JP2016009626A - Composite solid electrolyte body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite solid electrolyte free from the generation of cleavage and cracks, and in which flexibility and ion conductivity are made consistent.SOLUTION: Provided is a composite solid electrolyte body having the first face and the second face and in which lithium ions are conducted in a space between the first face and the second face, a plurality of inorganic solid electrolyte bodies having lithium ion conductivity are bound with a binder other than the inorganic solid electrolyte, some of a plurality of the inorganic solid electrolyte bodies being conductive passage constituting inorganic solid electrolyte bodies composing a lithium ion conductive passage continuous from the first face to the second face, and the ratio of the area of a plurality of the inorganic solid electrolyte bodies exposed to the first face to the area of the binder exposed to the first face is 0.25 to 500.

Description

  The present invention relates to a lithium ion conductive solid electrolyte body.

Lithium ion conductive inorganic solid electrolytes are being studied as an alternative to organic electrolytes in lithium ion secondary batteries, lithium air batteries and other electrochemical devices. This is because the inorganic solid electrolyte has no risk of leakage from the battery or ignition unlike the organic electrolyte.
For example, a solid electrolyte body in which a lithium ion conductive inorganic solid electrolyte is formed into a thin plate shape is disposed between the positive electrode and the negative electrode of a battery, thereby conducting the conduction of lithium ions between the positive electrode and the negative electrode, while conducting the electrons. It is possible to function as a separator that cuts off.
A battery separator made of a solid electrolyte is required to be as thin as possible in order to make lithium ion conduction resistance as small as possible. However, since the inorganic solid electrolyte is a brittle material, the separator made of the inorganic solid electrolyte has a problem that the thinner the separator is, the easier it is to crack or to generate a crack.
Patent Document 1 discloses a separator comprising a plurality of ion conductive solid segments, wherein each solid segment is connected by a deformable electrically insulating material.

Special table 2014-510363 gazette

As in the separator described in Patent Document 1, for example, if the solid electrolyte body is a composite solid electrolyte body of an inorganic solid electrolyte and a deformable polymer, the flexibility increases as compared with a solid electrolyte body made of an inorganic solid electrolyte. It is possible to reduce the occurrence of cracks and cracks. However, since the polymer having no ion conductivity occupies a certain proportion of the volume in the composite solid electrolyte body, the ion conductivity as a whole decreases. Moreover, when the ratio of the polymer without ion conductivity is reduced, the flexibility of the solid electrolyte body cannot be obtained sufficiently, and the generation of cracks and cracks cannot be sufficiently suppressed.
An object of the present invention is to provide a composite solid electrolyte having both flexibility and ionic conductivity.

In view of the above problems, the inventor of the present application configures a composite electrolyte body with an inorganic solid electrolyte and a binding material that binds these, and by making these configurations specific, both flexibility and ion conductivity are achieved. The composite solid electrolyte was found.
Specifically, the present invention has the following configuration.

(Configuration 1)
A composite solid electrolyte body having a first surface and a second surface for conducting lithium ions between the first surface and the second surface;
A plurality of inorganic solid electrolyte bodies having lithium ion conductivity are bonded with a binding material other than the inorganic solid electrolyte,
Some of the plurality of inorganic solid electrolyte bodies are conductive path constituting inorganic solid electrolyte bodies that constitute a lithium ion conduction path continuously from the first surface to the second surface,
The composite solid electrolyte body, wherein the ratio of the area of the plurality of inorganic solid electrolyte bodies exposed on the first surface to the area of the binding material exposed on the first surface is 0.25 or more and 500 or less.
(Configuration 2)
The composite solid electrolyte body according to Configuration 1, wherein the binding material is any resin selected from olefin, fluorine, epoxy, polyester, and polyurethane.
(Configuration 3)
The composite solid electrolyte body according to Configuration 1 or 2, wherein the binding material is a material having a type A durometer hardness of 30 or more and 90 or less as defined in JIS K6253.
(Configuration 4)
The composite solid electrolyte body in any one of the structures 1 to 3 in which the said inorganic solid electrolyte body consists of the material of the oxide lithium ion conductive solid electrolyte containing a crystal | crystallization.
(Configuration 5)
The exposed on the first surface, wherein the inorganic solid one area of the electrolyte body, the composite solid electrolyte body according to any one of the 30 × 10 ^-6 mm ² or more 500 mm ² or less is constituted from 1 to 4.
(Configuration 6)
6. The composite solid electrolyte body according to any one of configurations 1 to 5, wherein a ratio of the number of inorganic solid electrolyte bodies constituting a conduction path is 80% or more of the inorganic solid electrolyte body exposed on the first surface.
(Configuration 7)
The composite solid electrolyte body according to any one of configurations 1 to 6, wherein a distance between the first surface and the second surface is 0.05 mm or more and 5 mm or less.
(Configuration 8)
The composite solid electrolyte body according to any one of configurations 1 to 7, wherein the composite solid electrolyte body has a plate shape.
(Configuration 9)
The composite solid electrolyte body according to any one of configurations 1 to 7, wherein the composite solid electrolyte body is cylindrical.

