JPH0576138B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a solid electrolyte battery, and more particularly to a solid electrolyte battery having a flexible multilayer structure that is easy to manufacture. [Conventional technology] Recent technological advances in the electronics industry have been remarkable.
Electronic components such as ICs and LSIs are widely used in all fields, but even in the field of battery technology, efforts are being made to make them smaller and thinner, and they are now being used as power supplies for card-type calculators, cameras, wristwatches, etc. Used in large quantities. 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 technology to seal the battery, and currently the mainstream sealing technology uses crimp seals via gaskets, but the thinner the battery, the more difficult it is to use the sealing material. This increases the proportion of the battery's volume in the battery, making it difficult to provide the required battery capacity, and there is a limit to how thin the battery can be made. Batteries using lithium-based solid electrolytes have recently become commercially available, but since active metal lithium is used as the negative electrode active material, more reliable battery sealing technology than liquid electrolyte batteries is required. At present, it is difficult to make the device thinner. Under these circumstances, solid electrolyte materials with high ionic conductivity are being used to make batteries smaller and thinner, but when manufacturing batteries using these electrolyte materials, electrode materials are also required. It also needs to be easy to handle and have excellent workability and productivity during battery assembly. Regarding solid electrolyte materials, attempts have been made to apply polymer electrolytes, and a typical example of the conventional material is poly(oligoxyethylene methacrylate)-alkali metal salt system. However, even the best ionic conductivity is 10 ^-5 at room temperature.
s/cm, and the selectivity of moving ions is poor, causing problems such as the movement of not only cations (e.g. Li ⁺ ) but also anions (e.g. ClO ₄ ^- ).
It has not reached the practical stage. Furthermore, when making a battery using this type of material, it is necessary to use the metal lithium as the negative electrode active material, and it is difficult to obtain significant benefits in terms of processability, productivity, etc. during battery assembly. More recently, attempts have been made to utilize lithium ion conductive solid electrolytes, proton conductive solid electrolytes, silver ion conductive solid electrolytes, or copper ion conductive solid electrolytes that have high ionic conductivity. A typical lithium ion conductive solid electrolyte is 0.4LiSiO ₄ −0.6Li ₃ VO ₄ , and a typical proton conductive solid electrolyte is H ₃ Mo ₁₂ PO ₄₀ .
29H ₂ O, H ₃ W ₁₂ PO ₄₀・29H ₂ O, RbAg 4 I 5 is a typical silver ion conductive solid electrolyte, and RbAg ₄ I ₅ is a typical copper ion conductive solid electrolyte.
There is RbCu ₄ I _1.5 Cl _3.5 . However, since these solid electrolytes and electrode active materials are inorganic solid powders, it is necessary to pelletize them using a high-pressure press during production, which is a major obstacle in achieving productivity, uniformity, etc. Furthermore, the resulting pellets are hard and brittle, so there is a limit to how thin they can be made, and it is difficult to obtain pellets with a large area. Furthermore, when manufacturing a battery, it is necessary to bring the solid electrolyte and electrode active material into close contact with each other using a large pressure during the bonding operation with the electrode active material, which causes problems with variations in workability, adhesion, and the like. Furthermore, when attempting to bond over a large area, there is a problem that uniform adhesion cannot be obtained and the solid electrolyte may be destroyed. [Problems to be Solved by the Invention] An object of the present invention is to solve the problems of the prior art as described above, to achieve thinning, etc., and to facilitate the handling of electrode materials, which facilitates processing during battery assembly. The object of the present invention is to provide a solid electrolyte battery with excellent performance and productivity. [Means for Solving the Problems] The solid electrolyte battery of the present invention uses ionically conductive inorganic solid electrolyte powder (hereinafter simply referred to as "solid electrolyte powder").
) is dispersed in an insulating polymeric elastomer at a volume fraction of 55 to 95%.
Laminated between a negative electrode sheet and a positive electrode sheet in which a mixture of electrode active material powder and inorganic solid electrolyte powder is contained and dispersed in an insulating polymeric elastomer at a volume fraction of 75 to 95%. , characterized in that an extraction electrode is laminated on the electrode sheet. In the present invention, the electrode sheet is laminated in the order of the mixing ratio by changing the mixing ratio of the electrode active material powder and the solid electrolyte powder in stages, and when combined with the electrolyte sheet, the mixing ratio of the electrode active material powder and the solid electrolyte powder is changed in stages. It is preferable to integrally mold the electrode sheet with the extraction electrode so that a large proportion of the electrode sheet is in contact with the electrolyte sheet. The solid electrolyte battery of the present invention basically consists of an electrolyte sheet (hereinafter referred to as SE sheet), an electrode sheet, and an extraction electrode.
