KR20240062377A - Fireproof busbar and battery pack hanving the same - Google Patents

Abstract

The fire-resistant bus bar of the present invention includes a bus bar conductor portion; A fire-resistant silicon coating layer that surrounds the bus bar conductor portion except for both ends and is ceramicized at a high temperature to support the bus bar conductor portion; A protective layer surrounding the fireproof silicon coating layer; and an expanded silicon layer surrounding the protective layer and expanding above a predetermined temperature.
Additionally, the present invention provides a battery pack including the fire-resistant bus bar.

Description

Fireproof busbar and battery pack including the same {FIREPROOF BUSBAR AND BATTERY PACK HANVING THE SAME}

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

More specifically, it is provided with a fire-resistant silicon coating layer that becomes ceramic at high temperature, a protective layer surrounding this coating layer, and an expanded silicon layer surrounding the protective layer, so that the battery pack can maintain insulating and airtight properties even at high temperatures where ignition occurs inside the battery pack. It relates to fire-resistant bus bars and battery packs.

Battery packs applied to electric vehicles, etc. have a structure in which multiple battery modules including a plurality of secondary batteries are connected in series or parallel to obtain high output. In addition, the secondary battery is capable of repeated charging and discharging through electrochemical reactions between components, including positive and negative electrode current collectors, separators, active materials, and electrolyte solutions.

To electrically connect the battery modules, a bus bar is used. The bus bar is used to electrically connect terminal portions of adjacent battery modules or to connect battery modules to external electrical devices.

1 is a schematic diagram showing a conventional busbar structure.

As shown, the conventional bus bar 1 consists of a bus bar conductor portion 10 and a covering layer 20 surrounding the bus bar conductor portion. The busbar conductor 10 is, for example, a high-purity copper conductor such as C1100 or a metal conductor such as aluminum. The coating layer 20 is made of a material such as common silicone rubber or epoxy. The coating layer 20 covers the body portion of the bus bar conductor portion 10 except for both ends 11. At both ends 11 of the bus bar conductor portion 10, fastening holes 11a are disposed for fastening with corresponding electrical connection portions.

Figure 2 shows that the bus bar 1 electrically connects the battery module M installed in the battery pack. The bus bar (1) is installed in the through hole (H) of the partition wall (W) installed between the battery modules (20), and both ends (11) of the exposed metal conductor portion (10) of the bus bar (1) It is connected to the module terminals on both sides of the partition wall.

When, for example, battery modules are electrically connected to the conventional bus bar within a battery pack, no problem occurs in the operation of the battery pack at normal temperatures at which the battery pack operates normally.

However, when a flame occurs inside the battery pack, the temperature of the flame is very high (500 to 800℃, or over 800℃, and in severe cases, over 1000℃), so the silicone rubber or epoxy coating layer melts and the bus bar conductor part is exposed to the outside. It is exposed as. In this case, the exposed bus bar conductor part electrically contacts other metal parts in the pack, causing a short circuit, and the flame spreads further due to heat generation from the electric short circuit.

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

However, in extreme heat generation situations as described above, the materials exemplified above cannot sufficiently prevent heat diffusion. For example, typical heat-resistant silicone rubber has a heat-resistant temperature of only 125 to 300 degrees Celsius, so it cannot effectively deal with ignition situations inside the battery pack. Additionally, mica sheets and glass fiber coating layers do not have sufficient fire resistance.

As such, it is essential for recent battery packs to be designed to prevent flames from escaping to the outside of the pack when internal ignition occurs.

In addition, a design that can thermally and electrically insulate the bus bar conductor from the surroundings is needed even at high temperatures when a flame occurs.

From the above, there is a need for the development of technology that can improve insulation strength and assembly properties while maintaining electrical insulation properties by providing fire resistance at high temperatures.

Korean Patent Publication No. 2022-0001228

The purpose of the present invention is to provide a fire-resistant bus bar that can maintain thermal and electrical insulation for as long as possible even when a flame occurs inside a battery pack.

Additionally, the present invention is to provide a battery pack equipped with the fire-resistant bus bar.

The fire-resistant bus bar of the present invention for solving the above problems includes a bus bar conductor portion; A fire-resistant silicon coating layer that surrounds the bus bar conductor portion except for both ends and is ceramicized at a high temperature to support the bus bar conductor portion; A protective layer surrounding the fireproof silicon coating layer; and an expanded silicon layer surrounding the protective layer and expanding above a predetermined temperature.

The refractory silicon can be ceramicized at a temperature of 500 to 1700°C.

The fire-resistant silicone includes a silicone resin containing a silicone compound represented by the following formula (1); It can be ceramicized by sintering a metal oxide containing silicon oxide.

[Formula 1]

In Formula 1, m and n are each integers of 10 to 30.

The silicone resin and metal oxide may be included in a weight ratio of 1:0.5 to 1.5.

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

The protective layer may be made of glass fiber or mica material.

The expanded silicone may include 100 parts by weight of silicone rubber and 10 to 100 parts by weight of an expanding agent.

The expanding agent may be expanded graphite or expanded vermiculite.

The expansion start temperature of the expanded silicon may be 200 to 250°C.

The fireproof silicon coating layer and the expanded silicon layer are sequentially coated on the protective layer to form a tape-shaped coating portion, and the fireproof bus bar can be manufactured by winding the coating portion tape around the bus bar conductor portion.

The fireproof busbar can be manufactured by inserting the busbar conductor part into a mold and injecting fireproof silicon, or by insert injection molding by injecting the expanded silicon.

The fire-resistant bus bar may be a high-voltage bus bar that electrically connects high-voltage terminals of a plurality of battery modules.

A battery pack as another aspect of the present invention includes a plurality of battery modules; A flame prevention partition installed between the battery modules; The above-described fire-resistant bus bar electrically connecting the battery module; And it may include a pack housing accommodating the battery module and the flame prevention partition.

The flame prevention partition wall is provided with a bus bar installation through hole or a bus bar installation groove, the fire resistant bus bar is seated in the bus bar installation through hole or the bus bar installation groove, and both ends of the fire resistant bus bar are used for the flame prevention. It can be electrically coupled to the terminal portion of the battery module located on both sides of the partition.

