JP2018206605A - Thermal runaway prevention sheet - Google Patents

Abstract

To provide a thermal runaway prevention sheet that suppresses heat conduction to adjacent cells when one cell thermally runaway.SOLUTION: A thermal runaway prevention sheet contains at least one of a mineral powder and a flame retardant and starts an endothermic reaction at 100 to 1000°C, and accordingly, at least one structural change selected from the group consisting of phase change, expansion, foaming and curing takes place.SELECTED DRAWING: None

Description

  The present invention relates to a thermal runaway prevention sheet.

  More eco-friendly electric vehicles are becoming popular in order to control global warming and promote a recycling-oriented 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 a cell) increases rapidly and may reach 300 to 400 ° C. or higher. is there. Moreover, if one cell causes a thermal runaway, adjacent cells are likely to cause a thermal runaway, and as a result, a major accident may occur. For this reason, the member which suppresses thermal runaway was calculated | required.

  In order to prevent a plurality of cells from continuously running out of control (hereinafter referred to as continuous explosion), Patent Document 1 describes providing a plastic thermal runaway prevention wall between adjacent secondary batteries. ing. However, the thermal runaway prevention wall of Patent Document 1 is integrally formed with a heat conduction cylinder formed to have a shape equal to the outer shape of the secondary battery for heat dissipation, and the thermal runaway prevention wall is thermally conductive. It has a complex structure that is part of the cylinder.

Patent No. 4958409

  The objective of this invention is providing the thermal runaway prevention sheet | seat, battery structure, and electronic device which suppress the heat conduction to the adjacent cell, when one cell carries out thermal runaway.

In order to solve the above problems, the following aspects of the present invention are provided.
[1] 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 by the endothermic reaction. A type of structural change that prevents thermal runaway.
[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. The flame retardant includes at least one powder selected from the group consisting of bromine-based flame retardants, chlorine-based flame retardants, phosphorus-based flame retardants, boron-based flame retardants, silicone-based flame retardants, and nitrogen-containing compounds. The thermal runaway prevention sheet | seat as described in any one of -3.
[5] The thermal runaway prevention sheet according to any one of items 1 to 4, comprising 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, comprising a heat-absorbing material layer containing at least one of a mineral-based powder and a flame retardant, and a refractory heat-insulating layer. .
[7] A heat-absorbing material layer containing at least one of a mineral-based powder and a flame retardant, and a fire resistance containing one of a mineral-based powder and a flame retardant not included in the heat-absorbing material layer The thermal runaway prevention sheet | seat as described in any one of claim | item 1 -3 comprised from a heat-resistant heat insulation 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 substrate having a thickness of 0.1 to 1 mm.
[9] The thermal runaway prevention sheet according to item 6 or 7, wherein the sheet comprises at least the following three layers (i) or (ii).
(I) The refractory heat-insulating layer and the two heat-absorbing material layers disposed on both sides thereof (ii) The heat-absorbing material layer and the two layers of the refractory heat-insulating layer disposed on both sides thereof [10 The thermal runaway prevention sheet according to any one of Items 6 to 9, wherein the fireproof heat insulating layer and the endothermic material layer are integrally formed.
[11] When the thermal conductivity at 25 ° C. of the endothermic material layer is λ1, and the thermal conductivity at 25 ° C. of the refractory heat insulating layer is λ2,
Formula 0 <λ2 / λ1 <15
The thermal runaway prevention sheet | seat as described in any one of claim | item 6 -9 which is these.
[12] A thermal runaway prevention sheet used between the casings of the battery structure,
The sheet includes an endothermic material layer, and when the cell is thermally runaway, the sheet in contact with the housing expands, foams, or hardens, thereby suppressing thermal runaway and thermal deformation, which suppresses deformation of the housing. Prevention sheet.
[13] A battery structure comprising 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.

  ADVANTAGE OF THE INVENTION According to this invention, high heat insulation performance is expressed with a simple structure, and the continuous thermal runaway of an adjacent cell can be prevented. Since the thermal runaway prevention sheet of the present invention has sufficient heat insulating properties even if it is thin, it can impart excellent heat insulating performance to the battery in the electronic device.

