JP2014096311A - Solid electrolyte sheet, electrode sheet, and all solid secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-supported solid electrolyte sheet having a large area, and to provide a method of manufacturing a solid electrolyte sheet applicable to a continuous process and a mass-production.SOLUTION: The solid electrolyte sheet includes: a glass solid electrolyte containing at least a lithium element (Li) and a sulfur element (S); and a support body composed of an electronic insulating inorganic fiber. The method of manufacturing a solid electrolyte sheet includes a step of hot-pressing a laminate or a composite containing the glass solid electrolyte containing at least a lithium element (Li) and a sulfur element (S) and the support body composed of the electronic insulating inorganic fiber at 150°C to 360°C.

Description

  The present invention relates to a solid electrolyte sheet, an electrode sheet, and an all solid state secondary battery.

  In the current lithium ion battery, an organic electrolyte is mainly used as an electrolyte. Although organic electrolytes exhibit high ionic conductivity, the electrolytes are liquid and flammable, so there are concerns about risks such as leakage and ignition when used as batteries. Therefore, development of a safer solid electrolyte is expected as an electrolyte for next-generation lithium ion batteries.

In order to solve this problem, a sulfide-based solid electrolyte containing sulfur (S) element, lithium (Li) element and phosphorus (P) element as main components has been developed, and a battery using this sulfide-based solid electrolyte As an all-solid-state lithium battery was developed.
The sulfide-based solid electrolyte used in the all solid lithium battery is usually in a powder form. Therefore, for the convenience of handling, a sheet-like solid state is required. However, it is difficult to form a single-layer thin film sheet made of only a powdered solid electrolyte, and a complicated process is required for manufacturing a battery. Moreover, although it is necessary to mix electrolyte with the electrode material layer of an all-solid-state battery, there existed problems, such as an energy density falling, if it is a powdery electrolyte.

  With respect to such a problem, Patent Document 1 discloses a solid electrolyte sheet obtained by mixing a lithium ion conductive solid electrolyte and a thermoplastic polymer resin in a dry manner and rolling under heating. However, since the thermoplastic polymer resin is mixed as a support for the solid electrolyte during the production of the sheet, there is a problem that the ion conduction path of the solid electrolyte is cut by the polymer chain and the ionic conductivity is lowered.

  Patent document 2 is disclosing the solid electrolyte sheet which apply | coated the solid electrolyte ink to the nonwoven fabric by the spray. However, since the ion conduction path of the solid electrolyte is cut by the polymer chain constituting the nonwoven fabric, a decrease in ionic conductivity is inevitable.

  Non-Patent Document 1 discloses a solid electrolyte sheet containing mesh by applying a solid electrolyte slurry to a PET (polyethylene terephthalate) mesh (thickness: 100 μm, opening ratio: 70%) and pressurizing while drying the solvent. Yes. However, the PET mesh has insufficient heat resistance and stability (does not react with the solid electrolyte or the like).

  Patent document 3 is disclosing the solid electrolyte sheet which filled the solid electrolyte glass ceramics in the nonwoven fabric. However, the ionic conductivity was not sufficient.

JP-A-4-133209 Japanese Patent Laid-Open No. 1-115069 JP 2008-103258 A

New Energy Industry Development Organization 2001 Results Report ("Development of New Inorganic Electrolytes for All Solid Lithium Batteries with Improved Stability")

An object of the present invention is to provide a self-supporting solid electrolyte sheet having a large area.
Another object of the present invention is to provide a solid electrolyte sheet that is easy to manufacture and is applicable to continuous processes and mass production.

According to the present invention, the following solid electrolyte sheet and the like are provided.
1. A solid electrolyte sheet comprising a glass solid electrolyte containing at least lithium element (Li) and sulfur element (S) and a support made of electronic insulating inorganic fibers.
2. 2. The solid electrolyte sheet according to 1, wherein the glass solid electrolyte is a glass solid electrolyte containing lithium element (Li), sulfur element (S), and phosphorus element (P).
3. 3. The solid electrolyte sheet according to 1 or 2, wherein the glass solid electrolyte is a glass solid electrolyte produced using at least lithium sulfide and phosphorous pentasulfide.
4). The solid electrolyte sheet according to 3, wherein the molar ratio of the lithium sulfide to the diphosphorus pentasulfide is 60:40 to 85:15.
5. A glass ceramic solid electrolyte containing at least lithium element (Li) and sulfur element (S), and a support made of an electronic insulating inorganic fiber;
A solid electrolyte sheet, wherein the glass ceramic solid electrolyte is a solid electrolyte in which glass ceramic solid electrolyte particles are fused together.
6). 6. The solid electrolyte sheet according to 5, wherein the glass ceramic solid electrolyte is a glass ceramic solid electrolyte containing lithium element (Li), sulfur element (S), and phosphorus element (P).
7). The solid electrolyte sheet according to 5 or 6, wherein the glass ceramic solid electrolyte is a glass ceramic solid electrolyte produced using at least lithium sulfide and diphosphorus pentasulfide.
8). 8. The solid electrolyte sheet according to 7, wherein a molar ratio of the lithium sulfide to the phosphorous pentasulfide is 60:40 to 85:15.
9. The solid electrolyte sheet according to any one of 1 to 8, wherein the electronic insulating inorganic fiber is one or more selected from glass fiber and ceramic fiber.
10. The solid electrolyte sheet according to any one of 1 to 9, wherein the support is a nonwoven fabric having a porosity of 80 to 99%.
11. A solid electrolyte comprising a step of hot pressing a glass solid electrolyte containing at least lithium element (Li) and sulfur element (S) and a support or a composite body comprising an electronic insulating inorganic fiber at 150 ° C. to 360 ° C. Sheet manufacturing method.
A solid electrolyte sheet obtained from the method for producing a solid electrolyte sheet according to 12.11.
13. An electrode sheet including a glass solid electrolyte containing lithium element (Li) and sulfur element (S), an electrode material, and a support made of inorganic fibers.
14 14. The electrode sheet according to 13, wherein the glass solid electrolyte is a glass solid electrolyte containing lithium element (Li), sulfur element (S), and phosphorus element (P).
15. The electrode sheet according to 13 or 14, wherein the glass solid electrolyte is a glass solid electrolyte produced using at least lithium sulfide and phosphorous pentasulfide.
16. 16. The electrode sheet according to 15, wherein the molar ratio of the lithium sulfide to the diphosphorus pentasulfide is 60:40 to 85:15.
17. A glass ceramic solid electrolyte containing lithium element (Li) and sulfur element (S), an electrode material, and a support made of inorganic fibers,
The electrode sheet, wherein the glass ceramic solid electrolyte is a solid electrolyte in which glass ceramic solid electrolyte particles are fused together.
18. 14. The electrode sheet according to 13, wherein the glass ceramic solid electrolyte is a glass ceramic solid electrolyte containing lithium element (Li), sulfur element (S), and phosphorus element (P).
19. The electrode sheet according to 17 or 18, wherein the glass ceramic solid electrolyte is a glass ceramic solid electrolyte produced using at least lithium sulfide and phosphorous pentasulfide.
20. 20. The electrode sheet according to 19, wherein the molar ratio of the lithium sulfide to the phosphorous pentasulfide is 60:40 to 85:15.
21. The electrode sheet according to any one of 13 to 20, wherein the inorganic fiber is one or more selected from glass fiber, ceramic fiber, metal fiber, and carbon fiber.
22. The said support body is a woven fabric or nonwoven fabric formed from one or more fibers selected from glass fibers, ceramic fibers and metal fibers, and carbon fibers, a metal foam, or a composite thereof. Electrode sheet.
23. The electrode sheet according to any one of 13 to 22, wherein the support has a porosity of 80 to 99%.
An all-solid-state secondary battery comprising one or more selected from the solid electrolyte sheet according to 24.1 to 10 and 12, and the electrode sheet according to 13 to 23.
The manufacturing method of the all-solid-state secondary battery including the process which pressurizes any one or more of the solid electrolyte sheet of 25.1-10 and 12 and the electrode sheet of 13-23 by 1 MPa-100 MPa.
26. The method for producing an all-solid-state secondary battery according to 25, comprising a step of heat-treating at a temperature in the range of 150 to 360 ° C.
The solid electrolyte sheet according to any one of 27.5 to 8 and the electrode sheet according to any one of 17 to 20 are bonded together, and an all-solid secondary including a step of pressing the obtained laminate at 1 MPa to 100 MPa. Battery manufacturing method.
A step of producing a laminate by bonding the solid electrolyte sheet according to any one of 28.1 to 4 and the electrode sheet according to any one of 13 to 16;
The manufacturing method of the all-solid-state secondary battery including the process of pressurizing the said laminated body at 1 Mpa-100 Mpa, and the process of heat-processing the said pressurized laminated body in the temperature range of 150-360 degreeC.

