Support for solid electrolytes and solid electrolyte sheet containing the same

Abstract

To provide a substrate for solid electrolyte, suitable for making a solid electrolyte sheet having a low electric resistance, and a solid electrolyte sheet including the same.SOLUTION: The present invention relates to a substrate for solid electrolyte including a nonwoven fabric, having an elastic recovery of 30 to 99%, and a solid electrolyte sheet having a low electric resistance, which includes the substrate for solid electrolyte and a solid electrolyte.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a support for a solid electrolyte and a solid electrolyte sheet containing the same. [Background technology]

[0002] In recent years, with the development of portable devices and the practical application of electric vehicles, there has been a growing need for small, lightweight batteries with high capacity and high energy density.

[0003] The lithium-ion secondary batteries used in this process consist of a positive electrode active material, a negative electrode active material, and an electrolyte. Various improvements are being made to further enhance functionality, focusing on longer lifespan, higher capacity, and higher energy density. Furthermore, as these batteries are increasingly being used in products directly related to human life, such as automobiles, safety and reliability are simultaneously required, in addition to the aforementioned improvements in battery functionality.

[0004] Among these, the battery currently attracting attention is the all-solid-state battery. Conventional lithium-ion secondary batteries use organic electrolytes, which pose a risk of fire due to internal short circuits caused by overcharging or over-discharging, and are also prone to leakage. On the other hand, all-solid-state batteries use solid electrolytes, offering significant advantages in terms of safety and reliability. As solid electrolytes, sulfide and oxide-based inorganic electrolytes and polymer-based organic electrolytes are widely used.

[0005] To achieve the high energy density and high capacity required for batteries, solid electrolytes need to be thin, highly ionic conductive, and strong enough for improved handling. Therefore, a support electrolyte, where the solid electrolyte is coated onto a support, is used, and fibrous sheets such as nonwoven fabrics are used as the support.

[0006] Patent Document 1 below discloses a solid electrolyte sheet having an aromatic liquid crystal polyester nonwoven fabric, characterized in that the aromatic liquid crystal polyester nonwoven fabric has a high porosity for the purpose of being filled with a polymer solid electrolyte.

[0007] Patent Document 2 below discloses a solid electrolyte sheet that uses a porous substrate composed of fibrous material as a support.

[0008] Furthermore, Patent Document 3 discloses a solid electrolyte sheet using a nonwoven fabric having a specific basis weight and thickness as a support. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2006-190627 [Patent Document 2] International Publication No. 2020-054081 [Patent Document 3] Japanese Patent Publication No. 2016-31789 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] However, in the above-mentioned Patent Documents 1 to 3, the flexibility of the electrolyte sheet interface was not sufficiently considered, and the problem was that the electrical resistance increased due to insufficient conformability and contact with the electrode interface as an electrolyte sheet.

[0011] In view of the above-mentioned problems, the problem that the present invention aims to solve is to provide a solid electrolyte support suitable for obtaining an electrolyte sheet with low electrical resistance, and a solid electrolyte sheet containing the same. [Means for solving the problem]

[0012] The inventors of this invention diligently studied and conducted numerous experiments to solve the above problems, and as a result, unexpectedly discovered that the above problems could be solved with the following configuration, thus completing the present invention. In other words, the present invention is as follows: [1] A support for a solid electrolyte containing a non-woven fabric, characterized in that the elastic recovery rate of the support is 30 to 99%. [2] The support for a solid electrolyte according to [1], wherein the porosity of the support is 30 to 95%. [3] The support for a solid electrolyte according to [1] or [2], wherein the compression rate of the support is 0.1 to 40%. [4] The support for a solid electrolyte according to any one of [1] to [3], wherein the non-woven fabric contains synthetic fibers. [5] The support for a solid electrolyte according to [4], wherein the synthetic fiber is polyester. [6] The 100 g / m of the support 2 The support for a solid electrolyte according to any one of [1] to [5], wherein the thickness under load is 5 to 200 μm. [7] The support for a solid electrolyte according to any one of [1] to [6], wherein the non-woven fabric contains fibers with a fiber length of 51 mm or more. [8] The support for a solid electrolyte according to any one of [1] to [7], wherein the basis weight of the support is 5 to 50 g / m 2 . [9] The support for a solid electrolyte according to any one of [1] to [8], wherein the non-woven fabric contains ultrafine fibers with a fiber diameter of 0.1 to 5.0 μm.

