JPH0482166A - Manufacture of solid electrolytic sheet - Google Patents

Abstract

PURPOSE:To improve workability, productivity, shelf stability, flexibility and adhesiveness to an electrode active material by charging a mixed solution containing a multicomponent amorphous solid electrolyte powder composed of a specified compound, lithium iodide and lithium sulfide and a high polymer elastic body into an opening of non-conductive netting body, and thereafter drying them. CONSTITUTION:A multicomponent amorphous solid electrolytic powder is composed of at least one kind compound selected from a group consisting of boron sulfide, phosphorus sulfide and silicon sulfide, lithium iodide and lithium sulfide. The electrolyte powder is dried and accommodated in a quartz tube, subsequently being sealed in vacuum, and is heated and quenched, to form a massive product. The product is pulverized with a ball mill. The electrolytic sheet is obtained by charging a mixed solution of the solid electrolyte powder, high polymer elastic body and a solution in an opening of a non-conductive netting body, and drying it.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a solid electrolyte sheet, and more specifically to a solid electrolyte sheet with excellent ionic conductivity and high decomposition voltage, used for example in solid micro batteries. Relating to a manufacturing method.

[Conventional technology]

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, as batteries are becoming smaller and thinner, and are used in large quantities as power sources for card-type calculators, cameras, wristwatches, and the like.

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 via gaskets is mainly used, 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. Examples include polymer electrolyte batteries that take advantage of their advantages such as ease of processing and flexibility. It is known to be applied to A typical example is poly(oligooxyethylene methacrylate)-
Examples include alkaline earth bases, but the ionic conductivity of the polymer electrolyte is 1O-5s/c at room temperature even if it is the best.
In addition, the selectivity of mobile ions is poor, and it is difficult to select not only cations (e.g. Li'') but also anions (e.g. Cj2
There are problems such as movement of 04-), and it has not reached the stage of practical use.

In addition, attempts have been made to use ion-conductive solid electrolytes with high ionic conductivity, such as silver ions and copper ions, and representative examples include RbAgn1s and A
Silver ion conductive solid electrolyte such as g614 Wo4, R
bCu4 I, 5CI2. ．． Examples include copper ion conductive solid electrolytes such as No. 5 and the like.

However, since these have a low decomposition voltage of 0.5 to 0.6 sq., it is impossible to obtain a battery with a voltage higher than that voltage, and the range of application is limited.

On the other hand, lithium ion conductive solid electrolytes are known as solid electrolytes with high ionic conductivity and high decomposition voltage, and B2S3 L is a typical example.
izS Li1. , P2S5 Liz 5-Li
Examples include multi-component amorphous solid electrolytes such as I, Sin, -Li2S-LiT, and the like.

However, since these solid electrolytes are inorganic solid powders, it is necessary to pelletize them using high-pressure pressing when processing them into batteries, etc., which is a major obstacle in achieving productivity, uniformity, etc. Furthermore, since the resulting pellets are hard and brittle, there is a limit to how thin they can be made, and it is difficult to obtain pellets 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, resulting in problems with workability, adhesion, etc. There is a problem that uniform adhesion cannot be obtained during bonding, resulting in destruction of the electrolyte.

[Problem to be solved by the invention]

The purpose of the present invention is to improve processability by using a multi-component amorphous solid electrolyte with excellent ionic conductivity and high decomposition voltage.
To provide a method for manufacturing a solid electrolyte sheet that can obtain a solid electrolyte sheet with excellent productivity, storage stability, flexibility, and adhesion to an electrode active material, and that can be made thinner and larger in area. be.

[Means to solve the problem]

The present invention provides a liquid mixture containing a multi-component amorphous solid electrolyte powder consisting of at least 18 compounds selected from boron sulfide, phosphorus sulfide and silicon sulfide, lithium iodide and lithium sulfide, and an elastomer polymer. The present invention relates to a method for manufacturing a solid electrolyte sheet, which comprises filling openings in a conductive network and then drying the sheet.

The multicomponent amorphous solid electrolyte powder used in the present invention is composed of at least one compound selected from boron sulfide, phosphorus sulfide, and silicon sulfide, lithium iodide, and lithium sulfide, and is, for example, represented by the following general formula (I) χM-yLi1 ~(1-x-y) Li, S
(r) (where M is B2 S3 , Pz Ss and SiS.

at least one compound selected from, X is 0.1 to 0
．． 3, preferably 0.15 to 0.25, y is 0.2 to 0
, 5, preferably 0.3 to 0.5).

