Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
  • H01M10/0562—Solid materials
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B25/00—Phosphorus; Compounds thereof
  • C01B25/14—Sulfur, selenium, or tellurium compounds of phosphorus
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
  • H01B1/10—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances sulfides
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/058—Construction or manufacture
  • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0065—Solid electrolytes
  • H01M2300/0068—Solid electrolytes inorganic
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to a solid electrolyte and a method for producing the same.
• a solid electrolyte for example, a sulfide solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S) and a halogen element has been proposed (see Patent Documents 1 and 2).
• the objective of the present invention is to provide a solid electrolyte in which the generation of hydrogen sulfide is suppressed.
• the present invention has been made based on the above findings, and provides an organic compound comprising lithium (Li), phosphorus (P), sulfur (S), halogen (X) and nitrogen (N), a molar ratio of the difference between the lithium (Li) element and the sulfur (S) element to the phosphorus (P) element is 1.5 or more and 2.2 or less;
• the above-mentioned problem is solved by providing a solid electrolyte in which the molar ratio of the sum of the lithium (Li) element and the halogen (X) element to the phosphorus (P) element is 7.1 or more and 10.0 or less.
• the present invention also provides a method for producing a solid electrolyte containing lithium (Li), phosphorus (P), sulfur (S), halogen (X) and nitrogen (N), comprising the steps of:
• the method includes a step of firing a raw material composition for the solid electrolyte,
• the raw material composition includes one or more compounds containing at least one of lithium (Li), phosphorus (P), sulfur (S), and a halogen (X), and also includes an ammonium halide, thereby providing a method for producing a solid electrolyte.
• FIG. 1 shows X-ray diffraction patterns of the solid electrolytes obtained in Examples 1, 2, 3, and 4 and Comparative Examples 1 and 3.
• FIG. 2 shows the X-ray diffraction patterns of the solid electrolytes obtained in Example 5 and Comparative Example 2.
• FIG. 3 is an enlarged view of a main portion of the X-ray diffraction pattern of the solid electrolyte obtained in Example 1, and an enlarged view of a main portion of the X-ray diffraction pattern of the solid electrolyte obtained in Comparative Example 1.
• FIG. 4 is a graph showing the initial charge/discharge characteristics of the solid state batteries having the solid electrolytes obtained in Examples 1 and 2.
• the present invention will be described below based on its preferred embodiments.
• the solid electrolyte of the present invention contains lithium (Li), phosphorus (P), sulfur (S), halogen (X) and nitrogen (N).
• the solid electrolyte of the present invention is a sulfide solid electrolyte.
• the X element may be, for example, at least one of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).
• the solid electrolyte may contain at least Cl or Br as the X element, or may contain Cl and Br.
• the solid electrolyte of the present invention is able to suppress the generation of hydrogen sulfide by containing N element.
• the reason for this is not clear, but it is speculated as follows. That is, when the solid electrolyte contains N element, some of the P-S bonds in the solid electrolyte are replaced with P-N bonds, which reduces the sulfur content and suppresses the generation of hydrogen sulfide.
• the reaction between the P-N bonds and water occurs preferentially over the reaction between the P-S bonds and water, which is thought to result in the suppression of the generation of hydrogen sulfide.
• the N element may be substituted for a part of the constituent elements in a compound containing Li, P, S, and X.
• the N element may exist independently from a compound containing Li, P, S, and X.
• it is preferable that the N element is substituted for a part of the constituent elements in a compound containing Li, P, S, and X.
• the N element can exist as a compound containing the N element (hereinafter also referred to as an "N-element-containing compound").
• the N-element-containing compound is not particularly limited, but may be, for example, an ammonium halide. Examples of the ammonium halide include ammonium chloride, ammonium bromide, and ammonium iodide.
• the N-element-containing compound may be present in the solid electrolyte either alone or in combination of two or more kinds. From the viewpoint of enabling a battery using the solid electrolyte of the present invention to exhibit its performance more effectively, the N-containing compound is preferably ammonium chloride.
