WO2022249890A1 - 二次電池 - Google Patents

二次電池 Download PDF

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Publication number
WO2022249890A1
WO2022249890A1 PCT/JP2022/020015 JP2022020015W WO2022249890A1 WO 2022249890 A1 WO2022249890 A1 WO 2022249890A1 JP 2022020015 W JP2022020015 W JP 2022020015W WO 2022249890 A1 WO2022249890 A1 WO 2022249890A1
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WO
WIPO (PCT)
Prior art keywords
heat storage
storage sheet
secondary battery
storage material
resin
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2022/020015
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English (en)
French (fr)
Japanese (ja)
Inventor
健一 藤崎
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DIC Corp
Original Assignee
DIC Corp
Dainippon Ink and Chemicals Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by DIC Corp, Dainippon Ink and Chemicals Co Ltd filed Critical DIC Corp
Priority to JP2023511954A priority Critical patent/JP7388596B2/ja
Publication of WO2022249890A1 publication Critical patent/WO2022249890A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/61—Types of temperature control
    • H01M10/613—Cooling or keeping cold
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/61—Types of temperature control
    • H01M10/617—Types of temperature control for achieving uniformity or desired distribution of temperature
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/659—Means for temperature control structurally associated with the cells by heat storage or buffering, e.g. heat capacity or liquid-solid phase changes or transition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/183—Sealing members
    • H01M50/186—Sealing members characterised by the disposition of the sealing members
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to secondary batteries.
  • the temperature of the battery rises due to heat generated during high-speed charging or high-power discharging, it will lead to destabilization of the electrolyte and shortened battery life, leading to significant performance degradation. If the temperature exceeds 80° C., the battery may be damaged. For this reason, a cooling mechanism is essential, which requires a large-scale device and the like, which leads to an increase in the size of the battery. Furthermore, as ultra-high-speed charging progresses in the future, it is predicted that the amount of heat generated will increase, and there is a demand for the development of a temperature rise suppression method that does not rely solely on electric power.
  • Patent Document 1 discloses an in-vehicle assembled battery (secondary battery) having a configuration in which a heat storage sheet is sandwiched between single cells.
  • a secondary battery of the present invention comprises a positive electrode having a positive electrode terminal, a negative electrode having a negative electrode terminal, a separator interposed between the positive electrode and the negative electrode, and an electrolyte held in the separator.
  • at least one cell comprising a battery stack comprising; a case for housing the unit cell; and a first heat storage sheet that is fixed to the inner surface of the case and contains a first heat storage material.
  • the melting point of the first heat storage material is preferably -30°C or higher and 15°C or lower.
  • the content of the first heat storage material in the first heat storage sheet is 10 to 90% by mass.
  • the thickness of the first heat storage sheet is preferably 100-6000 ⁇ m.
  • the first heat storage sheet is made of foam containing the first heat storage material.
  • the secondary battery of the present invention further includes a second heat storage sheet disposed inside the first heat storage sheet and containing a second heat storage material having a higher melting point than the first heat storage material.
  • the secondary battery of the present invention includes a plurality of the cells, It is preferable that the second heat storage sheet is arranged so as to separate the adjacent unit cells.
  • each unit cell is covered with the second heat storage sheet with the positive electrode terminal and the negative electrode terminal exposed.
  • the melting point of the second heat storage material is preferably more than 15°C and 60°C or less.
  • the content of the second heat storage material in the second heat storage sheet is preferably 10-90% by mass.
  • the thickness of the second heat storage sheet is preferably 100-6000 ⁇ m.
  • the secondary battery of the present invention includes a plurality of the single cells each including the battery stack in a wound state, Each of the cells is preferably housed in the case with its longitudinal direction as the thickness direction of the case. (13) In the secondary battery of the present invention, it is preferable that the cell further includes a sealing body that seals the battery stack with the positive electrode terminal and the negative electrode terminal exposed.
  • FIG. 1 is a perspective view showing a first embodiment of a secondary battery of the invention
  • FIG. FIG. 2 is a partial cross-sectional view of the unit cell cut along line AA in FIG. 1
  • FIG. 10 is a partial cross-sectional view showing another configuration of the cell
  • FIG. 4 is a cross-sectional view showing a second embodiment of the secondary battery of the present invention
  • FIG. 5 is an exploded perspective view of a battery stack according to a second embodiment
  • FIG. 6 is a partially cutaway perspective view showing a third embodiment of the secondary battery of the present invention
  • It is a graph which shows the result of the simulation experiment of temperature-drop suppression. It is a graph which shows the result of the simulation experiment of temperature rise suppression.
  • FIG. 1 is a perspective view showing a first embodiment of the secondary battery of the present invention
  • FIG. 2 is a partial cross-sectional view of the cell taken along line AA in FIG. 1
  • FIG. 4] is a partial cross-sectional view showing another configuration of a cell.
  • a secondary battery 100 shown in FIG. 1 is, for example, a secondary battery mounted in a vehicle or the like, and includes a plurality of cells 1 and a case 10 that houses the cells 1 .
  • Each unit cell 1 is, as shown in FIG. It has a battery stack 9 that includes a separator 4 that has been sealed and an electrolyte that is held by the separator 4 .
  • the battery stack 9 is sealed with a sealing body 5 with the positive electrode tab 29 and the negative electrode tab 39 exposed.
  • the positive electrode 2 of this embodiment has a positive electrode current collector (aluminum foil or the like) 21 and positive electrode active material layers 22 provided on both sides of the positive electrode current collector 21 .
  • a positive electrode tab 29 is joined to the portion of the positive electrode current collector 21 exposed from the positive electrode active material layer 22 .
  • the positive electrode tab 29 is composed of a metal piece (copper piece, aluminum piece, nickel piece, etc.). The positive electrode tab 29 may be formed by processing the positive electrode current collector 21 .
  • the positive electrode active material layer 22 contains, for example, a positive electrode active material and a conductive aid.
  • the positive electrode active material include, but are not particularly limited to, lithium metal oxide compounds such as lithium cobaltate, lithium nickelate, and lithium manganate, sodium layered compounds, and the like. One of these lithium metal oxide compounds or sodium layered compounds may be used alone, or two or more thereof may be used in combination.
  • conductive aids include, but are not particularly limited to, graphene, carbon black, and the like.
