Composite member, method for manufacturing same, and power storage device

Abstract

Provided is a composite member having an insulation film that is capable of maintaining excellent insulation and heat resistance for a long period of time, does not require operation such as winding a tape or the like, and is free from problems such as occurrence of winding unevenness or a gap and detachment. A composite member (1) has a base material (2) and an insulation film (3) covering at least a portion of the surface of the base material (2). The insulation film (3) has: an inner layer (4) comprising a first film material which has a matrix (8) including a compound having a siloxane bond and an inorganic material (9) dispersed in the matrix (8) and having a squamous, plate, flake, or fibrous shape; and an outer layer (5) comprising a second film material which has a matrix (8) including a compound having a siloxane bond and an inorganic material dispersed in the matrix (8) and having a squamous, plate, flake, or fibrous shape. In the inner layer (4) and the outer layer (5), the respective alignments of the inorganic materials (9) with respect to the surface of the base material (2) are different from each other.

Description

Composite member, manufacturing method thereof, and power storage device

[0001] The present invention relates to a composite member in which a substrate is coated with an insulating film, and a manufacturing method thereof.The present invention also relates to an electricity storage device in which a plurality of battery cells or battery modules are connected by a composite member.

[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] During charging and discharging, an overcurrent flows through a battery cell, which can cause the busbar to heat up and, in some cases, even cause a fire. Therefore, busbars are required to have both insulation and heat resistance. For example, Patent Document 1 describes a busbar in which a ceramic tape, such as mica tape, is wrapped around a copper busbar body as a fire-resistant layer. Patent Document 2 also describes a busbar in which copper sleeves are fixed to both ends of an aluminum body, and the surface is further coated with an insulating layer.

[0004] Chinese Utility Model No. 216902355 Chinese Utility Model No. 218731641

[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.

[0006] Furthermore, busbars with a dip-coated insulating layer, as in Patent Document 2, have the advantage of eliminating the need for wrapping ceramic tape and being easily adaptable to busbars with complex shapes, but because the film thickness is thinner at the corners of the busbar (see FIG. 1), the corners are prone to damage and insulation failure. While it is possible to increase the film thickness at the corners by repeating dip coating, this would result in an unnecessarily thick film thickness on the flat surface of the busbar and would increase the amount of paint required to form the insulating layer, thereby increasing manufacturing costs.

[0007] Therefore, the present invention provides a composite member having an insulating coating that does not require winding work like ceramic tape, is free from problems such as uneven winding, gaps, or peeling, has sufficient film thickness at corners, and exhibits excellent insulation and heat resistance even when the composite member has a complex shape, as well as a manufacturing method that can easily manufacture the insulating coating.

[0008] The above object of the present invention is achieved by the following configuration [1] relating to a composite member.

[0009] [1] A composite member having a substrate and an insulating coating covering at least a portion of the surface of the substrate, wherein the insulating coating has: an inner layer made of a first coating material having a matrix containing a compound having a siloxane bond and a scale-like, flat, flake-like, or fibrous inorganic material dispersed in the matrix; and an outer layer made of a second coating material having a matrix containing a compound having a siloxane bond and a scale-like, flat, flake-like, or fibrous inorganic material dispersed in the matrix, wherein the orientation of the inorganic material with respect to the surface of the substrate differs between the inner layer and the outer layer.

[0010] Furthermore, preferred embodiments of the present invention relating to the composite member relate to the following [2] to

[15] .

[0011] [2] The composite member according to [1], wherein the inorganic material in the inner layer has a higher orientation than the inorganic material in the outer layer. [3] The composite member according to [2], wherein the inner layer contains 60 to 100% inorganic material oriented at an angle of 0 to 10 degrees with respect to a direction parallel to the surface of the substrate, and the outer layer contains 10 to 80% inorganic material oriented at an angle of 0 to 10 degrees with respect to a direction parallel to the surface of the substrate. [4] The composite member according to any one of [1] to [3], wherein the substrate has a pair of opposing main surfaces, a plurality of end surfaces connecting the main surfaces, and corners between the main surfaces and the end surfaces, and at least a portion of the insulating coating surrounds the corners of the substrate. [5] The composite member according to [4], wherein at least a portion of the insulating coating further surrounds the end surfaces of the substrate. [6] The composite member according to [4] or [5], wherein the outer surface of the insulating coating formed on the corner of the substrate has a cross-sectional shape that follows the corner of the substrate and has an R-shape. [7] The composite member according to any one of [1] to [6], wherein the inner layer and the outer layer have the same composition. [8] The composite member according to any one of [1] to [6], wherein the inner layer and the outer layer have different compositions. [9] The composite member according to any one of [1] to [8], wherein the compound having a siloxane bond contained in the first coating material and / or the second coating material is at least one of silicone and silica sol.

