Active material and method for producing the same, electrode mixture, and battery

Abstract

The active material of the present invention comprises a conductive material and a compound containing lithium (Li), sulfur (S), and M, and comprising a crystalline phase having an argyrodite-type crystal structure, wherein the conductive material is dispersed on the surface and within the particles of the compound. The M element represents phosphorus (P), etc. The active material of the present invention is a composite material of the aforementioned compound and the aforementioned conductive material. The aforementioned conductive material is preferably a carbon material or a metal material. The content of the aforementioned lithium element in the aforementioned active material is also preferably not less than 10% by mass and not more than 25% by mass.

Description

Technical Field

[0001] The present invention relates to an active material and a method for producing the same. In addition, the present invention relates to an electrode mixture and a battery containing the active material. Background Art

[0002] Lithium-ion batteries are widely used as power sources for portable electronic devices such as laptop computers and mobile phones due to their high energy density and ease of miniaturization and weight reduction. Furthermore, recent developments are underway to develop high-output, high-capacity lithium-ion batteries for use in electric vehicles and hybrid electric vehicles.

[0003] For example, Patent Document 1 proposes a cathode active material comprising a sulfide solid electrolyte material and a conductive material. Furthermore, Non-Patent Document 1 proposes a cathode active material comprising a composite of Li3PS4 glass as a sulfide solid electrolyte and a carbon-based conductive additive.

[0004] However, the present inventors have repeatedly studied the sulfide solid electrolyte used in lithium-ion batteries and proposed a method using a composition formula Li 7-x PS 6-x A compound represented by Ha (wherein x is 0.2 to 1.8, and Ha represents Cl or Br) (see Patent Document 2). This compound has high lithium ion conductivity.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: US2019 / 260065A1

[0008] Patent Document 2: US2016 / 156064A1

[0009] Non-patent literature

[0010] Non-Patent Literature 1: Journal of Power Sources 293 (2015), 721-725 Summary of the Invention

[0011] The present inventors have conducted research with the goal of improving the performance of lithium-ion batteries and have discovered that a more excellent positive electrode active material is required to further improve the performance of lithium-ion batteries.

[0012] An object of the present invention is to provide an active material capable of improving the performance of a lithium ion battery.

[0013] The electrolyte and active material used in batteries each play completely different roles. For example, conventional techniques that use materials used for sulfide solid electrolytes as active materials have found it difficult to further improve battery performance, such as capacity and rate characteristics. On the other hand, the present inventors have discovered that by combining the sulfide solid electrolyte proposed in Patent Document 2 with a conductive material to form a composite, it not only functions as an active material but also, when used as a positive electrode active material in lithium-ion batteries, can further improve battery performance, such as capacity and rate characteristics.

[0014] The present invention is based on the above-mentioned findings and solves the above-mentioned problems by providing the following active material, which contains a compound and a conductive material, and is a composite material of the above-mentioned compound and the above-mentioned conductive material, wherein the compound contains lithium (Li), sulfur (S) and M elements (M is at least one of phosphorus (P), germanium (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co) and manganese (Mn)) and includes a crystalline phase having a argyrodite-type crystal structure.

[0015] Furthermore, the present invention provides a method for producing the active material as a suitable method for producing the active material, comprising the following steps:

[0016] In a first step, a compound is prepared, wherein the compound contains lithium (Li), sulfur (S), and M (M is at least one of phosphorus (P), germanium (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co), and manganese (Mn)) and includes a crystalline phase having an argyrodite-type crystal structure; and

[0017] In the second step, the compound is mixed with a conductive material to form a composite. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a charge and discharge curve of a battery obtained using the positive electrode active material prepared in Example 1.

[0019] Figure 2 This is a charge and discharge curve of a battery obtained using the positive electrode active material prepared in Example 5.

[0020] Figure 3 This is a charge and discharge curve of a battery obtained using the positive electrode active material prepared in Comparative Example 3.

[0021] Figure 4 This is a SEM-EDS image of the positive electrode active material prepared in Example 5.

[0022] Figure 5 This is a SEM-EDS image of the positive electrode active material prepared in Comparative Example 4.

[0023] Figure 6 This is a cross-sectional SEM-EDS image of a battery obtained using the positive electrode active material prepared in Example 5.

[0024] Figure 7 This is a cross-sectional SEM-EDS image of a battery obtained using the positive electrode active material prepared in Comparative Example 4.

[0025] Figure 8 These are the X-ray diffraction patterns of the positive electrode active materials prepared in Examples 1, 3, and 4.

[0026] Figure 9 These are the X-ray diffraction patterns of the positive electrode active materials prepared in Comparative Examples 3 and 4.

[0027] Figure 10 This is a charge and discharge curve of a battery obtained using the positive electrode active material prepared in Comparative Example 4. DETAILED DESCRIPTION

[0028] Hereinafter, the present invention will be described based on its preferred embodiments. The present invention relates to an active material for a battery. Currently, lithium-ion batteries are the mainstream of secondary batteries, and lithium-ion batteries are required to have a further high energy density. From this point of view, solid-state batteries that use sulfides as solid electrolytes, which have few restrictions on active materials and can achieve high energy density, have attracted much attention. In addition, for the purpose of achieving further high energy density, active materials with high capacity are sought. Furthermore, active materials with high rate characteristics that can cope with short-time charge and discharge are also sought. The active material of the present invention meets these requirements.

[0029] The active material of the present invention comprises particles of a specific compound and a conductive material composited with the particles. In other words, the active material of the present invention comprises particles composed of a main body portion comprising particles of the specific compound and a conductive portion comprising a conductive material dispersed on the surface and / or within the main body portion and imparting electron conductivity. These main body portion and conductive portion are described below.

[0030] The main body is composed of a compound containing a specific element. Specifically, the main body is preferably composed of a compound containing lithium (Li), sulfur (S), and element M. Element M is preferably at least one of phosphorus (P), germanium (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co), and manganese (Mn).

[0031] Examples of compounds containing Li, S, and M include Li7PS6, Li 7+3x (P 5+ 1-x Fe 2+ x )S6、Li 7+x (P 5+ 1-x Si 4+ x )S6, etc. (wherein, x represents a number greater than or equal to 0.1 and less than or equal to 1.0).

[0032] In addition, as a compound comprising a Li element, an S element, and an M element, a compound comprising other elements on the basis of these three elements can also be used. As such other elements, for example, halogen (X) elements can be cited. By using a compound comprising an X element on the basis of a Li element, an S element, and an M element, the characteristics of the active material of the present invention become higher, so it is preferred. As the X element, at least one selected from F, Cl, Br, and I can be used.

