JP5096722B2 - Battery material manufacturing method and all solid state battery - Google Patents

Description

  The present invention relates to a method for producing a battery material comprising a lithium ion conductive solid electrolyte and an all-solid battery using the same.

In recent years, the demand for secondary batteries such as high-performance lithium batteries used in personal digital assistants, portable electronic devices, small household power storage devices, motorcycles powered by motors, electric vehicles, hybrid electric vehicles, etc. has increased. Yes.
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.

  Lithium ion conductive solid electrolytes are known to have high ionic conductivity (see, for example, Patent Document 1), and are used in all solid state batteries (all solid state secondary batteries) and the like. The lithium ion conductive solid electrolyte has a very low volatile content and high ionic conductivity immediately after being produced. However, the solid electrolyte is usually stored in a sheet form, a pellet form or a powder form for a certain period until it is used as a battery member. During this storage period, moisture in the air adheres to the surface of the solid electrolyte, and the ionic conductivity of the solid electrolyte decreases, and the performance of the solid battery manufactured using this decreases. There was a problem. Therefore, it is usually stored in an inert gas or dry air atmosphere.

JP-A-4-202024

However, even when the lithium ion conductive solid electrolyte is stored in an inert gas or dry air atmosphere, a slight amount of moisture, gas, and other volatiles present in the atmosphere adhere to the surface, and the solid electrolyte The present inventors have found that the battery performance is not improved because the ionic conductivity is lowered due to the surface change. In addition, the volatile matter includes components contained in the solid electrolyte immediately after the production of the solid electrolyte and components attached during storage, and as a result of qualitative analysis, such volatile matter includes H ₂ S, CS. _2. It was found that components such as water were included.

  The present invention has been made in view of the above-mentioned problems, and it has been found that by using a solid electrolyte dried just before use as a battery material, ionic conductivity can be improved and high battery performance can be expressed. The present invention has been completed.

  An object of the present invention is to provide a method for reducing the volatile content of a lithium ion conductive solid electrolyte, and an all-solid battery using a lithium ion conductive solid electrolyte having a reduced volatile content.

That is, this invention provides the manufacturing method of the following all-solid-state battery and battery material.
1. An all-solid battery in which the lithium ion conductive solid electrolyte layer has a volatile content of 50 g or less per kg of the solid electrolyte.
2. A method for producing a battery material, comprising heating and drying a lithium ion conductive solid electrolyte in a temperature range of 80 to 400 ° C. in an inert gas atmosphere.
3. 3. The method for producing a battery material according to 2 above, wherein the lithium ion conductive solid electrolyte is made from lithium sulfide and diphosphorus pentasulfide as raw materials.
4). 4. The method for producing a battery material according to 2 or 3 above, wherein the lithium ion conductive solid electrolyte is in a powder form.
5. 5. The method for producing a battery material according to any one of 2 to 4 above, wherein the battery material is a solid electrolyte layer forming material or an electrode material.

According to the present invention, it is possible to obtain an all-solid battery having high battery performance with high ion conductivity of the lithium ion conductive solid electrolyte layer.
According to the present invention, a battery material having high ion conductivity can be obtained.

Hereinafter, the present invention will be specifically described.
The present invention is characterized in that a lithium ion conductive solid electrolyte is heated and dried in an inert gas atmosphere at a temperature range of 80 to 400 ° C. to reduce the volatile content of the lithium ion conductive solid electrolyte.

(1) the substance constituting the lithium ion conductive solid electrolyte lithium ion conductive solid electrolyte may be an inorganic compound of sulfide-based, known ones can be used in lithium ion battery field.
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 (P ₂ S ₅ ), or lithium sulfide and simple phosphorus and simple sulfur, and further, lithium sulfide, diphosphorus pentasulfide, simple phosphorus and / or It is preferable to use a lithium ion conductive inorganic solid electrolyte produced from elemental sulfur.
The lithium ion conductive inorganic solid electrolyte can be produced from lithium sulfide and diphosphorus pentasulfide and / or simple phosphorus and simple sulfur. Specifically, it can be produced by melting these raw materials and then rapidly cooling them. Moreover, these raw materials can be obtained by processing by a mechanical milling method (MM method). The sulfide glass thus obtained may be heat-treated.

