Sheet for supporting solid electrolytes

Abstract

To provide a lightweight, highly porous, and puncture-resistant sheet for supporting solid electrolytes. [Solution] A sheet for carrying a solid electrolyte, made of a wet nonwoven fabric containing polyester core-sheath composite binder fibers, wherein the wet nonwoven fabric has a basis weight of 3 to 8 g / m². 2 The porosity is 60% or more, and the puncture strength-to-weight ratio is 8 gf / (g / m²). 2 A sheet for supporting solid electrolytes, characterized by being ) or more.

Description

[Technical Field]

[0001] This invention relates to a sheet for supporting solid electrolytes. [Background technology]

[0002] In recent years, all-solid-state batteries have attracted attention as the next-generation technology for lithium-ion batteries. Conventional lithium-ion batteries use organic solvent-based electrolytes, but all-solid-state batteries use solid electrolytes. Conventional organic solvent-based electrolytes are highly flammable, posing a risk of fire, and also have the problem that the charge and discharge performance of lithium-ion batteries changes significantly with temperature. On the other hand, all-solid-state batteries use a non-flammable solid electrolyte, thus reducing the risk of ignition, and are expected to exhibit stable performance across a wide temperature range due to their high electrochemical stability.

[0003] Sulfide-based electrolytes and oxide-based electrolytes are used as solid electrolytes. Generally, these solid electrolytes are formed by creating a slurry by dispersing the solid electrolyte and binder in a solvent, and then coating the surface with this slurry to form a solid electrolyte sheet.

[0004] However, this manufacturing method results in a brittle solid electrolyte sheet with low strength, making it difficult to handle. Furthermore, during the battery manufacturing process, when the electrode layers are stacked, the particles of the electrode layers come into contact with the solid electrolyte sheet, creating puncture stress. This makes the weak solid electrolyte sheet prone to cracking and other damage. Therefore, it is necessary to improve the puncture strength of the solid electrolyte sheet to prevent damage during the stacking process.

[0005] Among these, it has been proposed to use a nonwoven fabric combining polypropylene fibers or polyethylene fibers with fibrillated heat-resistant fibers as a support sheet for solid electrolytes (Patent Document 1). However, polypropylene and polyethylene, which are the materials that make up the nonwoven fabric, have a melting point of 120 to 160°C and low heat resistance, so there is a risk that the shape of the solid electrolyte layer may change when exposed to high temperatures. Thermal stability is necessary for solid electrolyte support sheets to exhibit stable battery performance over a wide temperature range.

[0006] Therefore, a solid electrolyte sheet made of nonwoven polyester fibers has been proposed (Patent Document 2). However, the disclosed polyester nonwoven fabric is simply made of polyester fibers with a basis weight of 8 g / m². 2 The following is the only method used, and such nonwoven fabrics have the drawback of low strength. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-24860 [Patent Document 2] Japanese Patent Publication No. 2016-31789 [Overview of the project] [Problems that the invention aims to solve]

[0008] This invention was made in view of the above background. The object of this invention is to provide a sheet for supporting solid electrolytes that is lightweight, has high porosity, and has excellent puncture strength. [Means for solving the problem]

[0009] In other words, the present invention relates to a sheet for carrying a solid electrolyte, which is made of a wet nonwoven fabric containing polyester core-sheath composite binder fibers, wherein the wet nonwoven fabric has a basis weight of 3 to 8 g / m². 2 The porosity is 60% or more, and the puncture strength-to-weight ratio is 8 gf / (g / m²). 2A sheet for supporting a solid electrolyte, characterized in that it is as described above. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a sheet for supporting a solid electrolyte that is lightweight, has high porosity, and is excellent in puncture strength. [Mode for Carrying Out the Invention]

[0011] Hereinafter, the present invention will be described in detail.

