Composite member

Abstract

Provided is a composite member which does not require winding work, can easily handle complex shapes, can suppress the occurrence of burning and peeling of an insulating film even when heated at high temperatures, and can maintain excellent insulation and heat resistance. A composite member (1) has a metal base material (2) and an insulating coating (3) that covers at least a portion of the surface of the base material (2). The insulating coating (3) has: a matrix (10) containing a compound with a siloxane bond; and an inorganic material (20) dispersed in the matrix. At normal temperature, the base material (2) and the insulation coating (3) are in contact with each other. When heated to a temperature equal to or higher than the oxidation initiation temperature of the metal constituting the base material (2), an adhesive layer (8) is formed between the base material (2) and the insulation coating (3). The adhesive layer (8) has a metal element included in the base material (2), a metal oxide of a metal element, an inorganic material (20), and at least one selected from silicone and silica.

Description

Composite materials

[0001] The present invention relates to a composite member in which a substrate is coated with an insulating coating.

[0002] Conductive materials, which are metal pieces with insulating coatings formed on their surfaces, are used to electrically connect components. For example, various electronic devices, electric vehicles or hybrid vehicles driven by electric motors, and storage batteries are equipped with power storage devices in which multiple battery cells are connected in series or parallel by conductive bus bars. Furthermore, lithium-ion secondary batteries, which have higher capacity and higher output than lead-acid batteries or nickel-metal hydride batteries, are primarily used as battery cells.

[0003] When a battery cell is charged or discharged, an overcurrent may flow through the bus bar, causing the bus bar to heat up and possibly even burst into flames. Therefore, the bus bar must be heat-resistant as well as insulating. For example, Patent Document 1 (JP-A-2003-125566) describes a bus bar in which a ceramic tape, such as mica tape, is wrapped around a copper bus bar body as a fire-resistant layer.

[0004] Chinese Utility Model No. 216902355

[0005] However, in Patent Document 1, the ceramic tape must be wrapped around the busbar body. Due to spatial limitations in the installation location of the battery cells, the busbar may have a complex shape, making it difficult to wrap the ceramic tape thoroughly around every corner of the busbar body. If the ceramic tape has uneven wrapping or gaps, sufficient insulation and heat resistance cannot be achieved. Furthermore, the adhesive surface of the ceramic tape may peel off. Furthermore, nylon tape is wrapped around the outside of the mica tape as an insulating layer, but nylon tape is sensitive to heat and has heat resistance issues. In particular, if a fire breaks out near the busbar, the insulating layer formed around the busbar body will immediately burn off.

[0006] Therefore, an object of the present invention is to provide a composite member that has excellent insulation and heat resistance, does not require winding work like ceramic tape, is free from problems such as uneven winding, gaps, and peeling, can be easily adapted to complex shapes, and can suppress burning and peeling of the insulating coating even when heated at high temperatures, thereby maintaining excellent insulation and heat resistance.

[0007] The above object of the present invention is achieved by the following configuration [1] or [2] relating to a composite member.

[0008] [1] A composite member having a metal substrate and an insulating coating covering at least a portion of the surface of the substrate, wherein the insulating coating has a matrix containing a compound having a siloxane bond and an inorganic material dispersed in the matrix, wherein the substrate and the insulating coating are in contact at room temperature, and when heated to a temperature equal to or higher than the oxidation start temperature of the metal constituting the substrate, an adhesive layer is formed between the substrate and the insulating coating, and the adhesive layer comprises a metal element contained in the substrate, a metal oxide of the metal element, the inorganic material, and at least one selected from silicone and silica.

[0009] [2] A composite member having a metal substrate, an insulating coating covering at least a portion of the surface of the substrate, and an adhesive layer formed between the substrate and the insulating coating, wherein the insulating coating has a matrix containing a compound having a siloxane bond and an inorganic material dispersed in the matrix, and the adhesive layer has a metal element contained in the substrate, a metal oxide of the metal element, the inorganic material, and at least one selected from silicone and silica.

[0010] Furthermore, preferred embodiments of the present invention relating to the composite member relate to the following [3] to

[18] .

[0011] [3] The composite material according to [1] or [2], wherein the insulating coating has pores that connect the outside to the surface of the substrate.

[0012] [4] The composite material according to any one of [1] to [3], wherein the insulating coating has a thickness of 150 μm or more.

[0013] [5] The composite material according to any one of [1] to [4], characterized in that at least a part of the surface of the insulating coating has a surface layer made of the matrix material.

[0014] [6] The composite material according to [5], wherein the thickness of the surface layer is 10 μm or more and 100 μm or less.

[0015] [7] The composite member according to any one of [1] to [6], characterized in that the insulating coating has a first coating containing the matrix and the inorganic material, and a second coating made of the matrix material, and the first coating and the second coating are alternately stacked in this order from the substrate side.

[0016] [8] The composite material according to [7], characterized in that the thickness of each of the second coatings is 10 μm or more and 100 μm or less.

[0017] [9] The composite material according to any one of [1] to [8], characterized in that at least a part of the surface of the insulating coating has a resin layer containing a resin different from the material of the matrix.

[0018]

[10] The composite material according to [9], characterized in that the resin layer has a thickness of 100 μm or more and 600 μm or less.

[0019]

[11] The composite material according to any one of [1] to

[10] , wherein the compound having a siloxane bond is at least one of silicone and silica sol.