• the solid electrolyte containing Li, S, P, and X elements is not particularly limited as long as it is a material having a function as a solid electrolyte, and examples thereof include conventionally known sulfide solid electrolytes.
• the value of (Li-S)/P when the molar ratio of the difference between Li and S relative to P is expressed as (Li-S)/P, the value of (Li-S)/P is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably 1.7 or more.
• the value of (Li-S)/P is preferably, for example, 2.2 or less, more preferably 2.0 or less, and even more preferably 1.8 or less.
• the value of S/P is, for example, preferably 2.0 or more, more preferably 2.5 or more, even more preferably 2.9 or more, and even more preferably 3.1 or more.
• the value of S/P is, for example, preferably 4.5 or less, more preferably 4.0 or less, and even more preferably 3.5 or less.
• the value of X/P is, for example, preferably 1.5 or more, more preferably 1.9 or more, and even more preferably 2.2 or more.
• the value of X/P is, for example, preferably 4.5 or less, more preferably 3.5 or less, more preferably 2.8 or less, and even more preferably 2.5 or less.
• the solid electrolyte of the present invention contains N element.
• N element is contained in the solid electrolyte, the generation of hydrogen sulfide from the solid electrolyte is suppressed.
• the amount of N element contained in the solid electrolyte is preferably such that the molar ratio of N element to P element, expressed as N/P, is 0.01 or more, more preferably 0.05 or more, even more preferably 0.06 or more, and even more preferably 0.1 or more.
• the amount of N element contained in the solid electrolyte is preferably such that the N/P value is 0.5 or less, more preferably 0.4 or less, even more preferably 0.25 or less, and even more preferably 0.2 or less.
• the value of N/P is preferably 0.01 or more and 0.5 or less, more preferably 0.05 or more and 0.4 or less, even more preferably 0.06 or more and 0.25 or less, and even more preferably 0.1 or more and 0.2 or less.
• the amount of each element constituting the solid electrolyte can be measured, for example, by ICP atomic emission spectrometry.
• the amount of N can be measured using an oxygen, nitrogen, and hydrogen analyzer.
• the amount of S can be measured by the barium sulfate gravimetric method.
• the above-mentioned molar ratios (Li-S)/P and (Li+X)/P can be calculated based on the amount of each element measured.
• the solid electrolyte of the present invention may contain elements other than Li, P, S, X, and N.
• part of the Li element may be replaced with another alkali metal element
• part of the P element may be replaced with another pnictogen element
• part of the S element may be replaced with another chalcogen element such as oxygen (O).
• the solid electrolyte of the present invention is permitted to contain impurities within a range that does not impair the effects of the present invention.
• the content of the impurities may be, for example, less than 5 mol%, preferably less than 3 mol%, and particularly less than 1 mol%.
• the solid electrolyte of the present invention may be a crystalline material or an amorphous material such as glass ceramics or glass.
• the solid electrolyte of the present invention is a crystalline material, it is preferable that the solid electrolyte contains a crystal phase having an argyrodite crystal structure, for example, from the viewpoint of effectively improving ion conductivity.
• the argyrodite crystal structure is a crystal structure possessed by a group of compounds derived from a mineral represented by the chemical formula: Ag 8 GeS 6 .
• Peak B/Peak A which is the ratio of the intensity of Peak B to the intensity of Peak A, is 2.0 or less, more preferably 1.6 or less, even more preferably 1.0 or less, and even more preferably 0.5 or less.
• the particle size of the solid electrolyte of the present invention is preferably 10 ⁇ m or less, more preferably 5 ⁇ m or less, even more preferably 3 ⁇ m or less, even more preferably 1.5 ⁇ m or less, and even more preferably 1.0 ⁇ m or less.
• the particle diameter D50 of the solid electrolyte is preferably 0.1 ⁇ m or more, more preferably 0.3 ⁇ m or more, and particularly preferably 0.5 ⁇ m or more. By having such a particle diameter, the surface area of the solid electrolyte is prevented from increasing excessively, and an increase in resistance can be suppressed. Also, mixing with the active material becomes easy.
• the solid electrolyte of the present invention has lithium ion conductivity in a solid state.