[0012] [Sheet for Supporting Solid Electrolyte] The wet-laid nonwoven fabric of the sheet for supporting a solid electrolyte according to the present invention is a wet-laid nonwoven fabric containing polyester core-sheath composite binder fibers.

[0013] [Polyester Core-Sheath Composite Binder Fiber] In the polyester core-sheath composite binder fiber according to the present invention, a binder component polymer that fuses at a temperature of 80 to 170°C to exhibit an adhesive effect is arranged in the sheath portion, and another polymer having a melting point 20°C or more higher than that of the sheath polymer is arranged in the core portion.

[0014] As the polymer for the sheath portion, amorphous copolyester can be exemplified. As the polymer for the core portion, aromatic polyesters such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polyethylene naphthalate can be exemplified.

[0015] As the polyester core-sheath composite binder fiber, a fiber in which the binder component forms all or part of the surface of a single fiber can be used, and the fiber may be an eccentric core-sheath composite fiber or a side-by-side composite fiber.

[0016] The polyester core-sheath composite binder fiber is excellent in adhesive force because it bonds fibers together by fusion of the sheath portion. In addition, since the polyester core-sheath composite binder fiber is excellent in water dispersibility, aggregation of fibers can be suppressed, and even a low-basis-weight nonwoven fabric can be produced with less unevenness and hole defects and excellent uniformity.

[0017] The polymer of the core portion preferably has a melting point of 190°C or higher. In this case, the core portion can maintain its shape without melting even when exposed to high temperatures during compounding with a solid electrolyte, battery manufacturing processes, and battery usage environments, so blocking of ion conduction paths and structural destruction of the solid electrolyte layer can be suppressed.

[0018] From the viewpoint of paper formability and strength of wet-laid nonwoven fabrics, the polyester core-sheath composite binder fiber preferably accounts for 30 to 100% by weight, more preferably 50 to 100% by weight of the weight of the wet-laid nonwoven fabric. If the weight of the polyester core-sheath composite binder fiber is less than 30% by weight, the strength of the wet-laid nonwoven fabric may be weakened, which is not preferable.

[0019] The average fiber diameter of the polyester core-sheath composite binder fiber is preferably 1 to 9 μm. If the average fiber diameter is less than 1 μm, the rigidity and strength of the nonwoven fabric may be insufficient, which is not preferable. On the other hand, if the average fiber diameter exceeds 9 μm, when producing a lightweight nonwoven fabric, the number of constituent fibers is small, so the fiber network becomes weak and sheet formation may become difficult, which is not preferable.

[0020] [Polyester non-binder fiber] The wet-laid nonwoven fabric of the solid electrolyte-supporting sheet of the present invention may contain polyester non-binder fibers in addition to the polyester core-sheath composite binder fibers. The polyester non-binder fibers preferably account for 0 to 70% by weight, more preferably 0 to 50% by weight of the wet-laid nonwoven fabric. If it exceeds 70% by weight, the strength of the wet-laid nonwoven fabric may be weakened, which is not preferable.

[0021] Examples of non-binder polyester fibers include drawn aromatic polyesters such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polyethylene naphthalate. These aromatic polyesters may also be copolymerized polyesters.

[0022] The melting point of polyester non-binder fibers is preferably 260-270°C. This melting point range provides excellent heat resistance, solvent resistance, and hydrolysis resistance, resulting in a highly reliable nonwoven fabric suitable for use as a separator or solid electrolyte support sheet. Polyester non-binder fibers have excellent dispersibility in water, which suppresses fiber aggregation and allows for the creation of uniform nonwoven fabrics with fewer inconsistencies and pore defects, even at low basis weights.

[0023] The average fiber diameter of the polyester non-binder fibers is preferably 0.1 to 9 μm. If the average fiber diameter is less than 0.1 μm, dispersion becomes difficult, and the fibers may pass through the mesh during the papermaking process, making it difficult to form a nonwoven fabric, which is undesirable. On the other hand, if it exceeds 9 μm, it may lead to non-uniformity of the nonwoven fabric, and when making a lightweight nonwoven fabric, the number of constituent fibers is small, resulting in a weak fiber network and making sheet formation difficult, which is also undesirable.

