HRP20192039A2 - Fire extinguisher for lithium-ion batteries - Google Patents

Abstract

The present invention relates to a fire extinguisher for extinguishing lithium-ion batteries (LIB) consisting of a tank (20) filled with extinguishing agent (60) and a propellant gas, wherein the tank (20) is additionally equipped with an activation mechanism (10) for activating of the fire extinguisher, by a nozzle (50) located either as a continuation of the activation mechanism (10) or previously attached to the connecting pipe (40) which is attached to said activation mechanism (10). A special feature of the present invention is the fact that an atomizer (30) made in the form of a rotor with an excitation tube is used to atomize the extinguishing agent (60). One or more gels selected from the group consisting of Hydrex®, Prevento® or Firesorb® are used as extinguishing agents, optionally, with additives that further neutralize the calcium-based LIB combustion products. These additives are calcium compounds selected from the group consisting of CaCl <SUB> 2 </SUB> or Ca (OH) <SUB> 2 </SUB> s of 1-40 weight percent of said compounds in aqueous solution.The present invention relates to a fire extinguisher for a lithium-ion battery (LIB) consisting of a container (20) filled with extinguishing agent (60) and a propellant gas, where the container (20) is further equipped with an actuation mechanism (10) for actuation a fire extinguisher , by means of a nozzle (50) provided either as an extension of the actuation mechanism (10) or previously attached to a connecting tube (40) that is attached to said actuation mechanism (10). A feature of the present invention is the fact that an atomizer (30) in the form of a rotor with an excitation tube is used to atomize the extinguishing agent (60). One or more gels selected from the group consisting of Hydrex®, Prevento® or Firesorb®, optionally, with additives that further neutralize calcium-based LIB products are used as the extinguishing agent. These additives are calcium compounds selected from the group CaCl <SUB> 2 </SUB> or Ca (OH) <SUB> 2 </SUB> with a 1-40 weight percent of said compounds in aqueous solution.

Description

The field of technology

The technical field of the present invention relates to special application fire extinguishers, specifically to appliances used for extinguishing lithium-ion batteries; hereinafter (Li-Ion batteries or LIB). By LIB we mean standard Li-Ion batteries and advanced lithium-polymer batteries, for the development of which the Nobel Prize in Chemistry was awarded in 2019.

Technical problem

LIBs, especially of the polymer type, today represent a technical solution without which we cannot imagine the functioning of the world as we know it. They are found in mobile phones, laptops, and more recently in electric vehicles from electric scooters and bicycles to electric vehicles such as cars, trucks and transport vehicles used in logistics such as forklifts in warehouses and autonomous robotic vehicles.

The failure of batteries, especially the accidental type, is associated with the development of heat due to a large amount of chemical energy that is released in a very short time and is converted into electrical energy in an electrochemical process. This happens most often in the case of a short circuit of one of the cells, structural damage or another type of scheduling. When charging batteries, smoke particles, waste leaves or snowflakes, various aerosols, liquid phases, droplets in the form of fog are released, with a preliminary note that the accident site is extremely hot. However, the biggest problem is the fact that the released material is extremely reactive, that it likes to settle on all surrounding surfaces and that it is very dangerous for human health due to its chemical composition. To understand the problem, it should be emphasized that all LIBs use lithium hexafluorophosphate (LiPF6) as the conducting salt. In case of battery damage, or so-called thermal runaway, which occurs when heat generation in the LIB goes out of control; see reference 1):

1) John T. Warner, in Lithium-Ion Battery Chemistries, 2019; chapter 3.9.3 Thermal runaway; available in e-form:

https://www.sciencedirect.com/topics/chemistry/thermal-runaway

said conductive salt decomposes into reactive toxic components. In terms of a deeper understanding of the technical problem, it is good to look at reference 2) below:

2) Hui Yang and others: "Thermal Stability of LiPF6 Salt and Li-ion Battery Electrolytes Containing LiPF6"; Lawrence Berkeley National Laboratory (University of California) 2006 Paper LBNL-58758

https://escholarship.org/uc/item/7j3826wj

which states that decomposition occurs at a temperature of about 110°C, whereby PF3 (phosphorus trifluoride), PF5 (phosphorus pentafluoride), HF (hydrogen fluoride), also known as hydrofluoric acid and POF3 phosphoryl fluoride or phosphorous oxyfluoride, are developed in contact with moisture. Furthermore, other corrosive and toxic substances containing phosphorus/oxygen/fluorine can be produced in the mentioned process. The chemistry of the decomposition of LiPF6 without the presence of water and at temperatures higher than 100°C is shown by the following set of reactions, where the symbol "g" denotes the gas phase (eng. gas) and the symbol "s" the solid phase (eng. solid)