• the lithium ion conductivity of the solid electrolyte of the present invention is, for example, preferably 0.1 mS/cm or more at room temperature, i.e., 25° C., more preferably 0.5 mS/cm or more, and even more preferably 1.0 mS/cm or more.
• Lithium ion conductivity is measured, for example, by the following method.
• a solid electrolyte is uniaxially pressurized with a load of about 6 t/ cm2 in a glove box substituted with sufficiently dried argon gas (dew point -60°C or less) to prepare a sample for measuring lithium ion conductivity consisting of a pellet with a diameter of 10 mm and a thickness of about 1 mm to 8 mm.
• the lithium ion conductivity is measured using an impedance measuring device, Solartron 1255B, manufactured by Toyo Corporation.
• the measurement conditions are an AC impedance method with a temperature of 25°C, a frequency of 100 Hz to 1 MHz, and an amplitude of 100 mV.
• the solid electrolyte can be preferably synthesized by a solid-phase reaction in which a raw material composition is heated and sintered.
• the raw material composition is a mixture of raw materials containing the above-mentioned elements that constitute the solid electrolyte.
• the raw material composition contains one or more compounds containing at least one of the elements Li, P, S, and X, and also contains an ammonium halide.
• the compound may be, for example, a compound containing a Li element, a compound containing a S element, a compound containing a P element, a compound containing an X element, and a compound containing an N element.
• the compound may contain at least two or more elements selected from Li, P, S, X, and N.
• the compound may be a compound containing Li and X, a compound containing P and S, a compound containing Li and S, a compound containing P and X, a compound containing S and X, or a compound containing N and X.
• the compound containing Li and X elements for example, lithium halide can be used.
• phosphorus sulfides such as diphosphorus trisulfide (P 2 S 3 ) and diphosphorus pentasulfide (P 2 S 5 ) can be used.
• An example of a compound containing Li and S elements that can be used is lithium sulfide (Li 2 S).
• a compound containing P and X elements for example, phosphorus halides such as PX3 and P2X5 can be used.
• sulfur halides such as SX 2 , SX 4 , SX 6 , and S 2 X 10 can be used.
• an ammonium halide is used.
• ammonium halide for example, ammonium chloride, ammonium bromide, or ammonium iodide is preferably used from the viewpoint of successfully obtaining the target solid electrolyte. In particular, it is preferable to use ammonium chloride.
• the raw material composition contains lithium sulfide, phosphorus sulfide, lithium halide, and ammonium halide as the compounds, since this allows for successful synthesis of a solid electrolyte containing N element.
• a is preferably 3.0 or more and 6.0 or less, more preferably 4.0 or more and 5.5 or less, and even more preferably 4.5 or more and 5.2 or less.
• b is preferably 2.0 or more and 4.8 or less, more preferably 2.5 or more and 4.0 or less, and even more preferably 3.0 or more and 3.4 or less.
• c is preferably 1.5 or more and 4.5 or less, more preferably 1.9 or more and 3.5 or less, and even more preferably 2.2 or more and 2.5 or less.
• x is preferably greater than 1.0 and equal to or less than 3.0, more preferably 1.4 or more and 2.6 or less, and even more preferably 1.8 or more and 2.2 or less.
• the above-mentioned compounds are mixed to prepare the raw material composition.
• an attritor, paint shaker, planetary ball mill, ball mill, bead mill, homogenizer, etc. can be used for mixing.
• the amount of each raw material added when mixing is appropriately adjusted to meet the desired composition of the solid electrolyte.
• the obtained raw material composition is subjected to a sintering process to cause a solid-phase reaction and obtain a crystalline sintered product.
• the sintering atmosphere can be, for example, an inert gas atmosphere such as an argon atmosphere or a nitrogen atmosphere, or a hydrogen sulfide atmosphere. From the viewpoint of reducing the proportion of sulfur element contained in the solid electrolyte, it is preferable to adopt an inert gas atmosphere.
• the firing temperature is preferably, for example, 200°C or higher, more preferably 300°C or higher, even more preferably 350°C or higher, and even more preferably 400°C or higher.
