Thermal runaway protection film

Abstract

The present invention relates to a thermal runaway protection film comprising high-purity crystalline fibers obtained by means of an evaporation drying method by which an ionic molten solution of an alkali halide-based compound or a halide is continuously passed between supports while being evaporated and dried by heat. According to the present invention, safety in the use of a secondary battery can be ensured by blocking further flame propagation in the event of a fire during use of a lithium secondary battery.

Description

Thermal runaway prevention film

[0001] The present invention relates to a thermal runaway prevention film that has a self-extinguishing function in the event of thermal runaway in an energy storage system (ESS) and an electric vehicle battery, and more specifically, to a thermal runaway prevention film that uses a phase-transition crystalline fiber that absorbs runaway heat and prevents thermal runaway.

[0002] Secondary batteries, such as lithium-ion batteries used in energy storage systems (ESS) and electric vehicles, are a key driving force for future industries, and each country is competing to develop them.

[0003] In secondary batteries, thermal runaway can occur when some battery cells stop functioning, explode due to external impact, or are overcharged, overdischarged, or left at high temperatures. If thermal runaway occurs in a single battery cell, the heat quickly spreads to adjacent battery cells or battery modules, ultimately causing a fire that can spread throughout the entire battery module and even burn down the vehicle.

[0004] In order to prevent thermal runaway of a secondary battery, Korean Patent Publication No. 2017-0005117 discloses a lithium ion battery having a thermal runaway protection member including a heat-absorbing material composed of aluminum foam, ceramic, ceramic fiber, or plastic, and Korean Patent No. 2332128 discloses a battery pack including a silicone sponge pad including a platinum-based flame retardant.

[0005] However, it is realistically difficult to prevent thermal runaway by lowering the temperature near 900℃ to below 90℃ using only foam materials or silicone sponge pads.

[0006] The problem to be solved by the present invention is to solve the above problems, and to provide a thermal runaway prevention film that can prevent further spread of flames in the event of a fire during use of a lithium secondary battery, thereby ensuring the safety of use of the secondary battery.

[0007] Another object of the present invention is to provide a secondary battery module and secondary battery pack having excellent stability, which have a film that prevents the spread of heat and flame between cells in a thermal runaway situation of a high-voltage battery cell.

[0008] One aspect of the present invention to achieve the above-described purpose is:

[0009] The present invention relates to a thermal runaway prevention film comprising a phase transition crystalline fiber of an alkali halide compound, a halide or a phase transition inorganic compound.

[0010] The above alkali halide compound may be selected from the group consisting of LiF (lithium fluoride), LiCl (lithium chloride), LiBr (lithium bromide), LiI (lithium iodide), NaF (sodium fluoride), NaCl (sodium chloride), NaBr (sodium bromide), NaI (sodium iodide), KF (potassium fluoride), KCl (potassium chloride), KBr (potassium bromide), KI (potassium iodide), RbF (rubidium fluoride), RbCl (rubidium chloride), RbBr (rubidium bromide), RbI (rubidium iodide), CsF (cesium fluoride), CsCl (cesium chloride), CsBr (cesium bromide), CsI (cesium iodide), and mixtures thereof.

[0011] The above halide may be selected from the group consisting of TlCl (thallium chloride), TlBr (thallium bromide), TlI (thallium iodide), InCl (indium chloride), InBr (indium bromide), InI (indium iodide), SnCl2 (tin(ii) chloride), SnBr2 (tin(ii) bromide), SnI2 (tin(ii) iodide), BiCl3 (bismuth(iii) chloride), BiBr3 (bismuth(iii) bromide), BiI3 (bismuth(iii) iodide), and CuI (copper iodide).

