JP2553588B2 - Solid-state electrochemical device and manufacturing method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state electrochemical device such as a solid electrolyte battery or a solid electric double layer capacitor in which all constituent elements are solid substances, and a method for producing the same.

Prior art Electrochemical devices, whose device components are all solid substances,
It has the advantages of no liquid leakage and easy miniaturization and thinning. When configuring such an element, a solid-state electrolyte for moving ions inside the element, that is, a solid electrolyte is required. Solid electrolytes are distinguished by moving ionic species, and include Li ⁺ ion conductive solid electrolytes, Ag ⁺ ion conductive solid electrolytes, Cu ⁺ ion conductive solid electrolytes, H ⁺ ion conductive solid electrolytes, and the like. A solid electrochemical element is constructed by combining these solid electrolytes and an appropriate electrode material.

Since these solid-state electrochemical elements are all solid substances, a powder-like electrode material is pressed through both sides of the solid electrolyte so as to form three layers as a whole into chips, It is assembled in a pellet form, or is formed in a thin film form on a substrate by using a physical vapor deposition method or a chemical vapor deposition method.

In a normal electrochemical device using a liquid electrolyte, electrical and ionic bonding between the electrolyte and the electrode material is easy, whereas in a device composed entirely of solid substances, solid electrolytes, electrode materials, and It is difficult to easily obtain electrical and ionic bonding between the solid electrolyte and the electrode material. For this reason, in an element using a liquid electrolyte, it is generally customary to mix impurities such as a binder with the electrode or the electrolyte in order to prevent the electrolyte from penetrating into the electrode too much and causing the shape of the electrode to collapse. However, in solid-state electrochemical devices, it is customary not to use impurities as much as possible because the bonding will be worse.

Problems to be Solved by the Invention As described above, since impurities are not used in the solid-state electrochemical device, when attempting to construct a thin and large-sized device, generally, the components are lacking in elasticity. There is a problem that it is brittle against impact and easily broken.
In addition, in the solid electrolyte, a chemically active monovalent cation is generally conductive, and when exposed to oxygen and moisture in the atmosphere, the solid electrolyte is deteriorated to be oxidized into a divalent cation or becomes an oxide. There is a problem that it may be fixed in the crystal and may not function as a conductor.

Means for Solving the Problems A solid electrochemical device of the present invention is a molded body of solid electrolyte particles coated with a plastic resin, and electrodes arranged on each of a pair of facing surfaces of the molded body of solid electrolyte particles. The solid electrolyte particle compact has an ion conductive conduction path formed by contact between solid electrolyte particles between the pair of facing surfaces.

The method for producing a solid electrochemical device of the present invention comprises electrode material particles or electrode material particles and solid electrolyte particles dispersed in a solvent containing a plastic resin, and after forming a plastic resin layer on the surface of these particles, molding of the electrode material. A step of producing a body, a step of dispersing the solid electrolyte particles in a solvent containing a plastic resin, forming a plastic resin layer on the surface of the solid electrolyte particles, and then producing a solid electrolyte molded body, and a set of the solid electrolyte molded body By the step of disposing the electrode material molded body on one of the facing surfaces and the other electrode material molded body on the other side and integrally molding, the solid electrolyte particles are separated from each other between the pair of facing surfaces of the solid electrolyte molded body. It is characterized in that an ion conductive conduction path is formed by contact.

