyldimethoxysilyl)propyl]ethylenediamine, N,N'-bis-[3-(trimethoxysilyl)propyl]1,6-hexanediamine, and N,N'-bis-[3-(triethoxysilyl)propyl]1,6-hexanediamine. N-(2-aminoethyl)-3-aminopropyltrimethoxysilane is preferred.

[0141] The content of the adhesion promoter in the battery-use curable adhesive composition is preferably 1 to 10 parts by weight, more preferably 1 to 5 parts by weight, relative to 100 parts by weight of the organic polymer containing hydrolyzable silane. The content of the silanol adhesion promoter in the first agent is also preferably within this range.

[0142] If the content of the adhesive accelerator is above these lower limits, the adhesive strength of the cured product is easily improved. If the content of the adhesive accelerator is below these upper limits, the cured product can be prevented from becoming brittle, thus inhibiting the reduction of adhesive strength.

[0143] <Water>

[0144] The second agent, and the battery-use curable adhesive composition formed by mixing the first and second agents, preferably contain water. This allows the battery-use curable adhesive composition to cure rapidly after mixing the first and second agents, which is therefore preferable.

[0145] Relative to 100 parts by weight of the organic polymer with hydrolyzable silane contained in the battery curable adhesive composition made by mixing the first agent and the second agent, the water content of the second agent is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 15 parts by weight, and even more preferably 1 to 10 parts by weight.

[0146] Similarly, relative to 100 parts by weight of the organic polymer having hydrolyzable silyl groups, the water content in the battery curable adhesive composition is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 15 parts by weight, and even more preferably 1 to 10 parts by weight.

[0147] <Dehydrating agent>

[0148] The first agent and the battery-use curable adhesive composition formed by mixing the first agent and the second agent preferably contain a dehydrating agent. By containing a dehydrating agent, the first agent can be prevented from curing due to moisture contained in the air or the like during storage.

[0149] Examples of dehydrating agents include silane compounds such as vinyltrimethoxysilane, dimethyldimethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane, as well as ester compounds such as methyl orthoformate, ethyl orthoformate, methyl orthoacetate, and ethyl orthoacetate. These dehydrating agents can be used alone or in combination of two or more. Vinyltrimethoxysilane is preferred.

[0150] Relative to 100 parts by weight of the hydrolyzable silyl organic polymer contained in the battery curing adhesive composition composed of the first agent and the second agent, the content of the dehydrating agent in the first agent is preferably 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight. When the content of the dehydrating agent is above these lower limits, curing during storage is easily suppressed; when the content of the dehydrating agent is below these upper limits, it is difficult for a decrease in curability caused by the dehydrating agent to occur.

[0151] Similarly, relative to 100 parts by weight of the organic polymer having hydrolyzable silyl groups, the content of the dehydrating agent in the battery curable adhesive composition is preferably 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight.

[0152] <Dispersant>

[0153] At least one of the first agent and the second agent in the battery curable adhesive of the present invention, as well as the battery curable adhesive composition formed by mixing the first agent and the second agent, may contain a dispersant. By containing a dispersant, viscosity is easily reduced, and workability and other properties become better.

[0154] Examples of dispersants include polymeric dispersants. Polymeric compounds with functional groups are examples of polymeric dispersants. Examples of polymeric compounds include, for example, acrylic, vinyl, polyester, polyurethane, polyether, epoxy, polystyrene, amino, and organosilicon compounds. Furthermore, examples of functional groups include carboxyl, phosphate, sulfonic acid, carboxyl ester, phosphate ester, sulfonate, hydroxyl, amino, quaternary ammonium salt, and amide groups. In addition, substances other than polymeric dispersants can be used as dispersants; for example, alkoxysilane compounds can be used.

[0155] The content of dispersant in the battery-grade curable adhesive composition is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 15 parts by weight, relative to 100 parts by weight of the organic polymer containing hydrolyzable silane. Furthermore, the content of dispersant in each of the first and second agents is also preferably within the above range.

