Method for manufacturing sulfide-based inorganic solid electrolyte materials

Abstract

To provide a method for producing a sulfide inorganic solid electrolyte material, which can stably yield a sulfide inorganic solid electrolyte material with improved lithium ion conductivity.SOLUTION: A method for producing a sulfide inorganic solid electrolyte material includes the step of mechanically treating a source composition of a sulfide inorganic solid electrolyte material comprising lithium sulfide and a phosphorus sulfide composition, to initiate a chemical reaction in each component for vitrification, resulting in a sulfide inorganic solid electrolyte material in a vitreous state. The phosphorus sulfide composition includes three or more peaks in the range of 2θ=22.5° or more and 24.5° or less, in an X-ray diffraction analysis spectrum from X-ray diffraction analysis.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a sulfide-based inorganic solid electrolyte material.

Background Art

[0002] Lithium ion batteries are generally used as power sources for small portable devices such as mobile phones and laptop computers. Recently, in addition to small portable devices, lithium ion batteries have also begun to be used as power sources for electric vehicles and power storage.

[0003] Currently commercially available lithium ion batteries use an electrolyte solution containing a flammable organic solvent. On the other hand, a lithium ion battery in which the electrolyte solution is replaced with a solid electrolyte and the battery is fully solidified (hereinafter also referred to as a fully solid-state lithium ion battery) does not use a flammable organic solvent in the battery, so simplification of the safety device can be achieved, and it is considered to be excellent in manufacturing cost and productivity.

[0004] As a solid electrolyte material used for such a solid electrolyte, for example, a sulfide-based inorganic solid electrolyte material is known.

[0005] Patent Document 1 (Japanese Patent Application Laid-Open No. 2016-27545) describes a sulfide-based solid electrolyte material characterized by having a peak at a position of 2θ = 29.86° ± 1.00° in X-ray diffraction measurement using CuKα rays and having a composition of Li 2y+3 PS4 (0.1 ≦ y ≦ 0.175).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] According to the studies of the present inventors, it has been revealed that when changing the type of phosphorus sulfide (for example, manufacturing company, manufacturing lot, manufacturing method), which is one of the raw materials of the sulfide-based inorganic solid electrolyte material, the lithium ion conductivity of the obtained sulfide-based inorganic solid electrolyte material may decrease.

[0008] The present invention has been made in view of the above circumstances, and provides a method for manufacturing a sulfide-based inorganic solid electrolyte material capable of stably obtaining a sulfide-based inorganic solid electrolyte material with improved lithium ion conductivity.

Means for Solving the Problems

[0009] The present inventors have intensively studied to achieve the above problems. As a result, by using a phosphorus sulfide composition having a specific X-ray profile as a raw material of the sulfide-based inorganic solid electrolyte material, it has been found that a sulfide-based inorganic solid electrolyte material with improved lithium ion conductivity can be stably obtained, and the present invention has been completed.

[0010] According to the present invention, there are provided a method for manufacturing a sulfide-based inorganic solid electrolyte material, a sulfide-based inorganic solid electrolyte material, a sulfide-based inorganic solid electrolyte, a sulfide-based inorganic solid electrolyte film, and a lithium ion battery as shown below.

[0011] [1] A step of mechanically treating a raw material composition of a sulfide-based inorganic solid electrolyte material containing lithium sulfide and a phosphorus sulfide composition to cause each component to undergo a chemical reaction while being vitrified to obtain a vitreous sulfide-based inorganic solid electrolyte material, The method for manufacturing a sulfide-based inorganic solid electrolyte material, wherein the phosphorus sulfide composition has three or more peaks in the range of 2θ = 22.5° or more and 24.5° or less in an X-ray diffraction analysis spectrum obtained by the method described in the following <X-ray Diffraction Analysis>. <X-ray Diffraction Analysis> Using an X-ray diffractometer, the phosphorus sulfide composition was placed in an airtight sample holder filled with argon gas and analyzed using CuKα radiation as the radiation source. The X-ray diffraction spectrum of the phosphorus sulfide composition was obtained under the following conditions: voltage 40kV, current 40mA, divergence slit 1°, divergence slit vertical limit 10mm, scattering slit 1°, receiving slit 0.3mm, measurement start angle 3°, measurement end angle 90°, and scan speed 0.2° / min. [2] A method for producing a sulfide-based inorganic solid electrolyte material according to [1], wherein the phosphorus sulfide composition contains P2S5. [3] A method for producing a sulfide-based inorganic solid electrolyte material according to [2], wherein the content of P2S5 in the phosphorus sulfide composition is 20% by mass or more. [4] A method for producing a sulfide-based inorganic solid electrolyte material according to any one of [1] to [3], wherein the phosphorus sulfide composition is in powder form. [5] A method for producing a sulfide-based inorganic solid electrolyte material according to any one of [1] to [4], wherein the mechanical treatment includes a mechanochemical treatment. [6] A method for producing a sulfide-based inorganic solid electrolyte material according to any one of [1] to [5], further comprising the step of heat-treating the glassy sulfide-based inorganic solid electrolyte material in a range of 180°C to 500°C. [7] The lithium ion conductivity of the sulfide-based inorganic solid electrolyte material, as measured by the method described in <Measurement of Lithium Ion Conductivity> below, is 1.0 × 10⁻⁶. -3 A method for producing a sulfide-based inorganic solid electrolyte material according to any one of the above [1] to [6], wherein the S / cm is 1 or higher. <Measurement of lithium-ion conductivity> First, 110 mg of sulfide-based inorganic solid electrolyte material is pressed at 270 MPa for 10 minutes to obtain a disc-shaped sample with a diameter of 9.5 mm and a thickness of 1 mm. Next, using an electrochemical measuring device, the lithium ion conductivity of the obtained disc-shaped sample is measured by AC impedance method with an applied voltage of 10 mV, a measurement frequency range of 0.1 Hz to 3 MHz, and a measurement temperature of 27 °C, using lithium foil as the electrode. [8] A sulfide-based inorganic solid electrolyte material obtained by a method for producing a sulfide-based inorganic solid electrolyte material according to any one of the above [1] to [7]. [9] A sulfide-based inorganic solid electrolyte comprising the sulfide-based inorganic solid electrolyte material described in [8] above.

[10] A sulfide-based inorganic solid electrolyte membrane containing the sulfide-based inorganic solid electrolyte described in [9] above as the main component.

[11] A lithium-ion battery comprising a positive electrode containing a positive electrode active material layer, an electrolyte layer, and a negative electrode containing a negative electrode active material layer, A lithium-ion battery in which at least one of the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer comprises the sulfide-based inorganic solid electrolyte material described in [8]. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for producing a sulfide-based inorganic solid electrolyte material that can stably obtain a sulfide-based inorganic solid electrolyte material with improved lithium ion conductivity. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view showing an example of the structure of the lithium-ion battery of this embodiment. [Figure 2] This figure shows the X-ray diffraction spectra of the phosphorus sulfide compositions used in the examples and comparative examples. [Figure 3] This figure shows an enlarged view of the X-ray diffraction analysis spectrum of the phosphorus sulfide compositions used in the examples and comparative examples, in the range of 2θ = 20 to 30°. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by common reference numerals, and the description thereof will be omitted as appropriate. Also, the drawings are schematic and do not match the actual dimensional ratios. The numerical range "A to B" represents A or more and B or less unless otherwise specified.