[10] The support for a solid electrolyte according to any one of [1] to [9], wherein the non-woven fabric includes a layer containing ultrafine fibers with a fiber diameter of 0.1 to 5.0 μm and a layer containing fibers with a fiber diameter of more than 5.0 μm and 30 μm or less.

[11] The support for a solid electrolyte according to

[10] , wherein the non-woven fabric includes a layer (layer I) containing ultrafine fibers with a fiber diameter of 0.1 to 5.0 μm and a layer (layer II) containing fibers with a fiber diameter of more than 5.0 μm and 30 μm or less.

[12] The support for a solid electrolyte according to any one of [1] to

[11] , wherein the non-woven fabric is thermally bonded over the entire surface.

[13] A solid electrolyte support according to any one of [1] to

[12] , wherein the nonwoven fabric comprises a layer (Layer I) containing ultrafine fibers with a fiber diameter of 0.1 to 5.0 μm and a layer (Layer II) containing fibers with a fiber diameter greater than 5.0 μm and less than or equal to 30 μm, the elastic recovery rate of the support is 45 to 99%, and the compressibility of the support is 0.1 to 9.7%.

[14] A solid electrolyte sheet comprising a support for a solid electrolyte according to any of [1] to

[13] above, and a solid electrolyte.

[15] The electrical conductivity of the solid electrolyte sheet is 1.0 × 10 -5 ~5.0×10 -1 A solid electrolyte sheet as described in

[14] , wherein the density is s / m. [Effects of the Invention]

[0013] The solid electrolyte support of the present invention is suitable for obtaining an electrolyte sheet with low electrical resistance. Furthermore, the solid electrolyte sheet of the present invention has low electrical resistance. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described in detail below. One embodiment of the present invention is a support for a solid electrolyte comprising a nonwoven fabric, characterized in that the elastic recovery rate of the support is 30 to 99%. The support for the solid electrolyte in this embodiment (hereinafter also simply referred to as "support") includes a nonwoven fabric. There are no particular limitations on the type of nonwoven fabric; for example, spunbond nonwoven fabric or meltblown nonwoven fabric can be used.

[0015] The elastic recovery rate of the support in this embodiment is 30 to 99%, preferably 45% or more, more preferably 50% or more, and also preferably 98% or less, more preferably 97% or less. The elastic recovery rate greatly affects the conformability of the electrolyte sheet to the electrode interface. In other words, the higher the elastic recovery rate, the better the sheet conforms to the electrode interface, and the lower the electrical resistance between the electrolyte sheet surface and the electrode.

[0016] The porosity of the support in this embodiment is preferably 30 to 95%, more preferably 35 to 90%, and even more preferably 40 to 85%. If the porosity is 30% or more, the amount of solid electrolyte that can be held increases, so the solid electrolytes come into sufficient contact with each other, and the electrical resistance inside the sheet decreases. On the other hand, if the porosity is 95% or less, the strength of the support can be ensured, and the occurrence of short circuits in the electrode reaction of the active material can be suppressed.

