Solid electrolyte materials and batteries

Abstract

The present invention provides a solid electrolyte material that can suppress a decrease in filling efficiency. [Solution] A solid electrolyte material comprising a sulfide solid electrolyte containing lithium, sulfur, and phosphorus, and an organic compound, wherein the organic compound has two or more benzene rings, and the melting point of the organic compound is 82°C or lower.

Description

[Technical Field]

[0001] This disclosure relates to solid electrolyte materials and batteries. [Background technology]

[0002] Various technologies have been proposed for solid electrolytes, such as those disclosed in Patent Document 1. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2024-093769 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] A problem arises when the packing density of the solid electrolyte material containing sulfide solid electrolytes and organic compounds is low, as this increases the resistance of the electrode layer containing the solid electrolyte material.

[0005] This disclosure has been made in view of the above circumstances, and its main purpose is to provide a solid electrolyte material that can suppress a decrease in filling efficiency. [Means for solving the problem]

[0006] In other words, this disclosure includes the following aspects: <1> A solid electrolyte material containing a sulfide solid electrolyte containing lithium, sulfur, and phosphorus, and an organic compound, The aforementioned organic compound has two or more benzene rings, A solid electrolyte material having a melting point of 82°C or lower for the aforementioned organic compound.

[0007] <2> The melting point of the aforementioned organic compound is 37°C or lower. <1> The solid electrolyte material described above.

[0008] <3> The aforementioned organic compound has two benzene rings. <1> or <2> The solid electrolyte material described above.

[0009] <4> The aforementioned organic compound is at least one selected from the group consisting of naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 1,4-dimethylnaphthalene, 1,5-dimethylnaphthalene, and biphenyl. <1> The solid electrolyte material described above.

[0010] <5> A battery having a positive electrode layer, a negative electrode layer, and an electrolyte layer, The aforementioned battery is <1> ~ <4> An electrode composite material comprising a solid electrolyte material described in any one of the above and an electrode active material is included in the positive electrode layer or the negative electrode layer. A battery in which at least a portion of the organic compound is present between the electrode active material and the sulfide solid electrolyte. [Effects of the Invention]

[0011] This disclosure offers the advantage of obtaining a solid electrolyte material that can suppress a decrease in filling efficiency. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic cross-sectional view illustrating a battery in this disclosure. [Figure 2] Figure 2 is a graph showing the relationship between the melting point of the organic compound and the packing density of each solid electrolyte material obtained in Examples 1-9 and Comparative Examples 1-6. [Figure 3] Figure 3 is a graph showing the relationship between the melting point of the organic compound and the packing density of each electrode layer obtained in Examples 10-12 and Comparative Examples 7-9. [Modes for carrying out the invention]

[0013] In this disclosure, unless otherwise specified, the average particle size is the median diameter (D50), which is the particle size at 50% of the cumulative value in the volume-based particle size distribution measured by laser diffraction-scattering particle size distribution analysis.

[0014] A. Solid electrolyte material In the present disclosure, a solid electrolyte material containing a sulfide solid electrolyte containing lithium element, sulfur element and phosphorus element, and an organic compound, wherein the organic compound has two or more benzene rings, and the melting point of the organic compound is 82°C or lower, is provided.

[0015] The solid electrolyte material contains a sulfide solid electrolyte and an organic compound.

