阅读说明：本技术 绝缘片以及组合电池 (Insulating sheet and assembled battery ) 是由 西川明良 东崎哲也 石野爱 竹川淳 赤尾俊和 于 2019-08-20 设计创作，主要内容包括：本发明的目的在于提高组合电池的安全性。绝缘片(10)夹入到将平面部(34)彼此对置配置的电池单元(20)间,且由含有无机填充剂的树脂组合物形成。组合电池(50)具备：具有平面部(34)的多个电池单元(20)；以及绝缘片(10),在将平面部(34)彼此对置配置后的多个电池单元(20)中的至少1个对置配置部(36)夹入有绝缘片(10)。(The purpose of the present invention is to improve the safety of an assembled battery. The insulating sheet (10) is sandwiched between the battery cells (20) arranged with the planar sections (34) facing each other, and is formed of a resin composition containing an inorganic filler. The assembled battery (50) is provided with: a plurality of battery cells (20) having a planar portion (34); and an insulating sheet (10) that sandwiches the insulating sheet (10) between at least 1 opposed arrangement portion (36) of the plurality of battery cells (20) in which the planar portions (34) are arranged to be opposed to each other.)

1. An insulating sheet, which is characterized in that,

the insulating sheet is sandwiched between the battery cells arranged with the flat surface portions facing each other,

the insulating sheet is formed from a resin composition containing an inorganic filler.

2. The insulating sheet according to claim 1,

the content of the inorganic filler is in the range of 30-95 mass% in 100 mass% of the resin composition.

3. Insulating sheet according to claim 1 or 2,

a fiber-reinforced material is embedded in the insulating sheet.

4. The insulating sheet according to any one of claims 1 to 3,

the inorganic filler is at least 1 selected from the group consisting of divalent or trivalent metal hydroxide, divalent metal sulfate hydrate, zinc oxysalt, silica, alumina, dawsonite, and sodium bicarbonate.

5. The insulating sheet according to any one of claims 1 to 4,

the resin composition contains at least 1 resin selected from the group consisting of a polyurethane resin, an epoxy resin, a silicone resin, a phenol resin, an unsaturated polyester resin, and a melamine resin as a resin component.

6. The insulating sheet according to claim 5,

in the resin composition, the resin component is a polyurethane resin, and the inorganic filler is a divalent or trivalent metal hydroxide.

7. A battery pack is characterized by comprising:

a plurality of battery cells having a planar portion; and

the insulating sheet according to claim 1 to 6,

the insulating sheet is sandwiched between at least 1 facing arrangement portion of the plurality of battery cells in which the planar portions are arranged to face each other.

Technical Field

The present invention relates to an insulating sheet interposed between battery cells and a battery pack using the insulating sheet.

Background

Lithium ion secondary batteries are small and lightweight rechargeable batteries, and have a large storage capacity per unit volume or per unit mass. Therefore, the present invention is widely used in mobile phones, notebook computers, Personal Digital Assistants (PDAs), video cameras, digital cameras, and the like, and is indispensable for small-sized, lightweight, and large-power-consumption mobile devices. In addition, the battery is also widely used for large-sized batteries, such as electric vehicles and stationary storage batteries for houses.

Based on such characteristics, the lithium ion secondary battery is considered as a key technology in the battery technology as energy saving and energy storage, but in recent years, safety has been emphasized due to the occurrence of accidents, recovery, and the like of the lithium ion secondary battery in succession, and improvement of reliability of the battery has been strongly desired.

For example, a method of changing or improving the material used in the battery and a method of improving the material used in the production of a battery pack from a plurality of battery cells are included in order to improve the safety of the battery. Resin potting is known as a material for improving safety used in manufacturing assembled batteries (assembled batteries) such as battery packs.

In the manufacture of the assembled battery by resin potting, the following method can be adopted: after a plurality of battery cells are combined in series and parallel to form a module, the module is stored in a mold or a bag, and a liquid resin (potting material) is injected into the module and cured (see patent document 1). This method has disadvantages in that it is difficult to control the resin to a uniform thickness, and it is not easy to fill the resin so as not to contain bubbles. Further, there is a problem that the resin flows into an unnecessary portion (for example, a gap between heat-fusion-bonded portions around the cell main body) to increase the quality. In addition, there is a problem that heating is required to cure the resin, and the curing of the resin takes time, and inspection after potting is difficult.