The fire-resistant bus bar of the present invention has a fire-resistant silicon coating layer that is ceramicized and supports the bus bar conductor portion instead of a coating layer that burns away when a flame occurs inside the pack, so it can maintain insulating and airtight properties even at high temperatures.

Additionally, the fire-resistant bus bar of the present invention is provided with a protective layer that protects the fire-resistant silicone coating layer. As a result, the shape and size of the fire-resistant silicon coating layer, which may become somewhat fragile as the protective layer surrounds the fire-resistant silicon coating layer and becomes ceramic at a high temperature, can be maintained.

Additionally, the present invention includes an expanded silicon layer that expands above a predetermined temperature on the outside of the protective layer. As a result, for example, it is possible to more reliably prevent flames from spreading by shielding passages within the battery pack that expand when the battery pack ignites and allow flames and high-temperature, high-pressure gases to pass through.

1 is a schematic and cross-sectional view showing a conventional bus bar structure.
Figure 2 is a schematic diagram showing connecting a battery module to a conventional bus bar.
Figure 3 is a perspective view and a cross-sectional view of a fire-resistant bus bar according to an embodiment of the invention.
Figure 4 is a schematic diagram showing an example of a process for manufacturing a fire-resistant bus bar of the present invention.
Figure 5 is a schematic diagram showing another example of the process of manufacturing a fire-resistant bus bar of the present invention.
Figure 6 is a schematic diagram showing an example of a battery pack structure in which the fire-resistant bus bar of the present invention is installed.
Figure 7 is a schematic diagram showing another example of a battery pack structure in which the fire-resistant bus bar of the present invention is installed.
Figure 8 is a side cross-sectional view showing the fire-resistant bus bar of the present invention installed in a battery pack.

Hereinafter, the detailed configuration of the present invention will be described in detail with reference to the attached drawings and various embodiments. The embodiments described below are shown as examples to aid understanding of the present invention, and the attached drawings are not drawn to scale to aid understanding of the invention, and the dimensions of some components may be exaggerated. .

Since the present invention can be subject to various changes and have various forms, specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

[Fireproof bus bar]

The fire-resistant bus bar of the present invention includes: a bus bar conductor portion; A fire-resistant silicon coating layer that surrounds the bus bar conductor portion except for both ends and is ceramicized at a high temperature to support the bus bar conductor portion; A protective layer surrounding the fireproof silicon coating layer; and an expanded silicon layer surrounding the protective layer and expanding above a predetermined temperature.

The bus bar conductor part may be a normal metal conductor part. In other words, it can be made of 99.9% or higher purity tough pitch copper material such as C1100, or it can also be made of aluminum material. That is, the busbar conductor portion of the present invention is not particularly limited as long as it is made of a metal material that can function as a busbar conductor for connecting electrical components. Both ends of the bus bar conductor portion are electrically connected to corresponding electrical connection portions.

The fire-resistant silicone coating layer is a layer that covers the bus bar conductor portion while surrounding the portion excluding both ends of the bus bar conductor portion. That is, the fireproof silicon coating layer is covered around the central portion of the bus bar conductor portion excluding both ends. The refractory silicon coating layer is ceramicized at a high temperature to support the bus bar conductor portion. The refractory silicon can be ceramicized at a temperature of 500 to 1700°C. The fire-resistant silicon of the present invention is distinguished from heat-resistant silicon with 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 flexibility due to the characteristics of silicone, but is a material that burns away or turns into ash at high temperatures above 500°C. Therefore, there is a limit to its application in preventing short-circuiting or heat propagation of a battery pack in a heat propagation situation.

Since the fire-resistant silicone coating layer has 'fire-resistant' properties that make it ceramic at a high temperature of 500°C or higher, it can maintain insulating and airtight properties within the battery pack even when a flame occurs.

In this way, the fire-resistant bus bar according to the present invention can realize high fire-resistant performance by providing fire-resistant silicon inside along with structural improvement.

The fireproof silicone is a composition containing silicone resin and metal oxide as main ingredients, and has flexibility and flexibility due to the characteristics of silicone at room temperature. In addition, it has a certain elasticity and exhibits high impact resistance and insulation, and when exposed to high temperatures, a silicon sintered body with a complex ceramic structure can be formed by sintering silicon resin and metal oxide.

Specifically, the silicone resin contained in fireproof silicon generates silica in powder form when burned at high temperature. The silica produced in this way reacts with the metal oxide of the refractory silicon to form a "eutectic mixture" on the edge of the metal oxide, thereby performing a bridging role between the silica and the metal oxide, so it hardens at the ignition temperature. , when cooled, forms a condensed ceramic product. This ceramic body can exercise the electrical function of the bus bar itself by preventing short circuits or disconnections between conductors due to damage to the fire-resistant silicon coating layer even when external mechanical shock is applied or moisture penetrates in the event of a fire.

For this purpose, the refractory silicone according to the present invention contains a silicone resin and a metal oxide.

The silicone resin is not particularly limited as long as it contains silicon (Si) in the molecule, but preferably may include a silicone compound represented by the following formula (1) (hereinafter referred to as “the silicone compound of formula 1”):

[Formula 1]

In Formula 1, m and n are each integers of 10 to 30.

The silicone compound of Formula 1 includes a methylsiloxane repeating unit, and includes vinyl groups inside and at the ends of the methylsiloxane repeating unit, respectively. The vinyl group is present not only at the ends 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. Through this, it can realize better fire resistance properties compared to silicone compounds that do not contain a vinyl group. You can.

Additionally, the weight average molecular weight of the silicone compound of Formula 1 may be adjusted to a specific range. The silicone compound of Formula 1 is a compound that forms the base of a silicone resin, and depending on the weight average molecular weight of the silicone compound of Formula 1, it can affect the physical properties of fireproof silicon at room temperature and high temperatures. For example, if the weight average molecular weight of the silicone compound of Formula 1 is excessively high, the viscosity of the silicone resin may increase and reactivity may decrease during high temperature sintering, and if the weight average molecular weight is significantly low, the room temperature elasticity and flexibility of the silicone resin may decrease. As a result, the manufacturing process of the fire-resistant bus bar is degraded, and there is a limit to the impact resistance, etc. Therefore, the silicone compound of 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; Alternatively, it may have an adjusted value of 5,000 to 7,000 g/mol.

