Fire-resistant cable and battery pack including same

Abstract

The present invention provides a fire-resistant cable including a cable core wire, a fire-resistant silicone coating layer that covers the cable core wire except for both ends and that is ceramicized at high temperature to support the cable core wire, and a metal case that houses the cable core wire and the fire-resistant silicone coating layer and has openings on both sides through which both ends of the cable core wire are led out. The present invention also provides a battery pack including the fire-resistant cable.

Description

[Technical field]

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

[0002] More specifically, the present invention relates to a fire-resistant cable and a battery pack that are provided with a fire-resistant silicone coating layer that is ceramicized at high temperatures and a metal case that encases the coating layer, and that can maintain their insulating and airtight properties even at high temperatures that could cause a fire inside the battery pack.

[0003] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0137521 dated October 24, 2022, and all contents disclosed in the documents of that 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] In order to electrically connect the battery modules, bus bars, cables, etc. are used. The cables are used to electrically connect terminal units of adjacent battery modules, to electrically connect a BMS unit and a battery module or a BMS unit and each battery cell provided in a battery module, or to connect a battery module to an external electric device.

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

[0007] As shown in the figure, the conventional cable 1 is composed of a cable core 10 and a coating layer 20 that encases the core. The core is a typical copper wire. The coating layer is made of a plastic resin such as polyethylene (PE) or polyvinyl chloride (PVC).

[0008] When the battery modules are electrically connected within a battery pack using the above-mentioned conventional cables, for example, no problems arise in the operation of the battery pack at normal temperatures where the battery pack operates normally.

[0009] However, when a fire occurs inside a battery pack, the temperature of the flame is so high (500°C to 800°C, or even higher than 800°C, and in severe cases, higher than 1000°C), that the plastic resin coating layer melts completely, exposing the cable core to the outside. When this happens, the exposed cable core comes into electrical contact with 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] To prevent thermal propagation, it may be possible to consider a cable using a mica sheet, glass fiber, or heat-resistant silicone (rubber) as the covering layer.

[0011] However, in the above-mentioned intense heat generation conditions, the above-mentioned materials cannot sufficiently prevent heat diffusion. For example, a normal heat-resistant silicone sheet can only withstand a heat temperature of 125°C to 300°C, and cannot effectively deal with the ignition condition inside the battery pack. In addition, the mica sheet and the glass fiber covering layer do 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 cable core from the surroundings even at high temperatures when a flame breaks out inside the battery pack.

[0014] Meanwhile, for example, when a cable connects battery modules, the cable may be supported by or pass through a structure (e.g., a bulkhead) of the battery pack, in which case the covering layer of the cable may be damaged by a sharp edge of the bulkhead, resulting in impaired insulation of the core wire and impaired airtightness.

[0015] Alternatively, the cable may have to be bent excessively due to the electrical connection path, but in the case of a thick cable used in a large-capacity battery, it is difficult to bend the cable as desired, which may result in poor assembly within the battery pack.

[0016] 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 insulating properties by providing fire resistance at high temperatures. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] Japanese Patent Registration No. 5312710 Summary of the Invention [Problem to be solved by the invention]

[0018] The present invention provides a fire-resistant cable that can maintain thermal insulation and electrical insulation for as long as possible even in the event of a fire inside a battery pack.

[0019] The present invention also provides a battery pack including the above fire-resistant cable. [Means for solving the problem]

[0020] The fire-resistant cable of the present invention for solving the above-mentioned problems includes a cable core wire, a fire-resistant silicone coating layer that covers a portion of the cable core wire except for both ends and that is ceramicized at a high temperature to support the cable core wire, and a metal case that houses the cable core wire and the fire-resistant silicone coating layer and has openings on both sides through which both ends of the cable core wire are led out to the outside.

[0021] The fire-resistant silicone can be ceramified at temperatures between 500°C and 1700°C.

[0022] The fire-resistant silicone can be made into a ceramic by sintering a silicone resin containing a silicone compound represented by the formula (1) and a metal oxide containing silicon oxide.

[0023] [ka]

[0024] In [Chemical formula 1], m and n are each an integer of 10 to 30.

[0025] The silicone resin and the metal oxide may be contained in a weight ratio of 1:0.5 to 1.5.

[0026] The silicon oxide-containing metal oxide may include one or more of pure silicon dioxide, silica, quartz, silica stone, tridymite, and keatite.

[0027] The metal case includes an upper case and a lower case, and the upper and lower cases can be joined together by a hook connection.

[0028] At least one of the inner and outer surfaces of the metal case may be anodized.

[0029] The metal case includes one of aluminum, steel, and stainless steel.

[0030] The cable core wire has a bent portion, The metal case may have a bent portion corresponding to the shape of the bent portion.

