The invention relates to extinguishing or preventing fires in electric batteries, in particular lithium ion batteries. In particular to the use of a composition for extinguishing or preventing such fires, a method for extinguishing a burning electric battery or preventing an electric battery from burning, to an electric battery that is surrounded by the composition as well as a product that comprises such a surrounded electric battery, and an assembly, comprising an electric battery and a fire extinguishing device, comprising the composition. The invention also relates to an enclosure intended to at least partially enclose an electric battery.

Batteries, in particular lithium ion batteries, have the risk of heating and burning, e.g. as a result of mechanical impact or electric short circuit within the battery. By lithium ion batteries is meant not only lithium ion batteries but also lithium polymer batteries. Lithium ion batteries are composed of very ultra thin metal films, in general aluminium and copper films, ultrathin plastic films, which above all contain notable amounts of fluorine and/or other halogens, ultra small particles of carbon as the negative electrode and ultra small (nano)particles of complex oxides and phosphates of (transition) metals, wherein lithium ions are intercalated, organic and inorganic solvents, wherein lithium compounds are dissolved, this in its entirety built into a housing of metal or plastic, or a metal-plastic combination, and provided with mechanical and electric connecting points. This construction is necessary for the achievement of the desired characteristics, but it also appears to carry exceptional behaviour in terms of fire, whereby lithium ion batteries are very difficult to extinguish.

The use of a lithium ion battery is enabled by an electronic battery management control system, usually incorporated in the battery, which control system controls, among other parameters, the voltage to prevent excess discharging, charging and disturbance of the electro-chemical balance, as a result of which internal electrochemical and/or physical damage could arise. If there is a defect or incorrect functioning of the control system then the temperature within the lithium ion battery may increase to above critical levels and a sudden fire can start in a battery. During a fire, such batteries may form gasses that may contain very dangerous fluorine and there is a risk of explosion. An existing fire can also transfer to a lithium ion battery. As electric batteries are commonly arranged in the form of a plurality of connected battery cells, a temperature increase in a single battery cell may not only lead to a fire within the said cell, but can also result in neighbouring battery cells to burn. Herein, a battery cell is intended to mean a single battery cell, that can electrically be connected in series or in parallel, to one or more other electric battery cells, therewith forming a so-called 'battery pack'.

Due to not only the risk of explosion, a burning battery, in particular a burning lithium ion battery presents a big risk; there is currently no appropriate solution to extinguish such a burning battery or to prevent such a battery from burning. Lithium ion batteries are used in increasing quantities in all sorts and types of consumer electronics and in batteries for vehicles for example bicycles, electric cars, aircrafts and boats and in integrated energy systems where there is a urgent need for an extinguisher system that is able to efficiently extinguish burning lithium ion batteries. Especially in the field of electric vehicles the risk is large, because the majority of such vehicles are also equipped with a fuel tank filled with highly flammable fossil fuel. In event of an accident involving such a vehicle the chance that a fire will transfer to the lithium ion battery is very large.

For the extinguishing of fires such extinguishing means as water, sand, powder, foam, carbon dioxide, chemical extinguishing agents and extinguishing aerosols are used. One also makes use of fire blankets in order to completely cover fires.

Commonly used extinguishing means are not appropriately suitable for extinguishing electric battery fires, in particular lithium ion battery fires. Water cools and suffocates the fire and reduces the flammability of a material. Water is however not suitable in the presence of electricity. Foam forms a fire suffocating layer on the burning and burnable material, but is also not suitable for use in the presence of electricity. Carbon dioxide and sand suffocate fire by means of removing oxygen. Carbon dioxide is used by for example in the burning of electric apparatus. Powder extinguishing means are also used to extinguish electric apparatus which is live. Chemical extinguishing means, such as halomethane form free halogen radicals in the burning process which free radicals slow down the burning. Although these chemical means are suitable for by example use in computer rooms these chemical means are often banned due to the large scale environmental damage caused by the use thereof. Aerosol extinguishing systems use a dry aerosol, which undergoes a chemical and physical reaction with reactive molecules formed in the fire. The aerosol contains potassium compounds which reacts with large quantities of oxygen when they come into contact with the air whereby potassium oxide and/or potassium hydroxide is formed. By removing the oxygen the fire is extinguished.