[0017] The compressibility of the support in this embodiment is preferably 0.1% or more, more preferably 0.5% or more, even more preferably 1% or more, and also preferably 40% or less, more preferably 35% or less, even more preferably 30% or less, and most preferably 9.7% or less. The electrolyte sheet is manufactured using press molding, and a higher compressibility of the support contributes to thinner sheets. Furthermore, a higher compressibility allows for more solid electrolyte to be packed into the sheet, increasing the contact area between electrolytes and lowering electrical resistance. Moreover, a higher compressibility increases the flexibility of the electrolyte sheet, allowing the interface on the electrolyte sheet side to follow the expansion and contraction of the electrode surface during electrode reactions, thereby reducing contact resistance. Additionally, a compressibility of 40% or less allows for sufficient packing of solid electrolyte during electrolyte sheet formation by press molding.

[0018] The nonwoven fabric included in the support of this embodiment preferably contains synthetic fibers. Synthetic fibers are chemically stable and make it easy to obtain a high-quality electrolyte sheet. As materials for the synthetic fibers, polyolefins such as polypropylene and polyethylene, polystyrene, polyphenylene sulfide, aramid, polyamide-imide, polyimide, nylon, and polyester such as polyethylene terephthalate (PET) can be used, with polyester being particularly preferred. Since polyester has higher heat resistance than other resins, the support containing the nonwoven fabric containing polyester has excellent dimensional stability. Furthermore, polyester is chemically stable and does not undergo reactions such as corrosion even when in contact with solid electrolytes such as sulfides or lithium metal. In addition, polyester has electrical insulating properties, which also helps to suppress short circuits of the electrode active material.

[0019] The support of this embodiment has a basis weight of 100 g / m 2 The thickness under load is preferably 5 to 200 μm, more preferably 7 μm to 180 μm, and still more preferably 10 to 150 μm. For a basis weight of 100 g / m 2 If the thickness under load is 5 μm or more, it is easy to increase the tensile strength, and the handling property during coating is good. On the other hand, for a basis weight of 100 g / m 2 If the thickness under load is 200 μm or less, the thickness after press molding can be suppressed, and the electrical resistance value of the electrolyte sheet decreases.

[0020] The non-woven fabric contained in the support of this embodiment preferably contains fibers having a fiber length of 51 mm or more, more preferably 100 mm or more, and still more preferably 150 mm or more. If the fiber length is 51 mm or more, the support has excellent tensile properties, tear properties, and puncture properties. Also, if the fiber length is 51 mm or more, there are few shedding fibers, and it is easy to produce an electrolyte sheet with excellent shape retention.

[0021] The basis weight of the support of this embodiment is preferably 5 to 50 g / m 2 and more preferably 8 to 40 g / m 2 and still more preferably 10 to 30 g / m 2 If the basis weight is 5 g / m 2 or more, it can be handled with good handling property in the coating process, and if it is 50 g / m 2 or less, since it is sufficiently thin after press molding, it is easy to lower the electrical resistance as an electrolyte sheet.

[0022] The apparent density of the support of this embodiment is preferably 0.069 to 0.97 g / cm 3 and more preferably 0.13 to 0.90 g / cm 3 and still more preferably 0.21 to 0.83 g / cm 3 If the apparent density is 0.69 g / cm 3 or more, the strength as a support can be ensured, and the occurrence of short circuits in the electrode reaction of the active material can be suppressed. On the other hand, if the apparent density is 0.97 g / cm 3If the following conditions are met, the amount of solid electrolyte held will increase, allowing for sufficient contact between the solid electrolytes and lowering the electrical resistance within the sheet.

[0023] The nonwoven fabric included in the support of this embodiment preferably includes an ultrafine fiber layer with a fiber diameter of 0.1 to 5 μm. Including the ultrafine fiber layer makes it easier to form an electrolyte sheet in which the solid electrolyte is uniformly arranged, and the electrical resistance can be reduced. In addition, including the ultrafine fiber layer suppresses seepage of the solid electrolyte during coating, resulting in an electrolyte sheet free of pinholes and defects, making it easier to obtain a high-quality electrolyte sheet. Furthermore, if the fiber diameter of the ultrafine fiber layer is 0.1 μm or more, the fiber strength is sufficiently high, ensuring the strength of the support, which is preferable. On the other hand, if the fiber diameter of the ultrafine fiber layer is 5 μm or less, the interfiber distance is made uniform, making it easier to form an electrolyte sheet in which the solid electrolyte is uniformly arranged. From the above viewpoint, the fiber diameter of the ultrafine fiber layer is preferably 0.3 to 4.0 μm, and more preferably 0.5 to 3.0 μm.

