JP2014135272A - All-solid-state battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an all-solid-state battery free of the possibility of liquid leakage of a nonaqueous electrolyte battery, having a battery container prevented from being destructed, further requiring no pressure equalizer and auxiliary machine for preventing the battery container and a power generation element from being destructed, capable of being reduced in size of a battery, and capable of achieving higher energy density.SOLUTION: The present invention relates to an all-solid-state battery including a power generation element that is housed in a flexible container, the power generation element comprising a positive electrode layer containing a positive electrode active material, a negative electrode layer containing a negative electrode active material, and a solid electrolyte layer provided between the positive electrode layer and the negative electrode layer, which are compacted by hydrostatic pressure to be joined.

Description

  The present invention relates to an all solid state battery. Specifically, the all solid state battery of the present invention relates to an all solid state battery used under high pressure such as in the deep sea.

  Conventionally, lead-acid storage batteries and silver oxide-zinc storage batteries have been used as power supply batteries used in high-pressure environments such as the deep sea. These batteries use an aqueous solution such as sulfuric acid or potassium hydroxide solution as an electrolyte, and a large amount of gas is generated due to decomposition of water during charging or discharging. When charging on the ground and discharging in the deep sea, if this gas remains in the electrode plate, the gas is compressed and contracted greatly under high pressure. For this reason, when the battery is a sealed type, a high voltage is applied to the entire battery, the battery is deformed, and finally there is a danger of being destroyed. Therefore, a battery using an aqueous electrolyte cannot have a sealed structure.

  For this reason, these deep-sea batteries are not used as a sealed type, but are used as an open-type structure in which special measures are taken so that high-pressures in the deep sea are uniformly applied to the entire components of the battery. In addition, when the aqueous electrolyte solution and seawater come into direct contact with each other, they mix with each other, reducing the electrolyte concentration and lowering the battery characteristics. The gas in the battery is discharged out of the battery through the gas-liquid separator. In general, a battery having these mechanisms is called an oil-immersed battery. The oil-immersed battery has a complicated mechanism, a large number of auxiliary devices other than the battery, and the energy density of the entire battery is low.

  On the other hand, the non-aqueous electrolyte battery does not generate gas, can be sealed, and does not require a gas-liquid separator, so the entire battery can be downsized, but it can be used under high pressure. There wasn't.

  A non-aqueous electrolyte battery has to have a sealed structure because battery performance is remarkably deteriorated due to water entering the battery. Conventionally, a sealed nonaqueous electrolyte battery used on the ground requires a gas space in order to compensate for a volume change of an active material accompanying a charge / discharge reaction and a volume change of the nonaqueous electrolyte solution due to a temperature change. This gas space is generally 3-30% of the battery internal volume.

  When such a sealed nonaqueous electrolyte battery is used under a high pressure such as 6500 m in the deep sea, for example, the pressure applied to the battery reaches 650 atm, and a difference occurs between the pressure outside the battery and the pressure inside the battery. Due to the contraction of the gas space due to the high pressure, the battery is deformed, and further, there is a problem that it cannot function as a battery due to destruction.

  Conventionally, in order to solve the problem of such a sealed nonaqueous electrolyte battery, an electrolyte storage container is provided outside the battery, and the electrolyte is injected into the battery as the pressure increases. Various techniques using an apparatus have been reported (Patent Documents 1 to 5). Such a pressure equalizing device makes it difficult to reduce the size of a deep-sea battery, and cannot take advantage of the features of a non-aqueous electrolyte battery that can be expected to have a high energy density.

JP 2001-185097 A Japanese Patent Laid-Open No. 10-247512 JP 7-335250 A JP-A-9-283177 JP-A-2-139850

  Therefore, the present invention prevents the battery container from being destroyed without worrying about leakage of the nonaqueous electrolyte battery, and further requires a pressure equalizing device and auxiliary equipment for preventing the battery container and the power generation element from being destroyed. An object of the present invention is to provide an all-solid-state battery capable of reducing the size of the battery without increasing the density and achieving a high energy density.