Positive electrode sheet, SE sheet, negative electrode sheet,
It is obtained by stacking the extraction electrodes in this order (the order of stacking may be reversed) and molding them together. The method of integral molding is not particularly limited, but for example, a method of heating and pressurizing at a temperature of about 100 to 150° C. for several tens of seconds to about 10 minutes under an inert gas is mentioned. After heating and pressurizing, heat treatment may be performed for about 1 to 3 hours under an inert gas to make the adhesion uniform. The solid electrolyte battery thus obtained is easy to manufacture, flexible, thin, and
Large areas can also be obtained. The solid electrolyte battery is put to practical use by simpler sealing techniques, such as resin sealing with epoxy resin or the like, or lamination sealing with polyethylene film, polypropylene film, or the like. The solid electrolyte powder of the SE sheet used in the present invention includes, for example, RbCu ₄ I _2-x Cl _3+x (x is 0.2 to 0.6),
Examples include MAg ₄ I ₅ (M is Rb or K),
RbCu ₄ I _1.5 due to its excellent ionic conductivity
Cl _3.5 is most preferred. The volume fraction of solid electrolyte powder in the SE sheet needs to be 55 to 95%. If the volume fraction of solid electrolyte powder is less than 55%,
The conductivity is less than 1×10 ^-6 s/cm, making it unsuitable for practical use. Further, if the volume fraction exceeds 95%, the sheet becomes brittle and cannot maintain its shape when formed into a sheet. Examples of the electrode active material powder of the electrode sheet used in the present invention include CuxTiS ₂ , CuxZrS ₂ ,
AgxTiS ₂ , AgxZrS ₂ , LixWO ₃ , LixTiS ₂ ,
Powders such as WO ₃ , V ₂ O ₅ and HWO ₅ are used, but
It is preferable that x is about 0.05 to 0.20 from the viewpoint of charge/discharge characteristics. Furthermore, metal powders such as Cu and Ag are used, but in order to prevent overdischarge, Cu ₂ S powder is used when Cu powder is used, and Ag ₂ S powder is used when Ag powder is used. respectively Cu (or
Ag): Cu ₂ S (or Ag ₂ S) = 8:2 to 6.5:4.5
It is preferable to add at a ratio of (weight ratio). Moreover, the ratio of electrode active material powder/solid electrolyte powder in the electrode sheet is preferably 1/4 to 5/4 (weight ratio). The reason why the solid electrolyte powder is added to the electrode active material powder is to reduce the interfacial resistance between the electrode and the electrolyte and to facilitate charge transfer at the interface. The volume fraction of the solid electrolyte powder and the electrode active material powder in the electrode sheet needs to be 75 to 95%. If the volume fraction is less than 75%, the contact efficiency with the solid electrolyte powder in the SE sheet will decrease, making it impossible to obtain sufficient battery characteristics, and if the volume fraction exceeds 95%, the sheet will become brittle when formed into a sheet. It will no longer be able to maintain its shape. The shape and particle size of the solid electrolyte powder and electrode active material powder used in the present invention are not particularly limited, but from the viewpoint of ease of mixing with the insulating polymer elastomer, etc. (Tyler standard sieve) is preferred. 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, and silicone rubber. ,
Styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-
Butylene-styrene copolymer (SEBS), butyl rubber, phosphazene rubber, polyethylene, polypropylene, polyethylene oxide, polypropylene oxide, polystyrene, vinyl chloride, ethylene-ethyl acetate copolymer, 1,2-polybutadiene, polymethyl methacrylate, and these Examples include mixtures, but from the viewpoint of good adhesion between the sheets and good adhesion with the lead-out electrode, thermoplastic materials are preferable, and from the viewpoint of obtaining further flexibility, materials with ASTM A hardness are preferred. 95 or less is preferable. 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. The method of uniformly dispersing solid electrolyte powder, electrode active material powder, etc. in an insulating polymer elastomer and forming a sheet is as follows.
