Composition for extinguishing lithium-containing batteries or alkali metals

Abstract

The invention relates to fire-extinguishing compositions for extinguishing fires involving lithium-containing batteries or pure alkali metals. The claimed fire-extinguishing composition contains the following proportions of ingredients: 40-90 wt% water-alcohol mixture; 2-35 wt% at least one inorganic and / or one organic salt of alkali metals and / or alkaline earth metals and / or ammonia and / or aluminium; 2-25 wt% at least one inorganic and / or one organic salt of transition metals. The composition does not contain fluorine substances. The boiling point of the composition is not less than 100°С. The composition may additionally contain 0.5-6 wt% saturated carboxylic acids having 2-6 carbon atoms, not more than 15 wt% water-soluble and / or alcohol-soluble surfactants, and also chloride ions. The composition is in the form of a homogeneous liquid solution. The invention makes it possible to more efficiently extinguish lithium-containing batteries at any stage of heat build-up or ignition, as well as to extinguish lithium-metal anode batteries, while also providing for optimal delivery and being usable in fluid and foam fire extinguishers.

Description

[0001] Liquid fire extinguishing agent for extinguishing lithium-containing batteries or pure alkali metals

[0002] Field of technology

[0003] The invention relates to fire extinguishing compositions for extinguishing fires of lithium-containing batteries or pure alkali metals, in particular liquid fire extinguishing compositions that are salt solutions based on mixtures of water and alcohol, in which transition metal salts are used as additional inhibitory components.

[0004] The terms "lithium-containing batteries" or "lithium-containing accumulators" refer to chemical power sources and energy storage devices whose materials contain lithium or any of its compounds (oxides, salts, etc.). Thus, the term "lithium-containing batteries" refers to all known types of lithium batteries, including lithium-ion and lithium-polymer batteries.

[0005] The possibility of lithium-containing batteries catching fire and developing a fire involving them requires high-level fire safety measures, as such fires are characterized by an extremely intense combustion process, significant heat generation, and the formation of explosive conditions, as well as the release of large quantities of toxic combustion products from batteries, posing a threat to human life and health and significant material damage.

[0006] A characteristic feature of fires involving lithium-containing batteries is the presence of a combined fire source, since the battery contains substances whose extinguishing relates to different fire sources

[0001] :

[0007] A - fires of solid and smoldering combustible materials (various structural elements of the battery - housing elements, separator, etc.);

[0008] B - combustible components of liquid electrolyte and their decomposition products;

[0009] C - combustible gases, released in large quantities during combustion and decomposition of electrolytes (carbon monoxide and low molecular weight gaseous hydrocarbons);

[0010] D - fires of metals and their compounds (lithium, aluminum, etc.);

[0011] E - electrical installations under voltage.

[0012] The combination of physical and chemical phenomena during combustion of different fire sources in a single block of lithium-containing batteries makes them difficult to extinguish and imposes special requirements on the means used. An additional factor is the release of extremely toxic compounds during combustion and thermal decomposition of lithium-containing battery materials - aerosols of lithium oxides and hydroxides, vapors of halogen-containing compounds (hydrogen fluoride and hydrogen chloride), hydrocyanic acid, sulfur and nitrogen oxides [2,3].

[0013] As shown in the study [4], one of the problems in extinguishing batteries is the extinguishing of metals and their compounds (due to the highly exothermic nature of their oxidation reactions and the limitations of the extinguishing agents used). In this case, compounds capable of extinguishing Class D fires (metal fires) are effective. The use of water is only permissible for extinguishing small batteries, where a rapid cooling effect can be achieved without the risk of releasing significant amounts of hydrogen and other flammable gases with the release of hot aerosol and explosion. Experience in attempting to extinguish fires involving lithium-containing batteries in electric vehicles has demonstrated the ineffectiveness of extinguishing such fires with water and known water-foam compounds [4,5], since cooling and isolation from atmospheric oxygen alone do not always achieve the extinguishing effect (this is especially evident when extinguishing large battery packs).The presence of oxides or other oxygen-containing compounds of transition metals (cobalt, nickel, manganese, etc.) in batteries creates conditions for combustion in an oxygen-free environment (therefore, even complete immersion in water is ineffective), creating conditions for the formation of thermite mixtures with extremely high combustion temperatures (up to 3000°C). Furthermore, the battery itself is a chemical current source and is not powered by an external source, and therefore, de-energizing the battery cells during combustion is impossible. Therefore, extinguishing the fire with highly conductive fire extinguishing agents (including water-based ones) using traditional delivery systems (fire extinguishers, fire suppression modules, etc.) in such cases does not meet electrical safety requirements [5].This poses the challenge of creating new fire extinguishing compositions that take these factors into account and are capable of extinguishing lithium-containing batteries regardless of their condition and conditions of use, as well as being universal when extinguishing various battery materials.

[0014] Despite their versatility in extinguishing various fire classes, including Class D fires, powder compositions struggle to extinguish complex structures due to their inability to penetrate the burning material. Furthermore, large quantities are required to cover the fire. However, even this does not ensure reliable extinguishment, as oxygen isolation is not sufficient for effective extinguishment of radiator fires.

[0015] The second most significant factor complicating fire extinguishing of lithium-containing batteries is the presence of large quantities of flammable gases during electrolyte decomposition, which form burning gas flares due to their release during battery depressurization. In this case, the use of water becomes ineffective, and the main known extinguishing methods rely on diluting flammable gas mixtures with halogen-containing inhibitors, which create phlegmatizing and inhibiting concentrations that suppress combustion in the gas phase. In this case, effective extinguishing is achieved when the volumetric concentration of halons in the gas phase reaches 4-20%. This solution is effective only in environments that provide sufficient gas tightness and airtightness (electrical cabinets, chambers, enclosed equipment, etc.).During active battery combustion in the open air, the battery rapidly loses its seal, making it extremely difficult to achieve inhibitory concentrations in the presence of flaming gas fountains. Furthermore, the decomposition products of halons and their interaction with combustible battery components are the same hazardous halogenated products (primarily hydrogen halides, phosgene, etc.).