  In order to achieve the above object, the present invention provides a positive electrode layer containing a positive electrode active material, a negative electrode layer containing a negative electrode active material, and a solid electrolyte layer provided between the positive electrode layer and the negative electrode layer by hydrostatic pressure. It is an all-solid-state battery characterized in that the power generation elements that are compacted and joined are accommodated in a flexible container.

  That is, the present invention uses hydrostatic pressure in the manufacturing process of the electric ground, and uses a pressure higher than the battery operating pressure that exceeds the atmospheric pressure. For this reason, even if an electric ground is used in an environment with a pressure exceeding atmospheric pressure, the container having both flexibility, liquid tightness, and air tightness is bent by the working pressure and closely adheres to the power generation element. Is supported from the inside by a power generation element composed of a positive electrode layer, a negative electrode layer, and a solid electrolyte, which are joined and consolidated by the above. This prevents the battery container from being destroyed. In addition, since the working pressure transmitted to the power generation element via the battery container can be lower than the joining pressure of the power generation element, the operation of the battery is maintained without destroying the power generation element. Therefore, since a pressure equalizing device and auxiliary devices for preventing the destruction of the container and the power generation element are not required, a small, lightweight and high energy density power supply device can be provided.

  The all-solid-state battery of the present invention can be used in a high-pressure environment such as the deep sea without any risk of liquid leakage or battery destruction, and it is possible to omit a pressure equalizing device and complicated auxiliary equipment, and is small and lightweight. It is.

It is the figure along the cross-sectional direction which shows the structure of the all-solid-state battery which concerns on embodiment of this invention. It is a figure along the section direction of the all-solid-state battery container at the time of hydrostatic pressure pressurization concerning an embodiment of the present invention. It is a characteristic view which shows the ratio of the surface density when the surface density when a hydrostatic pressure is 980 Mpa is set to 100 in a positive electrode. It is a characteristic view which shows the ratio of the surface density when the surface density when a hydrostatic pressure is 980 Mpa is set to 100 in a negative electrode. It is a characteristic figure which shows the ratio of the surface density when the surface density when a hydrostatic pressure is 980 Mpa is set to 100 in a solid electrolyte.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

<Configuration of all-solid-state battery>
First, based on FIG. 1, the structure of the solid battery 1 which concerns on this embodiment is demonstrated. The solid battery 1 includes a positive electrode current collector 2, an adhesive layer 3, a positive electrode layer 4, a solid electrolyte layer 5, a negative electrode layer 6, and a negative electrode current collector 7. The adhesive layer 3 and the positive electrode layer 4 constitute the positive electrode layer 10 of the solid battery 1. Further, the negative electrode layer 6 constitutes the negative electrode 20 of the solid battery 1.

  The positive electrode current collector 2 may be any conductor as long as it is a conductor, and is made of, for example, aluminum, stainless steel, nickel-plated steel, or the like.

  The adhesive layer 3 is for binding the positive electrode current collector 2 and the positive electrode layer 4. The adhesive layer 3 includes an adhesive layer conductive material, a first binder, and a second binder. The adhesive layer conductive material is, for example, carbon black such as ketjen black, acetylene black, graphite, natural graphite, artificial graphite, etc., but is not particularly limited as long as it is for increasing the conductivity of the adhesive layer 3, It may be used alone or a plurality may be mixed.

  The first binder is, for example, a nonpolar resin having no polar functional group. Therefore, the first binder is inactive to highly reactive solid electrolytes, particularly sulfide-based solid electrolytes. It is known that sulfide-based solid electrolytes are active against polar structures such as acids, alcohols, amines, ethers and the like. The first binder is for binding to the positive electrode layer 4. Here, if the positive electrode layer 4 contains the first binder or a component similar thereto, the first binder in the adhesive layer 3 passes through the interface between the adhesive layer 3 and the positive electrode layer 4. By interdiffusion with the first binder in the positive electrode layer 4, the positive electrode layer 4 is firmly bound. Therefore, the positive electrode layer 4 preferably contains the first binder.

