JP6885791B2 - Thermal runaway prevention sheet - Google Patents

Description

The present invention relates to a thermal runaway prevention sheet.

More eco-friendly electric vehicles are becoming widespread in order to curb global warming and promote a sound material-cycle society. However, it is difficult to achieve a practical cruising range without improving the energy density. On the other hand, a battery with improved energy density tends to induce thermal runaway, and when thermal runaway occurs, the temperature of the battery cell (hereinafter referred to as the cell) may rise sharply to reach 300 to 400 ° C. or higher. is there. In addition, if one cell causes thermal runaway, the adjacent cell is also likely to cause thermal runaway, and as a result, a major accident may occur. Therefore, there has been a demand for a member that suppresses thermal runaway.

In order to prevent a plurality of cells from running away in succession (hereinafter referred to as continuous explosion), Patent Document 1 describes that a plastic thermal runaway prevention wall is provided between adjacent secondary batteries. ing. However, the thermal runaway prevention wall of Patent Document 1 is integrally formed in a heat conduction cylinder whose inner surface is formed into a shape equal to the outer shape of the secondary battery for heat dissipation, and the thermal runaway prevention wall is heat conductive. It has a complicated structure that is a part of the cylinder.

Patent No. 4598409

An object of the present invention is to provide a thermal runaway prevention sheet, a battery structure, and an electronic device that suppress heat conduction to an adjacent cell when one cell has a thermal runaway.

In order to solve the above problems, the following aspects of the present invention are provided.
[1] Containing at least one of a mineral powder and a flame retardant, an endothermic reaction is started at 100 to 1000 ° C., and at least selected from the group consisting of phase change, expansion, foaming and hardening due to the endothermic reaction. A thermal runaway prevention sheet that undergoes a kind of structural change.
[2] The thermal runaway prevention sheet according to Item 1, wherein the volume change rate due to structural change is 80% to 500% or the reaction pressure is 0 to 5 MPa.
[3] The thermal runaway prevention sheet according to Item 1 or 2, wherein the thermal conductivity λ at 400 ° C. is 0.1 W / m · K or less.
[4] The mineral powder is at least one powder selected from the group consisting of diatomaceous earth, talc, calcium carbonate, aluminum hydroxide, titanium oxide, hiruishi (permiculite), zeolite, and white carbon (synthetic silica). Including the body
Item 1 containing at least one powder selected from the group consisting of brominated flame retardants, chlorine flame retardants, phosphorus flame retardants, boron flame retardants, silicone flame retardants, and nitrogen-containing compounds. The heat runaway prevention sheet according to any one of 3 to 3.
[5] The heat runaway prevention sheet according to any one of Items 1 to 4, which contains at least one matrix resin selected from a thermosetting resin, a thermoplastic resin, a thermoplastic elastomer, and rubber.
[6] The thermal runaway prevention sheet according to any one of Items 1 to 3, which is composed of a heat-absorbing material layer containing at least one of a mineral powder and a flame retardant and a fire-resistant heat insulating layer. ..
[7] A fire resistant material layer containing at least one of a mineral powder and a flame retardant and a fire resistant material layer containing one of a mineral powder and a flame retardant not contained in the endothermic material layer. Item 2. The heat runaway prevention sheet according to any one of Items 1 to 3, which is composed of a heat insulating layer.
[8] The thermal runaway prevention sheet according to Item 6, wherein the endothermic material layer has a thickness of 0.1 to 1 mm, and the refractory heat insulating layer contains a nonflammable base material having a thickness of 0.1 to 1 mm.
[9] The thermal runaway prevention sheet according to Item 6 or 7, wherein the sheet includes at least the following three layers (i) or (ii).
(I) The fire-resistant heat insulating layer and two layers of the endothermic material layer arranged on both sides thereof (ii) The heat-absorbing material layer and two layers of the fire-resistant heat insulating material arranged on both sides thereof [10 ] The thermal runaway prevention sheet according to any one of Items 6 to 9, wherein the fire-resistant heat insulating layer and the endothermic material layer are integrally molded.
[11] Assuming that the thermal conductivity of the endothermic material layer at 25 ° C. is λ1 and the thermal conductivity of the refractory heat insulating layer at 25 ° C. is λ2.
Equation 0 <λ2 / λ1 <15
The thermal runaway prevention sheet according to any one of Items 6 to 9.
[12] A thermal runaway prevention sheet used between the frames of a battery structure.
The sheet is provided with an endothermic material layer, and when the cell undergoes thermal runaway, the sheet in contact with the skeleton expands, foams, or hardens, thereby suppressing thermal runaway and suppressing deformation of the skeleton. Prevention sheet.
[13] A battery structure provided with the thermal runaway prevention sheet according to any one of Items 1 to 12.
[14] An electronic device equipped with the battery structure according to item 13.

According to the present invention, it is possible to exhibit high heat insulating performance with a simple configuration and prevent continuous thermal runaway of adjacent cells. Since the thermal runaway prevention sheet of the present invention has sufficient heat insulating properties even if it is thin, it is possible to impart excellent heat insulating properties to the battery in the electronic device.

FIG. 3 is a schematic cross-sectional view showing a thermal runaway prevention sheet according to the first embodiment of the present invention. FIG. 6 is a schematic vertical sectional view of an example of a battery module to which the thermal runaway prevention sheet of FIG. 1 is applied. FIG. 3 is a schematic cross-sectional view showing a thermal runaway prevention sheet according to a second embodiment of the present invention. FIG. 6 is a schematic vertical sectional view of an example of a battery module to which the thermal runaway prevention sheet of FIG. 2 is applied. FIG. 3 is a schematic cross-sectional view showing a thermal runaway prevention sheet according to a third embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing a thermal runaway prevention sheet according to a fourth embodiment of the present invention. FIG. 6 is a schematic vertical sectional view of another example of a battery module to which the thermal runaway prevention sheet of FIG. 1 is applied. FIG. 3 is a schematic vertical sectional view of another example of the battery module to which the thermal runaway prevention sheet of FIG. 3 is applied.

