Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
  • B29C43/20—Making multilayered or multicoloured articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/32—Component parts, details or accessories; Auxiliary operations
  • B29C43/34—Feeding the material to the mould or the compression means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
  • B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
  • B29C44/04—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles consisting of at least two parts of chemically or physically different materials, e.g. having different densities
  • B29C44/06—Making multilayered articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B25/00—Layered products comprising a layer of natural or synthetic rubber
  • B32B25/20—Layered products comprising a layer of natural or synthetic rubber comprising silicone rubber
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
  • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
• • 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
  • H01M10/65—Means for temperature control structurally associated with the cells
  • H01M10/658—Means for temperature control structurally associated with the cells by thermal insulation or shielding
• • 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
  • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
  • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
• • 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
  • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
  • H01M50/289—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by spacing elements or positioning means within frames, racks or packs
  • H01M50/293—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders characterised by spacing elements or positioning means within frames, racks or packs characterised by the material
• • 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

Definitions

• the present invention relates to a method for producing a heat insulating cushioning laminated sheet and its use in a battery unit.
• Battery modules used in automobiles generally have a mechanism in which one or more battery units, each of which has a large number of battery cells arranged, are arranged. It is known that battery cells expand and contract as the battery is charged and discharged, and it is known that a thermal insulating cushioning support sheet is provided between the battery cells to absorb the deformation (expansion and contraction) of the battery cells and suppress excessive deformation so that the battery cells do not interfere with each other, and to support each battery cell, and to have a thermal insulating property of suppressing heat conduction to adjacent battery cells in the event of thermal runaway of a battery cell.
• these secondary batteries may go into thermal runaway due to some factor, which may cause a fire or ignition due to the high temperature of the secondary battery.
• a mechanism is known for automobile batteries in which multiple battery cells are arranged to form a single battery module. In this mechanism, if one battery cell catches fire or emits smoke, the heat will be transmitted to adjacent battery cells, causing a chain reaction of thermal runaway, and the entire battery module may catch fire or explode.
• Patent Literature 1 discloses a method for preventing the spread of heat and combustion between battery cells by attaching a porous sponge sheet, which is a fire prevention sheet, between battery cells. Silicone rubber is used as the porous sponge sheet.
• the fire spread prevention sheet in Patent Document 1 is made of a sponge sheet to which a flame retardant has been added, and aims to prevent the spread of fire by the fire spread prevention sheet itself being non-flammable, and does not provide thermal insulation properties.
• the surface temperature of the runaway battery cell reaches or exceeds 600° C., but even silicone rubber, which has relatively good heat resistance, begins to decompose rapidly at around 400° C.
• the battery cell and the silicone rubber sponge sheet are directly attached, so when the battery experiences thermal runaway, the polymer components of the silicone rubber sponge sheet (fire-spread prevention sheet) decompose immediately, making it impossible to maintain its shape and function.
• both sides of the curable composition are sandwiched between the plates but are not fixed, which results in unstable production quality.
• both sides of the curable composition are not fixed to the plate, the surface direction between the plate and the curable composition is not regulated, so when the foaming ratio of the sponge sheet is high, the adhesion between the plate and the curable composition cannot withstand the expansion force caused by the foaming of the curable composition, and it is possible that the shape in the surface direction before foaming cannot be maintained, resulting in an unstable shape of the silicone rubber sponge sheet (fire-proof sheet) and an uneven distribution of sponge cells, i.e., unstable production quality.
• An object of the present invention is to provide a heat insulating and cushioning laminated sheet which is excellent in heat insulating properties and compressive stress when compressed, and in which the shape of the silicone rubber layer is maintained even when foaming occurs during production.
• the present invention relates to, for example, the following [1] to [10].
• a battery pack having a plurality of battery cells and a heat insulating cushioning laminated sheet manufactured by the manufacturing method of [1] sandwiched between each of the battery cells; The heat insulating cushioning laminated sheet contacts each of the battery cells via its support member.
• Battery unit [9] The battery unit of [8], wherein the thermal conductivity of the support member in the insulating cushioning laminated sheet is 0.20 W/m ⁇ K or less. [10] The battery unit of [8], wherein the silicone rubber layer in the insulating cushioning laminated sheet has an Asker C hardness of 40 to 90 in the direction in which the two support members face each other.
