JP5348853B2 - Sulfide-based electrolyte molded body and all-solid battery comprising the same - Google Patents

Description

  The present invention relates to a sulfide-based electrolyte powder, a sulfide-based electrolyte molded body using the same, and an all-solid battery.

In recent years, there has been an increasing demand for lithium ion secondary batteries used in personal digital assistants, portable electronic devices, small household power storage devices, motorcycles powered by motors, electric vehicles, hybrid electric vehicles, and the like.
In the lithium ion secondary battery, an organic electrolytic solution is used as an electrolyte. Although organic electrolytes exhibit high ionic conductivity, they are liquid and flammable, so there are concerns about safety such as leakage and ignition.

  As a method for ensuring the safety of a lithium ion secondary battery, an all-solid secondary battery using an inorganic solid electrolyte instead of an organic electrolyte has been studied. However, in general, inorganic solid electrolytes have lower ionic conductivity than organic electrolytes, and it has been difficult to put all solid secondary batteries into practical use.

For example, lithium ion conductive ceramics based on Li ₃ N have been reported as inorganic solid electrolytes. However, since this ceramic has a low decomposition voltage, it could not be used for an all-solid-state secondary battery operating at 3 V or higher.

Patent Document 1 discloses a solid electrolyte made of sulfide-based crystallized glass that exhibits high lithium ion conductivity even at room temperature. However, the electrolyte described in Patent Document 1 is industrially disadvantageous because it requires a large amount of expensive lithium. Moreover, since the ionic conductivity of the electrolyte in the vicinity of room temperature is about 1.0 × 10 ⁻³ S / cm, further improvement in ionic conductivity is necessary.
JP 2002-109955 A

  An object of the present invention is to provide a sulfide-based electrolyte molded body having high ionic conductivity.

According to the present invention, the following sulfide-based electrolyte powder and the like are provided.
1. Including at least one element selected from the group consisting of sulfur element, lithium element, and boron, silicon, germanium, phosphorus, and aluminum;
A sulfide-based electrolyte powder having an average particle size of 0.01 to 10 μm.
2. 2. The sulfide electrolyte powder according to 1, obtained using the following components (A) and (B).
(A) Lithium sulfide _(B) A m _S compounds represented by _n (A is boron, and silicon, germanium, phosphorus or aluminum, m and n is an integer of from 1 to 10, respectively.)
3. Including at least one element selected from the group consisting of sulfur element, lithium element, oxygen element, and boron, silicon, germanium, phosphorus and aluminum;
A sulfide-based electrolyte powder having an average particle size of 0.01 to 10 μm.
4). 4. The sulfide electrolyte powder according to 3, obtained by using the following components (A), (B) and (C).
(A) Lithium sulfide _(B) A m _S compounds represented by _n (A is boron, and silicon, germanium, phosphorus or aluminum, m and n is an integer of from 1 to 10, respectively.)
(C) Compound represented by Li _x M _y O _z (M is boron, silicon, germanium, sulfur, phosphorus, or aluminum, and x, y, and z are each an integer of 1 to 10)
5. Any one of 1 to 4 in which the exothermic peak detected by differential scanning calorimetry (in a dry nitrogen atmosphere, a heating rate of 10 ° C./min, 20 to 400 ° C.) is substantially one between 200 to 300 ° C. The sulfide-based electrolyte powder described in 1.
The sulfide-based solid electrolyte powder according to any one of 6.1 to 5, wherein each primary particle in a solid electrolyte molded body obtained by pressure-molding the powder is fused, and the solid electrolyte molding A sulfide-based solid electrolyte powder having a body density of 1.45 to 2.00 g / cm ³ .
A sulfide-based electrolyte molded body obtained by molding the sulfide-based electrolyte powder according to any one of 7.1 to 6,
A sulfide-based electrolyte molded body in which the sulfide-based electrolyte powders are fused to each other.
8). 8. The sulfide electrolyte molded body according to 7, wherein the calculated density is 1.45 to 2.00 g / cm ³ .
9. The sulfide-based electrolyte molded body according to 7 or 8 having an ionic conductivity of 4.5 × 10 ⁻³ S / cm or more.
An all-solid-state battery using the sulfide-based electrolyte molded body according to any one of 10.7 to 9.
A solid electrolyte comprising the sulfide-based electrolyte molded body according to any one of 11.7 to 9, and a positive electrode mixture containing the sulfide-based electrolyte powder according to any one of 1 to 6 and a positive electrode active material are heat-treated. The all-solid-state battery of 10 which comprises the negative electrode formed by heat-processing the negative electrode compound material containing the positive electrode formed by and / or the sulfide type electrolyte powder in any one of 1-6, and a negative electrode active material.
12. An all solid state battery obtained by further heat-treating the all solid state battery described in 10 or 11.