For example, when M is B2 S3, the multicomponent amorphous solid electrolyte powder contains predetermined amounts of B, S, Lil and L+z
After mixing and drying S, place it in a quartz tube and vacuum seal it.
It can be obtained by heating at 500° C. for 12 hours and further at 800″C for 3 hours, then quenching with ice water to obtain a lumpy product, and pulverizing this product with a ball mill or the like.

Examples of the elastic polymer used in the present invention include 1,
4-Polybutadiene, natural rubber, polyisoprene, SB
R, 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 cofi combination (sEBS)
, styrene-ethylene-propylene block copolymer (
SEP), butyl rubber, phosphazene rubber, polyethylene, polypropylene, polyethylene oxide, polypropylene oxide, polystyrene, vinyl chloride, ethylene-ethyl acetate copolymer, 1,2-polybutadiene, epoxy resin, phenol resin, cyclized polybutadiene, cyclized poly Examples include isoprene, polymethyl methacrylate, and mixtures thereof. Among these, SBS, STS, 5EBS, 12-
Thermoplastic materials such as polybutadiene are preferred;
Furthermore, from the viewpoint of flexibility, the AsTM-A hardness is preferably 90 or less. In addition, from the viewpoint of heat resistance of solid electrolyte powder,
Those having moldability at temperatures below 0°C are preferred.

In the present invention, the multicomponent amorphous solid electrolyte powder usually has a volume fraction of 30 to 95% in the elastomer polymer.
, preferably 55 to 92%. When the volume fraction of solid electrolyte powder is less than 30%, the conductivity of the mixture is I
If the volume fraction exceeds 95%, the obtained solid electrolyte sheet may become dangerous.

The hardness of the mixture of the solid electrolyte powder and the polymeric elastomer is preferably 65 to 9G in terms of ASTM-A hardness. When the hardness of the mixture is less than 65, the conductivity of the mixture I
If the hardness is less than 10-hs/cm, it is not suitable for practical use, and if the hardness exceeds 96, the resulting solid electrolyte sheet may have poor flexibility and become brittle.

In addition, in the present invention, in order to uniformly disperse the multi-component amorphous solid electrolyte powder in the polymeric elastomer, solid electrolyte powder with a volume fraction of 30 to 95% and a volume fraction of 5 to 95% dissolved in a solvent are used. It is used by mixing it with a 70% polymer elastomer solution. At this time, the order of addition of the solid electrolyte powder and the polymer elastomer solution is not particularly limited. In addition, in order to improve the uniformity of the mixture and make it a highly filling mixture, it is preferable to crush the solid electrolyte powder being mixed into fine particles, and use a mixing method that applies shearing force such as a ball mill or homogenizer. It is preferable.

Examples of the solvent used in this case include saturated hydrocarbons 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, trichlene, etc. Examples include solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, and ester solvents, and the boiling point of these solvents is preferably in the range of 70 to 150°C. If the boiling point is less than 70°C, the evaporation rate of the solvent in the mixture may be too fast when filling the mixture into the openings of the non-conductive network, so a uniform large-area sheet may not be obtained; If the temperature exceeds 150°C, the degree of development of the solvent may be slowed down, resulting in poor production efficiency. Further, the solid content concentration of the mixture contained in these solvents is preferably 50
~80% by weight.

The solid electrolyte sheet of the present invention is obtained by filling the openings of a non-conductive network with a liquid mixture containing the solid electrolyte powder obtained as described above, an elastic polymer, and a solution, and drying the mixture. 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:
Woven fabrics or nonwoven fabrics made of these materials can be mentioned. The aperture ratio of these net-like bodies is suitably in the range of 35 to 65%. Here, the aperture ratio is defined as the ratio of the total aperture area per unit area of the mesh. If the aperture ratio is less than 35%, the conductivity of the solid electrolyte sheet will be low, and if the aperture ratio exceeds 65%, the strength of the solid electrolyte sheet will be insufficient. In addition, the specific surface area of these networks is 50 to 10,0
A range of 00 rrr/g is suitable. Furthermore, in the case of non-woven fabric, the appropriate date range is 5 to 50 g/rrf.

The thickness of the mesh body is preferably in the range of 10 to 150 μm in consideration of the strength of the network body itself and the thinning of the battery, and the average area per opening is 1.6XIO-3 to 9X10
-2mm2 and the width between adjacent openings is 20-120
μm is preferred.

The method of filling the openings of the non-conductive network with the liquid mixture containing the solid electrolyte powder, the polymeric elastomer, and the solution includes:
After impregnating the net-like body in the mixed liquid and sufficiently adhering the mixed liquid to the net-like body, filling the opening with a blade, roll, etc. made of hard rubber, plastic, metal, etc.,
One example is a method of removing excessively attached mixed liquid. 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 mixed liquid has adhered, and the excessively adhered mixed liquid may be removed.