[0033] From the viewpoint of improving the properties as an active material due to the improvement of ion conductivity, the aforementioned compound containing Li element, S element, M element and X element is preferably a compound having the composition formula (1): Li a MS b X c (wherein, M is at least one element selected from phosphorus (P), germanium (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co) and manganese (Mn). X is at least one element selected from fluorine (F), chlorine (Cl), bromine (Br) and iodine (I)).

[0034] From the perspective of improving lithium ion conductivity, a is preferably 3.0 to 9.0, more preferably 3.5 to 8.0, and even more preferably 4.0 to 7.5. Furthermore, b is preferably 3.5 to 6.0, more preferably 4.0 to 5.8, and even more preferably 4.2 to 5.5. Furthermore, c is preferably 0.10 to 3.0, more preferably 0.50 to 2.5, and even more preferably 1.0 to 1.8.

[0035] In particular, the M element in the above composition formula is preferably at least one of phosphorus (P), germanium (Ge), antimony (Sb), tin (Sn) and silicon (Si). From the perspective of improving the characteristics as an active material, it is particularly preferred to include phosphorus (P).

[0036] From the viewpoint of improving the properties as an active material, the compound constituting the main body is particularly preferably a compound having the composition formula (2): Li 7-d MS 6-d X d In the formula, d is preferably 0.40 to 2.2, more preferably 0.80 to 2.0, and even more preferably 1.2 to 1.8.

[0037] In the composition formulas (1) and (2), a portion of the M element may be substituted with one or more elements selected from silicon (Si), germanium (Ge), tin (Sn), lead (Pb), boron (B), aluminum (Al), gallium (Ga), arsenic (As), antimony (Sb), and bismuth (Bi). In this case, formula (1) becomes Li a (M1 1-y M2 y )S b X c , formula (2) becomes Li 7-d (M1 1-y M2 y )S 6-d X d M2 is one or more elements selected from silicon (Si), germanium (Ge), tin (Sn), lead (Pb), boron (B), aluminum (Al), gallium (Ga), arsenic (As), antimony (Sb), and bismuth (Bi). y is preferably 0.010 to 0.70, more preferably 0.020 to 0.40, and even more preferably 0.050 to 0.20. It should be noted that the M1 element is the same as the M element described in the composition formula (1).

[0038] The composition of each element in the compound constituting the main body can be measured by, for example, ICP emission spectrometry.

[0039] The compound constituting the main body preferably contains the aforementioned elements and includes a crystalline phase having an argyrodite-type crystal structure. This further improves the properties of the active material of the present invention. In particular, the compound constituting the main body preferably includes a crystalline phase having a cubic argyrodite-type crystal structure. Whether the active material of the present invention includes a crystalline phase having an argyrodite-type crystal structure can be determined by analyzing the active material of the present invention using X-ray diffraction. For example, CuKα radiation can be used.

[0040] The compound constituting the main body preferably has peaks at 2θ=25.19°±1.00° and 29.62°±1.00° in an X-ray diffraction pattern measured using CuKα1 radiation. These peaks are derived from an argyrodite-type crystal phase.

[0041] The compound constituting the main body preferably has a peak at positions selected from the group consisting of 2θ=15.34°±1.00°, 17.74°±1.00°, 30.97°±1.00°, 44.37°±1.00°, 47.22°±1.00°, and 51.70°±1.00° in addition to having peaks at positions 2θ=25.19°±1.00° and 29.62°±1.00° in the X-ray diffraction pattern measured using CuKα1 radiation. The invention also provides a peak at one or more positions within 2θ=0.00°. In addition to peaks at 2θ=25.19°±1.00° and 29.62°±1.00°, it also preferably provides peaks at all of 2θ=15.34°±1.00°, 17.74°±1.00°, 30.97°±1.00°, 44.37°±1.00°, 47.22°±1.00°, and 51.70°±1.00°. These peaks are derived from the argyrodite-type crystal phase.

[0042] The peak position is expressed as ±1.00° from the center, but is preferably ±0.500° from the center, and more preferably ±0.300° from the center.

[0043] The main body contains the above-mentioned compound and may contain other materials and other components as needed. Therefore, the main body may contain a single phase composed of a crystalline phase of an argyrodite-type crystal structure, or the main body may contain other phases in addition to containing this phase. For example, the core may contain a Li2S phase, Li3PS4 phase, Li4P2S6 phase, LiCl or LiBr phase, etc. in addition to containing a crystalline phase of an argyrodite-type crystal structure. In particular, when the main body contains a Li2S phase in addition to containing a crystalline phase of an argyrodite-type crystal structure, it is preferred from the perspective of improving the capacity of the active material. In particular, the main body preferably uses a compound containing Li, S, M and X elements and containing a crystalline phase having an argyrodite-type crystal structure as the main material. In addition, in addition to containing the above-mentioned other materials and other components, the main body may also contain unavoidable impurities to the extent that the adverse effect on the effect of the present invention is minimal, for example, less than 5% by mass, and particularly less than 3% by mass.

[0044] The main body containing the compound has the form of particles, and the conductive part containing the conductive material is arranged on the surface and inside of the particles. As the conductive material, a material with electronic conductivity can be used without particular limitation. As the conductive material, various metal materials and conductive non-metallic materials can be listed. Any one of these metal materials and conductive non-metallic materials can be used, or both can be used in combination. As the aforementioned metal material, various precious metal elements can be listed, such as gold (Au) element, silver (Ag) element, platinum (Pt) element, palladium (Pd) element, rhodium (Rh) element, iridium (Ir) element, ruthenium (Ru) element and osmium (Os) element. In addition, various transition metal elements can be listed, such as copper (Cu) element, iron (Fe) element and tin (Sn) element. These metal elements can be used alone, or two or more can be used in combination.

[0045] As the aforementioned conductive non-metallic material, for example, a carbon material can be used. Examples thereof include graphite, acetylene black, carbon black, carbon nanofibers, carbon nanotubes, nanographene, and fullerene nanowhiskers. These carbon materials can be used alone or in combination of two or more. Among these carbon materials, carbon black is preferably used from the viewpoint of improving the initial capacity and discharge rate characteristics of the battery. From the viewpoint of making this advantage more significant, as the carbon black, Ketjen black is preferably used, among which furnace black is preferably used, and oil furnace black is particularly preferably used.

[0046] The conductive portion composed of various conductive materials serves as an electron conduction path when lithium is desorbed or absorbed from the main body, and therefore needs to be uniformly dispersed and closely adhered to the surface and the interior.

