Gasket for electrochemical device, and electrochemical device

Abstract

Provided are a gasket for an electrochemical device, said gasket having excellent low water vapor permeability, and an electrochemical device using the same. The gasket for an electrochemical device contains polybutylene terephthalate and has a compression rate of 5% or more at the time of mounting.

Description

Gasket for electrochemical device and electrochemical device

[0001] The present disclosure relates to a gasket for an electrochemical device and an electrochemical device.

[0002] It is known that resins such as perfluoroalkoxyalkane (PFA) are used as sealing members (gaskets) for electrochemical devices such as lithium ion secondary batteries (see, for example, Patent Documents 1 to 4).

[0003] Japanese Patent Application Laid-Open No. 2017-174732 International Publication No. 2020 / 066050 International Publication No. 2014 / 049645 Japanese Patent Application Laid-Open No. 2021-141045

[0004] An object of the present disclosure is to provide a gasket for an electrochemical device that has excellent low water vapor permeability, and an electrochemical device using the same.

[0005] The present disclosure (1) is a gasket for an electrochemical device that contains polybutylene terephthalate and has a compressibility of 5% or more when installed.

[0006] The present disclosure (2) is the gasket according to the present disclosure (1), in which the compression ratio is less than the rupture compression ratio.

[0007] The present disclosure (3) is the gasket according to the present disclosure (1) or (2), which has a water vapor permeability coefficient of less than 0.010 g / 1000 hr.

[0008] The present disclosure (4) is a gasket in any combination with any of the present disclosures (1) to (3) in contact with an electrolyte.

[0009] The present disclosure (5) is an electrochemical device including a gasket in any combination with any of the present disclosures (1) to (4).

[0010] The present disclosure (6) is a gasket for an electrochemical device that contains a polymer and has a compressibility of 20% or more and 75% or less when installed.

[0011] The present disclosure (7) is the gasket according to the present disclosure (6), wherein the compression ratio is less than the rupture compression ratio.

[0012] The present disclosure (8) is the gasket according to the present disclosure (6) or (7), which has a water vapor permeability coefficient of less than 0.010 g / 1000 hr.

[0013] The present disclosure (9) is a gasket in any combination with any of the present disclosures (6) to (8), which contains a polymer having a fluorine substitution rate of 95% or less.

[0014] The present disclosure (10) is a gasket in any combination with any of the present disclosures (6) to (9), which contains at least one polymer selected from the group consisting of polyethylene, polypropylene, polybutylene terephthalate, and polyphenylene sulfide.

[0015] The present disclosure (11) is a gasket in any combination with any of the present disclosures (6) to (10) in contact with an electrolyte.

[0016] The present disclosure (12) is an electrochemical device comprising a gasket in any combination with any of the present disclosures (6) to (11).

[0017] According to the present disclosure, it is possible to provide a gasket for an electrochemical device that has excellent low water vapor permeability, and an electrochemical device using the same.

[0018] 1 is a schematic cross-sectional view showing the configuration of a portion of an electrochemical device including a gasket. 2 is a schematic cross-sectional view of a permeation test jig used in a water vapor permeation test.

[0019] It has been discovered that even when a material that has previously been considered to have poor water vapor permeability is used for a gasket, the water vapor permeability can be reduced by setting the compression ratio when attached to an electrochemical device within a specific range.

[0020] The present disclosure will be specifically described below.

[0021] The present disclosure provides a gasket for an electrochemical device (hereinafter also referred to as the gasket (1) of the present disclosure) that contains polybutylene terephthalate (PBT) and has a compression rate of 5% or more when installed. The gasket (1) of the present disclosure has the above-described configuration, and thus has excellent low water vapor permeability.

[0022] In this specification, unless otherwise specified, the gasket (1) of the present disclosure and the gasket (2) of the present disclosure described below will be collectively referred to as the "gasket of the present disclosure."