[0020]

[12] The composite member according to any one of [1] to

[11] , characterized in that the inorganic material contains at least one selected from silica, alumina, mullite, and zirconia.

[0021]

[13] The composite member according to any one of [1] to

[11] , characterized in that the inorganic material contains at least one selected from glass-based materials, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth, and halloysite.

[0022]

[14] The composite member according to

[13] , characterized in that the adhesive layer contains 18% by mass or more and 22% by mass or less of oxygen, 5% by mass or less of magnesium, 5% by mass or less of aluminum, 8% by mass or more and 12% by mass or less of silicon, 5% by mass or less of potassium, and 50% by mass or more and 70% by mass or less of copper.

[0023]

[15] The composite member according to any one of [1] to

[14] , wherein the inorganic material contains at least one selected from the group consisting of flakes, fibers, and particles.

[0024]

[16] The composite member according to any one of [1] to

[11] , wherein the inorganic material contains at least one of a glass flake material and mica.

[0025]

[17] The composite material according to any one of [1] to

[16] , wherein the substrate is a bus bar that connects a plurality of battery cells or battery modules.

[0026]

[18] The composite material according to any one of [1] to

[16] , wherein the substrate is a connector, a protective component for a battery module, a case for an electronic component, a battery cell, a battery module, a battery pack, or a motor coil.

[0027] The composite material of the present invention has an insulating coating that covers at least a portion of the substrate and contains a compound having a siloxane bond and an inorganic material, thereby achieving excellent heat resistance and insulating properties. Furthermore, the composite material of the present invention has a structure in which the substrate and the insulating coating are in contact with each other at room temperature, and when heated to a temperature equal to or higher than the oxidation onset temperature of the metal that constitutes the substrate, an adhesive layer is formed between the substrate and the insulating coating, or an adhesive layer is already formed at room temperature. Therefore, even if a flame breaks out near the composite material, the insulating coating can be prevented from burning off or peeling off, and heat resistance and insulating properties can be maintained.

[0028] FIG. 1 is a SEM photograph of a cross section of a composite member according to this embodiment. FIG. 2 is a SEM photograph of a cross section of a composite member according to this embodiment after heating at 1000°C. FIG. 3 is an enlarged view of a portion of FIG. 2. FIG. 4 is an optical microscope photograph of the composite member heated at 1000°C shown in FIG. 2. FIG. 5 is a photograph of a composite member according to another embodiment of the present invention. FIG. 6 is a perspective view of a bus bar to which a composite member according to this embodiment is applied. FIG. 7A is a diagram showing a manufacturing method for a composite member according to this embodiment in the order of steps, and is a schematic diagram showing a first deposition step. FIG. 7B is a diagram showing a manufacturing method for a composite member according to this embodiment in the order of steps, and is a schematic diagram showing a first immersion step. FIG. 7C is a diagram showing a manufacturing method for a composite member according to this embodiment in the order of steps, and is a schematic diagram showing a second deposition step. FIG. 7D is a diagram showing a manufacturing method for a composite member according to this embodiment in the order of steps, and is a schematic diagram showing a second immersion step. Fig. 8A is a diagram showing the process steps of a manufacturing method for a composite member according to another embodiment of the present invention, and is a schematic diagram showing a first deposition step. Fig. 8B is a diagram showing the process steps of a manufacturing method for a composite member according to another embodiment of the present invention, and is a schematic diagram showing a first immersion step. Fig. 8C is a diagram showing the process steps of a manufacturing method for a composite member according to another embodiment of the present invention, and is a schematic diagram showing a second deposition step. Fig. 8D is a diagram showing the process steps of a manufacturing method for a composite member according to another embodiment of the present invention, and is a schematic diagram showing a second immersion step.

[0029] The present inventors conducted extensive research to obtain a composite member that can solve the above-mentioned problems without using an insulating tape such as ceramic tape. As a result, they discovered that by applying an insulating coating material to the surface of a substrate and forming an insulating coating that covers the surface of the substrate, it is possible to easily adapt the composite member to complex shapes. However, simply applying an insulating coating material and curing the material to form an insulating coating can cause the insulating coating to burn off if a flame breaks out near the composite member, making it difficult to maintain insulation.

[0030] The present inventors therefore focused on the region where the metal substrate and the insulating coating are bonded and found that when an adhesive layer containing specific components is formed in this region, the insulating coating is able to maintain its insulating properties without peeling off even in the event of a flame. The present invention was made based on this finding.

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and can be implemented with any modifications within the scope of the gist of the present invention.

[0032] [Composite Member] FIG. 1 is a photograph of a cross section of a composite member according to this embodiment, taken with a scanning electron microscope (SEM). The composite member 1 has a metal substrate 2 and an insulating coating 3 that covers at least a portion of the surface of the substrate 2. The insulating coating 3 has a matrix 10 containing a compound having a siloxane bond and an inorganic material 20 dispersed in this matrix 10. The composite member 1 may also have a surface layer 4 made of the material of the matrix 10, which will be described later, on at least a portion of the surface of the insulating coating 3. In this embodiment, at room temperature, the substrate 2 and the insulating coating 3 are in contact with each other, as shown in FIG. 1.