[0156] <Other>

[0157] In this invention, the first agent and the second agent, as well as the battery curable adhesive composition formed by mixing them, may also contain other additives such as thixotropic agents, antioxidants, ultraviolet absorbers, pigments, dyes, antisettling agents, and solvents.

[0158] <Mass ratio and viscosity of Agent 1 and Agent 2>

[0159] The mass ratio of agent 1 to agent 2 (agent 2 / agent 1) is preferably 1 or close to 1, specifically preferably 0.9 to 1.1, and more preferably 0.95 to 1.05. In this way, by making the mass ratio of agent 1 to agent 2 1 or close to 1, the preparation of the mixture of agent 1 and agent 2 becomes easier.

[0160] The viscosity η1 of the first agent at 25°C and a shear rate of 1 (1 / sec) is preferably 100–1000 Pa·s, more preferably 130–980 Pa·s. Similarly, the viscosity η2 of the second agent at 25°C and a shear rate of 1 (1 / sec) is preferably 100–1000 Pa·s, more preferably 130–980 Pa·s. If the viscosities of both the first and second agents are within the above ranges, the processability is good.

[0161] Furthermore, the absolute value of viscosity η1 and the difference between viscosity η and η2 is preferably 400 Pa·s or less, more preferably 300 Pa·s or less, and even more preferably 200 Pa·s or less. When the difference between viscosity η1 and viscosity η2 is so small, mixing of the first agent and the second agent becomes easier, and a composition with high homogeneity is easily obtained. The lower limit of the absolute value of the difference between viscosity η1 and viscosity η2 is 0 Pa·s.

[0162] In addition, the above-mentioned viscosities η1 and η2 were measured by a rheometer, as detailed in the examples.

[0163] The first agent and the second agent are filled into separate containers. Specifically, the first agent is filled into a first container, and the second agent is filled into a second container. The first and second containers can be separate or integrated. By integrating the first and second containers, it is easy to supply them to the demander as a container kit. Furthermore, in this specification, the first container filled with the first agent and the second container filled with the second agent are sometimes referred to together as a container kit.

[0164] Examples of containers include syringes, boxes, cans, and barrels, but are not limited to these. For example, when filling a syringe, a two-liquid parallel-flow syringe is preferred. (Example: A two-liquid parallel-flow syringe 30) Figure 1 As shown, the first syringe 31, which constitutes the first container, and the second syringe 32, which constitutes the second container, are arranged side by side as one unit. The first agent 35 and the second agent 36 filled in the syringes 31 and 32 can be dispensed from the syringes and mixed by the syringes as dispensers.

[0165] Alternatively, when using boxes, the container kit consists of a first box constituting the first container and a second box constituting the second container, and these boxes can also be integrated. Furthermore, the boxes can typically be mounted on syringes (e.g., a first syringe, a second syringe), and the first agent dispensed from the first box and the second agent dispensed from the second box are discharged and mixed from their respective outlets using the syringes as dispensers.

[0166] The mixing of agent 1 and agent 2 can be carried out using a mixer such as a static mixer. Static mixer 38, for example... Figure 1 As shown, the first agent 35 and the second agent 36 discharged from the outlets 31A and 32A of the first syringe 31 and the second syringe 32, respectively, are connected to the mixer 38, enabling them to be mixed inside the mixer 38. The mixture (curable composition) obtained by the mixer 38 can be discharged from the outlet 39 of the mixer 38.

[0167] Each syringe 31, 32 may have an opening of a tubing 33A, 34A respectively filled with a first agent 35 and a second agent 36, which is closed by a cap 33B, 34B. Figure 1 In the syringe 30 shown, the caps 33B and 34B can be removed, and the first agent 35 and the second agent 36 can be pushed out through the piston (not shown) inserted from the opening, and discharged from the discharge ports 31A and 32A.