According to the present invention, a self-supporting solid electrolyte sheet having a large area can be provided.
According to the present invention, it is possible to provide a solid electrolyte sheet that is easy to manufacture and can be applied to a continuous process and mass production.

It is a schematic sectional drawing of the battery manufactured in the Example. 2 is a cross-sectional photograph of the solid electrolyte sheet produced in Example 1. FIG.

[Solid electrolyte sheet]
The first solid electrolyte sheet of the present invention includes a glass solid electrolyte containing lithium element (Li) and sulfur element (S) and a support made of electronic insulating inorganic fibers.
The first solid electrolyte sheet is a solid electrolyte sheet that is self-supporting by including a support, and can have a large area.

The second solid electrolyte sheet of the present invention includes a glass ceramic solid electrolyte containing lithium element (Li) and sulfur element (S) and a support made of electronic insulating inorganic fibers, and the glass ceramic solid electrolyte is made of glass. This is a solid electrolyte in which ceramic solid electrolyte particles are fused together. Fusion means that a part of the particulate solid electrolyte is dissolved and the dissolved part is integrated with another solid electrolyte.
The second solid electrolyte sheet is a solid electrolyte sheet that is self-supporting by including a support, and can have a large area. Moreover, a high ionic conductivity can be shown because the solid electrolyte is a crystallized glass ceramic solid electrolyte.

  The thicknesses of the first solid electrolyte sheet and the second solid electrolyte sheet are each preferably 1 μm or more and 300 μm or less, more preferably 5 μm or more and 100 μm or less.

In the first solid electrolyte sheet, the first solid electrolyte sheet and the second solid electrolyte sheet are glass solid electrolytes in the first solid electrolyte sheet, whereas in the second solid electrolyte sheet, the ion conductive media are fused with each other. The composition of the support and the solid electrolyte is the same, although it is different in that it is a solid electrolyte composed of attached glass ceramic solid electrolyte particles.
Hereinafter, components of the first solid electrolyte sheet and the second solid electrolyte sheet (hereinafter, these may be collectively referred to as the solid electrolyte sheet of the present invention) will be described.

(1) Support made of electronic insulating inorganic fiber By using the electronic insulating inorganic fiber as the support of the solid electrolyte sheet of the present invention, the sheet can be made self-supporting while suppressing a decrease in conductivity. it can.
Examples of the electronic insulating inorganic fibers include glass fibers and ceramic fibers. Specific examples of the glass fiber glass include soda lime glass, silica (crystal) glass, borosilicate glass, and potash glass. Specific examples of the ceramic of the ceramic fiber include aluminum oxide, calcium oxide, magnesium oxide, cement, asbestos, rock wool, and other electronic insulating minerals.
The electronic insulating inorganic fiber constituting the solid electrolyte sheet may be either the above simple substance or a composite of two or more.

  In order to use a support made of inorganic fibers as a self-supporting sheet, the support may contain a binder for bonding the fibers together. The binder may be a general binder such as PVA and a vinyl chloride binder in addition to the binder described below. A general inorganic nonwoven fabric may contain, for example, 40% by weight or less, 15% by weight or less, and 10% by weight or less of a binder.

The cross-sectional shape of the electronic insulating inorganic fiber may be any shape, but is preferably a circle, an ellipse, a rectangle, a triangle, or the like. In addition, the fiber surface of the inorganic fiber may be uneven.
The fiber diameter or the maximum length of the cross section of the electronic insulating inorganic fiber is preferably 0.5 μm to 200 μm, more preferably 1 μm to 50 μm.

The support made of an electronic insulating inorganic fiber is preferably in the form of a sheet that is self-supporting in the form of a nonwoven fabric or a woven fabric. In this case, the thickness of the sheet is preferably 1 to 500 μm, more preferably 5 to 50 μm.
The porosity of the support made of an electronic insulating inorganic fiber is preferably 80 to 99%, more preferably 85 to 98%.

The porosity of the support can be determined as follows.
Porosity [%] = (1− (apparent density of support [g / cm ³ ]) / (true density of support material [g / cm ³ ]) × 100
The apparent density of the support can be determined as follows.
Apparent density of support [g / cm ³ ] = weight of support [g] / (volume of support = area × thickness [cm ³ ])
Moreover, what is necessary is just to use the density when the space | gap of the material is zero for the true density of support material.

In the solid electrolyte sheet of the present invention, the volume ratio of the support and the solid electrolyte is preferably 30:70 to 0.5: 99.5%, more preferably 20:85 to 1: 99%.
It is ideal that the volume ratio is (1−porosity) :( porosity), but may vary depending on the treatment such as pressurization and heating and the charging ratio of the support and the solid electrolyte. .

(2) Glass solid electrolyte containing lithium element (Li) and sulfur element (S) The glass solid electrolyte containing lithium element and sulfur element contained in the first solid electrolyte sheet (hereinafter sometimes simply referred to as glass solid electrolyte) is , A substance having ionic conductivity, which is a solid substance at room temperature (for example, 25 ° C.).
The glass solid electrolyte is a solid electrolyte containing no crystal phase. The presence or absence of the crystalline phase can be confirmed by X-ray diffraction measurement, and the solid electrolyte in which no peak is observed by the measurement is a solid electrolyte containing no crystalline phase.

The glass solid electrolyte preferably contains sulfur, lithium, and phosphorus as constituent elements.
The glass solid electrolyte may contain at least one element selected from the group consisting of B, Si, Ge, and Al.

Glass solid electrolytes include, for example, lithium sulfide (Li ₂ S) and diphosphorus pentasulfide (P ₂ S ₅ ); lithium sulfide, simple phosphorus and simple sulfur; or lithium sulfide, diphosphorus pentasulfide, simple phosphorus and / or simple sulfur. Can be produced as a raw material.

When the glass solid electrolyte is produced from lithium sulfide and diphosphorus pentasulfide, the mixing molar ratio is usually 50:50 to 85:15, preferably 60:40 to 85:15, more preferably 65:35 to 77. : 23. Particularly preferably, it is about Li ₂ S: P ₂ S ₅ = 68: 32 to 73:27 (molar ratio).

  A glass solid electrolyte is obtained by subjecting the mixture of the above materials to a melt reaction and then quenching or processing by a mechanical milling method (hereinafter sometimes referred to as MM method). When the obtained glass solid electrolyte is further heat-treated, a glass ceramic solid electrolyte described later which is a crystalline solid electrolyte is obtained.