[0033] FIG. 2 is a SEM photograph of a cross section of a composite member according to this embodiment after heating at 1000°C. FIG. 3 is an enlarged view of a portion of FIG. 2. FIG. 4 is an optical microscope photograph of the composite member shown in FIG. 2 heated at 1000°C. In FIG. 2, the substrate 2 is out of view, but an adhesive layer 8 is formed between the substrate 2 and the insulating coating 3. As will be described in detail later, in this embodiment, a copper substrate is used as the substrate 2, and mica is used as the inorganic material 20. The adhesive layer 8 contains copper, copper oxide (an oxide of copper), mica, and at least one selected from silicone and silica. As shown in the enlarged photograph of FIG. 3, the substrate 2 containing copper (copper oxide) and the insulating coating 3 containing mica and silicone (silica) are fused together within the adhesive layer 8.

[0034] In the composite material 1 configured as described above, the base material 2 is not insulated by wrapping tape around it, but rather an insulating coating material is applied to the surface of the base material 2, forming an insulating coating 3 that adheres closely to the base material 2. Therefore, when manufacturing the composite material 1 according to this embodiment, no wrapping work is required, there are no problems with uneven winding, gaps, or peeling, and it can easily be made to fit complex shapes. In addition, the insulating coating 3 is made of silicone or silica sol (silica: SiO ２ Because the composite material 1 includes the matrix 10 containing a compound having a siloxane bond (Si—O—Si bond) such as methyl methacrylate, and the inorganic material 20, the composite material 1 is less likely to deteriorate even when exposed to high temperatures, and is able to maintain excellent heat resistance and insulating properties. Furthermore, in the composite material 1, the substrate 2 and the insulating coating 3 are in contact at room temperature, but when heated at high temperatures, a strong adhesive layer 8 is formed in which the components of the substrate 2 and the insulating coating 3 fuse together. Therefore, if a flame breaks out near the composite material 1, the insulating coating 3 is prevented from immediately peeling off from the substrate 2, thereby preventing the surface of the substrate 2 from being exposed, and the heat resistance and insulating properties provided by the insulating coating 3 can be maintained.

[0035] The insulating coating 3, the substrate 2, the adhesive layer 8, the surface layer 4, and the like of the composite member 1 according to this embodiment will be described in detail below.

[0036] <Insulating Coating> The insulating coating 3 has a matrix 10 containing a compound having a siloxane bond and an inorganic material 20 dispersed in this matrix 10. Both the compound having a siloxane bond and the inorganic material 20 are materials with excellent heat resistance and insulating properties, and therefore, when the compound having a siloxane bond and the inorganic material 20 are included as components of the insulating coating 3, an insulating coating with excellent heat resistance and insulating properties can be obtained. Furthermore, a plurality of pores 30 are formed inside the insulating coating 3.

[0037] Examples of compounds having a siloxane bond (Si—O—Si bond) include silicone and silica sol (silica: SiO ２ From the viewpoint of excellent heat resistance and insulating properties, the compound having a siloxane bond contained in the matrix 10 is preferably at least one of silicone and silica sol, and more preferably silicone. It is also a preferred embodiment that the matrix 10 contains both silicone and silica sol.

[0038] In this embodiment, it is preferable that the thickness of the insulating coating 3 is appropriately defined as follows.

[0039] (Thickness of the Insulating Coating) When the thickness of the insulating coating 3 is 150 μm or more, the strength of the insulating coating 3 can be ensured and peeling can be suppressed, thereby achieving the desired insulating properties. Therefore, the thickness of the insulating coating 3 is preferably 150 μm or more, and more preferably 200 μm or more. On the other hand, the thicker the insulating coating 3, the stronger the insulating coating 3, so there is no particular upper limit to the thickness. However, if the thickness is too thick, it becomes difficult to control the size of the composite member 1 and the manufacturing cost increases. Furthermore, peeling is more likely to occur. Therefore, the thickness of the insulating coating 3 is preferably 800 μm or less, and more preferably 600 μm or less.

[0040] The material that constitutes the insulating coating in the composite material 1 according to this embodiment will be described in further detail below.

[0041] (Compound having siloxane bonds: silicone) Silicone, which is a suitable example of a compound having siloxane bonds and is contained in the matrix 10 of the insulating coating 3, is heated in the curing step of the coating material in the manufacturing method described below, whereby functional groups disappear and SiO bonds are generated. Furthermore, if a fire or the like occurs near the composite member and the insulating coating is heated to a temperature of, for example, 700°C or higher, the silicone will be thermally decomposed to form SiO ２ is generated. Then, this SiO ２ Since the insulating coating 3 containing silicone is not burned even when exposed to flames, it can obtain excellent heat resistance. Silicone is classified into silicone resin and silicone rubber, and either one is acceptable, but the fact that it is silicone resin is important because the SiO ２ This is preferable from the viewpoint of increasing the density.

[0042] (Inorganic Material) Inorganic material 20 has a high melting point and excellent heat resistance, and therefore, including inorganic material 20 in insulating coating 3 can further improve the heat resistance of insulating coating 3. Furthermore, inorganic material 20 can also function as a skeleton in insulating coating 3, thereby improving the strength of insulating coating 3.

[0043] The inorganic material 20 preferably contains a silicate compound. As described above, silicone, which is an example of a compound having a siloxane bond, is thermally decomposed to form SiO ２ However, silicate compounds can be converted into SiO ２ Since the silicate compound has the same components as those of the silicone matrix 10, it is possible to improve the bonding strength between the silicone matrix 10 and the inorganic material 20. The silicate compound preferably contains at least one selected from glass-based materials, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth, and halloysite.

