Cap-integrated fireproof busbar and battery pack equipped with same

Abstract

The cap-integrated fire-resistant busbar of the present invention includes a busbar conductor portion, a cap portion covering both ends of the busbar conductor portion, a body covering portion covering a body of the busbar conductor portion between the both ends and integrally connected to the cap portion, a fire-resistant silicone covering body that is ceramicized at high temperature to support the busbar conductor portion, and a protective layer that covers the fire-resistant silicone covering body. The present invention also provides a battery pack including the cap-integrated fire-resistant busbar.

Description

[Technical field]

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

[0002] More specifically, the present invention relates to a cap-integrated fire-resistant busbar that includes a cap portion and a main body covering portion that is integrally connected to the cap portion, a fire-resistant silicone covering that is ceramicized at high temperatures, and a protective layer that encases the covering, thereby enabling the busbar to maintain its insulating and airtight properties even at high temperatures that could cause fire inside the battery pack, and a battery pack including the same.

[0003] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0140043 dated October 27, 2022, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference. [Background technology]

[0004] A battery pack applied to an electric vehicle or the like has a structure in which a number of battery modules, each including a plurality of secondary batteries, are connected in series or parallel to obtain high output. The secondary battery can be repeatedly charged and discharged by electrochemical reactions between components including positive and negative electrode current collectors, separators, active materials, electrolytes, etc.

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

[0006] FIG. 1 is a schematic diagram showing a conventional assembly structure of a bus bar and a cap.

[0007] As shown in the figure, a conventional busbar 10 is composed of a busbar conductor portion 11 and a coating layer 12 that encases the busbar conductor portion. The busbar conductor portion is, for example, a high-purity copper conductor portion such as C1100 or a metal conductor portion such as aluminum. The coating layer is made of a material such as ordinary silicone rubber or epoxy. Conventionally, a cap 20 has been attached to the coating layer 12 of the busbar 10 using a wear-resistant tape 30 or the like. The cap is formed separately so that it can be opened and closed freely when fastening members are fastened to fastening holes 11a at both ends of the busbar 10 to connect the busbar 10 to other electrical connecting portions.

[0008] However, the cap is made of soft rubber, which has poor insulation and is vulnerable to impact. Also, the process of connecting the bus bar 10 and the cap 20 with tape is complicated and has poor productivity. Furthermore, the wear-resistant tape 30 has poor fire resistance, so if it melts at high temperatures, the bus bar 10 and the cap 20 may not be fixed and may be separated.

[0009] In particular, when the components inside the battery pack are electrically connected with the conventional bus bar, if a fire occurs inside the battery pack, the temperature of the flame is so high (500 to 800°C, or over 800°C, and in severe cases over 1000°C), that not only the rubber cap but also the silicone rubber and epoxy coating layer melts, exposing the bus bar conductor to the outside. When this happens, the exposed bus bar conductor electrically contacts other metal parts inside the pack, causing a short circuit, and the heat generated by the electrical short causes the flame to spread further.

[0010] In order to prevent thermal propagation, a bus bar using a mica sheet, glass fiber, or heat-resistant silicone (rubber) as the covering layer may be considered.

[0011] However, in the above-mentioned intense heat generation situation, the above-mentioned materials cannot sufficiently prevent heat diffusion. For example, ordinary heat-resistant silicone rubber has a heat resistance temperature of only 125 to 300°C and cannot effectively deal with the ignition situation inside the battery pack. In addition, the covering layer made of mica sheet or glass fiber does not have sufficient fire resistance.

[0012] Thus, recent battery packs are required to be designed in such a way that in the event of an internal fire, flames will not escape to the outside of the pack.

[0013] In addition, a design is required that can thermally and electrically insulate the bus bar conductor from its surroundings even at high temperatures when a flame breaks out inside the battery pack.

[0014] In view of the above, it can be said that there is a demand for the development of a technology that can improve the insulating strength and ease of assembly while maintaining electrical insulation properties by providing fire resistance at high temperatures. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] Korean Patent Publication No. 2022-0001228 Summary of the Invention [Problem to be solved by the invention]

[0016] The present invention provides a fire-resistant busbar that can maintain thermal and electrical insulation for as long as possible even in the event of a fire inside a battery pack.

[0017] Another object of the present invention is to provide a cap-integrated fire-resistant busbar in which not only the body covering portion of the busbar conductor but also the cap portions covering both ends of the busbar conductor are integrated together.

[0018] The present invention also provides a battery pack including the above-mentioned fire-resistant bus bar. [Means for solving the problem]

[0019] In order to solve the above-mentioned problems, the cap-integrated fire-resistant busbar of the present invention includes a busbar conductor portion, a cap portion covering both end portions of the busbar conductor portion, and a body covering portion that covers a body of the busbar conductor portion between the both end portions and is integrally connected to the cap portion, and also includes a fire-resistant silicone covering that is ceramicized at high temperature to support the busbar conductor portion, and a protective layer that covers the fire-resistant silicone covering.

[0020] The fire-resistant silicone can be ceramicized at a temperature of 500 to 1700°C.

[0021] The fire-resistant silicone can be made into a ceramic 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 integers of 10 to 30, respectively.

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

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

[0026] The protective layer can be a fiberglass layer or a mica layer.

[0027] A space for accommodating a fastening member is formed within the cap portion.

[0028] The protective layer may be provided on an inner circumferential surface of the cap portion.