[0047] From the perspective of uniformly dispersing the conductive portion containing the conductive material on the surface and inside the main body, the size of the conductive material is preferably smaller than that of the main body. Specifically, when the particle size of the main body is represented by D1 and the particle size of the conductive material is represented by D2, the value of D1 / D2 is preferably, for example, 2 or greater, more preferably 5 or greater, and even more preferably 10 or greater. On the other hand, the value of D1 / D2 is preferably, for example, 1000 or less, more preferably 500 or less, and even more preferably 10 or more and 100 or less.

[0048] The particle size D1 of the main body is preferably, for example, 0.1 μm or greater, more preferably 0.2 μm or greater, and even more preferably 0.5 μm or greater. Meanwhile, D1 is preferably, for example, 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. Furthermore, the particle size D2 of the conductive portion is preferably, for example, 1 nm or greater, more preferably 10 nm or greater, and even more preferably 20 nm or greater. Meanwhile, D2 is preferably, for example, 500 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less.

[0049] The particle size of the main body is the volume cumulative particle size D when the cumulative volume is 50% by volume, measured by laser diffraction scattering particle size distribution measurement method. 50 (hereinafter referred to as "D 50 " refers to the particle size D 50 ). On the other hand, when the particle size of the conductive portion is dispersed inside the particles of the main body, it is difficult to measure it by laser diffraction scattering particle size distribution measurement. Therefore, by using SEM (scanning electron microscope) or TEM (transmission electron microscope), the conductive portion dispersed inside the main body is directly observed to measure the average particle size. It should be noted that, for example, when the conductive material is the above-mentioned carbon nanotube or carbon nanofiber, the fiber diameter refers to: the diameter of the fiber cross section, or the average value of the major diameter and the minor diameter.

[0050] The active material of the present invention is a material in which a main body and a conductive part are composited, that is, a composite material of particles of a compound constituting the main body and a conductive material constituting the conductive part. In the "composite" mode, it is preferably a state in which the conductive part and the main body are inseparable and closely integrated and dispersed on the surface and inside of the main body. As the "composite" mode, for example, the particles of the conductive material are dispersed on the surface and / or inside of the particles of the compound in an inseparable manner; the particles of the compound constituting the main body and the particles of the conductive material constituting the conductive part undergo a chemical reaction and are bonded. "The particles of the conductive material are dispersed on the surface and inside of the particles of the compound constituting the main body in an inseparable manner" refers to the following state: for the active material of the present invention, when the constituent elements of the compound constituting the main body (such as sulfur) and the constituent elements of the conductive material constituting the conductive part are mapped, it can be confirmed that the constituent elements of the compound constituting the main body (such as sulfur) and the constituent elements of the conductive material constituting the conductive part exist in an overlapping manner. Alternatively, it refers to the following state: when observing a cross-section of the positive electrode layer of a battery produced using the active material of the present invention, it can be confirmed that the constituent elements of the compound constituting the main body portion (e.g., sulfur) and the constituent elements of the conductive material constituting the conductive portion are present in an overlapping manner on the surface and inside of the active material. It should be noted that the composite formation of the main body portion and the conductive portion can be confirmed by, for example, the presence or absence of C-S bonds based on Raman spectroscopy or photoelectron spectroscopy (when the conductive material is a carbon material).

[0051] The active material of the present invention smoothly carries out the supply and demand of electrons between the outside of the active material and the main body with the help of the conductive part, and obtains the desorption and storage function of lithium ions while obtaining conductivity. Furthermore, by utilizing a compound with a argyrodite-type crystal structure that has a high lithium content and high lithium ion conductivity in the main body, the battery having the active material of the present invention will show high capacity and high rate characteristics. In particular, the active material of the present invention is useful as a positive electrode active material for lithium-ion batteries. In contrast, the previously known sulfur-based positive electrode active materials such as elemental sulfur, lithium sulfide (Li2S) and its composite materials, or metal sulfides do not show conductivity or lack conductivity. Therefore, when these materials are used as active materials, there is a problem that the desired battery performance cannot be obtained.

[0052] Regarding the active material of the present invention, in the X-ray diffraction pattern measured using CuKα1 rays, the half-value width of the peak at the position of 2θ=29.62±1.0° is, for example, preferably 0.4° or more, more preferably 0.5° or more, and even more preferably 0.6° or more. It should be noted that the aforementioned half-value width is usually 3.0° or less. In the present invention, in the manufacturing method described later, the aforementioned half-value width can be achieved by performing a second step under prescribed conditions to composite the main body and the conductive part. This is obvious from the results of the embodiments and comparative examples described later. In other words, the half-value width of the peak at the position of 2θ=29.62±1.0° becomes an indicator of the degree of compositeness of the main body and the conductive part in the active material of the present invention.

[0053] In the active material of the present invention, the amount of the conductive material per 100 parts by mass of the particles of the compound constituting the main body is, for example, preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 5 parts by mass or more. On the other hand, the amount of the conductive material per 100 parts by mass of the particles of the compound constituting the main body is, for example, preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. By having the main body and the conductive portion within this range, batteries comprising the active material of the present invention exhibit significantly high capacity and high rate characteristics.

[0054] In the active material of the present invention, the lithium content of the compound is preferably, for example, 10% by mass or more, more preferably 12% by mass or more, and even more preferably 15% by mass or more. On the other hand, the lithium content is preferably, for example, 25% by mass or less, more preferably 23% by mass or less, and even more preferably 21% by mass or less. By setting the lithium content within this range, the capacity of the battery containing the active material of the present invention can be further increased.

[0055] In the active material of the present invention, the lithium ion conductivity of the compound constituting the main body of the active material is preferably, for example, 1×10 -5 S / cm or more, more preferably 1×10 -4 S / cm or more, more preferably 1×10 -3 By increasing the electrical conductivity of the compound constituting the main body, the rate characteristics of the battery having the active material of the present invention can be further improved.

[0056] Next, we will describe a suitable method for producing the active material of the present invention. This method primarily consists of a first step of preparing particles of the compound that constitutes the main body, and a second step of mixing these particles with a conductive material to form a composite. Each step is described below.

[0057] In the first step, particles of a compound containing the aforementioned elements and having a crystalline phase having an argyrodite-type crystal structure are prepared. This compound can be produced using known methods. When the compound contains, for example, lithium (Li), phosphorus (P), sulfur (S), chlorine (Cl), and bromine (Br), particles of the compound are obtained by mixing and calcining lithium sulfide (Li2S) powder, phosphorus pentasulfide (P2S5) powder, lithium chloride (LiCl) powder, and lithium bromide (LiBr) powder. These powders are preferably mixed using, for example, a ball mill, bead mill, or homogenizer.

[0058] After mixing as described above, the mixture is dried as needed, and then the mixed powder is calcined in an inert atmosphere or under the flow of hydrogen sulfide gas (H2S), and crushed, pulverized, and classified as needed to obtain the above-mentioned compound.

