JP2008226666A - Manufacturing method of solid electrolyte structure for all-solid battery, and manufacturing method of all-solid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte structure for an all-solid battery capable of reducing connection resistance at the connection interface with an electrode. <P>SOLUTION: This is a manufacturing method of a solid electrolyte structure for the all-solid battery in which a sheet laminate 11 is obtained by laminating a second green sheet 13 in which a solid electrolyte of powder shape and a pore-forming agent are formed in a sheet shape on at least one surface of a first green sheet 12 in which the solid electrolyte of powder shape is formed in a sheet shape, and by calcining the sheet laminate 11 so obtained, a solid electrolyte porous body consisting of the second green sheet 13 is adhered and integrally formed on at least one surface of a solid electrolyte dense body consisting of the first green sheet 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a solid electrolyte structure for an all-solid battery, and a method for producing an all-solid battery. More specifically, a method for manufacturing a solid electrolyte structure for an all solid state battery capable of reducing connection resistance at the connection interface with the electrode, and a method for manufacturing an all solid state battery using such a solid electrolyte structure About.

  In recent years, with the development of portable devices such as personal computers and mobile phones, the demand for batteries as power sources has been greatly expanded. In batteries used for such applications, liquid electrolytes (electrolytic solutions) such as organic solvents are conventionally used as a medium for moving ions. A battery using such an electrolytic solution may cause problems such as leakage of the electrolytic solution.

  In order to solve such a problem, development of an all-solid battery in which a solid electrolyte is used instead of a liquid electrolyte and all other elements are made of solid has been underway. In such an all-solid battery, since the electrolyte is solid, there is no fear of leakage that induces ignition and the like, and problems such as deterioration of battery performance due to corrosion hardly occur. In particular, all-solid lithium secondary batteries have been actively studied in various fields as secondary batteries that can easily have a high energy density (see, for example, Patent Document 1).

  Such an all-solid battery is excellent in safety and the like as described above, but since the electrolyte is all solid, the ionic conductivity of the solid electrolyte itself is improved and the interface between the electrode and the electrolyte is connected. Reducing the connection resistance (impedance) at the time has been a major issue.

  For example, in a conventional liquid lithium ion secondary battery, since the electrolyte is liquid, the electrolyte penetrates between the particles of the solid electrode, and the junction area between the solid electrode and the electrolyte is simply the surface of the solid electrode. This is not the area but the area of the specific surface of the solid electrode. In addition, regarding the connection between the solid electrode and the electrolyte, a good state can be ensured if the electrolyte sufficiently permeates the solid electrode.

  On the other hand, in the above-described all solid state battery, since both the electrode and the electrolyte are solid, the bonding area between them depends on the area where both particles are in contact. In the state where the sintering temperature of the electrode and the electrolyte is low and sintering is not progressing, the connection between these particles is almost point contact, but as the sintering progresses and the fusion between the particles proceeds, the bonding area (contacts) The area) is enlarged, and the connection resistance (impedance) at the connection interface is reduced. That is, the connection resistance decreases as the connecting portion (necking) between particles becomes thicker. However, in the firing temperature range where sufficient necking is obtained, it is necessary to take into account the reactivity between both materials, and a substantial bonding area is not easily obtained.

  Conventionally, when making a prototype of an all-solid battery, an electrode material (for example, an active material precursor) is applied on a flat surface of a solid electrolyte, and this is baked to form an electrode. In this case, the bonding area does not exceed the plane area of the region where the electrode is formed. In practice, the total area of contact between the electrode and the solid electrolyte particles is generally smaller than the surface area of the electrode.

  For this reason, in order to reduce the connection resistance (impedance) at the connection interface between the electrode and the solid electrolyte, for example, an all-solid battery in which a solid electrolyte is interposed between positive and negative active material particles is disclosed. (For example, refer to Patent Document 2). Specifically, each of the positive and negative electrodes is formed by firing a green sheet obtained by forming a slurry in which an active material and an electrolyte are mixed into a sheet shape, and is disposed between the electrodes. The (solid electrolyte layer) is formed by firing a sheet formed only of a solid electrolyte material. The positive electrode, the solid electrolyte layer, and the negative electrode thus obtained are subjected to pressure contact or pressure firing to produce an all-solid battery. Such an all-solid-state battery is said to be able to form an electrolyte network in the active material of the positive and negative electrodes.

JP-A-5-205741 JP 2000-311710 A

  However, in the case of the all-solid-state battery manufacturing method of Patent Document 2, when the sintering temperatures of the active material and the solid electrolyte to be used are different, the connection resistance (impedance) at the connection interface cannot be reduced, which is good. There was a problem that it was not possible to obtain proper charge / discharge characteristics. As the cause of this, the all-solid-state battery of Patent Document 2 forms an electrode using a material in which a solid electrolyte is mixed with an active material of positive and negative electrodes, but the sintering temperature of the active material and the solid electrolyte is different. This is presumably because a material having a high sintering temperature could not form a sufficient connecting portion (necking).

  On the other hand, when the sintering temperature of the active material and the solid electrolyte is designed to be close, this time, a reaction occurs between the two materials, and different materials are generated between the materials, resulting in an increase in impedance. There was a problem.

  Further, in the charge / discharge process of the secondary battery, the active material repeatedly expands and contracts when ions enter and leave the active material constituting the electrode. For example, in the case of a liquid secondary battery, since a liquid electrolyte having fluidity is used, the stress accompanying the expansion and contraction is relaxed, and there is a problem in the connection interface between the electrode and the electrolyte. However, in conventional all-solid-state batteries, the stress associated with this expansion and contraction acts directly on the connection interface, causing cracks and the like at the connection interface and peeling, hindering charge / discharge operation, and peeling. When it becomes larger, there is also a problem that the function as a battery is not performed.

  The present invention has been made in view of such problems of the prior art, and the object of the present invention is to reduce the connection resistance at the connection interface with the electrode and to charge and discharge the process. A manufacturing method for manufacturing a solid electrolyte structure for an all-solid battery capable of effectively dispersing and mitigating stress caused by expansion and contraction of an active material in the present invention, and a manufacturing method for an all-solid battery .

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have obtained a green sheet formed using a powdered solid electrolyte and a green sheet formed using a powdered solid electrolyte and a pore former. By stacking and firing the laminate, the solid electrolyte has a solid electrolyte dense body and a solid electrolyte porous body, and the solid electrolyte porous body is integrally formed on at least one surface of the solid electrolyte dense body. It has been found that the above problem can be achieved by a production method for producing a solid electrolyte structure, and the present invention has been completed.

  That is, according to this invention, the manufacturing method of the solid electrolyte structure for all-solid-state batteries shown below, and the manufacturing method of all-solid-state battery are provided.

[1] A solid electrolyte structure for an all-solid battery having a solid electrolyte dense body and a solid electrolyte porous body, wherein the solid electrolyte porous body is integrally formed on at least one surface of the solid electrolyte dense body. A method for producing a step of forming a powdery solid electrolyte into a sheet to obtain a first green sheet, and forming a powdery solid electrolyte and a pore former into a sheet to form a second green A step of obtaining a sheet; a step of obtaining a sheet laminate by laminating the second green sheet on at least one surface of the obtained first green sheet; and firing the obtained sheet laminate. Accordingly, the solid electrolyte porous body made of the second green sheet is fixed to and integrated with at least one surface of the solid electrolyte dense body made of the first green sheet. Method for producing a solid electrolyte structure for all-solid-state battery comprising a step of obtaining a solid electrolyte structure for a body cell, a.

[2] The all-solid-state battery according to [1], wherein the second green sheet is formed using a material powder in which the pore-forming material is contained in a volume ratio of 1 or more with respect to the solid electrolyte. For producing a solid electrolyte structure for use in an automobile.

[3] In the above [1] or [2], particles having an average particle diameter larger than that of the solid electrolyte used for forming the first green sheet are used as the solid electrolyte used for forming the second green sheet. The manufacturing method of the solid electrolyte structure for all-solid-state batteries as described.

[4] Any of [1] to [3], wherein the solid electrolyte having an average particle diameter of 5 μm or less is used as the solid electrolyte used for forming the first green sheet and the second green sheet. The manufacturing method of the solid electrolyte structure for all-solid-state batteries as described.

[5] As the solid electrolyte used for forming the first green sheet and the second green sheet, a titanium oxide type solid electrolyte or a solid electrolyte composed of a NASICON type phosphoric acid compound is used [1] The manufacturing method of the solid electrolyte structure for all-solid-state batteries in any one of-[4].