  • the positive electrode active material layer 22 may contain a binder (binding polymer) such as polyvinylidene fluoride, if necessary.
  • the negative electrode 3 of this embodiment has a negative electrode current collector (copper foil or the like) 31 and negative electrode active material layers 32 provided on both sides of the negative electrode current collector 31 .
  • a negative electrode tab 39 is bonded to the portion of the negative electrode current collector 31 exposed from the negative electrode active material layer 32 .
  • the negative electrode tab 39 is composed of a metal piece (copper piece, aluminum piece, nickel piece, etc.). The negative electrode tab 39 may be formed by processing the negative electrode current collector 31 .
  • the negative electrode active material layer 32 contains, for example, a negative electrode active material and a conductive aid.
  • the negative electrode active material include, but are not particularly limited to, carbon-based materials such as graphite (black lead), hard carbon, and soft carbon. These carbon-based materials may be used singly or in combination of two or more.
  • Examples of conductive aids include, but are not limited to, carbon nanotubes.
  • the negative electrode active material layer 32 may contain a binder (binding polymer) such as polyvinylidene fluoride, if necessary.
  • a separator 4 is interposed between the positive electrode 2 and the negative electrode 3 .
  • the separator 4 has a function of preventing a short circuit between the positive electrode 2 and the negative electrode 3 and a function of retaining an electrolyte.
  • the separator 4 holding the electrolyte can also be called an electrolyte layer.
  • the separator 4 may be made of a sheet material having a plurality of pores or a porous film such as a non-woven fabric, as long as the separator 4 has insulating properties and can retain an electrolyte.
  • the constituent material of the porous membrane include polyolefins such as polypropylene and polyethylene.
  • the electrolyte is preferably used as an electrolytic solution dissolved in a non-aqueous solvent.
  • the electrolyte (electrolyte solution) functions as a transfer medium for metal ions during charging and discharging of the cell 1 .
  • non-aqueous solvents include propylene carbonate and ethylene carbonate. These non-aqueous solvents may be used alone or in combination of two or more.
  • electrolytes include salts of lithium and fluoride such as lithium tetrafluoroborate and lithium hexafluorophosphate, and salts of sodium and fluoride such as sodium hexafluorophosphate.
  • electrolyte polymer can also be used for electrolyte.
  • the sealing body 5 can be composed of a laminate (laminate film) of a metal foil and a resin sheet, a metal can body, or the like.
  • a secondary battery 100 of the present embodiment is configured by housing a plurality of such cells 1 in a case 10 .
  • the case 10 can be made of, for example, a metal material such as aluminum, iron, or an alloy containing these, a resin material such as polyphenylene sulfide, or the like.
  • the case 10 is a box-shaped member having a bottom and peripheral walls, and is fitted with a lid (not shown) so as to close the opening.
  • the cover has, in a state of being attached to the case 10, an external connection positive electrode terminal collectively connected to the plurality of positive electrode tabs 29 and an external connection negative electrode terminal collectively connected to the plurality of negative electrode tabs 39. is provided.
  • a first heat storage sheet 20 containing a first heat storage material is fixed to the inner surface of the case 10 .
  • a heat storage material is a material that absorbs heat during a phase change from solid to liquid, while releasing heat during a phase change from liquid to solid. Therefore, if a heat storage material with a relatively low temperature at which a phase change occurs is selected, the heat stored in the heat storage material will be A drop in the temperature of the battery 1 can be prevented.
  • a heat storage material having a relatively low melting point is used as the first heat storage material.
  • the first heat storage material can smoothly absorb and release heat according to changes in the ambient temperature in the low temperature range. can. Therefore, by fixing the first heat storage sheet 20 to the inner surface of the case 10, it is possible to keep the unit cells 1 warm for a certain period of time after the stop until the next start. As a result, it is possible to prevent the voltage of the secondary battery 100 (vehicle) from dropping excessively.
  • the specific value of the melting point of the first heat storage material is preferably -30°C or higher and 60°C or lower, more preferably -10°C or higher and 15°C or lower, and -10°C or higher and 10°C or lower. is more preferable, and 0° C. or higher and 8° C. or lower is particularly preferable.
  • the melting point of the first heat storage material may be higher than 15 ° C. and 60 ° C. or lower. A temperature of 20° C. or higher and 50° C.
  • the first heat storage material having a melting point within this range heat generated during charging of the secondary battery 100 (single cell 1) can be better absorbed.
  • Examples of the first heat storage material include, but are not limited to, fatty acid ester, alkane (paraffin), and the like. These compounds may be used individually by 1 type, or may use 2 or more types together.
  • Examples of fatty acid esters include methyl decanoate, ethyl decanoate, methyl laurate, ethyl laurate, ethyl myristate, methyl palmitoleate, and methyl oleate.
  • the fatty acid ester is preferably methyl laurate, ethyl laurate, ethyl myristate, or methyl palmitoleate, and more preferably methyl laurate.
  • alkanes examples include decane, undecane, dodecane, tridecane, tetradecane, pentadecane and the like.
  • the alkane is preferably tridecane, tetradecane, or pentadecane, and more preferably tetradecane.
  • the first heat storage material is preferably in the form of coated particles coated with an outer shell made of an organic material such as melamine resin, acrylic resin, or urethane resin.
  • the average particle size of the coated particles is not particularly limited, it is preferably 10 to 3000 ⁇ m. By using the coated particles having an average particle diameter within this range, it becomes easy to form voids between the coated particles in the first heat storage sheet 20 and to achieve good moldability.
  • the average particle size is more preferably 30 ⁇ m or more, still more preferably 50 ⁇ m or more, and particularly preferably 100 ⁇ m or more.
  • the average particle diameter is more preferably 2000 ⁇ m or less, further preferably 1000 ⁇ m or less, because it facilitates formation of suitable voids, good moldability, and firm retention of the coated particles on the first heat storage sheet 20 .
  • the average particle diameter of the primary particles is within the above range.
  • the average particle diameter of the coated particles is measured by a laser diffraction particle size distribution analyzer (manufactured by Horiba, Ltd., "LA-950V2"), and the obtained median diameter (the particle diameter corresponding to 50% of the volume cumulative distribution : 50% particle size).
  • the first heat storage sheet 20 preferably contains a resin that holds the first heat storage materials (coated particles) and bonds the first heat storage materials together.
  • the first heat storage sheet 20 having voids can be easily produced by bonding the first heat storage materials in a three-dimensional network with such a resin.
