Classifications

• • 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
  • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
• • 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
  • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
• • 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
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
• • 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

Definitions

• the present invention relates to a positive electrode composite, a method for producing the positive electrode composite, and a lithium-ion battery.
• Heat treatment is required to restore the lithium ion conductivity of the solid electrolyte, which has been reduced by mechanical mixing, but this increases the number of steps and energy consumption, leading to higher manufacturing costs.
• this process is accompanied by the outflow of sulfur-based active materials that have been composited with the solid electrolyte by mechanical mixing.
• the object of the present invention is to provide a positive electrode composite that does not require heat treatment to restore lithium ion conductivity and that can produce a battery with excellent rate characteristics.
• a battery comprising a sulfur-based active material and a sulfide solid electrolyte
• the sulfide solid electrolyte contains phosphorus (P) and a halogen (X) including at least iodine (I) as constituent elements, a molar ratio (X/P) of the halogen (X) to the phosphorus (P) is 0.86 or more;
• a positive electrode mixture wherein a molar ratio (I/P) of the iodine (I) to the phosphorus (P) is 0.10 or more.
• the sulfide solid electrolyte contains lithium (Li) as a constituent element, 2.
• a method for producing a positive electrode composite material comprising a step of mechanically mixing a sulfur-based active material and a sulfide solid electrolyte to form a composite,
• the sulfide solid electrolyte is synthesized from a mixed raw material containing lithium (Li), phosphorus (P), and a halogen (X) containing at least iodine (I),
• the method satisfies the following formulas (1) and (2) when the mixed raw material is assumed to be a mixture of lithium sulfide (Li 2 S), diphosphorus pentasulfide (P 2 S 5 ) and lithium halide (LiX).
• the present invention provides a positive electrode composite that does not require heat treatment to restore lithium ion conductivity and that produces a battery with excellent rate characteristics.
• the positive electrode composite includes a sulfur-based active material and a sulfide solid electrolyte.
• the sulfide solid electrolyte includes phosphorus (P) and a halogen (X) including at least iodine (I) as constituent elements, and the molar ratio (X/P) of the halogen (X) to the phosphorus (P) is 0.86 or more, and the molar ratio (I/P) of the iodine (I) to the phosphorus (P) is 0.10 or more.
• the sulfide solid electrolyte exhibits sufficiently high lithium ion conductivity, and the deterioration of the sulfide solid electrolyte is suppressed even after mechanical mixing, compared to conventional positive electrode composites. This makes it unnecessary to perform a heat treatment to restore the lithium ion conductivity.
• a lithium ion battery having a rate characteristic equal to or higher than that of a conventional positive electrode composite can be obtained. The components of this embodiment will be described below.
• the sulfide solid electrolyte used in the present application contains a predetermined amount of halogen (X) including at least iodine (I).
• X halogen
• I iodine
• the sulfide solid electrolyte is less susceptible to deterioration due to mechanical mixing. Therefore, it is possible to restore the lithium ion conductivity. No heat treatment is required for this purpose.
• the molar ratio (X/P) is preferably 0.90 to 2.5, more preferably 1.00 to 2.00, and even more preferably 1.05 to 1.80.
• halogens other than iodine include fluorine, chlorine, and bromine.
• the halogen (X) may contain only iodine, or may contain iodine and one other halogen.
• the halogen (X) contains iodine and bromine.
• the molar ratio (I/P) is preferably 0.50 to 2.00, and more preferably 1.00 to 1.80.
• the sulfide solid electrolyte is preferably a solid electrolyte containing a glass (amorphous) component.
• a glass component can be confirmed by the presence of a broad peak (halo pattern) due to the amorphous component in an X-ray diffraction (XRD) measurement.
• XRD X-ray diffraction
• the sulfide solid electrolyte preferably contains lithium (Li) as a constituent element.
• the molar ratio (Li/P) of lithium (Li) to phosphorus (P) is preferably 3.00 to 5.25, more preferably 3.50 to 5.20, and may be 4.00 to 5.00, or even 4.00 to 4.80.
