JP2008103259A - Solid electrolyte sheet, electrode sheet, and all-solid secondary battery using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte sheet and an electrode sheet having a large area in which ion conductivity is hardly reduced even if a support is introduced for making a sheet self-supported. <P>SOLUTION: The solid electrolyte sheet includes a support having a solid electrolyte and a plurality of openings, in which the solid electrolyte has a continuous through-structure in the thickness direction in the openings of the support, and in which the support is composed of a photo-sensitive resin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid electrolyte sheet, an electrode sheet, and an all-solid secondary battery comprising the same. More specifically, the present invention relates to a solid electrolyte sheet and an electrode sheet including a support made of a photosensitive resin.

In recent years, demand for secondary batteries such as high-capacity and high-performance lithium batteries used in personal digital assistants, portable electronic devices, small household power storage devices, motor-driven motorcycles, electric vehicles, hybrid electric vehicles, etc. Has increased.
As the applications used expand, further improvements in safety and higher performance of secondary batteries are required.

  In order to ensure the safety of the lithium battery, it is effective to use an inorganic solid electrolyte instead of the organic solvent electrolyte. This is because inorganic solid electrolytes are nonflammable in nature and are safer than commonly used organic solvent electrolytes. Development of an all-solid lithium battery having high safety using such an electrolyte is desired.

Inorganic solid electrolytes used in all solid lithium batteries are usually in the form of powder. Therefore, for the convenience of handling, a sheet-like solid state is required. However, it has been difficult to form a single-layer thin film sheet composed only of a powdered solid electrolyte.
On the other hand, since the Li ion conductivity in the electrolyte when the battery is configured depends on the thickness of the electrolyte layer, it is desired to reduce the thickness of the solid electrolyte layer.

  With respect to such a problem, Patent Document 1 discloses a solid electrolyte sheet obtained by mixing a lithium ion conductive solid electrolyte and a thermoplastic polymer resin in a dry manner and rolling under heating. However, since the thermoplastic polymer resin is mixed as a support for the solid electrolyte during the production of the sheet, there is a problem that the ion conduction path of the solid electrolyte is cut by the polymer chain and the ionic conductivity is lowered. In addition, the thermoplastic polymer resin as a support floats on the surface of the sheet, and the sheet sometimes exhibits insulating properties.

  Patent Document 2 discloses a solid electrolyte sheet obtained by applying a solid electrolyte ink to a nonwoven fabric by spraying. However, since the ion conduction path of the solid electrolyte is cut by the polymer chain constituting the nonwoven fabric, a decrease in ionic conductivity is inevitable.

Non-Patent Document 1 discloses a solid electrolyte sheet with mesh by applying a solid electrolyte slurry to a PET (polyethylene terephthalate) mesh (thickness 100 μm, opening ratio 70%) and pressurizing while drying the solvent. ing.
JP-A-4-133209 Japanese Patent Laid-Open No. 1-115069 New Energy Industrial Technology Development Organization 2001 Results Report ("Development of New Inorganic Electrolytes for All Solid Lithium Batteries with Improved Stability")

An object of the present invention is to provide a solid electrolyte sheet and an electrode sheet having a large area with little decrease in ionic conductivity even when a support is introduced for sheet self-supporting.
Another object of the present invention is to provide a solid electrolyte sheet and an electrode sheet that are easy to manufacture and can be applied to continuous processes and mass production.

According to the present invention, the following solid electrolyte sheet, electrode sheet, and all-solid secondary battery are provided.
1. A solid electrolyte sheet comprising a solid electrolyte and a support having a plurality of openings, wherein the solid electrolyte has a continuous through structure in the thickness direction at the openings of the support, and the support is made of a photosensitive resin.
2. A solid electrolyte sheet comprising an electrode material and a support having a plurality of openings, wherein the electrode material has a continuous through structure in the thickness direction at the openings of the support, and the support is made of a photosensitive resin.
An all-solid secondary battery comprising at least one of the solid electrolyte sheet according to 3.1 and the electrode sheet according to 2.

ADVANTAGE OF THE INVENTION According to this invention, the self-supporting solid electrolyte sheet and electrode sheet which have a large area can be provided. In addition, since the solid electrolyte itself has a continuous self-supporting structure, the ionic conductivity hardly deteriorates even when a support is introduced for sheet self-supporting.
According to the present invention, it is possible to provide a solid electrolyte sheet and an electrode sheet that are easy to manufacture and can be applied to a continuous process and mass production.

The solid electrolyte sheet of the present invention includes a solid electrolyte and a support. The support is made of a photosensitive resin and has a plurality of openings. The opening ratio of the support is preferably 40 to 90%, more preferably 70 to 90%, and particularly preferably 80 to 90%. The solid electrolyte has a continuous through structure in the thickness direction of the sheet through the plurality of openings of the support.
Fig.1 (a) is a schematic top view which shows one Embodiment of the support body used for the solid electrolyte sheet which concerns on this invention.
The support shown in FIG. 1 (a) is a porous sheet 10 made of a photosensitive resin having a plurality of through holes.

