Fire-extinguishing composition and battery pack comprising same

Abstract

The present invention relates to a fire-extinguishing composition and a battery pack comprising same. The fire-extinguishing composition comprises an inorganic compound and a polybasic acid compound in a predetermined content ratio and has the viscosity at room temperature controlled to be within a predetermined range and thus, when a thermal event occurs in the battery pack, enables a fire-extinguishing film to be uniformly formed at the spot where the event has occurred, thereby having high cooling and smothering effects for fire-extinguishing. In addition, the battery pack comprising same enables rapidly detecting a spot where a thermal event has occurred and directly and intensively spraying the fire-extinguishing composition on said spot and thus has the advantages of not only enabling the easy prevention of the spreading of the thermal event but also enabling the reduction of the time required to resolve the event.

Description

Digestive composition and battery pack containing the same

[0001] The present invention relates to a fire extinguishing composition and a battery pack comprising the same.

[0002] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2024-0042899, dated March 29, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] Secondary batteries, with their ability to be repeatedly charged and discharged, are attracting significant attention in a wide range of applications, from small mobile devices to electric and hybrid vehicles, and even energy storage systems (ESS). Furthermore, applications utilizing secondary batteries are becoming increasingly diverse, and battery types are being developed to provide the appropriate output and capacity.

[0005] Secondary batteries used in electric vehicles and energy storage systems are used as so-called medium- to large-sized battery packs, which are made up of a large number of battery cells electrically connected, due to the need for high output and large capacity.

[0006] Medium- to large-sized battery packs are comprised of multiple battery modules housed within a case and electrically connected. They are equipped with various safety and control devices to prevent overcharging, overdischarging, overcurrent, overheating, and fire or explosion caused by chain reactions during use. The control devices continuously monitor the voltage, current, and temperature of the battery cells and control battery operation. However, even with these control devices, electrical failures can occur at any time due to external physical shock or vibration, or internal problems. It is a well-known fact that electrical failures in battery packs are highly likely to lead to fire and explosion.

[0007] Fires occurring in battery packs often begin with an abnormal temperature rise and internal gas generation within the lithium secondary batteries located within the battery module. When the internal pressure of a lithium secondary battery rises above a certain level due to an abnormal temperature rise and the generation of internal gas, venting occurs. This causes high-temperature gas to escape from the lithium secondary battery, creating a high-temperature spark containing electrode active material and aluminum particles. When these high-temperature gases and sparks come into contact with oxygen, a fire can occur.

[0008] If a thermal event, such as abnormally high temperature, gas venting, sparking, or fire caused by this, occurs in some of the battery modules included in the battery pack, and appropriate measures are not taken, the thermal event may spread to adjacent battery modules.

[0009] Therefore, there is a need to develop a battery pack that can effectively prevent and resolve the spread of thermal events occurring within the battery pack.

[0010]

[0011] Accordingly, an object of the present invention is to provide a technology that can effectively resolve a thermal event that has occurred while preventing it from spreading when the thermal event occurs in a device such as a battery pack including a plurality of battery cells.

[0012]

[0013] To solve the above-mentioned problem,

[0014] The present invention,

[0015] 100 parts by weight of an inorganic compound represented by the following chemical formula 1 and 0.01 to 5 parts by weight of a polyacid compound are mixed in water,

[0016] Provided is a fire extinguishing composition characterized in that the viscosity at 25±3℃ is in the range of 2,000 mPa·s to 10,000 mPa·s:

[0017] [Chemical Formula 1]

[0018] M p O q (OH) r

[0019] In chemical formula 1,

[0020] M is magnesium or aluminum,

[0021] p is an integer from 1 to 10, q is an integer from 0 to 20, and p≤q,

[0022] r is an integer from 1 to 5.

[0023] The above fire extinguishing composition contains an inorganic compound represented by Chemical Formula 1 and a polyacid compound in a predetermined content ratio to delay or extinguish ignition when a thermal event occurs in a battery pack.

[0024] The inorganic compound represented by the above chemical formula 1 may include at least one of boehmite, pseudoboehmite, diaspore, akdalaite, aluminum trihydroxide, and magnesium hydroxide.

[0025] The above polycarboxylic acid compound may include at least one of malonic acid, citric acid, malic acid, oxalic acid, glutamic acid, aspartic acid, amino acid, fatty acid, methanetricarboxylic acid, ethanetricarboxylic acid, benzene-1,3,5-tricarboxylic acid, 5-sulfo-1,2,4-benzenetricarboxylic acid, ethane-1,1,2,2-tetracarboxylic acid, propane-1,1,2,3-tetracarboxylic acid, butane-1,2,3,4-tetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid, benzene-1,2,4,5-tetracarboxylic acid, benzene-1,2,3,4,5-pentacarboxylic acid, and benzene-1,2,3,4,5,6-hexacarboxylic acid.

[0026] Additionally, the above-described digestion composition may further comprise at least one pH adjusting agent selected from the group consisting of sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, ammonium carbonate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, ammonium chloride, ammonium molybdate, ammonium bromate, ammonium acetate, ammonium nitrate, and ammonium sulfate.

[0027] The pH regulator may be included in an amount such that the pH of the digestive composition is 5 to 7.5.

[0028] Additionally, the digestive composition may further include one or more viscosity modifiers selected from the group consisting of sodium alginate, pectin, gelatin, high molecular weight polysaccharides, cellulose compounds, nonionic surfactants, bentonite, and borate.

[0029] The digestive composition according to the present invention may have a viscosity at 25±3°C in the range of 2,000 mPa·s to 10,000 mPa·s.

[0030] For example, the viscosity of the digestive composition may be in the range of 2,000 mPa·s or more and less than 5,000 mPa·s at 25±3°C, and may be in the range of 5,000 mPa·s or more and less than 9,000 mPa·s at 25±3°C.

[0031] The above digestive composition may have a solids content in the range of 10% to 90%.

[0032]

[0033] Furthermore, the present invention,

[0034] A cell assembly comprising a plurality of battery cells arranged in a first direction and a pack case in which the cell assembly is accommodated,

[0035] The above pack case provides a battery pack including a fire extinguishing unit disposed on at least one inner surface of the upper surface and side surfaces to spray the fire extinguishing composition according to the present invention described above when a thermal event occurs.

[0036] At this time, the thermal event may include one or more of a temperature rise of 100°C or more, gas venting, flame ejection, and fire occurrence.

[0037] In addition, the cell assembly may be equipped with a sensing unit including at least one detection sensor among a plurality of temperature detection sensors mounted on the cell assembly to detect the surface temperature of the cell assembly, a gas detection sensor to detect the concentration of carbon monoxide, carbon dioxide, and ethane contained in the internal air of the battery pack, and a flame detection sensor to detect whether a flame has occurred and the location where the flame has occurred.

[0038] In addition, the battery pack may further include a control unit that is electrically connected to the sensing unit and the digestion unit to obtain information detected by the detection sensor of the sensing unit when a thermal event occurs, and determines whether a thermal event has occurred and where it occurred from the obtained information, and moves the digestion unit to the corresponding occurrence location.

[0039] In addition, the extinguishing unit may include an extinguishing agent storage unit located outside the pack case and storing a extinguishing composition, a gas storage unit located outside the pack case and storing an inert gas, an injection device that receives and injects the extinguishing composition and inert gas stored in the extinguishing agent storage unit and the gas storage unit, respectively, and is capable of rotating 180° along a direction perpendicular to the first direction, and a guide unit located on the inner side of the pack case and moving the injection device along the first direction of the cell assembly.

