WO2022149477A1 - Oxide solid electrolyte, electrode mixture, and all-solid lithium ion battery - Google Patents

Abstract

This oxide solid electrolyte is a composite containing lithium sulfate (Li2SO4) and lithium carbonate (Li2CO3), wherein: the molar ratio (Li2SO4:Li2CO3) of the lithium sulfate and the lithium carbonate is 20:80 to 80:20; in the curve obtained by differential scanning calorimetry, the position of an exothermic peak is 200 °C or less; and the oxide solid electrolyte has a conductivity of 1.0×10-7 S/cm or more.

Description

Oxide solid electrolyte, electrode mixture, and all-solid-state lithium-ion battery

The present invention relates to a solid oxide electrolyte, an electrode mixture, and an all-solid-state lithium-ion battery. This application claims priority based on Japanese Patent Application No. 2021-002328 filed in Japan on January 8, 2021, and the contents thereof are incorporated herein by reference.

Lithium-ion secondary batteries have high energy density and are used in information-related equipment such as personal computers and mobile phones. In recent years, development of high-output and high-capacity lithium-ion secondary batteries for electric vehicles or hybrid vehicles has been promoted.

However, since the current lithium-ion secondary battery uses a flammable organic electrolytic solution, there is a problem that the lithium-ion secondary battery tends to ignite when it overheats. In fact, ignition accidents caused by lithium-ion secondary batteries have occurred in mobile devices, and there is a strong demand for improved safety.

As a technique for improving the safety of a lithium ion secondary battery, there is a technique using a solid electrolyte. However, in the case of an all-solid lithium ion secondary battery using a solid electrolyte, the negative electrode mixture layer, the solid electrolyte layer, and the positive electrode mixture layer are in solid-solid contact, respectively. Therefore, the movement paths of electrons and ions are significantly reduced as compared with the conventional lithium ion secondary battery using an organic electrolytic solution. In particular, since the oxide solid electrolyte having high conductivity is a hard particle and is not easily deformed, a good contact state between the solid and the solid cannot be obtained even by pressing or the like. Therefore, in the oxide solid electrolyte having high conductivity, the conductivity of electrons or ions between the oxide solid electrolytes is low. Therefore, it is currently required to improve the contact state between solid electrolytes.

As a technique for improving the contact state between solid electrolytes, Patent Document 1 sinters a lithium ion conductive inorganic substance containing _2.6 to 52.0% of ZrO2 component at an oxide-based mass%. The technology to be used is disclosed. Non-Patent Document 1 discloses a technique for sintering glass ceramics having a NASICON type crystal structure. Non-Patent Document 2 discloses a technique for hot-pressing Li ₃ BO ₃ -Li ₂ SO ₄ .

Japanese Patent Application Laid-Open No. 2012-246196

In the case of Patent Document 1 and Non-Patent Document 1, the contact between particles is improved by sintering at a high temperature, but the reaction of the solid electrolyte and the electrode active material at a high temperature causes ionic conductivity and charge / discharge reactivity. There is a problem of deterioration. In addition, in the case of Patent Document 1 and Non-Patent Document 1, since processing at a high temperature is required, there is a problem that equipment cost and running cost are high. Further, in the technique of Non-Patent Document 2, the contact state between particles is improved by hot-pressing a material for which a good contact state between particles cannot be formed at room temperature, but a high temperature is required. There is a problem that equipment cost and running cost are high. Therefore, there is a demand for a solid electrolyte having higher deformability at room temperature than the solid electrolyte disclosed in Non-Patent Document 2.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an oxide solid electrolyte having good deformability at room temperature and having high conductivity. Here, the normal temperature means 20 ° C to 30 ° C. Further, "good deformability at room temperature" means, for example, deformability at which the relative density becomes 95% or more in a press at room temperature and 1 GPa.

In order to solve the above problems, the present invention proposes the following means.
(1) The oxide solid electrolyte according to one aspect of the present invention is a composite containing lithium sulfate (Li ₂ SO ₄ ) and lithium carbonate (Li ₂ CO ₃ ).
The molar ratio of the lithium sulfate to the lithium carbonate (Li ₂ SO ₄ : Li ₂ CO ₃ ) is 20:80 to 80:20.
In the curve obtained by differential scanning calorimetry, the position of the exothermic peak is 200 ° C. or less, and the conductivity is 1.0 × 10 ^-7 S / cm or more.
(2) The oxide solid electrolyte according to (1) above is composed of a group consisting of lithium chloride, lithium bromide, lithium iodide, lithium borate, lithium phosphate, lithium nitrate, lithium silicate, and lithium aluminate. At least one selected may be further included.
(3) The electrode mixture according to one aspect of the present invention is
With the oxide solid electrolyte according to (1) or (2) above,
Electrode active material and
With conductive material
Including
The mass ratio of the oxide solid electrolyte, the electrode active material, and the conductive material (oxide solid electrolyte: electrode active material: conductive material) is 20 to 80:20 to 80: 0 to 30.
(4) The all-solid-state lithium-ion battery according to one aspect of the present invention contains the oxide solid electrolyte according to the above (1) or (2).
(5) The all-solid-state lithium-ion battery according to (4) above may include a solid electrolyte layer containing the oxide solid electrolyte.
(6) The all-solid lithium-ion battery according to (4) or (5) above may include a positive electrode active material layer containing the oxide solid electrolyte or a negative electrode active material layer containing the oxide solid electrolyte.
(7) In the all-solid lithium-ion battery according to (6) above, the positive electrode active material layer contains the oxide solid electrolyte, the positive electrode active material, and the positive electrode conductive material.
The mass ratio (oxide solid electrolyte: positive electrode active material: positive electrode conductive material) of the oxide solid electrolyte, the positive electrode active material, and the positive electrode conductive material is 20 to 80:20 to 80: 0 to 30. You may.
(8) In the all-solid lithium-ion battery according to (6) or (7) above, the negative electrode active material layer contains the oxide solid electrolyte, the negative electrode active material, and the negative electrode conductive material.
The mass ratio (oxide solid electrolyte: negative electrode active material: negative electrode conductive material) of the oxide solid electrolyte, the negative electrode active material, and the negative electrode conductive material is 20 to 80:20 to 80: 0 to 30. You may.

According to the above aspect of the present disclosure, it is possible to provide an oxide solid electrolyte, an electrode mixture, and an all-solid-state lithium-ion battery having good deformability at room temperature and high conductivity.

It is sectional drawing of the all-solid-state lithium ion battery which concerns on one Embodiment of this disclosure.

<Oxide solid electrolyte>
The oxide solid electrolyte of the present disclosure will be described. It should be noted that the embodiments exemplified below are for facilitating the understanding of the present invention, and are not for limiting the interpretation of the present invention. The present invention can be modified or improved from the following embodiments without departing from the spirit of the present invention.

(Composite containing lithium sulfate (Li ₂ SO ₄ ) and lithium carbonate (Li ₂ CO ₃ ))
The oxide solid electrolyte of the present disclosure is a composite containing lithium sulfate (Li ₂ SO ₄ ) and lithium carbonate (Li ₂ CO ₃ ). Here, the composite means a composite obtained by mixing a raw material containing lithium sulfate and lithium carbonate, for example, with a planetary ball mill. The oxide solid electrolyte of the present disclosure contains lithium sulfate and lithium carbonate, so that good conductivity and good deformability can be obtained.