In order to suppress heat generation in the assembled battery and prevent ignition between the battery cells, patent document 2 describes: the heat absorbing material is provided between the battery cell and the fixing member located at a position surrounding the outer peripheral surface of the battery cell, or between the surfaces of the adjacent battery cells facing each other. In this document, a mixture of 5 to 25 mass% of silica and 75 to 95 mass% of water is used as a heat absorbing material, and the mixture is applied to the outer peripheral surfaces of the battery cells and between the stacked battery cells, and there is no description about the use of an insulating sheet formed of a resin composition containing an inorganic filler.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2014-103123

Patent document 2: japanese examined patent publication No. 2016-533022

Disclosure of Invention

Technical problem to be solved by the invention

An object of an embodiment of the present invention is to provide an insulating sheet capable of improving the safety of an assembled battery, and an assembled battery using the insulating sheet.

Means for solving the problems

The insulating sheet according to the embodiment of the present invention is an insulating sheet interposed between battery cells arranged with the planar portions facing each other, and is formed of a resin composition containing an inorganic filler.

An assembled battery according to an embodiment of the present invention includes: a plurality of battery cells having a planar portion; and an insulating sheet sandwiched between at least 1 facing arrangement portion of the plurality of battery cells after the plane portions are arranged to face each other.

Effects of the invention

According to the embodiment of the present invention, since the insulating sheet made of the resin composition containing the inorganic filler is sandwiched between the battery cells having the flat surface portions facing each other, the safety of the assembled battery can be improved. Further, since the insulating sheet is formed into a sheet shape in advance and sandwiched between the battery cells, it is not necessary to cure the insulating sheet when assembling the assembled battery. In addition, since the dead space is not entered as in the case of resin potting, the assembled battery can be assembled with minimal increase in quality. In addition, the thickness can be easily controlled when the insulating sheet is manufactured, and the dimensional accuracy between the battery cells can be improved.

Drawings

Fig. 1 is a plan view of an insulating sheet according to an embodiment.

Fig. 2 is a sectional view of the insulating sheet.

Fig. 3 is a perspective view of a battery unit according to an embodiment.

Fig. 4 is a perspective view of an assembled battery according to an embodiment.

Fig. 5 is a schematic side view of the assembled battery.

Fig. 6 is a plan view of the assembled battery.

Description of the symbols

10 insulating sheet, 12 resin composition, 14 fiber-reinforced material, 20 battery cells, 34 flat portions, 36 facing arrangement portions, and 50 assembled battery

Detailed Description

Hereinafter, representative embodiments of the present invention will be described with reference to the drawings. In the following, the same or corresponding elements are denoted by the same reference numerals throughout the drawings, and redundant description thereof will be omitted.

The insulating sheet according to the present embodiment is a sheet that is used by being sandwiched between battery cells arranged with their planar portions facing each other, and can electrically insulate the battery cells from each other. The insulating sheet is a resin sheet formed from a resin composition containing an inorganic filler.

The resin composition constituting the insulating sheet may contain a resin component and an inorganic filler. Examples of the resin component include various resins (polymers or plastics), and examples of typical resin components include: polyurethane resin, epoxy resin, silicone resin, phenol resin, unsaturated polyester resin, melamine resin, and the like. These resins may be used in any 1 kind, or 2 or more kinds may be used in an appropriate combination (for example, as a polymer blend, a polymer alloy, or the like).

Further, even with the same kind of resin, 2 or more kinds of resins having different chemical structures or the like may be used in combination. For example, in the case where the resin component is a polyurethane resin, 2 or more kinds of polyurethane resins using different combinations of polyisocyanate and polyol can be used. Even if the combination of polyisocyanate and polyol is the same, 2 or more types of polyurethane resins obtained by changing the synthesis conditions can be used.

In the insulating sheet according to the present embodiment, among the above-described resins, a urethane resin can be particularly preferably used as the resin component. The insulating sheet according to the present embodiment preferably has elasticity or flexibility, and the urethane resin can be used to produce sheets having a wide range of elasticity or flexibility.

In addition, the ability of the polyurethane resin to achieve a wide range of elasticity or flexibility means that the elasticity or flexibility can be controlled as desired. Therefore, an insulating sheet having excellent elasticity or flexibility can be obtained depending on the structure of the assembled battery and the like. Further, the polyurethane resin has a relatively low viscosity at the time of processing compared with other resins, and can be cured at normal temperature without requiring high temperature. Therefore, workability and manufacturing efficiency in manufacturing the insulating sheet can be improved.

The resin composition constituting the insulating sheet is not particularly limited in storage modulus at 25 ℃, and may be, for example, 0.1 to 200 MPa. By providing flexibility in this manner, the cushioning effect of absorbing vibration and shock can be improved. Here, the storage modulus at 25 ℃ was measured by the method prescribed in JIS K7244-4 (tensile vibration non-resonance method, frequency 10 Hz).

