JPH0261912A - Manufacture of solid electrolytic sheets - Google Patents

Abstract

PURPOSE:To improve precision of thickness, ionic conductivity, and display smoothness of a solid electrolytic sheet by kneading a solid electrolytic powder with specific grain size and content with an insulating polymer elastic body while milling the electrolytic powder so as to control the grain size and content of the electrolytic powder dispersed in the elastic body, forming the resulting mixture into a sheet, and drying the sheet. CONSTITUTION:A solid electrolytic powder of which 80wt.% and more has grain size 50mum and more, an insulating polymer elastic body, and a solvent are kneaded each other. At the same time, the solid electrolytic powder is milled so as to make 90wt.% and more of the powder have grain size 10mum and less and obtain a kneaded body in which the powder is dispersed. Then, the kneaded body is molded into a sheet and dried. As the solid electrolytic powder, a copper ion conductive or a silver ion conductive inorganic solid electrolytic powder such as KyRb1-yCu4I2-xCl3+x (Y=0-0.5; X=0.2-0.6), MAg4I5 (M stands for Rb or K) is used. To prepare the powder for usage, these electrolytic powders are recrystallized in chloric acid, vacuum-dried at room temperature, milled while using toluene as a dispersant, press-molded, and then heated at 130 deg.C in nitrogen flow.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a solid electrolyte sheet, and more particularly to a solid electrolyte sheet with excellent ionic conductivity used in solid micro batteries and the like.

[Prior Art] Technological advances in the electronics industry have been remarkable in recent years, and electronic components such as ICs and LSIs are now widely used in all fields.The field of battery technology is no exception, with products becoming smaller and thinner. It is widely used as power supplies for card-type calculators, cameras, wristwatches, etc.

Most of the batteries used in these applications are alkaline batteries or lithium batteries, and the electrolytes used are liquid electrolytes. Batteries using these liquid electrolytes require advanced processing techniques to seal the batteries, and at present, sealing techniques using crimp seals using gaskets are mainly used.

However, as the battery becomes thinner, the ratio of the sealing member to the battery volume increases, making it more difficult to provide the required battery capacity, and there is a limit to how thin the battery can be made.

Based on the above, attempts are being made to develop new electrolyte materials to make batteries thinner and lighter. For example, polymer electrolyte materials that take advantage of their advantages such as ease of processing and flexibility are being used for batteries. There are applications.

The ionic conductivity of the polymer electrolyte is about 10' s/cm at room temperature even if it is the best, and the selectivity of moving ions is poor, resulting in the movement of not only cations (for example, Li'') but also anions (for example, C104). However, it has not reached the stage of practical use due to problems such as the occurrence of

Further, attempts have been made to utilize ion-conducting solid electrolytes having high ion conductivity, such as silver ions and copper ions.

Since these solid electrolytes are inorganic solid powders, they must be pelletized by high-pressure press when processed into batteries, etc. The resulting pellets are hard and brittle, so it is difficult to homogenize and process them without impairing the electrochemical properties of the solid electrolytes. There is a limit to thinning, and it is difficult to obtain one with a large area.

Furthermore, when applied to batteries, etc., it is necessary to apply a large pressure to bring the electrolyte and electrode into close contact when bonding with the electrode active material, but there is a problem with variations in adhesion, and bonding over a large area is not uniform. There is also the problem that good adhesion cannot be obtained and furthermore, the solid electrolyte may be destroyed.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the problems of the prior art described above, and to improve ionic conductivity, uniformity of film thickness, surface smoothness, and improvement of electrode active materials when used as batteries. It is an object of the present invention to provide a solid electrolyte sheet that can be made thinner and larger in area and has excellent adhesion with other objects.

[Means for Solving the Problems] The present invention provides a solid electrolyte powder in which 80% by weight or more has a particle size of 50 μm or more, an insulating polymeric elastomer (hereinafter simply referred to as "polymer elastomer"), and a solvent. At the same time, the solid electrolyte powder is pulverized to prepare a kneaded product in which 90% by weight or more of the solid electrolyte powder has a particle size of 10 μm or less dispersed in an insulating polymer elastomer solution, and the kneaded product is made into a sheet. The present invention provides a method for producing a solid electrolyte sheet, which is characterized by forming the solid electrolyte sheet into a shape and then drying it.