[0168] Additionally, when using tanks, container kits such as Figure 2As shown, a first can 41, which constitutes a first container and is filled with a first agent 45, and a second can 42, which constitutes a second container and is filled with a second agent 46. Furthermore, each can 41 and 42, for example, filled with the first agent 45 and the second agent 46, has a container body 43A and 44A with an opening, and a cap 43B and 44B that closes the opening of each container body 43A and 44B.

[0169] [Battery Structure]

[0170] The battery structure of the present invention comprises a structure and a plurality of battery cells disposed on the structure, wherein an adhesive layer is disposed between the structure and the battery cells, and between the plurality of battery cells. The adhesive layer is a cured product of a battery-grade curable adhesive composition containing an organic polymer having a hydrolyzable silane and a thermally conductive filler material. The cured product has a shear bond strength of 0.5 to 2.5 MPa, an elongation at maximum stress of 0.3 mm or more at a thickness of 2 mm, and a thermal conductivity of 1.5 W / m·K or more.

[0171] The cured material constituting the adhesive layer in the battery structure is the aforementioned curable adhesive composition for batteries.

[0172] The components of the battery-grade curable adhesive composition are as described above.

[0173] Furthermore, the shear bond strength, elongation at maximum stress, and thermal conductivity of the cured product of the battery-use curable adhesive composition are also as described above.

[0174] As a structure, it consists of various components that form the battery structure, such as the substrate connecting the battery cells, the housing of the battery pack, the housing of the battery module, the cooling plate, the water cooling plate, etc.

[0175] The cured product of the battery curable adhesive or battery curable adhesive composition of the present invention can be used as at least one of the following gap materials: gap material between individual cells, gap material between individual cells and module frame, gap material between battery module and battery pack frame, and gap material between individual cells and battery pack frame.

[0176] The following describes specific examples of the battery structure of the present invention.

[0177] Figure 3 A battery structure (battery module) 10 is shown, comprising a housing (frame) 11 containing a battery module and a plurality of battery cells 12 disposed within the housing 11. Each battery cell 12 is arranged with its flat surfaces facing each other. Furthermore, an adhesive layer 13, which is a cured product of a battery-grade curable adhesive composition, is fixed between the plurality of battery cells 12.

[0178] Battery cell 12 is a constituent unit of lithium-ion secondary batteries, etc., and generally consists of an outer packaging film and battery elements (not shown) sealed inside the outer packaging film. These battery elements may include a positive electrode, a negative electrode, a separator, and an electrolyte. Figure 4 As shown, the battery cell 12 is a flat body with a thickness thinner than its width, with the positive electrode 12a and the negative electrode 12b exposed on the outside, and the flat surface 12c being formed to be thicker than the crimped end 12d.

[0179] Battery cell 12 describes a laminated battery cell using an outer packaging film, but in addition to laminated battery cells, square battery cells or cylindrical battery cells may also be used.

[0180] like Figure 5 As shown, the adhesive layer 13 can also be disposed in the gap B between the housing 11 and the battery cell 12.

[0181] The adhesive layer 13 is provided in at least one of the gap B between the housing 11 and the battery cell 12 and the gap A between the plurality of battery cells 12. Alternatively, although not shown, the adhesive layer 13 may also be provided in both the gap B between the housing 11 and the battery cell 12 and the gap A between the plurality of battery cells 12.

[0182] Figure 6 This indicates a battery structure (battery pack) 20 comprising a housing (frame) 14 of a battery pack and a plurality of battery modules 10 disposed within the housing 14 of the battery pack. An adhesive layer 13 is fixed to the gap C between the plurality of battery modules 10.

[0183] In addition, Figure 6 In the middle, the adhesive layer 13 is also fixed in the gap D between the battery pack housing 14 and the battery module 10.

