JPS63239774A - Solid electrolyte sheet and its manufacture - Google Patents

Abstract

PURPOSE:To make it possible to obtain a thin type and a large area size by dispersing a specific solid electrolyte powder in an insulating high polymer elastic body evenly at a volume percentage 55 to 95 %. CONSTITUTION:This solid electrolyte sheet is composed of an ion conductive inorganic solid electrolyte powder (solid electrolyte powder) and an insulating high polymer elastic body. And the solid electrolyte powder is dispersed in the insulating high polymer elastic body evenly at a volume percentage 55 to 95 %. The hardness is 65 to 96 (ASTM A hardness), and the thickness is 10 to 250 mum. In such a composition, a thin type and a large area size can be realized, and can be used as an electrolyte sheet for a thin type cell less than 1.0 mm thick.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a solid electrolyte sheet and a method for manufacturing the same.
More specifically, the present invention relates to a solid electrolyte sheet with excellent ionic conductivity used, for example, in solid microbatteries, and a method for producing the same.

(Prior art) Technological advances in the electronics industry have been remarkable in recent years, and electronic components such as ICs and LSIs are widely used in all fields.The field of battery technology is no exception, and miniaturization,
It is designed to be thin and 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 that use these liquid electrolytes require advanced processing technology to seal the battery, and currently the sealing technology that uses crimp seals with gaskets is mainly used, but the thinner the battery, the more difficult it is to seal the battery. As the ratio of the components to the battery volume increases, it becomes 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. It has applications in batteries, etc.

(oligooxyethylene)-alkali metal salt system, but 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 mobile ions is poor, and the cation ( For example, there are problems such as migration of not only Li") but also anions (for example, ClO4'"), and this method has not yet reached a practical stage.

In addition, attempts have been made to use ionic conductive solid electrolytes such as silver ions and copper ions that have high ionic conductivity, and typical examples include RbAg4■5, copper ion conductive solid electrolytes, and silver ion conductive solid electrolytes. RbCu4I as an ion conductive solid electrolyte 1. ! 5 C1 clause, 0.4LiSi04-0 as lithium ion conductive solid electrolyte
．． 6Li3VO4, H as a proton-conducting solid electrolyte
3MO12PO4゜・29H20 and H3W12PO,,
There are 29H20 etc.

Since these solid electrolytes are inorganic solid powders, they must be pelletized by high-pressure pressing when processed into batteries, etc., which is a major obstacle in achieving productivity, uniformity, etc. In addition, the resulting pellet is hard (and brittle, so
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 force to bring the electrolyte and electrode into close contact when bonding with the electrode active material, resulting in problems with variations in workability, adhesion, etc. Uniform adhesion cannot be obtained by joining
There is a problem with electrolyte breakdown.

(Problems to be Solved by the Invention) An object of the present invention is to solve the problems of the prior art, and to provide a solid electrolyte with excellent ionic conductivity that has excellent processability, productivity, storage stability, and flexibility. It is an object of the present invention to provide a solid electrolyte sheet that has excellent adhesion to an electrode active material and can be made thinner and larger in area, and a method for producing the same.

(Means for Solving the Problems) The solid electrolyte sheet of the present invention is composed of an ion-conductive inorganic solid electrolyte powder (hereinafter simply referred to as "solid electrolyte powder") and an insulating polymeric elastomer. The electrolyte powder is uniformly dispersed in the insulating polymer elastic body at a volume fraction of 55 to 95%, the hardness is 65 to 96 (ASTM A hardness), and the thickness is 10 to 250 μm. .

As the solid electrolyte powder used in the present invention, for example, K
y Rb+-y Cu 4 ■2-X Cl 3tx
(yi O~0.5, x;0.2~0.6), MA
g4Ih (M; Rb or K), 0.4LiSi
040.6Li3 VO4, H3Mo12PO40・2
9 H20, H3W12PO46・29H20, etc., and RbCu+
l2-X C(13+x (x: 0.2-0.6
) is preferred, especially Rb Cu 4I1. ! s Cl
35 is preferred. RbCu4I2-x Cff3+x and MAg4I! s are both crystalline substances (J, Ele
ctrochem.

Soc, 126.1658 (1979)),
For example, RbCu4 I 2-x C13+x is produced as follows.

That is, RbCu4I2-x Cff3+x is Cu
Cl and CuI are recrystallized in hydrochloric acid and converted into p2
0! ! Vacuum-dried at room temperature in a desiccator containing a desiccant, while RbC1 was vacuum-dried at 100'C, predetermined amounts of these component salts were mixed, and heated at 130'C for 17 hours to completely remove water. This was vacuum sealed in a Pyrex glass tube, melted, and slowly cooled to room temperature.The solidified product was thoroughly ground in a ball mill using toluene as a dispersant, and the ground powder was pressure molded.
'C for about 17 hours, and the resulting press-molded product is ground again in a ball mill to obtain a powder.

The shape and particle size of the solid electrolyte powder used in the present invention are not particularly limited, but from the viewpoint of ease of mixing with the insulating polymer elastomer, etc. Preferably, those that pass through.