[0015] [Method for Producing Sulfide-Based Inorganic Solid Electrolyte Material] The method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment includes a step of mechanically treating a raw material composition of a sulfide-based inorganic solid electrolyte material containing lithium sulfide and a phosphorus sulfide composition to cause each component to undergo a chemical reaction while being vitrified to obtain a glassy sulfide-based inorganic solid electrolyte material. And the phosphorus sulfide composition of the present embodiment has three or more peaks in the range of 2θ = 22.5° or more and 24.5° or less in the X-ray diffraction analysis spectrum obtained by the method described in the following <X-ray Diffraction Analysis>. <X-ray Diffraction Analysis> Using an X-ray diffractometer, under the conditions of a voltage of 40 kV, a current of 40 mA, a divergence slit of 1°, a vertical limit of the divergence slit of 10 mm, a scattering slit of 1°, a receiving slit of 0.3 mm, a measurement start angle of 3°, a measurement end angle of 90°, and a scan speed of 0.2° / min, using CuKα rays as the radiation source, the phosphorus sulfide composition is set in an airtight sample holder filled with argon gas to obtain an X-ray diffraction analysis spectrum of the phosphorus sulfide composition

[0016] According to the studies of the present inventors, it has been clarified that when changing the type of phosphorus sulfide (for example, manufacturing company, manufacturing lot, manufacturing method), which is one of the raw materials of the sulfide-based inorganic solid electrolyte material, the lithium ion conductivity of the obtained sulfide-based inorganic solid electrolyte material may decrease. Therefore, the present inventors diligently studied how to provide a stable manufacturing method for sulfide-based inorganic solid electrolyte materials with improved lithium-ion conductivity. As a result, they discovered that by using a phosphorus sulfide composition as a raw material for the sulfide-based inorganic solid electrolyte material, in which three or more peaks are observed in the X-ray diffraction spectrum within the range of 2θ = 22.5° to 24.5°, the decrease in lithium-ion conductivity of the resulting sulfide-based inorganic solid electrolyte material can be suppressed, leading to the present invention. In other words, according to the method for producing sulfide-based inorganic solid electrolyte materials of this embodiment, by using a phosphorus sulfide composition in which three or more peaks are observed in the X-ray diffraction spectrum within the range of 2θ = 22.5° to 24.5° as a raw material for the sulfide-based inorganic solid electrolyte material, a sulfide-based inorganic solid electrolyte material with improved lithium ion conductivity can be stably obtained.

[0017] The method for producing a sulfide-based inorganic solid electrolyte material according to this embodiment includes the following step (A), and may further include steps (B) and (C). Step (C) may be performed between steps (A) and (B), or after step (B). Step (A): A process to obtain a sulfide-based inorganic solid electrolyte material in a glassy state by mechanically treating a raw material composition for a sulfide-based inorganic solid electrolyte material containing lithium sulfide and a phosphorus sulfide composition, thereby causing each component to react chemically and vitrify. Step (B): A step in which the obtained glassy sulfide-based inorganic solid electrolyte material is heated to crystallize at least a portion of it, thereby obtaining a glass-ceramic sulfide-based inorganic solid electrolyte material. Step (C): A process of crushing, classifying, or granulating the obtained sulfide-based inorganic solid electrolyte material in a glass or glass-ceramic state.

[0018] (Process (A)) First, a raw material composition for a sulfide-based inorganic solid electrolyte material is prepared. The raw material composition for the sulfide-based inorganic solid electrolyte material comprises lithium sulfide and a phosphorus sulfide composition, and may further contain lithium nitride as needed. Here, the mixing ratio of each raw material in the raw material composition is adjusted so that the resulting sulfide-based inorganic solid electrolyte material has the desired composition ratio.

[0019] The method of mixing the raw materials is not particularly limited as long as it is a method that can uniformly mix the raw materials, but for example, mixing can be done using a ball mill, bead mill, vibratory mill, impact grinding device, mixer (pug mixer, ribbon mixer, tumbler mixer, drum mixer, V-type mixer, etc.), kneader, twin-screw kneader, air jet grinder, crusher, rotary blade grinder, etc. The mixing conditions, such as the stirring speed, processing time, temperature, reaction pressure, and gravitational acceleration applied to the mixture, can be appropriately determined depending on the volume of the mixture being processed.

[0020] In step (A), a raw material composition for a sulfide-based inorganic solid electrolyte material containing lithium sulfide and a phosphorus sulfide composition is mechanically treated to vitrify the material while chemically reacting each component, thereby obtaining a sulfide-based inorganic solid electrolyte material in a glassy state. Here, mechanical treatment refers to a method that can vitrify a material while causing a chemical reaction by mechanically colliding two or more inorganic compounds, such as mechanochemical treatment. Mechanochemical treatment is a method of vitrifying a target composition while applying mechanical energy such as shear force or impact force. Furthermore, in process (A), the mechanochemical treatment is preferably a dry mechanochemical treatment, from the viewpoint of easily achieving an environment in which moisture and oxygen are removed at a high level. By using mechanochemical processing, each raw material can be mixed while being pulverized into fine particles, thereby increasing the contact area between each raw material. This promotes the reaction of each raw material, allowing the sulfide-based inorganic solid electrolyte material of this embodiment to be obtained more efficiently.

[0021] Here, mechanochemical treatment is a method of vitrification in which mechanical energy such as shear force, impact force, or centrifugal force is applied to the material to be mixed. Equipment used for vitrification by mechanochemical treatment (hereinafter referred to as vitrification equipment) includes crushing and dispersing machines such as ball mills, bead mills, vibratory mills, turbo mills, mechanofusion machines, disc mills, and roll mills; rotary and impact crushing devices consisting of a mechanism that combines rotation (shear stress) and impact (compressive stress), such as rock drills, rotary drills, and impact drivers; high-pressure gliding rolls; and vertical mills such as roller-type vertical mills and ball-type vertical mills. Among these, ball mills and bead mills are preferred, with ball mills being more preferred, from the viewpoint of being able to efficiently generate very high impact energy. Furthermore, from the standpoint of excellent continuous productivity, roll mills; rotary and impact grinding devices consisting of a mechanism that combines rotation (shear stress) and impact (compressive stress), such as rock drills, rotary hammers, and impact drivers; high-pressure gliding rolls; and vertical mills such as roller-type vertical mills and ball-type vertical mills are preferred.

[0022] The mixing conditions, such as rotation speed, processing time, temperature, reaction pressure, and gravitational acceleration applied to the raw material composition when mechanically processing the raw material composition, can be appropriately determined depending on the type and amount of the raw material composition being processed. Generally, the faster the rotation speed, the faster the rate of glass formation, and the longer the processing time, the higher the conversion rate to glass. Normally, when X-ray diffraction analysis is performed using CuKα rays as the radiation source, if the diffraction peak originating from the raw materials disappears or decreases, it can be determined that the raw material composition of the sulfide-based inorganic solid electrolyte material has been vitrified, and the desired sulfide-based inorganic solid electrolyte material has been obtained.

[0023] The mechanical treatment in step (A) is preferably carried out under an inert gas atmosphere. This prevents deterioration (e.g., oxidation) of the sulfide-based inorganic solid electrolyte material. Examples of the inert gas include argon gas, helium gas, nitrogen gas, etc. These inert gases are preferably of higher purity in order to prevent contamination of impurities into the product, and preferably have a dew point of -70°C or lower, more preferably -80°C or lower, in order to avoid contact with moisture.

[0024] Here, in step (A), the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material by the alternating current impedance method under the measurement conditions of 27.0°C, an applied voltage of 10 mV, and a measurement frequency range of 0.1 Hz to 3 MHz is preferably 1.0×10 -4 S·cm -1 or more, more preferably 2.0×10 -4 S·cm -1 or more, still more preferably 3.0×10 -4 S·cm -1 or more, still more preferably 4.0×10 -4 S·cm -1 or more, and it is preferable to perform vitrification treatment until this condition is met. Thereby, a sulfide-based inorganic solid electrolyte material having even better lithium ion conductivity can be obtained.

[0025] <Phosphorus sulfide composition> In the X-ray diffraction analysis spectrum obtained by the method described in the <X-ray diffraction analysis> of the phosphorus sulfide composition of the present embodiment, three or more peaks exist within the range of 2θ = 22.5° or more and 24.5° or less, and preferably three peaks exist.

[0026] The phosphorus sulfide composition of the present embodiment includes, for example, one or more selected from the group consisting of P2S5 (also represented as P4S 10 ), P4S9, P4S7, P4S3, and P4S5, preferably includes one or two selected from the group consisting of P2S5 and P4S9, and more preferably includes P2S5 and P4S9.

