Sealing components and batteries

Abstract

The invention proposes a sealing device that exhibits both the effectiveness of preventing the penetration and leakage of electrolyte solution and the effectiveness of reducing the failure rate of the sealing device. The sealing device is intended for batteries containing aqueous electrolyte solution; the material of the sealing device consists of an elastomer; the compression ratio R of the sealing device when fitted is 50% or more; and the sealing device satisfies Eb ≥ ax βb, where Eb is the elongation at break of the material of the sealing device as measured according to JIS K 6251, β is the shrinkage ratio of the cross-section, a = 6.919 x R - 2.066, and b = 2.278 x R - 1.767.

Description

Sealing member and battery

[0001] The present disclosure relates to a sealing member and a battery.

[0002] In batteries using non-aqueous electrolytes, it is necessary to seal the electrodes, and a sealing member is used for this purpose. The sealing member has the function of preventing leakage or permeation of the non-aqueous electrolyte in the battery (Patent Document 1). Patent Document 2 discloses that such a sealing member is compressed and attached to a cylindrical battery.

[0003] JP 2001-126684 A, JP 2000-30675 A

[0004] An object of the present disclosure is to provide a sealing member that achieves both the effect of suppressing permeation and leakage of an electrolyte and the effect of reducing the incidence of breakage of the sealing member.

[0005] The present disclosure relates to a sealing member for a battery using a non-aqueous electrolyte, wherein a material constituting the sealing member is made of an elastic material, and has a compressibility R of 50% or more when mounted, and wherein, when the breaking elongation of the material constituting the sealing member according to JIS K6251 is Eb and the cross-sectional aspect ratio is β, Eb≧a×β ｂ (a=6.919×R−2.066 b=2.278×R−1.767) The sealing member is preferably in the shape of a circular ring having a rectangular cross section.

[0006] Preferably, T satisfies the following: 0.4 mm≦T≦3.5 mm. Preferably, W satisfies the following: 0.4 mm≦W≦3.5 mm. The compression ratio is preferably 52% or more.

[0007] The elastic material is preferably a fluorine-containing elastomer. The elastic material is preferably an elastomer containing a vinylidene fluoride unit. The sealing member of the present disclosure has a β-value satisfying the following relationship: 3.0≧a×β ｂ It is preferable to satisfy the following: (a=6.919×R−2.066 b=2.278×R−1.767)

[0008] The battery using a non-aqueous electrolyte solution is preferably a lithium ion battery. The battery is preferably a prismatic battery. The present disclosure also relates to a battery using a non-aqueous electrolyte solution, characterized by having any of the sealing members described above.

[0009] The sealing member of the present disclosure is excellent in that it can suppress permeation and leakage of the electrolyte and also reduces the incidence of breakage of the sealing member. By achieving both of these performance properties, the sealing member can be suitably used in batteries that use a non-aqueous electrolyte.

[0010] FIG. 1 is a schematic diagram showing an example of a prismatic battery. FIG. 2 is a schematic diagram showing an example of an electrode. FIG. 3 is a schematic diagram showing an example of a sealing member of the present disclosure. FIG. 4 is a schematic diagram showing a cross-sectional view of an example of a sealing member of the present disclosure. FIG. 5 is a cross-sectional view showing an example of a sealed state of the present disclosure. FIG. 6 is a diagram showing the relationship between compressibility and permeation amount in a sealing member. FIG. 7 is a schematic diagram showing a cross-sectional view of an example of calculating the maximum strain of a sealing member by simulation. FIG. 8 is a diagram showing the relationship between the maximum strain and compressibility on the surface of a sealing member by simulation. FIG. 9 is a diagram showing the relationship between the maximum strain and cross-sectional aspect ratio on the surface of a sealing member by simulation.

[0011] The present disclosure will be described in detail below. As described above, an important role of the sealing member in a battery using a non-aqueous electrolyte solution is to suppress the permeation of the electrolyte solution. Furthermore, since the sealing member needs to be highly tightly adhered to the component, it is generally made of an elastic material such as an elastomer. Some of the components of the electrolyte solution permeate through such a sealing member, and the electrolyte solution decreases with long-term use. Since the decrease in the electrolyte solution causes deterioration of battery performance, it is necessary to suppress the permeation of such components in the electrolyte solution. In particular, since secondary batteries are used for long periods of time, suppressing such permeation is an important issue.

[0012] It is known that compressing and mounting the sealing member can suppress the permeation of electrolyte components. However, the details have not been investigated. Furthermore, compressing and mounting the sealing member increases internal strain, which can lead to problems such as cracking and other damage to the sealing member. Therefore, it is important to suppress the permeability of the sealing member while preventing cracking. Even if the material and compression rate used are the same, the likelihood of cracking and damage varies depending on the shape of the sealing member. Therefore, a computer simulation was used to investigate the shape of the sealing member that can withstand the above-mentioned compression rate. Furthermore, based on the obtained results, conditions for the shape of the sealing member that are less likely to crack were obtained. Furthermore, the appropriateness of these conditions was confirmed by actually manufacturing sealing members and measuring their physical properties.

[0013] As described above, the present disclosure has been completed by providing a sealing member having a shape that can reduce the rate of breakage even when the compression ratio of the sealing member is within a specific range and can achieve both a reduction in the amount of electrolyte permeation and physical strength.

[0014] That is, the present disclosure provides a sealing member for a battery using a non-aqueous electrolyte, which is made of an elastic material, has a compressibility R of 50% or more when mounted, and satisfies the following condition: Eb is the breaking elongation of the material constituting the sealing member, and β is the aspect ratio of the cross-sectional dimensions. Eb≧a×β ｂ (a=6.919×R−2.066 b=2.278×R−1.767) This sealing member is characterized by satisfying the following conditions. These will be described in detail below.

[0015] (Battery using the sealing member of the present disclosure) The sealing member of the present disclosure is a sealing member used in a battery using a non-aqueous electrolyte solution. As described above, the sealing member has the characteristic of being able to suppress permeation of the electrolyte solution, and therefore can be used in any battery using a non-aqueous electrolyte solution.

[0016] Specific examples of the battery include lithium ion batteries, lithium batteries, lithium sulfur batteries, sodium ion batteries, nickel-metal hydride batteries, etc. Among these, lithium ion batteries are particularly suitable for use.

[0017] The battery of the present disclosure uses a non-aqueous electrolyte solution, and thus has the effect of suppressing permeation of electrolyte solution components, and therefore, when the sealing member of the present disclosure is used in a battery having such a non-aqueous electrolyte solution, excellent effects are achieved.

[0018] The structure of the electrolyte contained in the battery case will be described. The electrolyte in this embodiment is, for example, LiPF ６ For example, an appropriate amount of LiPF ６ The lithium salts such as the above can be dissolved in a non-aqueous electrolyte such as a mixed solvent of diethyl carbonate and ethylene carbonate to be used as the electrolyte. The battery of this embodiment is constructed by injecting the electrolyte and sealing it.

