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

Abstract

An active material according to the present invention comprises: a compound which contains elemental lithium (Li), elemental sulfur (S) and an M element, while comprising a crystal phase that has an argyrodite crystal structure; and a conductive material which is dispersed in particles of the compound and on the surfaces of the particles. The M element represents elemental phosphorus (P) or the like. An active material according to the present invention is a composite material of the above-described compound and the above-described conductive material. It is preferable that the conductive material is a carbon material or a metal material. It is also preferable that the content of the elemental lithium in the active material is from 10% by mass to 25% by mass.

Description

Technical Field

[0001] The present invention relates to an active material and a method for producing the same. The present invention also relates to an electrode mixture and a battery containing the active material.

Background Art

[0002] Lithium ion batteries have high energy density and are easy to be reduced in size and weight, so they are widely used as power sources for portable electronic devices such as laptop computers and mobile phones. In recent years, development of high-output, high-capacity lithium ion batteries to be mounted in electric vehicles, hybrid electric vehicles, and the like has been progressing.

[0003] For example, Patent Document 1 proposes a positive electrode active material containing a sulfide solid electrolyte material and a conductive material. Furthermore, Non-Patent Document 1 proposes a positive electrode active material obtained by compositing Li₃PS₄ glass, which is a sulfide solid electrolyte, with a carbon-based conductive aid.

[0004] Meanwhile, the present inventors have repeatedly conducted research on sulfide solid electrolytes used in lithium ion batteries, and have obtained a composition formula Li 7-x PS 6-x Ha (wherein x is 0.2 or more and 1.8 or less, and Ha represents Cl or Br) (see Patent Document 2). This compound has high lithium ion conductivity.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0006]

Non-Patent Document 1

[0007] The inventors conducted studies aimed at improving the performance of lithium-ion batteries. As a result, they found that there is a need for superior cathode active materials to further improve the performance of lithium-ion batteries. The object of the present invention is to provide an active material that can improve the performance of lithium-ion batteries.

[0008] The electrolyte and active material used in batteries play completely different roles. For example, in conventional technology where materials used in sulfide solid electrolytes were repurposed as active material, it was difficult to further improve battery performance such as capacity and rate characteristics. On the other hand, the inventors of the present invention have discovered that by mixing the sulfide solid electrolyte proposed in the above-mentioned Patent Document 2 with a conductive material to form a composite, not only does it function as an active material, but by using it as a positive electrode active material in lithium-ion batteries, it is possible to improve battery performance such as capacity and rate characteristics to a greater extent than before.

[0009] The present invention is based on the above findings and comprises a compound containing 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 having a crystalline phase having an argyrodite type crystal structure, Having a conductive material, The above-mentioned problems are solved by providing an active material which is a composite material of the aforementioned compound and the aforementioned conductive material.

[0010] Furthermore, the present invention provides a suitable method for producing the active material, A first step is to prepare a compound containing lithium (Li) element, sulfur (S) element, and M element (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 containing a crystalline phase having an argyrodite type crystal structure. The process includes a second step of mixing the compound with a conductive material to form a composite. This invention provides a method for producing active materials. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 shows the charge-discharge curve of a battery using the positive electrode active material prepared in Example 1. [Figure 2] Figure 2 shows the charge-discharge curve of the battery using the positive electrode active material prepared in Example 5. [Figure 3] Figure 3 shows the charge-discharge curve of the battery using the positive electrode active material prepared in Comparative Example 3. [Figure 4] Figure 4 shows the SEM-EDS image of the cathode active material prepared in Example 5. [Figure 5] Figure 5 shows the SEM-EDS image of the cathode active material prepared in Comparative Example 4. [Figure 6] Figure 6 shows a cross-sectional SEM-EDS image of the battery using the positive electrode active material prepared in Example 5. [Figure 7] Figure 7 shows a cross-sectional SEM-EDS image of a battery using the positive electrode active material prepared in Comparative Example 4. [Figure 8] Figure 8 shows the X-ray diffraction patterns of the positive electrode active materials prepared in Examples 1, 3, and 4. [Figure 9] Figure 9 shows the X-ray diffraction patterns of the positive electrode active materials prepared in Comparative Examples 3 and 4. [Figure 10] Figure 10 shows the charge-discharge curve of the battery using the positive electrode active material prepared in Comparative Example 4. [Modes for carrying out the invention]

[0012] The present invention will be described below based on preferred embodiments thereof. The present invention relates to an active material for batteries. Currently, lithium-ion batteries are the mainstream of secondary batteries, and further increases in energy density are required for lithium-ion batteries. From this perspective, attention has been focused on solid-state batteries that use sulfide, a material that has fewer restrictions on active materials and can achieve higher energy density, as a solid electrolyte. Furthermore, for the purpose of achieving further higher energy density, active materials with high capacity are required. There is also a demand for active materials having high rate characteristics that can support rapid charging and discharging. The active material of the present invention meets these requirements.

