Bus bar, manufacturing method for the same, and power storage device

Abstract

To provide a bus bar that can stably ensure insulation, a manufacturing method for the same, and a power storage device.SOLUTION: A bus bar 1 used in a power storage device including a battery cell has a bus bar body 5 containing a conductive material that is coated with an insulation coating 10. Corners 7 of the bus bar body 5 are processed with a radius R. The manufacturing method for the bus bar 1 includes a step for processing the corners of the bus bar body 5 that contain a conductive material with a radius R and a step for forming the insulation coating 10 by applying insulation paint to the bus bar body 5 and then hardening it. The power storage device is a device that connects multiple battery cells or battery modules using the bus bar.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a bus bar and a manufacturing method thereof, and to an energy storage device in which a plurality of battery cells or battery modules are connected by a bus bar. [Background technology]

[0002] Electric storage devices in which multiple battery cells are connected in series or in parallel by bus bars are mounted on various electronic devices, electric vehicles or hybrid vehicles driven by electric motors, storage batteries, etc. In addition, lithium-ion secondary batteries, which have higher capacity and higher output than lead-acid batteries or nickel-metal hydride batteries, are mainly used as battery cells.

[0003] Since bus bars are required to have insulating properties, in Patent Document 1, a coating film made of a resin such as epoxy, epoxy polyester, or polyester is formed on the bus bar body such as a metal plate.

[0004] However, when an overcurrent flows through a battery cell during charging and discharging, the busbar may heat up and, in some cases, may burst into flames. In such an abnormal situation, the resin coating film as in Patent Document 1 does not have sufficient heat resistance. Therefore, in Patent Document 2, the busbar body is covered with a mica sheet that has electrical insulation and heat resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-48001 [Patent Document 2] Special Publication No. 2020-528650 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, in Patent Document 1, fluidized bed dip coating (fluidized bed dip powder coating) is used to form the coating. The busbar body is a member punched out of a metal plate into a specified shape, and the cross-sectional shape of the portion continuing from the front and back surfaces of the metal plate to the end face (thickness portion), i.e., the corners (see corners 7 in Fig. 2), is approximately a right angle. Therefore, when the coating is formed by fluidized bed dip coating as in Patent Document 1, the coating at the corners of the busbar body becomes thin, which is likely to cause insulation failure.

[0007] Furthermore, in Patent Document 2, the mica sheet needs to be wrapped around the busbar body. Due to spatial limitations of the installation location of the battery cells, the busbar may have a complex shape, and when the busbar has a complex shape, it is difficult to wrap the mica sheet around every corner of the busbar body. If the mica sheet has uneven winding or gaps, sufficient electrical insulation cannot be obtained. Furthermore, it is expected that the adhesive surface of the mica sheet will peel off at high temperatures.

[0008] Therefore, the present invention aims to provide a busbar that can stably ensure insulation. It also aims to provide a method for manufacturing a busbar that does not require a wrapping process like a mica sheet, does not cause problems such as uneven winding or gaps in the sheet or peeling of the sheet, can easily accommodate complex shapes, and is easy to manufacture. It also aims to provide an energy storage device that connects multiple battery cells or battery modules with such a busbar and exhibits high safety even in the event of an abnormality. [Means for solving the problem]

[0009] The above object of the present invention is achieved by the following configuration [1] relating to a busbar.

[0010] [1] A busbar for use in an energy storage device including a battery cell, A busbar body including a conductive material and an insulating coating that covers the busbar body, The busbar, wherein corners of the busbar body are rounded.

[0011] Further, preferred embodiments of the present invention relating to the busbar relate to the following [2] to

[12] .

[0012] [2] The busbar according to [1], wherein the radius of curvature (R) in the R processing of the corners is 500 μm or more.

[0013] [3] The busbar according to [2], characterized in that the insulating coating contains a filler.

[0014] [4] The busbar according to [3], characterized in that the filler contains an inorganic compound.

[0015] [5] The busbar according to [4], characterized in that the inorganic compound includes a silicate compound.

[0016] [6] The busbar according to [5], characterized in that the silicate compound is at least one selected from a glass-based material, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth, and halloysite.