As the solid electrolyte powder used in the present invention, for example, Ky
Rb Cu I C1(y:0t-y
4 2-x 3+x ~0.5, x:0,2~o,6), MAg415 (M
:Rb or K), copper ion conductive inorganic solid electrolyte powder or silver ion conductive inorganic solid electrolyte powder.
I C1 is 4 2-x 3+x preferred, and RbCu1C1 is particularly preferred. KyRb Cu I C1 and 1-
y 4 2-x 3+x Both MAg4I5 are crystalline substances [J, EIectr
ochem, Soc, L26.1858 (197
9)], and for example, RbCu I C1 is manufactured as follows. That is, CuC1 and Cul were recrystallized in hydrochloric acid and dried under vacuum at room temperature, while Rb
C1 was vacuum dried at 100°C, a predetermined amount of these component salts were mixed, heated at 130°C to completely dehydrate it, vacuum sealed in a Pyrex glass tube, heated and melted, and then allowed to cool to room temperature. The cooled and solidified product is thoroughly ground in a ball mill using toluene as a dispersant, the ground powder is pressure molded, treated at 130°C in a nitrogen stream, and then ground again in a ball mill to obtain a powder. .

Further, in the present invention, solid electrolyte powder in which 80% by weight or more has a particle size of 50 μm or more is used.

If the solid electrolyte powder is too small, its apparent specific gravity will be low and it will be difficult to handle. In addition, since the surface area becomes large, it is easily deteriorated during storage, and when formed into a sheet, the ionic conductivity decreases.

Examples of the polymeric elastomer used in the present invention include styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene block copolymer (SEP), polyethylene, polypropylene, polyethylene oxide, Polystyrene, vinyl chloride, ethylene-ethyl acetate copolymer, 1,4-polybutadiene, natural rubber, polyisoprene, SBRSNBRSE
PDM, EPM, urethane rubber, polyester rubber,
Chloroprene rubber, shrimp chlorohydrin gum, butyl rubber, phosphazene rubber, 1,2-polybutadiene, styrene-butadiene-styrene block copolymer (SBS
), styrene-isoprene-styrene block copolymer (SIS), and mixtures thereof. Among these, solubility with solvents, kneadability with solid electrolyte powder,
From the viewpoint of adhesiveness with the electrode active material and strength of the solid electrolyte sheet obtained, 5EBS and SEP are preferable. Specifically, as 5EBS, Kraton G-1650, G-1
652, G-1657XSG-1660X, G-172
6 (manufactured by She 11), and as SEP, Kraton G-1701X, G-1702X
(manufactured by She 11). Furthermore, from the viewpoint of flexibility, it is preferable to have an ASTM hardness of 90 or less.

In addition, from the viewpoint of heat resistance of the solid electrolyte powder, it is preferable that the solid electrolyte powder has moldability at 150° C. or lower, and it is particularly preferable that the solid electrolyte powder contains 50% by volume or more of an elastic polymer that does not contain unsaturated bonds. When the volume fraction is less than 50%, the decomposition voltage and electron transfer number of the obtained solid electrolyte sheet may deteriorate.

Examples of solvents include saturated hydrocarbon solvents that do not absorb water and do not react with the solid electrolyte powder, such as n-hexane, n-heptane, n-octane, cyclohexane, benzene, toluene, xylene, ethyl acetate, and trichlene, and aromatic solvents. Examples include hydrocarbon solvents, halogenated hydrocarbon solvents, and ester solvents, and these solvents have a boiling point of 70 to
Preferably, the temperature is in the range of 150°C. boiling point is 70'
If the temperature is less than 150°C, the evaporation rate of the solvent in the mixture will be too fast and a uniform large-area sheet may not be obtained.If the boiling point exceeds 150°C, the evaporation rate of the solvent will be slow and production Efficiency may deteriorate.