  • the resin is a resin that absorbs 70 parts by mass or less of the aqueous dispersion with respect to 100 parts by mass of the first heat storage material. It is preferred to use In this case, it is easy to secure a gap of a suitable size in the first heat storage sheet 20, and the first heat storage sheets 20 having high mechanical strength can be obtained by firmly bonding the first heat storage materials with resin. can be made. Also, during the production thereof, it is possible to easily produce the first heat storage sheet 20 by ensuring good coating properties of the mixed liquid.
  • the absorption amount is more preferably 60 parts by mass or less, still more preferably 55 parts by mass or less, and particularly preferably 50 parts by mass or less.
  • the lower limit of the absorption amount is usually about 10 parts by mass.
  • the amount of the aqueous dispersion absorbed by the first heat storage material can be measured according to, for example, JIS K5101-13-1.
  • As the aqueous resin dispersion it is preferable to use an aqueous dispersion obtained by dispersing 55 parts by mass of resin in 45 parts by mass of water.
  • the form of the resin is not particularly limited as long as the first heat storage sheet 20 (matrix) having voids can be produced. However, since it is easy to form the entire structure of the first heat storage sheet 20, and it is easy to form good voids and to secure the content (porosity) of the voids, the voids are formed by mechanical foaming. The resulting emulsion resin is preferred. Therefore, the first heat storage sheet 20 is preferably made of foam containing the first heat storage material. Thereby, the heat retaining property of the first heat storage sheet 20 can be further enhanced.
  • emulsion resins examples include acrylic emulsion resins, urethane emulsion resins, ethylene vinyl acetate emulsion resins, vinyl chloride emulsion resins, and epoxy emulsion resins.
  • acrylic emulsion resins are preferable because they are excellent in heat resistance and heat insulation, and urethane emulsion resins are preferable because they are excellent in flexibility.
  • the average particle size of the emulsion resin is preferably 30 to 1500 nm, more preferably 50 to 1000 nm, because it facilitates coating of the first heat storage material and bonding between the resin-coated first heat storage materials. is more preferred.
  • the average particle size of the emulsion resin is a 50% median size measured by a dynamic light scattering method, for example, a 50% median size on a volume basis measured by a Microtrac UPA type particle size distribution analyzer manufactured by Nikkiso Co., Ltd. can do.
  • the first heat storage sheet 20 preferably has a structure in which the first heat storage materials are coated with a resin and the first heat storage materials are bonded to each other by the resin.
  • the first heat storage sheet 20 has the first heat storage material compared to a configuration in which the first heat storage material is held in a molded foam material, or a configuration in which closed cells and the first heat storage material are dispersed in a resin matrix. Both material and voids can be contained at high densities.
  • the heat storage, heat retention, and heat insulation of the first heat storage sheet 20 can be adjusted appropriately. can also Furthermore, it is lightweight, easy to mold and process into a sheet shape, the first heat storage material is less likely to come off, and it is easy to impart flexibility.
  • the first heat storage sheet 20 has a structure in which the resin-coated first heat storage materials are bonded together by the resin to form a gap between the first heat storage materials. Therefore, the specific gravity of the first heat storage sheet 20 is preferably 0.15 to 0.9, more preferably 0.3 to 0.9. In this case, it is easy to obtain high heat retention of the first heat storage sheet 20 . Further, in this case, the weight of the first heat storage sheet 20 can be easily reduced, and good workability can be obtained.
  • the content of the first heat storage material in the first heat storage sheet 20 is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, because it is easy to achieve suitable heat storage and heat retention. More preferably, 30 to 70% by mass is even more preferable.
  • the content of the resin in the first heat storage sheet 20 is preferably 10 to 90% by mass because it is easy to adjust the content of the voids and the first heat storage material and to improve the content of both. , more preferably 20 to 80% by mass, more preferably 30 to 70% by mass.
  • the amount ratio of the first heat storage material and the resin is 80/20 to 15/85 in terms of the solid content mass ratio represented by the first heat storage material/resin. and more preferably 70/30 to 30/70. Since the first heat storage sheet 20 can be easily processed such as cutting, it is excellent in handleability. Although the thickness of the first heat storage sheet 20 is not particularly limited, it is preferably 100 to 6000 ⁇ m, more preferably 300 to 4000 ⁇ m, even more preferably 500 to 3000 ⁇ m. In this case, the heat storage property and heat retaining property of the first heat storage sheet 20 can be further improved.
  • the first heat storage sheet 20 preferably has a mandrel diameter of 25 mm or less, more preferably 20 mm or less, and 16 mm or less, where cracking occurs in a bending resistance test according to JIS K5600-5-1 (1999). is more preferable.
  • the first heat storage sheet 20 that satisfies these requirements can ensure suitable flexibility and excellent conformability to the surfaces of various members.
  • the bending resistance of the first heat storage sheet 20 measured according to the Gurley method defined in JIS L1913 (2010) is preferably 0.1 to 30 mN, more preferably 0.5 to 20 mN. More preferably, it is still more preferably 1 to 10 mN.
  • the first heat storage sheet 20 having such bending resistance can also ensure suitable flexibility and excellent conformability to the surfaces of various members.
  • the tensile strength of the first heat storage sheet 20 is preferably 0.1 MPa or more, more preferably 0.2 MPa or more.
  • the first heat storage sheet 20 can be flexible and tough.
  • the first heat storage sheet 20 is preferable because it is less likely to crack during processing, transportation, and the like, and can exhibit suitable workability, handleability, transportation suitability, bending suitability, and the like.
  • the upper limit of the tensile strength of the first heat storage sheet 20 is not particularly limited, it is preferably 15 MPa or less, more preferably 10 MPa or less, and even more preferably 5 MPa or less.
  • the elongation rate of the first heat storage sheet 20 at breakage is preferably 10% or more, more preferably 30% or more, and even more preferably 50% or more. In this case, embrittlement of the first heat storage sheet 20 can be suppressed. Moreover, even if the first heat storage sheet 20 is bent or distorted during processing, transportation, or the like, cracking or chipping is unlikely to occur.
  • the upper limit of the elongation at tensile break of the first heat storage sheet 20 is preferably 1000% or less, more preferably 500% or less, and even more preferably 300% or less. In this case, the first heat storage sheet 20 can achieve excellent flexibility while being tough. Therefore, the first heat storage sheet 20 is easy to obtain good workability, handleability, transportability, conformability to the surfaces of various members, and the like.