[0184] In addition, Figure 6 The diagram shows two forms of the adhesive layer 13 being fixed between the battery pack housing 14 and the battery module 10, and between the multiple battery modules 10. However, the adhesive layer 13 may also be fixed between at least one of the gaps D between the battery pack housing 14 and the battery module 10, and between the multiple battery modules 10.

[0185] In addition, Figure 6 The diagram shows a configuration where the adhesive layer 13 is not used inside the battery module 10. However, inside the battery module 10 disposed within the battery pack, it is also possible to use an adhesive layer 13. Figure 3 and Figure 5 The adhesive layer 13 is set as shown.

[0186] Figure 7A battery structure 30 without a casing is schematically shown. The battery structure 30 has a plurality of individual cells 12 and a cooling plate 15, on which the plurality of individual cells 12 are bonded by an adhesive layer 13, which is a cured product of a battery curable adhesive composition, to the cooling plate 15.

[0187] The adhesive layer of the cured product of the battery-use curable adhesive composition of the present invention has moderate adhesive strength, thus enabling the fixing of various structures and battery cells, or battery cells to each other, ensuring a certain strength, and allowing for peeling as needed. Excessive stress is not generated during peeling, thus preventing deformation of the structures and battery cells, and resulting in excellent recyclability. Furthermore, the cured product (adhesive layer) possesses both high thermal conductivity and good ductility, exhibiting excellent shape conformability to the expansion and contraction of battery cells, etc.

[0188] Example

[0189] The present invention will be described in more detail below by way of examples, but the present invention is not limited by these examples.

[0190] In this embodiment, the evaluation is performed using the following method.

[0191] [Shear bond strength, elongation at maximum stress]

[0192] Shear bond strength and elongation at maximum stress were measured according to the tensile shear test in JIS K6850:1999. Two substrates {KTL board (manufactured by Testpanel Co., Ltd., Japan, material: SPCC-SD, style: cationic electrodeposition coating (black))} were prepared, with the front ends of the substrates overlapping each other at a length of 25mm x 25mm. Between the overlapping portions of the substrates, a battery-grade curable adhesive composition consisting of equal parts (mass ratio 1:1) of the first and second agents was applied to a thickness of 2mm. The mixture was cured at 25°C and 50% RH for 2 weeks to prepare the test specimen. Using a tensile testing machine (TENSILON RTC-1310A manufactured by A&D), tensile tests were conducted on the specimens described above at room temperature (25°C) and a tensile speed of 10 mm / min. The tensile shear strength was measured, and the maximum stress on the obtained stress curve was taken as the shear bond strength. Additionally, the displacement at which the tensile stress reached its maximum value was taken as the elongation (mm) at maximum stress.

[0193] [Viscosity]

[0194] Regarding the viscosity (Pa·s) of each of the first and second agents at 25°C, a rheometer (e.g., Anton Paar's MCR-302e rheometer) was used. The sample temperature was adjusted to 25°C using a Peltier plate. Using parallel plates with a diameter of 20 mm, the shear rate was continuously varied within the range of 0.0001 to 100 (1 / sec) with a gap of 1 mm, and the viscosity was measured simultaneously. The viscosity (Pa·s) value is the viscosity at a shear rate of 1 (1 / s).

[0195] [2 Liquefaction]

[0196] The curable adhesives for batteries in the various embodiments and comparative examples were evaluated as follows.

[0197] A: Both Agent 1 and Agent 2 have properties that allow for viscosity measurement, and Agent 2 was liquefied.

[0198] B: The viscosity of either or both of the first and second agents could not be determined, and the agent was not liquefied by agent 2.

[0199] Thermal conductivity

[0200] A battery-grade curable adhesive composition prepared by mixing equal amounts of Agent 1 and Agent 2 (mass ratio 1:1) was cured for 2 weeks at 25°C and 50%RH. The resulting cured product was used as a sample to determine its thermal conductivity.