[0016] The organic compound is a compound having two or more benzene rings. When the organic compound is not contained in the solid electrolyte material, the particles of the sulfide solid electrolyte are difficult to slide, and the filling rate of the solid electrolyte material decreases. However, when the organic compound is contained, the particles of the sulfide solid electrolyte are easy to slide, and the filling rate of the solid electrolyte material is improved. The organic compound used in the present disclosure is basically a non-polar and hydrophobic molecule, and is likely to adsorb to a highly hydrophobic substance. Since the sulfide solid electrolyte used in the present disclosure is a substance with low polarity, it has good compatibility with the organic compound. Since the organic compound improves the filling rate of the solid electrolyte material, it can be expected to reduce the voids in the electrode layer using the solid electrolyte material and suppress the increase in resistance. The melting point of the organic compound may be 82°C or lower, and may also be 37°C or lower. The organic compounds used in this disclosure are characterized by the stacking of multiple molecules of the organic compound via intermolecular forces between aromatic π bonds. When a solid electrolyte material is pressed, the organic compound acts as a lubricant, causing multiple particles of the sulfide solid electrolyte to slide between them in a shearing motion via the organic compound present between the particles. Therefore, in the case of organic compounds with strong stacking forces due to intermolecular forces between aromatic π bonds, i.e., high melting points (above 82°C), shearing is less likely to occur, and thus excellent lubrication cannot be expected. On the other hand, in the case of organic compounds with weak stacking forces due to intermolecular forces between aromatic π bonds, i.e., low melting points (below 82°C), shearing easily occurs when the solid electrolyte material is pressed, resulting in excellent lubrication and improved packing efficiency of the solid electrolyte material. The benzene rings contained in the organic compound may be two or more, three or fewer, or even just two. For the organic compound to exert a lubricating effect, it needs to stack via intermolecular forces between aromatic π bonds. It is presumed that when there are two or more benzene rings rather than one, the flatness of the molecule increases, making stacking easier and thus facilitating the exertion of a lubricating effect. When there are three or fewer benzene rings, it is presumed that the stacking force of the aromatic π bonds does not become too large, making it easier for the particles to slide against each other. Examples of organic compounds include condensed polycyclic hydrocarbons such as naphthalene, derivatives of condensed polycyclic hydrocarbons, biphenyls and their derivatives, and compounds in which multiple benzene rings are linked by organic groups. The organic compound may be at least one selected from the group consisting of naphthalene (melting point 80.2°C), 1-methylnaphthalene (melting point -22°C), 2-methylnaphthalene (melting point 37°C), 1,2-dimethylnaphthalene (melting point 1.6°C), 1,3-dimethylnaphthalene (melting point -6°C), 1,4-dimethylnaphthalene (melting point 7.6°C), 1,5-dimethylnaphthalene (melting point 82°C), 1,6-dimethylnaphthalene (melting point -13.9°C), 1,7-dimethylnaphthalene (melting point -6°C), 1-fluoronaphthalene (melting point -9°C), 1-chloronaphthalene (melting point -2.5°C), 1-bromonaphthalene (melting point -1.8°C), 1-iodonaphthalene (melting point 4.2°C), and biphenyl (melting point 69°C). The proportion of the organic compound relative to 100% by mass of the solid electrolyte material may be greater than 0% by mass, 1% or more by mass, 5% or less by mass, or 2% or less by mass. By performing Raman analysis on a solid electrolyte material, it is possible to confirm whether the above-mentioned organic compound is present in the solid electrolyte material.

[0017] The sulfide solid electrolyte contains lithium, sulfur, and phosphorus. The sulfide solid electrolyte may further contain Me (Me is at least one of As, Sb, Si, Ge, Sn, Bi, Al, Zn, Ga, and In). The sulfide solid electrolyte may also contain halogen elements such as F, Cl, Br, and I.

[0018] The sulfide solid electrolyte may be a glass-based (amorphous) sulfide solid electrolyte, a glass-ceramic sulfide solid electrolyte, or a crystalline sulfide solid electrolyte. The sulfide solid electrolyte may have a crystalline phase. Examples of the crystalline phase include a thio-LISICON type crystalline phase, an argyrodite type crystalline phase, and an LGPS type crystalline phase.

[0019] The composition of the sulfide solid electrolyte is not particularly limited. For example, xLi2S·(1 - x)P2S5 (0.5 ≦ x < 1), and yLiI·zLiBr·(100 - y - z)(xLi2S·(1 - x)P2S5) (0.5 ≦ x < 1, 0 ≦ y ≦ 30, 0 ≦ z ≦ 30), etc. may be mentioned. In these compositions, x may satisfy 0.7 ≦ x ≦ 0.8. Further, as another example of the composition of the sulfide solid electrolyte, Li 7-x PS 6-x X x may be mentioned. X is at least one of F, Cl, Br, and I, and x satisfies 0 ≦ x < 2. Further, as another example of the composition of the sulfide solid electrolyte, Li 4-x Me 1-x P x S4 (0 < x < 1) may be mentioned. The Me element is the same as the above - defined one. Examples of the sulfide solid electrolyte include Li3PS4 - LiI - LiBr, LiI - LiBr - Li2S - P2S5, LiI - Li2S - P2S5, LiI - Li2S - P2O5, and LiI - Li3PO4 - P2S5, etc.