As lithium sulfide for producing a lithium ion conductive inorganic solid electrolyte, those commercially available without particular limitation can be used, but those having high purity are preferred.
Preferably, the lithium sulfide has a total content of at least a sulfur oxide lithium salt of 0.15% by mass or less, more preferably 0.1% by mass or less, and a content of lithium N-methylaminobutyrate of 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 solid electrolyte obtained by the melt quenching method or the mechanical milling method becomes 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 may be a crystallized product from the beginning, and the ionic conductivity of the crystallized product is low. Furthermore, even if this crystallized product is subjected to a 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, a deteriorated product of lithium N-methylaminobutyrate does not deteriorate the cycle performance of the lithium battery.
When lithium sulfide with reduced impurities is used, a high ion conductive electrolyte can be obtained.

The method for producing lithium sulfide used for producing the high ion conductive electrolyte is not particularly limited as long as it is a method that can reduce at least the impurities.
For example, it can 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 refinement | purification method of lithium sulfide. As a preferable purification method, for example, the method described in International Publication No. WO2005 / 40039 and the like can be mentioned.
Specifically, lithium sulfide 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 moreover, the aprotic organic solvent used for the production of lithium sulfide and the aprotic polar organic solvent used for washing are more preferably the same. preferable.

  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, and the like. 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 that is suitably used can be obtained.

P ₂ S ₅ can be used without particular limitation as long as it is industrially manufactured 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.

In the present invention, as the solid electrolyte to be dried by heating, both a glassy solid electrolyte and a solid electrolyte (glass ceramic) containing a crystal component can be used, and the type may be selected according to the required characteristics. Further, they may be used in combination.
The mixing molar ratio of lithium sulfide to diphosphorus pentasulfide and / 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).

  Examples of the method for producing a sulfide glass that is a glassy electrolyte include a melt quenching method and a mechanical milling method (MM method).

In the case of the melt quenching method, a predetermined amount of P ₂ S ₅ and Li ₂ S are mixed in a mortar, and the pellets are placed in a carbon-coated quartz tube and sealed in a vacuum. After reacting at a constant reaction temperature, the glass is put into ice and rapidly cooled to obtain a sulfide glass.
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 reactant is usually 10 ° C. or less, preferably 0 ° C. or less, and the cooling rate is usually about 1 to 10,000 K / sec, preferably 1 to 1000 K / sec.

In the case of the MM method, sulfide glass is obtained by mixing a predetermined amount of P ₂ S ₅ and Li ₂ S in a mortar and reacting them for a certain time by a mechanical milling method.
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 pulverization methods can be used for the MM method, 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.
For example, when a planetary ball mill is used, the rotational speed is set to several tens to several hundreds of revolutions / minute, and the treatment may be performed for 0.5 hours to 100 hours.

The electrolyte thus obtained is a glassy electrolyte, and immediately after production, the ionic conductivity is usually about 1.0 × 10 ^{−5 to} 8.0 × 10 ⁻⁴ (S / cm). .

  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.

Then, the obtained sulfide glass can be heat-treated to produce a solid electrolyte containing a crystal component.
The heat treatment temperature for producing the solid electrolyte containing the crystal component 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.

  The heat treatment time is preferably 3 to 240 hours, particularly preferably 4 to 230 hours, when the temperature is 190 ° C or higher and 220 ° C or lower. Moreover, in the case of the temperature higher than 220 degreeC and 340 degrees C or less, 0.1 to 240 hours are preferable, especially 0.2 to 235 hours are preferable, and also 0.3 to 230 hours are preferable. If the heat treatment time is shorter than 0.1 hour, a crystal having high ion conductivity may be difficult to obtain, and if it is longer than 240 hours, a crystal having low ion conductivity may be generated.

The lithium ion conductive inorganic solid electrolyte containing the crystal component thus obtained usually has an ionic conductivity of 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.

(2) Heat drying conditions of lithium ion conductive solid electrolyte Examples of the inert gas used include argon gas and nitrogen gas, and argon gas is preferred.

  The heating temperature is in the range of 80 to 400 ° C, preferably in the range of 100 to 300 ° C, more preferably in the range of 150 to 250 ° C. If the temperature is lower than 100 ° C, the attached volatile matter may not be sufficiently reduced. If the temperature exceeds 400 ° C, the performance may be deteriorated due to the modification of the solid electrolyte.

  The heat drying time is preferably in the range of 1 minute to 20 hours, and more preferably in the range of 10 minutes to 10 hours. If it is shorter than 1 minute, the attached volatile matter may be insufficiently reduced, and most of the volatile matter will be removed after 20 hours or more, so that no further effect can be expected.