[0019] Lithium ion batteries are known in various shapes, such as rectangular and cylindrical, and any of these can be used. An example of a rectangular lithium ion battery is shown in FIG. 1. A rectangular lithium ion battery is constructed by mounting battery components in a rectangular parallelepiped housing, and installing electrodes in two through-holes on the top surface of FIG. 1. At this time, the sealing member of the present disclosure is mounted together with the electrodes to prevent permeation and leakage of the nonaqueous electrolyte solution within the housing. Therefore, in this case, two sealing members are used per battery.

[0020] On the other hand, cylindrical lithium-ion batteries use a sealing member when fitting an anode into a through-hole provided in a cylindrical container. In this case, one sealing member is used per battery. However, cylindrical lithium-ion batteries generally contain a small amount of nonaqueous electrolyte. Therefore, even if the absolute permeation amount is small, the rate of deterioration in battery performance is significant. Therefore, it is presumed that a permeability equal to or greater than that of the prismatic lithium-ion battery is required. From the above perspective, when the sealing member of the present disclosure is applied to a cylindrical lithium-ion battery, excellent effects are also achieved.

[0021] (Compression Ratio) In the present disclosure, the sealing member is attached at a compression ratio of 50% or more. Attaching the sealing member at a high compression ratio reduces transmittance. This point was investigated through experiments. In the present disclosure, the compression ratio R is expressed as a ratio obtained by dividing the amount of dimensional change in thickness from before compression to after compression in the compression direction of the sealing member by the thickness dimensional value before compression. When expressed as a percentage (%), the value is multiplied by 100.

[0022] The compression ratio is more preferably 50% or more, even more preferably 52% or more, and even more preferably 54% or more. The compression ratio is more preferably 80% or less, even more preferably 70% or less, and even more preferably 65% ​​or less. There is no particular upper limit to the compression ratio, but imparting a compression ratio above a certain level during the assembly process may cause problems due to deformation of peripheral components constituting the battery, such as the battery lid, and therefore the above range is a preferable value as a range that is practically feasible. The reasons for deriving such numerical ranges are as follows.

[0023] Batteries (especially secondary batteries) are desired to have a durability of 100,000 hours. To achieve this, it is desirable that the amount of electrolyte permeation after 1,000,000 hours be less than 10%. On the other hand, a typical prismatic lithium-ion battery contains approximately 100 g of electrolyte. Therefore, it is necessary to keep the amount of electrolyte permeation after 1,000 hours to less than 0.05 g.

[0024] In order to study the compression ratio required to obtain such a permeation amount, the relationship between the permeation amount of the electrolyte solution and the compression ratio at 60° C. for 1000 hours was clarified through an experiment. The experiment was carried out as follows.

[0025] The device consisted of a container filled with electrolyte, similar to the electrode configuration of a battery, and a lid simulating an electrode that seals the container outlet together with a sealing member. The sealing member was compressed in the thickness direction by the container and lid at a predetermined compression rate, and then maintained in this state for a certain period of time. The container and lid were made of aluminum alloys used in actual batteries, with sufficient rigidity to prevent deformation against the sealing member during testing, and were impermeable to non-aqueous electrolyte. The permeation rate was measured by measuring the change in the total weight of the device over time.

[0026] In the above experiments, a VdF-based fluorine-containing elastomer (polymer composition: VdF / TFE / HFP=50 / 20 / 30 mol %, iodine content: 0.5 mass %) was used as the elastic material. The elastomer used here was obtained by molding a material having the following composition by the following molding method.

[0027] (Composition) 100 parts by mass of the VdF-based fluorine-containing elastomer, 20 parts by mass of MT carbon, 4 parts by mass of triallyl isocyanurate (TAIC), and 1.5 parts by mass of organic peroxide (2,5-dimethyl-2,5-bis(t-butylperoxy)hexane) were kneaded using an open roll to prepare a composition. (Molding method) The composition was placed in a mold, and pressure was applied using a compression molding machine, followed by secondary vulcanization at 170°C for 10 minutes to mold the composition, thereby obtaining a sealing member.

[0028] The produced sealing member was in the shape of a ring having a square cross section, with an outer diameter of the ring of 17.7 mm, T of 1.6 mm, and W of 1.75 mm.

[0029] The results are shown in Figure 2. As shown in Figure 2, experiments have revealed that by setting the compression rate to 50% or more, the amount of electrolyte permeation in 1000 hours can be reduced to 0.05 g or less. On the other hand, as the compression rate increases, the strain also increases, making cracks and breakage more likely to occur. For this reason, it is necessary to design a shape that can reduce the incidence of cracks and breakage even when mounted at a compression rate of 50% or more. Such a shape and the materials that make up the sealing member are described in detail below.

[0030] (Materials Constituting the Sealing Member) The sealing member of the present disclosure is made of an elastic material. That is, the use of an elastic material provides the sealing member with its performance. The elastic material is not particularly limited, and a polymer generally called an elastomer or a crosslinked product thereof can be used. In general, a crosslinked product of an elastomer is more preferable. As the elastic material, a fluorine-containing elastomer or a crosslinked product thereof is most suitable because of its low permeability to electrolyte solution components. The crosslinked product may be an elastomer obtained by internal crosslinking having a crosslinking group, or may be used in combination with a crosslinking agent.

[0031] Examples of the fluorine-containing elastomer include partially fluorinated elastomers and perfluoroelastomers, which are described in detail below.

[0032] (Partially Fluorinated Elastomer) Partially fluorinated elastomers include, for example, tetrafluoroethylene (TFE), vinylidene fluoride (VdF), and fluoropolymers represented by the general formula: CF ２ =CF-Rf ａ (wherein, Rf ａ Ha-CF ３ or -ORf ｂ (Rf ｂ It is preferable that the fluorine-containing elastomer contains a structural unit derived from at least one monomer selected from the group consisting of perfluoroethylenically unsaturated compounds represented by the formula (I) (where I is a perfluoroalkyl group having 1 to 5 carbon atoms) (for example, hexafluoropropylene (HFP), perfluoro(alkyl vinyl ether) (PAVE), etc.). Among these, elastomers containing VdF units or TFE units are preferred.

[0033] More specific examples of partially fluorinated elastomers include VdF-based fluorine-containing elastomers, TFE / propylene (Pr)-based fluorine-containing elastomers, TFE / Pr / VdF-based fluorine-containing elastomers, ethylene (Et) / HFP-based fluorine-containing elastomers, Et / HFP / VdF-based fluorine-containing elastomers, Et / HFP / TFE-based fluorine-containing elastomers, etc. Among these, VdF-based fluorine-containing elastomers, TFE / Pr-based fluorine-containing elastomers and TFE / Pr / VdF-based fluorine-containing elastomers are more preferred in terms of good heat aging resistance and oil resistance.

[0034] The VdF-based fluorine-containing elastomer is a partially fluorinated elastomer having VdF units. In the VdF-based fluorine-containing elastomer, the VdF units preferably account for 20 mol % or more and 90 mol % or less, more preferably 40 mol % or more and 85 mol % or less, still more preferably 45 mol % or more and 80 mol % or less, and particularly preferably 50 mol % or more and 80 mol % or less, of the total number of moles of the VdF units and monomer units derived from other monomers.

[0035] The other monomer in the VdF-based fluorine-containing elastomer is not particularly limited as long as it is a monomer copolymerizable with VdF, and for example, a fluorine-containing monomer can be used.