[0020] The shape of the sulfide solid electrolyte may be particulate from the viewpoint of good handleability. Further, the average particle diameter (D50) of the particles of the sulfide solid electrolyte is not particularly limited and may be 1 nm to 100 μm. The proportion of the sulfide solid electrolyte with respect to 100% by mass of the solid electrolyte material may be 95% by mass or more, may be 98% by mass or more, the upper limit may be less than 100% by mass, and may be 99% by mass or less.

[0021] B. Battery In the present disclosure, a battery having a positive electrode layer, a negative electrode layer, and an electrolyte layer, the battery includes an electrode mixture containing the above - mentioned solid electrolyte material containing the sulfide solid electrolyte containing lithium element, sulfur element, and phosphorus element, the above - mentioned organic compound, and an electrode active material in the positive electrode layer or the negative electrode layer, and provides a battery in which at least a part of the above - mentioned organic compound exists between the electrode active material and the sulfide solid electrolyte.

[0022] The electrode composite material includes a solid electrolyte material and an electrode active material. At least a portion of the organic compounds in the electrode mixture are present between the electrode active material and the sulfide solid electrolyte. It is presumed that the organic compounds function as a barrier, suppressing side reactions of the sulfide solid electrolyte (improving reduction resistance). Here, the benzene ring has a conjugated structure in which double bonds and single bonds are alternately linked, and has a π electron cloud. Therefore, in organic compounds having two or more benzene rings, the region where the π electron cloud extends is wide, resulting in good chemical stability (oxidation resistance, reduction resistance), and as a result, it is presumed that the chemical stability of the sulfide solid electrolyte located near such organic compounds is also improved. It is presumed that, due to these mechanisms, resistance increase is suppressed in batteries using the electrode mixture of this disclosure. When the electrode mixture is included in the positive electrode layer, the electrode mixture is a positive electrode mixture, and the positive electrode mixture includes the above-mentioned solid electrolyte material and a positive electrode active material. When the electrode mixture is included in the negative electrode layer, the electrode mixture is a negative electrode mixture, and the negative electrode mixture includes the solid electrolyte material and the negative electrode active material. The battery of this disclosure may or may not contain the above-mentioned solid electrolyte material in the negative electrode layer, provided that the positive electrode layer contains the positive electrode composite material. The battery of this disclosure may or may not contain the above-mentioned solid electrolyte material in the positive electrode layer, provided that the negative electrode layer contains the negative electrode composite material. The battery of this disclosure may include a positive electrode composite material in the positive electrode layer and a negative electrode composite material in the negative electrode layer.

[0023] The battery in this disclosure comprises a positive electrode layer, a negative electrode layer, and an electrolyte layer, and typically includes a positive electrode containing a positive electrode layer and a negative electrode containing a negative electrode layer. FIG. 1 is a schematic cross-sectional view illustrating a battery according to the present disclosure. The battery 10 shown in FIG. 1 includes a positive electrode layer 1, a negative electrode layer 2, an electrolyte layer 3 disposed between the positive electrode layer 1 and the negative electrode layer 2, a positive electrode current collector 4 that collects current from the positive electrode layer 1, and a negative electrode current collector 5 that collects current from the negative electrode layer 2. In the present disclosure, at least one of the positive electrode layer 1 or the negative electrode layer 2 contains the solid electrolyte material described in the above "A. Solid Electrolyte Material". According to the present disclosure, by using the above-described solid electrolyte material, a battery with a high filling rate of the electrode layer and low resistance can be obtained.

[0024] [Positive Electrode] The positive electrode has a positive electrode layer and may further have a positive electrode current collector as needed. The positive electrode layer is a layer containing at least a positive electrode active material. The positive electrode layer may be a layer containing a positive electrode composite material including the solid electrolyte material and the positive electrode active material. Further, the positive electrode layer may contain at least one of a solid electrolyte, a conductive material, and a binder as needed.