[0012] The above inorganic compound may be selected from the group consisting of MgCl2·6H2O (magnesium chloride), Sr(OH)2·8H2O (strontium hydroxide), Ba(OH)2·8H2O (barium hydroxide), NaCH2S2O2·5H2O (barium hydroxide), Na2S2O3·5H2O (sodium thiosulfate), CaBr2·6H2O (calcium bromide), Zn(NO3)2·6H2O (zinc nitrate), Na2HPO4·12H2O (disodium phosphate), Na2SO4·10H2O (sodium sulfate), LiNO2·3H2O (lithium nitrite), and CaCl2·6H2O (calcium chloride).

[0013] The above thermal runaway prevention film may further include a gas absorbent inside.

[0014] The above gas adsorbent may be at least one selected from the group consisting of porous carbon materials, porous metal-organic frameworks, porous silica gel, porous zeolite, porous activated carbon alumina, and porous bauxite.

[0015] The above crystalline fibers can be arranged in a direction.

[0016] The above-mentioned phase-transition crystalline fiber of an alkali halide compound, halide or phase-transition inorganic compound may be a crystalline fiber manufactured by mixing a porous solid material into an ionic melt of an alkali halide compound, halide or phase-transition inorganic compound to manufacture a slurry, then compressing and packing the slurry inside a carrier without pores, and then heating and evaporating and drying the carrier in which the slurry is compressed and packed to grow crystals.

[0017] Another aspect of the present invention relates to a thermal runaway prevention sheet manufactured by covering both sides of the thermal runaway prevention film of the present invention described above with a support.

[0018] The support may be at least one polymer sheet selected from the group consisting of polyvinyl chloride, cellulose acetate, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyolefin, polymethyl methacrylate, and polyvinylacetate.

[0019] The thickness of the above thermal runaway prevention sheet is 5 to 50 mm, and the final density is in the range of 150 to 400 kg / ㎥.

[0020] Another aspect of the present invention relates to a secondary battery module including the above-described thermal runaway prevention film or thermal runaway prevention sheet.

[0021] Another aspect of the present invention relates to a secondary battery pack including the secondary battery module of the present invention described above.

[0022] The thermal runaway prevention film of the present invention is inserted into a secondary battery, and when a flame occurs within the secondary battery, it blocks the flame or heat from spreading to the outside, thereby minimizing additional chain reactions and damage caused by the flame generated within the secondary battery. In this way, the thermal runaway prevention film of the present invention can further enhance the safety of a secondary battery module or secondary battery pack containing the film.

[0023] The thermal runaway prevention film of the present invention can maintain an optimal temperature by cooling the battery during normal operation of the battery, and can prevent thermal runaway when an abnormal situation such as thermal runaway occurs, thereby preventing loss of function of all cells accommodated in the module.

[0024] Figure 1 is a schematic cross-sectional view of a thermal runaway prevention film according to one embodiment of the present invention.

[0025] Figure 2 is a photograph of a LiCl crystalline fiber manufactured in an embodiment of the present invention.

[0026] Figure 3 is a photograph of a NaCl crystalline fiber manufactured in an embodiment of the present invention.

[0027] Figure 4 is a photograph of a KCl crystalline fiber manufactured in an embodiment of the present invention.

[0028] Figure 5 is a scanning electron microscope (SEM) photograph of a KCl crystalline fiber manufactured in an embodiment of the present invention.

[0029] Figure 6 shows an EDS spectrum of a KCl crystalline fiber manufactured in an embodiment of the present invention.

[0030] Figure 7 shows the results of X-ray diffraction (XRD) analysis of KCl crystalline fibers manufactured in an embodiment of the present invention.

[0031] Figure 8 is a photograph of an RbCl crystalline fiber manufactured in an embodiment of the present invention.

[0032] Figure 9 is a photograph of a CsCl crystalline fiber manufactured in an embodiment of the present invention.

[0033] Figure 10 is a photograph showing the results of a heat transfer experiment using a KCl crystalline fiber manufactured in an embodiment of the present invention.

[0034] The present invention is described in more detail below.

[0035] In order to clearly explain the present invention in the drawings, parts that are not related to the description are omitted.