It is a figure which shows the manufacturing method of the composite solid electrolyte body of this invention. It is a figure which shows the manufacturing method of the composite solid electrolyte body of this invention. It is a figure which shows the manufacturing method of the composite solid electrolyte body of this invention. A gray part is a binding material and a white part is an inorganic solid electrolyte body. It is a figure which shows the manufacturing method of the composite solid electrolyte body of this invention. A gray part is a binding material and a white part is an inorganic solid electrolyte body.

  The composite solid electrolyte body of the present invention becomes one composite solid electrolyte body by combining a plurality of inorganic solid electrolyte bodies with a binding material.

  The composite solid electrolyte body has at least two surfaces, a first surface and a second surface. The first surface and the second surface may be flat surfaces or curved surfaces. The composite solid electrolyte body may have a surface other than the first surface and the second surface. In this invention, the area | region divided by the ridgeline which appears on the surface of a composite solid electrolyte body is defined as one surface of a composite solid electrolyte. Examples of the form of the composite solid electrolyte body include a plate shape such as a square plate and a circular plate, and a cylindrical shape, but are not limited thereto. The first surface and the second surface of the composite solid electrolyte body are preferably the upper two surfaces having a large area.

  When the composite solid electrolyte body is used for a lithium ion battery, a lithium air battery, or other electrochemical devices, lithium ions are conducted between the first surface and the second surface. The binding material is made of a material other than a plurality of inorganic solid electrolyte bodies. Some of the plurality of inorganic solid electrolyte bodies constituting the composite solid electrolyte body continuously form a lithium ion conduction path from the first surface to the second surface of the composite solid electrolyte body. In the present invention, an inorganic solid electrolyte body that continuously forms a lithium ion conduction path from the first surface to the second surface of the composite solid electrolyte body is referred to as a conduction path configuration inorganic solid electrolyte body. The conduction path constituting inorganic solid electrolyte body is exposed on the first surface and the second surface of the composite solid electrolyte body.

  In the composite solid electrolyte body of the present invention, as described above, some of the plurality of inorganic solid electrolyte bodies continuously form a lithium ion conduction path from the first surface to the second surface of the composite solid electrolyte body. doing. Therefore, in an electrochemical device such as a lithium ion secondary battery, it has high lithium ion conductivity by using the composite solid electrolyte body of the present invention so that lithium ions are conducted between the first surface and the second surface. Lithium ions are conducted between the first surface and the second surface using only the inorganic solid electrolyte body as a conduction path. Therefore, the composite solid electrolyte body can be used as a separator having high lithium ion conductivity.