[6] A solid electrolyte structure for an all-solid battery is obtained by the method for producing a solid electrolyte structure for an all-solid battery according to any one of [1] to [5], and the obtained solid-electrolyte structure is obtained. In the pores of the solid electrolyte porous body in the solid electrolyte structure, a fine particle active material, a sol active material, a gel active material, a fine particle active material precursor, a sol active material precursor And a method for producing an all-solid battery comprising a step of forming an electrode active material in the pores of the solid electrolyte porous body by filling at least one selected from the group consisting of a gel-like active material precursor.

[7] At least one selected from the group consisting of the fine particle active material and the fine particle active material precursor in the pores of the solid electrolyte porous body in the solid electrolyte structure for an all solid state battery. And filling the pores of the solid electrolyte porous body with at least one selected from the group consisting of the sol-like active material and the sol-like active material precursor. The method for producing an all-solid-state battery according to [6], wherein the electrode active material is formed on the electrode.

[8] The solid electrolyte porous body is formed on both surfaces of the solid electrolyte dense body by the method for producing a solid electrolyte structure for an all-solid battery according to any one of [1] to [5]. A plurality of solid electrolyte structures for an all-solid battery are formed, and in the obtained solid electrolyte structure for an all-solid battery, a fine particle active material and a sol-like active material are placed in the pores of the solid electrolyte porous body. The solid electrolyte porous material is filled with at least one selected from the group consisting of a substance, a gel active material, a fine particle active material precursor, a sol active material precursor, and a gel active material precursor A step of obtaining an active material-filled solid electrolyte structure in which an electrode active material made of an active material is formed in the pores of the body, and a plurality of the obtained active material-filled solid electrolyte structures are separated via a current collector And stacking them so that they are electrically in series Method for manufacturing an all-solid battery unit with, the.

  According to the method for producing a solid electrolyte structure for an all-solid-state battery of the present invention, a solid electrolyte structure capable of realizing good charge / discharge characteristics by reducing the connection resistance (impedance) at the connection interface with the electrode is simplified. And it can be manufactured at low cost. Moreover, the manufacturing method of the solid electrolyte structure for all-solid-state batteries of this invention is excellent in productivity, and can manufacture the solid electrolyte structure for all-solid-state batteries industrially.

  In addition, the method for producing an all-solid battery according to the present invention can generate a small electric potential with a small size using the solid electrolyte structure obtained by the method for producing a solid electrolyte structure for an all-solid battery according to the present invention. All-solid-state batteries can be manufactured. This is because a solid electrolyte is used, and even when a plurality of battery cells are stacked in a single battery package, unlike a liquid electrolyte, the electrolyte can be formed without short-circuiting. Therefore, a configuration as such a battery unit (a stacked body of battery cells) is possible. Furthermore, the method for producing an all-solid battery unit is a battery unit in which a plurality of active material-filled solid electrolyte structures are stacked using the solid electrolyte structure obtained by the method for producing a solid electrolyte structure for an all-solid battery of the present invention. Therefore, it is possible to manufacture an all-solid-state battery unit that is small and capable of generating an extremely high potential.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below, but the present invention is not limited to the following embodiments and is based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. In addition, it should be understood that modifications, improvements, and the like appropriately added to the following embodiments also fall within the scope of the present invention.

[1] Method for producing solid electrolyte structure for all solid state battery:
First, an embodiment of a method for producing a solid electrolyte structure for an all-solid battery according to the present invention (hereinafter sometimes simply referred to as “a method for producing a solid electrolyte structure”) will be specifically described. Here, FIG. 1 is a perspective view showing a solid electrolyte structure obtained by one embodiment of the method for producing a solid electrolyte structure of the present invention, and FIG. 2 is an A- of the solid electrolyte structure shown in FIG. It is a figure which shows A 'cross section.

  The method for producing a solid electrolyte structure of the present embodiment includes a solid electrolyte dense body 2 and a solid electrolyte porous body 3 as shown in FIGS. 1 and 2, and the solid electrolyte porous body 3 is a solid electrolyte dense body. Producing a solid electrolyte structure for an all-solid battery integrally formed on at least one surface of the body 2 (in FIG. 1 and FIG. 2, both surfaces of a plate-like (sheet-like) solid electrolyte dense body 2) It is a method to do.

  As shown in FIG. 3, the method for producing the solid electrolyte structure of the present embodiment includes a step of obtaining a first green sheet 12 by forming a powdery solid electrolyte into a sheet, and as shown in FIG. 4. A step of obtaining a second green sheet 13 by forming a powdered solid electrolyte and a pore-forming agent into a sheet, and at least one surface of the obtained first green sheet 12 as shown in FIG. (In FIG. 5, the process of laminating the second green sheet 12 on both surfaces of the first green sheet 12 to obtain the sheet laminate 11 and firing the obtained sheet laminate 11) 1 and 2, the second green sheet 13 (see FIG. 5) is formed on at least one surface of the solid electrolyte dense body 2 made of the first green sheet 12 (see FIG. 5). Solid electrolyte consisting of many Body 3 is a method for producing a solid electrolyte structure for all-solid-state battery and a step of obtaining a solid electrolyte structure 1 for all-solid-state cell formed by integrally formed by fixing.

  As described above, the method for producing the solid electrolyte structure of the present embodiment is obtained by firing a sheet laminate formed using two different types of green sheets (first and second green sheets), thereby producing a solid electrolyte. The solid electrolyte structure 1 for an all-solid battery in which the dense body 2 and the solid electrolyte porous body 3 are integrally formed can be manufactured.

  Such a solid electrolyte structure 1 includes a solid electrolyte dense body 2 that is a substantial solid electrolyte portion, and a solid electrolyte porous body 3 that has a large specific surface area and can increase a bonding area with an active material. Is a laminated body integrated by firing, and the active material is filled in the pores 4 of the solid electrolyte porous body 3 to form an electrode active material, thereby reducing the connection resistance (impedance) at the connection interface. Good charge / discharge characteristics can be realized.

  In the present invention, since the solid electrolyte dense body and the solid electrolyte porous body can be integrally fired and integrated in the state of being laminated and integrated, they can be formed by one firing, and the process can be shortened and the cost can be reduced.

  For example, unlike the production method of the present invention, when a solid electrolyte porous body is retrofitted on a solid electrolyte dense body fired body, the solid electrolyte porous body is printed on the solid electrolyte dense body fired body. The solid electrolyte dense body needs to have a certain degree of rigidity. In the present invention, the rigidity of the portion constituting the solid electrolyte dense body is not required. On the other hand, since the solid electrolyte porous body (second green sheet) is laminated and integrated, it is handled in a thick state as a total thickness. And since a sheet laminated body is produced by laminating green sheets, the flatness of the surface of the obtained solid electrolyte porous body can be ensured, and the contact with the collector electrode can be improved.

  For this reason, the solid electrolyte porous body required to increase the amount of active material to be filled in the electrode portion necessary for improving the battery capacity is thickened, while the solid electrolyte which is the source of internal impedance Even if the dense body is thinned, it can be easily realized without increasing the process difficulty, and as a result, a great effect can be obtained in reducing the impedance of the solid electrolyte dense body.

[1-1] Configuration of solid electrolyte structure for all-solid battery:
Here, the configuration of the solid electrolyte structure manufactured by the method for manufacturing the solid electrolyte structure of the present embodiment (hereinafter sometimes referred to as “the present solid electrolyte structure”) will be described. The above-mentioned “solid electrolyte porous body” is composed of a porous body having a large number of pores communicating three-dimensionally from the surface to the inside thereof, and the solid electrolyte structure is used as an all-solid battery. When used, an active material can be filled into the pores to form an electrode active material. On the other hand, a “solid electrolyte dense body” is one in which pores as described above do not exist without actively forming pores. Specifically, ceramics mainly composed of a solid electrolyte are relatively It is a member formed densely.

  The above-mentioned solid electrolyte dense body is obtained by firing a green sheet (first green sheet) obtained by forming a powdered solid electrolyte into a sheet shape, so that the porosity is 0 even though it is a dense body. % Of a sintered body having a denser structure than the solid electrolyte porous body. For example, in the present solid electrolyte structure, the porosity of the solid electrolyte porous body is preferably 20% or more (more preferably 30 to 60%), and the porosity of the solid electrolyte dense body is less than 10% ( More preferably, it is 0.1 to 5.0%).

  As shown in FIG. 1 and FIG. 2, the solid electrolyte dense body 2 and the solid electrolyte porous body 3 are laminated bodies integrated by firing, so that the solid electrolyte dense body 2 that is a substantial solid electrolyte portion, The connection state (necking) with the solid electrolyte porous body 3 in which the electrode active material is formed by filling the material is also improved, as compared with the conventional all solid state battery in which the electrode and the electrolyte layer are simply laminated and brought into pressure contact. Thus, the connection resistance (impedance) between the solid electrolyte dense body 2 and the solid electrolyte porous body 3 can be kept low.