In addition, the metal oxide is a composition containing silicon oxide, and can act as a crystal nucleus when exposed to high temperature to form a high-density ceramic body together with the above-described silicone resin.

These metal oxides may include one or more of silicon dioxide, silica, quartz, silica, tridymite, and keatite. The metal oxide contains pure silicon dioxide (SiO ₂ ) as well as minerals such as quartz containing silicon dioxide (SiO ₂ ) as a main component, so it is not only highly economical, but also has a high melting point (high refractoriness) and 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 dissolution and molding of refractory silicon, and reduce defects that may occur in ceramic bodies.

In addition, it is good if the metal oxide can be sintered with a silicone resin to have a crystal structure that increases fire resistance, insulation, and mechanical strength. This metal oxide is in the form of a powder, but is not particularly limited, and has a size of 200 μm or less, for example, 0.1 μm to 200 μm; Alternatively, those having a size of 0.1㎛ ~ 100㎛ can be used.

In addition, the silicone resin may further include a silicon compound represented by the following Chemical Formula 2 (hereinafter referred to as “the silicone compound of Chemical Formula 2”), and the silicone compound of Chemical Formula 2, together with the silicon compound of Chemical Formula 1, acts as a metal at high temperature. Participates in sintering of the oxide to form a silicon sintered body:

[Formula 2]

In Formula 2, p is an integer of 10 to 30.

The silicone compound of Formula 2 increases the flexibility of the refractory silicon at room temperature, and can play a role in inducing the completion of sintering of the silicone resin through dehydration condensation with the silicone compound of Formula 1 during sintering, through which The ceramic body formation reaction can be terminated.

For this purpose, 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, based on the total weight of the fireproof silicon; 1 to 6 parts by weight; Alternatively, it may be used in an amount of 2 to 5 parts by weight.

In addition, fireproof silicon may contain silicone resin and metal oxide in a certain ratio in order to realize high elasticity at room temperature and to quickly form a ceramic body when exposed to high temperatures.

Specifically, the refractory silicon may have a weight ratio of silicone resin and metal oxide of 1:0.5 to 1.5, and specifically, 1:0.8 to 1.2. If the weight ratio of the metal oxide is low (less than 0.5), it is difficult to have a ceramic structure with a high density crystal structure at high temperature, so there is a problem of insufficient fire resistance and mechanical strength. Additionally, if the weight ratio of the metal oxide exceeds 1.5, the flexibility of the refractory silicon is reduced at room temperature, resulting in poor handleability.

As an example, the fire-resistant silicone of the present invention contains 35 to 50% by weight of the silicone compound of Formula 1; Quartz 16-32% by weight; 10-27% by weight of silicon dioxide; and a second silicone compound of Formula 2 in an amount of 1 to 6% by weight, and in some cases, a predetermined solvent may be additionally included to increase fairness during manufacturing.

As described above, the refractory silicon of the present invention is hardened by sintering a silicone resin and a metal oxide at 500° C. or higher to become ceramic. In addition, it is ceramicized up to 1700℃, and theoretically, it can partially maintain ceramicization even at temperatures above 1700℃. However, if the temperature exceeds 1700°C, the ceramicization retention time becomes shorter and the fire resistance required for the battery pack may not be maintained.

Before being ceramicized, the refractory silicone has rubber-like properties such as flexibility, flexibility, and elasticity, as described above. Therefore, it is easy to injection mold the fire-resistant silicone coating layer or coat it on the bus bar conductor as described later.

Since the fireproof silicon coating layer has flexibility before being ceramicized, it can flexibly follow the deformation of the bus bar conductor portion. Therefore, when installing the fire-resistant bus bar of the present invention in a battery pack, even if there is a slight assembly tolerance, it can be easily accommodated, thereby improving assembly efficiency. For example, when attaching a battery module to a battery pack by bolting, if the bus bar conductor portion connected to the battery module moves or is slightly distorted, the fireproof silicon coating layer can absorb such movement or distortion. Additionally, even when the battery pack vibrates due to the vibration of the electric vehicle, the fireproof silicon coating layer can naturally absorb the vibration.

On the other hand, when the refractory silicon is ceramicized at a high temperature, thermal and electrical insulation is maintained, but the mechanical strength is somewhat weakened and there is a risk of breaking by external force. In the present invention, in order to structurally improve the rigidity of the fire-resistant silicon coating layer, a protective layer surrounding the fire-resistant silicon coating layer is provided.

The protective layer is a layer that surrounds the outside of the fire-resistant silicon coating layer and protects the fire-resistant silicon coating layer from being directly exposed to flame. Additionally, when the refractory silicon coating layer is ceramicized, the overall shape and dimensions of the coating layer can be maintained by wrapping the ceramicized coating layer.

As the protective layer, for example, a material such as glass fiber or mica material, which has both insulating properties and heat resistance, can be used. That is, glass fiber tape or mica tape can be wrapped around the outside of the fireproof silicone coating layer to prevent the fireproof silicone coating layer from being exposed to the outside. However, the protective layer is not limited to this, and it is also possible to construct the protective layer from other materials with excellent insulation or heat resistance.

An expanded silicon layer that expands above a predetermined temperature is disposed on the outside of the protective layer. That is, the present invention includes a fire-resistant silicon coating layer surrounding the busbar conductor portion and an expanded silicon layer surrounding the protective layer again on the outside of the protective layer surrounding the fire-resistant silicon coating layer. In this sense, the bus bar of the present invention can be said to have a double silicon coating structure.

In this way, the present invention can realize high fire resistance performance along with structural improvement of the fire resistant bus bar by double silicon coating.

The expanded silicone is a composition containing silicone rubber and an expanding agent as main ingredients. It has a certain elasticity at room temperature, exhibits high impact resistance and insulation, and can have a structure that expands due to the expanding agent when exposed to high temperatures.