[0016] State of the art

[0017] Numerous solutions have been developed in this area using halons to extinguish lithium-containing batteries. Their advantage is the ability to extinguish combined fires. Disadvantages include low efficiency or the inability to extinguish Class D fires, the toxicity of decomposition products, and the difficulty of extinguishing large, unsealed batteries outdoors. To minimize these factors, capsules have been developed for various halogen-containing substances (primarily chlorine- and / or fluorine-containing compounds, among which fluoroketones are the most common). These capsules are placed in the battery casing and decompose upon heating, releasing a fire extinguishing agent that quickly reaches extinguishing concentration (if the battery casing has not been depressurized by this time). Examples of these solutions are given in patents KR102123584B1, published June 16, 2020; RU2791540C1, published December 20, 2022, and many others.However, these patents do not address the possibility of extinguishing a battery under conditions of rapid depressurization (for example, due to mechanical damage—when the initial battery casing is partially or completely destroyed, making it virtually impossible to create inhibitory concentrations of gaseous substances). This is particularly true for fires involving large lithium-containing batteries, such as traction batteries for electric vehicles.

[0018] Thus, most modern methods for extinguishing or localizing lithium-battery fires rely on external cooling with water or aqueous solutions, forced injection of various extinguishing agents, and the use of halons supplied from an external tank or by depressurizing extinguishing agent capsules. The advantage of using water and halons is their ability to cool the fire and penetrate the battery cells (due to their high fluidity). However, the risk of reignition remains, as isolation from atmospheric oxygen does not provide sufficient conditions for extinguishing. This is quite dangerous due to the release of hydrogen and gaseous halogenated substances.

[0019] The above determines the necessity and relevance of searching for and developing solutions for extinguishing various lithium-containing batteries, the use of which will be effective and reliable both for ensuring extinguishing and safe for people and the environment.

[0020] Due to the widespread use of such batteries in various mobile devices, battery-powered equipment, vehicles, autonomous energy sources and backup power supply systems, ensuring their fire safety is an important component that determines the possibility and conditions of their use.

[0021] The essence of the invention

[0022] The objective of the proposed invention is to create a liquid fire extinguishing composition applicable for extinguishing any lithium-containing batteries or pure alkali metals, which satisfies the following requirements:

[0023] 1) ensure the possibility of reliable extinguishing by effectively cooling the fire source, inhibiting the oxidation reaction of the main combustible substances, and eliminating conditions for the occurrence of explosions;

[0024] 2) eliminate fluorine-containing fire extinguishing agents, thereby solving the environmental problem of toxic vapor emission;

[0025] 3) reduce the emission of hazardous aerosols from burning substances and materials;

[0026] 4) ensure the versatility and reliability of the extinguishing method;

[0027] 5) increase the functional capabilities, and as a consequence expand the purpose; 6) use, if possible, inexpensive and accessible components for the production of such compositions in order to ensure low cost of the compositions based on them.

[0028] Thus, the objective of the present invention is to create new liquid fire extinguishing compositions that satisfy the set of requirements given, taking into account the possible conditions of their use.

[0029] Liquid-based solutions appear to be the most effective for solving this problem, due to their ability to penetrate the burning material, their significant cooling effect, and their ability to be delivered over long distances (to ensure a safe distance from the fire). Water-based compounds with functional additives, as indicated in [5], are particularly promising for extinguishing lithium-containing batteries due to their high heat capacity, high wettability, low viscosity, and electrical safety.

[0030] The technical result of the invention is to increase the efficiency of extinguishing lithium-containing batteries at any stage of their heating and combustion with a smaller amount of liquid fire extinguishing agent, the possibility of extinguishing the most explosive batteries with a lithium-metal anode, ensuring an optimal supply mode by increasing their fluidity and the possibility of using liquid fire extinguishers and foam generators.

[0031] The stated technical result is achieved through a liquid fire extinguishing composition, which includes the following components in a concentration of the total mass of the composition, but in total no more than 100 mass %:

[0032] a water-alcohol mixture with a mass ratio of alcohol and water in any proportions;

[0033] at least one inorganic and / or at least one organic salt of alkali and / or alkaline earth metals and / or ammonium and / or aluminum - 2-35 wt. %;

[0034] at least one inorganic and / or at least one organic salt of transition metals - 2-25 wt. %;

[0035] wherein the said composition may additionally contain saturated carboxylic acids with a number of carbon atoms from 2 to 6 inclusive - 0.5-6 mass %;

[0036] and / or surfactants - no more than 15% by weight, with the proportion of the remaining substances decreasing within the limits of their declared proportions. Therefore, when determining suitable embodiments of liquid fire extinguishing compositions according to the present invention, preference is given to compositions with a high specific heat capacity and boiling point. Through calculations and testing of various fire extinguishing compositions, it was determined that an acceptable minimum limit for the specific heat capacity of suitable liquid compositions is 2500 J / kg*K. When using liquid compositions with higher specific heat values, even at a low flow rate (for example, by spontaneous flow from a container without the use of forced feed or injection systems), sufficient heat removal is ensured, allowing for rapid cooling and thereby ensuring one of the main factors of extinguishing and transferring unignited adjacent battery cells to a safe mode.A minimum boiling point above 100°C was chosen for the liquid compositions to prevent premature boiling and evaporation of the fire extinguishing fluid and its components. This choice provides a significant advantage over halons, as most of them have a low boiling point (no more than 60°C) and a comparatively low heat capacity (no more than 1200 J / kg*K). When used in capsules, the selected temperature range of the fire extinguishing compositions claimed in this invention also offers the advantage of preventing premature activation, for example, when charging batteries.

[0037] The use of fluorine-free fire extinguishing agents eliminates the problem of toxic vapor release from fluorinated compounds. Therefore, the absence of fluorinated substances is a mandatory requirement when determining the components of the fire extinguishing agent for the purposes of this invention. Therefore, the selection of fire extinguishing agents in this invention is based on the use of fluorine-free components.

[0038] When selecting a fire extinguishing agent for the claimed method, preference is given to gas-generating extinguishing agents, which, upon decomposition, are capable of forming large quantities of non-flammable gases (e.g., carbon dioxide, nitrogen, water vapor, etc.), acting as diluents for flammable gases and thus significantly narrowing the range of explosive concentrations, while simultaneously suppressing combustion at a sufficient gas emission rate. Due to the endothermic nature of the gas emission process and the removal of heat with the exhaust gases, an additional cooling factor is provided. An example of such a composition is the variant described in patent RU2784095C1, published November 23, 2022. The viscosity of the liquid extinguishing agent used is essential, since it is very difficult to achieve a fine spray when applied through nozzles, thereby ensuring electrical safety.High-viscosity liquids require special design solutions for delivery systems. This significantly reduces extinguishing efficiency (low fluidity of the liquid or gel-like composition increases extinguishing time), and their delivery range is also shorter compared to low-viscosity compositions. Therefore, reducing the viscosity of the liquid fire extinguishing agent is one of the objectives of the invention.