[0036] Examples of VdF-based fluorine-containing elastomers include VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / CTFE copolymer, VdF / CTFE / TFE copolymer, VdF / PAVE copolymer, VdF / TFE / PAVE copolymer, VdF / HFP / PAVE copolymer, VdF / HFP / TFE / PAVE copolymer, VdF / TFE / Pr copolymer, VdF / Et / HFP copolymer, and VdF / CH ２ =CFCF ３ It is more preferable that the copolymer contains at least one copolymer selected from the group consisting of copolymers of the above-mentioned copolymers. Furthermore, it is more preferable that the copolymer contains at least one monomer selected from the group consisting of TFE, HFP, and PAVE as the other monomer other than VdF.

[0037] Among these, the VdF-based fluorine-containing elastomers include VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / CH ２ =CFCF ３ At least one copolymer selected from the group consisting of a copolymer of VdF / PAVE, a VdF / TFE / PAVE copolymer, a VdF / HFP / PAVE copolymer, and a VdF / HFP / TFE / PAVE copolymer is preferred, and at least one copolymer selected from the group consisting of a VdF / HFP copolymer, a VdF / HFP / TFE copolymer, a VdF / CH ２ =CFCF ３ and VdF / PAVE copolymers.

[0038] The VdF / PAVE copolymer preferably has a VdF / PAVE composition of (65 to 90) / (35 to 10) (mol %). Another preferred embodiment has a VdF / PAVE composition of (50 to 78) / (50 to 22) (mol %).

[0039] The VdF / TFE / PAVE copolymer preferably has a VdF / TFE / PAVE composition of (40-80) / (3-40) / (15-35) (mol %).

[0040] The VdF / HFP / PAVE copolymer preferably has a VdF / HFP / PAVE composition of (65 to 90) / (3 to 25) / (3 to 25) (mol %).

[0041] The VdF / HFP / TFE / PAVE copolymer preferably has a VdF / HFP / TFE / PAVE composition of (40 to 90) / (0 to 25) / (0 to 40) / (3 to 35) (mol %), and more preferably has a VdF / HFP / TFE / PAVE composition of (40 to 80) / (3 to 25) / (3 to 40) / (3 to 25) (mol %).

[0042] VdF / CH ２ =CFCF ３ As a copolymer of VdF / CH ２ =CFCF ３ The unit is (85-20) / (15-80) (mol%), and VdF and CH ２ =CFCF ３The monomer units other than VdF / CH are preferably 0 to 50 mol % of the total monomer units. ２ =CFCF ３ It is more preferable that the molar ratio of the units is (80 to 20) / (20 to 80). ２ =CFCF ３ In one preferred embodiment, the unit composition is (78 to 50) / (22 to 50) (mol %).

[0043] Also, VdF / CH ２ =CFCF ３ As a copolymer of VdF / CH ２ =CFCF ３ The unit is (85 to 50) / (15 to 50) (mol %), and VdF and CH ２ =CFCF ３ It is also preferred that the other monomer units account for 1 to 50 mol % of the total monomer units. ２ =CFCF ３ As other monomers other than the above, preferred are the monomers exemplified as other monomers in the VdF-based fluorine-containing elastomer, such as TFE, HFP, PMVE, perfluoroethyl vinyl ether (PEVE), PPVE, CTFE, trifluoroethylene, hexafluoroisobutene, vinyl fluoride, Et, Pr, alkyl vinyl ether, and monomers that provide a crosslinkable group, and among these, more preferred are PMVE, CTFE, HFP, and TFE.

[0044] The TFE / Pr partially fluorinated elastomer refers to a fluorine-containing copolymer consisting of 45 to 70 mol % of TFE and 55 to 30 mol % of Pr. In addition to these two components, a specific third component may be contained.

[0045] The specific third component may include, for example, fluorine-containing monomers such as fluorine-containing olefins other than TFE (e.g., VdF, HFP, CTFE, perfluoro(butylethylene), etc.), fluorine-containing vinyl ethers (perfluoro(propyl vinyl ether), perfluoro(methyl vinyl ether), etc.); hydrocarbon monomers such as α-olefins (ethylene, 1-butene, etc.), vinyl ethers (ethyl vinyl ether, butyl vinyl ether, hydroxybutyl vinyl ether, etc.), and vinyl esters (vinyl acetate, vinyl benzoate, vinyl crotonate, vinyl methacrylate, etc.); etc. The specific third component may be used alone or in combination of two or more.

[0046] The TFE / Pr partially fluorinated elastomer preferably contains VdF, and among the TFE / Pr partially fluorinated elastomers, an elastomer consisting of TFE, Pr and VdF is called a TFE / Pr / VdF fluorinated elastomer.

[0047] The TFE / Pr / VdF-based fluoroelastomer may further contain the specific third component other than VdF. The specific third component may be one type or a combination of two or more types. The total content of the third components in the TFE / Pr-based partially fluoroelastomer is preferably 35 mol% or less, more preferably 33 mol% or less, and even more preferably 31 mol% or less.

[0048] The Et / HFP copolymer preferably has an Et / HFP composition of (35 to 80) / (65 to 20) (mol %), more preferably (40 to 75) / (60 to 25) (mol %).

[0049] The Et / HFP / TFE copolymer preferably has an Et / HFP / TFE composition of (35 to 75) / (25 to 50) / (0 to 15) (mol %), more preferably (45 to 75) / (25 to 45) / (0 to 10) (mol %).

[0050] The partially fluorinated elastomer is preferably a partially fluorinated elastomer containing a VdF unit, more preferably a VdF / HFP copolymer or a VdF / HFP / TFE copolymer, and particularly preferably one having a VdF / HFP / TFE composition of (32-85) / (10-34) / (0-34) (mol%). The VdF / HFP / TFE composition is more preferably (32-85) / (15-34) / (0-34) (mol%), and even more preferably (47-81) / (17-29) / (0-26) (mol%).

[0051] For example, in the above VdF / HFP copolymer, the VdF / HFP composition is preferably (45 to 85) / (15 to 55) (mol%), more preferably (50 to 83) / (17 to 50) (mol%), still more preferably (55 to 81) / (19 to 45) (mol%), and particularly preferably (60 to 80) / (20 to 40) (mol%).

[0052] In the VdF / HFP / TFE copolymer, the VdF / HFP / TFE composition is preferably (32 to 80) / (10 to 34) / (4 to 34) (mol %).

[0053] The above-mentioned structure is the structure of the main monomer of the partially fluorinated elastomer, and in addition to the main monomer, a monomer that provides a crosslinkable group may be copolymerized. The monomer that provides a crosslinkable group may be any monomer that can introduce an appropriate crosslinkable group into the partially fluorinated elastomer depending on the production method and crosslinking system, and examples thereof include known polymerizable compounds that include a crosslinkable group such as an iodine atom, a bromine atom, a carbon-carbon double bond, a cyano group, a carboxyl group, a hydroxyl group, an amino group, or an ester group.