Specifically, when silicone rubber containing an expansion agent is exposed to high temperature, that is, the expansion start temperature of the expansion agent, the expansion agent begins to expand from the surface of the silicone rubber. As a char layer is formed on the surface of the silicone rubber where the expansion agent has expanded, it blocks external heat and air from entering the empty space, and can provide fire resistance properties by preventing the spread of heat conduction or limiting heat transfer to the inside. there is.

For this purpose, the expanded silicone according to the present invention includes silicone rubber and an expanding agent.

At this time, the silicone rubber is a base resin of expanded silicone and may include, but is not limited to, a polysiloxane resin having a siloxane structure and containing a vinyl group therein.

As one example, the silicone rubber may include a silicone resin (polysiloxane resin) represented by Formula 1 above.

That is, the silicone rubber that can be included as a component of the expanded silicone may include a silicone resin that can be a component of the fireproof silicone. In this case, in the refractory silicone composition, the silicone resin is sintered with a metal oxide and turned into ceramic at high temperature, but in the expanded silicone, the silicone resin (silicone rubber) provides a surface on which the expansion agent can expand.

The polysiloxane resin includes a methylsiloxane repeating unit, and includes vinyl groups inside and at the ends of the methylsiloxane repeating unit, respectively. The vinyl group is present not only at the ends of the polysiloxane resin but also inside the repeating unit, and plays a role in increasing the curing rate of silicone rubber when exposed to high temperatures. Through this, better heat resistance characteristics can be realized compared to polysiloxane resin that does not contain a vinyl group.

Additionally, the weight average molecular weight of the polysiloxane resin can be adjusted to a specific range. Polysiloxane resin is a compound that forms the base of silicone rubber, and depending on the weight average molecular weight of the polysiloxane resin, it can affect the physical properties of expanded silicone at room and high temperatures. For example, if the weight average molecular weight of the polysiloxane resin is excessively high, the viscosity of the silicone rubber may increase and the curing rate may decrease when exposed to high temperatures, and if the weight average molecular weight is significantly low, the room temperature elasticity and flexibility of the silicone rubber may be reduced. There is a limit to the fact that fairness deteriorates and impact resistance etc. decreases. Therefore, the polysiloxane resin may have a weight average molecular weight adjusted to 1,000 to 9,000 g/mol, specifically 3,000 to 8,000 g/mol; Alternatively, it may have an adjusted value of 5,000 to 7,000 g/mol.

Additionally, the expanding agent may be either expanded graphite or expanded vermiculite, but is not limited thereto.

The expanded vermiculite is a unique mineral that contains three types of moisture: absorbed water, interlayer water, and crystallized water. Pressure is generated, and the vermiculite is peeled and expanded by the generated pressure.

In this way, vermiculite expanded at high temperature has a very low specific gravity and has excellent insulation properties, non-flammability, noise blocking effect, moisture absorption effect, physical shock absorption effect, and the effect of an extender and filler.

The expanded vermiculite may have a particle size with an average diameter of 0.3 to 4 mm, but is not limited thereto. If the average diameter of expanded vermiculite exceeds 4 mm, compatibility with silicone rubber is poor, and if the average diameter of expanded vermiculite is less than 0.3 mm, material costs increase. Expanded vermiculite has a particle size of 0.3 to 4 mm in average diameter. It is preferable to have, and more preferably, a particle size with an average diameter of 0.3 to 0.7 mm is appropriate.

The expanded graphite refers to a sulfuric acid-graphite compound that contains oxygen between graphite layers by treating the graphite compound with sulfuric acid. The expanded graphite expands as oxygen present between graphite layers is vaporized into moisture when exposed to high heat.

This expanded graphite has a higher expansion rate (approximately 320 times) compared to expanded vermiculite (expansion rate: approximately 6 to 20 times), which can increase the efficiency of expanding expanded silicon at high temperatures. In addition, since it is incombustible in itself, the fire resistance and/or flame retardancy of the refractory bus bar can be significantly improved through the formation of a carbonized layer on the surface of the expanded silicone, and it acts as a filler for silicone rubber to increase the tear strength of the refractory bus bar. It can be improved further.

Here, the expanded graphite may have an expansion start temperature of 200 to 250°C and an expansion rate of 20 to 350 cm ³ /g, but is not limited thereto. Specifically, expanded graphite expands as moisture is evaporated when oxygen between graphite layers receives high heat. At this time, the expansion rate may range from 20 to 350 cm ³ /g, more preferably 200 to 350 cm ³ /g. It is g.

Specifically, if the expansion rate of the expanded graphite is less than 200 cm ³ /g, the surface of the silicone rubber does not expand sufficiently during combustion, so it cannot prevent heat diffusion and block external heat and air, so fire resistance is not realized. Additionally, the If the expansion rate exceeds 350 cm ³ /g, there is a problem that may cause an increase in material costs.

Additionally, the swelling agent may have a predetermined content ratio with silicone rubber. Specifically, the expanding agent may be included in the expanded silicone in an amount of 10 to 100 parts by weight based on 100 parts by weight of silicone rubber, and more specifically, 30 to 70 parts by weight based on 100 parts by weight of silicone rubber; 40 to 60 parts by weight; Alternatively, it may be included in expanded silicone in an amount of 50 to 90 parts by weight.

If the content of the expansion agent is less than 10 parts by weight per 100 parts by weight of silicone rubber, not only does it not achieve sufficient expansion of the expanded silicone exposed to high temperatures, but also the thickness of the char layer formed on the surface of the expanded silicone is thin, resulting in high fire resistance. There is a problem that cannot be manifested. In addition, if the content of the expanding agent exceeds 100 parts by weight based on 100 parts by weight of silicone rubber, not only does compatibility with silicone rubber deteriorate at room temperature, but the elasticity and flexibility of the expanded silicone also decrease, which not only improves fairness but also reduces the fireproof bus manufactured using it. There is a problem that the durability of the bar is reduced.

Furthermore, the expanded silicone may further include a plasticizer, a heat resistant agent, a flame retardant, a curing agent, etc. in order to control physical properties at room temperature and/or high temperature in addition to silicone rubber and an expanding agent.