• the molar ratio of sulfur (S) to phosphorus (P) is preferably 3.0 to 4.4, more preferably 3.5 to 4.3, even more preferably 3.8 to 4.2, and even more preferably 3.9 to 4.1.
• the types and molar ratios of the constituent elements of the sulfide solid electrolyte can be confirmed, for example, by an ICP emission spectrometer.
• the molar ratio of the constituent elements of the sulfide solid electrolyte can be adjusted by controlling the raw material composition. Note that the molar ratio of the constituent elements in the raw materials is approximately equal to the molar ratio of the constituent elements of the resulting sulfide solid electrolyte.
• the ionic conductivity of the sulfide solid electrolyte used is preferably 1.0 mS/cm or more, and more preferably 1.5 mS/cm or more.
• the sulfide solid electrolyte used in this embodiment can be produced, for example, by preparing starting materials for a known lithium ion sulfide solid electrolyte so that the molar ratio of the constituent elements satisfies the above range, and mechanically mixing them.
• two or more compounds or simple substances containing lithium, phosphorus, sulfur, and halogens including at least iodine as constituent elements can be used in combination, and there are no particular restrictions on which can be used as long as they exhibit ionic conductivity due to the metal atoms contained therein.
• Examples of the raw material containing lithium (Li) include lithium compounds such as lithium sulfide (Li 2 S), lithium oxide (Li 2 O), and lithium carbonate (Li 2 CO 3 ), and lithium metal alone. Among these, lithium compounds are preferred, and lithium sulfide is more preferred.
• the lithium sulfide can be used without any particular restrictions, but high purity lithium sulfide is preferred.
• Lithium sulfide can be produced, for example, by the methods described in JP-A-7-330312, JP-A-9-283156, JP-A-2010-163356, and JP-A-2011-84438.
• lithium hydroxide and hydrogen sulfide are reacted in a hydrocarbon organic solvent at 70°C to 300°C to produce lithium hydrosulfide, and then this reaction liquid is dehydrosulfided to synthesize lithium sulfide (JP Patent Publication No. 2010-163356).
• lithium hydroxide and hydrogen sulfide can be reacted in an aqueous solvent at 10°C to 100°C to produce lithium hydrosulfide, and then this reaction liquid can be dehydrosulfidized to synthesize lithium sulfide (JP Patent Publication 2011-84438).
• raw materials containing phosphorus include phosphorus sulfides such as diphosphorus trisulfide (P 2 S 3 ) and diphosphorus pentasulfide (P 2 S 5 ), phosphorus compounds such as sodium phosphate (Na 3 PO 4 ), and elemental phosphorus.
• phosphorus sulfide is preferred, and diphosphorus pentasulfide (P 2 S 5 ) is more preferred.
• Phosphorus compounds such as diphosphorus pentasulfide (P 2 S 5 ) and elemental phosphorus can be used without any particular limitation as long as they are industrially manufactured and sold.
• a raw material containing a halogen as a constituent element it is preferable to include a halogen compound represented by the following formula, for example.
• M represents sodium (Na), lithium (Li), boron (B), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), germanium (Ge), arsenic (As), selenium (Se), tin (Sn), antimony (Sb), tellurium (Te), lead (Pb), bismuth (Bi), or any of these elements bonded to an oxygen element or a sulfur element, and is preferably lithium (Li) or phosphorus (P), and more preferably lithium (Li).
• X is a halogen element selected from fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).
• l is an integer of 1 or 2
• m is an integer of 1 to 10.
• Xs may be the same or different.
• SiBrCl3 m is 4, and Xs are different elements, Br and Cl.
