Patent Description:
In general, secondary batteries refer to chargeable and dischargeable batteries, unlike primary batteries that are not chargeable. The secondary batteries are being widely used in the high-tech electronic fields such as mobile phones, notebook computers, and camcorders.

Such a secondary battery comprises an electrode assembly, in which an electrode and a separator are alternately stacked, and a case accommodating the electrode assembly.

However, the secondary battery has a problem in that explosion or ignition occurs when high-temperature heat occurs due to overcharging, overcurrent, and physical external impacts.

<CIT> relates to a micro encapsulated fire extinguishing composition.

<CIT> discloses self-extinguishing polymeric compositions.

The present invention is invented to solve the above problems, and therefore, an object of the present invention is to provide an extinguishing composition comprising a capsule containing an extinguishing material that comprises calcium bromide (CaBr2) to effectively suppress explosion or ignition by using an air blocking effect, a method for preparing an extinguishing composition, and a secondary battery.

The present invention is to achieve the above object, and therefore, an extinguishing composition according to a first embodiment of the present invention is defined in the appended set of claims, the extinguishing composition comprises: an extinguishing material; and a capsule configured to contain the extinguishing material, wherein the extinguishing material comprises calcium bromide (CaBr2).

The capsule may be made of a thermoplastic resin, and the thermoplastic resin may be composed of an acrylate monomer or an acrylate polymer.

The acrylate monomer may comprise a polymethyl methacrylate polymer.

The extinguishing composition further comprises a dispersion layer applied to an outer circumferential surface of the capsule, wherein the dispersion layer may be made of a silicone oil material.

A method for preparing an extinguishing composition according to the present invention comprises: a capsule solution preparation step (S10) of mixing a thermoplastic resin with a solvent to prepare a capsule solution in which the thermoplastic resin is dissolved; a capsule solution coating step (S20) of adding a plurality of extinguishing materials to the capsule solution to apply the capsule solution to surfaces of the plurality of extinguishing materials; and an extinguishing composition completion step (S30) of heating the plurality of extinguishing materials coated with the capsule solution to evaporate the solvent contained in the capsule solution so as to capsulate the thermoplastic resin remaining on the surfaces of the plurality of extinguishing materials, thereby preparing the extinguishing composition.

In the capsule solution coating step (S20), the plurality of extinguishing materials may use calcium bromide (CaBr2).

In the capsule solution preparation step (S10), the thermoplastic resin may use a polymethyl methacrylate polymer resin that is an acrylate polymer resin, and the solvent may use dichloromethane.

The method may further comprise a capsule solution stirring step (S23) of stirring the capsule solution, to which the plurality of extinguishing materials are added, to adjust a size and shape of each of the extinguishing materials and a thickness and shape of the capsule solution applied to the extinguishing materials between the capsule solution coating step (S20) and the extinguishing composition completion step (S30).

The method further comprises a dispersion solution coating step (S25) of applying a dispersion solution to the outside of the plurality of extinguishing materials coated with the capsule solution so that the plurality of extinguishing materials coated with the capsule solution are separated from each other between the capsule solution stirring step (S23) and the extinguishing composition completion step (S30).

The dispersion solution may be provided with silicone oil.

The method may further comprise, after the extinguishing composition completion step (S30), a dispersion solution removing step (S40) of cleaning the extinguishing composition to remove the dispersion solution applied to the extinguishing composition.

A secondary battery according to a second embodiment of the present invention as defined in the appended set of claims comprises: an electrode assembly in which a plurality of electrodes and a plurality of separators are alternately stacked; a case in which the electrode assembly is accommodated; an electrolyte stored in the case so as to be impregnated into the electrode assembly; and an extinguishing composition provided in at least one of the electrodes, the separators, or the electrolyte, wherein the extinguishing composition comprises an extinguishing material and a capsule containing the extinguishing material, and the extinguishing material comprises calcium bromide (CaBr2).

When the extinguishing composition is provided on the separators, the extinguishing composition may be applied to surfaces of the separators through a polymer binder.