[0039] To ensure the required combination of properties through the selection of components for preparing liquid fire extinguishing agents for lithium-containing batteries, the invention defines an optimal composition based on a water-alcohol mixture (hereinafter referred to as "Component 1") with a mass ratio of alcohols to water in any proportions other than zero, with a total concentration of 40 to 90% by weight of the total mass of the fire extinguishing agent. The water-alcohol mixture is a true solution of these substances, rather than a solution of surfactants or various types of colloidal dispersed systems. The number of individual components used within the alcohol mixture is unlimited.

[0040] Alcohols are defined as organic hydroxyl-containing compounds (i.e., organic compounds with one or more hydroxyl groups), regardless of their state of aggregation (liquid or solid), including dihydric, trihydric, tetrahydric, polyhydric, and high-molecular-weight alcohols, including complex organic compounds with other functional groups, provided they contain reactive hydroxyl groups. Thus, they include aliphatic alcohols of normal or isostructure, aromatic alcohols, glycols, polyglycols, amino alcohols, alcohol ethers, carbohydrates, and polyhydroxy compounds (polymeric compounds having at least one hydroxyl group in the monomer residue).Examples may include, but are not limited to, methanol, ethanol, 1-propanol, isopropanol, 1-butanol, isobutanol, tert-butyl alcohol, phenol, benzyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycols, glycerin, pentaerythritol, monoethanolamine, diethanolamine, triethanolamine, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl diglycol, mono- and disaccharides (glucose, fructose, galactose, mannose, maltose, sucrose), starch, modified starches, dextrin, cellulose and its derivatives, gums (guar, xanthan, konjac), polyvinyl alcohol.The values ​​of concentration of the water-alcohol mixture and selected For specific compositions, the ratios of alcohol and water depend on the solubility limits of the other components of the fire extinguishing composition selected, as well as on the required viscosity, boiling and freezing points of the resulting composition.

[0041] The second mandatory component of the liquid fire extinguishing composition according to the present invention is inorganic and / or organic salts of alkali and / or alkaline earth metals and / or ammonium and / or aluminum, in any proportions, at a concentration of 2 to 35% of the total composition weight (hereinafter referred to as "Component 2"), including their acidic and basic salts. The number of individual components used within the mixture of such salts is not limited.

[0042] The use of these salts is driven by their increased fire extinguishing capacity, particularly for extinguishing Class A fires, which constitute the primary fire load when considering battery fires. Numerous patent publications exist on the effect of salt compositions on the fire extinguishing capacity of liquid compounds, particularly chlorides, sulfates, and phosphates of alkali and alkaline earth metals, aluminum, and ammonium, with detailed descriptions of their mechanism of action. Also noteworthy is the beneficial gas evolution of some salts during decomposition, particularly ammonium salts, carbonates, and metal carboxylates (releasing ammonia and carbon dioxide). Dilution of the flammable gases released during electrolyte decomposition reduces the intensity of their combustion, thereby narrowing the limits of explosive concentrations or even eliminating the possibility of gas flares and explosions.Examples of suitable salts, but not limited to, include water- and / or alcohol-soluble chlorides, sulfates, hydrogen sulfates, hydroxosulfates, carbonates, hydrogen carbonates, orthophosphates, pyrophosphates, polyphosphates, tetraborates, formates, acetates, propionates, citrates, oxalates, lactates, gluconates, benzoates, malates, and succinates of sodium, potassium, magnesium, calcium, aluminum, and ammonium. The use of chlorides is justified here by the fact that they also exhibit a very high inhibitory capacity during fire extinguishing, while their decomposition with the release of chlorine-containing products is excluded.

[0043] The upper limit of the selected concentration, 35% by weight of the total composition weight, is determined by the limits of their solubility in a water-alcohol composition without loss of stability of the resulting composition and was determined empirically for a number of compositions. The lower limit is determined by the loss of the desired effect, and therefore the addition of salts in an amount of less than 2% by weight of the total composition weight is impractical. Since, as noted above, extinguishing lithium-containing batteries poses a separate problem when extinguishing materials included in class D, the present invention proposes the use of inorganic and / or organic transition metal salts in any proportions in a concentration of 2 to 25% of the total composition weight (hereinafter referred to as "Component 3"), including their acidic and basic salts.The presence of reactive salts of cl-elements, which are less active than alkali or alkaline earth metals due to their higher electronegativity on the Pauling scale, enables the absorption of energy by electron addition to unfilled d-habitats due to their low electron affinity. Electron affinity is known to determine oxidizing power, and atoms with high electron affinity are strong oxidizing agents. Therefore, the best choice would be compounds of those d-elements that are good reducing agents with negative electron affinities, among which Cr, Cu, Ni, and Co are particularly notable. Of particular interest are salts with low transition energies between ionized states of d-elements in various oxidation states, such as Fe. 3+ / Fe 2+ , So 3+ / So 2+ , Sg 3+ / Сг 2+etc., which serve as good reducing agents. Moreover, since the reduction of transition metal salts is catalyzed by atomic hydrogen and their activation energy is lower, they are capable of very active participation in oxidation-reduction reactions to form non-flammable products, without acting as oxygen donors. The above-described mechanism and properties of transition metal salts determine the possibility of inhibiting the oxidation reactions of alkali metals to form non-flammable products. Examples of useful water- and alcohol-soluble transition metal salts include, but are not limited to, chlorides, sulfates, nitrates, acetates, formates, citrates, gluconates, oxalates, lactates, glycinates, and succinates of iron, nickel, cobalt, copper, zinc, chromium, and manganese. The number of individual components used within a mixture of such salts is unlimited.

[0044] The upper and lower limit values ​​of the selected concentration of salts constituting Component-3 - from 2 to 25% by weight of the total mass of the composition - are determined by the same reasons as for the salts of Component-2.

[0045] Saturated carboxylic acids with 2 to 6 carbon atoms, inclusive, can be used as an additional component of liquid fire extinguishing compositions for battery fires, at concentrations ranging from 0.5 to 6% of the composition's total weight. The maximum concentrations of such acids have been established experimentally, taking into account their potential solubility in the liquid medium and the sufficiency of their use to ensure the desired effect. Examples include acetic, propionic, butyric, aminoacetic, oxalic, lactic, malic, tartaric, succinic, and citric acids. These acids were chosen due to their relatively good solubility in water and many alcohols without the formation of colloidal systems. Unsaturated acids (acrylic, methacrylic, fumaric, etc.) are not used due to their potential for polymerization and self-aggregation.

