JP2016139482A - Solid electrolyte sheet and all-solid secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolyte sheet capable of improving battery performance by reducing battery impedance, and an all-solid secondary battery.SOLUTION: A solid electrolyte sheet of the present invention includes a nonwoven fabric having an opening portion and a solid electrolyte provided to the surface and opening portion of the nonwoven fabric. The average particle size of the solid electrolyte is smaller than the intermediate value of an opening width at the opening portion of the nonwoven fabric.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a solid electrolyte sheet and an all-solid-state secondary battery including the solid electrolyte sheet.

  Conventionally, a lithium battery using a solid electrolyte is known as an all-solid secondary battery. This lithium battery includes a solid electrolyte layer, a positive electrode active material layer and a negative electrode active material layer, and a current collector bonded to each active material layer.

  The solid electrolyte layer has a function of conducting lithium ions and a function of a separator that prevents a short circuit between the negative electrode active material layer and the positive electrode active material layer, and should be formed as thin as possible to improve the energy density. Is preferred. However, since it is difficult to make a solid electrolyte thin film self-supporting, a method in which a solid electrolyte is applied to a substrate having an opening to produce a solid electrolyte layer is employed.

  For example, it is formed on a base material (nonwoven fabric) made of a porous film and at least one surface of the base material, and contains particles and a resin material. The arithmetic average roughness Sa of the surface is 1.0 μm or more and 4.0 μm or less. A combination of a separator for a nonaqueous electrolyte battery provided with a porous surface layer having a concavo-convex shape and a solid electrolyte has been proposed (for example, see Patent Document 1).

JP 2013-137984 A

  However, in the separator described in Patent Document 1, a binder is used to apply inorganic particles having an average particle size of 1 μm to the surface of the separator, so that the average particle size of the inorganic particles is 5 times or more (that is, Since the surface layer having a thickness of 5 μm or more is formed, the distance between the fibers (opening width) in the opening portion of the nonwoven fabric cannot be sufficiently ensured. Therefore, when such a separator is used, it becomes difficult to ensure lithium ion conductivity by the solid electrolyte, so that the resistance component (impedance) in the battery cell becomes very high, resulting in battery performance. There was a problem that decreased.

  Therefore, the present invention has been made in view of the above-described problems, and provides a solid electrolyte sheet and an all-solid secondary battery that can reduce battery impedance and improve battery performance. Objective.

  In order to achieve the above object, a solid electrolyte sheet of the present invention is a solid electrolyte sheet comprising a nonwoven fabric having openings, and a solid electrolyte provided on the surface of the nonwoven fabric and the openings, and the average particle of the solid electrolyte A diameter is smaller than the intermediate value of the opening width in the opening part of a nonwoven fabric, It is characterized by the above-mentioned.

  ADVANTAGE OF THE INVENTION According to this invention, the solid electrolyte sheet which can suppress a raise of an impedance and can improve battery performance can be provided. Moreover, the all-solid-state secondary battery excellent in battery performance can be provided by utilizing this fixed electrolyte sheet.

It is sectional drawing of the all-solid-state secondary battery which concerns on embodiment of this invention. It is a schematic diagram for demonstrating the solid electrolyte sheet in the all-solid-state secondary battery which concerns on embodiment of this invention. It is AA sectional drawing of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

  FIG. 1 is a cross-sectional view of an all solid state secondary battery according to an embodiment of the present invention, and FIG. 2 is a schematic diagram for explaining a solid electrolyte sheet in the all solid state secondary battery according to an embodiment of the present invention. is there. FIG. 3 is a cross-sectional view taken along the line AA in FIG.

  The all-solid-state secondary battery 1 includes a positive electrode current collecting member 2, a positive electrode active material layer 3, a solid electrolyte sheet 4, a negative electrode active material layer 5, and a negative electrode current collecting member 6.

  The positive electrode current collecting member 2 may be any material as long as it is a conductor. For example, the positive electrode current collecting member 2 is made of aluminum, stainless steel, nickel-plated steel, or the like.