  ADVANTAGE OF THE INVENTION According to this invention, the sulfide type electrolyte molded object which has high ionic conductivity can be provided.

  The sulfide-based electrolyte powder of the present invention contains sulfur element, lithium element, and at least one element selected from the group consisting of boron, silicon, germanium, phosphorus and aluminum, and has an average particle size of 0.01 to 10 μm. is there.

The sulfide-based electrolyte powder of the present invention has an average particle size of 0.01 to 10 μm, preferably 0.01 to 0.1 μm. When the average particle diameter exceeds 10 μm, when the sulfide-based electrolyte powder of the present invention is used for a solid battery, there is a possibility that the solid battery cannot be increased in energy density and output, and the average particle diameter is 0.01 μm. If it is less, classification may be required.
The average particle size is determined by observing the sulfide-based electrolyte powder using a scanning electron microscope, arbitrarily selecting 20 powder particles observed in an arbitrary 100 μm ² area, and determining the particle size. It is an average value of values obtained by measurement.

The sulfide-based electrolyte powder of the present invention is preferably a sulfide-based electrolyte powder obtained using the following components (A) and (B).
(A) Lithium sulfide _(B) A m _S compounds represented by _n (A is boron, and silicon, germanium, phosphorus or aluminum, m and n is an integer of from 1 to 10, respectively.)

The component (B) is preferably P ₂ S ₅ .

  In the sulfide-based electrolyte powder using the components (A) and (B), the molar ratio of the components (A) and (B) is, for example, component (A): component (B) = 50: 50 to 92. 5: 7.5, preferably 65-75: 35-25.

As another embodiment of the present invention, the sulfide-based electrolyte powder of the present invention contains at least one element selected from the group consisting of sulfur element, lithium element, oxygen element, and boron, silicon, germanium, phosphorus, and aluminum. And the average particle size is 0.01 to 10 μm.
The preferred average particle diameter of the sulfide-based electrolyte powder and the measuring method thereof are as described above.

The sulfide-based electrolyte powder according to another embodiment of the present invention is preferably a sulfide-based electrolyte powder obtained using the following components (A), (B), and (C).
(A) Lithium sulfide _(B) A m _S compounds represented by _n (A is boron, and silicon, germanium, phosphorus or aluminum, m and n is an integer of from 1 to 10, respectively.)
(C) Compound represented by Li _x M _y O _z (M is boron, silicon, germanium, sulfur, phosphorus, or aluminum, and x, y, and z are each an integer of 1 to 10)

The component (B) is preferably P ₂ S ₅ , and the component (C) is preferably a compound in which M is silicon or phosphorus.

  In the sulfide-based electrolyte powder using the components (A), (B) and (C), the molar ratio of the components (A), (B) and (C) is, for example, component (A): 40 to 92. .4 mol%, component (B): 7.5 to 40 mol%, component (C): 0.1 to 20 mol%, preferably component (A): 63 to 69.3 mol%, component ( B): 27 to 29.7 mol%, component (C): 1 to 10 mol%.