• halogen compounds include sodium halides such as NaI, NaF, NaCl, and NaBr; lithium halides such as LiF, LiCl, LiBr, and LiI; boron halides such as BCl 3 , BBr 3 , and BI 3 ; aluminum halides such as AlF 3 , AlBr 3 , AlI 3 , and AlCl 3 ; silicon halides such as SiF 4 , SiCl 4 , SiCl 3 , Si 2 Cl 6 , SiBr 4 , SiBrCl 3 , SiBr 2 Cl 2 , and SiI 4 ; phosphorus halides such as PF 3 , PF 5 , PCl 3 , PCl 5 , POCl 3 , PBr 3 , POBr 3 , PI 3 , P 2 Cl 4 , and P 2 I 4 ; and SF 2 and SF 4.
• sodium halides such as NaI, NaF, NaCl, and NaBr
• lithium halides such as lithium chloride (LiCl), lithium bromide (LiBr), and lithium iodide (LiI)
• phosphorus halides such as phosphorus pentachloride (PCl 5 ), phosphorus trichloride (PCl 3 ), phosphorus pentabromide (PBr 5 ), and phosphorus tribromide (PBr 3 )
• lithium halides such as LiCl, LiBr, and LiI
• PBr 3 lithium halides such as LiCl, LiBr, and LiI
• PBr 3 lithium halides such as LiCl, LiBr, and LiI are even more preferred, and LiI and LiBr are particularly preferred.
• the halogen compound may be any one of the above compounds containing iodine, or two or more of them may be used in combination.
• the mixed raw material is assumed to be a mixture of lithium sulfide (Li 2 S), diphosphorus pentasulfide (P 2 S 5 ) and lithium halide (LiX), the following formulas (1) and (2) are satisfied. 45 ⁇ [Li 2 S] ⁇ 100/([Li 2 S] + [P 2 S 5 ]) ⁇ 90 (1) 30 ⁇ [LiX] ⁇ 100/([Li 2 S] + [P 2 S 5 ] + [LiX]) (2) (In the formula, [Li 2 S] is the molar ratio of Li 2 S, [P 2 S 5 ] is the molar ratio of P 2 S 5 , and [LiX] is the molar ratio of LiX.)
• the above formula (1) [Li 2 S] ⁇ 100/([Li 2 S]+[P 2 S 5 ]) is preferably 70 or more and 80 or less, more preferably 72 or more and 78 or less, and particularly preferably 74 or more and 76 or less.
• the above formula (2) [LiX] ⁇ 100/([Li 2 S]+[P 2 S 5 ]+[LiX]) is preferably 30 or more and 60 or less, and more preferably 35 or more and 55 or less.
• the mixed raw material of the sulfide solid electrolyte is a mixture of lithium sulfide ( Li2S ), diphosphorus pentasulfide ( P2S5 ), lithium iodide (LiI) and any lithium halide (LiX: X is F, Cl or Br).
• Li2S lithium sulfide
• P2S5 diphosphorus pentasulfide
• LiI lithium iodide
• LiX lithium halide
• X is F, Cl or Br
• the molar ratio (I/ P ) of iodine (I) to phosphorus (P) is preferably 0.10 or more.
• the rotation speed is set to several tens to several hundreds of revolutions per minute, and the processing time is 0.5 to 100 hours. More specifically, in the case of the planetary ball mill (manufactured by Fritsch: model number P-7) used in the examples of the present application, the rotation speed of the planetary ball mill is preferably 100 rpm or more and 500 rpm or less, more preferably 150 rpm or more and 400 rpm or less.
• the temperature during pulverization may be room temperature, and in this case, cooling from the outside may not be performed, and for example, a 5-minute operation stop period may be provided every hour.
• pulverization may be performed while cooling without providing an operation stop period.
• balls serving as grinding media for example, zirconia balls, their diameter is preferably 0.2 to 20 mm.
• the sulfur-based active material is not particularly limited, but examples thereof include sulfur, lithium sulfide (Li 2 S), lithium polysulfide (Li 2 S n : n satisfies 1 ⁇ n ⁇ 8), titanium sulfide (TiS 2 ), molybdenum sulfide (MoS 2 ), iron sulfide (FeS, FeS 2 ), copper sulfide (CuS), nickel sulfide (Ni 3 S 2 ), and sulfur-containing polymer compounds.