  The positive electrode active material layer 3 includes a solid electrolyte, a positive electrode active material, a positive electrode layer conductive material (conductive aid), and a positive electrode layer binder.

  Examples of the solid electrolyte include a sulfide-based solid electrolyte and an oxide-based solid electrolyte.

The sulfide-based solid electrolyte is synthesized by at least one compound selected from the group consisting of silicon sulfide, phosphorus sulfide and boron sulfide as the second component, and at least lithium sulfide as the first component, Li ₂ S—P ₂ S ₅ is preferred.

This sulfide-based solid electrolyte is known to have higher lithium ion conductivity than other inorganic compounds. In addition to Li ₂ S—P ₂ S ₅ , SiS ₂ , GeS ₂ , B ₂ S _3, etc. The sulfide may be contained. Further, as the solid electrolyte, an inorganic solid electrolyte to which Li ₃ PO ₄ , halogen, a halogen compound or the like is appropriately added may be used.

A sulfide-based solid electrolyte is obtained by heating Li ₂ S and P ₂ S ₅ to a melting temperature or higher, melting and mixing them at a predetermined ratio, holding them for a predetermined time, and then rapidly cooling them. (Melting and quenching method).

The predetermined time for the heat treatment is preferably 0.1 hour or longer, and it is poured into liquid nitrogen and rapidly cooled to obtain a target vitrified inorganic solid electrolyte. Alternatively, a method of vacuum-sealing in a glass tube, heating and melting it, and then rapidly cooling with ice water or the like may be employed. It can also be obtained by treating Li ₂ S—P ₂ S ₅ by a mechanical milling method.

The compounds containing said elements, in a molar ratio of the Li ₂ S and _P 2 _{S 5,} preferably 50: obtained by mixing at 25: 50-80: 20, more preferably 60: 40 to 75 Examples include sulfides.

The oxide-based solid electrolyte, for _{example, Li 3 N, LISICON, LIPON} (Li 3 + y PO 4-x N x), Thio-LISICON (Li 3. 25 Ge 0.25 P 0.75 S 4), Li 2 O _{-Al 2 O 3 -TiO 2 -P 2} O 5 is (LATP).

The solid electrolyte has a structure such as amorphous, glassy, crystal (crystallized glass). When the solid electrolyte is a sulfide-based solid electrolyte made of Li ₂ S—P ₂ S ₅ , the lithium ion conductivity of the amorphous body is 10 ⁻⁴ Scm ⁻¹ . On the other hand, the lithium ion conductivity of the crystalline material is 10 ⁻³ Scm ⁻¹ .

  Further, the above-described solid electrolyte used in the positive electrode active material layer 3 is also used in the solid electrolyte sheet 4 and the negative electrode active material layer 5. The solid electrolyte in each of the positive electrode active material layer 3, the solid electrolyte sheet 4, and the negative electrode active material layer 5 is composed of, for example, a mixture of an amorphous material and a crystal material. The amorphous body is produced by mixing the first component and the second component of the sulfide described above and processing the mixture by a mechanical milling method. The crystalline body is produced, for example, by baking an amorphous body.

  The positive electrode active material is not particularly limited as long as it is a material capable of reversibly occluding and releasing lithium ions. For example, lithium cobalt oxide (LCO), lithium nickelate, lithium nickel cobaltate, nickel cobalt aluminum Lithium oxide (hereinafter also referred to as “NCA”), nickel cobalt lithium manganate (hereinafter also referred to as “NCM”), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, Examples include sulfur, iron oxide, and vanadium oxide. These positive electrode active materials may be used independently and 2 or more types may be used together.

  The positive electrode active material is preferably a lithium salt of a transition metal oxide having a layered rock salt structure, among the positive electrode active materials listed above. Here, “layered” means a thin sheet-like shape. The “rock salt type structure” is a sodium chloride type structure, which is a kind of crystal structure, in which the face-centered cubic lattice formed by each of the cation and the anion is 1 / of the edge of the unit cell. Refers to a structure shifted by two.