Further, the method for producing a solid electrochemical device of the present invention comprises a step of obtaining an electrode material molded body by mixing and molding a mixture of electrode material particles or a mixture of electrode material particles and solid electrolyte particles and a plastic resin powder, A step of mixing and molding the electrolyte particles and the plastic resin powder particles to obtain a solid electrolyte particle molded body; and a pair of facing surfaces of the solid electrolyte particle molded body, wherein the electrode material molded body is on one side and the other is on the other side. The step of arranging the electrode material molded bodies and molding them integrally forms an ion conductive conduction path between the solid electrolyte particle molded bodies by contacting the solid electrolyte particles with each other. And

Action In the present invention, a contaminant, which is usually avoided in a solid-state electrochemical device, is mixed, that is, a component wrapped with a plastic resin is used. As a result, when the element is assembled or when the solid electrolyte molded body or the electrode molded body is molded, the plastic resin is pushed between the constituent particles, and the particles are directly contacted with each other, and an aggregate surrounded by the plastic resin is formed as a whole. . Therefore, the constituent particles maintain their shape as an aggregate, ensure electrical and ionic connection with each other, and are not directly exposed to oxygen and moisture in the atmosphere, and are unlikely to deteriorate.

Example In order to solve the above-mentioned problems, we continued to study the mixing of contaminants that were normally avoided in solid-state electrochemical devices.In addition to the above, by using device components wrapped with a plastic resin, I have found that the above problems can be solved.

When the plastic resin is mixed with the solid electrolyte powder and the electrode material powder in an appropriate ratio by dry mixing or wet mixing, respectively,
As shown in 1a of FIG. 1 or 2a of FIG. 2, the surface of the solid electrolyte granular material 1 or the electrode material granular material 2 can be completely covered with the plastic resin. Then, the mixture prepared in this manner is pressed into a suitable shape while being heated if necessary with a pressing machine or the like, and at this time, the plastic resin, which is more likely to undergo mechanical deformation than these powders, is in a fluid state, As shown in 1b in Fig. 1 or 2b in Fig. 2, a part of the resin that covered the surface of the granular material before molding was pushed into the gap created by the granular material and the granular material. Are electrically and ionically connected. At the same time, the resin pushed into the gap acts to effectively bind the particles together. A solid electrochemical element is obtained by pressing the electrode material molded body through the solid electrolyte molded body molded in this way again so as to be integrated with other element constituent elements such as a current collector if necessary. Is obtained. FIG. 3 shows a part of the cross section of the solid electrolyte element. A and C are electrode material molded bodies, B is a solid electrolyte molded body, and 4 is a current collector. Also in this case, the flow of the plastic resin occurs in the same manner as described above, and the resin is pushed between the molded body and the granular material which was insufficiently filled with the plastic resin at the time of pressure molding, and the amount thereof is reduced. The electrical and ionic connections between the particles become stronger and more flexible when the particles are encapsulated by the resin, resulting in a flexible and flexible solid electrochemical element.

As described above, the solid electrolyte molded body and the electrode molded body may be molded in advance, and these may be integrally molded to form an element. Alternatively, the mixture with the resin may be directly molded into the element without passing through these molded bodies. Good.

In the present invention, a solid electrolyte molded body in which solid electrolyte particles are covered with a plastic resin is used, and in the electrochemical element in which this solid electrolyte molded body is used, electrodes are arranged on the upper and lower surfaces thereof. Used in the form. Therefore, the upper and lower parts of the solid electrolyte molded body which are brought into contact with these electrodes, in order to obtain a good ionic connection with the electrodes,
It is also possible to use a solid electrolyte molded body which is molded beforehand in a state where the coating of the plastic resin is extremely thin or is substantially not covered with the plastic resin.

In addition, by coating the surface of the solid electrolyte powder in which monovalent cations such as Li ⁺ , Ag ⁺ , Cu ⁺ , H ^{+, which} are chemically active, as conductive ions, with a plastic resin during raw material preparation. The influence of oxygen and moisture can be reduced in the subsequent element manufacturing process. Further, since the powder and granules obtained in this manner are covered with a plastic resin, except for a part which provides electrical and ionic connection between the powder and granules, when used as an element,
Even if it is directly placed in the atmosphere, each powder or granular material does not come into direct contact with oxygen or moisture, and it becomes a solid electrochemical element having excellent environmental resistance.

 Next, examples will be described more specifically.