[0201] Thermal conductivity was determined using a method that measures thermal resistance according to ASTM D5470-06. Specifically, cured materials with thicknesses of 1.0 mm, 1.5 mm, and 2.0 mm were prepared, and the thermal resistance and thickness were measured when compressed at 30 psi. For these three thermal resistance values, a line graph was plotted with thickness on the horizontal axis and thermal resistance on the vertical axis. An approximate straight line was obtained at the three points using the least squares method. The slope of this approximate straight line was then taken as the thermal conductivity.

[0202] Thermal resistance was measured at 80°C using a Long Win Science and Technology Corporation LW-9389.

[0203] [Observation of Destructive Patterns]

[0204] Observe the test pieces after the above shear bond strength test, and observe the failure mode of the cured material (adhesive layer).

[0205] <Overall Evaluation>

[0206] A: Thermal conductivity above 1.5 W / mK, shear bond strength of 0.7–2.5 MPa, and elongation at maximum stress above 0.4 mm.

[0207] B: Although the thermal conductivity is above 1.5 W / mK, and neither the shear bond strength nor the elongation at maximum stress satisfies the conditions in A above, the shear bond strength is 0.5 to 2.5 MPa, and the elongation at maximum stress is above 0.3 mm.

[0208] C: Meets any of the following criteria: Thermal conductivity less than 1.5 W / mK, shear bond strength less than 0.5 MPa, and elongation at maximum stress less than 0.3 mm.

[0209] The components used in the examples are as follows.

[0210] <Organic polymers containing hydrolyzable silanes>

[0211] • KANEKA's "MS Polymer SAX010" is an organic polymer with a number average molecular weight of 2400, linear structure, 94% terminal silylation, and dimethoxymethylsilyl groups at both ends of the polyoxypropylene.

[0212] • KANEKA's "MS Polymer SAT115" is an organic polymer with a number average molecular weight of 3400, a linear structure, a 60% terminal silylation rate, and dimethoxymethylsilyl groups at both ends of the polyoxypropylene.

[0213] · KANEKA's "MS Polymer SAT350" is an organic polymer with a number average molecular weight of 6800, a linear structure, a 91% terminal silylation rate, and dimethoxymethylsilyl groups at both ends of the polyoxypropylene.

[0214] AGC's "S4530" is a linear polymer with a number average molecular weight of 25,000 and a terminal silylation rate of 86%. It consists of dimethoxymethylsilyl groups at both ends of the polyoxypropylene.

[0215] Thermally conductive filler material

[0216] • Aluminum hydroxide 1 (untreated, amorphous, average particle size 90 μm, specific gravity 2.4 g / cm³) 3 )

[0217] • Aluminum hydroxide 2 (untreated, amorphous, average particle size 50 μm, specific gravity 2.4 g / cm³) 3 )

[0218] • Aluminum hydroxide 3 (untreated, amorphous, average particle size 10 μm, specific gravity 2.4 g / cm³) 3 )

[0219] • Aluminum hydroxide 4 (untreated, amorphous, average particle size 1 μm, specific gravity 2.4 g / cm³)3 )

[0220] • Aluminum hydroxide 5 (untreated, amorphous, average particle size 105 μm, specific gravity 2.4 g / cm³) 3 )

[0221] • Alumina 1 (untreated, spherical, average particle size 70μm, specific gravity 3.94g / cm³) 3 )

[0222] • Alumina 2 (untreated, spherical, average particle size 50μm, specific gravity 3.94g / cm³) 3 )

[0223] • Alumina 3 (untreated, spherical, average particle size 10μm, specific gravity 3.94g / cm³) 3 )

[0224] • Alumina 4 (untreated, spherical, average particle size 3μm, specific gravity 3.94g / cm³) 3 )

[0225] • Alumina 5 (untreated, spherical, average particle size 43μm, specific gravity 3.94g / cm³) 3 )

[0226] • Alumina 6 (untreated, spherical, average particle size 12.5 μm, specific gravity 3.94 g / cm³) 3 )

[0227] <Plasticizers>

[0228] Triethylene glycol di(2-ethylhexanoate) 3GO

[0229] DINCH 1,2-Cyclohexanedicarboxylate

[0230] <Additives>

[0231] Silanol condensation catalyst: Dibutyltin dilaurate

[0232] Silanol condensation catalyst 2: Dioctyltin dineodecanate, trade name "U-830", manufactured by Nitto Chemical Co., Ltd.