[0029] The protective layer may not be provided on the side of the fireproof silicone covering at the portion where the cap portion and the body covering portion are connected, and the protective layer may be provided only on the top surface of the connecting portion.

[0030] The bus bar conductor portion can be covered with the fire-resistant silicone covering by insert injection molding in which the fire-resistant silicone is injected into a mold in which the bus bar conductor portion is inserted.

[0031] The cap-integrated fireproof bus bar may be a high-voltage bus bar that electrically connects high-voltage terminal portions of a plurality of battery modules.

[0032] According to another aspect of the present invention, a battery pack includes a plurality of battery modules, fire prevention partitions installed between the battery modules, the above-mentioned cap-integrated fireproof bus bar electrically connecting the battery modules, and a pack housing accommodating the battery modules and the fire prevention partitions.

[0033] The flame prevention partition may include a busbar installation through-hole or a busbar installation groove, the cap-integrated fireproof busbar may be seated in the busbar installation through-hole or the busbar installation groove, both ends of the busbar conductor portion of the cap-integrated busbar may be electrically coupled to terminal portions of the battery modules located on both sides of the flame prevention partition, and a cap portion of the cap-integrated busbar may cover a coupling portion between the both ends and the terminal portions. Effect of the Invention

[0034] The fire-resistant busbar of the present invention is provided with a fire-resistant silicone coating that is ceramicized to support the busbar conductor portion instead of a coating layer that will not burn in the event of a flame breaking out inside the pack, and therefore can maintain its insulating and airtight properties even at high temperatures.

[0035] Furthermore, the fire-resistant busbar of the present invention has a body covering portion of the busbar conductor and a cap portion covering both ends of the busbar conductor formed as a single unit. This not only simplifies the production of the busbar and the cap, but also significantly improves the connection strength between the busbar and the cap.

[0036] The cap may also be constructed from fire-resistant silicone to further enhance the insulating and fire-resistant airtight properties of the cap.

[0037] In addition, the fire-resistant busbar of the present invention includes a protective layer covering the fire-resistant silicone coating, and the protective layer serves as a primary fire-resistant barrier while preventing the fire-resistant silicone coating from being directly exposed to flames, thereby allowing the fire-resistant busbar to maintain its overall shape and dimensions. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a schematic diagram showing a conventional assembly structure of a bus bar and a cap. [Diagram 2] FIG. 1 is a perspective view of a cap-integrated fireproof bus bar according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a side cross-sectional view of a cap-integrated fireproof bus bar according to an embodiment of the present invention. [Figure 4] FIG. 2 is a plan view of a cap-integrated fireproof bus bar according to an embodiment of the present invention. [Diagram 5] 1 is a photograph of a glass fiber layer included in a cap-integrated fire-resistant bus bar of the present invention. [Figure 6] FIG. 11 is a side cross-sectional view of a cap-integrated fire-resistant bus bar according to another embodiment of the present invention. [Figure 7] FIG. 13 is a perspective view of a cap-integrated fire-resistant bus bar according to another embodiment of the present invention. [Figure 8] FIG. 1 is a schematic diagram showing an example of a battery pack structure in which the cap-integrated fireproof bus bar of the present invention is installed. [Figure 9] FIG. 11 is a schematic diagram showing another example of a battery pack structure in which the cap-integrated fireproof bus bar of the present invention is installed. [Figure 10]1 is a perspective view showing a process in which the cap-integrated fireproof bus bar of the present invention is installed in a battery pack; FIG. [Figure 11] FIG. 2 is a side cross-sectional view showing a state in which the cap-integrated fireproof bus bar of the present invention is installed in a battery pack. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Hereinafter, detailed configurations of the present invention will be described in detail with reference to the attached drawings and various embodiments. The embodiments described below are illustratively shown to facilitate understanding of the present invention, and the attached drawings are not drawn to actual scale to facilitate understanding of the invention, and the dimensions of some components may be exaggerated.

[0040] Since the present invention can be modified in various ways and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text, but this is not intended to limit the present invention to the specific disclosed forms, and it is understood that the present invention includes all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0041] [Fireproof busbar with integrated cap] The cap-integrated fire-resistant busbar of the present invention includes a busbar conductor portion, a cap portion covering both end portions of the busbar conductor portion, and a body covering portion covering the body of the busbar conductor portion between the both end portions and integrally connected to the cap portion, and also includes a fire-resistant silicone covering body that is ceramicized at high temperature to support the busbar conductor portion, and a protective layer that covers the fire-resistant silicone covering body.

[0042] The busbar conductor portion may be a normal 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 may be manufactured from an aluminum material. That is, the busbar conductor portion of the present invention is not particularly limited as long as it is a metal material that can function as a busbar conductor for connecting electrical components. Both ends of the busbar conductor portion are electrically connected to corresponding electrical connection portions.

[0043] The fire-resistant silicone covering body includes a cap portion which covers both ends of the bus bar conductor portion, and a body covering portion which encases the body of the bus bar conductor portion between the both ends and is integrally connected to the cap portion.

[0044] This fire-resistant silicone coating is ceramicized at high temperatures to support the bus bar conductor. 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-resistant temperature of less than 300°C, in that it has a fire-resistant temperature of 500°C or higher. Heat-resistant silicone is a silicone resin or rubber composition that has flexibility and pliability due to the characteristics of silicone, but it is a material that does not burn or turns to ash at high temperatures of 500°C or higher. Therefore, there is a limit to its application in preventing short circuits of battery packs in heat propagation conditions or preventing heat propagation.