The extinguishing composition is further provided outside the case.

Also described herein is a battery pack, which comprises one or more secondary batteries, wherein each of the secondary batteries comprises: an electrode assembly in which a plurality of electrodes and a plurality of separators are alternately stacked; a case in which the electrode assembly is accommodated; an electrolyte stored in the case so as to be impregnated into the electrode assembly; and an extinguishing composition provided in at least one of the electrodes, the separators, or the electrolyte, wherein the extinguishing composition comprises an extinguishing material and a capsule containing the extinguishing material, and the extinguishing material comprises calcium bromide (CaBr2).

The extinguishing composition of the present invention comprises the extinguishing material and the capsule. The extinguishing material comprises calcium bromide (CaBr2). Therefore, the high-temperature heat and the flame may be effectively suppressed by using the air blocking effect to previously prevent the explosion accidents.

Particularly, the extinguishing composition may be applied to the secondary battery. Therefore, the ignition and the explosion of the secondary battery may be effectively prevented to improve the safety of the secondary battery.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings in such a manner that the technical idea of the present invention may easily be carried out by a person with ordinary skill in the art to which the invention pertains. In the drawings, anything unnecessary for describing the present invention will be omitted for clarity, and also like reference numerals in the drawings denote like elements.

As illustrated in <FIG>, an extinguishing composition <NUM> according to a first embodiment of the present invention comprises an extinguishing material <NUM> and micro capsules <NUM> (hereinafter, referred to as capsules) containing the extinguishing material <NUM>.

The extinguishing material <NUM> has an extinguishing function of suppressing high-temperature heat and comprises calcium bromide (CaBr2).

The calcium bromide (CaBr2) is a compound of bromine (Br) and calcium (Ca), which suppresses flame diffusion through oxygen removal to suppress generation of high-temperature heat. Particularly, the bromine (Br) is used as an extinguishing agent that is a halogen compound.

Each of the capsule <NUM> is configured to protect the extinguishing material from the outside at a predetermined temperature or less and is provided as a small shell made of a thermoplastic resin.

Here, the capsule <NUM> has not to exhibit an increase in resistance component and uses the thermoplastic resin having excellent chemical resistance and insulation with respect to an organic electrolyte.

For example, the thermoplastic resin is composed of an acrylate monomer or an acrylate polymer. The acrylate monomer or the acrylate polymer are lightweight, are not electrically conductive, do not rust or rot, are not well melted, has high strength, and are easily melted by heat. Particularly, the acrylate monomer and the acrylate polymer are excellent in hydrophobicity.

Also, a polymethyl methacrylate polymer is used as the acrylate polymer. The polymethyl methacrylate polymer among polymers has crystallinity and high transparency and also has hard properties as well as weather resistance, surface strength, chemical resistance, and electrical insulation. That is, the polymethyl methacrylate may be used to stably protect the extinguishing material.

In addition, a dispersion layer <NUM> that disperses the capsules <NUM> so as not to be attached is further provided outside the capsules <NUM>.

The dispersion layer <NUM> is applied to outer circumferential surfaces of the capsules <NUM> to allow the outer circumferential surfaces of the capsules <NUM> to be smooth, thereby removing an adhesive property of the capsules <NUM>. As a result, the capsules do not adhere to each other but are dispersed.

In particular, the dispersion layer <NUM> is made of a silicone oil material. The silicone oil is an oil-like liquid without taste and odor and allows the outer circumferential surface of the capsules <NUM> to be smooth, thereby reducing friction and preventing the capsules <NUM> from being worn or melted to be attached together. That is, the dispersion layer <NUM> may more easily disperse the capsules <NUM> by using the silicone oil material.

The dispersion layer <NUM> may be removed from the extinguishing composition <NUM> when the extinguishing composition <NUM> is completed.