[0027] The P2S5 content in the phosphorus sulfide composition of this embodiment is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, even more preferably 40% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, even more preferably 55% by mass or less, and even more preferably 50% by mass or less, when the total phosphorus sulfide composition of this embodiment is considered as 100% by mass, in order to further improve the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material of this embodiment. Here, the P2S5 content in the phosphorus sulfide composition of this embodiment is solid 31 It can be calculated from the P-NMR spectrum.

[0028] The P4S9 content in the phosphorus sulfide composition of this embodiment is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 45% by mass or more, even more preferably 50% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less, when the total phosphorus sulfide composition of this embodiment is considered as 100% by mass, in order to further improve the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material of this embodiment. Here, the content of P4S9 in the phosphorus sulfide composition of this embodiment is solid 31 It can be calculated from the P-NMR spectrum.

[0029] The phosphorus sulfide composition of this embodiment preferably contains P2S5 and P4S9. The total content of P2S5 and P4S9 in the phosphorus sulfide composition of this embodiment is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 97% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more, when the total phosphorus sulfide composition of this embodiment is considered to be 100% by mass, in order to further improve the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material of this embodiment. There is no particular upper limit to the total content of P2S5 and P4S9 in the phosphorus sulfide composition of this embodiment, but for example, it is 100% by mass or less.

[0030] solid 31 P-NMR spectra can be measured, for example, by the following method. First, the test sample is filled into a 3.2 mm diameter sample tube in a glow box purged with N2 gas, rotated at a magic angle (54.7 degrees) relative to the external magnetic field (Magic Angle Spinning: MAS), and measurements are performed under the following conditions. Equipment: JNM-ECA-600 manufactured by JEOL RESONANCE Co., Ltd. Observation frequency: 242.95MHz Pulse width: 90° pulse Pulse waiting time: 2800 seconds Total number of times: 64 Measurement mode: Single pulse method MAS speed: 12kHz Standard substance: (NH4)2HPO4·1.33ppm Test sample 31 Regarding the peaks detected in the P-NMR spectrum, see Reference 1 "Hellmut Eckert, Cheryl S. Liang and Galen D. Stucky: 31 P magic angle spinning NMR of crystalline phosphorous sulfides. Correlation of 31Referring to "P chemical shielding tensors with local environments, J. Phys. Chem, 1989, 93, 452-457," waveform separation using a Gaussian function was performed based on the peak assignments described below, and the integral value of each peak was calculated. The integral value of the peak originating from each component is proportional to the number of moles of phosphorus contained. Therefore, the content ratio can be calculated from the obtained integral values ​​and the molecular weight of each component. The chemical shifts for P2S5 are 40-52 ppm, P4S9 are 52-70 ppm, P4S7 are 80-90 ppm, 90-100 ppm, and 110-115 ppm, and P4S3 are 80-90 ppm and 90-100 ppm.

[0031] The phosphorus sulfide composition of this embodiment can be in powder form, for example. Since the sulfide-based inorganic solid electrolyte material of this embodiment is generally manufactured by a dry process, having the phosphorus sulfide composition of this embodiment in powder form makes the manufacture of the sulfide-based inorganic solid electrolyte material easier.

[0032] <Lithium sulfide> The lithium sulfide used as a raw material is not particularly limited; commercially available lithium sulfide may be used, or lithium sulfide obtained by the reaction of lithium hydroxide and hydrogen sulfide may be used, for example. From the viewpoint of obtaining a high-purity sulfide-based inorganic solid electrolyte material and suppressing side reactions, it is preferable to use lithium sulfide with few impurities. In this embodiment, lithium sulfide also includes polysulfide.

[0033] <Lithium Nitride> Lithium nitride may be used as a raw material. Here, since the nitrogen in lithium nitride is discharged from the system as N2, by using lithium nitride as a raw material, it is possible to increase only the Li composition in a sulfide-based inorganic solid electrolyte material that contains Li, P, and S as constituent elements. The lithium nitride used in this embodiment is not particularly limited, and commercially available lithium nitride (e.g., Li3N, etc.) may be used, or lithium nitride obtained by reaction of metallic lithium (e.g., Li foil) with nitrogen gas may be used. In the method for producing sulfide-based inorganic solid electrolyte materials of this embodiment, it is preferable to use lithium nitride with few impurities from the viewpoint of obtaining a high-purity solid electrolyte material and suppressing side reactions. Here, the ratio of each raw material in the raw material composition can be adjusted so that the sulfide-based inorganic solid electrolyte material has a desired composition ratio.

[0034] (Process (B)) In step (B), the obtained glassy sulfide-based inorganic solid electrolyte material is heated to crystallize at least a portion of it, thereby obtaining a glass-ceramic sulfide-based inorganic solid electrolyte material. This makes it possible to obtain a sulfide-based inorganic solid electrolyte material with even better lithium-ion conductivity. In other words, the sulfide-based inorganic solid electrolyte material of this embodiment is preferably in a glass-ceramic state (crystallized glass state) because of its excellent lithium-ion conductivity. Here, glass-ceramic refers to a material in which at least a portion of the inorganic compound has crystallized, and is also called crystallized glass.

[0035] The heat treatment temperature in step (B) is not particularly limited, but from the viewpoint of further improving the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material of this embodiment, it is preferably 180°C or higher, more preferably 200°C or higher, even more preferably 220°C or higher, and preferably 500°C or lower, more preferably 450°C or lower, even more preferably 400°C or lower, and even more preferably 350°C or lower.

[0036] The heat treatment time in step (B) is not particularly limited as long as it is sufficient to obtain a sulfide-based inorganic solid electrolyte material in the desired glass-ceramic state. However, from the viewpoint of further improving the lithium-ion conductivity of the sulfide-based inorganic solid electrolyte material of this embodiment, it is preferably 0.5 hours or more, more preferably 1 hour or more, and preferably 24 hours or less, more preferably 3 hours or less. Furthermore, the method of heat treatment in step (B) is not particularly limited, but for example, a heating furnace or a firing furnace can be used. The temperature, time, and other conditions during such heating can be appropriately adjusted to optimize the properties of the sulfide-based inorganic solid electrolyte material of this embodiment.

[0037] Furthermore, the heat treatment in step (B) is preferably carried out under an inert gas atmosphere from the viewpoint of preventing deterioration (e.g., oxidation) of the sulfide-based inorganic solid electrolyte material. Examples of inert gases used when heating glassy sulfide-based inorganic solid electrolyte materials include argon gas, helium gas, and nitrogen gas. These inert gases are preferably of high purity to prevent contamination of the product with impurities, and their dew point is preferably -30°C or lower, more preferably -70°C or lower, and particularly preferably -80°C or lower to avoid contact with moisture. The method of introducing the inert gas into the mixed system is not particularly limited as long as the mixed system is filled with an inert gas atmosphere, but examples include purging the inert gas and continuously introducing a constant amount of inert gas.

[0038] (Process (C)) In the method for producing a sulfide-based inorganic solid electrolyte material of this embodiment, a further step (C) of crushing, classifying, or granulating the obtained sulfide-based inorganic solid electrolyte material in a glass or glass ceramic state may be performed as needed. For example, by crushing to produce fine particles and then adjusting the particle size by classification or granulation, a sulfide-based inorganic solid electrolyte material having a desired particle size can be obtained. The crushing method is not particularly limited, and known crushing methods such as mixers, air jets, mortars, rotary mills, and coffee mills can be used. The classification method is also not particularly limited, and known methods such as sieving can be used. These grinding or classification processes are preferably carried out under an inert gas atmosphere or a vacuum atmosphere, as this prevents contact with moisture in the air.