[0013] The active material of the present invention comprises particles of a specific compound and a conductive material compounded with the particles. That is, the active material of the present invention includes particles composed of a main portion containing particles of the specific compound, and a conductive portion dispersed on the surface and / or inside the main portion and containing the conductive material that imparts electron conductivity. These main portion and conductive portion will be described below.

[0014] The main portion is composed of a compound containing a specific element. Specifically, the main portion is preferably composed of a compound containing lithium (Li) element, sulfur (S) element, and element M. Element M is, for example, at least one selected from the group consisting of phosphorus (P), germanium (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co), and manganese (Mn).

[0015] Examples of the compound containing Li element, S element and element M include Li₇PS₆, which is a compound containing only Li element, S element and element M, Li 7+3x (P 5+ 1-x Fe 2+ x )S₆, Li 7+x (P 5+ 1-x Si 4+ xExamples include S6 (where x represents a number between 0.1 and 1.0). Furthermore, as a compound containing Li, S, and M elements, it is also possible to use one that contains other elements in addition to these three elements. Examples of such other elements include halogen (X) elements. Using a compound containing X elements in addition to Li, S, and M elements is preferable because it further enhances the properties of the active material of the present invention. As X elements, at least one selected from F, Cl, Br, and I can be used.

[0016] The compound containing elements Li, S, M and X is defined by the compositional formula (1) Li a MS b X c It is preferable that the material be represented as follows: (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).) This is preferable because it improves ionic conductivity and further enhances the properties of the active material.

[0017] From the viewpoint 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. Also, 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.

[0018] In particular, the element M in the above compositional formula is preferably at least one of phosphorus (P), germanium (Ge), antimony (Sb), tin (Sn), and silicon (Si), and the inclusion of phosphorus (P) is especially preferable as it further enhances the properties of the active material.

[0019] The main compound is, in particular, Li (2) 7-d MS 6-d X d It is preferable that it be expressed as follows, as this further enhances its properties as an active material. In the formula, d is preferably 0.40 or more and 2.2 or less, more preferably 0.80 or more and 2.0 or less, and even more preferably 1.2 or more and 1.8 or less.

[0020] In compositional 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) is Li a (M1 1-y M2 y )S b X c Therefore, equation (2) is Li 7-d (M1 1-y M2 y )S 6-d X d The result is as follows: 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. Note that element M1 is the same as element M described in composition formula (1).

[0021] The composition of each element in the compound constituting the main part can be measured, for example, by ICP emission spectroscopy.

[0022] The compound constituting the main part preferably contains the elements described above, as well as 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 part preferably contains a crystalline phase having a cubic argyrodite-type crystal structure. Whether or not it contains a crystalline phase having an argyrodite-type crystal structure can be determined by analyzing the active material of the present invention by X-ray diffraction. For example, CuKα1 rays can be used as CuKα rays.

[0023] The compound constituting the main part preferably has peaks at positions 2θ = 25.19° ± 1.00° and 29.62° ± 1.00° in the X-ray diffraction pattern measured using CuKα1 rays. These peaks originate from the argyrodite-type crystalline phase.

[0024] The compound constituting the main part, in the X-ray diffraction pattern measured using CuKα1 rays, is found at positions 2θ = 25.19°±1.00° and 29.62°±1.00°, as well as at 1 or 51.70°±1.00° selected from 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°. It is even more preferable to have peaks at two or more positions, and even more preferable to have peaks at all of the following positions in addition to 2θ = 25.19°±1.00° and 29.62°±1.00°: 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 originate from the argyrodite-type crystal phase.

[0025] The peak position mentioned above is expressed as median ± 1.00°, but it is preferable that it be median ± 0.500°, and even more preferable that it be median ± 0.300°.