[10] The composite member according to any one of [1] to [9], wherein the inorganic material includes at least one selected from silica, alumina, mullite, zirconia, and calcium carbonate.

[11] The composite member according to any one of [1] to [9], 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.

[12] The composite member according to any one of [1] to [9], wherein the inorganic material comprises at least one of a glass flake material and mica.

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

[12] , wherein at least one of the inner layer and the outer layer is impregnated with a matrix material containing the compound having a siloxane bond.

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

[13] , wherein at least the portion of the substrate where the inner layer is to be formed has a rough surface.

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

[14] , wherein the outermost surface has a resin layer made of a resin different from the resins contained in the first coating material and the second coating material.

[0012] The above object of the present invention is achieved by the following configuration

[16] relating to a method for producing a composite member.

[0013]

[16] A method for producing a composite member according to any one of [1] to

[15] , comprising: an inner layer forming step of applying a coating material containing a first coating material, the first coating material having a matrix material containing a compound having a siloxane bond and a scale-like, flat, flake-like, or fibrous inorganic material, to at least a portion of the surface of the substrate, and curing the coating material; and an outer layer forming step of applying a coating material containing a second coating material, the second coating material having a matrix material containing a compound having a siloxane bond and a scale-like, flat, flake-like, or fibrous inorganic material, to at least a portion of the surface of the inner layer, by a coating method different from that used in the inner layer forming step, and curing the coating material.

[0014] Furthermore, preferred embodiments of the present invention relating to a method for manufacturing a composite member relate to the following

[17] to

[23] .

[0015]

[17] The method for producing a composite member according to

[16] , wherein the coating method in the inner layer forming step is dip coating, brush coating, spray coating, or dispenser coating, and the coating method in the outer layer forming step is dip coating, brush coating, or dispenser coating.

[18] The method for producing a composite member according to

[16] or

[17] , wherein the first coating material and the second coating material have the same composition.

[19] The method for producing a composite member according to

[16] or

[17] , wherein the first coating material and the second coating material have different compositions.

[20] The method for producing a composite member according to any one of

[16] to

[19] , wherein the compound having a siloxane bond contained in the first coating material and / or the second coating material is at least one of silicone and silica sol.

[21] The method for producing a composite member according to any one of

[16] to

[20] , characterized in that it comprises an impregnation step of immersing a matrix material containing a compound having a siloxane bond after at least one of the inner layer formation step and the outer layer formation step.

[22] The method for producing a composite member according to any one of

[16] to

[21] , characterized in that it comprises a surface roughening step of roughening the surface of the substrate.

[23] The method for producing a composite member according to any one of

[16] to

[22] , characterized in that it comprises a resin layer formation step of applying to the outermost surface a resin material containing a resin different from the resins contained in the first coating material and the second coating material, and curing the resin material.

[0016] The above object of the present invention is achieved by the following configuration

[24] relating to the electricity storage device.

[0017]

[24] A power storage device, characterized in that a plurality of battery cells or battery modules are connected by the composite member according to any one of [1] to

[15] .

[0018] The composite member of the present invention has a sufficiently thick insulating coating at the corners, allowing it to be adapted to complex shapes. Furthermore, the insulating coating has inner and outer layers with different orientations of the inorganic material, and therefore possesses properties derived from the differences in orientation. For example, if the orientation of the inorganic material in the inner layer is higher than that in the outer layer, the inner layer will have improved insulation and heat resistance, and the outer layer will have improved resistance to external impacts, allowing insulation and heat resistance to be maintained for a long period of time.

[0019] Furthermore, the method for manufacturing a composite member of the present invention does not require wrapping work such as with ceramic tape, and there are no problems such as uneven wrapping, gaps, or peeling. It is possible to make the insulating coating at the corners sufficiently thick, and it can easily accommodate complex shapes.

[0020] Furthermore, the energy storage device of the present invention has sufficient film thickness at the corners and connects multiple battery cells or battery modules using a composite material with excellent insulating and heat resistance properties, so safety can be maintained for a long period of time.