(The molar ratio of lithium sulfate to the lithium carbonate (Li ₂ SO ₄ : Li ₂ CO ₃ ) is 20:80 to 80:20).
The solid oxide electrolyte of the present disclosure contains lithium sulfate (Li ₂ SO ₄ ) and lithium carbonate (Li ₂ CO ₃ ), and the molar ratio of lithium sulfate to lithium carbonate (Li ₂ SO ₄ : Li ₂ CO ₃ ). Is from 20:80 to 80:20. When the molar ratio of lithium sulfate to lithium carbonate is in the above range, the oxide solid electrolyte has good deformability at room temperature. A more preferable molar ratio of lithium sulfate to lithium carbonate is 30:70 to 70:30.

In the solid oxide electrolyte of the present disclosure, the total content of lithium sulfate and lithium carbonate is preferably 30% by mass to 100% by mass. When the total content of lithium sulfate and lithium carbonate is in the above range, better deformability at room temperature can be obtained, which is preferable. More preferably, the total content of lithium sulfate and lithium carbonate is 40% by mass to 100% by mass.

(At least one selected from the group consisting of lithium chloride, lithium bromide, lithium iodide, lithium borate, lithium phosphate, lithium nitrate, lithium silicate, and lithium aluminate)
The solid oxide electrolyte of the present disclosure is at least one selected from the group consisting of lithium chloride, lithium bromide, lithium iodide, lithium borate, lithium phosphate, lithium nitrate, lithium silicate, and lithium aluminate. Further, it is preferable to include it. Higher conductivity by further comprising at least one selected from the group consisting of lithium chloride, lithium bromide, lithium iodide, lithium borate, lithium phosphate, lithium nitrate, lithium silicate, and lithium aluminate. Is preferable because it can be obtained.

The total content of lithium chloride, lithium bromide, lithium iodide, lithium borate, lithium phosphate, lithium nitrate, lithium silicate, and lithium aluminome in the solid oxide electrolyte of the present disclosure is 0% by mass to 70% by mass. % Is preferable. If the total content of lithium chloride, lithium bromide, lithium iodide, lithium borate, lithium phosphate, lithium nitrate, lithium silicate, and lithium aluminate is within the above range, better conductivity can be obtained. It is preferable because it can be used. More preferably, the total content of lithium chloride, lithium bromide, lithium iodide, lithium borate, lithium phosphate, lithium nitrate, lithium silicate, and lithium aluminate is 0% by mass to 60% by mass.

The chemical composition of the oxide solid electrolyte of the present disclosure is, for example, an energy-dispersed X-ray mounted on an electrolytic emission type transmission electron microscope (TEM) in a cross section of a positive electrode, a solid electrolyte layer, or a negative electrode of a lithium ion secondary battery. It can be quantified by a spectroscope (EDX) and Raman spectroscopy.

(The position of the exothermic peak is 200 ° C or less in the curve obtained by differential scanning calorimetry)
The solid oxide electrolyte of the present disclosure has an exothermic peak of 200 ° C. or lower in the curve (DSC curve) obtained by differential scanning calorimetry (DSC) measurement. When the position of the exothermic peak is 200 ° C. or lower in the DSC curve, good deformability of the oxide solid electrolyte can be obtained. A more preferable position of the exothermic peak is 190 ° C. or lower. The lower limit of the position of the exothermic peak is not particularly limited, but may be, for example, 80 ° C. or higher. If there are a plurality of exothermic peaks on the DSC curve, the position of the peak with the largest calorific value is defined as the exothermic peak position.

The oxide solid electrolyte of the present disclosure preferably has a calorific value of 5 J / g or more at the exothermic peak of 200 ° C. or lower obtained in the DSC curve. When the calorific value of the exothermic peak of 200 ° C. or lower obtained in the DSC curve is in the above range, higher deformability can be obtained, which is preferable. A more preferable calorific value is 10 J / g or more. A more preferable calorific value is 15 J / g or more. The upper limit of the calorific value of the exothermic peak is not particularly limited, but may be, for example, 500 J / g or less.

The exothermic peak of the oxide solid electrolyte of the present disclosure can be measured by, for example, the following method. In a glove box filled with an inert gas (for example, Ar), an oxide solid electrolyte (about 10 mg) is placed in an Al sealed sample container (GCA-0017 manufactured by Hitachi High-Tech Science Co., Ltd.) and sealed. By installing the sealed container on a differential scanning calorimeter (for example, DSC6200 manufactured by Seiko Instruments) and measuring at a temperature range of 50 ° C to 300 ° C and a temperature rise rate of 10 ° C / min, the DSC of the oxide solid electrolyte is measured. You can get a curve. From the obtained DSC curve, the position of the exothermic peak and the calorific value of the oxide solid electrolyte can be obtained. The peak position and calorific value can be calculated using, for example, the software attached to the differential scanning calorimeter DSC6200.

(Conductivity is 1.0 x ^10-7 S / cm or more)
The conductivity of the oxide solid electrolyte of the present disclosure is 1.0 × 10 ^-7 S / cm or more. If the conductivity of the oxide solid electrolyte is less than 1.0 × 10 ^-7 S / cm, the characteristics of the all-solid-state lithium-ion battery may deteriorate. The conductivity of the more preferable solid oxide electrolyte is 2.0 × 10 ^-7 S / cm or more. A more preferable conductivity of the oxide solid electrolyte is 4.0 × 10 ^-7 S / cm or more.

The conductivity of the oxide solid electrolyte of the present disclosure can be measured by, for example, the following method. In an argon gas atmosphere glove box, put Al foil or Au foil punched to a diameter of 10 mm in a tablet molder with a diameter of 10 mm (for example, manufactured by Nippon Kogaku), put solid electrolyte powder on it, smooth it, and then add more. An Al foil or Au foil punched to a diameter of 10 mm is put in and pressed at room temperature at 1 GPa for 30 minutes to obtain pellets for measuring a solid electrolyte. The obtained pellets are placed in a flat cell and sealed to form a cell for conductivity measurement. At room temperature, an impedance measuring device (for example, Solartron Impedance Analyzer A1260) applies a voltage of 50 mV and a measurement frequency of 1 Hz to 32 MHz. The conductivity can be calculated from the resistance value at the low frequency end of the semi-arc of the obtained Nyquist plot.

(Relative density 95% or more)
The oxide solid electrolyte of the present disclosure is excellent in deformability at room temperature. For example, when the oxide solid electrolyte of the present disclosure is pressed at room temperature at 1 GPa, the relative density represented by the following formula (1) becomes 95% or more. More preferably, the relative density when pressed at 1 GPa at room temperature is 98% or more. More preferably, the relative density when pressed at 1 GPa at room temperature is 99% or more.

The relative density of the oxide solid electrolyte of the present disclosure can be measured by the following method. In an argon gas atmosphere glove box, put Al foil or Au foil punched to a diameter of 10 mm in a tablet molder with a diameter of 10 mm (for example, manufactured by Nippon Kogaku), put solid electrolyte powder from above, and after leveling, further diameter. Al foil or Au foil punched to 10 mm is put in and pressed at room temperature at 1 GPa for 30 minutes to obtain pellets for relative density measurement. It can be calculated by dividing the density of the obtained pellets by the theoretical density calculated from the density (g / cm ³ ) and the mass (g) of each raw material as in the above equation (1).