[0054] Preferred examples of the monomer that provides a crosslinkable group include those represented by the general formula (2): CY １ ２ =CY ２ R ｆ ２ X １ (2) (wherein, Y １ , Y ２ is a fluorine atom, a hydrogen atom, or —CH ３ ;R ｆ ２is a linear or branched fluorine-containing alkylene group in which some or all of the hydrogen atoms have been substituted with fluorine atoms, which may have one or more ether-bonded oxygen atoms and which may have an aromatic ring; X １ is an iodine atom or a bromine atom).

[0055] Specific examples of the monomer that provides a crosslinkable group include those represented by the general formula (3): CY １ ２ =CY ２ R ｆ ３ CHR １ -X １ (3) (wherein, Y １ , Y ２ , X １ is the same as above, and R ｆ ３ is a linear or branched fluorine-containing alkylene group which may have one or more ether-bonded oxygen atoms and in which some or all of the hydrogen atoms have been substituted with fluorine atoms, i.e., a linear or branched fluorine-containing alkylene group in which some or all of the hydrogen atoms have been substituted with fluorine atoms, a linear or branched fluorine-containing oxyalkylene group in which some or all of the hydrogen atoms have been substituted with fluorine atoms, or a linear or branched fluorine-containing polyoxyalkylene group in which some or all of the hydrogen atoms have been substituted with fluorine atoms; R １ is a hydrogen atom or a methyl group), iodine- or bromine-containing monomers represented by the general formulas (4) to (21): CY ４ ２ =CY ４ (CF ２ ) ｎ -X １ (4) (wherein, Y ４ are the same or different and are a hydrogen atom or a fluorine atom, and n is an integer of 1 to 8) CF ２ =CFCF ２ R ｆ ４ -X １ (5) (wherein, R ４ is -(OCF ２ ) ｎ - or - (OCF (CF ３ )) ｎ-, and n is an integer from 0 to 5) CF ２ =CFCF ２ (OCF (CF ３ )CF ２ ) ｍ (OCH ２ CF ２ CF ２ ) ｎ OCH ２ CF ２ -X １ (6) (wherein m is an integer of 0 to 5, and n is an integer of 0 to 5) CF ２ =CFCF ２ (OCH ２ CF ２ CF ２ ) ｍ (OCF (CF ３ )CF ２ ) ｎ OCF (CF ３ )-X １ (7) (wherein m is an integer of 0 to 5, and n is an integer of 0 to 5) CF ２ =CF(OCF ２ CF (CF ３ )) ｍ O (CF ２ ) ｎ -X １ (8) (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8) CF ２ =CF(OCF ２ CF (CF ３ )) ｍ -X １ (9) CF (wherein m is an integer of 1 to 5) ２ = CFOCF ２ (CF (CF ３ ) OCF ２ ) ｎ CF(-X １ )CF ３ (10) CF (wherein n is an integer of 1 to 4) ２ = CFO (CF ２ ) ｎ OCF (CF ３ )-X １ (11) CF (wherein n is an integer of 2 to 5) ２ = CFO (CF ２ ) ｎ -(C ６H ４ )-X １ (12) CF (wherein n is an integer from 1 to 6) ２ =CF(OCF ２ CF (CF ３ )) ｎ OCF ２ CF (CF ３ )-X １ (13) (wherein n is an integer of 1 to 2) CH ２ =CFCF ２ O(CF(CF ３ )CF ２ O) ｎ CF (CF ３ )-X １ (14) (wherein n is an integer of 0 to 5), CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ (CF ２ ) ｎ -X １ (15) (wherein m is an integer of 0 to 5, and n is an integer of 1 to 3) CH ２ =CFCF ２ OCF (CF ３ ) OCF (CF ３ )-X １ (16) CH ２ =CFCF ２ OCH ２ CF ２ -X １ (17) CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ CF ２ CF (CF ３ )-X １ (18) (wherein m is an integer of 0 or more) CF ２ = CFOCF(CF ３ )CF ２ O (CF ２ ) ｎ -X １ (19) (wherein n is an integer of 1 or more) CF ２ = CFOCF ２ OCF ２ CF (CF ３ ) OCF２ -X １ (20) CH ２ =CH-(CF ２ ) ｎ X １ (21) (wherein n is an integer of 2 to 8) (in the general formulas (4) to (21), X １ are the same as above), and the like, which can be used alone or in any combination.

[0056] The iodine- or bromine-containing monomer represented by the general formula (3) includes a monomer represented by the general formula (22):

[0057] (wherein m is an integer of 1 to 5, and n is an integer of 0 to 3), and more specifically,

[0058] Among these, ICH ２ CF ２ CF ２ OCF = CF ２ is preferred.

[0059] More specifically, the iodine- or bromine-containing monomer represented by the general formula (4) is ICF ２ CF ２ CF=CH ２ , I(CF ２ CF ２ ) ２ CF=CH ２ are preferred.

[0060] More specifically, the iodine- or bromine-containing monomer represented by the general formula (8) is I(CF ２ CF ２ ) ２ OCF = CF ２ are preferred.

[0061] More specifically, the iodine- or bromine-containing monomer represented by the general formula (21) is CH ２ = CHCF ２ CF ２ I, I (CF ２ CF ２ ) ２CH=CH ２ are preferred.

[0062] Also, the formula: R ２ R ３ C=CR ４ -Z-CR ５ =CR ６ R ７ (In the formula, R ２ , R ３ , R ４ , R ５ , R ６ and R ７ are the same or different and are both H or an alkyl group having 1 to 5 carbon atoms; Z is a linear or branched alkylene or cycloalkylene group having 1 to 18 carbon atoms, which may contain an oxygen atom and is preferably at least partially fluorinated, or a (per)fluoropolyoxyalkylene group). Bisolefin compounds represented by these are also preferred as monomers that provide crosslinkable groups. In the present disclosure, the term "(per)fluoropolyoxyalkylene group" means a "fluoropolyoxyalkylene group or a perfluoropolyoxyalkylene group."

[0063] Z is preferably a (per)fluoroalkylene group having 4 to 12 carbon atoms, and R ２ , R ３ , R ４ , R ５ , R ６ and R ７ is preferably a hydrogen atom.

[0064] When Z is a (per)fluoropolyoxyalkylene group, the formula: -(Q) ｐ -CF ２ O-(CF ２ CF ２ O) ｍ -(CF ２ O) ｎ -CF ２ -(Q) ｐ- (wherein Q is an alkylene group having 1 to 10 carbon atoms or an oxyalkylene group having 2 to 10 carbon atoms, p is 0 or 1, and m and n are integers such that the m / n ratio is 0.2 to 5 and the molecular weight of the (per)fluoropolyoxyalkylene group is in the range of 500 to 10,000, preferably 1,000 to 4,000). In this formula, Q is preferably -CH ２ OCH ２ - and -CH ２ O (CH ２ CH ２ O) ｓ CH ２ -(s=1 to 3).

[0065] Preferred bisolefins are CH ２ =CH-(CF ２ ) ２ -CH=CH ２ , C.H. ２ =CH-(CF ２ ) ４ -CH=CH ２ , C.H. ２ =CH-(CF ２ ) ６ -CH=CH ２ , Formula: CH ２ = CH-Z １ -CH=CH ２ (In the formula, Z １ Ha-CH ２ OCH ２ -CF ２ O-(CF ２ CF ２ O) ｍ -(CF ２ O) ｎ -CF ２ -CH ２ OCH ２ - (m / n is 0.5, and the molecular weight is preferably 2000).