[0021] FIG. 1 is a photograph, in lieu of a drawing, of a cross section of a composite member of the present invention, showing a state after an inner layer has been formed. FIG. 2 is a photograph, in lieu of a drawing, of a cross section of a composite member of the present invention, showing a state after an outer layer has been formed on the inner layer. FIG. 3A is an SEM photograph of a cross section of an insulating coating at the end surface of the composite member shown in FIG. 2. FIG. 3B is an enlarged view of portion A in FIG. 3A. FIG. 3C is an enlarged view of portion B in FIG. 3A. FIG. 4A is an SEM photograph of a cross section of an insulating coating at the end surface of a substrate, showing the cross section of the insulating coating before impregnation treatment. FIG. 4B is an SEM photograph of a cross section of an insulating coating at the end surface of a substrate, showing the cross section of the insulating coating impregnated after the formation of the inner and outer layers. FIG. 4C is an SEM photograph of a cross section of an insulating coating at the end surface of a substrate, showing the cross section of the insulating coating after the inner layer has been impregnated and the outer layer has been formed. FIG. 4D is an SEM photograph of a cross section of an insulating coating at an end surface of a substrate, showing a cross section of an insulating coating in which an outer layer is formed on an impregnated inner layer and the outer layer is also impregnated. FIG. 5A is an SEM photograph of a cross section of an insulating coating at a corner of a substrate, showing the cross section of the insulating coating before impregnation. FIG. 5B is an SEM photograph of a cross section of an insulating coating at a corner of a substrate, showing the cross section of an insulating coating impregnated after forming the inner and outer layers. FIG. 5C is an SEM photograph of a cross section of an insulating coating at a corner of a substrate, showing the cross section of an insulating coating in which the outer layer is formed after impregnation of the inner layer. FIG. 5D is an SEM photograph of a cross section of an insulating coating at a corner of a substrate, showing the cross section of an insulating coating in which the outer layer is formed on an impregnated inner layer and the outer layer is also impregnated. FIG. 6 is a perspective view showing a bus bar as an example of a composite member. FIG. 7 is a schematic diagram showing a battery pack including the bus bar shown in FIG. 6 as an example of the power storage device of the present invention.

[0022] The inventors of the present invention have conducted extensive research to find a solution to the problem of thin insulating coating thickness at corners, which does not require the wrapping of insulating tape such as ceramic tape, can be applied to complex shapes, and has found that it is effective to form an inner layer made of a first coating material, and then form an outer layer made of a second coating material at the corners where the thickness is thin, using a coating method different from the coating method used to apply the first coating material.

[0023] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiment described below, and can be implemented with any modifications within the scope of the gist of the present invention.

[0024] 1 and 2 are photographs showing a composite member 1 of this embodiment along the thickness direction of a substrate 2, with an insulating coating 3 formed on at least a portion of the substrate 2. The insulating coating 3 is composed of an inner layer 4 and an outer layer 5, in that order from the side closest to the substrate 2. Fig. 1 shows a state where the inner layer 4 has been formed, and Fig. 2 shows a state where the outer layer 5 has been formed on the inner layer 4.

[0025] The substrate 2 has a pair of opposing main surface portions 2 a, 2 a, a plurality of end surface portions 2 b connecting the main surface portions 2 a, and corner portions 2 c between the main surface portions 2 a and the end surface portions 2 b, and as shown in the figure, the corner portions 2 c may have a rounded cross section. That is, the outer surface of the insulating coating 3 formed on the corner portions 2 c of the substrate 2 has a rounded cross section that follows the corner portions 2 c of the substrate 2.

[0026] Furthermore, the substrate 2 may be roughened by blasting or the like to improve adhesion to the inner layer 4. The degree of roughening is preferably such that the surface roughness Ra in accordance with JIS B 0031 is 1 μm or more, more preferably 2 μm or more. The surface roughness Ra represents the average value of the surface roughness measured at any three points on the surface of the substrate 2.

[0027] In this embodiment, the inner layer 4 is formed on each of the main surface portion 2 a , the end surface portion 2 b , and the corner portion 2 c of the substrate 2 .

[0028] The inner layer 4 is a layer having a matrix 8 containing a compound having a siloxane bond, a suitable example of which is silicone, and a scale-like, flat, flake-like, or fibrous inorganic material 9 dispersed in the matrix 8. As will be described later, the inner layer 4 is a layer obtained by applying and curing a first coating material having a matrix material containing a compound having a siloxane bond, a suitable example of which is silicone, and the scale-like, flat, flake-like, or fibrous inorganic material 9.