The shape of the oxide solid electrolyte of the present disclosure is not particularly limited, but for example, granules are preferable.

(Manufacturing method of oxide solid electrolyte)
The method for producing the oxide solid electrolyte of the present disclosure is not particularly limited, and examples thereof include a solid phase synthesis method, a dry mechanical milling treatment, a wet mechanical milling treatment, a melt quenching method, and a sol-gel method. As a method for producing the oxide solid electrolyte of the present disclosure, a dry mechanical milling treatment is particularly preferable. For example, the oxide solid electrolyte of the present disclosure can be obtained by mixing the raw material of the oxide solid electrolyte with zirconia balls at 370 rpm for 60 hours. The production conditions can be appropriately adjusted by measuring the DSC of the obtained solid oxide electrolyte and confirming the position of the exothermic peak and the calorific value.

<Electrode mixture>
The electrode mixture of the present disclosure includes the oxide solid electrolyte, the electrode active material and the conductive material of the present disclosure. The electrode mixture will be described below.

(Active substance)
The electrode active material is not particularly limited as long as it is used in a lithium ion secondary battery. The electrode active material (positive electrode active material) used for the positive electrode is not particularly limited as long as it is a material capable of reversibly releasing and storing lithium ions and capable of electron transport. As a positive electrode active material. For example, lithium transition metal oxides such as lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, and lithium iron phosphorus oxide, and sulfur-based active materials such as sulfur and its discharge products, lithium sulfide and lithium polysulfide. And so on. The positive electrode active material may be composed of only one of the above materials, or may be composed of two or more of the above materials.

The electrode active material (negative electrode active material) used for the negative electrode is not particularly limited as long as it is a material capable of reversibly releasing and storing lithium ions and capable of electron transport. Examples of the negative electrode active material include carbonaceous materials such as natural graphite, artificial graphite, resin charcoal, carbon fiber, activated charcoal, hard carbon, and soft carbon; tin, tin alloy, silicon, silicon alloy, gallium, gallium alloy, indium, etc. Alloy-based materials mainly composed of indium alloys, aluminum, aluminum alloys, etc .; conductive polymers such as polyacene, polyacetylene, polypyrrole, etc .; metallic lithium: lithium titanium composite oxide (for example, Li ₄ Ti ₅ O ₁₂ ) and the like can be mentioned. The negative electrode active material may be composed of only one of the above materials, or may be composed of two or more of the above materials.

(Conductive material)
As the conductive material, a conductive auxiliary agent that can be generally used for a lithium ion secondary battery and an all-solid-state lithium ion secondary battery can be used. Examples of the conductive material (positive electrode conductive material) used for the positive electrode include carbon black such as acetylene black and kechen black; carbon fiber; vapor phase carbon fiber; graphite powder; carbon nanotube and carbon material such as activated charcoal. be able to. The conductive material may be composed of only one of the above materials, or may be composed of two or more of the above materials.

Examples of the conductive material (negative electrode conductive material) used for the negative electrode include carbon black such as acetylene black and kechen black; carbon fiber; vapor phase carbon fiber; graphite powder; carbon nanotube and carbon material such as activated charcoal. be able to. The conductive material may be composed of only one of the above materials, or may be composed of two or more of the above materials.

When the total mass of the oxide solid electrolyte, the electrode active material and the conductive material of the present disclosure is 100, the mass ratio of the oxide solid electrolyte of the present disclosure, the electrode active material and the conductive material (oxide solid electrolyte). : Electrode active material: Conductive material) is 20 to 80:20 to 80: 0 to 30. When the mass ratio of the oxide solid electrolyte of the present disclosure, the electrode active material, and the conductive material is in the above range, high battery characteristics can be obtained. When the oxide solid electrolyte of the present disclosure is used for the positive electrode (positive electrode mixture), the mass ratio of the oxide solid electrolyte: the positive electrode active material: the positive electrode conductive material is 20 to 80:20 to 80: 0 to 30. be. When the oxide solid electrolyte of the present disclosure is used for the negative electrode (negative electrode mixture), the mass ratio of the oxide solid electrolyte: the negative electrode active material: the negative electrode conductive material is 20 to 80:20 to 80: 0 to 30.

The content of the oxide solid electrolyte in the electrode mixture of the present disclosure is preferably 20% by mass to 80% by mass. Further, the content of the electrode active material in the electrode mixture of the present disclosure is preferably 20% by mass to 80% by mass. The content of the conductive material in the electrode mixture of the present disclosure is preferably 0% by mass to 30% by mass. The content of the more preferable conductive material is 0% by mass to 25% by mass. When the contents of the oxide solid electrolyte, the electrode active material, and the conductive material in the electrode mixture of the present disclosure are in the above ranges, good battery characteristics can be obtained. The total of the oxide solid electrolyte, the electrode active material, the conductive material and other components is 100% by mass. Examples of other components include binders and the like.

The electrode mixture of the present disclosure may further contain a binder. The binder is not particularly limited, but a thermoplastic resin, a thermosetting resin and the like can be used, and for example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyfluorovinylidene (PVDF), styrene butadiene rubber, tetra. Fluoroethylene-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 Polymers, ethylene-chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethylvinyl ether-tetrafluoroethylene copolymer, ethylene- Examples thereof include acrylic acid copolymers, polyacrylic acid, sodium polyacrylic acid, lithium polyacrylic acid, polymethacrylic acid, sodium polymethacrylate, and lithium polymethacrylate. These binders may be used alone or in combination of two or more.

The content of the binder in the electrode mixture of the present disclosure is preferably 0% by mass to 10% by mass. Within this range, the active material or the like can be retained while maintaining the conductivity of the electrode mixture. A more preferable binder content is 0% by mass to 5% by mass.

The ratio of each component in the electrode mixture is, for example, in the cross section of the positive electrode or the negative electrode of the lithium ion secondary battery, the energy dispersion type X-ray spectrometer (EDX) mounted on the electrolytic emission type transmission electron microscope (TEM) and Raman. It can be quantified by spectroscopy and combustion decomposition method.

(Manufacturing method of electrode mixture)
The method for producing the electrode mixture of the present disclosure is not particularly limited as long as the oxide solid electrolyte, the electrode active material and the conductive material are uniformly mixed. Examples of the method for producing the electrode mixture of the present disclosure include a dry mechanical milling treatment, a wet mechanical milling treatment, and a melt quenching method.

<All-solid-state lithium-ion battery>
Next, with reference to FIG. 1, the all-solid-state lithium-ion battery 100 according to the embodiment of the present disclosure will be described. The all-solid-state lithium-ion battery 100 includes a solid electrolyte layer 11, a positive electrode mixture layer 12, a negative electrode mixture layer 13, a positive electrode current collector 14, and a negative electrode current collector 15. The all-solid-state lithium-ion battery 100 includes the oxide solid electrolyte of the present disclosure. That is, the all-solid lithium-ion battery 100 contains the oxide solid electrolyte of the present disclosure in at least one of the solid electrolyte layer 11, the positive electrode active material layer 12, and the positive electrode active material layer 12. Hereinafter, each part will be described.