The above-mentioned fire extinguishing systems are however not suitable for example in battery fires, in particular a so-called lithium ion batteries. WO2012/107382 describes a composition for extinguishing fires of lithium ion batteries, in particular in order to neutralize the developing fluorine gases therefrom. To this end, swellable polymers, such as hydrogels are provided, that comprise alkaline earth metal ions such as calcium, that are capable of binding with the fluorine gases to form insoluble fluorides such as CaFI ₂ . The water contained in the polymer allegedly cools the fire. However, such compositions are only suitable once a fire has developed, and are not suitable in both fire prevention and extinguishing once a fire actually started.

In order to at least provide a partial solution to the aforementioned problems, the present inventors have now found that a composition can be used for both extinguishing electric battery fires as well as for preventing said batteries from burning, said composition comprising a medium wherein at least one material contained which becomes vitrified at a temperature above 200°C.

By heating such materials a hard glassy substance develops, this process is described in as 'vitrifying'. The present invention makes use of this characteristic and surprisingly it has been shown that when a composition according to the invention is used on a burning electric battery, e.g. by spraying or nebulizing on to the object for example by using existing fire extinguishing apparatus, the vitrifiable material in the composition causes the composition to vitrify due to the heat of the fire. This vitrification takes place in a very short time whereby a hard glassy layer is formed on the burning object, whereby contact with oxygen in the air is prevented whereby the fire is extinguished and does not flare up again once the spraying or dowsing is stopped. This is in particular the case when applied to lithium ion batteries, for which there has been up until now no suitable fire extinguishing means. The composition is preferably brought in contact with the battery such, that after virtrification thereof, the said battery is at least partially encapsulated by the glassy material. The same is true in situations where the temperature of the battery, e.g. due to internal damage or electric shortcut, increases. When the temperature of the said electric battery reaches or increases to above the temperature at which the vitrifiable material of the composition becomes vitrified, the composition can be used on such a battery, resulting in the said battery becoming encased by the above- described glassy substance, therewith preventing a fire to develop in the said and neighbouring battery cells.

With the words "material which is vitrified at a temperature above 200°C" is meant that the material becomes glassy at a temperature in region above 200°C. It is not meant that the material already becomes glass or is vitrified below said temperature of 200°C, but only at a higher temperature. Therefore the material can also be vitrified above 300°C, 400°C, 500°C, 600°C, 700°C, 800°C or higher. The material is in any case vitrified at a temperature of the fire to be extinguished. This material is also referred to herein by 'vitrifiable material'. As the said vitrifiable material is a constituent of the composition used to extinguish or prevent electric battery fire according to the invention, the composition as a whole will preferably vitrify once the said temperature is reached or exceeded. The use according to the invention is therefore in particular before vitrification, i.e. gelling of the material and the composition. The vitrifiable material is contained in a medium, e.g. a solvent such as water. Said medium can also comprise e.g. matrix components as will be discussed below. The composition comprises the said medium and the virtrifiable material contained therein.

According to the invention, the composition is preferably used when it is pumpable, in order to be suitable therefore to be sprayed on to a fire or battery with elevated temperature using existing fire extinguishing apparatus.