[0024] [Wet-processed nonwoven fabric] The solid electrolyte support sheet of the present invention is a wet-laid nonwoven fabric. By using a wet-laid nonwoven fabric that meets the following conditions, a lightweight, highly porous, and puncture-resistant solid electrolyte support sheet can be obtained.

[0025] [Inspector] The basis weight of wet-laid nonwoven fabrics is 3-8 g / m². 2 Preferably 3-6 g / m 2 The weight is 3g / m 2 If the density is less than 8 g / m², the fiber network may be weak, making sheet formation difficult. 2Beyond this point, resistance may increase, and the increased volume is detrimental to making the battery compact.

[0026] [Porosity] The porosity of the wet-laid nonwoven fabric is 60% or more, preferably 65% ​​or more. If the porosity is less than 60%, the voids in the wet-laid nonwoven fabric are small, making it difficult for the solid electrolyte to penetrate the interior. This may lead to non-uniformity of the solid electrolyte, resulting in a shorter lifespan and increased resistance.

[0027] [Piercing strength weight ratio] The puncture strength-to-weight ratio is the value obtained by dividing the puncture strength of the wet-laid nonwoven fabric by its basis weight. In this invention, this value is 8 gf / (g / m²). 2 ) That is all. This puncture strength indicates the toughness in the cross-sectional direction. Wet-laid nonwoven fabrics need a certain level of toughness to absorb stress when stress concentrates during processes such as composite formation with solid electrolytes or lamination of electrodes, and the greater the toughness, the better.

[0028] [Tensile strength] The tensile strength of the wet-laid nonwoven fabric in the MD and CD directions is preferably 0.3 N / 15 mm or higher. The MD direction is the mechanical direction of the nonwoven fabric, and the CD direction is the width direction. This tensile strength is a numerical value that indicates the toughness of the sheet for supporting solid electrolytes. A certain level of toughness is required for the wet-laid nonwoven fabric to prevent tearing or ripping of the sheet during the manufacturing process of the sheet and the compounding process of the sheet and the solid electrolyte, and higher toughness is preferable.

[0029] [Tensile elongation] The tensile elongation in the MD and CD directions of the wet-laid nonwoven fabric is preferably 8% or more. This tensile elongation is a numerical value that indicates the toughness of the sheet for supporting solid electrolytes. A certain level of toughness is necessary for the wet-laid nonwoven fabric in order to improve handling and durability under tension during the manufacturing process of the sheet for supporting solid electrolytes and the compounding process of the sheet and solid electrolyte, and the higher the toughness, the better.

[0030] [Solid Electrolyte Sheet] The present invention also relates to the above-mentioned sheet for supporting a solid electrolyte, and a solid electrolyte sheet comprising a solid electrolyte supported on its surface and inside. Examples of solid electrolytes include sulfide-based and oxide-based inorganic solid electrolytes, as well as polymer electrolytes. Methods for compounding these solid electrolytes into the solid electrolyte-supporting sheet of the present invention include coating, dipping, and compression molding.

[0031] [Manufacturing method] The wet nonwoven fabric for solid electrolyte support sheets of the present invention can be manufactured by heat treatment after papermaking using a conventional long-screen paper machine, short-screen paper machine, round-screen paper machine, or a combination of these machines for multi-layer papermaking.

[0032] A fiber slurry is prepared by stirring the raw fibers for the nonwoven fabric in a pulper for at least 5 minutes. Examples of equipment used for stirring the fibers include pulpers, refiners, beaters, and mills, with pulpers being preferred.

[0033] A nonwoven fabric is created using a wet papermaking method with the prepared fiber slurry. By heat-treating this nonwoven fabric, the binder fibers contained in the raw fibers bond the fibers together. This heat treatment can be performed using, for example, a Yankee dryer or an air-through dryer.