Thus, the extinguishing composition <NUM> according to the first embodiment of the present invention comprises the extinguishing material <NUM> that is the calcium bromide (CaBr2) and the capsules <NUM>. Therefore, an extinguishing composition having a new structure with a superior extinguishing function may be realized to effectively suppress the high-temperature heat and the flame.

Hereinafter, a method for preparing the extinguishing composition according to the first embodiment of the present invention will be described.

As illustrated in <FIG>, a method for preparing the extinguishing composition according to the first embodiment of the present invention comprises a step (S10) of preparing a capsule solution, a step (S20) of applying the capsule solution, a step (S23) of stirring the capsule solution, a step (S25) of applying a dispersion solution, and a step (S30) of completing an extinguishing composition.

In the step (S10) of preparing the capsule solution, a thermoplastic resin and a solvent are mixed to prepare a capsule solution in which the thermoplastic resin is dissolved.

For example, in the step (S10) of preparing the capsule solution, as illustrated in <FIG>, the thermoplastic resin <NUM> is put into a water tank <NUM> in which the solvent <NUM> is stored. Then, a solution is generated while the thermoplastic resin <NUM> is melted by the solvent <NUM>, and a capsule solution <NUM> is prepared while the thermoplastic resin solution and the solvent are mixed with each other.

The thermoplastic resin <NUM> uses an acrylate polymer resin that is excellent in weather resistance, surface strength, chemical resistance, electrical insulation, and the acrylate polymer resin uses a polymethyl methacrylate polymer resin.

Also, the solvent <NUM> uses dichloromethane to easily dissolve the thermoplastic resin.

In the step (S20) of applying the capsule solution, a plurality of extinguishing materials are added to the capsule solution to apply the capsule solution, in which the thermoplastic resin is dissolved, to surfaces of the plurality of extinguishing materials.

For example, in the step (S20) of applying the capsule solution, as illustrated in <FIG>, the plurality of extinguishing materials <NUM> are added to the capsule solution <NUM> stored in the water tank <NUM>. Then, while the plurality of extinguishing materials <NUM> are accommodated in the capsule solution <NUM>, the capsule solution <NUM> may be naturally applied to outer circumferential surfaces of the plurality of extinguishing materials <NUM>.

Here, each of the extinguishing materials <NUM> uses calcium bromide (CaBr2).

In the step (S23) of stirring the capsule solution, the capsule solution to which the plurality of extinguishing materials are added is stirred to adjust a size and shape of each of the extinguishing materials and a thickness and shape of the capsule solution applied to the extinguishing materials.

For example, in the step (S23) of stirring the capsule solution, as illustrated in <FIG>, the water tank <NUM> in which the plurality of extinguishing materials and the capsule solution <NUM> are contained is installed in a stirrer <NUM>, and then, the stirrer <NUM> operates to allow the water tank <NUM> to rotate. Here, the stirrer <NUM> may allow the water tank <NUM> to rotate forward and reverse every predetermined time to increase in agitation. As a result, the plurality of extinguishing materials <NUM> stored in the water tank <NUM> are pulverized into a plurality of materials while colliding with each other or are deformed in a uniform shape. Particularly, the capsule solution <NUM> is applied again to the outside of the extinguishing materials that are pulverized into the plurality of materials. Also, while allowing the plurality of extinguishing materials <NUM> to rotate together with the water tank <NUM>, the capsule solution <NUM> applied to the outside of the extinguishing materials may be formed to have the uniform thickness and shape.

In the step (S25) of applying the dispersion solution, the dispersion solution is applied to the outside of the plurality of extinguishing materials coated with the capsule solution so that the plurality of extinguishing material coated with the capsule solution are separated from each other.

For example, in the step (S25) of applying the dispersion solution, as illustrated in <FIG>, the dispersion solution <NUM> is added to the capsule solution within the water tank <NUM> in which the stirring is completed in the step (S32) of stirring the capsule solution. As a result, the dispersion solution <NUM> is mixed with the capsule solution <NUM> and simultaneously applied to the outer circumferential surfaces of the plurality of extinguishing materials <NUM>. In detail, the dispersion solution <NUM> is applied to the outside of the capsule solution <NUM> that is disposed outside the extinguishing materials <NUM> to allow the outer circumferences of the extinguishing materials <NUM> to be smooth. Therefore, the plurality of extinguishing materials <NUM> contained in the capsule solution <NUM> may be effectively dispersed.