  Furthermore, when the active material is filled in the pores 4 of the solid electrolyte porous body 3, the connection interface between the active material and the electrolyte is present three-dimensionally at random. Therefore, the direction of the stress generated by the expansion and contraction of the active material accompanying the charge / discharge operation is also generated randomly in three dimensions, so that the stress generated by the expansion and contraction of the active material during the charge / discharge process can be effectively dispersed and relaxed. Can do.

[1-1a] Solid electrolyte dense body:
The solid electrolyte dense body 2 of the solid electrolyte structure 1 is formed by firing a first green sheet obtained by forming a powdered solid electrolyte into a sheet. The solid electrolyte dense body 2 is disposed so as to separate the positive electrode and the negative electrode in an all-solid battery, and becomes a substantial solid electrolyte portion.

[1-1b] Solid electrolyte porous body:
The solid electrolyte porous body 3 of the present solid electrolyte structure 1 includes a second green sheet obtained by forming a powdery solid electrolyte that is the same as or different from the solid electrolyte of the first green sheet and a pore former into a sheet shape. It is fired and integrally formed on at least one surface of the solid electrolyte dense body 2. This solid electrolyte porous body 3 has a large number of pores 4 that communicate three-dimensionally from the surface to the inside thereof, and when used as an all-solid battery, an electrode is formed by filling the pores 4 with an active material. An active material can be formed.

  The solid electrolyte porous body only needs to be integrally formed on at least one surface of the solid electrolyte dense body. However, as shown in FIGS. 1 and 2, both the plate-like (sheet-like) solid electrolyte dense body 2 are formed. It is preferable that they are integrally formed on the surface. With this configuration, both the positive electrode (that is, the positive electrode active material) and the negative electrode (that is, the negative electrode active material) of the all-solid battery can be formed in the pores 4 of the respective solid electrolyte porous bodies 3. it can. Although illustration is omitted, when the solid electrolyte porous body is formed only on one surface of the solid electrolyte dense body, either the positive electrode active material or the negative electrode active material is treated as the solid electrolyte porous material. An all-solid battery is manufactured by forming the other electrode (electrode active material) on the surface of the solid electrolyte dense body opposite to the side on which the solid electrolyte porous body is formed. May be.

[1-2] Method for producing solid electrolyte structure:
Hereinafter, each process of the manufacturing method of the solid electrolyte structure of this embodiment is demonstrated more concretely.

[1-2a] First green sheet forming step:
In the method for producing a solid electrolyte structure for an all solid state battery of the present embodiment, first, as shown in FIG. 3, a powdery solid electrolyte is formed into a sheet shape to obtain a first green sheet 12. The first green sheet 12 is a green sheet that becomes the solid electrolyte dense body 2 in the solid electrolyte structure 1 shown in FIG.

There is no restriction | limiting in particular about the kind of solid electrolyte for shape | molding a 1st green sheet, What used the conventionally well-known solid electrolyte in the powder form can be used. In the method for producing a solid electrolyte structure for an all solid state battery of the present embodiment, for example, a material containing lithium as mobile ions can be suitably used. Specific solid electrolyte, _Li 3 PO _4, including, LiPON mixed with nitrogen _{Li 3 PO 4, Li 2 S} -SiS 2, Li 2 S-P 2 S 5, Li 2 S-B 2 S 3 Examples thereof include lithium ion conductive glassy solid electrolytes such as lithium ion conductive solid electrolytes obtained by doping these glasses with lithium halides such as LiI and lithium oxyacid salts such as Li ₃ PO ₄ . Among them, a titanium oxide type solid electrolyte containing lithium, titanium, and oxygen, for example, Li _x La _y TiO ₃ (where x is 0 <x <1, y is 0 <y <1) and NASICON type phosphorus A solid electrolyte made of an acid compound, for example, Li _{1 + x} Al _x Ti _2-x (PO ₄ ) ₃ (where x is 0 <x <1) is preferable because it exhibits stable performance even in firing in an oxygen atmosphere. .

As a more preferable specific example of the solid electrolyte, Li _0.35 La _0.55 TiO ₃ can be mentioned.

  When the first green sheet is formed, a binder, a dispersant, a plasticizer, and the like can be added as necessary in addition to the above-described powdered solid electrolyte.

  A conventionally known method for producing a ceramic green sheet can be used in the first green sheet forming step. For example, a slurry is prepared by adding a solvent to a material powder containing the powdered solid electrolyte and, if necessary, a binder, a plasticizer, and the like.

  In the method for producing a solid electrolyte structure of the present embodiment, it is preferable to use particles (powdered solid electrolyte) having an average particle diameter of 5 μm or less as the solid electrolyte used for forming the first green sheet. By comprising in this way, a green sheet can be shape | molded favorably and the solid electrolyte dense body formed by clogging solid electrolyte particles appropriately can be formed.

  Next, the slurry prepared using the powdered solid electrolyte is defoamed, and then the slurry is formed into a sheet using a conventionally known sheet forming method such as a doctor blade method or a reverse roll coater method.

  The thickness of the first green sheet is not particularly limited, but the first green sheet is a solid electrolyte dense body in the solid electrolyte structure, that is, a substantially solid disposed so as to separate the positive electrode and the negative electrode. Since it becomes an electrolyte portion, the all solid state battery has an internal impedance corresponding to the thickness of the first green sheet. For this reason, in order to reduce the internal impedance of the all-solid-state battery, it is preferable to reduce the thickness of the first green sheet as much as possible. Specifically, the thickness of the first green sheet is preferably 100 μm or less, and more preferably 50 μm or less.

  The lower limit of the thickness of the first green sheet is not particularly limited as long as it can be handled. In particular, when the thickness is made thin, it is possible to handle the entire Lumirror used at the time of tape coating. The thickness may be several μm, for example, 5 μm or 1 μm.

  For binders, dispersants, plasticizers, etc. contained in the material powder used for forming the first green sheet, binders, dispersants, plasticizers, etc. used in the production of conventional ceramic green sheets are suitable. Can be used.

  For example, as the binder, organic binders such as hydroxypropylmethylcellulose, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinyl alcohol can be used. These may be used individually by 1 type, and may be used in combination of 2 or more type.

  For example, as a plasticizer, di-2-ethylhexyl phthalate, di-n-butyl phthalate, diisononyl phthalate, or the like can be used. These may be used individually by 1 type, and may be used in combination of 2 or more type.

  As a solvent for preparing the slurry, for example, an organic solvent such as toluene, xylene, or butadiene can be used. These may be used individually by 1 type, and may be used in combination of 2 or more type.

[1-2b] Second green sheet forming step:
Next, as shown in FIG. 4, a powdered solid electrolyte and a pore former are formed into a sheet shape to obtain a second green sheet 13. The second green sheet 13 is a green sheet that becomes the solid electrolyte porous body 3 in the solid electrolyte structure 1 shown in FIG.

  There is no restriction | limiting in particular about the kind of solid electrolyte for shape | molding a 2nd green sheet, A conventionally well-known solid electrolyte can be used. For example, as the solid electrolyte, the substances mentioned as the solid electrolyte used for the first green sheet can be used. In addition, the solid electrolyte may be the same as or different from the solid electrolyte used for the first green sheet. In addition, since the connection resistance with the solid electrolyte dense body can be further reduced in the manufactured solid electrolyte structure, it is the same as the solid electrolyte used for the first green sheet that becomes the solid electrolyte dense body. It is preferable to use a solid electrolyte.

  A 2nd green sheet is a green sheet used as the solid electrolyte porous body 3 in the solid electrolyte structure 1 shown in FIG. For this reason, in the manufacturing method of the solid electrolyte structure of this embodiment, as shown in FIG. 4, the 2nd green sheet is shape | molded using the pore forming agent 17 with a powdery solid electrolyte.

  In addition, although there is no restriction | limiting in particular about the compounding ratio of a solid electrolyte and a pore making agent, For example, it is preferable to use what a pore making material contained 1 time or more by volume ratio with respect to solid electrolyte, and volume. It is more preferable to use a material that is contained twice or more in a ratio. By comprising in this way, the porosity of the solid electrolyte porous body in a solid electrolyte structure can be made high, and it becomes possible to ensure many pores for filling with an active material.

  When forming the second green sheet, as in the case of the first green sheet, a binder, a dispersant, a plasticizer, etc. are added to the powdered solid electrolyte and the pore-forming agent as necessary. It can be included. In the sheet forming step, a conventionally known method for producing a ceramic green sheet can be used. For example, the same method as that described in the first green sheet forming step can be used.