• the heat insulating cushioning laminated sheet of the present invention has excellent heat insulating properties and compressive stress when compressed, and the shape of the silicone rubber layer is maintained even when foamed during manufacturing.
• FIG. 1 is a diagram showing the relationship between 0 degree Asker C hardness and 90 degree Asker C hardness. 1 is a diagram showing the relationship between 0 degree Asker C hardness and 90 degree Asker C hardness. FIG. 1 is a diagram showing a method for measuring thermal insulation under stress.
• the present invention relates to a method for producing a first laminated sheet, the first laminated sheet including a rubber composition including a curing agent, a foaming agent, and an uncured and unfoamed silicone rubber fixed between two supporting members; and step 2 of heating the first laminate sheet to cure and foam the uncured and unfoamed silicone rubber, thereby producing a second laminate sheet in which a silicone rubber layer including a group of elongated holes is fixed between the two support members.
• a first laminate sheet is prepared in which a rubber composition containing a curing agent, a foaming agent, and an uncured and unfoamed silicone rubber is fixed between two support members.
• the curing agent is added to impart appropriate elasticity to the rubber composition when it is foamed.
• the curing agent include organic peroxide curing agents such as alkyl peroxy esters, peroxy ketals, dialkyl peroxides, hydroperoxides, and ketone peroxides, and addition reaction curing agents consisting of organopolysiloxanes having two or more silicon-bonded hydrogen atoms (hydrosilyl groups) in one molecule and platinum compounds serving as curing catalysts.
• the crosslinking initiation temperature of the curing agent is preferably 70 to 200°C.
• organic peroxide curing agents such as Perhexa HC, Perhexa C, Perhexa V, Perhexa 25B, Perbutyl P, Perbutyl C, Percumyl D, Niper BMTM, Perhexa 25Z, Perhexyl Z, Perbutyl ZT, and Perbutyl Z (all manufactured by NOF Corporation), and TC-1, TC-3, TC-4, TC-8, and TC-12 (all manufactured by Momentive Performance Materials, Inc.).
• organic peroxide curing agents such as Perhexa HC, Perhexa C, Perhexa V, Perhexa 25B, Perbutyl P, Perbutyl C, Percumyl D, Niper BMTM, Perhexa 25Z, Perhexyl Z, Perbutyl ZT, and Perbutyl Z (all manufactured by NOF Corporation), and TC-1, TC-3, TC-4, TC-8, and TC-12 (all manufactured by Momentive Performance Materials, Inc
• the amount of the curing agent is preferably 0.01 to 10.0 parts by mass, more preferably 0.1 to 5.0 parts by mass, and even more preferably 0.1 to 1.0 parts by mass, per 100 parts by mass of silicone rubber. If the amount of the curing agent is within the above range, it is preferable in terms of compressive stress against strain.
• the foaming agent is a component that, when dispersed in a rubber composition, is heated, (i) the size of the foaming agent physically expands within the composition, or (ii) a chemical decomposition reaction occurs to generate gas, forming a group of holes within the rubber composition, forming a porous structure when the composition hardens.
• An example of the (i) type blowing agent is a thermally expandable microcapsule that contains a thermally expandable substance such as a hydrocarbon solvent in a shell material formed of a thermoplastic resin.
• a thermally expandable substance such as a hydrocarbon solvent in a shell material formed of a thermoplastic resin.
• Commercially available products of the (i) type blowing agent include Matsumoto Microsphere F-35D, F-36, F-50, F-65, FN-78D, and F-100M (all manufactured by Matsumoto Yushi Seiyaku Co., Ltd.).
• examples of the (ii) type blowing agent include sodium bicarbonate, dinitrosopentamethylenetetramine, azodicarbonamide, and azobisisobutyronitrile.
• Commercially available products of the (ii) type blowing agent include ME800 (manufactured by Momentive Performance Materials, Inc.).
• the amount of the foaming agent is preferably 0.1 to 20.0 parts by mass, more preferably 0.5 to 10.0 parts by mass, and even more preferably 1.0 to 7.0 parts by mass, per 100 parts by mass of silicone rubber.