[0031] The fire-resistant cable may be a high-voltage cable that electrically connects high-voltage terminal portions of a plurality of battery modules.

[0032] A battery pack according to another aspect of the present invention may include a plurality of battery modules, fireproof partitions installed between the battery modules, the fireproof cable described above that electrically connects the battery modules, and a pack housing that accommodates the battery modules and the fireproof partitions.

[0033] The fireproof partition has a cable installation through hole or a cable installation groove, and the metal case of the fireproof cable is seated in the cable installation through hole or the cable installation groove, and both ends of the cable core wire led out from the opening of the metal case can be electrically connected to terminal portions of the battery modules located on both sides of the fireproof partition.

[0034] The metal case of the fire-resistant cable may be formed to correspond to the shape of the cable installation through hole or cable installation groove. Effect of the Invention

[0035] The fire-resistant cable of the present invention has a fire-resistant silicone coating layer that is ceramicized and supports the cable core wire instead of a coating layer that will not burn in the event of a flame occurring inside the pack, so that it can maintain its insulating and airtight properties even at high temperatures.

[0036] The fire-resistant cable of the present invention also includes a metal case encasing the fire-resistant silicone coating layer. The metal case maintains the shape of the cable core and encases the fire-resistant silicone to prevent the fire-resistant silicone from being directly exposed to flames, thereby preventing deformation of the fire-resistant silicone and further enhancing the insulation and airtight properties.

[0037] In addition, the metal case can protect the fireproof silicone and the core wire, prevent insulation damage caused by sharp edges, and improve airtightness with the partition wall of the battery pack.

[0038] Furthermore, according to the present invention, the core wire is first formed and placed in the battery pack, and then the core wire is joined to the metal case having the fire-resistant coating layer. Therefore, even a thick core wire can be formed with a small radius of curvature (R value), which is suitable for a large-capacity battery. [Brief description of the drawings]

[0039] [Figure 1] FIG. 1 is a schematic diagram showing a conventional cable structure. [Diagram 2] 1 is a perspective view of a fire-resistant cable according to an embodiment of the present invention; [Diagram 3] FIG. 3 is a perspective view showing a state before assembly of a metal case of the fire-resistant cable of FIG. 2. [Figure 4] 3A and 3B are side and plan views of the fire resistant cable of the embodiment of FIG. 2. [Diagram 5] FIG. 3 is a cross-sectional view of the fire-resistant cable of the embodiment of FIG. 2. [Figure 6] FIG. 4 is a cross-sectional view of a fire-resistant cable according to another embodiment of the present invention. [Figure 7] FIG. 2 is a plan view of a fire resistant cable 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 fire-resistant cable 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 fire-resistant cable of the present invention is installed. [Figure 10] FIG. 2 is a side cross-sectional view showing a state in which the fire-resistant cable of the present invention is installed in a battery pack. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] 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.

[0041] 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.

[0042] [Fireproof cable] The fire-resistant cable of the present invention includes a cable core wire, a fire-resistant silicone coating layer that covers the cable core wire except for both ends and that is ceramicized at high temperature to support the cable core wire, and a metal case that houses the cable core wire and the fire-resistant silicone coating layer and has openings on both sides through which both ends of the cable core wire are led out to the outside.

[0043] The cable core may be a common copper core, and the core may be a wire core formed by twisting a plurality of copper wires, and both ends of the core are electrically connected to corresponding coupling parts.

[0044] The fire-resistant silicone coating layer is a layer that coats the cable core wire while wrapping the cable core wire except for both ends. That is, as shown in FIG. 2 to FIG. 5, the fire-resistant silicone coating layer coats the central portion of the core wire except for both ends. The fire-resistant silicone coating layer is ceramicized at high temperature to support the cable core wire. The fire-resistant silicone can be ceramicized at a temperature of 500°C to 1700°C. The fire-resistant silicone of the present invention is distinguished from heat-resistant silicone having a heat-resistant temperature of less than 300°C in that the fire-resistant temperature is 500°C or higher. Heat-resistant silicone is a silicone resin or rubber composition having flexibility and pliability due to the characteristics of silicone, but is a material that does not become ceramicized at a high temperature of 500°C or higher and does not burn or turns to ash. Therefore, there is a limit to its application to preventing short circuits or heat propagation of battery packs in a heat propagation situation.

[0045] The fire-resistant silicone coating layer 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 cable according to the present invention can realize high fire resistance by providing fire-resistant silicone inside the cable as well as improving the cable structure.

[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. This ceramic body prevents short circuits or disconnections between conductors due to damage to the fireproof silicone coating layer even when an external mechanical impact is applied during a fire or moisture penetrates, and the cable 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 [Chemical formula 2] (hereinafter referred to as "silicone compound of [Chemical formula 2]"):

[0051] [ka]

[0052] In [Chemical formula 2], m and n are each an integer of 10 to 30.