[0029] However, the thickness of the inner layer 4 at the end surface 2b and corners 2c of the substrate 2, especially at the corners 2c, is thinner than the thickness of the inner layer 4 at the main surface 2a, which raises concerns that the insulation and heat resistance may be insufficient. Therefore, as shown in Figure 2, an outer layer 5 is formed to surround the inner layer 4 at the end surface 2b and corners 2c of the substrate 2.

[0030] The outer layer 5 is a layer having a matrix 8 containing a compound having a siloxane bond, a suitable example of which is silicone, and a scale-like, flat, flake-like, or fibrous inorganic material 9 dispersed in the matrix 8. As will be described later, the outer layer 5 is a layer obtained by applying and curing a second coating material having a matrix material containing a compound having a siloxane bond, a suitable example of which is silicone, and the scale-like, flat, flake-like, or fibrous inorganic material 9.

[0031] Both the compound having a siloxane bond and the inorganic material 9 are materials with excellent heat resistance and insulating properties. Therefore, when the compound having a siloxane bond and the inorganic material 9 are contained as components in the matrix 8 in the inner layer 4 or the outer layer 5, an insulating coating (the inner layer 4 or the outer layer 5) can be obtained that has excellent heat resistance and insulating properties.

[0032] Compounds having a siloxane bond (Si—O—Si bond) include silicone and silica sol (silica: SiO ２From the viewpoint of excellent heat resistance and insulating properties, the compound having a siloxane bond contained in the matrix 8 in the inner layer 4 (first coating material) or the outer layer 5 (second coating material) is preferably at least one of silicone and silica sol, and more preferably silicone. In addition, it is also a preferred embodiment that the matrix 8 in the inner layer 4 (first coating material) or the outer layer 5 (second coating material) contains both silicone and silica sol.

[0033] 3A is an SEM photograph of a cross section of the insulating coating 3 at the end surface 2b of the substrate 2. The end surface 2b of the substrate 2 is at the bottom of the photograph, with the inner layer 4 and outer layer 5 formed thereon. The white lines in the photograph represent the inorganic material 9, which is scale-like, flat, flake-like, or fibrous, and therefore appears as a line in cross section. The gray areas in the photograph are the matrix 8, which surrounds the inorganic material 9. The black areas in the photograph are pores 10.

[0034] 3B is an enlarged view of portion A of the inner layer 4 in FIG. 3A, and FIG. 3C is an enlarged view of portion B of the outer layer 5 in FIG. 3A. As shown in FIG. 3B, in the inner layer 4, the inorganic material 9 is generally aligned substantially parallel to the surface of the substrate 2 (here, the end surface portion 2b), and the inorganic material 9 is in a state of "high orientation." In contrast, in the outer layer 5, as shown in FIG. 3C, the inclination angle of the inorganic material 9 with respect to the surface of the substrate 2 varies, and the inorganic material 9 is in a state of "low orientation."

[0035] As described above, in the composite member 1 of this embodiment, the insulating coating 3 is composed of an inner layer 4 and an outer layer 5, and is characterized in that the orientation of the inorganic material 9 differs between the inner layer 4 and the outer layer 5. This is due to the different coating methods used for the first coating material for forming the inner layer 4 and the second coating material for forming the outer layer 5, as will be explained in the manufacturing method described later.

[0036] If the orientation of the inorganic material 9 is different, the orientation may be low in the inner layer 4 and high in the outer layer 5, as opposed to the above, but if the orientation of the inorganic material 9 is uniform, the insulating properties will be high, while if the orientation of the inorganic material 9 is not uniform, the strength against external impact will be high. Therefore, by increasing the orientation of the inorganic material 9 in the inner layer 4 and decreasing it in the outer layer 5 as described above, the electrical properties will be high and damage to the insulating coating 3 and peeling from the substrate 2 when the composite members 1 come into contact with each other or with other parts can be suppressed, which is preferable.

[0037] Furthermore, as described above, when the orientation of the inorganic material 9 in the inner layer 4 is higher than the orientation of the inorganic material 9 in the outer layer 5, it is particularly preferable that the inner layer 4 contains 60 to 100% of the inorganic material 9 oriented at an angle of 0 to 10 degrees with respect to the direction parallel to the surface of the substrate 2, and the outer layer 5 contains 10 to 80% of the inorganic material 9 oriented at an angle of 0 to 10 degrees with respect to the direction parallel to the surface of the substrate 2, in terms of high electrical properties and more effectively suppressing damage to the insulating coating 3 and peeling from the substrate 2 when the composite members 1 come into contact with each other or with other components.