Preferably the medium therefore comprises a solvent in which the vitrifiable material is dissolved. The material can e.g. be contained in the medium as a solution, but also as a dispersion in a carrier liquid, for example. Also the medium can be, for example, a solution or a dispersion or similar, and can comprise a viscosity increasing matrix, such as for example a gel or a matrix with other desirable rheological properties in order to provide alternative means by which the vitrifiable material can be brought into contact with the envisaged electric battery to be encapsulated. As soon as such a composition is heated, such as by the heat of the battery, by the heat of the battery once burning or by burning surroundings then this material will be cured (vitrified) to an impermeable glassy layer. The solution is preferably a solution, more preferably an aqueous solution.. The vitrifiable material is preferably chosen from the group consisting of alkali metal silicates, earth alkali metal silicates, boron compounds and silicone resins, which are able to form a glass layer on heating. As such, aqueous silicate compositions are known to be used to extinguish fires such as bush fires (FR2361920). The use of aqueous gels comprising neutralized silicate for extinguishing fires are known from GB1349508 and FR2078186. These compositions however cure spontaneously, i.e. at ambient temperature, whereas the compositions as used according to the present invention vitrify only at or above 200°C, and are preferably stable in not-vitrified form, such as in the form of a liquid or (aqueous) gel at operating conditions of the battery.. WO97/20600 describes silicate containing aqueous solutions comprising sodium or potassium salts and ethylene glycol, that have an accelerated curing time as compared to pure water glass solutions, and also gel at ambient temperatures. Such compositions are described to be used for isolating soil pollutions, but also for extinguishing tire fires. A composition as used according to the invention however, can very well be an aqueous waterglass solution, without additional components, and therefor does not need to have incorporated therein additional salts such as sodium or potassium bicarbonates, halogens, sulphates and the like, that would rather facilitate spontaneous curing at ambient temperatures instead of preventing the composition from curing below 100°C or 200°C or higher, as is the case for the compositions used according to the present invention.. The composition as used according to the present invention can therefore very well be a single component composition, i.e. comprising the vitrifyable material in a medium such as water.without the need to be mixed with other components, solutions and the like that would e.g. influence the curing properties of the vitrifyable material in an undesired manner as described above, before being usable to spray or otherwise apply on electric batteries to extinguish or prevent fires.

The vitrifiable material in the medium of the composition as used according to the invention comprises preferably a silicate of a alkali metal (M). Solutions of such silicates are also known as waterglass. The most common silicate solutions are those of sodium silicates, potassium silicates and mixtures thereof. There are however other suitable silicate solutions of other alkaline metals such as lithium silicate.

Such silicates are defined above all on the basis of the weight ratio between Si0 ₂ : M ₂ 0, whereby M stands for an alkali metal. The ratio preferably varies from about 4: 1 to about 1 :4, more preferably from about 4 : 1 to about 1 : 1 , even more preferably from about 3.75 : 1 to about 2 : 1 , preferably using industrially applied sodium waterglass. At a ratio under 2.85 : 1 the waterglass is known as alkaline, above that ratio "neutral". An alkaline silicate means that an alkaline solution is formed on the solution in water. Examples of such alkaline sodium silicates are sodiumorthosilicate Na ₂ Si0 ₄ (having a Si0 ₂ : Na ₂ 0 ratio of 1 : 2), sodiumpyrosilicate, Na ₆ Si ₂ 0 ₇ (having a Si0 ₂ : Na ₂ 0 ratio of 1 : 1 .5), Na ₂ Si0 ₃ , Na ₂ Si ₃ 0 ₇ , and Na ₂ Si ₄ 0 ₉ .

Although other alkaline metals may be suitable, the silicate is preferably chosen from the group of sodium silicate, potassium silicate and lithium silicate or a combination of two or more thereof, preferably sodium or potassium silicate or a combination thereof. The composition which comprises the most preferred choice comprises a solution of sodium silicate.

The weight ratio of silicon oxide with respect to alkali metal oxide Si0 ₂ : M ₂ 0 is preferably 3.75 - 2 : 1 , more preferably 3.75 - 2.85 : 1 and even more preferably 3.5 - 3.3 : 1 .

The content of the vitrifiable material, silicate as described above, in the composition is required to be sufficient in order to extinguish or prevent the fire by forming a sufficiently thick glassy layer. The skilled person is able to determine in a simple way the correct concentration. In such a way one can apply a high concentration where relatively little composition is necessary to form a glassy layer. When one uses the composition in a more diluted solution one must apply relatively more fire extinguishing means.