  The thickness of the second green sheet is not particularly limited, but the second green sheet becomes a solid electrolyte porous body in the solid electrolyte structure, and in an all-solid battery, the inside of the pores of the solid electrolyte porous body. The active material is filled into the electrode active material. Since the capacity of the battery is determined according to the amount of the electrode active material, the thickness is such that it is possible to secure a larger amount of the active material filled in the pores while realizing downsizing of the all solid state battery. It is preferable that The specific thickness of the second green sheet is preferably 10 μm or more, and more preferably 100 μm or more.

  In addition, since it is possible to increase the capacity of the battery by increasing the thickness of the second green sheet, the upper limit of the thickness of the second green sheet is not particularly limited. However, in the manufacturing method of the present embodiment, a solid electrolyte structure is manufactured using a green sheet, thereby reducing the connection resistance at the connection interface with the electrode, and a thin solid electrolyte that has been difficult to manufacture conventionally. Since the structure can be manufactured, the thickness of the second green sheet is particularly preferably 100 to 500 μm.

  As the pore-forming agent, one that can be decomposed at a temperature lower than the firing temperature when firing the sheet laminate in which the green sheets are laminated is selected. By this firing, the pore-forming agent disappears and pores of the solid electrolyte porous body are formed. Specific examples of the pore-forming agent include theobromine, graphite, wheat flour, starch, phenol resin, polymethyl methacrylate, polyethylene, polyethylene terephthalate, or foamed resin (acrylonitrile plastic balloon or the like). Instead of forming pores, these pore-forming agents themselves burn out during firing.

  In the method for producing a solid electrolyte structure of the present embodiment, it is preferable to use particles (powdered solid electrolyte) having an average particle diameter of 5 μm or less as the solid electrolyte used for forming the second green sheet.

  Further, in the method for producing a solid electrolyte structure for an all solid state battery of the present embodiment, the average particle diameter is larger than the solid electrolyte used for forming the first green sheet as the solid electrolyte used for forming the second green sheet. It is preferable to use large particles. In other words, it is preferable to use particles having an average particle size smaller than that of the solid electrolyte used for forming the second green sheet as the solid electrolyte used for forming the first green sheet.

  For example, as the solid electrolyte structure manufactured by the manufacturing method of the present embodiment, the solid electrolyte dense body is preferably denser (that is, the porosity is low), while the solid electrolyte porous body is If the mechanical strength can be ensured, it is preferable that the porosity is higher. As described above, even if the second green sheet is formed using a pore-forming agent, the first and second green sheets are formed using the same material system (solid electrolyte). Therefore, in order to increase the density of the solid electrolyte dense body made of the first green sheet (that is, to lower the porosity), for example, a method of promoting sintering by increasing the firing temperature at the time of firing Is effective, but on the other hand, the sintering of the solid electrolyte porous body made of the second green sheet also proceeds and the porosity is lowered.

  As described above, the first and second green sheets can be obtained by using particles having an average particle diameter larger than that of the solid electrolyte used for forming the first green sheet as the solid electrolyte used for forming the second green sheet. The sintering temperature of the solid electrolyte can be made different, the solid electrolyte dense body in the solid electrolyte structure can be made denser, and the decrease in the porosity of the solid electrolyte porous body can be effectively prevented Is possible.

  In addition, it is preferable that the porosity of the solid electrolyte porous body formed with a 2nd green sheet is 20% or more, and it is still more preferable that it is 30 to 60%. On the other hand, the porosity of the solid electrolyte dense layer formed by the first green sheet is preferably less than 10%, and more preferably 0.1 to 5.0%. The porosity is a value measured by a mercury intrusion method.

[1-2c] Green sheet lamination step (sheet laminate formation step):
Next, as shown in FIG. 5, the second green sheet 13 is applied to at least one surface (in FIG. 5, both surfaces of the first green sheet 12) of the obtained first green sheet 12. The sheet laminate 11 is obtained by laminating.

  When laminating the second green sheet on the surface of the first green sheet, an adhesive layer for adhering the stacked green sheets is formed on at least one surface of the first and second green sheets. . This adhesive layer can be formed by an adhesive paste prepared by adding a binder and a solvent to a solid electrolyte similar to the solid electrolyte of the first or second green sheet.

  When forming the adhesive layer, the adhesive paste is printed on at least one surface of the first and second green sheets, for example, by screen printing, and then the solvent contained in the printed adhesive paste is volatilized. Can be formed. When the solvent of the adhesive paste is volatilized, for example, a method in which the adhesive paste and the printed green sheet are put in an oven and dried can be mentioned.

  Note that the adhesive layer does not have to be formed on both surfaces of the green sheet facing each other when they are overlapped, but may be formed on one surface of the facing green sheet. Of course, it may be formed on both sides of the facing green sheet.

  After forming the adhesive layer in this manner, the second green sheet is laminated on the surface of the first green sheet (the surface on which the adhesive layer is formed). When the green sheets are stacked in this way, in order to align the green sheets, for example, the guide pins are set up and sequentially stacked through the guide holes previously opened in the green sheets, or the green sheets are marked. To improve the accuracy of stacking by attaching (marks) and sequentially stacking the markers so that they are aligned, or by sequentially stacking the green sheets in a frame having the same inner shape as the outer shape of the green sheets. it can.

  When manufacturing the solid electrolyte structure 1 in which the solid electrolyte porous body 3 is formed on both surfaces of the solid electrolyte dense body 2 as shown in FIGS. 1 and 2, both sides of the first green sheet are produced. A second green sheet is laminated on each surface. In this way, a sheet laminate can be obtained.

  In addition, when such a sheet | seat laminated body is laminated | compressed and pressure-bonded in the state heated to the temperature range which the binder which remains in an adhesive layer softens, it can obtain a favorable adhesive state. However, on the other hand, it is preferable that adhesion is not performed even if the green sheets are stacked due to the handling property of the green sheets at room temperature. For example, it is preferable to select a binder type that softens in the range of about 60 ° C to 100 ° C. After heating to 60 ° C. to 100 ° C. in this way, it is preferable to apply pressure to the laminated surface while applying a load. Thereby, the adhesion by the adhesive layer is made stronger, and a solid electrolyte structure in which the solid electrolyte dense body and the solid electrolyte porous body are integrally formed can be obtained favorably.

[1-2d] Firing step (solid electrolyte structure forming step):
Next, by firing the sheet laminate obtained in this manner, the second layer of the solid electrolyte dense body 2 made of the first green sheet as shown in FIG. 1 and FIG. A fired body (solid electrolyte structure 1 for an all solid state battery) in which the solid electrolyte porous body 3 made of the green sheet is fixed and integrally formed is obtained. As described above, in the manufacturing method of the present embodiment, the solid electrolyte dense body and the solid electrolyte porous body can be integrated by co-firing in the stacked and integrated state, so that it can be formed by one firing, shortening the process, In addition, the cost can be reduced.

  In this firing step, firing is preferably performed in a temperature range lower than the firing temperature sufficient for sintering with the solid electrolyte dense body consisting of the first green sheet alone. The temperature that is sufficient for sintering in this case refers to the temperature at which firing shrinkage begins to saturate, and the lower temperature range is specifically below the temperature that is sufficient for sintering. The point is within a range of about 100 ° C. At this time, the solid electrolyte dense body is determined by determining the firing temperature based on the balance between the degree of sintering of the solid electrolyte dense body made of the first green sheet and the degree of sintering of the solid electrolyte porous body made of the second green sheet. As described above, a solid electrolyte structure having a higher density (low porosity) and a sufficient porosity as a solid electrolyte porous body can be produced.

  Furthermore, in this firing step, when the fired body (solid electrolyte structure) obtained by firing has warpage or undulation, a weight or the like is placed on the solid electrolyte structure to obtain a solid electrolyte structure. The warpage and the undulation can be corrected by raising the temperature again to the vicinity of the previous firing temperature and refiring in the state where the pressure is applied in the thickness direction.

  As described above, the solid electrolyte dense body 2 made of the first green sheet and the solid electrolyte porous body 3 made of the second green sheet as shown in FIGS. 1 and 2 are provided. The solid electrolyte structure 1 for an all-solid battery in which the porous body 3 is integrally formed on at least one surface (both surfaces in FIG. 1) of the solid electrolyte dense body 2 can be manufactured.

[2] Method for producing all solid state battery:
Next, an embodiment of the method for producing an all solid state battery of the present invention will be specifically described. Here, FIG. 6 is a schematic diagram showing a configuration of an all solid state battery obtained by an embodiment of the method for producing an all solid state battery of the present invention. This all-solid battery 10 includes a solid electrolyte structure 1 obtained by the method for producing a solid electrolyte structure for an all-solid battery of the present invention as shown in FIG. 1 and a solid electrolyte porous body of the solid electrolyte structure 1. And an electrode active material 11 made of an active material filled in three pores 4.