The ratio of the number of conduction path constituting inorganic solid electrolyte bodies to the plurality of inorganic solid electrolyte bodies constituting the composite solid electrolyte body of the present invention is preferably 80% or more, because high lithium ion conductivity is obtained, 85 % Or more is more preferable, and 90% or more is most preferable. A preferable upper limit of the number ratio is 100%.
The ratio of the number of conduction path constituting inorganic solid electrolyte bodies to the plurality of inorganic solid electrolyte bodies is determined by observing the cross section including the shortest path of the first surface and the second surface of the composite solid electrolyte body, The number is calculated by counting the number of conduction path constituting inorganic solid electrolyte bodies. As the region to be observed, a region in which at least ten conduction path constituting inorganic solid electrolyte bodies are observed is selected.
Note that the ratio of the number in the present invention means the ratio of the existence probability of the conductive path constituting inorganic solid electrolyte body in the composite solid electrolyte body in the limit of certainty obtained by the above calculation method, and the effect of the invention Is sufficient to satisfy the existence probability. There is no need to count the true number present in the composite solid electrolyte body.

In the composite solid electrolyte body of the present invention, the ratio of the area of the plurality of inorganic solid electrolyte bodies exposed on the first surface to the area of the binding material exposed on the first surface is 0.25 or more and 500 or less. When the value of the ratio is less than 0.25, the lithium ion conductivity per unit area between the first surface and the second surface in the composite solid electrolyte body becomes low. The value of the ratio is more preferably 1 or more and most preferably 3 or more in order to obtain high lithium ion conductivity. Moreover, when the value of the ratio exceeds 500, the composite solid electrolyte body cannot be sufficiently flexible, and cracks and cracks are likely to occur when used in an electrochemical device. The value of the ratio is more preferably 400 or less, and most preferably 300 or less in order to make it difficult for cracks and cracks to occur when used in an electrochemical device.
By setting the value of the ratio in the above-mentioned range, the lithium ion conductivity per unit area between the first surface and the second surface in the composite solid electrolyte body is increased, and the flexibility of the composite solid electrolyte body is ensured. Thus, it is possible to optimize the balance between lithium ion conductivity and flexibility in the electrochemical device.
The area of the plurality of inorganic solid electrolyte bodies exposed on the first surface refers to the sum of the projected areas on the first surface of the respective inorganic solid electrolyte bodies exposed on the first surface. It is up to the measurer to decide which of the upper two surfaces having the larger area of the composite solid electrolyte body is the first surface. Further, in determining the ratio of the area of the plurality of inorganic solid electrolyte bodies exposed on the first surface to the area of the binding material exposed on the first surface, an image of the first surface is taken in an arbitrary region. Then, the image is printed on a paper or film having a constant thickness and specific gravity, the binding material portion and the inorganic solid electrolyte body portion are separated, the weight of the paper or film is measured, and the weight ratio is calculated as the area ratio. It calculates by calculating | requiring as.
Here, the ratio of the area in the present invention means the ratio of the area in the limit of certainty obtained by the above calculation method, and in order to obtain the effect of the present invention, the limit of the certainty It is sufficient to satisfy the area ratio. It is not necessary to measure the true area ratio on the first surface of the composite solid electrolyte body.

  The binding material is preferably a material that causes a strong bond with the inorganic solid electrolyte body. When the binding material is a resin selected from olefin, fluorine, epoxy, polyester, and polyurethane, a strong bond occurs with the inorganic solid electrolyte body, and a composite solid electrolyte body having strong mechanical strength is obtained. This is preferable. Examples of the olefin resin include polypropylene.

In order to impart high lithium ion conductivity to the composite solid electrolyte, lithium ion conductivity may be imparted to the binding material itself. For example, LiBF ₄ , LiCF ₃ SO ₃ , LiSO ₃ CH ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC (SO ₂ CF ₃ ) ₃ , organic ionic polysulfide, By dissolving Li salt such as Li [B (C ₆ H ₄ O ₂ ) ₂ ], Li [B (C ₆ H ₃ FO ₂ ) ₂ ], lithium bis (trifluoromethanesulfonyl) imide in the above resin, Lithium ion conductivity can be imparted to the binding material itself.

The binding material preferably has a type A durometer hardness of 90 or less as defined in JIS K6253 in order to increase the flexibility of the composite solid electrolyte body and suppress the occurrence of cracks and cracks in the composite solid electrolyte body. More preferably, it is 90 or less, and most preferably 80 or less.
Further, the binding material preferably has a type A durometer hardness of 30 or more as defined in JIS K6253 in order to increase the strength of the composite solid electrolyte body against sharp metals such as foreign matter and nails mixed during battery manufacture. 30 or more is more preferable, and 40 or more is most preferable.
The measurement of the type A durometer hardness specified in JIS K6253 is made only with the binding material constituting the composite solid electrolyte body, and a sheet having the same thickness as that of the composite solid electrolyte body is produced, and the sheet conforms to JIS K6253. Measure hardness with a Type A durometer.