[0040] Here, the injection device may include a slurry supply pipe that is fluidly connected to the extinguishing agent storage unit and supplies the extinguishing composition stored in the extinguishing agent storage unit, a gas supply pipe that is fluidly connected to the gas storage unit and supplies the inert gas stored in the gas storage unit, an injection body that is fluidly connected to the slurry supply pipe and the gas supply pipe and provides a space where the extinguishing composition and the inert gas supplied therefrom are mixed, and a nozzle that is connected to an end of the injection body and sprays a mixture in which the extinguishing composition and the inert gas are mixed.

[0041] The above gas supply pipe may further include a compression pump for applying pressure to the inert gas, and the nozzle may have a flow rate controlled by the pressure of the inert gas supplied from the gas supply pipe.

[0042] Furthermore, the spray body may be provided with a rotating device including a motor configured to generate a driving force for rotating in a direction perpendicular to the first direction and a gear interposed between the motor and the spray body; and a fixing device positioned between the rotating device and the guide portion to move the spray body by the guide portion.

[0043]

[0044] The fire extinguishing composition according to the present invention comprises an inorganic compound and a polyacid compound in a predetermined content ratio and controls the viscosity at room temperature to a predetermined range, thereby uniformly forming a fire extinguishing film at the point where the event occurs when a thermal event occurs in a battery pack, and thus has the characteristics of a high cooling effect for fire extinguishing and a high suffocation effect.

[0045] In addition, the battery pack including this can quickly detect the point where a thermal event has occurred and spray the fire extinguishing composition at that point, so it is easy to prevent the spread of the thermal event and has the advantage of shortening the time required to resolve the event.

[0046]

[0047] Figure 1 is a structural diagram schematically showing the structure of a battery pack and the operating principle of a digestive unit according to the present invention.

[0048] Figure 2 is a perspective view showing a digestive unit according to the present invention.

[0049] FIG. 3 is a cross-sectional view showing a cross-section of the injection device cut in the Y-axis and Z-axis directions to show the structure of the injection device of the digestive unit according to the present invention.

[0050] FIG. 4 is a cross-sectional view showing a cross-section of the injection device cut in the X-axis and Y-axis directions to show the structure of the rotating device of the digestive unit according to the present invention.

[0051]

[0052] The present invention can be modified in various ways and has many embodiments, and specific embodiments will be described in detail in the detailed description.

[0053] However, this is not intended to limit the present invention to a specific embodiment, but should be understood to include all modifications, equivalents, or substitutes included in the technical scope of the present invention.

[0054] In the present invention, it should be understood that terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0055] Additionally, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only the case where it is "directly below" the other part, but also the case where there is another part in between. Furthermore, in the present application, being placed "on" may include the case where it is placed above as well as below.

[0056] As used herein, the terms "about," "approximately," and "substantially" are used to mean a range or approximation of a numerical value or degree, taking into account inherent manufacturing and material tolerances, and are used to prevent infringers from unfairly exploiting the disclosure, which includes precise or absolute numerical values ​​provided to aid understanding of the present invention.

[0057] Also, in this specification, "D 50 " can be defined as the particle size corresponding to 50% of the volume accumulation amount in the particle size distribution curve (graph curve of particle size distribution) of each particle. The above D 50 For example, it can be measured using the laser diffraction method. The laser diffraction method can generally measure particle diameters from the submicron range to several mm, and can obtain results with high reproducibility and high resolution.

[0058] As used herein, "solids content" refers to the mass percentage of substances other than the solvent (i.e., solids) included in the fire extinguishing composition. The solids content can be obtained by first measuring the mass of the fire extinguishing composition, second measuring the mass after volatilizing the solvent included in the fire extinguishing composition, and then calculating the percentage of the second measured mass based on the first measured mass.

[0059]

[0060] Hereinafter, the present invention will be described in more detail.

[0061]

[0062] Digestive composition

[0063] The present invention,

[0064] 100 parts by weight of an inorganic compound represented by the following chemical formula 1 and 0.01 to 5 parts by weight of a polyacid are mixed in water,

[0065] Provided is a fire extinguishing composition characterized in that the viscosity at 25±3℃ is in the range of 2,000 mPa·s to 10,000 mPa·s:

[0066] [Chemical Formula 1]

[0067] M p O q (OH) r

[0068] In chemical formula 1,

[0069] M is magnesium or aluminum,

[0070] p is an integer from 1 to 10, q is an integer from 0 to 20, and p≤q,

[0071] r is an integer from 1 to 5.

[0072]

[0073] The fire extinguishing composition according to the present invention is applied to a battery pack including a lithium secondary battery as a battery cell, and may be used to extinguish a fire that has already occurred or to limit an abnormal temperature rise prior to ignition. The fire extinguishing composition may be sprayed at a point where a thermal event is expected to occur or has occurred in the battery pack, thereby forming a uniform fire extinguishing film on the surface of the point. The fire extinguishing composition can cool the surrounding heat while preventing contact with oxygen in the air during the process of forming the fire extinguishing film, and thus has excellent fire prevention and extinguishing effects.

[0074] Here, the thermal event may mean one or more of a temperature rise of 100°C or more, gas venting, flame eruption, and fire occurrence occurring inside a device including a plurality of lithium secondary battery cells.

[0075] To achieve the above-described effect, the fire extinguishing composition comprises an inorganic compound and a polyacid compound.

[0076] The above-mentioned inorganic compound, which constitutes the main component of the fire extinguishing composition, maintains a stable state even at temperatures of approximately 200 to 350°C and has the characteristic of absorbing heat from the surroundings by thermally decomposing into water and inorganic oxides at temperatures higher than the above-mentioned temperature. In this case, the thermal decomposition can lower the surrounding temperature of the inorganic compound, thereby suppressing ignition, thereby reducing the possibility of fire. Furthermore, the above-mentioned inorganic compound has the advantage of not only reducing the generation of smoke and toxic gases in the event of a fire, but also suppressing ignition even when flames or sparks are present.

[0077] Such inorganic compounds include compounds represented by the following chemical formula 1:

[0078] [Chemical Formula 1]

[0079] M p O q (OH) r

[0080] In chemical formula 1,

[0081] M is magnesium or aluminum,

[0082] p is an integer from 1 to 10, q is an integer from 0 to 20, and p≤q,

[0083] r is an integer from 1 to 5.

[0084] For example, the inorganic compound may include one or more of boehmite, pseudoboehmite, diaspore, akdalaite, aluminum trihydroxide, and magnesium hydroxide.

[0085] Conventionally, clay used in fire extinguishing compositions has excellent fire resistance in itself, but has limitations in that the fire resistance is reduced due to a chemical reaction that occurs between the components that make up the clay and the environment in which the fire extinguishing composition is placed. However, the inorganic compounds have excellent chemical resistance, and thus can achieve high fire resistance even when left in the composition state for a long time. In addition, the inorganic compounds have a relatively high amount of heat absorption in the temperature range of 200 to 300°C compared to metal oxides such as alumina, and therefore have the effect of delaying the internal temperature of the battery pack from reaching the ignition point rather than when the internal temperature rapidly increases before ignition occurs inside the battery pack.