In the present specification, thermal runaway means that the internal temperature of the battery rises to 60 ° C. or higher due to the causes of external short circuit, internal short circuit, overcharge, overdischarge, heating, etc., and the chemical reaction inside the battery proceeds to promote the inside of the battery. Refers to the state in which the temperature rise of the battery progresses at an accelerating rate. In particular, thermal runaway becomes remarkable when the internal temperature of the battery is 200 ° C. or higher.

In the present specification, the term "battery" refers to a lithium ion battery, a lithium ion polymer battery, a nickel / hydrogen battery, a lithium / sulfur battery, a nickel / cadmium battery, a nickel / iron battery, a nickel / zinc battery, a sodium / sulfur battery, and the like. It means a secondary battery such as a lead storage battery or an air battery.

The battery is classified into a cylindrical type, a square type, and a laminated type according to the shape of the cell.

In the present specification, the “battery cell” refers to a constituent unit of a battery in which a positive electrode material, a negative electrode material, a separator, a positive electrode tab or a positive electrode terminal, a negative electrode tab, a negative electrode terminal, and the like are housed in an exterior member. Also called simply "cell".

When the battery cell has a cylindrical shape, it refers to a constituent unit of a battery in which a positive electrode material, a negative electrode material, a separator, a positive electrode tab, a negative electrode tab, an insulating material, a gas discharge valve, a gasket, a positive electrode cap, etc. are housed in an outer can.

When the battery cell has a square shape, it refers to a constituent unit of a battery in which a positive electrode material, a negative electrode material, a separator, a positive electrode terminal, a negative electrode terminal, an insulating material, a gas discharge valve, and the like are housed in an outer can.

When the battery cell is a laminated type, it refers to a constituent unit of a battery in which a positive electrode material, a negative electrode material, a separator, a positive electrode tab, a negative electrode tab, and the like are housed in an exterior film. Examples of the exterior film include an aluminum film on which a polyethylene terephthalate film is laminated.

In the present specification, the "battery module" refers to a component unit of a battery in which a plurality of battery cells are housed in a housing, and the "battery pack" refers to a battery in which a plurality of battery modules are housed in a housing. In addition to the battery cell, necessary members such as an electric connection cable electrically connected to the battery cell are used inside the battery pack and the battery as needed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, the thermal runaway prevention sheet 1 of the first embodiment of the present invention includes an endothermic material layer 2. The endothermic material layer 2 contains at least one of a mineral powder and a flame retardant, starts an endothermic reaction at 100 to 1000 ° C., and is selected from the group consisting of phase change, expansion, foaming and hardening according to the reaction. At least one type of structural change occurs.

The endothermic material layer 2 may contain both the mineral powder and the flame retardant, or may contain only one of the mineral powder and the flame retardant.

The mineral powder is at least one selected from the group consisting of diatomaceous earth, talc, calcium carbonate, aluminum hydroxide, titanium oxide, hilarite (also called permiculite), zeolite, and white carbon (also called synthetic silica). Examples include powder. These mineral powders absorb heat by a dehydration reaction to form an inorganic heat insulating layer. For better endothermic properties, aluminum hydroxide is preferred as the mineral powder. One mineral powder can be used alone, or two or more kinds can be used in combination.

Examples of the flame retardant include at least one flame retardant selected from the group consisting of brominated flame retardants, chlorine flame retardants, phosphorus flame retardants, boron flame retardants, silicone flame retardants, and nitrogen-containing compounds. One flame retardant may be used alone, or two or more kinds may be used in combination.

The brominated flame retardant suppresses combustion by generating bromine-based gas and blocking oxygen. Examples of the brominated flame retardant include tetrabromobisphenol A, decabromobiphenyl, pentabromodiphenyl ether and the like.

Chlorine-based flame retardants suppress combustion by generating chlorine-based gas and blocking oxygen. Examples of the chlorine-based flame retardant include chlorine-based paraffin and chlorine-based polyethylene.

Phosphorus-based flame retardants block oxygen and heat by forming a carbonized layer. Examples of the phosphorus-based flame retardant include phosphoric acid ester and ammonium polyphosphate.

Boron-based flame retardants block oxygen and heat by forming a carbonized layer. Examples of the boron-based flame retardant include sodium polyborate, borax, zinc borate and the like.

The silicone flame retardant forms a Si—C inorganic heat insulating layer. Examples of the silicone-based flame retardant include silicone resin and the like.

Nitrogen-containing compounds block oxygen with a nitrogen-based gas. Examples of the nitrogen-containing compound include ammonium phosphate, guanidine compound, melamine compound and the like.

The start temperature of the endothermic reaction can be adjusted to 100 to 1000 ° C. by appropriately selecting the type and amount of the mineral powder and / or the flame retardant.

The endothermic material layer 2 can contain at least one matrix resin selected from thermosetting resins, thermoplastic resins, thermoplastic elastomers and rubbers.

Examples of the thermoplastic resin include polypropylene resin, polyethylene resin, poly (1-) butene resin, polyolefin resin such as polypentene resin, polyester resin such as polyethylene terephthalate, polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, and ethylene. Examples thereof include synthetic resins such as vinyl acetate copolymer (EVA), polycarbonate resin, polyphenylene ether resin, (meth) acrylic resin, polyamide resin, polyvinyl chloride resin (PVC), novolak resin, polyurethane resin and polyisobutylene.

Examples of the thermosetting resin include synthetic resins such as polyurethane, polyisocyanate, polyisocyanurate, phenol resin, epoxy resin, urea resin, melamine resin, unsaturated polyester resin, and polyimide.

Examples of the elastomer include olefin-based elastomers, styrene-based elastomers, ester-based elastomers, amide-based elastomers, vinyl chloride-based elastomers, and combinations thereof.