Examples of the insulating polymer elastomer used in the present invention include 1,4-polybutadiene, natural rubber, polyisoprene, SBR, NBR, EPDM, EPM, urethane rubber,
Polyester rubber, chloroprene rubber, epichlorohydrin rubber, silicone rubber, styrene-butadiene
Styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS)
, styrene-ethylene-butylene-styrene J" polymer (5EBS), butyl rubber, phosphazene rubber, polyethylene, polypropylene, polyethylene oxide, polypropylene oxide, polystyrene, vinyl chloride, ethylene-ethyl acetate copolymer, 1゜2-polybutadiene, Examples include epoxy resin, phenol resin, cyclized polybutadiene, cyclized polyisoprene, polymethyl methacrylate, and mixtures thereof, but from the viewpoint of adhesion to the electrode active material, 5BSSSIS, 5EBS, 1,2-polybutadiene, etc. It is preferable to have thermoplasticity, and from the viewpoint of flexibility, it is preferable to have ASTM A hardness of 90 or less.Also, from the viewpoint of heat resistance of the solid electrolyte powder, 150 ° C.
It is preferable that the material has the following moldability.

As a method for uniformly dispersing solid electrolyte powder in an insulating polymeric elastic material and forming a sheet, ion conductive solid electrolyte powder is mixed in a volume fraction of 55 to 95% and an insulating polymeric elastic material is mixed in a volume fraction of 55 to 95%. 5 to 45% of the solvent is mixed with at least one solvent selected from saturated hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, and ester solvents,
By applying the obtained mixture onto the substrate and drying it,
There is a method of forming a sheet having a hardness of 65 to 96 (ASTM A hardness) and a thickness of 10 to 250 μm.

In this case, the order in which the solid electrolyte powder, insulating polymer elastomer, and solvent are added is not particularly limited; A preferred method is to knead the polymer solution and solid electrolyte powder using a ball mill or the like, roll the resulting mixture using an applicator bar or the like, and dry the solvent to obtain a sheet. The above method has the following advantages: a thin film with a thickness of 100 μm or less is obtained, there is little heat generation during kneading (the solid electrolyte powder is hard to change or decompose), there is almost no contact with the atmosphere during rough kneading, and the solid electrolyte This is preferable because it is easy to consider the working environment because the powder is difficult to change or decompose due to moisture and oxygen.The specific solvent used in this manufacturing method is, for example, n-
Saturated hydrocarbon solvents that do not absorb water and do not react with solid electrolyte powder, such as hexane, n-hebutane, n-octane, cyclohexane, benzene, toluene, xylene, ethyl acetate, and trichlene, aromatic hydrocarbon solvents, and halogenated carbonized solvents. Examples include hydrogen solvents or ester solvents, and 1,4-polybutadiene, natural rubber, polyisoprene, SBR, NBR, etc. soluble in the above solvents as the insulating polymer elastomer.
SBS, SIS.

Preferably, 5EBS, butyl rubber, phosphazene rubber, polyethylene oxide, polystyrene, 1,2-polybutadiene, etc. are used.

Other manufacturing methods other than those mentioned above include, for example, kneading an insulating polymer elastomer and solid electrolyte powder in a two-axis mixing device,
Examples include a method of rolling the obtained mixture into a sheet.

In the solid electrolyte sheet of the present invention, the volume fraction of the solid electrolyte powder used in the insulating polymer elastomer is 55
It is important to set it to ~95%, preferably 75-92%. If the volume fraction of the solid electrolyte powder is less than 55%, the conductivity will be less than IXlXlo-6s7, which is not suitable for practical use. Moreover, if the volume fraction exceeds 95%, the sheet becomes brittle and cannot maintain its shape as a sheet.

Further, the hardness of the solid electrolytic sheet of the present invention is as per ASTM
A hardness is 65 to 96. If the hardness of the sheet is less than 65, the electrical conductivity will be 1×10″″6 s/cm or less, making it unsuitable for practical use. If the hardness exceeds 96, the flexibility will be poor.

Furthermore, the thickness of the solid electrolyte sheet of the present invention is 10 to 2
It is 50 μm. If the thickness of the sheet is less than 10 μm, it will easily tear and its strength will not be maintained. Moreover, if the thickness exceeds 250 μm, the conductivity tends to be 1×10″″6 s/cm or less.

The solid electrolyte sheet of the present invention uses a rosin-based tackifier such as a modified coumaron-indene resin, a rosin derivative, a terpene resin, a coumaron-indene resin, a phenol-modified coumaron-indene resin, etc., in order to increase the adhesive strength with the electrode active material. , an aromatic tackifier or a terpene tackifier may be added.

(Examples) Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 3, Comparative Examples 1 to 2 CuCISCu I and RbC1 in molar ratio Cucl
: Cu I : RbCj! =2.5 : 1.5
: Each was weighed so that the ratio was 1:1. Recrystallize the CuCa and CuI in hydrochloric acid, vacuum dry them in a desiccator containing a P2O5 desiccant,
On the other hand, the above RbCg was vacuum dried at 100°C, a predetermined amount of these component salts were mixed, and the mixture was heated at 130°C for 17 hours to completely dehydrate it, and this was vacuum sealed in a Pi 1 Nox glass tube and melted. After that, it was slowly cooled to room temperature, and the solidified material was milled in a ball mill using toluene as a dispersant.
After processing for about an hour, the obtained pressure-molded product was ground again in a ball mill to obtain Rb Cu 4 I 1. ! tC
135 powder was obtained.