[0066] Among them, CH ２ =CH-(CF ２ ) ６ -CH=CH ２Preferred is 3,3,4,4,5,5,6,6,7,7,8,8-dodecafluoro-1,9-decadiene represented by the following formula:

[0067] The number average molecular weight Mn of the partially fluorinated elastomer is preferably from 1,000 to 1,000,000, more preferably from 10,000 to 500,000, and particularly preferably from 20,000 to 300,000.

[0068] The partially fluorinated elastomer preferably has a fluorine content of 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more. The upper limit of the fluorine content is preferably 75% by mass or less, and more preferably 73% by mass or less. The fluorine content is １９ F-NMR and １ It is calculated based on measurements such as H-NMR and elemental analysis.

[0069] The partially fluorinated elastomer preferably has a Mooney viscosity at 100°C (ML1+10(100°C)) of 130 or less. The Mooney viscosity is more preferably 110 or less, and even more preferably 90 or less. The Mooney viscosity is more preferably 10 or more, and even more preferably 20 or more. The Mooney viscosity is a value measured in accordance with JIS K 6300-1.2013.

[0070] The partially fluorinated elastomer preferably has a glass transition temperature of -50 to 0°C. The glass transition temperature is more preferably -2°C or lower, and even more preferably -3°C or lower. The glass transition temperature is more preferably -45°C or higher, and even more preferably -40°C or higher. The glass transition temperature may be -10°C or higher, or may be -9°C or higher. Here, the glass transition temperature can be determined from the DSC differential curve in accordance with JIS K6240:2011, using a differential scanning calorimeter (for example, X-DSC7000 manufactured by Hitachi High-Tech Science Corporation) to obtain a DSC curve by heating 10 mg of a sample at a rate of 20°C / min.

[0071] The partially fluorinated elastomer preferably has an iodine content of 0.05 to 1.0% by mass, more preferably 0.08% by mass or more, even more preferably 0.10% by mass or more, and more preferably 0.80% by mass or less, even more preferably 0.60% by mass or less.

[0072] The iodine content can be determined by elemental analysis. ２ SO ３ Mix 5 mg of Na in 20 ml of pure water. ２ CO ３ and K. ２ CO ３ The absorbent solution is prepared by dissolving 30 mg of a 1:1 (mass ratio) mixture of KI and iodine ions in oxygen in a quartz flask, and after leaving it for 30 minutes, the absorbent is measured using a Shimadzu 20A ion chromatograph. For the calibration curve, a KI standard solution containing 0.5 mass ppm of iodine ions and a solution containing 1.0 mass ppm of iodine ions can be used.

[0073] (Perfluoroelastomer) The perfluoroelastomer can be produced by polymerizing a perfluoromonomer as a fluorine-containing monomer.

[0074] Perfluoromonomers include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), CF ２ =CF-ORf １３ (23) (wherein, Rf １３ represents a perfluoroalkyl group having 1 to 8 carbon atoms, ２ = CFOCF ２ ORf １４ (24) (wherein, Rf １４ is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms and containing 1 to 3 oxygen atoms), and ２ = CFO (CF ２ CF (Y １５ ) O) ｍ (CF２ ) ｎ F (25) (wherein, Y １５ represents a fluorine atom or a trifluoromethyl group, m is an integer of 1 to 4, and n is an integer of 1 to 4.

[0075] In the polymerization of the perfluoromonomer, a monomer that provides a crosslinkable group may be polymerized together with the perfluoromonomer.

[0076] The monomers that provide crosslinkable groups include CX ４ ２ =CX ５ Rf １５ X ６ (26) (wherein, X ４ , X ５ are each independently H, F or an alkyl group having 1 to 5 carbon atoms, and Rf １５ is a linear or branched alkylene or oxyalkylene group which may have one or more ether-bonded oxygen atoms and which may have an aromatic ring, and in which some or all of the hydrogen atoms may be substituted with fluorine atoms; X ６ is an iodine atom, a bromine atom, a cyano group, a carboxyl group, an alkoxycarbonyl group, a hydroxyl group, a vinyl group, an azide group, a sulfonyl azide group, a carbonyl azide group, or an alkyne group. The alkyne group may be an ethynyl group.

[0077] Among the monomers that provide crosslinkable groups, CX １６ ２ =CX １６ -Rf １６ CHR １６ X １７ (27) (wherein, X １６ are each independently a hydrogen atom, a fluorine atom, or CH ３ , Rf １６ represents a fluoroalkylene group, a perfluoroalkylene group, a fluoro(poly)oxyalkylene group or a perfluoro(poly)oxyalkylene group, R １６ is a hydrogen atom or CH ３ , X１７ is an iodine atom or a bromine atom), １６ ２ =CX １６ -Rf １７ X １７ (28) (wherein, X １６ are each independently a hydrogen atom, a fluorine atom, or CH ３ , Rf １７ represents a fluoroalkylene group, a perfluoroalkylene group, a fluoro(poly)oxyalkylene group or a perfluoro(poly)oxyalkylene group, X １７ is an iodine atom or a bromine atom), ２ = CFO (CF ２ CF (CF ３ ) O) ｍ (CF ２ ) ｎ -X １８ (29) (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, X １８ represents a cyano group, an azide group, a sulfonyl azide group, a carbonyl azide group, a carboxyl group, an alkoxycarbonyl group, an alkyne group, an iodine atom, a bromine atom, or a CH ２ I), a monomer represented by CH ２ =CFCF ２ O(CF(CF ３ )CF ２ O) ｍ (CF (CF ３ )) ｎ -X １９ (30) (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, X １９ represents a cyano group, a carboxyl group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or CH ２ OH), and ２０ ２ =CR ２０ -Z ２０ -CR ２０ =CR ２０ ２ (31) (wherein, R ２０ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. ２０represents a linear or branched alkylene group having 1 to 18 carbon atoms, a cycloalkylene group having 3 to 18 carbon atoms, an at least partially fluorinated alkylene group or oxyalkylene group having 1 to 10 carbon atoms, which may have an oxygen atom, or -(Q) ｐ -CF ２ O-(CF ２ CF ２ O) ｍ (CF ２ O) ｎ -CF ２ -(Q) ｐ - (wherein Q is an alkylene group or an oxyalkylene group, p is 0 or 1, and m / n is 0.2 to 5), and is a (per)fluoropolyoxyalkylene group having a molecular weight of 500 to 10,000.

[0078] X １６ is preferably a fluorine atom. １６ and Rf １７ is preferably a perfluoroalkylene group having 1 to 5 carbon atoms. １６ is preferably a hydrogen atom. １８ represents a cyano group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CH ２ Preferably, X is I. １９ represents a cyano group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or CH ２ It is preferably OH.