[0024] The nonwoven fabric included in the support of this embodiment is preferably composed of at least two layers, including an ultrafine fiber layer (Layer I) with a fiber diameter of 0.1 to 5 μm and a fiber layer (Layer II) with a fiber diameter of more than 5 μm and 30 μm or less. In this case, Layer I plays the role of a functional layer, and Layer II plays the role of a strength layer. By using a laminated nonwoven fabric of at least two layers, combining Layer I and Layer II, a denser, network-like nonwoven fabric structure can be formed compared to when each layer is used as a support individually. As a result, when it is used as an electrolyte sheet, the electrolyte is filled more uniformly, resulting in lower electrical resistance. Preferred laminated structures include a two-layer structure of Layer I-Layer II, a three-layer structure of Layer I-Layer-Layer I, a three-layer structure of Layer II-Layer I-Layer (i.e., a three-layer structure in which Layer I is positioned as an intermediate layer between two Layer IIs), and a four-layer structure of Layer I-Layer-Layer II-Layer I.

[0025] The method for manufacturing the nonwoven fabric included in the support of this embodiment is not limited. However, when the above-mentioned II layer is provided, the manufacturing method is preferably the spunbond method, dry method, wet method, etc. When the above-mentioned I layer is provided, the manufacturing method is preferably the dry or wet method using ultrafine fibers, electrospinning method, melt-blown method, or force spinning method, etc. From the viewpoint of easily and densely forming the ultrafine fiber layer, the I layer is preferably formed by the melt-blown method. Furthermore, the fibers forming the I layer may be split or fibrillated by beating, partial dissolution, etc., before being used for the manufacture of the nonwoven fabric.

[0026] Methods for integrating unbonded webs and forming a laminated nonwoven fabric having the I layer and the II layer include, for example, a method of integration by thermal bonding, a method of three-dimensional entanglement by spraying a high-speed water stream, and a method of integration using particulate or fibrous adhesives. Integration by thermal bonding is preferred because it allows the formation of a laminated nonwoven fabric without the use of a binder. Methods of integration by thermal bonding include integration by thermal embossing (thermal embossing roll method) and integration by high-temperature hot air (air-through method).

[0027] Integration by thermal bonding can be achieved, for example, by thermal bonding using a press roll (flat roll or embossed roll) at a temperature 50 to 120°C lower than the melting point of the synthetic resin, with a linear pressure of 100 to 1000 N / cm. From the viewpoint of reducing the thickness and lowering the electrical resistance of the electrolyte sheet, it is preferable to use thermal bonding with a flat roll to create a nonwoven fabric that is thermally bonded across its entire surface. In this specification, the term "thermally bonded across its entire surface" refers to thermal bonding across the entire surface of the nonwoven fabric, not so-called partial thermal bonding (point bonding) where only a part of the nonwoven fabric is thermally bonded. Furthermore, if the linear pressure in the thermal bonding process is 100 N / cm or higher, sufficient adhesion is easily obtained and sufficient strength is easily achieved. Also, if the linear pressure is 1000 N / cm or lower, the deformation of the fibers is small, the apparent density is low, the porosity is high, and the desired effect is easily obtained.