In an embodiment of the invention the Si0 ₂ content in the composition is preferably 25 - 35 wt.%, more preferably 27 - 31 wt.%. however, the Si0 ₂ content can also be 13 wt.% or more, or 15 wt.% ore more or 18 wt.% or more. The desired viscosity can be adjusted by the final content of Si0 ₂ .

The composition, when used according to the invention, preferably comprises a filler. Inclusion of a filler has the consequence that less sodium silicate needs to be applied to create the same effect. The filler is included in the glass layer during vitrification and is thus also important for determining the volume and therefore the thickness of the applied layer. The filler is preferably fire resistant in order to further increase the fire resistant effects of the composition. The filler is therefore preferably chosen from the group consisting of sand, silt, clay minerals, types of quartz, pegmatites, and glass granules. The filler is preferably a clay mineral, belonging to the smectic group, preferably a phylosilicate, and most preferably a vermiculite. Vermiculite is a commonly available mineral and is a phylosilicate that belongs to the group of smectics within the group of clay minerals, and has a high fire resistant content. As such vermiculite is already used in fire safety of flammable materials, including lithium ion batteries. These batteries are stored embedded in vermiculite containing beads in order to quickly extinguish a fire.

It should be noted that a fire resistant composition that contains silicate and vermiculites is described in US 4689249. Such a composition is painted onto an object whereby this object gains fire resistant characteristics. Application of such a composition as a fire prevention or extinguisher composition, that means applying the composition in liquid form to an already burning electric battery, or battery about to burn, on in order to surround the said battery in glass is not disclosed by this American patent.

The skilled person is able to determine a suitable amount of filler to be used in the composition. Thereby he will also consider the possible size of the granules of filler. Accordingly he knows that the quantity and granule size of the filler van have an influence on the viscosity and on the pumpability of the composition. By means of an example when fine or superfine vermiculite (with an average granule size of 0 - 3.0 mm and 0 - 1 .5 mm respectively) are used in a composition as used according to the invention in an amount up to 20 wt.%, this composition remains pumpable. Also higher amounts are possible. Preferably the amount of vermiculite is 5 - 20 wt.%, more preferably 8 - 15 wt.% and even more preferably 9 - 12 wt.%.

Other additives can be included in the composition as used according to the invention, which materials form a polymer together with the vitrifiable material such as water glass, via which an improved vitrification can be obtained. It is however to be noted that vitrification will only take place above the envisaged threshold temperature, in case of e.g. short circuits as explained above, or in case of fire, lying significantly above the operating temperature of the battery, such as a temperature of 200°C of higher. Besides for example sodium aluminates the skilled person knows such materials and he will use these in the correct quantity.

In a special embodiment the medium of the composition as used according to the invention comprises a carrier material or a matrix forming material, wherein the vitrifiable material is contained, for example in order to adjust the rheological characteristics of the composition according to the specific application. For a thin fluid composition is as a rule no carrier material needed. When one wishes to produce a more viscous or syrupy composition, for example with an improved binding to the burning battery material then the medium can contain a carrier material.

The matrix forming material can for example be a gel-like or gel- forming material, which forms a gel matrix wherein the vitrifiable material is contained. The gel can be viscous, highly viscous or indeed solid-like, according to the desired application. A solid-like gel can for example be placed on a burning object. The gel will form a glass layer due to the heat produced by the fire.

The vitrifiable material and therefore the composition as used according to the invention is vitrified preferably at a temperature above 200°C, for example above 300°C, 400°C, 500°C, 600°C, 700°C, and 800°C.