In the present invention, in order to uniformly disperse the solid electrolyte powder in the elastomer polymer, the solid electrolyte powder and the elastomer polymer are mixed using a solvent as a medium.

In this case, the order of addition of the solid electrolyte powder, the polymeric elastomer, and the solvent is not particularly limited, but in order to improve the uniformity of the mixture, a solution of the polymeric elastomer dissolved in the solvent and the solid electrolyte are added. The powder is uniformly kneaded using a ball mill, paint conditioner, homogenizer, etc., and at the same time the solid electrolyte powder is pulverized.

In the present invention, the solid electrolyte powder after kneading is pulverized so that 90% by weight or more has a particle size of 10 μm or less. If the particle size of the solid electrolyte powder after kneading is large, the obtained solid electrolyte sheet will have poor ionic conductivity and surface smoothness. A solid electrolyte sheet obtained using the solid electrolyte powder pulverized as described above has a uniform thickness, excellent surface smoothness, and no pinholes. It also has good ionic conductivity and excellent adhesion to copper plates and the like.

Here, the solid content weight concentration of the kneaded product containing the solvent is 50
~80% is preferred. If the solid content weight concentration is less than 50%, shearing force is not applied efficiently during kneading, and the viscosity is low, making it difficult to adjust the thickness of the solid electrolyte sheet, and if it exceeds 80%, This makes kneading difficult.

In the present invention, the solid electrolyte sheet is obtained by forming the kneaded material containing the solvent obtained as described above into a sheet shape and then drying it, but preferably the kneaded material containing the solvent obtained as described above is dried. The material is filled into the openings of the non-conductive mesh and then dried. Examples of the material of this non-conductive network include cellulose, nylon 6, nylon 66, polypropylene, polyethylene polyester, glass fiber, etc. Specific examples of the non-conductive network include materials such as Examples include woven or nonwoven fabrics.

The method for filling the openings of the non-conductive net with the kneaded material containing the solvent is to impregnate the net into the kneaded material containing the solvent, sufficiently adhere the kneaded material to the net, and then harden the kneaded material into the non-conductive mesh. Examples include a method of filling the opening with a blade, roll, or the like made of rubber, plastic, metal, etc., and removing excess adhering kneaded material. At this time, a Teflon sheet, a polyester sheet, etc. may be interposed between the blade, roll, etc. and the net-like body to which the kneaded material has adhered, and the excessively adhered kneaded material may be removed.

In this way, a solid electrolyte sheet is obtained by filling the openings of the non-conductive network with a kneaded material containing a solvent and drying it. The drying step is preferably carried out in an environment with a relative humidity of 30% or less. If the relative humidity exceeds 30%, the quality of the solid electrolyte powder may change. The method of keeping the relative humidity below 30% is not particularly limited.
The above steps may be performed in a dehumidified dry air atmosphere or an inert gas atmosphere such as nitrogen or argon.

In addition, in order to improve the conductivity and adhesion of a solid electrolyte sheet using a non-conductive network to the electrode active material used when used as a solid micro-battery, etc., it is necessary to It is preferable to have the kneaded material layer of 5 to 25 μm, and the thickness of the solid electrolyte sheet is preferably 10 to 250 μm. The thickness of the sheet is 10 μm
If the thickness is less than 250 mm, it will tear easily and will not maintain its strength.
If it exceeds μm, the conductivity tends to be less than I x 10' s/cm.

In the present invention, the volume fraction of the solid electrolyte powder in the solid electrolyte sheet is preferably 55 to 95%, more preferably 75 to 92%. When the volume fraction of solid electrolyte powder is less than 55%, the conductivity of the kneaded material is I
If the volume fraction is less than X 10' s /cm, it is not suitable for practical use, and if the volume fraction exceeds 95%, the obtained solid electrolyte sheet may become brittle.