As an example, the expanded silicone may further include a curing agent containing a silicon compound such as silicone oil, silica, tetravinyl cyclotetrasiloxane, and octamethyl cyclotetrasiloxane, and the curing agent may contain a trace amount of a catalyst such as platinum along with a silicon compound.

In general, silicone rubber is cured by crosslinking the siloxane chain through an addition reaction between polysiloxane containing a vinyl group and polysiloxane having Si-H bonds. However, if expanded graphite is contained, the curing efficiency of silicone rubber may be reduced. Therefore, the curability of expanded silicone containing silicone rubber and expanded graphite can be improved by further including a curing agent.

At this time, the curing agent may be contained in an amount of 5 to 20 parts by weight based on 100 parts by weight of silicone rubber, and specifically, 5 to 15 parts by weight based on 100 parts by weight of silicone rubber; Alternatively, it may be contained in 11 to 18 parts by weight. If the content of the curing agent is less than 5 parts by weight, the curability of the expanded silicone may decrease, which may cause a problem of insufficient curing. If the content of the curing agent exceeds 20 parts by weight, the fire resistance decreases, and curing of the expanded silicone at room temperature may occur. There is a limit to how hard it can progress.

As an example, the expanded silicone includes 40 to 80% by weight of polysiloxane resin of Formula 1; 15-40% by weight of bulking agent; And it may include 1 to 20% by weight of a hardener.

The specific form and manufacturing method of the fire-resistant bus bar will be described in detail in the following embodiments.

(First Embodiment)

Figure 3 is a perspective view and a cross-sectional view of a fire-resistant bus bar according to an embodiment of the invention, and Figure 4 is a schematic diagram showing an example of a process for manufacturing the fire-resistant bus bar 100 of the present invention.

As shown, the fire-resistant bus bar 100 is provided with a bus bar conductor portion 110 on the innermost side, and a coating portion (P) is formed on the portion of the bus bar conductor portion 110 except for both ends 111. It is equipped with Both ends 111 of the bus bar conductor portion 110 are exposed to the outside and are provided with fastening holes 111a for coupling with corresponding electrical connection portions (eg, terminal portions).

The coating portion (P) includes a fire-resistant silicon coating layer 120 surrounding the busbar conductor portion 110, a protective layer 130 surrounding the fire-resistant silicon coating layer 120, and an expanded silicon layer 140 surrounding the protective layer. ) is provided.

The thickness of the fire-resistant silicon coating layer 120, the protective layer 130, and the expanded silicon layer 140 can be appropriately determined depending on the required insulation and fire resistance of the bus bar. Since the fireproof silicon coating layer 120 is a core coating layer that surrounds the bus bar conductor portion 110 and is made of ceramic to maintain insulation performance, it is preferable to be formed thicker than the protective layer 130 and the expanded silicon layer 140. In other words, even if it becomes ceramic and becomes partially brittle, it is better to form it with a volume and thickness sufficient to maintain the shape of the fire-resistant silicon coating layer 120 surrounding the bus bar conductor portion 110 as a whole.

It is sufficient for the protective layer 130 to surround the fireproof silicon coating layer 120 and maintain the overall shape of the coating layer. Therefore, the protective layer 130 does not need to be excessively thick. For example, the protective layer can be made of glass fiber tape or mica tape with a thickness of about 0.1 to 1 mm.

The present invention includes an expanded silicon layer 140 on the outermost layer. That is, in the present invention, the insulating layer can be composed of three layers: a fireproof silicon coating layer 120, a protective layer 130, and an expanded silicon layer 140. Since the outermost expanded silicon layer 140 is exposed to the outside and expanded at high temperature, its thickness and volume can be determined by considering the installation space of the fireproof bus bar. If there is sufficient expansion space, there is theoretically no need to limit the thickness of the expanded silicon layer. However, considering insulation and fire resistance and manufacturing costs, there is no need to make the expanded silicon layer excessively thick. Additionally, when a fire-resistant bus bar is installed in a limited space, it is sufficient to include an expansion agent sufficient to expand within the space. Therefore, it is desirable to determine the thickness of the expanded silicon layer by considering the size of the installation space. In addition, since the expanded silicon layer exhibits insulation and fire resistance performance together with the fire-resistant silicon coating layer, it is better to determine the thickness by considering the thickness of the fire-resistant silicon coating layer.

The coating portion (P) may be formed in a tape shape. In Figure 4, it is shown that the coating portion (P) is molded into a tape shape.

For example, a protective layer tape of a predetermined length (length surrounding the circumference of the busbar conductor portion), such as a glass fiber tape or mica tape, may be prepared, and a heat-resistant silicone coating layer 120 may be coated on the protective layer tape. That is, as shown in FIG. 4, fire-resistant silicon can be injected from the nozzle 151 of the fire-resistant silicon storage tank 150 located on the upper part of the protective layer tape 140 toward the protective layer tape 140. As described above, refractory silicone is, for example, a mixture of a silicone resin and a metal oxide, and can be contained in a predetermined solvent in the form of a fluid coating liquid or slurry.

By injecting this fire-resistant silicone coating liquid onto the upper surface of the protective layer tape 140 and going through drying and a predetermined curing process, a protective layer tape coated with fire-resistant silicon can be made.

This coated protective layer tape can be wound on the busbar conductor portion 110, and the expanded silicon layer can be coated again on the rolled protective layer tape.

In terms of the manufacturing process, it is advantageous to coat the expanded silicone again on the protective layer tape coated with the fireproof silicone. That is, as in FIG. 4, the expanded silicon coating liquid is injected from the nozzle of the expanded silicon storage tank (not shown) onto the protective layer tape coated with fireproof silicon. As a result, it is possible to create a tape-shaped coating portion P in which a fireproof silicon coating layer and an expanded silicon layer are sequentially coated on the protective layer tape. The fireproof bus bar 100 of the form shown in FIG. 3 can be manufactured by wrapping this coating portion (P) tape around the bus bar conductor portion.

(Second Embodiment)

Figure 5 is a schematic diagram showing another example of the process of manufacturing the fire-resistant bus bar of the present invention.

In this embodiment, the fire-resistant bus bar 100 is manufactured by a type of insert injection molding method in which the bus bar conductor portion 110 is placed in advance in a mold and fire-resistant silicon or expanded silicon is injected into the mold.