The particle size of the glass solid electrolyte particles is preferably 0.01 μm or more and 50 μm or less.
If it is less than 0.01 μm, handling may be difficult. When it is larger than 50 μm, the contact area with the active material is reduced, and the ion conductivity may be lowered. The particle size of the glass solid electrolyte particles is more preferably 0.05 or more and 20 μm or less, further preferably 0.1 μm or more and 100 μm or less, and particularly preferably 0.1 μm or more and 50 μm or less.
The particle size can be determined by a laser diffraction particle size distribution measuring method.

The laser diffraction particle size distribution measurement method can measure the particle size distribution without drying the composition. Specifically, the particle size in the composition is irradiated with a laser and the scattered light is analyzed to determine the particle size. Measure the distribution.
In the present invention, the solid electrolyte is measured in a dry state.
The specific measurement method is as follows. As a measuring device, for example, Mastersizer 2000 manufactured by Malvern Instruments Ltd. can be used.

First, 110 ml of dehydrated toluene (Wako Pure Chemicals, product name: special grade) was placed in the dispersion tank of the apparatus, and 6% of dehydrated tertiary butyl alcohol (Wako Pure Chemicals, special grade) was added as a dispersant. Added. After sufficiently mixing the above mixture, a solid electrolyte is added and the particle size is measured.
Here, the addition amount of the solid electrolyte is adjusted so that the laser scattering intensity corresponding to the particle concentration falls within the specified range (10 to 20%) on the operation screen specified by the above apparatus. If this range is exceeded, multiple scattering may occur, making it impossible to obtain an accurate particle size distribution. On the other hand, if the amount is less than this range, the S / N ratio is deteriorated and there is a possibility that accurate measurement cannot be performed.
In the above apparatus, since the laser scattering intensity is displayed based on the addition amount of the solid electrolyte, the addition amount that falls within the laser scattering intensity range is found.

(3) Glass ceramic solid electrolyte containing lithium element (Li) and sulfur element (S) Glass ceramic solid electrolyte containing lithium element (Li) and sulfur element (S) contained in the second solid electrolyte sheet (hereinafter simply referred to as glass) The ceramic solid electrolyte may be a solid electrolyte containing a crystalline phase. Here, the included crystal structure is preferably a Li ₇ P ₃ S ₁₁ structure.
The presence or absence of the crystalline phase can be confirmed by X-ray diffraction measurement, and the solid electrolyte whose peak is observed by the measurement is a solid electrolyte containing a crystalline phase. For example, the crystal structure of the Li ₇ P ₃ S ₁₁ structure is 2θ = 17.8, 18.2, 19.8, 21.8, 23.8, 25.9, 29.5, A peak is observed at 30.0 deg.

In the glass ceramic solid electrolyte of the second solid electrolyte sheet, solid electrolyte particles are fused to each other. Since the solid electrolyte particles are fused to each other, a wide range of ion conduction paths can be formed.
In addition, it can confirm that the solid electrolyte particle is fuse | melted by observing the 2nd solid electrolyte sheet using an optical microscope, and observing the boundary line of solid electrolyte particles.

(4) Others The solid electrolyte sheet may further contain a binder.
Examples of the binder include fluorine-containing resins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and fluorine rubber, heat-resistant resins such as polyimide (PI) and polyamideimide (PAI), polypropylene, polyethylene, and the like. A thermoplastic resin, ethylene-propylene-dienemer (EPDM), sulfonated EPDM, natural butyl rubber (NBR), etc. can be used alone or as a mixture of two or more. In addition, an aqueous dispersion of cellulose or styrene butadiene rubber (SBR), which is an aqueous binder, can also be used.

When the solid electrolyte sheet includes a binder, the blending ratio of the solid electrolyte and the binder in the solid electrolyte sheet is preferably solid electrolyte: binder = 90.0: 10.0 to 99.9: 0. 1 [wt%], more preferably solid electrolyte: binder = 99.0: 1.0 to 99.9: 0.1.
From the viewpoint of the flexibility imparting effect of the sheet, the blending amount of the binder is preferably 0.1% by weight or more.

[Method for producing solid electrolyte sheet]
The method for producing the solid electrolyte sheet is not particularly limited as long as the solid electrolyte powder can be uniformly disposed on the support. Moreover, it is preferable to make it as free as possible.
A 1st solid electrolyte sheet is obtained as a sheet | seat with which the glass solid electrolyte powder was filled to the support body by apply | coating or filling a glass solid electrolyte powder to a support body, and pressurizing the obtained laminated body or composite_body | complex. The second solid electrolyte sheet can be obtained by further heat-treating the obtained first solid electrolyte sheet.
In addition, if the solid electrolyte is crystallized before filling the woven fabric or non-woven fabric as the support with the solid electrolyte powder, the solid electrolytes are not fused even if heat treatment is performed after filling, and the second solid electrolyte A sheet cannot be obtained.

For example, a polytetrafluoroethylene (PTFE) sheet is placed on an aluminum foil, a solid electrolyte powder is uniformly sprayed or electrostatically coated thereon, a support is placed thereon, and a solid electrolyte is further placed thereon. Is uniformly sprayed or electrostatically applied, a PTFE sheet is placed, an aluminum foil is placed, a support is sandwiched between solid electrolytes, this is heated and pressed to obtain a solid electrolyte sheet without voids Can do. It is preferable that the solid electrolyte powder is filled so as to fill not only the surface of the support but also the gap of the support.
In addition, it may replace with aluminum foil and may use the sheet | seat (foil) of another raw material. In that case, it is preferable that the material is a material that is difficult to be sulfided, difficult to pass moisture in the air, and hardly deteriorated even at a temperature of 340 ° C.
Moreover, it may replace with a PTFE sheet and may use the sheet | seat (foil) of another raw material. In that case, it is preferable that the material be hardly sulfided, easily peeled off from the solid electrolyte sheet, and hardly deteriorated even at a temperature of 340 ° C.
In addition, if it is a raw material which has said function, it can also be pinched | interposed with one sheet | seat (foil).

In addition to the spray coating and electrostatic coating described above, the solid electrolyte powder may be applied to the support by dispersing the solid electrolyte in a solvent to form a slurry. By applying and drying the solid electrolyte slurry, it is possible to uniformly dispose the solid electrolyte on the support and obtain an electrolyte sheet without voids.
The solvent used is preferably a hydrocarbon solvent such as hexane, heptane, octane, toluene, xylene, etc., and has a low water content, preferably 10 ppm or less, particularly preferably 1 ppm or less.
When a binder is used, it is preferable to disperse the binder in the slurry. Moreover, it is good to heat and compress simultaneously with drying or after drying, and to improve adhesiveness with a support body.

The solid electrolyte used is preferably glass or a mixture of glass and glass ceramics.
In the case of press molding, a method such as heat compression, roll compression with a two-way roller, or a combination thereof can be used, depending on the binder used.
Examples of the pressurization include a method using a press machine and a roll press method in which two rolls are passed. The pressure is usually 0.01 to 200 MPa, preferably 1 to 150 MPa, and particularly preferably 5 to 100 MPa. The solid electrolyte sheet is usually thickened by pressurization, and the shape is easily maintained.

  The heating temperature is preferably not less than the glass transition temperature (Tg) of the glass solid electrolyte and not more than the crystallization temperature (Tc) of the glass solid electrolyte + 100 ° C. or less. If the heating temperature is less than the Tg of the glass solid electrolyte, the production time may be very long. On the other hand, when (Tc + 100 ° C.) is exceeded, impurities or the like may be contained in the solid electrolyte having a crystal component to be obtained, and the ionic conductivity may be lowered.