Rubber substances include natural rubber, isoprene rubber, butadiene rubber, 1,2-polybutadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, chlorinated butyl rubber, ethylene-propylene rubber, and ethylene-propylene-diene rubber (EPDM). ), Chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polyvulture rubber, non-vulture rubber, silicon rubber, fluororubber, urethane rubber and other rubber substances.

As these synthetic resins and / or rubber substances, one kind or two or more kinds can be used.

Among these synthetic resins and / or rubber substances, PVC and EVA are preferable in terms of molding processability. In order to obtain flexible and rubbery properties, non-vulcanized rubber such as butyl rubber and polyolefin resin are preferable. PVC is preferable in terms of fire resistance. Epoxy resin is preferable from the viewpoint of increasing the flame retardancy of the resin itself and improving the fire protection performance.

The endothermic material layer 2 preferably contains a matrix resin and aluminum hydroxide.

The presence of the matrix resin can suppress the collapse of the expanded structure during expansion and increase the strength of the residual hardness. In addition, durability against the decay of the residue due to heat can be imparted. As a result, the rate of temperature rise of the endothermic material layer 2 can be suppressed.

Since aluminum hydroxide undergoes a phase change in crystal structure from about 200 ° C. and undergoes an endothermic reaction by dehydration decomposition, it is possible to suppress the temperature rise of the cell.

The endothermic material layer 2 can further contain an expandable material.
The expandable material functions to form a heat insulating layer and to block the space that serves as a flow path for fire and heat.

Examples of the expandable material include heat-expandable microcapsules, water-containing microcapsules, foaming agents, microencapsulated foaming agents, heat-expandable layered inorganic substances, and combinations thereof.

The heat-expandable microcapsules are formed in a shell formed of a plastic polymer obtained by polymerizing a composition containing one or more kinds of monomers and a cross-linking agent, and have a temperature below the softening point of the polymer. It contains a volatile swelling agent that becomes gaseous. For example, the shell is composed of a polymer obtained by polymerizing a monomer mixture containing 95% by weight or more of (meth) acrylonitrile and 70% by weight or more of (meth) acrylonitrile being acrylonitrile, and has a degree of cross-linking of 60% by weight or more. The heat-expandable microcapsules are described in WO2010 / 052972. When the polymer contains a monomer other than (meth) acrylonitrile, such monomer includes a monomer selected from the group consisting of methacrylic acid ester, acrylic acid ester, styrene, vinylidene chloride and vinyl acetate.

Examples of the volatile swelling agent include a low boiling point organic solvent and a compound which is thermally decomposed into a gas by heating and are preferably used. Among them, a low boiling point organic solvent is particularly preferably used. These volatile leavening agents may be used alone or in combination of two or more.

Examples of the low boiling point organic solvent include ethane, ethylene, propane, propene, n-butane, isobutane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, heptane, nonane, decane, and petroleum. hydrocarbons such as ethers; CCl ₃ F, chlorofluorocarbons such as _{CCl 2 F 2, CClF 3,} CClF 2 -CCl 2 F 2; tetramethylsilane, trimethylethyl silane, trimethyl isopropyl silane, such as trimethyl -n- propyl silane Tetraalkylsilane and the like can be mentioned and are preferably used, but among them, hydrocarbons such as n-butane, isobutane, n-pentane, isopentane, n-hexane, nonane, decane and petroleum ether can be used, and preferably. 3 to 12 carbon atoms are used. Further, linear hydrocarbons and esters may also be used. Particularly preferably, a hydrocarbon having 4 or more carbon atoms is particularly preferably used. These low boiling point organic solvents may be used alone or in combination of two or more.

The water-containing microcapsules are the above-mentioned microcapsules containing water.

Examples of the foaming agent include an inorganic foaming agent, an organic foaming agent, and a combination thereof.

Examples of the inorganic foaming agent include gas-generating materials that are inorganic compounds such as water and sodium hydrogen carbonate. These inorganic foaming agents can be used alone or in combination of two or more.

Examples of the organic foaming agent include ethane, ethylene, propane, propene, n-butane, isobutane, n-butene, isobutene, n-pentane, isopentan, neopentane, n-hexane, heptane, nonane, decane, petroleum ether and the like. Hydrocarbons; azo compound-containing foaming agents such as azodicarbonamide (ADCA) and azodiaminobenzene; nitroso compounds such as dinitrosopentamethylenetetramine (DPT), N, N'-dinitroso-N, N'-dimethylterephthalamide. Containing foaming agents: sulfonyl / hydrazide-containing foaming agents such as benzenesulfonylhydrazide, p, p'-oxybisbenzenesulfonylhydrazide (OBSH), hydrazodicarbonamide (HDCA) and the like. One of these organic foaming agents or a combination of two or more of these organic foaming agents can be used.

The microencapsulated foaming agent is one or two or more of the above-mentioned foaming agents encapsulated in microcapsules. As the synthetic resin used for the microcapsules, for example, a thermoplastic synthetic resin having a viscosity that melts when the temperature rises above a certain level and the microcapsules do not crack and expand substantially spherically may be used.

By adding the microencapsulating foaming agent to the heat runaway prevention sheet 1 (and the endothermic material layer 2), the heat runaway prevention sheet 1 (and the endothermic material layer 2) was heated to a certain temperature or higher. In this case, since the synthetic resin melts, the heat runaway prevention sheet 1 (and the endothermic material layer 2) can be foamed.

The heat-expandable layered inorganic substance expands when heated and is not particularly limited, and examples thereof include vermiculite, kaolin, mica, and heat-expandable graphite. Thermally expandable graphite is a conventionally known substance that expands when heated. Powders such as natural scaly graphite, thermally decomposed graphite, and kiss graphite are mixed with inorganic acids such as concentrated sulfuric acid, nitric acid, and selenic acid, and concentrated nitrate and perchloric acid. A graphite interlayer compound is formed by treatment with a strong oxidizing agent such as chloric acid, perchlorate, permanganate, dichromate, dichromate, hydrogen peroxide, etc., and is a layer of carbon. It is a kind of crystalline compound that maintains its structure.