[0025] Examples of the positive electrode active material include oxide active materials. Examples of the oxide active materials include rock salt layer-type active materials such as LiCoO2, LiMnO2, LiNiO2, LiVO2, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and other rock salt layer-type active materials, spinel-type active materials such as LiMn2O4, Li4Ti5O 12 , and Li(Ni 0.5 Mn 1.5 )O4 and other spinel-type active materials, olivine-type active materials such as LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4. A coating layer containing a Li-ion conductive compound may be formed on the surface of the positive electrode active material. This is because it can suppress the reaction between the positive electrode active material and the solid electrolyte. Examples of Li-ion conductive compounds include B2O3, Li2B4O7, LiBPO4, Li3PO4, LiPO3, and LiNbO3. The thickness of the coating layer is, for example, 1 nm to 30 nm. The coverage rate of the Li-ion conductive compound coating the positive electrode active material is, for example, 70% or more, may be 90% or more, or may be 100%. The method of coating with the Li-ion conductive compound is not particularly limited, and conventionally known methods can be used as appropriate.

[0026] The positive electrode active material is usually particulate. The positive electrode active material may be primary particles or secondary particles formed by aggregation of primary particles. The average particle size (D50) of the positive electrode active material is not particularly limited, but for example, it may be 0.01 μm or more and 50 μm or less, or 0.5 μm or more and 30 μm or less.

[0027] The proportion of positive electrode active material in the positive electrode layer may be, for example, 20% by mass or more. If the proportion of positive electrode active material is too low, a sufficient energy density may not be obtained. On the other hand, the proportion of positive electrode active material in the positive electrode layer may be, for example, 80% by mass or less. If the proportion of positive electrode active material is too high, the ionic conductivity and electronic conductivity in the positive electrode layer may relatively decrease.

[0028] The proportion of sulfide solid electrolyte in the positive electrode layer may be, for example, 10% by mass or more. If the proportion of sulfide solid electrolyte is too low, there may be insufficient ion conduction paths in the positive electrode layer. On the other hand, the proportion of sulfide solid electrolyte in the positive electrode layer may be, for example, 60% by mass or less. If the proportion of sulfide solid electrolyte is too high, the proportion of positive electrode active material will be relatively low, which may result in a lower energy density.

[0029] The positive electrode layer may contain a conductive material. Adding a conductive material improves the electronic conductivity of the positive electrode layer. Examples of conductive materials include carbon materials, metal particles, and conductive polymers. Examples of carbon materials include particulate carbon materials such as acetylene black (AB) and Ketjenblack (KB), and fibrous carbon materials such as vapor-processed carbon fiber (VGCF), carbon nanotubes (CNT), and carbon nanofibers (CNF).

[0030] The proportion of conductive material in the positive electrode layer may be, for example, 0.1% by mass or more. If the proportion of conductive material is too low, there may be insufficient electron conduction paths in the positive electrode layer. On the other hand, the proportion of conductive material in the positive electrode layer may be, for example, 5% by mass or less. If the proportion of conductive material is too high, the proportion of positive electrode active material will be relatively low, which may result in a lower energy density.

[0031] The positive electrode layer may contain a binder. Examples of binders include styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), butadiene rubber (BR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-isoprene-styrene block copolymer (SIS), and ethylene-propylene-diene copolymer (EPDM).

[0032] The proportion of binder in the positive electrode layer may be, for example, 0.5 mass% or more. If the proportion of binder is too low, the increase in resistance due to charging and discharging may not be sufficiently reduced. On the other hand, the proportion of binder in the positive electrode layer may be, for example, 5 mass% or less. If the proportion of binder is too high, the proportion of positive electrode active material will be relatively low, which may result in a lower energy density.

[0033] The thickness of the positive electrode layer may be, for example, 0.1 μm or more and 1000 μm or less.

[0034] The method for manufacturing the positive electrode layer is not particularly limited, but for example, it may involve mixing the positive electrode mixture with a solvent to obtain a positive electrode slurry, coating the positive electrode slurry onto a positive electrode current collector, drying it, and forming a positive electrode layer. When forming the positive electrode layer, a pressing process may be performed to press the positive electrode layer in the thickness direction. Examples of pressing processes include roller pressing and flat plate pressing. Examples of solvents include tetralin, diisobutyl ketone, butyl butyrate, mesitylene, heptane, dibutyl ether, decane, dodecane, isodecane, and toluene, and may contain two or more of these components.