FIG.1 (b) is a schematic sectional drawing of the solid electrolyte sheet 1 using the porous sheet 10 shown by Fig.1 (a).
The solid electrolyte sheet 1 includes a porous sheet 10 and a solid electrolyte 20, and the solid electrolyte 20 fills a gap created by the porous sheet 10.
As shown in FIG. 1B, the solid electrolyte 20 has a continuous through structure 12 in the thickness direction T. This continuous penetration structure 12 exists in the opening of the porous sheet 10. Since the solid electrolyte 20 has a continuous through structure, the ion conduction path is not cut and the ionic conductivity is not lowered.

  In FIG. 1B, the number of perforated sheets 10 is one, but a plurality of thin sheets may be stacked. Moreover, the thickness of the solid electrolyte sheet may be thicker than the thickness of the porous sheet. The shape is not limited to regular pores, and may be irregular or random pores.

  Since the solid electrolyte sheet of the present invention includes a support made of a photosensitive resin, it has excellent mechanical strength. For example, the sheet of the present invention is a self-supporting sheet that can be easily handled and moved without being chipped or cracked even with tweezers. In addition, since the support is made of a photosensitive resin, the aperture ratio and the thickness of the support can be easily adjusted by patterning or the like.

  The thickness of the solid electrolyte sheet is preferably 10 to 500 μm, more preferably 50 to 400 μm, and particularly preferably 500 to 100 μm. If the thickness is less than 10 μm, a short circuit may occur in the electrolyte layer when the battery is formed. On the other hand, if the thickness exceeds 500 μm, the lithium ion conductivity in the electrolyte layer may decrease, and the battery performance may decrease.

The thickness of the porous sheet can be appropriately set according to the thickness of the solid electrolyte sheet, and is preferably thinner (for example, 10 to 300 μm). When the thickness of the porous sheet is thin, more batteries can be accumulated in a limited volume, and the battery capacity can be increased. Moreover, since the thickness of a solid electrolyte sheet also becomes thin, internal resistance falls. Therefore, the charge / discharge current can be increased. In addition, since the solid electrolyte sheet becomes flexible, an all-solid secondary battery having flexibility can be obtained.
Examples of the shape of the through hole of the porous sheet include a circle, a square, a rectangle, and other polygons.

  Since the support included in the solid electrolyte sheet of the present invention is made of a photosensitive resin, a patterned support can be easily obtained. Thereby, the freedom degree of the thickness of a support body increases. For example, the following effects can be obtained by reducing the thickness of the support. First, it is possible to accumulate more batteries in a limited volume compared to the conventional case, and it is possible to increase the battery capacity. Secondly, since the thickness of the solid electrolyte is also reduced, the internal resistance is lowered. Therefore, the charge / discharge current can be increased. Third, since the solid electrolyte sheet becomes flexible, an all-solid secondary battery having flexibility can be obtained.

As the photosensitive resin, a known negative type or positive type photosensitive resin can be used.
When producing a thin porous sheet (for example, 10 to 300 μm), it is preferable to use a photosensitive polyimide resin. More specifically, a negative photosensitive resin in which a photosensitive group is introduced into the carboxyl group of polyamic acid by amide bond described in JP-A-60-1000014, Polymer Engineering And Science, July 1989, Vol 29,964 A positive photosensitive resin composition obtained by blending naphthoquinone diazide sulfonic acid ester with a polyimide resin having a phenol group described in JP-A-7-196917, or the like. be able to. The resin is excellent in heat resistance, electrical characteristics and mechanical characteristics.
The thin porous sheet made of the above resin is tough and excellent in heat resistance and electrical insulation.

  In the patterning, the resin is applied to a smooth substrate, dried, exposed through a mask, and developed using a developer. After the development, drying is performed and the obtained pattern is cured, whereby a patterned polyimide resin can be obtained. In addition, the porous sheet of the present invention includes, for example, a resin composition containing a polyimide precursor, a sensitizer, and a photopolymerization initiator, specifically, a material described in JP-A-7-196917. It is obtained by blending appropriately.

  A polymer having an unsaturated double bond can be used as the photosensitive resin for producing a thick porous sheet (for example, 100 to 500 μm). Examples of the polymer include cellulosic polymers, polyamides, modified polyvinyl alcohol, and polyisoprene. Moreover, when using the said polymer which does not have an unsaturated double bond, it can also be used as a photosensitive resin by making the said polymer into a binder resin and mixing this with a polyfunctional acrylate monomer and a photoinitiator. it can. After molding such a resin into a plate shape, patterning is performed through a positive or negative mask, and development is performed using a developer. After development, drying can be performed to obtain a porous sheet. As specific resins, Cosmolite manufactured by Toyobo Co., Ltd., Cyrel manufactured by DuPont Co., Ltd., Flex Seed manufactured by Nippon Paint Co., Ltd., and the like can be used.