The more specific structure of the polyurethane resin is not particularly limited. For example, as the polyisocyanate and the polyol used as the raw materials of the polyurethane resin, known raw materials can be suitably selected. For example, typical examples of the polyisocyanate include aromatic, alicyclic or aliphatic polyisocyanates having 2 or more isocyanate groups, and modified polyisocyanates obtained by modifying the same. These polyisocyanates may be prepolymers. Further, as the polyol, typically, polyether polyol, polyester polyol, polyhydric alcohol, hydroxyl group-containing diene polymer, and the like can be cited. These polyisocyanates and polyols may be used alone in 1 kind, or may be used in combination of 2 or more kinds as appropriate. In addition, a catalyst that promotes the resination reaction of the polyisocyanate and the polyol may be used. Examples of the catalyst include: amine catalysts, metal compound catalysts, isocyanurate catalysts, and the like. These catalysts may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The resin composition constituting the insulating sheet contains at least an inorganic filler in addition to the resin component. The inorganic filler can contribute to the flame retardancy or heat dissipation of the insulating sheet. Specific examples of the inorganic filler include: divalent or trivalent metal hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; divalent metal sulfate hydrates such as calcium sulfate hydrate and magnesium sulfate hydrate; zinc oxyacid salts such as zinc borate and zinc stannate; silicon dioxide; alumina; dawsonite; sodium bicarbonate, and the like. These inorganic fillers may be used alone in 1 kind, or may be suitably selected from 2 or more kinds.

In the insulating sheet according to the present embodiment, among the above inorganic fillers, divalent or trivalent metal hydroxides, for example, aluminum hydroxide, magnesium hydroxide, or the like are particularly preferably used. The divalent or trivalent metal hydroxide generates water by heating, and therefore, it is possible to impart excellent flame retardancy to the insulating sheet and also to improve heat dissipation properties.

As the inorganic filler, divalent metal sulfate hydrate such as calcium sulfate hydrate, magnesium sulfate hydrate, and the like can also be preferably used. Divalent metal sulfate hydrates, as well as divalent or trivalent metal hydroxides, also produce water upon heating. Alternatively, sodium hydrogencarbonate can also be preferably used as the inorganic filler. Sodium bicarbonate also produces water as a result of heating. Further, sodium hydrogencarbonate may be used in combination with a divalent or trivalent metal hydroxide. Sodium bicarbonate is relatively inexpensive compared to aluminum hydroxide or magnesium hydroxide. Thus, by using them in combination, it is possible to achieve good flame retardancy and heat dissipation and reduce an increase in the manufacturing cost of the insulating sheet.

In one embodiment, the resin composition preferably has a polyurethane resin as the resin component and a divalent or trivalent metal hydroxide as the inorganic filler.

The inorganic filler may be blended in the resin component in the form of powder. The average particle diameter of the inorganic filler is not particularly limited, and may be in the range of usually 0.5 to 40 μm, more preferably 2 to 20 μm. The shape of the powder of the inorganic filler is not particularly limited, and various shapes such as a spherical shape, a flaky shape (scaly shape), a needle shape, and an irregular shape can be used. Here, the average particle diameter (D50) can be determined by particle size analysis by a known laser diffraction method.

The resin composition constituting the insulating sheet may contain known additives in addition to the resin component and the inorganic filler. Examples of the additives include a foaming agent, a foam stabilizer, a colorant, a flame retardant, and a plasticizer, and are not particularly limited.

The resin composition may contain a flame retardant in order to impart flame retardancy to the insulating sheet. The flame retardant is not particularly limited, and examples thereof include: phosphorus flame retardants, halogen flame retardants, melamine flame retardants, and the like. Examples of the phosphorus-based flame retardant include: halogen-containing phosphates such as tris (2-chloroethyl) phosphate and tris (2, 3-dibromopropyl) phosphate; halogen-free phosphates such as trimethyl phosphate, tricresyl phosphate, trixylyl phosphate, and triphenyl phosphate; ammonium polyphosphate; and the like. Examples of the halogen-based flame retardant include decabromodiphenyl ether, pentabromodiphenyl ether, hexabromocyclododecane, tetrabromobisphenol a, and hexabromobenzene. Further, as the melamine-based flame retardant, cyanurate such as melamine can be mentioned. Further, antimony compounds such as antimony trioxide can also be used as the flame retardant. The antimony compound can be used in combination with a halogen flame retardant to further improve flame retardancy.