  Examples of the first binder include styrene thermoplastic elastomers such as SBS (styrene butadiene block polymer), SEBS (styrene ethylene butadiene styrene block polymer), styrene-styrene butadiene-styrene block polymer, SBR, and the like. (Styrene butadiene rubber), BR (Butadiene rubber), NR (Natural rubber), IR (Isoprene rubber), EPDM (Ethylene-propylene-diene terpolymer), and partial hydrides or complete hydrides thereof Is exemplified. Other examples include polystyrene, polyolefin, olefinic thermoplastic elastomer, polycycloolefin, and silicone resin.

  The second binder is a binder that has better binding properties to the positive electrode current collector 2 than the first binder. A binder having excellent binding properties to the positive electrode current collector 2 is obtained by, for example, applying a binder film obtained by applying a binder solution to the positive electrode current collector 2 and drying the positive electrode current collector 2. The force required for peeling from the electric body 2 can be determined by measuring with a commercially available peel tester. The second binder is, for example, a polar functional group-containing resin having a polar functional group, and is firmly bound to the positive electrode current collector 2 through a hydrogen bond or the like. However, since the second binder is often highly reactive with the sulfide-based solid electrolyte, it is not included in the positive electrode layer 4.

  Examples of the second binder include NBR (nitrile rubber), CR (chloroprene rubber), and partially hydrides or complete hydrides thereof, copolymers of polyacrylate esters, PVdF (polyvinylidene fluoride). Ride), VDF-HFP (Pinylidene fluoride-hexafluoropropylene copolymer), and their carboxylic acid modified products, CM (chlorinated polyethylene), polymethacrylic acid ester, polyvinyl alcohol, ethylene-vinyl alcohol copolymer Examples include coalescence, polyimide, polyamide, polyamideimide and the like. Moreover, the polymer etc. which copolymerized the monomer which has carboxylic acid, a sulfonic acid, phosphoric acid etc. in said 1st binder are illustrated.

  The content ratio of the adhesive layer conductive material, the first binder, and the second binder is not particularly limited. For example, the adhesive layer conductive material is the total mass of the adhesive layer 3. The first binder is 3 to 30% by mass with respect to the total mass of the adhesive layer 3, and the second binder is 2 to 20 with respect to the total mass of the adhesive layer 3. % By mass.

The positive electrode layer 4 is composed of a sulfide-based solid electrolyte, a positive electrode active material, and a positive electrode layer conductive material. The positive electrode layer conductive material may be the same as the adhesive layer conductive material. Examples of the sulfide-based solid electrolyte include sulfides containing Li, P, and S. More _{specifically, Li 7 P 3 S 11,} Li 3 PS 4, Li 7 PS 6 ,, Li 6 PS 5 Cl , and the like.

The sulfide-based solid electrolyte is obtained by heating Li ₂ S and P ₂ S ₅ to a melting temperature or higher, melting and mixing them at a predetermined ratio, holding them for a predetermined time, and then rapidly cooling (melting). Quenching method). Alternatively, Li ₂ S—P ₂ S ₅ can be obtained by a mechanical milling method. The mixing ratio of Li ₂ S—P ₂ S ₅ is usually 50:50 to 80:20, preferably 60:40 to 75:25 in terms of molar ratio.

Examples of the solid electrolyte include those containing a lithium ion conductor made of an inorganic compound as the inorganic solid electrolyte in addition to the sulfide-based solid electrolyte. Examples of such lithium ion conductors include Li ₃ N, LIICON, LIPON (Li _{3 + y} PO _4−x N _x ), Thio-LISICON (Li _3.25 Ge _0.25 P _0.75 S ₄ ), Li has _{2 O-Al 2 O 3 -TiO} 2 -P 2 O 5 (LATP).

  Solid electrolytes have crystal, amorphous, glassy, glass ceramic (crystallized glass) structures, among which the lithium ion conductivity of the crystallized glass structure is much better than the amorphous structure. ing.

  The positive electrode active material is not particularly limited as long as it is a material capable of reversibly occluding and releasing lithium ions. For example, lithium cobalt oxide (LCO), lithium nickelate, lithium nickel cobaltate, nickel cobalt aluminum acid Lithium (hereinafter also referred to as “NCA”), nickel cobalt lithium manganate (hereinafter also referred to as “NCM”), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, sulfur , Iron oxide, vanadium oxide and the like. These positive electrode active materials may be used independently and 2 or more types may be used together.