[0046] The use of saturated carboxylic acids as independent components provides a number of technical advantages, namely:

[0047] 1) ensuring passivation of active burning metals in a safe mode;

[0048] 2) increasing the solubility of many salts of Component-2 and Component-3, which form highly soluble complexes with these acids;

[0049] 3) carboxylic acids act as a buffering agent when regulating the acidity of the fire extinguishing composition.

[0050] It has been empirically established that the rate of reaction between carboxylic acids and active alkali or alkaline earth metals is very slow due to the low reactivity of these acids, so the metal oxidation reaction proceeds safely. There are known examples of the safe dissolution of pure alkali metals even in relatively strong organic acids, such as acetic acid, which reacts without ignition or explosion due to its slow dissolution. At the same time, even aqueous solutions of carboxylic acids visibly inhibit metal oxidation by water, as carboxylic acids are the first to react due to their acidic nature. The use of carboxylic acids in aqueous-alcoholic solutions in the presence of transition metal salts significantly enhances the passivation effect of burning active metals, ensuring rapid and reliable extinguishing by allowing the acids to react with them instead of water, forming difficult-to-combust or non-combustible substances.

[0051] A similar effect, according to literary data [5], is produced by fatty alkyl esters of aliphatic acids in aqueous solutions of fatty alcohols with a number of atoms of 6-12 in the fire extinguishing agent F-500 produced by Hazard Control Technologies, when at a concentration of 2-5 mass.% it becomes possible to extinguish lithium batteries.

[0052] The advantages of the claimed fire extinguishing composition compared to F-500 are the use of readily available and inexpensive carboxylic acids instead of fatty alcohol esters, which are capable of forming stable solutions without the need for additional stabilization or preliminary mixing, the possibility of creating compositions with a low freezing point (down to minus 40 °C) compared to minus 3 °C for F-500, as well as the possibility of directly extinguishing alkali metals and large quantities of alkaline earth metals (including pyrophoric fine powders) due to the combined inhibitory action of carboxylic acids and transition metal salts, providing a more powerful fire extinguishing effect.

[0053] Therefore, preference is given here to carboxylic acids with low activity of functional carboxyl groups and at the same time with high complexing capacity in relation to multivalent cations: aminoacetic, lactic, citric, acetic and malic acids.

[0054] The liquid fire extinguishing composition according to the invention may also contain a surfactant in an amount of up to 15% by weight. This component is optional, but its presence becomes necessary when it is necessary to increase the composition's fluidity (by increasing wetting, reducing surface tension) or to make it suitable for use in foam generators. In the latter case, the surfactant must exhibit foaming properties in saline aqueous-alcoholic solutions. Foaming makes it possible to use low- and medium-expansion foam generators as delivery devices and to reduce the consumption of the extinguishing composition.

[0055] Moreover, the use of stable surfactants that do not cause undesirable effects (sediment formation or decomposition due to interaction with other components) is permitted in these formulations. The choice of surfactant depends on the ability to operate in environments with varying pH values, and therefore cationic, amphoteric, and nonionic surfactants can be used for acidic environments, or anionic, amphoteric, and nonionic surfactants for alkaline environments. Amphoteric and nonionic surfactants, which are stable over a wide pH range and have virtually no interaction with the formulation's components, offer a distinct advantage. Examples of suitable surfactants include, but are not limited to, alkylamine oxides, alkyl betaines, amidoalkyl betaines of higher fatty acids, alkylolamides of higher fatty acids, polysorbates, alkyl glycosides, alkyl sulfates, alkyl aryl sulfonates, alkyl phosphates, alpha-olefin sulfonates, and alkylated quaternary ammonium chlorides. Fluorinated surfactants are not used as surfactants according to the present invention.

[0056] The range of possible combinations for the use of the specified components in determining liquid fire extinguishing compositions within the framework of the solution claimed in the present invention is not limited to them, but may include any solutions that satisfy the specified conditions.

[0057] The liquid fire extinguishing compositions of the present invention are homogeneous, ready-to-use compositions that require no prior preparation. The use of two- or multi-component mixtures requiring mixing before use is not contemplated, as this requires additional technical solutions for mixing the reagents and reduces extinguishing reliability.

[0058] The liquid fire extinguishing composition of the present invention may be a liquid solution capable of forming gas / liquid dispersions, i.e., foaming. In this case, the foaming liquid composition may contain a certain number of gas bubbles.

[0059] The claimed liquid fire extinguishing compositions can be housed within batteries (e.g., in special containers or encapsulating agents) or supplied externally—from an external reservoir by gravity or forced delivery using a suitable, accessible method (pneumatic, mechanical, etc.). They are also suitable for use in fire extinguishers and foam generators. Any suitable carrier gas—air, nitrogen, argon, etc.—can be used in fire extinguishers or other pneumatic delivery devices.

[0060] A review of the prior art has shown that the protected fire extinguishing liquid composition has significant distinctive features in relation to its analogues.

[0061] Thus, patents RU2784095C1, published November 23, 2022; RU2784106C1, published November 23, 2022, and patent application CN118613306A, published September 6, 2024, are known, which use a mixture of alkali and alkaline earth metal salt solutions (magnesium chloride and potassium carbonate) with the possible addition of propylene glycol to extinguish lithium-ion batteries. These initially use two solutions, mixed together immediately upon use, which complicates the design of the delivery systems and reduces the reliability of extinguishing. The solution presented in this patent is distinguished by the fact that the composition is ready-made and does not require pre-mixing. In addition, the addition of transition metal salts allows for enhanced fire extinguishing performance without the need to convert the fire extinguishing agent into a gel-like state by using high concentrations of glycol, and therefore the agent can remain at a low viscosity, which reduces consumption during its use.