[0026] The main part contains the compound described above and may contain other materials or other components as needed. Therefore, the main part may consist of a single phase composed of a crystalline phase with an argyrodite-type crystal structure, or it may contain other phases in addition to the said phase. For example, the core may contain a Li2S phase, Li3PS4 phase, Li4P2S6 phase, LiCl or LiBr phase in addition to the crystalline phase with an argyrodite-type crystal structure. In particular, it is preferable for the main part to contain a Li2S phase in addition to the crystalline phase with an argyrodite-type crystal structure because it increases the capacity of the active material. However, it is preferable for the main part to be a compound containing Li, S, M and X elements and a crystalline phase having an argyrodite-type crystal structure as the main material. In addition to the other materials and other components described above, the main part may also contain unavoidable impurities to an extent that does not adversely affect the effects of the present invention, for example, less than 5% by mass, especially less than 3% by mass.

[0027] The main part containing the compound described above has the form of particles, and a conductive part containing the conductive material described above is arranged on the surface or inside the particles. Any material having electronic conductivity can be used as the conductive material without particular limitations. Examples of conductive materials include various metallic materials and conductive nonmetallic materials. Either one of the metallic material or the conductive nonmetallic material may be used, or both may be used in combination. Examples of the metallic material include various noble metal elements, such as gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), and osmium (Os). Examples of transition metal elements include copper (Cu), iron (Fe), and tin (Sn). These metallic elements may be used individually, or two or more may be used in combination. As the conductive nonmetallic material, for example, carbon materials can be used. Examples include graphite, acetylene black, carbon black, carbon nanofibers, carbon nanotubes, nanographene, and fullerene nanowhiskers. These carbon materials may be used individually or in combination of two or more. Of these carbon materials, carbon black is preferred in terms of improving the initial capacity and discharge rate characteristics of the battery. From the viewpoint of making this advantage even more pronounced, it is preferable to use Ketjen black as the carbon black, and among these, furnace black is preferred, and in particular oil furnace black is preferred.

[0028] The conductive parts, including the various conductive materials mentioned above, must be uniformly dispersed and in close contact with the surface and interior, as they play a role as electron conduction paths when lithium is deabsorbed from the main part.

[0029] From the viewpoint of uniformly dispersing the conductive part containing the conductive material on the surface and inside the main part, it is preferable that the size of the conductive material is smaller than the size of the main part. More specifically, when the particle size of the main part is D1 and the particle size of the conductive material is D2, the value of D1 / D2 is preferably 2 or more, more preferably 5 or more, and even more preferably 10 or more. On the other hand, the value of D1 / D2 is preferably 1000 or less, more preferably 500 or less, and even more preferably 10 or more and 100 or less.

[0030] The particle size D1 of the main part is preferably, for example, 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.5 μm or more. On the other hand, 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 part is preferably, for example, 1 nm or more, more preferably 10 nm or more, and even more preferably 20 nm or more. On the other hand, D2 is preferably, for example, 500 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less.

[0031] The particle size of the main part is the cumulative volume particle size D at 50% of the cumulative volume, measured by laser diffraction scattering particle size distribution analysis. 50 (hereinafter referred to as "D") 50 When this is said, it refers to the particle size. On the other hand, the particle size of the conductive part is difficult to measure by laser diffraction scattering particle size distribution measurement when the conductive part is dispersed inside the particles of the main part. Therefore, the average particle size is measured by directly observing the conductive part dispersed inside the main part using SEM (scanning electron microscope) or TEM (transmission electron microscope). Note that, for example, when the conductive material is the carbon nanotube or carbon nanofiber mentioned above, the fiber diameter refers to the diameter in the cross-section of the fiber, or the average value of the major axis and minor axis.

[0032] The active material of the present invention is a composite material comprising a main part and a conductive part, that is, a composite material of compound particles constituting the main part and a conductive material constituting the conductive part. In the "composite" configuration, it is preferable that the conductive part is dispersed on the surface or inside the main part, in close and inseparable contact with the main part. Examples of the "composite" configuration include a configuration in which conductive material particles are inseparably dispersed on the surface and / or inside the compound particles, or a configuration in which the compound particles constituting the main part and the conductive material particles constituting the conductive part are chemically reacted and bonded together. "Conductive material particles are inseparably dispersed on the surface or inside the compound particles constituting the main part" means, for example, that when the active material of the present invention 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 part (e.g., sulfur) are mapped to the constituent elements of the conductive material constituting the conductive part, it can be confirmed that the constituent elements of the compound constituting the main part (e.g., sulfur) and the constituent elements of the conductive material constituting the conductive part overlap. Alternatively, when observing a cross-section of the positive electrode layer of a battery made using the active material of the present invention, it can be confirmed that the constituent elements of the compound constituting the main part (e.g., sulfur) and the constituent elements of the conductive material constituting the conductive part are present on the surface or inside the active material in an overlapping manner. The composite nature of the main part and the conductive part can be confirmed, for example, by the presence or absence of CS bonding using Raman spectroscopy or photoelectron spectroscopy (when the conductive material is a carbon material).

