Fireproof busbars and battery packs equipped with them

Abstract

The present invention provides a battery pack including the fireproof busbar, the fireproof busbar comprising: a busbar conductor portion; a fireproof silicone coating layer that covers the busbar conductor portion except for both ends and that is ceramicized at a high temperature to support the busbar conductor portion; and a protective layer that covers the fireproof silicone coating layer, the fireproof silicone coating layer having a built-in metal sheet that reinforces the structural rigidity of the fireproof silicone coating layer.

Description

Technical Field

[0001] The present invention relates to a refractory bus bar and a battery pack including the same.

[0002] More specifically, the present invention relates to a refractory bus bar and a battery pack including a refractory silicone coating layer that is ceramized at high temperatures and a protective layer that wraps the coating layer, and that can maintain insulation and airtightness even at high temperatures at which ignition occurs inside the battery pack.

[0003] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0139401 filed on October 26, 2022, and all of the contents disclosed in the literature of the Korean patent application are included as part of this specification.

Background Art

[0004] A battery pack applied to an electric vehicle or the like has a structure in which a number of battery modules including a plurality of secondary batteries are connected in series or parallel in order to obtain high output. The secondary battery can be repeatedly charged and discharged by an electrochemical reaction between components including a positive electrode and a negative electrode current collector, a separator, an active material, an electrolyte, and the like.

[0005] A bus bar is used to electrically connect the battery modules. The bus bar is used to electrically connect the terminal portions of adjacent battery modules or to connect the battery module to an external electrical device.

[0006] FIG. 1 is a schematic diagram showing a conventional bus bar structure.

[0007] As shown in the figure, a conventional busbar 1 consists of a busbar conductor portion 10 and a covering layer 20 that surrounds the busbar conductor portion. The busbar conductor portion 10 is, for example, a high-purity copper conductor portion such as C1100 or a metal conductor portion such as aluminum. The covering layer 20 is made of a material such as ordinary silicone rubber or epoxy. The covering layer 20 covers the main body portion of the busbar conductor portion 10, excluding both ends 11. Fastening holes 11a are provided at both ends 11 of the busbar conductor portion 10 for fastening to corresponding electrical connectors.

[0008] Figure 2 shows that the busbar 1 electrically connects the battery modules M installed within the battery pack. The busbar 1 is installed in a through-hole H of a partition wall W installed between the battery modules M, and both ends 11 of the exposed metal conductor portion 10 of the busbar 1 are connected to the module terminals on both sides of the partition wall, respectively.

[0009] When battery modules are electrically connected using the conventional busbars described above within the battery pack, for example, no problems occur with the operation of the battery pack at normal operating temperatures.

[0010] However, when a flame occurs inside the battery pack, the temperature of the flame is extremely high (500-800°C, or even over 800°C, and in severe cases over 1000°C), causing the silicone rubber or epoxy coating layer to completely melt and the busbar conductors to be exposed to the outside. When this happens, the exposed busbar conductors come into electrical contact with other metal parts of the pack, causing a short circuit, and the heat generated by the short circuit causes the flame to spread further.

[0011] To prevent thermal propagation, busbars using mica sheets, glass fibers, or heat-resistant silicone (rubber) as the coating layer can be considered.

[0012] However, under the intense heat generation conditions described above, the materials exemplified above cannot adequately prevent heat diffusion. For example, ordinary heat-resistant silicone rubber has a heat resistance temperature of only 125-300°C and cannot effectively deal with ignition conditions inside a battery pack. Furthermore, mica sheets and glass fiber coatings do not possess sufficient fire resistance.

[0013] Thus, modern battery packs are designed to prevent flames from leaking outside the pack in the event of internal ignition.

[0014] Furthermore, the design must ensure that the busbar conductor is thermally and electrically insulated from its surroundings, even at high temperatures during flame generation.

[0015] Based on the above, it can be said that there is a need for the development of a technology that can improve insulation strength and ease of assembly while maintaining electrical insulation properties by providing fire resistance at high temperatures. [Prior art documents] [Patent Documents]

[0016] [Patent Document 1] Korean Published Patent Publication No. 2022-0001228 [Overview of the Initiative] [Problems that the invention aims to solve]

[0017] The present invention provides a fire-resistant busbar that can maintain thermal and electrical insulation for as long as possible, even when a flame occurs inside a battery pack.

[0018] Furthermore, the present invention aims to provide a battery pack equipped with the above-mentioned fire-resistant busbar. [Means for solving the problem]

[0019] The refractory busbar of the present invention for solving the above problems includes a busbar conductor part, a refractory silicone coating layer that wraps the part excluding both ends of the busbar conductor part and is ceramified at high temperature to support the busbar conductor part, and a protective layer that wraps the refractory silicone coating layer. The refractory silicone coating layer is characterized in that a metal sheet for reinforcing the structural rigidity of the refractory silicone coating layer is incorporated therein.

[0020] The above refractory silicone can be ceramified at a temperature of 500 to 1700 °C.

[0021] The above refractory silicone can be ceramified by sintering a silicone resin containing a silicone compound represented by the following Chemical Formula 1 and a metal oxide containing silicon oxide.

[0022]

Number

[0023] In the above Chemical Formula 1, m and n are each an integer of 10 to 30.

[0024] The above silicone resin and metal oxide can be contained in a weight ratio of 1:0.5 to 1.5.

[0025] The metal oxide containing silicon oxide may contain one or more of pure silicon dioxide, silica, quartz, silica stone, tridymite, and keatite.

[0026] The above metal sheet can be extended along the refractory silicone coating layer that wraps the busbar conductor part and incorporated into the refractory silicone coating layer so as to wrap the busbar conductor part.