The lithium ion conductive solid electrolyte after heating and drying is preferably used as a battery material immediately after drying, but if stored at 100 to 300 ° C. in an inert gas or dry air atmosphere, the storage time is not limited. There is little influence on the ionic conductivity of the solid electrolyte due to redeposition of moisture and the like.
Moreover, if the process as a battery material, that is, the process until it is assembled into an all-solid-state battery is carried out in the range of 100 to 300 ° C. in an inert gas atmosphere, the battery performance by reattachment of volatile components such as moisture There is almost no impact on. The process until it is assembled as an all-solid battery means a process until the positive electrode, the negative electrode, the solid electrolyte layer, and the current collector are integrated, preferably a process until the all-solid battery is sealed.

The volatile content of the lithium ion conductive solid electrolyte heat-dried under the above conditions is 50 g or less (5 wt% or less) per 1 kg of the solid electrolyte, preferably 3 g or less (3 wt% or less). When the volatile content exceeds 50 g per kg of the solid electrolyte, the ionic conductivity of the solid electrolyte is reduced to about 10 ⁻⁴ S / cm, and the rate characteristics and cycle characteristics of the battery manufactured using this are as follows. Performance is significantly inferior.
The volatile content of the lithium ion conductive solid electrolyte can be measured by the method described in the examples.

  In the present invention, the lithium ion conductive solid electrolyte to be heat-dried may be in any shape such as powder, pellet, sheet, etc., but the powder surface has the largest surface area. It is easy to reduce the volatile content such as moisture.

  According to the present invention, even a solid electrolyte layer or an electrode layer formed into a sheet shape or a pellet shape is inherently possessed by the solid electrolyte by heating and drying under the above conditions before assembling the battery. High ionic conductivity can be maintained, and a battery using the same can exhibit high performance.

  The lithium ion conductive solid electrolyte heated and dried under the above conditions can be used as a solid electrolyte layer of a solid battery or in a mixture with an electrode material. By using a solid electrolyte with a reduced volatile content, the high ion conductivity of the lithium ion conductive solid electrolyte can be sufficiently exhibited.

(3) All solid state battery
Because traditional is that is stored for a period of time from when manufactured, they had formed a solid electrolyte layer by using a lithium ion conductive solid electrolyte volatiles ion conductivity due to the adhesion of drops of slight moisture in the atmosphere, The all-solid-state battery manufactured using this was inferior in battery performance, such as a rate characteristic at the time of charging / discharging and a cycle characteristic.
On the other hand, a solid electrolyte layer formed using a lithium ion conductive solid electrolyte that has been stored for a certain period of time and dried by heating under the above conditions before being used as a battery material has a volatile content per kg of the solid electrolyte. Since it is reduced to 50 g or less, the all-solid-state battery manufactured using this can exhibit the above-mentioned outstanding battery performance.

  A basic configuration of the all solid state battery is shown in FIG. Hereinafter, each component and the manufacturing method of an all-solid-state battery are demonstrated.

(I) Manufacturing method of solid electrolyte layer In the all-solid-state battery of the present invention, a solution in which a powdered or pellet-shaped solid electrolyte is mixed with a solvent or a binder (such as a binder or a polymer compound) is applied and applied. Then, the solvent can be removed to form a film. Also, the solid electrolyte itself, solid electrolyte and binder (binder, polymer compound, etc.) and support (materials and compounds to reinforce the strength of the solid electrolyte layer and prevent short circuit of the solid electrolyte itself) are mixed -It is also possible to form a film by pressing the combined electrolyte under pressure.
In the present invention, a sheet-like solid electrolyte layer is formed using a powdered or pellet-shaped lithium ion conductive solid electrolyte, preferably a powdered solid electrolyte, which is dried by heating under the above-described conditions. Although it is preferable to form, a sheet-like solid electrolyte may be heat-dried on the said conditions.

(Ii) Current collector The material of the current collector used in the all solid state battery of the present invention is not particularly limited, and those used as current collector materials in the battery field can be used. Specific examples include a plate-like body or a foil-like body made of copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, indium, lithium, or an alloy thereof.

(Iii) Positive electrode material The positive electrode material used in the all solid state battery of the present invention is not particularly limited, and those used as a positive electrode active material in the battery field can be used. For example, as a sulfide-based positive electrode active material, titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), iron sulfide (FeS, FeS ₂ ), copper sulfide (CuS), nickel sulfide (Ni ₃ S ₂ ), etc. TiS ₂ is preferable.
Examples of the oxide-based positive electrode active material include bismuth oxide (Bi ₂ O ₃ ), bismuth lead acid (Bi ₂ Pb ₂ O ₅ ), copper oxide (CuO), vanadium oxide (V ₆ O ₁₃ ), and cobalt acid. Examples include lithium (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), and lithium manganate (LiMnO ₂ ). It is also possible to use a mixture of these. Of these, lithium cobaltate is preferred. In addition to the above, niobium selenide (NbSe ₃ ) can also be used.