The inorganic solid electrolyte constituting the composite solid electrolyte is preferably made of a material of oxide lithium ion conductive solid electrolyte containing crystals. The reason is that it is possible to obtain a composite solid electrolyte body having high lithium ion conductivity and high chemical durability and mechanical strength.
The material of the oxide lithium ion conductive solid electrolyte containing a crystal is a lithium ion conductive perovskite crystal, a garnet crystal, a polycrystal composed of any NASICON crystal, or any of these crystals Glass ceramics containing as a crystal phase are exemplified.
As a lithium ion conductive perovskite crystal, there is La _0.55 Li _0.35 TiO ₃ (so-called LLT), for example.
Li ₇ La ₃ Zr ₂ O ₁₂ (so-called LLZ) is given as a lithium ion conductive garnet-type crystal.
As a lithium ion conductive NASICON-type crystal, Li _{1 + x + z} M _x (Ge _1-y Ti _y ) _2−x Si _z P _3−z O ₁₂ (however, 0 ≦ x ≦ 0.8, 0 ≦ y ≦ 1.0, 0.ltoreq.z.ltoreq.0.6, one or more selected from M = Al, Ga).

As a material of the oxide lithium ion conductive solid electrolyte containing crystals, Li _{1 + x + z} M _x (Ge _1-y Ti _y ) _2−x Si _z having high chemical durability and ion conductivity and easy to manufacture. Including a crystal phase of P _3-z O ₁₂ (where 0 ≦ x ≦ 0.8, 0 ≦ y ≦ 1.0, 0 ≦ z ≦ 0.6, M = Al, Ga). Glass ceramics are most preferred.
This glass ceramic can be manufactured by the following method.
First, raw materials such as H ₃ PO ₄ , Al (PO ₃ ) ₃ , Li ₂ CO ₃ , SiO ₂ , TiO ₂ , Ga ₂ O ₃ , GeO ₂ , and ZrO ₂ are appropriately selected, and in mol% based on the oxide. ,
Li ₂ O from 10% to 25%,
0.5% to 15% in total of at least one of Al ₂ O ₃ and Ga ₂ O ₃ ,
25% to 50% in total of at least one of TiO ₂ and GeO ₂ ,
SiO ₂ from 0% to 15%,
P ₂ O ₅ from 26% to 50%
A raw material is prepared so that ZrO ₂ has a composition containing each component of 0% to 10%, and is melted in a platinum crucible to obtain a glass melt. Next, the obtained glass melt is quenched by casting into a mold or water to obtain an amorphous mother glass.
Next, the amorphous glass is heat-treated to precipitate crystals. The maximum temperature of the heat treatment is preferably in the range of 800 ° C. or higher and 1100 ° C. or lower.
Through the above steps, Li _{1 + x + z} M _x (Ge _1−y Ti _y ) _2−x Si _z P _3−z O ₁₂ (however, 0 ≦ x ≦ 0.8, 0 ≦ y ≦ 1.0, 0 ≦ z It is possible to produce glass ceramics including a crystal phase of ≦ 0.6, one or more selected from M = Al and Ga.

Exposed on the first surface of the composite solid electrolyte body, an inorganic solid one area of the electrolyte body, if it is 30 × 10 ^-6 mm ² or more 500 mm ² or less, electrochemical such as lithium air batteries and lithium ion secondary batteries When used in a device, the lithium ion conductivity in the surface of the composite solid electrolyte body becomes uniform to a certain degree, which is preferable in terms of battery life, and the flexibility in the surface of the composite solid electrolyte body becomes uniform to a certain degree, which is preferable. . Exposed on the first surface of the composite solid electrolyte body, one area of the inorganic solid electrolyte body, more preferably 30 × 10-4mm ² or more, most preferably 100 × ¹⁰ -4 mm ² or more. Exposed on the first surface of the composite solid electrolyte body, one area of the inorganic solid electrolyte body, more preferably 300 mm ² or less, 200 mm ² or less being most preferred. In addition, one area of the inorganic solid electrolyte body is a projected area on the first surface of a portion exposed on the first surface of one inorganic solid electrolyte body.