[0039] [Sulfide-based inorganic solid electrolyte material] The sulfide-based inorganic solid electrolyte material of this embodiment can be obtained by the method for producing the sulfide-based inorganic solid electrolyte material of this embodiment. The sulfide-based inorganic solid electrolyte material of this embodiment can be used in any application requiring lithium-ion conductivity, and is preferably used in lithium-ion batteries, more preferably in all-solid-state lithium-ion batteries.

[0040] The lithium ion conductivity of the sulfide-based inorganic solid electrolyte material of this embodiment, measured by the method described in <Measurement of Lithium Ion Conductivity> below, is preferably 1.0 × 10⁻⁶, from the viewpoint of further improving the input / output characteristics of the lithium-ion battery. -3 S / cm or more, more preferably 1.1 × 10 -3 S / cm or more, more preferably 1.2 × 10 -3 S / cm or more, more preferably 1.3 × 10 -3 S / cm or more, more preferably 1.4 × 10 -3 It is S / cm or higher. Furthermore, the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material in this embodiment is not particularly limited, but for example, 1.0 × 10⁻⁶ -2 It is less than or equal to S / cm, and 5.0 × 10-3 It may be less than or equal to S / cm, 3.0 × 10 -3 It may be less than or equal to S / cm, 2.0 × 10 -3 It is also acceptable if the S / cm is less than or equal to 1 / cm. <Measurement of lithium-ion conductivity> First, 110 mg of sulfide-based inorganic solid electrolyte material is pressed at 270 MPa for 10 minutes to obtain a disc-shaped sample with a diameter of 9.5 mm and a thickness of 1 mm. Next, using an electrochemical measuring device, the lithium ion conductivity of the obtained disc-shaped sample is measured by AC impedance method, with Li foil used as the electrode, under the conditions of an applied voltage of 10 mV, a measurement frequency range of 0.1 Hz to 3 MHz, and a measurement temperature of 27°C. Lithium ion conductivity can be measured using electrochemical measuring instruments such as the SP-300 potentiostat / galvanostat manufactured by Biologic.

[0041] The sulfide-based inorganic solid electrolyte material of this embodiment preferably exhibits good electrochemical stability. Here, electrochemical stability refers, for example, to the property of being resistant to oxidation and reduction over a wide voltage range. More specifically, in the sulfide-based inorganic solid electrolyte material of this embodiment, the maximum value of the oxidative decomposition current of the sulfide-based inorganic solid electrolyte material measured under conditions of a temperature of 25°C, a sweep voltage range of 0 to 5V, and a voltage sweep rate of 5mV / sec is preferably 0.50μA or less, more preferably 0.20μA or less, even more preferably 0.10μA or less, even more preferably 0.05μA or less, and even more preferably 0.03μA or less. It is preferable that the maximum value of the oxidative decomposition current of the sulfide-based inorganic solid electrolyte material is less than or equal to the above upper limit, because this can suppress the oxidative decomposition of the sulfide-based inorganic solid electrolyte material in the lithium-ion battery. The lower limit of the maximum value of the oxidative decomposition current of sulfide-based inorganic solid electrolyte materials is not particularly limited, but for example, it is 0.0001 μA or higher.

[0042] The sulfide-based inorganic solid electrolyte material of this embodiment can be used in any application requiring lithium-ion conductivity. In particular, the sulfide-based inorganic solid electrolyte material of this embodiment is preferably used in lithium-ion batteries. More specifically, it is preferably used in the positive electrode active material layer, negative electrode active material layer, electrolyte layer, etc., of a lithium-ion battery. Furthermore, the sulfide-based inorganic solid electrolyte material of this embodiment is suitably used in the positive electrode active material layer, negative electrode active material layer, solid electrolyte layer, etc., that constitute an all-solid-state lithium-ion battery, and is more suitably used in the solid electrolyte layer that constitutes an all-solid-state lithium-ion battery. An example of an all-solid-state lithium-ion battery using the sulfide-based inorganic solid electrolyte material of this embodiment is one in which the positive electrode, the solid electrolyte layer, and the negative electrode are stacked in this order.

[0043] In this embodiment, the sulfide-based inorganic solid electrolyte material preferably contains Li, P, and S as constituent elements, from the viewpoint of further improving electrochemical stability, stability in moisture and air, and handling ease.

[0044] Furthermore, from the viewpoint of improving the balance of lithium ion conductivity and electrochemical stability, and from the viewpoint of further improving stability and handling in moisture or air, the sulfide-based inorganic solid electrolyte material of this embodiment has a molar ratio Li / P of Li content to P content that is preferably 1.0 or more and 5.0 or less, more preferably 2.0 or more and 4.0 or less, even more preferably 2.5 or more and 3.8 or less, even more preferably 2.7 or more and 3.6 or less, even more preferably 2.8 or more and 3.5 or less, even more preferably 2.9 or more and 3.4 or less, and even more preferably 3.0 or more and 3.3 or less, and the molar ratio S / P of S content to P content is preferably 2.0 or more and 6.0 or less, more preferably 3.0 or more and 5.0 or less, even more preferably 3.5 or more and 4.5 or less, even more preferably 3.8 or more and 4.2 or less, even more preferably 3.9 or more and 4.1 or less, and even more preferably 4.0. The sulfide-based inorganic solid electrolyte material of this embodiment incorporates Li3PS4 and Li3PS4, from the viewpoint of improving the balance of lithium ion conductivity and electrochemical stability, as well as further improving stability and handling in moisture or air. 10 P3S 12 Preferably, it includes one or two selected from the group consisting of the following: Here, the content of Li, P, and S in the sulfide-based inorganic solid electrolyte material of this embodiment can be determined, for example, by ICP emission spectroscopy or X-ray analysis.

[0045] The sulfide-based inorganic solid electrolyte material of this embodiment can take the form of particulate matter, for example. The particulate sulfide-based inorganic solid electrolyte material in this embodiment is not particularly limited, but the average particle diameter d in the weight-based particle size distribution measured by laser diffraction scattering particle size distribution analysis is important. 50 However, the particle size is preferably 1 μm to 100 μm, more preferably 3 μm to 80 μm, and even more preferably 5 μm to 60 μm. Average particle size d of sulfide-based inorganic solid electrolyte material 50 By keeping the above range, good handling performance can be maintained while further improving lithium-ion conductivity.

[0046] [Sulfide-based inorganic solid electrolyte] The sulfide-based inorganic solid electrolyte of this embodiment includes the sulfide-based inorganic solid electrolyte material of this embodiment. The sulfide-based inorganic solid electrolyte of this embodiment may include, for example, a different type of solid electrolyte material as a component other than the sulfide-based inorganic solid electrolyte material of this embodiment, as long as it does not impair the objectives of the present invention. As a type of solid electrolyte material different from the sulfide-based inorganic solid electrolyte material of the present embodiment, there is no particular limitation as long as it has ion conductivity and insulation, but generally, those used in lithium-ion batteries can be used. For example, inorganic solid electrolyte materials such as sulfide-based inorganic solid electrolyte materials of a type different from the sulfide-based inorganic solid electrolyte material of the present embodiment, oxide-based inorganic solid electrolyte materials, and other lithium-based inorganic solid electrolyte materials; organic solid electrolyte materials such as polymer electrolytes can be mentioned.

[0047] Examples of sulfide-based inorganic solid electrolyte materials of a type different from the sulfide-based inorganic solid electrolyte material of the present embodiment include, for example, Li2S-SiS2 materials, Li2S-GeS2 materials, Li2S-Al2S3 materials, Li2S-SiS2-Li3PO4 materials, and the like. These may be used alone or in combination of two or more. Here, for example, the Li2S-SiS2 material means a solid electrolyte material obtained by chemically reacting an inorganic composition containing at least Li2S (lithium sulfide) and SiS2 with each other by mechanical treatment. Here, lithium sulfide includes polysulfide lithium.