The heating temperature is more preferably (Tg + 5 ° C.) or more and (Tc + 90 ° C.) or less, and further preferably (Tg + 10 ° C.) or more and (Tc + 80 ° C.) or less.
For example, in the case of a glass solid electrolyte containing lithium and sulfur, the heating temperature is 150 ° C. or higher and 360 ° C. or lower, preferably 160 ° C. or higher and 350 ° C. or lower, more preferably 180 ° C. or higher and 310 ° C. or lower, Preferably they are 180 degreeC or more and 290 degrees C or less, Most preferably, they are 190 degreeC or more and 270 degrees C or less.

The crystallization temperature of the glass solid electrolyte can be specified by differential thermo-thermogravimetry or the like. For example, using a thermogravimetry apparatus (TGA / DSC1 manufactured by METTLER TOLEDO), about 20 mg of glass solid electrolyte is heated. It can be specified by measuring by heating at a rate of 10 ° C./min.
It should be noted that the crystallization temperature or the like may change depending on the temperature rising rate or the like, and should be selected based on Tc measured at a rate close to the temperature rising rate for heat treatment. Therefore, when the treatment is performed at a temperature raising rate other than the example, the optimum heat treatment temperature changes, but it is desirable to perform the heat treatment under the above-mentioned conditions with reference to Tc measured at the temperature raising rate for heat treatment.

  The heating time is preferably 0.005 minutes or more and 10 hours or less. More preferably, it is 0.005 minutes or more and 5 hours or less, and particularly preferably 0.01 minutes or more and 3 hours or less. If it is less than 0.005 minutes, the electrolyte contains a large amount of glass components, which may lower the ionic conductivity. If it exceeds 10 hours, impurities and the like may be generated in the solid electrolyte, and the ionic conductivity may be lowered.

[Electrode sheet]
The first electrode sheet of the present invention includes a glass solid electrolyte containing lithium element (Li) and sulfur element (S), an electrode material, and a support made of inorganic fibers.
The first electrode sheet is an electrode sheet that is self-supporting by including a support and can have a large area.

The second electrode sheet of the present invention includes a glass ceramic solid electrolyte containing lithium element (Li) and sulfur element (S), an electrode material, and a support made of inorganic fibers, and the glass ceramic solid electrolyte is glass ceramic. An electrolyte in which solid electrolyte particles are fused together.
The second electrode sheet is an electrode sheet that is self-supporting by including a support, and can have a large area. Moreover, a high ionic conductivity can be shown because the solid electrolyte is a crystallized glass ceramic solid electrolyte.

  The thicknesses of the first electrode sheet and the second electrode sheet (hereinafter sometimes collectively referred to as the electrode sheet of the present invention) are each preferably 1 μm or more and 300 μm or less, more preferably 5 μm or more and 100 μm or less. It is.

The first electrode sheet and the second electrode sheet are glass ceramics in which the ion conductive medium is a glass solid electrolyte in the first electrode sheet, whereas the ion conductive medium is fused to each other in the second electrode sheet. Although it differs in that it is a solid electrolyte particle, the composition of the support and the solid electrolyte is common.
The solid electrolyte sheet support of the present invention is a support made of electronic insulating inorganic fibers, whereas the first electrode sheet and the second electrode sheet support are made of inorganic fibers. Well, it is different in that it is not limited to electronic insulating inorganic fibers. In addition, the solid electrolyte contained in the electrode sheet is the same as the solid electrolyte sheet.
Moreover, the electrode sheet may further contain a conductive additive and / or a binder.
Hereinafter, an electrode material that is included in the electrode sheet of the present invention and does not include the solid electrolyte sheet of the present invention, and a support made of inorganic fibers will be described.

(1) Support made of inorganic fiber Examples of the inorganic fiber include glass fiber, ceramic fiber, metal fiber, and carbon fiber.
The glass fiber and the ceramic fiber may be glass and ceramics having electronic conductivity. Therefore, not only fibers made of soda-lime glass, silica (crystal) glass, borosilicate glass, potash glass, alumina, calcia, magnesia, cement, asbestos, rock wool, and other electronic insulating minerals, but also electronic conductivity such as titania. Ceramic fibers having can also be used.

  A support made of carbon fiber can be used. The carbon fiber is, for example, a fiber obtained by carbonizing polyacrylonitrile, pitch, or the like at a high temperature. This carbon fiber can be made into a sheet by making a nonwoven fabric or a woven fabric and used as a support.

Even if it is an electronically insulating inorganic fiber, an electronically conductive film such as metal or carbon is formed on the surface of the fiber by using a method such as vacuum deposition, sputter film formation, or plating. It can also be used and used as an electronically conductive inorganic fiber.
By using a support having electronic conductivity, the effect of increasing the conductivity of the electrode can be expected.

When the electrode sheet is a negative electrode sheet, the metal fiber constituting the support is preferably a metal that is not easily sulfided when heated to 340 ° C. or less and that is not easily alloyed with Li even at the negative electrode potential, and Ti and stainless steel are suitable. Further, even if Cu, Ni, or the like that is sulfided when heated, if the surface is coated with a material that is not easily sulfided, it can be used as a metal for a negative electrode.
When the electrode sheet is a positive electrode sheet, the metal fiber constituting the support is preferably a metal that is not easily sulfided when heated to 340 ° C. or less and that is not easily oxidized even at the positive electrode potential, such as Au, Pt, Al, Ti, and stainless steel. Al, Ti, and stainless steel are more preferable from the viewpoint of availability.

The support made of inorganic fibers is preferably in the form of a sheet that is self-supporting in the form of a nonwoven fabric or a woven fabric. Moreover, when an inorganic fiber is a metal fiber, the form of a metal foam may be sufficient.
The thickness of the support in these cases is preferably 1 to 500 μm, more preferably 5 to 50 μm. The porosity of the support made of inorganic fibers is preferably 80 to 99%, more preferably 85 to 98%.

(2) Electrode material An electrode material contains a positive electrode active material and a negative electrode active material.
When the electrode sheet includes a positive electrode active material as an electrode material, the sheet can function as a positive electrode sheet. Similarly, when an electrode sheet contains a negative electrode active material as an electrode material, the sheet can function as a negative electrode sheet.

As the negative electrode active material, a material capable of inserting and desorbing lithium ions, and a material known as a negative electrode active material in the battery field can be used. In addition, the negative electrode active material used in the present invention may be not only a known negative electrode active material but also a negative electrode active material developed in the future, and it is needless to say that a commercially available material can be used.
For example, carbon materials, specifically artificial graphite, graphite carbon fiber, resin-fired carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon Examples thereof include fibers, vapor-grown carbon fibers, natural graphite, and non-graphitizable carbon. Or it may be a mixture thereof. Preferably, it is artificial graphite.
In addition, an alloy in combination with a metal itself such as metal lithium, metal indium, metal aluminum, metal tin, or metal silicon, or another element or compound can be used as the negative electrode active material. Among these, silicon, tin, and lithium metal having a high theoretical capacity are preferable.
In particular, a negative electrode active material (silicon oxide) containing both silicon and oxygen as constituent elements is preferable as a material having a high capacity and good cycle characteristics.

As the positive electrode active material, a material capable of inserting and desorbing lithium ions, and a material known as a positive electrode active material in the battery field can be used. In addition, the positive electrode active material used in the present invention may be not only a known positive electrode active material but also a positive electrode active material developed in the future, and it is needless to say that a commercially available material can be used.
For example, V ₂ O ₅ , LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _c ) O ₂ (where 0 <a <1, 0 <b <1, 0 < c <1, a + b + c = 1), LiNi _1-Y Co _{Y 2} O ₂ , LiCo _1-Y Mn _{Y 2} O ₂ , LiNi _1-Y Mn _{Y 2} O ₂ (where 0 ≦ Y <1), Li (Ni _{a Co b Mn c) O 4 (} 0 <a <2,0 <b <2,0 <c <2, a + b + c = 2), LiMn 2-Z Ni Z O 4, LiMn 2-Z Co Z O 4 ( wherein 0 <Z <2), LiMPO ₄ (where M = Co, Mn, Fe), Li ₂ MSiO ₄ (where M = Co, Mn, Fe), LiMBO ₃ (where M = Co , Mn, Fe), sulfur, and organic sulfur compounds.