[0059] The firing temperature in an atmosphere containing hydrogen sulfide gas is preferably 350° C. or higher, more preferably 450° C. or higher. On the other hand, the firing temperature is preferably 650° C. or lower, more preferably 600° C. or lower, and even more preferably 500° C. or lower.

[0060] On the other hand, the firing temperature when firing in an inert atmosphere is preferably, for example, 350° C. or higher. On the other hand, the firing temperature is preferably, for example, 550° C. or lower, more preferably 500° C. or lower, and even more preferably 450° C. or lower.

[0061] The particles of the compound constituting the main body can also be made by making the raw material powder amorphous by mechanical grinding, and heat-treating the amorphous raw material powder as needed to crystallize it. In this case, as long as the raw material powder can be fully mixed and amorphized, there is no particular limitation on the processing device and processing conditions. In particular, if a planetary ball mill is used, the container filled with the raw material powder rotates and revolves at high speed, and therefore, high impact energy is generated between the pulverizing media, i.e., the balls, which are put into the container together with the raw material powder, and the raw material powder can be effectively and uniformly amorphized. The mechanical grinding method can be either dry or wet.

[0062] The processing conditions for mechanical milling can be appropriately set depending on the processing equipment used. For example, by performing the process for a period of 0.1 to 100 hours, the raw material powder can be more efficiently and uniformly amorphized. The balls used as the grinding medium are preferably made of ZrO2, Al2O3, Si3N4 (silicon nitride), or WC (tungsten carbide), and the ball diameter is preferably between 0.2 mm and 10 mm.

[0063] The aforementioned compound can be obtained by heat-treating the raw material powder rendered amorphous by mechanical milling under the same firing conditions as above to crystallize it. The raw material powder subjected to mechanical milling is more uniformly mixed than raw material powder obtained by conventional pulverization and mixing, thus enabling the heat treatment temperature to be further lowered.

[0064] Alternatively, particles of the compound constituting the main body can be produced by a liquid phase method using an organic solvent. In this case, the particles can be obtained by dissolving the sulfide or halide that forms the raw material for the compound constituting the main body in a solvent such as tetrahydrofuran or ethanol, and precipitating the compound using the solvent as a reaction field. Alternatively, the compound constituting the main body can be synthesized in advance using another method, dissolved in a solvent such as ethanol, and then precipitated, thereby obtaining the compound. This liquid phase method can produce particles of the compound constituting the main body in a shorter time and with less energy than other methods, and it is also relatively easy to reduce the particle size of the particles.

[0065] After obtaining the bulk composed of compound particles in this manner, the bulk is preferably adjusted to an appropriate particle size. The preferred particle size of the bulk can be the same as that described above, and therefore, description thereof is omitted here.

[0066] Next, the main body is mixed with a conductive material to form a composite. The conductive material used can be the same as that described above, so its description is omitted here.

[0067] The composite formation of the main body and the conductive material is achieved by, for example, applying mechanical energy to the particles of the compound and the conductive material constituting the main body. For this purpose, preferably, a compressive / impact force, or a shearing / frictional force is applied to the main body and the conductive material while they are mixed.

[0068] For imparting mechanical energy such as compression / impact force, shearing / friction force to the main body and the conductive material in a mixed state and performing composite formation, it is preferred to adopt a device used when mainly stirring, mixing, kneading, granulating, crushing, dispersing and / or surface modifying the powder. For example, a planetary ball mill, a ball mill, a jet mill, a bead mill, a stirring type crusher, a vibration mill, a hammer mill, a roller mill and an atomizer can be used. The main type of mechanical energy that can be imparted using these devices varies depending on the device. For example, when a planetary ball mill is used, compression / impact force is mainly applied to the main body and the conductive material in a mixed state, thereby enabling the two to be composited. The centrifugal acceleration obtained when the device rotates is not particularly limited as long as it is a degree that enables the main body and the conductive portion to be composited. For example, it is preferably more than 10G, more preferably more than 15G, and more preferably more than 18G. In addition, the above-mentioned centrifugal acceleration is, for example, preferably less than 40G, more preferably less than 30G, and more preferably less than 25G. By setting the centrifugal acceleration within the above range, the effects of the present invention can be more pronounced.

[0069] Alternatively, the aforementioned liquid phase method can be used to composite the main body with the conductive material. In this case, the conductive material is pre-dispersed in an organic solvent, and then the raw materials for the compound particles constituting the main body and the compound constituting the main body are introduced into the organic solvent, causing the particles to precipitate on the surface and inside the conductive material, thereby enabling composite formation. Composite formation based on this method can further reduce the particle size of the composited particles.

[0070] The active material of the present invention can be prepared into an electrode mixture by mixing it with an electrolyte, a conductive material, a binder, etc. When the active material of the present invention is used as a positive electrode active material, the electrode mixture becomes a positive electrode mixture constituting a positive electrode layer.

[0071] The electrolyte may be, for example, a solid electrolyte. The solid electrolyte preferably has ionic conductivity such as lithium ion conductivity. Specifically, examples include inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and halide solid electrolytes; and organic polymer electrolytes such as polymer electrolytes. From the perspective of achieving a more significant effect of the present invention, the solid electrolyte is preferably a sulfide solid electrolyte. The sulfide solid electrolyte may be the same as the sulfide solid electrolyte used in general solid-state batteries. The sulfide solid electrolyte may, for example, contain Li and S and have lithium ion conductivity.

[0072] The sulfide solid electrolyte can be any of a crystalline material, glass ceramics, and glass. The sulfide solid electrolyte can have an argyrodite-type crystal structure. Examples of such sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiX ("X" represents one or more halogen elements), Li2S-P2S5-P2O5, Li2S-Li3PO4-P2S5, Li3PS4, Li4P2S6, Li 10 GeP2S 12 、Li 3.25 Ge 0.25 P 0.75 S4、Li7P3S 11 、Li 3.25 P 0.95 S4, Li a PS b X c ("X" represents one or more halogen elements. a represents a number from 3.0 to 9.0. b represents a number from 3.5 to 6.0. c represents a number from 0.1 to 3.0.) In addition, examples include the sulfide solid electrolytes described in International Publication No. 2013 / 099834 and International Publication No. 2015 / 001818.

[0073] The active material contained in the electrode mixture can be only the active material of the present invention, or it can be used in combination with other active materials. As other active materials, known sulfur elements and active materials containing sulfur can be listed. The ratio of the active material of the present invention in the electrode mixture can be, for example, more than 20 mass %, more than 30 mass %, or more than 40 mass %. On the other hand, the above ratio can be, for example, less than 70 mass %, or less than 60 mass %.