[0034] The heat treatment temperature is, for example, 80 to 200°C, and the duration is, for example, 10 to 600 seconds. After heat treatment, calendering may be performed using metal / metal rollers, metal / paper rollers, or metal / elastic rollers. When a wet-laid nonwoven fabric has a multilayer structure, after obtaining the wet-laid nonwoven fabric, multiple wet-laid nonwoven fabrics can be bonded together using a calender or the like.

[0035] A solid electrolyte sheet can be manufactured by supporting a solid electrolyte on the surface and inside the solid electrolyte-supporting sheet of the present invention using a conventional method. For example, a solid electrolyte sheet can be obtained by fixing the solid electrolyte-supporting sheet onto a glass plate, coating one side with a solid electrolyte slurry using a bar coater, and drying at 40-90°C for 10-30 minutes. [Examples]

[0036] The present invention will be described below with reference to examples. 1.Non-woven material The following fibers were used in the examples and comparative examples. • Polyester core-sheath composite binder fiber: Teijin Frontier Co., Ltd. "Tepilus TJ04CN SD 0.5dtex 5mm" (average fiber diameter 6.8μm, average fiber length 5.0mm) • Polyester core-sheath composite binder fiber: Teijin Frontier Co., Ltd. "Tepilus TJ04CN SD 1.1dtex 5mm" (average fiber diameter 10.1μm, average fiber length 5.0mm) • Undrawn polyester binder fiber: Teijin Frontier Co., Ltd.'s "Tepilus TK08PN SD 0.2dtex 3mm" (average fiber diameter 4.3μm, average fiber length 3.0mm) • Polyester non-binder fiber: Teijin Frontier Co., Ltd. "Tepils TA04PN SD 0.1dtex 3mm" (average fiber diameter 3.1μm, average fiber length 3.0mm) • Polyester non-binder fiber: Teijin Frontier Co., Ltd. "Tepils TA04PN SD 0.06dtex 3mm" (average fiber diameter 2.4μm, average fiber length 3.0mm)

[0037] 2. Preparation of solid electrolytes 175g of Ohara's "PW-01" as an oxide-based solid electrolyte and 30g of JSR's "TRD2001" as a binder were added to 295g of distilled water and stirred for 60 seconds using a household mixer. Then, 25g of BYK's "RHEOBYK-425" as a rheological agent was added, and the mixture was stirred at 300 rpm for 1 hour using a homodisperser to obtain a solid electrolyte slurry.