[0044] The main component of silica sol (silica), which is another suitable example of a compound having a siloxane bond, is SiO ２and the silicate compound is silica sol (SiO ２ ), the bonding strength between the matrix 10 containing silica sol (silica) and the inorganic material 20 can also be improved.

[0045] It is also preferable that the inorganic material 20 contains at least one selected from silica, alumina, mullite, and zirconia. These materials have high melting points and high insulating properties. Therefore, including these materials in the insulating coating 3 can further improve the heat resistance and insulating properties of the insulating coating 3. When a busbar is used as an example of the composite member of the present invention, the expected heat exposure temperature of the busbar is equal to or higher than the melting point of the metal material typically used in the body of a busbar. In this embodiment, including silica, alumina, mullite, zirconia, or the like as the inorganic material 20 can prevent the busbar body from being exposed to high heat because these materials have melting points equal to or higher than the heat exposure temperature. Therefore, these materials are suitable for use as materials for the insulating coating 3 of a busbar.

[0046] The shape of inorganic material 20 is preferably at least one selected from flakes, fibers, and particles. When inorganic material 20 has such a shape, the adhesive strength between inorganic material 20 and matrix 10 is increased when inorganic material 20 is dispersed in matrix 10, thereby improving the strength of insulating coating 3.

[0047] Furthermore, when the inorganic material 20 includes a glass-based material, the glass-based material preferably includes at least one selected from a flaky glass-based material, glass particles, and glass fibers. Among these, the flaky glass-based material is oriented planarly inside the insulating coating 3 and exhibits excellent insulating properties and heat resistance. Therefore, it is particularly preferable that the glass-based material includes a flaky glass-based material. Furthermore, for the same reasons as for the flaky glass-based material, mica is also preferably used as the inorganic material 20.

[0048] The content of inorganic material 20 relative to all components in insulating coating 3 is preferably 3 to 70 volume %, more preferably 10 to 50 volume %, and even more preferably 20 to 40 volume %. If the content of inorganic material 20 is less than 3 volume %, sufficient insulation and heat resistance may not be obtained. On the other hand, if the content exceeds 70 volume %, the viscosity of the coating liquid used for dip coating becomes too high, resulting in poor film formability.

[0049] In addition to the matrix 10 and inorganic material 20 described above, the insulating coating 3 may contain other materials such as a flame retardant, a dispersant, or a pigment, as long as the materials do not affect the insulating properties or heat resistance. As will be described later, the insulating coating 3 is formed by applying a coating material (coating liquid) to the surface of the substrate. In order to improve the application performance of the coating liquid containing the material of the matrix 10 and the inorganic material 20, it is preferable that the insulating coating 3 contain a thixotropic agent.

[0050] Furthermore, in this embodiment, the insulating coating 3 may include a coating other than the coating containing the inorganic material 20. Figure 5 is a photograph showing a composite member 1 according to another embodiment of the present invention. In the other embodiment shown in Figure 5, the same components as those shown in Figure 1 are designated by the same reference numerals, and detailed description thereof will be omitted or simplified. As shown in Figure 5, the composite member 1 includes a first coating 11 containing the material of the matrix 10 and the inorganic material 20, and a second coating 12 made of the material of the matrix 10, and the first coatings 11 and the second coatings 12 are stacked alternately in this order from the substrate 2 side.

[0051] Unlike the first coating 11, the second coating 12 does not contain the inorganic material 20, but is made of the material of the matrix 10. Therefore, high adhesion can be obtained between the first coating 11 and the second coating 12. Furthermore, the second coating 12 is a hard and dense layer, and the material of the matrix 10, which contains silicone (a compound having a siloxane bond), has excellent insulating properties. Therefore, when second coatings 12 having a dense structure made of the material of the matrix 10 are repeatedly stacked, even better insulating properties can be obtained.

[0052] <Substrate> In this embodiment, the substrate 2 is not particularly limited except that it is made of metal, and the main body of various products to which the composite material 1 according to this embodiment is applied can be used as the substrate 2. For example, when a bus bar, which will be described later, is applied as the composite material 1, a conductive bus bar body can be used as the substrate 2. Note that the bus bar body is conductive and the substrate itself is electrically conductive, but in this embodiment, the substrate 2 to be coated with the insulating coating 3 is not limited to being conductive. For example, a substrate made of a non-electrically conductive material can also be used.

[0053] <Adhesive Layer> In the composite member 1 according to this embodiment, the substrate 2 and the insulating coating 3 are in contact at room temperature, but when heated to a high temperature, an adhesive layer 8 is formed between the substrate 2 and the insulating coating 3. The adhesive layer 8 is formed by fusing a part of the substrate 2 with a part of the insulating coating 3 when the composite member 1 is heated in the presence of an oxide of the metal that constitutes the substrate 2, silicone that constitutes the matrix of the insulating coating 3, and an inorganic material. In other words, the adhesive layer 8 is formed when the composite member 1 is heated to a temperature equal to or higher than the oxidation start temperature of the metal that constitutes the substrate 2. Therefore, the obtained adhesive layer 8 contains the metal element contained in the substrate 2, the metal oxide of this metal element, the inorganic material 20, and at least one selected from silicone and silica. As will be described in detail later, when silicone is heated at high temperatures, silica (SiO ２ ) is generated, and therefore, depending on the heating temperature, the adhesive layer 8 may contain only silicone, may contain both silicone and silica, or may contain only silica.