The opening ratio of the support contained in the solid electrolyte sheet of the present invention is preferably 40 to 90%. Thereby, ion conduction path | pass inhibition can be suppressed and a ionic conductivity can prevent a fall. The aperture ratio indicates the ratio of the opening to a certain area of the support.
Since the porous sheet (support) contained in the solid electrolyte sheet of the present invention is made of resin and the opening can be freely designed by patterning or the like, the opening ratio can be simply calculated from the following equation.
Opening ratio (%) = sum of opening area × 100 / area of perforated sheet

The solid electrolyte used in the solid electrolyte sheet of the present invention is not particularly limited, and materials composed of organic compounds, inorganic compounds, or both organic and inorganic compounds can be used, and those known in the field of lithium ion batteries can be used. . In particular, sulfide-based inorganic solid electrolytes are known to have higher ionic conductivity than other inorganic compounds, and inorganic solid electrolytes described in JP-A-4-202024 can be used. Specifically, an inorganic solid electrolyte in which Li ₃ PO ₄ , a halogen, and a halogen compound are appropriately added to an inorganic solid electrolyte composed of a combination of Li ₂ S and SiS ₂ , GeS ₂ , P ₂ S ₅ , B ₂ S _3. Can be used. In addition, since lithium ion conductivity is high, lithium sulfide and diphosphorus pentasulfide, or lithium sulfide and simple phosphorus and simple sulfur, as well as lithium sulfide, diphosphorus pentasulfide, simple phosphorus and / or simple sulfur generated from lithium It is preferable to use an ion conductive inorganic solid electrolyte. The average particle diameter of the solid electrolyte during mixing is preferably 0.001 μm to 50 μm in consideration of dispersion in the sheet.

A binder can be added to the solid electrolyte as long as the object of the present invention is not impaired.
As the binder, a thermoplastic resin or a thermosetting resin can be used. For example, polysiloxane, polyalkylene glycol, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer ( FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer ( ETFE resin), polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene -Chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer Combined or (Na ⁺ ) ion crosslinked body of the material, ethylene-methacrylic acid copolymer or (Na ⁺ ) ion crosslinked body of the material, ethylene-methyl acrylate copolymer or (Na ⁺ ) ion crosslinked of the material Body, ethylene-methyl methacrylate copolymer, or (Na ⁺ ) ion-crosslinked body of the material.

Among these, polysiloxane, polyalkylene glycol, polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE) are preferable.
In particular, it is preferable to use fibrous polytetrafluoroethylene because a solid electrolyte sheet having high Li ion conductivity can be obtained.

  In addition, you may mix | blend the additive which has lithium ion conductivity, such as an ionic liquid, with a solid electrolyte.

Hereinafter, a preferable solid electrolyte will be described.
The lithium ion conductive inorganic solid electrolyte can be produced from lithium sulfide and diphosphorus pentasulfide and / or simple phosphorus and simple sulfur. Specifically, a lithium-phosphorous sulfide glass obtained by melting these raw materials and then rapidly cooling them or treating the raw materials by a mechanical milling method (hereinafter sometimes referred to as MM method) is used. Heat-treated.

As Li ₂ S, those commercially available without particular limitation can be used, but those having high purity are preferable as described below.
Lithium sulfide preferably has a total content of lithium salts of sulfur oxides of 0.15% by mass or less, more preferably 0.1% by mass or less, and a content of lithium N-methylaminobutyrate is preferably 0. .15% by mass or less, more preferably 0.1% by mass or less. When the total content of the lithium salt of sulfur oxide is 0.15% by mass or less, the obtained electrolyte is a glassy electrolyte (fully amorphous). That is, when the total content of the lithium salt of sulfur oxide exceeds 0.15% by mass, the obtained electrolyte is a crystallized product from the beginning, and the ionic conductivity of this crystallized product is low.
Furthermore, even if the crystallized product is subjected to the following heat treatment, the crystallized product is not changed, and a lithium ion conductive inorganic solid electrolyte having a high ion conductivity cannot be obtained.

Further, when the content of lithium N-methylaminobutyrate is 0.15% by mass or less, the deteriorated product of lithium N-methylaminobutyrate does not deteriorate the cycle performance of the lithium battery.
Therefore, in order to obtain a high ion conductive electrolyte, it is necessary to use lithium sulfide with reduced impurities.

The method for producing lithium sulfide used in the solid substance is not particularly limited as long as it is a method that can reduce at least the impurities.
For example, it can also be obtained by purifying lithium sulfide produced by the following method.
Among the following production methods, the method a or b is particularly preferable.
a. A method in which lithium hydroxide and hydrogen sulfide are reacted at 0 to 150 ° C. in an aprotic organic solvent to produce lithium hydrosulfide, and this reaction solution is then desulfurized at 150 to 200 ° C. -330312).
b. A method of directly producing lithium sulfide by reacting lithium hydroxide and hydrogen sulfide at 150 to 200 ° C. in an aprotic organic solvent (Japanese Patent Laid-Open No. 7-330312).
c. A method of reacting lithium hydroxide and a gaseous sulfur source at a temperature of 130 to 445 ° C. (Japanese Patent Laid-Open No. 9-283156).