Further, in the present invention, the hardness of the solid electrolyte sheet is preferably 65 to 96 in terms of ASTM-A hardness. When the hardness of the sheet is less than 65, the conductivity of the solid electrolyte sheet is I
X 10's/cm or less, and the hardness is 96
If it exceeds this, the flexibility of the solid electrolyte sheet may deteriorate and it may become brittle.

Furthermore, the solid electrolyte sheet obtained according to the present invention contains, for example, modified rosin, rosin derivative, terpene resin, coumaron-indene resin, phenol-modified coumaron-indene resin, etc. in the kneaded material in order to increase the adhesive strength with the electrode active material. A rosin tackifier, an aromatic tackifier or a terpene tackifier may be added.

[Example] Hereinafter, the present invention will be explained in detail with reference to drawings and examples, but the present invention is not limited to these examples.

FIG. 1 is an explanatory diagram showing the method for manufacturing a solid electrolyte sheet of the present invention.

In FIG. 1, a woven fabric 1 as a base material is dipped in a treatment solution 5 containing a kneaded material 2 of solid electrolyte powder, polymeric elastomer, and solvent by a feed roll 4, and then pulled up by a blade 3. After the kneaded material is sufficiently filled into the openings of the woven fabric, it is dried in a drying device (not shown) to obtain a solid electrolyte sheet.

Example 1 Styrene-ethylene-butylene-styrene block copolymer (hereinafter abbreviated as Is E B SJ, manufactured by Shell, trade name Kraton G-1650, specific gravity 2 0.92)
and styrene-butadiene-styrene block copolymer (
TR-20, manufactured by Japan Synthetic Rubber Co., Ltd., hereinafter abbreviated as rSBSJ
00, specific gravity: 0.96) were weighed so that the volume ratio was 8/2, and these were dissolved in toluene to obtain a polymeric elastomer solution with a solution weight concentration of 10%. This has a particle size of 60
RbCu4■1.5 with 80% by weight of particles larger than μm
C] 50 g of 3.5 solid electrolyte powder (specific gravity: 4.5) was added and mixed to obtain a mixture having a solid content weight concentration of 69%.

The resulting mixture was kneaded in a paint conditioner for 2 hours and transferred to a processing container 5 as shown in FIG.

Next, using a nylon woven fabric with a thickness of 50 μm, this woven fabric is immersed in the kneaded material in the processing container 5, and after the kneaded material is sufficiently adhered to the surface of the woven fabric, the fluororubber blade 3
While applying sufficient clamping force, the woven fabric was pulled out from the blade 3, and the kneaded material was filled into the openings of the woven fabric. The obtained sheet was sufficiently dried in a nitrogen stream to remove the solvent in the mixed material, and a solid electrolyte sheet was obtained. The thickness, gloss, total conductivity, and adhesion to the copper plate of the obtained solid electrolyte sheet, and the particle size of the solid electrolyte powder after kneading are 1.
The content ratio of particles of 0 μm or less was measured and evaluated by the following method, and the results are shown in Table 1.

Thickness: Using a dial thickness gauge (manufactured by Amagasaki Seisakusho),
The thickness of one solid electrolyte sheet (5 m x 0.225 m) was measured at 100 locations, and the average thereof was determined. Further, the coefficient of variation in thickness was determined from the average of the differences between the average thickness value and the measured value at each location, as shown in the following equation.

standard deviation Coefficient of variation (CV) - xloo (%) average value Measured at 45° using a gloss Nigelosmeter.

Total conductivity: solid electrolyte sheet sandwiched between copper plates, 130°
It was bonded by applying a pressure of 10 kg/crI for 5 minutes at C, and the impedance at AC I K11z was LCR.
It was evaluated using a meter (YHP4274A) and determined from its DC component (6A).

Adhesion to copper plates: sandwich the solid electrolyte sheet between copper plates,
A pressure of 10 kg/cd was applied at 30° C. for 5 minutes, and the solid electrolyte sheet adhered to the copper plate was subjected to a base grain test (commercial cellophane tape, fold size = 1 mm x 1 mm, number of tests = 100 times) for evaluation.

Content ratio of particles with a particle size of 10 μm or less: The kneaded product after kneading was observed with a scanning electron microscope (JSM-840).