[0048] [[ID=^11]] Examples of oxide-based inorganic solid electrolyte materials include NASICON-type materials such as LiTi2(PO4)3, LiZr2(PO4)3, LiGe2(PO4)3; perovskite-type materials such as (La 0.5+x Li 0.5-3x )TiO3; Li2O-P2O5 materials; Li2O-P2O5-Li3N materials; and the like. Examples of other lithium-based inorganic solid electrolyte materials include, for example, LiPON, LiNbO3, LiTaO3, Li3PO4, LiPO 4-x N x (x is 0 < x ≤ 1), LiN, LiI, LISICON, and the like. Furthermore, glass ceramics obtained by precipitating crystals of inorganic solid electrolytes can also be used as inorganic solid electrolyte materials.

[0049] As the above-mentioned organic solid electrolyte material, for example, polymer electrolytes such as dry polymer electrolytes and gel electrolytes can be used. As the polymer electrolyte, one commonly used in lithium-ion batteries can be used.

[0050] [Sulfide-based inorganic solid electrolyte membrane] The sulfide-based inorganic solid electrolyte membrane of this embodiment mainly contains the sulfide-based inorganic solid electrolyte of this embodiment. The sulfide-based inorganic solid electrolyte membrane of this embodiment can be used, for example, in the solid electrolyte layer that constitutes an all-solid-state lithium-ion battery. An example of an all-solid-state lithium-ion battery to which the solid electrolyte membrane of this embodiment is applied is one in which the positive electrode, the solid electrolyte layer, and the negative electrode are stacked in this order. In this case, the solid electrolyte layer is made of the solid electrolyte membrane.

[0051] The average thickness of the sulfide-based inorganic solid electrolyte membrane in this embodiment is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more, from the viewpoint of further suppressing the loss of solid electrolyte and the occurrence of cracks on the surface of the solid electrolyte membrane. The average thickness of the sulfide-based inorganic solid electrolyte membrane in this embodiment is preferably 500 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less. This further reduces the impedance of the solid electrolyte membrane, and as a result, the battery characteristics of the resulting all-solid-state lithium-ion battery can be further improved.

[0052] The sulfide-based inorganic solid electrolyte membrane of this embodiment is preferably a pressure-molded body of particulate solid electrolyte. That is, it is preferable to pressurize the particulate solid electrolyte to form a solid electrolyte membrane with a certain strength due to the anchoring effect between the solid electrolyte materials. By forming a pressure-molded body, bonding occurs between the solid electrolytes, and the strength of the resulting solid electrolyte membrane is further increased. As a result, the loss of solid electrolyte and the occurrence of cracks on the surface of the solid electrolyte membrane can be further suppressed.

[0053] The content of the sulfide-based inorganic solid electrolyte material in the sulfide-based inorganic solid electrolyte membrane of this embodiment is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more. This improves the contact between solid electrolytes and reduces the interfacial contact resistance of the solid electrolyte membrane, resulting in a further improvement in the lithium ion conductivity of the solid electrolyte membrane. By using such a solid electrolyte membrane with excellent lithium ion conductivity, the battery characteristics of the resulting all-solid-state lithium-ion battery can be further improved. The upper limit of the content of the sulfide-based inorganic solid electrolyte material of this embodiment in the sulfide-based inorganic solid electrolyte membrane of this embodiment is not particularly limited, but for example, it is 100% by mass or less.

[0054] The planar shape of the sulfide-based inorganic solid electrolyte membrane in this embodiment is not particularly limited and can be appropriately selected according to the shape of the electrodes and current collectors, but for example, it can be rectangular.

[0055] The sulfide-based inorganic solid electrolyte membrane of this embodiment may contain a binder resin, but the binder resin content is preferably less than 0.5% by mass, more preferably less than 0.1% by mass, even more preferably less than 0.05% by mass, and even more preferably less than 0.01% by mass. Furthermore, it is even more preferable that the solid electrolyte membrane of this embodiment is substantially free of binder resin, and even more preferable that it is completely free of binder resin. This improves the contact between solid electrolytes and reduces the interfacial contact resistance of the solid electrolyte membrane. As a result, the lithium ion conductivity of the solid electrolyte membrane can be further improved. By using such a solid electrolyte membrane with improved lithium ion conductivity, the battery characteristics of the resulting all-solid-state lithium-ion battery can be improved. Furthermore, "substantially free of binder resin" means that it may contain binder resin to an extent that does not impair the effects of this embodiment. Also, when an adhesive resin layer is provided between the solid electrolyte layer and the positive or negative electrode, the adhesive resin originating from the adhesive resin layer that is present near the interface between the solid electrolyte layer and the adhesive resin layer is excluded from "binder resin in the solid electrolyte membrane".

[0056] The above-mentioned binder resin refers to a binder commonly used in lithium-ion batteries to bond inorganic solid electrolyte materials together. Examples include polyvinyl alcohol, polyacrylic acid, carboxymethylcellulose, polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, and polyimide.

[0057] The sulfide-based inorganic solid electrolyte membrane of this embodiment can be obtained, for example, by depositing particulate solid electrolyte in a film-like manner on the cavity surface of a mold or on the surface of a substrate, and then pressurizing the solid electrolyte deposited in a film-like manner. The method for pressurizing the solid electrolyte is not particularly limited. For example, if particulate solid electrolyte is deposited on the cavity surface of a mold, pressing with a mold and a press die can be used. If particulate solid electrolyte is deposited on the surface of a substrate, pressing with a mold and a press die, a roll press, a flat plate press, etc., can be used. The pressure applied to pressurize the solid electrolyte is, for example, between 10 MPa and 500 MPa.

[0058] Furthermore, if necessary, the inorganic solid electrolyte deposited in a film may be pressurized and heated. Heating and pressurizing will cause fusion and bonding between the solid electrolytes, further increasing the strength of the resulting solid electrolyte film. As a result, the loss of solid electrolytes and the occurrence of cracks on the surface of the solid electrolyte film can be further suppressed. The temperature at which the solid electrolyte is heated is, for example, between 40°C and 500°C.

[0059] [Lithium-ion battery] The lithium-ion battery of this embodiment is, for example, a lithium-ion battery comprising a positive electrode including a positive electrode active material layer, an electrolyte layer, and a negative electrode including a negative electrode active material layer, wherein at least one of the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer contains the sulfide-based inorganic solid electrolyte material of this embodiment.

[0060] Figure 1 is a cross-sectional view showing an example of the structure of the lithium-ion battery of this embodiment. The lithium-ion battery 100 of this embodiment includes, for example, a positive electrode 110 containing a positive electrode active material layer 101, an electrolyte layer 120, and a negative electrode 130 containing a negative electrode active material layer 103. Furthermore, at least one of the positive electrode active material layer 101, the negative electrode active material layer 103, and the electrolyte layer 120 contains the sulfide-based inorganic solid electrolyte material of this embodiment described above. It is also preferable that all of the positive electrode active material layer 101, the negative electrode active material layer 103, and the electrolyte layer 120 contain the sulfide-based inorganic solid electrolyte material of this embodiment described above.

[0061] In this embodiment, unless otherwise specified, the layer containing the positive electrode active material is referred to as the positive electrode active material layer 101. The positive electrode 110 may optionally include a current collector 105 in addition to the positive electrode active material layer 101, or it may not include the current collector 105. In this embodiment, unless otherwise specified, the layer containing the negative electrode active material is referred to as the negative electrode active material layer 103. The negative electrode 130 may optionally include a current collector 105 in addition to the negative electrode active material layer 103, or it may not include the current collector 105.

[0062] The shape of the lithium-ion battery 100 in this embodiment is not particularly limited and may include cylindrical, coin-shaped, prismatic, film-shaped, or any other shape.

[0063] The lithium-ion battery 100 of this embodiment is manufactured according to generally known methods. For example, it is manufactured by stacking a positive electrode 110, an electrolyte layer 120, and a negative electrode 130, forming them into a cylindrical, coin-shaped, prismatic, film-shaped, or any other arbitrary shape, and sealing in a non-aqueous electrolyte as needed.