The positive electrode active material is preferably a lithium salt of a transition metal oxide having a layered rock salt type structure, among the examples of the positive electrode active materials listed above. “Layered” as used herein means a thin sheet-like shape, and “rock salt structure” refers to a sodium chloride structure, which is a kind of crystal structure, and includes cations and anions. Each of the face-centered cubic lattices formed by each indicates a structure that is shifted from each other by a half of the edge of the unit lattice. As a lithium salt of a transition metal oxide having such a layered rock salt structure, for example, Li _1-x-yz Ni _x Co _y Al _z O ₂ (NCA) or Li _1-x-yz Ni _x Co _y Mn _z O ₂ (NCM) (0 <x <1, 0 <y <1, 0 <z <1, and x + y + z <1) is represented by a lithium salt of a ternary transition metal oxide. Can be mentioned.

  The positive electrode layer binder is, for example, a nonpolar resin having no polar functional group. Therefore, the positive electrode layer binder is inactive to highly reactive solid electrolytes, particularly sulfide-based solid electrolytes. The positive electrode layer binder preferably includes the first binder described above. Since the electrolyte of the solid battery 1 is a highly reactive sulfide-based solid electrolyte, the positive electrode layer binder is a nonpolar resin.

  Even if the positive electrode layer 4 is directly bound to the positive electrode current collector 2, the positive electrode layer 4 may not be sufficiently bound to the positive electrode current collector 2. Therefore, the adhesive layer 3 containing the first binder and the second binder is interposed between the positive electrode layer 4 and the positive electrode current collector 2. As a result, the first binder in the adhesive layer 3 is firmly bound to the positive electrode layer 4, and the second binder in the adhesive layer 3 is firmly bound to the positive electrode current collector 2. The positive electrode current collector 2 and the positive electrode layer 4 are firmly bound. Here, when the first binder is contained in the positive electrode layer binder, the first binder in the adhesive layer 3 passes through the interface between the adhesive layer 3 and the positive electrode layer 4 and the first binder in the positive electrode layer 4. The positive electrode layer 4 and the positive electrode current collector 2 are firmly bonded by interdiffusion with the first binder.

  The ratio of the content of the sulfide-based solid electrolyte, the positive electrode active material, the positive electrode layer conductive material, and the positive electrode layer binder in the positive electrode is not particularly limited. For example, the sulfide-based solid electrolyte is 20 to 50% by mass with respect to the total mass of the positive electrode layer 4, the positive electrode active material is 45 to 75% by mass with respect to the total mass of the positive electrode layer 4, and the positive electrode layer conductive material is the positive electrode layer. 1 to 10% by mass with respect to the total mass of 4, and the positive electrode layer binder is 0.5 to 4% by mass with respect to the total mass of the positive electrode layer 4.

  The electrolyte layer 5 includes a sulfide-based solid electrolyte and an electrolyte binder. The electrolyte binder is a nonpolar resin having no polar functional group. Accordingly, the electrolyte binder is inactive to highly reactive solid electrolytes, particularly sulfide-based solid electrolytes. The electrolyte binder preferably includes a first binder.

  The first binder in the electrolyte layer 5 interdiffuses with the first binder in the positive electrode layer 4 through the interface between the positive electrode layer 4 and the electrolyte layer 5, so that the positive electrode layer 4 and the electrolyte layer 5 Is firmly bound. The ratio of the content of the sulfide-based solid electrolyte and the electrolyte binder is not particularly limited. For example, the sulfide-based solid electrolyte is 95 to 99 mass% with respect to the total mass of the electrolyte layer 5, and the electrolyte binder is 0.5 to 5 mass% with respect to the total mass of the electrolyte layer 5.

  The negative electrode layer 6 includes a negative electrode active material and a negative electrode binder. The negative electrode binder includes the first binder described above. The first binder of the negative electrode layer 6 interdiffuses with the first binder of the electrolyte layer 5 to firmly adhere the negative electrode layer 6 and the electrolyte layer 5. The binder contains a second binder having a polar functional group in addition to the first binder.

  Examples of the negative electrode active material include graphite-based active materials such as artificial graphite, natural graphite, a mixture of artificial graphite and natural graphite, and natural graphite coated with artificial graphite.