• sulfur having a high purity is preferred. Specifically, the purity is preferably 95% by mass or more, more preferably 96% by mass or more, and particularly preferably 97% by mass or more.
• crystal system of sulfur examples include ⁇ -sulfur (orthorhombic system), ⁇ -sulfur (monoclinic system), ⁇ -sulfur (monoclinic system), amorphous sulfur, etc. These may be used alone or in combination of two or more kinds.
• the elemental sulfur is partially or entirely converted into a discharge product during the battery reaction. Therefore, in one embodiment, the discharge product of elemental sulfur is present in the positive electrode mixture (positive electrode).
• discharge products of elemental sulfur include Li 2 S in a fully discharged state and lithium polysulfides in the intermediate stages thereof, such as Li 2 S 2 , Li 2 S 4 , Li 2 S 6 , and Li 2 S 8 .
• the positive electrode mixture preferably further contains a conductive assistant.
• the conductive assistant may be any material having electron conductivity.
• the conductive assistant preferably has a plurality of pores. A carbon material having pores is particularly preferable. Carbon materials have high conductivity and are lighter than other conductive materials, so that the output density and capacity per unit weight of the battery can be increased.
• the specific surface area of the conductive assistant is preferably 0.1 m 2 /g or more and 5000 m 2 /g or less, more preferably 1 m 2 /g or more and 4000 m 2 /g or less, even more preferably 1 m 2 /g or more and 3000 m 2 /g or less, and most preferably 10 m 2 /g or more and 3000 m 2 /g or less.
• the pore volume of the conductive assistant is preferably 0.1 cc/g or more and 5.0 cc/g or less.
• the pores in the conductive assistant preferably have an average diameter of 0.1 nm or more and 40 nm or less, more preferably 0.5 nm or more and 40 nm or less, even more preferably 0.5 nm or more and 20 nm or less, and most preferably 1 nm or more and 20 nm or less.
• the specific surface area, pore volume, and pore diameter of the conductive assistant can be determined using a nitrogen adsorption isotherm obtained by adsorbing nitrogen gas to the conductive assistant at liquid nitrogen temperature.
• the specific surface area can be calculated by the Brenauer-Emmet-Telle (BET) multipoint method using the nitrogen adsorption isotherm.
• the pore volume and pore diameter can be determined by the Barret-Joyner-Halenda (BJH) method using the nitrogen adsorption isotherm.
• the measurement can be performed using, for example, a specific surface area/pore distribution measuring device (Autosorb-3) manufactured by Quantacrome.
• Carbon materials include, but are not limited to, carbon blacks such as Ketjen black, acetylene black, denka black, thermal black, and channel black, mesoporous carbon, activated carbon, amorphous carbon, carbon nanotubes, vapor-grown carbon fiber (VGCF), and carbon nanohorns, while conductive carbon materials include fullerene, carbon fiber, natural graphite, artificial graphite, graphene, graphene oxide, and reduced graphene oxide. Of these, activated carbon is preferred. These may be used alone or in combination of two or more. Composites of these may also be used.
• carbon blacks such as Ketjen black, acetylene black, denka black, thermal black, and channel black
• mesoporous carbon activated carbon
• amorphous carbon carbon nanotubes
• VGCF vapor-grown carbon fiber
• carbon nanohorns include fullerene, carbon fiber, natural graphite, artificial graphite, graphene, graphene oxide, and reduced graphene oxide.
• the positive electrode mixture may or may not contain other components in addition to the sulfur-based active material, the sulfide solid electrolyte, and the conductive assistant.
• the other components are not particularly limited, but examples thereof include a binder, a solvent, a dispersant, and the like.
• the solid electrolyte is evaluated as being altered when the solid electrolyte alteration parameter ⁇ of the positive electrode composite is 750 or more.
• the solid electrolyte alteration parameter ⁇ is preferably 600 or less, more preferably 500 or less, and even more preferably 250 or less.