[0086] In addition, the inorganic compound may have a predetermined particle size. The inorganic compound may have a fine average particle size so as to uniformly form a fire extinguishing film on the surface of the sprayed point after spraying the fire extinguishing composition even in a small amount. For example, the inorganic compound may have an average particle size (D 50) may be in the range of 0.01 ㎛ to 100 ㎛, specifically 0.01 ㎛ to 75 ㎛, 0.01 ㎛ to 50 ㎛, 0.01 ㎛ to 30 ㎛, 0.01 ㎛ to 20 ㎛, 0.01 ㎛ to 10 ㎛, 0.01 ㎛ to 5 ㎛, 0.01 ㎛ to 3 ㎛, 0.01 ㎛ to 2 ㎛, 0.01 ㎛ to 1 ㎛, 0.1 ㎛ to 100 ㎛, 1 ㎛ to 100 ㎛, 1 ㎛ to 20 ㎛, 1 ㎛ to 10 ㎛, 1 ㎛ to 5 ㎛, 1 ㎛ to 3 ㎛, 0.5 ㎛ to 2 ㎛, 2 ㎛ to 6 ㎛, 5 ㎛ to It may range from 20 μm, 10 μm to 20 μm, 1 μm to 9 μm or 1.5 μm to 6 μm.

[0087] The present invention relates to an average particle diameter (D) of an inorganic compound 50 ) by adjusting the above-described range, the surrounding heat can be more effectively absorbed when a thermal event occurs due to the large surface area, thereby preventing or delaying the occurrence of a fire when the temperature inside the battery pack rises rapidly. In addition, the present invention can prevent accidents caused by dust generation during the manufacture of the fire extinguishing composition due to the average particle size smaller than the lower limit of the above-described range, and can increase the dispersibility of the manufactured fire extinguishing composition. Furthermore, the present invention can prevent the heat absorption performance of the inorganic compound from being lowered in advance due to the average particle size larger than the upper limit of the above-described range, while preventing the state stability from being reduced during long-term storage.

[0088] The above polyfunctional compound acts as a chelating agent for the inorganic compound included in the fire extinguishing composition, thereby helping to form a uniform fire extinguishing film without agglomerating on the surface where the inorganic compound is sprayed after spraying the fire extinguishing composition.

[0089] For this purpose, the polyhydric acid compound may include a compound containing two or more carboxyl groups (-COOH), and specifically, malonic acid, citric acid, malic acid, oxalic acid, glutamic acid, aspartic acid, amino acid, fatty acid, methane tricarboxylic acid, ethane tricarboxylic acid, benzene-1,3,5-tricarboxylic acid, 5-sulfo-1,2,4-benzenetricarboxylic acid, ethane-1,1,2,2-tetracarboxylic acid, It may include at least one of propane-1,1,2,3-tetracarboxylic acid, butane-1,2,3,4-tetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid, benzene-1,2,4,5-tetracarboxylic acid, benzene-1,2,3,4,5-pentacarboxylic acid, and benzene-1,2,3,4,5,6-hexacarboxylic acid (mellitic acid).

[0090] For example, the polyacid compound may include citric acid, malic acid, and / or malonic acid.

[0091] Additionally, the above-mentioned inorganic compound and polyacid compound may be included in the fire extinguishing composition in a predetermined content ratio to increase fire resistance. Specifically, the fire extinguishing composition may contain 0.01 to 5 parts by weight of the polyacid compound when it contains 100 parts by weight of the inorganic compound, and more specifically, may contain 0.01 to 4 parts by weight, 0.01 to 3 parts by weight, 0.01 to 2 parts by weight, 0.01 to 1 part by weight, 0.05 to 5 parts by weight, 0.1 to 5 parts by weight, 0.5 to 5 parts by weight, 1 to 5 parts by weight, 2 to 5 parts by weight, 3 to 5 parts by weight, 4 to 5 parts by weight, 1 to 4 parts by weight, 1 to 3 parts by weight, 2 to 4 parts by weight, or 1.5 to 3 parts by weight of the polyacid compound.

[0092] In addition, the fire extinguishing composition may have a slurry form in which the inorganic compound and the polyacid compound are mixed in a solvent, wherein the solvent may be water (H2O). The water can not only function as a solvent for mixing with various flame retardants, but can also absorb a significant amount of ambient heat when vaporized into water vapor. In addition, since the volume of the water increases by about 1,600 times when vaporized, it can rapidly reduce the oxygen concentration at the point where a fire has occurred, which has an excellent suffocating effect. In addition, insulating oils such as silicone oils used as solvents in conventional fire extinguishing compositions are often flammable, and if they are non-flammable, they are expensive, which poses a problem of low economic efficiency. In contrast, water has the advantage of being not only non-flammable but also excellent economic efficiency.

[0093] Meanwhile, the point in time when the fire extinguishing composition is sprayed is immediately before or after a rapid temperature rise and gas venting of the battery cell. In this case, water contained in the sprayed fire extinguishing composition may penetrate into the inside of the battery cell. Water that penetrates into the inside of the battery cell easily reacts with the electrolyte again and accelerates the generation of gases such as hydrogen fluoride (i.e., hydrofluoric acid) that are harmful to the human body, so there is a high possibility that it will lead to a fire that emits higher heat than a general fire, and there is a limitation that it is difficult to respond to the fire that has occurred. Therefore, the fire extinguishing composition according to the present invention is a mixture of an inorganic compound and a polyacid compound with water, and the solid content can be adjusted to satisfy a predetermined range. Specifically, the extinguishing composition may have a solids content in the range of 10% to 90%, specifically 10% to 90%, 15% to 90%, 20% to 90%, 25% to 90%, 30% to 90%, 35% to 90%, 40% to 90%, 45% to 90%, 50% to 90%, 55% to 90%, 60% to 90%, 65% to 90%, 70% to 90%, 75% to 90%, 10% to 50%, 10% to 40%, 25% to 50%, 30% to 80%, 40% to 70%, 51% to 90%, 51% to 80%, 51% to It may have a solids content in the range of 70%, 55% to 75%, 45% to 60% or 51% to 65%.

[0094] The present invention can easily mix an inorganic compound and a polyacid compound by adjusting the solid content of the fire extinguishing composition to the above range while appropriately lowering the water content in the fire extinguishing composition. In addition, when a mixture of an inorganic compound and a polyacid compound is sprayed in a powder state, it is difficult to form a fire extinguishing film on the surface of the point where the fire extinguishing composition is dispersed. However, the fire extinguishing composition of the present invention has a slurry form in which an inorganic compound and a polyacid compound are mixed with water, so that after the surface of the point where the fire extinguishing composition is sprayed is coated, the water vaporizes, thereby uniformly forming a fire extinguishing film. Since the fire extinguishing film vaporizes a small amount of water during the formation process, it not only exhibits the effect of cooling the point where the fire extinguishing composition is sprayed and its surroundings without additional reaction with the battery cell, but also can effectively prevent oxygen in the internal air from being supplied to the point where a thermal event occurs after the film is formed.