[0035] Examples of materials for the positive electrode current collector include SUS, Cr, Au, Pt, Zn, aluminum, copper, nickel, iron, titanium, and carbon. The thickness of the positive electrode current collector is, for example, 0.1 μm or more and 100 μm or less. The shape of the positive electrode current collector may be foil-like or plate-like. The planar shape of the positive electrode current collector is not particularly limited, but examples include circular, elliptical, rectangular, and any polygonal shape. The positive electrode current collector may have a buffer layer, an elastic layer, or a PTC (Positive Temperature Coefficient) thermistor layer on its surface.

[0036] [Negative electrode] The negative electrode has a negative electrode layer and, if necessary, further has a negative electrode current collector. The negative electrode layer is a layer containing at least a negative electrode active material. The negative electrode layer may also contain a negative electrode composite material comprising the solid electrolyte material and the negative electrode active material. Furthermore, the negative electrode layer may optionally contain at least one of a solid electrolyte, a conductive material, and a binder. Examples of negative electrode active materials include Si-based active materials, carbon-based active materials, oxide-based active materials, and Li-based active materials. Examples of Si-based active materials include elemental Si, Si alloys, Si oxides, and Si carbides. Examples of metals other than Si in Si alloys include Li, Sn, Fe, Co, Ni, Ti, Cr, Na, W, Mo, V, Nb, Zr, and Hf. Si alloys may contain only one metal other than Si, or two or more. An example of a Si oxide is SiO. An example of a Si carbide is SiC. Examples of carbon-based active materials include graphite, hard carbon, and soft carbon. Examples of oxide-based active materials include lithium titanate. Examples of lithium-based active materials include elemental lithium and lithium alloys. Other metallic elements contained in lithium alloys include magnesium, silver, silver, indigo, tungsten, silicon, galvanic acid, aurum, and phosphate. The conductive material and binder used in the negative electrode layer are the same as those described above for the positive electrode layer.

[0037] Examples of materials for the negative electrode current collector include SUS, aluminum, copper, nickel, iron, titanium, and carbon. The thickness of the negative electrode current collector varies depending on its shape, but may be in the range of, for example, 1 μm to 50 μm. The shape of the negative electrode current collector may be foil-like or plate-like. The planar shape of the negative electrode current collector is not particularly limited, but examples include circular, elliptical, rectangular, and any polygonal shape. The negative electrode current collector may have a buffer layer, an elastic layer, or a PTC thermistor layer on its surface.

[0038] [Electrolyte layer] The electrolyte layer is a layer formed between the positive electrode layer and the negative electrode layer, and contains at least an electrolyte. The electrolyte may be a solid electrolyte (sometimes referred to as SE) or a liquid electrolyte (electrolyte solution). Non-aqueous electrolytes can be used as the electrolyte. One type of non-aqueous electrolyte may be used alone, or two or more types may be used in combination.

[0039] As a non-aqueous electrolyte, one containing a lithium salt and a non-aqueous solvent is typically used. Examples of lithium salts include inorganic lithium salts such as LiPF6, LiBF4, LiClO4, and LiAsF6; and organic lithium salts such as LiCF3SO3, LiN(SO2CF3)2(Li-TFSI), LiN(SO2C2F5)2, and LiC(SO2CF3)3. Examples of non-aqueous solvents include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone, sulfolane, acetonitrile (AcN), dimethoxymethane, 1,2-dimethoxyethane (DME), 1,3-dimethoxypropane, diethyl ether, tetraethylene glycol dimethyl ether (TEGDME), tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfoxide (DMSO), and mixtures thereof. The concentration of the lithium salt in the non-aqueous electrolyte may be, for example, 0.3 to 5 M.