• the ionic conductivity ⁇ of the sulfide solid electrolyte can be measured by an AC impedance method, the details of which will be described later.
• the ionic resistance ⁇ of the positive electrode composite can be measured by preparing an ionic resistance measurement cell containing the positive electrode composite and a solid electrolyte, and applying an AC impedance method to the ionic resistance measurement cell. The measurement method will be described in detail later.
• the positive electrode mixture according to this embodiment can be produced, for example, by the method described below.
• a method for producing a positive electrode composite according to one embodiment of the present invention includes a step of mechanically mixing the above-described sulfur-based active material and a sulfide solid electrolyte having a composition represented by the above-described formulas (1) and (2) to form a composite.
• a sulfur-based active material-conductive additive composite material may be formed from the above-mentioned sulfur-based active material and conductive additive, and then the sulfide solid electrolyte and the sulfur-based active material-conductive additive composite material may be mechanically mixed.
• the sulfur-based active material is elemental sulfur
• the conductive additive and elemental sulfur are mixed and sealed, and the mixture is heated to melt the elemental sulfur and impregnate the elemental sulfur into the pores, thereby forming the sulfur-conductive additive composite material.
• the mixture ratio of elemental sulfur and conductive additive can be adjusted appropriately to suit the materials used.
• the mass ratio (S/C) of elemental sulfur (S) and conductive additive (C) in a sulfur-based active material-conductive additive composite material is 0.5 or more.
• a mass ratio (S/C) of 10 or less is preferable.
• the mixture of elemental sulfur and the conductive assistant is heated in a sealed state at a temperature equal to or higher than the melting point of elemental sulfur (about 115°C).
• the heating temperature is adjusted according to the carbon material and elemental sulfur, but is preferably equal to or higher than 130°C, and more preferably equal to or higher than 150°C.
• the upper limit of the heating temperature is equal to or lower than the boiling point of elemental sulfur (about 445°C).
• the heating time is preferably 0.1 to 24 hours.
• the sulfur-conductive additive composite material is obtained by cooling after heating. If necessary, a pulverization step may be carried out after cooling.
• a sulfur-based active material or a sulfur-based active material-conductive additive composite material and a sulfide solid electrolyte are mechanically mixed to form a positive electrode mixture.
• mechanical mixing refers to mechanically applying a shear force, an impact force, or the like. Examples of mechanical mixing methods include a pulverizer such as a planetary ball mill, a vibration mill, or a rolling mill, and a kneader.
• the sulfur-based active material, the sulfur-based active material-conductive assistant composite material, and the sulfide solid electrolyte may be partially pulverized by this step.
• the rotation speed of the planetary ball mill is preferably 100 rpm or more and 500 rpm or less, and more preferably 150 rpm or more and 400 rpm or less.
• balls serving as grinding media for example, zirconia balls, their diameter is preferably 0.2 to 20 mm.
• the content of the sulfide solid electrolyte is preferably 5 to 200 parts by mass, and more preferably 10 to 120 parts by mass, when the sulfur-based active material or sulfur-based active material-conductive additive composite material is taken as 100 parts by mass. If the content of the solid electrolyte is 5 parts by mass or less, it becomes difficult to obtain sufficient ion conduction, and if it is 200 parts by mass or more, the content of the active material decreases, making it difficult to improve the energy density.
• Positive electrode and lithium ion battery The positive electrode or lithium ion battery according to one embodiment of the present invention includes the positive electrode mixture of the present invention described above.
• a solid electrolyte can be used instead of a liquid electrolyte to produce an all-solid-state lithium ion battery.
• an all-solid-state lithium ion battery with good rate characteristics can be produced.
• An all-solid-state lithium ion battery mainly consists of a positive electrode layer, a negative electrode layer, and an electrolyte layer, and the positive electrode mixture of the present invention is suitable as a constituent material of the positive electrode layer.
• the negative electrode layer and the electrolyte layer can be manufactured by a known method.
• a current collector In addition to the positive electrode layer, the negative electrode layer, and the electrolyte layer, it is preferable to use a current collector, and a known current collector is also used.