[0079] Examples of the monomer that provides a crosslinkable group include CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ C.N., C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ COOH, CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２CH ２ I, CF ２ = CFOCF ２ CF ２ CH ２ I, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) CN, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COOH, CH ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) CH ２ OH, CH ２ = CHCF ２ CF ２ I, CH ２ =CH(CF ２ ) ２ CH=CH ２ , C.H. ２ =CH(CF ２ ) ６ CH=CH ２ , and CF ２ = CFO (CF ２ ) ５ CN, and CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CN and CF ２ = CFOCF ２ CF ２ CH ２ It is more preferable that the compound is at least one selected from the group consisting of I.

[0080] The perfluoroelastomer is preferably at least one selected from the group consisting of perfluoroelastomers containing TFE units, such as TFE / monomer copolymers represented by general formula (23), (24) or (25), and TFE / monomer represented by general formula (23), (24) or (25) / monomer copolymers that provide crosslinkable groups.

[0081] In the case of a TFE / perfluoro(methyl vinyl ether) (PMVE) copolymer, the composition is preferably 45 to 90 / 10 to 55 (mol %), more preferably 55 to 80 / 20 to 45, and even more preferably 55 to 70 / 30 to 45.

[0082] In the case of a copolymer of TFE / PMVE / a monomer that provides a crosslinkable group, the ratio is preferably 45 to 89.9 / 10 to 54.9 / 0.01 to 4 (mol %), more preferably 55 to 77.9 / 20 to 49.9 / 0.1 to 3.5, and even more preferably 55 to 69.8 / 30 to 44.8 / 0.2 to 3.

[0083] In the case of TFE / monomer copolymers having 4 to 12 carbon atoms and represented by general formula (23), (24) or (25), the ratio is preferably 50 to 90 / 10 to 50 (mol %), more preferably 60 to 88 / 12 to 40, and even more preferably 65 to 85 / 15 to 35.

[0084] In the case of a copolymer of TFE / monomer having 4 to 12 carbon atoms represented by general formula (23), (24), or (25) / monomer that provides a crosslinkable group, the ratio is preferably 50 to 89.9 / 10 to 49.9 / 0.01 to 4 (mol %), more preferably 60 to 87.9 / 12 to 39.9 / 0.1 to 3.5, and even more preferably 65 to 84.8 / 15 to 34.8 / 0.2 to 3. Outside these composition ranges, the properties of a rubbery elastic body are lost and tend to become more like those of a resin.

[0085] The perfluoroelastomer is preferably at least one selected from the group consisting of TFE / monomer represented by general formula (25) / monomer copolymer providing a crosslinkable group, TFE / monomer copolymer represented by general formula (25), TFE / monomer copolymer represented by general formula (23), and TFE / monomer represented by general formula (23) / monomer copolymer providing a crosslinkable group.

[0086] Examples of the perfluoroelastomer include those described in International Publication No. 97 / 24381, Japanese Patent Publication No. 61-57324, Japanese Patent Publication No. 4-81608, and Japanese Patent Publication No. 5-13961.

[0087] The perfluoroelastomer preferably has a glass transition temperature of −70° C. or higher, more preferably −60° C. or higher, and even more preferably −50° C. or higher, from the viewpoint of excellent resistance to compression set at high temperatures. Furthermore, from the viewpoint of good cold resistance, the glass transition temperature is preferably 5° C. or lower, more preferably 0° C. or lower, and even more preferably −3° C. or lower.

[0088] The glass transition temperature can be determined by obtaining a DSC curve using a differential scanning calorimeter (DSC822e, manufactured by Mettler Toledo) by heating 10 mg of a sample at a rate of 10°C / min, and by determining the temperature as the midpoint between two intersections of an extension of the baseline of the DSC curve before and after the second-order transition and a tangent to the inflection point of the DSC curve.

[0089] In terms of good heat resistance, the perfluoroelastomer preferably has a Mooney viscosity ML(1+20) at 170°C of 30 or more, more preferably 40 or more, and even more preferably 50 or more. In terms of good processability, the Mooney viscosity ML(1+20) is preferably 150 or less, more preferably 120 or less, and even more preferably 110 or less.

[0090] In terms of good heat resistance, the perfluoroelastomer preferably has a Mooney viscosity ML(1+20) at 140°C of 30 or more, more preferably 40 or more, and even more preferably 50 or more. In terms of good processability, the Mooney viscosity ML(1+20) is preferably 180 or less, more preferably 150 or less, and even more preferably 110 or less.

[0091] In terms of good heat resistance, the perfluoroelastomer preferably has a Mooney viscosity ML(1+10) at 100°C of 10 or more, more preferably 20 or more, and even more preferably 30 or more. In terms of good processability, the Mooney viscosity ML(1+10) is preferably 120 or less, more preferably 100 or less, and even more preferably 80 or less.

[0092] The Mooney viscosity can be measured using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES at 170°C, 140°C, or 100°C in accordance with JIS K6300.

[0093] The fluorine-containing elastomer obtained by the production method of the present disclosure can be crosslinked by adding a crosslinking agent. The type and amount of the crosslinking agent are not particularly limited, and any known ranges can be used.

[0094] The method for obtaining the fluorine-containing elastomer composition is not particularly limited as long as it can uniformly mix the fluorine-containing elastomer and the crosslinking agent, for example, by kneading powder obtained by coagulating the fluorine-containing elastomer alone with other additives and compounding ingredients as required in a kneader such as an open roll mixer.

[0095] When the fluorine-containing elastomer is an uncrosslinked elastomer and is crosslinked by using a crosslinking agent in combination, the crosslinking system may be, for example, a peroxide crosslinking system, a polyol crosslinking system, a polyamine crosslinking system, etc., and is preferably at least one selected from the group consisting of a peroxide crosslinking system and a polyol crosslinking system. From the viewpoint of chemical resistance, a peroxide crosslinking system is preferred, and from the viewpoint of heat resistance, a polyol crosslinking system is preferred.

[0096] Therefore, the crosslinking agent is preferably at least one crosslinking agent selected from the group consisting of polyol crosslinking agents and peroxide crosslinking agents, and more preferably a peroxide crosslinking agent.

[0097] The amount of the crosslinking agent to be added may be appropriately selected depending on the type of crosslinking agent, etc., but is preferably 0.2 to 5.0 parts by mass, more preferably 0.3 to 3.0 parts by mass, per 100 parts by mass of the fluorine-containing elastomer composition.

[0098] Peroxide crosslinking can be carried out by using a peroxide-crosslinkable uncrosslinked elastomer as the fluorine-containing elastomer and an organic peroxide as the crosslinking agent.

[0099] The peroxide-crosslinkable uncrosslinked elastomer is not particularly limited as long as it has a peroxide-crosslinkable moiety. The peroxide-crosslinkable moiety is not particularly limited, and examples thereof include a moiety having an iodine atom and a moiety having a bromine atom.

[0100] The organic peroxide may be any organic peroxide that can easily generate peroxy radicals in the presence of heat or a redox system, and examples thereof include 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3.

[0101] The amount of the organic peroxide to be blended is preferably 0.1 to 15 parts by mass, more preferably 0.3 to 5 parts by mass, per 100 parts by mass of the fluorine-containing elastomer.

[0102] When the crosslinking agent is an organic peroxide, the fluorine-containing elastomer composition preferably further contains a crosslinking aid, such as triallyl cyanurate or triallyl isocyanurate (TAIC).