[0028] Furthermore, thermal bonding allows for control of the compression characteristics of the nonwoven fabric after pressing by controlling the fabric temperature before it enters the press roll during the heat bonding process. The fabric temperature before pressing is the temperature of the nonwoven fabric (web) 50 cm upstream from the roll nip point. For example, in the case of polyester material, by setting the fabric temperature before pressing to a range of 40 to 120°C, it is possible to obtain the elastic recovery rate and compression rate within the above range. By setting a high fabric temperature before pressing, the crystallinity of the yarn is promoted in advance, thereby ensuring the minimum amount of amorphous material necessary for bonding between fibers, suppressing over-compression, and creating a support with a high elastic recovery rate. There are no particular limitations on the method of adjusting the fabric temperature before pressing to a range of 40 to 120°C, but examples include effectively utilizing the heat dissipation of the heated press roll with a heat retention plate, or preheating the nonwoven fabric with a preheating roll.

[0029] Another embodiment of the present invention is a solid electrolyte sheet comprising the solid electrolyte support and a solid electrolyte. The following describes a solid electrolyte sheet, which includes the support and solid electrolyte of this embodiment. The electrical conductivity of the solid electrolyte sheet, which includes the support and solid electrolyte of this embodiment, is 1.0 × 10⁻⁶. -5 ~5.0×10 -1 It is preferably s / m, and more preferably 5.0 × 10 -5 ~1.0×10 -1 s / m, more preferably 1.0 × 10 -4 ~5.0×10 -2 It is s / m.

[0030] The solid electrolyte used in combination with the support of this embodiment is not particularly limited as long as it has lithium ion conductivity, and examples include inorganic solid electrolytes such as sulfide solid electrolytes and oxide solid electrolytes, and polymer solid electrolytes. Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-Si, Li2S-P2S5-GeS2, and Li2S-B2S3 glass, as well as Li 10 GeP2S 12(LGPS-based) or Li6PS5Cl (argyrodite-based) can be used. Among these, argyrodite-based materials with particularly high lithium-ion conductivity and high chemical stability are preferred. As an oxide-based solid electrolyte, for example, Li7La3Zr20 12 Examples include LiTi2Z(PO4)3, LiGeO2(P04)3, and LiLaTiO3.

[0031] In this embodiment, when a solid electrolyte is coated onto the support, the solid electrolyte can be coated in slurry form. The slurry used for coating can be prepared by adding solid electrolyte particles and a binder to a solvent and mixing them. It is preferable to select a solvent for the slurry that does not easily degrade the solid electrolyte. For example, it is preferable to use a non-polar aprotic solvent represented by hydrocarbon solvents such as hexane, heplan, octane, nonane, decane, decalin, toluene, and xylene. In particular, it is more preferable to use an ultra-dehydrated solvent with a water content of 0.001% by mass (10 ppm) or less. After filling the pores of the support with the slurry, the solvent in the slurry is removed by drying. After coating with slurry and drying of the solvent, the composite of the support and solid electrolyte is press-molded. The press-molding conditions are, for example, a pressure of 5 to 50 MPa, a temperature of 50 to 200°C, and a pressing time of 1 to 30 minutes. [Examples]

[0032] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited in any way to these examples. Unless otherwise specified, the length direction of the nonwoven fabric is the MD direction (machine direction), and the width direction is the direction perpendicular to the length direction within the plane of the nonwoven fabric.

[0033] (1) Basis weight (g / m 2 ) In accordance with the method specified in JIS L-1906, a 20 cm x 25 cm test specimen was taken at 3 locations per meter in the width direction and 3 locations per meter in the length direction, for a total of 9 locations per meter (1 m x 1 m), and its mass was measured. The average value was then converted to the mass per unit area to determine the basis weight.

[0034] (2) Thickness (μm) In accordance with the method specified in JIS L-1906, the thickness of the test specimen was measured at 10 locations per meter of width under a load of 9.8 kPa, and the average value was calculated.

[0035] (3) Apparent density (g / cm³) 3 ) The weight measured in (1) above (g / m 2 Using the thickness (μm) measured in (2) above, and adjusting the units, the following formula is used: Apparent density = (basis weight) / (thickness) The apparent density was calculated using the following method.