[0017] [7] The busbar according to [6], wherein the glass-based material is at least one selected from the group consisting of glass flakes, glass particles, glass fibers, and glass beads.

[0018] [8] The busbar according to [6], characterized in that the silicate compound contains at least one of a glass-based material and mica, and the glass-based material is flake glass.

[0019] [9] The busbar according to any one of [3] to [8], wherein a content of the filler relative to all components in the insulating coating is 3 to 70 volume %.

[0020]

[10] The busbar according to any one of [1] to [8], wherein the insulating coating has a minimum thickness of 300 μm or more.

[0021]

[11] The busbar according to any one of [1] to [8], wherein the insulating coating contains a silicone-based material.

[0022]

[12] The busbar according to any one of [1] to [8], wherein the insulating coating contains a silicone resin and a thixotropic agent.

[0023] The above object of the present invention can be achieved by the following configuration

[13] relating to a method for manufacturing a busbar.

[0024]

[13] A method for manufacturing a bus bar used in an energy storage device including a battery cell, comprising: A process of performing R processing on corners of a busbar body including a conductive material; and after applying an insulating paint to the busbar body, drying the insulating paint to form an insulating coating.

[0025] Further, preferred embodiments of the present invention relating to a method for manufacturing a bus bar relate to the following items

[14] to

[25] .

[0026]

[14] A method for manufacturing a busbar according to

[13] , characterized in that the insulating paint is applied to the busbar body by using at least one coating method selected from spray coating, powder coating, and dip coating.

[0027]

[15] The method for manufacturing a busbar according to

[13] , wherein the radius of curvature (R) in the R processing of the corners is 500 μm or more.

[0028]

[16] The method for manufacturing a busbar according to

[15] , wherein the insulating varnish contains a filler.

[0029]

[17] The method for manufacturing a busbar according to

[16] , wherein the filler contains an inorganic compound.

[0030]

[18] The method for manufacturing a busbar according to

[17] , wherein the inorganic compound includes a silicate compound.

[0031]

[19] The method for manufacturing a busbar according to

[18] , wherein the silicate compound is at least one selected from glass-based materials, mica, kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth and halloysite.

[0032]

[20] The method for manufacturing a busbar according to

[19] , wherein the glass-based material is at least one selected from glass flakes, glass particles, glass fibers, and glass beads.

[0033]

[21] The method for manufacturing a busbar according to

[19] , characterized in that the silicate compound contains at least one of a glass-based material and mica, and the glass-based material is flake glass.

[0034]

[22] The method for manufacturing a busbar according to any one of

[16] to

[21] , wherein the content of the filler in the insulating varnish is 3 to 70 volume % relative to the total solid components.

[0035]

[23] The method for manufacturing a busbar according to any one of

[13] to

[21] , characterized in that the insulating veneer is applied to the busbar body so that the minimum film thickness of the insulating veneer is 300 μm or more.

[0036]

[24] The method for manufacturing a busbar according to any one of

[13] to

[21] , wherein the insulating varnish contains a silicone-based material.

[0037]

[25] The method for manufacturing a busbar according to any one of

[13] to

[21] , wherein the insulating varnish contains a silicone resin and a thixotropic agent.

[0038] The above object of the present invention can be achieved by the following configuration

[26] relating to the electricity storage device.

[0039]

[26] A power storage device comprising a plurality of battery cells or battery modules connected by the bus bar according to any one of [1] to

[12] . Effect of the Invention

[0040] The busbar of the present invention has a busbar body with rounded corners covered with an insulating coating. The corners of the busbar body also have a sufficiently thick insulating coating formed thereon, making insulation failure less likely to occur.

[0041] Furthermore, the busbar manufacturing method of the present invention simplifies the manufacturing process since the insulating paint can be applied using a simple painting method, and can form a thick insulating coating without gaps regardless of the shape of the busbar body, even on the corners of the busbar body.