[0054] When a copper substrate 2 is used, the temperature at which copper oxidation begins to progress significantly is approximately 400°C. Therefore, formation of the adhesive layer 8 begins when the substrate 2 is heated to a temperature of 400°C or higher in an environment where oxygen is present to oxidize the copper. Furthermore, when a copper substrate 2 is used, the components of the adhesive layer 8 preferably fall within the following ranges. That is, the adhesive layer 8 preferably contains 18% by mass to 22% by mass of oxygen, 5% by mass or less of magnesium, 5% by mass or less of aluminum, 8% by mass to 12% by mass of silicon, 5% by mass or less of potassium, and 50% by mass to 70% by mass of copper. Of the above components, magnesium, aluminum, and potassium are components derived from mica. Silicon is a component derived from mica or silicone. Oxygen is a component derived from silica, silicone, or mica. Copper is a component derived from the copper substrate used as the substrate.

[0055] Specifically, in the composite member 1 shown in Figures 2 to 4, a copper substrate is used as the substrate 2, mica is used as the inorganic material 20, and the carbon content in the adhesive layer relative to the total mass of the adhesive layer is 7.62 mass%, the oxygen content is 19.69 mass%, the magnesium content is 2.61 mass%, the aluminum content is 0.97 mass%, the silicon content is 9.63 mass%, the potassium content is 0.76 mass%, and the copper content is 54.47 mass%.

[0056] In this embodiment, the insulating coating 3 is formed by applying a coating material to the surface of the substrate 2 and then heating and curing the coating material. If the surface of the metal material constituting the substrate 2 is previously oxidized, the adhesive layer 8 may also be formed by heating to form the insulating coating 3. Therefore, the present invention also includes cases where the adhesive layer 8 is already formed at room temperature. That is, another embodiment of the present invention includes a composite member 1 having a metal substrate 2, an insulating coating 3 covering at least a portion of the surface of the substrate 2, and an adhesive layer 8 formed between the substrate 2 and the insulating coating 3, as shown in FIG. 3 . When the composite member 1 has the adhesive layer 8 at room temperature, the components contained in the adhesive layer 8 are the same as those described above. In this specification, room temperature refers to the temperature at which the composite member is normally used, such as 25°C.

[0057] In this embodiment, conditions for forming the adhesive layer 8 include heating at a predetermined temperature and oxidation of the metal constituting the substrate 2. Therefore, even if the composite member 1 is heated to a temperature equal to or higher than the oxidation onset temperature of the metal constituting the substrate 2, the desired adhesive layer 8 may not be formed if oxygen is not present on the surface of the substrate 2. Therefore, it is preferable that the pores 30 formed in the insulating coating 3 communicate with the outside of the composite member 1 and the surface of the substrate 2. Because FIG. 1 shows a cross section of the composite member 1, fine pores 30 appear to be scattered independently, but some pores 30 are actually connected from the outside of the composite member 1 to the surface of the substrate 2. The presence of pores 30 that are connected from the outside facilitates oxygen's access to the surface of the substrate 2, resulting in the formation of metal oxides, which facilitates the formation of the adhesive layer 8 upon heating.

[0058] <Surface Layer> The composite member 1 may have a surface layer 4 made of the material of the matrix 10 on at least a portion of the surface of the insulating coating 3. Like the second coating described above, the surface layer 4 does not contain the inorganic material 20 as in the insulating coating 3 and is made of only the material of the matrix 10. Therefore, the surface layer 4 has high adhesion to the insulating coating 3 and is harder and denser than the insulating coating 3, thereby providing the effect of protecting the surface of the insulating coating 3. Therefore, forming the surface layer 4 on at least a portion of the surface of the insulating coating 3 can suppress damage to the surface of the insulating coating 3 and cushion the impact of a colliding object. Furthermore, the formation of the surface layer 4 can also provide the effect of preventing powder shedding of the inorganic material 20, etc.

[0059] (Thickness of Surface Layer) When the composite material 1 has a surface layer 4, if the thickness of the surface layer 4 is 10 μm or more, the surface layer 4 can have the effect of protecting the insulating coating 3. Furthermore, if the thickness of the surface layer 4 is 100 μm or less, the size of the composite material 1 is not affected and an increase in manufacturing costs can be suppressed.

[0060] <Resin Layer> The composite material 1 may have a resin layer 7 (shown in FIG. 7D , which will be described later) on at least a portion of its surface. The resin layer 7 may be made of an insulating resin, such as epoxy resin, nylon resin, SBR (styrene butadiene rubber), or silicone rubber. The composite material 1 having the resin layer 7 can further improve its insulating properties and heat resistance. The resin layer 7 may be formed on the surface of the insulating coating 3 or on the surface layer 4.

[0061] (Thickness of Resin Layer) When the composite material 1 has a resin layer, if the thickness of the resin layer is 100 μm or more, the effect of improving insulation and heat resistance can be sufficiently obtained. Therefore, the thickness of the resin layer is preferably 100 μm or more, more preferably 120 μm or more, and even more preferably 150 μm or more. Furthermore, if the thickness of the resin layer is 600 μm or less, it does not affect the size of the composite material 1 and can also suppress an increase in manufacturing costs. Therefore, the thickness of the resin layer is preferably 600 μm or less, more preferably 550 μm or less, and even more preferably 500 μm or less.