[0062] The liquid compositions presented in application US2024424454A1, published on 26.12.2024, contain saturated aqueous solutions of alkali metals. Despite the simplicity and low cost of these compositions, they are incapable of quenching lithium due to the lack of an inhibition mechanism (see Example 1). In patent CN113209541B, published on 06.08.2021 and patent applications CN115445136A, published on 09.12.2022; CN116808499A, published on 29.09.2023; international application W02023089108A1, published On May 25, 2023, a patent cited the possibility of using aqueous-alcoholic solutions of salts together with surfactants and suspended particles of vermiculite, carbon, or aluminum hydroxide to produce fire-extinguishing suspensions for extinguishing lithium batteries. These sources do not mention the use of carboxylic acids, and the products themselves are heterogeneous systems whose stability, despite the presence of thickeners and dispersants, is limited by time. Patent US2013207018A1, published August 15, 2023.In 2013, an aqueous suspension of poorly water-soluble calcium, magnesium, or strontium salts with a dispersing thickening agent was proposed for fire extinguishing. In the invention proposed here, the liquid composition does not contain any solid or liquid suspended particles, meaning it does not constitute a heterogeneous system (suspension or emulsion). Therefore, there is no risk of instability of such dispersed systems and no need for preliminary homogenization or the addition of any colloidal system stabilizers.

[0063] Applications CN116271674A, published June 23, 2023, and CN108014442A, published May 11, 2018, describe water-based liquid fire extinguishing compositions that use alcohols, organosilicon, and fluorinated surfactants as additives. A distinctive feature of the present invention is the use of a set of cheaper and more readily available inorganic and organic salts, and transition metal salts and additionally carboxylic acids are used as flame retardants instead of toxic fluorinated compounds and their decomposition products. Applications CN115671640A, published May 11, 2018,

[0064] 03.02.2023; CN115671640A, published 03.02.2023; CN114177564A, published 15.03.2022, and CN109939410A, published 28.06.2019, the above compositions also contain fluorocarbon surfactants, which are extremely unfavorable for the environment, in contrast to the claimed composition, in which the use of fluorine-free fire extinguishing agents eliminates the risk of poisoning by decomposition products and the problem of disposal of fluorine-containing compounds. Therefore, the requirement for determining the components of the fire extinguishing composition within the framework of the present invention is the absence of fluorine-containing substances. In this regard, the selection of fire extinguishing agents in the present invention is based exclusively on the use of fluorine-free components. The use of fluorinated surfactants in the above patents is due to the need to increase the fluidity of the compositions and their inhibitory effect. In the patent claimed here, inhibition is achieved by the presence of transition metal salts in the composition and saturated carboxylic acids that further enhance their action.Application KR20240022224A, published February 20, 2024, describes an invention for extinguishing Class D fires and lithium battery fires using an aqueous gel based on silicates and polyacrylates with various flame arrestors and inorganic salt additives. This solution does not cover the use of alcohols, transition metal salts, and carboxylic acids as possible components and therefore lacks several of the aforementioned advantages. Furthermore, these flame arrestors also comprise solid particles of glass beads, silica, and metal oxides or hydroxides, meaning the resulting system is also a suspension whose stability is limited in time.

[0065] Patent application CN103170083 A, published June 26, 2013, describes an aerosol-forming fire extinguishing composition utilizing transition metal salts (iron, nickel, zinc, copper, cobalt, manganese, etc.) as the main component (65 to 95%) of the fire extinguishing composition, with the possible addition of industrial alcohol during its preparation. This invention does not use water as a solvent, and the final product is a composite aerogel agent. At the same time, this invention describes a positive fire extinguishing effect from the decomposition of organic transition metal salts. The fire extinguishing compositions described in this patent are not classified as liquid fire extinguishing compositions, and the high content of transition metal salts significantly increases their cost, which is a disadvantage.

[0066] The use of transition metal salts in a lithium battery thermal runaway inhibitor is also mentioned in patent CN114159717B, published December 23, 2022. Distinguishing features include the absence of water in the composition, the presence of fluorine-containing compounds, and a different component weight ratio. The absence of water makes compositions based on it highly viscous, limiting their scope of application and significantly increasing their cost. Furthermore, the composition described is not a solution of the components mentioned, but a suspension, as a dispersant is a required component of the composition.

[0067] In applications US2012312562A1, published 12 / 13 / 2012, and US2014034864A1, published

[0068] February 6, 2014, provides examples of aqueous fire extinguishing compositions based on alkaline earth metal salts and water-swelling polymers that can be cross-linked with glycols. The use of these polymer gels significantly limits the use of these compositions for extinguishing alkali metal fires, including fires involving lithium-ion batteries, unlike the claimed composition. The viscosity of the liquid extinguishing agent is crucial, as it is very difficult to achieve a fine spray when applied through nozzles, thereby ensuring electrical safety. High-viscosity liquids require special design solutions for the delivery system, which significantly reduces extinguishing efficiency (low fluidity of the liquid or gel composition increases extinguishing time), and their delivery range is also shorter compared to low-viscosity compositions.

[0069] In addition, the composition claimed in accordance with the present invention contains an alkali metal combustion inhibitor in the form of transition metal salts, which makes it possible to extinguish even pure alkali metals and significantly increases the efficiency of extinguishing lithium batteries.

[0070] The ability to extinguish pure metallic lithium (with a base metal content greater than 99% by weight), alkaline earth metals, and light metals is crucial when comparing fire extinguishing agents for lithium-containing batteries, as these are the most challenging to extinguish due to their extremely high reactivity and explosiveness. However, given the potential presence of lithium as pure metal (in lithium-metal battery anodes), aluminum foil testing is necessary for such challenging applications. Example 1 below shows an example of a composition according to the present invention for extinguishing a lithium metal ingot.

[0071] A liquid fire extinguishing composition described in patent RU2699752C1, published September 9, 2019, describes the ability to extinguish Class D1 fires with aqueous solutions of alkali metal, aluminum, and copper salts, as well as the use of surfactants. This solution can be considered the closest analogue to the claimed invention and has been adopted as a prototype. While this patent contains some of the substances listed in the present invention, the main difference is the use of a water-alcohol component (Component 1), which expands the range of possible combinations and provides a number of significant advantages.

[0072] The ability to extinguish metallic lithium and its compounds is ensured by the presence of Component 3 and, if necessary, saturated carboxylic acids with carbon atoms from 2 to 6 inclusive, which inhibit its active reaction with water, but are absent from the proposed analogue. Attempts to extinguish metallic lithium with the composition described in patent RU2699752C1, published on September 9, 2019, do not result in an explosion (as observed in many other cases), but do result in increased lithium combustion and confirm the impossibility of extinguishing it (see Example 1).