The dispersion solution <NUM> uses a silicone oil, and the silicone oil may greatly increase in dispersibility of the extinguishing materials.

In the step (S30) of completing extinguishing composition, the plurality of extinguishing materials coated with the capsule solution are heated to evaporate the solvent contained in the capsule solution. Thus, the thermoplastic resin remaining on the surfaces of the plurality of extinguishing materials may be coagulated to form capsules, thereby preparing the extinguishing solution comprising the capsules containing the extinguishing materials.

For example, in the step (S30) of completing the extinguishing composition, as illustrated in <FIG>, the water tank <NUM> containing the extinguishing material <NUM>, the capsule solution <NUM>, and the dispersion solution <NUM> is installed in a heater <NUM> and then heated by the heater <NUM>. Thus, the extinguishing substance <NUM>, the capsule solution <NUM> and the dispersion solution <NUM> stored in the water tank <NUM> increase in temperature. Here, the solvent <NUM> contained in the capsule solution <NUM> is evaporated, and thus, the thermoplastic resin from which the solvent <NUM> of the capsule solution <NUM> applied to the extinguishing material <NUM> is coagulated to form the capsule <NUM>. Also, while moisture contained in the dispersion solution <NUM> applied to the outer circumferential surface of the capsule <NUM> is evaporated, a dispersion layer <NUM> surrounding the capsule <NUM> is formed.

The extinguishing composition <NUM> comprising the extinguishing material <NUM>, the capsule <NUM>, and the dispersion layer <NUM> may be prepared through the above-described processes.

The dispersion layer <NUM> is configured to disperse the plurality of extinguishing materials <NUM> without being coagulated when the extinguishing composition <NUM> is prepared. When the extinguishing composition <NUM> is completely prepared, the dispersion layer <NUM> is removed from the extinguishing composition <NUM>. That is, when the dispersion layer <NUM> is provided in the secondary battery, the dispersion layer <NUM> may contaminate or deteriorate the electrolyte provided in the secondary battery to cause performance deterioration or failures of the secondary battery.

Thus, when the extinguishing composition is completely prepared, the step of removing the dispersion is performed to remove the dispersion solution.

In the step (S40) of removing the dispersion solution, the extinguishing composition is cleaned to remove the dispersion solution that is the dispersion layer applied to the extinguishing composition.

For example, in the step (S40) of removing the dispersion solution, as illustrated in <FIG>, the plurality of extinguishing compositions <NUM> are put into the water tank <NUM> containing water <NUM>. Then, the dispersion solution that is the dispersion layer applied to each of the extinguishing compositions <NUM> may be removed by the water <NUM> stored in the water tank <NUM> while being cleaned. Alternatively, the dispersion layer applied to the extinguishing compositions may be removed by using flowing water.

As described above, when the step (S40) of removing the dispersion solution is completed, as illustrated in <FIG>, the finished extinguishing composition <NUM> comprising the extinguishing material <NUM> and the capsule <NUM> may be prepared.

Therefore, the method for preparing the extinguishing composition according to the first embodiment of the present invention may be simply and easily prepared. Particularly, as the calcium bromide (CaBr2) is used as the extinguishing material, an extinguishing agent having a new component may be obtained.

Hereinafter, in descriptions of another embodiment of the present invention, constituents having the same configuration and function as the above-mentioned embodiment have been given the same reference numeral in the drawings, and thus duplicated description will be omitted.