[0095] In the case of a slurry having a high solid content, the viscosity is high, and in this case, not only is it difficult to spray the fire extinguishing composition, but the sprayed fire extinguishing composition is sprayed in a lumpy state and cannot form a coating layer, so it is difficult to form a fire extinguishing film even if the water in the composition vaporizes. Therefore, the fire extinguishing composition according to the present invention can satisfy a predetermined viscosity at room temperature for forming a coating layer and converting into a fire extinguishing film after spraying. Specifically, the fire extinguishing composition may have a viscosity at 25±3°C in the range of 2,000 mPa·s to 10,000 mPa·s. For example, the fire extinguishing composition may have a viscosity at 25±3°C of 2,000 mPa·s to 8,000 mPa·s; 2,000 mPa·s to 6,000 mPa·s; 2,000 mPa·s to 4,000 mPa·s; 2,000 mPa·s to 5,000 mPa·s; 2,500 mPa·s to 5,000 mPa·s; 3,000 mPa·s to 4,500 mPa·s; 4,000 mPa·s to 5,000 mPa·s; 4,000 mPa·s to 6,000 mPa·s; 4,000 mPa·s to 8,000 mPa·s; 5,000 mPa·s to 9,000 mPa·s; 5,100 mPa·s to 9,000 mPa·s; 6,000 mPa·s to 8,000 mPa·s; 7,000 mPa·s to 9,900 mPa·s; 2,500 mPa·s to 3,500 mPa·s; 2,000 mPa·s or more but less than 5,000 mPa·s; Or it may be in the range of 5,000 mPa·s or more and less than 9,000 mPa·s.

[0096] The present invention enables the fire extinguishing composition to be sprayed in a slurry state with a high solids content without clogging the spraying device when a thermal event occurs within a battery pack by ensuring that the room temperature viscosity of the fire extinguishing composition is within the aforementioned range. Furthermore, the sprayed fire extinguishing composition can form a uniform coating layer, and the time required for the water contained in the fire extinguishing composition to vaporize is short, thereby shortening the fire extinguishing response time.

[0097] The above-mentioned digestion composition may further include a separate viscosity modifier to adjust the viscosity at room temperature to the above-mentioned range. The viscosity modifier may further include one or more viscosity modifiers selected from the group consisting of sodium alginate, pectin, gelatin, high molecular weight polysaccharides, cellulose compounds, nonionic surfactants, bentonite, and borate.

[0098] The above-described fire extinguishing composition may further include a pH regulator to have a pH close to neutrality. The fire extinguishing composition itself has a weakly acidic pH range of 3 to 4, as it contains a polyacid compound together with an inorganic compound. However, if the fire extinguishing composition has a weakly acidic pH, when applied to a battery pack, not only will it cause corrosion of the equipment in which the fire extinguishing composition is stored and supplied, but the corrosion will also cause a problem in that the performance of the fire extinguishing composition is reduced. Therefore, the composition may further include a pH regulator to have a pH close to neutrality, specifically, a pH range of 5 to 7.5, 5 to 6.5, 5.5 to 7, 6 to 7.5, or 6.5 to 7.5.

[0099] The above pH adjusting agent may further include at least one pH adjusting agent selected from the group consisting of sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, ammonium carbonate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, ammonium chloride, ammonium molybdate, ammonium bromate, ammonium acetate, ammonium nitrate, and ammonium sulfate.

[0100] For example, the pH adjusting agent may include ammonium phosphate, and among them, may include first ammonium phosphate (NH4H2PO4).

[0101] The above pH adjusting agent can neutralize the fire extinguishing composition, while simultaneously absorbing and cooling the surrounding heat generated during thermal decomposition, and generating a non-combustible gas to achieve a suffocating effect. In particular, the first ammonium phosphate is unstable to heat and begins thermal decomposition at about 150°C, and can undergo an endothermic process through thermal decomposition stepwise at about 190±10°C, about 215±10°C, about 300±10°C, and about 250±10°C through the following reaction. Therefore, the first ammonium phosphate can not only neutralize the fire extinguishing composition, but also absorb a large amount of heat during thermal decomposition, which is advantageous in the fire extinguishing process:

[0102] [Reaction Formula 1]

[0103] NH4H2PO4→ H3PO4+ NH3

[0104] [Reaction Formula 2]

[0105] 2H3PO4→ H4P2O7+ H2O

[0106] [Reaction Formula 3]

[0107] H4P2O7→ 2HPO3+ H2O

[0108] [Reaction Formula 4]

[0109] 2HPO3→ P2O5+ H2O.

[0110]

[0111] The fire extinguishing composition according to the present invention, having the above-described composition, can uniformly form a fire extinguishing film at the point where a thermal event occurs within a battery pack within a short period of time, thereby realizing cooling effects, suffocation effects, etc. Therefore, the fire extinguishing composition can prevent the spread of fire and has an excellent fire extinguishing effect. Furthermore, since the fire extinguishing composition has a slurry form in which an inorganic compound and a polyacid compound are dispersed in water, it is not only environmentally friendly but also economically advantageous.

[0112]

[0113] battery pack

[0114] Furthermore, the present invention,

[0115] A battery pack comprising the above-described digestive composition is provided.

[0116] Specifically, the battery pack includes a cell assembly including a plurality of battery cells arranged in a first direction and a pack case in which the cell assembly is accommodated, and the pack case includes a fire extinguishing unit disposed on at least one inner surface of an upper surface and a side surface to spray the fire extinguishing composition of the present invention described above when a thermal event occurs.

[0117] The above battery pack includes a fire extinguishing unit that sprays the fire extinguishing composition described above on the inner side of the pack case where the cell assembly is accommodated, and has an excellent effect of extinguishing a thermal event such as a flame eruption or fire while preventing it from spreading when it occurs inside.

[0118] Furthermore, rather than spraying the fire extinguishing composition throughout the battery pack when a thermal event occurs, the fire extinguishing unit can quickly move to the point where the thermal event occurred and directly spray the fire extinguishing composition concentrated on that point. This allows the battery pack to respond more quickly to a thermal event, thereby offering the advantage of superior safety.

[0119] Here, the thermal event means that the temperature inside the battery pack rapidly and abnormally rises to 100℃ or higher, 150℃ or higher, 200℃ or higher, or 250℃ or higher, or that gas venting, flames, fire, etc. occur inside the battery pack. Once the thermal event occurs, one or more of the above-described phenomena occur simultaneously or in a chain reaction.

[0120] Fig. 1 is a structural diagram schematically illustrating the structure of a battery pack and the operating principle of a digestive unit according to the present invention. Hereinafter, a battery pack (1) according to the present invention will be described with reference to Fig. 1.

[0121] The above battery pack (1) includes a cell assembly (10) including a plurality of battery cells arranged in a first direction (a direction parallel to the X-axis) and a pack case (50) in which the cell assembly is accommodated. At this time, the battery cells included in the cell assembly (10) may be pouch-shaped battery cells, square battery cells, cylindrical battery cells, etc., and may preferably be pouch-shaped battery cells. In this case, the cell assembly (10) may have a form in which a plurality of pouch-shaped battery cells are arranged in the thickness direction of the battery cells.

[0122] In addition, the cell assembly (10) may mean a cell stack in which a plurality of battery cells are fixed by a frame structure, and in some cases, may mean a battery module including a plurality of battery cells.

[0123] Additionally, the battery pack may have a predetermined separation distance between the cell assembly (10) and the pack case (50) so that the extinguishing unit can move to the point where the thermal event occurs when a thermal event occurs. For example, the cell assembly (10) and the pack case (50) may have a separation distance between them in the range of 5 to 20 cm, 5 to 15 cm, 5 to 10 cm, 10 to 20 cm, or 15 to 20 cm.