[0036] In this specification, singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "have" are intended to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but should be understood to not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0037] One aspect of the present invention relates to a thermal runaway prevention film comprising a phase-transition crystalline fiber of an alkali halide compound, a halide, or a phase-transition inorganic compound. The crystalline fiber is a crystalline fiber formed of highly crystallized, ordered particles in a regular three-dimensional array in space.

[0038] A 'Phase Changing Material (PCM)' is a material that has the function of absorbing, storing, and releasing heat according to changes in the surrounding temperature, and has a large latent heat in a small volume. A phase change material is a material that utilizes the latent heat characteristic of absorbing or releasing heat when a substance undergoes a phase transition. A phase change material is a material that absorbs heat when the temperature rises and releases heat when the temperature drops according to the change in heat flow due to the external and internal temperature gradient. Since the temperature change at the phase transition temperature is minimized, it allows for maintaining an optimal temperature. The heat of dissolution of a latent heat material is an inherent characteristic of the material, and since the phase transition temperature and heat of dissolution vary depending on the material, mixing and utilizing appropriate latent heat materials depending on the intended use allows for effective function over a wide temperature range.

[0039] Thermal runaway in lithium-ion batteries continuously generates heat and oxygen until all internal energy is depleted, making it impossible to extinguish with conventional fire extinguishing equipment. The thermal runaway prevention film containing phase-transition crystalline fibers of the present invention absorbs heat and undergoes a phase transition phenomenon in response to temperature changes in the battery cell. This phenomenon absorbs high heat and cools the battery within the golden time of 15 to 40 seconds in the event of a lithium-ion battery fire, thereby preventing thermal runaway.

[0040] The above alkali halide compounds are LiF (lithium fluoride, melting point 845°C), LiCl (lithium chloride, melting point 605°C), LiBr (lithium bromide, melting point 552°C), LiI (lithium iodide, melting point 446°C), NaF (sodium fluoride, melting point 993°C), NaCl (sodium chloride, melting point 801°C), NaBr (sodium bromide, melting point 747°C), NaI (sodium iodide, melting point 661°C), KF (potassium fluoride, melting point 858°C), KCl (potassium chloride, melting point 770°C), KBr (potassium bromide, melting point 734°C), KI (potassium iodide, melting point 681°C), RbF (rubidium fluoride, melting point 775°C), It may be selected from the group consisting of RbCl (rubidium chloride, melting point 718°C), RbBr (rubidium bromide, melting point 693°C), RbI (rubidium iodide, melting point 646°C), CsF (cesium fluoride, melting point 682°C), CsCl (cesium chloride, melting point 645°C), CsBr (cesium bromide, melting point 636°C), CsI (cesium iodide, melting point 621°C), and mixtures thereof.

[0041] The above halides are TlCl (thallium chloride, melting point 430°C), TlBr (thallium bromide, melting point 480°C), TlI (thallium iodide, melting point 441°C), InCl (indium chloride, melting point 586°C), InBr (indium bromide, melting point 285°C), InI (indium iodide, melting point 210°C), SnCl2 (tin (II) chloride, melting point 247°C), SnBr2 (tin (II) bromide, melting point 215°C), SnI2 (tin (II) iodide, melting point 320°C), BiCl3 (bismuth (III) chloride, melting point 227°C), BiBr3 (bismuth (III) bromide, melting point 219°C), BiI3 (bismuth (III) iodide, melting point 408℃), and CuI (copper iodide, melting point 606℃).

[0042] The above inorganic compounds are MgCl2·6H2O (magnesium chloride, melting point 714°C), Sr(OH)2·8H2O (strontium hydroxide, melting point 375°C), Ba(OH)2·8H2O (barium hydroxide, melting point 78°C), NaCH2S2O2·5H2O (barium hydroxide, melting point 78°C), Na2S2O3·5H2O (sodium thiosulfate, melting point 48°C), CaBr2·6H2O (calcium bromide, melting point 730°C), Zn(NO3)2·6H2O (zinc nitrate, melting point 110°C), Na2HPO4·12H2O (disodium phosphate, melting point 250°C), Na2SO4·10H2O (sodium sulfate, melting point 894°C), It may be selected from the group consisting of LiNO2·3H2O (lithium nitrite, melting point 222°C), CaCl2·6H2O (calcium chloride, melting point 772°C).