(Iv) Negative electrode material The negative electrode material used in the all solid state battery of the present invention is not particularly limited, and those used as a negative electrode active material in the battery field can be used. Examples thereof include 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, Examples thereof include pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon. Alternatively, a mixture thereof may be used. Preferably, it is artificial graphite.
Also, an alloy in combination with a metal itself such as metallic lithium, metallic indium, metallic aluminum, metallic silicon, or another element or compound can be used as the negative electrode material.

(V) Ion conductive active material In the solid electrode material (electrode material) which is a member of an all-solid battery, in order to improve ion conductivity in addition to electronic conductivity, the particles of the electrode material are in close contact with each other, It is important to have many junctions and surfaces between particles and to secure more ion conduction paths. Therefore, a method is used in which an ion conductive active material such as an electrolyte is mixed to make an electrode material. As the electrolyte, a solid electrolyte used for forming a solid electrolyte layer can be used. In this case, it is preferable that the solid electrolyte to be mixed is one that is heat-dried under the above conditions to reduce the volatile content. In addition, the smaller the space generated in the gap between the polar material particles (the ratio of the volume of the polar material particles to the volume of the polar material particles: the porosity), the denser the polar material layer is and the higher the ionic conductivity.

(Vi) Conductive aid As the conductive aid, a material having electrical conductivity may be appropriately added to the positive electrode so that electrons move smoothly in the positive electrode active material. There are no particular restrictions on the electrically conductive substance, and conductive substances such as acetylene black, carbon black, and carbon nanotubes or conductive polymers such as polyaniline, polyacetylene, and polypyrrole may be used alone or in combination. Can do.

(Vii) Method for producing electrode layer The electrode can be produced by forming the electrode material (positive electrode material or negative electrode material) into a film shape on at least a part of the current collector. Examples of the film forming method include a blast method, an aerosol deposition method, a cold spray method, a sputtering method, a vapor phase growth method, and a thermal spraying method. By forming a film by such a method, the porosity of the electrode material layer can be further reduced, and the ionic conductivity can be improved.
Blasting and aerosol deposition are preferred because they can be formed in a temperature range that does not change the crystal state of the electrolyte under simple equipment and room temperature conditions.

(Viii) Manufacturing method of all-solid-state battery An all-solid-state battery can be manufactured by bonding and joining the above-described battery members. As a method of joining, there are a method of laminating each member, 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.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited at all by an Example.
[Production Example 1]
(1) Production of lithium sulfide (Li ₂ S) In a 10 liter autoclave equipped with a stirring blade, N-methyl-2-pyrrolidone (NMP) 3326.4 g (33.6 mol) and lithium hydroxide 287.4 g (12 mol) ) And heated to 300 rpm and 130 ° 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 solid electrolyte About 1 g of a mixture of Li ₂ S and P ₂ S ₅ (manufactured by Aldrich) produced as described above in a molar ratio of 70:30 and 10 balls made of alumina having a diameter of 10 mm Is put into a 45 mL alumina container, and is subjected to mechanical milling treatment for 20 hours with a planetary ball mill (manufactured by Fritsch: Model No. P-7) in nitrogen at room temperature (25 ° C.) at a rotation speed of 370 rpm. Thus, a sulfide-based glass which was a white yellow powder was obtained. Moreover, the obtained powder was put into a glass closed container and heat-treated at 300 ° C. for 2 hours to be fired to obtain a sulfide glass ceramic.

This sulfide glass ceramic was processed into a pellet-shaped (diameter: about 10 mm, thickness: about 1 mm) shaped body. About this molded object, the ionic conductivity was measured at normal temperature (25 degreeC). The measurement was performed by an alternating current two-terminal method using carbon as an electrode for the molded body. As a result, the ionic conductivity at room temperature (25 ° C.) immediately after production of the obtained sulfide-based glass ceramic was 1.0 × 10 ⁻³ S / cm ² .

The volatile content of the sulfide-based glass ceramic immediately after production was measured as follows.
(1) Measurement of volatile content The volatile content was determined using TG / DTA manufactured by SSI Nanotechnology. A predetermined amount of electrolyte sample was quantified in an N ₂ atmosphere, placed in a measurement pan, and heated from room temperature to 400 ° C. at a rate of 10 ° C./min. The weight loss at that time was measured, and from this, the volatile content per kg of the sample was calculated.