[0062] [Specific Application Examples of the Composite Material] There are no particular limitations on the products to which the composite material 1 can be applied, but it can be applied, for example, to bus bars used to connect multiple battery cells or battery modules in an energy storage device. The configuration of the composite material 1 will be described below using a bus bar as an example.

[0063] FIG. 6 is a perspective view showing a busbar to which the composite member according to this embodiment is applied. Note that FIG. 6 shows the busbar (composite member) 100 in a state immediately before being attached to a battery cell 130. The busbar body (base material) 110 is, for example, a Z-shaped metal plate member. The busbar body is secured in place by inserting an electrode 135 of the battery cell 130 into a connection hole 115a at one end and covering it with a terminal cap 136. The busbar body 110 also has a connection hole 115b at the other end, which is used to connect an adjacent battery cell (not shown) or an external device (not shown). The busbar body 110 is covered with an insulating coating 3 throughout its entirety, excluding the connection holes 115a and 115b. This is how the busbar 100 is configured.

[0064] Although not shown in the figures, the busbar body 110 may be I-shaped overall or may have an irregular shape with curved portions, and may have various shapes depending on the installation location of the battery cell 130.

[0065] If the busbar body 110 has a shape with a bent portion 110a or a curved portion (not shown), such as the Z-shape shown in the figure, the following problems may occur. For example, in a method in which ceramic tape is wrapped around the body, as in the busbar disclosed in Patent Document 1, the wrapping process is time-consuming to prevent unevenness or gaps in the winding at the bent portion 110a or the curved portion. In addition, it is possible that gaps may occur in the ceramic tape due to vibration or the adhesive between the ceramic tape and the body may peel off.

[0066] In contrast, in the busbar 100 configured as described above, the busbar body 110 is not insulated by wrapping tape around it, but rather a material (coating liquid) for forming the insulating coating 3 is applied to the surface of the busbar body 110, forming the insulating coating 3 in close contact with the busbar body 110. Therefore, no wrapping operation is required when manufacturing the busbar 100, and there are no problems such as uneven winding, gaps, or peeling, and the busbar can easily be made into a complex shape.

[0067] Methods for applying the coating liquid to the surface of the busbar body 110 include "dip coating," in which the busbar body 110 is immersed in the coating liquid, and painting with a brush or spray. When dip coating is used, the insulating coating 3 is not formed on the connection holes 115a and 115b, so these areas are masked before being immersed in the coating liquid. In this way, the insulating coating 3 can be formed to cover at least a portion of the surface of the busbar body 110.

[0068] In addition to the bus bar, the composite member according to this embodiment can be applied to connectors, protective parts for battery modules, cases for electronic components, battery cells, battery modules, battery packs, or motor coils.

[0069] [Method for manufacturing composite member] The composite member shown in Figure 1 can be manufactured, for example, by the manufacturing method described below. Figures 7A to 7D are schematic diagrams showing the manufacturing method for a composite member according to an embodiment of the present invention in the order of steps. Note that, in the manufacturing method described below, a case where the compound having a siloxane bond contained in matrix 10 is silicone will be described, but the same can be applied to a case where the compound having a siloxane bond is silica sol (silica).

[0070] 7A , first, a first coating material (not shown) is applied to at least a portion of the surface of the substrate 2. The first coating material (coating liquid) is, for example, an organic solvent to which a silicone-containing matrix 10 material and an inorganic material 20 have been added.

[0071] (First Coating Material Drying Step) After the above-mentioned coating step, the first coating material is dried at a temperature of, for example, 50° C. In this first coating material drying step, the organic solvent is volatilized.

[0072] (First Coating Material Curing Step) The dried first coating material is then heated to a temperature of, for example, 200° C. to cure it. This first coating material curing step causes dehydration condensation of the silicone, forming the first layer 5 with a three-dimensional network structure. Numerous pores 30 are also formed in the first layer 5.

[0073] (First Immersion Process) The substrate 2 on which the first layer 5 has been formed is then immersed in a second coating material (not shown). The second coating material does not contain the inorganic material 20, but is an organic solvent to which the silicone-containing matrix 10 material has been added. The second coating material is then dried, for example, at a temperature of 50°C, and then heated, for example, at a temperature of 200°C to harden it. As shown in FIG. 7B , this immersion process fills some of the numerous pores 30 formed in the first layer 5 with the second coating material, thereby reducing the number of pores in the first layer 5. The second coating material may not contain the inorganic material 20 of the first coating material, or may be a material different from the material of the matrix 10.

[0074] 7C, a first coating material (not shown) is again laminated on the surface of the first layer 5. The first coating material (coating liquid) is the same material as that used in the first coating process. At this time, the first coating material also fills some of the pores 30 remaining in the first layer 5.

[0075] (Second drying step of the first coating material) After the above-mentioned coating step, the first coating material is dried at a temperature of, for example, 50° C. This second drying step of the first coating material volatilizes the organic solvent in the first coating material applied in the second coating step.

[0076] (Second First Coating Material Curing Process) The dried first coating material is then heated to a temperature of, for example, 200° C. and cured. This second first coating material curing process causes dehydration condensation of the silicone, forming a second layer 6 with a three-dimensional network structure. A large number of pores 30 are also formed in the second layer 6.