[0124] In addition, the battery pack (1) may include a means for moving the extinguishing unit to the corresponding point when a thermal event occurs.

[0125] For example, in order to detect the point where a thermal event occurs, a sensing unit (30) that detects changes in temperature, changes in the concentration of internal air components, and whether a flame occurs when a thermal event occurs may be provided in the cell assembly (10).

[0126] Specifically, the cell assembly (10) may be equipped with one or more detection sensors (31) among a plurality of temperature detection sensors that detect the surface temperature of the cell assembly (10), a gas detection sensor that detects the concentration of venting gas contained in the internal air of the battery pack (1), and a flame detection sensor that detects whether a flame has occurred and the location where the flame has occurred.

[0127] The above temperature detection sensor is mounted on the surface of the cell assembly and can measure the surface temperature of the cell assembly in real time. At this time, the temperature detection sensor may be mounted in multiple numbers on the surface of the cell assembly along the first direction at a predetermined distance apart, or may be individually mounted on each of the multiple battery cells constituting the cell assembly.

[0128] In addition, the gas detection sensor can measure the components and concentration of the internal air that change according to gas venting of the battery cell. Gas venting of the battery cell means that the internal temperature of the battery cell rises due to electrical, thermal, and physical external stresses on the battery cell, and the resulting gas is discharged to the outside of the battery cell by vaporizing or decomposing the electrolyte. At this time, the discharged gas includes hydrocarbon gases such as methane and ethane, and carbon oxide gases such as carbon monoxide (CO) and carbon dioxide (CO2). Therefore, the gas detection sensor can measure the concentration of hydrocarbon gases and carbon oxide gases, which are venting gases, among the air components inside the battery pack.

[0129] In addition, the flame detection sensor is equipped with an infrared LED and can detect whether a flame has occurred by measuring an infrared wavelength (110 to 760 nm) derived from the flame when the flame is emitted and / or a fire occurs.

[0130] The above gas detection sensor and the gas detection sensor may be mounted in plurality on the surface of the cell assembly or on the inner surface of the pack case (50) adjacent to the cell assembly (10) along the first direction at a predetermined distance apart from each other.

[0131] In addition, the cell assembly (10) may include a control unit (40) that is electrically connected to the sensing unit to receive measured or detected results and determines whether a thermal event has occurred from the received results.

[0132] For example, if the detection sensor (31) is a temperature detection sensor, the control unit (40) can obtain surface temperature information of the cell assembly (10) measured by a plurality of temperature detection sensors. Thereafter, based on the obtained temperature information, the temperature change per second is calculated, and if the calculated temperature change amount is +5°C or more (i.e., a temperature increase of 5°C or more), it can be determined that a rapid temperature increase of 100°C or more has occurred at the location of the temperature detection sensor that provided the temperature information.

[0133] When the above detection sensor (31) is a gas detection sensor, the control unit (40) obtains information on the air components and concentrations inside the cell assembly (10) measured by a plurality of gas detection sensors, and based on the obtained information, if the concentration change of the venting gas, hydrocarbon gas and carbon oxide gas, is 50 to 1,000 ppm per second, it can be determined that gas venting has occurred.

[0134] If the above detection sensor (31) is a flame detection sensor, the control unit (40) obtains infrared detection information measured by a plurality of flame detection sensors, and determines whether infrared is detected based on the obtained infrared detection information, and determines that infrared is detected and that flames have erupted and / or a fire has occurred.

[0135] If the control unit (40) determines that a thermal event has occurred based on information obtained from the sensing unit (30), it can determine that the thermal event has occurred at the location of the detection sensor (31) that transmitted the corresponding information among the plurality of detection sensors (31). The location of occurrence of the thermal event is determined, and the control unit (40) can move the electrically connected fire extinguishing unit (20) to the corresponding location to spray the fire extinguishing composition.

[0136] The above control unit (40) can also function as a BMS (battery management system) that controls charging and discharging of the battery pack (10). In addition, the control unit (40) can be placed on one side of the cell assembly (10), and in some cases, can be placed inside the pack case (50).

[0137] Here, the digestion unit (20) may include a means for moving to a point where a thermal event occurs and a means for spraying a digestion composition in the form of a slurry that satisfies a predetermined viscosity at room temperature.

[0138] FIGS. 2 to 4 are drawings showing the structure of a fire extinguishing unit and a spraying device and a rotating device included in the fire extinguishing unit. Referring to FIGS. 2 to 4, the fire extinguishing unit (20) may include: a fire extinguishing agent storage unit (not shown) located outside the pack case (50) and storing a fire extinguishing composition; a gas storage unit (not shown) located outside the pack case (50) and storing an inert gas; a spraying device (21) supplied with and spraying the fire extinguishing composition and inert gas stored in the fire extinguishing agent storage unit and the gas storage unit, respectively, and capable of rotating 180° along a direction perpendicular to the first direction; and a guide unit (22) located on the inner surface of the pack case (50) and moving the spraying device (21) along the first direction of the cell assembly (10).

[0139] The above-mentioned digestion unit (20) includes a spray device (21) for spraying a slurry-type extinguishing composition, and the spray device (21) may have a structure for spraying the extinguishing composition in a form mixed with an inert gas.

[0140] The above-mentioned fire extinguishing composition is maintained in a filled state in ① the fire extinguishing agent storage section where the fire extinguishing composition is stored, ② the fire extinguishing unit (20) mounted inside the pack case (50), and ③ the pipe section connecting the fire extinguishing agent storage section and the fire extinguishing unit (20) during normal operation of the battery pack (1). However, when a sudden thermal event occurs, the filled fire extinguishing composition is sprayed to the point where the thermal event occurred through the spraying device (21). At this time, since the fire extinguishing composition to be dispersed has been filled in the fire extinguishing agent storage section and / or the pipe section for a long time, the dispersibility of each component may be reduced, resulting in separation of the solute and the solvent. In this case, the sprayed fire extinguishing composition cannot form a uniform fire extinguishing film, so the fire extinguishing performance is significantly reduced.

[0141] Accordingly, the fire extinguishing unit (20) according to the present invention includes a fire extinguishing agent storage unit in which a fire extinguishing composition is stored and a gas storage unit in which an inert gas is stored outside the pack case (50), and includes an injection device (21) having a structure in which the fire extinguishing composition supplied from each storage unit and the inert gas are mixed, thereby preventing the dispersibility of the fire extinguishing composition from being reduced.

[0142] Specifically, as shown in FIGS. 2 and 3, the injection device (21) may include a slurry supply pipe (211) that is fluidly connected to the extinguishing agent storage and supplies the extinguishing composition stored in the extinguishing agent storage, a gas supply pipe (212) that is fluidly connected to the gas storage and supplies the inert gas stored in the gas storage, an injection body (213) that is fluidly connected to the slurry supply pipe (211) and the gas supply pipe (212) to provide a space (213') in which the extinguishing composition and the inert gas supplied therefrom are mixed, and a nozzle (214) that is connected to an end of the injection body (213) and sprays a mixture in which the extinguishing composition and the inert gas are mixed.