[0038] 3. Measurement and Evaluation Measurement and evaluation were performed by the following methods. (1) Fiber diameter and average fiber diameter Using a transmission electron microscope (TEM, with length measurement function), measurement was performed by taking photographs of fiber cross-sections at a magnification of 1,000 to 30,000 times. For the fiber diameter, the diameter of the circumscribed circle of the single fiber cross-section was used. The average value of n=5 was taken as the average fiber diameter. (2) Fiber length and average fiber length Fibers were placed on a substrate using a scanning electron microscope (SEM), and fiber length was measured at 10 to 500 times magnification. The length measurement function of the SEM was used to measure the fiber length. The average value of n=5 was taken as the average fiber length. (3) Basis weight Measurement was performed in accordance with JIS P8124 (Method for measuring the mass per unit area of paper). (4) Thickness Thickness was measured in accordance with JIS P8118 (Method for measuring thickness and density of paper and paperboard). Measurement was performed under a measurement load of 75g / cm 2 , and measurement was conducted with n=5. The average value was obtained and taken as the thickness. (5) Density Density was calculated from the basis weight and thickness using the following formula, where W is the basis weight (g / m 2 ) and L is the thickness (mm). Density (g / cm 3 )=(W / 10000) / (L / 10) (6) Porosity Porosity was calculated from the density of the nonwoven fabric and the resin density of the constituent fibers using the following formula, where D is the density (g / cm 3 ) and R is the resin density (g / cm 3 ). Here, R is the density of the polyester resin, and calculation was performed with R=1.36. Porosity (%)=100-{(D / R)×100} (7) Tensile strength and elongation The measurements were taken in accordance with JIS P8113 (Tensile strength and test methods for paper and cardboard). MD tensile strength is the tensile strength in the MD direction (average value measured with n=4), and CD tensile strength is the tensile strength in the CD direction (average value measured with n=4). MD tensile elongation is the tensile elongation in the MD direction (average value measured with n=4), and CD tensile elongation is the tensile elongation in the CD direction (average value measured with n=4). (8) Puncture strength and puncture strength-to-weight ratio Measurements were taken using the handheld compression tester "KES-G5" (manufactured by Kato Tech Co., Ltd.). A puncture test was performed with a needle tip radius of curvature of 0.5 mm and a puncture speed of 50 ± 5 mm / min, and the maximum puncture load was defined as the puncture strength (gf). Measurements were taken with a sample size of 3, and the average value was calculated and defined as the puncture strength (gf). The obtained puncture strength (gf) and the basis weight (g / m²) of the nonwoven fabric were compared. 2 From ), the puncture strength-to-weight ratio (gf / (g / m) is calculated using the following formula. 2 The following was calculated: P is the puncture strength (gf), and W is the basis weight (g / m). 2 ) Piercing strength weight ratio (gf / (g / m 2 ))=P / W (9) Paint retention ratio The basis weight of the solid electrolyte sheet and the nonwoven fabric were calculated using the following formula. Here, Wn is the basis weight of the nonwoven fabric (g / m²). 2 ), Ws is the basis weight (g / m²) of the solid electrolyte sheet. 2 ) Paint retention ratio=(Ws-Wn) / Wn

[0039] [Example 1] As shown in Table 1, the nonwoven fabric was constructed using 70% by weight of the above-mentioned polyester core-sheath composite binder fibers (average fiber diameter 6.8 μm, average fiber length 5.0 mm, "Tepilus TJ04CN SD 0.5 dtex 5 mm" manufactured by Teijin Frontier Co., Ltd.) as binder fibers, and 30% by weight of the above-mentioned polyester non-binder fibers (average fiber diameter 2.4 μm, average fiber length 3.0 mm, "Tepilus TA04PN SD 0.06 dtex 3 mm" manufactured by Teijin Frontier Co., Ltd.) as non-binder fibers. The mixture was stirred in a pulper for 5 minutes to prepare a fiber slurry.

[0040] Using this fiber slurry, a nonwoven fabric was prepared by a wet papermaking method. This was then transferred to a Yankee dryer at a linear pressure of 0.3 kg / cm and dried at 120°C for 30 seconds to adjust the basis weight and thickness to obtain a wet nonwoven fabric sheet for supporting solid electrolytes. Furthermore, a solid electrolyte support sheet was fixed onto a glass plate, a solid electrolyte slurry was coated onto one side using a bar coater, and dried at 80°C for 5 minutes to create a solid electrolyte sheet. The evaluation results are shown in Table 2.

[0041] The resulting solid electrolyte support sheet has a basis weight of 5.3 g / m². 2 It is lightweight and has a high porosity of 87.7%, yet its puncture strength-to-weight ratio is 11.5 gf / (g / m²). 2 ) resulted in excellent puncture resistance. Thus, because it has high voids yet high puncture resistance, the solid electrolyte can penetrate the interior, resulting in excellent paint retention ratio of the solid electrolyte sheet after coating, and also excellent puncture resistance of the solid electrolyte sheet.