  The second binder is firmly bound to the negative electrode current collector 7 through a hydrogen bond. However, the binding property between the negative electrode layer 6 and the electrolyte layer 5 may not be sufficient with the second binder alone. Therefore, in the present embodiment, the negative electrode layer 6 includes the first binder in addition to the second binder. As a result, the first binder is firmly bound to the electrolyte layer 5. When the electrolyte layer 5 includes the first binder, the first binder in the negative electrode layer 6 is the first binder in the electrolyte layer 5 through the interface between the negative electrode layer 6 and the electrolyte layer 5. By interdiffusion, the electrolyte layer 5 can be more firmly bound. The negative electrode active material may be tin or silicon material instead of graphite.

  Note that the ratio of the content of the negative electrode active material, the first binder, and the second binder is not particularly limited. For example, the negative electrode binder is 95 to 99% by mass with respect to the total mass of the negative electrode layer 6, and the first binder is 0.5 to 5% by weight with respect to the total mass of the negative electrode layer 6, and the second binder. The agent should just contain 0.5 to 5 weight% with respect to the negative electrode layer 6 total weight.

  The negative electrode current collector 7 may be any conductive material, such as copper, stainless steel, nickel-plated steel, or the like. In addition, you may add a well-known additive etc. to said each layer suitably.

<Method for manufacturing solid battery>
Next, an example of a method for manufacturing the solid battery 1 will be described. First, a first binder, a second binder, an adhesive layer conductive material, and a first solvent for dissolving the first binder and the second binder. An adhesive layer coating solution containing is produced. Here, examples of the first solvent include amide solvents such as NMP (N-methylpyrrolidone), DMF (N, N-dimethylformamide), N, N-dimethylacetamide, and alkyls such as butyl acetate and ethyl acetate. Examples include ester solvents, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ether solvents such as tetrahydrofuran and diethyl ether, alcohol solvents such as methanol, ethanol, and isopropyl alcohol.

  Next, the adhesive layer coating liquid is applied onto the positive electrode current collector 2 and dried to produce the adhesive layer 3. In addition, an adhesive layer coating solution may be applied to a substrate such as a desktop screen printing machine and dried to form an adhesive film, and the adhesive film may be pressure-bonded to the positive electrode current collector 2.

  Next, a positive electrode layer coating solution containing a sulfide-based solid electrolyte, a positive electrode active material, a positive electrode layer conductive material, and a second solvent for dissolving the positive electrode layer binder is generated. The second solvent dissolves the positive electrode layer binder (first binder) but does not dissolve the second binder. The second solvent is specifically a nonpolar solvent, and examples thereof include aromatic hydrocarbons such as xylene, toluene, and ethylbenzene, and aliphatic hydrocarbons such as pentane, hexane, and heptane. Next, the positive electrode layer coating liquid is applied onto the adhesive layer 3 and dried to produce the positive electrode layer 4. Thereby, since the 1st binder in the contact bonding layer 3 melt | dissolves in the positive electrode layer 4 by melt | dissolving in a 2nd solvent, the binding | bonding of the contact bonding layer 3 and the positive electrode layer 4 becomes stronger. Thus, in this embodiment, since the positive electrode 10 is produced | generated by coating, the large area positive electrode 10 can be manufactured easily. That is, in this embodiment, the large-capacity solid battery 1 can be easily manufactured.

  In addition, since the second solvent does not dissolve the second binder, when the positive electrode layer coating solution is applied onto the adhesive layer 3, the second binder in the adhesive layer 3 becomes the positive electrode layer 4. Swelling inside is prevented. This prevents the sulfide solid electrolyte in the positive electrode layer 4 from being deteriorated by the second binder. Through the above steps, a positive electrode structure including the positive electrode current collector 2, the adhesive layer 3, and the positive electrode layer 4 is generated.

  On the other hand, a negative electrode layer coating liquid containing a first binder, a second binder, a negative electrode active material, and a first solvent is generated. Since the negative electrode layer 6 does not require a sulfide-based solid electrolyte, a polar solvent can be used as the first solvent. Next, the negative electrode layer coating liquid is applied onto the negative electrode current collector 7 and dried to produce the negative electrode layer 6. Thereby, a negative electrode structure is produced.