1 is a schematic cross-sectional view showing a thermal runaway prevention sheet according to a first embodiment of the present invention. The schematic longitudinal cross-sectional view of the example of the battery module which constructed the thermal runaway prevention sheet | seat of FIG. The schematic sectional drawing which shows the thermal runaway prevention sheet | seat of 2nd embodiment of this invention. The schematic longitudinal cross-sectional view of the example of the battery module which constructed the thermal runaway prevention sheet | seat of FIG. The schematic sectional drawing which shows the thermal runaway prevention sheet | seat of 3rd embodiment of this invention. The schematic sectional drawing which shows the thermal runaway prevention sheet | seat of 4th embodiment of this invention. FIG. 4 is a schematic longitudinal sectional view of another example of the battery module in which the thermal runaway prevention sheet of FIG. 1 is installed. FIG. 4 is a schematic longitudinal sectional view of another example of a battery module in which the thermal runaway prevention sheet of FIG. 3 is installed.

  In this specification, thermal runaway means that the internal temperature of the battery rises to 60 ° C. or more due to external short circuit, internal short circuit, overcharge, overdischarge, heating, etc., and the chemical reaction inside the battery proceeds and the inside of the battery advances. Refers to the state where the temperature rise of the accelerating is accelerated. In particular, thermal runaway becomes prominent when the internal temperature of the battery is 200 ° C. or higher.

  In this specification, “battery” means 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, It means secondary batteries such as lead-acid batteries and air batteries.

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

  In this specification, the “battery cell” refers to a structural 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 or a negative electrode terminal, and the like are housed in an exterior member. Also simply called “cell”.

  In the case where the battery cell is cylindrical, 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, and the like indicate a structural unit of a battery accommodated in an outer can.

  When the battery cell is rectangular, the positive electrode material, the negative electrode material, the separator, the positive electrode terminal, the negative electrode terminal, the insulating material, the gas discharge valve, and the like refer to the structural unit of the battery accommodated in the outer can.

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

  In this specification, “battery module” refers to a structural unit of a battery in which a plurality of battery cells are accommodated in a casing, and “battery pack” refers to a unit in which a plurality of battery modules are accommodated in a casing. In addition to the battery cell, a necessary member such as an electric connection cable electrically connected to the battery cell is used as needed inside the battery pack and the battery.

  Embodiments of the present invention will be described below 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-based powder is at least one selected from the group consisting of diatomaceous earth, talc, calcium carbonate, aluminum hydroxide, titanium oxide, hiruishi (also called permiculite), zeolite, and white carbon (also called synthetic silica). Examples include powders. These mineral-based 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-based powder can be used alone, or two or more can be used in combination.

  Examples of the flame retardant include at least one flame retardant selected from the group consisting of bromine-based flame retardants, chlorine-based flame retardants, phosphorus-based flame retardants, boron-based flame retardants, silicone-based flame retardants, and nitrogen-containing compounds. A flame retardant can be used individually by 1 type or in combination of 2 or more types.

  Brominated flame retardants suppress combustion by generating brominated gases and blocking oxygen. Examples of brominated flame retardants include tetrabromobisphenol A, decabromobiphenyl, pentabromodiphenyl ether, and the like.

  Chlorine flame retardant suppresses combustion by generating chlorine gas and blocking oxygen. Examples of the chlorinated flame retardant include chlorinated paraffin and chlorinated polyethylene.

  The phosphorus flame retardant blocks oxygen and heat by forming a carbonized layer. Examples of phosphorus flame retardants include phosphate esters and ammonium polyphosphate.

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

  The silicone-based flame retardant forms a Si—C inorganic heat insulating layer. A silicone resin etc. are mentioned as a silicone type flame retardant.

  The nitrogen-containing compound blocks 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 flame retardant.

  The endothermic material layer 2 can contain at least one matrix resin selected from a thermosetting resin, a thermoplastic resin, a thermoplastic elastomer, and rubber.

  Examples of the thermoplastic resin include polypropylene resins, polyethylene resins, poly (1-) butene resins, polyolefin resins such as polypentene resins, polyester resins such as polyethylene terephthalate, polystyrene resins, acrylonitrile-butadiene-styrene (ABS) resins, 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), novolac 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 elastomers include olefin elastomers, styrene elastomers, ester elastomers, amide elastomers, vinyl chloride elastomers, combinations thereof, and the like.