Next, a styrene-butadiene-styrene broth copolymer (TR-2000 manufactured by Japan Synthetic Rubber Co., Ltd.) was dissolved in toluene to obtain a polymer solution, and this was added to the particle size 2 obtained above.
RbCu4I1.00 mesh or less. ICβ solid electrolyte powder (specific gravity: 4.5) whose volume fraction is 60% and 80%
, 90% (Examples 1 to 3) and 50% and 96% (Comparative Examples 1 to 2), and kneaded in a ball mill for 2 hours. The resulting mixture was placed on a Teflon sheet with an applicator bar. The sheet was stretched in a vacuum cleaner, and the toluene was evaporated in dry air to obtain each sheet.

The hardness, thickness, bending resistance, adhesion to a copper plate, total conductivity, and electron transport number of the obtained sheet were measured and evaluated by the following methods.

Hardness: A solid electrolyte sheet was folded to a thickness of about 1 inch and evaluated by ASTM A hardness on a glass plate.

Bending resistance: A bending test was conducted at a radius of 80 f1, and evaluation was made based on the number of times the sheet cracked or broke.

Adhesion to copper plate: Place a solid electrolyte sheet on a well-polished copper plate, place a Teflon sheet on top, and heat at 130°C.
So 10kg/co! Pressure was applied for 5 minutes, and a base test (commercial cellophane tape, square size = 5wm x 5 dragons, n = 100) was performed on the solid electrolyte sheet adhered to the copper plate, and evaluation was made by the number of squares that peeled off.

Total conductivity: solid electrolyte sheet sandwiched between copper plates at 130℃
The impedance at AC I KHz was evaluated using an LCR meter (YHP4274A), and its DC component (6A
).

Electron transport number: A solid electrolyte sheet was sandwiched between platinum plates and bonded by applying a pressure of 10 kg/cd at 130°C for 5 minutes in the same manner as above, and gradually changing the DC voltage from 0 to 0.5 ■. , the ratio (6D/6) of the DC conductivity (6D) obtained by evaluating the amount of current flowing and the above DC component (6A)
A).

Table 1 shows the measurement results of Examples 1-3 and Comparative Examples 1-2. It can be seen that the solid electrolyte sheet of the present invention has improved total conductivity etc. compared to the comparative example in which the volume fraction is outside the range.

Moreover, the relationship between the volume fraction and the total conductivity of Examples 1 to 3 is shown in FIG.

Below is the margin: Table 1: Example 4: The sheet fell apart when it was made, making it impossible to sue.
~6 Styrene-butadiene-styrene block copolymer (J
R-2000) pellets and solid electrolyte powder (Example 1~
3) at 110°C in a twin-screw kneading device.
The mixture was kneaded for 0 minutes, and the resulting mixture was rolled and formed using twin-screw rolls to obtain a solid electrolyte sheet. The obtained sheet was subjected to the same measurements as in Examples 1 to 3, and the results were reported in the second
Shown in the table.

Table 2 and above show examples in which a copper ion conductive solid electrolyte is used as the solid electrolyte, but other ion conductive solid electrolytes, such as silver ion conductive, lithium ion conductive, proton conductive solid electrolytes, etc. Needless to say, the same effect can be obtained by using the same method.

(Effects of the Invention) According to the solid electrolyte sheet and the manufacturing method thereof of the present invention, it has superior specific ion conductivity compared to conventional polymer electrolytes, and has excellent processability, productivity, storage stability, and flexibility, and It has excellent adhesion to the active material and can be made thinner and larger in area. Otm
It has become possible to apply the following as an electrolyte sheet for thin batteries.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between volume fraction and total conductivity in Examples 1 to 3.

Claims (3)

[Claims] (1) consisting of an ion-conducting inorganic solid electrolyte powder and an insulating polymeric elastomer, the inorganic solid electrolyte powder being uniformly dispersed in the insulating polymeric elastomer at a volume fraction of 55 to 95%; A solid electrolyte sheet having a hardness of 65 to 96 (ASTMA hardness) and a thickness of 10 to 250 μm. (2) The inorganic solid electrolyte is RbCu_4I_2_-_x
The solid electrolyte sheet according to claim 1, characterized in that Cl_3_+_x (x is 0.2 to 0.6). (3) Ion conductive inorganic solid electrolyte powder at a volume fraction of 55 to 95% and insulating polymer elastic material at a volume fraction of 5%
~45% saturated hydrocarbon solvent, aromatic hydrocarbon solvent,
By mixing with at least one solvent selected from halogenated hydrocarbon solvents and ester solvents, and applying the resulting mixture onto a substrate and drying it, the hardness can be increased to 65 to 96.
(ASTMA hardness) and a thickness of 10 to 250 μm.