[0053] The silicone compound of [Chemical formula 2] 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 [Chemical formula 2] 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 enabling the silicone compound to realize better fire resistance than a silicone compound that does not contain a vinyl group.

[0054] In addition, the weight-average molecular weight of the silicone compound of [Chemical formula 2] can be adjusted to a specific range. The silicone compound of [Chemical formula 2] is a compound that forms the base of the silicone resin, and can affect the physical properties of the fire-resistant silicone at room temperature and high temperature depending on the weight-average molecular weight of the silicone compound of [Chemical formula 2]. For example, if the weight-average molecular weight of the silicone compound of [Chemical formula 2] is excessively high, the viscosity of the silicone resin increases and the reactivity during high-temperature sintering may decrease, and if the weight-average molecular weight is significantly low, the room-temperature elasticity and flexibility of the silicone resin are reduced, and the manufacturing processability of the fire-resistant cable decreases, while there is a limit to the decrease in impact resistance, etc. Therefore, the silicone compound of [Chemical formula 2] according to the present invention can have a weight-average molecular weight adjusted to 1,000 g / mol to 9,000 g / mol, specifically 3,000 g / mol to 8,000 g / mol, or 5,000 g / mol 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 contain a silicone compound represented by [Chemical formula 3] (hereinafter referred to as "the silicone compound of [Chemical formula 3]"). The silicone compound of [Chemical formula 3], together with the silicone compound of [Chemical formula 2], participates in the sintering of the metal oxide at high temperatures to form a silicone sintered body:

[0059] [ka]

[0060] In [Chemical formula 3], p is an integer of 10 to 30.

[0061] The silicone compound of [Chemical formula 3] increases the flexibility of the fire-resistant silicone at room temperature, while at the same time inducing the completion of sintering of the silicone resin by dehydration condensation with the silicone compound of [Chemical formula 2] during sintering, thereby completing the reaction of forming a ceramic body.

[0062] For this reason, the silicone compound of [Chemical Formula 3] may be used in an amount of less than 10 parts by weight per 100 parts by weight of the fire-resistant silicone, specifically, 0.5 to 9 parts by weight, 1 to 6 parts by weight, or 2 to 5 parts by weight.

[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% by weight to 50% by weight of a silicone compound of [Chemical formula 2], 16% by weight to 32% by weight of quartz, 10% by weight to 27% by weight of silicon dioxide, and 1% by weight to 6% by weight of a second silicone compound of [Chemical formula 3], 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 fire-resistant silicone has rubber-like properties, including flexibility, softness, and elasticity, before being ceramized. Therefore, the fire-resistant silicone coating layer can be easily injected into a metal case, which will be described later, for injection molding, or can be easily applied to the inside of the metal case. In addition, when the cable core is sandwiched between the fire-resistant silicone coating layer provided in the metal case, the flexible fire-resistant silicone pressurizes the cable core and envelops the core. As a result, the flexible fire-resistant silicone can cover the core without gaps while conforming to the shape of the cable core.

[0068] The fire-resistant silicone coating layer has flexibility before being ceramicized, and can flexibly follow deformation of the cable core. Therefore, when the fire-resistant cable of the present invention is installed in a battery pack, even if there is a slight assembly tolerance, it can flexibly accommodate it. For example, when a battery module is fastened to a battery pack by bolting, if the cable core connected to the battery module moves or twists slightly, the fire-resistant silicone coating layer can absorb such movement or twisting. In addition, even if the battery pack vibrates due to vibration of the electric vehicle, the fire-resistant silicone coating layer can naturally absorb the vibration.

[0069] On the other hand, the ceramicized fire-resistant silicone directly wraps and supports the core wire, allowing the core wire to continue to maintain its shape.

[0070] The fire-resistant cable of the present invention also includes a metal case in which the above-mentioned cable core and the fire-resistant silicone coating layer are housed.

[0071] The metal case may include openings at both sides through which both ends of the cable core wire are led out, and both ends of the cable core wire may be exposed to the outside through the openings at both sides, and both ends of the core wire may be coupled to corresponding electrical connecting portions.

[0072] The metal case maintains the shape of the molded cable core wire. In addition, the fire-resistant silicone coating layer is wrapped to prevent the fire-resistant silicone coating layer from being directly exposed to flames when the battery pack is ignited. This prevents the fire-resistant silicone coating layer from being deformed, and enhances insulation and airtightness. The metal case also firmly supports the outer shape of the fire-resistant silicone to prevent it from collapsing when the battery pack is ignited, allowing insulation and airtightness to be maintained for a long time.