(2) Qualitative analysis Qualitative analysis of volatile components was measured with a pyrolysis gas chromatograph mass spectrometer. The sample was introduced into a thermal decomposition section heated to 400 ° C., and the generated gas was detected with a gas chromatograph mass spectrometer. Gas components were identified by library search. As a result, it was confirmed that the main volatile components were H ₂ S, CS ₂ and H ₂ O.
The manufacturer and model of each part, and measurement conditions are as follows.

A. Thermal decomposition part Manufacturer: Frontier Lab Co., Ltd. Model: Py2020iD type Thermal decomposition atmosphere: He
Temperature: 400 ° C
Heating time: 30 seconds

A. Gas Chromatograph Mass Spectrometer Manufacturer: JEOL Ltd. Model: JMS-Q1000GC K9

  As a result, the volatile content of the sulfide glass ceramic immediately after production was 2% by weight.

Comparative Example 1
The sulfide glass ceramic (lithium ion conductive solid electrolyte) obtained in Production Example 1 (3) was left in a glove box in an argon atmosphere at -70 ° C. for 1 week, and then the volatile component content was measured. The ion conductivity was as low as 7 × 10 ⁻⁴ S / cm.

Example 1
Similarly to Comparative Example 1, the sulfide-based glass ceramic (lithium ion conductive solid electrolyte) after being left in a glove box in an argon atmosphere at −70 ° C. for 1 week was heated at 250 ° C. for 2 hours under an argon stream. Heat-dried. As a result, the volatile component content was not detected immediately after drying by heating, and the ionic conductivity was 2.0 × 10 ⁻³ S / cm. This ionic conductivity is equal to or higher than that immediately after the production of the sulfide-based glass ceramic.

Example 2: Manufacture of all-solid battery (1) Manufacture of positive electrode / solid electrolyte layer / negative electrode pellet A negative electrode material constituting the negative electrode was obtained by heating and drying in Example 1 with carbon graphite (manufactured by TIMCAL, SFG-15). The sulfide-based glass ceramic thus obtained was mixed at a mass ratio of 1: 1. A positive electrode material constituting the positive electrode was produced by mixing lithium cobaltate and the sulfide-based glass ceramic obtained by heating and drying in Example 1 at a mass ratio of 6: 4. Then, using a commercially available pellet molding machine, a negative electrode material (10 mg), a sulfide-based glass ceramic (150 mg) obtained by heating and drying in Example 1 which is a solid electrolyte, and a positive electrode material (20 mg) are sequentially formed into a pellet molding machine. And a pressure of 20 t / cm ^{2 was} sequentially applied to produce a three-layer pellet of a positive electrode, a solid electrolyte layer, and a negative electrode.

(2) Manufacture of all-solid-state battery A current collector was sandwiched between both electrodes by a SUS plate, and the current-collector was pressure-bonded by screwing to obtain an all-solid-state battery.

  According to the present invention, it is possible to recover the ionic conductivity of a lithium ion conductive solid electrolyte in which the ionic conductivity is lowered due to a small amount of volatile matter in the atmosphere adhering to the surface while being stored for a certain period after manufacture. Therefore, it is possible to provide an all-solid battery having high battery performance.

It is a schematic diagram which shows the basic composition of the all-solid-state battery of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 All-solid-state battery 10 Positive electrode 20 Solid electrolyte layer 30 Negative electrode 40,42 Current collector

Claims (4)

A sulfide-based inorganic solid electrolyte,
  As a result of measurement by the following method, H ₂ S, CS ₂ And H ₂ A sulfide-based inorganic solid electrolyte in which O is not detected.
  A sample of the inorganic solid electrolyte is heated from room temperature to 400 ° C. at a rate of 10 ° C./min, and volatile components are introduced into the thermal decomposition part of the pyrolysis gas chromatograph mass spectrometer, and heated in a pyrolysis atmosphere He at 400 ° C. for 30 seconds. The generated gas is detected by a gas chromatograph mass spectrometer. The sulfide-based inorganic solid electrolyte according to claim 1, comprising at least one of Si, Ge, P, and B and lithium and sulfur. An electrode composite comprising the sulfide-based inorganic solid electrolyte according to claim 1 and a positive electrode active material or a negative electrode active material. An all-solid battery comprising the sulfide-based inorganic solid electrolyte according to claim 1 .

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