[0043] The thermal runaway prevention film of the present invention may further include a gas adsorbent inside. In the present invention, the gas adsorbent is not limited to whether it adsorbs by physical adsorption or chemical adsorption, and any gas adsorbent having a gas absorption capability may be used without limitation. The gas adsorbent may be at least one selected from the group consisting of a porous carbon material, a porous metal-organic framework, a porous silica gel, a porous zeolite, porous activated carbon alumina, and porous bauxite. Meanwhile, any one of Fe3O4, Zn2[Fe(CN)6], Zn3[Fe(CN)6]2, and Ce[Fe(CN)6] oxygen adsorbents may also be used as the gas adsorbent.

[0044] The average size of the above gas adsorbent may be 5 μm or less, preferably 3 μm or less, and more preferably 1 μm or less. Specifically, it may be 0.1 to 5 μm, preferably 0.1 to 3 μm, and more preferably 0.1 to 1 μm, but is not necessarily limited thereto.

[0045] In the present invention, crystalline fibers can be arranged in a directionally aligned manner within the thermal runaway prevention film. When crystalline fibers are arranged in a directionally aligned manner, the specific surface area increases, resulting in improved thermal conductivity and heat absorption efficiency. Furthermore, the volume is reduced, allowing for thinner production.

[0046] The phase-transfer crystalline fiber of an alkali halide compound, a halide or a phase-transfer inorganic compound constituting the thermal runaway prevention film of the present invention can be made into a high-purity crystalline fiber by an evaporation drying method in which an ionic substance of an alkali halide compound, a halide or a phase-transfer inorganic compound is mixed in a solvent and the molten solution is heated while continuously passing it between carriers.

[0047] Specifically, an ionic melt is first prepared by mixing an alkali halide compound, a halide, or a phase-transition inorganic compound into a solvent. Next, a porous solid material is mixed into the ionic melt obtained in the previous step to prepare a slurry, and the slurry is compressed and packed within a carrier so that there are no pores. The carrier in which the slurry is compressed and packed is heated to evaporate and dry according to a temperature and concentration gradient, thereby growing crystals to obtain crystalline fibers.

[0048] The solvent usable for producing an ionic melt may be at least one selected from the group consisting of alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0049] The concentration of the ionic melt of the alkali halide compound, halide, or phase transition inorganic compound may be 5 to 40 wt%. When mixing the alkali halide compound, halide, or phase transition inorganic compound with a solvent, heating or stirring may be performed as needed. For example, mixing may be performed at room temperature or high temperature of 25°C to 70°C for 0.5 to 2 hours at 400 rpm.

[0050] The porous solid material for slurry usable in the present invention includes silicate, sodium silicate, sodium meta silicate, lithium silicate, fumed silica, silicon dioxide, magnesium aluminum silicate, magnesium calcium silicate, aluminum calcium silicate, magnesium aluminum calcium silicate, aluminum oxide, germanium oxide, zirconium oxide, boric anhydride, activated carbon, super activated carbon, microcrystalline cellulose, cellulose fiber, zeolite, montmorillonite, hectorite, Magadite, kenyaite, kaolinite, saponite, beidelite, nontronite, vermicullite, swellable mica, synthetic mica, kanemite, smectite, illite, chlorite, muscovite, pyrophyllite, antigorite, glauconite, vermiculite, sepiolite, imogolite, sobockite, nacrite, anauxite, sericite, ledikite, chrysotile,Nanoparticles composed of a material selected from the group consisting of, but not necessarily limited to, antigorite;

[0051] The ionic molten liquid is mixed with the porous solid material in a weight ratio of 7:2 to 9:2 and uniformly mixed at about 100 to 200 rpm to produce a slurry having a viscosity of 100,000 to 200,000 cp at room temperature.