[0074] The battery of the present invention preferably comprises a positive electrode layer containing a positive electrode active material, a negative electrode layer containing a negative electrode active material, and a solid electrolyte layer containing a solid electrolyte, wherein the positive electrode active material is the active material described above. The battery can be manufactured by, for example, stacking the three layers of the positive electrode layer, solid electrolyte layer, and negative electrode layer manufactured as described above and performing pressure molding.

[0075] In order to achieve the desired effect more significantly, the battery of the present invention preferably has an interface where the positive electrode active material and the solid electrolyte are in contact. Here, "the positive electrode active material and the solid electrolyte are in contact" refers to any of the following situations: the positive electrode active material contained in the positive electrode layer is in contact with the solid electrolyte; the positive electrode active material contained in the positive electrode layer is in contact with the solid electrolyte contained in the solid electrolyte layer.

[0076] The battery having the active material of the present invention is preferably a lithium-ion battery, and preferably a lithium-sulfur battery. As the battery herein, a solid-state battery having a solid electrolyte layer, in particular an all-solid-state battery, can be cited. In addition, the battery in the present invention can be a primary battery or a secondary battery, and is preferably used in a secondary battery, and is particularly preferably used in a lithium secondary battery. "Lithium secondary battery" broadly includes the meaning of a secondary battery that is charged and discharged by the movement of lithium ions between a positive electrode and a negative electrode.

[0077] A solid-state battery comprises a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive and negative electrode layers. The active material of the present invention is preferably contained in the positive electrode layer. "Solid-state battery" refers to a battery that contains no liquid or gel-like electrolyte, and also includes, for example, a battery that contains less than 50% by mass, less than 30% by mass, or less than 10% by mass of a liquid or gel-like electrolyte.

[0078] Example

[0079] The present invention will be described in more detail below by way of examples. However, the scope of the present invention is not limited to these examples. Unless otherwise specified, "%" and "parts" refer to "mass %" and "mass parts" respectively.

[0080] [Example 1]

[0081] To become Li shown in Table 1 5.8 PS 4.8 Cl 1.2 In order to prepare a composition of the present invention, lithium sulfide (Li2S) powder, phosphorus pentasulfide (P2S5) powder and lithium chloride (LiCl) powder were weighed in such a way that the total amount became 2 g, and mixed / crushed at 150 revolutions for 20 hours using a planetary ball mill (manufactured by FRITSCH, P-7) to prepare a mixed powder. The mixed powder was filled into a carbon container, and the mixture was heated at a temperature rise and fall rate of 200°C / h in a tubular electric furnace while hydrogen sulfide gas (H2S, purity of 100%) was circulated at 1.0 L / min, and sintered at 500°C for 4 hours. Thereafter, the sample was crushed with a mortar, crushed with a ball mill, and sized using a sieve with a mesh of 53 μm to obtain a particle size D 50 The powdery compound was 3.8 μm in diameter. X-ray diffraction (hereinafter also referred to as “XRD”) analysis confirmed that the compound had a crystalline phase having an argyrodite-type crystal structure.

[0082] As the conductive material, conductive carbon black, namely Ketjen Black (registered trademark) EC300 manufactured by Lion Specialty Chemicals Co., Ltd. was used. The particle size D 500.04 μm. Relative to 100 parts of the above compound, 20 parts of the conductive material were used and mixed / compounded using a planetary ball mill (manufactured by Fritsch, P-7) at 500 rpm for 10 hours. Thereafter, the sample was crushed with a mortar and sized with a sieve having a mesh size of 53 μm to obtain a particle size D 50 The particles of the positive electrode active material are 3.2 μm.

[0083] All the above operations were performed in a glove box in which the atmosphere was replaced with sufficiently dried Ar gas (dew point -60°C or lower).

[0084] [Examples 2 to 4]

[0085] To become Li shown in Table 1 6.8 PS 5.8 Cl 0.2 、Li 5.4 PS 4.4 Cl 0.8 Br 0.8 He Li 5.8 PS 4.8 Cl 1.2 The raw material powders were mixed in the same manner as in Example 1, except that the raw material powders were mixed in the manner of the composition. A powder of the compound was obtained. XRD analysis confirmed that the obtained compound had a crystalline phase with an argyrodite-type crystal structure. Carbon nanotubes (VGCF (registered trademark)-H manufactured by Showa Denko K.K.) or Ketjen Black, as in Example 1, were used as the conductive material. The carbon nanotubes had a fiber diameter of 150 nm and a fiber length of 6 μm.

[0086] In addition, in Example 4, except having used 10 parts of Ketjen Black with respect to 100 parts of the compound, the same operation as in Example 1 was carried out to obtain particles of the active material.

[0087] [Examples 5 and 6]

[0088] To become Li7PS6 and Li as shown in Table 1 7.3 P 0.9 Fe 0.1In order to prepare the composition of S6, the raw material powders were weighed to a total of 2 g and mechanically ground using a planetary ball mill (Fritsch, P-7) at 500 rpm for 20 hours to produce an amorphized mixed powder. The amorphized mixed powder was then placed in a carbon container and heated in a tubular electric furnace at a temperature ramp rate of 200°C / h while flowing an inert gas (Ar, 100% purity) at 1.0 L / min, calcining at 400°C for 4 hours. The sample was then crushed in a mortar and sized using a 53 μm sieve to obtain a powdered compound having the particle size shown in Table 1. XRD analysis confirmed that the compound had a crystalline phase with an argyrodite-type crystal structure. The same procedures as in Example 2 were followed to obtain active material particles.

[0089] [Comparative Example 1]

[0090] This comparative example is an example in which a conductive material composed of Ketjen Black is compounded on the surface and inside of particles of elemental sulfur to produce particles of an active material.

[0091] Relative to particle size D 50 100 parts of sulfur particles with a particle size of 35.6 μm, using particle size D 50 20 parts of Ketjen black with a particle size of 0.04 μm were mixed and compounded in the same manner as in Example 1 using a planetary ball mill (Fritsch, P-7) at 500 rpm for 10 hours. 50 The particles of active substance are 28.4 μm.

[0092] [Comparative Example 2]

[0093] This comparative example is an example in which a conductive material composed of carbon nanotubes is compounded on the surface and inside of lithium sulfide particles to produce particles of an active material.

[0094] Relative to particle size D 50 100 parts of lithium sulfide particles with a particle size of 20 μm, using a particle size D 50 20 parts of carbon nanotubes with a diameter of 0.15 μm were mixed and compounded in the same manner as in Example 1 using a planetary ball mill (Fritsch, P-7) at 500 rpm for 10 hours. 50 The particles of active substance are 17.4 μm.