[0045] The fire-resistant silicone covering has a "fire-resistant" property of being ceramicized at high temperatures of 500°C or more, and therefore can maintain insulating properties and airtight properties within the battery pack even in the event of a flame.

[0046] In this manner, the fire-resistant busbar according to the present invention can realize high fire resistance by providing fire-resistant silicone inside as well as structural improvements.

[0047] The fire-resistant silicone is a composition mainly composed of silicone resin and metal oxide, and has softness and flexibility due to the characteristics of silicone at room temperature. It also has a certain elasticity, shows high impact resistance and insulation, and when exposed to high temperatures, it can form a silicone sintered body with a complex ceramic structure by sintering the silicone resin and metal oxide.

[0048] Specifically, the silicone resin contained in the fireproof silicone generates powdered silica when burned at high temperatures. The silica thus generated reacts with the metal oxide of the fireproof silicone to form a "eutectic mixture" at the edge of the metal oxide, thereby performing a bridging role between the silica and the metal oxide, so that it hardens at the ignition temperature and forms a condensed ceramic product when cooled. Such a ceramic body prevents short circuits or disconnections between conductors due to damage to the fireproof silicone coating even when an external mechanical impact is applied during a fire or moisture penetrates, and the busbar itself can perform its electrical function.

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

[0050] The silicone resin is not particularly limited as long as it is a resin containing silicon (Si) in the molecule, but preferably contains 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 of 10 to 30, respectively.

[0053] The silicone compound of formula 1 contains a methylsiloxane repeating unit and a vinyl group at the inside and end of the methylsiloxane repeating unit. The vinyl group is present not only at the end of the silicone compound of formula 1 but also inside the repeating unit, and plays a role in increasing the degree of polymerization of the silicone resin when exposed to high temperatures, thereby achieving better fire resistance than silicone compounds that do not contain vinyl groups.

[0054] In addition, the silicone compound of Chemical Formula 1 may have a weight average molecular weight adjusted to a specific range. The silicone compound of Chemical Formula 1 is a compound that forms the base of a silicone resin, and may affect the physical properties of the fireproof silicone at room temperature and high temperature depending on the weight average molecular weight of the silicone compound of Chemical Formula 1. 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, and if the weight average molecular weight is significantly low, the elasticity and flexibility of the silicone resin at room temperature may decrease, and the manufacturing processability of the fireproof busbar may decrease, while there is a limit to the decrease in impact resistance, etc. 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] In addition, the metal oxide is a composition containing silicon oxide, and when exposed to high temperatures, it acts as a crystal nucleus 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 stone, tridymite, and keatite. The metal oxides include minerals such as quartz containing silicon dioxide (SiO2) as a main component as well as pure silicon dioxide (SiO2), and therefore are not only highly economical but also have a high melting point (high fire resistance) and a high sintering degree, and can exhibit excellent electrical insulation performance. In particular, silicon dioxide, silica, quartz, etc. can improve various performances during the sintering process, induce easy melting and molding of the fireproof silicone, and reduce defects that may occur in the ceramic body.

[0057] The metal oxide may have a crystal structure that increases fire resistance, insulation, mechanical strength, etc., when sintered with the silicone resin. Such metal oxide is in a powder form, and although there is no particular limitation, one having a size of 200 μm or less, specifically, for example, 0.1 μm to 200 μm or 0.1 μm to 100 μm can be used.

[0058] The silicone resin may further include a silicone compound represented by the following formula 2 (hereinafter, referred to as "silicone compound of formula 2"). The silicone compound of formula 2, together with the silicone compound of formula 1, participates in the sintering of metal oxide at high temperatures to form a silicone sintered body:

[0059]

number

[0060] In the above Chemical Formula 2, p is an integer of 10-30.

[0061] The silicone compound of Formula 2 increases the flexibility of the fireproof silicone at room temperature, while at the same time inducing the termination of sintering of the silicone resin by dehydration condensation with the silicone compound of Formula 1 during sintering, thereby terminating the reaction of forming a ceramic body.

[0062] For this reason, the silicone compound of Formula 2 may be used in an amount of less than 10 parts by weight, specifically 0.5 to 9 parts by weight, 1 to 6 parts by weight, or 2 to 5 parts by weight, based on 100 parts by weight of the fire-resistant silicone.

[0063] In addition, the fireproof silicone may contain a certain ratio of silicone resin and metal oxide to realize high elasticity at room temperature and to rapidly form a ceramic body when exposed to high temperature.

[0064] Specifically, the weight ratio of the silicone resin to the metal oxide in the fireproof silicone may be 1:0.5-1.5, specifically 1:0.8-1.2. If the weight ratio of the metal oxide is less than 0.5, it is difficult to obtain a ceramic structure having a high density crystal structure at high temperatures, and there is a problem that fire resistance and mechanical strength are not sufficiently realized. In addition, if the weight ratio of the metal oxide exceeds 1.5, the flexibility of the fireproof silicone at room temperature is reduced, and there is a limit to good handling.

[0065] As one example, the fireproof silicone of the present invention may contain 35 to 50% by weight of a silicone compound of Chemical Formula 1, 16 to 32% by weight of quartz, 10 to 27% by weight of silicon dioxide, and 1 to 6% by weight of a second silicone compound of Chemical Formula 2, and in some cases, may further contain a predetermined solvent to improve processability during production.