[0023] The gasket (1) of the present disclosure has a compression ratio of 5% or more when installed. To further improve the low water vapor permeability, the compression ratio is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, even more preferably 25% or more, even more preferably 30% or more, and particularly preferably 40% or more. The compression ratio is preferably less than 75%, more preferably 70% or less, even more preferably 65% ​​or less, and even more preferably less than 65%. The compression ratio can be calculated using the following formula: Compression ratio (%) = [(thickness of gasket before compression) - (thickness of gasket in compressed state)] / (thickness of gasket before compression) x 100. When determining the compression ratio of an installed gasket, the cross section of the gasket may be observed in an X-ray photograph while it is installed and compressed. The thickness of the gasket at the point where the distance between the surfaces of the compressed portion due to installation is shortest may be taken as the thickness of the gasket in the compressed state, and the thickness of the gasket at the point where the thickness of the uncompressed portion is the thickest may be taken as the thickness of the gasket before compression. Alternatively, the thickness of the gasket after removing it from the mounted state and subjecting it to a heat treatment at 150° C. for 24 hours may be taken as the thickness of the gasket before it is compressed.

[0024] The gasket (1) of the present disclosure preferably has a compression ratio less than the rupture compression ratio, i.e., the gasket does not rupture at the compression ratio when mounted. The rupture compression ratio is 17.7±0.1 mm for the outer diameter, 14.2±0.1 mm for the inner diameter, and 1.6±0.05 mm for the thickness (L). ０ ) A compression test is carried out in accordance with JIS K7181:2011 using a circular gasket having a square cross section, and the compression ratio at the time of gasket rupture is determined.

[0025] In order to further improve the low water vapor permeability, the gasket (1) of the present disclosure preferably has a water vapor permeability coefficient of 0.015 g / 1000 hr or less, more preferably less than 0.010 g / 1000 hr, even more preferably 0.009 g / 1000 hr or less, even more preferably 0.008 g / 1000 hr or less, even more preferably 0.007 g / 1000 hr or less, even more preferably 0.006 g / 1000 hr or less, particularly preferably 0.005 g / 1000 hr or less, and may be 0.0001 g / 1000 hr or more. The water vapor permeability coefficient is determined by measuring the mass of water that permeates a circular gasket having a rectangular cross section with an outer diameter of 17.7 mm, an inner diameter of 14.3 mm, and a thickness of 1.6 mmt, under the above-mentioned compression ratio when mounted, at 80°C for 1000 hours.

[0026] The gasket (1) of the present disclosure may contain components other than PBT, but preferably consists essentially of PBT. This allows the effects of PBT to be significantly exhibited. "Consisting essentially of PBT" means that the PBT content is 95.0% by mass or more relative to the gasket. The PBT content is preferably 98.0% by mass or more relative to the gasket, more preferably 99.0% by mass or more, even more preferably 99.5% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more. It is also preferable that the gasket (1) of the present disclosure consists essentially of PBT.

[0027] The present disclosure also provides a gasket for an electrochemical device (hereinafter also referred to as gasket (2) of the present disclosure) that contains a polymer and has a compressibility of 20% or more and 75% or less when installed.

[0028] The gasket (2) of the present disclosure has an excellent low water vapor permeability due to its compression ratio when installed of 20% or more and 75% or less. The compression ratio is preferably 25% or more, more preferably 30% or more, and even more preferably 40% or more, in order to further improve the low water vapor permeability. It is also preferable that the compression ratio is less than 75%, even more preferably 70% or less, even more preferably 65% ​​or less, and particularly preferably less than 65%. The compression ratio can be calculated using the following formula: Compression ratio (%) = [(thickness of gasket before compression) - (thickness of gasket in compressed state)] / (thickness of gasket before compression) x 100. When determining the compression ratio of an installed gasket, the cross section of the gasket may be observed in an X-ray photograph while it is installed and compressed. The thickness of the gasket at the point where the distance between the surfaces of the compressed portion due to installation is shortest may be taken as the thickness of the gasket in the compressed state, and the thickness of the gasket at the point where the thickness of the uncompressed portion is the thickest may be taken as the thickness of the gasket before compression. Alternatively, the thickness of the gasket after removing it from the mounted state and subjecting it to a heat treatment at 150° C. for 24 hours may be taken as the thickness of the gasket before it is compressed.