[0233] water

[0234] Dehydrating agent: Vinyltrimethoxysilane

[0235] Adhesion accelerator: N-(2-aminoethyl)-3-aminopropyltrimethoxysilane

[0236] Dispersant: "DISPERBYK-106" manufactured by BYK-Chemie.

[0237] Compatibilizer: Butylcarbidol

[0238] Antioxidant: Songwon, SONGNOX1010

[0239] <Calculation of the sum of the surface areas of metal hydroxides>

[0240] The sum of the surface areas (m²) of 100g of metal hydroxide relative to the organic polymer with hydrolyzable silyl groups. 2 ), is based on the surface area (m²) of each 1g of the mixed metal hydroxides. 2 / g), which is calculated by summing the proportions of each metal hydroxide.

[0241] For example, the surface area (m²) of 1g of a metal hydroxide with an average particle size of A μm. 2 / g) is calculated according to the following formula (1).

[0242] The surface area (m²) of metal hydroxide per 1g with an average particle size of A μm 2 / g)=

[0243] Surface area of ​​a single particle (m 2 / particle) / volume of one particle (m) 3 / particles) / specific gravity (g / cm³) 3 ) / 10 -6 Equation (1)

[0244] The surface area (m²) of a single particle in equation (1) 2 / particle), through "4×π×(A / 2) 2 ×10 -12 "calculate.

[0245] The volume (m³) of a single particle in equation (1) 3 / particle), through "(4 / 3)×π×(A / 2) 3 ×10 -18 "Calculate. Also, π is the value of a circle's circumference."

[0246] [Example 1]

[0247] According to the formulation in Table 1, the first agent was prepared by mixing a hydrolyzable silane-containing organic polymer (MS Polymer SAT350), aluminum hydroxide 1, aluminum hydroxide 4, aluminum oxide 2, aluminum oxide 3, a plasticizer, a silanol condensation catalyst, a dehydrating agent, an adhesion promoter, a dispersant, and an antioxidant together. The second agent was prepared by mixing a hydrolyzable silane-containing organic polymer (MS Polymer SAT350), aluminum hydroxide 1, aluminum hydroxide 4, aluminum oxide 2, aluminum oxide 3, a plasticizer, water, and a dispersant together, according to the formulation in Table 1. Thus, a battery-grade curable adhesive composed of the first and second agents was obtained.

[0248] [Examples 2-10, Reference Examples 1-2, Comparative Examples 1-6]

[0249] Except for changing the types and amounts of each component according to Tables 1, 1-2 and 1-3, a battery curable adhesive composed of the first agent and the second agent was obtained in the same manner as in Example 1.

[0250]

[0251]

[0252]

[0253]

[0254]

[0255] The battery-grade curable adhesives of each embodiment are composed of a first agent and a second agent comprising an organic polymer having a hydrolyzable silane group and a thermally conductive filler. The viscosities of the first agent and the second agent are both within suitable ranges, allowing for liquefaction and use. Furthermore, the cured product of the battery-grade curable adhesive composition formed by mixing the first agent and the second agent exhibits a shear bond strength of 0.5 to 2.5 MPa, an elongation at maximum stress of 0.3 mm or more, and a thermal conductivity of 1.5 W / m·K or more. In other words, the battery-grade curable adhesives of the embodiments have a thermal conductivity as high as 1.5 W / m·K or more, demonstrating excellent heat dissipation. Additionally, the elongation at maximum stress shows a high value of 0.3 mm or more, exhibiting excellent conformability to the expansion and contraction of a single cell. Moreover, with a shear bond strength of 0.5 to 2.5 MPa, the cured product can fix components forming the battery structure with appropriate adhesive force, and when peeling off the cured product, excessive stress is not required, resulting in excellent peelability.