The heat-expandable graphite obtained by the acid treatment as described above may be further neutralized with ammonia, an aliphatic lower amine, an alkali metal compound, an alkaline earth metal compound or the like.

The content of the expandable material in the thermal runaway prevention sheet 1 (and the endothermic material layer 2) can be appropriately set according to the expansion ratio. The expandable material is usually 0.1 to 20 parts by mass, preferably 1 to 10 parts by mass, based on 100 parts by mass of the resin component. The thermal runaway prevention sheet 1 (and the endothermic material layer 2) starts expanding at a temperature exceeding 80 ° C., and the expansion ratio in the thickness direction (thickness after expansion / thickness before expansion) is 2 to 50 times, preferably 2 to 50 times. Adjust so that it is about 3 to 30 times. Further, according to this formulation, the heat-expandable sheet formed from the thermal runaway prevention sheet 1 (and the endothermic material layer 2) expands due to heating such as heat generation of the battery, and a required coefficient of thermal expansion can be obtained. In addition, after expansion, a residue having a predetermined heat insulating performance and a predetermined strength can be formed, and stable fire protection performance can be achieved. Further, by using an expandable material having a low expansion start temperature, the thermal runaway prevention sheet 1 (and the endothermic material layer 2) can be designed to start expansion even at a relatively low temperature.

The endothermic material layer 2 can further contain a plasticizer.

The plasticizer is not particularly limited as long as it is a plasticizer generally used in producing a polyvinyl chloride resin molded product. Specifically, for example, phthalate plasticizers such as di-2-ethylhexyl phthalate (DOP), dibutyl phthalate (DBP), diheptyl phthalate (DHP), and diisodecyl phthalate (DIDP),
Fatty acid ester plasticizers such as di-2-ethylhexyl adipate (DOA), diisobutyl adipate (DIBA), dibutyl adipate (DBA); epoxidized ester plasticizers such as epoxidized soybean oil; polyesters such as adipic acid ester and adipate polyester Plasticizers; Trimellitic acid ester plasticizers such as Tory 2-ethylhexyl trimellitate (TOTM) and Triisononyl trimellitate (TINTM); Process oils such as mineral oils and the like. One type or two or more types of plasticizers can be used.

If the content of the plasticizer is small, the injection moldability, extrusion moldability, etc. tend to decrease, and if the content is large, the obtained molded product tends to be too soft. Therefore, the content of the plasticizer is not limited, but it is preferably 0 to 40% by mass, more preferably 5 to 35% by mass in the endothermic material layer 2.

The endothermic material layer 2 can contain various additive components as needed, as long as the object of the present invention is not impaired. The type of this additive component is not particularly limited, and various additives usually used for foam molding can be used. Examples of such additives include lubricants, shrinkage inhibitors, bubble nucleating agents, crystal nucleating agents, plasticizers, colorants (pigments, dyes, etc.), ultraviolet absorbers, antioxidants, antioxidants, and the above heat conduction. Examples thereof include fillers excluding bodies, reinforcing agents, flame retardants, flame retardants, antistatic agents, surfactants, lubricants, surface treatment agents and the like. The amount of the additive added can be appropriately selected within a range that does not impair the formation of bubbles and the like, and the amount of the additive used for foaming and molding a normal resin can be adopted. Such additives can be used alone or in combination of two or more.

The thickness of the thermal runaway prevention sheet of the present invention is not particularly limited, but is preferably 0.1 mm to 1 mm. The "thickness" of the thermal runaway prevention sheet as used herein refers to the average thickness of the three points in the width direction of the thermal runaway prevention sheet.

The endothermic material layer 2 undergoes at least one structural change selected from the group consisting of phase change, expansion, foaming and hardening according to the endothermic reaction.

"Phase change" means that a phase that is a chemically and physically uniform part changes to a different phase such as a liquid phase, a solid phase, a gas phase, a plasma phase, or a crystal structure phase due to changes in external stimuli such as temperature and pressure. Refers to transfer. For example, aluminum hydroxide is a white powder crystal that is stable up to about 200 ° C., and at higher temperatures, a dissociation reaction of water of crystallization occurs, and it is separated into 66% aluminum oxide and 34% water of crystallization. The crystal structure changes.

"Expansion" means that the volume and length of the target substance itself increase before and after. For example, when heat-expandable graphite is heated to about 100 to 300 ° C., the acid between the graphite layers is released, and the volume of graphite expands to about 3 to 100 times.

“Foam” refers to the formation of a gas phase membrane structure. For example, silicates and borates foam when heated to form foams.

"Curing" refers to the hardening of the condition. It becomes hard by cross-linking by reaction with a curing agent or by polymerization reaction. Its hardness is determined by the progress of the reaction and the structure of the polymer. Phenol resin, epoxy resin, polyurethane, etc. are cured by a polymerization reaction by heating.

The thermal runaway prevention sheet 1 of the first embodiment is selected from the group consisting of phase change, expansion, foaming, and curing when the cell to which the thermal runaway prevention sheet 1 is attached is heated by thermal runaway. At least one type of structural change occurs. Therefore, by securing the distance between the adjacent cells by the thermal runaway prevention sheet 1, the heat due to the thermal runaway of one cell is suppressed from being transferred to the adjacent cells, and as a result, the heat is continuously transferred to the adjacent cells. Thermal runaway can be suppressed.