[0027] A fire-resistant silicone coating layer is provided between the inside of the metal sheet and the busbar conductor portion, and a fire-resistant silicone coating layer is provided between the outside of the metal sheet and the protective layer. The fire-resistant silicone coating layers on the inside and outside of the metal sheet can be connected through through holes formed in the metal sheet.

[0028] The above metal sheet can be molded together with the above fire-resistant silicone coating layer.

[0029] The above-mentioned metal sheet has multiple through holes, and by injection molding refractory silicone onto the upper and lower surfaces of the metal sheet, the refractory silicone is coated onto the upper and lower surfaces of the metal sheet and filled into the through holes, thereby forming the metal sheet and the refractory silicone coating layer integrally.

[0030] The integrated metal sheet and the fire-resistant silicone coating layer described above can be processed into a tape shape, and the tape can be wound around the busbar conductor to coat the busbar conductor with the fire-resistant silicone coating layer.

[0031] In the fire-resistant busbar of the present invention, the busbar conductor portion and the metal sheet are arranged in a mold, the metal sheet encloses the busbar conductor portion while being separated from it, and a fire-resistant silicone coating layer comprising the metal sheet can cover the busbar conductor portion by insert injection molding in which the fire-resistant silicone is injected into the mold.

[0032] The protective layer described above may be made of glass fiber or mica material.

[0033] The above-mentioned fire-resistant busbar may be a high-voltage busbar that electrically connects the high-voltage terminals of multiple battery modules.

[0034] Another aspect of the present invention, the battery pack may include a plurality of battery modules, flame-preventing partitions installed between the battery modules, fire-resistant busbars electrically connecting the battery modules, and a pack housing that accommodates the battery modules and the flame-preventing partitions.

[0035] The flame-preventing partition wall is provided with busbar installation through-holes or busbar installation grooves, the fire-resistant busbars are secured to the busbar installation through-holes or busbar installation grooves, and both ends of the fire-resistant busbars can be electrically connected to the terminals of battery modules located on both sides of the flame-preventing partition wall. [Effects of the Invention]

[0036] The fire-resistant busbar of the present invention is equipped with a fire-resistant silicone coating layer that is ceramicized to support the busbar conductor portion, instead of a coating layer that is inflammable when a flame occurs inside the pack, thus maintaining insulation and airtightness even at high temperatures.

[0037] Furthermore, the fire-resistant silicone coating layer can be reinforced with a metal sheet to prevent deformation due to external forces. The metal sheet also maintains the insulation and shape of the busbar and provides the shielding function necessary for high voltages.

[0038] Furthermore, the fire-resistant busbar of the present invention is equipped with a protective layer that protects the fire-resistant silicone coating layer, and the protective layer temporarily acts as a fire-resistant wall while preventing the fire-resistant silicone coating layer from being directly exposed to flames, thereby maintaining the overall shape and dimensions. [Brief explanation of the drawing]

[0039] [Figure 1] These are schematic and cross-sectional diagrams showing a conventional busbar structure. [Figure 2] This is a schematic diagram showing how battery modules are connected using conventional busbars. [Figure 3]These are perspective views and cross-sectional views of a fire-resistant busbar according to one embodiment of the present invention. [Figure 4] This is a schematic diagram illustrating an example of the process for manufacturing the fire-resistant busbar of the present invention. [Figure 5] This is a schematic diagram illustrating another example of the process for manufacturing the fire-resistant busbar of the present invention. [Figure 6] This is a schematic diagram showing an example of a battery pack structure in which the fire-resistant busbar of the present invention is installed. [Figure 7] This is a schematic diagram showing another example of a battery pack structure in which the fire-resistant busbar of the present invention is installed. [Figure 8] This is a side cross-sectional view showing the fire-resistant busbar of the present invention installed on a battery pack. [Modes for carrying out the invention]

[0040] The detailed configuration of the present invention will be described below with reference to the attached drawings and various embodiments. The embodiments described below are illustrative to aid in understanding the present invention, and the attached drawings are not illustrated to actual scale to aid in understanding the invention, and the dimensions of some components may be exaggerated.

[0041] The present invention is subject to various modifications and may take many forms; therefore, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to any particular disclosure, but rather should be understood to include all modifications, equivalents, or substitutions that fall within the spirit and technical scope of the present invention.

[0042] [Fireproof bus bar] The fire-resistant busbar of the present invention includes a busbar conductor portion, a fire-resistant silicone coating layer that encloses the portion of the busbar conductor portion excluding both ends and is ceramicized at high temperature to support the busbar conductor portion, and a protective layer that encloses the fire-resistant silicone coating layer, wherein the fire-resistant silicone coating layer has a metal sheet embedded in it that reinforces the structural rigidity of the fire-resistant silicone coating layer.

[0043] The busbar conductor portion described above may be an ordinary metal conductor portion. That is, it may be made of a high-purity tough pitch copper material of 99.9% or more, such as C1100, or it may be manufactured from aluminum. In other words, the busbar conductor portion of the present invention is not particularly limited as long as it is made of a metal material that can function as a busbar conductor for connecting electrical components. Both ends of the busbar conductor portion described above are electrically connected to the corresponding electrical connection portion.