  • the tensile strength and elongation at breakage of the first heat storage sheet 20 can be measured according to the method specified in JIS K6251. Specifically, the first heat storage sheet 20 is cut into a dumbbell-shaped No. 2 shape, and a test piece is prepared with two marked lines with an initial distance between marked lines of 20 mm. This test piece is attached to a tensile tester and pulled at a speed of 200 mm/min to break. At this time, the maximum force (N) until breakage and the distance between gauge lines (mm) at breakage are measured, and the tensile strength and elongation at breakage can be calculated from the following equations.
  • Tensile strength TS (MPa) is calculated by the following formula.
  • TS Fm/Wt
  • Fm is the maximum force (N)
  • W is the width of the parallel portion (mm)
  • t is the thickness of the parallel portion (mm).
  • Eb (Lb - L0) / L0 x 100
  • Lb is the distance between the marked lines (mm) at breakage
  • L0 is the initial distance between the marked lines (mm).
  • the first heat storage sheet 20 may contain various additives as necessary.
  • additives include flame retardants, harmful substance adsorbents such as formaldehyde, coloring pigments, and deodorants.
  • the first heat storage sheet 20 as described above can preferably be produced by mechanically foaming a resin composition containing a resin, a first heat storage material, and an aqueous medium, followed by coating, casting, and drying. .
  • the resin composition may be dried and then cured by heat, ultraviolet rays, or the like, if necessary.
  • Water can be preferably used as an aqueous medium that can be used for preparing the resin composition.
  • the aqueous medium may be a mixture of water and a water-soluble solvent.
  • the water-soluble solvent include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, ethyl carbitol, ethyl cellosolve and butyl cellosolve, and polar solvents such as N-methylpyrrolidone. These water-soluble solvents may be used alone or in combination of two or more.
  • Surfactants, thickeners, flame retardants, cross-linking agents, and other additives may be mixed with the resin composition, if necessary.
  • the resin composition can be mixed with an arbitrary surfactant in order to refine and stabilize the foamed foam.
  • Any of anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants and the like may be used as surfactants.
  • the surfactant is preferably an anionic surfactant, more preferably a fatty acid ammonium surfactant such as ammonium stearate.
  • Surfactants may be used alone or in combination of two or more.
  • a necessary amount of a thickener may be mixed in the resin composition in order to improve the stability and film-forming properties of the foamed foam.
  • thickeners include acrylic acid-based thickeners, urethane-based thickeners, polyvinyl alcohol-based thickeners, and the like. Among them, it is preferable to use an acrylic acid-based thickener and a urethane-based thickener as the thickener.
  • a necessary amount of a flame retardant may be mixed in the resin composition in order to improve the flame retardancy of the first heat storage sheet 20 .
  • the flame retardant is not particularly limited, but organic flame retardants and inorganic flame retardants can be used as appropriate.
  • the organic flame retardant is preferably, for example, a phosphorus compound, a halogen compound, a guanidine compound, or the like.
  • organic flame retardants include primary ammonium phosphate, secondary ammonium phosphate, phosphoric triester, phosphite, phosphonium salt, phosphoric triamide, chlorinated paraffin, ammonium bromide, deca Bromobisphenol, tetrabromobisphenol A, tetrabromoethane, decabromodiphenyloxide, hexabromophenyloxide, pentabromooxide, hexabromobenzene, guanidine hydrochloride, guanidine carbonate, guanylurea phosphate and the like.
  • inorganic flame retardants examples include antimony and aluminum compounds, boron compounds, and ammonium compounds. Specific examples of inorganic flame retardants include antimony pentoxide, antimony trioxide, and sodium tetraborate decahydrate. hydrates (borax), ammonium sulfate, ammonium sulfamate, and the like. As the flame retardant, one of the above compounds may be used alone, or two or more thereof may be used in combination.
  • the resin composition may be mixed with a necessary amount of a curing agent.
  • the curing agent may be appropriately selected according to the type of resin used, and examples thereof include epoxy curing agents, melamine curing agents, isocyanate curing agents, carbodiimide curing agents, oxazoline curing agents, and the like.
  • the content of the resin in the resin composition is preferably 30 to 200 parts by mass, preferably 50 to 150 parts by mass, with respect to 100 parts by mass of the aqueous medium when, for example, an acrylic emulsion resin is used. It is more preferable to have In this case, it becomes easy to adjust the viscosity of the resin composition to a suitable range, and to stably foam it.
  • the content of the first heat storage material in the resin composition may be blended so that the amount ratio of the first heat storage material/resin in the first heat storage sheet 20 is within the above range.
  • the content is preferably 30 parts by mass or less with respect to 100 parts by mass (solid content) of the resin, since it is easy to obtain suitable foaming properties. .5 to 20 parts by mass, more preferably 3 to 15 parts by mass.
  • the content thereof is preferably 0.1 to 10 parts by mass, preferably 0.5 to 8 parts by mass, with respect to 100 parts by mass (solid content) of the resin. It is more preferable to have
  • the fixing of the first heat storage sheet 20 to the inner surface of the case 10 can be performed by, for example, an adhesive, fusion (ultrasonic fusion, high frequency fusion, heat fusion), adhesive, or the like.
  • the secondary battery 100 has a second heat storage sheet 30 that isolates adjacent unit cells 1 housed in the case 10 .
  • Any material can be used as the second heat storage sheet 30 as long as it contains a second heat storage material having a melting point within the range shown below.
  • the second heat storage material absorbs the heat generated during charging of the secondary battery 100 (single cell 1), so that the temperature of the cell 1 can be prevented from rising. Therefore, it is possible to prevent deterioration, ignition, etc. of the unit cell 1 in advance.
  • each unit cell 1 is covered with the second heat storage sheet 30 with the positive electrode tab 29 and the negative electrode tab 39 exposed. As a result, it is possible to more reliably suppress an increase in the temperature of the cell 1 during charging of the secondary battery 100 (cell 1).
  • the specific value of the melting point of the second heat storage material is preferably ⁇ 30° C. or higher and 60° C. or lower, more preferably 15° C. or higher and 60° C. or lower, and more preferably 20° C. or higher and 50° C. or lower. , more preferably 30° C. or higher and 45° C. or lower, and particularly preferably 35° C. or higher and 45° C. or lower.