LiPF6 → LiF(g) + PF5(g)

In the presence of moisture or water, the hydrolysis of LiPF6 takes place as described below:

LiPF6 + 2H20 → LiOH(s) + POF3(g) + 3HF(g)

The following hydrolysis procedures should also be kept in mind:

PF5 + H20 → POF3 + 2HF

POF3 + 3H20 → H3PO4 + 3HF

The above clearly shows that phosphorus oxyfluoride, which is formed as an intermediate, eventually turns into extremely reactive HF in the reaction with water or moisture from the atmosphere.

Knowing the technical problems of LIBs mentioned above, the testing and use of batteries is related to the circuit that prevents the occurrence of thermal runaway. However, there are situations when it is practically impossible to avoid, for example in the case of an electric vehicle collision, the question remains of the functionality of the control electronics and the degree of mechanical damage to the batteries - for example, mechanical breakdown of the cells. Furthermore, a problem can arise during storage and transport of LIBs if thermal runaway occurs in some of the batteries or cells.

According to the knowledge of the inventor, to date there are no reliable fire extinguishers for extinguishing lithium-ion batteries on the market that would enable a significant reduction of the components that arise in accidental situations with LIB.

The first technical problem immediately arises is the choice of an extinguishing agent that is suitable for LIB and possible additives that modulate such an extinguishing agent.

Another technical problem is solving the problem of dispersing such an agent on the LIB, considering the fact that standard fire-fighting agents are not able to act in a simple way together with gels.

Some of the possible solutions to the first technical problem are shown in reference 3) below:

3) EP2461872B1, adopted patent entitled: METHOD FOR FIGHTING AND/OR PREVENTING FIRES IN LITHIUM ION CELLS AND LITHIUM ION POLYMER CELLS; inventors T. WOEHRLE and others; rights holders Samsung SDI Co. (Korea) and Robert Bosch GmbH (Germany)

where the application of various gels such as Hydrex®, Prevento®, Firesorb® as a base fire extinguishing agent is discussed. Calcium salt, chosen from CaCl2 or calcium hydroxide Ca(OH)2, is added to these fire extinguishing bases; preferably as 20% wt./vol. aqueous solution with the addition of some of the gels selected above.

For the dispersion of the mixture from reference 3) in the subject invention, the technical solution described in reference 4) below was used:

4) EP2523733B1, adopted EP patent for the invention: APPARATUS FOR REGULATING TWO-PHASE FLOW AND PORTABLE ATOMIZER BASED ON TWO-PHASE FLOW; inventors J. Klimkowski and others; rights holder Telesto (Poland).

which is available commercially under the trademark Telesto®. Reference 4) discloses an atomizer with a mixing chamber to mix the liquid phase and the gas phase (propellant) under pressure to obtain the finest possible droplets of extinguishing agent mist, and to increase the active surface area.

No less important part is the nozzle of the same manufacturer, which is used together with the atomizer from reference 4), here it is listed below as reference 5)

5) Registered RCD before EUIPO; number 001714544-0002, design name: Nozzles [for fluid distribution]; rights holder Telesto (Poland).

https://euipo.europa.eu/eSearch/#details/designs/001714544-0002

The present invention uses the synergy of technical solutions from references 3), 4) and 5) in order to obtain a highly functional and efficient apparatus for extinguishing initial LIB fires; especially applicable in electric vehicles, of which there are more and more every day on the roads and LIB warehouses.

The essence of invention

The subject invention discloses a lithium-ion battery (LIB) fire extinguisher. It consists of a container filled with extinguishing agent and pressure gas. The tank is additionally equipped with an activation mechanism for activating the fire extinguisher, with a nozzle that is designed either as a continuation of the activation mechanism or attached to a connecting pipe that is attached to the mentioned activation mechanism on the opposite side. The special feature of this device is reflected in the fact that an atomizer designed in the form of a rotor with an exciting tube is used to atomize the extinguishing agent. As an extinguishing agent, one or more gels are used, optionally, with additives that additionally neutralize LIB combustion products and are based on calcium.