[0042] Furthermore, in the energy storage device of the present invention, since a plurality of battery cells or battery modules are connected by such bus bars, insulation failure is unlikely to occur and high safety is exhibited even in the event of an abnormality. [Brief description of the drawings]

[0043] [Figure 1] FIG. 1 is an exploded perspective view showing an example of a bus bar of the present invention attached to a battery cell. [Diagram 2] FIG. 2 is a cross-sectional view showing the embodiment of the busbar along the line AA in FIG. 1, and is a schematic diagram showing an enlarged view of the periphery of a corner of the busbar body. [Diagram 3] FIG. 3 is a perspective view illustrating a method for measuring the minimum and maximum thicknesses of an insulating coating. [Figure 4]FIG. 4 is a cross-sectional view showing an example of the electricity storage device of the present invention. [Diagram 5] FIG. 5 is a graph showing the results of measuring the thickness of the insulating coating in the examples and the comparative examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] Hereinafter, the 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 modified and implemented as desired without departing from the gist of the present invention.

[0045] [Busbar] Fig. 1 is an exploded perspective view showing a busbar 1 according to this embodiment attached to a battery cell 110. As shown in Fig. 1, the busbar body 5 made of a conductive material is, for example, a Z-shaped metal plate member, and an electrode 111 of the battery cell 110 is inserted into a connection hole 6a at one end and fixed by covering it with a terminal cap 112. An adjacent battery cell (not shown) or an external device (not shown) is connected to a connection hole 6b at the other end of the busbar body 5. The busbar 1 is formed by covering the entire surface of the busbar body 5 excluding the connection holes 6a and 6b with an insulating coating 10, which will be described later.

[0046] Although not shown in the drawings, the busbar body 5 can have various shapes according to where the battery cell 110 is installed, such as an overall I-shape or an irregular shape with a curved portion.

[0047] If the busbar body 5 has a Z-shaped bent portion 5a or a curved portion (not shown) as shown in FIG. 1, the method of wrapping a mica sheet around the busbar in Patent Document 2 may require a lot of work to prevent uneven winding or gaps from occurring around the bent portion 5a or the curved portion, or it may cause gaps due to vibration or peeling of the adhesive. However, as described below, in this embodiment, the insulating coating 10 can be formed using at least one coating method selected from spray coating, powder coating, and dip coating, so that such problems do not occur. Among these coating methods, "dip coating" in particular has the advantage of being a simple process. In this specification, the insulating coating obtained by at least one coating method selected from spray coating, powder coating, and dip coating may also be called an "insulating coating".

[0048] Fig. 2 is a cross-sectional view taken along the line AA in Fig. 1, and is a schematic diagram showing an enlarged view of the periphery of a corner 7 of a busbar body 5. As shown in the figure, the corner 7 of the busbar body 5 is rounded. When forming the insulating coating 10 of the busbar 1 of the present invention, at least one coating method selected from, for example, spray coating, powder coating, and dip coating can be used. However, these coating methods have a problem in that the coating becomes thin when the corner 7 of the busbar body 5 has a right angle in cross section. Therefore, by rounding the corner 7 of the busbar body 5, the coating at the corner 7 can be made thicker. Specifically, the thickness of the insulating coating 10 at the corner 7 of the busbar body 5 is preferably 300 µm or more.

[0049] As shown in the figure, the insulating coating 10 becomes thinner at the corners 7 of the busbar body 5 and gradually becomes thicker to a film thickness described below. However, in this embodiment, the film thickness at the corners 7 can be made thicker, so that the difference between the film thickness at the corners and the maximum film thickness can be made smaller.

[0050] If the radius of curvature (R) in the R processing is 500 μm or more, an insulating coating 10 with a sufficient thickness of 300 μm or more can be formed on the corners 7 of the busbar body 5. More preferably, R≧600 μm.

[0051] The insulating coating 10 preferably has insulating properties, and more preferably has heat resistance and fire resistance to withstand heat and flames from the battery cell 110 in the event of an abnormality. Specifically, it is preferable for the insulating coating 10 to have the composition shown below.

[0052] It is preferable that the insulating coating 10 contains a filler, since this can improve heat resistance. Inorganic compounds have high melting points and excellent heat resistance, so it is more preferable that the insulating coating 10 contains an inorganic compound as a filler, and it is even more preferable that the insulating coating 10 contains a silicate compound. By selecting the material of the insulating coating 10 in this way and imparting heat resistance and fire resistance to the insulating coating 10, it is possible to protect the busbar from high temperatures and flames from a battery cell that has experienced thermal runaway, and to prevent the thermal runaway from spreading to adjacent battery cells via the busbar 1.