The mixing ratio of the negative electrode active material and the solid electrolyte is preferably negative electrode active material: solid electrolyte = 50 wt%: 50 wt% to 90 wt%: 10 wt%, and the negative electrode active material: solid electrolyte = 55 wt%: 45 wt% -80% by weight: 20% by weight is more preferable, and negative electrode active material: solid electrolyte = 60% by weight: 40% by weight to 75% by weight: 25% by weight is more preferable.
The mixing ratio of the positive electrode active material and the solid electrolyte is preferably positive electrode active material: solid electrolyte = 50 wt%: 50 wt% to 90 wt%: 10 wt%, and positive electrode active material: solid electrolyte = 60 wt%: 40 wt% -80% by weight: 20% by weight is more preferable, and positive electrode active material: solid electrolyte = 65% by weight: 35% by weight to 75% by weight: 25% by weight is more preferable.

(3) Others The electrode sheet can further contain a binder and / or a conductive aid.
Examples of the conductive assistant include substances selected from carbon materials, metal powders and metal compounds, and mixtures thereof.
Specific examples of conductive aids are preferably carbon, nickel, copper, aluminum, indium, silver, cobalt, magnesium, lithium, chromium, gold, ruthenium, platinum, beryllium, iridium, molybdenum, niobium, osnium, rhodium, tungsten And a substance containing at least one element selected from the group consisting of zinc, more preferably simple carbon, carbon, nickel, copper, silver, cobalt, magnesium, lithium, ruthenium, gold, platinum, niobium, osnium or rhodium A simple metal, a mixture or a compound containing
Specific examples of the carbon material of the conductive additive include carbon black such as ketjen black, acetylene black, denka black, thermal black, channel black, graphite, carbon fiber, activated carbon, carbon nanotube, vapor grown carbon fiber ( VGCF) and graphene. These can be used alone or in combination of two or more.
Among the above conductive assistants, acetylene black, denka black, ketjen black, carbon nanotube, vapor grown carbon fiber (VGCF), and graphene having high electron conductivity are suitable.

[All-solid secondary battery]
The all solid state secondary battery of the present invention is an all solid state secondary battery comprising at least one selected from the solid electrolyte sheet of the present invention and the electrode sheet of the present invention.
Therefore, the all-solid-state secondary battery of the present invention includes (i) an all-solid battery that includes only the solid electrolyte sheet of the present invention, (ii) an all-solid battery that includes only the electrode sheet of the present invention, and (iii) An all solid state battery including both the solid electrolyte sheet and the electrode sheet of the present invention is included.
Regarding the all solid-state batteries of (i), (ii) and (iii) above, members known in the battery field can be used for members other than the solid electrolyte sheet and electrode sheet of the present invention.

In the case of (i), the negative electrode layer is preferably a negative electrode layer containing a negative electrode active material represented by the following formula (1), a polyimide binder, and / or the above-mentioned conductive aid.
Li _x SiO _y (1)
(X: a number from 0 to 5 and y is a number from 0 to 1.6)
As a polyimide binder, it is only necessary to use a polyimide precursor that is generally sold, and it is three-dimensionally cross-linked to be used for carbon fiber composites, etc., rather than using polyimide for producing a film such as Kapton. It is more preferable to use a type of polyimide that can suppress cycle deterioration of the negative electrode.
A negative electrode layer made of Li _x SiO _y , a carbon conductive aid and a polyimide binder, or a negative electrode layer made of Li _x SiO _y , a carbon conductive aid, a support and a polyimide binder is preferred.

The negative electrode active material represented by the formula (1) is also useful as an electrode material of the electrode sheet of the present invention. For example, in the case of (iii), the negative electrode layer is Li _x SiO _y , carbon conductive additive, support, solid A negative electrode layer made of an electrolyte and a polyimide binder is preferable.

  In the case of (ii), the solid electrolyte layer is preferably a layer made of a sulfide-based solid electrolyte. The sulfide-based solid electrolyte is the same as the solid electrolyte used for the electrolyte sheet and electrode sheet of the present invention except that the shape may be particles or not.

  As the current collector, a known current collector can be used. For example, Au, Pt, Al, Ti, stainless steel, carbon fiber sheet, or a layer coated with Au or the like that reacts with a sulfide-based solid electrolyte such as Cu or Ni can be used.

[Method for producing all-solid-state secondary battery]
The all-solid-state secondary battery of the present invention can be produced by pressing a laminate including one or more of the solid electrolyte sheet of the present invention and the electrode sheet of the present invention at, for example, 1 MPa to 100 MPa. The pressure applied to the laminate is preferably 25 MPa to 50 MPa.
In the production of an all-solid secondary battery, for example, when only the solid electrolyte sheet of the present invention is used and the electrode sheet of the present invention is not used, known sheets can be used for the positive electrode sheet and the negative electrode sheet.

When the solid electrolyte sheet and electrode sheet of the present invention used for the production of an all-solid secondary battery are sheets containing a glass solid electrolyte (first solid electrolyte sheet and first electrode sheet), the obtained laminate For example, the glass solid electrolyte in the sheet can be made into a glass ceramic solid electrolyte by heat-treating in a temperature range of 150 to 360 ° C.
A preferable heat treatment temperature is 270 to 340 ° C.

In the method for producing an all solid state battery of the present invention, preferably, the first solid electrolyte sheet of the present invention and the first electrode sheet of the present invention are bonded to form a laminate, and the obtained laminate is 1 MPa to 100 MPa. An all-solid battery is manufactured by pressurizing and heat-treating the pressurized laminate in a temperature range of 150 to 360 ° C. Alternatively, the first solid electrolyte sheet of the present invention and the second electrode sheet of the present invention are bonded together to form a laminate, or the second solid electrolyte sheet of the present invention and the first electrode sheet of the present invention. A laminated body can also be used by bonding.
By using a sheet containing a glass solid electrolyte for both the solid electrolyte sheet and the electrode sheet, fusion occurs at the interface between the solid electrolyte sheet and the electrode sheet during heating, so that the interface is more firmly adhered and the interface resistance is reduced. As a result, ion conductivity is further improved, and performance such as input / output characteristics when the battery is finally formed is improved. In addition, the interface does not easily peel off when the electrode expands and contracts due to charging / discharging, and the effect of suppressing deterioration of the battery due to the peeling of the interface due to vibration during use is increased in a battery for mobile devices or in-vehicle use. In addition, the heat treatment process is performed once, and the manufacturing process can be shortened.

In the method for producing an all-solid battery of the present invention, preferably, the second solid electrolyte sheet of the present invention and the second electrode sheet of the present invention are bonded together to form a laminate, and the obtained laminate is 1 MPa to 100 MPa. Pressurize to produce an all-solid battery.
By using a sheet containing a glass ceramic solid electrolyte for both the solid electrolyte sheet and the electrode sheet, the heat treatment process can be omitted, and the manufacturing process can be shortened.