[0036] (4) Porosity (%) The apparent density (g / cm³) calculated in (3) above 3 Using ), the following equation: Porosity = {1 - (Apparent Density) / (Resin Density)} / 100 The porosity was calculated from this.

[0037] (5) Fiber diameter (μm) Nonwoven fabric was cut into 10cm x 10cm pieces, pressed onto iron plates at 60°C (top and bottom) under a pressure of 0.30MPa for 90 seconds, and then platinum was deposited onto the fabric. Using a SEM (Surface-Ejected Microscope) (JSM-6510, manufactured by JEOL Ltd.), the platinum-deposited nonwoven fabric was imaged under conditions of an acceleration voltage of 15kV and a working distance of 21mm. The magnification was set to 10,000x for yarns with an average fiber diameter of less than 0.5μm, 6,000x for yarns with an average fiber diameter of 0.5μm or more but less than 1.5μm, and 4,000x for yarns with an average fiber diameter of 1.5μm or more. The field of view at each magnification was 12.7μm x 9.3μm at 10,000x, 21.1μm x 15.9μm at 6,000x, and 31.7μm x 23.9μm at 4,000x. More than 100 fibers were randomly imaged, and the diameter of all fibers was measured. However, fibers fused together in the direction of the yarn's length were excluded from the measurement. The following formula: Dw = ΣWi·Di = Σ(Ni·Di) 2 ) / (Ni·Di) {In the formula, Wi = weight fraction of fiber diameter Di = Ni·Di / ΣNi·Di, where Ni is the number of fibers of fiber diameter Di.} The weight-average fiber diameter (Dw) obtained by this method was defined as the average fiber diameter (μm).

[0038] (6) Tensile strength (N / 15mm) Excluding 10 cm from each end of the sample (nonwoven fabric, support), 15 mm wide x 20 cm long test pieces were cut at 5 locations per 1 m width. A load was applied to the test pieces until they fractured, and the average strength of the test pieces at maximum load in the MD direction was determined.

[0039] (7) Elastic recovery rate, compressibility The elastic recovery rate and compressibility were measured using a Shimadzu MCT-50 microcompression testing machine. The test conditions involved applying a load to the sample up to the maximum test force, followed by unloading to the minimum test force, in a load-unload mode. The minimum test force was 0.05 mN, and the maximum test force was set to the force required for 10% deformation in compression mode. The elastic recovery rate and compressibility were calculated as follows. Elastic recovery rate (Rr) = {L2 / (L1-L2)} × 100 Compression ratio (Cr)=(L1 / d)×100 d: Thickness of the nonwoven fabric (support) L1: Displacement difference between maximum and minimum test force in load mode L2: Displacement difference between maximum and minimum test force in unloading mode

[0040] (8) Measurement of electrical resistance (electrical conductivity (S / m)) A HIOKI Digital Super Megohmmeter and a HIOKI SME-8311 electrode for flat samples were used as the measuring equipment. A 100mm x 100mm test specimen (solid electrolyte sheet) was prepared, and the electrical conductivity was measured under measurement conditions of 10V voltage and 60 seconds. The solid electrolyte sheet used for measurement was prepared as follows: An amorphous powder of the sulfide electrolyte Li2S-P2S5 (80:20 mol%) was mixed with a xylene solution of SBR (electrolyte binder) so that the SBR amounted to 1% of the mass of the amorphous powder. To this mixture, a xylene solution of NBR (electrolyte layer binder) was added so that the NBR amounted to 0.5% of the amorphous powder, and an appropriate amount of dehydrated xylene was added to adjust the viscosity. This mixture was placed in a mixing container, and zirconia balls were added so that they occupied 1 / 3 of the container's volume. The mixture was stirred at 3000 rpm for 5 minutes to prepare an electrolyte slurry. A support was impregnated into the electrolyte slurry, and then nipped using a roll press and smoothed with a blade to obtain a composite in which the slurry had sufficiently penetrated the inside of the support. This composite was dried in a hot air dryer to produce an electrolyte sheet.