• the firing temperature is preferably, for example, 700°C or lower, more preferably 600°C or lower, and even more preferably 550°C or lower.
• the firing time is not critical, and may be any time that allows a fired product of the desired composition to be obtained. Specifically, it is preferable that the firing time be long enough for the solid-phase reaction of the raw material composition to occur sufficiently.
• the firing time may be, for example, 30 minutes or more, 2 hours or more, or 3 hours or more. On the other hand, the firing time may be, for example, 10 hours or less, or 5 hours or less.
• the sulfur in the sulfide contained in the raw material composition reacts with the hydrogen in the ammonium halide to generate hydrogen sulfide, and as a result, the composition of each element contained in the calcined product may differ from the theoretical composition of the raw material composition.
• the fired product may be crushed and pulverized as necessary, and may further be classified as necessary.
• a grinder such as a planetary ball mill, a vibration mill, or a tumbling mill, or a kneader.
• the solid electrolyte thus obtained can be used alone or in a mixture with other solid electrolytes.
• the solid electrolyte of the present invention can be used as a material constituting a solid electrolyte layer, a positive electrode layer, or a negative electrode layer.
• the solid electrolyte of the present invention can be used in a battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer located between the positive electrode layer and the negative electrode layer.
• the solid electrolyte can be used in so-called solid-state batteries. More specifically, it can be used in lithium solid-state batteries.
• the lithium solid-state battery may be a primary battery or a secondary battery. There is no particular restriction on the shape of the battery, and for example, a laminate type, a cylindrical type, a square type, or other shape can be adopted.
• solid-state battery includes solid-state batteries that do not contain any liquid or gel-like substance as an electrolyte, as well as embodiments that contain, for example, 50% by mass or less, 30% by mass or less, or 10% by mass or less of a liquid or gel-like substance as an electrolyte.
• the solid electrolyte layer contains the solid electrolyte of the present invention
• the solid electrolyte layer can be produced, for example, by a method of dropping a slurry consisting of a solid electrolyte, a binder, and a solvent onto a substrate and scraping it off with a doctor blade or the like, a method of contacting the substrate with the slurry and then cutting it with an air knife, a method of forming a coating film by a screen printing method or the like and then removing the solvent by heating and drying, etc.
• the solid electrolyte can also be produced by forming a powdered solid electrolyte into a compact by pressing or the like and then appropriately processing it.
• the thickness of the solid electrolyte layer is typically preferably 5 ⁇ m or more and 300 ⁇ m or less, and more preferably 10 ⁇ m or more and 100 ⁇ m or less.
• the solid electrolyte of the present invention is used together with an active material to form an electrode mixture.
• the proportion of the solid electrolyte in the electrode mixture is typically 10 mass% or more and 50 mass% or less.
• the electrode mixture may contain other materials such as a conductive material as necessary.
• An electrode mixture, a binder, and a solvent are mixed to prepare a paste, which is then applied to a current collector such as aluminum foil and dried to prepare electrodes such as positive and negative electrodes.
• any positive electrode material used as a positive electrode active material in lithium ion batteries can be used as appropriate.
• positive electrode active materials containing lithium specifically, spinel type lithium transition metal oxides and lithium metal oxides having a layered structure, can be mentioned.
• the positive electrode material may contain a conductive material or other materials.
• a negative electrode material used as a negative electrode active material of a lithium ion battery can be appropriately used. Since the solid electrolyte of the present invention is electrochemically stable, a carbon-based material such as graphite, artificial graphite, natural graphite, or non-graphitizable carbon (hard carbon), which is a material that charges and discharges at a base potential (about 0.1 V vs. Li + /Li) comparable to lithium metal or lithium metal, can be used as the negative electrode material. This can greatly improve the energy density of the solid battery. In addition, silicon or tin, which are promising high-capacity materials, can also be used as the active material. The negative electrode material may also contain a conductive material in addition to the negative electrode active material, or other materials.
• the present invention further discloses the following solid electrolyte, electrode mixture, electrode, battery, and method for producing the solid electrolyte.
• a solid electrolyte, wherein a molar ratio of the sum of the lithium (Li) element and the halogen (X) element to the phosphorus (P) element is 7.1 or more and 10.0 or less.