[0038] There are no limitations on the film thickness of the inner layer 4 and the outer layer 5, but the inner layer 4 is preferably 100 to 800 μm on the main surface 2 a of the substrate 2 and 30 to 400 μm on the end surface 2 b and corners 2 c of the substrate 2. The outer layer 5 is preferably 0 to 400 μm on the main surface 2 a of the substrate 2 and 50 to 800 μm on the end surface 2 b and corners 2 c of the substrate 2.

[0039] Furthermore, as shown in Figures 3A to 3C, the insulating coating 3 is dotted with pores 10, which raises concerns about reduced insulation, heat resistance, and film strength. Therefore, the inner layer 4 and outer layer 5 are impregnated with a matrix material containing a compound with a siloxane bond, of which silicone is a suitable example. Compounds with siloxane bonds, particularly silicone, have excellent insulation and heat resistance, and by flowing into and filling the pores 10, the insulating properties and heat resistance are improved, and the film is densified, resulting in increased film strength. While the impregnation may be performed on only the inner layer 4 or only the outer layer 5, it is preferable to perform the impregnation on both the inner layer 4 and the outer layer 5.

[0040] 4A to 4D are SEM photographs showing a cross section of the insulating coating 3 at the end surface 2b of the substrate 2. FIG. 4A shows a cross section of the insulating coating 3 before impregnation. Both the inner layer 4 and the outer layer 5 have numerous pores 10, shown in black in the figure. In contrast, as shown in FIG. 4B, when the inner layer 4 and the outer layer 5 are formed and then impregnated with a matrix material containing silicone (a compound having a siloxane bond), the pores 10 in the outer layer 5 are primarily filled with the matrix material containing silicone, resulting in fewer pores 10. Furthermore, as shown in FIG. 4C, when the inner layer 4 is formed and then impregnated with a matrix material containing silicone, the number of pores 10 in the inner layer 4 is reduced. Furthermore, as shown in FIG. 4D, when the outer layer 5 is formed on the inner layer 4 impregnated with a matrix material containing silicone, and the outer layer 5 is also impregnated with a matrix material containing silicone, the number of pores 10 in both the inner layer 4 and the outer layer 5 is reduced.

[0041] The same is true for the cross section of the insulating coating 3 at the corner 2c. Fig. 5A shows a cross section of the insulating coating 3 before impregnation, showing numerous pores 10 scattered throughout both the inner layer 4 and the outer layer 5. In contrast, as shown in Fig. 5B, when the inner layer 4 and the outer layer 5 are formed and then impregnated with a silicone-containing matrix material, the pores 10 in the outer layer 5 are primarily filled with the silicone-containing matrix material, resulting in fewer pores 10. Furthermore, as shown in Fig. 5C, when the inner layer 4 is formed and then impregnated with a silicone-containing matrix material, the number of pores 10 in the inner layer 4 is reduced. Furthermore, as shown in Fig. 5D, when the outer layer 5 is formed on the inner layer 4 impregnated with a silicone-containing matrix material and then the outer layer 5 is also impregnated with a silicone-containing matrix material, the number of pores 10 in both the inner layer 4 and the outer layer 5 is reduced.

[0042] Although not shown in the figures, the inner layer 4 and the outer layer 5 may be surrounded by a resin layer if necessary. This resin layer is made of a resin different from the resin contained in the inner layer 4 and the outer layer 5, and further enhances the insulation properties, heat resistance, and impact resistance of the insulating coating 3. To achieve these effects, 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 increases 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.

[0043] The composite material 1 has the above-described configuration. Preferred materials for the substrate 2, inner layer 4, outer layer 5, and resin layer are exemplified below.

[0044] (Substrate 2) The main body of various products to which the composite material 1 is applied can be used as the substrate 2. For example, when a bus bar 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 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.

[0045] (Inner layer 4) The inner layer 4 is made of a first coating material containing a matrix 8 containing a compound having a siloxane bond and a scale-like, flat, flake-like, or fibrous inorganic material 9. Silicone, which is a suitable example of a compound having a siloxane bond, is heated when curing the first coating material in the manufacturing method described below. The heating causes the functional groups to disappear and SiO bonds to form. Furthermore, if a fire or the like occurs near the composite member 1 and the insulating coating 3 is heated to a temperature of, for example, 700°C or higher, the silicone will thermally decompose to form SiO ２ The produced SiO ２Since the inner layer 4 containing silicone is not burned even when exposed to a flame, it can obtain excellent heat resistance and will not peel off from the substrate 2. Silicone is classified into silicone resin and silicone rubber, and either may be used, but selecting silicone resin is preferable because it reduces the amount of SiO formed. ２ This is preferable from the viewpoint of increasing the density.