[0053] 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.

[0054] The glass-based material is preferably at least one selected from glass flakes, glass particles, glass fibers, and glass beads.

[0055] Among these fillers, mica and flake glass are planarly oriented in the coating and exhibit excellent insulating properties and heat resistance. Therefore, when the filler according to the present embodiment contains a silicate compound, it is particularly preferable that the silicate compound contains at least one of a glass-based material and mica, and the glass-based material contains flake glass.

[0056] The content of the filler relative to all components in the insulating coating 10 is preferably 3 to 70% by volume. If the filler content is less than 3% by volume, sufficient insulation and heat resistance may not be obtained. As described below, the insulating coating 10 can be formed using at least one coating method selected from spray coating, powder coating, and dip coating, but if the filler content exceeds 70% by volume, the viscosity of the insulating coating becomes too high, resulting in poor film formability.

[0057] Furthermore, since the insulating coating 10 has excellent non-flammability and heat resistance, it is preferable that the insulating coating 10 contains a silicone-based material as a binder. Examples of the silicone-based material include silicone resin, and the use of a thixotropic agent as a thickener in combination makes it easier to control the thickness of the insulating coating 10.

[0058] In addition to the above-mentioned filler and silicone-based material, insulating coating 10 may contain other materials such as flame retardants, dispersants, pigments, etc., as long as they do not affect the insulating properties or heat resistance.

[0059] The minimum thickness of the insulating coating 10 is preferably 300 μm or more. If the minimum thickness, including the corners 7, is less than 300 μm, sufficient insulation and heat resistance may not be obtained, so it is more preferable that the thickness is 400 μm or more, and even more preferable that the thickness is 500 μm or more. As for the upper limit of the thickness, even if the thickness is made thicker than necessary, further improvement in insulation and heat resistance cannot be expected, and rather, defects in the film quality such as cracks may occur in the insulating coating 10. Therefore, the maximum thickness of the insulating coating 10 is preferably 2000 μm or less, more preferably 1500 μm or less, and even more preferably 1000 μm or less.

[0060] Here, a method for measuring the minimum and maximum thicknesses of the insulating coating 10 in the busbar 1 according to this embodiment will be specifically described with reference to Fig. 3. Fig. 3 shows all bent portions of the busbar 1 shown in Fig. 1 cut along the two faces that form the inner corners and divided into plate-like bodies 11, 12, and 13 and bent bodies 14 and 15. Since it is difficult to measure the thickness of the insulating coating 10 in the entire area formed on the surface of the busbar body 5, in this embodiment, the thickness is measured by the following measurement method. Note that in this measurement method, the bent bodies 14 and 15 that are cut off when the busbar 1 is cut along the two faces that form the inner corners are ignored.

[0061] For example, the plate-like body 12 is cut at three locations, namely, film thickness measurement lines 12a, 12b, and 12c, along a direction perpendicular to the longitudinal direction. The film thickness measurement lines 12a and 12c are located 1 mm inward from both longitudinal end faces 12d and 12e of the plate-like body 12. The film thickness measurement line 12b is located at the center between the film thickness measurement lines 12a and 12c.

[0062] The plate-like body 11 is cut in the same direction as the cutting direction of the plate-like body 12, at three locations corresponding to the thickness measurement lines 11a, 11b, and 11c. Note that a connection hole 6a is provided at one end of the plate-like body 11, and the thickness of the insulating coating 10 may not be stable near the end face 11d on the side of the connection hole 6a. Therefore, the position of the thickness measurement line 11a is set to a position 5 mm inward from the end face 11d of the insulating coating 10. The position of the thickness measurement line 11c is set to a position 1 mm inward from the other end face 11e of the plate-like body 11, and the position of the thickness measurement line 11b is set to the center position between the thickness measurement lines 11a and 11c.

[0063] As for plate-like body 13, similar to plate-like body 11, connection hole 6b is provided at one end, and therefore film thickness measurement line 13a is positioned 5 mm inward from end face 13d of insulating coating 10. Film thickness measurement line 13c is positioned 1 mm inward from the other end face 13e of plate-like body 13, and film thickness measurement line 13b is positioned at the center between film thickness measurement line 13a and film thickness measurement line 13c.