[0044] The fire-resistant silicone coating layer is a layer that covers the busbar conductor portion while enclosing the portion excluding both ends. That is, the fire-resistant silicone coating layer covers the central part of the busbar conductor portion excluding both ends. The fire-resistant silicone coating layer is ceramicized at high temperatures to support the busbar conductor portion. The fire-resistant silicone can be ceramicized at temperatures of 500 to 1700°C. The fire-resistant silicone of the present invention is distinguished from heat-resistant silicone, which has a heat resistance temperature of less than 300°C, in that its fire resistance temperature is 500°C or higher. Heat-resistant silicone is a silicone resin or rubber composition that has flexibility and pliability due to the properties of silicone, but it is a material that will not burn or will turn to ash at high temperatures of 500°C or higher. Therefore, there are limitations to its application in preventing short circuits or heat propagation in battery packs under heat propagation conditions.

[0045] The above-mentioned fire-resistant silicone coating layer has "fire-resistant" properties, which are ceramicized at high temperatures of 500°C or higher, so it can maintain its insulating and airtight properties within the battery pack even when flames are generated.

[0046] Thus, the fire-resistant busbar according to the present invention can achieve high fire resistance performance by incorporating fire-resistant silicone inside, along with structural improvements.

[0047] The above-mentioned refractory silicone is a composition mainly composed of silicone resin and metal oxide, and at room temperature, it possesses flexibility and pliability due to the properties of silicone. It also has a predetermined elastic force, exhibits high impact resistance and insulation, and when exposed to high temperatures, it can form a silicone sintered body with a complex ceramic structure through sintering of the silicone resin and metal oxide.

[0048] Specifically, the silicone resin contained in refractory silicone generates powdered silica when burned at high temperatures. This generated silica reacts with the metal oxide in the refractory silicone, forming a "eutectic mixture" at the edges of the metal oxide. This bridging action between the silica and the metal oxide causes it to harden at the ignition temperature, and upon cooling, it forms a condensed ceramic product. Such a ceramic body prevents short circuits and disconnections between conductors due to damage to the refractory silicone coating layer, even when subjected to external mechanical shock or moisture penetration during a fire, allowing the busbar itself to perform its electrical function.

[0049] For this purpose, the fire-resistant silicone according to the present invention comprises a silicone resin and a metal oxide.

[0050] The above-mentioned silicone resin is not particularly limited as long as it is a resin containing silicon (Si) in its molecule, but it may preferably include a silicone compound represented by the following chemical formula 1 (hereinafter referred to as "silicone compound of chemical formula 1"):

[0051]

number

[0052] In the above chemical formula 1, m and n are integers between 10 and 30.

[0053] The silicone compound of chemical formula 1 contains methylsiloxane repeating units, each containing vinyl groups both internally and at its ends. These vinyl groups are present not only at the ends of the silicone compound of chemical formula 1 but also internally within the repeating units, and play a role in increasing the degree of polymerization of the silicone resin when exposed to high temperatures. This allows for superior fire resistance compared to silicone compounds that do not contain vinyl groups.

[0054] Furthermore, the weight-average molecular weight of the silicone compound of chemical formula 1 can be adjusted to a specific range. The silicone compound of chemical formula 1 is a compound that forms the base of the silicone resin, and depending on the weight-average molecular weight of the silicone compound of chemical formula 1, it can affect the physical properties of the refractory silicone at room temperature and high temperature. For example, if the weight-average molecular weight of the silicone compound of chemical formula 1 is excessively high, the viscosity of the silicone resin may increase and the reactivity during high-temperature sintering may decrease. If the weight-average molecular weight is significantly low, the room-temperature elasticity and flexibility of the silicone resin may decrease, reducing the ease of manufacturing refractory busbars, while there is a limit to the impact resistance and other properties. Therefore, the silicone compound of chemical formula 1 according to the present invention may have a weight-average molecular weight adjusted to 1,000 to 9,000 g / mol, specifically 3,000 to 8,000 g / mol, or 5,000 to 7,000 g / mol.

[0055] Furthermore, the above-mentioned metal oxide is a composition containing silicon oxide, which acts as a crystal nucleus when exposed to high temperatures and can play a role in forming a high-density ceramic body together with the silicone resin described above.

[0056] Such metal oxides may include one or more of silicon dioxide, silica, quartz, silica, tridymite, and keatite. Because these metal oxides include minerals such as quartz, which contains silicon dioxide (SiO2) as its main component, along with pure silicon dioxide (SiO2), they are not only economically efficient but also possess high melting points (high refractory properties) and high sintering degrees, exhibiting excellent electrical insulation performance. In particular, silicon dioxide, silica, and quartz improve various properties during the sintering process, inducing easy melting and molding of refractory silicone and reducing defects that may occur in ceramic bodies.

[0057] Furthermore, the metal oxide may have a crystalline structure that increases fire resistance, insulation, and mechanical strength when sintered with the silicone resin. Such metal oxides are in powder form and are not particularly limited, but can be used that have a size of 200 μm or less, specifically, for example, 0.1 μm to 200 μm or 0.1 μm to 100 μm.

[0058] Furthermore, the above-mentioned silicone resin may further contain a silicone compound represented by the following chemical formula 2 (hereinafter referred to as the "silicone compound of chemical formula 2"), and the silicone compound of chemical formula 2, together with the silicone compound of chemical formula 1, participates in the sintering of metal oxides at high temperatures to form a silicone sintered body:

[0059]

number

[0060] In the chemical formula 2 above, p is an integer between 10 and 30.

[0061] The silicone compound of chemical formula 2 described above enhances the flexibility of refractory silicone at room temperature, while also inducing the termination of the sintering of the silicone resin through dehydration condensation with the silicone compound of chemical formula 1 during sintering, thereby terminating the ceramic body formation reaction.