[0046] The matrix 8 may be composed of silicone alone, or may contain other materials such as a flame retardant, a dispersant, a pigment, etc., as long as the insulating properties and heat resistance are not affected. In addition, it is preferable that the matrix 8 contains a thixotropic agent to improve the application performance of the first coating material.

[0047] (Inorganic Material 9) The inorganic material 9 contained in the first coating material has an aspect ratio of, for example, 10 or more, and therefore must have a scale-like, plate-like, flake-like, or fibrous appearance, a high melting point, and excellent heat resistance. It also contributes to the skeleton of the inner layer 4 (and also contributes to the skeleton of the outer layer 5, described below). In this embodiment, the "aspect ratio" refers to the ratio (b / a) of the major axis b of a substance to the minor axis a, and indicates the average value of the numerous inorganic materials (particles) present in the inner layer 4 or outer layer 5. To maximize the effects of the present invention, the aspect ratio is preferably 15 or more, and more preferably 20 or more.

[0048] As a specific material name, silicate compounds are preferred. As described above, silicone, which is an example of a compound having a siloxane bond, is converted into 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 8, it is possible to improve the bonding strength between the silicone matrix 8 and the inorganic material 9. The silicate compound is preferably at least one selected from glass-based materials, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth, and halloysite.

[0049] The main component of silica sol (silica), which is another suitable example of a compound having a siloxane bond, is SiO ２ and the silicate compound is silica sol (SiO ２ ), the bonding strength between the matrix 8 containing silica sol (silica) and the inorganic material 9 can also be improved.

[0050] It is also preferable that the inorganic material 9 contains at least one selected from silica, alumina, mullite, zirconia, and calcium carbonate. These materials have high melting points and high insulating properties. When a bus bar is used as an example of the composite member 1, the expected heat exposure temperature of the bus bar is equal to or higher than the melting point of the metal material typically used in the body of a bus bar. These materials are preferable because they have melting points equal to or higher than the heat exposure temperature and can prevent the bus bar body from being exposed to high heat.

[0051] The content of inorganic material 9 relative to all components of the first coating material 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 9 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 becomes too high, resulting in poor film-forming properties.

[0052] (Outer Layer 5) The outer layer 5 is made of a second coating material containing a silicone-containing matrix 8 and a scale-like, plate-like, flake-like, or fibrous inorganic material 9. The second coating material may have the same composition as the first coating material described above, and the preferred material names and the content of the inorganic material 9 will not be described here. The second coating material may also have a different composition from the first coating material, and a material different from the first coating material may be selected from the preferred materials listed above, or the content of the inorganic material 9 may be changed.

[0053] (Resin Layer) The resin forming the resin layer may be different from the resins contained in the inner layer 4 and the outer layer 5, but is preferably a heat-resistant resin such as an epoxy resin, a nylon resin, SBR (styrene butadiene rubber), silicone rubber, or PVC (polyvinyl chloride).

[0054] [Manufacturing Method of Composite Member] A manufacturing method of the composite member 1 of this embodiment will be described below, and examples include the following <Manufacturing Method 1> and <Manufacturing Method 2>. In order to make the orientation of the inorganic material 9 different between the inner layer 4 and the outer layer 5 as described above, it is sufficient to change the application method for the first coating material that will become the inner layer 4 and the second coating material that will become the outer layer 5. Note that the following manufacturing method will be described for the case where the compound having a siloxane bond contained in the matrix is ​​silicone, but it can also be applied in the same way when the compound having a siloxane bond is silica sol (silica).

[0055] <Manufacturing Method 1> (Inner Layer Forming Step) A first coating material is applied to the substrate 2. Possible application methods include dip coating, brush coating, spray coating, and dispenser coating. The coating of the first coating material is then dried, for example, at a temperature of 50°C to volatilize the organic solvent in the first coating material. In this way, a first layer that will become the inner layer 4 is formed.

[0056] (Outer Layer Formation Process) Next, a second coating material is applied onto the first layer. The application method can be partial dip coating, brush coating, dispenser coating, or the like, which allows the second coating material to be applied locally to areas where the first layer is thin, such as the end surface 2b and corners 2c. The second coating material is applied using a different application method than that used for the first layer. After application, the second coating material is dried, for example, at a temperature of 50°C, to volatilize the organic solvent in the second coating material. In this way, the second layer, which will become the outer layer 5, is formed.