[0029] The gasket (2) of the present disclosure preferably has a compression ratio less than the rupture compression ratio, i.e., the gasket does not rupture at the compression ratio when mounted. The rupture compression ratio is 17.7±0.1 mm for the outer diameter, 14.2±0.1 mm for the inner diameter, and 1.6±0.05 mm for the thickness (L). ０ ) A compression test is carried out in accordance with JIS K7181:2011 using a circular gasket having a square cross section, and the compression ratio at the time of gasket rupture is determined.

[0030] In order to further improve the low water vapor permeability of the gasket (2) of the present disclosure, the water vapor permeability coefficient is preferably less than 0.010 g / 1000 hr, more preferably 0.009 g / 1000 hr or less, even more preferably 0.008 g / 1000 hr or less, even more preferably 0.007 g / 1000 hr or less, even more preferably 0.006 g / 1000 hr or less, particularly preferably 0.005 g / 1000 hr or less, and may be 0.0001 g / 1000 hr or more. The water vapor permeability coefficient is determined by measuring the mass of water that permeates a circular gasket having a rectangular cross section with an outer diameter Φ of 17.7 mm, an inner diameter Φ of 14.3 mm, and a thickness of 1.6 mmt under the above-mentioned conditions of compression ratio when mounted at 80°C for 1000 hours.

[0031] The gasket (2) of the present disclosure contains a polymer, and preferably contains a polymer with a fluorine substitution rate of 95% or less. Polymers with a low fluorine substitution rate have advantages such as low processing costs, ease of processing, and a light specific gravity, but may have poor barrier properties against water vapor, etc. The gasket of the present disclosure has excellent low water vapor permeability even when it contains a polymer with a low fluorine substitution rate. The fluorine substitution rate of a polymer can be calculated using the following formula: Fluorine substitution rate (%) = (number of fluorine atoms bonded to carbon atoms constituting the polymer) / ((number of hydrogen atoms bonded to carbon atoms constituting the polymer) + (number of fluorine atoms and chlorine atoms bonded to carbon atoms constituting the polymer)) x 100

[0032] The polymer having a fluorine substitution rate of 95% or less includes a fluoropolymer having a fluorine substitution rate of 95% or less and a non-fluorine polymer (fluorine substitution rate 0%), with the non-fluorine polymer being preferred.

[0033] The fluorine substitution rate of the fluoropolymer is more preferably 90% or less, even more preferably 70% or less, and even more preferably 50% or less, and is preferably 10% or more, and more preferably 20% or more.

[0034] Examples of the fluoropolymer include ethylene [Et] / tetrafluoroethylene [TFE] copolymer [ETFE], Et / TFE / hexafluoropropylene [HFP] copolymer [EFEP], polychlorotrifluoroethylene [PCTFE], chlorotrifluoroethylene [CTFE] / TFE copolymer, CTFE / TFE / perfluoro(alkyl vinyl ether) [PAVE] copolymer, Et / CTFE copolymer, polyvinyl fluoride [PVF], polyvinylidene fluoride [PVdF], vinylidene fluoride [VdF] / TFE copolymer, VdF / HFP copolymer, and VdF / TFE / HFP. copolymer, VdF / HFP / (meth)acrylic acid copolymer, VdF / CTFE copolymer, VdF / pentafluoropropylene copolymer, VdF / PAVE / TFE copolymer, and other fluororesins; and fluororubbers such as vinylidene fluoride [VdF]-based fluororubbers, tetrafluoroethylene [TFE] / propylene [Pr]-based fluororubbers, TFE / Pr / VdF-based fluororubbers, ethylene [Et] / hexafluoropropylene [HFP]-based fluororubbers, Et / HFP / VdF-based fluororubbers, Et / HFP / TFE-based fluororubbers, fluorosilicone-based fluororubbers, and fluorophosphazene-based fluororubbers.