[0256] The battery-curing adhesive of Reference Example 1 meets the specified values ​​of the present invention in terms of shear bond strength, elongation at maximum stress, and thermal conductivity. On the other hand, the compositions of the first and second agents are significantly different; for example, only the first agent contains an organic polymer with hydrolyzable silyl groups, and the amount of plasticizer (diluent) in the first agent is relatively small, resulting in a large viscosity difference and poor workability. Similarly, the battery-curing adhesive of Reference Example 2 also has significantly different compositions of the first and second agents, resulting in a large viscosity difference and poor processability. Furthermore, the battery-curing adhesive of Reference Example 2 has a low terminal silylation rate of the organic polymer, leading to low reactivity with thermally conductive fillers containing hydroxyl groups and poor shear bond strength.

[0257] Furthermore, in Reference Examples 1 and 2, it was considered to reduce the viscosity difference by changing the formulation of the thermally conductive filler materials of Agent 1 and Agent 2. However, in this case, the design freedom of the organic polymer of Agent 1, which has a lower plasticizer dosage, is reduced; for example, only organic polymers with low viscosity can be used. Additionally, from the viewpoint of reducing viscosity, it is possible to reduce the total amount of thermally conductive filler material by increasing the proportion of alumina, which has high thermal conductivity. However, in this case, the shear bond strength is prone to decrease due to the reduced amount of alumina.

[0258] The curable adhesive for batteries in Comparative Example 1 has low shear bond strength and cannot secure the components forming the battery structure with appropriate adhesive force. This is because the sum of the surface areas of the metal hydroxides relative to 100g of the organic polymer is smaller than that in the examples.

[0259] The curable adhesive used in Comparative Example 2 also exhibits low shear bond strength, failing to secure components forming the battery structure with appropriate adhesive force. It can be assumed that Comparative Example 2 is due to the higher molecular weight of the hydrolyzable silyl organic polymer used, resulting in a lower concentration of the reaction point with the thermally conductive filler material containing hydroxyl groups.

[0260] The curable adhesives used in Comparative Examples 3 and 6 also exhibited low shear bond strength, failing to secure the components forming the battery structure with appropriate adhesive force. It can be assumed that Comparative Examples 3 and 6 are due to the low terminal silanization rate of the hydrolyzable silane-containing organic polymers used, resulting in a lower concentration of the reaction point with the thermally conductive filler material containing hydroxyl groups.

[0261] In Comparative Examples 4 and 5, the elongation at maximum stress was smaller, resulting in poorer tracking of expansion and contraction relative to the single cell. This can be attributed to the presence of a large amount of small-particle aluminum hydroxide, which has a larger surface area than the sum of the surface areas of 100g of the organic polymer metal hydroxide.

[0262] Explanation of symbols in attached drawings

[0263] 10-cell structure

[0264] 11 Battery module housing

[0265] 12 battery cells

[0266] 12a positive electrode

[0267] 12b negative electrode

[0268] 12c flat surface

[0269] 12d end

[0270] 13 adhesive layers

[0271] 14 Battery Pack Casing

[0272] 15 cooling plates

[0273] 20-cell structure

[0274] 30 syringes

[0275] 31 First syringe

[0276] 31A First Syringe Discharge Port

[0277] 32 Second syringe

[0278] 32A No. 2 syringe discharge port

[0279] 33A and 34A tubes

[0280] Cap of 33B and 34B tubes

[0281] 35, 45, first dose

[0282] 36, 46, second dose

[0283] 38 Mixer

[0284] 39 Mixer outlet

[0285] 40 battery structure

[0286] 41. Can No. 1

[0287] 42, second can

[0288] 43A and 44A have open container bodies.