[0062] For this reason, the silicone compound of chemical formula 2 described above may be used in amounts of less than 10 parts by weight per 100 parts by weight of refractory silicone, specifically in amounts of 0.5 to 9 parts by weight, 1 to 6 parts by weight, or 2 to 5 parts by weight.

[0063] Furthermore, refractory silicone may contain silicone resin and metal oxide in a certain ratio to achieve high elasticity at room temperature and rapid ceramic formation when exposed to high temperatures.

[0064] Specifically, the weight ratio of silicone resin to metal oxide in the above-mentioned refractory silicone may be 1:0.5 to 1.5, and more specifically, 1:0.8 to 1.2. If the weight ratio of metal oxide is low, less than 0.5, it is difficult to have a ceramic structure with a high-density crystalline structure at high temperatures, resulting in problems in achieving sufficient refractory properties and mechanical strength. On the other hand, if the weight ratio of metal oxide exceeds 1.5, the flexibility of the refractory silicone at room temperature is reduced, and there is a limit to how well it can be handled.

[0065] As one example, the refractory silicone of the present invention may contain 35-50% by weight of a silicone compound of chemical formula 1, 16-32% by weight of quartz, 10-27% by weight of silicon dioxide, and 1-6% by weight of a second silicone compound of chemical formula 2, and may optionally further contain a predetermined solvent to improve processability during manufacturing.

[0066] As described above, the refractory silicone of the present invention hardens and becomes ceramic at temperatures of 500°C or higher through sintering of the silicone resin and metal oxide. Furthermore, it can be ceramicized up to 1700°C, and theoretically, partial ceramicization can be maintained even at temperatures above 1700°C. However, above 1700°C, the ceramicization maintenance time shortens, and it may not be able to maintain the required refractory performance within the battery pack.

[0067] The above-mentioned refractory silicone, before being ceramicized, possesses rubber-like properties such as flexibility, elasticity, and flexibility, as described above. Therefore, it is easy to injection mold the refractory silicone coating layer as described later, or to coat it onto the busbar conductor.

[0068] Since the above-mentioned fire-resistant silicone coating layer is flexible before ceramicization, it can flexibly follow the deformation of the busbar conductor portion. Therefore, when the fire-resistant busbar of the present invention is installed in a battery pack, even if there are some assembly tolerances, they can be easily accommodated, thus improving ease of assembly. For example, when a battery module is fastened to a battery pack by bolting, if the busbar conductor portion connected to the battery module flows or twists slightly, the above-mentioned fire-resistant silicone coating layer can absorb such flow or twisting. Also, even if the battery pack vibrates due to vibrations of the electric vehicle, the above-mentioned fire-resistant silicone coating layer can naturally absorb those vibrations.

[0069] On the other hand, when the above-mentioned refractory silicone is ceramicized at high temperatures, thermal and electrical insulation is maintained, but the mechanical strength is somewhat weakened, and there is a risk of cracking due to external force. In this invention, in order to structurally improve the rigidity of such a refractory silicone coating layer, the present invention provides a metal sheet embedded in the refractory silicone coating layer and a protective layer surrounding the refractory silicone coating layer.

[0070] The protective layer described above surrounds the outside of the fire-resistant silicone coating layer, protecting it from direct exposure to flames. In other words, the protective layer primarily acts as a fire-resistant wall. Furthermore, when the fire-resistant silicone coating layer is ceramicized, the protective layer encases the ceramicized coating layer, maintaining its overall shape and dimensions.

[0071] For the protective layer, for example, a material such as glass fiber or mica that combines insulating and heat-resistant properties can be used. That is, glass fiber tape or mica tape can be wrapped around the outside of the fire-resistant silicone coating layer to prevent it from being exposed to the outside. However, the protective layer is not limited to these, and it is also possible to construct the protective layer from other materials that have excellent insulating or heat-resistant properties.

[0072] A metal sheet is embedded within the refractory silicone coating layer to reinforce its rigidity. The metal sheet, embedded within the refractory silicone coating layer, serves as a kind of framework. The refractory silicone coating layer is flexible and pliable before ceramicization, and therefore may be structurally fragile. For example, even after the refractory silicone coating layer is coated or applied to the busbar conductor and hardened, it may deform due to the properties of the material. However, when the metal sheet is provided within the refractory silicone coating layer, the metal sheet acts as a framework and structurally supports the coating layer.

[0073] In particular, when the refractory silicone coating layer is ceramicized at high temperatures, it can become brittle, potentially weakening its mechanical strength. In this case, the metal sheet structurally supports the ceramicized silicone, preventing deformation of the coating layer due to external forces. This allows the shape of the refractory silicone coating layer to be maintained, and also ensures that the insulating function of the coating layer is stably maintained. Furthermore, since the metal sheet is made of metal, it can also provide electromagnetic shielding, for example, when the refractory busbar is used as a high-voltage busbar. Therefore, the refractory busbar of the present invention, which incorporates a metal sheet, can be suitably used as a high-voltage busbar.

[0074] The above metal sheet may be made of, for example, one of the following metals: aluminum, steel, or stainless steel. However, it is not limited to these, and other suitable metal materials that can reinforce the rigidity of the fire-resistant silicone coating layer and have electromagnetic shielding properties may also be used.

[0075] The specific forms of the fire-resistant busbars and metal sheets will be described in detail in the following embodiments.

[0076] (First Embodiment) Figure 3 is a perspective view and a cross-sectional view of a fire-resistant busbar according to one embodiment of the present invention.