A gel from the group consisting of: Hydrex®, Prevento® or Firesorb® was chosen as the preferred extinguishing agent. As an optional addition, a compound selected from the group CaCl2 or Ca(OH)2 can be used with 1-40 weight percent of the mentioned compounds in an aqueous solution that is added to the already mentioned gel.

Nitrogen (N2) is preferably used as the propellant gas in the present invention. The invention is intended for extinguishing fires caused by ordinary LIB and Li-polymer LIB in vehicles and LIB warehouses.

Description of the drawing

The subject invention is described by drawing 1, which shows the components of the fire extinguisher according to the subject invention. The references used in the drawing are:

10 - activation mechanism

20 - container

30 - atomizer made with a rotor with an exciting tube

40 - connecting pipe

50 - nozzle

60 - extinguishing agent

Detailed description of the invention

The subject invention is described in drawing 1. The structural fire extinguisher for extinguishing lithium-ion batteries (LIB) externally resembles any other similar fire extinguisher. It consists of a container (20) filled with an extinguishing agent (60) with a pressure gas, preferably in the form of an inert and cheap gas such as nitrogen (N2). After the extinguishing agent (60) is placed in the tank (20) itself, the propellant - pressurized nitrogen is pressurized to a pressure of approximately 15 bar.

The container itself (20) is additionally equipped with an activation mechanism (10) for activating the fire extinguisher with a safety brake or a belt, the functioning of which is well known in the state of the art. The activation mechanism (10) is a mechanism where a spring-supported axial valve is released with a lever, which ejects the contents of the tank (20) under pressure, but after the atomization phase. A nozzle (50) can be placed directly on the activation mechanism (10) in one variant according to the invention. In another variant according to the invention, the connecting pipe (40) is connected to the activation mechanism (10) on one side and to the nozzle (50) on the other end, as shown in drawing 1.

The nozzle (50) is designed as the so-called water-mist nozzle at the end of the connecting pipe (40) and the nozzle (50) enables the creation of a mist, which contributes to increasing the active surface of the means with which the fuel substance is covered; in our case LIB. A suitable nozzle is the one from reference 5), but nozzles with similar characteristics from the state of the art can also be used.

The characteristic of the present invention is the use of an atomizer (30) made in the form of a rotor with an excitation tube by the company Telesto® and patented as EP2523733B1, see reference 4) of the state of the art. The role of the atomizer itself (30) is multiple. The rotation of its rotor reduces the pressure difference between the tank (20) and the environment, which is significant and greater than 10 bar, which prevents the escape of the propellant and the reliable emptying of the tank (20) to the end of the used fire extinguishing mixture.

Another important role is the creation of a mist consisting of the used gel and nitrogen, which provides a larger active surface that extinguishes the flame and thus more efficient work.

In the present invention, all suitable state-of-the-art gels can be used as gels, especially: Hydrex®, Prevento® or Firesorb® gels from renowned manufacturers. It should be said that such and similar preparations are well described in use as gel fire extinguishing agents in the following references:

6) US 3,229,769 adopted US patent for the invention: METHOD FOR CONTROLLING THE SPREAD OF FIRE; inventor R.N. Bashaw and others; rights holder DOW CHEMICAL Co.;

7) EP1817086B1 adopted European patent for the invention: FIRE EXTINGUISHING AND/OR FIRE-RETARDANT COMPOSITIONS; inventor M. Beck and others; rights holder BASF which discloses the product Prevento®

Hydrex® is a product of ÖKO-TEC Umweltschutzsysteme GmbH from Germany. Product information can be found at the link below:

8) https://oeko-tec.de/wp-content/uploads/2018/10/oeko_tec_hydrex_englisch.pdf

Hydrex® is a fire extinguishing agent similar to the aforementioned Prevento® or Firesorb®. It is a gel that is supplied in powder form and is mixed before use. Hydrex® was the first such product on the market; it is mixed in a quantity of approximately 1% in 10 liters and forms a gelatinous liquid of high heat capacity in a short time; hence the ability to absorb heat from the environment. Basically, these are water-absorbing polymers (hydrogels) such as sodium polyacrylate, potassium polyacrylate, superabsorbent polymer, etc.; which are well-known ingredients from the state of the art.

Prevento® is an innovative extinguishing agent from BASF, see reference 7). It consists of 1% w/w water absorbent polymer, 1.1% w/w trisodium citrate, 0.2% w/w xanthan, 0.12% w/w polyethylene glycol and 0.2% w/w biocide that enables the stability of the mixture.