[0040] The electrolyte layer may be impregnated with an electrolyte such as the aforementioned electrolyte solution, and a separator may be used to prevent contact between the positive electrode layer and the negative electrode layer. The material for the separator is not particularly limited as long as it is a porous membrane. Examples include polyethylene (PE), polypropylene (PP), polyester, polyvinyl alcohol, cellulose, and polyamide resins, with polyethylene and polypropylene being particularly preferred. The separator may have a single-layer structure or a multi-layer structure. Examples of multi-layer separators include a PE / PP two-layer separator, or a PP / PE / PP or PE / PP / PE three-layer separator. The separator may be made of nonwoven fabrics such as resin nonwoven fabric or glass fiber nonwoven fabric.

[0041] The electrolyte layer may be a solid electrolyte layer composed of solids. The solid electrolyte layer contains a solid electrolyte and, if necessary, a binder, etc. The solid electrolyte layer contains the sulfide solid electrolyte described in "A. Solid Electrolyte Material" above as the solid electrolyte. Solid electrolytes can be used individually or in combination of two or more types. When using two or more types of solid electrolytes, they may be mixed together, or two or more layers of solid electrolytes may be formed to create a multilayer structure. The proportion of solid electrolyte in the solid electrolyte layer is not particularly limited, but may be, for example, 50% by mass or more, or 100% by mass. The solid electrolyte layer may contain less than 10% by mass of electrolyte relative to the total amount of the solid electrolyte layer. Examples of binders include those that can be incorporated into the positive electrode layer as described above. The binder content in the solid electrolyte layer may be 0% to 10% by mass relative to the total amount of the solid electrolyte layer.

[0042] The thickness of the electrolyte layer may be, for example, 0.1 μm or more and 1000 μm or less.

[0043] The battery in this disclosure may further include a restraining jig that applies restraining pressure along the thickness direction to the positive electrode layer, electrolyte layer, and negative electrode layer. In particular, if the electrolyte layer is a solid electrolyte layer, restraining pressure may be applied to form good ion conduction paths and electron conduction paths. The restraining pressure may be, for example, 0.1 MPa or more. On the other hand, the restraining pressure may be, for example, 100 MPa or less.

[0044] [battery] The type of battery in this disclosure is not particularly limited, but is typically a lithium-ion battery. Furthermore, the battery in this disclosure may be a liquid battery in which the electrolyte layer contains an electrolyte solution, or a solid battery in which the electrolyte layer contains a solid electrolyte. The solid battery may be a semi-solid battery or a fully solid battery. In this disclosure, a semi-solid battery is a battery in which the electrolyte layer has a solid electrolyte and a liquid component (e.g., solvent and electrolyte solution). In this disclosure, a fully solid battery is a battery in which the electrolyte layer has only a solid electrolyte as the electrolyte. Furthermore, the battery in this disclosure may be a primary battery or a secondary battery, but is particularly favored as a secondary battery because it can be repeatedly charged and discharged and is useful, for example, as an in-vehicle battery. The shape of the battery is not particularly limited and may be, for example, coin-type, cylindrical, prismatic, sheet-type, button-type, flat-type, or stacked-type.

[0045] Applications of batteries include, for example, powering vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), gasoline cars, and diesel cars. In particular, they may be used as power sources for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or battery electric vehicles (BEVs). Batteries may also be used as power sources for mobile devices other than vehicles (e.g., trains, ships, aircraft), and as power sources for electrical products such as information processing devices. [Examples]

[0046] <Example 1> (Preparation of solid electrolyte materials) 3000 mg of mesitylene was placed in a propylene container, and 20 mg of 1,5-dimethylnaphthalene was added as an organic compound and dissolved. 1000 mg of glass-ceramic sulfide solid electrolyte particles were then added, and the mixture was stirred with an ultrasonic homogenizer to obtain a slurry. The slurry was placed in a petri dish, and then the mesitylene was removed by heating and drying to obtain a solid electrolyte material.

[0047] <Example 2> A solid electrolyte material was obtained in the same manner as in Example 1, except that the organic compound was changed to naphthalene.

[0048] <Example 3> A solid electrolyte material was obtained in the same manner as in Example 1, except that the organic compound was changed to biphenyl.

[0049] <Example 4> A solid electrolyte material was obtained in the same manner as in Example 1, except that the organic compound was changed to 2-methylnaphthalene.

[0050] <Example 5> A solid electrolyte material was obtained in the same manner as in Example 1, except that the organic compound was changed to 1,4-dimethylnaphthalene.