[0057] After the first and second layers are formed, they are cured by heating at a temperature of, for example, 200°C. This heating causes dehydration condensation of the silicone (a compound having a siloxane bond), forming a three-dimensional network structure and generating pores 10. Therefore, the first and second layers are impregnated with a matrix material containing silicone. To impregnate, an impregnation step is performed after drying, such as immersion in a solution containing a matrix material containing silicone. The impregnation step may be repeated multiple times to further reduce the number of pores 10.

[0058] In this way, a composite member 1 having an insulating coating 3 made up of an inner layer 4 and an outer layer 5 formed thereon is manufactured.

[0059] If necessary, the insulating coating 3 may be surrounded by a resin layer. To form the resin layer, for example, an epoxy resin paint is applied to the insulating coating 3, and then dried and hardened. When forming the resin layer, part of the material constituting the resin layer may permeate into the first layer or the second layer.

[0060] <Manufacturing Method 2> In the above-described Manufacturing Method 1, the first layer and the second layer are formed and then cured. Here, the first layer is cured, an impregnation step is performed to form the inner layer 4, and then the second layer is formed on the inner layer 4, cured, and an impregnation step is performed to form the outer layer 5.

[0061] Similarly, the insulating coating 3 may be surrounded by a resin layer.

[0062] The application amounts of the first coating material and the second coating material are adjusted so that the film thickness after hardening will be the preferred film thickness described above.

[0063] The surface of the substrate 2 may be roughened, and blast treatment or the like may be added.

[0064] In the above-described manufacturing method, the first coating material (coating liquid) is an organic solvent to which a silicone-containing matrix material and an inorganic material have been added, and the second coating material (coating liquid) does not contain an inorganic material and is an organic solvent to which a silicone-containing matrix material has been added. However, depending on the types of the first coating material and 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.

[0065] [Specific Application Examples of the Composite Material 1] The composite material 1 can be applied to products such as bus bars, connectors, power storage devices such as battery modules and battery packs, cases for electronic components, motor coils, etc. An example of a bus bar is shown below.

[0066] 6 shows the busbar 100 just before being attached to the battery cell 130. The busbar body 110, which serves as the substrate 2, is, for example, a Z-shaped metal plate member. The busbar body 110 is secured in place by inserting the electrodes 135 of the battery cell 130 into the connection holes 115a at one end and covering them with terminal caps 136. The busbar body 110 also has connection holes 115b at the other end, which are used to connect an adjacent battery cell (not shown) or an external device (not shown). The busbar body 110 is covered with the insulating coating 3 described above, except for the connection holes 115a and 115b. This is how the busbar 100 is constructed.

[0067] 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 busbar body 110, as in the busbar disclosed in Patent Document 1, the wrapping process is time-consuming in order to prevent uneven wrapping or gaps from occurring at the bent portion 110a or the curved portion. Furthermore, it is possible that gaps may occur in the ceramic tape due to vibration or the adhesive between the ceramic tape and the busbar body 110 may peel off.

[0068] In contrast, with the busbar 100 according to this embodiment, the insulating coating 3, which is insulating and heat-resistant and has high strength, can be formed on the surface of the busbar body 110 without wrapping tape around the busbar body 110. Furthermore, because the process of wrapping tape around the busbar body 110 is not required, there are no problems such as uneven wrapping, gaps, or peeling, and the busbar can easily accommodate complex shapes.

[0069] [Electricity Storage Device] This embodiment also relates to an electric energy storage device. FIG. 7 is a schematic diagram of an electric energy storage device 200 in which a plurality of battery cells 130, 130 are connected by the bus bar 100 shown in FIG. 6 and housed in a case 210. Note that the electric energy storage device 200 may have a configuration in which a plurality of battery cells 130, 130 are connected by the bus bar 100 shown in FIG. 6 and housed in the case 210, as shown in FIG. 7, or may have a configuration in which a plurality of battery modules (not shown) are connected by the bus bar 100 shown in FIG. 6 and housed in the case 210.

[0070] Since the bus bar 100 is covered with the insulating coating 3 of this embodiment described above, even if one battery cell 130 experiences thermal runaway, the adjacent battery cells 130 can be protected, providing excellent safety.

[0071] 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.

[0072] This application is based on a Japanese patent application (Patent Application No. 2024-056201) filed on March 29, 2024, the contents of which are incorporated herein by reference.