The inorganic solid electrolyte body which comprises a composite solid electrolyte body can be produced with the following method.
The first is a method in which a lump (bulk body) of an oxide lithium ion conductive solid electrolyte material containing crystals is formed into a desired shape by performing mechanical processing such as cutting, cutting, grinding, and polishing.
The second method is a method of pulverizing a material of oxide lithium ion conductive solid electrolyte containing crystals to form a granular material. Each of the powder particles becomes an inorganic solid electrolyte body. In this case, if necessary, the particle size of the pulverized powder particles may be selected within a certain range.
Third, a powder of oxide lithium ion conductive solid electrolyte material containing crystals is mixed with a binder, a solvent, etc. to prepare a paste or slurry, which is molded into a desired shape and then sintered. is there.

  The shape of the inorganic solid electrolyte body may be a triangular prism, a quadrangular prism, other prisms, or a cylinder, but is not limited to such a geometric shape. As described above, the pulverized powder particles may be used as the shape of the inorganic solid electrolyte body as they are. However, the portions exposed on the first surface and the second surface may be processed so as to follow the surfaces.

The distance between the first surface and the second surface of the composite solid electrolyte body is to reduce the lithium ion conduction resistance while obtaining sufficient mechanical strength for use in electrochemical devices such as lithium ion secondary batteries. It is preferable that it is 0.001 mm or more and 5 mm or less. When it is smaller than 0.001 mm, it is difficult to obtain sufficient mechanical strength. When it is larger than 5 mm, it becomes difficult to obtain lithium ion conductivity necessary for use in an electrochemical device such as a lithium ion secondary battery. The lower limit of the distance between the first surface and the second surface of the composite solid electrolyte body is more preferably 0.005 mm, and most preferably 0.01 mm. The upper limit of the distance between the first surface and the second surface of the composite solid electrolyte body is more preferably 0.1 mm, and most preferably 0.5 mm.
Here, the distance between the first surface and the second surface of the composite solid electrolyte body refers to the shortest distance from any point on the first surface toward the second surface. For example, when the shape of the composite solid electrolyte body is a plate, it refers to the thickness of the plate, and when it is a cylinder, it refers to a distance that is half the difference between the outer diameter and the inner diameter of the cylinder, that is, the thickness.

The following method can be used as the method for producing the composite solid electrolyte body.
[First method]
A plurality of inorganic solid electrolyte bodies are formed into prisms or cylinders. As shown in FIG. 1 (a), these inorganic solid electrolyte bodies 1 are laminated with their orientations aligned and bonded with a bonding material 2. As shown in FIG. 1B, the composite of the binding material and the inorganic solid electrolyte body is sliced so as to cross the binding material and the inorganic solid electrolyte body, and the composite solid electrolyte body of FIG. 1C is manufactured. Can do. You may grind and polish the 1st surface and the 2nd surface as needed.

[Second method]
The composite solid electrolyte body produced in FIG. 1C is further laminated as shown in FIG. 2A and bonded with a bonding material. When stacking, the composite solid electrolyte body may be stacked so that the position of the inorganic solid electrolyte body is shifted as shown in FIG. In FIG. 2 (a), the left and right side end portions of the laminated composite solid electrolyte body are ground so that the end portions after lamination become one surface. The laminated body can be sliced as shown in FIG. 2B to produce the composite solid electrolyte body shown in FIG.