The plastic resin according to the present invention may be any commercially available plastic resin, and among these plastic resins, synthetic rubber such as polyethylene, polypropylene, styrene-butadiene rubber or neoprene rubber, silicone resin, acrylic resin are particularly preferable. Used for.

When polyethylene, polypropylene, or acrylic resin is used, fine powders of these resins are used, and dry mixing is performed with each powder of the element constituting material such as the solid electrolyte powder or the electrode material powder. The particle size of the resin is preferably 1/10 to 1/10000 of the particle size of each of these powders. During the mixing, a mixture in which polyethylene, polypropylene, or acrylic resin particles are coated around the element-constituting material powder particles due to static electricity generated between the particles is obtained.

When a synthetic rubber such as styrene / butadiene or neoprene, a silicone resin, or an acrylic resin is used, wet mixing is performed using an organic solvent such as toluene or xylene.
5-20 synthetic rubber, acrylic resin or silicone resin
By adding powders of element constituent material powder to a solvent dissolved in weight percent and mixing it into a slurry, apply it on a plate such as fluororesin and then disperse the solvent under reduced pressure, if necessary with heating. A film can be formed, or the mixture obtained by allowing the slurry to stand under reduced pressure to dissipate the solvent may be subjected to pressure molding.

As the solid electrolyte used in the present invention, LiI, LiIH
₂ O, Li ₃ N, Li ₄ SiO ₄ -Li ₃ PO ₄ etc.Li ⁺ ion conductive solid electrolyte, RbAg ₄ I ₅ ,, Ag ₃ SI, AgI-Ag ₂ O-MoO ₃ Glass etc Ag ⁺ ion conductive Solid electrolyte, RbCu ₄ I _1.75 Cl _3.25 RbCu ₄ I
_1.5 C _3.5 , RbCu ₄ I _1.25 Cl _3.75 , K _0.2 Rb _0.8 Cu ₄ I _1.5 Cl _3.5 , Cu
_{I-Cu 2 O-MoO 3} Cu + ion conductive solid electrolyte solutions such as glass,
There are H ⁺ ion conductive solid electrolytes such as H ₃ Mo ₁₂ PO ₄₀・ 29H ₂ O and H ₃ W ₁₂ PO ₄₀・ 29H ₂ O.

Examples of the electrode material used in the present invention include carbon materials such as graphite, acetylene black, activated carbon, titanium sulfide, niobium sulfide, copper sulfide, silver sulfide, lead sulfide, silver chevrel (silver molybdenum sulfide), and copper chevrel (copper molybdenum sulfide). ),
Sulfides such as iron sulfide, tungsten oxide, vanadium oxide, chromium oxide, molybdenum oxide, titanium oxide, iron oxide, silver oxide, oxides such as copper oxide, silver chloride, halides such as lead iodide, copper, silver, A metal material such as lithium, gold, platinum, titanium, or an alloy thereof can be used. An electrode material that exchanges ions with a solid electrolyte, such as titanium disulfide, can be used to form a solid electrolyte battery, and an electrode material that exchanges ions with the solid electrolyte and undergoes an optical change with it, for example, When tungsten oxide is used, a solid electrochemical display element (electrochromic element) can be formed. Although the ion exchange is not performed with the solid electrolyte, a solid electric double layer capacitor can be formed by using an electrode material that forms an electric double layer at the interface with the solid electrolyte, such as activated carbon. According to the present invention, any of the solid-state electrochemical devices will be highly flexible, extremely strong against mechanical shock, and excellent in environmental resistance.