[0064] As described above, the three plate-like bodies 11, 12, and 13 are cut along the film thickness measurement lines 11a-11c, 12a-12c, and 13a-13c, respectively, and photographs are taken of a total of nine cut surfaces. Then, image processing is performed on each photograph, and the distance from the surface of the busbar body 5 to the surface of the insulating coating 10 is measured, and the minimum film thickness is defined as the minimum film thickness, and the maximum film thickness is defined as the maximum film thickness.

[0065] The cross-sectional view shown in Fig. 2 is an example of a cut surface cut along a thickness measurement line using the above measurement method. The thickness of the insulating coating 10 at the corner 7 of the busbar body 5 can also be measured along the thickness measurement line described in the above thickness measurement method. Specifically, in the busbar body 5, extension lines are drawn on each of the two planes constituting the corner 7, and the bisector of the angle formed by the two extension lines is defined as the corner measurement line. Then, the distance from the surface of the busbar body 5 to the surface of the insulating coating 10 on the corner measurement line is defined as the "thickness of the insulating coating at the corner."

[0066] In this embodiment, since the corners 7 are rounded, it is possible to ensure a sufficient thickness of the insulating coating 10 at the corners 7 without increasing the maximum film thickness. Specifically, in a conventional busbar in which the corners are not rounded, the thickness of the insulating coating at the corners is less than 0.15 times the maximum film thickness, but in this embodiment, the thickness of the insulating coating at the corners can be made 0.15 times or more the maximum film thickness. If the radius of curvature (R) of the rounded corners is 500 μm or more, the thickness of the insulating coating at the corners can be made 0.20 times or more the maximum film thickness.

[0067] Although not shown in the figures, if the bus bar has a shape having a curved portion, it is preferable to cut the curved portion that is cut off when cutting it into plate-like pieces in the same manner as above, at a position 1 mm inside from both end faces and at the center position between them, and measure the film thickness.

[0068] [Busbar manufacturing method] (R processing) To manufacture the busbar 1, first, corners 7 of the busbar body 5 are rounded. As described above, it is preferable to make the radius of curvature (R) 500 μm or more. There are no limitations on the processing method, and milling, turning, etc. can be used.

[0069] (Formation of insulating film) Next, the insulating coating 10 is formed on the surface of the busbar body 5 by, for example, "dip coating." For example, a predetermined amount of filler is added to silicone resin and thoroughly mixed to prepare an insulating paint. Then, the periphery of the connection holes 6a, 6b (see FIG. 1) of the busbar body 5 is masked, the busbar body is immersed in the insulating paint, and after being pulled out, the insulating paint is dried to form the insulating coating.

[0070] In this embodiment, the method for applying the insulating paint to the surface of the busbar body 5 is not particularly limited, and at least one coating method selected from spray coating, powder coating, and dip coating can be used. Whichever coating method is used, the insulating coating 10 with a sufficient thickness can be easily formed at the corners.

[0071] Regarding the amount of insulating paint to be applied, it is preferable to appropriately adjust the pulling speed, drying temperature, etc. so that the minimum film thickness after drying (i.e., the minimum film thickness of the insulating coating 10) is preferably 300 μm or more, more preferably 400 μm or more, and even more preferably 500 μm or more.

[0072] The content of the filler in the insulating coating material is preferably 3 to 70% by volume, more preferably 10 to 60% by volume, and even more preferably 20 to 50% by volume. As described above, if the filler content is less than 3% by volume, there is a risk that sufficient insulation and heat resistance cannot be obtained. On the other hand, if the filler content exceeds 70% by volume, the viscosity of the heat-resistant insulating coating material may become too high, resulting in a decrease in film-forming properties.

[0073] The method of wrapping a mica sheet as in Patent Document 2 requires a wrapping operation, which is particularly time-consuming in order to prevent uneven wrapping or gaps around the bent portion 5a or curved portion. It is also anticipated that gaps may be generated or the adhesive may peel off due to vibration or the like. However, in the present invention, the insulating coating 10 can be formed using at least one coating method selected from spray coating, powder coating, and dip coating, so that such problems do not occur. Among these coating methods, "dip coating" in particular has the advantage of being a simple process.