The specific composition of the resin composition constituting the insulating sheet is not particularly limited. For example, the content of the inorganic filler is not particularly limited, and considering the flame retardancy of the obtained insulating sheet, the content (content ratio) of the inorganic filler is preferably in the range of 30 to 95 mass%, more preferably in the range of 45 to 70 mass%, and may be in the range of 50 to 70 mass% when the total amount of the resin composition (total resin composition) is 100 mass%. When the content of the inorganic filler is 30% by mass or more, the insulating sheet can be easily provided with good flame retardancy and heat dissipation properties, depending on the kind of the inorganic filler or the resin component. Of course, the content of the inorganic filler can be appropriately set according to the properties of the insulating sheet to be obtained, but is not particularly limited to the above range.

The insulating sheet may be embedded with a fiber-reinforced material. The resin composition and the fiber-reinforced material are structurally combined by embedding the fiber-reinforced material, whereby the strength of the insulating sheet can be increased, and the effect that breakage is less likely to occur when the assembled battery is manufactured or when the battery cell is expanded and deformed can be obtained.

Examples of the fiber-reinforced material include synthetic fibers such as glass fibers, polyester, and aramid fibers, and fibers made of an insulating material are preferably used. More specifically, a glass fiber substrate made of glass fibers such as glass roving, a polyester fiber substrate made of polyester yarn, and the like can be given. The shape of the fiber-reinforced material, that is, the shape of the substrate such as a glass fiber substrate or a polyester fiber substrate is not particularly limited, and may be a woven fabric, a knitted fabric, or a nonwoven fabric, or may be a material in which filaments are aligned in parallel at predetermined intervals.

Fig. 1 is a plan view showing an example of an insulating sheet 10 in which a fiber-reinforced material 14 is embedded in a resin composition 12, and fig. 2 is a cross-sectional view thereof. The insulating sheet 10 has a rectangular planar shape, and fiber-reinforced members 14 in which filaments made of glass fibers, synthetic fibers, or the like are arranged in parallel at predetermined intervals are embedded.

As a method for embedding the fiber-reinforced material in the insulating sheet, a known method for molding fiber-reinforced plastic (FRP) can be used, and examples thereof include: drawing forming, sheet winding, pin winding, filament winding, SMC, hand lay-up, and the like. In the drawing, a fiber-reinforced material is impregnated with a resin, drawn into a mold, cured in the mold into a predetermined cross-sectional shape, and drawn by a drawing device, and can be preferably used in the present embodiment.

The ratio of the fiber-reinforced material in the insulating sheet is not particularly limited, and for example, the fiber volume occupancy Vf may be 20 to 60%, or 30 to 60%. By setting the fiber volume occupancy Vf to 20% or more, the strength improvement effect can be improved. Further, by setting the content to 60% or less, the occupancy of the resin composition can be ensured, and the effects of insulation and heat dissipation based on this can be advantageously exhibited. Here, the fiber volume occupancy Vf is a percentage of the volume occupied by the fiber reinforcement material when the total volume of the insulating sheet is taken as 100%.

The content of the fiber-reinforced material in the insulating sheet is not particularly limited, and may be 25 to 65 mass%, or 35 to 65 mass% with the mass of the entire insulating sheet being 100 mass%.

The insulation property of the insulating sheet is not particularly limited, and for example, the volume resistivity is preferably 1X 10⁸Omega cm or more. The volume resistivity can be measured by using an insulation resistance meter and a method specified in JIS K6911.

The insulating sheet is a planar sheet sandwiched between opposing planar portions between adjacent battery cells. The thickness (T0) (see fig. 2) of the insulating sheet is not particularly limited. It is preferable to secure a predetermined interval in the formation of the assembled battery so as to suppress the occurrence of thermal links such as ignition between adjacent battery cells. The thickness of the insulating sheet is preferably 0.5mm or more, and may be in the range of 0.5 to 4.0mm, or 0.8 to 3.0mm, for example. By setting the thickness of the insulating sheet to 0.5mm or more, the strength of the insulating sheet can be easily secured, and the effect of suppressing the thermal link can be improved. Further, by setting the thickness to 4.0mm or less, an increase in the quality of the assembled battery can be suppressed, and a decrease in the energy density of the assembled battery can be reduced.

Next, a battery pack using the insulating sheet will be described. An assembled battery according to an embodiment includes: a plurality of battery cells having a planar portion; and an insulating sheet sandwiched between at least 1 facing arrangement portion of the plurality of battery cells in which the planar portions are arranged to face each other.