• the amount of the foaming agent is within the above range, a good balance between hardness, compression set, and foaming ratio is achieved, and this is preferable from the viewpoint of heat insulation properties under stress load.
• the millable silicone rubber preferably contains diorganopolysiloxane.
• diorganopolysiloxanes include TSE270-8U and TSE-221-8U manufactured by Momentive Performance Materials, Inc.
• the molecular chain terminals of the diorganopolysiloxane may be blocked with a trimethylsilyl group, a dimethylvinylsilyl group, a dimethylhydroxysilyl group, a trivinylsilyl group, or the like.
• the weight average molecular weight of the silicone rubber is preferably 1.0 ⁇ 10 5 to 1.0 ⁇ 10 6.
• the weight average molecular weight is a value measured by gel permeation chromatography (GPC).
• the rubber composition can be produced by kneading the curing agent, the foaming agent, and the uncured and unfoamed silicone rubber until the mixture is homogenous using a twin-screw roll, a kneader, a mixer, etc.
• the method for producing the rubber composition is not limited to the above-mentioned method, and can be adjusted or changed as appropriate depending on the application. Therefore, it is preferable to have, before step 1, a step 0 of preparing a rubber composition containing the curing agent, the foaming agent, and an uncured and unfoamed silicone rubber by kneading.
• Support members include ceramics, cloth, aluminum sheets, glass cloth, porous heat-insulating sheets, silica aerogel, etc. Support members are not limited to the above, and for example, metal plates with tiny ventilation holes or heat-insulated aluminum plates can also be used.
• the support member is preferably a flame-retardant insulating material, since flame retardancy is required.
• a non-flame-retardant member may also be combined with a flame-retardant member.
• a laminated sheet in which a rubber composition is fixed and then foamed using cloth, an aluminum sheet with fine irregularities, or the like may be laminated with a flame-retardant insulating material layered on the outside of the cloth or aluminum sheet with fine irregularities to form a support member.
• the support member is preferably a breathable member, more preferably a porous member, and even more preferably at least one member selected from the group consisting of glass cloth, porous heat insulating sheet, and silica aerogel.
• the heat insulating sheet is, for example, a sheet of material such as glass fiber or ceramic fiber.
• the thickness of the support member is not particularly limited, but is preferably 0.05 to 3.0 mm, and more preferably 0.05 to 1.0 mm. A thickness within the above range is preferable because it makes the support member easier to handle and reduces unevenness in the thickness of the laminated sheet caused by the expansion force when the silicone rubber foams.
• the support member preferably has a thermal conductivity of 0.20 W/m ⁇ K or less. If the thermal conductivity is within the above range, it can meet the thermal conductivity required when sandwiched between battery cells.
• Fixing means to determine the position to such an extent that the position does not shift.
• the fixing may be performed by adhesion, fusion, bonding, anchor effect due to uneven surfaces, physical fixation, or adhesion.
• adhesion is preferred from the viewpoint of reliable fixing while taking into consideration the compatibility of the materials used in the present application.
• adhesive media include cyanoacrylate adhesives, acrylic resin adhesives, and silicone rubber adhesives that can be used for bonding silicone rubber.
• the specific procedure for fixing the rubber composition between the support members is to adjust the kneaded rubber composition to the desired thickness using a roll or the like, and then extrude it into a cylinder, a rectangular column, or a similar shape.
• the support members are brought into contact with both sides of the shaped rubber composition, and the rubber composition is fixed between the support members. If the fixing is by adhesion, an adhesive is applied to the support members and dried, and then the adhesive-coated sides of the support members are attached to both sides of the shaped rubber composition, taking care not to allow air bubbles to get in, to fix them in place.
• the procedure for fixing is not limited to the above, and can be changed as appropriate depending on the combination of the support members and the rubber composition.
• Step 2 The first laminate sheet is heat-treated to foam and harden the uncured and unfoamed silicone rubber, thereby producing a second laminate sheet in which a silicone rubber layer including a group of elongated holes is fixed between the two support members.
• the silicone rubber layer containing the long and narrow holes may be referred to as a sponge.
• the heating temperature is not particularly limited as long as it is equal to or higher than the foaming temperature of the foaming agent and equal to or lower than the decomposition temperature of the silicone rubber, but is preferably 150 to 200° C.