Although not particularly limited, for example, a method of kneading an insulating polymer elastomer, solid electrolyte powder, electrode active material powder, etc. in a Banbury mixer, and rolling the resulting mixture into a sheet. , a polymer solution in which an insulating polymer elastomer is dissolved in a specific solvent, solid electrolyte powder, electrode active material powder, etc. are kneaded in a ball mill, etc., and the resulting mixture is rolled with an applicator bar, etc., and the solvent is dried. Examples include a method of obtaining a sheet by doing so. In particular, the latter method
It is easy to obtain a thin film with a uniform thickness of 100 μm or less, there is little heat generation during kneading, and deterioration and decomposition of the solid electrolyte powder is difficult to occur.Furthermore, there is almost no contact with the atmosphere during kneading, and the solid electrolyte powder is free from moisture and oxygen. It is preferable as a manufacturing method because it is difficult to cause deterioration and decomposition due to etc., and there is no need to particularly adjust the surrounding humidity, oxygen, etc. conditions. In this case, use a non-water-absorbing solvent that does not react with the solid electrolyte powder, such as n-hexane, n-heptane, n-octane, cyclohexane, benzene, toluene, xylene, ethyl acetate, trichlene, etc. is preferable, and in this case, the insulating polymer elastomer is a 1,4-
polybutadiene, natural rubber, polyisoprene,
SBR, NBR, SBS, SIS, SEBS, butyl rubber,
The use of phosphazene rubber, polyethylene oxide, polystyrene, 1,2-polybutadiene, etc. is preferred. The solid electrolyte powder or insulating polymer elastomer contained in the SE sheet and the electrode sheet may be common or different, but the homogeneity of the molded body,
It is preferable to use a common material between the SE sheet and the electrode sheet from the viewpoint of adhesion between the SE sheet and the electrode sheet. Also, the above
The thickness of SE sheet and electrode sheet is 10~
250 μm and 20-250 μm are preferred. The material of the extraction electrode used in the present invention is not particularly limited, but from the viewpoint of adhesion with the electrode sheet, a thin silver plate is suitable for a copper-based electrode sheet, but a thin copper plate with nickel plating is preferable. Alternatively, it may be plated with gold or an alloy such as phosphor bronze. In the present invention, the electrode sheet gradually changes the mixing ratio of solid electrolyte powder and electrode active material powder from the surface in contact with the SE sheet, and the ratio of solid electrolyte powder is large on the surface in contact with the SE sheet, which approaches the extraction electrode. Accordingly, it is preferable to form a multilayered electrode sheet in which a plurality of sheets are laminated in order of mixing ratio so that the ratio of solid electrolyte powder becomes small. The degree of multilayering of the electrode sheet in this case is not particularly limited, and even two layers can have an effect, but preferably three to nine layers. However, from the viewpoint of avoiding complicated processing and thickening, it is appropriate to have 3 to 6 layers. By multilayering the electrode sheet in this manner, it is possible to reduce the interfacial resistance between the electrode and the electrolyte and increase the current capacity. [Example] The present invention will be described below with reference to Examples, but the present invention is not limited thereto. (Example 1) 1 part (parts by weight, same hereinafter) of styrene-butadiene-styrene block copolymer (specific gravity: 0.96, manufactured by Japan Synthetic Rubber Co., Ltd., TR-2000) as an insulating polymeric elastomer was dissolved in toluene. A polymer solution was obtained, and 4.2 parts of RbCu ₄ with a particle size of 200 mesh or less was added to this.
A solid electrolyte powder (specific gravity: 4.5) consisting of I _1.5 Cl _3.5 was added and kneaded in a ball mill for 2 hours, the resulting mixture was spread on a Teflon sheet with an applicator bar, and the toluene was evaporated in dry air.
An SE sheet with a volume fraction of 90% and a thickness of 20 μm was obtained. Then Cu powder, Cu ₂ S powder and RbCu ₄ I _1.5
Solid electrolyte powder consisting of Cl _3.5 in weight ratio Cu:Cu ₂
S:RbCu ₄ I _1.5 Cl _3.5 = 2.9:2.7:1 ratio was mixed, press-molded into pellets, vacuum sealed in a glass tube and heated at 200℃ for 17 hours, and the pellets were made into powder of 200 mesh or less. The powder was pulverized to obtain a powder for negative electrode. This negative electrode powder and the styrene-butadiene-styrene block copolymer are kneaded and molded in the same manner as in the SE sheet production,
A negative electrode sheet with a volume fraction of 90% and a thickness of 45 μm was obtained. In addition, the molar ratio of Cu powder and TiS ₂ powder is
The mixture was mixed at a ratio of 0.15:1, press-molded into pellets, vacuum sealed in a quartz tube, heated at 550°C for 72 hours, and the resulting Cu _0.15 TiS ₂ pellets were crushed to a size of 200 meshes or less. This powder and RbCu ₄ I _1.5
Solid electrolyte powder consisting of Cl _3.5 was mixed at a weight ratio of 1:1 to obtain a positive electrode powder. This positive electrode powder and the above styrene-butadiene-styrene copolymer are kneaded in the same manner as in the case of preparing the SE sheet,
A negative electrode sheet having a volume fraction of 90% and a thickness of 45 μm was obtained by molding. The obtained positive electrode sheet, SE sheet, and negative electrode sheet were laminated in order, and a copper thin plate was used as the extraction electrode.