  Rubber materials 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, ethylene-propylene-diene rubber (EPDM). ), Rubber materials such as chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polyvulcanized rubber, non-vulcanized rubber, silicon rubber, fluorine rubber, and urethane rubber.

  These synthetic resins and / or rubber substances can be used singly or in combination.

  Among these synthetic resins and / or rubber substances, PVC and EVA are preferable in terms of moldability. In order to obtain flexible and rubber-like properties, non-vulcanized rubber such as butyl rubber and polyolefin resin are preferable. From the viewpoint of fire resistance, PVC is preferable. From the viewpoint of increasing the flame retardancy of the resin itself and improving the fire prevention performance, an epoxy resin is preferable.

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

  Due to the presence of the matrix resin, it is possible to suppress the collapse of the expansion structure during expansion and increase the strength of the residual hardness. Moreover, the durability with respect to the decay | disintegration of the residue by heat | fever can be provided. As a result, the temperature increase rate of the endothermic material layer 2 can be suppressed.

  Since aluminum hydroxide undergoes a phase change in the crystal structure from about 200 ° C. and undergoes an endothermic reaction by dehydration and decomposition, the temperature rise of the cell can be suppressed.

The endothermic material layer 2 can further contain an expandable material.
The inflatable material functions to form a heat insulating layer and close a space that becomes a flow path of fire and heat.

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

  The heat-expandable microcapsule has a temperature below the softening point of the polymer in a shell formed from a plastic polymer obtained by polymerizing a composition containing one or more types of monomers and a crosslinking agent. It contains a volatile swelling agent that becomes gaseous. For example, the shell is made of a polymer obtained by polymerizing a monomer mixture containing 95% by weight or more of (meth) acrylonitrile, 70% by weight or more in (meth) acrylonitrile being acrylonitrile, and the degree of crosslinking is 60% by weight or more. A thermally expandable microcapsule is described in WO 2010/052972. When the polymer contains monomers other than (meth) acrylonitrile, such monomers include monomers selected from the group consisting of methacrylic acid esters, acrylic acid esters, styrene, vinylidene chloride and vinyl acetate.

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

Examples of the low-boiling organic solvent include ethane, ethylene, propane, propene, n-butane, isobutane, n-butene, isobutene, n-pentane, isopentane, neopentane, n-hexane, heptane, nonane, decane, petroleum Hydrocarbons such as ether; chlorofluorocarbons such as CCl ₃ F, CCl ₂ F ₂ , CClF ₃ , CClF ₂ —CCl ₂ F ₂ ; tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, trimethyl-n-propylsilane, etc. Tetraalkylsilane and the like can be mentioned, and preferably used. Among them, hydrocarbons such as n-butane, isobutane, n-pentane, isopentane, n-hexane, nonane, decane and petroleum ether can be used. Carbon numbers from 3 to 12 are used. Further, straight chain hydrocarbons and esters may also be used. Particularly preferred are hydrocarbons having 4 or more carbon atoms. These low boiling point organic solvents may be used alone or in combination of two or more.

  The microcapsule containing water is the above-described microcapsule enclosing water.

  Examples of the foaming agent include inorganic foaming agents, organic foaming agents, and combinations 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, isopentane, neopentane, n-hexane, heptane, nonane, decane, petroleum ether, and the like. Hydrocarbons containing azo compounds such as azodicarbonamide (ADCA) and azodiaminobenzene; nitroso compounds such as dinitrosopentamethylenetetramine (DPT) and N, N'-dinitroso-N, N'-dimethylterephthalamide Containing foaming agents; sulfonyl hydrazide-containing foaming agents such as benzenesulfonyl hydrazide, p, p′-oxybisbenzenesulfonyl hydrazide (OBSH), hydrazodicarbonamide (HDCA), and the like. One or more of these organic foaming agents can be used in combination.

  The microencapsulated foaming agent is one in which one or more of the above foaming agents are encapsulated in a microcapsule. As the synthetic resin used for the microcapsule, for example, a thermoplastic synthetic resin having a viscosity that melts when the temperature reaches a certain temperature or more and expands into a substantially spherical shape without breaking the microcapsule may be used.

  By adding a microencapsulated foaming agent to the thermal runaway prevention sheet 1 (and the endothermic material layer 2), the thermal 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 thermal runaway prevention sheet 1 (and the endothermic material layer 2) can be foamed.