  The manufacturing method of the all-solid-state battery of the present embodiment is obtained by obtaining the solid electrolyte structure for an all-solid-state battery by the method for manufacturing the solid-electrolyte structure for the all-solid-state battery of the present invention described above. In the pores of the solid electrolyte porous body in the solid electrolyte structure for an all-solid-state battery, a fine particle active material, a sol active material, a gel active material, a fine particle active material precursor, a sol An all solid state battery comprising a step of forming an electrode active material in the pores of the solid electrolyte porous body by filling at least one selected from the group consisting of an active material precursor and a gel active material precursor It is a manufacturing method. By comprising in this way, the all-solid-state battery with low connection resistance in the connection interface with an electrode can be manufactured simply and cheaply. The active material precursor is an active material when fired.

[2-1] Configuration of all-solid battery:
Here, the configuration of an all solid state battery (hereinafter, also referred to as “the all solid state battery”) manufactured by an embodiment of the method for manufacturing an all solid state battery of the present invention will be described. In the all solid state battery 10 shown in FIG. 6, solid electrolyte porous bodies 3 (3a, 3b) are respectively formed on both surfaces of the solid electrolyte dense body 2 of the solid electrolyte structure 1, and one solid electrolyte porous body is formed. A positive electrode active material 11a is formed by the active material filled in the pores 4 of 3a, and a negative electrode active material 11b is formed by the active material filled in the pores 4 of the other solid electrolyte porous body 3b. Note that a positive electrode collector electrode 14 is electrically connected to the positive electrode active material 11a. A negative electrode collector 15 is electrically connected to the negative electrode active material 11b.

  In this all solid state battery 10, the solid electrolyte dense body 2 of the solid electrolyte structure 1 as shown in FIG. 1 becomes a substantial solid electrolyte portion in the all solid state battery 10, and the solid electrolyte dense body 2 is sandwiched between the solid electrolyte dense body 2. Since the positive electrode active material 11a and the negative electrode active material 11b made of an active material filled in the pores 4 having a large specific surface area of the electrolyte porous body 3 are disposed, the connection resistance (impedance) at the connection interface is reduced. Thus, good charge / discharge characteristics can be realized.

  Furthermore, since the solid electrolyte dense body 2 and the solid electrolyte porous body 3 constituting the solid electrolyte structure 1 are integrally fired, the solid electrolyte dense body 2 that is a substantial solid electrolyte portion, and the active material The connection state (necking) with the solid electrolyte porous body 3 that is filled to form an electrode active material is also improved, compared with a conventional all-solid battery in which an electrode and an electrolyte layer are simply stacked and brought into pressure contact, The connection resistance (impedance) between the solid electrolyte dense body 2 and the solid electrolyte porous body 3 can also be kept low.

  In the all solid state battery 10 shown in FIG. 6, the solid electrolyte porous body 3 (3a, 3b) is formed on both surfaces of the plate-like (sheet-like) solid electrolyte dense body 2, respectively. The solid electrolyte porous body is formed only on one surface of the solid electrolyte dense body, and either the positive electrode active material or the negative electrode active material is activated by the active material filled in the pores of the solid electrolyte porous body. A material (for example, positive electrode active material) is formed, and the other electrode (for example, negative electrode (negative electrode active material) formed separately is formed on the surface of the solid electrolyte dense body opposite to the side on which the solid electrolyte porous body is formed. )) May be provided. Thus, the all-solid-state battery provided with the solid electrolyte structure in which the solid electrolyte porous body is formed only on one surface of the solid electrolyte dense body may be used.

[2-1a] Solid electrolyte structure:
As shown in FIG. 6, the solid electrolyte structure 1 used for the all-solid battery 10 is a solid electrolyte structure manufactured by the method for manufacturing a solid electrolyte structure for an all-solid battery according to the present invention described above. 1 (see FIG. 1). In addition, about the kind of solid electrolyte which comprises the solid electrolyte dense body 2 and the solid electrolyte porous body 3 of the solid electrolyte structure 1, it selects suitably according to the kind of active material which comprises the positive electrode active material 11a and the negative electrode active material 11b. can do.

  In the all solid state battery 10, it is preferable that the solid electrolyte constituting the solid electrolyte structure 1 has a higher sintering temperature than the active material constituting the electrode active material 11. By comprising in this way, the reactivity between both materials at the time of each baking is suppressed.

[2-1b] Electrode active material:
As shown in FIG. 6, the electrode active material 11 of the all solid state battery 10 is at least one of a positive electrode active material 11a and a negative electrode active material 11b (in FIG. 6, both of the positive electrode active material 11a and the negative electrode active material 11b). ) Is formed of an active material filled in the pores 4 of the solid electrolyte porous body 3 of the solid electrolyte structure 1. Such an electrode active material 11 can be formed by filling the pores 4 of the solid electrolyte porous body 3 with at least one selected from the group consisting of an active material and an active material precursor.

  Further, when the solid electrolyte porous body is formed only on one surface of the solid electrolyte dense body of the solid electrolyte structure, one electrode active material is an active material filled in the pores of the solid electrolyte porous body. The other electrode (electrode active material) is formed by forming an electrode material containing an active material into a thin film or sheet having a predetermined thickness. For example, the other electrode active material is an electrode active material manufactured by a conventionally known method such as a press method, a doctor blade method, or a roll coater method, and is deposited by, for example, sputtering method or heating a deposition source by resistance. A solid electrolyte porous body of a solid electrolyte dense body by a resistance heating vapor deposition method, an ion beam vapor deposition method in which a vapor deposition source is heated by an ion beam, or an electron beam vapor deposition method in which a vapor deposition source is heated and vaporized by an electron beam. It can be disposed on the surface opposite to the side on which the body is formed.

The positive electrode active material 11a as shown in FIG. 6 is formed of a positive electrode active material (positive electrode active material). There is no restriction | limiting in particular about the kind of positive electrode active material, The positive electrode active material used for a conventionally well-known all-solid-state battery can be used. In particular, when a metal oxide is used as the positive electrode active material, the secondary battery can be sintered in an oxygen atmosphere. Specific examples of such a positive electrode active material include manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide (for example, Li _x Mn ₂ O ₄ or Li _x MnO ₂ ), and lithium nickel composite. Oxide (for example, Li _x NiO ₂ ), lithium cobalt composite oxide (for example, Li _x CoO ₂ ), lithium nickel cobalt composite oxide (for example, LiNi _1-y Co _y O ₂ ), lithium manganese cobalt composite oxide _{(e.g., LiMn y Co 1-y O} 2), spinel type lithium-manganese-nickel composite oxide _{(e.g., Li x Mn 2-y Ni} y O 4), lithium phosphates having an olivine structure _(e.g., Li x FePO _{4, Li x Fe 1-y} Mn y PO 4, Li x CoPO 4), NASICON structure And lithium phosphate compounds having a structure (for example, Li _x V ₂ (PO ₄ ) ₃ ), iron sulfate (Fe ₂ (SO ₄ ) ₃ ), vanadium oxide (for example, V ₂ O ₅ ), and the like. . These may be used alone or in combination of two or more. In these chemical formulas, x and y are preferably in the range of 0-1.

  In addition, the positive electrode active material can include a conductive additive as appropriate in addition to the positive electrode active material. Examples of the conductive assistant include acetylene black, carbon black, graphite, various carbon fibers, and carbon nanotubes.

More preferable specific examples of the positive electrode active material include LiCoO ₂ , Li _x Mn ₂ O ₄ , and Li _x MnO ₂ .

  The negative electrode active material 11b is formed of a negative electrode active material (negative electrode active material). There is no restriction | limiting in particular about the kind of negative electrode active material, The negative electrode active material used for a conventionally well-known all-solid-state battery can be used. Examples thereof include carbon, metal compounds, metal oxides, Li metal compounds, Li metal oxides (including lithium-transition metal composite oxides), boron-added carbon, graphite, and compounds having a NASICON structure. These may be used alone or in combination of two or more.

Examples of the carbon include conventionally known carbon materials such as graphite carbon, hard carbon, and soft carbon. Examples of the metal compound include LiAl, LiZn, Li ₃ Bi, Li ₃ Cd, Li ₃ Sd, Li ₄ Si, Li _4.4 Pb, Li _4.4 Sn, and Li _0.17 C (LiC ₆ ). be able to. The metal _{oxides, SnO, SnO 2, GeO,} GeO 2, In 2 O, In 2 O 3, PbO, PbO 2, Pb 2 O 3, Pb 3 O 4, Ag 2 O, AgO, Ag 2 O ₃ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , SiO, ZnO, CoO, NiO, TiO ₂ and FeO. Examples of the Li metal compound include Li ₃ FeN ₂ , Li _2.6 Co _0.4 N, Li _2.6 Cu _0.4 N, and the like. Examples of the Li metal oxide (lithium-transition metal composite oxide) include a lithium-titanium composite oxide represented by Li ₄ Ti ₅ O ₁₂ . Examples of the boron-added carbon include boron-added carbon and boron-added graphite.