A battery was created by press molding at 130°C and sealing the periphery with epoxy resin. FIG. 1 shows a cross-sectional view of the obtained battery. In the figure, 1 is an SE sheet, 2 is a positive electrode sheet, 3 is a negative electrode sheet, 4 and 5 are extraction electrodes, and 6 is a sealing material. Table 1 shows the test results for the thickness, total conductivity, self-discharge characteristics, charge/discharge cycle, and low-temperature characteristics of the obtained battery. In addition, the above-mentioned total conductivity (s/cm) is AC 1KHz.
The impedance was evaluated using an LCR meter (YHP4274A, manufactured by Yokogawa Heuretsu Pats Card Co., Ltd.), and was determined from the DC component. The self-discharge characteristics were determined from the change in battery voltage during a charge/discharge cycle of 4 mAh/cc (discharged for 2 hours, charged for 1 hour). The charge/discharge cycle is a charge/discharge cycle of 2.5 mAh/cc, and is expressed as the number of cycles at which the discharge voltage becomes 0.35 volt or less. Low-temperature characteristics were shown as charge-discharge characteristics at -10°C. (Example 2) SE sheet (volume fraction
90% and thickness 20 μm). As a negative electrode sheet (volume fraction 90%), solid electrolyte powder consisting of Cu powder, Cu ₂ S powder, and RbCu ₄ I _1.5 Cl _3.5 was used at a weight ratio of Cu:Cu ₂ S:RbCu ₄ I _1.5 Cl _3.5 = 3. :
2:3 (negative electrode sheet 1; thickness 20 μm), 3:2:2
(Negative electrode sheet 2; thickness 30μm) and 3:2:1
(Negative electrode sheet 3; thickness 30 μm) were prepared in the same manner as in Example 1. Also, as a positive electrode sheet (volume fraction 90%),
The weight ratio of solid electrolyte powder consisting of Cu _0.15 TiS ₂ powder and RbCu ₄ I _1.5 Cl _3.5 is Cu _0.15 TiS ₂ :RbCu ₄ I _1.5 Cl _3.5 =
Mixtures at a ratio of 1:3 (positive electrode sheet 1; thickness 20 μm), 1:2 (positive electrode sheet 2; thickness 30 μm), and 1:1 (positive electrode sheet 3; thickness 20 μm) were prepared in the same manner as in Example 1, respectively. Created with. The obtained sheets were divided into positive electrode sheet 3 / positive electrode sheet 2 / positive electrode sheet 1 / SE sheet / negative electrode sheet 1 /
A battery was produced in the same manner as in Example 1 by laminating negative electrode sheet 2/negative electrode sheet 3 in this order and using a thin copper plate as the lead electrode. FIG. 2 shows a cross-sectional view of the obtained battery. In the figure, 2a is a positive electrode sheet 1, 2b is a positive electrode sheet 2, 2c is a positive electrode sheet 3, 3a is a negative electrode sheet 1, 3b is a negative electrode sheet 2, and 3c is a negative electrode sheet 3. The test results of the obtained battery are shown in Table 1 in the same manner as in Example 1.

【table】

〔Effect of the invention〕

According to the present invention, it is possible to reduce the thickness of a solid electrolyte battery, provide flexibility to the battery, and increase the area of the battery. Furthermore, it has excellent workability and productivity during battery assembly.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a solid electrolyte battery according to Example 1 of the present invention, and FIG. 2 is a cross-sectional view of a solid electrolyte battery according to Example 2 of the present invention. 1... Electrolyte sheet, 2... Positive electrode sheet, 2a
...Positive electrode sheets 1, 2b...Positive electrode sheets 2, 2c
...Positive electrode sheet 3, 3...Negative electrode sheet, 3a...
Negative electrode sheets 1, 3b... Negative electrode sheets 2, 3c...
Negative electrode sheets 3, 4 and 5... Extraction electrode, 6
... Sealing material.

Claims (1)

[Scope of Claims] 1. An electrolyte sheet containing and dispersing ion-conducting inorganic solid electrolyte powder in an insulating polymeric elastomer at a volume fraction of 55 to 95%, an electrode active material powder and an inorganic solid electrolyte. A mixture with powder is contained and dispersed in an insulating polymer elastomer at a volume fraction of 75 to 95% and is laminated between a negative electrode sheet and a positive electrode sheet, and an extraction electrode is attached to the electrode sheet. A solid electrolyte battery characterized by being laminated. 2. The electrode sheet is a stack of multiple sheets in which the mixing ratio of the electrode active material powder and the inorganic solid electrolyte powder is changed in stages, and the mixing ratio of the inorganic solid electrolyte powder in the electrode sheet is stacked in the order of the mixing ratio. 2. The solid electrolyte battery according to claim 1, wherein the large surface of the solid electrolyte battery is in contact with the electrolyte sheet.