[0073] In addition, when the metal case is installed in a battery pack, for example, it can be surface-attached to the assembly space in the battery pack to maintain airtightness. Since the metal case has a hard surface, even if there are sharp edges in the assembly space in the battery pack, the insulation and the cable core wire in the fireproof cable can be prevented from being damaged.

[0074] The metal case may be made of one of aluminum, steel, and stainless steel, but is not limited thereto, and may be made of other metals as long as they are strong enough to protect the cable core and the fire-resistant silicone coating layer and are easy to mold and process.

[0075] In order to reinforce the insulating property, the surface of the metal case may be subjected to a surface treatment, for example, anodizing may be performed on the inner surface, the outer surface, or both the inner and outer surfaces of the metal case.

[0076] Anodizing is one of the metal surface treatment techniques belonging to chemical coating treatments along with phosphate coating and chromate, and is applied to improve the corrosion resistance and wear resistance of non-ferrous metal products such as aluminum, titanium, copper, and magnesium. When the target metal is electrolyzed with a diluted acid solution over an anode, an oxide film is formed by oxygen generated at the anode. In the case of aluminum, alumina (Al2O3) is formed as the oxide film. Since such an oxide film is an insulator, a metal case made of a metal (e.g., aluminum) that has been anodized becomes a surface insulator. Therefore, the fire-resistant cable of the present invention that has an anodized metal case has two electrical insulators. That is, it has a fire-resistant silicone coating layer as the first insulator and an oxide film on the surface of the metal case as the second insulator. Therefore, the insulation of the fire-resistant cable is further improved by anodizing.

[0077] The metal case may be an integrally formed case or a case in which separate case parts are joined together to form a single case, as long as it is capable of housing the cable core and the fire-resistant silicone coating layer surrounding the core. However, in any case, it is necessary that the metal case has openings on both sides through which both ends of the cable core can be led out to the outside.

[0078] Specific configurations of the fire-resistant cable and the metal case will be described in detail in the following embodiments.

[0079] (First embodiment) FIG. 2 is an oblique view of a fire-resistant cable according to one embodiment of the present invention, FIG. 3 is an oblique view showing the state of the fire-resistant cable of FIG. 2 before assembly of a metal case, FIG. 4 is a side view and a plan view of the fire-resistant cable of the embodiment of FIG. 2, and FIG. 5 is a cross-sectional view of the fire-resistant cable of the embodiment of FIG. 2.

[0080] Referring to the drawings, the metal case 130 of the fire-resistant cable 100 of the present embodiment includes an upper case 130A and a lower case 130B. That is, in the present embodiment, the metal case 130 is not integrally formed but is composed of two parts. The upper case 130A and the lower case 130B can be easily coupled to each other by the hook coupling part 132. That is, the lower case 130B includes a protrusion 132B on the upper front side, and the upper case 130A includes a hook part 132A on the lower front side to which the protrusion is fitted. The hook part 132A and the protrusion 132B constitute the hook coupling part 132. As shown in FIG. 3, the side surfaces of the upper case 130A and the lower case 130B on the side where the hook coupling part 132 is not formed are connected to each other by a hinge coupling. Therefore, one of the upper and lower cases can be hinged and moved (rotated) relative to the other. In the state shown in FIG. 3, one of the upper and lower cases is rotated relative to the other to bring them closer together, and the hook portion 132A is engaged with the protrusion portion 132B to join the upper and lower cases, thereby forming the metal case 130 of the present invention.

[0081] As shown in Fig. 3, the upper case 130A and the lower case 130B are provided with open grooves 131A and 131B on both sides thereof. Therefore, when the upper and lower cases are joined, the open groove 131A of the upper case and the open groove 131B of the lower case are engaged with each other to form an opening 131. Both ends of the cable core wire 110 can be led out through the opening 131. The size and shape of the open grooves 131A and 131B provided in the upper and lower cases do not necessarily have to be the same. For example, one of the two open grooves may be smaller in size than the other as long as the two open grooves 131A and 131B are engaged with each other to form an opening that matches the shape of the core wire.

[0082] In this embodiment, the two open grooves 131A and 131B are engaged to form the opening 131, but the present invention is not limited to this. For example, openings may be formed on both sides of one of the upper case 130A or the lower case 130B, and the other case may not have an opening and be closed. However, when the two cases each have an open groove and the two open grooves are joined to form an opening as in this embodiment, it is convenient to position the cable core 110 between the upper and lower cases and combine the upper and lower cases to assemble a fire-resistant cable.

[0083] Furthermore, the cable core wire 110 can be fixedly coupled to the metal case 130 more easily by using the hook coupling.