Example 1 100 parts by weight of Cu ⁺ ion conductive solid electrolyte powder particles represented by RbCu ₄ I _1.5 Cl _3.5 having an average particle size of 10 μ as a solid electrolyte,
A mixture obtained by mixing 200 parts by weight of polyethylene powder having an average particle diameter of 0.1 μm in a dry nitrogen atmosphere was prepared by using a press machine.
The solid electrolyte molded body having a thickness of 100 μ was obtained by molding at a pressure of 200 Kg / cm ² into 5 mm × 20 mm. Next, in the same way, the average particle size is 15μ
m of Cu _0.1 NbS ₂ 50 parts by weight of the positive electrode active material powder, 50 parts by weight of the solid electrolyte powder and 15 parts by weight of the polyethylene powder, the size of which is 5 mm × 20 mm and the thickness is 20 mm.
A positive electrode molded body of 0 μm was obtained. Similarly, a mixture of 50 parts by weight of the negative electrode active material powder made of metallic copper having an average particle size of 8 μm, 50 parts by weight of the solid electrolyte powder, and 25 parts by weight of the polyethylene powder having a size of 5 mm × 20 mm and a thickness of 120 μm.
A negative electrode molded body of was obtained. Each of the thus-obtained compacts was press-molded into three layers under a pressure of 250 Kg / cm ² to obtain a Cu-based solid battery A.

Example 2 A Cu-based solid battery B was obtained in the same manner as in Example 1 except that polypropylene powder having an average particle size of 0.1 μm was used instead of polyethylene powder.

[Comparative Example 1] A Cu-based solid battery C was obtained in the same manner as in Example 1 except that polyethylene powder was not mixed.

Example 3 Ag ⁺ ion conductive solid electrolyte powder represented by RbAg ₄ I ₅ having an average particle size of 8 μ as a solid electrolyte, positive electrode active material powder having an average particle size of 15 μm represented by Ag _0.1 NbS ₂ , Average particle size is 8μ
Ag in the same manner as in Example 1 except that the metallic silver powder of m was used.
A solid-state battery D was obtained.

[Comparative Example 2] An Ag-based solid battery E was obtained in the same manner as in Example 3 except that polyethylene powder was not mixed.

Example 4 L represented by LiI having an average particle size of 15 μm as a solid electrolyte
i ⁺ ion-conductive solid electrolyte powder, positive electrode active material powder represented by WO ₃ having an average particle size of 12 μ, Li _1.5 W having an average particle size of 10 μm
Example 1 except that a negative electrode active material powder represented by O ₃ was used
A Li-based solid battery F was obtained in the same manner as in.

[Comparative Example 3] A Li-based solid battery G was obtained in the same manner as in Example 4 except that polyethylene powder was not mixed.

Example 5 H ₃ Mo ₁₂ PO ₄₀ / 29H ₂ having a mean particle size of 20 μ as a solid electrolyte
H ⁺ ion-conductive solid electrolyte powder represented by O, positive electrode active material powder represented by WO ₃ having an average particle size of 8 μm, HWO ₃ represented by OWO having an average particle size of 8 μm and negative electrode powder An H-based solid battery H was obtained in the same manner as in Example 1 except that acrylic resin powder having an average particle size of 0.2 μm was used instead of polyethylene powder.

[Comparative Example 4] An H-based solid battery I was obtained in the same manner as in Example 5, except that the acrylic resin powder was not mixed.