  • the second heat storage material include, but are not particularly limited to, fatty acid ester, alkane (paraffin), and the like.
  • the melting point of the second heat storage material is more preferably -10°C or higher and 15°C or lower, more preferably -10°C or higher and 10°C. It is more preferably 0° C. or higher and 8° C. or lower.
  • fatty acid esters examples include methyl myristate, methyl palmitate, ethyl palmitate, methyl stearate, and ethyl stearate.
  • the fatty acid ester is preferably methyl palmitate, ethyl palmitate, methyl stearate, or ethyl stearate, and more preferably methyl stearate.
  • alkanes include hexadecane, heptadecane, octadecane, nonadecane, icosane, henicosane, and docosane.
  • the alkane is preferably heptadecane, octadecane, nonadecane, icosane, henicosane, or docosane, more preferably nonadecane, icosane, henicosane, or docosane, and still more preferably icosane, henicosane, or docosane.
  • the second heat storage material is preferably in the form of coated particles coated with an outer shell made of an organic material such as melamine resin, acrylic resin, or urethane resin.
  • the average particle size of the coated particles is not particularly limited, but is preferably 10 to 1000 ⁇ m, more preferably 50 to 500 ⁇ m. It is preferable that the average particle size of the primary particles is within the above range. may be within the above range.
  • the average particle size of the coated particles is defined in the same manner as described for the first heat storage material.
  • the moisture content of the second heat storage material is preferably 3% by mass or less, more preferably 2% by mass or less, even more preferably 1.5% by mass or less, and 1.2% by mass or less. is particularly preferred.
  • the second heat storage sheet 30 preferably contains a matrix-forming resin.
  • resins include thermoplastic resins, thermosetting resins, UV-curable resins, and the like.
  • a thermoplastic resin is preferable as the resin because it is excellent in moldability of the second heat storage sheet 30 .
  • Thermoplastic resins include vinyl chloride resins, acrylic resins, urethane resins, olefin resins, ethylene-vinyl acetate copolymer, styrene-butadiene resins, polystyrene resins, polybutadiene resins, polyester resins, and polyamide resins.
  • polyimide-based resins polycarbonate-based resins, 1,2-polybutadiene-based resins, polycarbonate-based resins, polyimide-based resins, and the like.
  • vinyl chloride-based resins are preferable because they can easily improve the moldability at low temperatures and the dispersibility of the second heat storage material.
  • the use of a vinyl chloride resin is preferable because the second heat storage sheet 30 can be produced at a low temperature by preparing a resin composition using the particles and forming a sol-cast film.
  • the resin composition is a paste-like composition in which the second heat storage material is dispersed in a mixture of vinyl chloride resin particles and a plasticizer.
  • the average particle size of the vinyl chloride resin particles is preferably 0.01 to 10 ⁇ m, more preferably 0.1 to 5 ⁇ m.
  • the vinyl chloride resin particles may be directly dispersed in the form of primary particles, or may be dispersed in the form of aggregated primary particles as spherical secondary particles.
  • vinyl chloride resin particles having different average particle sizes may be mixed to have a particle size distribution in which two or more peaks are present. The particle size can be measured by a laser method or the like.
  • the shape of the vinyl chloride-based resin particles is preferably approximately spherical because it facilitates the development of suitable fluidity and the change in viscosity upon aging is small.
  • Vinyl chloride-based resin particles are preferably produced by emulsion polymerization or suspension polymerization because they can be easily formed into a spherical shape and the particle size distribution can be easily controlled.
  • the degree of polymerization of the vinyl chloride resin is preferably 500-4000, more preferably 600-2000. Further, by setting the viscosity within the above range, it becomes easy to adjust the rotational viscometer viscosity and the steady shear viscosity of the resin composition to a suitable range. Commercially available vinyl chloride resin particles can be appropriately used.
  • the content of the thermoplastic resin in the second heat storage sheet 30 is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, and more preferably 30 to 60% by mass. % is more preferred.
  • a resin matrix can be suitably formed in the second heat storage sheet 30, and the second heat storage sheet 30 having flexibility and toughness can be easily formed.
  • it is preferable to mix a plasticizer with the resin composition because it is easy to ensure good coatability and moldability of the resin composition.
  • Plasticizers include epoxy plasticizers, methacrylate plasticizers, polyester plasticizers, polyetherester plasticizers, aliphatic diester plasticizers, trimellitic acid plasticizers, adipic acid plasticizers, and benzoic acid plasticizers. Plasticizers, phthalic acid-based plasticizers, and the like can be mentioned. These plasticizers may be used alone or in combination of two or more.
  • a commercially available product can be appropriately used as the plasticizer.
  • Commercially available epoxy plasticizers include Monosizer W-150 manufactured by DIC; Adeka Cizer O-130P, O-180A, D-32, D-55 manufactured by ADEKA, Kapox S-6 manufactured by Kao Corporation, and the like.
  • Commercially available polyester plasticizers include Polycizer W-2050, W-2310, W-230H manufactured by DIC Corporation; Adekasizer PN-7160, PN-160, PN-9302, PN-150, PN-170 manufactured by ADEKA Corporation.
  • trimellitic acid-based plasticizers include Monosizer W-705 manufactured by DIC, Adekasizer C-9N manufactured by ADEKA, and TOTM and TOTM-NB manufactured by Mitsubishi Chemical.
  • examples of commercially available benzoic acid-based plasticizers include Monosizer PB-3A manufactured by DIC Corporation and JP120 manufactured by Mitsubishi Chemical Corporation.
  • plasticizers that can be gelled at a particularly low temperature because it is easy to suppress the leakage of the second heat storage material and the plasticizer.
  • the gelation completion temperature of such a plasticizer is preferably 150° C. or lower, more preferably 140° C. or lower, even more preferably 130° C. or lower, particularly preferably 120° C. or lower. °C or less is most preferred.
  • the gelation end temperature can be a temperature at which the light transmittance of the gelled film becomes constant.
  • Plasticizers with good low-temperature moldability include epoxy plasticizers, polyester plasticizers, benzoic acid plasticizers, and the like. These plasticizers with good low-temperature moldability are preferable because they easily impart toughness to the resin matrix as well as suitable heat storage properties. From the viewpoint of heat resistance and low-temperature moldability, epoxy plasticizers and polyester plasticizers are particularly preferred.