  The heat-expandable layered inorganic material expands when heated, and is not particularly limited. Examples thereof include vermiculite, kaolin, mica, and heat-expandable graphite. Thermally expandable graphite is a conventionally known substance that expands when heated, and powders such as natural scaly graphite, pyrolytic graphite, and quiche graphite are mixed with inorganic acids such as concentrated sulfuric acid, nitric acid, and selenic acid, concentrated nitric acid, excess A graphite intercalation compound produced by treatment with a strong oxidizing agent such as chloric acid, perchlorate, permanganate, dichromate, dichromate, hydrogen peroxide, etc. A type of crystalline compound that maintains its structure.

  The heat-expandable graphite obtained by 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 expansive material is usually 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the resin component. The thermal runaway prevention sheet 1 (and the endothermic material layer 2) starts to expand 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 Adjust to about 3 to 30 times. Moreover, according to this composition, the thermally expansible sheet formed from the thermal runaway prevention sheet 1 (and the endothermic material layer 2) is expanded by heating such as heat generation of the battery, and a necessary volume expansion coefficient can be obtained. In addition, after expansion, a residue having a predetermined heat insulation performance and a predetermined strength can be formed, and a stable fireproof performance can be achieved. Moreover, the thermal runaway prevention sheet 1 (and the endothermic material layer 2) can be designed to start expansion even at a relatively low temperature by using an expandable material having a low expansion start temperature.

  The endothermic material layer 2 can further contain a plasticizer.

If the said plasticizer is a plasticizer generally used when manufacturing a polyvinyl chloride resin molded object, it will not specifically limit. Specifically, for example, phthalate plasticizers such as di-2-ethylhexyl phthalate (DOP), dibutyl phthalate (DBP), diheptyl phthalate (DHP), diisodecyl phthalate (DIDP),
Fatty acid ester plasticizers such as di-2-ethylhexyl adipate (DOA), diisobutyl adipate (DIBA) and dibutyl adipate (DBA); Epoxidized ester plasticizers such as epoxidized soybean oil; Polyesters such as adipic acid esters and adipic acid polyesters Examples include plasticizers; trimellitic acid ester plasticizers such as tri-2-ethylhexyl trimellitate (TOTM) and triisononyl trimellitate (TINTM); and process oils such as mineral oil. One or more plasticizers can be used.

  When the content of the plasticizer is small, the injection moldability, extrusion moldability and the like tend to be lowered, and when the content is increased, the obtained molded product tends to be too soft. For this reason, although content of a plasticizer is not limited, it is preferable that it is 0-40 mass% in the endothermic material layer 2, More preferably, it is 5-35 mass%.

  In the endothermic material layer 2, various additive components can be contained as necessary within a range where the object of the present invention is not impaired. The kind of the 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, cell nucleating agents, crystal nucleating agents, plasticizers, colorants (pigments, dyes, etc.), ultraviolet absorbers, antioxidants, anti-aging agents, and the above heat conduction agents. Examples include fillers excluding the body, reinforcing agents, flame retardants, flame retardant aids, antistatic agents, surfactants, vulcanizing agents, and surface treatment agents. The addition amount of the additive can be appropriately selected within a range that does not impair the formation of bubbles and the like, and the addition amount used for normal resin foaming and molding can be adopted. Such additives can be used alone or in combination of two or more.

  Although the thickness of the thermal runaway prevention sheet | seat of this invention is not specifically limited, It is preferable that it is 0.1 mm-1 mm. The “thickness” of the thermal runaway prevention sheet referred to in this specification refers to an average thickness of 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 curing in accordance with an endothermic reaction.

  “Phase change” means that a phase that is a uniform part of chemical and physical properties is changed into a different phase such as liquid phase, solid phase, gas phase, plasma phase, crystal structure phase, etc. by external stimulus change such as temperature and pressure. Refers to metastasis. For example, aluminum hydroxide is a white powder crystal that is stable up to about 200 ° C., and at a temperature higher than that, dissociation reaction of water of crystallization occurs, separating 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 and decrease. For example, when heat-expandable graphite is heated to about 100 to 300 ° C., an acid between graphite layers is released, and the volume of graphite expands to about 3 to 100 times.