(Solid electrolyte layer)
The solid electrolyte layer 11 is a layer formed between the positive electrode active material layer 12 and the negative electrode active material layer 13. The solid electrolyte layer 11 contains a solid electrolyte. As the solid electrolyte contained in the solid electrolyte layer 11, a solid electrolyte other than the oxide solid electrolyte of the present disclosure may be used. Examples of the solid electrolyte other than the oxide solid electrolyte of the present disclosure include lithium aluminum titanium phosphorus oxide (LATP), lithium aluminum germanium phosphorus oxide (LAGP), lithium lanthanum zirconium oxide (LLZ) and the like. These solid electrolytes may be used alone or in admixture of two or more, or may be combined with the oxide solid electrolytes of the present disclosure. The thickness of the solid electrolyte layer 11 can be appropriately selected. The thickness of the solid electrolyte layer 11 is preferably 200 μm or less, for example.

The lithium ion conductivity of the solid electrolyte other than the oxide solid electrolyte of the present disclosure is preferably 1.0 × 10 ^-5 S / cm or more, more preferably 1.0 × 10 ^-4 S / cm or more. be. Within this range, the battery characteristics of the all-solid-state lithium-ion battery 100 are further improved.

The solid electrolyte layer 11 may further contain a binder. The binder is not particularly limited, but a thermoplastic resin, a thermosetting resin and the like can be used, and for example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyfluorovinylidene (PVDF), styrene butadiene rubber, tetra. Fluoroethylene-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 Polymers, ethylene-chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethylvinyl ether-tetrafluoroethylene copolymer, ethylene- Examples thereof include acrylic acid copolymers, polyacrylic acid, sodium polyacrylic acid, lithium polyacrylic acid, polymethacrylic acid, sodium polymethacrylate, and lithium polymethacrylate. These binders may be used alone or in combination of two or more.

The content of the binder in the solid electrolyte layer 11 of the present disclosure is preferably 0% by mass to 10% by mass. Within this range, the solid electrolyte and the like can be retained while maintaining the conductivity of the electrode mixture. A more preferable binder content is 0% by mass to 5% by mass.

(Positive electrode active material layer)
The positive electrode active material layer 12 is formed on the positive electrode current collector 14. The positive electrode active material layer 12 contains a solid electrolyte, an electrode active material, and a conductive material. Hereinafter, the positive electrode active material layer 12 will be described. Further, the thickness of the positive electrode active material layer 12 can be appropriately selected. The thickness of the positive electrode active material layer 12 is preferably 200 μm or less, for example.

(Solid electrolyte)
As the solid electrolyte contained in the positive electrode active material layer 12, the oxide solid electrolyte of the present disclosure may be contained, or a solid electrolyte other than the oxide solid electrolyte of the present disclosure may be contained. Examples of the solid electrolyte other than the oxide solid electrolyte of the present disclosure include lithium aluminum titanium phosphorus oxide (LATP), lithium aluminum germanium phosphorus oxide (LAGP), lithium lanthanum zirconium oxide (LLZ) and the like. The solid electrolyte other than the above-mentioned oxide solid electrolyte of the present disclosure may be used alone or in combination of two or more, or may be combined with the oxide solid electrolyte of the present disclosure.

The lithium ion conductivity of the solid electrolyte other than the oxide solid electrolyte of the present disclosure is preferably 1.0 × 10 ^-5 S / cm or more, more preferably 1.0 × 10 ^-4 S / cm or more. be. Within this range, the battery characteristics of the all-solid-state lithium-ion battery 100 are further improved.

(Positive electrode active material)
The electrode active material (positive electrode active material) used for the positive electrode is not particularly limited as long as it is a material capable of reversibly releasing and storing lithium ions and capable of electron transport. As a positive electrode active material. For example, lithium transition metal oxides such as lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, and lithium iron phosphorus oxide, and sulfur-based active materials such as sulfur and its discharge products, lithium sulfide and lithium polysulfide. And so on. The positive electrode active material may be composed of only one of the above materials, or may be composed of two or more of the above materials.

(Positive electrode conductive material)
As the positive electrode conductive material, a conductive auxiliary agent that can be generally used for a lithium ion secondary battery and an all-solid-state lithium ion secondary battery can be used. Examples of the positive electrode conductive material include carbon black such as acetylene black and kechen black; carbon fiber; vapor phase carbon fiber; graphite powder; carbon nanotube and carbon material such as activated charcoal. The conductive material may be composed of only one of the above materials, or may be composed of two or more of the above materials.

(Mass ratio of oxide solid electrolyte, positive electrode active material, and positive electrode conductive material: 20 to 80:20 to 80: 0 to 30)
When the positive electrode active material layer 12 contains the oxide solid electrolyte of the present disclosure, the oxide solid electrolyte of the present disclosure is used when the total mass of the oxide solid electrolyte, the positive electrode active material, and the positive electrode conductive material is 100. The mass ratio of the positive electrode active material and the positive electrode conductive material (oxide solid electrolyte: positive electrode active material: positive electrode conductive material) is preferably 20 to 80:20 to 80: 0 to 30. If the mass ratio of the oxide solid electrolyte of the present disclosure, the positive electrode active material, and the positive electrode conductive material is in the above range, higher battery characteristics can be obtained.

The content of the oxide solid electrolyte in the positive electrode active material layer 12 is preferably 20% by mass to 80% by mass. Further, the content of the positive electrode active material in the positive electrode active material layer 12 is preferably 20% by mass to 80% by mass. The content of the positive electrode conductive material in the positive electrode active material layer 12 is preferably 0% by mass to 30% by mass. The content of the positive electrode conductive material is more preferably 0% by mass to 25% by mass. When the contents of the oxide solid electrolyte, the positive electrode active material, and the positive electrode conductive material in the positive electrode active material layer 12 are in the above range, better battery characteristics can be obtained. The total of the oxide solid electrolyte, the positive electrode active material, the positive electrode conductive material and other components is 100% by mass. Examples of other components include binders and the like.

The positive electrode active material layer 12 may further contain the binder used in the electrode mixture of the present disclosure.

(Negative electrode active material layer)
The negative electrode active material layer 13 is formed on the negative electrode current collector 15. The negative electrode active material layer 13 contains a solid electrolyte, a negative electrode active material, and a negative electrode conductive material. Hereinafter, the negative electrode active material layer 13 will be described. Further, the thickness of the negative electrode active material layer 13 can be appropriately selected. The thickness of the negative electrode active material layer 13 is preferably 200 μm or less, for example.

(Solid electrolyte)
As the solid electrolyte contained in the negative electrode active material layer 13, the oxide solid electrolyte of the present disclosure may be contained, or a solid electrolyte other than the oxide solid electrolyte of the present disclosure may be contained. Examples of the solid electrolyte other than the oxide solid electrolyte of the present disclosure include lithium aluminum titanium phosphorus oxide (LATP), lithium aluminum germanium phosphorus oxide (LAGP), lithium lanthanum zirconium oxide (LLZ) and the like. The solid electrolyte other than the above-mentioned oxide solid electrolyte of the present disclosure may be used alone or in combination of two or more, or may be combined with the oxide solid electrolyte of the present disclosure.

The lithium ion conductivity of the solid electrolyte other than the oxide solid electrolyte of the present disclosure is preferably 1.0 × 10 ^-5 S / cm or more, more preferably 1.0 × 10 ^-4 S / cm or more. be. Within this range, the battery characteristics of the all-solid-state lithium-ion battery 100 are further improved.