• the solid electrolyte is not particularly limited, and any known solid electrolyte can be used.
• Example 1 (1) Preparation of sulfur-based active material-conductive additive composite material Activated carbon (MSC-30 manufactured by Kansai Thermochemical Co., Ltd.) and sulfur were placed in a glass bottle in a mass ratio of 3:7, and the bottle was sealed in a SUS tube container. The bottle was heated in an electric furnace at 150°C for 6 hours and then at 300°C for 2.75 hours to obtain a sulfur-based active material-conductive additive composite material containing activated carbon and sulfur.
• Activated carbon MSC-30 manufactured by Kansai Thermochemical Co., Ltd.
• Example 2 A positive electrode mixture was obtained in the same manner as in Example 1 (2) except that in the production of the sulfide solid electrolyte of Example 1, the raw materials were changed to 0.2553 g of lithium sulfide, 0.4112 g of diphosphorus pentasulfide, and 0.5334 g of lithium iodide.
• Example 3 A positive electrode mixture was obtained in the same manner as in Example 1 except that in the production of the sulfide solid electrolyte of Example 1 (2), the raw materials were changed to 0.2360 g of lithium sulfide, 0.3802 g of diphosphorus pentasulfide, 0.5342 g of lithium iodide, and 0.0495 g of lithium bromide.
• Example 1 A positive electrode mixture was obtained in the same manner as in Example 1, except that a sulfide solid electrolyte prepared by the following manufacturing method was used.
• the raw materials were 0.4127 g of lithium sulfide, 0.6655 g of diphosphorus pentasulfide, 0.2137 g of lithium iodide, and 0.2080 g of lithium bromide.
• the mixed raw materials and 10 zirconia balls with a diameter of 10 mm were placed in a 45 mL zirconia pot and sealed.
• the mixture was mixed for 40 hours at a rotation speed of 370 rpm using a planetary ball mill (manufactured by Fritsch, model number P-7) to obtain a glassy treated product.
• the treated product was heated at 195°C for 3 hours to produce a sulfide solid electrolyte.
• Example 2 A positive electrode mixture was obtained in the same manner as in Example 1, except that a sulfide solid electrolyte prepared by the following manufacturing method was used.
• the raw materials were 0.3830 g of lithium sulfide and 0.6170 g of diphosphorus pentasulfide.
• the mixed raw materials and 10 zirconia balls with a diameter of 10 mm were placed in a 45 mL zirconia pot and sealed.
• the mixture was mixed for 40 hours at a rotation speed of 370 rpm using a planetary ball mill (manufactured by Fritsch, model number P-7).
• Example 3 A positive electrode mixture was obtained in the same manner as in Example 1, except that a sulfide solid electrolyte prepared by the following manufacturing method was used.
• the raw materials were 0.4129 g of lithium sulfide, 0.5875 g of diphosphorus pentasulfide, 0.2241 g of lithium chloride, and 0.2755 g of lithium bromide.
• the mixed raw materials and 10 zirconia balls with a diameter of 10 mm were placed in a 45 mL zirconia pot and sealed.
• the mixture was mixed for 40 hours at a rotation speed of 370 rpm using a planetary ball mill (manufactured by Fritsch, model number P-7).
• the treated material was heated at 430° C. for 8 hours to obtain a sulfide solid electrolyte.
• Example 4 A positive electrode mixture was obtained in the same manner as in Example 1, except that a sulfide solid electrolyte prepared by the following manufacturing method was used.
• the raw materials were 0.3830 g of lithium sulfide and 0.6170 g of diphosphorus pentasulfide.
• the mixed raw materials and 10 zirconia balls with a diameter of 10 mm were placed in a 45 mL zirconia pot and sealed.
• the mixture was mixed for 40 hours at a rotation speed of 370 rpm using a planetary ball mill (manufactured by Fritsch, model number P-7).