[0066] As described above, the fire-resistant silicone of the present invention is cured and ceramicized by sintering the silicone resin and metal oxide at 500° C. or higher. It can also be ceramicized up to 1700° C., and theoretically can maintain partial ceramicization even at temperatures above 1700° C. However, if the temperature exceeds 1700° C., the ceramicization time is shortened and the required fire resistance in the battery pack may not be maintained.

[0067] As described above, the fireproof silicone has rubber-like properties, including flexibility, softness, and elasticity, before being ceramified, so that the fireproof silicone coating can be easily injection molded or coated onto the busbar conductor as described below.

[0068] The fireproof silicone coating has flexibility before being ceramized, and can flexibly follow deformation of the busbar conductor. Therefore, when the fireproof busbar of the present invention is installed in a battery pack, even if there is a slight assembly tolerance, it can be easily accommodated, improving assembly. For example, when a battery module is fastened to a battery pack by bolting, if the busbar conductor connected to the battery module flows or twists slightly, the fireproof silicone coating can absorb such flow or twist. In addition, even if the battery pack vibrates due to vibration of the electric vehicle, the fireproof silicone coating can naturally absorb the vibration.

[0069] In particular, the cap-integrated fireproof busbar of the present invention is characterized in that the fireproof silicone covering includes not only the body covering part that encases the body part of the busbar conductor part, but also the cap part that covers both ends of the busbar conductor part. Since the cap part is connected integrally with the body covering part, it is not necessary to connect the cap part to the busbar with a separate tape as in the past. Therefore, the connection strength between the cap part and the body covering part is greatly improved. In addition, since the cap part and the body covering part can be integrally molded to manufacture the cap-integrated fireproof busbar, the manufacturing process is simplified. Furthermore, since the cap part is made of fireproof silicone, the cap part can also be ceramicized at high temperatures to protect both the busbar conductor part and its electrical connection part, thereby further enhancing the insulation performance and airtightness characteristics.

[0070] On the other hand, when the fireproof silicone is ceramified at high temperatures, the 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 the present invention, in order to structurally improve the rigidity of such a fireproof silicone coating, a protective layer is provided to cover the fireproof silicone coating.

[0071] The protective layer is a layer that covers the exterior of the fireproof silicone coating and protects the fireproof silicone coating from being directly exposed to flames. That is, the protective layer primarily serves as a fireproof wall. When the fireproof silicone coating is ceramified, the protective layer encases the ceramified coating and maintains the overall shape and dimensions of the coating.

[0072] The protective layer may be made of, for example, glass fiber or mica material that has both insulating and heat resistance. For example, a glass fiber tape or mica tape may be wrapped around the outside of the fireproof silicone coating to prevent the fireproof silicone coating from being exposed to the outside. However, the protective layer is not limited to this, and the protective layer may be made of other materials that have excellent insulating or heat resistance.

[0073] Specific configurations of the cap-integrated fire-resistant busbar will be described in detail in the following embodiments.

[0074] (First embodiment) Fig. 2, Fig. 3 and Fig. 4 are a perspective view, a side cross-sectional view and a plan view of a cap-integrated fire-resistant busbar according to an embodiment of the present invention. Fig. 5 is a photograph showing a glass fiber layer included in the cap-integrated fire-resistant busbar of the present invention.

[0075] As shown in the figure, the cap-integrated fireproof busbar 100 includes a busbar conductor portion 110 at its innermost portion. Both ends 111 of the busbar conductor portion 110 may be exposed to the outside and include fastening holes 111a for coupling with corresponding electrical connecting portions (e.g., the busbar conductor portion 110 of another fireproof busbar, or the terminal portions 210, 220 of a battery module) using fastening members B.

[0076] A central covering portion P is provided on a main body portion excluding both end portions 111 of the bus bar conductor portion 110. Caps C are provided on both end portions 111 of the bus bar conductor portion 110. The caps C are connected to the central covering portion P.

[0077] 3, the cap C includes a fireproof silicone covering and a protective layer. The central covering portion P also includes a fireproof silicone covering and a protective layer. That is, the fireproof silicone covering 120 includes a cap portion 121 that forms the main body of the cap, and a main body covering portion 122 that encases the main body of the bus bar conductor portion 110, and the cap portion 121 and the main body covering portion 122 are integrally connected.

[0078] Moreover, the protective layer 130 includes a cap protective layer 131 that covers the cap portion 121 , and a body protective layer 132 that covers the body covering portion 122 .

[0079] An accommodation space S for the fastening member B is formed in the cap C or the cap portion 121. Therefore, as shown in FIG. 3, when the fastening member B penetrates the fastening hole 111a of the cap-integrated fire-resistant busbar 100 and is coupled to a corresponding electrical connection portion (e.g., the busbar conductor portion 110 of another fire-resistant busbar, or the terminal portion 210, 220 of a battery module), an exposed end portion of the fastening member B can be accommodated in the accommodation space S in the cap C or the cap portion 121. As a result, the fastening member B is protected by the cap portion 121, and a short circuit due to contact with other external components can be prevented. As shown in the drawings, the accommodation space S may have a sufficient space to accommodate the fastening member B. If necessary, a coupling member (e.g., a nut: not shown) corresponding to the fastening member B may be installed in the accommodation space S. In this case, the nut and the end portion of the fastening member B may be firmly coupled to each other by screw coupling. Alternatively, if necessary, the size of the accommodation space S may be reduced so that the end portion of the fastening member B is firmly fitted into the accommodation space. This allows the fastening member B and the cap portion 121 to be more firmly coupled together, and the cap portion 121 can reliably cover the cap-integrated fire-resistant busbar 100 and the corresponding electrical connection portion. The cap portion 121 may include a base portion 121a and a fastening member insertion portion 121b extending upward from the base portion 121a and having an accommodation space S for the fastening member therein. In the above drawings, the base portion 121a is shown to cover the upper and side surfaces of both ends of the busbar conductor portion. However, if necessary, the base portion 121a may be expanded to be large enough to cover the side surfaces of the busbar conductor portion and the corresponding electrical connection portion.