[0077] As shown in the figure, the fire-resistant busbar 100 has a busbar conductor portion 110 on its innermost side, and a covering portion P is provided on the portion of the busbar conductor portion 110 excluding both ends 111. Both ends 111 of the busbar conductor portion 110 are exposed to the outside and are provided with fastening holes 111a for connecting to corresponding electrical connection portions (e.g., terminal portions).

[0078] The above-mentioned covering portion P comprises a fire-resistant silicone coating layer 120 that surrounds the busbar conductor portion 110, and a protective layer 130 that surrounds the fire-resistant silicone coating layer 120. A metal sheet 140 is embedded in the fire-resistant silicone coating layer 120.

[0079] The fire-resistant silicone coating layer 120 described above can be formed transparent or opaque depending on the detailed configuration of the coating layer. In the perspective view of Figure 3, the fire-resistant silicone coating layer 120 is shown in a transparent state in order to clearly show the shape of the embedded metal sheet 140.

[0080] As shown in Figure 3, the metal sheet 140 extends along the fire-resistant silicone coating layer 120 that surrounds the busbar conductor portion 110 and is embedded in the fire-resistant silicone coating layer 120 so as to enclose the busbar conductor portion 110. That is, the metal sheet 140 extends along the fire-resistant silicone coating layer 120 like a skeleton. The thickness of the metal sheet 140 can be suitably determined according to the thickness of the coating layer 120, the composition and physical properties of the fire-resistant silicone coating layer 120, etc. In the case of a high-voltage busbar, the thickness of the metal sheet 140 can be set to the thickness required for electromagnetic wave shielding. For example, the metal sheet 140 can be manufactured with a thickness of 0.3 to 3 mm.

[0081] It is preferable to separate the metal sheet 140 and the busbar conductor portion 110 for insulation. In this case, as shown in the cross-sectional view of Figure 3, a fire-resistant silicone coating layer 120 is placed (filled) between the metal sheet 140 and the busbar conductor portion 110. Furthermore, a fire-resistant silicone coating layer 120 is provided between the outside of the metal sheet 140 and the protective layer 130. Therefore, the fire-resistant silicone coating layer 120 is located on the inside and outside of the metal sheet 140, with the metal sheet 140 as the boundary. In this case, the fire-resistant silicone coating layers 120 on the inside and outside of the metal sheet 140 can be blocked by the metal sheet 140. However, in order to make the bond between the metal sheet 140 and the fire-resistant silicone coating layer 120 stronger, it is more preferable to form the fire-resistant silicone coating layers 120 on the inside and outside of the metal sheet 140 so that they are connected to each other via the metal sheet 140.

[0082] For this purpose, as shown in Figure 3, through-holes 141 can be arranged in the metal sheet 140. In this case, the inner and outer refractory silicone coating layers 120 of the metal sheet 140 can be connected to each other through the through-holes 141. This allows the metal sheet 140 and the inner and outer refractory silicone coating layers 120 to be bonded more firmly as a single unit, thereby improving the structural rigidity of the refractory silicone coating layer 120. Therefore, when the refractory silicone coating layer 120 is ceramicized, the metal sheet 140 can support the coating layer 120 more firmly. Multiple through-holes 141 can be formed on the metal sheet 140 at intervals from each other. The through-holes 141 can have circular, square, or other shapes, and the size of the through-holes 141 can also be suitably selected.

[0083] The above-mentioned metal sheet 140 can be molded together with the above-mentioned refractory silicone coating layer 120. The molding of the above-mentioned refractory silicone coating layer 120, or the manufacturing process of the refractory busbar 100 of the present invention, will be described in detail in the following embodiments.

[0084] (Second Embodiment) Figure 4 is a schematic diagram showing an example of the manufacturing process of the fire-resistant busbar 100 of the present invention.

[0085] In this embodiment, the metal sheet 140 is molded together with the fire-resistant silicone coating layer 120.

[0086] The metal sheet 140 has, for example, a plurality of circular through holes 141. Fire-resistant silicone can be injected towards the metal sheet 140 from nozzles 151 of fire-resistant silicone storage tanks 150 located above and below the metal sheet 140. As described above, the fire-resistant silicone is, for example, a mixture of silicone resin and metal oxide, and can be in the form of a fluid coating liquid or slurry contained in a predetermined solvent. When such a fire-resistant silicone coating liquid is injected onto the upper and lower surfaces of the metal sheet 140, the upper and lower surfaces of the metal sheet 140 are coated with fire-resistant silicone, and at the same time, the through holes 141 are also filled with fire-resistant silicone. In this case, as shown in the drawing, the fire-resistant silicone on the upper and lower surfaces of the metal sheet 140 is integrally connected through the through holes 141 of the metal sheet 140. Since the injection of the fire-resistant silicone can be performed in a fixed mold, the metal sheet 140 and the fire-resistant silicone can be manufactured integrally by injection molding. The fire-resistant silicone coating layer 120 coated on the metal sheet 140 may, after drying and a predetermined curing process, possess physical properties similar to, for example, silicone rubber.

[0087] The integrated metal sheet 140 and the fire-resistant silicone coating layer 120 can be processed into a tape shape as shown in Figure 4. By winding such a fire-resistant silicone coating tape onto the busbar conductor portion 110, the busbar conductor portion 110 can be covered with the fire-resistant silicone coating layer 120. Next, by winding a protective layer 130, for example, a glass fiber tape, onto the fire-resistant silicone coating layer 120, the fire-resistant busbar 100 of the present invention can be manufactured.

[0088] The fire-resistant silicone coating tape can be wound onto the busbar conductor portion 110, and then the protective layer 130 tape can be wound on top. However, as shown in Figure 4, the protective layer 130 tape can be attached to the fire-resistant silicone coating tape beforehand to form the coating portion P. In this case, the fire-resistant busbar 100 can be manufactured in one step by winding the coating portion tape onto the busbar conductor portion 110, which has the advantage of shortening the manufacturing process.