(Negative electrode active material)
The negative electrode active material is not particularly limited as long as it can reversibly release and occlude lithium ions and can transport electrons. Examples of the negative electrode active material include carbonaceous materials such as natural graphite, artificial graphite, resin charcoal, carbon fiber, activated charcoal, hard carbon, and soft carbon; tin, tin alloy, silicon, silicon alloy, gallium, gallium alloy, indium, etc. Alloy-based materials mainly composed of indium alloys, aluminum, aluminum alloys, etc .; conductive polymers such as polyacene, polyacetylene, polypyrrole, etc .; metallic lithium: lithium titanium composite oxide (for example, Li ₄ Ti ₅ O ₁₂ ) and the like can be mentioned. The negative electrode active material may be composed of only one of the above materials, or may be composed of two or more of the above materials.

(Negative electrode conductive material)
As the negative electrode conductive material, a conductive auxiliary agent that can be generally used for a lithium ion secondary battery and an all-solid-state lithium ion secondary battery can be used. Examples of the positive electrode conductive material include carbon black such as acetylene black and kechen black; carbon fiber; vapor phase carbon fiber; graphite powder; carbon nanotube and carbon material such as activated charcoal. The conductive material may be composed of only one of the above materials, or may be composed of two or more of the above materials.

(Mass ratio of oxide solid electrolyte, negative electrode active material, and negative electrode conductive material: 20 to 80:20 to 80: 0 to 30)
When the negative electrode active material layer 13 contains the oxide solid electrolyte of the present disclosure, the oxide solid electrolyte of the present disclosure is used when the total mass of the oxide solid electrolyte, the negative electrode active material, and the negative electrode conductive material is 100. The mass ratio of the negative electrode active material and the negative electrode conductive material (oxide solid electrolyte: negative electrode active material: negative electrode conductive material) is 20 to 80:20 to 80: 0 to 30. If the mass ratio of the oxide solid electrolyte of the present disclosure, the negative electrode active material, and the negative electrode conductive material is in the above range, higher battery characteristics can be obtained.

The content of the oxide solid electrolyte in the negative electrode active material layer 13 is preferably 20% by mass to 80% by mass. Further, the content of the negative electrode active material in the negative electrode active material layer 13 is preferably 20% by mass to 80% by mass. The content of the negative electrode conductive material in the negative electrode active material layer 13 is preferably 0% by mass to 30% by mass. A more preferable content of the negative electrode conductive material is 0% by mass to 25% by mass. When the contents of the oxide solid electrolyte, the negative electrode active material, and the negative electrode conductive material in the negative electrode active material layer 13 are in the above range, better battery characteristics can be obtained. The total of the oxide solid electrolyte, the negative electrode active material, the negative electrode conductive material and other components is 100% by mass. Examples of other components include binders and the like.

The negative electrode active material layer 13 may further contain the binder used in the electrode mixture of the present disclosure.

(Positive current collector)
The positive electrode current collector 14 is provided so as to be in contact with the positive electrode active material layer 12. The presence of the positive electrode current collector 14 facilitates the extraction of electricity from the positive electrode active material layer 12. As the positive electrode current collector 14, a known positive electrode current collector can be used, and examples thereof include Al and SUS. Further, the thickness and shape of the positive electrode current collector 14 can be appropriately selected.

(Negative electrode current collector)
The negative electrode current collector 15 is provided so as to be in contact with the negative electrode active material layer 13. The presence of the negative electrode current collector 15 facilitates the extraction of electricity from the negative electrode active material layer 13. As the negative electrode current collector 15, a known negative electrode current collector can be used, and examples thereof include Cu. If the negative electrode active material layer 13 has high electron conductivity, the negative electrode current collector 15 may not be provided. Further, the thickness and shape of the negative electrode current collector 15 can be appropriately selected.

The all-solid-state lithium-ion battery 100 can be manufactured by a known method.

In addition, it is possible to replace the constituent elements in the embodiment with well-known constituent elements as appropriate without departing from the spirit of the present invention, and the above-mentioned modified examples may be appropriately combined. In the above embodiment, the positive electrode current collector 14 is provided, but if the electron conductivity of the positive electrode active material layer 12 is high, the positive electrode current collector 14 may not be provided. Further, in the above embodiment, the negative electrode current collector 15 is provided, but if the negative electrode active material layer 13 has high electron conductivity, the negative electrode current collector 15 may not be provided.

Next, an example of the present invention will be described. The conditions in the examples are one condition example adopted for confirming the feasibility and effect of the present invention, and the present invention is based on this one condition example. Not limited. The present invention can adopt various conditions as long as the gist of the present invention is not deviated and the object of the present invention is achieved.

(Example 1)
Lithium sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) and lithium carbonate (manufactured by Rare Metallic) were weighed at 543 mg of lithium sulfate and 157 mg of lithium carbonate so as to have a molar ratio of 70:30. Example 1 by using a planetary ball mill (Premium Line P-7 manufactured by Frilsch), weighing lithium sulfate and lithium carbonate are placed in an 80 ml pot together with about 120 g of 5 mm zirconia balls and mixed at a revolution speed of 370 rpm for 60 hours. Oxide solid electrolyte was obtained.

(Example 2)
After weighing 828 mg of lithium sulfate and 372 mg of lithium carbonate so that the molar ratio of lithium sulfate and lithium carbonate is 60:40, they are mixed under the same conditions as in Example 1 to obtain the oxide solid electrolyte of Example 2. rice field.

(Example 3)
Lithium sulfate and lithium carbonate were weighed at 359 mg of lithium sulfate and 241 mg of lithium carbonate so that the molar ratio was 50:50, and then mixed under the same conditions as in Example 1 to obtain the oxide solid electrolyte of Example 3. rice field.

(Example 4)
After weighing 299 mg of lithium sulfate and 301 mg of lithium carbonate so that the molar ratio of lithium sulfate and lithium carbonate was 40:60, they were mixed under the same conditions as in Example 1 to obtain the oxide solid electrolyte of Example 4. ..

(Example 5)
After weighing 273 mg of lithium sulfate and 427 mg of lithium carbonate so that the molar ratio of lithium sulfate and lithium carbonate was 30:70, they were mixed under the same conditions as in Example 1 to obtain the oxide solid electrolyte of Example 5. ..

(Example 6)
Lithium sulfate, lithium carbonate, and lithium iodide (manufactured by Sigma Aldrich) were weighed with 717 mg of lithium sulfate, 321 mg of lithium carbonate, and 162 mg of lithium iodide so that the molar ratio was 54:36:10. Mixing was performed under the same conditions to obtain the oxide solid electrolyte of Example 6.

(Example 7)
Lithium sulfate, lithium carbonate, and lithium iodide were weighed at 614 mg of lithium sulfate, 275 mg of lithium carbonate, and 311 mg of lithium iodide so as to have a molar ratio of 48:32:20, and then mixed under the same conditions as in Example 1. The oxide solid electrolyte of Example 7 was obtained.

(Example 8)
Lithium sulfate, lithium carbonate, and lithium iodide were weighed at 518 mg of lithium sulfate, 232 mg of lithium carbonate, and 450 mg of lithium iodide so as to have a molar ratio of 42:28:30, and then mixed under the same conditions as in Example 1. The oxide solid electrolyte of Example 8 was obtained.