There is no restriction | limiting in particular as a purification method of the lithium sulfide obtained as mentioned above. Preferable purification methods include, for example, International Publication No. WO2005 / 40039.
Specifically, the lithium sulfide obtained as described above is washed at a temperature of 100 ° C. or higher using an organic solvent.
The organic solvent used for washing is preferably an aprotic polar solvent, and more preferably, the aprotic organic solvent used for lithium sulfide production and the aprotic polar organic solvent used for washing are the same. .
Examples of the aprotic polar organic solvent preferably used for washing include aprotic polar organic compounds such as amide compounds, lactam compounds, urea compounds, organic sulfur compounds, cyclic organophosphorus compounds, Or it can use suitably as a mixed solvent. In particular, N-methyl-2-pyrrolidone (NMP) is selected as a good solvent.

The amount of the organic solvent used for washing is not particularly limited, and the number of times of washing is not particularly limited, but is preferably 2 or more. Cleaning is preferably performed under an inert gas such as nitrogen or argon.
The washed lithium sulfide is dried at a temperature equal to or higher than the boiling point of the organic solvent used for washing for 5 minutes or more, preferably about 2 to 3 hours or more under an inert gas stream such as nitrogen under normal pressure or reduced pressure. Thus, lithium sulfide used in the present invention can be obtained.

P ₂ S ₅ can be used without particular limitation as long as it is industrially produced and sold. In place of P ₂ S ₅ , elemental phosphorus (P) and elemental sulfur (S) in a corresponding molar ratio can also be used. Simple phosphorus (P) and simple sulfur (S) can be used without particular limitation as long as they are industrially produced and sold.

The mixing molar ratio of the lithium sulfide to diphosphorus pentasulfide or simple phosphorus and simple sulfur is usually 50:50 to 80:20, preferably 60:40 to 75:25.
Particularly preferably, it is about Li ₂ S: P ₂ S ₅ = 68: 32 to 74:26 (molar ratio).

As a method for producing lithium / phosphorous sulfide glass, there are a melt quenching method and a mechanical milling method (MM method).
In the case of the melt quenching method, P ₂ S ₅ and Li ₂ S mixed in a predetermined amount in a mortar and pelletized are placed in a carbon-coated quartz tube and vacuum-sealed. Lithium / phosphorous sulfide glass is obtained by reacting at a predetermined reaction temperature and then putting it into ice and quenching.
The reaction temperature at this time is preferably 400 ° C to 1000 ° C, more preferably 800 ° C to 900 ° C.
Moreover, reaction time becomes like this. Preferably it is 0.1 to 12 hours, More preferably, it is 1 to 12 hours.
The quenching temperature of the reaction product is usually 10 ° C. or lower, preferably 0 ° C. or lower, and the cooling rate is about 1 to 10,000 K / sec, preferably 1 to 1000 K / sec.

When the MM method is used, a predetermined amount of P ₂ S ₅ and Li ₂ S are mixed in a mortar and reacted for a predetermined time by a mechanical milling method, thereby obtaining a lithium / phosphorous sulfide glass.
The mechanical milling method using the above raw materials can be reacted at room temperature. According to the MM method, since a glassy electrolyte can be produced at room temperature, there is an advantage that a raw material is not thermally decomposed and a glassy electrolyte having a charged composition can be obtained.
Further, the MM method has an advantage that the glassy electrolyte can be made into fine powder simultaneously with the production of the glassy electrolyte.
Although various types of MM methods can be used, it is particularly preferable to use a planetary ball mill.
The planetary ball mill can efficiently generate very high impact energy by rotating the platform while the pot rotates.
Although the rotation speed and rotation time of the MM method are not particularly limited, the faster the rotation speed, the faster the glassy electrolyte production rate, and the longer the rotation time, the higher the conversion rate of the raw material into the glassy electrolyte.
The electrolyte thus obtained is a glassy electrolyte and usually has an ionic conductivity of about 1.0 × 10 ^{−5 to} 8.0 × 10 ⁻⁴ (S / cm).

As conditions for the MM method, for example, when a planetary ball mill is used, the rotational speed may be set to several tens to several hundreds of revolutions / minute, and the treatment may be performed for 0.5 hours to 100 hours.
Although specific examples of the sulfide glass by the melt quenching method and the MM method have been described above, manufacturing conditions such as temperature conditions and processing time can be appropriately adjusted according to the equipment used.