The components (A) to (C) used in the sulfide-based electrolyte powder of the present invention are not particularly limited, and those that are industrially available can be used, but those with high purity are preferred.
For example, the lithium sulfide as the component (A) preferably has a total content of lithium salt of sulfur oxide of 0.15% by mass or less, more preferably 0.1% by mass or less, and N-methylaminobutyric acid. The lithium content is 0.15% by mass or less, more preferably 0.1% by mass or less. When the total content of the lithium salt of sulfur oxide is 0.15% by mass or less, the obtained solid electrolyte 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 there is a possibility that a solid electrolyte having high ionic 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 in the solid substance is not particularly limited as long as it is a method that can reduce at least the impurities.
For example, it can also be obtained by purifying lithium sulfide produced by the following method.
Among the following production methods, the method a or b is particularly preferable.
a. A method in which lithium hydroxide and hydrogen sulfide are reacted at 0 to 150 ° C. in an aprotic organic solvent to produce lithium hydrosulfide, and this reaction solution is then desulfurized at 150 to 200 ° C. -330312).
b. A method of directly producing lithium sulfide by reacting lithium hydroxide and hydrogen sulfide at 150 to 200 ° C. in an aprotic organic solvent (Japanese Patent Laid-Open No. 7-330312).
c. A method of reacting lithium hydroxide and a gaseous sulfur source at a temperature of 130 to 445 ° C. (Japanese Patent Laid-Open No. 9-283156).

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

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

The sulfide-based electrolyte powder of the present invention preferably has an exothermic peak of 200 to 300 ° C. detected by differential scanning calorimetry (DSC) at a heating rate of 10 ° C./min and 20 to 400 ° C. in a dry nitrogen atmosphere. There is substantially one in between.
When the exothermic peak of the sulfide-based electrolyte powder of the present invention is substantially one between 200 and 300 ° C., the sulfide-based electrolyte powder after DSC contains a crystalline phase and has a homogeneous composition. It becomes a crystalline glass state.

  In the present invention, the phrase “substantially one exothermic peak is between 200 and 300 ° C.” means a peak having a maximum calorific value at 200 to 300 ° C. in the entire temperature range (20 to 400 ° C.). On the other hand, the other exothermic peak is a minute peak having a calorific value of 10% or less of the maximum calorific value.

The sulfide electrolyte powder of the present invention can be produced by using, for example, a mechanical milling method (MM method).
In the case of the MM method, a predetermined amount of components (A) and (B) or components (A) to (C) are mixed in a mortar and reacted for a predetermined time by a mechanical milling method, thereby vitrifying sulfide-based electrolyte. A powder is obtained.
The mechanical milling method using the above raw materials can be reacted at room temperature. According to the MM method, since the sulfide-based electrolyte powder can be produced at room temperature, there is an advantage that the raw material is not thermally decomposed and a sulfide-based electrolyte powder having a charged composition can be obtained.
Further, the MM method has an advantage that the sulfide-based electrolyte powder can be finely powdered simultaneously with the production of the sulfide-based electrolyte powder.
Although various types can be used for the MM method, for example, a mechanical mill such as a planetary ball mill, a vibration mill, or a jet mill can be used.

  When the MM treatment is performed for a long time with relatively small energy, the DSC exothermic peak becomes substantially one. Specifically, a predetermined amount of components (A) and (B), or components (A) to (C), in a dry atmosphere with a dew point of −40 ° C. or less, 0.02 to 1 kJ / kg · s for 60 hours. The sulfide electrolyte powder of the present invention can be produced by pulverizing for 280 hours.

The sulfide-based electrolyte molded body of the present invention is composed of the sulfide-based electrolyte powder of the present invention, and the powders are fused to each other.
The molded body can be produced, for example, by molding the sulfide-based electrolyte powder of the present invention at a predetermined pressure and heat-treating at a predetermined temperature. Thus, by applying pressure and heat-treating, the sulfide-based electrolyte powders can be fused to each other at a high density, and a wide range of ion conduction paths can be formed.
The fact that the sulfide-based electrolyte powder is fused is observed by using a scanning electron microscope to observe the obtained sulfide-based electrolyte compact, and the boundary between the sulfide-based electrolyte powders is observed. It can be confirmed by what cannot be done.

The molding pressure of the sulfide-based electrolyte molded body is usually 2 to 10 MPa.
As heat processing temperature, it is 150 to 360 degreeC normally. If the heat treatment temperature is lower than 150 ° C., it may be difficult to obtain a crystal glass with high ion conductivity, and if it is higher than 360 ° C., a crystal structure with low ion conductivity may be formed.
The heat treatment time is, for example, 0.5 to 10 hours.