As a lithium salt of a transition metal oxide having such a layered rock salt structure, for example, Li _1.1-x Ni _y Co _z Al _1-yz O ₂ (NCA) or Li _1.1-x Transition of the ternary system represented by Ni _y Co _z Mn _1-yz O ₂ (NCM) (0 <x <0.6, 0 <y <1, 0 <z <1, and y + z <1) Examples thereof include lithium salts of metal oxides.

  The positive electrode layer conductive material is added to form a conductive network between the positive electrode active materials to reduce the impedance of the positive electrode active material layer. The conductive auxiliary agent may be used in an appropriate amount in the positive electrode active material layer. For example, carbon black such as ketjen black and acetylene black, graphite, natural graphite, artificial graphite, carbon nanotube, and carbon nanofiber may be used. However, it is not particularly limited as long as it is for increasing the conductivity of the positive electrode layer 3, and may be used alone or in combination.

  Examples of the binder include styrene thermoplastic elastomers such as SBS (styrene butadiene block polymer), SEBS (styrene ethylene butadiene styrene block polymer), and styrene-styrene butadiene-styrene block polymer, SBR (styrene butadiene). Rubber), BR (butadiene rubber), NR (natural rubber), IR (isoprene rubber), EPDM (ethylene-propylene-diene terpolymer), NBR (nitrile rubber), CR (chloroprene rubber), and these Partially hydrogenated or fully hydrogenated, polyacrylic acid ester copolymer, PVDF (polyvinylidene fluoride), VDF-HFP (vinylidene fluoride-hexafluoropropylene copolymer), and their carboxylic acid modification , CM (chlorination Polyethylene), polymethacrylic acid ester, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyimide, polyamide, polyamideimide and the like. Other examples include polystyrene, polyolefin, olefinic thermoplastic elastomer, polycycloolefin, and silicone resin.

  The ratio of the solid electrolyte, the positive electrode active material, the positive electrode layer conductive material, and the positive electrode layer binder content in the positive electrode active material layer 3 is not particularly limited. For example, the solid electrolyte is 5 to 50% by mass with respect to the total mass of the positive electrode active material layer 3, the positive electrode active material is 45 to 95% by mass with respect to the total mass of the positive electrode material layer 3, and the positive electrode layer conductive material is positive electrode active. 1-10 mass% with respect to the total mass of the material layer 3, and a positive electrode layer binder is 0.5-4 mass% with respect to the total mass of the positive electrode active material layer 3. FIG.

  As shown in FIGS. 2 and 3, the solid electrolyte sheet 4 includes an opening 12, a nonwoven fabric 8 that functions as a support, and a solid electrolyte 11 provided on the surface of the nonwoven fabric 8 and the opening 12. ing. And the solid electrolyte 11 is contained with the electrolyte binder inside the nonwoven fabric 8, As mentioned later, it produces as a self-supporting solid electrolyte sheet.

As the solid electrolyte 11, the solid electrolyte described in the positive electrode current collector 2 can be used. Among these, from the viewpoint that lithium ion conductivity is excellent, Li ₂ S— which is a sulfide-based solid electrolyte is used. It is preferable to use an amorphous powder of P ₂ S ₅ (the molar ratio of Li ₂ S to P ₂ S ₅ is 80:20 mol%).

  In addition, regarding the binder in the solid electrolyte sheet 4, the ratio of the contents of the solid electrolyte 11 and the electrolyte binder is not particularly limited. For example, the solid electrolyte 11 is set to 95 to 99% by mass with respect to the total mass of the solid electrolyte sheet 4, and the electrolyte binder is set to 0.5 to 5% by mass with respect to the total mass of the solid electrolyte sheet 4. Can do.

  In particular, since the sulfide-based solid electrolyte has high reactivity, the solid electrolyte binder is preferably a nonpolar resin having no polar functional group, and has the same binding as the positive electrode active material binder described above. It is preferable to include a dressing.

  In the present invention, the non-woven fabric 8 is not particularly limited, and it is possible to use glass or resin fibers that are randomly laid and entangled without being woven, and made into a sheet by adhesive or pressure bonding.