[0052] The carrier is a columnar (channel) carrier that accommodates a slurry containing a porous solid material, and can be made of metal, plastic, ceramic, and / or glass. The diameter of the carrier is 10 mm to 50 mm, and the length of the carrier is in the range of 3 to 6 cm.

[0053] In the evaporation drying step of the above-mentioned carrier, the heating temperature according to the thermal diffusion that causes the material movement of the ionic aqueous solution occurring in the microvolume pores is preferably set to 25 to 100°C, and the humidity in the evaporation drying step is preferably set to 10 to 50%.

[0054] Another aspect of the present invention relates to a thermal runaway prevention sheet in which the thermal runaway prevention film described above is inserted between two supports.

[0055] Figure 1 is a schematic cross-sectional view of a thermal runaway prevention sheet according to one embodiment of the present invention.

[0056] Referring to FIG. 1, the thermal runaway prevention sheet according to the present invention is manufactured by covering both sides of the thermal runaway prevention film (10) of the present invention described above with a support (polymer sheet) (20).

[0057] The above thermal runaway prevention film (10) includes a phase-transition crystalline fiber of an alkali halide compound, a halide, or a phase-transition inorganic compound as described above, and may optionally further include a gas adsorbent.

[0058] The above support (20) may be at least one polymer sheet selected from the group consisting of polyvinyl chloride, cellulose acetate, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyolefin, polymethyl methacrylate, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), and polyvinylacetate.

[0059] In one embodiment of the present invention, the thickness of the thermal runaway prevention sheet may be 5 to 50 mm, and the final density may be in the range of 150 to 400 kg / ㎥, but the present invention is not limited thereto.

[0060] Hereinafter, a method for manufacturing a thermal runaway prevention sheet according to the present invention will be described. A hot-melt adhesive layer of 1 to 100 μm is applied between each polymer support (20) discharged from both rollers, and a phase-transition crystalline fiber of an alkali halide compound, a halide, or a phase-transition inorganic compound constituting a thermal runaway prevention film (10) is arranged, and then sealed by vacuum thermal compression, and if necessary, additionally sealed by a high-frequency method, thereby manufacturing a thermal runaway prevention sheet having a structure as shown in FIG. 1. Since the thermal runaway prevention sheet undergoes a phase transition from a solid to a liquid depending on the temperature change of the battery cell, it can be manufactured in a form in which the left and right sides of the sheet are adjacently bonded or in contact with each other. If manufactured in this way, no matter which part of the thermal runaway prevention sheet is cut, the phase-transition crystalline fiber of the alkali halide compound, a halide, or a phase-transition inorganic compound will not leak out of the sheet. When crystalline fibers are uniformly arranged between two supports, they are spatially uniformly arranged compared to crystalline powders, which increases the specific surface area and thus has the advantage of increasing heat absorption efficiency.

[0061] Another aspect of the present invention relates to a secondary battery module including the above-described thermal runaway prevention film or thermal runaway prevention sheet.

[0062] The thermal runaway prevention film of the present invention can be incorporated into a secondary battery module. The secondary battery module comprises secondary batteries and thermal runaway prevention films. The thermal runaway prevention film is inserted between the secondary batteries and, in the event of a fire, delays the transfer of heat through an endothermic reaction, thereby suppressing combustion and propagation of the fire, thereby exhibiting a fire-extinguishing function.

[0063] In the battery module, the thermal runaway prevention film may be located at least one of i) between one of a plurality of secondary battery cells accommodated in the housing and an adjacent cell, ii) between an electrode tab of one of the secondary battery cells and an electrode tab of an adjacent cell, and iii) on the upper portion of a cell accommodated in the housing member.