  • the gelation end temperature is obtained by mixing the vinyl chloride resin for paste (polymerization degree: 1700), the plasticizer, and the heat stabilizer (Ca—Zn) at a mass ratio of 100/80/1.5. This composition was sandwiched between a glass plate and a preparation, and then the temperature was raised at a rate of 5° C./min. 800) to determine the temperature at which the light transmittance is constant.
  • the viscosity of the plasticizer at 25° C. is preferably 1500 mPa s or less, more preferably 1000 mPa s or less, still more preferably 500 mPa s or less, and particularly preferably 300 mPa s or less. preferable.
  • a plasticizer having a viscosity within this range the viscosity of the resin composition for producing the second heat storage sheet 30 can be kept low. can be enhanced. Moreover, in this case, it becomes easy to adjust the rotational viscometer viscosity and the steady shear viscosity of the resin composition to a suitable range.
  • the weight average molecular weight of the plasticizer is preferably 200-3000, more preferably 300-1000.
  • the plasticizer itself is less likely to exude, and the viscosity of the resin composition can be kept low. Therefore, the filling rate of the second heat storage material in the second heat storage sheet 30 can be increased. Moreover, in this case, it becomes easy to adjust the rotational viscometer viscosity and the steady shear viscosity of the resin composition to a suitable range.
  • the weight average molecular weight (Mw) is a value converted to polystyrene based on gel permeation chromatography (hereinafter abbreviated as "GPC") measurement. GPC measurement can be performed under the following conditions.
  • Measuring device guard column "HLC-8330" manufactured by Tosoh Corporation Column: "TSK SuperH-H” manufactured by Tosoh Corporation + “TSK gel SuperHZM-M” manufactured by Tosoh Corporation + “TSK gel SuperHZM-M” manufactured by Tosoh Corporation + “TSK gel SuperHZ-2000” manufactured by Tosoh Corporation + “TSK gel SuperHZ-2000” manufactured by Tosoh Corporation Detector: RI (differential refractometer) Data processing: "GPC-8020 model II version 4.10" manufactured by Tosoh Corporation Column temperature: 40°C Developing solvent: Tetrahydrofuran (THF) Flow rate: 0.35 mL/min Sample: Filtrate (100 ⁇ L) obtained by filtering a tetrahydrofuran solution of 1.0% by mass in terms of resin solid content through a microfilter Standard sample: The following monodisperse polystyrene with a
  • the second heat storage material is coated particles, among the above plasticizers, it is preferable to use a plasticizer having an HSP distance of 6 or more with respect to the second heat storage material.
  • a plasticizer having an HSP distance of 6 or more with respect to the second heat storage material.
  • the second heat storage sheet 30 easily achieves suitable heat resistance in which volume shrinkage does not easily occur even at high temperatures.
  • large volume shrinkage may occur at high temperatures.
  • the HSP distance is preferably 7 or more, and more preferably 8 or more, since suitable heat resistance can be easily obtained.
  • the upper limit of the HSP distance is not particularly limited, but it is preferably 40 or less, more preferably 30 or less, and further preferably 25 or less, because it is easy to obtain suitable compatibility and moldability. preferable.
  • the HSP distance is an index representing the solubility between substances using the Hansen Solubility Parameter (HSP).
  • the Hansen solubility parameter expresses solubility in a multidimensional (typically three-dimensional) vector, which can be expressed in terms of dispersion, polarity, and hydrogen bonding. The vector similarity is then expressed as the distance of the Hansen Solubility Parameter (HSP distance).
  • Hansen Solubility Parameters are presented as reference values in various documents, for example, Hansen Solubility Parameters: A User's Handbook (Charles Hansen et al., 2007, 2nd edition), and the like.
  • Hansen Solubility Parameters can also be calculated based on the chemical structure of a substance using commercially available software such as Hansen Solubility Parameter in Practice (HSPiP). In addition, calculation is performed assuming that the solvent temperature is 25°C.
  • Preferred combinations of the plasticizer and the second heat storage material include, for example, the following combinations.
  • epoxy plasticizers, polyester plasticizers, trimellitic acid plasticizers, and the like can be preferably used.
  • epoxy plasticizers, polyester plasticizers, trimellitic acid plasticizers, benzoic acid plasticizers, etc. are preferably used. be able to.
  • an epoxy-based plasticizer is preferable because it can suitably impart various properties such as heat resistance to the second heat storage sheet 30 .
  • the HSP distance between the thermoplastic resin and the plasticizer is preferably 15 or less, more preferably 12 or less, because the resin matrix is easily formed. preferable.
  • the lower limit of the HSP distance is not particularly limited, but is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more.
  • the plasticizer When using coated particles as the second heat storage material, absorption of the plasticizer with respect to 100 parts by mass of the second heat storage material measured according to JIS K5101-13-1 when the plasticizer is mixed with the second heat storage material A plasticizer in an amount of 150 parts by mass or less can be preferably used.
  • the absorption amount of the plasticizer is preferably 140 parts by mass or less, more preferably 135 parts by mass or less, and even more preferably 130 parts by mass or less, since suitable heat resistance can be easily obtained.
  • the lower limit of the absorption amount is not particularly limited, it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, because suitable compatibility and moldability can be easily obtained.
  • the absorption amount of the plasticizer is within the above range, it becomes easy to adjust the storage elastic modulus of the resin composition to a suitable range.
  • the plasticizer absorption is measured according to the method for measuring oil absorption according to JIS K5101-13-1. Specifically, depending on the expected absorption amount, 1 to 20 g of the second heat storage material is placed as a sample on a glass plate, and the plasticizer is gradually added by 4 to 5 drops at a time from a burette. . Knead the sample each time with a steel palette knife. This operation is repeated, and dropping is continued until lumps of the plasticizer and the sample are formed. After that, the operation of dropping one drop at a time and kneading completely is repeated, and the point at which the paste becomes a smooth hardness is taken as the end point, and the absorption amount at this time is defined as the absorption amount of the plasticizer. The end point should be such that the paste can be spread without cracking or crumbling and can be lightly adhered to the measuring plate.
  • a resin composition containing a resin and a second heat storage material is prepared, and the resin composition is applied on a support to form a coating film. It can be produced by heating at a temperature of 150° C. or less.