[0095] [Comparative Example 3]

[0096] In this comparative example, the conductive material composed of Ketjen Black was not compounded with the Li used in Example 1. 5.8 PS 4.8 Cl1.2 An example of a particle in which an active substance is produced by the surface or interior of the particle.

[0097] Relative to particle size D 50 3.8μm Li 5.8 PS 4.8 Cl 1.2 100 parts of the particles and 20 parts of Ketjen black were mixed in the same manner as in Example 1 using a planetary ball mill (Fritsch, P-7) at 200 rpm for 10 hours. 50 The active material particles are 3.6 μm.

[0098] [Comparative Example 4]

[0099] This comparative example is similar to Comparative Example 3, but does not incorporate the conductive material composed of Ketjen black into the Li 5.8 PS 4.8 Cl 1.2 An example of a particle in which an active substance is produced by the surface or interior of the particle.

[0100] Relative to particle size D 50 3.8μm Li 5.8 PS 4.8 Cl 1.2 100 parts of the particles and 20 parts of Ketjen black were mixed in the same manner as in Example 1 using a planetary ball mill (Fritsch, P-7) at 300 rpm for 1 hour. 50 The active material particles are 3.3 μm.

[0101] [Comparative Example 5]

[0102] This comparative example is an example of using only the particles of Li7PS6 used in Example 5 to form an active material without forming a composite with a conductive material.

[0103] 〔Determination of elemental composition〕

[0104] The powders of the main body compounds obtained in the Examples and Comparative Examples were completely dissolved and their elemental compositions were determined using ICP emission spectrometry. The results confirmed that the composition ratios were generally consistent with those of the raw material compounds used. The lithium content of the active materials obtained in the Examples and Comparative Examples was also determined using the same method.

[0105] 〔Identification of generated phase〕

[0106] The powders of the compounds serving as the main body obtained in Examples and Comparative Examples were analyzed by X-ray diffraction (XRD) to identify the generated phases.

[0107] [XRD measurement]

[0108] In a glove box purged with thoroughly dried Ar gas (dew point below -60°C), the positive electrode active material powders obtained in the Examples and Comparative Examples were placed in an airtight holder not exposed to the atmosphere and subjected to XRD analysis. The generated phases were identified by XRD analysis, and the half-value width of the peak at 2θ = 29.62° ± 1.0° (hereinafter sometimes referred to as "Peak A") of the argyrodite-type crystalline phase was calculated. The XRD measurement conditions are as follows.

[0109] Device name: Fully automatic multifunctional X-ray diffraction device SmartLab SE (manufactured by Rigaku Corporation)

[0110] Radiation source: CuKα1

[0111] Tube voltage: 40kV

[0112] Tube current: 50mA

[0113] ·Measurement method: Concentration method (reflection method)

[0114] Optical system: Multilayer mirror divergent beam method (CBO-α)

[0115] Detector: One-dimensional semiconductor detector

[0116] ·Incident Soller gap: Soller gap 2.5°

[0117] Length limit slit: 10mm

[0118] Soller gap: 2.5°

[0119] Entrance slit: 1 / 6°

[0120] Light receiving slit: 2mm (open)

[0121] Measurement range: 2θ = 10 to 120°

[0122] Step width: 0.02°

[0123] Scanning speed: 1.0° / min

[0124] 〔Particle size D 50 〕

[0125] Regarding the powder of the compound as the main body obtained in the examples and comparative examples or the positive electrode active material powder, a laser diffraction particle size distribution measuring apparatus was used with an automatic sample feeder ("Microtorac SDC" manufactured by MICROTRAC-BEL) to place the sample (powder) into a water-soluble solvent. After irradiating the sample with 40W ultrasonic waves for 360 seconds at a flow rate of 40%, the particle size distribution was measured using a laser diffraction particle size distribution measuring apparatus "MT3000II" manufactured by MICROTRAC-BEL. The particle size distribution was measured based on the obtained volume-based particle size distribution spectrum. 50 .

[0126] 〔Ionic conductivity〕

[0127] In a glove box purged with thoroughly dried Ar gas (dew point below -60°C), the powders of the compounds used as the main components in the examples and comparative examples were uniaxially pressed and then compressed at 200 MPa using a CIP (cold isostatic pressing) to produce pellets with a diameter of 10 mm and a thickness of approximately 4 to 5 mm. Furthermore, after applying carbon paste as electrodes to both the upper and lower surfaces of the pellets, they were heat-treated at 180°C for 30 minutes to produce samples for ionic conductivity measurement. The ionic conductivity (S / cm) was measured using an AC impedance method at room temperature (25°C) using a Solartron 1255B device manufactured by TOYO Corporation and a measurement frequency of 0.1 Hz to 1 MHz.

[0128] 〔Observation and elemental mapping of active material particles〕

[0129] The positive electrode active material powders obtained in the examples and comparative examples were observed using a scanning electron microscope equipped with an energy dispersive X-ray spectrometer (SEM-EDS). The constituent elements of the compound serving as the main body, namely sulfur, and the constituent elements of the conductive material were mapped. The presence of sulfur and the constituent elements of the conductive material in the compound was measured to confirm the state of the composite.

[0130] In addition, after using the active materials obtained in the examples and comparative examples to make the batteries described below, the cross-section of the positive electrode layer of the battery is observed in the same manner as described above, and the presence of sulfur elements in the compound and the constituent elements of the conductive material are measured on the surface and inside of the active material, thereby confirming the composite state in the battery state.

[0131] Battery Evaluation

[0132] Solid-state batteries were fabricated using the active materials obtained in the Examples and Comparative Examples as the positive electrode active material according to the following procedures. The initial capacity and rate characteristics of these fabricated solid-state batteries were evaluated according to the following procedures. The results are shown in Tables 1 and 2 below.

[0133] <Fabrication of All-Solid-State Battery Cells>

[0134] As the positive electrode active material, the positive electrode active material prepared in the examples and comparative examples was used, and as the solid electrolyte powder used in the positive electrode layer and the solid electrolyte layer, Lithium argyrodite-type crystal structure was used. 5.4 PS 4.4 Cl 0.8 Br 0.8 , In-Li alloy is used as the negative electrode active material of the negative electrode layer to make an all-solid-state battery.

[0135] (Preparation of Positive Electrode Mixture)

[0136] The positive electrode mixture powder for the positive electrode layer was prepared by mortar-mixing the positive electrode active material powders obtained in the Examples and Comparative Examples with the solid electrolyte powders at a mass ratio of 60:40. Note that Comparative Example 4, in which the positive electrode active material powder was not composited with a conductive material, was prepared by mortar-mixing the positive electrode active material powder, solid electrolyte powder, and the aforementioned carbon nanotubes, which serve as the conductive material for imparting conductivity to the positive electrode layer, at a mass ratio of 50:40:10.