The solid electrolyte sheet of the present invention is obtained by filling the mixed liquid into the openings of the non-conductive network and drying it in this way. 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 for maintaining the relative humidity at 30% or less is not particularly limited, and the above steps may be performed in an atmosphere of dehumidified dry air or an inert gas atmosphere such as nitrogen or argon.

The solid electrolyte sheet of the present invention is made by filling the openings of a non-conductive network with a mixture of solid electrolyte powder and an elastomer polymer. In order to improve the
It is preferred to have m said mixture layers.

Moreover, the thickness of the solid electrolyte sheet of the present invention is preferably 10 to 250 μm. If the thickness of the sheet is less than 10 μm, it will easily tear and will not maintain its strength. Also, the thickness is 2
If it exceeds 50 μm, the conductivity I x 10-”s 7c
It is likely to be less than m.

According to the above method, since the non-conductive network is used as the base material, a solid electrolyte sheet with extremely excellent thickness accuracy can be obtained.
Furthermore, since it can be manufactured continuously, it has the advantage that a large-area solid electrolyte sheet can be easily obtained.

〔Example〕

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

Example 1 (1) B, S, Liz S and LiI, B:S
: L iz S : L i I = 0.46 :
They were weighed so that the ratio was 0.69:0.30:0.47 (molar ratio). After mixing these raw materials, 6
It was vacuum dried at 0°C, placed in a quartz tube, and vacuum sealed. This was heated at 500°C for 12 hours, followed by 800°C for 3 hours, then quenched with ice water to give a lumpy product.

This product is pulverized with a ball mill to give a particle size of 0.238z33-0.30LizS with a particle size of 200 mesh or less.
A multi-component amorphous solid electrolyte powder (specific gravity 2.6) represented by -0.47LiI was obtained.

(2) Next, a styrene-butadiene-styrene block copolymer (manufactured by Japan Synthetic Rubber Co., Ltd., TR-2000) was dissolved in toluene to obtain a polymer solution, and the above-mentioned (1)
0.23B, 33 with a particle size of 200 mesh or less obtained in
-0.30Liz S-A solid electrolyte powder represented by 0.47Lil was added at a volume fraction of 90 to the copolymer.
% and kneaded in a ball mill for 2 hours, the resulting mixture was transferred to a container and adjusted to a solid content concentration of 60% by weight.

(3) As the woven fabric, use a polyester woven fabric with a thickness of 50 μm, an average area of 5.5 x 10-"tan" per opening, and a width of 50 μm between adjacent openings, and place this woven fabric inside the container. After soaking in the mixed solution and sufficiently adhering the mixed solution to the surface of the woven fabric, pinch the woven fabric with a blade, and while applying sufficient clamping force, pull the woven fabric from the blade to apply the mixed solution onto the woven fabric. The opening was filled. The obtained sheet was sufficiently dried in a nitrogen stream to remove toluene, and a solid electrolyte sheet with a thickness of 70 μm was obtained.

The total electrical conductivity, decomposition voltage and hardness of the obtained sheet were measured by the following methods, and the results are shown in Table 1.

Total conductivity: Gold was deposited as electrodes on both sides of the obtained sheet by vapor deposition, and the total conductivity (Sew-') was determined from a Cole-Cole plot using an LCR meter (manufactured by YHP Corporation, YHP4274A) using a conventional method. Ta.

Decomposition voltage: Using a platinum plate for the anode and LiM for the cathode, a solid electrolyte sheet was sandwiched between the electrode plates and bonded by applying a pressure of 10 kg/cJ at 130°C for 5 minutes.The DC voltage was gradually increased. The resulting equilibrium current value (a current value that is constant under a constant voltage) was determined, and from this voltage-equilibrium current value relationship, the voltage at which the equilibrium current value suddenly increased was determined as the decomposition voltage.

Hardness: Solid electrolyte sheet folded, approximately 1mm thick
The hardness was evaluated by ASTM A hardness on a glass plate.

Example 2 (1) LiI and Li, P, S, LiI:Li4
P,57=0.45:0.18 (molar ratio). After mixing these raw materials, 60
It was dried under vacuum at °C, placed in a quartz tube, and sealed under vacuum. 90
Once heated to 0°C to melt the mixture, then heated to 700°C.
C for 30 minutes and then quenched at 110°C to obtain a lumpy product. This product is ground in a ball mill,
0.19Pz Ss 0.19Pz Ss with particle size of 200 mesh or less.
A multi-component amorphous solid electrolyte powder (specific gravity 2.7) represented by 36Liz SO, 45Lil was obtained.