[0074] Furthermore, the insulating coating 10 does not have overlapping windings as in the case of a mica sheet, and the insulating properties are not reduced.

[0075] [Electricity storage device] 4, the power storage device 100 has a plurality of battery cells 110 housed in a battery case 120. Adjacent battery cells 110 are connected to each other by the bus bar 1.

[0076] The busbar 1 is covered with the insulating coating 10, and even the corners 7 are covered with the insulating coating 10 having a sufficient thickness, so that sufficient insulation can be ensured and the busbar 1 can be protected even if a battery cell 110 experiences thermal runaway. Therefore, the power storage device of this embodiment has a plurality of battery cells 110 and battery modules (not shown) connected together by such bus bars 1, and therefore exhibits high safety even in the event of an abnormality. EXAMPLES

[0077] The present invention will be explained more clearly with reference to the following examples and comparative examples. Specifically, test pieces in which an insulating coating was formed after rounding the corners and test pieces in which an insulating coating was formed without rounding were prepared, and the thicknesses of the insulating coatings formed on the corners were compared.

[0078] Example 1 The corners of an aluminum plate 150 mm long, 30 mm wide, and 2 mm thick, which was used to represent the busbar body, were rounded to a radius of curvature R = 900 μm. The rounded aluminum plate was then immersed in an insulating paint containing 27% by volume of mica particles relative to the total volume of the insulating paint and silicone resin, and after being pulled up, the paint was dried to form an insulating coating, and a test specimen was prepared. The amount of coating was changed by changing the pulling conditions, and the thickness of the insulating coating after drying was adjusted.

[0079] Example 2 A test piece was prepared in the same manner as in the example, except that a copper plate was used instead of an aluminum plate and the corners were subjected to R processing with a curvature radius R of 600 μm.

[0080] Comparative Example 1 The same aluminum plate as in Example 1 was used without subjecting the corners to rounding, and a test piece was prepared in the same manner.

[0081] The test piece thus prepared was cut along the pair of sides at the center, and the cut surface was photographed and image-processed. The maximum thickness of the insulating coating in the image was measured, and the thicknesses of the insulating coating at the four corners were also measured. The measurement results are shown in a graph in FIG. 5. Note that the "flat part thickness" in FIG. 5 represents the maximum value of the insulating coating thickness in the image photographed by the above method, and in this example, it was considered to be the maximum thickness of the insulating coating formed on the test piece. Furthermore, the "corner part thickness" represents the minimum value of the insulating coating at the four corners in the image photographed by the above method, and in this example, it was considered to be the minimum thickness of the insulating coating formed on the test piece.

[0082] As shown in FIG. 5, for each test piece, as the coating thickness on the flat surface increases, the coating thickness on the corners also increases. However, in the test piece of Comparative Example 1 in which the corners are not subjected to R processing, even if the plane portion film thickness is 62 μm, no insulating coating is formed on the corners. In contrast, in the test piece of Example 1 in which the corners are subjected to R processing, even if the plane portion film thickness is 58 μm, an insulating coating of about 11 μm is formed at the angle. In the test piece of Comparative Example 1, in order to make the corner film thickness 10 μm, the plane portion film thickness needs to be thickened to about 110 μm. In addition, when comparing Comparative Example 1 and Example 2, in the test piece of Comparative Example 1, when the plane portion film thickness is 1229 μm, the corner film thickness is only 114 μm. On the other hand, in the test piece of Example 2, when the plane portion film thickness is 1152 μm, the corner film thickness is 460 μm, and an insulating coating of sufficient thickness can be formed on the corner. In this way, by applying R processing to the corners of the busbar body, it is possible to make the insulating coating on the flat portions thinner and also reduce the amount of coating required to form the insulating coating, thereby reducing manufacturing costs.

[0083] Furthermore, these test results show that by setting the radius of curvature (R) in R processing to 500 μm or more, and by forming the thickness of the insulating coating on the flat portions to approximately 1,250 μm, the thickness of the insulating coating at the corners can be made 300 μm or more, and the thickness of the insulating coating at the corners can be controlled within a preferred range. [Explanation of symbols]

[0084] 1 Busbar 5 Busbar body 6a, 6b Connection holes 7 Corner 10 Insulation coating 100 Electricity storage device 110 Battery Cell 111 Electrode 120 Battery case R Corner curvature radius

Claims

1. A bus bar used in an electricity storage device including a battery cell, a busbar body including a conductive material and an insulating coating covering the busbar body; The busbar is characterized in that corners of the busbar body are rounded.