[Third method]
A plurality of inorganic solid electrolyte powders are used as inorganic solid electrolyte bodies. The particle diameter of the powder is adjusted to be approximately equal to the target thickness of the composite solid electrolyte body. The powder, the binding material, the solvent and the like are mixed to prepare a slurry. The slurry is formed to a desired thickness by a tape casting method or the like. The solvent is evaporated from the formed slurry and dried. At this time, most of the inorganic solid electrolyte bodies are in a continuous state up to the first surface and the second surface as shown in FIG.
Thereafter, as shown in FIG. 3B, the first surface and the second surface may be ground or polished as necessary to form a smooth surface.
Further, as shown in FIG. 4A, the slurry is formed to be thicker than the particle diameter of the granular material, and the first surface and the second surface are ground or polished as shown in FIG. A composite solid electrolyte body in which the inorganic solid electrolyte body is exposed on one surface and the second surface can be obtained.

Example 1
[Preparation of inorganic solid electrolyte]
H ₃ PO ₄ , Al (PO ₃ ) ₃ , Li ₂ CO ₃ , SiO ₂ and TiO ₂ were used as raw materials. These raw materials were prepared in such a manner that the composition of the inorganic solid electrolyte after production was mol% based on oxide, P ₂ O ₅ = 33.8%, Al ₂ O ₃ = 7.6%, Li ₂ O = 14.5% , SiO ₂ = 2.8%, TiO ₂ = 41.3% were weighed and mixed uniformly to obtain a mixture. The mixture was placed in a platinum pot, which was heated in an electric furnace at 1450 ° C. for 3 hours. The mixture melted into a glass melt. During the heating for 3 hours, stirring was performed several times so that the glass melt became homogeneous.
The obtained glass melt was dropped into running water to obtain flaky glass. The glass was crystallized by heat treatment at 950 ° C. for 12 hours to obtain lithium ion conductive glass ceramics. The precipitated crystal phase was confirmed to be Li1 + x + yAlxTi2-xSiyP3-yO12 (0 ≦ x ≦ 0.4, 0 <y ≦ 0.6) as the main crystal phase by powder X-ray diffraction.
The obtained glass ceramic flakes were pulverized by a ball mill, and the pulverized particles were sieved to obtain glass ceramic powder having an average particle size of 42 μm. Further, the flaky lithium ion conductivity obtained by impedance measurement was 9.4 × 10 ⁻⁴ Scm ⁻¹ at 25 ° C.

[Production of composite solid electrolyte]
The ethylene / vinyl alcohol resin and the glass ceramic powder were adjusted to a volume ratio of 20:80 and kneaded. The kneaded composite solid electrolyte was hot-pressed and formed into a sheet having a thickness of 60 μm. The sheet was cut into 50 mm squares, and both sides were ground by grinding to a thickness of 30 μm. In the sheet, the glass ceramic powder becomes an inorganic solid electrolyte, and the ethylene / vinyl alcohol resin constitutes the binding material.
When one surface of 50 mm square of the sheet is the first surface, an SEM image of a 400 × 200 μm region of the first surface is taken, and the areas of the plurality of inorganic solid electrolyte bodies exposed on the first surface are measured. The ratio to the area of the bonding material exposed on one side was calculated to be 4. In the same observation, one area of the inorganic solid electrolyte body exposed on the first surface was 3 × 10 ⁻⁴ mm ² in number average. Further, when the cross section of the sheet was observed with a SEM in a field of 100 × 50 μm, the ratio of the number of the conductive path constituting inorganic solid electrolyte bodies to the inorganic solid electrolyte bodies observed in the region was 87%.
The lithium ion conductivity obtained by impedance measurement was 5.6 × 10 ⁻⁴ Scm ⁻¹ at 25 ° C.
Only the ethylene / vinyl alcohol resin used in the sheet was finished to 30 μm, and the hardness was measured with a type A durometer in accordance with JIS K6253. As a result, the type A durometer hardness was 90.