[0035] Examples of the non-fluorine-containing polymer include non-fluorine-containing resins such as polyethylene (PE) such as ultra-high molecular weight polyethylene, polypropylene (PP), polybutylene terephthalate (PBT), and polyphenylene sulfide (PPS); non-fluorine-containing rubbers such as nitrile rubber, hydrogenated nitrile rubber, styrene-butadiene rubber (SBR), chloroprene rubber (CR), butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), ethylene-α-olefin rubber, ethylene-α-olefin-non-conjugated diene rubber, chlorinated polyolefin rubber, chlorosulfonated polyolefin rubber, acrylic rubber, ethylene-based acrylic rubber, epichlorohydrin rubber, silicone rubber, butyl rubber (IIR), ethylene-vinyl ester rubber, and ethylene-methacrylate rubber; thermosetting resins such as phenolic resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, silicone resin, polyurethane, and thermosetting polyimide; and crosslinked resins such as crosslinked acrylic resin and crosslinked polyethylene. Among these, non-fluorine resins are preferred, at least one selected from the group consisting of PE, PP, PBT, and PPS is more preferred, and at least one selected from the group consisting of PE, PP, and PBT is even more preferred. In particular, at least one selected from the group consisting of PP and PBT is preferred because of its excellent compression resistance. PE and PP are preferred, and PE is more preferred because of its even better low water vapor permeability.

[0036] The PE is preferably an ultra-high molecular weight PE, which has a weight average molecular weight of 1.0×10 ６ It is preferable that the ratio is 2.0×10 or more. ６ More preferably, it is 7.0 × 10 or more. ７ Preferably, it is 7.0 x 10 or less. ６ The molecular weight of the ultra-high molecular weight PE is measured by gel permeation chromatography (GPC) in terms of polystyrene.

[0037] Examples of commonly available ultra-high molecular weight PE include Tiber UHMW-PE manufactured by Mitsubishi Chemical Advanced Materials Corporation and Hi-Zex Million manufactured by Mitsui Chemicals, Inc.

[0038] The gasket (2) of the present disclosure may contain components other than the polymer, but preferably consists essentially of the polymer. This allows the effects of the polymer to be significantly exhibited. "Consisting essentially of the polymer" means that the content of the polymer is 95.0% by mass or more relative to the gasket. The content of the polymer is preferably 98.0% by mass or more relative to the gasket, more preferably 99.0% by mass or more, even more preferably 99.5% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more. It is also preferable that the gasket (2) of the present disclosure consists essentially of the polymer.

[0039] The gasket of the present disclosure can be produced by molding a raw polymer into a desired shape. The form of the raw polymer is not limited and may be a powder, pellet, dispersion, or the like, but is preferably a powder or pellet.

[0040] It is preferable to select a raw polymer having a compressibility at break greater than the desired compressibility.

[0041] The method for molding the raw polymer is not particularly limited, and known molding methods such as cutting, injection molding, extrusion molding, compression molding, etc. Alternatively, a rubber composition containing a rubber and a crosslinking agent (and a crosslinking aid, if necessary) may be crosslinked and molded by a known method.

[0042] The gasket of the present disclosure is a member used in an electrochemical device to prevent leakage of liquid or gas or intrusion of liquid or gas from the outside.

[0043] The shape of the gasket of the present disclosure is not particularly limited and may be, for example, an annular shape. Furthermore, the gasket of the present disclosure may have a shape such as a circle, an oval, or a rectangle with rounded corners in a plan view, and may have a through-hole in the center.

[0044] A usage mode of a gasket according to an embodiment of the present disclosure will be described with reference to the drawings.

[0045] 1, an electrochemical device 10 (e.g., a sealed prismatic secondary battery) includes an outer can (not shown) and a lid 1. An electric element (not shown), such as a power generator, is housed inside the outer can, and the opening of the outer can is hermetically sealed with the lid 1. An external terminal 2 (positive electrode terminal or negative electrode terminal) is provided on the lid 1, and externally generated electric power is supplied to the electric element via the external terminal 2 for storage, and also for supplying electric power to an external load.