[0089] In this embodiment, the covering portion P is made into a tape, and the tape of the covering portion P can be repeatedly wrapped around the busbar conductor portion 110 as needed, thereby further enhancing insulation and fire resistance. Furthermore, it is convenient to adjust the number of turns of the covering portion tape to adjust the insulation characteristics and fire resistance to match the design values.

[0090] However, in this embodiment, the flexibility of the metal sheet 140 may be a problem when processing it into a tape shape. If the thickness of the metal sheet 140 is made very thin, the metal sheet 140 can bend to follow the bending of the refractory silicone coating layer 120, but if the thickness of the metal sheet 140 is relatively thick, it may be difficult to roll it into a tape shape. The embodiment described below overcomes these manufacturing difficulties by pre-processing the shape of the metal sheet 140.

[0091] (Third embodiment) Figure 5 is a schematic diagram showing another example of the process for manufacturing the fire-resistant busbar 100 of the present invention.

[0092] In this embodiment, a refractory busbar 100 is manufactured by a type of insert injection molding method in which a metal sheet 140 and a busbar conductor portion 110 are pre-placed in a mold, and refractory silicone is injected into the mold.

[0093] In Figure 5, the busbar conductor portion 110 and the metal sheet 140 are placed in the upper and lower molds 160 and 160' for insert injection molding, so that the metal sheet 140 can enclose the busbar conductor portion 110 while being separated from it. Subsequently, a refractory silicone coating liquid or slurry is injected through the injection port 161 provided in the molds 160 and 160'. In this case, the refractory silicone fills the space between the metal sheet 140 and the busbar conductor portion 110 through the through-holes 141 in the metal sheet 140, and also fills the space between the outside of the metal sheet 140 and the molds 160 and 160'. After a predetermined drying and curing process, the molds are removed to obtain a coating layer with the busbar conductor portion 110 embedded in it, as shown in Figure 3. Subsequently, a protective layer 130 tape, such as a glass fiber tape or mica tape, is wrapped around the coating layer to obtain the refractory busbar 100 of the present invention.

[0094] In this embodiment, since the metal sheet 140 is pre-bent and processed to enclose the busbar conductor portion 110, a relatively thick metal sheet 140 can be easily applied. Furthermore, since the refractory silicone can be filled simultaneously on both the inside and outside of the metal sheet 140 through the through-holes 141, the manufacturing process is greatly simplified. In addition, the thickness of the refractory busbar coating layer 120 can be easily adjusted according to the size of the mold.

[0095] [Battery Pack] Figure 6 is a schematic diagram showing an example of a battery pack structure in which the fire-resistant busbar of the present invention is installed; Figure 7 is a schematic diagram showing another example of a battery pack structure in which the fire-resistant busbar of the present invention is installed; and Figure 8 is a side cross-sectional view showing the state in which the fire-resistant busbar of the present invention is installed in a battery pack.

[0096] The fire-resistant busbar 100 of the present invention described above comprises a fire-resistant silicone coating layer 120 that is ceramicized at high temperatures, a protective layer 130 that encloses the fire-resistant silicone coating layer 120 to maintain its shape, and a metal sheet 140 that reinforces the rigidity of the coating layer. Therefore, when applied to a battery pack in which internal ignition may occur, the safety of the battery pack can be greatly improved.

[0097] The fire-resistant busbar 100 described above can be used, for example, to electrically connect multiple battery modules housed within a battery pack. In this case, the fire-resistant busbar 100 can electrically connect the terminals of adjacent battery modules. Alternatively, the fire-resistant busbar 100 can be used to connect battery modules to external electrical devices.

[0098] In particular, the high-voltage terminals of a battery module generate relatively high heat due to the high current. As a result, when a flame occurs inside the pack, a high amount of heat can be concentrated at these high-voltage terminals. Therefore, the fire-resistant busbar 100 of the present invention is suitable for use as a high-voltage busbar that electrically connects the high-voltage terminals of multiple battery modules. Furthermore, since the fire-resistant busbar 100 is equipped with a metal sheet 140 that has an electromagnetic wave shielding function, it is even more suitable for use as a high-voltage busbar where electromagnetic wave shielding is particularly important.

[0099] The battery pack 1000 of the present invention may include a plurality of battery modules 200, flame-preventing partitions 300 installed between the battery modules, the fire-resistant busbars 100 described above that electrically connect the battery modules, and a pack housing 400 that houses the battery modules and the flame-preventing partitions.

[0100] Referring to Figure 6, it is shown that multiple battery modules 200 are housed in a pack housing 400. Each battery module 200 comprises a cell stack (not shown) in which multiple battery cells are stacked, and cell leads of different polarities are derived from each battery cell of the cell stack. These cell leads are electrically connected to or to bus bars such as terminal bus bars or interbus bars. To electrically connect the multiple battery modules, a fire-resistant bus bar 100 according to the present invention may be applied.

[0101] On the other hand, Figures 6 and 7 disclose a conventional battery module 200 in which the module housing completely encloses the top, bottom, left, and right sides of the battery cell stack. However, the fire-resistant busbar 100 of the present invention can also be applied to a battery module having a module housing with a moduleless structure configured such that at least one of the top, bottom, left, and right sides of the cell stack is open, or to a battery cell block in which all of the top, bottom, left, and right sides of the cell stack are open. In this way, a so-called cell-to-pack battery pack can be constructed by installing cell blocks or battery modules in which all or part of the module housing is omitted into a battery pack. The fire-resistant busbar 100 of the present invention can be used for electrical connection of cell blocks or moduleless battery modules installed in such a cell-to-pack battery pack.