Production Example 1 (Production of high purity lithium sulfide)
Production of high-purity lithium sulfide was carried out in the same manner as in the examples of International Publication WO2005 / 040039A1. Specifically, it was performed as follows.
(1) Production of lithium sulfide (Li ₂ S) Lithium sulfide was produced according to the method of the first aspect (two-step method) of JP-A-7-330312. Specifically, N-methyl-2-pyrrolidone (NMP) 3326.4 g (33.6 mol) and lithium hydroxide 287.4 g (12 mol) were charged into a 10 liter autoclave equipped with a stirring blade, and 300 rpm, 130 The temperature was raised to ° C. After the temperature rise, hydrogen sulfide was blown into the liquid at a supply rate of 3 liters / minute for 2 hours.
Subsequently, this reaction solution was heated in a nitrogen stream (200 cc / min) to dehydrosulfide a part of the reacted hydrogen sulfide. As the temperature increased, water produced as a by-product due to the reaction between the hydrogen sulfide and lithium hydroxide started to evaporate, but this water was condensed by the condenser and extracted out of the system. While water was distilled out of the system, the temperature of the reaction solution rose, but when the temperature reached 180 ° C., the temperature increase was stopped and the temperature was kept constant. After the dehydrosulfurization reaction was completed (about 80 minutes), the reaction was completed to obtain lithium sulfide.

(2) Purification of lithium sulfide After decanting NMP in the 500 mL slurry reaction solution (NMP-lithium sulfide slurry) obtained in (1) above, 100 mL of dehydrated NMP was added and stirred at 105 ° C. for about 1 hour. . NMP was decanted at that temperature. Further, 100 mL of NMP was added, stirred at 105 ° C. for about 1 hour, NMP was decanted at that temperature, and the same operation was repeated a total of 4 times. After completion of the decantation, lithium sulfide was dried at 230 ° C. (temperature higher than the boiling point of NMP) under a nitrogen stream for 3 hours under normal pressure. The impurity content in the obtained lithium sulfide was measured.

Incidentally, lithium sulfite _(Li 2 _SO 3), the content of each sulfur oxide lithium sulfate _(Li 2 SO ₄₎ and lithium thiosulfate _{(Li 2 S 2 O 3)} , and N- methylamino acid lithium (LMAB) Was quantified by ion chromatography. As a result, the total content of sulfur oxides was 0.13% by mass, and LMAB was 0.07% by mass.

Production Example 2 (Production of solid electrolyte glass)
Using the high-purity lithium sulfide produced in Production Example 1, a solid electrolyte was produced and crystallized in the same manner as in Example 1 of International Publication WO07 / 065539.
Specifically, it was performed as follows.
0.6492 g (0.01417 mol) of high purity lithium sulfide produced in Production Example 1 and 1.3492 g (0.00607 mol) of diphosphorus pentasulfide (manufactured by Aldrich) were mixed well. Then, the mixed powder, 10 zirconia balls having a diameter of 10 mm, and a planetary ball mill (manufactured by Fritsch Co., Ltd .: Model No. P-7) are put into an alumina pot and completely sealed, and the alumina pot is filled with nitrogen, The atmosphere was nitrogen.
For the first few minutes, the planetary ball mill was rotated at a low speed (85 rpm) to sufficiently mix lithium sulfide and diphosphorus pentasulfide. Thereafter, the rotational speed of the planetary ball mill was gradually increased to 370 rpm. Mechanical milling was performed at 370 rpm for 20 hours with a planetary ball mill rotating speed to obtain sulfide glass as a white yellow powder.

Vitrification (sulfide glass) of the white yellow powder obtained by mechanical milling was confirmed by X-ray measurement. It was 220 degreeC when the glass transition temperature of this sulfide glass was measured by DSC (differential scanning calorimetry). Moreover, the electrical conductivity of the obtained sulfide glass was 9.8 × 10 ⁻⁵ S / cm.

Example 1
[Manufacture of solid electrolyte sheet]
A PTFE sheet (Nichias naflon tape, thickness 0.5 mm) is laid on an Al foil (thickness 50 μm), 10 g of the sulfide glass obtained in Production Example 2, and a glass nonwoven fabric (Olivest glass nonwoven fabric SAS as a support). -030, thickness 231 μm, basis weight 29.6 g / m ³ , density 0.130 g / cm ³ , glass fiber: 9 μm diameter × 13 mm), 10 g of sulfide glass obtained in Production Example 2 in this order, The sulfide glass was made uniform on the support, and a PTFE sheet and an Al foil were placed thereon.
This laminate was press-heated under the conditions of 1 ton, 270 ° C., and 10 min with a hot press apparatus (SA-401 manufactured by Tester Sangyo). After the heat and pressure treatment, the Al foil and the PTFE sheet were peeled off to obtain an electrolyte sheet having a thickness of 300 μm. The obtained electrolyte sheet was punched into a diameter of 12.0 mm and arranged in a circular sheet shape.
The cross section of the obtained sheet was observed using an optical microscope. A cross-sectional photograph of the sheet is shown in FIG. In the cross section of this sheet, a plurality of particles were fused together, and it was confirmed that the molded body had few voids. Further, the obtained electrolyte sheet did not generate cracks even when bent, and there was no crack in the peripheral part even when punched.

[Production and evaluation of batteries]
(1) Synthesis of negative electrode active material (SiO powder) 7.51 g of SiO ₂ powder (manufactured by high purity chemical, average particle size 1 μm, amorphous state) and 3.51 g of Si powder (manufactured by high purity chemical, average particle size 5 μm) A zirconia ball having a diameter of 4 mm was placed in a zirconia pot, and the lid was closed in a glove box filled with an argon atmosphere. SiO powder was synthesized by performing mechanical alloying treatment at a gravitational acceleration of 150 G for 10 hours using a high energy planetary ball mill apparatus (manufactured by Kurimoto Steel Works).
The average particle diameter of the obtained SiO powder is 5 μm, and the molar ratio of Si / O is in the range of 0.9 to 1.1.

(2) Production of negative electrode (production of negative electrode by negative electrode coating method)
The SiO powder 8.0g synthesized in (1), the conductive auxiliary agent Ketjen Black (KB) 0.5g, and the binder polyimide (PI) precursor (LV-042, Toray) 1. 5 g (in terms of solid content) was mixed and kneaded while mixing N-methyl-2-pyrrolidone (NMP), which is a solvent for adjusting viscosity, to obtain an electrode slurry.
This electrode slurry was applied onto a 10 μm thick SUS304 material stainless steel foil using a doctor blade, temporarily dried at 80 ° C. for 10 minutes in the atmosphere, then dried at 200 ° C. under reduced pressure for 5 hours, and a polyimide precursor. Was imidized into polyimide. After cooling this to room temperature, it was punched out into a circle of φ9 mm to produce a negative electrode. The weight of SiO contained per obtained negative electrode was 0.75 mg.

(3) Manufacture of battery The obtained negative electrode and the electrolyte sheet were overlapped in the direction in which the negative electrode layer and the solid electrolyte were in contact with each other, pressed at 20 MPa using a desktop hand press machine, and then 0.5 mm thick. A Li-In alloy foil (Li / In weight ratio of 4) punched into a circle with a diameter of 9 mm is attached to the opposite side of the negative electrode as a counter electrode, and the negative electrode layer / solid electrolyte layer / Li-In alloy A battery pellet having a three-layer structure of layers was obtained.