[0033] The active material of the present invention facilitates the smooth transfer of electrons between the outside of the active material and the main part via the conductive portion, thereby acquiring conductivity and lithium ion desorption functionality. Furthermore, by utilizing a compound with a high lithium content and a high lithium ion conductivity argyrodite crystal structure as the main part, a battery using the active material of the present invention exhibits 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, conventionally known sulfur-based positive electrode active materials such as elemental sulfur, lithium sulfide (Li2S) and its composite materials, or metal sulfides either do not exhibit conductivity or have poor conductivity, resulting in the problem that desired battery performance cannot be obtained when these materials are used as active materials.

[0034] In the active material of the present invention, the full width at half maximum (FWHM) of the peak located at 2θ = 29.62 ± 1.0° in the X-ray diffraction pattern measured using CuKα1 rays is preferably 0.4 or more, more preferably 0.5 or more, and even more preferably 0.6 or more. The FWHM is typically 3.0 or less. In the present invention, the main portion and the conductive portion are composited by performing a second step under predetermined conditions in the manufacturing method described later, thereby achieving the aforementioned FWHM. This is evident from the results of the examples and comparative examples described later. In other words, the FWHM of the peak located at 2θ = 29.62 ± 1.0° serves as an indicator of the degree of composite formation between the main portion and the conductive portion in the active material of the present invention.

[0035] In the active material of the present invention, the amount of conductive material per 100 parts by mass of the compound particles constituting the main part is preferably, for example, 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 conductive material per 100 parts by mass of the compound particles constituting the main part is preferably, for example, 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. With the main part and conductive part within this range, a battery equipped with the active material of the present invention will exhibit remarkably high capacity and high rate characteristics.

[0036] In the active material of the present invention, the lithium element content in 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 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 element content within this range, the capacity of a battery having the active material of the present invention can be further increased.

[0037] In the active material of the present invention, the lithium ion conductivity of the compound constituting the main part in the active material is, for example, 1 × 10⁻⁶ -5 Preferably, S / cm or higher, 1 × 10 -4 It is even more preferable that the ratio is 1 × 10⁻⁶ or higher. -3 It is even more preferable that the conductivity is S / cm or higher. By increasing the conductivity of the compound constituting the main part, the rate characteristics of the battery having the active material of the present invention can be further improved.

[0038] Next, a preferred method for producing the active material of the present invention will be described. This production method is broadly divided into two main steps: a first step of preparing particles of the compound constituting the main part, and a second step of mixing the compound particles with a conductive material to composite them. Each step will be described below.

[0039] In the first step, particles of a compound containing the aforementioned elements and a crystalline phase having an argyrodite-type crystal structure are prepared. This compound can be produced by known methods. If the compound contains, for example, lithium (Li), phosphorus (P), sulfur (S), chlorine (Cl), and bromine (Br), particles of the compound are obtained by mixing lithium sulfide (Li2S) powder, phosphorus pentasulfide (P2S5) powder, lithium chloride (LiCl) powder, and lithium bromide (LiBr) powder, and then calcining the mixture. For mixing these powders, it is preferable to use, for example, a ball mill, a bead mill, or a homogenizer.

[0040] After mixing as described above, the mixture can be dried as necessary, then calcined under an inert atmosphere or under a flow of hydrogen sulfide gas (H2S), crushed and pulverized as necessary, and classified to obtain the compound. When firing in an atmosphere containing hydrogen sulfide gas, the firing temperature is preferably, for example, 350°C or higher, and more preferably 450°C or higher. On the other hand, the firing temperature is preferably, for example, 650°C or lower, more preferably 600°C or lower, and even more preferably 500°C or lower. On the other hand, when firing in an inert atmosphere, the firing temperature is preferably, for example, 350°C or higher. On the other hand, the above firing temperature is preferably, for example, 550°C or lower, more preferably 500°C or lower, and even more preferably 450°C or lower.