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

  “Curing” refers to the condition becoming stiff. It becomes hard due to crosslinking by the reaction with the curing agent or polymerization reaction. Its hardness depends on 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. For this reason, by ensuring the distance between the adjacent cells by the thermal runaway prevention sheet 1, it is possible to suppress the heat due to the thermal runaway of one cell from being transmitted to the adjacent cells, and thus to the continuous 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 that the endothermic material layer 2 receives due to the structural change caused by the endothermic reaction. When the structural change is hardening, the volume change rate is 100% or less due to hardening shrinkage, the endothermic material layer 2 is not pushed, and the reaction pressure is almost 0 MPa. The volume change rate when the structural change is curing 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 5 MPa or less. When the structural change is phase change, expansion, or foaming, the volume change rate is more than 100% and 500% or less.

  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 preferable.

  Thus, since the endothermic material layer 2 is cured or has an increased volume, the thermal runaway prevention sheet 1 can ensure the distance between adjacent cells more reliably.

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

  The thermal runaway prevention sheet comprises at least one of the above matrix components, mineral powders and flame retardants, and optional other components, a single screw extruder, a twin screw extruder, an injection molding machine, a Banbury mixer, a kneader. It can be manufactured by coating or molding a composition mixed using a known apparatus such as a mixer, a kneading roll, a lye machine, a planetary stirrer or the like. 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 on which the thermal runaway prevention sheet 1 of the first embodiment is applied. The thermal runaway prevention sheet 1 is disposed between the adjacent battery cells 7 so as to extend in the direction, 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 side (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. For example, there may be mentioned a method in which the battery cell 7 and the thermal runaway prevention sheet 1 are laminated and fixed using a frame after the material is pasted or fixed by the self-adhesiveness of the thermal runaway prevention sheet 1.

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

  The case 6 is, for example, a metal or resin molded case, but is not limited thereto. The battery cell 7 and the thermal runaway prevention sheet 1 are flat rectangular parallelepipeds 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 functions as an air passage for heat dissipation of the battery cell 7. For example, the battery cell 7 may be heated at the time of operation, but the battery cell 7 can dissipate heat faster by securing the space 8.

  The thermal runaway prevention sheet 1 is selected from the group consisting of phase change, expansion, foaming, and curing when the thermal runaway prevention sheet 1 is heated due to abnormal heat generation or a fire or the like and starts an endothermic reaction at 100 to 1000 ° C. At least one structural change occurs, and a heat insulating layer is formed between adjacent battery cells 7. Further, when the structural change is a phase change, expansion, or foaming, a space that becomes a fire or heat flow path between adjacent battery cells 7 is closed. For this reason, the thermal runaway prevention sheet 1 functions as a heat insulating layer, can prevent or suppress heat transfer from one battery cell 7 to the adjacent battery cell 7 and continuous explosion, and can continue 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 including the battery cell 7 is ensured.

  Thus, it is the thermal runaway prevention sheet 1 used between the housings of the battery structure, and the sheet 1 includes the endothermic material layer 2, and the sheet 1 in contact with the housing expands when the cell undergoes thermal runaway. The thermal runaway prevention sheet 1 that suppresses thermal runaway and suppresses deformation of the casing by foaming or curing is included in the scope of the present invention.

  Note that the casing means a unit cell including a unit cell in which a positive electrode terminal and a negative electrode terminal are arranged in opposite directions, an insulating member that covers each of these unit cells, and an exterior material. Refers to a cell.

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

  Next, the thermal runaway prevention sheet 1 of 2nd embodiment of this invention is demonstrated.

  Referring to FIG. 3, the thermal runaway prevention sheet 1 according to 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 formed by pressing or other various forming methods.

  The refractory heat insulation 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 thickness of the endothermic material layer 2 is 0.1 to 1 mm, and the thickness of the refractory heat insulating layer 3 is 0.1 to 1 mm. The nonflammable substrate is preferably a nonflammable fiber. By setting it as such a structure, an endothermic component osmose | permeates a fiber and there exists a high temperature rising suppression effect. As a result, the volume energy density of the battery can be increased.

  As a nonflammable base material used for the fireproof heat insulation layer 3, 1 type, or 2 or more types, such as a metal and an inorganic material as an inorganic base material, can be mentioned. Examples of the metal include aluminum, iron, stainless steel, tin, lead, tin-lead alloy, and copper.