[0080] The cap portion 121 and the main body covering portion 122 of the fireproof silicone-coated body 120 may be integrally molded. For example, the fireproof silicone-coated body 120 may be molded by injecting fireproof silicone into a mold (not shown) having the shapes of the cap portion 121 and the main body covering portion 122 of the fireproof silicone-coated body 120. As described above, the fireproof silicone may be, for example, a mixture of silicone resin and metal oxide, and may be in the form of a coating liquid or slurry having fluidity by being contained in a predetermined solvent. Such a fireproof silicone coating liquid or slurry may be injected into a mold to mold the fireproof silicone-coated body 120 separately from the busbar conductor portion 110. After a predetermined drying and curing process, the mold is removed to obtain the fireproof silicone-coated body 120 according to the present invention.

[0081] In this case, the bus bar conductor portion 110 is longitudinally fitted into the main body covering portion 122 of the molded fire-resistant silicone covering body 120, so that the main body covering portion 122 is enveloped in the main body of the bus bar conductor portion 110. At this time, the cap portions 121 of the molded fire-resistant silicone covering body 120 are positioned on both end portions 111 of the bus bar conductor portion 110 to cover both end portions.

[0082] As described above, the fireproof silicone coating 120 can be molded separately from the busbar conductor portion 110 and then joined to the busbar conductor portion 110, but the molding of the fireproof silicone coating 120 and the coating of the busbar conductor portion 110 can be performed simultaneously by a so-called insert injection method. The latter method can further simplify the manufacturing process, thereby improving productivity.

[0083] That is, the fireproof silicone coating liquid or slurry is injected into a mold (not shown) for insert injection molding in which the busbar conductor portion 110 is inserted and the edge of the busbar conductor portion is provided with the shape of the fireproof silicone coating. In this case, the fireproof silicone is filled into the mold while enveloping the busbar conductor portion 110, forming the fireproof silicone coating 120 having the above-mentioned shape. When the mold is removed after a predetermined drying and curing process, the fireproof silicone coating 120 having the busbar conductor portion 110 embedded therein can be obtained as shown in FIG. 3.

[0084] 4 and 5, a protective layer 130 is provided on the fire-resistant silicone coating 120. For example, a tape such as a glass fiber tape or a mica tape for the protective layer 130 is wound on the fire-resistant silicone coating 120 to obtain the cap-integrated fire-resistant busbar 100 of the present invention. In the drawings of this specification, the protective layer 130 exposed to the outside is shown in a lattice-like mesh pattern.

[0085] The protective layer 130 is also adapted to match the shape of the cap portion 121. That is, the protective layer 130 may include a base portion protective layer 131a that covers the base portion 121a, and an insertion portion protective layer 131b that covers the fastening member insertion portion 121b.

[0086] For example, a material such as glass fiber or mica having both insulating and heat-resistant properties may be used as the protective layer 130. That is, a glass fiber tape or a mica tape may be wrapped around the outside of the fireproof silicone coating to prevent the fireproof silicone coating from being exposed to the outside. A photograph of the glass fiber layer is shown in FIG. 5.

[0087] Glass fiber is an inorganic fibrous material mainly made of silicate. Such glass fiber can be made into a glass fiber fabric by weaving a yarn made by twisting and winding glass fiber strands (see FIG. 5(a)) or into a nonwoven fabric (see FIG. 5(b)). A certain adhesive can be applied to such glass fiber fabric or nonwoven fabric and attached onto the above-mentioned fire-resistant silicone coating 120 to produce the cap-integrated fire-resistant busbar 100 of the present invention. Glass fiber has the advantages of being fire-resistant and having high electrical insulation.

[0088] Mica is a type of silicate mineral, has a layered structure, and usually has a hexagonal plate-like crystal form, and is used as an electrical insulator or heat insulating material. Mica has better fire resistance than the above-mentioned glass fiber. Therefore, mica is more preferable as a protective layer for protecting the fire-resistant silicone coating layer. However, the protective layer is not limited to this, and the protective layer can also be made of other materials with excellent insulating properties or heat resistance.

[0089] For example, the protective layer 130 may be formed by wrapping a tape of the protective layer 130 processed into a tape shape on the fire-resistant silicone covering. However, the method of forming the protective layer 130 is not limited thereto. For example, the protective layer 130 may be formed on the covering by coating, painting, spraying, or other various known methods.

[0090] Second embodiment FIG. 6 is a side cross-sectional view of a cap-integrated fire-resistant bus bar according to another embodiment of the present invention.

[0091] In the cap-integrated fire-resistant busbar 100' of this embodiment, the cap protective layer 131' is provided up to the inner circumferential surface of the cap portion 121. That is, while there is no protective layer on the inner circumferential surface of the cap portion that is not exposed to the outside in the embodiment of Fig. 3, in this example, the cap protective layer 131' such as a glass fiber tape or a mica tape is provided also on the inner circumferential surface of the cap portion 121.