As illustrated in <FIG> and <FIG>, a secondary battery <NUM> according to a second embodiment of the present invention comprises an electrode assembly <NUM> in which a plurality of electrodes <NUM> and a plurality of separators <NUM> are alternately stacked, a case <NUM> in which the electrode assembly <NUM> is accommodated, an electrolyte <NUM> stored in the case <NUM> so as to be impregnated into the electrode assembly <NUM>, and an extinguishing composition <NUM> provided in at least one of the electrodes <NUM>, the separators <NUM>, or the electrolyte <NUM> to suppress high-temperature heat generated in the case <NUM>, thereby preventing explosion or ignition from occurring.

Here, the extinguishing composition <NUM> comprises an extinguishing material <NUM> and a capsule <NUM> containing the extinguishing material <NUM>, and the extinguishing material <NUM> comprises calcium bromide (CaBr2).

The extinguishing composition <NUM> has the same component and function as the extinguishing composition according to the foregoing first embodiment, and thus, its duplicated description will be omitted.

Therefore, the secondary battery <NUM> according to the second embodiment of the present invention comprises the extinguishing composition <NUM>. As a result, when the electrolyte within the case <NUM> rapidly increases in temperature by the electrode assembly <NUM>, the capsule <NUM> of the extinguishing composition <NUM> may be melted to suppress or cool the increases in temperature of the electrolyte <NUM> through the extinguishing material <NUM>, thereby preventing the secondary battery <NUM> from being exploded or ignited.

The extinguishing composition <NUM> may be provided in the separator <NUM> provided in the electrode assembly <NUM> to effectively suppress the increase in temperature of the electrodes disposed at both sides of the separator <NUM>.

Particularly, the extinguishing composition <NUM> may be applied to the surface of the separator <NUM> through a polymer binder <NUM> to effectively fix the extinguishing composition <NUM> to the separator <NUM>.

The extinguishing composition <NUM> is further provided on an outer surface of the case <NUM>. That is, the extinguishing composition may be applied to the outer circumferential surface of the case <NUM> through the binder to form an extinguishing composition layer. Therefore, the secondary battery may be stably protected against the high-temperature heat applied from the outside of the secondary battery, thereby improving the safety of the secondary battery.

As illustrated in <FIG>, a battery pack <NUM> comprises one or more secondary batteries <NUM> and a pack case <NUM> accommodating the one or more secondary batteries <NUM>. Each of the secondary batteries <NUM> comprises an electrode assembly <NUM> in which a plurality of electrodes and a plurality of separators are alternately stacked, a case <NUM> in which the electrode assembly <NUM> is accommodated, an electrolyte <NUM> stored in the case <NUM> so as to be impregnated into the electrode assembly <NUM>, and an extinguishing composition <NUM> provided in at least one of the electrodes <NUM>, the separators <NUM>, or the electrolyte <NUM>.

Therefore, the battery pack <NUM> may comprise the secondary battery <NUM> provided with the extinguishing composition to effectively suppress or cool the increase in temperature of the secondary battery, thereby improving the safety.

Particularly, in the battery pack <NUM> the secondary battery <NUM> may comprise the extinguishing composition layer <NUM> made of the extinguishing material <NUM> outside the case <NUM> to effectively suppress the high-temperature heat generated in the pack case <NUM>, thereby preventing the explosion or ignition from occurring.

Experimental Example <NUM> is performed to confirm a structure of a prepared extinguishing composition.

An extinguishing composition prepared by using the method for preparing the extinguishing composition according to the first embodiment of the present invention is prepared, and then, when the prepared extinguishing composition is photographed by using an electron microscope, a photograph as shown in <FIG> may be obtained.

That is, referring to <FIG>, in Preparation Example <NUM>, it may be confirmed that the extinguishing compositions have different sizes. Particularly, it may be confirmed that the extinguishing composition having a globular shape is generated. The photographed extinguishing composition has a size of <NUM> µm to <NUM> µm.

Experimental Example <NUM> is performed to confirm whether the extinguishing composition is applied.

A separator containing no extinguishing composition is prepared, and the prepared separator is photographed by using an electron microscope.

The extinguishing composition is applied to a surface of the separator. Here, the extinguishing composition is applied to the surface of the separator through a polymer binder, and when the coating of the extinguishing composition is completed, it is photographed by using the electron microscope.