  Moreover, it is preferable to use metal foil as a 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 the inorganic material include glass wool, rock wool, ceramic wool, gypsum fiber, carbon fiber, stainless steel fiber, slag fiber, silica alumina fiber, alumina fiber, silica fiber, and zirconia fiber. The inorganic fiber layer preferably uses an inorganic fiber cloth using the inorganic fiber. Moreover, it is preferable to use what laminated the metal foil for the inorganic fiber used for an inorganic fiber layer.

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

  The refractory heat insulating layer 3 may include both the mineral powder and the flame retardant described with respect to the endothermic material layer 2, or may include only one of the mineral powder and the flame retardant, Both mineral powder and flame retardant may not be included. In one embodiment, the refractory heat insulating layer 3 contains one of a mineral-based powder and a flame retardant that are not included in the heat-absorbing material layer 2. With such a configuration, the heat insulation performance or the fire prevention 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.

Preferably, the thermal conductivity at 25 ° C. of the endothermic material layer 2 is λ1, and the thermal conductivity at 25 ° C. of the refractory heat insulating layer 3 is λ2.
Formula 0 <λ2 / λ1 <15
Meet. By setting it as such a structure, a temperature increase rate can be suppressed and it can be hard to tell temperature to an adjacent cell. Therefore, the effect of achieving both heat conduction suppression and heat insulation can be achieved. λ2 / λ1 is preferably 0.1 or more. 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 on which the thermal runaway prevention sheet 1 of the second embodiment is applied. The thermal runaway prevention sheet 1 is disposed between the adjacent battery cells 7 so as to extend in the direction, 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 reference 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, and a heat insulating layer is formed between adjacent battery cells 7. Further, when the structural change is a phase change, expansion, or foaming, a space that becomes a fire or heat flow path between adjacent battery cells 7 is closed. For this reason, the thermal runaway prevention sheet 1 functions as a heat insulating layer, can prevent or suppress heat transfer from one battery cell 7 to the adjacent battery cell 7 and continuous explosion, and can continue 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 including the battery cell 7 is ensured.

  Next, the thermal runaway prevention sheet 1 of 3rd embodiment of this invention is demonstrated.

  Referring to FIG. 5, the thermal runaway prevention sheet 1 according to the third embodiment of the present invention includes a refractory heat insulating layer 3 and two endothermic material layers 2 disposed 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 fireproof 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 one or two other additional layers.

  As shown in FIGS. 2 and 4, the thermal runaway prevention sheet 1 according to 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 4th embodiment of this invention is demonstrated.

  Referring to FIG. 6, the thermal runaway prevention sheet 1 according to the fourth embodiment of the present invention includes an endothermic material layer 2 and two refractory heat-insulating layers 3 disposed on both sides thereof. That is, the thermal runaway prevention sheet 1 according to 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 1 or 2 other additional layers.

  As shown in FIGS. 2 and 4, the thermal runaway prevention sheet 1 of the fourth embodiment is also used for heat transfer from one battery cell 7 in the battery module 10 to the adjacent battery cell 7, continuous explosion, and continuous explosion. It 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 constructed. 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 having a pipe through which water or refrigerant flows. Therefore, for example, the battery cell 7 may be heated at the time of operation, but by securing the water cooling system 9, the battery cell 7 in contact with the water cooling system 9 can be radiated faster. 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 may not 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 applied. 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 including a pipe through which water or refrigerant flows. Therefore, for example, the battery cell 7 may be heated at the time of operation, but by securing the water cooling system 9, the battery cell 7 in contact with the water cooling system 9 can be radiated faster. 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 may not 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.

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

  An “electronic device” refers to a machine that converts electrical energy into kinetic energy that performs a specific operation, display, or the like when current flows through a circuit. For example, a car, an electric bicycle, a mobile phone, a digital camera, a video camera, an electronic notebook, a personal computer, a radio, a music player, a storage medium player, a storage medium recorder, a game machine, a television, a printer, a vacuum cleaner, and the like can be given.

  The use of the thermal runaway prevention sheet 1 of the present invention is not limited to a battery, and can be used, for example, as a flameproofing material for buildings, a coolant for a power generation furnace, and a heat insulating material attached to a window.