[0092] In the case where both the inner and outer circumferential surfaces of the cap portion 121 are covered with the cap protective layers 131, 131' as in the second embodiment, the following advantages are obtained.

[0093] The protective layers 131, 131' on the inner and outer periphery of the cap portion act as a primary fireproof barrier to ensure that the fireproof silicone coating of the cap portion 121 is not exposed to flames.

[0094] In addition, since the cap protective layers 131, 131' on the inner and outer periphery completely encase the fireproof silicone coating placed therebetween, even if the cap portion 121 is ceramicized at high temperatures and its strength is somewhat reduced, the cap protective layers support the cap portion, and the shape and dimensions of the cap portion can be more stably maintained.

[0095] Third embodiment FIG. 7 is a perspective view of a cap-integrated fire-resistant bus bar according to another embodiment of the present invention.

[0096] The cap-integrated fire-resistant busbar 100'' of this embodiment differs from the first and second embodiments in that the protective layer 130 is not provided on the side surface of the fire-resistant silicone coating 120 at the portion 123 connecting the cap portion 121 and the main body coating portion 122.

[0097] That is, in this embodiment, the protective layer 130 is provided only on the upper surface of the connecting portion 123. As shown in the bottom drawing of Fig. 2, the cap C or cap portion 121 is lifted up from the bus bar conductor portion 110 or lowered toward the bus bar conductor portion 110 as needed for the fastening operation. That is, the portion 123 connecting the cap C or cap portion 121 and the main body covering portion 122 is folded up as needed. In this case, if the entire connecting portion 123 is covered with a relatively hard protective layer 130 (e.g., glass fiber or mica), the processability of the fastening operation may be deteriorated.

[0098] In this embodiment, the processability of the fastening operation is improved by not providing the protective layer 130 on both side surfaces of the connecting portion 123. If necessary, in order to further improve the processability, the protective layer 130 may also not be provided on the upper surface of the connecting portion 123. However, in this case, the connecting portion 123 does not have any protective layer at all, and the fire resistance may be reduced. From the above, whether or not to provide a protective layer on the connecting portion 123 and to what extent the protective layer should be formed must be appropriately determined in consideration of the processability and fire resistance.

[0099] [Battery pack] FIG. 8 is a schematic diagram showing an example of a battery pack structure in which the cap-integrated fire-resistant busbar of the present invention is installed, FIG. 9 is a schematic diagram showing another example of a battery pack structure in which the cap-integrated fire-resistant busbar of the present invention is installed, and FIGS. 10 and 11 are an oblique view and a side cross-sectional view showing the state in which the cap-integrated fire-resistant busbar of the present invention is installed in a battery pack.

[0100] The above-described cap-integrated fire-resistant busbars 100, 100', 100'' of the present invention include a fire-resistant silicone coating 120 that is ceramicized at high temperatures, and a protective layer 130 that encases the fire-resistant silicone coating 120 and maintains its shape. Therefore, when applied to a battery pack in which internal fire may occur, the safety of the battery pack can be significantly improved.

[0101] The cap-integrated fire-resistant busbar 100, 100', 100'' may be used, for example, to electrically connect a plurality of battery modules housed in a battery pack to each other. In this case, the cap-integrated fire-resistant busbar may electrically connect terminal portions of adjacent battery modules. Alternatively, the cap-integrated fire-resistant busbar may be used to connect a battery module to an external electric device.

[0102] In particular, the high voltage terminal of the battery module generates relatively high heat due to a high current. As a result, when a fire occurs inside the pack, high heat may be concentrated on the high voltage terminal. Therefore, the cap-integrated fire-resistant bus bar of the present invention is suitable for use as a high voltage bus bar that electrically connects the high voltage terminals of a plurality of battery modules.

[0103] The battery pack 1000 of the present invention may include a plurality of battery modules 200, fire prevention partitions 300 installed between the battery modules, the above-described cap-integrated fireproof busbars 100, 100', 100'' that electrically connect the battery modules, and a pack housing 400 that accommodates the battery modules and the fire prevention partitions.

[0104] 8, a plurality of battery modules 200 are accommodated in a pack housing 400. The battery module 200 includes a cell stack (not shown) in which a plurality of battery cells are stacked, and cell leads of different polarities are led out from the battery cells of the cell stack. The cell leads are electrically connected to a bus bar, such as a terminal bus bar or an inter bus bar, or to a bus bar. A cap-integrated fireproof bus bar according to the present invention may be applied to electrically connect the plurality of battery modules.

[0105] Meanwhile, in Figs. 8 and 9, a typical battery module 200 is disclosed in which the module housing completely surrounds the top, bottom, left and right sides of the battery cell stack. However, the present invention is not limited thereto, and the cap-integrated fire-resistant busbar of the present invention may be applied to, for example, a battery module having a module housing of a moduleless structure in which 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 the entire top, bottom, left and right sides of the cell stack are open. In this way, a cell block or a battery module in which all or part of the module housing is omitted may be installed in a battery pack to configure a so-called cell-to-pack battery pack. The cap-integrated fire-resistant busbar 100, 100', 100'' of the present invention may be used for electrical connection of the cell block or the module-less battery module installed in such a cell-to-pack battery pack.