[0051] <Example 6> A solid electrolyte material was obtained in the same manner as in Example 1, except that the organic compound was changed to 1-methylnaphthalene.

[0052] <Comparative Example 1> 3000 mg of mesitylene was placed in a propylene container, and 1000 mg of glass-ceramic sulfide solid electrolyte particles were added to it. A slurry was obtained by stirring with an ultrasonic homogenizer. The slurry was placed in a petri dish, and then the mesitylene was removed by heating and drying to obtain a solid electrolyte material.

[0053] <Comparative Example 2> A solid electrolyte material was obtained in the same manner as in Example 1, except that the organic compound was changed to decane.

[0054] <Comparative Example 3> A solid electrolyte material was obtained in the same manner as in Example 1, except that the organic compound was changed to anthracene.

[0055] <Comparative Example 4> A solid electrolyte material was obtained in the same manner as in Example 1, except that the organic compound was changed to 2,3-dimethylnaphthalene.

[0056] <Example 7> A solid electrolyte material was obtained in the same manner as in Example 1, except that the glass-ceramic sulfide solid electrolyte was changed to a crystalline sulfide solid electrolyte.

[0057] <Example 8> A solid electrolyte material was obtained in the same manner as in Example 1, except that the glass-ceramic sulfide solid electrolyte was changed to a crystalline sulfide solid electrolyte and the organic compound was changed to 1,4-dimethylnaphthalene.

[0058] <Example 9> A solid electrolyte material was obtained in the same manner as in Example 1, except that the glass-ceramic sulfide solid electrolyte was changed to a crystalline sulfide solid electrolyte and the organic compound was changed to 1-methylnaphthalene.

[0059] <Comparative Example 5> A solid electrolyte material was obtained using the same method as in Comparative Example 1, except that the glass-ceramic sulfide solid electrolyte was changed to a crystalline sulfide solid electrolyte.

[0060] <Comparative Example 6> A solid electrolyte material was obtained in the same manner as in Example 1, except that the glass-ceramic sulfide solid electrolyte was changed to a crystalline sulfide solid electrolyte and the organic compound was changed to decane.

[0061] <Measurement of filling density of solid electrolyte materials> 100 mg of each solid electrolyte material obtained in Examples 1-9 and Comparative Examples 1-6 was placed in a φ11.28 mm cylinder, the top and bottom layers of the solid electrolyte material were clamped with SUS pins, and the cylinder was pressed at 19.6 MPa. The volume of the solid electrolyte material after pressing was taken as the apparent volume of the solid electrolyte material. The ratio of the total volume of the raw materials (organic compounds and sulfide solid electrolytes) of the solid electrolyte material to the apparent volume of the solid electrolyte material was calculated as the packing rate using the following formula. The results are shown in Table 1. Packing rate = (Total volume of raw materials for solid electrolyte material ÷ Apparent volume of solid electrolyte material) × 100

[0062] [Table 1]

[0063] Figure 2 is a graph showing the relationship between the melting point of the organic compound and the packing density of each solid electrolyte material obtained in Examples 1-9 and Comparative Examples 1-6. Comparing Examples 1-6 and Comparative Examples 1-4, which use glass-ceramic sulfide solid electrolytes, it can be seen that Comparative Example 2, which uses an organic compound without a benzene ring, has a lower packing density than Comparative Example 1, and Comparative Examples 2-3, which use organic compounds with a melting point above 82°C, have a lower packing density than Comparative Example 1. However, Examples 1-6, which use organic compounds having two benzene rings and a melting point of 82°C or lower, have a higher packing density than Comparative Example 1. Comparing Examples 7-9 and Comparative Examples 5-6, which use crystalline sulfide solid electrolytes, Comparative Example 6, which uses an organic compound without a benzene ring, has a lower packing density than Comparative Example 5. However, Examples 7-9, which use an organic compound having two benzene rings and a melting point of 82°C or lower, have a higher packing density than Comparative Example 5. These results indicate that using organic compounds having two or more benzene rings and a melting point of 82°C or lower allows the organic compounds to function as lubricants and improves the packing efficiency.