(2) In the same manner as in (2) of Example 1, a polymer solution of styrene-butadiene-styrene block copolymer was obtained, and this was added to
．． 19P2S, 0.36LlzS 0.45Li
The solid electrolyte powder represented by I was mixed so that its volume fraction was 90% of the above copolymer, kneaded in a ball mill for 2 hours, and the resulting mixture was transferred to a container and the solid content concentration was 55%. Eight rounds were made to give a weight percentage.

(3) As the woven fabric, use a polyester woven fabric with a thickness of 50 μm, an average area of 5.5 x 10-0-2 rr per opening, and a width of 50 μm between adjacent openings, and use this woven fabric inside the container. After immersing the woven fabric in the mixed solution and sufficiently adhering the mixed solution to the surface of the woven fabric, sandwich the woven fabric with a blade, and while applying sufficient clamping force, pull the woven fabric from the blade to apply the mixed solution onto the woven fabric. The opening was filled. The obtained sheet was sufficiently dried in a nitrogen stream to remove toluene, and a solid electrolyte sheet with a thickness of 60 μm was obtained.

The total conductivity and decomposition voltage of the obtained sheet were measured by the following methods, and the results are shown in Table 1.

Example 3 (1) StS2 and I, +zS, 5iSz:Li2
They were weighed so that the ratio was 5=0.4:0.6 (molar ratio). After mixing these raw materials, they were vacuum dried at 60°C, heated at 950°C for 1 hour in an argon atmosphere, taken out, quenched with liquid nitrogen, and dried at 0.4°C.
SiSz 0.6L12S was obtained. After pulverizing this with a ball mill, LiI is Lid: (0,43i 52
-0.6 Liz S) -〇, 4:0.6 (molar ratio), heated again, and then quenched to obtain a product. This product is pulverized with a ball mill to obtain a particle size of 0.24'3+Sz with a particle size of 200 mesosius or less.
A multi-component amorphous solid electrolyte powder (specific gravity 2.6) represented by 0.36Liz SO, 4LtI was obtained.

(2) In the same manner as in Example 1, styrene-butadiene-
A polymer solution of the styrene block copolymer is obtained, and a 0.24
S i 32-0.36 L iz S-0゜4Li
The solid electrolyte powder indicated by l was mixed so that its volume fraction was 90% of the above copolymer, kneaded in a ball mill for 2 hours, and the resulting mixture was transferred to a container to give a solid content concentration of 57. It was adjusted to % by weight.

(3) The mixed solution obtained above was filled into the opening of a polyester woven fabric in the same manner as in Example 1 (3), and the thickness was 65 mm.
A solid electrolyte sheet of μm size was obtained.

The total conductivity and decomposition voltage of the obtained sheet were measured by the following methods, and the results are shown in Table 1.

Comparative Example 1 (1) 0.23B2 S3-0.
A multi-component amorphous solid electrolyte powder represented by 30Liz S 0.47Li I was obtained.

(2) Next, powdered Teflon and the solid electrolyte powder obtained in (1) above were mixed in a mortar so that the volume fraction thereof was 90%.

Using a press, press the mixture to a diameter of 1 at a pressure of 5t/cffl.
It was press-molded to a thickness of 0 mm and a thickness of 150 μm.

The total conductivity and decomposition voltage of the obtained pellet were evaluated in the same manner as in Example 1, and the results are listed in Table 1.

A solid electrolyte sheet with excellent processability, productivity, storage stability, flexibility, and adhesion with electrode active materials can be obtained by using a multi-component amorphous solid electrolyte with high decomposition voltage and high decomposition voltage. It becomes possible to make the solid electrolyte sheet thinner and larger in area.

The solid electrolyte sheet obtained by the present invention is particularly useful as a material for electrochemical devices such as high energy density lithium batteries and electrochromic display devices.

*1: Out of the 5 pellets produced, 4 pellets developed cracks due to heat during A u withering, and could not be measured.

*2: None of the five samples produced adhered to the platinum plate and could not be measured.

*3: Brittle <, could not be measured because it was destroyed.

〔Effect of the invention〕

Claims (1)

[Claims] (1) A mixed liquid containing a multicomponent amorphous solid electrolyte powder consisting of at least one compound selected from boron sulfide, phosphorus sulfide, and silicon sulfide, lithium iodide, and lithium sulfide, and an elastomer polymer is made into a non-conductive liquid. 1. A method for producing a solid electrolyte sheet, which comprises filling the openings of a solid electrolyte sheet and then drying the sheet.