[0064] <Positive electrode> The positive electrode 110 is not particularly limited, and one commonly used in lithium-ion batteries can be used. The positive electrode 110 is not particularly limited, but can be manufactured according to generally known methods. For example, it can be obtained by forming a positive electrode active material layer 101 containing a positive electrode active material on the surface of a current collector 105 such as aluminum foil. The thickness and density of the positive electrode active material layer 101 are determined appropriately according to the intended use of the battery and are not particularly limited; they can be set in accordance with generally known information.

[0065] The positive electrode active material layer 101 contains the positive electrode active material. The positive electrode active material is not particularly limited as long as it is a positive electrode active material that can be used in the positive electrode of a lithium-ion battery, but examples include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), solid solution oxide (Li2MnO3-LiMO2 (M=Co, Ni, etc.)), lithium-manganese-nickel oxide (LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 Composite oxides such as O2, olivine-type lithium phosphate oxide (LiFePO4); conductive polymers such as polyaniline and polypyrrole; sulfide-based cathode active materials such as Li2S, CuS, Li-Cu-S compounds, TiS2, FeS, MoS2, Li-Mo-S compounds, Li-Ti-S compounds, Li-VS compounds, and Li-Fe-S compounds; materials using sulfur as an active material, such as sulfur-impregnated acetylene black, sulfur-impregnated porous carbon, and mixed powders of sulfur and carbon; etc. can be used.

[0066] The positive electrode active material layer 101 is not particularly limited, but may include one or more materials selected from, for example, binder resins, thickeners, conductive additives, and solid electrolyte materials, as components other than the positive electrode active material. Each of these materials will be described below.

[0067] The positive electrode active material layer 101 may also contain a binder resin that serves to bond the positive electrode active materials together and to the current collector 105. The binder resin in this embodiment is not particularly limited as long as it is a normal binder resin that can be used in lithium-ion batteries, but examples include polyvinyl alcohol, polyacrylic acid, carboxymethylcellulose, polytetrafluoroethylene, polyvinylidene fluoride, styrene-butadiene rubber, and polyimide. These binders may be used individually or in combination of two or more.

[0068] The positive electrode active material layer 101 may contain a thickening agent to ensure the fluidity of the slurry suitable for coating. The thickening agent is not particularly limited as long as it is a conventional thickening agent usable in lithium-ion batteries, but examples include cellulosic polymers such as carboxymethylcellulose, methylcellulose, and hydroxypropylcellulose, and their ammonium salts and alkali metal salts, water-soluble polymers such as polycarboxylic acids, polyethylene oxide, polyvinylpyrrolidone, polyacrylates, and polyvinyl alcohol. These thickening agents may be used individually or in combination of two or more.

[0069] The positive electrode active material layer 101 may contain a conductive additive from the viewpoint of improving the conductivity of the positive electrode 110. The conductive additive is not particularly limited as long as it is a conventional conductive additive that can be used in lithium-ion batteries, but examples include carbon black such as acetylene black and kechen black, and carbon materials such as vapor-processed carbon fibers.

[0070] The positive electrode of the lithium-ion battery in this embodiment may contain a solid electrolyte that includes the sulfide-based inorganic solid electrolyte material of this embodiment, or it may contain a solid electrolyte that includes a different type of solid electrolyte material than the sulfide-based inorganic solid electrolyte material of this embodiment. As a solid electrolyte material of a different type from the sulfide-based inorganic solid electrolyte material of this embodiment, there are no particular limitations as long as it has ionic conductivity and insulating properties, but those commonly used in lithium-ion batteries can be used. For example, examples include inorganic solid electrolyte materials such as sulfide-based inorganic solid electrolyte materials of a different type from the sulfide-based inorganic solid electrolyte material of this embodiment, oxide-based inorganic solid electrolyte materials, and other lithium-based inorganic solid electrolyte materials; and organic solid electrolyte materials such as polymer electrolytes. More specifically, the solid electrolyte materials mentioned in the description of the sulfide-based inorganic solid electrolyte of this embodiment above can be used.

[0071] The mixing ratio of the various materials in the positive electrode active material layer 101 is determined appropriately according to the intended use of the battery and is not particularly limited; it can be set in accordance with generally known information.

[0072] <Negative electrode> The negative electrode 130 is not particularly limited, and one commonly used in lithium-ion batteries can be used. The negative electrode 130 is not particularly limited, but can be manufactured according to generally known methods. For example, it can be obtained by forming a negative electrode active material layer 103 containing a negative electrode active material on the surface of a current collector 105 made of copper or the like. The thickness and density of the negative electrode active material layer 103 are determined appropriately according to the intended use of the battery and are not particularly limited; they can be set in accordance with generally known information.

[0073] The negative electrode active material layer 103 contains the negative electrode active material. The above-mentioned negative electrode active material is not particularly limited as long as it is a negative electrode active material that can be used in the negative electrode of a lithium-ion battery, but examples include: carbonaceous materials such as natural graphite, artificial graphite, resin carbon, carbon fiber, activated carbon, hard carbon, and soft carbon; metallic materials mainly consisting of lithium, lithium alloys, tin, tin alloys, silicon, silicon alloys, gallium, gallium alloys, indium, indium alloys, aluminum, and aluminum alloys; conductive polymers such as polyacene, polyacetylene, and polypyrrole; and lithium titanium composite oxide (e.g., Li4Ti5O 12Examples include the following. These negative electrode active materials may be used individually or in combination of two or more.

[0074] The negative electrode active material layer 103 is not particularly limited, but may include one or more materials selected from, for example, binder resins, thickeners, conductive additives, and solid electrolyte materials, as components other than the negative electrode active material. These materials are not particularly limited, but examples include those similar to the materials used for the positive electrode 110 described above. The mixing ratio of the various materials in the negative electrode active material layer 103 is determined appropriately according to the intended use of the battery and is not particularly limited; it can be set in accordance with generally known information.

[0075] The negative electrode of the lithium-ion battery in this embodiment may contain a solid electrolyte that includes the sulfide-based inorganic solid electrolyte material of this embodiment, or it may contain a solid electrolyte that includes a different type of solid electrolyte material than the sulfide-based inorganic solid electrolyte material of this embodiment. As a solid electrolyte material of a different type from the sulfide-based inorganic solid electrolyte material of this embodiment, there are no particular limitations as long as it has ionic conductivity and insulating properties, but those commonly used in lithium-ion batteries can be used. For example, examples include inorganic solid electrolyte materials such as sulfide-based inorganic solid electrolyte materials of a different type from the sulfide-based inorganic solid electrolyte material of this embodiment, oxide-based inorganic solid electrolyte materials, and other lithium-based inorganic solid electrolyte materials; and organic solid electrolyte materials such as polymer electrolytes. More specifically, the solid electrolyte materials mentioned in the description of the sulfide-based inorganic solid electrolyte of this embodiment above can be used.

[0076] <Electrolyte layer> Next, the electrolyte layer 120 will be described. The electrolyte layer 120 is a layer formed between the positive electrode active material layer 101 and the negative electrode active material layer 103. Examples of the electrolyte layer 120 include a separator impregnated with a non-aqueous electrolyte, or a solid electrolyte layer containing a solid electrolyte.

[0077] The separator in this embodiment is not particularly limited as long as it electrically insulates the positive electrode 110 and the negative electrode 130 and has the function of permeating lithium ions, but for example, a porous film can be used.

[0078] Microporous polymer films are preferably used as porous membranes, and examples of materials include polyolefins, polyimides, polyvinylidene fluoride, and polyesters. In particular, porous polyolefin films are preferred, specifically porous polyethylene films and porous polypropylene films.

[0079] The non-aqueous electrolyte mentioned above is a solution in which an electrolyte is dissolved in a solvent. Any known lithium salt can be used as the electrolyte, and the appropriate one should be selected according to the type of active material. For example, LiClO4, LiBF6, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiB 10 Cl 10 Examples include LiAlCl4, LiCl, LiBr, LiB(C2H5)4, CF3SO3Li, CH3SO3Li, LiCF3SO3, LiC4F9SO3, Li(CF3SO2)2N, and lithium lower fatty acid carboxylates.