[0084] Referring to FIG. 3, the upper fireproof silicone coating layer 120A is filled inside the upper case 130A, and the lower fireproof silicone coating layer 120B is filled inside the lower case 130B. The assembly process of the cable core 110 and the metal case 130 will be described with reference to FIG. 2 and FIG. 3. The cable core 110 is placed on one of the upper fireproof silicone coating layer 120A and the lower fireproof silicone coating layer 120B, for example, on the lower fireproof silicone coating layer 120B. At this time, the lower ends of both ends of the cable core 110 are placed on the open grooves 131B provided on both sides of the lower case 130B, and both ends are led out of the open grooves 131B by a certain length. Next, the upper case 130A is hook-coupled to the lower case 130B so that the open grooves 131A of the upper case 130A cover the upper ends of both ends of the cable core 110. As shown in Figs. 2 and 5, when the upper and lower cases are hook-coupled, the cable core wire 110 is pressed by the upper fireproof silicone coating layer 120A and the lower fireproof silicone coating layer 120B due to the hook coupling force, and is fixed in the metal case 130. Since the fireproof silicone coating layer 120 has elasticity and flexibility, the cable core wire 110 is pressed and embedded in the upper and lower fireproof silicone due to the hook coupling force. As a result, the cable core wire 110 is covered by the fireproof silicone coating layer 120 in the form shown in Fig. 5 and is fixed in the metal case 130. At this time, both ends of the cable core wire 110 are led out to the outside by a certain length. The outer circumference of the cable core wire 110 is restricted by the inner circumferential surface of the open groove 131A of the upper case 130A and the inner circumferential surface of the open groove 131B of the lower case, and the cable core wire 110 can be stably maintained in the metal case 130.

[0085] In this way, by constructing metal case 130 with upper and lower cases and connecting the upper and lower cases with a hook connection, it is possible to simultaneously fix (cover) cable core wire 110 to fire-resistant silicone covering layer 120 and assemble metal case 130.

[0086] If necessary, the upper and lower fireproof silicone coating layers 120A and 120B shown in FIG. 3 may be formed with a shape (not shown) corresponding to the outer circumferential shape of the cable core 110. For example, if the elasticity and flexibility of the fireproof silicone coating layer 120 is insufficient, the cable core may not be completely wrapped by the fireproof silicone coating layer 120 despite the hook bonding force of the upper and lower cases. In this case, a space may be partially formed between the cable core 110 and the fireproof silicone coating layer 120. In order to prevent the space from being formed, the upper and lower fireproof silicone coating layers may be formed with a shape corresponding to the outer circumferential shape of the upper half and the lower half of the cable core 110 on the upper and lower fireproof silicone coating layers 120A and 120B. However, the fireproof silicone having the composition of the above-mentioned embodiment has sufficient elasticity and flexibility, and in principle, even if the cable core shape is not formed as shown in FIG. 3, it can be flexibly deformed by the hook bonding force to wrap the cable core without any gaps.

[0087] The cable core wire 110 and the metal case 130 may be assembled in advance as shown in Fig. 3. Alternatively, the fire-resistant silicone coating layer 120 may be filled or applied in advance inside the metal case 130, and then the cable core wire 110 may be coupled into the metal case 130 only at the site where the battery pack is to be installed.

[0088] Furthermore, when the fire-resistant silicone coating layer 120 is formed inside the metal case 130, it is also possible to apply a flexible fire-resistant silicone to the metal case 130, or to form an opening in a part of the metal case 130 and fill the fire-resistant silicone from the outside through the opening. In the latter case, for example, it is also possible to position the cable core wire 110 in the metal case 130 in advance, and inject (injection mold) the fire-resistant silicone into the metal case 130 through the opening, so that the fire-resistant silicone naturally wraps around and coats the cable core wire 110.

[0089] The advantages of field bonding of the cable core 110 to the metal case 130 having the fire-resistant silicone coating layer 120 will be described in detail in connection with other embodiments described below.

[0090] Second embodiment FIG. 6 is a cross-sectional view of a fire-resistant cable according to another embodiment of the present invention.

[0091] In the fire-resistant cable 100' of this embodiment, in order to reinforce insulation, anodizing is performed on the inner and outer surfaces of the metal case 130. Other than the anodizing, the fire-resistant cable 100' of this embodiment is the same as that of the first embodiment in that it includes a cable core wire 110, a fire-resistant silicone coating layer 120 that encases the cable core wire 110, and a metal case 130 that houses the cable core wire 110 and the fire-resistant silicone coating layer 120 and has openings on both sides through which both ends of the cable core wire are led out.

[0092] As described above, anodizing improves the corrosion resistance and wear resistance of non-ferrous metal products. For example, if the metal case is made of aluminum, the aluminum is placed as an anode and electrolyzed in a diluted acid solution. Oxide film 133, which is an insulator, i.e., metal oxide (alumina (Al2O3)) is formed on the aluminum surface by oxygen generated at the anode. Therefore, the insulation of the fire-resistant cable 100' of this embodiment is further improved.