[0064] A secondary battery pack can also be provided by including at least one such secondary battery module. The secondary battery pack can be manufactured by combining the secondary battery modules as unit modules according to the desired output and capacity. Considering installation efficiency, structural stability, etc., the secondary battery pack can be preferably used as a power source for electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, power storage devices, etc., but the scope of application is not limited to these.

[0065] Hereinafter, the present invention will be described in more detail through examples. These examples are intended merely to illustrate the present invention more specifically, and the scope of the present invention is not limited by these examples.

[0066] Example

[0067] Example 1 (Manufacture of LiCl crystalline fiber)

[0068] LiCl (ACS reagent, ≥99% Sigma-Aldrich) and distilled water were mixed to an initial concentration of 20 wt%, and then dissolved in a heating stirrer at 25°C and 400 rpm to prepare a LiCl aqueous solution. The LiCl aqueous solution was poured into fumed silica having a size of 15 nm and uniformly mixed at 100 rpm to prepare a slurry having a viscosity of 100,000 to 200,000 cP at room temperature. At this time, the aqueous solution was 7 g and the fumed silica was 2 g. This slurry was poured into a columnar (channel) carrier filled with silica particles inside a polyethylene tube having a diameter of 15 mm and a height of 30 mm, and the carrier was compression-packed so that there were no pores inside. The slurry-packed support was placed in a forced convection oven with only one surface exposed, and the inside of the oven was set to a temperature of 70°C and a humidity of 20%, and left for 48 hours.

[0069] Pure LiCl crystalline fibers were produced by growing crystals according to the temperature and concentration gradient for 48 hours under the above conditions. A photograph of the produced LiCl crystalline fiber is shown in Fig. 2.

[0070]

[0071] Example 2 (Manufacture of NaCl crystalline fiber)

[0072] Crystalline fibers were manufactured in the same manner as in Example 1, except that a NaCl aqueous solution was used and a constant temperature and humid chamber was used. To control the degree of evaporation and diffusion through an elevated temperature and humidity environment, the slurry-packed support was placed upright in the constant temperature and humidity chamber with only one surface exposed. The interior of the constant temperature and humidity chamber was set to 80°C and humidity 40%, and crystals were grown for 48 hours, resulting in the manufacture of pure NaCl crystalline fibers. A photograph of the manufactured NaCl crystalline fiber is shown in Fig. 3.

[0073]

[0074] Example 3 (Preparation of NaCl crystalline fibers from seawater)

[0075] A NaCl crystalline fiber was manufactured in the same manner as in Example 2, except that 1 kg of seawater was concentrated to 20 g using a rotary evaporator instead of the NaCl aqueous solution, and a carrier having a diameter of 500 mm and a length of 75 cm was used.

[0076]

[0077] Example 4 (Manufacture of KCl crystalline fiber)

[0078] Crystalline fibers were manufactured in the same manner as in Example 1, except that a KCl aqueous solution was used. A photograph of the manufactured KCl crystalline fiber is shown in Fig. 4. The microstructure of the manufactured KCl crystalline fiber was measured using a scanning electron microscope (SEM), and the photograph is shown in Fig. 5.

[0079] In order to confirm the crystal phase of the KCl crystalline fiber manufactured in this example, X-ray diffraction (XRD) analysis was performed, and the results are shown in Fig. 7. Fig. 6 is an EDS spectrum of the KCl crystalline fiber manufactured in this example.

[0080] As shown in Fig. 7, in the case of the KCl crystalline fiber of the present invention, peaks due to crystals appear, but in the case of the KCl powder, it was confirmed that no crystalline phase appeared other than the peaks appearing in the crystalline KCl fiber of the present invention. It was confirmed that the manufacturing method of the present invention produces a crystallized fiber by SEM, XRD, and EDS data.

[0081]

[0082] Example 5 (Preparation of RbCl crystalline fiber)

[0083] Crystalline fibers were manufactured in the same manner as in Example 1, except that an RbCl aqueous solution was used. A photograph of the manufactured RbCl crystalline fiber is shown in Fig. 8.