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

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited at all by these Examples.

  Thermally expandable graphite “ADT501” manufactured by ADT as thermal expandable component, “APA-100” manufactured by Taihei Chemical Industry Co., Ltd. as inorganic foam component, talc “SG-2000” manufactured by Nippon Talc Co., Ltd., Sakai Industry Aluminum hydroxide “B-303” manufactured by the company, “TAIEN-E” manufactured by Taihei Chemical Industry Co., Ltd., “AP422” manufactured by Clariant Co., Ltd., and PVC resin “HA” manufactured by Tokuyama Sekisui Industry Co., Ltd. as the matrix resin component -53F ", ethylene-propylene-diene rubber" EPT3092M (EPDM) "manufactured by Mitsui Chemicals, polyvinyl alcohol" SELVOL "manufactured by Sekisui Chemical Co., Ltd., calcium carbonate" BF-300 "manufactured by Shiraishi Calcium Co., Ltd., Nippon Seiko Co., Ltd. Antimony trioxide “PATOX-C”, plasticizer “DIDP” manufactured by JPLUS, ADE KA Co./Zn-based PVC stabilizer “RX-218”, Sakai Chemical Industry Co., Ltd. calcium stearate “SC-100”, Showa Denko Co., Ltd., chlorinated polyethylene “Elaslene”, Mitsubishi Chemical Co., Ltd. “Metablene” P-530A "Aluminum glass cloth manufactured by Kanbo Plus Co., Ltd. was used as the non-combustible substrate.

Example 1, Example 2, Comparative Example 1
From the resin composition blended with the composition shown in Table 1, thermal runaway prevention sheets of Example 1, Example 2 and Comparative Example 1 were produced. In the table, “-” means not contained. Each physical property measurement value is shown. In the table, “-” indicates that there is no measurement value.

Examples 3-7, Comparative Example 2
A heat-absorbing material layer (endothermic layer 3-7, comparative heat-absorbing layer 2) and a 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, “-” means not contained. Each physical property measurement value is shown. In the table, “-” indicates that there is no measurement value. The thermal endothermic material layer and the refractory heat insulation layer produced in Table 2 and Table 3 are combined with the composition shown in Table 4, and processed to the specified thickness, thereby preventing thermal runaway prevention sheets of Examples 3 to 7 and Comparative Example 2. Got.
(Moldability)
A resin composition containing a mineral powder and a flame retardant having the composition shown in Tables 1 and 2 is supplied to a single screw extruder and extruded at 170 to 190 ° C., and Examples 1, 2 and The thermal runaway prevention sheet of Comparative Example 1 was obtained. In addition, by combining the obtained heat-absorbing material layer and fire-resistant heat insulating layer sheet, press working or multicolor molding, the thermal runaway prevention of Examples 3 to 7 and Comparative Example 2 having a beautiful surface at 170 to 190 ° C. A sheet was obtained. There was no adhesion of the compound to the screw and mold after molding, and the moldability was good.
(aspect ratio)
Using the SEM cross-sectional photograph, the scale length of the thermally expandable graphite photograph was measured and converted to calculate the aspect ratio.
(Volume change rate, reaction pressure)
On the test piece (length 100mm, width 100mm, thickness 1.0mm) produced from the molded body of the heat-expandable refractory resin material of Examples 1-7 and Comparative Examples 1-2 obtained, an aluminum plate (Material A1012, tempered H24, thickness 2.0 mm, 56 g) was supplied to an electric furnace and heated at 400 ° C. for 10 minutes, and then the thickness of the test piece was measured. ) / (Thickness of test piece before heating) was calculated as an index of volume change rate and reaction pressure.
(Residue 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 and heated at 600 ° C. for 30 minutes, and then the expansion ratio was measured. The test piece was supplied to a compression tester (manufactured by Kato Tech Co., Ltd., “Finger Filling Tester”), compressed with a 0.25 cm ² indenter at a speed of 0.1 cm / sec, and the stress at break was measured.
(Residue shape retention)
The above residue hardness is an indicator 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 indicator of the hardness of the entire residue, so an indicator of the hardness of the entire residue As a result, the shape retention was measured. The shape retention of the residue was measured by holding both ends of the test piece for which the expansion ratio was measured by hand and visually observing how easily the residue collapses. The case where the test piece was lifted without collapsing was evaluated as pass (PASS), and the case where the test piece was collapsed and was not lifted was evaluated as fail (FAIL).
(Thermal conductivity)
Thermal conductivity was measured using QTM-500 (manufactured by Kyoto Electronics Industry Co., Ltd.). The sensor / probe shape was measured by a comparative method using φ0.8 × needle length 60. The thermal runaway prevention sheet was measured for the residue sample heated at 600 ° C. for 30 minutes, and the heat endothermic material layer and the refractory heat insulation 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) prepared from the obtained thermal runaway prevention sheet and three aluminum plates (length 200 mm, width 140 mm, thickness) simulating the battery cell exterior material (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 This was a simulated cell for a thermal runaway test. A simulated cell was placed on the ALC plate and heated in a vertical furnace along the ISO 834 heating curve until the surface of (1) reached 400 ° C., followed by 10 minutes. When the surface temperature of (3) is less than 200 ° C. and there is no penetration to the non-heated surface and there is no flame out, it is evaluated as a pass (PASS), and 200 ° C. or higher, or the non-heated surface penetrates or goes out. The case was evaluated as FAIL.
(Impact resistance)