[0102] To prevent flame propagation between adjacent modules, the battery pack 1000 may include flame-preventing partitions 300 installed between battery modules. The flame-preventing partitions 300 may be made of metal to ensure rigidity. The flame-preventing partitions 300 serve to prevent flames from spreading to adjacent modules in the event of a fire in one module. In this case, the flame-preventing partitions 300 may be provided with busbar installation through-holes 310 or busbar installation grooves 320. Figure 6 shows a flame-preventing partition 300 provided with busbar installation through-holes 310, and Figure 7 shows a flame-preventing partition 300 provided with busbar installation grooves 320. In terms of flame prevention and airtightness, a partition provided with busbar installation through-holes 310 as shown in Figure 6 is advantageous. The busbar installation grooves 320 in Figure 7 are open at the top, which is advantageous for busbar installation and electrical connection work of the busbars.

[0103] The fire-resistant busbar 100 can be fixed to the busbar installation through-hole 310 or the busbar installation groove 320. At this time, both ends 111 of the busbar conductor portion 110 can be electrically connected to the terminal portions 210 and 220 of the battery modules 200 located on both sides of the flame-preventing partition wall 300.

[0104] Figure 8 shows how the fire-resistant busbar 100 electrically connects the battery modules 200 within the battery pack 1000. A flame-preventing partition 300 is located between adjacent battery modules 200, and the flame-preventing partition is provided with a busbar installation through-hole 310. The fire-resistant busbar 100 of the present invention is inserted into the through-hole.

[0105] On the other hand, if a flame occurs inside the battery pack 1000, the fire-resistant busbar of the present invention undergoes ceramicization of the fire-resistant silicone coating layer 120 surrounding the busbar conductor portion 110, forming a dense sintered body. That is, unlike conventional heat-resistant silicones that become inflamed or turn to ash at temperatures above 500°C, it undergoes ceramicization and maintains its shape. As a result, the fire-resistant silicone coating layer 120 stably supports the busbar conductor portion 110 even when a flame occurs. At this time, the metal sheet 140 reinforces the rigidity of the fire-resistant silicone coating layer 120 and prevents cracking of the coating layer 120. Furthermore, the protective layer 130 prevents the fire-resistant silicone coating layer 120 from coming into direct contact with the flame, preventing deformation of the fire-resistant silicone and further enhancing its insulating and fire-resistant properties.

[0106] [Example of experiment]

[0107] (Experimental Example 1) A refractory silicone consisting of 50 parts by weight of the silicone compound of chemical formula 1, 20 parts by weight of quartz, and 30 parts by weight of pure silicon dioxide is applied to a thickness of 0.5 to 3 mm. 2 A copper busbar conductor section, having a predetermined cross-sectional area selected from a range of cross-sectional areas, was coated with a predetermined thickness, excluding both ends. The fire-resistant silicone coated busbar of Example 1 was manufactured by winding SWECO's 0.18 mm thick glass fiber tape (product name: AGTWO) twice around the above fire-resistant silicone coated busbar.

[0108] The length of the busbar conductor and the exposed length of both ends were made the same as in Example 1, and AGTWO glass fiber tape was wrapped around the center of the busbar conductor to manufacture the busbar of Comparative Example 2. The coating thickness of the wrapped glass fiber tape was made approximately the same as the coating thickness of Example 1.

[0109] For Comparative Example 2, a mica tape made of phlogopite mica, a natural mica material, was wrapped around the center of the busbar conductor, and then AGTWO glass fiber tape was wrapped over it. The length of the busbar conductor and the exposed length of both ends were the same as in Example 1 and Comparative Example 1.

[0110] To test the insulation properties (insulation maintenance performance) in the event of a fire, copper wire was wound around the busbars of Example 1 to Comparative Example 2 with the same number of turns. One end of the outermost copper wire of the busbar was connected to the negative terminal of a voltage withstand tester, and one end of the busbar conductor was connected to the positive terminal of the voltage withstand tester. With a voltage of 1000V applied to the busbars using the voltage withstand tester, the entire surface of the busbars was uniformly heated with a large torch with a flame temperature of 1100-1150°C.

[0111] The insulation failure time at which the insulation state is destroyed, i.e., a short circuit occurs, under the voltage and heating temperature conditions described above was measured, and the measurement results are shown in Table 1 below.

[0112] [Table 1]

[0113] As shown in Table 1 above, the busbar equipped with the coating layer according to the present invention had the longest insulation failure time, showing a significant difference in insulation failure time compared to Comparative Examples 1 and 2.

[0114] Therefore, it can be seen that the insulation properties of the fire-resistant busbar of the present invention, which is equipped with the fire-resistant silicone coating layer and protective layer described above, are excellent. Example 1 was a test of insulation performance without a metal sheet, and it can be said that the insulation performance against external high temperatures is further improved when a metal sheet is embedded in the fire-resistant silicone coating layer. In addition, when a metal sheet is installed, the mechanical strength of the ceramicized fire-resistant silicone coating layer is improved, and electromagnetic wave shielding function can also be obtained incidentally.

[0115] (Experimental Example 2) Fire-resistant silicones with compositions shown in Table 2 below were prepared by varying the weight ratio of the silicone compound of chemical formula 1 above to the weight ratio of the metal oxide.

[0116] Under the same conditions as in Experimental Example 1, a refractory silicone coating layer was applied to the copper busbar conductor to a predetermined thickness, and AGTWO glass fiber tape was wrapped around the refractory silicone coating layer.