[0046] A gasket 3 for sealing and insulation is provided between the external terminal 2 and the lid 1. The gasket 3 corresponds to the gasket of the present disclosure. An insulating plate 4 is provided on the lid 1 to electrically insulate the external terminal 2 from the lid 1. The external terminal 2 has a terminal head 21 having a rectangular block shape and a cylindrical shaft 22. The shaft 22 protrudes from the bottom surface of the terminal head 21 (the interior side of the electrochemical device).

[0047] As shown in FIG. 1 , the gasket 3 has a cylindrical portion 31 , a flange portion 32 that extends radially from one opening of the cylindrical portion 31 , and a side wall portion 33 that rises from the periphery of the flange portion 32 .

[0048] The cylindrical portion 31 is fitted onto the shaft portion 22 of the external terminal 2, and the inner peripheral surface of the cylindrical portion 31 abuts against the outer peripheral surface of the shaft portion 22. The cylindrical portion 31 is also inserted into the through hole of the lid 1, and the outer peripheral surface of the cylindrical portion 31 abuts against the inner peripheral surface of the through hole of the lid 1.

[0049] The flange portion 32 is sandwiched between the lid 1 and the external terminal 2 , with one contact surface of the flange portion 32 contacting the lower surface of the external terminal 2 and the other contact surface of the flange portion 32 contacting the surface of the lid 1 .

[0050] With the cylindrical portion 31 and flange portion 32 of the gasket 3 in a compressed state, the gasket 3 comes into contact with the external terminal 2 and the lid 1, thereby ensuring the hermeticity of the electrochemical device.

[0051] The gasket of the present disclosure is used in electrochemical devices such as batteries and capacitors. Examples of batteries include secondary batteries such as lithium ion batteries. The capacitor is not particularly limited, but is preferably an electrochemical capacitor. Examples of electrochemical capacitors include electric double layer capacitors, hybrid capacitors, and redox capacitors. Examples of hybrid capacitors include sodium ion capacitors, lithium ion capacitors, and magnesium ion capacitors. Among these, electric double layer capacitors are particularly preferred.

[0052] The gasket of the present disclosure can be suitably used as a gasket for batteries, and can be particularly suitably used as a gasket for secondary batteries such as lithium ion batteries.

[0053] The secondary battery may be a secondary battery using an electrolytic solution or a solid-state secondary battery. In this specification, the solid-state secondary battery may be a secondary battery containing a solid electrolyte, and may be a semi-solid-state secondary battery containing a solid electrolyte and a liquid component as the electrolyte, or an all-solid-state secondary battery containing only a solid electrolyte as the electrolyte.

[0054] The gasket of the present disclosure preferably contacts the electrolyte, i.e., has a contact surface with the electrolyte. Because the gasket of the present disclosure has excellent low water vapor permeability, when used in contact with the electrolyte, it can suppress the intrusion of water into the electrolyte. The electrolyte referred to here includes not only the electrolyte itself provided in the electrochemical device, but also substances derived from the electrolyte, and may be liquid, solid, or gas. The gas includes, for example, volatilized electrolytic solution and gas generated by decomposition of the electrolytic solution during charging and discharging.

[0055] The electrochemical device according to the present disclosure preferably includes a non-aqueous electrolyte. The gasket according to the present disclosure is preferably used in contact with the non-aqueous electrolyte, i.e., has a surface that comes into contact with the non-aqueous electrolyte.

[0056] The non-aqueous electrolyte may be prepared by dissolving a known electrolyte salt in a known organic solvent for dissolving electrolyte salts.

[0057] The organic solvent for dissolving the electrolyte salt is not particularly limited, and one or more of known hydrocarbon solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; and fluorine-based solvents such as fluoroethylene carbonate, fluoroether, and fluorinated carbonate can be used.