[0041] The particles of the compound constituting the main component can also be produced by amorphizing the raw material powder using a mechanical milling method, and then heat-treating the amorphized raw material powder to crystallize it as needed. In this case, there are no particular limitations on the processing apparatus and processing conditions, as long as the raw material powder can be sufficiently mixed and amorphized. In particular, when a planetary ball mill is used, the container in which the raw material powder is filled rotates at high speed, generating high impact energy between the raw material powder and the balls, which are the grinding media placed in the container together, making it possible to amorphize the raw material powder efficiently and uniformly. The mechanical milling method can be either dry or wet.

[0042] The processing conditions for the mechanical milling method can be appropriately set according to the processing equipment used. For example, processing for a time of 0.1 hours to 100 hours can more efficiently and uniformly amorphousize the raw material powder. The balls used as the grinding media 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.

[0043] The compound can be obtained by crystallizing the amorphous raw material powder, which has been processed by mechanical milling, under the same firing conditions as described above. Since the raw material powder that has undergone mechanical milling is more uniformly mixed than the raw material powder obtained by ordinary grinding and mixing, it is possible to lower the heat treatment temperature even further.

[0044] Furthermore, particles of the compound constituting the main component can also be produced by a liquid-phase method using an organic solvent. In this case, sulfides or halides, which are the raw materials for the compound constituting the main component, are dissolved in a solvent such as tetrahydrofuran or ethanol, and the compound is precipitated using the solvent as a reaction field. Alternatively, the compound constituting the main component can be synthesized in advance by another method, dissolved in a solvent such as ethanol, and then re-precipitationd to obtain the compound. Such a liquid-phase method makes it possible to produce particles of the compound constituting the main component in a shorter time and with less energy than other methods, and it is also relatively easy to reduce the particle size.

[0045] Once the main part, consisting of compound particles, is obtained in this way, it is preferable to adjust the particle size of this main part to an appropriate size. The preferred particle size of the main part can be the same as described above, so it is omitted here.

[0046] Next, the main component and the conductive material are mixed and compounded. The conductive material used can be the same as described above, so its details are omitted here.

[0047] The composite of the main component and the conductive material is achieved, for example, by applying mechanical energy to the particles of the compound constituting the main component and the particles of the conductive material. For this purpose, it is preferable to apply compressive / impact forces or shear / frictional forces to the main component and the conductive material in their mixed state.

[0048] To compound the main component and conductive material in a mixed state by applying mechanical energy such as compressive / impact force or shear / frictional force, it is preferable to use equipment mainly used for stirring, mixing, kneading, granulating, grinding, dispersing, and / or surface modifying powders. For example, planetary ball mills, ball mills, jet mills, bead mills, agitator-type pulverizers, vibratory mills, hammer mills, roller mills, and atomizers can be used. The main types of mechanical energy that can be applied using these devices differ depending on the device. For example, when using a planetary ball mill, the main component and conductive material in a mixed state can be compounded by mainly applying compressive / impact force to them. The centrifugal acceleration obtained when the device rotates is not particularly limited as long as it is sufficient to compound the main component and conductive material, but for example, it is preferably 10G or more, more preferably 15G or more, and even more preferably 18G or more. Furthermore, the above centrifugal acceleration is preferably 40G or less, more preferably 30G or less, and even more preferably 25G or less. By keeping the centrifugal acceleration within the above range, the effects of the present invention can be made even more pronounced.

[0049] Furthermore, the aforementioned liquid-phase method can also be used in the compounding of the main component and the conductive material. In this case, the conductive material is first dispersed in an organic solvent, and then the raw materials for the particles of the compound constituting the main component, or the compounds constituting the main component, are placed in the organic solvent. This allows the particles to precipitate on the surface or inside the conductive material, thereby enabling compounding. Compounding by this method makes it possible to further reduce the particle size of the compounded particles.

[0050] The active material of the present invention can be mixed with an electrolyte, a conductive material, a binder, etc., to form an electrode mixture. When the active material of the present invention is used as a positive electrode active material, the electrode mixture becomes a positive electrode mixture that constitutes the positive electrode layer.