The reaction pressure of the thermal runaway prevention sheet 1, that is, the endothermic material layer 2, is preferably 0 to 5 MPa. The "reaction pressure" here refers to the pressure received by the endothermic material layer 2 due to the structural change caused by the endothermic reaction. When the structural change is curing, the volume change rate is 100% or less due to curing shrinkage, the endothermic material layer 2 is not pressed, and the reaction pressure is approximately 0 MPa. When the structural change is hardening, the volume change rate is preferably 80% or more and 100% or less.

When the structural change is phase change, expansion, or foaming, the volume change rate due to the structural change exceeds 100%, and the reaction pressure is greater than 0 MPa and less than 5 MPa. When the structural change is phase change, expansion, or foaming, the volume change rate is more than 100% and less than 500%.

The fact that the volume change rate due to the structural change of the thermal runaway prevention sheet or the endothermic material layer 2 is 80% to 500% and / or the reaction pressure is 0 to 5 MPa is the point of suppressing heat transfer to the adjacent cell due to the heat insulating effect. Is preferable.

As described above, since the endothermic material layer 2 is cured or the volume is expanded, the thermal runaway prevention sheet 1 can more reliably secure the distance between adjacent cells.

Further, the thermal conductivity λ of the thermal runaway prevention sheet 1, that is, the endothermic material layer 2 at 400 ° C. is preferably 0.1 W / m · K or less. Therefore, even if thermal runaway occurs in one cell, the heat from the thermal runaway of one cell is transferred to the adjacent cells by securing the distance between the adjacent cells due to the heat insulating effect of the endothermic material layer 2. This can be suppressed, and thus continuous thermal runaway to adjacent cells can be suppressed.

The thermal runaway prevention sheet contains at least one of the above matrix components, mineral powder and flame retardant, and other components of the option, such as a single-screw extruder, a twin-screw extruder, an injection molding machine, a Banbury mixer, and a kneader. It can be produced by coating or molding a mixed composition using a known device such as a mixer, a kneading roll, a raikai machine, or a planetary stirrer. Molding includes press molding, extrusion molding and injection molding. Coating or molding is well known in the art.

As shown in FIG. 2, a plurality of battery cells 7 (three are shown in the figure) are vertically separated from each other in the housing 6 of the battery module 10 to which the thermal runaway prevention sheet 1 of the first embodiment is installed. They are housed side by side so as to extend in the direction, and a thermal runaway prevention sheet 1 is arranged between adjacent battery cells 7, and the thermal runaway prevention sheet 1 is attached to one surface of the battery cell 7.

As a method of installing the thermal runaway prevention sheet 1 on a part or all of at least one surface (for example, one side or a pair of both sides) of the battery cell 7, for example, the thermal runaway prevention sheet 1 is adhered to the surface of one battery cell 7. Examples thereof include a method of sticking and fixing the battery cell 7 and the thermal runaway prevention sheet 1 through a material or by self-adhesiveness of the thermal runaway prevention sheet 1, and a method of fixing the battery cell 7 and the thermal runaway prevention sheet 1 using a frame after laminating them.

The dimensions of the thermal runaway prevention sheet 1 are not particularly limited, and may be changed according to the size of the battery cell 7 and the size of the space in the battery module 10.

The housing 6 is, for example, a metal or resin molded housing, but is not limited thereto. The battery cell 7 and the thermal runaway prevention sheet 1 are substantially rectangular parallelepipeds in the shape of a flat plate in FIG. 2, and are arranged substantially parallel to each other. A space 8 is provided around the battery cell 7 and the thermal runaway prevention sheet 1 in the housing 6, and between the battery cell 7 and the thermal runaway prevention sheet 1 adjacent to the battery cell 7. The space 8 acts as an air passage for heat dissipation of the battery cell 7. For example, the battery cell 7 may be heated during operation, but by securing such a space 8, the battery cell 7 can dissipate heat more quickly.

The thermal runaway prevention sheet 1 starts an endothermic reaction at 100 to 1000 ° C. when the thermal runaway prevention sheet 1 is heated due to abnormal heat generation or fire, and is selected from the group consisting of phase change, expansion, foaming, and curing. At least one type of structural change occurs, forming an endothermic layer between adjacent battery cells 7. Further, when the structural change is phase change, expansion, or foaming, the space serving as a flow path for fire or heat between adjacent battery cells 7 is blocked. Therefore, the thermal runaway prevention sheet 1 functions as a heat insulating layer, and can prevent or suppress heat transfer from a certain battery cell 7 to the adjacent battery cell 7 and continuous explosion, and is continuous to the adjacent battery cell 7. Thermal runaway can be prevented or suppressed, and the safety of the battery cell 7 and the battery module 1 provided with the battery cell 7 is ensured.

As described above, the thermal runaway prevention sheet 1 used between the skeletons of the battery structure includes the endothermic material layer 2, and when the cell heats out, the sheet 1 in contact with the skeleton expands. The thermal runaway prevention sheet 1 that suppresses thermal runaway and suppresses deformation of the skeleton by foaming or curing is included in the scope of the present invention.

The skeleton refers to a cell cell in which the positive electrode terminal and the negative electrode terminal are arranged so as to be opposite to each other, an insulating member covering each of the cell cells, and a structural unit including an exterior material, and in particular, the above-mentioned battery. Point to a cell.

The battery structure refers to a structure in which at least one and a plurality of battery cells are connected by wiring or the like to be modularized and sealed in a container, and particularly refers to the above-mentioned battery module.

Next, the thermal runaway prevention sheet 1 of the second embodiment of the present invention will be described.

Referring to FIG. 3, the thermal runaway prevention sheet 1 of the second embodiment of the present invention includes an endothermic material layer 2 and a refractory heat insulating layer 3 laminated on the endothermic material layer 2. The details of the endothermic material layer 2 are the same as those described for the endothermic material layer 2 of the first embodiment. In the present embodiment, the endothermic material layer 2 and the refractory heat insulating layer 3 are integrally molded and fused. The endothermic material layer 2 and the refractory heat insulating layer 3 can be molded by a press or various other molding methods.