• 0.8936 g of the resulting treated product, 0.1064 g of lithium borohydride, and 100 g of zirconia balls having a diameter of 4 mm were placed in a 45 mL zirconia pot, which was then sealed.
• the pot was mixed using a planetary ball mill at a rotation speed of 370 rpm for 15 hours to obtain a sulfide solid electrolyte.
• the sulfide solid electrolytes prepared in each example were evaluated as follows.
• Ionic Conductivity of Solid Electrolyte A circular pellet with a diameter of 10 mm (cross-sectional area S: 0.785 cm 2 ) and a height (L) of 0.1 to 0.5 cm was molded from the solid electrolyte to prepare a sample. Electrode terminals were attached to the top and bottom of the sample, and measurements were made at 25°C by an AC impedance method (frequency range: 1 MHz to 1 Hz, amplitude: 10 mV) to obtain a Cole-Cole plot.
• AC impedance method frequency range: 1 MHz to 1 Hz, amplitude: 10 mV
• ion resistance measurement cell 100 mg of the solid electrolyte A prepared by the above procedure was pressure molded in a Macol cylinder with a diameter of 10 mm. 20 mg of positive electrode composite powder was added to the pressurized surface, and pressure molded again. 20 mg of positive electrode composite powder was added to the pressurized surface opposite to the positive electrode composite, and pressed to prepare an ion resistance measurement cell.
• Solid electrolyte alteration parameter ⁇ [Solid electrolyte ionic conductivity ⁇ ] ⁇ [Positive electrode composite ionic resistance ⁇ ]
• Solid electrolyte alteration parameter ⁇ 750 or more, it was determined that the solid electrolyte had altered.
• the powder to be measured was filled into a groove having a diameter of 20 mm and a depth of 0.2 mm, and the groove was smoothed with glass to prepare a sample.
• the sample was sealed with a Kapton film for XRD and measured without exposing it to air.
• the measurement was performed under the following measurement conditions using a powder X-ray diffraction measurement device D2 PHASER manufactured by BRUKER Corporation.
• Tube voltage 30 kV
• Tube current 10mA
• X-ray wavelength Cu-K ⁇ ray (1.5418 ⁇ )
• Optical system focusing method
• Slit configuration Soller slit 4° (both incident and receiving sides), divergence slit 1 mm, K ⁇ filter (Ni plate 0.5%), air scatter screen 3 mm)
• Table 2 shows the raw material composition of the sulfide solid electrolyte for each of the above examples and comparative examples.
• Table 3 shows the raw material composition of the sulfide solid electrolyte expressed by formulas (1) and (2).
• Table 4 shows the molar ratio of the raw material constituent elements to phosphorus (P).
• Table 5 shows the evaluation results of the sulfide solid electrolyte, the positive electrode composite, and the battery.
• the positive electrode composite material prepared by mechanically mixing the sulfide solid electrolyte and the sulfur-based active material-conductive additive composite material produced in Examples 1 to 3 suppresses deterioration of the solid electrolyte, and that the all-solid-state lithium ion battery containing the solid electrolyte as the positive electrode composite material has excellent rate characteristics (discharge capacity).
• the positive electrode composites containing the sulfide solid electrolyte of Comparative Examples 1 to 4 although the ionic conductivity of the solid electrolyte is higher than that of Examples 1 to 3, the ionic resistance of the positive electrode composite is also higher than that of Examples 1 to 3, and therefore the derived solid electrolyte alteration parameter ⁇ is also high.
• the positive electrode composites of Comparative Examples 1 to 4 are used as lithium ion batteries, the discharge capacity (rate characteristics) is lower than that of Examples 1 to 3. Therefore, it is presumed that the solid electrolyte in the positive electrode composites of Comparative Examples 1 to 4 has been altered by mechanical mixing.
• the positive electrode composite of the present invention is suitable as a positive electrode for a lithium ion battery.
• the lithium ion battery of the present invention is also suitable for use in, for example, information-related devices and communication devices such as personal computers, video cameras, and mobile phones, and in vehicles such as electric cars.

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