Since the higher the density of the molded body is, the more ion conduction paths can be secured, the calculated density of the sulfide-based electrolyte molded body of the present invention is preferably 1.45 to 2.00 g / cm ³ , more preferably. 1.5 to 2.00 g / cm ³ .
The calculated density means a molded body in which a molded body composed only of the sulfide-based electrolyte powder of the present invention is sandwiched between two electrodes composed of a mixed powder of 5 mg of graphite and 5 mg of the sulfide-based electrolyte powder of the present invention. The specific density can be calculated using the following formula.
Calculated density = ((5 mg + 5 mg) × 2 + mass of the sulfide-based electrolyte powder used in the molded body) / volume of the molded body For example, a sulfide-based electrolyte powder composed only of Li ₂ S and P ₂ S ₅ is sulfided. When used for the production of a system electrolyte molded body, the theoretical upper limit of the calculated density (void 0) is 2.00.

The ionic conductivity of the sulfide-based electrolyte molded body of the present invention is preferably 4.5 × 10 ⁻³ S / cm or more, more preferably 5 × 10 ⁻³ S / cm or more. Since the molded body has such ionic conductivity, the all-solid-state battery using the sulfide-based electrolyte molded body of the present invention can achieve high output.

FIG. 1 is a schematic cross-sectional view showing an embodiment of an all-solid battery according to the present invention.
In the all-solid-state battery 1, a solid electrolyte molded body 20 that is a sulfide-based electrolyte molded body of the present invention is sandwiched between a pair of electrodes composed of a positive electrode 10 and a negative electrode 30. Current collectors 40 and 42 are provided on the positive electrode 10 and the negative electrode 30, respectively.

  The positive electrode 10 is made of a positive electrode active material, and is preferably a positive electrode obtained by heat-treating the sulfide-based electrolyte powder of the present invention and the positive electrode mixture of the positive electrode active material. In the positive electrode mixture, the mixing ratio (weight ratio) of the sulfide-based electrolyte powder and the cathode material is preferably sulfide-based electrolyte powder: positive electrode active material = 20-50: 80-50. Although heating conditions are not specifically limited, Usually, heating temperature is 100-350 degreeC and heating time is 0.1 to 10 hours. A positive electrode material for a high-power battery can be produced by heating under these conditions.

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

  The negative electrode 30 is a negative electrode made of a negative electrode active material, and preferably a heat-treated negative electrode mixture containing sulfide-based electrolyte powder. In the negative electrode mixture, the mixing ratio (weight ratio) between the sulfide-based electrolyte powder and the negative electrode material is preferably sulfide-based electrolyte powder: negative electrode active material = 20-50: 80-50.

What is used as a negative electrode active material in the battery field can be used for a negative electrode active material. For example, carbon materials, specifically artificial graphite, graphite carbon fiber, resin-fired carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon Examples thereof include fibers, vapor-grown carbon fibers, natural graphite, and non-graphitizable carbon. Or it may be a mixture thereof. 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.

  A material having electrical conductivity may be appropriately added to the positive electrode 10 and the negative electrode 30 as a conductive auxiliary agent so that electrons move smoothly in the positive electrode active material. The electrically conductive substance is not particularly limited, but a conductive substance such as acetylene black, carbon black, or carbon nanotube or a conductive polymer such as polyaniline, polyacetylene, or polypyrrole is used alone or in combination. Can do.

The positive electrode and the negative electrode can be produced by forming the electrode material in 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.

The solid electrolyte molded body 20 is a sulfide-based electrolyte molded body of the present invention.
The solid electrolyte molded body can be manufactured by using the above-described method. For example, it can also be manufactured by forming a particulate lithium ion conductive solid material by a blast method or an aerosol deposition method. Also, a lithium ion conductive solid material can be formed by a cold spray method, a sputtering method, a vapor deposition method (CVD), a thermal spraying method, or the like.
Further, there is a method in which a solution in which a solid electrolyte is mixed with a solvent and a binder (binder, polymer compound, etc.) is applied and applied, and then the solvent is 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.
Blasting and aerosol deposition are preferred because they can be formed in a temperature range that does not change the state of the solid electrolyte under simple equipment and room temperature conditions.