(Example 2)
As raw materials, H ₃ PO ₄ , Al (PO ₃ ) ₃ , Li ₂ CO ₃ , SiO ₂ , TiO ₂ , GeO ₂ and ZrO ₂ were used. These raw materials are composed of mol% in terms of oxides of the inorganic solid electrolyte after production, Li ₂ O = 14.4%, Al ₂ = O ₃ 8.1%, SiO ₂ = 1.7%, P ₂ O ₅ = 37.9%, TiO ₂ = 17.0%, GeO ₂ = 19.8%, ZrO ₂ = 1.1% were weighed and mixed uniformly to obtain a mixture. The mixture was placed in a platinum pot, which was heated in an electric furnace at 1350 ° C. for 3 hours. The mixture melted into a glass melt. During the heating for 3 hours, stirring was performed several times so that the glass melt became homogeneous. Thereafter, the obtained glass melt was poured from a platinum pipe attached to a pot into a metal mold heated to 300 ° C. The platinum pipe is heated to adjust the temperature of the glass melt. Glass that has been poured into a mold and allowed to cool until the surface temperature reaches 600 ° C. or lower, then placed in an electric furnace heated to 550 ° C., and slowly cooled to room temperature to remove thermal strain. A block was made.
The glass block was cut into 100 mm × 5 mm × 1.2 mm and then crystallized by heat treatment at 900 ° C. for 12 hours to obtain the target glass ceramic.
The precipitated crystal phase was confirmed to be Li1 + x + yAlx (Ti + Ge) 2-xSiyP3-yO12 (0 ≦ x ≦ 0.4, 0 <y ≦ 0.6) as the main crystal phase by powder X-ray diffraction. Moreover, the ionic conductivity of the glass ceramic obtained by measuring impedance was 1.2 × 10 ⁻⁴ Scm ⁻¹ at 25 ° C.
The glass ceramic was laminated by thermocompression bonding using a PFA film (25 μm) to prepare a 38 mm thick composite solid electrolyte body. It was cut into a thickness of 0.6 mm with a wire saw and molded into a 38 × 100 × 0.6 mm sheet.
In the sheet, 0.6 mm × 1.2 mm × 100 mm glass ceramics becomes the inorganic solid electrolyte body, and PFA constitutes the binding material. When one of the 100 mm × 38 mm surfaces of the sheet is the first surface, an SEM image of a 5 × 2.5 mm region of the first surface is taken, and the areas of the plurality of inorganic solid electrolyte bodies exposed on the first surface Of the area of the bonding material exposed on the first surface was 99. Further, in the same observation, one area of the inorganic solid electrolyte body exposed on the first surface was observed by SEM in a 1 × 0.5 mm field of view of the solid electrolyte region of the cross section of the sheet. The ratio of the number of conduction path constituting inorganic solid electrolyte bodies to the inorganic solid electrolyte bodies observed in the region was 100%.
The ionic conductivity determined by impedance measurement was 0.9 × 10 ⁻⁴ Scm ⁻¹ at 25 ° C.
When only a PFA film used for the sheet was laminated to a thickness of 0.6 mm and the hardness was measured with a type A durometer in accordance with JIS K6253, the type A durometer hardness was 60.

(Example 3)
H ₃ PO ₄ , GeO ₂ , Al (PO ₃ ) ₃ , and Li ₂ CO ₃ were used as raw materials. The composition is such that P ₂ O ₅ = 37.5%, GeO ₂ = 35.0%, Al ₂ O ₃ = 7.5%, Li ₂ O = 20.0% in mol% in terms of oxide. The mixture was weighed and mixed uniformly, and then placed in a platinum crucible and dissolved by heating in an electric furnace. The temperature was raised to 1300 ° C. in an electric furnace, and melting was performed at that temperature for 3 hours. Thereafter, the molten glass was cast on an iron plate previously heated to 300 ° C. to produce a uniform plate-like glass. And it annealed at 520 degreeC for 2 hours in order to remove the distortion of glass. The glass thus obtained was cut into a size of 50 mm × 50 mm × 2 mm and heat treated at 800 ° C. for 12 hours to obtain a dense glass ceramic.
The precipitated crystal phase was confirmed to be Li _{1 + X} Al _X Ge _2-X (PO ₄ ) ₃ by powder X-ray diffraction. The glass ceramic exhibited a high lithium ion conductivity of 4.0 × 10 ⁻⁴ S / cm at 25 ° C.
The glass ceramic was bonded to an epoxy resin by thermocompression bonding to prepare a composite solid electrolyte body having a thickness of 40 mm. Cut to a thickness of 0.8 mm with a wire saw and molded into a 40 x 50 x 0.8 mm sheet. In the same sheet, 0.6 mm x 2 mm x 50 mm glass ceramic becomes an inorganic solid electrolyte body, and epoxy Resin constitutes the binding material. When one of the 50 mm × 40 mm surfaces of the sheet is the first surface, an SEM image of a 5 × 2.5 mm region of the first surface is taken, and the areas of the plurality of inorganic solid electrolyte bodies exposed on the first surface Of the area of the bonding material exposed on the first surface was 99. Moreover, when the cross section of the sheet was observed with a SEM in a field of 2 × 1 mm, the ratio of the number of the inorganic solid electrolyte bodies constituting the conduction path to the inorganic solid electrolyte bodies observed in the region was 100%.
The ionic conductivity determined by impedance measurement was 0.9 × 10 ⁻⁴ Scm ⁻¹ at 25 ° C.
Only the epoxy resin used for the sheet was finished to 0.8 mm, and the hardness was measured with a type A durometer in accordance with JIS K6253. As a result, the type A durometer hardness was 20.