Example 2 A solid electrolyte sheet was produced in the same manner as in Example 1, except that the volume fraction of the solid electrolyte powder in the kneaded material with respect to the polymer elastomer was 90% and the solid content weight concentration was 79%. The properties were evaluated and the results are shown in Table 1.

Comparative Example 1 In Example 1, the weight concentration of the polymeric elastomer solution was 4%, the volume fraction of the solid electrolyte powder to the polymeric elastomer in the kneaded product was 55%, and the solid content weight concentration was 22%, and paint A solid electrolyte sheet was obtained in the same manner as in Example 1, except that the kneading with the conditioner was carried out for 50 minutes, and its properties were evaluated. The results are shown in Table 1.

Comparative Example 2 In Example 1, the particle size of the solid electrolyte powder before kneading was 10
A solid electrolyte sheet was obtained in the same manner as in Example 1 except that it contained 90% by weight or more of particles of .mu.m or less, and its properties were evaluated. The results are shown in Table 1.

Margin below [Effects of the Invention According to the present invention, it is possible to obtain a solid electrolyte sheet with extremely excellent thickness accuracy, high ionic conductivity, and excellent surface smoothness. In addition, the solid electrolyte sheet obtained by the present invention has excellent adhesion with electrode active materials when manufacturing batteries, and can be made thinner and larger in area. It is useful as a material for electrochemical devices such as electrolyte sheets for solid-state microbatteries, electrochromic display devices, and electric double layer capacitors.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the method for manufacturing a solid electrolyte sheet of the present invention. 1...Woven fabric 2...Mixed solution 3...Blade 4...Feed roll 5...Processing container 5: Processing container patent application Person Japan Synthetic Rubber Co., Ltd. Procedural Amendment 1. Display of the case Japanese Patent Application No. 63-211689 2, Name of the invention Method for manufacturing solid electrolyte sheet 3, Person making the amendment Relationship to the case Patent applicant address 2-11-24 Tsukiji, Chuo-ku, Tokyo Contact information Tokyo Japan Synthetic Rubber Co., Ltd. Patent Department, 2-11-24 Tsukiji, Chuo-ku, Tokyo Telephone: (03) 541-4111 ■ 5. Contents of amendment (1) The following statement must be made between lines 8 and 9 on page 9 of the specification. Add text. "The smaller the particle size of the solid electrolyte powder after kneading, the smaller the electronic conductivity." ” he corrected. (3) "Content ratio of particles of 10 μm or less" in line 17 of the same page of the same book is corrected to "content ratio of particles of 10 μm or less and particles of 1 μm or less". (4) Circular, page 15, line 7 from the bottom Add the following text between the 6th line from the bottom. [Electronic conductivity: A solid electrolyte sheet was sandwiched between a platinum plate and a copper plate, and the sheets were bonded together by applying a pressure of 10 kg/cJ at 130°C for 5 minutes. (5) P. 16, line 1 of the same book, "Grain "Content ratio of particles with a diameter of 10 μm or less" should be corrected to "Content ratio of particles with a diameter of 10 μm or less and particles with a diameter of 1 μm or less." (6) The following sentence should be added between lines 9 and 10 of the same page of the inquiry letter [Example 3] A solid electrolyte sheet was obtained in the same manner as in Example 1 except that the obtained mixture was kneaded in a paint conditioner for 6 hours, its properties were evaluated, and the results are presented. (7) "Table 1" on page 18 of the same book is corrected as shown in the attached sheet.

Claims (1)

[Claims] A solid electrolyte powder in which 80% by weight or more has a particle size of 50 μm or more, an insulating polymer elastomer, and a solvent are kneaded and the solid electrolyte powder is simultaneously pulverized to produce a solid electrolyte in which 90% by weight or more has a particle size of 10 μm or less. A method for producing a solid electrolyte sheet, which comprises preparing a kneaded product in which powder is dispersed in an insulating polymer elastomer solution, forming the kneaded product into a sheet shape, and then drying the kneaded product.