• ⁇ 4> The solid electrolyte according to any one of ⁇ 1> to ⁇ 3>, which has at least two peaks at a position of 25.5° ⁇ 1.0° in an X-ray diffraction pattern.
• ⁇ 5> The solid electrolyte according to any one of ⁇ 1> to ⁇ 4>, wherein a molar ratio of the nitrogen (N) element to the phosphorus (P) element is 0.01 or more and 0.5 or less.
• N nitrogen
• P phosphorus
• An electrode mixture comprising the active material according to any one of ⁇ 1> to ⁇ 5>, a solid electrolyte, and a conductive material.
• An electrode comprising the electrode mixture according to ⁇ 6> and a binder.
• Comparative Example 1 (1) Preparation of raw material composition Lithium sulfide (Li 2 S) powder, diphosphorus pentasulfide (P 2 S 5 ) powder, lithium chloride (LiCl) powder, and lithium bromide (LiBr) powder were weighed out so as to obtain the raw material mass ratio shown in Table 1 below. Heptane was added to these powders to prepare a slurry. This slurry was placed in a zirconia container and set in a planetary ball mill device. Zirconia balls with a diameter of 5 mm were used as grinding media. The ball mill device was operated at 100 rpm, and wet mixing was performed for 10 hours. The mixed slurry was vacuum dried at room temperature to remove heptane. In this way, a raw material composition was obtained.
• Firing The raw material composition was fired to obtain a fired product. Firing was performed using a tubular electric furnace. Nitrogen gas with a purity of 100% was circulated in the electric furnace during firing. Firing was performed by increasing the temperature to 300°C at 200°C/h and maintaining the temperature at 300°C for 4 hours, then increasing the temperature to 500°C at 200°C/h and maintaining the temperature at 500°C for 4 hours, for a total of 10.5 hours.
• Examples 1, 2 and 3 A raw material composition was obtained by weighing out lithium sulfide ( Li2S ) powder, diphosphorus pentasulfide ( P2S5 ) powder, lithium chloride (LiCl) powder, lithium bromide (LiBr) powder, and ammonium chloride ( NH4Cl ) powder so as to obtain the raw material mass ratio shown in the following Table 1.
• Li2S lithium sulfide
• P2S5 diphosphorus pentasulfide
• LiCl lithium chloride
• LiBr lithium bromide
• NH4Cl ammonium chloride
• Example 4 A raw material composition was obtained by weighing out lithium sulfide ( Li2S ) powder, diphosphorus pentasulfide ( P2S5 ) powder, lithium chloride (LiCl) powder, lithium bromide (LiBr) powder, lithium iodide (LiI) powder, and ammonium chloride ( NH4Cl ) powder so as to obtain the raw material mass ratio shown in the following Table 1.
• Li2S lithium sulfide
• P2S5 diphosphorus pentasulfide
• LiCl lithium chloride
• LiBr lithium bromide
• LiI lithium iodide
• NH4Cl ammonium chloride
• Comparative Example 2 A raw material composition was obtained by weighing out lithium sulfide ( Li2S ) powder, diphosphorus pentasulfide ( P2S5 ) powder, lithium chloride (LiCl) powder, and lithium bromide (LiBr) powder so as to obtain the raw material mass ratio shown in the following Table 1. A solid electrolyte powder was obtained in the same manner as in Comparative Example 1 except for this.
• Example 5 A raw material composition was obtained by weighing out lithium sulfide ( Li2S ) powder, diphosphorus pentasulfide ( P2S5 ) powder, lithium chloride (LiCl) powder, lithium bromide (LiBr) powder, and ammonium chloride ( NH4Cl ) powder so as to obtain the raw material mass ratio shown in the following Table 1.
• Li2S lithium sulfide
• P2S5 diphosphorus pentasulfide
• LiCl lithium chloride
• LiBr lithium bromide
• NH4Cl ammonium chloride
• Comparative Example 3 This comparative example is an example intended to reduce the generation of hydrogen sulfide by reducing the molar ratio of S/P in a solid electrolyte containing Li, P, S and X elements but not containing N.