Here, in Comparative Example <NUM> and Preparation Example <NUM>, the separator made of the same material is used, and the same electron microscope is used for the photographing.

In Comparative Example <NUM>, referring to (a) of <FIG>, it is seen that nothing is present on the surface of the separator. Also, in Preparation Example <NUM>, referring to (b) of <FIG>, it may be confirmed that a convex ridge that is expressed by a white color is disposed on an entire surface of the separator. It is confirmed that the ridge is applied to the entire surface of the separator with the extinguishing composition.

Experimental Example <NUM> is performed to evaluate extinguishing ability of the extinguishing composition.

A solvent in which dimethyl carbonate and ethylene carbonate, which are used as flammable organic electrolytes are mixed with each other is burnt to measure a time required for combustion.

A solvent in which dimethyl carbonate and ethylene carbonate, which are used as flammable organic electrolytes are mixed with each other is burned in a state of containing the extinguishing composition to measure a time required for combustion. Here, in Preparation Example <NUM>, three combustion experiments are carried out. As a result, the obtained results are shown as Preparation Example <NUM>-<NUM>, Preparation Example <NUM>-<NUM>, and Preparation Example <NUM>-<NUM>.

In Comparative Example <NUM> and Preparation Example <NUM>, the same solvent in which dimethyl carbonate and ethylene carbonate are mixed with each other is used and then burned by using the same firearm.

In Comparative Example <NUM> and Preparation Example <NUM>, combustion results of <FIG> may be obtained through the results obtained by measuring the combustion time.

Referring to <FIG>, in Comparative Example <NUM>, it may be confirmed that a combustion time of <NUM> seconds is measured. Also, in Preparation Example <NUM>-<NUM>, it may be confirmed that a combustion time of <NUM> seconds is measured. In Preparation Example <NUM>-<NUM>, it may be confirmed that a combustion time of <NUM> seconds is measured. In Preparation Example <NUM>-<NUM>, it may be confirmed that a combustion time of <NUM> seconds is measured. That is, in Preparation Example <NUM>, it may be confirmed that a combustion time of <NUM> seconds to <NUM> seconds is measured.

Thus, according to the results of Experimental Example <NUM>, in Preparation Example <NUM>, in which the extinguishing composition is added, it may be seen that the combustion time is significantly reduced when compared to Comparative Example <NUM>.

Experimental Example <NUM> is performed to confirms performance impacts of the secondary battery comprising the extinguishing composition (discharge capacity).

A secondary battery comprising an electrode assembly, an electrolyte, and a case is prepared, and a change in performance is measured while charging and discharging the prepared secondary battery.

A secondary battery comprising an electrode assembly, an electrolyte, a case, and an extinguishing composition is prepared, and a change in performance is measured while charging and discharging the prepared secondary battery. Here, in Preparation Example <NUM>, three performance experiments are carried out. As a result, the obtained results are shown as Preparation Example <NUM>-<NUM>, Preparation Example <NUM>-<NUM>, and Preparation Example <NUM>-<NUM>.

In Comparative Example <NUM> and Preparation Example <NUM>, the secondary batteries have the same constituent except for the extinguishing composition, and the charging and discharging are performed under the same environment and voltage.

According to the results obtained by measuring the performance in Comparative Example <NUM> Preparation Example <NUM>, a graph shown in <FIG> may be obtained.

Referring to <FIG>, it may be confirmed that the performance in Comparative Example <NUM> and Preparation Example <NUM> have the same cycle. Thus, in Preparation Example <NUM>, even if the extinguishing composition is provided, it may be confirmed that there is no significant difference in performance, that is, discharge capacity.

Claim 1:
An extinguishing composition comprising:
an extinguishing material; and
a capsule configured to contain the extinguishing material,
wherein the extinguishing material comprises calcium bromide (CaBr2);
wherein the extinguishing composition further comprises a dispersion layer applied to an outer circumferential surface of the capsule.