  The nonwoven fabric fiber 10 used for the nonwoven fabric 8 is not particularly limited as long as it does not adversely affect the solid electrolyte 11 and is a fiber having insulating properties and flexibility. For example, polyethylene terephthalate fiber, nylon fiber, aramid fiber, glass fiber and the like can be used.

  Moreover, the thickness of the nonwoven fabric 8 is preferably 10 μm or more and 25 μm or less. Since the solid electrolyte sheet 4 having a sufficient thickness can be produced by setting the thickness to 10 μm or more, the self-supporting property of the solid electrolyte sheet 4 can be ensured. Further, by setting the thickness of the nonwoven fabric 8 to 25 μm or less, the solid electrolyte 11 is included in the surface and inside of the nonwoven fabric 8 so that the solid electrolyte 11 is distributed also inside the nonwoven fabric 8 and penetrates to the back. Therefore, impedance can be suppressed and a decrease in discharge capacity can be suppressed.

  Moreover, the solid electrolyte sheet 4 of this invention is produced by apply | coating the coating liquid containing the solid electrolyte 11 to the surface of the nonwoven fabric 8 installed on the base material, and making it dry. Thereby, after a coating liquid is dried, the self-supporting solid electrolyte sheet is produced by peeling the nonwoven fabric 8 from a base material.

  In addition, as a base material of the nonwoven fabric 8, if it does not melt | dissolve in the solvent (xylene etc.) used for the coating liquid of the solid electrolyte 11, such as metal foil, a glass plate, a polyethylene terephthalate film, it will not specifically limit.

  Here, the present invention is characterized in that the average particle diameter of the solid electrolyte 11 is smaller than the intermediate value of the opening width in the opening 12 of the nonwoven fabric 8.

  With such a configuration, as shown in FIG. 3, when the solid electrolyte sheet 4 is produced, the solid electrolyte 11 passes between the nonwoven fabric fibers 10 constituting the nonwoven fabric 8, and the front and back surfaces of the nonwoven fabric 8 (that is, solids). Since it is distributed on the front surface 4a and the back surface 4b) of the electrolyte sheet 4, many ion paths are formed.

  As a result, since the impedance of the solid electrolyte sheet 4 can be reduced, the performance of the all-solid secondary battery 1 can be improved.

  The “average particle size” as used herein refers to a 50% particle size (D50) and can be measured by a laser diffraction / scattering particle size distribution measuring device (for example, Microtrack MT-3000II manufactured by Nikkiso Co., Ltd.). .

  Further, “the opening width D in the opening 12 of the nonwoven fabric 8” means “the distance between the nonwoven fabric fibers 10 in the opening 12 of the nonwoven fabric 8”, and “the intermediate value M of the opening width D” (see FIG. 3). ) Means “a value that is located in the center when a plurality of opening widths D are arranged in ascending order”.

  Further, as described above, since the nonwoven fabric 8 of the present invention is one in which fibers are laid randomly, the distribution of the opening width D is a woven fabric in which the nonwoven fabric fibers 10 are regularly woven or holes are formed by patterning. Compared with the distribution of the size of the opening width of the sheet, it has a feature that it becomes larger.

  The intermediate value of the opening width D is preferably 0.01 μm to 100 μm, more preferably 0.1 μm to 20 μm, and particularly preferably 1 μm to 10 μm. This is because when the intermediate value of the opening width D is smaller than 0.01 μm, the contact between the solid electrolytes 11 is insufficient, and the ion path may not be sufficiently formed, and when it is larger than 100 μm. This is because the solid electrolyte 11 may not be supported by the nonwoven fabric fiber 10.

  The average particle diameter of the solid electrolyte 11 is preferably 0.01 μm to 50 μm, more preferably 0.05 μm to 20 μm, and particularly preferably 0.1 μm to 10 μm. This is because when the average particle diameter is smaller than 0.01 μm, it may be difficult to produce the solid electrolyte 11. When the average particle diameter is larger than 50 μm, the layer of the solid electrolyte 11 becomes thick, This is because the weight energy density may decrease.

  The negative electrode active material layer 5 includes a negative electrode active material, a negative electrode active material layer binder, and the solid electrolyte described above. As the negative electrode active material layer binder, the same binder as the positive electrode active material layer binder described above can be used.