Example 6 RbCu ₄ I _1.75 Cl _3.25 having an average particle size of 2 μm as a solid electrolyte
100 parts by weight of the Cu ⁺ ion conductive solid electrolyte powder represented by the following was mixed with 30 parts by weight of a toluene solution containing 10% by weight of styrene-butadiene rubber to obtain a solid electrolyte slurry.
The slurry was spread on a fluororesin flat plate with a bar coater to a dry thickness of 20 μm, which was reduced to 1 Torr.
20μm thickness and 60m width by vacuum drying at 0 ℃ for 3 hours
A solid electrolyte thin film of m and 800 mm in length was obtained. Next, 50 parts by weight of graphite powder having an average particle size of 0.5 μm and the above solid electrolyte powder 50
By mixing 35 parts by weight of the above toluene solution, a positive electrode slurry was obtained, and a positive electrode thin film having a thickness of 30 μm, a width of 60 mm and a length of 800 mm was similarly obtained. Further, similarly 50 parts by weight of metallic copper powder having an average particle size of 2 μm, 50 parts by weight of solid electrolyte powder, toluene solution 18
Anode slurry was obtained from parts by weight, and using this, a thickness of 20 μm,
A negative electrode thin film with a width of 60 mm and a length of 800 mm was obtained. The positive electrode thin film is arranged on one surface of the solid electrolyte thin film thus obtained, and the negative electrode thin film is arranged on the other surface thereof, and a three-layer structure is formed at a pressure of 20 Kg / cm ² by a pressure roller heated to 130-150 ° C. A solid battery J was obtained by pressure-bonding so as to form an integral body, forming a thin film having a width of 65 mm, a length of 1000 mm, and a thickness of 55 to 60 μm, and cutting the thin film into 5 mm × 20 mm.

[Example 7] A solid battery K was obtained in the same manner as in Example 6 except that a silicone resin was used instead of the styrene-butadiene rubber.

Example 8 A solid battery L was obtained in the same manner as in Example 6 except that acrylic resin was used instead of styrene / butadiene rubber.

Example 9 A graphite powder, a solid electrolyte powder, and a styrene-butadiene rubber having a thickness of 30 μm obtained in the same manner as in Example 6 through a solid electrolyte thin film having a thickness of 20 μm obtained in the same manner as in Example 6 were used.
Electrode thin film of μm is placed on top and bottom, and 20
It is pressure-bonded at a pressure of Kg / cm ² at 130 to 150 ° C so that the three layers are integrated to form a thin film with a width of 65 mm, a length of 1000 mm, and a thickness of 60 to 65 μm, which is cut into 5 mm x 20 mm solid electric electrodes. A multilayer capacitor K was obtained.

Example 10 H ₃ Mo ₁₂ PO ₄₀ · 29 having an average particle size of 20 μm as a solid electrolyte
50 parts by weight of H ⁺ ion conductive solid electrolyte powder represented by H ₂ O, 20 parts by weight of acrylic resin powder having an average particle size of 0.2 μm,
Graphite powder having an average particle size of 0.5 μm was mixed and molded in the same manner as in Example 1 to form a graphite electrode having a size of 5 mm × 20 mm and a thickness of 30 μm. This electrode and the same method as in Example 5 were used.
A display electrode having a thickness of 10 μm and a size of 5 mm × 20 mm containing WO _3, and a solid electrolyte thin film having a thickness of 50 μm and a size of 5 mm × 20 mm made of an H ⁺ ion conductive solid electrolyte and an acrylic resin are used. The electrolyte thin film was used as an intermediate layer, and three layers were pressed together to obtain a solid electrochromic device L having a thickness of about 85 μm and a size of 5 mm × 20 mm.

The solid state batteries A to J, the solid state electric double layer capacitor K, and the solid state electrochromic element L thus obtained were subjected to a repeated bending test at an angle of 30 ° in the longitudinal direction in a bare state. The table below shows the number of folds before cutting occurs. The ratio of the internal resistance R _{1 to} the initial internal resistance R ₀ when each battery, capacitor, and electrochromic device is left in the atmosphere of 45 ° C and 60% humidity for 48 hours, R ₁ / R
₀ is also shown in the table below.

In the examples, as the electrolyte material, Li ⁺ , Ag ⁺ ,
Typical Cu ⁺ , H ⁺ , ion conductive solid electrolyte materials are LiI, RbAg ₄ I ₅ ,, RbCu ₄ I _1.5 Cl _3.5 , H ₃ MO ₁₂ PO ₄₀・ 29H ₂ O
However, it is needless to say that the same effect can be obtained by using other electrolyte materials. As the solid electrolyte material referred to in the present invention, in addition to the above-mentioned typical ones, a material in which sulfuric acid is retained in silica gel or the like, a liquid substance is retained in a solid material to an extent that does not change the physical shape of the solid. Including materials. The same applies to the positive electrode active material and the negative electrode active material.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to obtain a flexible solid electrochemical element having excellent mechanical strength and being hardly affected by oxygen, moisture and the like.