[0042] [Example 2] As shown in Table 1, the constituent fibers of the nonwoven fabric were 50% by weight of the above-mentioned polyester core-sheath composite binder fibers (average fiber diameter 6.8 μm, average fiber length 5.0 mm, "Tepilus TJ04CN SD 0.5 dtex 5 mm" manufactured by Teijin Frontier Co., Ltd.) as binder fibers, and 50% by weight of the above-mentioned polyester non-binder fibers (average fiber diameter 2.4 μm, average fiber length 3.0 mm, "Tepilus TA04PN SD 0.06 dtex 3 mm" manufactured by Teijin Frontier Co., Ltd.) as non-binder fibers. Wet-laid nonwoven fabrics were prepared in the same manner as in Example 1, with the basis weight and thickness changed as shown in Table 2. The basis weight was adjusted by adjusting the amount of fiber slurry supplied. The thickness was adjusted by adjusting the pressure of the roll press after the Yankee dryer.

[0043] Furthermore, a solid electrolyte sheet was prepared using the same method as in Example 1. The evaluation results are shown in Table 2. Similar to Example 1, the nonwoven fabric was lightweight and had high porosity, while exhibiting excellent puncture strength-to-weight ratio. Also, similar to Example 1, the solid electrolyte sheet exhibited excellent paint retention and puncture strength.

[0044] [Example 3] As shown in Table 1, the constituent fibers of the nonwoven fabric were 100% by weight of the aforementioned polyester core-sheath composite binder fibers (average fiber diameter 6.8 μm, average fiber length 5.0 mm, "Tepilus TJ04CN SD 0.5dtex 5 mm" manufactured by Teijin Frontier Co., Ltd.) as binder fibers. Wet-laid nonwoven fabrics were prepared in the same manner as in Example 1, with the basis weight and thickness changed as shown in Table 2. The basis weight was adjusted by adjusting the amount of fiber slurry supplied. The thickness was adjusted by adjusting the pressure of the roll press after the Yankee dryer.

[0045] Furthermore, a solid electrolyte sheet was prepared using the same method as in Example 1. The evaluation results are shown in Table 2. Similar to Example 1, the nonwoven fabric was lightweight and had high porosity, while exhibiting excellent puncture strength-to-weight ratio. Also, similar to Example 1, the solid electrolyte sheet exhibited excellent paint retention and puncture strength.

[0046] [Example 4] As shown in Table 1, the constituent fibers of the nonwoven fabric were 100% by weight of the aforementioned polyester core-sheath composite binder fibers (average fiber diameter 6.8 μm, average fiber length 5.0 mm, "Tepilus TJ04CN SD 0.5dtex 5 mm" manufactured by Teijin Frontier Co., Ltd.) as binder fibers. Wet-laid nonwoven fabrics were prepared in the same manner as in Example 1, with the basis weight and thickness changed as shown in Table 2. The basis weight was adjusted by adjusting the amount of fiber slurry supplied. The thickness was adjusted by adjusting the pressure of the roll press after the Yankee dryer.

[0047] Furthermore, a solid electrolyte sheet was prepared using the same method as in Example 1. The evaluation results are shown in Table 2. Similar to Example 1, the nonwoven fabric was lightweight and had high porosity, while exhibiting excellent puncture strength-to-weight ratio. Also, similar to Example 1, the solid electrolyte sheet exhibited excellent paint retention and puncture strength.

[0048] [Comparative Example 1] As shown in Table 1, the constituent fibers of the nonwoven fabric were 50% by weight of the above-mentioned undrawn polyester binder fibers (average fiber diameter 4.3 μm, average fiber length 3.0 mm, "Tepilus TK08PN SD 0.2 dtex 3 mm" manufactured by Teijin Frontier Co., Ltd.) as binder fibers, and 50% by weight of the above-mentioned non-binder polyester fibers (average fiber diameter 3.1 μm, average fiber length 3.0 mm, "Tepilus TA04PN SD 0.1 dtex 3 mm" manufactured by Teijin Frontier Co., Ltd.) as non-binder fibers. Wet-laid nonwoven fabrics were prepared in the same manner as in Example 1, with the basis weight and thickness changed as shown in Table 2. At this time, the basis weight was adjusted by adjusting the amount of fiber slurry supplied. The thickness was adjusted by adjusting the pressure of the roll press after the Yankee dryer.