The type of the battery cell is not particularly limited, and various known batteries can be used. Specifically, for example, a secondary battery such as a lithium ion battery, a nickel cadmium battery, and a nickel hydrogen battery can be given. Among these, a lithium ion battery is particularly preferable as the battery cell.

As the battery cell, a battery cell having a flat surface portion is used, and for example, a plate-shaped battery cell also called a laminate-type battery cell may be used, or a square-shaped (square column-shaped or rectangular-shaped) battery cell may be used. Each battery cell preferably has a plurality of flat surface portions so that the flat surface portions of the plurality of battery cells can be arranged to face each other to form the assembled battery.

As an example of the battery cell, a laminate type battery cell will be described. Fig. 3 shows an example of a laminated lithium ion battery cell 20. A laminated lithium ion battery cell is a battery cell in which an electrode assembly (also referred to as a battery element) including a positive electrode, a negative electrode, and a separator disposed therebetween is housed in a laminated film, and known battery cells can be used.

The battery unit 20 shown in fig. 3 includes an electrode assembly 22 having a rectangular plate shape and a laminate film 24. Laminate film 24 is constituted as follows: the electrode assembly 22 is housed inside the peripheral edge 26 of 2 rectangular sheets 24a and 24a formed by covering both surfaces of a metal layer with resin layers by heat-sealing. Specifically, a recess 25 for housing the electrode assembly 22 is formed in advance in the laminate film 24, the electrode assembly 22 is placed in the recess 25, the peripheral edge 26 is heat-welded to form the battery cell 20, and the portion of the recess 25 in which the electrode assembly 22 is housed constitutes a rectangular plate-shaped cell main body 21.

In the example shown in fig. 3, recesses 25 are formed in the inner and outer 2 rectangular sheets 24a and 24a constituting the laminate film 24, respectively, and the two sheets are overlapped with each other, so that a space for accommodating the electrode assembly 22 is formed in 2 recesses 25. This may also be replaced by: the recess 25 is formed only in one rectangular sheet 24a, and the other rectangular sheet 24a is a flat sheet, and a space for accommodating the electrode assembly 22 is formed between the one recess 25 and the other flat surface by overlapping the two.

The electrode assembly 22 is provided with a positive electrode terminal 28 and a negative electrode terminal 30 electrically connected to a positive electrode tab and a negative electrode tab, respectively, and these positive electrode terminal 28 and negative electrode terminal 30 are led out from the laminated film 24 to the outside. In this example, the positive electrode terminal 28 and the negative electrode terminal 30 are drawn from the same side of the rectangular laminated film 24. Further, insulating films 32 made of polypropylene are provided on both upper and lower surfaces of the positive electrode terminal 28 and the negative electrode terminal 30.

In the battery cell 20 shown in fig. 3, the cell main body 21 having a rectangular plate shape has flat surface portions 34 and 34 on both the inner and outer surfaces. That is, in this example, the flat surface portions 34 are provided in a rectangular shape on both the inner and outer surfaces of the battery cell 20.

As shown in fig. 4, a plurality of battery cells 20 are stacked one on another so that their flat surface portions 34 face each other, that is, unit main bodies 21 having a rectangular plate shape are stacked, whereby an assembled battery 50 is configured. In this example, 4 battery cells 20 are stacked, but the number of battery cells 20 is not particularly limited.

As shown in fig. 4 and 5, the insulating sheet 10 is sandwiched between the facing planar portions 34, that is, between the facing planar portions 34, 34 of the adjacent battery cells 20, 20. In this example, since the insulating sheet 10 is provided between all the battery cells 20 and 20 adjacent to each other, the battery cells 20 and the insulating sheets 10 are alternately stacked. The insulating sheet 10 may be provided in at least 1 facing portion 36 of the plurality of battery cells 20 in which the flat portions 34 are arranged to face each other. Here, the facing portion 36 is a portion where the flat portions 34 and 34 are disposed facing each other between the adjacent battery cells 20 and 20. When 3 or more battery cells 20 are stacked, since 2 or more opposed arrangement portions 36 are present, the insulating sheet 10 may be sandwiched between at least 1 opposed arrangement portion 36.

The insulating sheet 10 is preferably formed in a size that covers the entire planar portion 34 of the battery cell 20 (i.e., the entire cell body 21). In this example, as shown in fig. 4 to 6, the battery cell 20 is formed to have a size covering the entire battery cell including the peripheral edge 26 of the laminate film 24.