A bus bar conductor portion 110 is disposed within the upper and lower molds 160 and 160' for insert injection molding in FIG. 5. Thereafter, the coating liquid or slurry of refractory silicon is injected through the injection port 161 provided in the molds 160 and 160'. As a result, a semi-finished product in which the busbar conductor portion 110 and the fireproof silicon coating layer 120 are integrated can be manufactured. Thereafter, a protective layer 130, such as a glass fiber tape, is wound on the integrated semi-finished product. Next, the semi-finished product with the protective layer 130 wrapped around it is placed again in similar molds 170 and 170', and the coating liquid or slurry of expanded silicon is injected through the injection hole 171 and molded. Afterwards, the final product fire-resistant bus bar can be manufactured through a predetermined drying and curing process.

In this embodiment, the thickness of the refractory bus bar covering layer 120 or the thickness of the expanded silicon layer 140 can be easily adjusted depending on the mold size.

[Battery Pack]

Figure 6 is a schematic diagram showing an example of a battery pack structure in which a fire-resistant bus bar of the present invention is installed, Figure 7 is a schematic diagram showing another example of a battery pack structure in which a fire-resistant bus bar of the present invention is installed, and Figure 8 is a schematic diagram showing another example of a battery pack structure in which a fire-resistant bus bar of the present invention is installed. This is a side cross-sectional view showing the bus bar installed in the battery pack.

The fire-resistant bus bar 100 of the present invention described above includes a fire-resistant silicon coating layer 120 that is ceramicized at a high temperature, a protective layer 130 that surrounds the fire-resistant silicon coating layer 120 and maintains its shape, and the protective layer. It is provided with an expanded silicon layer 140 surrounding the . Therefore, when applied to a battery pack where internal combustion may occur, the safety of the battery pack can be greatly improved.

The fire-resistant bus bar 100 can be used, for example, to electrically connect a plurality of battery modules accommodated in a battery pack to each other. In this case, the fire-resistant bus bar 100 can electrically connect terminal portions of adjacent battery modules. Alternatively, the fire-resistant bus bar 100 may be used to connect battery modules to external electrical devices.

In particular, the high-voltage terminals of the battery module generate relatively high heat due to high current. Accordingly, when a flame occurs inside the pack, higher heat may be concentrated in the high voltage terminal. Therefore, the fire-resistant bus bar 100 of the present invention is suitable for application as a high-voltage bus bar that electrically connects the high-voltage terminal parts of a plurality of battery modules.

The battery pack 1000 of the present invention includes a plurality of battery modules 200; A flame prevention partition 300 installed between the battery modules; The above-described fire-resistant bus bar 100 electrically connecting the battery module; And it may include a pack housing 400 that accommodates the battery module and a flame prevention partition.

Referring to FIG. 6, a plurality of battery modules 200 are shown being 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 derived 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 interbus bar. The fire-resistant bus bar 100 according to the present invention can be applied to electrically connect the plurality of battery modules.

Meanwhile, Figures 6 and 7 show a typical battery module 200 in which the module housing completely surrounds the top, bottom, left, and right sides of the battery cell stack. However, it is not limited to this, for example, a battery module having a module housing of a modular structure configured to open at least one of the top, bottom, left, and right sides of the cell stack, or a battery module in which the entire top, bottom, left, and right sides of the cell stack are open. The fire-resistant bus bar 100 of the present invention can also be applied to battery cell blocks. In this way, cell blocks or battery modules with all or part of the module housing omitted can be installed in the battery pack to form a battery pack with a so-called cell-to-pack structure. The fire-resistant bus bar 100 of the present invention can be used for electrical connection of battery modules of a cell block or module-less structure installed in a battery pack of this cell-to-pack structure.

In order to prevent flame spread between adjacent modules, the battery pack 1000 may include a flame prevention partition 300 installed between battery modules. The flame prevention partition 300 may be made of metal to ensure rigidity. The flame prevention partition 300 functions to prevent the flame from spreading to adjacent modules when a fire occurs in one module. In this case, the flame prevention partition 300 may be provided with a bus bar installation through hole 310 or a bus bar installation groove 320. Figure 6 shows that the flame prevention partition 300 is provided with a bus bar installation through hole 310, and Figure 7 shows that the flame prevention partition 300 is provided with a bus bar installation groove 320. In terms of flame prevention and airtightness, a partition wall provided with a bus bar installation through hole 310 as shown in FIG. 6 is advantageous. Since the top of the bus bar installation groove 320 in FIG. 7 is open, it is convenient to install the bus bar and perform electrical connection work on the bus bar.

The fire-resistant bus bar 100 may be seated in the bus bar installation through hole 310 or the bus bar installation groove 320. At this time, both ends 111 of the bus bar conductor portion 110 may be electrically coupled to the terminal portions 210 and 220 of the battery module 200 located on both sides of the flame prevention partition 300.

FIG. 8 shows the fire-resistant bus bar 100 electrically connecting the battery module 200 within the battery pack 1000. A flame-prevention partition wall 300 is located between neighboring battery modules 200, and the flame-prevention partition wall is provided with a bus bar installation through hole 310. The fire-resistant bus bar 100 of the present invention is inserted into the through hole.

The expanded silicon layer 140 is disposed on the outermost side of the fire-resistant bus bar 100 to form a primary fire-resistant wall. Additionally, when the temperature inside the pack rises and reaches a predetermined expansion start temperature (eg, 200 to 250°C), the pack expands by the expansion agent contained therein. For example, when the fire-resistant bus bar 100 is installed in the bus bar installation through hole 310 of the flame prevention partition 300 as shown in FIGS. 6 and 8, the expanded silicon layer 140 is primarily damaged when internal ignition occurs. It may be expanded to shield the through hole 310. As a result, the battery modules 200 arranged with the flame prevention partition 300 are completely shielded from each other, so that flames and high-temperature, high-pressure gas cannot move. As a result, heat propagation can be blocked when a flame occurs within the battery pack.