[0080] The solvent used to dissolve the above electrolyte is not particularly limited as long as it is a liquid commonly used to dissolve electrolytes, and includes carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), and vinylene carbonate (VC); lactones such as γ-butyrolactone and γ-valerolactone; and ethers such as trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, 2-ethoxyethane, tetrahydrofuran, and 2-methyltetrahydrofuran. Examples include sulfoxides such as dimethyl sulfoxide; oxolanes such as 1,3-dioxolane and 4-methyl-1,3-dioxolane; nitrogen-containing compounds such as acetonitrile, nitromethane, formamide, and dimethylformamide; organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, and ethyl propionate; phosphate triesters and diglymes; triglimes; sulfolanes such as sulfolane and methylsulfolane; oxazolidinones such as 3-methyl-2-oxazolidinone; and sultones such as 1,3-propanesultone, 1,4-butanesultone, and naphthalsultone. These may be used individually or in combination of two or more.

[0081] The solid electrolyte layer in this embodiment is a layer formed between the positive electrode active material layer 101 and the negative electrode active material layer 103, and is a layer formed of a solid electrolyte containing a solid electrolyte material. The solid electrolyte contained in the solid electrolyte layer is not particularly limited as long as it has lithium ion conductivity, but in this embodiment, it is preferable that it is a solid electrolyte containing the sulfide-based inorganic solid electrolyte material of this embodiment. The solid electrolyte content in the solid electrolyte layer of the lithium-ion battery of this embodiment is not particularly limited as long as the desired insulation properties can be obtained, but is preferably 10% to 100% by volume, preferably 50% to 100% by volume, preferably 70% to 100% by volume, preferably 90% to 100% by volume, and more preferably substantially free of components other than the solid electrolyte. Furthermore, "substantially free of components other than solid electrolytes" means that components other than solid electrolytes may be included to an extent that does not impair the effects of this embodiment.

[0082] The solid electrolyte contained in the solid electrolyte layer of the lithium-ion battery of this embodiment is not particularly limited as long as it has lithium-ion conductivity, but it is preferably a sulfide-based inorganic solid electrolyte of this embodiment.

[0083] The content of the sulfide-based inorganic solid electrolyte of this embodiment in the solid electrolyte layer of the lithium-ion battery of this embodiment is not particularly limited as long as the desired insulation properties can be obtained, but is preferably 10% to 100% by volume, more preferably 50% to 100% by volume, even more preferably 70% to 100% by volume, and even more preferably 90% to 100% by volume, and even more preferably substantially free of components other than the sulfide-based inorganic solid electrolyte of this embodiment. Furthermore, "substantially free of components other than the sulfide-based inorganic solid electrolyte of this embodiment" means that components other than the sulfide-based inorganic solid electrolyte of this embodiment may be included to the extent that the effects of this embodiment are not impaired.

[0084] The solid electrolyte layer of the lithium-ion battery in this embodiment may contain a binder resin. By including a binder resin, a flexible solid electrolyte layer can be obtained. Examples of binder resins include fluorine-containing binders such as polytetrafluoroethylene and polyvinylidene fluoride.

[0085] The thickness of the solid electrolyte layer of the lithium-ion battery in this embodiment is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.1 μm or more and 300 μm or less.

[0086] The embodiments of the present invention have been described above, but these are merely examples, and various other configurations can also be adopted. It should be noted that the present invention is not limited to the embodiments described above, and any modifications, improvements, etc., that can achieve the objectives of the present invention are included in the present invention. [Examples]

[0087] The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto. [1]Measurement method First, the measurement methods in the following examples and comparative examples will be explained.

[0088] (1)Solid 31 P-NMR measurement The phosphorus sulfide compositions used in the examples and comparative examples were prepared as follows: 31 P-NMR measurements were performed on each sample. First, the test sample was filled into a 3.2 mm diameter sample tube in a glow box purged with N2 gas, and the tube was rotated at a magic angle (54.7 degrees) relative to the external magnetic field (Magic Angle Spinning: MAS). Measurements were then performed under the following conditions. Equipment: JNM-ECA-600 manufactured by JEOL RESONANCE Co., Ltd. Observation frequency: 242.95MHz Pulse width: 90° pulse Pulse waiting time: 2800 seconds Total number of times: 64 Measurement mode: Single pulse method MAS speed: 12kHz Standard substance: (NH4)2HPO4·1.33ppm Test sample 31 Regarding the peaks detected in the P-NMR spectrum, see Reference 1 "Hellmut Eckert, Cheryl S. Liang and Galen D. Stucky: 31 P magic angle spinning NMR of crystalline phosphorous sulfides. Correlation of 31Referring to "P chemical shielding tensors with local environments, J. Phys. Chem, 1989, 93, 452-457," waveform separation was performed using a Gaussian function based on the peak assignments below, and the integral value of each peak was calculated. The content ratio was calculated from the obtained integral values ​​and the molecular weight of each component. The chemical shifts for P2S5 are 40-52 ppm, P4S9 are 52-70 ppm, P4S7 are 80-90 ppm, 90-100 ppm, and 110-115 ppm, and P4S3 are 80-90 ppm and 90-100 ppm.

[0089] (2) Measurement of the composition ratio of sulfide-based inorganic solid electrolyte materials Using an ICP emission spectrometer (SPS3000, manufactured by Seiko Instruments Corporation), the mass percentages of Li, P, and S in the sulfide-based inorganic solid electrolyte materials obtained in the examples and comparative examples were determined by ICP emission spectroscopy, and the molar ratios of each element were calculated based on these values.

[0090] (3) Measurement of lithium ion conductivity The lithium ion conductivity of the sulfide-based inorganic solid electrolyte materials obtained in the examples and comparative examples was measured using the method described below. The results are shown in Table 1. First, 110 mg of sulfide-based inorganic solid electrolyte material was pressed at 270 MPa for 10 minutes to obtain a disc-shaped sample with a diameter of 9.5 mm and a thickness of 1 mm. Next, using a Biologic SP-300 potentiostat / galvanostat, the lithium ion conductivity of the obtained disc-shaped sample was measured by AC impedance method, with Li foil as the electrode, under the conditions of an applied voltage of 10 mV, a measurement frequency range of 0.1 Hz to 3 MHz, and a measurement temperature of 27°C.

[0091] (4) X-ray diffraction analysis The X-ray diffraction spectra of the phosphorus sulfide compositions used in the examples and comparative examples were measured using the method described below. Using an X-ray diffractometer (Rigaku Corporation, RINT2000), under the following conditions: voltage 40kV, current 40mA, divergence slit 1°, divergence slit vertical limit 10mm, scattering slit 1°, receiving slit 0.3mm, measurement start angle 3°, measurement end angle 90°, and scan speed 0.2° / min, CuKα rays were used as the radiation source. The phosphorus sulfide composition was placed in an airtight sample holder filled with argon gas, and the X-ray diffraction spectrum of the phosphorus sulfide composition was obtained. Figure 2 shows the X-ray diffraction spectra of the phosphorus sulfide compositions used in each example and comparative example. Figure 3 shows a magnified view of the X-ray diffraction spectra of the phosphorus sulfide compositions used in each example and comparative example in the range of 2θ = 20 to 30°. Table 1 shows the number of peaks in the range of 2θ = 22.5° to 24.5° in the X-ray diffraction spectra of the phosphorus sulfide compositions used in the examples and comparative example.