[0137] (Fabrication of all-solid-state battery cells)

[0138] The lower opening of a polypropylene cylinder (with an opening diameter of 10.5 mm and a height of 18 mm) with upper and lower openings is blocked with a negative electrode (made of SUS), solid electrolyte powder is placed on it, and after blocking with a positive electrode (made of SUS), uniaxial pressure is applied at 200 MPa to form a solid electrolyte layer. Next, the positive electrode is temporarily removed, and positive electrode mixture powder is placed on the solid electrolyte layer. After blocking with the positive electrode again, uniaxial pressure is applied at 560 MPa to stack the positive electrode layer and the solid electrolyte layer. Thereafter, the cylinder is turned upside down, the negative electrode is temporarily removed, In-Li foil is placed on the solid electrolyte layer, and blocked with the negative electrode again. Finally, a vise is used to clamp the positive and negative electrodes with a load of 6 N·m, thereby making an all-solid-state battery cell stacked with a positive electrode layer, a solid electrolyte layer, and a negative electrode layer. It should be noted that the thickness of each layer is about 40 μm for the positive electrode layer, about 600 μm for the solid electrolyte layer, and about 400 μm for the negative electrode layer. The production of the all-solid-state battery cell is carried out in a glove box purged with argon gas at a dew point temperature of -60°C. The produced all-solid-state battery is connected to a charge and discharge measuring device in an environmental testing machine maintained at 25°C to evaluate the battery characteristics. It should be noted that the current of 2.0 mA during charge and discharge is set as 1C rate.

[0139] [Initial capacity]

[0140] In the initial charge and discharge (first cycle), in order to effectively desorb and store lithium ions contained in the positive electrode active material, the battery was charged to 3.0 V at 0.03 C using the CC-CV method, and discharged to 0.38 V using the CC method at 0.03 C. In the second cycle, the battery was charged to 3.0 V at 0.1 C using the CC-CV method, and discharged to 0.38 V using the CC method at 0.1 C. Here, the charge and discharge capacity of the second cycle is set as the initial charge and discharge capacity. It should be noted that in the active material in which elemental sulfur and a conductive material are composited, no lithium element is contained in the active material, and therefore, the first cycle starts with discharge.

[0141] [Rate characteristics]

[0142] The third cycle of charge and discharge was performed using the above method. In the fourth cycle and thereafter, charge and discharge were performed at rates of 0.2C, 0.5C, 1C, 2C, and 5C. The discharge capacity at each rate was compared with the discharge capacity in the second cycle (0.1C) to evaluate the rate characteristics.

[0143] [Table 1]

[0144]

[0145] [Table 2]

[0146]

[0147] The results shown in Tables 1 and 2 clearly demonstrate that all-solid-state batteries using the active materials of each example as the positive electrode active material exhibit superior initial capacity and rate characteristics compared to the comparative example. In particular, a comparison of Examples 1 and 3, in which the conductive portion includes Ketjen black, with Examples 2, 3, 5, and 6, in which the conductive portion includes carbon nanotubes, clearly demonstrates that the batteries of Examples 1 and 3 exhibit superior discharge rate characteristics. In other words, it is clear that the inclusion of Ketjen black in the conductive portion improves the discharge rate characteristics of the battery.

[0148] Comparative Example 1, which uses elemental sulfur as the main body, exhibits high initial capacity but poor rate performance. The inventors speculate that this is because the lithium ion conductivity of elemental sulfur is so low that it cannot be measured. Therefore, even when the discharge current is increased and the rate is raised, lithium ions cannot be rapidly absorbed into the elemental sulfur.

[0149] Element mapping using SEM-EDS confirmed that sulfur and carbon elements existed in an overlapping manner on the surface and inside of the active material obtained in each example.

[0150] Figure 1 、 2 , 3 and 10 respectively represent the charge-discharge curves when the charge-discharge rate is changed to 0.1C, 0.2C, 0.5C, 1C, 2C and 5C in the all-solid-state batteries obtained using the positive electrode active materials prepared in Example 1, Example 5, Comparative Example 3 and Comparative Example 10. In the all-solid-state batteries obtained using the positive electrode active materials prepared in Examples 1 and 5, a high discharge capacity is shown even when the charge-discharge rate is increased, but in the all-solid-state batteries obtained using the positive electrode active materials prepared in Comparative Examples 3 and 4, the discharge capacity is significantly reduced when the charge-discharge rate is increased. In particular, although the powder of the compound having the same composition as that of Example 1 is used in the main body of Comparative Examples 3 and 4, the initial capacity and discharge rate characteristics are still significantly inferior to those of Example 1. The inventors speculate that this is because the particle size of the compound powder used in Comparative Example 3 is large and the conditions of the planetary ball mill used during the composite treatment, i.e., the rotation speed, are low. Therefore, the conductive material is not evenly dispersed on the surface and inside of the compound particles, and the performance as a positive electrode active material cannot be exhibited.

[0151] Figure 4 and Figure 5It is an SEM image obtained by observing the appearance of the positive electrode active material powder prepared in Example 5 and Comparative Example 4, and a figure obtained by sputtering the existence state of carbon element and sulfur element by EDS. It should be noted that the composition of the compound used in Example 5 and Comparative Example 4 is the same. Since the carbon element as the conductive material component and the sulfur element as the compound component of the positive electrode active material powder prepared in Example 5 exist in an overlapping manner, it can be confirmed that the particles of the compound and the conductive material are uniformly composited. On the other hand, in the positive electrode active material powder prepared in Comparative Example 4, the carbon element as the conductive material component and the sulfur element of the compound exist in different positions. Therefore, it can be confirmed that the compound particles of the positive electrode active material prepared in Comparative Example 4 are not composited with the conductive material, but are simply mixed.

[0152] Figure 6 and Figure 7 The results are obtained by processing the positive electrode active material powder prepared in Example 5 and Comparative Example 4 by cross-section polishing (CP) to expose the cross section, and mapping the presence of carbon, sulfur, and bromine by SEM observation and EDS. In the cross section of the all-solid-state battery obtained using the positive electrode active material powder prepared in Example 5, the carbon element as a conductive material component is located in the area where the bromine element as a solid electrolyte component is not present and is located in the area where the sulfur element is present in large amounts. Therefore, it can be confirmed that the conductive material is uniformly compounded on the surface and inside of the particles of the compound. On the other hand, in the cross section of the all-solid-state battery obtained using the positive electrode active material powder prepared in Comparative Example 4, the carbon element as a conductive material component is present in the area where the bromine element as a compound component is present and is present around the area where the sulfur element is present in large amounts. Therefore, it can be confirmed that the conductive material is not compounded with the particles of the compound, and that the powder of the compound and the powder of the conductive material are simply mixed.