• the heating means is not particularly limited, but examples thereof include a hot air oven and a hot plate press.
• heating time there are no particular restrictions on the heating time as long as it is long enough for the foaming agent to finish foaming and hardening to be completed, but 5 to 60 minutes is preferable.
• Heating causes the foaming agent to foam and the silicone rubber to harden, forming a silicone rubber layer containing a group of elongated holes.
• the silicone rubber layer containing the group of elongated holes is fixed between the two support members described above.
• the fixing is the same as that described above in step 1.
• the second laminate sheet in which the obtained silicone rubber layer containing the group of elongated holes is fixed between the two support members is used as a heat insulating cushioning laminate sheet.
• the elongated holes constituting the elongated hole group are preferably formed in the silicone rubber layer so that they have a long axis along the direction in which the two support members face each other.
• step 1 the rubber composition is fixed to the support member, and then in step 2, the rubber composition is foamed, so that the long axis of the elongated hole can be oriented in this direction. Since the elongated hole has a long axis along the direction in which the two support members face each other in the silicone rubber layer, the rubber volume facing from one side to the other side of the silicone rubber layer can be increased, so that the silicone rubber layer can have a higher hardness and a higher resilience (higher apparent spring constant) than a silicone rubber layer in which round or sheet-direction elongated holes are dispersed at the same foaming rate. In other words, high hardness and high resilience can be obtained while maintaining the heat insulation provided by the elongated holes, and appropriate heat insulation, cushioning, and support can be imparted.
• the expansion ratio of the silicone rubber is preferably 2 to 11. If the expansion ratio is 2 or more, the thermal conductivity of the system does not become high, and if the expansion ratio is 11 or less, the reaction force of the silicone rubber layer having the group of elongated holes does not become small during compression, which can prevent the cells themselves from collapsing, and the thermal conductivity during compression does not become high.
• the expansion ratio can be determined by the method described in the Examples.
• the group of elongated holes is not particularly limited, but is usually present throughout the silicone rubber layer, and preferably accounts for 30 to 90 volume % and more preferably 50 to 80 volume % of the total volume of the sheet.
• the silicone rubber layer is porous.
• the long/short ratio (aspect ratio) of one hole in the group of elongated holes is preferably more than 1 and not more than 8, more preferably 2 to 8. If the aspect ratio is not more than the upper limit of the above range, the cells will not be easily crushed when highly compressed in the long side direction, and the gaps will not become small, and when one battery cell generates abnormal heat, the heat transfer to the adjacent cell can be sufficiently suppressed, which is effective in preventing thermal runaway in the entire battery module.
• the aspect ratio of the elongated holes can be determined by the method described in the Examples.
• the Asker C hardness in the direction in which the two support members face each other (referred to as 0 degree Asker C hardness, see FIG. 1) is preferably 40 to 90, more preferably 50 to 85. If the 0 degree Asker C hardness is equal to or higher than the lower limit of the above range, the compressive stress necessary to hold the battery cell can be generated, and if it is equal to or lower than the upper limit of the above range, the compressive stress when the battery cell expands will not be too large, and will not cause damage to the battery cell.
• the hardness is determined by the method described in the Examples.
• the Asker C hardness in the direction intersecting the 0 degree Asker C hardness (referred to as 90 degree Asker C hardness; see Figure 1) is lower than the 0 degree Asker C hardness.
• 90 degree Asker C hardness is lower than the 0 degree Asker C hardness, the two support members are less likely to be crushed when a constant load is applied in the opposing direction, which is advantageous for maintaining voids within the pores.
• the thickness of the silicone rubber layer is not particularly limited, but is preferably 0.1 mm or more, and more preferably 1.0 mm or more. If the thickness of the silicone rubber layer is within the above range, it is preferable because it can exhibit the cushioning and insulating functions of a sponge.
• the air in the gaps in the silicone rubber layer which has a group of elongated holes, gives the cushioning material excellent thermal insulation. Therefore, the cushioning material contributes to low thermal conductivity between adjacent battery cells.
• the temperature of the dummy cell of the second laminate sheet measured by the method described in the Examples is preferably 150° C. or less, more preferably 140° C. or less.