[0092] [2][Manufacturing of sulfide-based inorganic solid electrolyte materials] <Example 1> (Li 10 P3S 12 (Manufacturing) Under an argon atmosphere at 20°C, 1.27 g of powdered phosphorus sulfide composition 1 (Perimeter Solutions, product name: Normal / S, Lot. 22D1218453), 0.79 g of Li2S (Furukawa Machinery & Metal Co., Ltd., purity 99.9%), and 0.04 g of Li3N (Furukawa Machinery & Metal Co., Ltd.) were weighed. Next, under an argon atmosphere at 20°C, the weighed phosphorus sulfide composition 1, Li2S, and Li3N were mixed in a mortar while being ground to obtain mixture (a1). 2.1 g of the obtained mixture (a1) was mechanochemically treated using a planetary ball mill (using a 45 mL zirconia pot and 18 10 mm diameter zirconia balls) under an argon atmosphere at 20°C to obtain material (b1). More specifically, the mixture (a1) was mechanically milled at 400 rpm for 10 minutes, followed by a 5-minute resting period, and this process was repeated 120 times to obtain material (b1). During the mechanical milling process, 15 hours after the start of the mechanochemical treatment, powder adhering to the zirconia pot wall and the zirconia ball surface was scraped off. The obtained material (b1) is placed in a carbon crucible and heated in a furnace under an argon atmosphere at 270°C for 2 hours, Li 10 P3S 12 A sulfide-based inorganic solid electrolyte material represented by [formula] was obtained.

[0093] (Manufacturing of Li3PS4) Under an argon atmosphere at 20°C, 1.3 g of powdered phosphorus sulfide composition 1 (manufactured by Perimeter Solutions, product name: Normal / S, Lot. 22D1218453) and 0.8 g of Li2S (manufactured by Furukawa Machinery & Metal Co., Ltd., purity 99.9%) were weighed. Next, under an argon atmosphere at 20°C, the weighed phosphorus sulfide composition 1 and Li2S were mixed in a mortar while being ground to obtain mixture (a2). 2.1 g of the obtained mixture (a2) was mechanochemically treated using a planetary ball mill (using a 45 mL zirconia pot and 18 10 mm diameter zirconia balls) under an argon atmosphere at 20°C to obtain material (b2). More specifically, the mixture (a2) was mechanically milled at 400 rpm for 10 minutes, followed by a 5-minute standing period, and this process was repeated 120 times to obtain material (b2). During the mechanical milling process, 15 hours after the start of the mechanochemical treatment, powder adhering to the zirconia pot wall and the zirconia ball surface was scraped off. The obtained material (b2) was placed in a carbon crucible and heat-treated in a furnace under an argon atmosphere at 270°C for 2 hours to obtain a sulfide-based inorganic solid electrolyte material represented by Li3PS4.

[0094] <Example 2> Except for using powdered phosphorus sulfide composition 2 (manufactured by Kanto Chemical Co., Ltd., Grade 1, Lot. 607H1801) instead of phosphorus sulfide composition 1, the same procedure as in Example 1 was used for Li 10 P3S 12 We obtained a sulfide-based inorganic solid electrolyte material represented by and a sulfide-based inorganic solid electrolyte material represented by Li3PS4, respectively.

[0095] <Comparative Example 1> 50 g of powdered phosphorus sulfide composition 1 (manufactured by Perimeter Solutions, product name: Normal / S, Lot. 22D1218453) was placed in a quartz container and set in a vacuum heating device (manufactured by Furukawa Machinery & Metal Co., Ltd.), and heated at 300°C for 2 hours under a reduced pressure of -0.094 MPa. Next, the quartz container, heated to 300°C, was immersed in a bucket of water with all valves closed to maintain a vacuum, and rapidly cooled to 30°C. The components that accumulated at the bottom of the quartz container after cooling to 30°C were designated as "Phosphorus Sulfide Composition 3". Next, the same procedure as in Example 1 was followed, except that phosphorus sulfide composition 3 was used instead of phosphorus sulfide composition 1. 10 P3S 12 We obtained a sulfide-based inorganic solid electrolyte material represented by and a sulfide-based inorganic solid electrolyte material represented by Li3PS4, respectively.

[0096] <Comparative Example 2> Except for using powdered phosphorus sulfide composition 4 (Perimeter Solutions, product name: Normal / eXG, Lot. 22D1222095) instead of phosphorus sulfide composition 1, the same procedure as in Example 1 was used for Li 10 P3S 12 We obtained a sulfide-based inorganic solid electrolyte material represented by and a sulfide-based inorganic solid electrolyte material represented by Li3PS4, respectively.

[0097] [Table 1]

[0098] The sulfide-based inorganic solid electrolyte material obtained by the manufacturing method of the example showed improved lithium ion conductivity compared to the sulfide-based inorganic solid electrolyte material obtained by the manufacturing method of the comparative example. [Explanation of symbols]

[0099] 100 Lithium-ion batteries 101 Cathode active material layer 103 Negative electrode active material layer 105 Current collector 110 Positive electrode 120 Electrolyte Layer 130 Negative electrode

Claims

1. The process includes a step of obtaining a sulfide-based inorganic solid electrolyte material in a glassy state by mechanically treating a raw material composition for a sulfide-based inorganic solid electrolyte material containing lithium sulfide and a phosphorus sulfide composition, thereby causing each component to react chemically and vitrify. A method for producing a sulfide-based inorganic solid electrolyte material, wherein the phosphorus sulfide composition has three or more peaks in the X-ray diffraction spectrum obtained by the method described in <X-ray diffraction analysis> below, within the range of 2θ = 22.5° to 24.5°. <X-ray diffraction analysis> Using an X-ray diffractometer, under the following conditions: voltage 40 kV, current 40 mA, divergence slit 1°, divergence slit vertical limit 10 mm, scattering slit 1°, receiving slit 0.3 mm, measurement start angle 3°, measurement end angle 90°, and scan speed 0.2° / min, CuKα rays were used as the radiation source, and the phosphorus sulfide composition was placed in an airtight sample holder filled with argon gas to obtain the X-ray diffraction spectrum of the phosphorus sulfide composition.

2. The phosphorus sulfide composition is P ２ S ５ A method for producing a sulfide-based inorganic solid electrolyte material according to claim 1, comprising:

3. The P in the phosphorus sulfide composition ２ S ５ A method for producing a sulfide-based inorganic solid electrolyte material according to claim 2, wherein the content of is 20% by mass or more.

4. A method for producing a sulfide-based inorganic solid electrolyte material according to claim 1 or 2, wherein the phosphorus sulfide composition is in powder form.

5. A method for producing a sulfide-based inorganic solid electrolyte material according to claim 1 or 2, wherein the mechanical treatment includes a mechanochemical treatment.

6. A method for producing a sulfide-based inorganic solid electrolyte material according to claim 1 or 2, further comprising the step of heat-treating the glassy sulfide-based inorganic solid electrolyte material in a range of 180°C to 500°C.

7. The lithium ion conductivity of the sulfide-based inorganic solid electrolyte material, as measured by the method described in <Measurement of Lithium Ion Conductivity> below, is 1.0 × 10⁻⁶. －３ A method for producing a sulfide-based inorganic solid electrolyte material according to claim 1 or 2, wherein the ratio is S / cm or higher. <Measurement of lithium-ion conductivity> First, 110 mg of sulfide-based inorganic solid electrolyte material is pressed at 270 MPa for 10 minutes to obtain a disc-shaped sample with a diameter of 9.5 mm and a thickness of 1 mm. Next, using an electrochemical measuring device, the lithium ion conductivity of the obtained disc-shaped sample is measured by AC impedance method with an applied voltage of 10 mV, a measurement frequency range of 0.1 Hz to 3 MHz, and a measurement temperature of 27°C, using Li foil as the electrode.

8. A sulfide-based inorganic solid electrolyte material obtained by the method for producing a sulfide-based inorganic solid electrolyte material according to claim 1 or 2.

9. A sulfide-based inorganic solid electrolyte comprising the sulfide-based inorganic solid electrolyte material described in claim 8.

10. A sulfide-based inorganic solid electrolyte membrane containing the sulfide-based inorganic solid electrolyte described in claim 9 as the main component.

11. A lithium-ion battery comprising a positive electrode containing a positive electrode active material layer, an electrolyte layer, and a negative electrode containing a negative electrode active material layer, A lithium-ion battery in which at least one of the positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer comprises the sulfide-based inorganic solid electrolyte material described in claim 8.

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