[0073] Adding alcohols to a fire extinguishing composition serves several purposes: 1) alcohols serve as excellent co-solvents and complexing agents for many inorganic and organic salts, increasing their solubility, including through complex formation, ensuring the stability and homogeneity of the system for a long time;

[0074] 2) many alcohols are capable of lowering the surface tension of water or water-salt solutions, thus improving the fluidity of the resulting compositions based on them;

[0075] 3) alcohols with a high molecular weight increase the boiling point of the liquid composition, making it less volatile;

[0076] 4) the use of alcohols in the mixture makes it possible to extinguish even pure (metallic) alkali metals, since the reaction of their neutralization with alcohols occurs less violently and without an explosion.

[0077] 5) a number of alcohols lower the freezing point of water-alcohol solutions and thereby expand the operating temperature range of compositions based on them.

[0078] When extinguishing lithium-containing batteries, the ability to extinguish lithium is crucial, as metallic lithium is the most difficult to extinguish and is extremely explosive, especially when in contact with water, aqueous solutions, many organic compounds, and freons. The prototype patent mentions the ability to extinguish magnesium, aluminum, titanium, and their alloys, while the liquid fire extinguishing agent according to the present invention is also capable of extinguishing burning lithium metal and its compounds.

[0079] Thus, there are a number of significant distinguishing features between them, namely:

[0080] 1) in the present invention, the main distinguishing feature is the presence of a water-alcohol component;

[0081] 2) the present invention specifies the requirements for the thermophysical and physicochemical characteristics of the fire extinguishing composition to ensure the possibility of guaranteed extinguishing, whereas the prototype patent does not disclose the requirements for them that affect the effectiveness of such a solution;

[0082] 3) the claimed liquid fire extinguishing composition is capable of extinguishing alkali metals and their compounds, whereas the prototype patent does not indicate the possibility of extinguishing lithium-containing batteries; 4) the area of ​​application of the fire extinguishing compositions differs.

[0083] Thus, the cited patents and patent applications provide fire extinguishing compositions that use various components mentioned in the present invention, but nowhere is the combination claimed here in the indicated proportions found, and also none of the cited sources indicate the possibility of additional use of saturated carboxylic acids as a possible component for passivation of active metals, which together provide a strong fire extinguishing effect with the availability of components, low cost and improved performance characteristics.

[0084] Implementation of the invention

[0085] The patent descriptions and patent applications cited above, which are considered analogs to the present invention, provide virtually no data on extinguishing actual batteries, demonstrating their fire extinguishing capacity and effectiveness. While numerous patented solutions are known in this area of ​​technology, statistics and characteristics of fires involving lithium-containing batteries indicate that extinguishing them remains difficult or impossible, and existing prevention or suppression systems have not proven sufficiently effective.

[0086] Therefore, to conduct tests that closely approximate real fire conditions, it was necessary to create appropriate experimental conditions. For this purpose, model fire sites were developed that represent full-scale imitation of lithium-based batteries, as well as reproducible thermal (heating), electrical (overcharging), or mechanical (impact, impalement) initiation of thermal runaway and ignition.

[0087] Drawings explaining the essence of the invention.

[0088] Fig. 1 shows a photo of a model fire site according to examples 7-8.

[0089] Fig. 2 shows a photo of a model firebox according to example 6.

[0090] Fig. 3 shows a photo of extinguishing a model fire according to example 7 using a liquid fire extinguishing agent for extinguishing lithium-containing batteries, where A is the outbreak of the fire; B is the supply of the fire extinguishing agent (FE); C is the result of extinguishing; D is the analysis of the fire.

[0091] Fig. 4 shows a photograph of the external appearance of the model fire source during the experiment according to example 6, where A is the initial stage; B is flame combustion; C is the supply of the fire extinguishing agent; G is the cessation of the supply of the fire extinguishing agent; D is the external appearance of the fire source after extinguishing; E (on the right) is the external appearance of the battery after extinguishing. Fig. 5 shows a temperature graph (thermogram) of the model fire source according to example No. 1.

[0092] Fig. 6 shows a graph of the temperatures of the model hearth according to sample No. 2. Fig. 7 shows a graph of the temperatures of the model hearth according to sample No. 3.

[0093] Examples

[0094] To confirm the effectiveness of the declared fire extinguishing compositions, testing was carried out, presented in the examples.

[0095] All experiments were carried out outdoors with free access to oxygen.

[0096] To confirm the possibility of extinguishing any lithium-containing batteries, including those with a metallic lithium anode as the most difficult case, in Example 1 an example test is carried out to extinguish a small amount of metallic lithium to assess the nature of the interaction of the fire extinguishing agent.

[0097] Example 1

[0098] A fire extinguishing agent based on a water-alcohol mixture of water and polyethyleneglycol with a molecular weight of 400 with an alcohol:water ratio of 80:20 was used - 90 wt. % (Component 1), potassium chloride - 6 wt. % (Component 2), nickel (II) chloride - 2.5 wt. % (Component 3), butyric acid - 1.5 wt. %. The test consists of determining the extinguishing time of a solid ingot of metallic lithium with an active substance content of at least 99.0 wt. % weighing 10 g in a model fire source, which is a pre-dried thick-walled cast iron mold. Ignition was carried out using a device with a gas burner. Upon achieving spontaneous combustion of lithium and the appearance of a characteristic dark red flame, the start time of free combustion of lithium was recorded, and the ignition device was removed from the test area.After 60 seconds from the onset of free combustion, when the burning lithium had glowed bright white and reached a temperature above 1000°C, extinguishment was initiated by pouring 200 ml of liquid fire extinguishing agent from a container positioned on a rigid pole at least 1.5 m from the operator. Extinguishing time was shown to be less than 1 minute.

[0099] A similar test with the original composition according to patent RU2699752C1, published on 09.09.2019, showed an increase in combustion intensity and the inability to extinguish lithium.

[0100] A similar test with a reproduced composition according to application US2024424454A1, published.

[0101] On December 26, 2024, the fire showed increased intensity and the inability to extinguish it with lithium. A similar test using the original US-made fluorinated liquid composition resulted in an immediate explosion of lithium metal, demonstrating not only the inability to extinguish it but also the serious risks associated with its use.

[0102] Example 2

[0103] A battery pack consisting of 3.7V NCR 18650 cells with a total capacity of 96Ah was used as a model fire starter. The battery pack was housed in a steel case with a steel mesh attached to the top. Ignition was achieved by heating the fire from an external source using a tubular electric heater.