[0143] The above-mentioned injection device (21) has a structure in which the extinguishing composition and the inert gas supplied through the slurry supply pipe (211) and the gas supply pipe (212) are mixed in the injection body immediately before spraying the extinguishing composition, and then sprayed through the nozzle (214). Through this, the extinguishing composition mixed with the inert gas in the injection body can have improved dispersibility of inorganic compounds and polyacid compounds.

[0144] In addition, the gas supply pipe (212) may further include a compression pump (not shown) that applies pressure to the inert gas, thereby controlling the pressure (or flow rate) of the inert gas supplied to the spray body (213). The pressure (or flow rate) of the inert gas supplied to the spray body (213) may affect the spray pressure (or flow rate) of the fire extinguishing composition sprayed from the nozzle (214). When the viscosity of the fire extinguishing composition according to the present invention is greater than that of water, the spray angle may become narrower and the spray distance may become shorter compared to when the viscosity is low. When the spray angle of the fire extinguishing composition becomes narrower and the spray distance becomes shorter, it may become difficult to control the location where the fire extinguishing composition is distributed, and a larger amount of the fire extinguishing composition is used to form a uniform fire extinguishing film at the point where the thermal event occurs. However, the present invention can control the flow rate of the fire extinguishing composition sprayed from the nozzle by controlling the pressure of the inert gas mixed with the fire extinguishing composition by separately including a compression pump in the gas supply pipe (212), thereby facilitating control of the location at which the fire extinguishing composition is sprayed. Accordingly, the present invention can form a uniform coating layer at the location where a thermal event occurs even when using a small amount of the fire extinguishing composition in slurry form.

[0145] Furthermore, the spray body (213) may include a rotating device (215) that rotates the spray body (213) so that the fire extinguishing composition can be intensively sprayed to the point where a thermal event occurs.

[0146] The above-described digestion unit (20) includes a guide unit (22) positioned on the inner surface of the pack case (50) to move the injection device (21). However, since the guide unit (22) moves only along the first direction (parallel to the X-axis) of the cell assembly (10), it is difficult for the injection device (21) to move in a direction perpendicular to the first direction (i.e., parallel to the Y-axis or Z-axis direction). Accordingly, the injection body (213) of the injection device (21) may include a rotation device (215) that rotates about a rotation axis substantially parallel to the first direction. Accordingly, the rotation device (215) can rotate in a direction perpendicular to the first direction of the cell assembly (10). Here, the direction perpendicular to the first direction of the cell assembly (10) may mean i) a second direction perpendicular to the first direction of the cell assembly (10) when the rotation device (215) is disposed on the inner surface of the pack case (50) (i.e., a direction parallel to the Z-axis direction), or ii) a third direction perpendicular to the first direction of the cell assembly (10) when the rotation device (215) is disposed on the inner upper surface of the pack case (50) (i.e., a direction parallel to the Y-axis direction). The rotation device (215) can directly rotate the spray body (213) so that the nozzle (214) of the spray device (21) where the fire extinguishing composition is dispersed faces the point where the thermal event occurs, thereby intensively spraying the fire extinguishing composition at the point where the thermal event occurs.

[0147] At this time, the rotating device (215) can be rotated 180° in a direction perpendicular to the first direction. Accordingly, the rotating device (215) can easily spray the fire extinguishing composition from one end to the other end in a direction perpendicular to the first direction with respect to the cell assembly (10) by rotating the spraying device (21) 180°.

[0148] The above-described rotating device (215) may include a motor (215-1) that provides rotational power to rotate the spray device (21) and a gear (215-2) that induces rotation according to the rotational power of the motor. Specifically, as shown in FIG. 4, the spray body (213) may be rotated by including a motor (215-1), a first gear (215-2a), a shaft (215-3), and a second gear (215-2b). The orientation of the spray body (213) may be controlled by the motor (215-1), the first gear (215-2a), the shaft (215-3), and the second gear (215-2b). In addition, the orientation of the spray body (213) may be controlled by receiving position information determined from detection information measured by the sensing unit (30) from the control unit (40). Accordingly, the injection device (21) can intensively inject the extinguishing composition at the point where the thermal event occurred (or an adjacent point), thereby enabling a quick response to the thermal event.

[0149] The above motor (215-1) may be configured to generate driving force for rotation of the nozzle (214). The above motor (215-1) may be a precision control motor, such as a servo motor or a step motor.

[0150] In addition, the first gear (215-2a) may be interposed between the motor (215-1) and the nozzle (214). The second gear (215-2b) may be interposed between the first gear (215-2a) and the nozzle (214). For example, each of the first gear (215-2a) and the second gear (215-2b) may be either a helical gear or a spur gear. The first gear (215-2a) and the second gear (215-2b) may be connected by, for example, a shaft (215-3), but is not limited thereto. The shaft (215-3) may be omitted, and the first gear (215-2a) and the second gear (215-2b) may be in direct contact. The driving force generated by the motor (215-1) can be transmitted to the nozzle (214) via the first gear (215-2a), the shaft (215-3) and the second gear (215-2b), and the nozzle (214) can be rotated by the driving force.

[0151] Furthermore, the digestion unit (20) includes a guide unit (22) to move along the extension direction of the space, i.e., the first direction, within the space formed between the cell assembly (10) and the pack case (50) in order to move the injection device (21) to the point where the thermal event occurred (or an adjacent point).

[0152] The above guide portion (22) can be formed directly on the inner surface of at least one of the upper surface and the side surface of the pack case (50). When the guide portion (22) is formed directly on the inner surface of the pack case (50), no additional space is required for forming the guide portion (22), and the guide portion (22) can be formed during the manufacturing of the pack case (50), thereby improving the energy density and manufacturing processability of the battery pack (1).

[0153] The above guide portion (22) may be provided as a groove, a protrusion, or a slit formed on the inner surface of the pack case (50). For example, the above guide portion (22) may be a groove, a protrusion, or a slit that has a shape that extends long along the extension direction of the pack case (50) (in the direction parallel to the X-axis) on the inner surface of the pack case (50).

[0154] Meanwhile, the spray body (213) of the spray device (21) may be provided with a fixing device (216) for fixing to the guide part (22) through a rotating device (215). The fixing device (216) may be provided on an outer portion of the rotating device (215) included in the spray body (213), and may have a complementary structure corresponding to the guide part (22) so as to be fastened to the guide part (22) in the form of a groove, a protrusion, or a slit. The fixing device (216) may be configured so that a portion fastened to the guide part (22) moves along the extension direction without leaving the guide part (22).

[0155] Furthermore, the digestion unit (20) may include a driving unit (not shown). The driving unit may be configured to provide power to the injection device (21). The driving unit may be coupled to the injection device (21). The driving unit may include, for example, a motor and a roller driven by the motor. In this case, the roller may be in contact with the guide unit (22) and operate according to the rotation of the motor, thereby allowing the injection device (21) to move along the extension direction of the guide unit (22).

[0156] In addition, the extinguishing unit (20) may be configured to be driven by power supplied from the battery pack (50) itself. That is, the battery pack (1) of the present invention may be configured to receive power required for the operation of the driving unit and / or the operation of the spraying device (21) (spraying operation of the extinguishing composition) from some of the battery cells of the cell assembly included in the battery pack (1) itself, without being supplied through a separate power device. In this case, since there is no need to apply a separate battery for driving the extinguishing unit (20), the structure of the battery pack (1) may be simplified.