Using the obtained battery pellet, a coin-type lithium secondary battery (2032 type coin cell) having a schematic cross-sectional view shown in FIG. 1 was produced.
The coin-type lithium secondary battery 1 in FIG. 1 has a configuration in which a battery element 2 is fitted between a metal case 3 and a metal sealing plate 4. The battery element 2 has a structure in which a current collector 211, a positive electrode (or counter electrode) 21, a solid electrolyte layer 22, a negative electrode 23, a current collector 231 and a metal flat plate (spacer) 232 are laminated in this order from the metal case 3 side. The positive electrode (or counter electrode) 21, the solid electrolyte layer 22, and the negative electrode 23 correspond to the above-described Li—In alloy layer, solid electrolyte layer, and negative electrode layer of the battery pellet, respectively.
A gasket 5 made of polypropylene (PP) was used. Further, two 0.5 mm SUS plates were used for the metal flat plate 232. A disc spring was applied as the spring 6. When this disc spring and two 0.5 mm spacers were applied, the pressure inside the coin battery was 10 MPa.
The pressure inside the coin battery was measured at the substantially central portion of the solid electrolyte by using pressure sensitive paper.

About the obtained lithium secondary battery, the charge / discharge test was implemented and evaluated on the conditions shown below.
As a result, it was possible to obtain an initial charge capacity (Li occlusion side) of 2246 mAh / g and a 2nd discharge (Li release side) of 1269 mAh / g at a current of 0.05 C. Further, when the current was set to 0.02 C, a high discharge capacity of 1453 mAh / g was obtained, and 969 mAh / g was obtained even at a current value of 0.2 C.
The conditions for the charge / discharge test are as follows:
Voltage range: 1.0 to 0.0 V vs. Li ⁺ / Li
Current: 0.05C, 0.02C, 0.2C
Test temperature: 80 ° C

Example 2
A battery was manufactured and evaluated in the same manner as in Example 1 except that the negative electrode sheet and the electrolyte sheet were not pressed. In addition, the unevenness | corrugation was seen by the obtained battery pellet of the 3 layer structure.
As a test result, it was possible to obtain an initial charge capacity (Li occlusion side) of 979 mAh / g and a 2nd discharge (Li release side) of 593 mAh / g at a current of 0.05 C.

Example 3
Instead of glass fiber nonwoven fabric, glass nonwoven fabric paper (GMC-00-10E, thickness 51 μm, basis weight 9.5 g / m ³ , density 0.19 g / cm ³ , made by Oji Specialty Paper) is used as the support. A solid electrolyte sheet and a battery were produced and evaluated in the same manner as in Example 2 except that the solid electrolyte sheet was produced.
In addition, the thickness of the obtained solid electrolyte sheet was 73 micrometers, and the unevenness | corrugation was seen by the obtained battery pellet of 3 layer structure.
As a test result, it was possible to obtain an initial charge capacity (Li occlusion side) of 415 mAh / g and a 2nd discharge (Li release side) of 170 mAh / g at a current of 0.05 C.

Example 4
(1) Production of positive electrode sheet (production of positive electrode sheet using glass fiber support)
Ethanol: 187 mL, lithium ethoxide (LiOC ₂ H ₅ ): 9.31 g, titanium isopropoxide (Ti (Oi—C ₃ H ₇ ) ₄ ): 63.30 g of Li ₄ Ti ₅ O No. ₁₂ precursor solution was added at 2 g / min. Using a tumbling fluidized coating apparatus (Multiplex MP-01, manufactured by Paulek). _Was sprayed onto the Li (Ni _0.8 Co _0.15 Al _0.05 ) O ₂ powder at a rate of Thereafter, the Li (Ni _0.8 Co _0.15 Al _0.05 ) O ₂ powder whose surface was coated with the Li ₄ Ti ₅ O ₁₂ precursor liquid was heated in air at 400 ° C. for 1 hour to make the surface Li _4. A coating of Ti ₅ O ₁₂ was made. As a result, the surface of Li (Ni _0.8 Co _0.15 Al _0.05 ) O ₂ powder (average particle size: 5 μm) was uniformly coated with Li ₄ Ti ₅ O ₁₂ at a thickness of 5 nm.
The coating layer of Li ₄ Ti ₅ O ₁₂ prevents the reaction between Li (Ni _0.8 Co _0.15 Al _0.05 ) O ₂ and the sulfide solid electrolyte from occurring as much as possible by a hot press process described later. Is the purpose.

Li ₄ Ti ₅ O ₁₂ coated Li (Ni _0.8 Co _0.15 Al _0.05 ) O ₂ and acetylene black, VGCF (vapor grown carbon fiber), the sulfide glass obtained in Production Example 2 : Weighed and mixed to have a 3: 2: 30 weight ratio. Gap of glass nonwoven fabric (GMC-00-10E, thickness 51 μm, basis weight 9.5 g / m ³ , density 0.19 g / cm ³ , Oji Special Paper) serving as a support for the obtained mixed powder Filled. The obtained glass nonwoven fabric paper / mixed powder composite was sandwiched between PTFE sheets (Nichias Naflon tape, thickness 0.5 mm), and the outside was sandwiched between Al foils (thickness 50 μm).
This laminate was press-heated under the conditions of 1 ton, 270 ° C., and 10 min with a hot press apparatus (SA-401 manufactured by Tester Sangyo). After the heat and pressure treatment, the Al foil and the PTFE sheet were peeled off to obtain a positive electrode sheet having a thickness of 83 μm. The obtained positive electrode sheet was punched out to a diameter of 9.0 mm and arranged in a circular sheet shape to produce a positive electrode sheet.

(2) Production of negative electrode sheet (production of negative electrode sheet using glass fiber support)
A Li—SiO alloy was produced in the same manner as in Example 1 (1) except that not only equal molar amounts of Si and SiO ₂ but also 25 wt% of metal Li pieces were added. By adding Li, the initial irreversible capacity of SiO was compensated. As a result, when a battery is manufactured in combination with a positive electrode containing Li, the positive electrode's Li is no longer used for supplementing the initial irreversible capacity of SiO, and the electric capacity of the entire battery is increased. be able to.
The obtained Li—SiO alloy, acetylene black, VGCF, and the sulfide glass obtained in Production Example 2 were weighed and mixed so that the weight ratio was 50: 3: 2: 50. The obtained mixed powder was filled into a glass nonwoven fabric paper in the same manner as in the production of the positive electrode sheet of (1), hot pressed to form a sheet, and punched to obtain a negative electrode sheet having a diameter of 9 mm. The thickness of the obtained negative electrode sheet was 78 μm.

(3) Production of solid electrolyte sheet A solid electrolyte sheet was produced in the same manner as in Example 3.

(4) Manufacture of battery The obtained positive electrode sheet, negative electrode sheet and solid electrolyte sheet were brought into contact with each other in such a manner that the solid electrolyte sheet was sandwiched between the positive electrode sheet and the negative electrode sheet, and pressed at 40 MPa using a desktop hand press machine. Thus, a battery pellet having a three-layer structure of positive electrode layer / solid electrolyte layer / negative electrode layer was obtained.
A coin-type lithium secondary battery (2032 type coin cell) similar to that in Example 1 was produced using the obtained battery pellet.

About the obtained lithium secondary battery, the charge / discharge test was implemented and evaluated on the conditions shown below.
As a result, at an electric current of 0.02 C, the initial charge capacity (positive electrode Li release side) 77.4 mAh / g (in terms of positive electrode active material weight), 2nd discharge (positive electrode Li storage side) 77.0 mAh / g (positive electrode active) A volume of material weight conversion) could be obtained.
The conditions for the charge / discharge test are as follows:
Voltage range: 4.4 to 1.5 V vs. Li ⁺ / Li
Current: 0.02C
Test temperature: 80 ° C

Comparative Example 1
A solid electrolyte sheet was produced in the same manner as in Example 1 except that PET mesh (thickness 250 μm, fiber diameter 30 μm, aperture ratio 75%) was used as the support instead of the glass fiber nonwoven fabric.
In addition, although the shrinkage | contraction of the support body was seen at the time of manufacture of a solid electrolyte sheet, the sheet-like solid electrolyte sheet was obtained. The obtained sheet was punched into a diameter of 12.0 mm, and was used by adjusting it into a circular sheet shape.