• the compressive stress is a necessary characteristic for a sheet sandwiched between battery cells in a secondary battery, such as a lithium-ion battery, to properly hold the cells.
• the compressive stress of the second laminate sheet at 25% compression measured by the measuring method described in the Examples, is preferably 150N to 500N.
• the silicone rubber layer has a high hardness because the pores constituting the pore group have a major axis along the thickness direction of the silicone rubber layer, and therefore can exert a high compressive stress compared to those having a low hardness, and can bind the battery cell with a strong force.
• step 1 the contact surface of the unfoamed and uncured rubber composition is fixed to the support member before foaming and curing, thereby suppressing expansion of the silicone rubber layer due to foaming, stabilizing the shape, and achieving uniform dispersion of the elongated holes, which in turn suppresses unintended unevenness in heat insulation and load stability. Furthermore, since the unfoamed and uncured rubber composition is foamed after being fixed to the support member, in a preferred embodiment, the elongated holes extend in the thickness direction, and long elongated holes can be formed in the compression direction of the silicone rubber layer without applying compressive or tensile forces to the unfoamed and uncured rubber composition during foaming.
• the heat-insulating cushioning support sheet obtained by the above manufacturing method has support members fixed to both sides of the silicone rubber layer, which has load support and insulating properties due to its porosity, so that the silicone rubber layer does not come into direct contact with the battery, etc., and deterioration of the silicone rubber layer can be suppressed even if the battery, etc., becomes hot.
• a battery cell is a unit that constitutes a storage battery.
• a battery unit is made up of multiple battery cells connected together, and examples of such batteries include lithium-ion batteries.
• a battery unit has multiple battery cells, and the number of battery cells is adjusted appropriately based on the required performance, as long as the number is two or more.
• the heat insulating cushioning laminated sheet is sandwiched between the battery cells and contacts one side of each of the battery cells via the support member.
• the insulating cushioning laminate sheet is fixed by being sandwiched between each of the adjacent battery cells, and there does not need to be a layer for fixing such as an adhesive layer or a pressure-sensitive adhesive layer between the insulating cushioning laminate sheet and the side of each of the adjacent battery cells, but one may be present.
• the insulating cushioning laminate sheet is usually approximately the same size as the side of the battery cell it contacts, but it may be larger or smaller than the side of the battery cell as appropriate depending on the application.
• the long axis of the long hole group of the long hole group is perpendicular to the battery cell.
• the rubber volume facing from one side of the silicone rubber layer to the other side can be increased, so that it can have a higher hardness and a higher resilience (higher apparent spring constant) than a silicone rubber layer in which round or long holes arranged along the sheet direction are dispersed at the same foaming rate.
• high hardness and high resilience can be obtained while maintaining the insulation properties of the long holes, and appropriate insulation, cushioning, and support can be provided.
• the 0 degree Asker C hardness of the silicone rubber layer is in the following preferred range along with the direction of the long axis, a high compressive stress can be generated, and the battery cell can be restrained with a strong force.
• the support member preferably has a thermal conductivity of 0.20 W/m ⁇ K or less. If the thermal conductivity is within the above range, it can meet the thermal conductivity required when sandwiched between battery cells.
• the 0 degree Asker C hardness is preferably 40 to 90, and more preferably 50 to 85. If the 0 degree Asker C hardness is equal to or higher than the lower limit of the above range, the compressive stress necessary to hold the battery cell can be generated, and if it is equal to or lower than the upper limit of the above range, the compressive stress will not become too large when the battery cell expands, and therefore the battery cell will not be damaged.
• the expansion ratio of the silicone rubber in the silicone rubber layer containing the elongated holes is preferably 2 to 11. If the expansion ratio is 2 or more, the thermal conductivity of the system does not become high, and if the expansion ratio is 11 or less, the reaction force of the silicone rubber layer having the elongated holes does not become small during compression, which can prevent the cells themselves from collapsing, and the thermal conductivity during compression does not become high.
• the expansion ratio can be determined by the method described in the Examples.
• the group of elongated holes is not particularly limited, but is usually present throughout the silicone rubber layer, and preferably accounts for 30 to 90 volume % and more preferably 50 to 80 volume % of the total volume of the sheet.