  • a film-like substrate from which the second heat storage sheet 30 can be peeled off and which exhibits heat resistance at the temperature of the heating process can be suitably used.
  • resin films used as various process films can be suitably used. Examples of such resin films include polyester resin films such as polyethylene terephthalate resin films and polybutylene terephthalate resin films.
  • the thickness of the resin film is not particularly limited, it is preferably 25 to 100 ⁇ m from the viewpoint of handleability and availability.
  • the surface of the resin film is preferably release-treated.
  • release agents used for release treatment include alkyd-based resins, urethane-based resins, olefin-based resins, and silicone-based resins.
  • Cast film-forming in which the resin composition is applied onto a support can be carried out using a coating machine such as a roll knife coater, a reverse roll coater and a comma coater. Among them, a method of feeding a resin composition onto a support and forming a coating film having a constant thickness with a doctor knife or the like can be preferably used.
  • the formed coating film can be made into the second heat storage sheet 30 by gelling or hardening by heating or drying.
  • the temperature of the coating film during heating is preferably 150° C. or lower, more preferably 140° C. or lower, even more preferably 130° C. or lower, and 120° C. or lower. Especially preferred.
  • the heating time may be appropriately adjusted depending on the gelation speed and the like, but is preferably about 10 seconds to 10 minutes.
  • the coating film may be appropriately dried by air drying or the like.
  • the resin composition (coating liquid) forming the second heat storage sheet 30 may be prepared by appropriately mixing according to the resin and the second heat storage material.
  • a vinyl chloride resin is used as the resin
  • a method of forming a coating film by sol casting using a vinyl sol coating liquid containing vinyl chloride resin particles is preferred.
  • the coating film can be formed at a low temperature without kneading with a mixer or extrusion molding. Therefore, the second heat storage material is less likely to be destroyed, and the second heat storage material is less likely to seep out from the obtained second heat storage sheet 30 .
  • the vinyl sol coating liquid can also contain a solvent as appropriate.
  • a solvent used in the sol casting method for vinyl chloride resin can be appropriately used.
  • the solvent includes ketones such as diisobutyl ketone and methyl isobutyl ketone, esters such as butyl acetate, and glycol ethers. These solvents may be used alone or in combination of two or more.
  • the above solvent is preferable because it tends to slightly swell the resin at room temperature to facilitate dispersion, and also facilitates melting gelation in the heating process.
  • a diluent solvent may also be used together with the above solvent.
  • the diluting solvent a solvent that does not dissolve the resin and suppresses swelling of the dispersion solvent is preferably used. Examples of such diluent solvents include paraffinic hydrocarbons, naphthenic hydrocarbons, aromatic hydrocarbons, terpene hydrocarbons, and the like.
  • the vinyl sol coating solution can be mixed with a heat stabilizer in order to suppress decomposition deterioration and coloration mainly due to dehydrochlorination reaction of the vinyl chloride resin.
  • thermal stabilizers include calcium/zinc stabilizers, octyltin stabilizers, barium/zinc stabilizers, and the like.
  • the content of the heat stabilizer in the vinyl sol coating liquid is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the vinyl chloride resin.
  • Additives such as a viscosity reducer, a dispersant, and an antifoaming agent may be mixed in the vinyl sol coating solution as required.
  • the content of these additives is preferably 0.5 to 10 parts by mass with respect to 100 parts by mass of the vinyl chloride resin.
  • the viscosity of the vinyl sol coating solution during coating may be adjusted as appropriate depending on the desired thickness of the second heat storage sheet 30, the coating conditions, etc., but it is 1000 mPa s because it is easy to obtain good coating properties. It is preferably 3000 mPa ⁇ s or more, more preferably 5000 mPa ⁇ s or more.
  • the upper limit of the viscosity is preferably 70,000 mPa ⁇ s or less, more preferably 50,000 mPa ⁇ s or less, even more preferably 30,000 mPa ⁇ s or less, and particularly preferably 25,000 mPa ⁇ s or less. .
  • the viscosity of the coating liquid can be measured with a Brookfield viscometer.
  • the second heat storage sheet 30 made of the sol-cast film of the vinyl sol coating liquid containing the vinyl chloride resin particles and the second heat storage material does not apply shear or pressure to the second heat storage material during manufacturing, so the second heat storage material is not destroyed. is difficult to occur. Therefore, the second heat storage material is less likely to seep out even though a resin-based material is used.
  • the second heat storage sheet 30 can be obtained which has heat storage properties due to the second heat storage material and which has good flexibility. Furthermore, since it can be easily laminated with other layers and processed, it is preferably applied to the secondary battery 100 .
  • the content of the second heat storage material in the second heat storage sheet 30 is preferably 10 to 90% by mass, more preferably 20 to 70% by mass, because it is easy to achieve suitable heat storage properties. More preferably, it is 30 to 50% by mass.
  • the content of the plasticizer in the second heat storage sheet 30 is preferably 5 to 75% by mass, more preferably 10 to 70% by mass, even more preferably 20 to 60% by mass. It is particularly preferred that it is up to 40% by mass. In this case, it becomes easier to obtain good coatability and moldability of the resin composition.
  • the plasticizer is 30 to 150 parts by mass with respect to 100 parts by mass of the thermoplastic resin. It is preferably from 40 to 130 parts by mass, and even more preferably from 50 to 120 parts by mass.
  • the thickness of the second heat storage sheet 30 is not particularly limited, it is preferably 100 to 6000 ⁇ m, more preferably 300 to 4000 ⁇ m, even more preferably 500 to 3000 ⁇ m. In this case, it is possible to improve the heat storage performance of the second heat storage sheet 30 while satisfactorily preventing heat transfer between adjacent unit cells 1 .
  • the tensile strength of the second heat storage sheet 30 is preferably 0.1 MPa or more, more preferably 0.3 MPa or more, even more preferably 0.6 MPa or more, and particularly 1 MPa or more. preferable. In this case, it is possible to obtain the second heat storage sheet 30 that is tough while having flexibility. In addition, the second heat storage sheet 30 is preferable because cracks are less likely to occur during processing, transportation, and the like, and favorable workability, handleability, transportation suitability, bending suitability, and the like can be readily exhibited. Although the upper limit of the tensile strength of the second heat storage sheet 30 is not particularly limited, it is preferably 15 MPa or less, more preferably 10 MPa or less, and even more preferably 5 MPa or less.