[0157] Although not specifically illustrated in the drawing, the battery pack (1) of the present invention may be configured so that the extinguishing unit (20) receives power necessary for operation from battery cells of the cell assembly (10) included in the battery pack (1) in which a thermal event has not occurred. For example, the driving unit provided in the extinguishing unit (20) may be individually electrically connected to a plurality of battery cells included in the cell assembly (10). Switches may be individually provided on the power supply line connecting the driving unit and each battery cell. Each of the switches may be connected to the control unit (40) of the present invention. The control unit (40) may be configured to control, for example, a switch installed on a power supply line connecting the driving unit and the battery cell located farthest from the battery cell in which a thermal event has occurred to be turned on, and to control the switches connecting the remaining battery cells and the driving unit to be turned off.

[0158] Furthermore, the extinguishing unit (20) may include a pipe configured to be connected to the injection device (21) and supply a extinguishing composition and / or an inert gas to the injection device (21). The pipe may include a slurry supply pipe (211) for supplying the extinguishing composition stored in the extinguishing agent storage unit to the injection body (213) and a gas supply pipe (212) for supplying the inert gas stored in the gas storage unit to the injection body (213). The pipe may extend along a first direction (a direction parallel to the X-axis) and be drawn out of the battery pack (1). When the extension direction of the pipe extends along a direction parallel to the extension direction of the guide unit (22) in this way, the phenomenon in which the pipe interferes with other components inside the battery pack (1) according to the movement of the extinguishing unit (20) can be minimized.

[0159] In addition, the above-mentioned pipe section may be made of a material capable of changing shape in order to minimize the restrictions that occur in the movement of the digestive section (20), and may be wound on a reel so that its length can be adjusted during normal operation of the battery pack (1).

[0160]

[0161] The battery pack according to the present invention has the above-described configuration, so that it can quickly detect the point where a thermal event has occurred and directly and intensively spray the fire extinguishing composition at that point, thereby facilitating the prevention of the spread of the thermal event and shortening the time required to resolve the event.

[0162]

[0163] Hereinafter, the present invention will be described in more detail through examples and experimental examples.

[0164] However, the following examples and experimental examples are only illustrative of the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

[0165]

[0166] Examples 1 to 7 and Comparative Examples 1 to 5. Preparation of digestive compositions

[0167] Aluminum hydroxide (Al(OH)3), magnesium hydroxide (Mg(OH)2) and alumina (Al2O3) were prepared as inorganic compounds, and citric acid was prepared as a polyacid compound. At this time, the inorganic compounds had an average particle diameter (D 50 ) was used with a particle size of about 1 to 5 μm. In addition, ammonium phosphate (NH4H2PO4) was prepared as a pH adjuster. The polyacid compound based on 100 parts by weight of the prepared inorganic compound was weighed and mixed in the content shown in Table 1 below, and water was added to the mixture. Then, the mixture with water added was stirred at 500±50 rpm for 10 minutes, and a pH adjuster was added so that the pH of the mixture became 7.0±0.3, and sodium alginate was used as a viscosity adjuster to adjust the room temperature viscosity as shown in Table 1. Thereafter, stirring was performed at the same stirring speed for 10 to 20 minutes to prepare a fire extinguishing composition for a battery pack. At this time, the solid content of each of the prepared fire extinguishing compositions was measured. The results are shown in Table 1.

[0168] Inorganic compound type Polyvalent compound content Solid content Room temperature viscosity [mPa·s] Example 1 Al(OH) 30.5 parts by weight 60%~70% About 3,500~4,000 Example 2 Al(OH) 32 parts by weight 60%~70% About 3,500~4,000 Example 3 Mg(OH) 22 parts by weight 60%~70% About 3,500~4,000 Example 4 Al(OH) 3 : Mg(OH) 2 = 1:1 (wt. / wt.) 2 parts by weight 60%~70% About 3,500~4,000 Example 5 Al(OH) 32 parts by weight 1%~5% About 3,500~4,000 Example 6 Al(OH) 32 parts by weight 95%~98% About 3,500~4,000 Example 7Al(OH)32 weight part 60%~70% approx. 6,500~7,000 Comparative example 1Al(OH)30.005 weight part 60%~70% approx. 3,500~4,000 Comparative example 2Al(OH)36 weight part 60%~70% approx. 3,500~4,000 Comparative example 3Al(OH)32 weight part 60%~70% approx. 500~600 Comparative example 4Al(OH)32 weight part 60%~70% approx. 11,000~11,500 Comparative example 5Al2O32 weight part 60%~70% approx. 3,500~4,000

[0169]

[0170] Experimental example.

[0171] In order to evaluate the extinguishing performance of the extinguishing compositions manufactured in the examples and comparative examples, the following experiments were performed.

[0172] Specifically, to simulate a battery pack in which a thermal event occurred, a chamber corresponding to the battery pack case was prepared. At this time, the chamber was equipped with a fire extinguishing agent tank, in which a fire extinguishing agent composition was stored, and a nozzle for spraying the fire extinguishing agent was connected via a pipe to the inner upper surface of the chamber.

[0173] In addition, 10 1Ah-class secondary battery cells were prepared, and each of the prepared secondary battery cells was charged so that the SOC of each secondary battery cell became 100%. The 10 prepared secondary battery cells were assembled into a cartridge-type cell assembly, and then each secondary battery cell was mounted in the chamber so that it was stacked. At this time, the cell assembly was designed so that aluminum plates having a predetermined thickness were bolted to the upper and lower portions of each secondary battery cell, assuming a pressurized structure of the secondary battery cells within the assembly, and each secondary battery cell was pressurized by the joined aluminum plates. In addition, an aluminum cooling plate was separately interposed between the upper and lower aluminum plates and the secondary battery cells, and between the stacked secondary battery cells. A heating pad (Silicone heater, SBH2012, manufactured by Hotko Co., Ltd.) was installed between the lowermost secondary battery cell and the aluminum plate, and the heating pad was heated to induce thermal runaway by heating the secondary battery cell at a heating rate of 7°C / min. When the secondary battery cell ignited due to the thermal runaway, an extinguishing composition (100-150 g) was sprayed for 5 seconds through a nozzle provided on the inner upper surface of the chamber.

[0174] ① The time required for the secondary battery cell to be extinguished immediately after the above-mentioned fire extinguishing composition was sprayed was measured. In addition, ② when the temperature inside the chamber cooled to room temperature, the mounted cell assembly was removed and the shape of the fire extinguishing composition remaining in the area where the fire extinguishing composition was sprayed was visually evaluated.

[0175] At this time, the visual evaluation was evaluated as ○, △, or X based on the criteria shown below.

[0176] - ○: When the remaining digestive composition forms a uniform digestive film.

[0177] - △: If the remaining digestive composition forms a digestive film, but the formed digestive film is not uniform, or if a lump of digestive composition exists in addition to the digestive film.

[0178] - X: When the remaining digestive composition does not form a digestive film and has a lumpy and / or point-dispersed form.

[0179] The measured and evaluated results are shown in Table 2 below.

[0180] Digestion time Residual extinguishing composition form Example 1202 seconds ○ Example 2195 seconds ○ Example 3188 seconds ○ Example 4163 seconds ○ Example 5683 seconds X Example 6577 seconds X Example 7185 seconds ○ Comparative example 1435 seconds X Comparative example 2369 seconds △ Comparative example 3428 seconds X Comparative example 4451 seconds X Comparative example 5399 seconds X

[0181]

[0182] As shown in Table 2 above, it can be seen that the fire extinguishing composition according to the present invention is excellent in extinguishing a fire occurring within a battery pack.