  As the current collectors 40, 42, 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 is used. Can be used.

  The all solid state battery of the present invention can be manufactured by bonding and joining the battery members described above. 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. You may join to a joint 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.

  Moreover, it is preferable that the all solid state battery manufactured by the above method is further heat-treated. The heating conditions are usually 100 to 350 ° C. and 0.1 to 10 hours. A battery with high output can be produced by heating. The heat treatment of the all-solid battery includes a case where only the battery element portion including only the negative electrode, the solid electrolyte formed body, and the positive electrode is heat-treated. Also, it does not include heat treatment such as safety devices and lapping.

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

(2) Purification of lithium sulfide After decanting NMP in the 500 mL slurry reaction solution (NMP-lithium sulfide slurry) obtained in (1) above, 100 mL of dehydrated NMP was added and stirred at 105 ° C. for about 1 hour. . 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.

Example 1
Li ₂ S and P ₂ S ₅ (manufactured by Aldrich) produced in the above production example were used as starting materials. 250 g of the mixture adjusted to a molar ratio of 70:30 was placed in a SUS container (capacity: 6.7 L) filled with zirconia balls, and 200 hours under a dry atmosphere at a dew point of −40 ° C. or lower and at room temperature. A mechanical milling treatment was performed by applying mechanical energy of 1 kJ / kg · s with a vibration mill to obtain a sulfide-based electrolyte powder of white yellow powder.
Powder X-ray diffraction measurement was performed on the obtained powder (CuKα: λ = 1.5418Å). The obtained chart is shown in FIG. From this chart, it was confirmed that the sulfide-based electrolyte powder was vitrified.

  When the obtained powder was observed using a scanning electron microscope, fine particles having a particle size of 0.2 to 6 μm were observed, and the average particle size of the obtained powder was found to be 1.4 μm. .

  Further, differential scanning calorimetry was performed on the obtained powder. The obtained chart is shown in FIG. From this chart, it was confirmed that the sulfide-based electrolyte powder had one exothermic peak near 250 ° C. Differential scanning calorimetry was performed at 10 ° C./min in a nitrogen atmosphere using MODEL DSC-7 (manufactured by PerkinElmer).

  The obtained sulfide-based electrolyte powder was filled in a tablet molding machine, and a pressure of 4 to 6 MPa was applied to produce a sulfide-based electrolyte molded body. Furthermore, a solid electrolyte molded body (diameter of about 10 mm, thickness of about 1 mm) was obtained by placing a mixture of 5 mg of graphite and 5 mg of the obtained sulfide-based electrolyte powder on both surfaces of the molded body and applying pressure again with a tablet molding machine. Was made.

The obtained molded body was put in a glass bottle, further put in a SUS tube in an argon atmosphere and sealed, and subjected to a baking treatment at 300 ° C. for 2 hours. The ionic conductivity of the molded article for evaluation obtained by the firing treatment was measured by an alternating current impedance method. As a result, the ionic conductivity of the obtained solid electrolyte molded body at room temperature (25 ° C.) was 7.3 × 10 ⁻³ S / cm. Moreover, when the density of this molded body was calculated from the results of weight and thickness measurement and the diameter of the tablet molding machine, the calculated density was 1.58 g / cm ³ .

Moreover, the cross section of this molded object was observed using the scanning electron microscope. A cross-sectional photograph of the molded body is shown in FIG. In the cross section of this molded body, the particles were fused together, and it was confirmed that the molded body had few voids. In Table 1 below, the observation of the fusion of the sulfide-based electrolyte powder in the cross section of the compact was evaluated as follows.
○: The sulfide electrolyte powders are fused.
X: The sulfide-based electrolyte powder is not fused.

Moreover, it was confirmed that the crystallinity of this molded body was 66%. The crystallinity, using JNM-CMXP302NMR apparatus (manufactured by JEOL Ltd.), to measure the solid ³¹ PNMR spectrum under the following conditions, the obtained solid ³¹ PNMR spectrum, is observed in 70~120ppm The resonance lines were separated into Gaussian curves using a non-linear least square method and calculated from the area ratio of each curve.