  As the negative electrode active material, graphite-based active material graphite such as artificial graphite, natural graphite, a mixture of artificial graphite and natural graphite, natural graphite coated with artificial graphite, or metallic lithium, silicon alloy, tin alloy, etc. is used. can do. Note that the graphite powder may be at least partially coated with an inorganic compound, metal, or the like.

  The ratio of the content of the negative electrode active material, the solid electrolyte, and the negative electrode binder is not particularly limited. For example, the sulfide-based solid electrolyte is 0 to 40% by mass with respect to the total mass of the negative electrode active material layer 6, the negative electrode binder is 60 to 100% by mass with respect to the total mass of the negative electrode active material layer 6, and the first The binder may contain 0.5 to 5 wt% with respect to the total mass of the negative electrode active material layer 6.

  As long as the negative electrode current collection member 6 is a conductor, what kind of thing may be sufficient, for example, it is comprised with copper, stainless steel, nickel plating steel, etc. In addition, you may add a well-known additive etc. to said each layer suitably.

  Hereinafter, the present invention will be described based on examples. In addition, this invention is not limited to these Examples, These Examples can be changed and changed based on the meaning of this invention, and they are excluded from the scope of the present invention. is not.

Example 1
(Preparation of positive electrode structure)
LiNiCoAlO ₂ ternary powder as a positive electrode active material, Li ₂ S—P ₂ S ₅ (80-20 mol%) amorphous powder as a sulfide-based solid electrolyte, and carbon as a positive electrode active material layer conductive material The conductive assistant composed of fibers was weighed so as to have a mass% ratio of 60/35/5, and mixed using a rotation and revolution mixer.

  Next, to this mixed powder, a dehydrated xylene solution in which SBR as a binder was dissolved was added so that the SBR was 5.0% by mass with respect to the total mass of the mixed powder to produce a primary mixed liquid. . Furthermore, a secondary mixed solution was generated by adding an appropriate amount of dehydrated xylene for viscosity adjustment to the primary mixed solution.

  Next, in order to improve the dispersibility of the mixed powder, a zirconia ball having a diameter of 5 mm is mixed with the secondary mixed liquid so that the space, the mixed powder, and the zirconia ball each occupy 1/3 of the total volume of the kneading container. It was thrown into. And the produced | generated tertiary mixed liquid was thrown into the rotation-revolution mixer, and the positive electrode coating liquid was produced | generated by stirring at 3000 rpm for 3 minutes.

  Next, an aluminum foil current collector having a thickness of 15 μm is prepared as a positive electrode current collecting member, the positive electrode current collecting member is placed on a desktop screen printing machine, and the positive electrode coating liquid is sheeted using a metal mask having a thickness of 150 μm. Coated on top. Thereafter, the sheet coated with the positive electrode coating solution was dried on a hot plate at 60 degrees Celsius for 30 minutes, and then vacuum dried at 80 ° C. for 12 hours. Thereby, the positive electrode active material layer was formed on the positive electrode current collector. The total thickness of the positive electrode current collector and the positive electrode active material layer after drying was about 165 μm. Further, the density per area of the positive electrode active material layer was 15 mg per square centimeter.

  A sheet composed of the positive electrode current collecting member and the positive electrode active material layer was rolled using a roll press with a roll gap of 10 μm to produce a positive electrode structure. The thickness of the positive electrode structure was about 120 μm.

(Preparation of negative electrode structure)
Graphite powder as a negative electrode active material (vacuum dried at 80 ° C. for 24 hours) and PVdF as a binder were weighed in a mass ratio of 95: 5. Then, these materials and an appropriate amount of NMP were put into a rotation and revolution mixer, stirred at 3000 rpm for 3 minutes, and then defoamed for 1 minute to produce a negative electrode coating solution.