• the silicone rubber layer is porous.
• the long/short ratio (aspect ratio) of one hole in the group of elongated holes is preferably more than 1 and not more than 8, more preferably 2 to 8. If the aspect ratio is not more than the upper limit of the above range, the cells will not be easily crushed when highly compressed in the long side direction, and the gaps will not become small, and when one battery cell generates abnormal heat, the heat transfer to the adjacent cell can be sufficiently suppressed, which is effective in preventing thermal runaway in the entire battery module.
• the aspect ratio of the elongated holes can be determined by the method described in the Examples.
• the temperature of the dummy cell of the thermal insulating cushioning laminate sheet measured by the method described in the Examples is preferably 150° C. or less, more preferably 140° C. or less.
• the compressive stress is a necessary characteristic for a sheet sandwiched between battery cells in a secondary battery, such as a lithium-ion battery, to hold the cells appropriately.
• the heat insulating buffer laminate sheet preferably has a compressive stress of 150N to 500N when compressed by 25% as measured by the measuring method described in the Examples. By setting the compressive stress to 150N or more, a certain binding force can be applied even when cold, and by setting the compressive stress to 500N or less, the load on the battery cell when the battery cell expands can be suppressed from increasing, and the battery cell is not damaged.
• the silicone rubber layer has a high hardness because the pores constituting the pore group have a major axis along the thickness direction of the silicone rubber layer, and therefore can exert a high compressive stress compared to those having a low hardness, and can bind the battery cell with a strong force.
• the expansion ratio is a value calculated by (specific gravity of solid rubber after curing/specific gravity of silicone rubber after foaming and curing) ⁇ 100 (%), and the specific gravity was measured according to the method described in JIS K 6268.
• Aspect ratio of the elongated holes and angle of the long diameter of the elongated holes relative to the direction opposite to the two support members A central portion of the silicone rubber layer containing the group of elongated holes in the second laminated sheets obtained in the Examples and Comparative Examples was cut out, and the cross section was observed at a magnification of 216x using a laser microscope OLS4000 (manufactured by Olympus) to determine the aspect ratio of the elongated holes and the angle of the long diameter of the elongated holes relative to the thickness direction (vertical direction) of the silicone rubber layer.
• the aspect ratio is the value of the long diameter of a narrow hole/the short diameter of a narrow hole.
• Thermal insulation during compression was evaluated using an apparatus as shown in FIG. 3 below.
• an iron block hereinafter referred to as heat generating cell 1 with dimensions of 149 ⁇ 91 ⁇ 20 mm was placed above and heated to 600° C.
• An aluminum block hereinafter referred to as dummy cell 4 with dimensions of 149 ⁇ 91 ⁇ 50 mm was placed below it and kept at a temperature of 25° C.
• the second laminated sheet obtained in the examples and comparative examples with dimensions of 140 ⁇ 90 ⁇ 3 mm was placed on the upper surface of the dummy cell.
• the upper heat generating cell was lowered and pressed against the second laminated sheet (2 and 3) with a load of 1.0 MPa, and the temperature was measured using a thermocouple placed between the dummy cell and the insulating material, and the thermal insulation was evaluated based on the maximum temperature reached on the surface of the dummy cell within 60 minutes after the heat generating cell was pressed against it.
• Example 1 Silicone rubber, a curing agent, and resin beads (foaming agent) and a chemical foaming agent were kneaded in the proportions shown in Table 1 in a LABOLATORY MILL (manufactured by Kansai Roll Co., Ltd.) to prepare a rubber composition containing the curing agent, the foaming agent, and uncured, unfoamed silicone rubber.
• the obtained rubber composition was fixed between two pieces of glass cloth using an adhesive called LOCTITE 454 (manufactured by Henkel) to produce a first laminate sheet (Step 1).
• the first laminate sheet was heated at 200°C for 30 minutes to foam and harden the silicone rubber, thereby forming a silicone rubber layer containing a group of elongated holes, and a second laminate sheet was produced in which the silicone rubber layer was adhered between two support members (Step 2). Since the angle of the long diameter of the long hole with respect to the vertical direction of the silicone rubber layer is 0 degrees, the long holes constituting the long hole group are formed in the silicone rubber layer so as to have their long axes along the direction facing the two support members.