Thereafter, the obtained lithium / phosphorous sulfide glass is heat-treated at a predetermined temperature to produce a solid electrolyte.
The heat treatment temperature for generating the solid electrolyte is preferably 190 ° C to 340 ° C, more preferably 195 ° C to 335 ° C, and particularly preferably 200 ° C to 330 ° C.
When the temperature is lower than 190 ° C., it may be difficult to obtain a crystal with high ion conductivity. When the temperature is higher than 340 ° C., a crystal with low ion conductivity may be generated.
In the case of a temperature of 190 ° C. or higher and 220 ° C. or lower, the heat treatment time is preferably 3 to 240 hours, particularly preferably 4 to 230 hours. Moreover, in the case of the temperature higher than 220 degreeC and 340 degrees C or less, 0.1 to 240 hours are preferable, 0.2 to 235 hours are especially preferable, Furthermore, 0.3 to 230 hours are preferable.
If the heat treatment time is shorter than 0.1 hour, it may be difficult to obtain a crystal with high ion conductivity, and if it is longer than 240 hours, a crystal with low ion conductivity may be formed.
The lithium ion conductive inorganic solid electrolyte thus obtained usually has an ionic conductivity of about 7.0 × 10 ^{−4 to} 5.0 × 10 ⁻³ (S / cm).

This lithium ion conductive inorganic solid electrolyte has 2θ = 17.8 ± 0.3 deg, 18.2 ± 0.3 deg, 19.8 ± 0.3 deg, X-ray diffraction (CuKα: λ = 1.5418４), It is preferable to have diffraction peaks at 21.8 ± 0.3 deg, 23.8 ± 0.3 deg, 25.9 ± 0.3 deg, 29.5 ± 0.3 deg, 30.0 ± 0.3 deg.
A solid electrolyte having such a crystal structure has extremely high lithium ion conductivity.

The solid electrolyte sheet of the present invention can be produced, for example, by the following method.
The solid electrolyte sheet of the present invention can be produced by dissolving the solid electrolyte in a solvent to form a slurry and applying it to a support.
The solvent used for slurrying the solid electrolyte is not particularly limited as long as it does not adversely affect the performance of the solid electrolyte, and examples thereof include non-aqueous solvents.
Examples of the non-aqueous solvent include solvents used in electrolyte solutions such as dry heptane, toluene, hexane, tetrahydrofuran (THF), N methylpyrrolidone, acetonitrile, dimethoxyethane, and dimethyl carbonate, and preferably have a water content. The solvent is 100 ppm or less, more preferably 50 ppm or less.

  As a coating method when applying the slurry solid electrolyte to both sides or one side of the support, slide die coating, comma die coating, comma reverse coating, etc. can be used when producing a thick film. In such a case, a gravure coat, a gravure reverse coat or the like can be used.

  After applying the solid electrolyte slurry, drying is performed. For drying, a drying device using hot air, a heater, high frequency, or the like can be used. Drying may be performed from both sides of the solid electrolyte sheet or from one side. At this time, for example, in the case of hot air, it is necessary to optimally adjust the temperature and the air volume so that the solvent in the slurry is not sufficiently removed. Although the dried solid electrolyte sheet can be used as it is, it can be further pressurized to increase the strength. For pressurization, a sheet press or a roll press can be used. If the pressure at the time of pressurization is low, the thickness of the solid electrolyte layer may be uneven, and if it is high, the support including the solid electrolyte and the resin may be damaged.

  On the other hand, when a solid electrolyte is used as a powder instead of being slurried, the solid electrolyte is collided at high speed by the sandblast method (SB method), aerosol deposition method (AD method), etc. -It may be filled or the solid electrolyte may be sprayed as it is. Furthermore, the solid electrolyte powder can be placed on the support in an inert gas and sucked from below the support to fill the support with the solid electrolyte (autoclave method). Alternatively, the solid electrolyte powder may be placed on both sides or one side of the support and pressurized using a press or the like to fill the openings of the support. When forming a sheet using the solid electrolyte as a powder, ultrasonic waves or the like may be applied after filling the solid electrolyte from the viewpoint of improving the filling efficiency.

  The electrode sheet of the present invention has the same structure except that the solid electrolyte of the solid electrolyte sheet of the present invention is replaced with an electrode material. That is, it includes an electrode material and an open support, the electrode material has a continuous through structure in the thickness direction, and the support is made of a photosensitive resin. The opening ratio of the support is preferably 40 to 90%.

The electrode material includes a positive electrode material and a negative electrode material.
As a positive electrode material, what is used as a positive electrode active material in the battery field | area can be used. For example, in the sulfide system, titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), iron sulfide (FeS, FeS ₂ ), copper sulfide (CuS), nickel sulfide (Ni ₃ S ₂ ), and the like can be used. Preferably, TiS ₂ can be used.
In the oxide system, bismuth oxide (Bi ₂ O ₃ , Bi ₂ Pb ₂ O ₅ ), copper oxide (CuO), vanadium oxide (V ₆ O ₁₃ ), lithium cobaltate (LiCoO ₂ ), lithium nickelate ( LiNiO ₂ ), lithium manganate (LiMnO ₂ ) and the like can be used. It is also possible to use a mixture of these. Preferably, lithium cobaltate can be used.
In addition to the above, niobium selenide (NbSe ₃ ) can also be used.