[0058] The electrolyte salt is, for example, LiClO ４ , LiAsF ６ , LiBF ４ , LiPF ６ , LiN(SO ２ CF ３ ) ２ , LiN(SO ２ C ２ F ５ ) ２ , LiCl, LiBr, CH ３ SO ３ Li, CF ３ SO ３ Li, cesium carbonate, etc. are listed, and LiPF is particularly preferred due to its good cycle characteristics. ６ , LiBF ４ , LiN(SO ２ CF ３ ) ２ , LiN(SO ２ C ２ F ５ ) ２ Or a combination of these is preferred.

[0059] The concentration of the electrolyte salt is preferably 0.8 mol / L or more, more preferably 1.0 mol / L or more. The upper limit is usually 1.5 mol / L, although it depends on the organic solvent used to dissolve the electrolyte salt.

[0060] The solid electrolyte used in the solid secondary battery may be a sulfide-based solid electrolyte or an oxide-based solid electrolyte. In particular, the sulfide-based solid electrolyte has the advantage of being flexible.

[0061] The sulfide-based solid electrolyte is not particularly limited, and may be Li２ S-@ ２ S ５ 、 ２ S-@ ２ S ３ 、 ２ S-@ ２ S ３ -P ２ S ５ 、 ２ Ψ-SiΨ ２ 、---- ２ Ψ-SiΨ ２ 、---- ２ S-@ ２ S ５ 、---- ２ S-@ ２ O ５ 、---- ３ 2O ４ -P ２ S ５ 、---- ２ Ψ-SiΨ ２ -P ２ S ５ 、 ２ Ψ-SiΨ ２ -L) ４ SiO ４ 、 ２ Ψ-SiΨ ２ -L) ３ 2O ４ 、 ３ PS ４ -L) ４ GeS ４ 、 ３．４ P ０．６ Si ０．４ S ４ 、 ３．２５ P ０．２５ Ge ０．７６ S ４ 、 ４－ｘ Ge １－ｘ P ｘ S ４ (8=0.6~0.8), L- ４＋ｙ Ge １－ｙ G ｙ S ４ (y=0.2~0.3),L-PS&-、L-&.、- ７－ｘ－２ｙ PS ６－ｘ－ｙ C- ｘ(0.8≦x≦1.7, 0<y≦-0.25x+0.5), Li １０ SnP ２ S １２ Any one selected from the above, or a mixture of two or more thereof, can be used.

[0062] The sulfide-based solid electrolyte preferably contains lithium. Sulfide-based solid electrolytes containing lithium are used in solid-state batteries that use lithium ions as a carrier, and are particularly preferred in terms of electrochemical devices having high energy density.

[0063] The oxide-based solid electrolyte is preferably a compound that contains oxygen atoms (O), has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation properties.