  DESCRIPTION OF SYMBOLS 1 ... Thermal runaway prevention sheet, 2 ... Heat endothermic material layer, 3 ... Fireproof heat insulation layer.

Claims (14)

  At least one structure selected from the group consisting of phase change, expansion, foaming, and hardening, containing at least one of a mineral powder and a flame retardant, starting an endothermic reaction at 100 to 1000 ° C. Thermal runaway prevention sheet that changes.   The thermal runaway prevention sheet according to claim 1, wherein the volume change rate due to structural change is 80% to 500% or the reaction pressure is 0 to 5 MPa.   The thermal runaway prevention sheet according to claim 1 or 2, wherein the thermal conductivity λ at 400 ° C is 0.1 W / m · K or less. The mineral powder includes 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). ,
The flame retardant comprises at least one powder selected from the group consisting of brominated flame retardants, chlorinated flame retardants, phosphorus flame retardants, boron flame retardants, silicone flame retardants, and nitrogen-containing compounds. The thermal runaway prevention sheet | seat as described in any one of 1-3.   The thermal runaway prevention sheet according to any one of claims 1 to 4, comprising at least one matrix resin selected from a thermosetting resin, a thermoplastic resin, a thermoplastic elastomer, and rubber.   The thermal runaway prevention sheet as described in any one of Claims 1-3 comprised from the heat | fever endothermic material layer containing at least one of mineral type powder and a flame retardant, and a fireproof heat insulation layer.   A heat-absorbing material layer containing at least one of a mineral-based powder and a flame retardant, and a fire-resistant heat-insulating layer containing one of a mineral-based powder and a flame retardant not included in the heat-absorbing material layer The thermal runaway prevention sheet as described in any one of Claims 1-3 comprised from these.   The thermal runaway prevention sheet according to claim 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. The thermal runaway prevention sheet according to claim 6 or 7, wherein the sheet comprises at least the following three layers (i) or (ii).
(I) The refractory heat insulating layer and the two heat-absorbing material layers disposed on both sides thereof (ii) The heat-absorbing material layer and the two layers of the refractory heat-insulating layer disposed on both sides thereof   The thermal runaway prevention sheet according to any one of claims 6 to 9, wherein the fireproof heat insulating layer and the endothermic material layer are integrally formed. When the thermal conductivity at 25 ° C. of the endothermic material layer is λ1, and the thermal conductivity at 25 ° C. of the refractory heat insulating layer is λ2,
Formula 0 <λ2 / λ1 <15
The thermal runaway prevention sheet according to any one of claims 6 to 9. A thermal runaway prevention sheet used between the casings of the battery structure,
The sheet includes an endothermic material layer, and when the cell is thermally runaway, the sheet in contact with the housing expands, foams, or hardens, thereby suppressing thermal runaway and thermal deformation, which suppresses deformation of the housing. Prevention sheet.   The battery structure provided with the thermal runaway prevention sheet as described in any one of Claims 1-12.   An electronic device equipped with the battery structure according to claim 13.