[0041] [Examples 1-7, 12] As a fiber layer (Layer II) with a fiber diameter of more than 5 μm and less than or equal to 30 μm, polyethylene terephthalate (PET) resin was extruded from a spunbond spinneret (V-type nozzle) at a spinning temperature of 290°C. The yarn was cooled symmetrically from both sides by a cooling device directly below the spinneret (both at an air velocity of 0.5 m / s), and continuous long fibers (fiber diameter 15 μm) were obtained by pulling with a draw jet. These fibers were then spread and dispersed and deposited on a web conveyor to form a web. Next, as an ultrafine fiber layer (Layer I), PET resin was used and spun by the melt-blown method under conditions of a spinning temperature of 290°C, and blown onto the web. At this time, the distance from the melt-blown nozzle to the web was set to 300 mm, and the suction force at the collection surface directly below the melt-blown nozzle was set to 0.2 kPa and the air velocity to 7 m / sec. Furthermore, continuous long fibers (fiber diameter 15 μm) produced by the same spunbond method as above were laminated on top of this to obtain a laminated web. Furthermore, the laminated webs were integrated using a press roll (calender roll), and a nonwoven fabric was produced to a predetermined thickness by adjusting the calendering pressure and temperature, as shown in Table 1 below, and this was used as a support. The position of the heating plate on the heating roll was adjusted so that the fabric temperature before calendering, which is important for controlling the compression characteristics, was 50, 70, or 90°C.

[0042] [Example 8] As shown in Table 1 below, a nonwoven fabric was prepared in the same manner as in Example 1, except that polyphenylene sulfide (PPS) resin was used as the raw material, and the spinning temperature, calendering temperature, fabric temperature, thickness, and apparent density were adjusted to predetermined values. This nonwoven fabric was then used as a support.

[0043] [Example 9] As shown in Table 1 below, PET resin short fibers with a fiber diameter of 4 μm and a fiber length of 5 mm are formed into a net at a density of 20 g / m² using a papermaking method. 2 The fibers were collected in this manner, dehydrated and dried, and then compressed on a flat roll to the extent that the fibers did not dissipate, thereby obtaining a short-fiber nonwoven fabric. During compression, the calendering temperature and fabric temperature were adjusted as appropriate to obtain the desired thickness, porosity, and compression characteristics.

[0044] [Example 10] As a fiber layer (Layer II) with a fiber diameter of more than 5 μm and less than or equal to 30 μm, PET resin was extruded from a spunbond spinneret (V-type nozzle) at a spinning temperature of 290°C. The yarn was cooled symmetrically from both sides by a cooling device directly below the spinneret (both at an air velocity of 0.5 m / s), and continuous long fibers (fiber diameter 15 μm) were obtained by pulling with a drawjet. These fibers were then spread and dispersed and deposited on a web conveyor to form a web. Next, as shown in Table 1 below, the web was integrated using a calender roll, and a nonwoven fabric was produced by adjusting the calendering pressure to achieve a predetermined thickness, which was then used as a support. The fabric temperature before calendering was adjusted to 70°C.

[0045] [Example 11] As the ultrafine fiber nonwoven fabric layer (Layer I), PET resin was used and spun by the melt-blown method under conditions of a spinning temperature of 290°C, and deposited on a web conveyor. At this time, the distance from the melt-blown nozzle to the web was set to 300 mm, and the suction force at the collection surface directly below the melt-blown nozzle was set to 0.2 kPa and the air velocity to 7 m / sec. Next, as shown in Table 1 below, the web was integrated using a calender roll, and a nonwoven fabric was produced by adjusting the calendering pressure to achieve a predetermined thickness, which was then used as the support. The fabric temperature before calendering was adjusted to 70°C.