[0153] Figure 8 This is the XRD pattern of the positive electrode active material powder prepared in Examples 1, 3 and 4. In Examples 1, 3 and 4, when the main body and the conductive part in a mixed state were composited using a planetary ball mill, high centrifugal acceleration was applied under high rotation speed conditions, thereby imparting high mechanical energy to the main body and the conductive part, causing the two to composite. Figure 8 The XRD diffraction pattern shown and the half-value width shown in Table 3 below confirm that, during the composite formation, the half-value width of each diffraction peak belonging to the argyrodite-type crystal phase is broadened by maintaining the argyrodite-type crystal phase and moderately low crystallization of the crystal phase.

[0154] Figure 9This is the XRD pattern of the positive electrode active material powder prepared in Comparative Examples 3 and 4. In Comparative Examples 3 and 4, when the main body and the conductive part in a mixed state were composited using a planetary ball mill, the centrifugal acceleration applied was insufficient due to the low rotation speed condition. Therefore, high mechanical energy was not applied to the main body and the conductive part, and the two were not fully composited. In addition, according to Figure 9 The XRD diffraction pattern shown and the half-value width shown in Table 3 below confirm that the argyrodite-type crystal phase contained in the main body maintains a high crystallinity state.

[0155] [Table 3]

[0156]

[0157] Industrial applicability

[0158] In summary, the active material according to the present invention can improve the performance of lithium-ion batteries.

Claims

1. A method for producing an active substance, comprising the following steps: In the first step, a compound containing lithium (Li), sulfur (S), and M and having a crystalline phase having an argyrodite-type crystal structure is prepared, wherein: M is at least one of phosphorus (P), germanium (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co), and manganese (Mn); as well as In the second step, the compound is mixed with a conductive material to form a composite. In the second step, mechanical energy is applied to the compound and the conductive material so that the centrifugal acceleration is 15G or more. The second step is performed so that the half-value width of the peak at the position of 2θ=29.62±1.0° in the X-ray diffraction pattern measured using CuKα1 radiation becomes 0.5° or more. The main body containing the compound and the conductive material are particles, and the volume cumulative particle size D when the cumulative volume of the main body is 50% by volume based on the laser diffraction scattering particle size distribution measurement method is 0. 50 When D1 is used, and D2 is used as the average particle size of the conductive material measured by directly observing the conductive material dispersed in the main body using a scanning electron microscope or a transmission electron microscope, D1 / D2 is 10 or more and 100 or less, D1 is 0.5 μm or more and 20 μm or less, D2 is 20 nm or more and 200 nm or less, When the active material is observed using a scanning electron microscope SEM-EDS equipped with an energy dispersive X-ray spectrometer and the constituent elements of the compound constituting the main body and the constituent elements of the conductive material constituting the conductive part are mapped, it can be confirmed that the constituent elements of the compound constituting the main body and the constituent elements of the conductive material constituting the conductive part exist in an overlapping manner.

2. The manufacturing method according to claim 1, wherein In the second step, the mechanical energy is applied using a planetary ball mill, and the conductive material and the compound are composited in a state where they are inseparably bonded and dispersed on the surface and inside of the compound.

3. The manufacturing method according to claim 1 or 2, wherein: In the second step, 1 part by mass or more and 50 parts by mass or less of the conductive material are mixed with 100 parts by mass of the compound.

4. The manufacturing method according to claim 1 or 2, wherein: The compound further contains a halogen (X) element.

5. The manufacturing method according to claim 4, wherein: The compound is composed of the formula Li a MS b X c express, In the formula, M is at least one element selected from phosphorus (P), germanium (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co) and manganese (Mn); X is at least one element selected from fluorine (F), chlorine (Cl), bromine (Br) and iodine (I); a is greater than or equal to 3.0 and less than or equal to 9.0; b is greater than or equal to 3.5 and less than or equal to 6.0; and c is greater than or equal to 0.10 and less than or equal to 3.

0.

6. The manufacturing method according to claim 1 or 2, wherein: The conductive material is carbon black.

7. The manufacturing method according to claim 6, wherein: The conductive material is Ketjen Black.

8. An active material comprising a compound and a conductive material, which is a composite material of the compound and the conductive material. The compound contains lithium (Li) element, sulfur (S) element and M element and includes a crystalline phase having an argyrodite-type crystal structure, wherein: M is at least one of phosphorus (P), germanium (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co), and manganese (Mn), The half-value width of the peak at the position of 2θ=29.62±1.0° in the X-ray diffraction pattern measured using CuKα1 radiation is 0.5° or more. The main body containing the compound and the conductive material are particles, and the volume cumulative particle size D when the cumulative volume of the main body is 50% by volume based on the laser diffraction scattering particle size distribution measurement method is 0. 50 When D1 is used, and D2 is used as the average particle size of the conductive material measured by directly observing the conductive material dispersed in the main body using a scanning electron microscope or a transmission electron microscope, D1 / D2 is 10 or more and 100 or less, D1 is 0.5 μm or more and 20 μm or less, D2 is 20 nm or more and 200 nm or less, When the active material is observed using a scanning electron microscope SEM-EDS equipped with an energy dispersive X-ray spectrometer and the constituent elements of the compound constituting the main body and the constituent elements of the conductive material constituting the conductive part are mapped, it can be confirmed that the constituent elements of the compound constituting the main body and the constituent elements of the conductive material constituting the conductive part exist in an overlapping manner.

9. The active material according to claim 8, wherein The conductive material is dispersed in the compound in an inseparably dispersed manner.

10. The active material according to claim 8 or 9, wherein The conductive material is contained in an amount of 1 part by mass or more and 50 parts by mass or less relative to 100 parts by mass of the compound.

11. The active material according to claim 8 or 9, wherein The conductive material is a carbon material or a metal material.

12. The active material according to claim 11, wherein The conductive material is carbon black.

13. The active material according to claim 12, wherein The conductive material is Ketjen Black.

14. The active material according to claim 8 or 9, wherein A content of the lithium element in the compound is 10% by mass or more and 25% by mass or less.

15. The active substance according to claim 8 or 9, wherein The compound further contains a halogen (X) element. 16 . An electrode mixture comprising the active material according to claim 8 and a sulfide solid electrolyte.

17. A battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer. The positive electrode layer contains the active material according to any one of claims 8 to 15.

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