[0093] The anodizing treatment may be performed on the inner surface or the outer surface of the metal case 130, or on both the inner surface and the outer surface as in the example of FIG. 6. When the inner surface of the metal case 130 is anodized, the cable core wire 110 can be doubly insulated together with the fire-resistant silicone coating layer 120 inside the metal case. When the outer surface of the metal case is anodized, the electrical insulation performance against external metal parts can be improved. When both the inner surface and the outer surface of the metal case are anodized, all of the above effects can be achieved.

[0094] Third embodiment FIG. 7 is a plan view of a fire resistant cable according to another embodiment of the present invention.

[0095] In this embodiment, a fire-resistant cable 100'' is shown in which the cable core wire 110 has a bent portion, and the metal case 130' also has a bent portion having a shape corresponding to the shape of the bent portion.

[0096] In addition to the shape of the fire-resistant cable, the third embodiment is the same as the other embodiments in that it comprises a cable core wire and a fire-resistant silicone coating layer that encases the cable core wire, and that it comprises a metal case that houses the cable core wire and the fire-resistant silicone coating layer and has openings on both sides through which both ends of the cable core wire are led out.

[0097] For example, cables may need to be bent many times due to the layout of components inside a battery pack. However, in the case of large-capacity battery packs, conventional thick cables have a small radius of curvature (R value), meaning that it is difficult to bend them beyond a certain limit. This increases the volume that the cables occupy inside the battery pack, which reduces the area occupied by other components such as battery cells, resulting in a problem of reduced energy density.

[0098] However, in the case of a large-capacity battery pack, the fire-resistant cable 100'' of the present embodiment may be bent by bending only the cable core 110 without the covering layer and then coupled to the corresponding electrical coupling part. Since only the core without the covering layer is bent, the radius of curvature, i.e., the R value, can be reduced. Then, a metal case 130' having a shape corresponding to the bent cable core and a fire-resistant silicone covering layer therein may be coupled to the core. In this case, the hook coupling part 132' provided on the metal case 130' may also be formed into a bent shape as necessary.

[0099] As described above, the fire-resistant cable 100'' of this embodiment has an advantage that the fire-resistant cable can be easily installed even when the core wire is relatively thick, and the assembling efficiency is further improved.

[0100] In this embodiment, the cable core 110 can be installed at the site first due to the fire-resistant cable structure unique to the present invention. Therefore, since only the core can be formed into a desired shape without a coating layer, even a relatively thick core can be easily formed. Then, a metal case 130' is manufactured to correspond to the shape of the core, a fire-resistant silicone coating layer is applied or filled inside the metal case 130', and the core is assembled to the metal case at the site, whereby the fire-resistant cable of the present invention can be easily installed.

[0101] The shape of the bent portion shown in Figure 7 is one example, and as long as the manufacturing conditions of the metal case permit, the fire-resistant cable of this embodiment can also be applied to other shapes, such as when the bent portions are continuous or when the cable has both bent portions and straight portions.

[0102] [Battery pack] FIG. 8 is a schematic diagram showing an example of a battery pack structure in which the fire-resistant cable of the present invention is installed, FIG. 9 is a schematic diagram showing another example of a battery pack structure in which the fire-resistant cable of the present invention is installed, and FIG. 10 is a side cross-sectional view showing the fire-resistant cable of the present invention installed in a battery pack.

[0103] The fire-resistant cables 100, 100', 100'' of the present invention described above include a fire-resistant silicone coating layer 120 that is ceramicized at high temperatures, and a metal case 130 that encases the fire-resistant silicone coating layer 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.

[0104] The fire-resistant cable 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 fire-resistant cable may electrically connect terminal portions of adjacent battery modules. Alternatively, the fire-resistant cable may be used to electrically connect a BMS portion and a battery module. Alternatively, the fire-resistant cable may be used to connect a battery module to an external electrical device.

[0105] 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 fire-resistant cable of the present invention is suitable for use as a high voltage cable that electrically connects the high voltage terminals of a plurality of battery modules.

[0106] 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 fire-resistant cables 100, 100', 100'' that electrically connect the battery modules, and a pack housing 400 that houses the battery modules and the fire prevention partitions.

[0107] 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 bus bars, such as terminal bus bars or inter bus bars, or cables. A fire-resistant cable according to the present invention may be applied to electrically connect the plurality of battery modules.

[0108] 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 fire-resistant cable 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 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 fire-resistant cable 100, 100', 100'' of the present invention may be used for electrically connecting the cell block or the module-less battery module installed in such a cell-to-pack battery pack.