(Comparative Example 1)
The glass flakes of Example 1 were pulverized by a ball mill and adjusted to an average particle size of 18 μm and a maximum particle size of 29 μm. Using this powder, a 25 μm sheet composite electrolyte was obtained in the same manner as in Example 1. When one surface of 50 mm square of the sheet is the first surface, an SEM image of a 400 × 200 μm region of the first surface is taken, and the areas of the plurality of inorganic solid electrolyte bodies exposed on the first surface are measured. The ratio to the area of the bonding material exposed on one side was determined to be 2. In the same observation, one area of the inorganic solid electrolyte body exposed on the first surface was 1.0 × 10 ⁻³ mm ² in number average. Further, when the cross section of the sheet was observed with a SEM in a field of view of 100 × 50 μm, the ratio of the number of the conductive path constituting inorganic solid electrolyte bodies to the inorganic solid electrolyte bodies observed in the region was less than 1%. . The ionic conductivity obtained from the impedance measurement was 2 × 10 ⁻⁸ Scm ⁻¹ .

1 Inorganic solid electrolyte body 2 Binding material

Claims (9)

A composite solid electrolyte body having a first surface and a second surface for conducting lithium ions between the first surface and the second surface;
A plurality of inorganic solid electrolyte bodies having lithium ion conductivity are bonded with a binding material other than the inorganic solid electrolyte,
Some of the plurality of inorganic solid electrolyte bodies are conductive path constituting inorganic solid electrolyte bodies that constitute a lithium ion conduction path continuously from the first surface to the second surface,
The composite solid electrolyte body, wherein the ratio of the area of the plurality of inorganic solid electrolyte bodies exposed on the first surface to the area of the binding material exposed on the first surface is 0.25 or more and 500 or less.   2. The composite solid electrolyte body according to claim 1, wherein the binding material is a resin selected from olefin, fluorine, epoxy, polyester, and polyurethane.   The composite solid electrolyte body according to claim 1 or 2, wherein the binding material is a material having a type A durometer hardness of 30 or more and 90 or less as defined in JIS K6253.   The composite solid electrolyte body according to any one of claims 1 to 3, wherein the inorganic solid electrolyte body is made of an oxide lithium ion conductive solid electrolyte material containing crystals. The exposed on the first surface, wherein the inorganic one area of the solid electrolyte body, a composite solid electrolyte body according to any one of the 30 × 10 ^-6 mm ² or more 500 mm ² from the claim 1 or less 4.   The composite solid electrolyte body according to any one of claims 1 to 5, wherein, of the inorganic solid electrolyte body exposed on the first surface, the ratio of the number of inorganic solid electrolyte bodies constituting the conduction path is 80% or more.   The composite solid electrolyte body according to any one of claims 1 to 6, wherein a distance between the first surface and the second surface is 0.05 mm or more and 5 mm or less.   The composite solid electrolyte body according to claim 1, wherein the composite solid electrolyte body has a plate shape.   The composite solid electrolyte body according to claim 1, wherein the composite solid electrolyte body is cylindrical.