  Next, an electrolyte layer coating solution containing a sulfide-based solid electrolyte, an electrolyte binder, and a second solvent is generated. The second solvent dissolves the electrolyte binder (first binder), but does not dissolve the second binder. Next, the electrolyte layer coating liquid is applied onto the negative electrode layer 6 and dried to produce the electrolyte layer 5. Thereby, since the 1st binder in the negative electrode layer 6 is dissolved in the electrolyte layer 5 by melt | dissolving in a 2nd solvent, the binding with the electrolyte layer 5 and the negative electrode layer 6 becomes firmer.

  Subsequently, the solid battery 1 is produced | generated by crimping | bonding the positive electrode structure and the sheet | seat which consists of the electrolyte layer 5 and a negative electrode structure by a hydrostatic pressure.

<Hydrostatic press>
As shown in FIG. 2, the sheets obtained by the above-described steps were stacked, put into an aluminum laminate film 30, degassed with a vacuum machine, and then heat-sealed and packed. The code | symbol 32 of FIG. 2 shows a heat seal part. Thereafter, this was placed on a support plate, and a vacuum laminate pack including the support plate was performed. Next, it was pressed for a predetermined time at 3 MPa to 120 MPa using an isostatic press. Thereafter, in order to perform a water pressure resistance test of the battery, it was put into a container, deaerated and sealed, and a hydrostatic pressure of 2 MPa to 111 MPa corresponding to a deep sea environment of 200 to 10911 m was applied using a hydrostatic pressure press. An aluminum laminate film is the battery container having flexibility, liquid tightness, and air tightness of the present invention. As another battery container, there is a welder made of a sealable thin film such as a stainless laminate film.

<Example>
Next, examples of the present embodiment will be described. In addition, all the operations in the following Examples and Comparative Examples were performed in a dry room having a dew point temperature of −55 ° C. or lower.
[Example 1]
[Generation of adhesive layer]
Adhesive layer conductive material graphite (Timcal KS-4, the same applies hereinafter) and acetylene black (electrochemical industry, the same applies hereinafter), and styrene thermoplastic elastomer as the first binder (hereinafter referred to as the binder) A) (Asahi Kasei S.E.E 1611, the same shall apply hereinafter) and acid-modified PVdF (hereinafter referred to as Binder B) (Kureha KF 9200, same shall apply hereinafter) as the second binder 60: 10: 15: 15 Weighed at a mass% ratio. Then, these materials and an appropriate amount of NMP were put into a planetary mixer and stirred at 3000 rpm for 5 minutes to prepare an adhesive layer coating solution.

  Next, an aluminum foil current collector having a thickness of 20 μm is placed as a positive electrode current collector 2 on a desktop screen printing machine (manufactured by Neurong Seimitsu Kogyo Co., Ltd., the same shall apply hereinafter), and an adhesive layer coating solution is used using a 400 mesh screen. Was coated on an aluminum foil current collector. Thereafter, the positive electrode current collector 2 coated with the adhesive layer coating solution was vacuum-dried at 80 ° C. for 12 hours. Thereby, the adhesive layer 3 was formed on the positive electrode current collector 2. The thickness of the adhesive layer 3 after drying was 7 μm.

[Creation of positive electrode layer]
LiNiCoAlO ₂ ternary powder as a positive electrode active material and Li ₂ S—P ₂ S ₅ (80:20 mol%) as a sulfide-based solid electrolyte were subjected to mechanical milling (MM treatment) at 200 rpm for 30 minutes. The amorphous solid electrolyte powder obtained above and the vapor-grown carbon fiber powder as the positive electrode layer conductive material (conducting aid) are weighed in a mass ratio of 60: 35: 5, and a planetary mixer is used. And mixed.