The refractory heat insulating layer 3 contains a nonflammable base material having a thickness of 5 μm to 1 mm, more preferably 0.1 mm to 1 mm. Preferably, the endothermic material layer 2 has a thickness of 0.1 to 1 mm, and the refractory heat insulating layer 3 has a thickness of 0.1 to 1 mm. The nonflammable substrate is preferably a nonflammable fiber. With such a configuration, the endothermic component permeates the fiber, and a high temperature rise suppressing effect can be obtained. As a result, the volumetric energy density of the battery can be increased.

Examples of the nonflammable base material used for the refractory heat insulating layer 3 include one type or two or more types of a metal, an inorganic material as an inorganic base material, and the like. Examples of the metal include aluminum, iron, stainless steel, tin, lead, tin-lead alloy, copper and the like.

Further, it is preferable to use a metal foil as the metal, and examples of the metal foil include aluminum foil, iron foil, stainless steel foil, tin foil, lead foil, tin-lead alloy foil, and copper foil.

Examples of non-equipment include glass wool, rock wool, ceramic wool, gypsum fiber, carbon fiber, stainless fiber, slag fiber, silica-alumina fiber, alumina fiber, silica fiber, zirconia fiber and the like. As the inorganic fiber layer, it is preferable to use an inorganic fiber cloth using the inorganic fiber. Further, as the inorganic fiber used for the inorganic fiber layer, it is preferable to use one in which a metal foil is laminated.

As specific examples of the metal foil laminated inorganic fiber, for example, an aluminum foil laminated glass cloth, a copper foil laminated glass cloth and the like are more preferable.

The fire-resistant heat insulating layer 3 may contain both the mineral powder and the flame retardant described with respect to the endothermic material layer 2, or may contain only one of the mineral powder and the flame retardant. It does not have to contain both mineral powder and flame retardant. In one embodiment, the refractory heat insulating layer 3 contains one of a mineral powder and a flame retardant that is not contained in the endothermic material layer 2. With such a configuration, the heat insulating performance or the fire protection performance can be further improved as compared with the case where the thermal runaway prevention sheet is composed of one layer of the endothermic material layer 2.

Further, preferably, the thermal conductivity of the endothermic material layer 2 at 25 ° C. is λ1 and the thermal conductivity of the refractory heat insulating layer 3 at 25 ° C. is λ2.
Equation 0 <λ2 / λ1 <15
Meet. With such a configuration, the rate of temperature rise can be suppressed, and it is possible to make it difficult to transmit the temperature to the adjacent cells. Therefore, it is possible to achieve the effect of suppressing heat conduction and achieving both heat insulating properties. λ2 / λ1 is preferably 0.1 or more. Further, λ2 / λ1 is preferably 10 or less, more preferably 5 or less.

As shown in FIG. 4, a plurality of battery cells 7 (three are shown in the figure) are vertically separated from each other in the housing 6 of the battery module 10 to which the thermal runaway prevention sheet 1 of the second embodiment is installed. They are housed side by side so as to extend in the direction, and a thermal runaway prevention sheet 1 is arranged between adjacent battery cells 7, and the thermal runaway prevention sheet 1 is attached to one surface of the battery cell 7.

Each component in the battery module 10 is as described with respect to FIG.

The thermal runaway prevention sheet 1 of the second embodiment starts an endothermic reaction at 100 to 1000 ° C. when the thermal runaway prevention sheet 1 is heated due to abnormal heat generation or fire, and is composed of phase change, expansion, foaming and curing. At least one structural change selected from the group occurs, forming an endothermic layer between adjacent battery cells 7. Further, when the structural change is phase change, expansion, or foaming, the space serving as a flow path for fire or heat between adjacent battery cells 7 is blocked. Therefore, the thermal runaway prevention sheet 1 functions as a heat insulating layer, and can prevent or suppress heat transfer from a certain battery cell 7 to the adjacent battery cell 7 and continuous explosion, and is continuous to the adjacent battery cell 7. Thermal runaway can be prevented or suppressed, and the safety of the battery cell 7 and the battery module 1 provided with the battery cell 7 is ensured.

Next, the thermal runaway prevention sheet 1 of the third embodiment of the present invention will be described.

Referring to FIG. 5, the thermal runaway prevention sheet 1 of the third embodiment of the present invention includes a refractory heat insulating layer 3 and two endothermic material layers 2 arranged on both sides thereof. That is, the thermal runaway prevention sheet 1 of the third embodiment includes a laminate in which the endothermic material layer 2, the refractory heat insulating layer 3, and the endothermic material layer 2 are laminated in this order. The details of the endothermic material layer 2 and the refractory heat insulating layer 3 are the same as those described for the endothermic material layer 2 of the first embodiment. The thermal runaway prevention sheet 1 of the third embodiment may include other additional layers of 1 or 2.

As shown in FIGS. 2 and 4, the thermal runaway prevention sheet 1 of the third embodiment also prevents or suppresses heat transfer from one battery cell 7 in the battery module 10 to the adjacent battery cell 7 and continuous explosion. Can be constructed to do.

Next, the thermal runaway prevention sheet 1 of the fourth embodiment of the present invention will be described.

Referring to FIG. 6, the thermal runaway prevention sheet 1 of the fourth embodiment of the present invention includes an endothermic material layer 2 and two refractory heat insulating layers 3 arranged on both sides thereof. That is, the thermal runaway prevention sheet 1 of the fourth embodiment includes a laminate in which the refractory heat insulating layer 3, the endothermic material layer 2, and the refractory heat insulating layer 3 are laminated in this order. The details of the endothermic material layer 2 and the refractory heat insulating layer 3 are the same as those described for the endothermic material layer 2 of the first embodiment. The thermal runaway prevention sheet 1 of the fourth embodiment may include other additional layers of 1 or 2.