[0104] When the fire flared up, it was extinguished using a mixture of water and isopropyl alcohol in a ratio of 90:10 (76% by weight), a mixture of magnesium and ammonium sulfates in a ratio of 1:4 (20% by weight), and cobalt(II) chloride hexahydrate (4% by weight). The mixture was applied from a 5-liter pressurized fire extinguisher with a spray nozzle. Extinguishing was accomplished in 45 seconds.

[0105] Example 3

[0106] A steel cylinder with a wall thickness of 2 mm was used as a source of fire, in which 32 lithium-ion batteries 18650 INR 3.2 V with a capacity of 2000 mAh each were placed, directly adjacent to each other. In the upper part of the cylinder with a lid, a hermetically sealed polyethylene container with a volume of 0.5 liters was placed with a liquid fire extinguishing agent with a boiling point of 112 °C. The composition of the fire extinguishing agent is water: ethylene glycol: triethanolamine in a ratio of 4: 4: 2 in an amount of 70 wt. %, sodium citrate - 4 wt. %, 20 wt. % - iron sulfate monohydrate (III), citric acid - 6 wt. %. The advantage of this composition is a low freezing point, and it can be used at temperatures down to minus 30 °C. At the bottom of the cylinder, a wire was connected to the battery terminals to charge them, and a thermocouple was introduced, the temperature-sensitive element of which was placed in the middle of the battery block (between them).The batteries were ignited by overcharging them with a current significantly exceeding their rated charging current. The ignition time was 3 minutes before the lithium-ion battery safety valves were triggered. The temperature reached 110°C before the batteries depressurized and active thermal runaway began. After 15 seconds, the thermocouple recorded a sharp rise in temperature, reaching 330°C with flames appearing from under the lid. The fire extinguishing agent module was triggered, with a sharp drop in temperature within 5-10 seconds to below 100°C, followed by a gradual cooling of the fire to below 50°C. Upon examination of the cooled fire, it was determined that five elements had depressurized, three of which had burned completely. The remaining battery elements remained intact, and testing showed that these elements were suitable for further use.

[0107] Example 4

[0108] The fire source was similar to that described in Example 3, with the following differences: a polypropylene container was used, and the extinguishing agent was a liquid fire extinguishing composition with a boiling point of 168 °C and a specific heat capacity of 2560 J / kg*K at 20 °C (determined calorimetrically) based on glycerin and water in a ratio of 95:5 - 80 wt. %, aluminum potassium alum - 5 wt. %, zinc sulfate - 11 wt. %, lactic acid - 4 wt. %. The use of small amounts of aluminum potassium alum helps to liquefy the composition, and the use of a high-boiling mixture of glycerin and water helps to avoid early boiling of the liquid in cases where the safety of batteries with a high thermal runaway temperature (over 120 °C) is ensured. Ignition was achieved by heating the steel cylinder body with a propane torch. The batteries used were 18650 LTO 3.7 V with a capacity of 1500 mAh.The fire was extinguished within seconds, and upon investigation, it was discovered that one battery cell was damaged (depressurized and partially charred), which had damaged the extinguishing agent container. The maximum thermocouple temperature read 244°C. No significant heating or ignition of adjacent cells was observed.

[0109] Example 5

[0110] A lithium-polymer battery pack with a voltage of 22.2 V and a total capacity of 30 Ah was used as a model fire source. Ignition was achieved by mechanical damage (puncture) of the battery with its rapid self-ignition. Extinguishing was carried out using a 5-liter pressure fire extinguisher. The used fire extinguishing fluid is water-based with the addition of hydroxyethyl cellulose in a ratio of 99:1 - 85 wt. %, a mixture of sodium and ammonium sulfates in a ratio of 1:1 - 10 wt. %, copper (II) sulfate - 4.5 wt. %, acetic acid - 0.5 wt. %. The fire was supplied from a 5-liter pressure fire extinguisher with a spray nozzle. Extinguishing was accomplished in less than 30 s. The advantage of the composition presented here is its ability to quickly cool the source, low cost and versatility in relation to extinguishing many small fires involving lithium-containing batteries.The addition of hydroxyethyl cellulose allows for a slight thickening of the composition so that it does not quickly flow off the burning surface, while at the same time forming a non-combustible crust of reaction products on it and isolating it from oxygen.

[0111] Example 6: A battery pack for powering uninterruptible power supplies, consisting of 56 lithium-iron-phosphate cells of the 32700 type, was chosen as the source of the fire. The battery pack capacity was 80 Ah, voltage 12.8 V. The battery pack was placed in a lidless steel cell with walls spaced 5 cm from the battery surface. Ignition was achieved by heating from an external source using a tubular electric heater. A temperature sensor was attached to the battery pack housing, transmitting a signal to recording equipment. When ignition occurred and the temperature reached more than 700 °C according to the sensor readings, extinguishing was carried out by feeding the extinguishing agent from an external tank with a pump through a fire hose and a nozzle placed above the box. The extinguishing agent was a mixture of water and propylene glycol (4:1) - 40 wt. %, potassium acetate (35 wt.%), a mixture of zinc acetate and copper sulfate (1:4) - 25 wt.%.This composition has a low viscosity, allowing it to be used in multiple sprayers, and a low freezing point due to the high potassium acetate content. Another advantage of using potassium acetate is its effective extinguishing of Class B fires and its ability to quickly suppress excessive gas evolution due to the increased extinguishing efficiency of electrolyte components. When the fire was dismantled after it had cooled, more than 100% of the components were found to be intact.

[0112] Example 7

[0113] The fire was centered on a rectangular tray containing a cassette containing 161 ICR 18650 lithium-ion batteries (hereinafter referred to as LIBs) with a capacity of less than 2.55 Ah. A steel lid was secured to the tray with studs, allowing for a gap of up to 2 cm to simulate a battery casing depressurization and to dispense the extinguishing agent. The lid also ensured the experiment's safety by preventing the scattering of burning batteries. Ignition was achieved by heating the fire from an external source using a tubular electric heater. Extinguishing was accomplished when the maximum temperature reached over 600°C using a 5-liter self-priming fire extinguisher with a low-expansion foam nozzle. A thermocouple input was made in the side of the steel tray, the end of which was placed in the center of the hearth (between the cylindrical elements), the signal was transmitted to an analog-to-digital converter (recording device), from where the data was downloaded in the form of thermograms.