[Brief description of drawings]

FIG. 1 is a diagram showing a solid electrolyte powder granule whose surface is covered with a plastic resin and an aggregate of the solid electrolyte powder granules obtained by press-molding these powder granules, and FIG. 2 is a plastic resin A diagram showing a solid electrolyte granular material and an electrode material granular material whose surface is covered with, and an aggregate of the electrode material granular material and the solid electrolyte granular material obtained by press-molding these granular materials. , Third
The figure shows a solid electrolyte molded body B and electrode material molded bodies A and C.
It is a figure which shows a part of cross section of the solid electrolyte element comprised by. 1 ... Solid electrolyte powder, 2 ... Electrode material powder, 3 ...
… Plastic resin.

Claims (9)

(57) [Claims] 1. A solid electrochemical device comprising a molded body of solid electrolyte particles coated with a plastic resin, and a molded body of electrode material arranged on each of a pair of facing surfaces of the molded body of solid electrolyte particles. A solid electrochemical element in which the solid electrolyte particle compact has an ionically conductive path formed by contact between solid electrolyte particles between the pair of facing surfaces. 2. The solid electrochemical element according to claim 1, wherein the molded electrode material is a mixture of electrode material particles and solid electrolyte particles. 3. The solid electrochemical device according to claim 1, wherein at least one of the electrode material particles and the solid electrolyte particles of the electrode material molded body is coated with a plastic resin. 4. The solid electrochemical device according to claim 1, wherein the solid electrolyte particles are monovalent cation conductive solid electrolyte particles. 5. The thermoplastic resin is a thermoplastic resin selected from synthetic rubbers such as styrene-butadiene rubber and neoprene rubber, polyethylene, polypropylene, silicone resin, acrylic resin, or a mixture thereof. The solid-state electrochemical device described. 6. Electrode material particles or electrode material particles and solid electrolyte particles are dispersed in a solvent containing a plastic resin,
After forming a plastic resin layer on the surface of these particles, a step of producing an electrode material molded body, dispersing solid electrolyte particles in a solvent containing a plastic resin, and forming a plastic resin layer on the surface of the solid electrolyte particles, then forming a solid electrolyte molded body. And a step of forming the electrode material molded body on one of a pair of opposing surfaces of the solid electrolyte molded body and another electrode material molded body on the other side to integrally mold the solid electrolyte molded body. 2. A method for producing a solid electrochemical element, comprising forming an ionically conductive conduction path by contacting solid electrolyte particles with each other between the pair of opposed surfaces. 7. The solid-state electrochemical according to claim 6, wherein the plastic resin is a thermoplastic resin selected from synthetic rubber such as styrene-butadiene rubber and neoprene rubber, silicon resin, acrylic resin or a mixture thereof. Device manufacturing method. 8. A step of mixing and molding electrode material particles or a mixture of electrode material particles and solid electrolyte particles and a plastic resin powder to obtain an electrode material molded body, solid electrolyte particles and a plastic resin powder. And molding to obtain a solid electrolyte particle compact, and disposing the electrode material compact on one of a pair of opposing surfaces of the solid electrolyte particle compact, and the other electrode material compact on the other side. A method for producing a solid electrochemical element, characterized in that an ionically conductive path is formed between the solid electrolyte particles by contacting each other between the pair of facing surfaces of the solid electrolyte particle formed body by the integrally forming step. . 9. The method for producing a solid electrochemical element according to claim 8, wherein the plastic resin is a thermoplastic resin selected from polyethylene, polypropylene, acrylic resins and mixtures thereof.