  A copper foil current collecting member having a thickness of 16 μm was prepared as a negative electrode current collecting member, and a negative electrode coating solution was applied onto the copper foil current collecting member using a blade. The thickness (gap) of the negative electrode coating solution on the copper foil current collector was about 150 μm. The sheet coated with the negative electrode coating solution was stored in a dryer heated to 80 degrees Celsius and dried for 15 minutes. Further, the dried sheet was vacuum dried at 80 ° C. for 24 hours. A sheet composed of the negative electrode current collector and the negative electrode was rolled using a roll press with a roll gap of 10 μm to produce a negative electrode structure. The thickness of the negative electrode structure was about 140 μm. The density per area of the negative electrode active material layer was 15 mg per square centimeter.

(Preparation of electrolyte coating solution)
The _{Li 2 S-P 2 S 5} (80:20 mol%) amorphous powder as a sulfide-based solid electrolyte, SBR weight xylene solution SBR is amorphous powder (electrolyte layer binder) to The primary mixed solution was adjusted by adding so as to be 1% by mass. Furthermore, a secondary mixed solution is prepared by adding a xylene solution of NBR (electrolyte layer binder) to this mixed solution so that NBR is 0.5% by mass with respect to the mass of the amorphous powder. did. Furthermore, an appropriate amount of dehydrated xylene for viscosity adjustment was added to this secondary mixture to produce a tertiary mixture. Furthermore, in order to improve the dispersibility of the mixed powder, a zirconia ball having a diameter of 5 mm is changed into a tertiary mixed liquid so that the space, the mixed powder, and the zirconia ball each occupy 1/3 of the total volume of the kneading container. I put it in. The quaternary mixed solution thus produced was put into a rotation and revolution mixer, and stirred at 3000 rpm for 3 minutes to produce an electrolyte layer coating solution. The average particle size of the solid electrolyte used was 5 μm.

(Preparation of solid electrolyte sheet)
Next, a 200 mm × 200 mm polyethylene terephthalate (PET) film is placed on a desktop screen printing machine, and a nonwoven fabric having a thickness of 10 μm and 190 mm × 190 mm is placed thereon, on which a thickness of 150 μm and an opening is 90 mm × 60 mm. The electrolyte layer coating solution was applied using a metal mask.

  The nonwoven fabric was produced by forming a sheet of polyethylene terephthalate fiber having a fiber diameter in the range of 0.1 to 0.2 dtex by a wet papermaking method. Moreover, when the intermediate value of the opening width in the opening part of a nonwoven fabric was measured by performing image processing of the used nonwoven fabric, it was 10 micrometers. Moreover, the thickness of the nonwoven fabric was 10 micrometers.

  Next, the PET film coated with the electrolyte layer coating solution was dried on a hot plate at 40 ° C. for 10 minutes and then vacuum dried at 40 ° C. for 12 hours. Then, the nonwoven fabric and the solid electrolyte were simultaneously peeled from the PET film and punched with a Thomson blade to obtain a 92 mm × 62 mm solid electrolyte sheet in which the solid electrolyte and the nonwoven fabric were integrated. The thickness of the solid electrolyte sheet after drying was about 180 μm.

(Production of solid battery)
First, the prepared negative electrode structure and positive electrode structure were punched with a Thomson blade. More specifically, the negative electrode structure was punched to a size of 88 mm × 58 mm, and the positive electrode structure was punched to a size of 87 mm × 57 mm.

  Next, after laminating the negative electrode structure-solid electrolyte sheet-positive electrode structure in this order, they are bonded together by a dry lamination method using a roll press machine with a roll gap of 50 μm, so that a single cell of a solid battery (single battery) ) Was generated.

  In addition, when the solid electrolyte part of the solid electrolyte sheet is made larger in the planar direction than the size of the negative electrode structure / positive electrode structure, the negative electrode structure-solid electrolyte sheet-positive electrode structure is pressed. It was possible to prevent the negative electrode structure and the positive electrode structure from being short-circuited at the end face of the single cell.

(Impedance measurement)
Next, the produced single cell was put into an aluminum laminate film to which a terminal was attached, and evacuated with a vacuum machine, heat sealed, and packed. The obtained test cell was charged to 4.0 V at a current density of 0.1 mA / cm ² (0.1 C) in an environment of 25 ° C., and the impedance value was measured using an LCZ meter (Yokogawa Hewlett-Packard Company). And manufactured at an AC frequency of 0.1 Hz to 1 MHz.