The invention also relates to a method for extinguishing a burning electric battery or preventing an electric battery from burning, comprising applying a composition as defined above to the electric battery when burning or when reaching or exceeding the temperature at which the material contained in the medium of the composition becomes vitrified, method for extinguishing of a burning object whereby the composition according to the invention is applied to the burning object, preferably by spraying or nebulizing the composition from a fluid form, preferably a liquid form.. The method further preferably comprises the step of allowing the material to vitrify, therewith at least partially encapsulating the electric battery. The composition is preferably applied to the electric battery by spraying or nebulizing the composition in fluid form, preferably in liquid form. The electric battery is preferably a lithium ion battery.

The invention also relates to an electric battery protected from fire that is at least partly enclosed by a composition as described above. When the temperature of such a battery increases to above the temperature at which the vitrifiable material and therefore preferably the composition as a whole vitrifies, or even starts to burn, the surrounding casing is heated whereby the composition forms a glassy layer on the burning battery, whereby the fire is prevented, or is extinguished due to a lack of oxygen. The casing is preferably at least partially of such type that on heating the casing around the battery becomes fluid and/or permeable for the composition contained therein, allowing a glassy layer to formaround the battery.

The composition is preferably contained in a substantially closed space next to the object, so that the composition can not escape and is at all times close to the object. The composition can therefore be in a fluid, preferably liquid form but also in a gel or in another sense bound form in order to be present on the battery, so that when the temperature of the battery increases to or beyond the temperature at which the composition vitrifies, vitrification of the composition takes place. To achieve this, the composition is preferably included in a stable state in order to ensure a long storage thereof and thereby guarantee that the composition is vitrified, preferably, by increasing the temperature to above 200°C or one of the aforementioned temperatures.

In a particular embodiment the electric battery according to the invention is contained in a housing, which housing comprises a composition according to the invention. If fire breaks out in the battery, or when the temperature thereof increases, or if a fire begins in the area around the object, the composition which is present in the housing will form a glassy layer whereby the battery will at least be partially covered. If the fire begins from outside, the battery will set alight and if the fire begins on the inside then this fire will be extinguished by the forming of a glassy layer.

In an advantageous embodiment the medium comprises a matrix forming material wherein the vitrifying material is contained. In an advantageous embodiment the matrix forming material is a gel in the composition as used according to the invention. Therefore one can encase the electric battery with for example gel plates which although do not form a closed casing around the battery, on heating a glassy layer forms on the battery. The advantage of a gel compared to a liquid is that there is a lower or no risk of leaking.

The invention also relates to an assembly, comprising an electric battery and a fire extinguishing device, the said fire extinguishing device comprising detection means detecting a fire or a temperature increase, at least one spraying nozzle and a container accommodating the composition as above, designed such, that in case of fire or temperature increase above a predetermined threshold temperature, the composition is delivered from the container via the spraying nozzle onto the electric battery. Such an assembly can be regarded as a stationary fire extinguishing system, that automatically extinguishes a battery fire or prevents such a fire when the temperature of the battery rises to critical temperatures. Such a device, or at least one or more spraying nozzles thereof, are placed in proximity of an installed battery. Such a device can e.g. be designed as a so-called sprinkler installation, in case of fire being actuated manually or automatically, as a result of which the composition as described above is delivered via the spraying nozzle onto the electric battery where the spraying nozzle is located. A vehicle can thus be provided with such a fire extinguisher device, which e.g. when a fire is detected, such as by the aid of a fire sensor cooperating with or contained in the fire extinguisher device, sprays the composition as described above in the direction of the battery. Accordingly, such a fire extinguishing device can be placed in a car or an aircraft. Suitable detecting means are known in the art. Such detecting means may comprise a sensor, allowing the system to spray the composition after a fire, temperature increase, gas or smoke or an impact that is higher than the maximum breaking deceleration, has been detected. The threshold temperature is preferably 100°C or higher, more preferably 200°C or higher. In particular, the threshold temperature equals or is higher than the temperature at which the material contained in the medium of the composition vitrifies. When the battery reaches such a threshold temperature, the assembly will apply the composition onto the electric battery, or battery pack, the composition will vitrify and the fire will extinguish or be prevented.