[0103] The amount of the crosslinking aid to be blended is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 7.0 parts by mass, and even more preferably 0.1 to 5.0 parts by mass, per 100 parts by mass of the fluorine-containing elastomer.

[0104] The polyol crosslinking can be carried out by using a polyol-crosslinkable uncrosslinked elastomer as the fluorine-containing elastomer and a polyhydroxy compound as the crosslinking agent.

[0105] The polyol-crosslinkable uncrosslinked elastomer is not particularly limited as long as it has a polyol-crosslinkable moiety. The polyol-crosslinkable moiety is not particularly limited, and examples thereof include moieties having vinylidene fluoride (VdF) units. Methods for introducing the crosslinkable moiety include copolymerizing a monomer that provides a crosslinkable moiety during polymerization of the uncrosslinked elastomer.

[0106] As the polyhydroxy compound, a polyhydroxy aromatic compound is preferably used because of its excellent heat resistance.

[0107] The elastic material may be blended with various additives that are typically blended into elastomers, such as fillers, processing aids, plasticizers, colorants, stabilizers, adhesion aids, mold release agents, electrical conductivity imparting agents, thermal conductivity imparting agents, surface non-tackifying agents, flexibility imparting agents, heat resistance improving agents, and flame retardants, as needed, and these additives may be used within a range that does not impair the effects of the present disclosure.

[0108] A sealing member can be obtained from the elastic material. The sealing member can be obtained by molding and crosslinking the elastic material. The fluorine-containing elastomer composition can be molded by a conventionally known method. The molding and crosslinking methods and conditions may be within the range of known methods and conditions for the molding and crosslinking employed. The order of molding and crosslinking is not limited, and molding may be followed by crosslinking, crosslinking may be followed by molding, or molding and crosslinking may be carried out simultaneously.

[0109] Examples of molding methods include, but are not limited to, pressure molding using a mold or injection molding. Crosslinking methods that can be used include steam crosslinking, conventional methods in which a crosslinking reaction is initiated by heating, and radiation crosslinking, with crosslinking by heating being preferred. Specific crosslinking conditions that are not limited to these are typically a temperature range of 140 to 250°C and a crosslinking time of 1 minute to 24 hours, and can be determined appropriately depending on the type of crosslinking agent used.

[0110] (Elongation at break) In the sealing member of the present disclosure, the elongation at break of the material constituting the sealing member is defined as Eb. The elongation at break can be measured in accordance with JIS K6251 using a dumbbell-shaped No. 5 test piece with a thickness of 2 mm, and is expressed as the elongation at break when the test piece is broken by tension, expressed as a ratio to the test length before the test.

[0111] The strain that occurs when a sealing member is compressed and installed depends greatly on the shape of the sealing member. Meanwhile, the susceptibility of a sealing member to breakage is related to the breaking elongation of the material that constitutes the sealing member. That is, if a strain exceeding the breaking elongation is applied to the sealing member, it will cause cracking. To achieve the objective of the present disclosure of preventing the sealing member from breaking, it is important to design the shape so that the material is not subjected to a strain exceeding the breaking elongation. From this perspective, the present disclosure calculates the maximum strain when a sealing member of a specific shape is compressed, and calculates the shape of the sealing member so that this maximum strain is in a range smaller than the above-mentioned Eb.

[0112] Since the measurement results of breaking elongation have a certain degree of variability, the breaking elongation of 10 samples is measured, and the breaking elongation is taken as the average value excluding the maximum and minimum values. As a result of measurement by this method, it is preferable that the breaking elongation of the fluorine-containing elastomer is 200% to 300%, with a standard deviation σ of 20 or less.

[0113] (Sealing Member) The sealing member of the present disclosure is preferably an annular shape having a rectangular cross section as shown in FIG. 3. It is preferable that such an annular shape be sandwiched between the lid and the battery container as shown in FIG. 5. Such a sealing member is compressed between the lid and the battery container, resulting in a high compression ratio. Here, "rectangular cross section" means that the cross-sectional shape of the annular sealing member when cut outward from the center of the circle is square or rectangular.

[0114] The cross-sectional shape of the annular sealing member is shown in Figure 4. If the axial distance of the annular ring in this cross-section is W and the circumferential distance is T, the cross-sectional aspect ratio can be defined as β = T / W. This aspect ratio is a value measured in an uncompressed state and is a value obtained by measurement using a conventional method.

[0115] The outer diameter of the annular sealing member is preferably 10 mm to 50 mm. This range is consistent with the size of current common battery shapes. W is preferably 0.5 to 2.5 mm. To function as a sealing member, a width within this range is desirable. The lower limit of W is preferably 0.4 mm, more preferably 0.45 mm, and even more preferably 0.5 mm. The upper limit of W is preferably 3.5 mm, more preferably 3.0 mm, and even more preferably 2.5 mm. T is preferably 0.5 to 2.5 mm. To function as a sealing member, a thickness within this range is desirable. The lower limit of T is preferably 0.4 mm, more preferably 0.45 mm, and even more preferably 0.5 mm. The upper limit of T is preferably 3.5 mm, more preferably 3.0 mm, and even more preferably 2.5 mm.

[0116] (Calculation of Maximum Strain by Simulation Analysis) The strain when a certain compression rate is applied to a sealing member having the above-described shape was calculated for sealing members having various β. The simulation was performed using ANSYS V19.0 under the following conditions: similar to the component configuration of the electrode portion in a battery, member A is arranged below the sealing member in the axial direction and is simulating an electrode having a surface that extends in the radial direction of the sealing member, and member B is arranged above the sealing member in the axial direction and is simulating a lid having a surface that extends in the radial direction of the sealing member; member A is fixed, and member B is moved downward while being maintained horizontally, thereby pressing the sealing member arranged between them.

[0117] The material of the sealing member used in the simulation was a VdF-based fluorine-containing elastomer, and its specific physical properties, as specified in JIS K6251, were a tensile stress of 5.0 MPa at 100% elongation and a breaking elongation of 210%. A tensile test was also conducted in accordance with JIS K6251, and the resulting tensile stress and elongation test data were precisely curve-fitted to a hyperelastic model prepared in ANSYS to calculate material parameters. The hyperelastic model to which the calculated material parameters were applied was then set as the material properties of the sealing member. Members A and B were assumed to be rigid planes, with sufficient rigidity relative to the sealing member, which is an elastomer material. It is known that the strain value generated by compressing the sealing member, described below, does not depend on the rigidity of the elastomer, i.e., in this case, the shape and size of the stress-strain diagram. In other words, in this sense, the physical properties of the sealing member material may be those of a fluorine-containing elastomer other than those mentioned above, and further, any elastomer material other than a fluorine-containing elastomer may be used. Under the above-mentioned simulation conditions, sealing members having various β were compressed at predetermined compression rates, and the maximum strain was determined for each compression rate. Here, the maximum strain was measured by measuring the maximum value of the principal strain generated on the surface of the sealing member under a predetermined compression state, and converting this principal strain into a nominal strain equivalent to uniaxial tension.