As shown in FIGS. 2 and 4, the thermal runaway prevention sheet 1 of the fourth embodiment also transfers heat from one battery cell 7 in the battery module 10 to the adjacent battery cell 7, and continuously explodes, and continuously explodes. Can be constructed to prevent or suppress.

FIG. 7 is another example of the battery module 10 on which the thermal runaway prevention sheet 1 of the first embodiment of FIG. 1 is installed. In this embodiment, each battery cell 7 and each thermal runaway prevention sheet 1 (that is, the endothermic material layer 2) are connected to a water cooling system 9 provided with a pipe through which water or a refrigerant flows. Therefore, for example, the battery cell 7 may be heated during operation, but by securing the water cooling system 9, the battery cell 7 in contact with the water cooling system 9 can be dissipated more quickly. In the present embodiment, since each battery cell 7 and each thermal runaway prevention sheet 1 are cooled by the water cooling system 9, the space 8 does not have to exist between the battery cell 7 and each thermal runaway prevention sheet 1.

FIG. 8 is another example of the battery module 10 on which the thermal runaway prevention sheet 1 of the second embodiment of FIG. 3 is installed. Also in this embodiment, each battery cell 7 and each thermal runaway prevention sheet 1 (that is, the endothermic material layer 2) are connected to a water cooling system 9 provided with a pipe through which water or a refrigerant flows. Therefore, for example, the battery cell 7 may be heated during operation, but by securing the water cooling system 9, the battery cell 7 in contact with the water cooling system 9 can be dissipated more quickly. In the present embodiment, since each battery cell 7 and each thermal runaway prevention sheet 1 are cooled by the water cooling system 9, the space 8 does not have to exist between the battery cell 7 and each thermal runaway prevention sheet 1.

The thermal runaway prevention sheet 1 of the third or fourth embodiment shown in FIGS. 5 to 7 may be applied to the battery module 10 as shown in FIGS. 2, 4, 7, and 8.

The battery structure provided with the thermal runaway prevention sheet 1 according to the embodiment of the present invention described above, and an electronic device equipped with such a battery structure are also included in the scope of the present invention.

"Electronic equipment" refers to a machine that converts electrical energy into kinetic energy that performs a specific operation, display, etc. by flowing an electric current through a circuit. Examples thereof include automobiles, electric bicycles, mobile phones, digital cameras, video cameras, electronic organizers, personal computers, radios, music players, storage medium players, storage medium recorders, game consoles, televisions, printers, vacuum cleaners and the like.

The application of the thermal runaway prevention sheet 1 of the present invention is not limited to batteries, and can be used, for example, as a flameproof material for buildings, a coolant for power generation furnaces, and a heat insulating material to be attached to windows.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Hereinafter, the present invention will be described in detail by way of examples with reference to the drawings. The present invention is not limited to these examples.

Thermally expandable graphite "ADT501" manufactured by ADT as a heat-expandable component, "APA-100" manufactured by Taihei Chemical Industry Co., Ltd. as an inorganic foaming component, talc "SG-2000" manufactured by Nippon Tarku Co., Ltd. as a mineral powder, Tomoe Kogyo Aluminum hydroxide "B-303" manufactured by Taihei Kagaku Sangyo Co., Ltd. as a phosphorus-based flame retardant, "AP422" manufactured by Clariant Co., Ltd., and PVC resin "HA" manufactured by Tokuyama Sekisui Kogyo Co., Ltd. as a matrix resin component. -53F ", Mitsui Chemicals'ethylene-propylene-diene rubber" EPT3092M (EPDM) ", Sekisui Chemicals' polyvinyl alcohol" SELVOL ", Shiraishi Calcium's calcium carbonate" BF-300 ", Nippon Seiko Co., Ltd. Antimon trioxide "PATOX-C", J-PLUS plastic agent "DIDP", ADEKA Ca / Zn-based PVC stabilizer "RX-218", Sakai Chemical Industry's calcium stearate "SC-100", Showa Denko Co., Ltd. chlorinated polyethylene "Eraslen", Mitsubishi Chemical Co., Ltd. Metabrene "P-530A", and Kanbow Plus Co., Ltd. aluminum glass cloth were used as nonflammable substrates.

Example 1, Example 2, Comparative Example 1
The thermal runaway prevention sheets of Example 1, Example 2 and Comparative Example 1 were produced from the resin compositions blended with the compositions shown in Table 1. In the table, "-" is not contained. The measured values of each physical property are shown. In the table, "-" indicates that there is no measured value.