  As a negative electrode material, what is used as a negative electrode active material in the battery field | area can be used. For example, carbon materials, specifically artificial graphite, graphite carbon fiber, resin-fired carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon Examples include fibers, vapor grown carbon fibers, natural graphite, and non-graphitizable carbon. Or it may be a mixture thereof. Preferably, it is artificial graphite. Moreover, the metal itself of metal lithium, metal indium, metal aluminum, or metal silicon, or the alloy which combined these metals with another element or compound can be used as a negative electrode material.

  In the electrode sheet of the present invention, in order to improve the ionic conductivity in addition to the electronic conductivity, the particles of the electrode material are in close contact with each other, there are many junctions and surfaces between the particles, and more ion conduction paths are secured. It is important to. Therefore, a method of mixing an ion conductive active material such as a solid electrolyte used in the solid electrolyte sheet with the electrode material is also used. In addition, the smaller the space generated in the gaps between the electrode material particles (the ratio of the volume of the electrode material particles to the volume of the electrode material particles: the porosity), the denser the electrode material is, and the higher the ionic conductivity.

Moreover, you may mix the solid electrolyte used with a conductive support agent and a solid electrolyte sheet with the said electrode material.
The conductive auxiliary agent is a substance having electrical conductivity for allowing electrons to move smoothly in the positive electrode active material. Although it does not specifically limit as a conductive support agent, Conductive substances, such as acetylene black, carbon black, and a carbon nanotube, or conductive polymers, such as polyaniline, polyacetylene, and polypyrrole, can be used individually or in mixture.

  The electrode sheet can be produced in the same manner as the solid electrolyte sheet.

The all solid state secondary battery of the present invention has at least one of the above-described solid electrolyte sheet and electrode sheet of the present invention.
FIG. 2 is a schematic cross-sectional view showing an embodiment of an all solid state secondary battery according to the present invention.
The all solid state secondary battery 2 has a configuration in which an electrolyte 40 is sandwiched between a pair of electrodes including a positive electrode 30 and a negative electrode 50. The positive electrode 30 includes a current collector 32 and a positive electrode sheet 34, and the negative electrode 50 includes a current collector 52 and a negative electrode sheet 54. These 34 and 54 are electrode sheets of the present invention. The electrolyte 40 consists of the solid electrolyte sheet 1, and the solid electrolyte sheet 1 is the solid electrolyte sheet of the present invention.

As the current collectors 32 and 52, a plate or foil made of copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, indium, lithium, or an alloy thereof, or the like Can be used.
The current collectors 32 and 52 may be the same or different. For example, a copper foil may be used for the current collector 32, and an aluminum foil may be used for the current collector 52.

  In FIG. 2, the sheet of the present invention is used for all of the positive electrode, the negative electrode, and the solid electrolyte, but the sheet of the present invention may be used for at least one of the positive electrode, the negative electrode, and the solid electrolyte.

The all-solid-state secondary battery of the present invention can be manufactured by laminating and bonding the above-described electrode sheet and / or solid electrolyte sheet of the present invention. As a method of joining, there are a method of laminating each sheet, pressurizing and pressure bonding, a method of pressing through two rolls (roll to roll), and the like.
Moreover, you may join to the joining surface through the active material which has ion conductivity, and the adhesive material which does not inhibit ion conductivity.
In joining, heat fusion may be performed as long as the crystal structure of the solid electrolyte does not change.

The all solid state secondary battery of the present invention becomes a practical level all solid state battery by joining the electrode sheet and / or the solid electrolyte sheet.
Further, since the battery of the present invention can be thinned, it can be stacked to obtain a high output. Furthermore, a high degree of integration is possible.

Production Example 1 (Production of lithium / phosphorous sulfide solid electrolyte)
(1) Production of lithium sulfide (Li ₂ S) Lithium sulfide was produced according to the method of the first aspect (two-step method) of JP-A-7-330312. Specifically, N-methyl-2-pyrrolidone (NMP) 3326.4 g (33.6 mol) and lithium hydroxide 287.4 g (12 mol) were charged into a 10 liter autoclave equipped with a stirring blade, and 300 rpm, 130 The temperature was raised to ° C. After the temperature rise, hydrogen sulfide was blown into the liquid at a supply rate of 3 liters / minute for 2 hours. Subsequently, this reaction solution was heated in a nitrogen stream (200 cc / min) to dehydrosulfide a part of the reacted hydrogen sulfide. As the temperature increased, water produced as a by-product due to the reaction between hydrogen sulfide and lithium hydroxide started to evaporate, but this water was condensed by the condenser and extracted out of the system. While water was distilled out of the system, the temperature of the reaction solution rose, but when the temperature reached 180 ° C., the temperature increase was stopped and the temperature was kept constant. After the dehydrosulfurization reaction was completed (about 80 minutes), the reaction was completed to obtain lithium sulfide.