[0183] Specifically, the fire extinguishing compositions of Examples 1 to 4 and Example 7 were confirmed to uniformly form a fire extinguishing film on the surface of the point where ignition occurred after spraying, and thus were shown to have a remarkably short fire extinguishing time of less than 210 seconds.

[0184] From these results, it can be seen that the fire extinguishing composition according to the present invention contains an inorganic compound and a polyacid compound in a predetermined content ratio and controls the viscosity at room temperature to a predetermined range, thereby uniformly forming a fire extinguishing film at the point where the event occurs when a thermal event occurs in the battery pack, and thus has a high cooling effect and suffocation effect for fire extinguishing.

[0185]

[0186] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art or having ordinary knowledge in the art that the present invention can be variously modified and changed within a scope that does not depart from the technical scope of the present invention as set forth in the claims to be described below.

[0187] Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the patent claims.

[0188]

[0189] [Explanation of symbols]

[0190] 1: Battery pack

[0191] 10: Cell assembly

[0192] 20: Digestive unit 21: Injection device

[0193] 22: Guide Department

[0194] 30: Sensing unit 31: Detection sensor

[0195] 40: Control unit 50: Pack case

[0196] 211: Slurry supply pipe 212: Gas supply pipe

[0197] 213: Injector body

[0198] 213': Space where the extinguishing composition and inert gas are mixed

[0199] 214: Nozzle

[0200] 215: Rotating device

[0201] 215-1: Motor 215-2: Gear

[0202] 215-2a: 1st gear 215-2b: 2nd gear

[0203] 215-3: Shaft

[0204] 216: Fixture

[0205] S: Spacing between cell assembly and pack case

[0206] M: Inside the battery pack

[0207] dx: X-axis direction

[0208] Rz: Z-axis rotation

Claims

1. 100 parts by weight of an inorganic compound represented by the following chemical formula 1 and 0.01 to 5 parts by weight of a polyacid compound are mixed in water, A fire extinguishing composition characterized by a viscosity at 25±3℃ of 2,000 mPa·s to 10,000 mPa·s: [Chemical Formula 1] M p O q (OH) r In chemical formula 1, M is magnesium or aluminum, p is an integer from 1 to 10, q is an integer from 0 to 20, and p≤q, r is an integer from 1 to 5.

2. In paragraph 1, A fire extinguishing composition having a viscosity of 2,000 mPa·s or more and less than 5,000 mPa·s at 25±3℃.

3. In paragraph 1, A fire extinguishing composition having a viscosity of 5,000 mPa·s or more and less than 9,000 mPa·s at 25±3℃.

4. In paragraph 1, The above-mentioned fire extinguishing composition is characterized in that the solid content is in the range of 10% to 90%.

5. In paragraph 1, A fire extinguishing composition comprising at least one of the inorganic compounds represented by the above chemical formula 1, boehmite, pseudoboehmite, diaspore, akdalaite, aluminum trihydroxide, and magnesium hydroxide.

6. In paragraph 1, A fire extinguishing composition comprising at least one of the above polycarboxylic compounds: malonic acid, citric acid, malic acid, oxalic acid, glutamic acid, aspartic acid, amino acids, fatty acids, methanetricarboxylic acid, ethanetricarboxylic acid, benzene-1,3,5-tricarboxylic acid, 5-sulfo-1,2,4-benzenetricarboxylic acid, ethane-1,1,2,2-tetracarboxylic acid, propane-1,1,2,3-tetracarboxylic acid, butane-1,2,3,4-tetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid, benzene-1,2,4,5-tetracarboxylic acid, benzene-1,2,3,4,5-pentacarboxylic acid, and benzene-1,2,3,4,5,6-hexacarboxylic acid.

7. In paragraph 1, The above fire extinguishing composition further comprises at least one pH adjusting agent selected from the group consisting of sodium bicarbonate, potassium bicarbonate, sodium carbonate, potassium carbonate, ammonium carbonate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate, ammonium chloride, ammonium molybdate, ammonium bromate, ammonium acetate, ammonium nitrate, and ammonium sulfate.

8. In paragraph 7, A digestive composition in which the pH regulator is included in an amount such that the pH of the digestive composition is 5 to 7.

5.

9. In paragraph 1, The above digestive composition further comprises at least one viscosity modifier selected from the group consisting of sodium alginate, pectin, gelatin, high molecular weight polysaccharide, cellulose compound, nonionic surfactant, bentonite, and borate.

10. A cell assembly including a plurality of battery cells arranged in a first direction and a pack case in which the cell assembly is accommodated, A battery pack having a fire extinguishing unit disposed on at least one inner surface of the pack case, the upper surface and the side surface, for spraying the fire extinguishing composition according to claim 1 when a thermal event occurs.

11. In paragraph 10, The above thermal event is a battery pack including at least one of a temperature rise of 100°C or more, gas venting, flame ejection, and fire occurrence.

12. In paragraph 10, The above cell assembly, A plurality of temperature detection sensors mounted on the cell assembly to detect the surface temperature of the cell assembly, A gas detection sensor that detects the concentration of carbon monoxide, carbon dioxide and ethane contained in the internal air of the battery pack, and A battery pack having a sensing unit including at least one flame detection sensor that detects whether a flame has occurred and where the flame has occurred.

13. In paragraph 12, The battery pack further includes a control unit that is electrically connected to a sensing unit and a digestion unit, obtains information detected by a detection sensor of the sensing unit when a thermal event occurs, determines whether a thermal event has occurred and where it occurred from the obtained information, and moves the digestion unit to the corresponding occurrence location.

14. In paragraph 10, The above digestive organs are, A fire extinguishing agent storage unit located outside the above pack case and in which the fire extinguishing composition is stored, A gas storage unit located outside the above pack case and storing inert gas, A spraying device that receives and sprays the fire extinguishing composition and inert gas stored in the fire extinguishing agent storage unit and the gas storage unit, respectively, and is capable of rotating 180° along a direction perpendicular to the first direction, and A battery pack comprising a guide portion positioned on the inner side of the pack case and configured to move the injection device along the first direction of the cell assembly.

15. In paragraph 14, The above injection device, A slurry supply pipe that is fluidly connected to the above-mentioned extinguishing agent storage unit and supplies the extinguishing composition stored in the extinguishing agent storage unit, A gas supply pipe that is fluidly connected to the gas storage unit and supplies the inert gas stored in the gas storage unit, An injection body that is fluidly connected to the slurry supply pipe and the gas supply pipe and provides a space where the extinguishing composition and inert gas supplied from them are mixed, and A battery pack comprising a nozzle connected to the end of the injection body and injecting a mixture of a fire extinguishing composition and an inert gas.

16. In paragraph 15, The above gas supply line further includes a compression pump for applying pressure to the inert gas, The above nozzle is a battery pack whose flow rate is controlled by the pressure of the inert gas supplied from the gas supply pipe.

17. In paragraph 15, The above injection body is, A rotating device including a motor configured to generate a driving force for rotation along a direction perpendicular to the first direction and a gear interposed between the motor and the spray body; and A battery pack having a fixing device positioned between the above-mentioned rotating device and the guide portion, the fixing device moving the spray body by the guide portion.

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