[0077] (Second Immersion Process) Then, as shown in FIG. 7D , the substrate 2 on which the second layer 6 has been formed is immersed in a second coating material (not shown). The second coating material is the same material as that used in the first immersion process. The second coating material is then dried, for example, at a temperature of 50°C, and then heated, for example, at a temperature of 200°C to harden it. This immersion process fills some of the numerous pores 30 formed in the second layer 6 with the second coating material, thereby reducing the number of pores in the second layer 6. The second coating material used in the second immersion process may not contain the inorganic material 20 of the first coating material, or may be a material different from the material of the matrix 10.

[0078] The immersion time in the second immersion step may be the same as that of the first immersion step, or may be longer than that of the first immersion step. The second coating material penetrates into the second layer 6 from the surface thereof, but if the second coating material remains on the surface of the second layer 6 due to the long immersion time, it hardens as it is, forming a surface layer 4 on the surface of the second layer 6. This surface layer 4 is made of the second coating material remaining on the surface, and therefore has a dense structure that does not contain inorganic material 20.

[0079] (Resin Layer Forming Step) Thereafter, the resin layer 7 is formed on the surface layer 4 by, for example, electrostatic powder coating or fluidized bed dip coating of an epoxy resin paint. When forming the resin layer 7, the material constituting the resin layer 7 may permeate into the insulating coating 3.

[0080] 7A to 7D are merely examples, and the manufacturing method is not particularly limited as long as an adhesive layer is formed between the substrate 2 and the insulating coating 3 when the substrate 2 is heated to or above the oxidation onset temperature of the metal constituting the substrate 2, or a composite member having a pre-existing adhesive layer is formed. For example, the first immersion step of the second coating material, the second deposition step of the first coating material, and the second immersion step of the second coating material may be omitted. Furthermore, the deposition step and the immersion step may be repeated three or more times. Although not shown, an adhesive layer may also be formed between the substrate 2 and the insulating coating 3 at this point.

[0081] Furthermore, a composite member having the structure shown in FIG. 5 can be manufactured, for example, by the manufacturing method described below. FIGS. 8A to 8D are schematic diagrams showing the manufacturing method of a composite member according to another embodiment of the present invention in the order of steps. In FIGS. 8A to 8D, the same components as those shown in FIGS. 7A to 7D above are designated by the same reference numerals, and detailed descriptions thereof will be omitted or simplified. However, for ease of explanation, in FIGS. 8A to 8D, the reference numerals for the first and third first coating layers, counting in the order of lamination from the substrate 2, are distinguished. Furthermore, the reference numerals for the second and fourth second coating layers are distinguished.

[0082] <Formation of First Layer> (First Coating Step) As shown in FIG. 8A , first, a material for a first coating (first coating material) (not shown) is applied to at least a part of the surface of the substrate 2 .

[0083] (First Coating Material Drying Step) After the above-mentioned coating step, the first coating material is dried at a temperature of, for example, 50° C. In this first coating material drying step, the organic solvent is volatilized.

[0084] (First Coating Material Curing Step) The dried first coating material is then heated to a temperature of, for example, 200° C. and cured. This first coating material curing step causes dehydration condensation of the silicone, forming the first coating 11 a with a three-dimensional network structure. At this point, numerous pores 30 are formed in the first coating 11 a.

[0085] <Formation of Second Layer> (First Immersion Step) The substrate 2 on which the first coating 11a is formed is then immersed in a material for a second coating (not shown). The second coating material does not contain the inorganic material 20, but is an organic solvent to which the silicone-containing matrix 10 material has been added. As shown in FIG. 8B , this immersion step fills some of the numerous pores 30 formed in the first coating 11a with the second coating material, thereby reducing the number of pores in the first coating 11a. Furthermore, excess second coating material not absorbed into the pores 30 remains on the surface of the first coating 11a. The second coating material is then dried, for example, at 50°C, and then heated, for example, at 200°C to harden it. This results in a second coating 12a made of the silicone-containing matrix 10 material being formed on the surface of the first coating 11a. The obtained second coating 12 a is made of the second coating material remaining on the surface, and therefore has a dense structure that does not contain inorganic material 20 .

[0086] <Formation of Third Layer> (Second Coating Process) Then, as shown in Fig. 8C, the first coating material is again laminated on the surface of the second coating 12a. This first coating material is the same material as that used in the first coating process.

[0087] (First Coating Material Drying Step: Second Time) After the second coating step, the first coating material is dried, for example, at a temperature of 50° C. This second first coating material drying step volatilizes the organic solvent in the first coating material applied in the second coating step.

[0088] (Second First Coating Material Curing Process) The dried first coating material is then heated to a temperature of, for example, 200° C. and cured. This second first coating material curing process causes dehydration condensation of the silicone, resulting in the formation of a first coating 11 b with a three-dimensional network structure. At this point, numerous pores 30 are formed in the first coating 11 b.

[0089] <Formation of the Fourth Layer> (Second Dipping Process) Then, as shown in FIG. 8D , the substrate 2 on which the first coating 11b is formed is immersed in a second coating material. The second coating material is the same material as that used in the first immersion process. This second immersion process fills some of the numerous pores 30 formed in the first coating 11b with the second coating material, thereby reducing the number of pores in the first coating 11b. Furthermore, any second coating material not absorbed into the pores 30 remains on the surface of the first coating 11b. The second coating material is then dried, for example, at 50°C, and then heated, for example, at 200°C to harden it. This forms a second coating 12b (surface layer) on the surface of the first coating 11b, made of the silicone-containing matrix 10 material. Like second coating 12a, second coating 12b is made of a second coating material that does not contain inorganic material 20, and therefore is made of only the matrix material and has a dense structure. Therefore, by including second coatings 12a and 12b in insulating coating 3, the insulating properties can be further improved.