[0289] 43B, 44B A lid that closes the opening of the main body of a container.

Claims

1. A battery-grade curable adhesive, comprising a first agent and a second agent, The first agent contains a silanol condensation catalyst and a thermally conductive filler material, and is filled in a first container. The second agent contains an organic polymer with hydrolyzable silane and a thermally conductive filler material, and is filled in a second container. The cured product obtained by curing the battery-grade curable adhesive composition formed by mixing the first and second agents at 25°C and 50% RH for 2 weeks showed a shear bond strength of 0.5–2.5 MPa in a tensile shear test. The cured material, at a thickness of 2 mm, exhibits an elongation of more than 0.3 mm at maximum stress in a tensile shear test. The thermal conductivity of the cured material is above 1.5 W / m·K.

2. The battery-grade curable adhesive as described in claim 1, wherein the content of the thermally conductive filler in the battery-grade curable adhesive composition is 60-85% by volume. The thermally conductive filler material contains a thermally conductive filler material with hydroxyl groups on its surface.

3. The battery-grade curable adhesive as described in claim 1 or 2, wherein the content of the thermally conductive filler in the battery-grade curable adhesive composition is 60-85% by volume, and the thermally conductive filler contains a metal hydroxide. The total surface area of ​​the metal hydroxides is 200–1500 m² relative to 100 g of the hydrolyzable silyl organic polymer in the battery curing adhesive composition. 2 .

4. The battery curable adhesive as described in claim 1 or 2, wherein the first agent further comprises an organic polymer having a hydrolyzable silane group.

5. The battery-grade curable adhesive as described in claim 1 or 2, wherein the second agent further contains water.

6. The battery curable adhesive as described in claim 3, wherein the content of metal hydroxide in the battery curable adhesive composition is 10-80% by volume.

7. The battery-grade curable adhesive as described in claim 3, wherein the metal hydroxide is aluminum hydroxide.

8. The battery curable adhesive as described in claim 3, wherein the metal hydroxide is untreated aluminum hydroxide.

9. The battery curable adhesive as described in claim 1 or 2, wherein the thermally conductive filler contains small-particle-size aluminum hydroxide with an average particle size of less than 20 μm.

10. The battery-grade curable adhesive as described in claim 1 or 2, wherein the organic polymer having hydrolyzable silane is a polyoxyethylene having hydrolyzable silane.

11. The battery curable adhesive as claimed in claim 1 or 2, wherein the organic polymer having hydrolyzable silanes has hydrolyzable silanes at the ends of its linear main chain.

12. The battery-grade curable adhesive as described in claim 1 or 2, wherein the number-average molecular weight Mn of the organic polymer having hydrolyzable silane is 1000 to 40000.

13. The battery-grade curable adhesive as claimed in claim 1 or 2, wherein at least one of the first agent and the second agent further comprises a plasticizer.

14. The battery curable adhesive as described in claim 1 or 2, wherein the viscosity η1 of the first agent measured at 25°C and a shear rate of 1 / sec is 100 to 1000 Pa·s, and the viscosity η2 of the second agent measured at 25°C and a shear rate of 1 / sec is 100 to 1000 Pa·s, and the absolute value of the difference between the viscosity η1 and the viscosity η2 is less than 400 Pa·s.

15. A battery structure having a structure and a plurality of battery cells disposed within the structure, An adhesive layer is disposed at least at one location between the structure and the battery cell, and between the plurality of battery cells. The adhesive layer is a cured product of a battery-grade curable adhesive composition containing an organic polymer with hydrolyzable silane and a thermally conductive filler material. The cured product has a shear bond strength of 0.5 to 2.5 MPa as measured in a tensile shear test, an elongation at maximum stress of 0.3 mm or more as measured in a tensile shear test when the cured product is 2 mm thick, and a thermal conductivity of 1.5 W / m·K or more.

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