[0049] Furthermore, a solid electrolyte sheet was prepared using the same method as in Example 1. The evaluation results are shown in Table 2. In this example, the binder fibers constituting the nonwoven fabric were unstretched binder fibers. The obtained solid electrolyte sheet had low puncture strength.

[0050] [Comparative Example 2] As shown in Table 1, the nonwoven fabric was prepared using the same composition and method as in Comparative Example 1. Furthermore, a wet-laid nonwoven sheet for supporting solid electrolytes was obtained by calendering at 150°C at 50 kg / cm². A solid electrolyte sheet was then prepared using the same method as in Example 1. The evaluation results are shown in Table 2.

[0051] In this example, the binder fibers constituting the nonwoven fabric were undrawn binder fibers, and the nonwoven fabric had a low porosity due to calendering. The resulting solid electrolyte sheet had low puncture strength and a low paint retention ratio of the solid electrolyte.

[0052] [Comparative Example 3] As shown in Table 1, the constituent fibers of the nonwoven fabric were 100% by weight of the aforementioned undrawn polyester binder fibers (average fiber diameter 4.3 μm, average fiber length 3.0 mm, "Tepilus TK08PN SD 0.2 dtex 3 mm" manufactured by Teijin Frontier Co., Ltd.) as binder fibers. Wet-laid nonwoven fabrics were prepared in the same manner as in Example 1, with the basis weight and thickness changed as shown in Table 2. The basis weight was adjusted by adjusting the amount of fiber slurry supplied. The thickness was adjusted by adjusting the pressure of the roll press after the Yankee dryer.

[0053] Furthermore, a solid electrolyte sheet was prepared using the same method as in Example 1. The evaluation results are shown in Table 2. In this example, the binder fiber species constituting the nonwoven fabric was undrawn binder fiber. The obtained solid electrolyte sheet had low puncture strength.

[0054] [Comparative Example 4] As shown in Table 1, the constituent fibers of the nonwoven fabric were 70% by weight of the above-mentioned polyester core-sheath composite binder fiber (average fiber diameter 6.8 μm, average fiber length 5.0 mm, manufactured by Teijin Frontier Co., Ltd., "Tepilus TJ04CN SD 0.5dtex 5mm") as the binder fiber, and 30% by weight of the above-mentioned polyester non-binder fiber (average fiber diameter 2.4 μm, average fiber length 3.0 mm, manufactured by Teijin Frontier Co., Ltd., "Tepilus TA04PN SD 0.06dtex 3mm") as the non-binder fiber, and a wet-laid nonwoven fabric was prepared in the same manner as in Example 1. Furthermore, a wet-laid nonwoven sheet for supporting solid electrolytes was obtained by calendering at 150°C at 50 kg / cm.

[0055] Furthermore, a solid electrolyte sheet was prepared using the same method as in Example 1. The evaluation results are shown in Table 2. Due to the calendering process, the porosity was low, and the paint retention ratio of the solid electrolyte sheet was also low.

[0056] [Comparative Example 5] As shown in Table 1, the constituent fibers of the nonwoven fabric were 20% by weight of the above-mentioned polyester core-sheath composite binder fibers (average fiber diameter 6.8 μm, average fiber length 5.0 mm, Teijin Frontier's "Tepilus TJ04CN SD 0.5 dtex 5 mm") as binder fibers and 80% by weight of the above-mentioned polyester fibers (average fiber diameter 2.4 μm, average fiber length 3.0 mm, Teijin Frontier's "Tepilus TA04PN SD 0.06 dtex 3 mm") as non-binder fibers, and a wet-laid nonwoven fabric was prepared in the same manner as in Example 1. At this time, the basis weight was adjusted by adjusting the amount of fiber slurry supplied. The thickness was adjusted by adjusting the pressure of the roll press after the Yankee dryer.