• Figure 1 shows a schematic diagram of the laminated sheets of Example 1 and the following Examples 2 to 7, as well as the measurement surface of the Asker C hardness.
• Examples 2 to 5 A second laminate sheet was produced in the same manner as in Example 1, except that the rubber composition was changed to the composition shown in Table 1.
• Example 6 A second laminate sheet was produced in the same manner as in Example 2, except that the rubber composition of Example 2 was fixed between two sheets of insulation sheet A instead of between two sheets of glass cloth to form a first laminate sheet.
• Example 7 A second laminate sheet was produced in the same manner as in Example 2, except that the rubber composition of Example 2 was fixed between two sheets of insulation sheet B instead of between two sheets of glass cloth to form a first laminate sheet.
• Example 8 A second laminate sheet was produced by carrying out steps 1 and 2 in the same manner as in Example 2. A silicone rubber layer was cut out from the obtained second laminate sheet and bonded between two pieces of glass cloth the same as in Example 2 so that the long axis direction of the group of elongated holes differed by 90° from that of the second laminate sheet to produce a laminate sheet.
• Figure 2 shows a schematic diagram of the laminate sheet of Example 8 and the measurement surface of the Asker C hardness.
• Example 1 A second laminate sheet was produced in the same manner as in Example 1, except that the rubber composition did not contain a foaming agent as shown in Table 1.
• Example 2 A second laminate sheet was produced in the same manner as in Example 2, except that the composition of the rubber composition was the composition shown in Table 1 and the first laminate sheet was composed only of the rubber composition without containing the two glass cloths.
• Examples 1 to 5 and Comparative Example 1 are comparisons of the amount of foaming agent added when a silicone rubber layer is used.
• Examples 1 to 3 as the foaming ratio increases from 2 to 7 times, the compressive stress decreases, but the heat insulating property during compression increases.
• the heat insulating property during compression decreases and the compressive stress increases.
• the pore shape cannot be maintained at a constant compressive stress and the foam collapses, so the heat insulating property during compression decreases, and the compressive stress at a constant compression ratio decreases due to the large number of voids.
• Example 2 and Example 8 are comparisons of the angle of the long direction of the slit with respect to the direction in which the two supporting members face each other in the silicone rubber layer when a rubber composition of the same composition is used, whether the angle of the long direction of the slit with respect to the direction in which the two supporting members face each other is 0 degrees or 90 degrees.
• the angle of the cell long direction with respect to the direction in which the two supporting members face each other is 0 degrees in the silicone rubber layer as in Example 2, the compression stress increases when a certain load is applied, so that voids remain in the silicone rubber layer, and the heat insulating property during compression is high.
• Example 2 and Comparative Example 2 are comparisons of the difference between the presence and absence of a support member when using a rubber composition of the same composition.
• the second laminated sheet in which the support members are bonded to both sides of the silicone rubber layer in Example 2 shows excellent low heat insulation during compression and excellent compressive stress.
• the silicone rubber layer without a support member as in Comparative Example 2 has difficulty in maintaining the shape of the silicone rubber layer during foaming in step 2, so that the thermal conductivity during compression is high and the heat insulation is poor.
• the compressive stress at a constant compression rate is also low.
• Examples 2, 6, and 7 were obtained by observing the characteristics due to the difference in thermal conductivity of the support member when using rubber compositions of the same composition. Comparing Examples 2, 6, and 7, the smaller the thermal conductivity of the support member, the better the heat insulation during compression.
• the heat insulating and cushioning laminated sheet obtained by the manufacturing method of the present invention is suitable for use as a heat insulating and cushioning material between battery cells of a battery unit.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Laminated Bodies (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=95896714

Family Applications (1)

Country Status (2)

Citations (5)

Family Cites Families (2)

• 2024
  • 2024-11-28 JP JP2025524392A patent/JPWO2025115971A1/ja active Pending
  • 2024-11-28 WO PCT/JP2024/042188 patent/WO2025115971A1/ja active Pending

Patent Citations (5)

Also Published As

Similar Documents

Legal Events