  Then, the arc portion of the obtained Cole-Cole plot is curve-fitted into a semicircle shape with the X axis as the base, and the numerical value at the intersection of the right end of the semicircle and the X axis is used as the impedance value of the test cell. Recorded. The results are shown in Table 1.

(Example 2)
As described above, except that Li ₂ S—P ₂ S ₅ (Molar ratio of Li ₂ S to P ₂ S ₅ is 80:20 mol%) amorphous powder having an average particle diameter of 3 μm was used as the solid electrolyte. A solid battery was produced in the same manner as in Example 1. And the impedance was measured like the above-mentioned Example 1. The results are shown in Table 1.

(Comparative Example 1)
As described above, except that Li ₂ S—P ₂ S ₅ (Molar ratio of Li ₂ S to P ₂ S ₅ is 80:20 mol%) amorphous powder having an average particle size of 20 μm was used as the solid electrolyte. A solid battery was produced in the same manner as in Example 1. And the impedance was measured like the above-mentioned Example 1. The results are shown in Table 1.

(Comparative Example 2)
A solid battery was produced in the same manner as in Example 1 except that the solid electrolyte layer was formed by directly applying an electrolyte coating solution on the negative electrode structure. More specifically, a negative electrode structure was first installed on a desktop screen printer, and an electrolyte coating solution was applied thereon using a metal mask having a thickness of 150 μm and an opening of 90 mm × 60 mm. Next, after drying for 10 minutes on a hot plate at 40 ° C., the solid battery was produced by vacuum drying at 40 ° C. for 12 hours.

  And the impedance was measured like the above-mentioned Example 1. The results are shown in Table 1.

  As shown in Table 1, in Examples 1 and 2 where the average particle diameter of the solid electrolyte is smaller than the intermediate value of the opening width of the nonwoven fabric, the average particle diameter of the solid electrolyte is smaller than the intermediate value of the opening width of the nonwoven fabric. It can be seen that an increase in impedance can be suppressed as compared with the large comparative example 1.

  Moreover, in Example 1, 2, it turns out that it has the same impedance as the comparative example 2 which does not use the nonwoven fabric in a solid electrolyte sheet. That is, in Examples 1 and 2, by using a nonwoven fabric, it is possible to produce a solid electrolyte sheet excellent in self-supporting property and flexibility while maintaining a low impedance as in the case of not using a nonwoven fabric. I understand that I can do it.

  As described above, the present invention is suitable for a solid electrolyte sheet and an all-solid-state secondary battery including the solid electrolyte sheet.

DESCRIPTION OF SYMBOLS 1 All-solid-state secondary battery 2 Positive electrode current collection member 3 Positive electrode active material layer 4 Solid electrolyte sheet 5 Negative electrode active material layer 6 Negative electrode current collection member 8 Nonwoven fabric (support)
DESCRIPTION OF SYMBOLS 10 Nonwoven fabric fiber 11 Solid electrolyte 12 Opening part of nonwoven fabric M Intermediate value of opening width in opening part of nonwoven fabric

Claims (5)

A non-woven fabric having an opening;
A solid electrolyte sheet comprising a solid electrolyte provided on a surface of the nonwoven fabric and the opening,
The solid electrolyte sheet, wherein an average particle diameter of the solid electrolyte is smaller than an intermediate value of an opening width in the opening of the nonwoven fabric.   2. The solid electrolyte sheet according to claim 1, wherein an average particle diameter of the solid electrolyte is 0.01 μm to 50 μm.   3. The solid electrolyte sheet according to claim 1, wherein an intermediate value of the opening width is 0.01 μm to 100 μm.   The solid electrolyte sheet according to any one of claims 1 to 3, wherein the solid electrolyte is a sulfide-based solid electrolyte. A positive electrode active material layer;
A negative electrode active material layer;
An all-solid-state secondary battery comprising: the solid electrolyte sheet according to any one of claims 1 to 4.