[0057] Furthermore, a solid electrolyte sheet was prepared using the same method as in Example 1. The evaluation results are shown in Table 2. In this example, the weight ratio of polyester core-sheath composite binder fibers, which constitute the nonwoven fabric, was low at 20% by weight, resulting in a low puncture strength weight ratio. The resulting solid electrolyte sheet had low puncture strength.

[0058] [Comparative Example 6] As shown in Table 1, the constituent fibers of the nonwoven fabric were 100% by weight of the aforementioned polyester core-sheath composite binder fibers (average fiber diameter 6.8 μm, average fiber length 5.0 mm, "Tepilus TJ04CN SD 0.5dtex 5 mm" manufactured by Teijin Frontier Co., Ltd.) as binder fibers, and a wet-laid nonwoven fabric was prepared in the same manner as in Example 1. At this time, the basis weight was adjusted by adjusting the amount of fiber slurry supplied. The thickness was adjusted by adjusting the pressure of the roll press after the Yankee dryer.

[0059] Furthermore, a solid electrolyte sheet was prepared using the same method as in Example 1. The evaluation results are shown in Table 2. The obtained solid electrolyte-supporting sheet had a basis weight of 1.9 g / m².2 Because it was lightweight, the solid electrolyte sheet had weak puncture resistance.

[0060] [Comparative Example 7] As shown in Table 1, the constituent fibers of the nonwoven fabric were 100% by weight of the aforementioned polyester core-sheath composite binder fibers (average fiber diameter 10.1 μm, average fiber length 5.0 mm, "Tepilus TJ04CN SD 1.1dtex 5 mm" manufactured by Teijin Frontier Co., Ltd.) as binder fibers, and a wet-laid nonwoven fabric was prepared in the same manner as in Example 1. At this time, the basis weight was adjusted by adjusting the amount of fiber slurry supplied. The thickness was adjusted by adjusting the pressure of the roll press after the Yankee dryer.

[0061] Furthermore, a solid electrolyte sheet was prepared using the same method as in Example 1. The evaluation results are shown in Table 2. The obtained solid electrolyte-supporting sheet had a large fiber diameter and a small fiber network, resulting in a lot of paint seepage and a low paint retention ratio for the solid electrolyte sheet.

[0062] [Table 1]

[0063] [Table 2] [Industrial applicability]

[0064] The solid electrolyte support sheet of the present invention can be used as a battery component. According to the present invention, by using a wet nonwoven fabric that is lightweight, has high voids, and has excellent puncture strength, the puncture strength of the solid electrolyte layer can be improved when a solid electrolyte is supported on it.

Claims

1. A sheet for carrying solid electrolytes, comprising a wet-laid nonwoven fabric containing polyester core-sheath composite binder fibers, wherein the wet-laid nonwoven fabric has a basis weight of 3 to 8 g / m². ２ The porosity is 60% or more, and the puncture strength-to-weight ratio is 8 gf / (g / m²). ２ A sheet for supporting solid electrolytes, characterized by being ) or more.

2. The sheet for supporting solid electrolytes according to claim 1, wherein polyester core-sheath composite binder fibers account for 30 to 100% by weight of the wet-laid nonwoven fabric.

3. The sheet for supporting a solid electrolyte according to claim 1, wherein polyester non-binder fibers constitute 0 to 70% by weight of the wet nonwoven fabric.

4. The sheet for supporting solid electrolytes according to claim 1, wherein the average fiber diameter of the polyester core-sheath composite binder fibers is 1 to 9 μm.

5. A solid electrolyte sheet according to any one of claims 1 to 4, comprising a solid electrolyte supporting sheet according to claim 1, and a solid electrolyte supported on its surface and inside.

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