In addition to the negative electrode active material, the negative electrode active material can appropriately include a conductive additive. As the conductive auxiliary agent, the same conductive auxiliary agent as described in the above positive electrode active material can be suitably used. Examples of the compound having a NASICON structure include lithium phosphate compounds (such as Li _x V ₂ (PO ₄ ) ₃ ).

More preferable specific examples of the negative electrode active material include Li ₄ Ti ₅ O ₁₂ and TiO ₂ .

  Moreover, as a material which comprises the positive electrode collector 14 and the negative electrode collector 15 used for the all-solid-state battery 10 of this embodiment, platinum (Pt), platinum (Pt) / palladium (Pd), gold (Au), for example , Silver (Ag), aluminum (Al), copper (Cu), ITO (indium-tin oxide film), and the like.

[2-2] Method for producing all-solid battery:
Hereinafter, each process of the manufacturing method of the all-solid-state battery of this embodiment is demonstrated more concretely.

[2-2a] Step of forming a solid electrolyte structure for an all-solid battery:
First, in the method for producing an all-solid battery according to the present embodiment, according to the method for producing a solid electrolyte structure of the present invention described so far, a solid electrolyte having a solid electrolyte as a main component as shown in FIGS. It has a dense body 2 and a solid electrolyte porous body 3 containing a solid electrolyte as a main component, and the solid electrolyte porous body 3 is at least one surface of the solid electrolyte dense body 2 (in FIG. 1 and FIG. The solid electrolyte structure 1 for an all-solid battery formed integrally on both surfaces of the body 2 is obtained.

  About the solid electrolyte contained in the 1st green sheet used as a solid electrolyte dense body, and the 2nd green sheet used as a solid electrolyte porous body, it can select suitably in the kind of active material which comprises an electrode active material. .

[2-2b] Step of forming electrode active material:
Next, in the pores of the solid electrolyte porous body in the solid electrolyte structure for an all-solid battery thus obtained, a fine particle active material, a sol active material, a gel active material, a fine particle Active material precursor, sol-like active material precursor, and at least one selected from the group consisting of gel-like active material precursor are filled to form an electrode active material in the pores of the solid electrolyte porous body To do.

  That is, in the step of forming the electrode active material, the active material that becomes the electrode active material and the active material precursor that becomes the active material by firing are formed in the pores of the solid electrolyte porous body in the solid electrolyte structure. At least one selected from the group is filled, and the active material precursor is fired as necessary to form an electrode active material in the pores of the solid electrolyte porous body.

  With this configuration, the active material can be uniformly filled in the pores of the solid electrolyte porous body, and the area of the connection interface between the active material and the solid electrolyte per unit area can be dramatically increased. Can do. Thereby, the reaction resistance at the connection interface can be drastically reduced.

  As the active material, a positive electrode active material (positive electrode active material) for forming the positive electrode active material described above or a material obtained by pulverizing an active material (negative electrode active material) for forming the negative electrode active material is used. Can do. Further, the above-mentioned active material in the form of fine particles may be made into a dispersion solution (solification) using an organic solvent, an aqueous solvent, pure water or the like, and this dispersion solution may be filled in the pores. Alternatively, a gel-like semi-solid material containing a finely divided active material may be used.

  As the active material precursor, a material that becomes the above-described positive electrode active material or negative electrode active material by firing can be used. As for the form of the active material precursor, as in the above active material, a fine particle, sol, or gel can be suitably used.

  As a method of filling at least one selected from the group consisting of the active material and the active material precursor into the pores of the solid electrolyte porous body, for example, in vacuum, the active material and the active material precursor containing the above If the dispersion solution is dropped and impregnated on the surface of the solid electrolyte porous body, or if it can be handled in the atmosphere, or if the solution is low in volatility, In an active atmosphere, the dispersion solution or the sol-like active material precursor can be impregnated by dropping it on the surface of the solid electrolyte porous body and then evacuating it.

  In addition, when filling at least one selected from the group consisting of an active material and an active material precursor, an auxiliary agent (conductive auxiliary agent) such as acetylene black is added to assist the electronic conductivity of the active material. The pores may be filled simultaneously or individually.

  As described above, after filling at least one selected from the group consisting of the active material and the active material precursor, it is preferable to fix the active material by drying or firing. For example, when a sol-like active material precursor or a gel-like active material precursor is used, the active material is generated from the active material precursor by firing at a predetermined temperature.

  Further, when the active material or the active material precursor is not sufficiently filled in one operation, the active material or the active material precursor is spread in the pores 4 of the solid electrolyte porous body 3 by repeating the filling a plurality of times. Like that.

  In addition, an active material and an active material precursor may be used individually by 1 type, and may be used in combination of 2 or more type. Further, when two or more kinds are used in combination, they may be in the same form, or may be in a different form of fine particles, sol, or gel. For example, in the method for manufacturing an all-solid battery according to the present embodiment, the pores of the solid electrolyte porous body in the solid electrolyte structure are selected from the group consisting of a fine particle active material and a fine particle active material precursor. And at least one selected from the group consisting of a sol-form active material and a sol-form active material precursor is further filled in the pores, and the solid electrolyte porous body is filled with pores. It is preferable to form an electrode active material. By comprising in this way, an active material can be filled without a space | gap with the pore of a solid electrolyte porous body, and the capacity | capacitance of the obtained all-solid-state battery can be increased.

  In addition, as shown in FIG. 6, when the solid electrolyte porous body 3 is formed on both surfaces of the solid electrolyte dense body 2 of the solid electrolyte structure 1, two kinds of active materials for positive electrode and negative electrode are used. And active material precursors are used to fill the active material and active material precursor into the pores 4 of the solid electrolyte porous bodies 3 to form electrode active materials.

  On the other hand, although illustration is omitted, when the solid electrolyte porous body is formed only on one surface of the solid electrolyte dense body of the solid electrolyte structure, the pores of the solid electrolyte porous body are formed using the above-described method. One electrode active material is formed by filling at least one selected from the group consisting of an active material and an active material precursor. The other electrode (electrode active material) is, for example, an electrode active material produced by a conventionally known method such as a press method, a doctor blade method, or a roll coater method, for example, the same as an active material precursor or a solid electrolyte. A method of applying and laminating and bonding an adhesive paste made of raw materials, a sputtering method, a resistance heating vapor deposition method in which a vapor deposition source is heated by vapor deposition, a resistance heating vapor deposition method in which a vapor deposition source is heated by an ion beam and vapor deposition, an electron beam It is formed by disposing on the surface of the solid electrolyte dense body opposite to the side where the solid electrolyte porous body is formed by a method such as an electron beam vapor deposition method in which the vapor deposition source is heated and vapor deposited.

[2-2c] Cutting step:
In this way, the solid electrolyte structure in which the electrode active material is formed in the pores of the solid electrolyte porous body is cut into a desired shape to form an all-solid battery. In the manufacturing method of the present embodiment, the solid electrolyte structure is a first green sheet obtained by forming a powdered solid electrolyte into a sheet, and a powdered solid electrolyte and a pore former are formed into a sheet. The solid electrolyte structure used in each of the above steps is manufactured as a sheet-like material having a relatively large surface area, that is, larger than an all-solid battery as a final product. Have been. Thus, for example, it is possible to obtain machine tools and the like dicing saw or wire saw, YAG laser, the all-solid-state cell is cut to a desired size by laser processing machine such as a CO ₂ laser. In addition, by performing the above process using a solid electrolyte structure having a large surface area as described above, a plurality of all solid state batteries can be simultaneously manufactured from one solid electrolyte structure, and the productivity is excellent. .

  Further, in the obtained all solid state battery, a positive electrode collector electrode 14 and a negative electrode collector electrode 15 as shown in FIG. 6 may be disposed in each electrode active material (positive electrode active material and negative electrode active material). Examples of the material constituting the positive electrode collector 14 and the negative electrode collector 15 include platinum (Pt), platinum (Pt) / palladium (Pd), gold (Au), silver (Ag), aluminum (Al), copper ( Cu), ITO (indium-tin oxide film), and the like.

  Moreover, it is good also as a product shape of an all-solid-state battery by coat | covering the outer periphery of the side wall of the obtained all-solid-state battery by molding with resin or glass material.