In the case where the insulating sheet 10 includes the fiber-reinforced material 14 formed of a base material in which the filaments are aligned in parallel, as shown in fig. 1, the filaments of the fiber-reinforced material 14 are preferably aligned in parallel in the longitudinal direction of the cell main body 21 of the battery cell 20, that is, in the longitudinal direction of the rectangular insulating sheet 10. That is, the orientation direction of the filaments in the insulating sheet 10 is preferably aligned with the longitudinal direction of the sheet 10. However, the orientation direction of the filaments may be arranged perpendicular to the longitudinal direction of the insulating sheet 10, or may be arranged in other directions. As described above, a woven fabric, a knitted fabric, or a nonwoven fabric can be used as the fiber reinforcement material, and in the case of using a woven fabric, for example, the warp direction may be aligned with the longitudinal direction of the insulating sheet, or the weft direction may be aligned with the longitudinal direction of the insulating sheet. In the case of the braid, for example, the transverse direction may be aligned with the longitudinal direction of the insulating sheet, or the longitudinal direction may be aligned with the longitudinal direction of the insulating sheet.

When the battery cells are stacked with the insulating sheet interposed therebetween, the battery cells and the insulating sheet may be fixed by an adhesive, may be fixed by a double-sided tape, or may be fixed in a stacked state by a holding member by winding a tape or the like around the outer periphery thereof after the battery cells are stacked without being fixed.

In the assembled battery, the plurality of battery cells may be connected in series or in parallel, and is not particularly limited. Further, an electrical connection member for electrically connecting the plurality of battery cells may be provided. Various components constituting a known assembled battery such as a battery pack may be included.

According to the present embodiment, since the insulating sheets are prepared in advance from the resin composition containing the inorganic filler and the insulating sheets are sandwiched between the battery cells, it is not necessary to cure the resin at the time of assembling the assembled battery, as in the case of resin potting. Further, since the liquid resin does not enter the dead space, the assembled battery can be configured with a minimum increase in quality. In addition, since the thickness can be easily controlled when the insulating sheet is manufactured, the dimensional accuracy between the battery cells is higher than when a liquid potting material is used. Further, since only the insulating sheet is sandwiched between the battery cells, inspection is easy.

In the present embodiment, the insulating sheet made of the resin composition containing the inorganic filler is sandwiched between the battery cells, whereby heat from the battery cells can be favorably released. Therefore, even if a high temperature occurs due to abnormality, ignition, or the like in any one of the battery cells, the insulating sheet can prevent ignition. In addition, by containing the inorganic filler, the resin composition is less likely to flow even when exposed to a flame and at a high temperature. Therefore, the safety of the assembled battery can be improved.

Further, since the strength of the insulating sheet is improved by embedding the fiber-reinforced material in the insulating sheet and combining the fiber-reinforced material with the insulating sheet, it is possible to suppress breakage during production or during an abnormality.

Examples

The present invention will be described in further detail with reference to examples, but the present invention is not limited thereto. The burn resistance test was performed as follows.

(flame resistance test)

The battery cell used was a laminate type lithium ion battery cell having a peripheral edge portion 26 of a length of 140mm, a width of 55mm, a thickness of 4.5mm and a cell capacity of 3Ah, which was manufactured by a company. In the cell outer layer disposed at the lowermost surface of the 4 cells, an eight-cell silicone rubber heater (SBH2012, 25 × 50mm) was provided. Then, an insulating sheet is disposed between the battery cells, and a battery pack having the insulating sheet disposed thereon is manufactured.

A voltage of 100V was applied to the silicone rubber heater and heated to 200 ℃ or higher. The battery connected to the heater was used as a heat source battery, and the battery adjacent to the heat source battery was used as an adjacent battery, and the temperature of the adjacent battery was measured in an environment of 25 ℃.

(examples 1 to 3)

A resin composition having an inorganic filler content of 65 mass% was prepared using a polyurethane resin (trade name: EIMFLEX EF-243, manufactured by first Industrial pharmaceutical Co., Ltd.) as a resin component and aluminum hydroxide (C-310, manufactured by Sumitomo chemical Co., Ltd.) as an inorganic filler. In addition, as the fiber reinforcement, a glass fiber base material including glass roving (manufactured by daiiso chemical co., LTD, Multi-end roving, product number "ER 550E-2400") was used.

3 kinds of insulating sheets (speed 6 cm/min, heating temperature 130 ℃ C.) having a thickness of 3.0mm (example 1), 2.0mm (example 2) and 1.0mm (example 3) were produced by drawing using the resin composition and the fiber-reinforced material. As shown in fig. 1 and 2, the insulating sheet has the following structure: fiber reinforced materials obtained by aligning glass rovings in parallel are embedded. The alignment interval of the glass roving was set as: the width of each 10mm was 15 pieces in example 1, 10 pieces in example 2, and 6 pieces in example 3.