[0106] In order to prevent flame propagation between adjacent modules, the battery pack 1000 may include a fire prevention partition 300 installed between the battery modules. The fire prevention partition 300 may be made of a metal material to ensure rigidity. The fire prevention partition 300 serves to prevent flame propagation to an adjacent module when a fire occurs in one module. In this case, the fire prevention partition 300 may be provided with a busbar installation through hole 310 or a busbar installation groove 320. FIG. 8 shows that the fire prevention partition 300 is provided with a busbar installation through hole 310, and FIG. 9 shows that the fire prevention partition 300 is provided with a busbar installation groove 320. In terms of fire prevention and airtightness, a partition provided with the busbar installation through hole 310 as shown in FIG. 8 is advantageous. The busbar installation groove 320 in FIG. 9 has an open upper portion, which is advantageous for performing busbar installation and electrical connection work of the busbar.

[0107] The fireproof busbars 100, 100′, 100″ may be seated in the busbar installation through-holes 310 or the busbar installation grooves 320. In this case, both ends 111 of the busbar conductor part of the cap-integrated fireproof busbar may be electrically coupled to terminal parts 210, 220 of the battery modules 200 located on both sides of the fire prevention partition 300.

[0108] 10 and 11 show how the cap-integrated fire-resistant busbar 100 electrically connects the battery modules 200 in the battery pack 1000. A fire prevention partition 300 is positioned between adjacent battery modules 200, and the fire prevention partition has a busbar installation groove 320. The cap-integrated fire-resistant busbar 100 of the present invention is seated on the busbar installation groove 320. The shape of the cap-integrated fire-resistant busbar 100 is formed corresponding to the shape of the busbar installation groove 320. Therefore, the cap-integrated fire-resistant busbar 100 of the present invention can be surface-attached to the fire prevention partition 300 in an airtight manner. This can further improve the airtightness of the battery pack.

[0109] The cap C integrally provided on the cap-integrated fireproof busbar 100 covers the joint between the both ends 111 and the terminal parts 210 and 220. Therefore, it is not necessary to separately connect a cap to the busbar as in the conventional case, and the installation of the fireproof busbar and the cap joint work can be performed simultaneously.

[0110] Meanwhile, in the case where a flame occurs in the battery pack 1000, the cap-integrated fire-resistant busbar 100 of the present invention forms a dense sintered body by simultaneously ceramicizing the main body covering portion 122 and the cap portion 121 that encase the busbar conductor portion 110. That is, unlike conventional heat-resistant silicone, which does not burn or turn to ash at a high temperature of 500°C or more, the fire-resistant silicone covering 120 is ceramicized and maintains its shape. As a result, the fire-resistant silicone covering 120 stably supports the busbar conductor portion 110 even when a flame occurs. In addition, the protective layer 130 prevents the fire-resistant silicone covering 120 from coming into direct contact with the flame, thereby preventing deformation of the fire-resistant silicone, and further strengthens the insulation and fire resistance.

[0111] [Experimental Example]

[0112] (Experimental Example 1) A fireproof silicone consisting of 50 parts by weight of the silicone compound of the above chemical formula 1, 20 parts by weight of quartz, and 30 parts by weight of pure silicon dioxide was applied to a thickness of 0.5 to 3 mm. 2 A coating of a predetermined thickness was applied to the copper busbar conductor portion, excluding both ends, having a predetermined cross-sectional area selected from the range of cross-sectional areas in the range of 0.18 mm and 0.18 mm. A 0.18 mm thick glass fiber tape (product name: AGT6WO) manufactured by SWECO was wound twice around the above-mentioned fire-resistant silicone-coated busbar to manufacture the fire-resistant silicone-coated busbar of Example 1.

[0113] A 0.18 mm thick mica tape (product name: SA765) manufactured by SWECO was wound twice around the fire-resistant silicone coated bus bar to produce a fire-resistant silicone coated bus bar of Example 2.

[0114] The length of the busbar conductor and the exposed length of both ends were the same as in Examples 1 and 2, and a glass fiber tape of AGT6WO was wound around the center of the busbar conductor to produce the busbar of Comparative Example 1. The coating thickness of the wound glass fiber tape was approximately the same as that of Example 1.

[0115] For the busbar of Comparative Example 2, the SA765 mica tape was wound once around the center of the busbar conductor, and then the glass fiber tape of Comparative Example 1 was wound once on top of that. The length of the busbar conductor and the exposed length of both ends were the same as in Examples 1 and 2 and Comparative Example 1.

[0116] In order to test the insulation characteristics (insulation maintenance performance) in the event of a fire, the covering parts (coating part, tape winding part) of the busbars of Example 1 to Comparative Example 2 were wound with copper wire with the same number of turns, and one end of the copper wire at the outermost part of the covering part was connected to the negative terminal of a withstand voltage tester, and one end of the busbar conductor part was connected to the positive terminal of the withstand voltage tester. With a voltage of 1000V applied to the busbars by the withstand voltage tester, the entire surface of the busbars was uniformly heated with a large torch with a flame temperature of 1100 to 1150°C.

[0117] Under the above voltage and heating temperature conditions, the insulation failure time until the insulation state is broken down, i.e., a short circuit occurs, was measured, and the measurement results are shown in Table 1 below.

[0118] [Table 1]

[0119] As shown in Table 1 above, the cap-integrated busbar having the fire-resistant silicone coating and protective layer according to the present invention had the longest insulation failure time, and showed a large difference in insulation failure time compared to Comparative Example 1 and Comparative Example 2.

[0120] Therefore, it is clear that the insulating properties of the fire-resistant busbar of the present invention having the above-mentioned fire-resistant silicone coating and protective layer are very excellent. In particular, Example 2, which used mica tape as the protective layer, had better insulating performance than the example in which glass fiber tape was used as the protective layer.