[0064] Specific examples of the compound include Li ｘａ La ｙａ TiO ３ [xa=0.3~0.7, ya=0.3~0.7] (LLT), Li ｘｂ La ｙｂ Zr ｚｂ M ｂｂ ｍｂ O ｎｂ (M ｂｂ is at least one element selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn, where xb satisfies 5≦xb≦10, yb satisfies 1≦yb≦4, zb satisfies 1≦zb≦4, mb satisfies 0≦mb≦2, and nb satisfies 5≦nb≦20.), Li ｘｃ B ｙｃ M ｃｃ ｚｃ O ｎｃ (M ｃｃ is at least one element selected from C, S, Al, Si, Ga, Ge, In, and Sn, where xc satisfies 0≦xc≦5, yc satisfies 0≦yc≦1, zc satisfies 0≦zc≦1, and nc satisfies 0≦nc≦6.), Li ｘｄ (Al, Ga) ｙｄ (Ti, Ge) ｚｄ Si ａｄ P ｍｄ O ｎｄ(where 1≦xd≦3, 0≦yd≦2, 0≦zd≦2, 0≦ad≦2, 1≦md≦7, 3≦nd≦15), Li （３－２ｘｅ） M ｅｅ ｘｅ D ｅｅ O(xe represents a number between 0 and 0.1, and M ｅｅ represents a divalent metal atom. ｅｅ represents a halogen atom or a combination of two or more halogen atoms.), Li ｘｆ Si ｙｆ O ｚｆ (1≦xf≦5, 0<yf≦3, 1≦zf≦10), Li ｘｇ S ｙｇ O ｚｇ (1≦xg≦3, 0<yg≦2, 1≦zg≦10), Li ３ BO ３ -Li ２ SO ４ , Li ２ Alumni ２ O ３ -P ２ O ５ , Li ２ O—SiO ２ , Li ６ BaLa ２ Ta ２ O １２ , Li ３ P.O. （４－３／２ｗ） N ｗ (w is w<1), Li having a LISICON (Lithium super ionic conductor) type crystal structure ３．５ Zn ０．２５ GeO ４ , La having a perovskite crystal structure ０．５１ Li ０．３４ TiO ２．９４ , La ０．５５ Li ０．３５ TiO ３ , LiTi having a NASICON (sodium super ionic conductor) type crystal structure ２ P ３ O １２ , Li １＋ｘｈ＋ｙｈ (Al, Ga) ｘｈ (Ti, Ge) ２－ｘｈ Si ｙｈ P ３－ｙｈ O１２ (where 0≦xh≦1, 0≦yh≦1), Li having a garnet-type crystal structure ７ La ３ Zr ２ O １２ Also, ceramic materials in which elements are substituted for LLZ are known. For example, Li ６．２４ La ３ Zr ２ Al ０．２４ O １１．９８ , Li ６．２５ Al ０．２５ La ３ Zr ２ O １２ and Li substituted with Ta ６．６ La ３ Zr １．６ Ta ０．４ O １２ , Nb-substituted Li ６．７５ La ３ Zr １．７５ Nb ０．２５ O １２ Other examples include LLZ-based ceramic materials in which at least one element of Mg (magnesium) and A (A is at least one element selected from the group consisting of Ca (calcium), Sr (strontium), and Ba (barium)) is substituted for LLZ. Phosphorus compounds containing Li, P, and O are also desirable. For example, lithium phosphate (Li ３ P.O. ４ ), LiPON, LiPOD, in which some of the oxygen in lithium phosphate is replaced with nitrogen １ (D １ is at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, Au, etc. １ ON (A １ is at least one selected from Si, B, Ge, Al, C, Ga, etc.) can also be preferably used. ２ O-Al ２ O ３ -SiO ２ -P ２ O ５-TiO ２ -GeO ２ , Li ２ O-Al ２ O ３ -SiO ２ -P ２ O ５ -TiO ２ etc.

[0065] The oxide-based solid electrolyte preferably contains lithium. The oxide-based solid electrolyte containing lithium is used in a solid-state battery that uses lithium ions as a carrier, and is particularly preferred in terms of electrochemical devices having a high energy density.

[0066] The oxide-based solid electrolyte is preferably an oxide having a crystalline structure. Oxides having a crystalline structure are particularly preferred in terms of good Li ion conductivity. Examples of oxides having a crystalline structure include perovskite-type (La ０．５１ Li ０．３４ TiO ２．９４ ), NASICON type (Li １．３ Al ０．３ Ti １．７ (P.O. ４ ) ３ etc.), garnet type (Li ７ La ３ Zr ２ O １２ (LLZ), etc. Among these, garnet type is preferred.

[0067] The present disclosure also includes an electrochemical device including the gasket of the present disclosure.

[0068] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0069] The present disclosure will now be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[0070] Experimental Examples 1 to 9 <Raw Materials> Polypropylene (PP) (product name: Prime Polypro F227, manufactured by Prime Polymer Co., Ltd.) Polybutylene terephthalate (PBT) (product name: PBT Natural Color Unfilled, manufactured by Kureha Extron Co., Ltd.) Ultra-high molecular weight polyethylene (UHMWPE) (product name: Hi-Zex Million, manufactured by Mitsui Chemicals, Inc.)