(2) Purification of lithium sulfide After decanting NMP in the 500 mL slurry reaction solution (NMP-lithium sulfide slurry) obtained in (1) above, 100 mL of dehydrated NMP was added and stirred at 105 ° C. for about 1 hour. did. NMP was decanted at that temperature. Further, 100 mL of NMP was added, stirred at 105 ° C. for about 1 hour, NMP was decanted at that temperature, and the same operation was repeated a total of 4 times. After completion of the decantation, lithium sulfide was dried at 230 ° C. (temperature higher than the boiling point of NMP) under a nitrogen stream for 3 hours under normal pressure. The impurity content in the obtained lithium sulfide was measured.

Incidentally, lithium sulfite _(Li 2 _SO 3), the content of each sulfur oxide lithium sulfate _(Li 2 SO ₄₎ and lithium thiosulfate _{(Li 2 S 2 O 3)} , and N- methylamino acid lithium (LMAB) Was quantified by ion chromatography. As a result, the total content of sulfur oxides was 0.13% by mass, and LMAB was 0.07% by mass.

(3) Production of lithium ion conductive solid electrolyte Li ₂ S and P ₂ S ₅ (manufactured by Aldrich) produced in the above production example were used as starting materials. About 1 g of a mixture prepared at a molar ratio of 70 to 30 and 10 alumina balls having a particle diameter of 10 mmΦ are placed in a 45 mL alumina container, and a planetary ball mill (manufactured by Fritsch: Model No. P-7) is used. A sulfide-based glass that was a white-yellow powder was obtained by mechanical milling for 20 hours at a rotational speed of 370 rpm at room temperature (25 ° C.) in nitrogen.
Powder X-ray diffraction measurement was performed on the obtained powder (CuKα: λ = 1.5418Å). Since the obtained chart showed a broad shape peculiar to the amorphous body, it was confirmed that this powder was vitrified (amorphized).

  This powder (sulfide-based glass) was fired in nitrogen at a temperature range from room temperature (25 ° C.) to 250 ° C. to produce a lithium ion conductive solid electrolyte. It took about 3 hours to raise and lower the temperature.

The lithium ion conductive solid electrolyte produced above was subjected to powder X-ray diffraction measurement (CuKα: λ = 1.5418Å). The obtained glass ceramic was confirmed to have diffraction peaks at 2θ = 17.8 deg, 18.2 deg, 19.8 deg, 21.8 deg, 23.8 deg, 25.9 deg, 29.5 deg, 30.0, It has been confirmed that it has a crystal phase different from the conventionally known Li ₇ PS ₆ , Li ₄ P ₂ S ₆ , and Li ₃ PS ₄ .

The ion conductivity at room temperature (25 ° C.) of the lithium ion conductive solid electrolyte obtained by this treatment was 2.0 × 10 ⁻³ Scm ⁻¹ .
The ionic conductivity was measured while processing the produced glass powder (powder before firing) into a pellet-like (diameter of about 10 mm, thickness of about 1 mm), and subjecting this compact to firing. . The measurement was performed by an alternating current two-terminal method for a molded body in which a carbon paste was applied as an electrode.

Production Example 2 (Manufacture of lattice sheet)
With respect to 100 parts by weight of the polyimide precursor, 2,6-bis- (4-diethylaminobenzal) -4-methyl-cyclohexanone as a photosensitizer and 0.5% of N-phenylglycine as a photopolymerization initiator are used. 10 parts by weight was added, and an organic solvent (N-methyl-2-pyrrolidone) was added as appropriate until coating was possible to obtain a resin composition.
The polyimide precursor was synthesized as follows. First, the inside of a flask equipped with a stirrer and a thermometer is replaced with nitrogen gas. Thereafter, 12.86 g of 3,3′-diaminobenzidine and 200 g of N-methyl-2-pyrrolidone were added into the flask. While maintaining the temperature of the mixture in the flask at 10 ° C. or lower, 18.60 g of isocyanatoethyl methacrylate was further added and stirred at room temperature for 3 hours. Furthermore, 6.00 g of 4,4′-diaminodiphenyl ether and 2.49 g of 1,3-bis (3-aminopropyl) -1,1,3,3, -tetramethyldisiloxane were added to the flask. Then, 32.22 g of 3,3′-benzophenonetetracarboxylic acid and 4,4′-benzophenonetetracarboxylic dianhydride were added while cooling so that the temperature of the reaction solution in the flask did not exceed 40 ° C. did. After completion of the addition, the mixture in the flask was stirred at room temperature for 10 hours to obtain a polyimide precursor.