[0073] REFERENCE SIGNS LIST 1 composite member 2 substrate 3 insulating coating 4 inner layer 5 outer layer 8 matrix 9 inorganic material 10 pores 100 busbar 110 busbar body 110a bent portion 130 battery cell 135 electrode 200 power storage device 210 case

Claims

1. A composite member having a substrate and an insulating coating covering at least a portion of the surface of the substrate, wherein the insulating coating has: an inner layer made of a first coating material having a matrix containing a compound having a siloxane bond and a scale-like, flat, flake-like or fibrous inorganic material dispersed in the matrix; and an outer layer made of a second coating material having a matrix containing a compound having a siloxane bond and a scale-like, flat, flake-like or fibrous inorganic material dispersed in the matrix, wherein the orientation of the inorganic material relative to the surface of the substrate differs between the inner layer and the outer layer.

2. The composite member according to claim 1, wherein the orientation of the inorganic material in the inner layer is higher than the orientation of the inorganic material in the outer layer.

3. The composite member according to claim 2, wherein the inner layer contains 60 to 100% inorganic material oriented at an angle of 0 to 10 degrees relative to a direction parallel to the surface of the substrate, and the outer layer contains 10 to 80% inorganic material oriented at an angle of 0 to 10 degrees relative to a direction parallel to the surface of the substrate.

4. A composite member as described in claim 1, characterized in that the substrate has a pair of opposing main surface portions, a plurality of end surface portions connecting the main surface portions, and corner portions between the main surface portions and the end surface portions, and at least a portion of the insulating coating surrounds the corner portions of the substrate.

5. The composite member according to claim 4, wherein at least a portion of said insulating coating further surrounds said end surface portion of said substrate.

6. The composite member according to claim 4, wherein the outer surface of the insulating coating formed on the corner of the base material has a cross-sectional shape that follows the corner of the base material and has an R-shape.

7. The composite member according to claim 1, wherein the inner layer and the outer layer have the same composition.

8. The composite member according to claim 1, wherein the inner layer and the outer layer are of different compositions.

9. The composite member according to claim 1, wherein the compound having a siloxane bond contained in the first coating material and / or the second coating material is at least one of silicone and silica sol.

10. The composite member according to claim 1, wherein the inorganic material comprises at least one selected from the group consisting of silica, alumina, mullite, zirconia, and calcium carbonate.

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

12. The composite member according to claim 1, wherein the inorganic material includes at least one of a flake glass-based material and mica.

13. The composite member according to claim 1, wherein at least one of the inner layer and the outer layer is impregnated with a matrix material containing the compound having a siloxane bond.

14. The composite member according to claim 1, wherein at least the portion of the substrate on which the inner layer is formed has a rough surface.

15. A composite member according to claim 1, characterized in that the outermost surface has a resin layer made of a resin different from the resins contained in the first coating material and the second coating material.

16. A method for producing a composite member according to any one of claims 1 to 15, comprising: an inner layer forming step of applying to at least a portion of the surface of the substrate a paint containing a first coating material having a matrix material containing a compound having a siloxane bond and a scale-like, flat, flake-like or fibrous inorganic material, and curing the paint; and an outer layer forming step of applying to at least a portion of the surface of the inner layer, by a coating method different from that used in the inner layer forming step, a paint containing a second coating material having a matrix material containing a compound having a siloxane bond and a scale-like, flat, flake-like or fibrous inorganic material, and curing the paint.

17. A method for manufacturing a composite member according to claim 16, characterized in that the coating method in the inner layer forming step is dip coating, brush coating, spray coating or dispenser coating, and the coating method in the outer layer forming step is dip coating, brush coating or dispenser coating.

18. The method for manufacturing a composite member according to claim 16, characterized in that the first coating material and the second coating material have the same composition.

19. The method for manufacturing a composite member according to claim 16, characterized in that the first coating material and the second coating material have different compositions.

20. A method for manufacturing a composite member according to claim 16, characterized in that the compound having a siloxane bond contained in the first coating material and / or the second coating material is at least one of silicone and silica sol.

21. A method for producing a composite member according to claim 16, characterized in that after at least one of the inner layer forming step and the outer layer forming step, an impregnation step is performed in which a matrix material containing a compound having a siloxane bond is immersed.

22. The method for producing a composite member according to claim 16, further comprising a step of roughening the surface of the substrate.

23. A method for manufacturing a composite member as described in claim 16, characterized in that it includes a resin layer forming step of applying and curing a resin material containing a resin different from the resins contained in the first coating material and the second coating material to the outermost surface.

24. An electricity storage device, characterized in that a plurality of battery cells or battery modules are connected by the composite member according to any one of claims 1 to 15.

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