(Example 9)
Lithium sulfate, lithium carbonate, and lithium iodide were weighed at 428 mg of lithium sulfate, 192 mg of lithium carbonate, and 280 mg of lithium iodide so as to have a molar ratio of 36:24:40, and then mixed under the same conditions as in Example 1. The oxide solid electrolyte of Example 9 was obtained.

(Example 10)
Lithium sulfate, lithium carbonate, and lithium iodide were weighed at 345 mg of lithium sulfate, 155 mg of lithium carbonate, and 700 mg of lithium iodide so as to have a molar ratio of 30:20:50, and then mixed under the same conditions as in Example 1. The oxide solid electrolyte of Example 10 was obtained.

(Example 11)
Lithium sulfate, lithium carbonate, and lithium chloride (manufactured by Sigma Aldrich) were weighed with 746 mg of lithium sulfate, 334 mg of lithium carbonate, and 120 mg of lithium chloride so as to have a molar ratio of 48:32:20, and then the same conditions as in Example 1. To obtain the oxide solid electrolyte of Example 11.

(Example 12)
Lithium sulfate, lithium carbonate, and lithium chloride were weighed at 722 mg of lithium sulfate, 323 mg of lithium carbonate, and 155 mg of lithium chloride so as to have a molar ratio of 45:30:25, and then mixed under the same conditions as in Example 1 to Example. Twelve oxide solid electrolytes were obtained.

(Example 13)
Lithium sulfate, lithium carbonate, and lithium chloride were weighed at 696 mg of lithium sulfate, 312 mg of lithium carbonate, and 192 mg of lithium chloride so as to have a molar ratio of 42:28:30, and then mixed under the same conditions as in Example 1 to Example. Thirteen oxide solid electrolytes were obtained.

(Example 14)
Lithium sulfate, lithium carbonate, and lithium chloride were weighed at 639 mg of lithium sulfate, 287 mg of lithium carbonate, and 274 mg of lithium chloride so as to have a molar ratio of 36:24:40, and then mixed under the same conditions as in Example 1 to Example. 14 oxide solid electrolytes were obtained.

(Example 15)
Lithium sulfate, lithium carbonate, and lithium bromide (manufactured by Sigma Aldrich) were weighed at 338 mg of lithium sulfate, 151 mg of lithium carbonate, and 111 mg of lithium bromide so as to have a molar ratio of 48:32:20, and then the same as in Example 1. The mixture was mixed under the conditions of (1) to obtain the oxide solid electrolyte of Example 15.

(Example 16)
Lithium sulfate, lithium carbonate, and lithium bromide were weighed at 636 mg of lithium sulfate, 285 mg of lithium carbonate, and 279 mg of lithium bromide so as to have a molar ratio of 45:30:25, and then mixed under the same conditions as in Example 1. The oxide solid electrolyte of Example 16 was obtained.

(Example 17)
Lithium sulfate, lithium carbonate, and lithium bromide were weighed at 596 mg of lithium sulfate, 267 mg of lithium carbonate, and 336 mg of lithium bromide so as to have a molar ratio of 42:28:30, and then mixed under the same conditions as in Example 1 to carry out. The oxide solid electrolyte of Example 17 was obtained.

(Example 18)
Lithium sulfate, lithium carbonate, and lithium bromide were weighed at 258 mg of lithium sulfate, 116 mg of lithium carbonate, and 226 mg of lithium bromide so as to have a molar ratio of 36:24:40, and then mixed under the same conditions as in Example 1. The oxide solid electrolyte of Example 18 was obtained.

(Example 19)
Lithium sulfate, lithium carbonate, and lithium phosphate (manufactured by Sigma Aldrich) were weighed at 530 mg of lithium sulfate, 237 mg of lithium carbonate, and 233 mg of lithium bromide so as to have a molar ratio of 48:32:20, and then the same as in Example 1. The mixture was mixed under the conditions of (1) to obtain the oxide solid electrolyte of Example 19.

(Example 20)
Lithium sulfate, lithium carbonate, and lithium nitrate (manufactured by Sigma Aldrich) were weighed at 585 mg of lithium sulfate, 262 mg of lithium carbonate, and 153 mg of lithium bromide so as to have a molar ratio of 48:32:20, and then the same as in Example 1. The mixture was mixed under the conditions to obtain the oxide solid electrolyte of Example 20.

(Comparative Example 1)
After weighing 1040 mg of lithium borate and 160 mg of lithium sulfate so that lithium borate (manufactured by Toyoshima Seisakusho Co., Ltd.) and lithium sulfate have a molar ratio of 90:10, they are mixed under the same conditions as in Example 1 and compared with Comparative Example 1. A solid electrolyte was obtained.

(Comparative Example 2)
The solid electrolyte of Comparative Example 1 was heat-treated at 285 ° C. for 1 hour in an argon atmosphere to obtain the solid electrolyte of Comparative Example 2.

(Positive electrode mixture 1)
As the positive electrode active material, 60 mg of lithium nickel cobalt manganese oxide (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , manufactured by BASF Toda Battery Materials Co., Ltd.) and 40 mg of the oxide solid electrolyte of Example 2 were weighed and menowed. By mixing in a dairy pot, a powdery positive electrode mixture 1 was obtained.

(Positive electrode mixture 2)
A powdery positive electrode mixture 2 was obtained by weighing and mixing in the same manner as in the positive electrode mixture 1 except that the oxide solid electrolyte of Example 13 was used instead of the oxide solid electrolyte of Example 2.

(Positive electrode mixture 3)
As the positive electrode active material, 60 mg of lithium sulfide (manufactured by Mitsuwa Chemical Co., Ltd.), 120 mg of the oxide solid electrolyte of Example 13, and 20 mg of activated carbon (MSC-30) were weighed. Using a planetary ball mill (Premium Line P-7 manufactured by Frillsch), lithium sulfide weighed together with about 40 g of 5 mm zirconia balls, the oxide solid electrolyte of Example 13, and activated carbon were placed in a 45 ml pot, and the revolution speed was 370 rpm for 2 hours. By mixing, a powdery positive electrode mixture 3 was obtained.

(Positive electrode mixture 4)
Weighing and mixing under the same conditions as for the positive electrode mixture 3 except that the oxide solid electrolyte of Example 16 was used instead of the oxide solid electrolyte of Example 13, a powdery positive electrode mixture 4 was obtained. ..

(Positive electrode mixture 5)
As the positive electrode active material, 60 mg of lithium sulfide, 60 mg of the oxide solid electrolyte of Example 13, and 20 mg of activated carbon (MSC-30) were weighed. Using a planetary ball mill (Premium Line P-7 manufactured by Frillsch), lithium sulfide weighed together with about 40 g of 5 mm zirconia balls, the oxide solid electrolyte of Example 13, and activated carbon were placed in a 45 ml pot, and the revolution speed was 370 rpm for 2 hours. Mixed. The obtained powder and the solid electrolyte of Example 13 were weighed so as to have a mass ratio of 70:30, and mixed in a mortar to obtain a powdery positive electrode mixture 5.

(Positive electrode mixture 6)
Weighing and mixing under the same conditions as for the positive electrode mixture 5 except that the oxide solid electrolyte of Example 16 was used instead of the oxide solid electrolyte of Example 13, a powdery positive electrode mixture 6 was obtained. ..

(Comparative positive electrode mixture 1)
A comparative positive electrode mixture 1 was obtained by weighing and mixing in the same manner as in the positive electrode mixture 1 except that the solid electrolyte of Comparative Example 2 was used instead of the oxide solid electrolyte of Example 2.