[0118] Fig. 8 shows the relationship between the maximum strain on the surface of the sealing member and the compression ratio for various values ​​of β. Fig. 9 shows the relationship between the maximum strain on the surface of the sealing member and the cross-sectional aspect ratio β for various values ​​of compression ratio R. From these simulation results, the maximum strain ε is calculated as follows: ε = a × β ｂ It was revealed that the following relationships exist: (a=6.919×R−2.066 b=2.278×R−1.767)

[0119] As described above, the sealing member breaks when a maximum strain higher than the breaking elongation of the material occurs. Therefore, by designing the shape of the sealing member so as to satisfy the relationship Eb≧ε, breaking is less likely to occur. From the above, Eb≧a×β ｂ It has been revealed that by satisfying the following relational expressions: (a=6.919×R−2.066 b=2.278×R−1.767), the sealing member is less likely to break or crack.

[0120] In addition, in order to make the wire less susceptible to breakage, the following condition is satisfied: Eb-σ ≧a×β ｂ (σ is the standard deviation of Eb) As described above, since the breaking elongation has a certain degree of variability, measurements are performed on multiple samples to obtain the value of breaking elongation, as described above. Since multiple data are obtained when obtaining such an average value, the standard deviation σ can be calculated from this. If the calculated strain is smaller than Eb-σ, the rate of sealing members that crack can be reduced. If it is smaller than Eb-2σ, the rate of cracks can be reduced even further.

[0121] In addition, in order to make the wire less susceptible to breakage, the following condition is satisfied: 0.9×Eb≧a×β ｂ The following relation may be satisfied.

[0122] For example, when a material made of a VdF-based fluorine-containing elastomer, which is the partially fluorinated elastomer, is used, Eb=200%, and therefore, 3.0≧a×β ｂ(a=6.919×R−2.066 b=2.278×R−1.767) Furthermore, it is necessary to satisfy the following relational expressions: 2.5≧a×β ｂ (a and b are the same as in the above formula) It is more preferable that the following relational expression is satisfied: 2.0≧a×β ｂ It is more preferable that the following relational expression is satisfied: (a and b are the same as in the above formula).

[0123] In this disclosure, ε = a × β ｂ The relational expression (a = 6.919 × R - 2.066 b = 2.278 × R - 1.767) is a general expression for calculating the maximum strain ε based on the compression ratio of the sealing member and the shape of the sealing member. This is clear from the simulation conditions described above. Therefore, this general expression holds regardless of the type of material used. Although the ε value and compression ratio vary depending on the material used and the method of use, the above general expression is a widely generalized mathematical expression. Therefore, the present disclosure can be applied by appropriately using the compression ratio R and the maximum strain ε of the material, regardless of the type of elastomer.

[0124] The present disclosure will be described below based on examples. However, the present disclosure is not limited to the examples described below. The following examples were carried out by manufacturing a sealing member that reflected the above-mentioned simulation results and evaluating its physical properties.

[0125] The validity of the above-mentioned calculation formula was confirmed by producing sealing members of various shapes using a VdF-based fluorine-containing elastomer (polymer composition VdF / TFE / HFP = 50 / 20 / 30 mol%, iodine content 0.5 mass%). The elastomer used here was obtained by molding an elastomer having the following composition using the following molding method. The elastomer had a breaking elongation of 210% according to JIS K6251. Furthermore, the standard deviation of the breaking elongation was 20%.

[0126] (Composition) 100 parts by mass of the VdF-based fluorine-containing elastomer, 20 parts by mass of MT carbon, 4 parts by mass of triallyl isocyanurate (TAIC), and 1.5 parts by mass of organic peroxide (2,5-dimethyl-2,5-bis(t-butylperoxy)hexane) were kneaded using an open roll to prepare a composition. (Molding method) The composition was placed in a mold, and pressure was applied using a compression molding machine, followed by secondary vulcanization at 170°C for 10 minutes to mold the composition, thereby obtaining a sealing member.

[0127] The manufactured sealing members had the values ​​of T and W shown in the table below. By applying these values ​​to the formula of the present disclosure and assuming R=62.5%, the maximum strain ε calculated is shown in Table 1.

[0128]

[0129] These sealing members were mounted in lithium ion batteries at a compression rate of 62.5% based on the following evaluation method. After mounting, the batteries were removed and the presence or absence of cracks was judged based on the criteria of ◯ for those without cracks or fractures on the surface of the sealing member and × for those with cracks or fractures. The test was carried out on 10 samples, and the results are shown in Table 2.

[0130]

[0131] Furthermore, the maximum strain ε calculated by applying the formula of the present disclosure to the manufactured sealing member when the compression ratio R was 52.5% is shown in Table 3.

[0132]

[0133] These sealing members were mounted in lithium ion batteries at a compression rate of 52.5% based on the following evaluation method. After mounting, the batteries were removed and the presence or absence of cracks was judged based on the criteria of ◯ for those without cracks or fissures on the surface of the sealing member and × for those with cracks or fissures. The test was carried out on 10 samples, and the results are shown in Table 4.

[0134]

[0135] In addition, considering the results of the above examples, even if an elastomer other than that used in the examples is used, a sealing member having a suitable shape based on the calculation formula of the present disclosure can be obtained by a theory based on a similar method.

[0136] The sealing member of the present disclosure can be used in batteries that use non-aqueous electrolytes.

[0137] REFERENCE SIGNS LIST 1 Battery container / lid 2 Electrode terminal 3 Sealing member 4 Non-aqueous electrolyte 5 Member A 6 Member B (before compression) 6' Member B (after compression) 7 Sealing member (before compression) 7' Sealing member (after compression)

Claims

1. A sealing member for a battery using a non-aqueous electrolyte, wherein the material constituting the sealing member is made of an elastic material, the compression ratio R during mounting is 50% or more, and when the elongation at break according to JIS K6251 of the material constituting the sealing member is Eb and the cross-sectional aspect ratio is β, Eb ≧ a × β ｂ (a = 6.919 × R - 2.066 b = 2.278 × R - 1.767), and the sealing member is characterized by satisfying the above conditions.

2. The sealing member according to claim 1, wherein the sealing member has an annular shape with a square cross-section.

3. The sealing member according to claim 1 or 2, wherein T satisfies 0.4 mm ≤ T ≤ 3.5 mm.

4. The sealing member according to claim 1 or 2, wherein W satisfies 0.4 mm ≤ W ≤ 3.5 mm.

5. The sealing member according to claim 1, 2, 3, or 4, wherein the compression ratio is 52% or more.

6. The sealing member according to any one of claims 1 to 4, wherein the elastic material is a fluorine-containing elastomer.

7. The sealing member according to any one of claims 1 to 5, wherein the elastic material is an elastomer containing vinylidene fluoride units.

8. 3.0 ≥ a × β ｂ The sealing member according to claim 6, satisfying (a = 6.919 × R - 2.066, b = 2.278 × R - 1.767).

9. The battery using a non-aqueous electrolyte is a lithium-ion battery according to any one of claims 1 to 7.

10. The battery is a prismatic battery according to any one of claims 1 to 8.

11. A battery using a non-aqueous electrolyte, characterized by having the sealing member according to any one of claims 1 to 9.

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