The fiber volume occupancy Vf, which is the ratio of the fiber reinforcing material in the insulating sheet, is shown in table 1 below. The volume resistivity of the insulating sheet is shown in table 1 below.

The insulation sheets of examples 1 to 3 were sandwiched between the battery cells by 1 sheet, and the ignition resistance test was performed. The distance between the adjacent battery cells was 3.0mm in example 1, 2.0mm in example 2, and 1.0mm in example 3. Table 1 shows the results of the ignition resistance test (temperature of the adjacent battery, evaluation of ignition, and state of the insulating sheet after the test).

(examples 4 to 6)

The same resin compositions as in examples 1 to 3 were used, and a polyester fiber base material formed of polyester yarn (product No. K5, manufactured by gun limitted) was used as a fiber-reinforced material. Insulating sheets of 3 thicknesses of 3.0mm (example 4), 2.0mm (example 5) and 1.0mm (example 6) were produced in the same manner as in examples 1 to 3. The polyester fiber base material is a base material formed by parallelly drawing a plurality of twisted polyester yarns, and the drawing interval is set as follows: in terms of the number of the above polyester filaments (i.e., filaments before twisting), 88 filaments were obtained per 10mm width in example 4, 58 filaments were obtained per 10mm width in example 5, and 37 filaments were obtained per 10mm width in example 6. The ignition resistance test was performed in the same manner as in examples 1 to 3 using the insulating sheets of examples 4 to 6. The results are shown in table 1.

(examples 7 to 9)

3 kinds of insulation sheets having thicknesses of 3.0mm (example 7), 2.0mm (example 8) and 1.0mm (example 9) were produced in the same manner as in examples 1 to 3 without using a fiber-reinforced material, and were subjected to a burn resistance test. The results are shown in table 1.

(examples 10 to 12)

Insulating sheets of 3 kinds of thicknesses, 3.0mm (example 10), 2.0mm (example 11) and 1.0mm (example 12), were produced in the same manner as in examples 1 to 3, except that magnesium hydroxide (starmaga, product of shenisai chemical industry) was used as the inorganic filler, and the ignition resistance test was performed. The results are shown in table 1.

(examples 13 to 15)

3 kinds of insulation sheets having thicknesses of 3.0mm (example 13), 2.0mm (example 14) and 1.0mm (example 15) were produced in the same manner as in examples 10 to 12 without using a fiber-reinforced material, and were subjected to a burn resistance test. The results are shown in table 1.

(examples 16 to 18)

Insulating sheets of 3 kinds of thicknesses, 3.0mm (example 16), 2.0mm (example 17) and 1.0mm (example 18), were produced in the same manner as in examples 1 to 3, except that sodium bicarbonate (grade P, manufactured by Tokuyama Corporation) was used as the inorganic filler, and the ignition resistance test was performed. The results are shown in table 1.

(examples 19 to 21)

Insulating sheets of 3 kinds of thicknesses, 3.0mm (example 19), 2.0mm (example 20) and 1.0mm (example 21), were produced in the same manner as in examples 4 to 6 except that sodium hydrogen carbonate (grade P, an industrial product manufactured by Tokuyama Corporation) was used as the inorganic filler, and the ignition resistance test was performed. The results are shown in table 1.

(examples 22 to 24)

3 kinds of insulating sheets having thicknesses of 3.0mm (example 22), 2.0mm (example 23) and 1.0mm (example 24) were produced in the same manner as in examples 16 to 18 without using a fiber-reinforced material, and were subjected to a burn resistance test. The results are shown in table 1.

(examples 25 to 27)

Magnesium sulfate hydrate (industrial TC for purified magnesium sulfate crystals (7-water salt, manufactured by Mozu chemical Co., Ltd.)) was used as an inorganic filler. The resulting mixture was pulverized to an average particle diameter (D50) of 40 μm by a ball mill before use. Except for this, 3 kinds of insulating sheets having thicknesses of 3.0mm (example 25), 2.0mm (example 26) and 1.0mm (example 27) were produced in the same manner as in examples 1 to 3, and were subjected to the ignition resistance test. The results are shown in table 1.