• a raw material composition was obtained by weighing out lithium sulfide ( Li2S ) powder, diphosphorus pentasulfide ( P2S5 ) powder, lithium chloride (LiCl) powder, and lithium bromide (LiBr) powder so as to obtain the raw material mass ratio shown in the following Table 1.
• a solid electrolyte powder was obtained in the same manner as in Comparative Example 1 except for this.
• the solid electrolyte powder was melted in a graphite crucible using an oxygen, nitrogen, and hydrogen analyzer (EMGA930 manufactured by Horiba, Ltd.), and the generated gas was extracted as N2 using a thermal conductivity detector after removing CO2 and H2O using a CO2 remover and a H2O remover, and the N content was quantified.
• the amount of hydrogen sulfide generated and the particle size D50 were measured by the methods described below.
• the characteristics of a solid-state battery containing a solid electrolyte were evaluated by the method described below. The results are shown in Table 1.
• Example 1 to 5 and Comparative Examples 1 to 3 were subjected to XRD measurement to obtain diffraction patterns.
• the XRD measurement was performed using an X-ray diffraction device "Smart Lab SE” manufactured by Rigaku Corporation. The measurement conditions were: no exposure to air, scanning axis: 2 ⁇ / ⁇ , scanning range: 10° to 120°, step width: 0.02°, and scanning speed: 1°/min.
• the X-ray source was CuK ⁇ 1 ray.
• the tube voltage was 40 kV and the tube current was 80 mA. The measurement results are shown in FIG. 1 and FIG. 2.
• the amount of hydrogen sulfide generated from the solid electrolyte was measured using a detector tube.
• the solid electrolyte was weighed out in an amount of 2 mg into a metal container in a glove box purged with sufficiently dried Ar gas (dew point -60° C. or less), and then placed in a bag made of laminate film and sealed.
• a 1000 ml glass separable flask was placed in a thermo-hygrostat chamber maintained at room temperature (25°C) with a dew point of -30°C adjusted by mixing dry air and air, and was held until the inside of the separable flask became the same as the environment in the thermo-hygrostat chamber.
• the sealed bag containing the solid electrolyte was opened in the thermo-hygrostat chamber, the solid electrolyte was quickly placed in the separable flask, and the separable flask was then sealed.
• the amount of hydrogen sulfide generated from immediately after sealing until 30 minutes had elapsed was measured 30 minutes later using a gas detector (No. 4LL manufactured by Gastec).
• the positive electrode active material was LiNi0.6Co0.2Mn0.2O2 (NCM) powder, which is a ternary layered compound with a surface coated with lithium niobate .
• the negative electrode active material was graphite (Gr) powder.
• the positive electrode mixture was prepared by mixing in a mortar a positive electrode active material powder, a solid electrolyte powder, and a conductive assistant in a mass ratio of 60: 37: 3. This positive electrode mixture was uniaxially press molded at 20 MPa to produce positive electrode mixture pellets.
• the negative electrode mixture powder was prepared by mixing graphite powder and solid electrolyte powder in a mass ratio of 64:36 in a mortar.
• battery characteristics evaluation (initial charge/discharge characteristics) was performed by the following method.
• the all-solid-state battery cell was placed in an environmental tester maintained at 25° C., and connected to a charge/discharge device to evaluate the battery characteristics.
• the battery was charged and discharged at 1 mA at 1C.
• the battery was charged at 0.1C to 4.5V by CC-CV method, and the initial charge capacity was obtained.
• the battery was discharged at 0.1C to 2.5V by CC method, and the initial discharge capacity was obtained.
• the initial charge/discharge curves of Example 1 and Example 2 are shown in FIG. 4.
• Example 4 the initial charge capacity was 217.4 mAh/g and the initial discharge capacity was 182.2 mAh/g in Example 1.
• the initial charge capacity was 211.4 mAh/g and the initial discharge capacity was 176.8 mAh/g in Example 2.
• the present invention provides a solid electrolyte in which the generation of hydrogen sulfide is suppressed, and a method for producing the same.

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