[3] Manufacturing method of all solid state battery unit:
Next, an embodiment of the method for producing an all solid state battery unit of the present invention will be specifically described. The manufacturing method of the all-solid-state battery unit of this embodiment is the same as that of the solid-electrolyte structure for the all-solid-state battery according to the present invention described above. A plurality of solid electrolyte structures for an all-solid battery thus formed are formed, and in the resulting solid electrolyte structure for an all-solid battery, a fine particle active material, a sol-like structure is formed in the pores of the solid electrolyte porous body. A solid electrolyte porous material filled with at least one selected from the group consisting of an active material, a gel-like active material, a particulate active material precursor, a sol-like active material precursor, and a gel-like active material precursor A step of obtaining an active material-filled solid electrolyte structure in which an electrode active material made of an active material is formed in the pores of the body, and a plurality of the obtained active material-filled solid electrolyte structures are connected via a current collector , Stacked in electrical series A method for manufacturing an all-solid battery unit and a step.

  As shown in FIG. 7, the all-solid battery unit manufactured by the manufacturing method of the all-solid battery unit of the present embodiment is an electrode made of an active material in the pores 4 of the solid electrolyte porous body 3 of the solid electrolyte structure 1. An all-solid battery unit 31 in which a plurality of active material-filled solid electrolyte structures 32 in which an active material 22 is formed are stacked in series via a collector electrode 33, and has one solid electrolyte structure The active material-filled solid electrolyte structure 32 made of the body 1 becomes a single cell of a battery, and is a battery unit configured by stacking a plurality of single cells. Here, FIG. 7 is a schematic diagram showing the configuration of the all solid state battery unit obtained by an embodiment of the method for producing the all solid state battery unit of the present invention.

  Such an all-solid-state battery unit can generate a high potential that is difficult to achieve with a single-cell all-solid-state battery, and may be necessary depending on the number of active material-filled solid electrolyte structures stacked via a current collector. Potential (high potential) can be ensured. In particular, in the above-described method for producing a solid electrolyte structure of the present invention, since the solid electrolyte dense body and the solid electrolyte porous body are formed using a green sheet, the active material-filled solid electrolyte structure that becomes a single cell is formed. It is possible to reduce the thickness, and it is possible to reduce the thickness of the entire all solid state battery unit.

  7 shows an all solid state battery unit 31 in which three active material-filled solid electrolyte structures 32 are stacked so as to be electrically connected in series via a collector electrode 33. There is no particular limitation on the number of filled solid electrolyte structures 32.

  In the manufacturing method of the all solid state battery unit of the present embodiment, when forming the active material filled solid electrolyte structure, first, the manufacturing method of the solid electrolyte structure for the all solid state battery of the present invention described above is first described. As a result, a plurality of solid electrolyte structures in which a solid electrolyte porous body is formed on both surfaces of the solid electrolyte dense body are formed. The type of solid electrolyte used for forming the solid electrolyte dense body and the solid electrolyte porous body of the solid electrolyte structure into a sheet shape may be appropriately selected according to the type of active material constituting the electrode active material. it can.

  Next, in the pores of the solid electrolyte porous body in the obtained solid electrolyte structure, a fine particle active material, a sol active material, a gel active material, a fine particle active material precursor, a sol Active material filling in which at least one selected from the group consisting of an active material precursor and a gel-like active material precursor is filled to form an electrode active material made of the active material in the pores of the solid electrolyte porous body A solid electrolyte structure is obtained. The method of filling the active material or active material precursor described above can be realized by the same method as the above-described method for manufacturing an all solid state battery of the present invention. That is, in the manufacturing method of the all solid state battery unit of the present embodiment, the solid electrolyte structure filled with the active material and the active material precursor constituting the all solid state battery is converted into a single cell (ie, active cell) of the battery unit. Substance-filled solid electrolyte structure).

  Next, a plurality of the active material-filled solid electrolyte structures obtained in this way are stacked so as to be electrically in series via a current collector to produce an all-solid battery unit. The current collector is, for example, a positive electrode active material of one active material-filled solid electrolyte structure and another active material-filled solid electrolyte structure disposed adjacent to the one active material-filled solid electrolyte structure It is the plate-shaped member which has electrical conductivity for electrically connecting with the negative electrode active material. As a result, a plurality of thin active material-filled solid electrolyte structures are electrically connected in series by sandwiching a plate-like current collector therebetween.

  Examples of the material constituting the current collector include platinum (Pt), platinum (Pt) / palladium (Pd), gold (Au), silver (Ag), aluminum (Al), copper (Cu), and ITO (indium). -Tin oxide film).

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

(Example 1)
A first green sheet is formed using a material powder in which Li _0.35 La _0.55 TiO ₃ (solid electrolyte) is powdered, and Li _0.35 La _0.55 TiO ₃ (solid electrolyte) is formed. A second green sheet was formed using a material powder obtained by mixing the powder and theobromine (pore forming agent). Incidentally, the second green _sheet, Li _{0.35 La} 0.55 TiO ₃ (solid electrolyte) and theobromine (pore forming agent) in a volume ratio of 1: a material powder was blended so that 1.

Next, an adhesive layer formed using Li _0.35 La _0.55 TiO ₃ (solid electrolyte) was formed on one side of the second green sheet by screen printing.

Next, the order of the second green sheet, the first green sheet, and the second green sheet so that the surface on which the adhesive layer of the second green sheet is formed is the side to be joined to the first green sheet. Then, after heating to about 80 ° C., pressure lamination was performed at a surface pressure of 40 kgf / cm ² to obtain a sheet laminate.

Next, the obtained sheet laminate is fired at 1160 ° C., which is a temperature sufficient for sintering Li _0.35 La _0.55 TiO ₃ (solid electrolyte), to obtain a solid electrolyte for an all-solid battery. A structure (Example 1) was manufactured.

(Example 2)
The sheet laminated body obtained by the same process as Example 1 was baked at 1130 degreeC, and the solid electrolyte structure (Example 2) for all-solid-state batteries was manufactured.

(Example 3)
The sheet laminated body obtained by the same process as Example 1 was baked at 1090 degreeC, and the solid electrolyte structure (Example 3) for all-solid-state batteries was manufactured.

Example 4
A first green sheet is formed using a material powder in which Li _0.35 La _0.55 TiO ₃ (solid electrolyte) is powdered, and Li _0.35 La _0.55 TiO ₃ (solid electrolyte) is formed. A second green sheet was formed using a material powder obtained by mixing the powder and theobromine (pore forming agent). Incidentally, the second green _sheet, Li _{0.35 La} 0.55 TiO ₃ (solid electrolyte) and theobromine (pore forming agent) in a volume ratio of 1: a material powder was blended so that 2.

  Using the obtained first green sheet and second green sheet, a sheet laminate was obtained by the same process as in Example 1, and the obtained sheet laminate was fired at 1130 ° C. A solid electrolyte structure (Example 4) for an all-solid battery was produced.

(Example 5)
A first green sheet is formed using a material powder in which Li _0.35 La _0.55 TiO ₃ (solid electrolyte) is powdered, and Li _0.35 La _0.55 TiO ₃ (solid electrolyte) is formed. A second green sheet was formed using a material powder obtained by mixing the powder and theobromine (pore forming agent). Incidentally, the second green _sheet, Li _{0.35 La} 0.55 TiO ₃ (solid electrolyte) and theobromine (pore forming agent) in a volume ratio of 1: a material powder was blended so that 3.

  Using the obtained first green sheet and second green sheet, a sheet laminate was obtained by the same process as in Example 1, and the obtained sheet laminate was fired at 1130 ° C. A solid electrolyte structure (Example 5) for an all-solid battery was produced.

  8 to 14 are SEM photographs of cross sections of the solid electrolyte dense body and the solid electrolyte porous layer of the solid electrolyte structures in Examples 1 to 5, FIG. 8 is Example 1, and FIG. 9 is Example. 2 and FIG. 10 are SEM photographs of Example 3, FIGS. 11 and 12 are Examples 4 and FIGS. 13 and 14 are SEM photographs of Example 5. FIG.

(Comparative Example 1)
A material powder in which Li _0.35 La _0.55 TiO ₃ (solid electrolyte) is powdered is molded by a mold press to obtain a first molded body having a diameter of about φ13 mm and a thickness of 1 mmt after firing. It was. The obtained 1st molded object was baked at 1150 degreeC in air | atmosphere atmosphere, and the solid electrolyte dense body was produced.