  Next, a xylene solution in which the binder A as the positive electrode layer binder is dissolved is added to the mixed powder so that the binder A is 1.0% by mass with respect to the total mass of the mixed powder. A primary mixed solution was prepared. Furthermore, a secondary mixed solution was generated by adding an appropriate amount of dehydrated xylene for viscosity adjustment to the primary mixed solution. Furthermore, in order to improve the dispersibility of the mixed powder, a zirconia ball having a diameter of 5 mm is changed into a secondary mixed solution so that the space, the mixed powder, and the zirconia ball each occupy 1/3 of the total volume of the kneading container. I put it in. The tertiary mixture produced in this way was put into a planetary mixer and stirred at 3000 rpm for 3 minutes to produce a positive electrode layer coating solution.

  Subsequently, the sheet | seat which consists of the positive electrode electrical power collector 2 and the contact bonding layer 3 was mounted in the desk screen printer, and the positive electrode layer coating liquid was applied on the sheet | seat using a 150 micrometer metal mask. Then, after drying the sheet | seat with which the positive electrode layer coating liquid was coated with a 40 degreeC hotplate for 10 minutes, it was vacuum-dried at 40 degreeC for 12 hours. Thereby, the positive electrode layer 4 was formed on the adhesive layer 3. The total thickness of the positive electrode current collector 2, the adhesive layer 3, and the positive electrode layer 4 after drying was around 165 μm.

[Formation of negative electrode layer]
A graphite powder as a negative electrode active material (vacuum dried at 80 ° C. for 24 hours), a binder A as a first binder, and a binder B as a second binder; Weighed at a mass ratio of 5: 0.5: 3.0. Then, these materials and an appropriate amount of NMP were put into a rotation and revolution mixer, stirred at 3000 rpm for 3 minutes, and then defoamed for 1 minute to prepare a negative electrode layer coating solution.

  Next, a 16 μm-thick copper foil current collector was prepared as the negative electrode current collector 7, and the negative electrode layer coating solution was applied onto the copper foil current collector using a blade. The thickness (gap) of the negative electrode layer coating solution on the copper foil current collector was around 150 μm.

  The sheet coated with the negative electrode layer coating solution was stored in a dryer heated to 80 ° C. and dried for 20 minutes. Then, the sheet | seat which consists of the negative electrode electrical power collector 7 and the negative electrode layer 6 was rolled using the roll press machine with a roll gap of 10 micrometers, and the negative electrode structure was produced | generated. The thickness of the negative electrode structure was about 100 μm. Further, the rolled sheet was subjected to vacuum heating at 100 ° C. for 12 hours.

[Creation of electrolyte layer]
Li ₂ S—P ₂ S ₅ (80:20 mol%) amorphous powder as a sulfide-based solid electrolyte, xylene solution of binder A (electrolyte binder) + binder A is amorphous The primary mixed liquid was adjusted by adding so as to be 1% by mass with respect to the mass of the fine powder. Furthermore, a secondary mixed solution was generated by adding an appropriate amount of dehydrated xylene for viscosity adjustment to the primary mixed solution. Furthermore, in order to improve the dispersibility of the mixed powder, a zirconia ball having a diameter of 5 mm is changed into a secondary mixed solution so that the space, the mixed powder, and the zirconia ball each occupy 1/3 of the total volume of the kneading container. I put it in. The tertiary mixture produced in this manner was put into a planetary mixer and stirred at 3000 rpm for 3 minutes to prepare an electrolyte layer coating solution.

  Next, the negative electrode structure was placed on a desktop screen printer, and an electrolyte layer coating solution was applied onto the negative electrode structure using a 200 μm metal mask. Thereafter, the sheet coated with the electrolyte layer coating solution was dried on a hot plate at 40 ° C. for 10 minutes and then vacuum dried at 40 ° C. for 12 hours. Thereby, the electrolyte layer 5 was formed on the negative electrode structure. The thickness of the electrolyte layer 5 after drying was around 130 μm.