Thereafter, when the temperature rises further, the refractory silicon coating layer 120 becomes ceramic. When a flame occurs within the battery pack 1000, in the fire-resistant bus bar of the present invention, the fire-resistant silicon coating layer 120 surrounding the bus bar conductor portion 110 is ceramicized to form a dense sintered body. In other words, it does not burn out or turn to ash at high temperatures of 500°C or higher like conventional heat-resistant silicon, but becomes ceramic and maintains its shape. Accordingly, the fireproof silicon coating layer 120 stably supports the busbar conductor portion 110 even when a flame occurs.

At this time, the protective layer 130 surrounds the refractory silicon coating layer 120 to prevent deformation of the ceramicized refractory silicon coating layer and maintain its shape, further enhancing insulation and fire resistance.

As described above, according to the present invention, the expanded silicon layer surrounding the bus bar conductor unit primarily protects against flames, and the fire-resistant silicone coating layer secondarily protects against flames, providing a two-stage protection function. In this process, the protective layer maintains the shape of the fire-resistant silicon coating layer, thereby maintaining the insulation and strength of the fire-resistant silicon coating layer.

Meanwhile, the expansion start temperature of the expanded silicon and the ceramicization temperature of the refractory silicon coating layer may be the same or different. However, since the expanding agent of expanded silicon can maintain the expanded state even at the high temperature at which refractory silicon becomes ceramic after being expanded at the expansion start temperature, the expansion start temperature can be set to a temperature lower than the ceramization temperature. When the expansion start temperature and the ceramicization temperature are set to be the same, the expansion of the expanded silicon and the ceramicization of the refractory silicon can occur with a slight time lag or almost simultaneously.

[Example]

(Example 1)

Fireproof silicon consisting of 50% by weight of the silicon compound of Formula 1, 20% by weight of quartz, and 30% by weight of pure silicon dioxide was applied to all areas except both ends of the conductor portion of the copper bus bar having a predetermined cross-sectional area selected from the range of 0.5 to 3 mm ^2. The part was coated to a predetermined thickness. A 0.18 mm thick glass fiber tape (product name: AGT6WO) from SWECO was wound twice on the fireproof silicon coated busbar to form a protective layer surrounding the fireproof silicone coating layer. Next, expanded silicon consisting of 100 parts by weight of the silicon compound (polysiloxane compound) of Formula 1 and 30 parts by weight of expanded graphite was coated on the protective layer to a predetermined thickness to prepare the fireproof bus bar of Example 1.

The bus bar of Comparative Example 2 was manufactured by wrapping AGT6WO glass fiber tape over the central part of the bus bar conductor part with the length of the bus bar conductor part and the exposed length of both ends the same as in Example 1. The coating thickness of the wound glass fiber tape was almost the same as that of Example 1.

As the busbar of Comparative Example 2, a mica tape made of phlogopite mica, a natural mica, was wound around the central part of the busbar conductor, and an AGT6WO glass fiber tape was wound on it. The length of the bus bar conductor portion and the exposed length of both ends are the same as Example 1 and Comparative Example 1.

In order to test the insulation characteristics (insulation maintenance performance) in the event of a fire, copper wire was wound with the same number of turns around the covering of the bus bars of Examples 1 to Comparative Examples 2, and one end of the outermost copper wire of the covering was tested with a withstand voltage tester. It was connected to the negative terminal, and one end of the bus bar conductor was connected to the positive terminal of the withstand voltage tester. With a voltage of 1000 V applied to the bus bars using a withstand voltage tester, the entire surface of the bus bars was uniformly heated using a large torch with a flame temperature of 1100 to 1150°C.

The insulation fail time at which the insulation state is destroyed, that is, a short circuit occurs, was measured under the above voltage and heating temperature conditions, and the measurement results are shown in Table 1 below.

Busbar configuration Insulation Fail Time Comparative Example 1 Copper busbar conductor + glass fiber tape 2 minutes 35 seconds Comparative Example 2 Copper busbar conductor + mica tape + glass fiber tape 13 minutes Example 1 Copper bus bar conductor + fireproof silicone coating layer + glass fiber tape + expanded silicone layer 19 minutes

As shown in Table 1, the fire-resistant bus bar according to the present invention had the longest insulation failure time, and showed a significant difference from Comparative Example 1 and Comparative Example 2 in terms of insulation failure time.

Therefore, it can be seen that the insulation characteristics of the fire-resistant bus bar of the present invention described above are very excellent.

(Example 2)

Fireproof silicone with the composition shown in Table 2 below was prepared by varying the weight ratio of the silicon compound of Formula 1 and the weight ratio of the metal oxide.

A fire-resistant silicone coating layer was coated to a predetermined thickness on the copper busbar conductor under the same conditions as in Example 1, and an AGT6WO glass fiber tape was wound on the fire-resistant silicone coating layer, and then the expanded silicon layer was glassed in the same manner as in Example 1. It was coated on a fiber tape. The composition of the expanded silicon layer was 100 parts by weight of silicon compound (polysiloxane compound) and 30 parts by weight of expanded graphite, as in Example 1.

A copper wire was wound around the bus bar conductor under the same conditions as in Example 1, and one end of the copper wire and one end of the bus bar conductor were connected to a withstand voltage tester. With voltage applied, it was heated with a large torch under the same conditions as in Example 1, and the insulation fail time was measured. The measurement results are shown in Table 2 below.

Example 2 Composition of fireproof silicone coating layer Insulation Fail Time Experimental Example 2-1 Silicone compound 50% by weight: Metal oxide 50% by weight
(Quartz: 20% by weight, pure silicon dioxide: 30% by weight) 19 minutes Experimental Example 2-2 Silicone compound 50% by weight: Metal oxide 25% by weight
(Quartz: 10% by weight, pure silicon dioxide: 15% by weight) 16 minutes 10 seconds Experimental Example 2-3 Silicone compound 50% by weight: Metal oxide 75% by weight
(Quartz: 30% by weight, pure silicon dioxide: 45% by weight) 22 minutes Experimental Example 2-4 Silicone compound 50% by weight: Metal oxide 20% by weight
(Quartz: 10% by weight, pure silicon dioxide: 10% by weight) 15 minutes 30 seconds Example 2-5 Silicone compound 50% by weight: Metal oxide 80% by weight
(Quartz: 35% by weight, pure silicon dioxide: 45% by weight) 22 minutes 40 seconds

In Experimental Examples 2-1 to 2 to 5, the weight ratio of the silicon compound and the metal oxide was 1:1, 1:0.5, 1;1.5, 1:0.4, and 1:1.6.