[0064] <Comparative Example 7> (Preparation of electrode composite material) Mesitylene was placed in a propylene container, and nickel layered oxide (a layered active material containing nickel) as the positive electrode active material, a glass-ceramic sulfide solid electrolyte, and a conductive material were added in a ratio of 74 / 23 / 3 vol%. A slurry was obtained by stirring with an ultrasonic homogenizer. The slurry was placed in a petri dish, and then the mesitylene was removed by heating and drying to obtain an electrode mixture.

[0065] <Example 10> (Preparation of electrode composite material) Mesitylene was placed in a propylene container, and 20 mg of 1,5-dimethylnaphthalene was added as an organic compound and dissolved. Nickel layered oxide as the positive electrode active material, a glass-ceramic sulfide solid electrolyte, and a conductive material were added in a ratio of 74 / 23 / 3 vol%, and the mixture was stirred with an ultrasonic homogenizer to obtain a slurry. The slurry was placed in a petri dish, and then the mesitylene was removed by heating and drying to obtain an electrode mixture.

[0066] <Example 11> An electrode composite was obtained in the same manner as in Example 10, except that the organic compound was changed to 1,4-dimethylnaphthalene.

[0067] <Example 12> An electrode composite was obtained in the same manner as in Example 10, except that the organic compound was changed to 1-methylnaphthalene.

[0068] <Comparative Example 8> An electrode composite was obtained in the same manner as in Example 10, except that the organic compound was changed to decane.

[0069] <Comparative Example 9> An electrode composite was obtained in the same manner as in Example 10, except that the organic compound was changed to anthracene.

[0070] <Measurement of electrode layer filling density> 100 mg of each electrode composite obtained in Examples 10-12 and Comparative Examples 7-9 was placed in a φ11.28 mm cylinder, the resulting electrode layer was clamped between SUS pins, and pressed at 19.6 MPa. The volume of the electrode layer after pressing was taken as the apparent volume of the electrode layer. The packing efficiency, calculated as the ratio of the total volume of the electrode layer raw materials (organic compound, sulfide solid electrolyte, nickel layered oxide, and conductive material) to the apparent volume of the electrode layer, was calculated using the following formula. The results are shown in Table 2. Electrode layer packing efficiency = (Total volume of raw materials before electrode layer fabrication ÷ Apparent volume of electrode layer) × 100

[0071] [Table 2]

[0072] Figure 3 is a graph showing the relationship between the melting point of the organic compound and the packing density of each electrode layer obtained in Examples 10-12 and Comparative Examples 7-9. Comparative Example 8, which used an organic compound without a benzene ring, had a lower packing density than Comparative Example 7. Comparative Example 9, which used an organic compound with a melting point exceeding 82°C, also had a lower packing density than Comparative Example 7. However, Examples 10 to 12, which used an organic compound having two benzene rings and a melting point of 82°C or lower, had a higher packing density than Comparative Example 7. Therefore, it can be expected that the voids in the electrode layer will be reduced, thereby reducing resistance. [Explanation of Symbols]

[0073] 1 ... Positive electrode layer 2 ... Negative electrode layer 3...electrolyte layer 4...Positive electrode current collector 5...Negative electrode current collector 10...battery

Claims

1. A solid electrolyte material containing a sulfide solid electrolyte containing lithium, sulfur, and phosphorus, and an organic compound, The aforementioned organic compound has two or more benzene rings, A solid electrolyte material wherein the melting point of the aforementioned organic compound is 82°C or lower.

2. The solid electrolyte material according to claim 1, wherein the melting point of the organic compound is 37°C or lower.

3. The solid electrolyte material according to claim 1, wherein the organic compound has two benzene rings.

4. The solid electrolyte material according to claim 1, wherein the organic compound is at least one selected from the group consisting of naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 1,4-dimethylnaphthalene, 1,5-dimethylnaphthalene, and biphenyl.

5. A battery having a positive electrode layer, a negative electrode layer, and an electrolyte layer, The battery includes an electrode composite material comprising a solid electrolyte material according to any one of claims 1 to 4 and an electrode active material in the positive electrode layer or the negative electrode layer. A battery in which at least a portion of the organic compound is present between the electrode active material and the sulfide solid electrolyte.

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