Comparative Example 2
To a mixture of 10 g of the sulfide glass obtained in Production Example 2 and 1 g of polypropylene powder (particle size: 5 μm), 10 mL of hexane was added and mixed to obtain a slurry. The slurry was uniformly applied on a stainless steel foil having a thickness of 20 μm using a doctor blade, and then hexane was removed by evaporation at 70 ° C. in dry air. The both surfaces of the mixed film of the remaining sulfide glass and polypropylene were sandwiched between the PTFE sheet and the Al foil in the same manner as in Example 1, and the obtained laminate was 1 ton, 270 ° C., 10 min using a hot press device. Press heating was performed under the following conditions.
After the heating / pressurizing treatment, the Al foil and the PTFE sheet were peeled off, and the obtained solid electrolyte sheet was punched out to a diameter of 12.0 mm to prepare a circular sheet shape.

The conductivity of the 70Li ₂ S · 30P ₂ S ₅ glass ceramics solid electrolyte obtained by heating and crystallizing the sulfide glass obtained in Production Example 2 at 270 ° C., and the solid electrolyte sheets of Example 1 and Comparative Example 1-2, respectively. evaluated. The results are shown in Table 1.

The solid electrolyte sheet of Example 1 maintains a conductivity of about 90% as compared with the conductivity of the glass ceramic alone despite including the support, whereas Comparative Example 1 and Comparison In the solid electrolyte sheet of Example 2, it is reduced to 1/10 or less.
From the results of Table 1, it was found that the solid electrolyte sheet of the present invention was a thin and flexible solid electrolyte sheet with almost no decrease in electrical conductivity. It can also be seen that the use of the production method of the present invention can easily realize an increase in size of the solid electrolyte sheet.

  An all solid state secondary battery comprising at least one selected from the solid electrolyte sheet of the present invention and the electrode sheet of the present invention is a mobile communication device, a portable electronic device, an electric bicycle, an electric motorcycle, an electric vehicle, wind power generation or solar power. It is suitably used for a main power source such as a stationary storage battery for a battery.

DESCRIPTION OF SYMBOLS 1 Coin type lithium secondary battery 2 Battery element 211 Current collector 21 Positive electrode (counter electrode)
22 Solid Electrolyte Layer 23 Negative Electrode 231 Current Collector 232 Metal Flat Plate 3 Metal Case 4 Metal Sealing Plate 5 Gasket 6 Spring

Claims (28)

  A solid electrolyte sheet comprising a glass solid electrolyte containing at least lithium element (Li) and sulfur element (S) and a support made of electronic insulating inorganic fibers.   The solid electrolyte sheet according to claim 1, wherein the glass solid electrolyte is a glass solid electrolyte containing lithium element (Li), sulfur element (S), and phosphorus element (P).   The solid electrolyte sheet according to claim 1 or 2, wherein the glass solid electrolyte is a glass solid electrolyte produced using at least lithium sulfide and phosphorous pentasulfide.   The solid electrolyte sheet according to claim 3, wherein a molar ratio of the lithium sulfide to the diphosphorus pentasulfide is 60:40 to 85:15. A glass ceramic solid electrolyte containing at least lithium element (Li) and sulfur element (S), and a support made of an electronic insulating inorganic fiber;
A solid electrolyte sheet, wherein the glass ceramic solid electrolyte is a solid electrolyte in which glass ceramic solid electrolyte particles are fused together.   The solid electrolyte sheet according to claim 5, wherein the glass ceramic solid electrolyte is a glass ceramic solid electrolyte containing lithium element (Li), sulfur element (S), and phosphorus element (P).   The solid electrolyte sheet according to claim 5 or 6, wherein the glass ceramic solid electrolyte is a glass ceramic solid electrolyte produced using at least lithium sulfide and diphosphorus pentasulfide.   The solid electrolyte sheet according to claim 7, wherein a molar ratio of the lithium sulfide to the diphosphorus pentasulfide is 60:40 to 85:15.   The solid electrolyte sheet according to claim 1, wherein the electronic insulating inorganic fiber is one or more selected from glass fiber and ceramic fiber.   The solid electrolyte sheet according to any one of claims 1 to 9, wherein the support is a nonwoven fabric having a porosity of 80 to 99%.   A solid electrolyte comprising a step of hot pressing a glass solid electrolyte containing at least lithium element (Li) and sulfur element (S) and a support or a composite body comprising an electronic insulating inorganic fiber at 150 ° C. to 360 ° C. Sheet manufacturing method.   The solid electrolyte sheet obtained from the manufacturing method of the solid electrolyte sheet of Claim 11.   An electrode sheet including a glass solid electrolyte containing lithium element (Li) and sulfur element (S), an electrode material, and a support made of inorganic fibers.   The electrode sheet according to claim 13, wherein the glass solid electrolyte is a glass solid electrolyte containing lithium element (Li), sulfur element (S), and phosphorus element (P).   The electrode sheet according to claim 13 or 14, wherein the glass solid electrolyte is a glass solid electrolyte produced using at least lithium sulfide and phosphorous pentasulfide.   The electrode sheet according to claim 15, wherein a molar ratio of the lithium sulfide to the diphosphorus pentasulfide is 60:40 to 85:15. A glass ceramic solid electrolyte containing lithium element (Li) and sulfur element (S), an electrode material, and a support made of inorganic fibers,
The electrode sheet, wherein the glass ceramic solid electrolyte is a solid electrolyte in which glass ceramic solid electrolyte particles are fused together.   The electrode sheet according to claim 13, wherein the glass ceramic solid electrolyte is a glass ceramic solid electrolyte containing lithium element (Li), sulfur element (S) and phosphorus element (P).   The electrode sheet according to claim 17 or 18, wherein the glass ceramic solid electrolyte is a glass ceramic solid electrolyte produced using at least lithium sulfide and diphosphorus pentasulfide.   The electrode sheet according to claim 19, wherein a molar ratio of the lithium sulfide to the diphosphorus pentasulfide is 60:40 to 85:15.   The electrode sheet according to any one of claims 13 to 20, wherein the inorganic fiber is one or more selected from glass fiber, ceramic fiber, metal fiber, and carbon fiber.   The said support body is a woven fabric or nonwoven fabric formed from one or more fibers selected from glass fibers, ceramic fibers and metal fibers, and carbon fibers, a metal foam, or a composite thereof. The electrode sheet as described.   The electrode sheet according to any one of claims 13 to 22, wherein the porosity of the support is 80 to 99%.   An all-solid-state secondary battery comprising at least one selected from the solid electrolyte sheet according to claim 1 and 12 and the electrode sheet according to claims 13 to 23.   The manufacturing method of the all-solid-state secondary battery including the process which pressurizes any one or more of the solid electrolyte sheet of Claims 1-10 and 12 and the electrode sheet of Claims 13-23 by 1 Mpa-100 Mpa.   The manufacturing method of the all-solid-state secondary battery of Claim 25 including the process heat-processed at the temperature of the range of 150-360 degreeC.   The solid electrolyte sheet according to any one of claims 5 to 8 and the electrode sheet according to any one of claims 17 to 20 are bonded together, and the obtained laminate is pressurized at 1 MPa to 100 MPa. A method for manufacturing a secondary battery. A step of producing a laminate by bonding the solid electrolyte sheet according to any one of claims 1 to 4 and the electrode sheet according to any one of claims 13 to 16;
The manufacturing method of the all-solid-state secondary battery including the process of pressurizing the said laminated body at 1 Mpa-100 Mpa, and the process of heat-processing the said pressurized laminated body in the temperature range of 150-360 degreeC.