[0071] <Fracture compression ratio (compression ratio at break)> For three types of materials, PP, PBT, and UHMWPE, the outer diameter was 17.7±0.1 mm, the inner diameter was 14.2±0.1 mm, and the thickness was 1.6±0.05 mm (L ０ Compression tests were conducted in accordance with JIS K7181:2011 using annular gaskets with a rectangular cross section (size 100 mm or larger). After compressing to a predetermined compression ratio, the gaskets were opened, removed, and observed under a microscope to determine the rupture compression ratio. The predetermined compression ratios were 60%, 65%, 70%, 75%, and 80%, in 5% increments, and 10 gaskets were used for each compression ratio. The compression ratio at which crazes began to appear on the surface or inside of the gaskets based on observation was defined as the rupture compression ratio. The results are shown in Table 1.

[0072] <Test Piece> The above polymer was heated to above its melting point to prepare a sheet, and from the sheet, a circular gasket with a square cross section, measuring 14.3 mm in inner diameter, 17.7 mm in outer diameter, and 1.6 mm in height, was prepared.

[0073] <Water Vapor Permeation Test> As shown in FIG. 2, 2 g of water 42 was placed in an aluminum alloy cup 41. A gasket 47 was inserted between the cup 41 and a gasket compression jig 43, and the lid 44 was tightened with bolts 45 to compress the gasket 47. A spacer 46 was placed between the lid 44 and the cup 41, and the compression rate of the gasket 47 was adjusted to 12.5%, 37.5%, or 62.5%. The compression rate was calculated using the following formula: (Gasket compression rate (%)) = {1 - (Distance between the cup 41 and the gasket compression jig 43 (gasket placement portion)) / (Height of the gasket before compression)} × 100. The mass of the permeation test jig 40 obtained in this manner was measured. The permeation test jig 40 was placed in an electric furnace at 80°C, left for 1000 hours, removed, and left at room temperature for 2 hours, after which the mass was measured. The water vapor permeation coefficient was calculated using the following formula. This operation was repeated three times, and the average water vapor permeation coefficient was calculated. The average values ​​are shown in Table 2. Water vapor permeability coefficient (g / 1000 hr) = (mass of permeation test jig before heating) - (mass of permeation test jig after heating)

[0074]

[0075]

[0076] 10: Electrochemical device 1: Lid 2: External terminal 21: Terminal head 22: Shaft 3: Gasket 31: Cylindrical portion 32: Flange portion 33: Side wall portion 4: Insulating plate 40: Permeation test jig 41: Cup 42: Water 43: Gasket compression jig 44: Lid 45: Bolt 46: Spacer 47: Gasket

Claims

1. A gasket for electrochemical devices that contains polybutylene terephthalate and has a compression rate of 5% or more when installed.

2. The gasket of claim 1, wherein the compression ratio is less than the rupture compression ratio.

3. The gasket according to claim 1 or 2, which has a water vapor permeability coefficient of less than 0.010 g / 1000 hr.

4. The gasket according to any one of claims 1 to 3, which is in contact with an electrolyte.

5. An electrochemical device comprising the gasket according to any one of claims 1 to 4.

6. A gasket for an electrochemical device, which contains a polymer and has a compression rate of 20% or more and 75% or less when installed.

7. The gasket of claim 6, wherein the compression ratio is less than the rupture compression ratio.

8. The gasket according to claim 6 or 7, which has a water vapor permeability coefficient of less than 0.010 g / 1000 hr.

9. The gasket according to any one of claims 6 to 8, which comprises a polymer having a fluorine substitution rate of 95% or less.

10. The gasket according to any one of claims 6 to 9, which contains at least one polymer selected from the group consisting of polyethylene, polypropylene, polybutylene terephthalate and polyphenylene sulfide.

11. The gasket according to any one of claims 6 to 10, which is in contact with an electrolyte.

12. An electrochemical device comprising the gasket according to any one of claims 6 to 11.

Images