Next, the said resin composition was apply | coated by the casting method so that thickness might be set to 200 micrometers on the smooth glass substrate which performed the mold release process, and it was made to dry for 30 minutes-2 hours at the temperature of 100-180 degreeC. Thereafter, a negative mask having a lattice pattern with an opening shape having a pitch of 20 μm and an opening shape having a side of 200 μm was brought into close contact with the resin surface, and ultraviolet rays of 100 to 3000 mJ / cm ² were irradiated using a high-pressure mercury lamp.
After the ultraviolet irradiation, development was performed using an aqueous alkali solution such as sodium hydroxide, and the grid sheet was sufficiently dried with hot air of 50 to 80 ° C. for 15 to 30 minutes. Then, the imidation reaction was accelerated | stimulated by heating the said sheet | seat at the temperature of 200-400 degreeC for 1-3 hours, and the lattice-shaped sheet | seat of the patterned polyimide resin was obtained. When the obtained sheet was observed using a scanning electron microscope (SEM), the aperture ratio was about 80%.

Example 1
First, using the lithium ion conductive solid electrolyte of Production Example 1 and dehydrated toluene, a slurry solution having a solid electrolyte weight percentage of 30% was prepared. Next, a lattice-shaped sheet having a thickness of 200 μm produced in Production Example 2 was cut out into a circular shape of φ40 mm.
The slurry solution was applied to the grid sheet using a bar coater, and the solvent toluene was removed by drying at about 70 ° C. to obtain a solid electrolyte sheet. The solid electrolyte sheet was pressed at a pressure of about 3500 kg / cm ² using a press to obtain a solid electrolyte sheet having a thickness of about 310 μm.

When the ionic conductivity of the obtained solid electrolyte sheet was measured by the alternating current impedance method (measurement frequency: 100 Hz to 15 MHz), it was 1.76 × 10 ⁻³ S / cm, and in Production Example 1 not including the lattice sheet It showed an ionic conductivity of about 88% of the solid electrolyte. Further, this solid electrolyte sheet was a self-supporting sheet having a strength that can be easily handled and moved without causing the surroundings to be sandwiched between tweezers or cracking the solid electrolyte sheet.

Comparative Example 1
The manufacturing process of the solid electrolyte sheet was advanced in the same manner as in Example 1 except that the grid sheet of Production Example 2 was not used. However, when the pellet was confirmed after the pressurizing operation with the press, a part of the outer peripheral portion was separated and several cracks were generated in the pellet. In order to measure the ionic conductivity, when trying to lift the pellet with tweezers, the pellet itself was damaged and the ionic conductivity could not be measured.

Example 2
A lithium battery was produced as follows using carbon graphite (manufactured by TIMCAL, SFG-15) as the negative electrode material, and lithium cobaltate (LiCoO ₂ ) as the positive electrode material, and the battery characteristics were evaluated.

The lithium ion conductive solid electrolyte obtained in Production Example 1 and carbon graphite were mixed at a mass ratio of 1: 1 to obtain a negative electrode material.
Moreover, what mixed lithium cobaltate and the lithium ion conductive solid electrolyte obtained by manufacture example 1 by mass ratio of 8: 5 was used as positive electrode material.
Using the negative electrode material (10 mg) and the positive electrode material (20 mg), a three-layer structure was formed between the negative electrode material (10 mg) and the positive electrode material (20 mg), thereby forming a measurement cell.

  When the battery characteristics were examined by charging and discharging this measurement cell with a constant current of 10 μA, the initial charge / discharge efficiency was 83%. The operating potential of this battery (potential difference of the positive electrode when the standard electrode potential of lithium metal was used as a reference (0V)) was 3.4V.

The solid electrolyte sheet and electrode sheet of the present invention can be used for an all-solid secondary battery.
The all-solid-state secondary battery of the present invention can be used as a battery for a portable information terminal, a portable electronic device, a small electric power storage device for home use, a motorcycle using a motor as a power source, an electric vehicle, a hybrid electric vehicle, or the like.

It is a schematic top view which shows one Embodiment of the support body used for the solid electrolyte sheet which concerns on this invention. It is a schematic sectional drawing which shows one Embodiment of the all-solid-state secondary battery which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid electrolyte sheet 2 All-solid-state secondary battery 10 Porous sheet 12 Continuous penetration structure 20 Solid electrolyte 30 Positive electrode 32,52 Current collector 34 Positive electrode sheet 40 Electrolyte 50 Negative electrode 54 Negative electrode sheet

Claims (3)

Including a solid electrolyte and a support having a plurality of openings;
The solid electrolyte has a continuous through structure in the thickness direction at the opening of the support,
A solid electrolyte sheet in which the support is made of a photosensitive resin. Including a support having an electrode material and a plurality of openings;
The electrode material has a continuous through structure in the thickness direction at the opening of the support,
A solid electrolyte sheet in which the support is made of a photosensitive resin. An all solid state secondary battery comprising at least one of the solid electrolyte sheet according to claim 1 and the electrode sheet according to claim 2.

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