  • the elongation at tensile break of the second heat storage sheet 30 is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, and 25% or more. is particularly preferred. In this case, embrittlement of the second heat storage sheet 30 can be suppressed. In addition, even if the second heat storage sheet 30 is bent or distorted during processing, transportation, or the like, cracking or chipping is less likely to occur.
  • the upper limit of the elongation at tensile break of the second heat storage sheet 30 is preferably 1000% or less, more preferably 500% or less, and even more preferably 300% or less. In this case, the second heat storage sheet 30 can have suitable flexibility while being strong. Therefore, the second heat storage sheet 30 is more likely to exhibit good workability, handleability, transport suitability, bending suitability, and the like.
  • each unit cell 1 is covered with the second heat storage sheet 30 while the positive electrode tab 29 and the negative electrode tab 39 are exposed. You may arrange
  • FIG. 4 is a cross-sectional view showing a second embodiment of the secondary battery of the present invention
  • FIG. 5 is an exploded perspective view of the battery stack of the second embodiment.
  • the secondary battery 100 of the second embodiment will be described below, but the description will focus on the differences from the secondary battery 100 of the first embodiment, and the description of the same items will be omitted.
  • the case 10 has a cylindrical body portion 11 .
  • a first heat storage sheet 20 is fixed to the inner peripheral surface of the body portion 11 .
  • one battery stack 9 single cell 1 with the sealing body 5 omitted
  • the second heat storage sheet 30 are superimposed (see FIG. 5) and wound, and the body 11 (second 1 heat storage sheet 20) (see FIG. 4).
  • the secondary battery 100 of the second embodiment functions and effects similar to those of the secondary battery 100 of the first embodiment can be obtained.
  • the contact area between the battery stack 9 and the second heat storage sheet 30 can be increased, and the second heat storage sheet 30 more efficiently absorbs heat from the battery stack 9. and can be discharged.
  • the separator 4 instead of the second heat storage sheet 30, the separator 4 may be stacked on the battery stack 9 and stored inside the body portion 11 in a wound state.
  • the battery stack 9 may be housed inside the trunk portion 11 as the unit cell 1 sealed with a sealing body (armoring material) 5 .
  • FIG. 6 is a partially cutaway perspective view showing a third embodiment of the secondary battery of the present invention.
  • the secondary battery 100 of the third embodiment will be described below, but the description will focus on the differences from the secondary batteries 100 of the first and second embodiments, and the description of the same items will be omitted.
  • a secondary battery 100 shown in FIG. 6 a plurality of cylindrical cells 1 are arranged in a rectangular case 10 .
  • a first heat storage sheet 20 is fixed to the inner surface of the case 10 .
  • the plurality of cells 1 are accommodated (arranged) in the case 10 in a matrix with the longitudinal direction (axial direction) of the case 10 being the thickness direction (height direction) of the case 10 .
  • an external connection positive electrode terminal 12 collectively connected to the plurality of positive electrode tabs 29 and an external connection negative electrode terminal 13 collectively connected to the plurality of negative electrode tabs 39 are provided. It is The configuration shown in FIG. 4 can be adopted for each unit cell 1 . However, in this case, the first heat storage sheet 20 in the cell 1 is omitted.
  • each cell 1 may be a normal cylindrical cell.
  • the outer periphery of each unit cell 1 may be covered with the second heat storage sheet 30, or a plurality of unit cells 1 arranged in a row may be collectively covered with the second heat storage sheet 30. .
  • the present invention is not limited to the configurations of the above-described embodiments.
  • configuration for any other purpose may be added, or may be replaced with any configuration exhibiting similar functions.
  • the first heat storage sheet 20 and the second heat storage sheet 30 may each be a laminate in which a plurality of sheets are laminated.
  • the first heat storage sheet 20 may be fixed to the inner surface of the case 10, and the second heat storage sheet 30 may be laminated inside.
  • the types of positive electrode active material, negative electrode active material, and electrolyte are appropriately selected according to the ion species to be transferred during charging and discharging.
  • the mechanically foaming binder was applied onto the PET film with an applicator, it was pre-dried by heating at a dryer temperature of 100° C. for 5 minutes and then heat-treated at a dryer temperature of 140° C. for 10 minutes for curing.
  • a first heat storage sheet having a thickness of 3 mm was produced.
  • the specific gravity of the first heat storage sheet was 0.42
  • the mass of the first heat storage sheet was 1260 g/m 2
  • the content of the coated particles contained in the first heat storage sheet was 65% by mass.
  • Second heat storage sheet Polyvinyl chloride resin particles with a degree of polymerization of 900 (ZEST PQ92 manufactured by Shin Daiichi Vinyl Co., Ltd.) 100 parts by mass, polyester plasticizer (Polycizer W-230H manufactured by DIC) 70 parts by mass, other additives 2 parts by mass of a dispersant (Eposizer E-100EL manufactured by DIC) and 2 parts by mass of a dispersant (Disperplast-1142 manufactured by BYK), and a second heat storage material containing methyl stearate as an outer shell made of urethane resin.
  • a plastisol coating solution 100 parts by mass of coated particles (average particle size: 150 ⁇ m, melting point: 38° C.) microencapsulated using the above-mentioned powder were blended to prepare a plastisol coating solution. After applying this plastisol coating liquid on a PET film with an applicator coating machine, it is heated at a dryer temperature of 150° C. for 8 minutes to gel, the PET film is peeled off, and a second heat storage sheet with a thickness of 1 mm is obtained. was made. The content of the coated particles contained in the second heat storage sheet was 35.5% by mass.
  • Example A1 A test body was prepared in the same manner as in Example A, except that a 3 mm thick heat insulating material (manufactured by Toray Industries, Inc., "Toraypef"; thermal conductivity: 0.035 W/mK) was used instead of the first heat storage sheet. Got ready.
  • Comparative Example A2 A test body was prepared in the same manner as in Example A, except that the first heat storage sheet was omitted.
  • Example B1 A test specimen was prepared in the same manner as in Example B, except that a vinyl chloride sheet (not containing the second heat storage material) having a thickness of 1 mm, a width of 150 mm, and a length of 150 mm was used instead of the second heat storage sheet. did.
  • Comparative example B2 A test body was prepared in the same manner as in Example B, except that the second heat storage sheet was omitted. A gap of 1 mm was maintained between the simulated cells.

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