(Comparative positive electrode mixture 2)
Lithium aluminum germanium phosphorus oxide (LAGP, manufactured by Toyoshima Seisakusho Co., Ltd.) was used as the oxide solid electrolyte in place of the solid electrolyte of Example 2, and the mixture was weighed and mixed in the same manner as in the positive electrode mixture 1 to form a powder. Comparative positive electrode mixture 2 was obtained.

(Comparative positive electrode mixture 3)
Lithium aluminum titanium phosphorus oxide (LATP, manufactured by Toyoshima Seisakusho Co., Ltd.) was used as the oxide solid electrolyte in place of the solid electrolyte of Example 2, and the mixture was weighed and mixed in the same manner as in the positive electrode mixture 1 to form a powder. Comparative positive electrode mixture 3 was obtained.

(Negative electrode mixture 1)
Weigh 50 mg of lithium titanium oxide (Li ₄ Ti ₅ O ₁₂ (LTO), manufactured by Ishihara Sangyo Co., Ltd.) and 50 mg of the oxide solid electrolyte of Example 2 as the negative electrode active material, and mix them in a Menou dairy pot to form a powdered negative electrode. Combined material 1 was obtained.

(Negative electrode mixture 2)
The powdery negative electrode mixture 2 was obtained by mixing in a Menou dairy pot under the same conditions as the negative electrode mixture 1 except that 50 mg of the oxide solid electrolyte of Example 8 was weighed instead of the oxide solid electrolyte of Example 2. Obtained.

(Negative electrode mixture 3)
As the negative electrode active material, 50 mg of graphite (manufactured by Wako Pure Chemical Industries, Ltd.) and 50 mg of the oxide solid electrolyte of Example 13 were weighed and mixed in an agate mortar to obtain a powdery negative electrode mixture 3.

(Negative electrode mixture 4)
As the negative electrode active material, 50 mg of silicon (manufactured by Nikola Co., Ltd.) and 50 mg of the oxide solid electrolyte of Example 13 were weighed and mixed in an agate mortar to obtain a powdery negative electrode mixture 4.

(Negative electrode mixture 5)
A powdery negative electrode mixture 5 was obtained by weighing and mixing in the same manner as the positive electrode mixture 3 except that silicon was used as the negative electrode active material instead of lithium sulfide as the positive electrode active material.

(Negative electrode mixture 6)
A powdery negative electrode mixture 6 was obtained by weighing and mixing in the same manner as the positive electrode mixture 5 except that silicon was used as the negative electrode active material instead of lithium sulfide as the positive electrode active material.

(Battery manufacturing method-1)
In an argon gas atmosphere glove box, put an Al foil or Cu foil punched to a diameter of 10 mm in a tablet molder (JASCO Corporation) with a diameter of 10 mm, put a positive electrode mixture or a negative electrode mixture from above, and apply a predetermined pressure. A positive electrode was produced by pressing. Next, the obtained electrode was placed on a SUS plate with a diameter of 15.5 mm, a polyethylene oxide-based polymer solid electrolyte membrane containing a lithium salt was pasted on it, and Li metal punched to φ12 mm as a counter electrode from above. The foil (thickness 0.2 mm) is placed on the opposite side of the positive electrode. This was sealed to make an evaluation battery. In the evaluation of the positive electrode mixture, Al foil was used, and in the evaluation of the negative electrode mixture, Al foil was used when LTO was contained, and Cu foil was used in the case of graphite and silicon.

(Battery manufacturing method-2)
In the argon gas atmosphere glove box, a cylindrical jig made of SKD11 (10 mmΦ, height 10 mm) as a negative current collector from the lower side of a ceramic cylindrical tube jig (inner diameter 10 mmΦ, outer diameter 23 mmΦ, height 20 mm). The composite product 1 and 80Li ₂ S-20P ₂ S ₅ in which the solid electrolyte (E) (5Li ₂ S-GeS ₂ -P ₂ S ₅ ) was fired at 510 ° C. for 8 hours from the upper side of the ceramic cylindrical tube jig. Was mixed with a ball mill at 500 rpm for 10 hours at a mass ratio of 90:10, and 80 mg of the mixed composite was added. Further, by inserting a cylindrical jig (10 mmΦ, height 15 mm) made of SKD11 as a positive electrode current collector from above the cylindrical tube jig made of ceramics, sandwiching the solid electrolyte (E), and pressing at a pressure of 80 MPa for 3 minutes. A solid electrolyte layer having a diameter of 10 mmΦ and a thickness of about 0.6 mm was formed. Next, once the SKD11 cylindrical jig (positive electrode current collector) inserted from the upper side is pulled out, the prepared positive electrode mixture or negative electrode mixture is put on the solid electrolyte layer in the ceramic cylindrical tube, and again from the upper side. A cylindrical jig (positive electrode current collector) made of SKD11 was inserted and pressed at a pressure of 720 MPa for 3 minutes to form a positive electrode layer having a diameter of 10 mmΦ and a thickness of about 0.1 mm. Next, the SKD11 cylindrical jig (negative electrode current collector) inserted from the bottom was pulled out, and a 0.20 mm thick lithium sheet (manufactured by Honjo Metal Co., Ltd.) was punched to a diameter of 8 mmΦ with a punch. And a 0.3 mm thick indium sheet (manufactured by Furuuchi Kagaku Co., Ltd.) punched out to a diameter of 9 mmΦ with a punch, put it in from the bottom of the ceramic cylindrical tube jig, and again from the bottom of the SKD11 cylinder. A jig (negative electrode current collector) was inserted and pressed at a pressure of 80 MPa for 3 minutes to form a lithium-indium alloy negative electrode. As described above, an all-solid-state lithium-ion battery in which a negative electrode current collector, a lithium-indium alloy negative electrode layer, a solid electrolyte layer, a positive electrode layer, and a positive electrode current collector are laminated in this order from the bottom was produced. This was sealed to make an evaluation battery.

(Full cell 1)
In an argon gas atmosphere glove box, put an Al foil punched to a diameter of 10 mm into a tablet molder (Nippon Kogaku) with a diameter of 10 mm, put the powder of the positive electrode mixture 1 from above, and press for 400 MPa to form a positive electrode layer. A solid electrolyte powder (a mixture of the solid electrolyte of Comparative Example 2 and the solid electrolyte of Example 3 in a dairy pot at a mass ratio of 75:25) is placed therein and pressed at 400 MPa, and the negative electrode mixture 2 is further formed. And Al foil were put in and pressed by 1 GPa to prepare a full cell of a solid lithium ion battery in which three layers of a positive electrode layer-a solid electrolyte layer-a negative electrode layer were laminated. This was sealed to make an evaluation battery.

(Measurement of conductivity of solid electrolyte)
In the Ar gas atmosphere glove box, an Al foil or Au foil punched to a diameter of 10 mm is placed in a tablet molder (Nippon Kogaku) with a diameter of 10 mm, and solid electrolyte powder (Examples 1 to 20, Comparative Example 1) is placed on the Al foil or Au foil. 2) was added, and after leveling, Al foil or Au foil punched to a diameter of 10 mm was further added and pressed at 1 GPa for 30 minutes to obtain pellets for solid electrolyte measurement. This was placed in a flat cell manufactured by Hosen Co., Ltd. and sealed to make a cell for measuring conductivity. Next, at room temperature, an impedance measuring device (Solartron Impedance Analyzer A1260) was used to measure the applied voltage at an applied voltage of 100 mV and a measurement frequency of 1 Hz to 32 MHz. The rate was calculated. Table 1 summarizes the conductivity and relative density of each solid electrolyte.