  Next, a screen printing paste was prepared using a solid electrolyte powder having the same material composition as that of the solid electrolyte used in the first molded body. In this comparative example, the above-mentioned solid electrolyte powder was blended with ESREC B (trade name: manufactured by Sekisui Chemical Co., Ltd.) as a binder component, CS-12 (trade name: manufactured by Chisso Corporation) as an organic solvent, and theobromine as a pore-forming agent. In addition, a screen printing paste was prepared. The obtained screen printing paste was applied to the surface of the solid electrolyte dense body by a screen printing method to obtain a second molded body having a diameter of about 12 mm in diameter and a thickness of 10 μmt after firing.

  Next, the obtained second molded body is additionally fired together with the solid electrolyte dense body at a temperature lower than the firing temperature of the first molded body, and is fired and integrated on at least one surface of the solid electrolyte dense body. The solid electrolyte porous layer was formed to produce a solid electrolyte structure. The conditions for the additional firing were 1100 ° C. in an air atmosphere. Here, FIG. 15 is an SEM photograph of a cross section of the solid electrolyte dense body and the solid electrolyte porous layer of the solid electrolyte structure in Comparative Example 1.

(Discussion)
As shown in FIGS. 8 to 14, when the solid electrolyte structures of Examples 1 to 3 are compared, in the solid electrolyte dense body, the sintering does not progress much in Example 3, but Examples 1 and 2 Then, it can be said that it is a sufficient sintered state. On the other hand, in the solid electrolyte porous body, a state in which sufficient necking was ensured in Examples 1 and 2 was obtained, but in Example 1, the sintering progressed further and the opening (porosity) of the solid electrolyte porous body was increased. The situation is on the decline.

  For this reason, as the optimum balance between the solid electrolyte dense body and the solid electrolyte porous body, the firing conditions of the solid electrolyte structure of Example 2 are suitable.

  Next, with respect to the controllability of the degree of opening of the solid electrolyte porous body, when Example 2 is compared with Examples 4 and 5, control is performed so that the opening of the solid electrolyte porous body increases as the blending ratio of the pore former increases. You can see that it is made.

  Further, the solid electrolyte structure of Comparative Example 1 had a thin solid electrolyte porous body and a poor flatness. In the method for producing a solid electrolyte structure for an all-solid battery of the present invention, the flatness of the surface portion of the solid electrolyte porous body is improved by tape molding using a green sheet, and the pore former It is possible to obtain a solid electrolyte structure in which the thickness of the solid electrolyte porous body is reduced while the thickness of the solid electrolyte porous body is increased while the opening of the solid electrolyte porous body is controlled by the added amount of.

  The all-solid-state battery of the present invention is a battery (for hybrid power supply) used in combination with other batteries including portable device batteries, IC card built-in batteries, implant medical device batteries, substrate surface mounting batteries, solar batteries Battery) and the like.

It is a perspective view which shows the solid electrolyte structure obtained by one Embodiment of the manufacturing method of the solid electrolyte structure of this invention. It is a figure which shows the A-A 'cross section of the solid electrolyte structure shown in FIG. It is a schematic diagram explaining the process of obtaining the 1st green sheet in one Embodiment of the manufacturing method of the solid electrolyte structure of this invention. It is a schematic diagram explaining the process of obtaining the 2nd green sheet in one Embodiment of the manufacturing method of the solid electrolyte structure of this invention. It is a schematic diagram explaining the process of obtaining the sheet | seat laminated body in one Embodiment of the manufacturing method of the solid electrolyte structure of this invention. It is a schematic diagram which shows the all-solid-state battery obtained by one Embodiment of the manufacturing method of the all-solid-state battery of this invention. It is a schematic diagram which shows the all-solid-state battery unit obtained by one Embodiment of the manufacturing method of the all-solid-state battery unit of this invention. 2 is a SEM photograph of a cross section of a solid electrolyte dense body and a solid electrolyte porous layer of the solid electrolyte structure of Example 1. FIG. 4 is a SEM photograph of a cross section of a solid electrolyte dense body and a solid electrolyte porous layer of a solid electrolyte structure of Example 2. FIG. 4 is a SEM photograph of a cross section of a solid electrolyte dense body and a solid electrolyte porous layer of a solid electrolyte structure of Example 3. 4 is a SEM photograph of a cross section of a solid electrolyte dense body and a solid electrolyte porous layer of a solid electrolyte structure of Example 4. 4 is a SEM photograph of a cross section of a solid electrolyte dense body and a solid electrolyte porous layer of a solid electrolyte structure of Example 4. 6 is a SEM photograph of a cross section of a solid electrolyte dense body and a solid electrolyte porous layer of a solid electrolyte structure of Example 5. 6 is a SEM photograph of a cross section of a solid electrolyte dense body and a solid electrolyte porous layer of a solid electrolyte structure of Example 5. 4 is a SEM photograph of a cross section of a solid electrolyte dense body and a solid electrolyte porous layer of a solid electrolyte structure of Comparative Example 1.

Explanation of symbols

1: solid electrolyte structure, 2: solid electrolyte dense body, 3, 3a, 3b: solid electrolyte porous body, 4: pores, 10: all solid state battery, 11, 22: electrode active material, 11a: positive electrode active material, 11b: negative electrode active material, 12: first green sheet, 13: second green sheet, 14: positive electrode collector, 15: negative electrode collector, 17: pore former, 31: all solid state battery unit, 32: active Substance-filled solid electrolyte structure, 33: current collector.

Claims (8)

A method for producing a solid electrolyte structure for an all-solid battery comprising a solid electrolyte dense body and a solid electrolyte porous body, wherein the solid electrolyte porous body is integrally formed on at least one surface of the solid electrolyte dense body Because
Forming a powdery solid electrolyte into a sheet to obtain a first green sheet;
Forming a powdery solid electrolyte and a pore former into a sheet to obtain a second green sheet;
A step of laminating the second green sheet to obtain a sheet laminate on at least one surface of the obtained first green sheet;
By firing the obtained sheet laminate, the solid electrolyte porous body made of the second green sheet is fixed to at least one surface of the solid electrolyte dense body made of the first green sheet. And a step of obtaining a solid electrolyte structure for an all-solid battery formed integrally, and a method for producing a solid electrolyte structure for an all-solid battery.   The solid electrolyte for an all-solid-state battery according to claim 1, wherein the second green sheet is formed using a material powder in which the pore former is contained in a volume ratio of 1 or more with respect to the solid electrolyte. Manufacturing method of structure.   3. The all solid state battery according to claim 1, wherein particles having an average particle diameter larger than that of the solid electrolyte used for forming the first green sheet are used as the solid electrolyte used for forming the second green sheet. A method for producing a solid electrolyte structure.   The all-solid-state battery as described in any one of Claims 1-3 which uses a solid electrolyte with an average particle diameter of 5 micrometers or less as said solid electrolyte used for shaping | molding of said 1st green sheet and said 2nd green sheet, respectively. For producing a solid electrolyte structure for use in an automobile.   The solid electrolyte used for forming the first green sheet and the second green sheet is a titanium oxide type solid electrolyte or a solid electrolyte composed of a NASICON type phosphoric acid compound. A method for producing a solid electrolyte structure for an all-solid battery according to claim 1. A solid electrolyte structure for an all-solid battery is obtained by the method for producing a solid electrolyte structure for an all-solid battery according to any one of claims 1 to 5,
In the pores of the solid electrolyte porous body in the obtained solid electrolyte structure for an all-solid battery, a fine particle active material, a sol active material, a gel active material, and a fine particle active material precursor Filling a sol-like active material precursor and at least one selected from the group consisting of a gel-like active material precursor and forming an electrode active material in the pores of the solid electrolyte porous body A method for manufacturing an all-solid battery.   The pores of the solid electrolyte porous body in the solid electrolyte structure for an all solid state battery were filled with at least one selected from the group consisting of the fine particle active material and the fine particle active material precursor. Thereafter, at least one selected from the group consisting of the sol-like active material and the sol-like active material precursor is further filled in the pores, and the electrode is placed in the pores of the solid electrolyte porous body The manufacturing method of the all-solid-state battery of Claim 6 which forms an active material. The solid electrolyte porous body is formed on both surfaces of the solid electrolyte dense body by the method for producing a solid electrolyte structure for an all solid state battery according to any one of claims 1 to 5. Forming a plurality of solid electrolyte structures,
In the pores of the solid electrolyte porous body in the obtained solid electrolyte structure for an all-solid battery, a fine particle active material, a sol active material, a gel active material, and a fine particle active material precursor An electrode active material made of an active material is formed in the pores of the solid electrolyte porous material by filling at least one selected from the group consisting of a sol-like active material precursor and a gel-like active material precursor Obtaining an active material-filled solid electrolyte structure,
And stacking a plurality of the obtained active material-filled solid electrolyte structures so as to be electrically in series via a current collector.