Measurement conditions of solid ³¹ P-NMR spectrum Observation nucleus: ³¹ P
Observation frequency: 121.339 MHz
Measurement temperature: Room temperature Measurement method: MAS method Pulse sequence: Single pulse 90 ° Pulse width: 4 μs
Magic angle rotation speed: 8600Hz
Wait time until the next pulse application after FID measurement: 100-2000s
(Set to be more than 5 times the maximum spin-lattice relaxation time)
Number of integrations: 64 times Chemical shifts were determined using (NH ₄ ) ₂ HPO ₄ (chemical shift 1.33 ppm) as an external reference.
In order to prevent deterioration due to moisture in the air during sample filling, the sample was filled into a hermetic sample tube in a dry box in which dry nitrogen was continuously flowed.

Example 2
A sulfide-based electrolyte powder (average particle diameter 2 μm) and a molded body thereof were prepared and evaluated in the same manner as in Example 1 except that the mechanical milling time was 120 hours. The results are shown in Table 1.

Comparative Example 1
A sulfide-based electrolyte powder (average particle size 1 μm) was produced in the same manner as in Example 1 except that the mechanical milling time was 40 hours.
Powder X-ray diffraction measurement was performed on the obtained powder (CuKα: λ = 1.5418Å). From the obtained chart, it was confirmed that the sulfide electrolyte powder was vitrified.
In addition, this sulfide-based electrolyte powder was sealed in a SUS tube under an argon atmosphere and subjected to a baking treatment at 300 ° C. for 2 hours. The sulfide-based electrolyte powder subjected to the firing treatment was filled in a tablet molding machine, and a pressure of 4 to 6 MPa was applied to produce a sulfide-based electrolyte molded body. Further, a mixture of 5 mg of graphite and 5 mg of the calcinated sulfide-based electrolyte powder was placed on both sides of the molded body, and pressure was applied again with a tablet molding machine, so that a molded body for evaluation (diameter of about 10 mm, thickness of about 1 mm). ) Were prepared and evaluated. The results are shown in Table 1.

Comparative Example 2
A molded article for evaluation was produced and evaluated in the same manner as in Comparative Example 1 except that the sulfide-based electrolyte powder produced in Example 1 was used. The results are shown in Table 1.

Comparative Example 3
Except that Li ₂ S and P ₂ S ₅ (manufactured by Aldrich) produced in the above production example were used as starting materials, and mechanical milling treatment was performed using a vibration mill and applying mechanical energy of 1 kJ / kg · s for 36 hours. In the same manner as in Example 1, a sulfide-based electrolyte powder (average particle size 1.5 μm) was produced.

The obtained powder was subjected to differential scanning calorimetry in the same manner as in Example 1. The obtained chart is shown in FIG. From this chart, it was confirmed that the sulfide-based electrolyte powder had three exothermic peaks at around 233 ° C., around 246 ° C., and around 265 ° C.
Moreover, the molded object for evaluation was produced and evaluated like Example 1 using the obtained powder. The results are shown in Table 1.

Comparative Example 4
The sulfide-based electrolyte powder produced in Example 1 was put in a SUS tube under an argon atmosphere and sealed, and subjected to a baking treatment at 300 ° C. for 2 hours. The sulfide-based electrolyte powder subjected to the firing treatment was filled in a tablet molding machine, and a pressure of 4 to 6 MPa was applied to produce a sulfide-based electrolyte molded body. Further, a mixture of 5 mg of graphite and 5 mg of the calcined sulfide-based electrolyte powder was placed on both sides of the molded body, and pressure was applied again with a tablet molding machine, so that a solid electrolyte molded body for measuring ionic conductivity (diameter of about 10 mm and a thickness of about 1 mm).
The produced compact was vacuum-sealed in an aluminum pack, and a pressure of about 1 t / cm ² was applied by a cold isostatic pressing method (CIP) to produce an evaluation compact. This evaluation molded body was evaluated. The results are shown in Table 1.