(Calculation method of relative density)
It was calculated by the above formula (1) in which the density of the pellets for measuring the solid electrolyte obtained by the 1 GPa press was divided by the theoretical density calculated from the density of each raw material. Here, the densities (g / cm3) of each raw material are lithium sulfate 2.22, lithium carbonate 2.11, lithium iodide 4.08, lithium bromide 3.46, lithium chloride 2.07, and lithium borate, respectively. Calculated as 2.16, lithium phosphate 2.54, and lithium nitrate 2.38. The results are shown in Table 1. A relative density of 95% or more was regarded as acceptable.

(Peak temperature of heat generation of solid electrolyte)
The oxide solid electrolytes (about 10 mg) of Examples 1 to 20 and Comparative Examples 1 and 2 were placed in an Al sealed sample container (GCA-0017 manufactured by Hitachi High-Tech Science Co., Ltd.) in a glove box filled with Ar gas and sealed. .. By installing the sealed container on a differential scanning calorimeter (for example, DSC6200 manufactured by Seiko Instruments) and measuring at a temperature range of 50 ° C to 300 ° C and a heating rate of 10 ° C / min, the DSC of the oxide solid electrolyte is measured. I got a curve. From the obtained DSC curve, the position of the exothermic peak and the calorific value of the oxide solid electrolyte were obtained. The results are shown in Table 1.

(Evaluation of charge / discharge characteristics of positive electrode mixture and negative electrode mixture)
Using the positive electrode mixture 1 to 6 and the comparative positive electrode mixture 1 to 3, the evaluation battery manufactured by the battery manufacturing method 1 or 2 is charged and discharged (ACD-M01A, manufactured by Asuka Electronics Co., Ltd. or HJ1001SD8, Hokuto Denko Co., Ltd.). The initial discharge capacity or the initial charge capacity per electrode active material was measured by charging and discharging with a constant current. The results of the positive electrode mixture are shown in Table 2. In the case of evaluation of the negative electrode mixture, the negative electrode mixture 1 to 6 were used, and the evaluation battery produced by the battery manufacturing method 1 or 2 was used. Table 3 shows the measurement results of the negative electrode mixture. Here, as the charge / discharge characteristics, the discharge capacity was used for the positive electrode and the charge capacity was used for the negative electrode. For the batteries using the negative electrode mixture 5 and 6, the discharge capacity was set to 2500 mAh / g.

(Evaluation of full cell charge / discharge characteristics)
The full cell produced above was charged and discharged with a constant current using a charging / discharging device (ACD-M01A, manufactured by Asuka Electronics Co., Ltd. or HJ1001SD8, manufactured by Hokuto Denko Co., Ltd.), and the initial discharge capacity or the initial charge capacity per electrode active material was measured. Table 4 shows the evaluation results of full cells. Here, for the charge / discharge characteristics, the discharge capacity was used for the full cell.

As shown in Table 1, Examples 1 to 20 oxide solid electrolytes contain Li ₂ SO ₄ and Li ₂ CO ₃ , and the molar ratio of Li ₂ SO ₄ to Li ₂ CO ₃ is 20: 80 to 80 :. Since it was 20 and had an exothermic peak of 200 ° C. or lower in the DSC curve, the relative density of the pellets obtained by pressing at room temperature and 1 GPa was 95% or more. Further, the solid electrolytes of Examples 1 to 20 had a conductivity of 1.0 × 10 ^-7 S / cm or more.

On the other hand, the solid electrolytes of Comparative Examples 1 and 2 did not have an exothermic peak of 200 ° C. or lower in the DSC curve. Therefore, the relative density of the pellets obtained by pressing at room temperature and 1 GPa was less than 95%, and the deformability at room temperature was inferior.

As shown in Tables 2 to 4, the positive electrode mixture 1 to 6 using the oxide solid electrolyte of the examples had excellent battery characteristics as compared with the comparative positive electrode mixture 1 to 3. Similarly, the negative electrode mixture and the full cell using the oxide solid electrolyte of the example also had excellent battery characteristics.

By using the oxide solid electrolyte of the present disclosure as the positive electrode, the negative electrode, and the solid electrolyte layer of the all-solid lithium ion battery, the positive electrode, the negative electrode, the solid electrolyte layer, and the full cell, which show good battery characteristics, can be pressed only at room temperature. Can be produced with. Since electrodes and full cells can be formed by a very simple method, the oxide solid electrolyte of the present invention and the electrode mixture using the same are suitable materials for mass production, and therefore have high industrial applicability.

11 solid electrolyte layer, 12 positive electrode active material layer, 13 negative electrode active material layer, 14 positive electrode current collector, 15 negative electrode current collector, 100 all-solid-state lithium-ion battery

Claims (8)

1. A complex containing lithium sulfate (Li ₂ SO ₄ ) and lithium carbonate (Li ₂ CO ₃ ).
   The molar ratio of the lithium sulfate to the lithium carbonate (Li ₂ SO ₄ : Li ₂ CO ₃ ) is 20:80 to 80:20.
   In the curve obtained by differential scanning calorimetry, the position of the exothermic peak is 200 ° C or less.
   An oxide solid electrolyte having a conductivity of 1.0 × 10 ^-7 S / cm or more.
2. The first aspect of claim 1, further comprising at least one selected from the group consisting of lithium chloride, lithium bromide, lithium iodide, lithium borate, lithium phosphate, lithium nitrate, lithium silicate, and lithium aluminate. Oxide solid electrolyte.
3. The oxide solid electrolyte according to claim 1 or 2,
   Electrode active material and
   With conductive material
   Including
   The mass ratio of the oxide solid electrolyte, the electrode active material, and the conductive material (oxide solid electrolyte: electrode active material: conductive material) is 20 to 80:20 to 80: 0 to 30. Mixture.
4. An all-solid-state lithium-ion battery containing the oxide solid electrolyte according to claim 1 or 2.
5. The all-solid-state lithium-ion battery according to claim 4, further comprising a solid electrolyte layer containing the oxide solid electrolyte.
6. The all-solid lithium-ion battery according to claim 4 or 5, further comprising a positive electrode active material layer containing the oxide solid electrolyte or a negative electrode active material layer containing the oxide solid electrolyte.
7. The positive electrode active material layer contains the oxide solid electrolyte, the positive electrode active material, and the positive electrode conductive material, and the mass ratio of the oxide solid electrolyte, the positive electrode active material, and the positive electrode conductive material (oxide solid electrolyte). : The all-solid lithium ion battery according to claim 6, wherein the positive electrode active material (positive electrode conductive material) is 20 to 80: 20 to 80: 0 to 30.
8. The negative electrode active material layer contains the oxide solid electrolyte, the negative electrode active material, and the negative electrode conductive material, and the mass ratio of the oxide solid electrolyte, the negative electrode active material, and the negative electrode conductive material (oxide solid electrolyte). : The all-solid-state lithium ion battery according to claim 6 or 7, wherein the negative electrode active material: negative electrode conductive material) is 20 to 80:20 to 80: 0 to 30.

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