[0114] The experiment utilized a fire extinguishing agent based on a mixture of water and ethylene glycol (80:20) — 82% by weight, aluminum sulfate octadecahydrate — 7% by weight, potassium chromium alum — 4% by weight, cocoamidopropyl betaine — 5% by weight, and aminoacetic acid — 2% by weight (sample #1). The agent exhibits high fire extinguishing performance compared to similar products, both due to the use of chromium salts and the ability to reduce consumption through foaming. The use of saturated carboxylic acids as independent components ensures the safe passivation of active burning metals. Less than half of the extinguishing agent was consumed to extinguish the model fire in this example. Some of the batteries remained intact (undamaged).

[0115] Similar tests were conducted with 5-liter fire extinguishers containing liquid fluorocarbon-based compounds manufactured in the USA (sample No. 2) and a liquid compound based on an aqueous solution of specialized surfactants manufactured in Europe (sample No. 3). For comparison, the volume of the extinguishing compounds used in all cases was the same: 5 liters.

[0116] The extinguishing results are presented in Table 1, and the thermograms are shown in Figures 5-7.

[0117] Table 1

[0118]

[0119] During the tests carried out, it was established that: - when dismantling the model fires after their complete burnout, after attempts to extinguish them using fire extinguishers with samples No. 2 and No. 3, no unburned elements of the LIB were found;

[0120] - sample No. 2 showed the possibility of cooling the fire (as can be seen from the thermogram in Fig. 6), but could not cope with it due to the lack of inhibition capability and insufficient fire extinguishing capacity;

[0121] - when attempting to extinguish the fire with sample composition No. 3, it was noted that cooling of the fire site practically did not occur (the temperature in the fire site, recorded by a thermocouple, remained close to the maximum values ​​during the entire time the composition was supplied and after the supply was stopped);

[0122] - the use of a fire extinguisher with sample No. 1 made it possible to extinguish a model fire with lithium-ion batteries;

[0123] - after extinguishing with sample composition No. 1 for 30 minutes, no signs of re-ignition were detected, the source cooled to a temperature of 40 °C, and when dismantling the model source, a large number (approximately 1 / 3) of unburned LIB elements were found.

[0124] Example 8

[0125] A model fire site according to Example 7 using a fire extinguishing composition based on a mixture of water and ethyl cellosolve (95:5) - 80 wt. %, a mixture of ammonium sulfate and diammonium phosphate (1:2) - 16 wt. %, anhydrous zinc chloride - 2 wt. %, non-ionic surfactant polysorbate-80 - 1 wt. %, aminoacetic acid - 1 wt. %. The specified composition has an increased fire extinguishing capacity with respect to class A fires compared to Examples 1-7 due to the use of a combination of ammonium sulfates and phosphates in the composition. The use of ethyl cellosolve and surfactants provides good penetrating ability, which ensures a high extinguishing rate, and the use of an inhibitor of zinc chloride and aminoacetic acid ensures passivation of active burning metals in a safe mode. The fire was extinguished when the maximum temperature reached over 800°C using a 5-liter pressure fire extinguisher, using a spray nozzle. The extinguishing time was less than 1 minute. More than half of the batteries remained intact.

[0126] The examples provided demonstrate that the claimed liquid fire extinguishing compositions, when delivered to the combustion zone in sufficient quantities for the specified (calculated) fire load, can extinguish even actively burning battery cells, preventing further thermal runaway and ignition of adjacent cells. Furthermore, the absence of combustion in cells with damaged casings (due to the release of aerosol and gases formed during electrolyte decomposition) indicates that not only the batteries are cooled, but also the combustible mixture is inhibited, preventing re-ignition.

[0127] The industrial applicability of the claimed invention lies in the fact that the developed liquid fire extinguishing agent can be implemented in any suitable delivery devices (fire extinguishers, modules, self-acting containers or capsules, when fed from a reservoir) for extinguishing lithium-containing batteries during their production, operation, maintenance, and disposal. This ensures the fire safety of any lithium-containing batteries, and the claimed solution can be used to create a primary or backup fire suppression system.

[0128] [1] Kharlamenkov A. S. - Modern methods of extinguishing lithium-ion batteries. Part 1. / / Fire and explosion safety / 2023. Vol. 32. No. 1. P. 89-96;

[0129] [2] O. Willstrand, R. Bisshop, R. Blomqvist, A. Temple, J.AAnderson / Toxic gases from electric vehicle fires / / RISE Research Institutes of Sweden, Division Safety and Transport Boras -2020, Sweden;

[0130] [3] J. Chen, F. Gao, X. Li, K. Yang, S. Wang and R. Yang / The Study of the Toxicity of the Gas Released on Lithium Ion Battery during Combustion / / 2nd International Conference on Automation, Mechanical and Electrical Engineering (AMEE 2017), Atlantis Press: Adv. Engineering, Vol. 87 - 2017;

[0131] [4] Wei-tao LUO et al. / Research and Development of Fire Extinguishing Technology for Power Lithium Batteries / / Procedia Engineering 211 - 2018, pp. 531-537.

[0132] [5] Shuai Yuan, Chongye Chang, Shuaishuai Yan, Pan Zhou, Xinming Qian, Mengqi Yuan, Kai Liu / А review of fire-extinguishing agent on suppressing lithium-ion batteries fire / / Journal of Energy Chemistry, Vol. 62 - 2021, pp. 262-280.

Claims

CLAUSES OF THE INVENTION 1. A liquid fire extinguishing composition on a water-alcohol basis for extinguishing fires of lithium-containing batteries or pure alkali metals, including a water-alcohol mixture (Component-1), at least one inorganic and / or at least one organic salt of alkali and / or alkaline earth metals and / or ammonium and / or aluminum (Component-2), at least one inorganic and / or at least one organic salt of transition metals (Component-3) in the following ratio, in mass %: Component- 1 - 40-90, Component-2 - 2-35, Component-3 - 2-25, The boiling point of the composition is at least 100 °C and the composition does not contain fluorine-containing substances.

2. The composition according to item 1, which additionally contains saturated carboxylic acids with a number of carbon atoms from 2 to 6 inclusive in an amount of 0.5-6 wt.%.

3. A composition according to any one of paragraphs 1-2, which additionally contains surfactants soluble in water and / or alcohols in an amount of no more than 15% by weight.

4. A composition according to any of paragraphs 1-3, in which the specific heat capacity of the composition is at least 2500 J / kg*K.

5. A composition according to any one of paragraphs 1-4, which contains substances that include chlorine in the form exclusively of chloride ion.

6. A composition according to any of paragraphs 1-5, which is a homogeneous liquid solution.

7. A composition according to any of paragraphs 1-6, which is a liquid solution with the possibility of forming dispersed gas / liquid systems.

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