(examples 28 to 30)

3 kinds of insulating sheets having a thickness of 3.0mm (example 28), 2.0mm (example 29) and 1.0mm (example 30) were produced in the same manner as in examples 1 to 3 except that a product obtained by mixing aluminum hydroxide (C-310, manufactured by Sumitomo chemical Co., Ltd.) and sodium hydrogen carbonate (grade P, manufactured by Tokuyama Corporation) at a mass ratio of 1: 1 was used as the inorganic filler, and the flame resistance test was performed. The results are shown in table 1.

(examples 31 to 33)

Insulating sheets of 3 kinds of thickness (3.0 mm (example 31), 2.0mm (example 32) and 1.0mm (example 33) were produced in the same manner as in examples 1 to 3 except that magnesium hydroxide (starmaga, manufactured by sheniso chemical industries) and sodium hydrogen carbonate (P-grade, manufactured by Tokuyama Corporation) were mixed at a mass ratio of 1: 1 as an inorganic filler, and the ignition resistance test was performed. The results are shown in table 1.

(examples 34 to 36)

Using the same resin components and inorganic fillers as in example 3, resin compositions containing 45 mass%, 55 mass%, and 75 mass% of the inorganic filler were prepared. As the fiber reinforcement, a glass fiber base material including the same glass roving (daiiso chemical. co., LTD, Multi-end rovings, product number "ER 550E-2400") as in example 3 was used. Processing was carried out in the same manner as in example 3 to prepare 3 kinds of insulating sheets having a thickness of 1.0mm and inorganic filler contents of 45 mass% (example 34), 50 mass% (example 35) and 75 mass% (example 36), and the ignition resistance test was carried out. The results are shown in Table 1.

Comparative examples 1 to 3

Insulating sheets of 3 thicknesses of 3.0mm (comparative example 1), 2.0mm (comparative example 2) and 1.0mm (comparative example 3) were produced in the same manner as in examples 1 to 3, except that the inorganic filler was not blended in the resin composition (i.e., only the urethane resin was used), and the ignition resistance test was performed. The results are shown in table 1.

Comparative examples 4 to 6

3 kinds of insulation sheets having a thickness of 3.0mm (comparative example 4), 2.0mm (comparative example 5) and 1.0mm (comparative example 6) were produced in the same manner as in comparative examples 1 to 3 without using a fiber-reinforced material, and were subjected to a flame retardant test. The results are shown in table 1.

[ Table 1]

As shown in table 1, it is understood that the insulating sheet according to the example does not cause ignition in the ignition resistance test, and can realize good flame retardancy and heat dissipation properties. Further, it is found that the insulating sheet is less likely to break in the burn resistance test by embedding the fiber reinforcement material. In contrast, the insulating sheet according to the comparative example does not contain an inorganic filler, and therefore, good flame retardancy and heat dissipation properties cannot be achieved, and ignition occurs. In addition, in the insulating sheet having a thickness of 3.0mm in comparative example 1, although the burning did not occur, the melt flow of the resin occurred. From this, it is found that by incorporating an inorganic filler into the insulating sheet, the resin hardly flows even when exposed to a flame and at a high temperature.

As described above, according to the present embodiment, the assembled battery can be manufactured by sandwiching the insulating sheet between the battery cells, and the accuracy of the interval between the battery cells can be improved as compared with filling the potting material in a liquid state. Further, since it is not necessary to use a liquid potting material, it is not necessary to take measures to prevent the potting material from containing bubbles or flowing into unnecessary portions. Further, since it is not necessary to cure the liquid potting material, equipment such as a molding die and a heating means (or a mixing means if the potting material is a 2-liquid mixing type) is not necessary, and a curing time is also not necessary. In addition, since the amount of resin can be reduced as compared with the case of filling the potting material, the weight of the assembled battery can be reduced.

Further, since the insulating sheet is made of resin and contains an inorganic filler, heat can be dissipated well from the battery cells, and heat from the battery cells can be dissipated over the entire insulating sheet in close contact therewith. Therefore, the adjacent battery cells can be prevented from being burnt. In addition, by containing the inorganic filler, the flow of the resin can be suppressed, and the safety of the assembled battery can be improved.

While several embodiments of the present invention have been described above, these embodiments are given as examples only, and are not intended to limit the scope of the invention. These embodiments can be implemented in other various ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. The embodiments, omissions, substitutions, and changes thereof are not limited to the scope and gist of the invention, and are also included in the inventions described in the claims and the equivalent thereof.

Industrial applicability

Embodiments of the present invention can be used not only for mobile device power sources but also for improving the safety of medium-or large-sized batteries mounted as electric bicycles, electric vehicle seats, robots, electric vehicles, emergency power sources, and large-capacity stationary power sources, and can be used for various batteries.