Examples 3 to 7, Comparative Example 2
The endothermic material layer (endothermic layer 3-7, comparative endothermic layer 2) and the refractory heat insulating layer (heat insulating layer 3-7, comparative heat insulating layer 2) were blended in the compositions shown in Tables 2 and 3. In the table, "-" is not contained. The measured values of each physical property are shown. In the table, "-" indicates that there is no measured value. The thermal runaway prevention sheet of Examples 3 to 7 and Comparative Example 2 is formed by combining the endothermic material layer prepared in Tables 2 and 3 and the refractory heat insulating layer with the composition shown in Table 4 and processing them to a specified thickness. Got
(Moldability)
A resin composition containing a mineral powder and a flame retardant having the compositions shown in Tables 1 and 2 was supplied to a uniaxial extruder and extruded at 170 to 190 ° C. A thermal runaway prevention sheet of Comparative Example 1 was obtained. Further, by combining the obtained heat-absorbing material layer and the fire-resistant heat insulating layer sheet and pressing or multicolor molding, thermal runaway prevention of Examples 3 to 7 and Comparative Example 2 having a beautiful surface at 170 to 190 ° C. I got a sheet. There was no adhesion of the compound to the screw and the mold after molding, and the moldability was good.
(aspect ratio)
The scale length of the photograph of the heat-expandable graphite was measured using the SEM cross-sectional photograph and converted to calculate the aspect ratio.
(Volume change rate, reaction pressure)
An aluminum plate is placed on a test piece (length 100 mm, width 100 mm, thickness 1.0 mm) prepared from the obtained molded bodies of the heat-expandable fire-resistant resin material of Examples 1 to 7 and Comparative Examples 1 and 2. (Material A1012, tempered H24, thickness 2.0 mm, 56 g) was supplied to an electric furnace, heated at 400 ° C. for 10 minutes, and then the thickness of the test piece was measured. ) / (Thickness of the test piece before heating) was calculated as an index of volume change rate and reaction pressure.
(Residual hardness)
A test piece (length 100 mm, width 100 mm, thickness 1.0 mm) prepared from the obtained thermal runaway prevention sheet was supplied to an electric furnace, heated at 600 ° C. for 30 minutes, and then the expansion ratio was measured after heating. The test piece was supplied to a compression tester (“Finger Filling Tester” manufactured by Kato Tech Co., Ltd.) ^{, compressed with an indenter of 0.25 cm 2} at a rate of 0.1 cm / sec, and the breaking point stress was measured.
(Shape retention of residue)
The above residual hardness is an index of the hardness of the residue after expansion, but since the measurement is limited to the surface portion of the residue, it may not be an index of the hardness of the entire residue. The shape retention was measured as. The shape retention of the residue was measured by holding both ends of the test piece whose expansion ratio was measured by hand and lifting it up, and visually observing the fragility of the residue at that time. The case where the test piece was lifted without collapsing was evaluated as pass (PASS), and the case where the test piece collapsed and could not be lifted was evaluated as fail (FAIL).
(Thermal conductivity)
The thermal conductivity was measured using QTM-500 (manufactured by Kyoto Electronics Industry Co., Ltd.). The shape of the sensor / probe was φ0.8 × needle length 60, and was measured by a comparative method. The thermal runaway prevention sheet was measured for the residue sample heated at 600 ° C. for 30 minutes, and the endothermic material layer and the fire-resistant heat insulating layer were measured for the sheet sample at 25 ° C. (room temperature).
(Thermal runaway test)
Two test pieces (length 150 mm, width 90 mm, thickness 1.0 mm) made from the obtained thermal runaway prevention sheet and three aluminum plates (length 200 mm, width 140 mm, thickness) simulating the exterior material of the battery cell. Prepare 1.0 mm), combine (1) aluminum plate- (2) test piece- (3) aluminum plate- (4) test piece- (5) aluminum plate in this order, and fasten the four corners with screws. , A simulated cell for thermal runaway test. A simulated cell was placed on the ALC plate, and the surface (1) was heated to 400 ° C. in a vertical furnace along the heating curve of ISO834, followed by 10 minutes. When the temperature of the surface of (3) is less than 200 ° C. and there is no penetration to the non-heated surface and no flame is emitted, it is evaluated as pass (PASS), and 200 ° C. or higher or penetration or flame to the unheated surface The case was evaluated as rejected (FAIL).
(Impact resistance)

1 ... Thermal runaway prevention sheet, 2 ... Thermal endothermic material layer, 3 ... Fire resistant heat insulating layer.

Claims (8)

At least one structure selected from the group consisting of phase change, expansion, foaming and hardening by containing at least one of a mineral powder and a flame retardant and starting an endothermic reaction at 100 to 1000 ° C. It is composed of an endothermic material layer that changes and a fire resistant heat insulating layer.
A thermal runaway prevention sheet in which the endothermic material layer has a thickness of 0.1 to 1 mm, and the refractory heat insulating layer contains a nonflammable base material having a thickness of 0.1 to 1 mm. At least one structure selected from the group consisting of phase change, expansion, foaming and hardening by containing at least one of a mineral powder and a flame retardant and starting an endothermic reaction at 100 to 1000 ° C. A thermal runaway prevention sheet composed of an endothermic material layer that undergoes changes and a fire-resistant heat insulating layer.
A thermal runaway prevention sheet in which the sheet includes at least the following three layers (i) or (ii).
(I) The fire-resistant heat insulating layer and two endothermic material layers arranged on both sides thereof.
(Ii) The endothermic material layer and two refractory heat insulating layers arranged on both sides thereof. At least one structure selected from the group consisting of phase change, expansion, foaming and hardening by containing at least one of a mineral powder and a flame retardant and starting an endothermic reaction at 100 to 1000 ° C. It is composed of an endothermic material layer that changes and a fire resistant heat insulating layer.
An integrated thermal runaway sheet in which the fire-resistant heat insulating layer and the endothermic material layer are integrally molded. At least one structure selected from the group consisting of phase change, expansion, foaming and hardening by containing at least one of a mineral powder and a flame retardant and starting an endothermic reaction at 100 to 1000 ° C. It is composed of an endothermic material layer that changes and a fire resistant heat insulating layer.
Assuming that the thermal conductivity of the endothermic material layer at 25 ° C. is λ1 and the thermal conductivity of the refractory heat insulating layer at 25 ° C. is λ2,
Equation 0 <λ2 / λ1 <15
A thermal runaway prevention sheet. The mineral powder contains at least one powder selected from the group consisting of diatomaceous earth, talc, calcium carbonate, aluminum hydroxide, titanium oxide, hirustone (permiculite), zeolite, and white carbon (synthetic silica). ,
The claim includes the flame retardant including at least one powder selected from the group consisting of a brominated flame retardant, a chlorine flame retardant, a phosphorus flame retardant, a boron flame retardant, a silicone flame retardant, and a nitrogen-containing compound. The heat runaway prevention sheet according to any one of 1 to 4. The heat runaway prevention sheet according to any one of claims 1 to 5 , which comprises at least one matrix resin selected from a thermosetting resin, a thermoplastic resin, a thermoplastic elastomer, and rubber. A battery structure provided with the thermal runaway prevention sheet according to any one of claims 1 to 6. An electronic device equipped with the battery structure according to claim 7.

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