[0109] 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 cable installation through hole 310 or a cable installation groove 320. FIG. 8 shows that the fire prevention partition 300 is provided with a cable installation through hole 310, and FIG. 9 shows that the fire prevention partition 300 is provided with a cable installation groove 320. In terms of fire prevention and airtightness, a partition provided with the cable installation through hole 310 as shown in FIG. 8 is advantageous. The cable installation groove 320 in FIG. 9 has an open upper portion, which is advantageous for cable installation and cable electrical connection work.

[0110] The fire-resistant cables 100, 100′, 100″ may be seated in the cable installation through-hole 310 or the cable installation groove 320. At this time, both ends of the cable core wire 110 led out from the opening of the metal case 130 may be electrically coupled to terminal parts 210, 220 of the battery modules 200 located on both sides of the fire prevention partition 300.

[0111] FIG. 10 shows how the fire-resistant cable 100 electrically connects the battery modules 200 in the battery pack 1000. A fire-resistant partition 300 is located between adjacent battery modules 200, and the fire-resistant partition has a cable installation through hole 310. The metal case 130 of the fire-resistant cable 100 of the present invention is inserted into the through hole. In this case, the shape of the metal case 130 of the fire-resistant cable is formed corresponding to the shape of the cable installation through hole (or cable installation groove). Therefore, the fire-resistant cable 100 of the present invention can be airtightly attached to the fire-resistant partition 300. This can further improve the airtightness of the battery pack. In addition, even if the cable installation through hole or the cable installation groove has a sharp edge due to processing, the metal case 130 covers and protects the fire-resistant silicone coating layer 120 and the cable core wire 110. That is, the insulating strength and airtightness of the fire-resistant cable are further improved by the metal case.

[0112] In this case, if at least one side of the metal case is anodized as in the second embodiment, the insulation of the fire-resistant cable 100' can be further improved. In addition, although the fire-resistant cable 100 has a straight shape in FIG. 10, the battery module can be connected by making the cable core wire and the metal case have a bent portion as in the third embodiment. In this case, the curvature radius of the fire-resistant cable can be reduced, and the energy density of the battery pack can be increased.

[0113] Meanwhile, in the case where a fire occurs in the battery pack 1000, the fire-resistant cable of the present invention forms a dense sintered body by ceramicizing the fire-resistant silicone coating layer surrounding the cable core. That is, unlike conventional heat-resistant silicone, which does not burn or turn to ash at high temperatures of 500°C or more, it ceramicizes and maintains its shape. As a result, the fire-resistant silicone coating layer stably supports the cable core even when a flame occurs. The metal case not only maintains the shape of the fire-resistant silicone coating layer, but also prevents the flame from coming into contact with the fire-resistant silicone coating layer, preventing deformation of the fire-resistant silicone, and further strengthens the insulating properties and airtight properties.

[0114] [Experimental Example]

[0115] (Experimental Example 1) A fireproof silicone consisting of 50 parts by weight of the silicone compound of [Chemical formula 2], 20 parts by weight of quartz, and 30 parts by weight of pure silicon dioxide was applied to a 0.5 mm 2 ~3mm 2 A copper cable core having a predetermined cross-sectional area selected from the range of cross-sectional areas was coated with a predetermined thickness. The fire-resistant silicone-coated cable of Example 1 was manufactured by exposing both ends of the cable core except for the coated portion.

[0116] The length of the cable core and the exposed length of both ends were the same as in Example 1, and a glass fiber tape (3M 361) was wrapped around the center of the cable core a total of two times. The coating thickness of the wrapped glass fiber tape was approximately the same as the coating thickness of the fire-resistant silicone to produce the cable of Comparative Example 1.

[0117] For the cable of Comparative Example 2, a mica tape made of phlogopite mica, which is natural mica, was wound once around the center of the cable core wire, and then the glass fiber tape of Comparative Example 1 was wound once on top of that. The length of the cable core wire and the exposed length of both ends were the same as those of Example 1 and Comparative Example 1.

[0118] In order to test the insulation characteristics (insulation maintenance performance) in the event of a fire, the coated parts (coating part, tape winding part) of the cables of Example 1 to Comparative Example 2 were wound with copper wire with the same number of turns, one end of the outermost copper wire of the coated part was connected to the negative terminal of a voltage resistance tester, and one end of the cable core wire was connected to the positive terminal of a voltage resistance tester. With a voltage of 1000V applied to the above cables by the voltage resistance tester, the surface of the entire cable was uniformly heated with a large torch with a flame temperature of 1100°C to 1150°C.

[0119] Under the above voltage and heating temperature conditions, the insulation failure time until the insulation breaks down, i.e., a short circuit occurs, was measured, and the measurement results are shown in [Table 1].