[0121] (Experimental Example 2) The weight ratio of the silicone compound of the above Chemical Formula 1 and the weight ratio of the metal oxide were varied to prepare fireproof silicones having the compositions shown in Table 2 below.

[0122] The fireproof silicone of Examples 1-1 to 1-5 was coated to a predetermined thickness on a copper busbar conductor under the same conditions as in Experimental Example 1, and a glass fiber tape of AGT6WO was wound around it. After that, a copper wire was wound around the busbar coating layer under the same conditions as in Experimental Example 1, and the busbar was connected to a voltage resistance tester.

[0123] In addition, with a voltage applied, the test piece 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.

[0124] [Table 2]

[0125] In the above Examples 1 to 5, the weight ratio of the silicone compound to the metal oxide was 1:1, 1:0.5, 1:1.5, 1:0.4, and 1:1.6.

[0126] All the examples have a much longer insulation fail time than the comparative examples 1 and 2. However, in the case of examples 1-4, in which the weight ratio is less than 0.5, the insulation fail time was somewhat shorter, which is believed to be due to the fact that the metal oxide was insufficient, resulting in a somewhat insufficient generation of a ceramic structure having a high density crystal structure at high temperatures.

[0127] In the case of Example 1-5 in which the weight ratio was 1.6, the insulation failure time was sufficiently long, but the metal oxide was excessive, reducing the flexibility of the fire-resistant silicone at room temperature, making it difficult to conform to and cover the bus bar conductor.

[0128] The present invention has been described in detail above with reference to the drawings and embodiments, etc. However, the configurations described in the drawings or embodiments, etc. in this specification are merely one embodiment of the present invention and do not represent all of the technical ideas of the present invention, and therefore there may be various equivalents and modifications that can replace them at the time of filing this application. [Explanation of symbols]

[0129] 100, 100', 100'': Fireproof busbar P: Central covering part C: Cap 110: Busbar conductor section 111: Both ends 120: Fire-resistant silicone coating 121: Cap section 122: Body covering part 123: Connection site 130: Protective layer 131, 131': cap protection layer 132: Body protection layer B: Fastening member S: Space for accommodating fastening components 200: Battery module 210, 220: Terminal section 300: Flame prevention bulkhead 310: Busbar installation through hole 320: Busbar installation groove 400: Pack housing 1000: Battery pack

Claims

1. A bus bar conductor portion; a fire-resistant silicone covering body including a cap portion covering both end portions of the bus bar conductor portion and a body covering portion covering a body of the bus bar conductor portion between the both end portions and integrally connected to the cap portion, the fire-resistant silicone covering body being ceramicized at high temperature to support the bus bar conductor portion; and a protective layer covering the fire-resistant silicone covering.

2. 2. The cap-integrated fire-resistant busbar according to claim 1, wherein the fire-resistant silicone coating is ceramified at a temperature of 500 to 1700°C.

3. The fire-resistant silicone coating is made into a ceramic by sintering a silicone resin containing a silicone compound represented by the following chemical formula 1 and a metal oxide containing silicon oxide: [0010] 2. The cap-integrated fireproof busbar according to claim 1, wherein in the chemical formula 1, m and n are each an integer of 10 to 30.

4. The cap-integrated fireproof busbar according to claim 3, wherein the silicone resin and the metal oxide are contained in a weight ratio of 1:0.5 to 1.

5.

5. 4. The fire-resistant busbar integral with a cap according to claim 3, wherein the metal oxide containing silicon oxide includes one or more of pure silicon dioxide, silica, quartz, silica stone, tridymite and keatite.

6. The fire-resistant busbar with integrated cap according to claim 1 , wherein the protective layer is a glass fiber layer or a mica layer.

7. The cap-integrated fireproof busbar according to claim 1 , wherein a space for accommodating a fastening member is formed in the cap portion.

8. The cap-integrated fire-resistant busbar according to claim 1 , wherein the protective layer is provided on an inner circumferential surface of the cap portion.

9. 2. The cap-integrated fire-resistant busbar according to claim 1, wherein the protective layer is not provided on a side surface of the fire-resistant silicone coating at a portion connecting the cap portion and the body covering portion, and the protective layer is provided only on an upper surface of the connecting portion.

10. 2. The cap-integrated fire-resistant busbar according to claim 1, wherein the busbar conductor portion is covered with the fire-resistant silicone covering by insert injection molding in which fire-resistant silicone is injected into a mold having the busbar conductor portion inserted therein.

11. 2. The cap-integrated fireproof busbar according to claim 1, wherein the cap-integrated fireproof busbar is a high-voltage busbar that electrically connects high-voltage terminal portions of a plurality of battery modules.

12. A plurality of battery modules; a fire prevention partition installed between the battery modules; The cap-integrated fireproof busbar according to any one of claims 1 to 11, which electrically connects the battery modules; A battery pack including the battery module and a pack housing that houses a flame-prevention partition.

13. The fire prevention partition has a bus bar installation through hole or a bus bar installation groove, The cap-integrated fireproof busbar is seated in the busbar installation through-hole or the busbar installation groove, both ends of the bus bar conductor portion of the cap-integrated bus bar are electrically connected to terminal portions of the battery modules located on both sides of the flame prevention partition wall, The battery pack according to claim 12 , wherein the cap portion of the cap-integrated bus bar covers a joint portion between the both ends and the terminal portion.

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