The invention also relates to a product that comprises an electric battery or assembly according to the invention. This means that the product comprises a battery that may be partly or completely encased by the composition according to the invention, or comprises an electric battery in combination with a stationary extinguishing device as described above. Preferably the battery is a lithium ion battery. Such products are for example electric apparatuses which are provided with an electric battery, which battery is encased by the composition as used according to the invention or provided with a stationery extinguishing system as described above. The product can be an electronic device such as a mobile phone or a laptop, or a vehicle, for example a bicycle, a car, an aircraft or a boat, wherein the electric battery is preferably designed in order to drive the vehicle. In such products relatively powerful lithium ion batteries are commonly used, which poses an extra big risk in the case of fire for people and the environment. By encasing the said battery or batteries in the composition as used according to the invention, the chance of a serious accident in the case of fire in these batteries and therefore the product thereof, for example the vehicle or electronic apparatus is prevented. Such vehicles can also be provided with an auxiliary safety system whereby the composition is activated to initiate, in particular to accelerate vitrification when a sensor for example detects a fire, temperature increase, gas or smoke or an impact that is higher than the maximum breaking deceleration (occurs during an accident), by for example quickly heating the composition with a suitable apparatus therefor, or for example by adding a catalyst which leads to accelerated vitrification.

In still another embodiment, the invention relates to an enclosure, intended to at least partially, but preferably fully enclose an electric battery. Said enclosure, such as a pouch, casing or box, comprises the composition as used in the present invention. In an attractive embodiment, the battery is a lithium ion battery. In a special embodiment, the casing can be designed as double-walled pouch, casing or box, between the walls of which the composition as defined above is contained. Accordingly, one or more electric batteries can be placed in the pouch, casing or box in case of fire or as precaution. In case of fire, the composition will vitrify, and the fire will be extinguished. It is also possible to keep objects in such an enclosure as a precautionary measure, e.g. during high-risk events. Accordingly, e.g. mobile phones or laptops can be kept in such an enclosure during the flight of an airplane, . It is also possible, during such events, to have the enclosures readily available to enwrap the object or to put the object in the enclosure in case of fire. The same is valid for instruments that are fed by e.g. lithium ion batteries, such as in the cockpit of an airplane.

Under conditions without fire, the walls of the enclosure are preferably impermeable for the composition, in order to avoid leaking of the composition from the enclosure and unintended contacting with the object present therein, or with the user of such an enclosure. Preferably, at least the inner wall of the enclosure becomes permeable for the composition of the invention at elevated temperatures, for example because the said wall would melt or tear or open otherwise at these elevated temperatures of e.g. 100°C or 200°C or higher. In case of fire, the composition is contacted with the burning object in the enclosure in a fast manner, whereafter the composition vitrifies and the fire is extinguished. The skilled person is aware of such materials, such as suitable plastics or textile materials. Such an enclosure also protects against e.g. explosion of the batteries of an encased object when the fire comes from the outside.

The invention shall further be explained by means of a number of examples, without limiting the said invention.

Example 1A: Liquid composition

PQ Corporation Crystal 0075 CAS 1344-09-0 El N ECS 2156874

Si02 3.3/3.5 Na20

Viscosity at 20°C 100-200 cp (0.1 -0.2 Pa.s)

density 1 .36-1 .38 g/cm3

Si02 content: 27.5-28.8 wt.%

Na20 content: 8.1 -8.5 wt.%

in water. Example 1 B: Composition in highly viscous form

PQ Corporation Crystal 0079 CAS 1344-09-8 El N ECS 2156874

Si02 3.3/3.5 Na20

Viscosity at 20°C 200-10.000 cp (0.2-10 Pa.s)

density 1 .38-1 .41

Si02 content: 28.5-30 wt.%

Na20 content: 8.5-9.0 wt.%

in water.