[0046] [Example 13] Similar to Example 1, polyethylene terephthalate (PET) resin was extruded from a spunbond spinneret (V-type nozzle) at a spinning temperature of 290°C to form a fiber layer (Layer II) with a fiber diameter of more than 5 μm and less than or equal to 30 μm. The yarn was cooled symmetrically from both sides by a cooling device directly below the spinneret (both at a wind speed of 0.5 m / s), and continuous long fibers (fiber diameter 15 μm) were obtained by pulling with a draw jet. These fibers were then spread and dispersed and deposited on a web conveyor to form a web. Next, PET resin was used as the ultrafine fiber layer (Layer I), and spun by the melt-blown method under conditions of a spinning temperature of 290°C, and blown onto the web. At this time, the distance from the melt-blown nozzle to the web was set to 300 mm, and the suction force at the collection surface directly below the melt-blown nozzle was set to 0.2 kPa and the wind speed to 7 m / sec. Furthermore, the laminated webs were integrated using a press roll (calender roll), and a nonwoven fabric was produced to a predetermined thickness by adjusting the calendering pressure and temperature, as shown in Table 1 below, and this was used as a support. The position of the heating plate on the heating roll was adjusted so that the fabric temperature before calendering, which is important for controlling the compression characteristics, was 70°C.

[0047] [Comparative Example 1] A short-fiber nonwoven fabric made of PET resin with a fiber diameter of 4 μm and a fiber length of 5 mm was subjected to calendering as shown in Table 1 below to obtain the desired thickness, porosity, and compression characteristics. The fabric temperature was not specifically considered, and the calendering was performed at the ambient temperature of 23°C.

[0048] [Comparative Example 2] As shown in Table 1 below, a nonwoven fabric was prepared in the same manner as in Example 10, except that the fabric temperature before calendering was set to the ambient temperature of 23°C, and this was used as a support.

[0049] [Table 1] [Industrial applicability]

[0050] The solid electrolyte support of the present invention can be combined with inorganic solid electrolytes such as sulfide solid electrolytes and oxide solid electrolytes, or polymer solid electrolytes, to obtain a solid electrolyte sheet with low electrical resistance, and is therefore suitable for use as a component in all-solid-state batteries.

Claims

1. A solid electrolyte sheet comprising a support for a solid electrolyte and a solid electrolyte, The solid electrolyte support comprises a laminated nonwoven fabric consisting of a spunbond nonwoven fabric and a melt-blown nonwoven fabric, the laminated nonwoven fabric being heat-bonded across its entire surface, the compressibility of the support being 1.1% to 9.7%, the porosity of the support being 40% to 85%, and the apparent density of the support being 0.21 g / cm³. 3 0.83g / cm or more 3 The following: The solid electrolyte is a sulfide solid electrolyte or an oxide solid electrolyte, and The electrical conductivity of the solid electrolyte sheet is 1.0 × 10⁻⁴ to 5.0 × 10⁻¹ s / m. A solid electrolyte sheet characterized by the following features.

2. The following steps: A process of filling a solid electrolyte inside a support for a solid electrolyte, press-molding it, and obtaining a solid electrolyte sheet having an electrical conductivity of 1.0 × 10⁻⁴ to 5.0 × 10⁻¹ s / m; A method for producing a solid electrolyte sheet, comprising: The solid electrolyte support comprises a laminated nonwoven fabric consisting of a spunbond nonwoven fabric and a melt-blown nonwoven fabric, the laminated nonwoven fabric being heat-bonded across its entire surface, the compressibility of the support being 1.1% or more and 9.7% or less, the porosity of the support being 40% or more and 85% or less, and the apparent density of the support being 0.21 g / cm³ or more and 0.83 g / cm³ or less, A method for manufacturing a solid electrolyte sheet, wherein the solid electrolyte is a sulfide solid electrolyte or an oxide solid electrolyte.

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