[0117] Under the same conditions as in Experimental Example 1, copper wire was wound onto a refractory silicone coating layer and connected to a voltage withstand tester. With voltage applied, it was heated with a large torch under the same conditions as in Experimental Example 1, and the insulation failure time was measured. The measurement results are shown in Table 2 below.

[0118] [Table 2]

[0119] In Examples 1 to 5 described above, the weight ratios of the silicone compound to the metal oxide were 1:1, 1:0.5, 1:1.5, 1:0.4, and 1:1.6, respectively.

[0120] All examples exhibited significantly longer insulation fail times compared to Comparative Examples 1 and 2. However, in Example 4, where the weight percentage was less than 0.5, the insulation fail time was somewhat shorter, which is judged to be due to insufficient metal oxide and a slight lack of formation of a ceramic structure with a high-density crystalline structure at high temperatures.

[0121] Furthermore, in Example 5, where the weight ratio was 1.6, the insulation failure time was sufficiently long, but the excessive metal oxide reduced the flexibility of the refractory silicone at room temperature, making it difficult to conform to and coat the busbar conductor.

[0122] The present invention has been described in more detail above with reference to the drawings and embodiments. However, the configurations described in the drawings or embodiments described herein are merely one embodiment of the present invention and do not represent the entire technical concept of the present invention. Therefore, there may be various equivalents and modifications that can substitute for them at the time of filing. [Explanation of Symbols]

[0123] 100: Fireproof busbar 110: Busbar conductor section 120: Fire-resistant silicone coating layer 130: Protective layer 140: Metal sheet 141: Through Hole 150: Refractory silicone storage tank 160, 160': Upper and lower molds 200: Battery Module 210, 220: Terminal section 300: Flame prevention bulkhead 310: Busbar installation through-hole 320: Busbar mounting groove 400: Pack Housing 1000: Battery Pack

Claims

1. Busbar conductor section, A refractory silicone coating layer containing silicone resin and metal oxide encloses the portion of the busbar conductor excluding both ends, and is ceramicized to support the busbar conductor; The fire-resistant silicone coating layer includes a protective layer that encloses the aforementioned fire-resistant silicone coating layer, A fire-resistant busbar, wherein the fire-resistant silicone coating layer has a metal sheet embedded within it that reinforces the structural rigidity of the fire-resistant silicone coating layer.

2. The fire-resistant bus bar according to claim 1, wherein the fire-resistant silicone coating layer is ceramicized at a temperature of 500 to 1700°C.

3. The aforementioned refractory silicone coating layer is ceramicized by sintering a silicone resin containing a silicone compound represented by the following chemical formula 1 with a metal oxide containing silicon dioxide: [Math 1] The fire-resistant busbar according to claim 1, wherein in the chemical formula 1, m and n are each integers from 10 to 30.

4. The fire-resistant bus bar according to claim 3, wherein the silicone resin and metal oxide are contained in a weight ratio of 1:0.5 to 1.

5.

5. The refractory bus bar according to claim 3, wherein the silicon dioxide-containing metal oxide comprises one or more of pure silicon dioxide, silica, quartz, silica, tridymite, and keytite.

6. The fire-resistant busbar according to claim 1, wherein the metal sheet is embedded in the fire-resistant silicone coating layer so as to extend along the fire-resistant silicone coating layer that surrounds the busbar conductor portion and surround the busbar conductor portion.

7. The fire-resistant silicone coating layer is provided between the inside of the metal sheet and the busbar conductor portion. The fire-resistant silicone coating layer is provided between the outer surface of the metal sheet and the protective layer. The fire-resistant bus bar according to claim 6, wherein the fire-resistant silicone coating layers on the inside and outside of the metal sheet are connected via through holes formed in the metal sheet.

8. The fire-resistant bus bar according to claim 1, wherein the metal sheet is integrally formed with the fire-resistant silicone coating layer.

9. The aforementioned metal sheet has multiple through holes, The fire-resistant bus bar according to claim 8, wherein the metal sheet and the fire-resistant silicone coating layer are integrally formed by coating the upper and lower surfaces of the metal sheet with fire-resistant silicone and filling the through-holes with fire-resistant silicone.

10. The fire-resistant busbar according to claim 9, wherein the integral metal sheet and the fire-resistant silicone coating layer are processed into a tape shape, and the fire-resistant silicone coating layer covers the busbar conductor portion.

11. The metal sheet encloses the busbar conductor portion while being separated from the busbar conductor portion, The fire-resistant busbar according to claim 8, wherein the fire-resistant silicone coating layer comprising the metal sheet covers the busbar conductor portion.

12. The fire-resistant bus bar according to claim 1, wherein the protective layer is made of glass fiber or mica material.

13. The fire-resistant busbar according to claim 1, wherein the fire-resistant busbar is a high-voltage busbar that electrically connects the high-voltage terminals of a plurality of battery modules.

14. Multiple battery modules, A flame-preventing partition is installed between the aforementioned battery modules, A fire-resistant busbar according to any one of claims 1 to 13, electrically connecting the battery module, A battery pack comprising the aforementioned battery module and a pack housing that accommodates a flame-preventing partition.

15. The aforementioned flame-preventing partition wall is equipped with a busbar installation through-hole or busbar installation groove, The fire-resistant busbar is secured to the busbar installation through-hole or busbar installation groove. The battery pack according to claim 14, wherein both ends of the fire-resistant busbar are electrically coupled to the terminals of battery modules located on both sides of the flame-preventing partition.

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