Firesorb® is a product manufactured by Evonik (formerly Degusa); and product information can be found in reference 9)

9) http://www.bushencroachment.com/uploads/5/4/4/9/5449109/msds_firesorb_mo.pdf

According to the above reference, the product consists of sodium acrylate/acrylamide - copolymer and fatty acid ester as a water-in-oil emulsion. Isotridecyl polyglycol ether or polyglycol ether alone are used as solubility enhancers. As in the case of the Prevento® composition, a biocide is used, which enables the durability of the product for about 2 years.

Reference 3) describes the unexpected effect of using inorganic compounds with calcium that minimize and bind harmful compounds produced by LIB burning. It was observed that 20% wt./vol. a solution of CaCl2 in water together with a gel fire extinguishing agent results, in addition to the well-known technical fire extinguishing effect - which results from the previously listed gels - also the binding of calcium directly to fluorine. Thus, calcium ions from the aqueous solution bind very quickly with hydrofluoric acid (HF) and other fluorine compounds such as (POF3), thus forming calcium fluoride (CaF2), which is water insoluble and precipitates in situ. Alternatively, as a source of calcium ions in water, it can be Ca(OH)2 in aqueous solution, which gives the same or similar technical effect to the use of CaCl2. It is clear that the amount of Ca ions must be sufficient in the solution, and reference 3) states that a good measure is 1-40% wt./vol. solution of preferred salt CaCl2 in water, preferably 20% wt./vol.

In the state of the art, reference 3) it is also described that water-absorbing polymers are present in concentrations of 1.5% - 3% wt./vol. which, as an additional technical effect, has the retention of liquid on the burnt part of the LIB.

The fire extinguisher according to the invention in question is extremely reliable and effective for use in the event of a fire on Li-Ion batteries, LiPo (lithium polymer or lithium ion polymer) batteries, collectively known as LIB. In the aforementioned LIBs, in addition to the aforementioned conductive salt LiPF6 and other active substances, depending on the type of batteries used; eg Li2Mn2O4 (LMO), LiFePO4 (LPF), Li4Ti5O12 (LiTiO). The fire extinguisher according to the subject invention can be reliably used in cases of use of these other active substances in LIB cells as well.

This invention combines in a non-trivial way the knowledge from reference 3) which discloses the use of gels and optionally the role of calcium ions in inhibiting LIB combustion products with the knowledge from reference 4) how to produce a mist of droplets with a diameter of 0.0003 mm to 0.01 mm; preferably with a mean diameter of about 0.001 mm to 0.005 mm; where less is better, and for the sake of contact surface and heat absorption. Reference 4) is silent about the use of the mentioned atomizers for the needs of LIB extinguishing, so the mentioned combination, apart from being new, is also inventive in the state of the art.

Industrial applicability

The industrial applicability of the subject invention is undeniable. The subject invention discloses a fire extinguisher for extinguishing lithium-ion batteries (LIBs) with the technology of creating a mist from gels that retain water and additional substances that bind to the harmful products of combustion of active substances from LIB cells. The intended operating temperature range is 0°-60°C.

Claims (5)

1. Fire extinguisher for extinguishing lithium-ion batteries (LIB) consisting of a container (20) filled with an extinguishing agent (60) and pressure gas, where the container (20) is additionally equipped with an atomizer (30) and an activation mechanism (10) for activating the fire extinguisher, with a nozzle (50) for creating a water mist, which is performed either as a continuation of the activation mechanism (10) or attached to a connecting pipe (40) which is attached to the aforementioned activation mechanism (10), indicated by: - that for atomizing the extinguishing agent (60) an atomizer (30) made in the form of a rotor with an exciting tube is used, and - that one or more gels are used as an extinguishing agent, optionally, with additives that additionally neutralize the products of LIB combustion based on calcium ions. 2. Fire extinguisher according to claim 1, characterized in that the extinguishing agent (60) is a gel selected from the group consisting of: Hydrex®, Prevento® or Firesorb®. 3. Fire extinguisher according to claim 1 or 2, characterized in that the optional additive is a compound selected from the group of CaCl2 or Ca(OH)2 with from 1%-40% wt./vol. of the mentioned compounds in aqueous solution. 4. Fire extinguisher according to any of the preceding claims, characterized in that the pressure gas is nitrogen (N2). 5. The use of a fire extinguisher according to any one of claims 1-4, characterized in that it is intended to extinguish a fire caused by ordinary LIB and Li - polymer LIB.