All examples have much longer insulation fail times than Comparative Examples 1 and 2. However, in the case of Experimental Example 2-4 where the weight ratio was less than 0.5, the insulation failure time was somewhat short, which is believed to be because the metal oxide was not sufficient and the creation of a ceramic structure with a high-density crystal structure at high temperature was somewhat insufficient.

In addition, in the case of Experimental Example 2-5 where the weight ratio was 1.6, the insulation failure time was sufficiently long, but the flexibility of the refractory silicon decreased at room temperature due to excessive metal oxide, making it difficult to follow and cover the bus bar conductor.

(Example 3)

The composition of the fire-resistant silicone coating layer was set under the same conditions as in Example 1, and an AGT6WO glass fiber tape was wound on the fire-resistant silicone coating layer, and then the expanded silicone layer was coated on the glass fiber tape with a different composition.

A copper wire was wound around the bus bar conductor under the same conditions as in Example 1, and one end of the copper wire and one end of the bus bar conductor were connected to a withstand voltage tester. With voltage applied, it was heated with a large torch under the same conditions as in Example 1, and the insulation failure time was measured. The measurement results are shown in Table 3 below.

Example 3 Expanded silicone layer composition Insulation Fail Time Experimental Example 3-1 100 parts by weight of silicone rubber: 30 parts by weight of expanded graphite 19 minutes Experimental Example 3-2 100 parts by weight of silicone rubber: 8 parts by weight of expanded graphite 15 minutes 10 seconds Experimental Example 3-3 100 parts by weight of silicone rubber: 100 parts by weight of expanded graphite 20 minutes Experimental Example 3-4 100 parts by weight of silicone rubber: 110 parts by weight of expanded graphite 17 minutes

In Experimental Examples 3-1 to 3 to 4, the weight ratio of silicone rubber and expanded graphite was 1:0.3, 1:0.08, 1:1, and 1:1.1.

All experimental examples had much longer insulation failure times than Comparative Examples 1 and 2. However, in the case of Experimental Example 3-2, in which expanded graphite was contained in a small amount, the char layer formed on the surface of the expanded silicon was thin due to the small amount of expander, and the fire resistance was somewhat reduced.

In addition, in the case of Experimental Example 3-4 containing 110 parts by weight of expanded graphite, the expanding agent was excessively contained, which not only reduced the durability of the fire-resistant bus bar containing it, but also caused flame to enter the excessively expanded gap, resulting in fire resistance (insulation failure). You can see that time) actually drops slightly.

Above, the present invention has been described in more detail through drawings and examples. However, since the configurations described in the drawings or examples described in this specification are only one embodiment of the present invention and do not represent the entire technical idea of the present invention, at the time of filing this application, various equivalents and It should be understood that variations may exist.

100: Fireproof bus bar
110: Busbar conductor part
120: Fireproof silicone coating layer
130: protective layer
140: Expanded silicon layer
150: Fireproof silicon storage tank
160,160': Top and bottom mold
170,170': Top and bottom mold
200: Battery module
210,220: Terminal part
300: Bulkhead for flame prevention
310: Busbar installation through hole
320: Busbar installation groove
400: pack housing
1000: Battery pack

Claims (14)

Busbar conductor section;
A fire-resistant silicon coating layer that surrounds the bus bar conductor portion except for both ends and is ceramicized at a high temperature to support the bus bar conductor portion;
A protective layer surrounding the fireproof silicon coating layer; and
A fireproof bus bar surrounding the protective layer and including an expanded silicon layer that expands above a predetermined temperature.
According to paragraph 1,
The refractory silicon is a refractory bus bar that becomes ceramic at a temperature of 500 to 1700°C.
According to paragraph 1,
The fire-resistant silicone includes a silicone resin containing a silicone compound represented by the following formula (1); A refractory busbar characterized in that it is ceramicized by sintering a metal oxide containing silicon oxide:
[Formula 1]

In Formula 1, m and n are each integers of 10 to 30.
According to paragraph 3,
A refractory bus bar containing the silicone resin and metal oxide in a weight ratio of 1:0.5 to 1.5.
According to paragraph 3,
The metal oxide containing silicon oxide is a refractory bus bar containing one or more of pure silicon dioxide, silica, quartz, silica, tridymite, and keatite.
According to paragraph 1,
The protective layer is a fireproof bus bar made of glass fiber or mica.
According to paragraph 1,
The expanded silicone is a fireproof bus bar containing 100 parts by weight of silicone rubber and 10 to 100 parts by weight of an expanding agent.
In clause 7,
A refractory bus bar wherein the expanding agent is expanded graphite or expanded vermiculite.
In clause 7,
A fireproof bus bar where the expansion start temperature of the expanded silicon is 200 to 250°C.
According to paragraph 1,
A fireproof bus bar manufactured by sequentially coating the fireproof silicon coating layer and the expanded silicon layer on the protective layer to form a tape-shaped coating portion, and winding the coating portion tape around the bus bar conductor portion.
According to paragraph 1,
A fire-resistant bus bar manufactured by insert injection molding by inserting the bus bar conductor part into a mold and injecting fire-resistant silicon, or injecting the expanded silicon.
According to paragraph 1,
The fire-resistant bus bar is a high-voltage bus bar and a fire-resistant bus bar that electrically connects high-voltage terminals of a plurality of battery modules.
A plurality of battery modules;
A flame prevention partition installed between the battery modules;
A fireproof bus bar according to any one of claims 1 to 12 electrically connecting the battery module; and
A battery pack including a pack housing accommodating the battery module and a flame prevention partition.
According to clause 11,
The flame prevention partition has a bus bar installation through hole or a bus bar installation groove,
The fireproof bus bar is seated in the bus bar installation through hole or bus bar installation groove,
A battery pack in which both ends of the fire-resistant bus bar are electrically coupled to terminal parts of a battery module located on both sides of the flame prevention partition.

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