[0090] Whether or not the second coating 12a is formed is determined by conditions such as the immersion time when the substrate 2 on which the first coating 11a is formed is immersed in the second coating material. In the above-described manufacturing method, the immersion conditions in the first immersion step and the second immersion step are not particularly limited. When it is desired to form the second coatings 12a and 12b, it is preferable to adjust the immersion conditions so that excess second coating material remains on the surfaces of the first coatings 11a and 11b and the second coatings 12a and 12b are formed.

[0091] The resin layer 7 may or may not be formed, and the method for forming it is as described above.

[0092] In the above-described manufacturing method, the series of steps from the deposition step to the immersion step was repeated twice, but this may be repeated multiple times until the desired film thickness is achieved. If the series of steps is repeated three or more times, the thickness of the second coating made of the second coating material increases, thereby forming an insulating coating 3 with even higher insulating properties.

[0093] Furthermore, in the above-described manufacturing method, the first coating material (coating liquid) is an organic solvent to which a silicone-containing matrix 10 material and an inorganic material 20 have been added, and the second coating material (coating liquid) does not contain the inorganic material 20 and is an organic solvent to which a silicone-containing matrix 10 material has been added. However, depending on the types of the first coating material and the second coating material, such as silica sol (silica), the composite member of the present invention can be obtained without performing the above-described immersion step.

[0094] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0095] This application is based on a Japanese patent application (Patent Application No. 2023-170685) filed on September 29, 2023, the contents of which are incorporated herein by reference.

[0096] REFERENCE SIGNS LIST 1 composite member 2 substrate 3 insulating coating 4 surface layer 5 first layer 6 second layer 7 resin layer 8 adhesive layer 10 matrix 11, 11a, 11b first coating 12, 12a, 12b second coating 20 inorganic material 30 pores 100 busbar 110 busbar body 110a bent portion 130 battery cell

Claims

1. A composite member having a metal substrate and an insulating coating covering at least a portion of the surface of the substrate, wherein the insulating coating has a matrix containing a compound having a siloxane bond and an inorganic material dispersed in the matrix, wherein the substrate and the insulating coating are in contact at room temperature, and when the substrate is heated to a temperature equal to or higher than the oxidation start temperature of the metal constituting the substrate, an adhesive layer is formed between the substrate and the insulating coating, wherein the adhesive layer comprises a metal element contained in the substrate, a metal oxide of the metal element, the inorganic material, and at least one selected from silicone and silica.

2. A composite member having a metal substrate, an insulating coating covering at least a portion of the surface of the substrate, and an adhesive layer formed between the substrate and the insulating coating, wherein the insulating coating has a matrix containing a compound having a siloxane bond and an inorganic material dispersed in the matrix, and the adhesive layer has a metal element contained in the substrate, a metal oxide of the metal element, the inorganic material, and at least one selected from silicone and silica.

3. A composite material according to claim 1 or 2, characterized in that the insulating coating has pores connecting the outside and the surface of the base material.

4. A composite material as set forth in claim 1 or 2, characterized in that the insulating coating has a thickness of 150 μm or more.

5. A composite member according to claim 1 or 2, characterized in that at least a portion of the surface of said insulating coating has a surface layer made of the material of said matrix.

6. The composite material according to claim 5, wherein the thickness of the surface layer is 10 μm or more and 100 μm or less.

7. A composite member as described in claim 1 or 2, characterized in that the insulating coating comprises a first coating containing the matrix and the inorganic material, and a second coating made of the material of the matrix, and the first coating and the second coating are laminated alternately in this order multiple times from the substrate side.

8. The composite material according to claim 7, wherein the thickness of each of the second coatings is 10 μm or more and 100 μm or less.

9. The composite member according to claim 1 or 2, characterized in that at least a portion of the surface of the insulating coating has a resin layer containing a resin different from the material of the matrix.

10. The composite material according to claim 9, wherein the thickness of the resin layer is 100 μm or more and 600 μm or less.

11. The composite member according to claim 1 or 2, wherein the compound having a siloxane bond is at least one of silicone and silica sol.

12. The composite member according to claim 1 or 2, characterized in that the inorganic material contains at least one selected from the group consisting of silica, alumina, mullite and zirconia.

13. The composite member according to claim 1 or 2, characterized in that the inorganic material comprises at least one selected from glass-based materials, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth and halloysite.

14. The composite member described in claim 13, characterized in that the adhesive layer contains 18% by mass or more and 22% by mass or less of oxygen, 5% by mass or less of magnesium, 5% by mass or less of aluminum, 8% by mass or more and 12% by mass or less of silicon, 5% by mass or less of potassium, and 50% by mass or more and 70% by mass or less of copper.

15. The composite member according to claim 1 or 2, characterized in that the inorganic material contains at least one type selected from the group consisting of flake-shaped, fibrous and particulate-shaped inorganic materials.

16. The composite member according to claim 1 or 2, characterized in that the inorganic material includes at least one of a flake-like glass-based material and mica.

17. The composite member according to claim 1 or 2, characterized in that the substrate is a bus bar that connects a plurality of battery cells or battery modules.

18. The composite member according to claim 1 or 2, characterized in that the substrate is a connector, a protective part for a battery module, a case for an electronic component, a battery cell, a battery module, a battery pack, or a coil for a motor.

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