The cross section of the molded article for evaluation produced in Comparative Example 4 was observed using a scanning electron microscope. A cross-sectional photograph of the molded body is shown in FIG. The calculated density of the compact was 1.45 g / cm ² or more, but it was confirmed that the particles were not fused together in the cross section of the compact.

  FIG. 7 shows the relationship between the ionic conductivity and the calculated density of the molded articles for evaluation produced in Examples 1 and 2 and Comparative Examples 1 and 4 of the present invention.

The sulfide electrolyte powder of the present invention enables high energy density and high output of a solid battery, and is suitable as a material for a solid electrolyte of a lithium battery.
Furthermore, the all-solid-state battery using the sulfide-based electrolyte powder of the present invention having the above characteristics is excellent in safety.

It is a schematic sectional drawing which shows one Embodiment of the all-solid-state battery which concerns on this invention. 2 is an X-ray diffraction spectrum chart of the sulfide-based electrolyte powder produced in Example 1. FIG. 2 is a DSC chart of the sulfide-based electrolyte powder produced in Example 1. 2 is a cross-sectional photograph of a molded article for evaluation produced in Example 1. 6 is a DSC chart of a sulfide-based electrolyte powder produced in Comparative Example 3. 6 is a cross-sectional photograph of a molded article for evaluation produced in Comparative Example 4. It is a figure which shows the relationship between the ionic conductivity and the calculation density of the molded object for evaluation manufactured in Example 1 and 2 of this invention, and Comparative Example 1 and Comparative Example 4. FIG.

Explanation of symbols

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

Claims (7)

Containing at least one element selected from the group consisting of sulfur element, lithium element, boron, silicon, germanium, phosphorus and aluminum, and an average particle size of 0.01 to 10 μm,
Sulfide-based electrolyte powder whose exothermic peak detected by differential scanning calorimetry (in dry nitrogen atmosphere, heating rate 10 ° C./min, 20 to 400 ° C.) is substantially one between 200 and 300 ° C. Are sulfide-based electrolyte molded bodies fused to each other,
The sulfide electrolyte powder is obtained using component (A) lithium sulfide and component (B) P ₂ S ₅ ;
The molar ratio of the components (A) and (B) is component (A): component (B) = 65-75: 35-25,
The calculated density is 1.45 to 2.00 g / cm ³ ;
The said sulfide type electrolyte molded object whose ionic conductivity in 25 degreeC is 4.5x10 < ^-3 > S / cm or more.   The sulfide-based electrolyte molded body according to claim 1, wherein the molar ratio of the components (A) and (B) is component (A): component (B) = 70: 30. Sulfur element, lithium element, oxygen element, and
Containing at least one element selected from the group consisting of boron, silicon, germanium, phosphorus and aluminum, and having an average particle size of 0.01 to 10 μm,
Sulfide-based electrolyte powder whose exothermic peak detected by differential scanning calorimetry (in dry nitrogen atmosphere, heating rate 10 ° C./min, 20 to 400 ° C.) is substantially one between 200 and 300 ° C. Are sulfide-based electrolyte molded bodies fused to each other,
The sulfide electrolyte powder is composed of component (A) lithium sulfide and component (B) P. ₂ S ₅ And a compound represented by component (C) LixMyOz (M is boron, silicon, germanium, sulfur, phosphorus, or aluminum, and x, y, and z are each an integer of 1 to 10). ,
The molar ratio of said component (A), (B) and (C) is component (A): component (B): component (C) = 63-69.3: 27-29.7: 1-10. ,
Calculated density is 1.45 to 2.00 g / cm ³ And
The ionic conductivity at 25 ° C. is 4.5 × 10 ^-3 The sulfide-based electrolyte molded body having a S / cm or more. The sulfide-based electrolyte molded body according to any one of claims 1 to 3 , wherein the calculated density is 1.5 to 2.00 g / cm ³ . The sulfide-based electrolyte molded body according to any one of claims 1 to 4 , wherein the ionic conductivity at 25 ° C is 5 x ^10-3 S / cm or more. All-solid-state battery comprising a sulfide-based electrolyte molded article according to any one of claims 1-5. An all-solid battery obtained by further heat-treating the all-solid battery according to claim 6 .