[0084]

[0085] Example 6 (Manufacture of CsCl crystalline fiber)

[0086] Crystalline fibers were manufactured in the same manner as in Example 1, except that a CsCl aqueous solution was used. A photograph of the manufactured CsCl crystalline fiber is shown in Fig. 9.

[0087]

[0088] Example 7 (Manufacture of MgCl2·6H2O crystalline fiber)

[0089] Crystalline fibers were manufactured in the same manner as in Example 1, except that an aqueous solution of MgCl2·6H2O was used.

[0090]

[0091] Example 8 (Manufacture of CaCl2·6H2O crystalline fiber)

[0092] Crystalline fibers were manufactured in the same manner as in Example 1, except that a CaCl2·6H2O aqueous solution was used.

[0093]

[0094] Manufacturing Example 1: Manufacturing of thermal runaway prevention film

[0095] A hot-melt adhesive layer of 1 to 100 μm was applied on a polyethylene terephthalate (PET) layer using a polymer film, and a phase-transition crystalline fiber of an alkali halide compound, a halide, or a phase-transition inorganic compound prepared in Examples 1 to 8 was placed thereon. Then, the film was sealed by vacuum thermal compression and then further sealed by high-frequency method to produce a thermal runaway prevention film.

[0096]

[0097] Test Example 1: Measurement of phase transition temperature

[0098] In order to confirm the morphology of the crystalline fibers obtained in Examples 1 to 8, differential scanning calorimetry (DSC) analysis was performed on the crystalline fibers manufactured in each Example to observe the phase transition temperature, and the length of the fibers was measured, and the results are shown in Table 1 below.

[0099] Melt carrier diameter (nm)Carrier length (cm)Solvent concentration (wt%)Temperature (℃)RH (%)Fiber length (cm)Phase transition temperature (℃)Example 1LiCl153Distilled water2070105605Example 2NaCl2503Distilled water2080406801Example 3NaCl153Sea water10070402801Example 4KCl153Distilled water20701017770Example 5RbCl153Distilled water2070104.4718Example 6CsCl153Distilled water2070102.5645Example 7MgCl2·6H2O153Distilled water2090103714Example 8CaCl2·6 H2O153Distilled water207055772

[0100]

[0101] As shown in Table 1 above, the crystalline fiber according to the present invention grew to a length of 2.5 cm to 17 cm, and the thermal runaway prevention film using the crystalline fiber manufactured according to the present invention exhibited a phase transition temperature of 605°C to 801°C, and exhibited the property of being able to block thermal runaway by phase transition.

[0102]

[0103] Test Example 2: Heat Transfer Experiment of Thermal Runaway Prevention Sheet

[0104] Figure 10 is a photograph showing the results of a heat transfer experiment on a thermal runaway prevention sheet using KCl crystalline fibers manufactured in Example 4. Crystalline powder and crystalline fibers were placed on a heating plate, and the temperature rise rates were photographed with an infrared camera for comparison. In the photograph, yellow indicates the heating plate temperature, and purple indicates a relatively low temperature. As can be seen in the photograph of Figure 10, when the same amount of heat is applied, the crystalline fibers absorb heat well, demonstrating effective thermal runaway prevention performance.

[0105] While preferred embodiments of the present invention have been described in detail above, it should be understood that these embodiments are provided merely as examples. Numerous modifications, alterations, and substitutions will occur to those skilled in the art without departing from the spirit and scope of the present invention. Therefore, the appended claims are intended to cover all such modifications as fall within the spirit and scope of the present invention.

Claims

1. A thermal runaway prevention film comprising a phase transition crystalline fiber of an alkali halide compound, a halide or a phase transition inorganic compound.