[Production of solid battery]
The sheet consisting of the negative electrode structure and the electrolyte layer 5 and the positive electrode structure are respectively punched with a Thomson blade, and the electrolyte layer 5 of the sheet and the positive electrode layer 4 of the positive electrode structure are put on an aluminum laminate film and deaerated with a vacuum machine After that, it was heat sealed and packed. Then, using an isostatic press, the pressure was bonded at 3 MPa (corresponding to a water pressure of a water depth of 300 m), 60 MPa (corresponding to a water pressure of a water depth of 6000 m), 120 MPa (corresponding to a water pressure of a water depth of 12,000 m) for 10 minutes, A single cell (single cell) of the solid battery 1 was produced, and each was used as a single cell for Example 1, Example 2, and Example 3. Moreover, as a comparative example 1, after punching with the Thomson blade as described above, the sheet electrolyte layer 5 and the positive electrode layer 4 of the positive electrode structure are separated by a dry lamination method using a roll press machine (1 MPa pressure) with a roll gap of 50 μm. A unit cell of the solid battery 1 was prepared.

  Subsequently, the battery obtained above was housed and sealed in the battery case of FIG. 2, and then the hydrostatic pressure was 2 MPa (corresponding to a water pressure of a water depth of 200 m), 50 MPa (corresponding to a water pressure of a water depth of 5000 m), 111 MPa (the world's best). Table 1 shows the results of observing the appearance of the unit cell after opening the battery container after pressurizing again for 10 minutes with a water pressure of 10911 m (corresponding to the water pressure of the Mariana Trench).

  As can be seen from Table 1, it was found that the higher the applied pressure at the time of molding the unit cell, the greater the water pressure withstands the pressure corresponding to the deep water pressure.

  Next, the relationship between hydrostatic pressure and surface density was examined. The hydrostatic pressure was changed in the range of 49 MPa to 980 MPa, and the surface density of the positive electrode, negative electrode, and solid electrolyte after pressurization was measured. The areal density was measured from weight and thickness by punching each with φ10 mm. The measurement results are shown in FIGS. FIG. 3 shows the ratio of the surface density when the surface density is 100 when the hydrostatic pressure is 980 MPa in the positive electrode, and FIG. 4 shows the surface density when the surface density is 100 when the hydrostatic pressure is 980 MPa in the negative electrode. FIG. 5 shows the ratio of the surface density when the surface density is 100 when the hydrostatic pressure is 980 MPa in the solid electrolyte. From the results of FIGS. 3-5, as explained in the above-described embodiment, the hydrostatic pressure is approximately 100 MpPa or more and the surface density ratio of the positive electrode or the like is 90% or more. It is possible to provide a solid state battery that can be expected to have electric ground performance.

Next, the capacity retention rate after 10 cycles and the impedance (Ω) after 10 cycles were measured for the solid batteries respectively pressed at the hydrostatic pressure of FIG. 3-5. In the former, charging / discharging was performed between 4 V and 2.5 V with a current density of 0.5 mA / cm ^{2 in} a high temperature bath at 25 ° C. The discharge capacity at the 10th cycle was determined as a percentage with the discharge capacity at the 1st cycle as 100%. In the latter, charging / discharging was performed between 4 V and 2.5 V with a current density of 0.5 mA / cm ^{2 in} a high-temperature bath at 25 ° C., and measurement was performed in a charged state at the 10th cycle. The measurement results for each of the solid state batteries pressed at the hydrostatic pressure in FIG. 3-5 are as shown in Table 2 below. From this result, it was found that a solid battery pressed at a hydrostatic pressure of 294 MPa or more (preferably a solid battery pressed at a hydrostatic pressure of 100 MPa or more) has excellent cycle characteristics and low resistance.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes and modifications within the scope of the technical idea described in the claims. Of course, these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Solid battery 2 Positive electrode collector 3 Adhesive layer 4 Positive electrode layer 5 Electrolyte layer 6 Negative electrode layer 7 Negative electrode collector

Claims (4)

  A power generation element in which a positive electrode layer containing a positive electrode active material, a negative electrode layer containing a negative electrode active material, and a solid electrolyte layer provided between the positive electrode layer and the negative electrode layer are consolidated by hydrostatic pressure and joined is flexible. All-solid-state battery characterized by being housed in a conductive container.   The all-solid-state battery according to claim 1, wherein the hydrostatic pressure is higher than an operating pressure environment.   The all-solid-state battery of Claim 1 or 2 with which the use pressure environment of the said battery exceeds atmospheric pressure.   The all-solid-state battery according to any one of claims 1 to 3, wherein the hydrostatic pressure is 100 MPa or more.