2. The bus bar according to claim 1, wherein the radius of curvature (R) of the rounded corners is 500 μm or more.

3. The bus bar according to claim 2 , wherein the insulating coating contains a filler.

4. The bus bar according to claim 3 , wherein the filler includes an inorganic compound.

5. The busbar of claim 4 , wherein the inorganic compound comprises a silicate compound.

6. 6. The bus bar according to claim 5, wherein the silicate compound is 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.

7. 7. The bus bar according to claim 6, wherein the glass-based material is at least one selected from the group consisting of glass flakes, glass particles, glass fibers, and glass beads.

8. 6. The bus bar according to claim 5, wherein the silicate compound is at least one selected from the group consisting of kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth, and halloysite.

9. The bus bar according to any one of claims 3 to 8, wherein a content of the filler relative to all components in the insulating coating is 3 to 70% by volume.

10. The bus bar according to any one of claims 1 to 8, wherein the insulating coating has a minimum thickness of 300 µm or more.

11. The bus bar according to any one of claims 1 to 8, wherein the insulating coating contains a silicone-based material.

12. The bus bar according to any one of claims 1 to 8, wherein the insulating coating contains a silicone resin and a thixotropic agent.

13. A busbar as described in any one of claims 1 to 8, characterized in that the thickness of the insulating coating at the corner portion is not less than 0.15 times and not more than 115 / 288 times the maximum thickness of the insulating coating.

14. A method for manufacturing a bus bar used in an energy storage device including battery cells, comprising: a step of performing rounding on corners of a busbar body including a conductive material; and applying an insulating paint to the bus bar body and then drying the insulating paint to form an insulating coating.

15. The method for manufacturing a busbar according to claim 14, wherein the insulating paint is applied to the busbar body by using at least one coating method selected from the group consisting of spray coating, powder coating, and dip coating.

16. The method for manufacturing a bus bar according to claim 14, wherein the radius of curvature (R) in the rounding of the corners is set to 500 μm or more.

17. The method for manufacturing a bus bar according to claim 16, wherein the insulating varnish contains a filler.

18. The method for manufacturing a bus bar according to claim 17, wherein the filler includes an inorganic compound.

19. The method for manufacturing a busbar according to claim 18, wherein the inorganic compound includes a silicate compound.

20. 20. The method for manufacturing a bus bar according to claim 19, wherein the silicate compound is 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.

21. 21. The method for manufacturing a bus bar according to claim 20, wherein the glass-based material is at least one selected from the group consisting of glass flakes, glass particles, glass fibers, and glass beads.

22. 20. The method for manufacturing a bus bar according to claim 19, wherein the silicate compound is at least one selected from the group consisting of kaolin, talc, clay, pyrophyllite, montmorillonite, bentonite, wollastonite, xonotlite, zeolite, diatomaceous earth, and halloysite.

23. The method for manufacturing a bus bar according to any one of claims 17 to 22, wherein a content of the filler relative to a total solid content in the insulating varnish is 3 to 70 volume %.

24. The method for manufacturing a busbar according to any one of claims 14 to 22, wherein the insulating coating is applied to the busbar body so that the minimum thickness of the insulating coating after drying is 300 µm or more.

25. The method for manufacturing a bus bar according to any one of claims 14 to 22, wherein the insulating varnish contains a silicone-based material.

26. The method for manufacturing a bus bar according to any one of claims 14 to 22, wherein the insulating varnish contains a silicone resin and a thixotropic agent.

27. ​​A method for manufacturing a busbar as described in any one of claims 14 to 22, characterized in that the insulating paint is applied to the busbar body so that the thickness of the insulating coating at the corner portion is not less than 0.15 times and not more than 115 / 288 times the maximum thickness of the insulating coating.

28. A power storage device in which a plurality of battery cells or battery modules are connected by the bus bar according to any one of claims 1 to 8.

Images