2. A thermal runaway prevention film according to claim 1, characterized in that the alkali halide compound is selected from the group consisting of LiF (lithium fluoride), LiCl (lithium chloride), LiBr (lithium bromide), LiI (lithium iodide), NaF (sodium fluoride), NaCl (sodium chloride), NaBr (sodium bromide), NaI (sodium iodide), KF (potassium fluoride), KCl (potassium chloride), KBr (potassium bromide), KI (potassium iodide), RbF (rubidium fluoride), RbCl (rubidium chloride), RbBr (rubidium bromide), RbI (rubidium iodide), CsF (cesium fluoride), CsCl (cesium chloride), CsBr (cesium bromide), CsI (cesium iodide), and mixtures thereof.

3. In paragraph 1, the halide is TlCl (thallium chloride), TlBr (thallium bromide), TlI (thallium iodide), InCl (indium chloride), InBr (indium bromide), InI (indium iodide), SnCl 2 (Stin(II) chloride), SnBr 2 (Stan(ii) bromide), SnI 2 (Stan(II) iodide), BiCl 3 (Bismuth(iii) chloride), BiBr 3 (Bismuth(iii) bromide), BiI 3 A thermal runaway prevention film characterized in that it is selected from the group consisting of (bismuth iodide(iii)), and CuI (copper iodide).

4. In paragraph 1, the inorganic compound is MgCl 2 ·6H 2 O(magnesium chloride), Sr(OH) 2 ·8H 2 O(strontium hydroxide), Ba(OH) 2 ·8H 2 O(barium hydroxide), NaCH 2 S 2 O 2 ·5H 2 O(barium hydroxide), Na 2 S 2 O 3 ·5H 2 O(sodium thiosulfate), CaBr 2 ·6H 2 O(calcium bromide), Zn(NO 3 ) 2 ·6H 2 O(zinc nitrate), Na 2 HPO 4 ·12H 2 O(disodium phosphate), Na 2 SO 4 ·10H 2 O(sodium sulfate), LiNO 2 ·3H 2 O(lithium nitrite) and CaCl 2 ·6H 2 A thermal runaway prevention film characterized in that it is selected from the group consisting of O (calcium chloride).

5. A thermal runaway prevention film according to claim 1, characterized in that the thermal runaway prevention film further includes a gas absorbent inside.

6. A thermal runaway prevention film according to claim 5, characterized in that the gas adsorbent is at least one selected from the group consisting of a porous carbon material, a porous metal-organic framework, a porous silica gel, a porous zeolite, porous activated carbon alumina, and porous bauxite.

7. A thermal runaway prevention film according to claim 1, characterized in that the crystalline fibers are arranged in a direction.

8. A thermal runaway prevention film according to claim 1, characterized in that the phase-transition crystalline fiber of the alkali halide compound, halide or phase-transition inorganic compound is a crystalline fiber manufactured by an evaporation drying method in which an ionic substance of the alkali halide compound, halide or phase-transition inorganic compound is mixed in a solvent and the molten liquid is continuously passed between carriers while heating.

9. A thermal runaway prevention sheet manufactured by covering both sides of a thermal runaway prevention film according to any one of claims 1 to 8 with a support.

10. A thermal runaway prevention sheet according to claim 9, wherein the support is a sheet made of at least one polymer selected from the group consisting of polyvinyl chloride, cellulose acetate, polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyolefin, polymethyl methacrylate, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), and polyvinylacetate.

11. A thermal runaway prevention sheet according to claim 9, characterized in that the thickness of the thermal runaway prevention sheet is 5 to 50 mm and the final density is in the range of 150 to 400 kg / ㎥.

12. A thermal runaway prevention sheet according to claim 9, characterized in that the thermal runaway prevention film and the support are additionally bonded by hot-melt bonding or high-frequency bonding.

13. A secondary battery module comprising a thermal runaway prevention film according to any one of claims 1 to 8 or a thermal runaway prevention sheet according to any one of claims 9 to 12.

14. A secondary battery pack including the secondary battery module of clause 12.

Images