[0120] [Table 1]

[0121] As shown in Table 1 above, the cable having the fire-resistant silicone coating layer according to the present invention had the longest insulation failure time, and showed a large difference from Comparative Example 1 and Comparative Example 2 in terms of insulation failure time.

[0122] Therefore, it can be seen that the insulation properties of the fire-resistant cable of the present invention, in which the above-mentioned fire-resistant silicone coating layer is filled in a metal case, are very excellent. In Example 1, the insulation performance was tested without a metal case, and it can be said that it is clear that when a metal case is installed outside the fire-resistant silicone coating layer, the fire-resistant silicone is not directly exposed to flames, and therefore the insulation performance against high external temperatures is further improved.

[0123] (Experimental Example 2) By varying the weight of the silicone compound of [Chemical Formula 2] and the weight ratio of the metal oxide, fireproof silicones having the compositions shown in [Table 2] were prepared.

[0124] The fireproof silicone of Examples 1 to 5 was coated to a predetermined thickness on a copper core wire under the same conditions as in Experimental Example 1, and a copper wire was wound on the cable coating layer under the same conditions as in Experimental Example 1, and connected to a voltage resistance tester.

[0125] In addition, with 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].

[0126] [Table 2]

[0127] In the above Examples 1 to 5, 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.

[0128] All the examples have a much longer insulation fail time than the comparative examples 1 and 2. However, in the case of example 4, in which the weight ratio is less than 0.5, the insulation fail time was slightly shorter at 5 minutes, which is believed to be due to an insufficient amount of metal oxide and a somewhat insufficient generation of a ceramic structure having a high density crystal structure at high temperatures.

[0129] In the case of Example 5, in which the weight ratio was 1.6, the insulation fail time was sufficiently long, but the amount of metal oxide was excessive, which in turn reduced the flexibility of the fire-resistant silicone at room temperature, making it difficult to conform to the cable core wire and cover it.

[0130] 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]

[0131] 100, 100', 100'': Fireproof cable 110: Cable core 120: Fire-resistant silicone coating layer 130: Metal case 131: Opening 132: Hook joint 133: Oxide film 200: Battery module 210, 220: Terminal section 300: Bulkhead for flame prevention 310: Cable installation through hole 320: Cable installation groove 400: Pack housing 1000: Battery pack

Claims

1. A cable core, a fire-resistant silicone coating layer that covers the cable core except for both ends, the fire-resistant silicone coating layer being ceramicized at a high temperature to support the cable core; a metal case that houses the cable core wire and the fire-resistant silicone coating layer, the metal case having openings on both sides through which both ends of the cable core wire are led out to the outside.

2. 2. The fire resistant cable according to claim 1, wherein the fire resistant silicone coating layer ceramizes at a temperature of 500°C to 1700°C.

3. The fire-resistant silicone coating layer is made into a ceramic by sintering a silicone resin containing a silicone compound represented by [Chemical Formula 1] and a metal oxide containing silicon oxide, 【Chemistry 1】 2. The fire-resistant cable according to claim 1, wherein in the formula (1), m and n are each an integer of 10 to 30.

4. The fire-resistant cable 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 cable of claim 3, wherein the metal oxide containing silicon oxide comprises one or more of pure silicon dioxide, silica, quartz, silica stone, tridymite and keatite.

6. 2. The fire resistant cable of claim 1, wherein the metal case comprises an upper case and a lower case, the upper case and the lower case being joined by a hook joint.

7. The fire-resistant cable according to claim 1 , wherein at least one of the inner and outer surfaces of the metal case is anodized.

8. 10. The fire resistant cable of claim 1, wherein the metal case comprises one of aluminum, steel, and stainless steel.

9. The cable core wire has a bent portion, The fire-resistant cable according to claim 1 , wherein the metal case has a bent shape corresponding to a shape of the bent portion.

10. The fire-resistant cable according to claim 1 , wherein the fire-resistant cable is a high-voltage cable electrically connecting high-voltage terminal portions of a plurality of battery modules.

11. A plurality of battery modules; a fire prevention partition installed between the battery modules; a fire-resistant cable according to any one of claims 1 to 10, which electrically connects the battery modules; and A battery pack including a pack housing that houses the battery module and the flame prevention partition.

12. The fireproof bulkhead has a cable installation through hole or a cable installation groove, The metal case of the fire-resistant cable is seated in the cable installation through hole or the cable installation groove, 12. The battery pack according to claim 11, wherein both ends of the cable core wire led out from the opening of the metal case are electrically coupled to terminal portions of the battery modules located on both sides of the fire prevention partition.

13. The battery pack according to claim 12 , wherein the metal case is formed corresponding to a shape of the cable installation through-hole or the cable installation groove.

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