Example 1 C: Liquid composition

PQ Corporation Crystal 0075 CAS 1344-09-0 El N ECS 2156874

Si02 3.3/3.5 Na20

Viscosity at 20°C 100-200 cp (0.1 -0.2 Pa.s)

density 1 .36-1 .38 g/cm3

Si02 content: 27.5-28.8 wt.%

Na20 content: 8.1 -8.5 wt.%

Vermiculite (NVM Products B.V. , Amsterdam, Holland) 10 wt.%

in water.

Example 2A: Extinguishing of lithium ion batteries In a steel container with wall measurements of 100 x 100 x 20 cm seven lithium ion batteries were fixed to each other with sticky tape and placed on a grill, the lithium ion batteries were of the type 18650 (diameter 18 mm, height 65 mm) originating from a battery of an electric bike, the model of bike being Bionix Protarion, the batteries were heated with a Camping Gaz SOU DOGAZ X2000 solder burner. After 3 minutes fire brook out in the batteries by breaking open a cell, where after the burner was removed and the fire spread further to the other cells. After a further minute burning by itself the composition according to Example 1A was sprinkled over the batteries for a couple of seconds using a watering can, which resulted in a thick glassy crust of water glass, whereby the fire was extinguished, without a further fire breaking out.

Example 2B: Extinguishing of lithium ion batteries

As in Example 2A, but the fire was extinguished with the composition according to Example 1 C. The fire was extinguished immediately after being sprinkled.

Comparative Example 2

In a similar experiment, whereby water was sprinkled on the burning batteries the flames were temporarily extinguished, but after a few seconds of sprinkling a fire brook out.

Example 3A: Extinguishing of a bike battery

Instead of separate cells from a R18650 type battery being bounded together a complete battery from an electric bike, model Protarium BP-L2410SH 1 (26.6 VDC; 10Ah; 266 Wh, manufactured by GWA Energy (8F.31 . LN 169 Kangning St. Sijihih, NTC, Taiwan) was placed on a grill and heated with a Camping Gaz SOUDOGAZ X2000 solder burner, where after 2 minutes the batteries broke into flames and after a further 2 minutes heating the burner was removed. The battery burned steadily further on its own, whereby ever more cells broke open and the fire spread further. After a further 2 minutes the liquid composition 1 B was sprinkled on the fire, whereafter the fire immediately was extinguished and a water glass layer formed on the battery.

Example 3B: Extinguishing of a bike battery As in Example 3A, but the fire was extinguished with the composition according to Example 1 C. The fire was extinguished immediately after being sprinkled.

Comparative Example 3

As in Example 3, but in place of a water glass comprising solution water was used as the extinguishing material. The battery broke into flames after a few seconds of being sprinkled with water.

Example 4A: Extinguishing of a note book battery

Instead of batteries of the Examples 1 and 2 a Notebook battery, made from R18650 type batteries was placed on a grill and heated with a Camping Gaz SOUDOGAZ X2000 solder burner, where after 1 minute fire broke out in the battery. The heating was continued for 2 minutes where after the burner was removed. The battery burned sturdily further on its own, whereby ever more cells broke open and the fire spread further. After a further 2 minutes the liquid composition 1A was sprinkled on the fire where after the fire immediately was extinguished by the formation of a water glass layer.

Example 4B: Extinguishing of a note book battery

As in example 4A, but the fire was extinguished with the composition according to Example 1 C. The fire was extinguished immediately after being sprinkled.

Comparative Example 4

As in Example 4, but in stead of a water glass comprising solution water was used as the fire extinguishing material. The battery broke into flames after a few seconds of being sprinkled. Example 5: Prevention of a fire

A bike battery according to Example 3 was encased with a 1 cm thick layer of viscous composition according to Example 1 B in a plastic housing. This object was set on fire by a gas burner whereby the plastic housing melted and the gel was changed into glass after first viscosity of the gel had reduced. The gel formed an encasing glass layer around the battery which did not further burn. The butane gas burner was removed after 10 minutes.