[0051] 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 viewpoint of making the effects of the present invention more pronounced, the solid electrolyte is preferably a sulfide solid electrolyte. The sulfide solid electrolyte can be the same as that used in general solid-state batteries. The sulfide solid electrolyte may, for example, contain Li and S and have lithium ion conductivity. The sulfide solid electrolyte may be a crystalline material, glass ceramic, or glass. The sulfide solid electrolyte may have an argyrodite-type crystal structure. Examples of such sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiX (where "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 Compounds represented by (where "X" represents one or more halogen elements; a represents a number between 3.0 and 9.0; b represents a number between 3.5 and 6.0; c represents a number between 0.1 and 3.0) are examples. Other examples include sulfide solid electrolytes described in International Publication No. 2013 / 099834 and International Publication No. 2015 / 001818.

[0052] The active material contained in the electrode mixture may consist solely of the active material of the present invention, or it may be used in combination with other active materials. Other active materials include known elemental sulfur and active materials containing sulfur. The proportion of the active material of the present invention in the electrode mixture may be, for example, 20% by mass or more, 30% by mass or more, or 40% by mass or more. On the other hand, the aforementioned proportion may be, for example, 70% by mass or less, or 60% by mass or less.

[0053] The battery of the present invention 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 preferably the active material described above. The battery can be manufactured, for example, by stacking three layers of the positive electrode layer, solid electrolyte layer, and negative electrode layer manufactured as described above and press-molding them.

[0054] The battery of the present invention preferably has an interface in which the positive electrode active material and the solid electrolyte come into contact, in order to make the desired effect more pronounced. Here, "the positive electrode active material and the solid electrolyte come into contact" includes both the positive electrode active material contained in the positive electrode layer coming into contact with the solid electrolyte, and the positive electrode active material contained in the positive electrode layer coming into contact with the solid electrolyte contained in the solid electrolyte layer.

[0055] The battery having the active material of the present invention is preferably a lithium-ion battery, and more preferably a lithium-sulfur battery. Examples of batteries in this invention include solid-state batteries having a solid electrolyte layer, and especially all-solid-state batteries. The battery in this invention may be a primary battery or a secondary battery, but it is preferably used as a secondary battery, and particularly preferably as a lithium secondary battery. "Lithium secondary battery" broadly encompasses secondary batteries that perform charging and discharging by the movement of lithium ions between the positive and negative electrodes.

[0056] A solid-state battery has 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. The term "solid-state battery" includes not only solid-state batteries that do not contain any liquid or gel-like substances as an electrolyte, but also embodiments that contain, for example, 50% by mass or less, 30% by mass or less, or 10% by mass or less of a liquid or gel-like substance as an electrolyte. [Examples]

[0057] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to these examples. Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass," respectively.

[0058] [Example 1] Li shown in Table 1 5.8 PS 4.8 Cl 1.2 To achieve the desired composition, lithium sulfide (Li2S) powder, phosphorus pentasulfide (P2S5) powder, and lithium chloride (LiCl) powder were used. Each was weighed to a total of 2g, and the mixture was mixed and ground using a planetary ball mill (Fritsch, P-7) at 150 rpm for 20 hours to prepare a mixed powder. This mixed powder was filled into a carbon container and heated in a tubular electric furnace at a heating rate of 200°C / h while circulating hydrogen sulfide gas (H2S, 100% purity) at a rate of 1.0 L / min, and calcined at 500°C for 4 hours. After that, the sample was crushed in a mortar, ground in a ball mill, and then sieved through a 53 μm mesh sieve to obtain a particle size D 50 A powdered compound with a particle size of 3.8 μm was obtained. X-ray diffraction (hereinafter also referred to as "XRD") measurements confirmed that this compound has a crystalline phase with an argyrodite-type crystal structure. As the conductive material, Ketjenblack® EC300, a conductive carbon black manufactured by Lion Specialty Chemicals, was used. This conductive material has a particle size of D 50The particle size was 0.04 μm. 20 parts of conductive material were used for 100 parts of the compound, and the mixture was compounded using a planetary ball mill (Fritsch, P-7) at 500 rpm for 10 hours. Afterwards, the sample was crushed in a mortar and sieved to a particle size D using a sieve with a mesh size of 53 μm. 50 A particle of the positive electrode active material with a size of 3.2 μm was obtained. All of the above operations were performed inside a glove box that had been purged with thoroughly dried Ar gas (dew point below -60°C).

[0059] [Examples 2-4] 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 , and Li 5.8 PS 4.8 Cl 1.2 A compound powder was obtained in the same manner as in Example 1, except that the raw material powders were mixed to achieve the specified composition. XRD measurements confirmed that the obtained compound had a crystalline phase with an argyrodite-type crystal structure. As the conductive material, carbon nanotubes (Showa Denko, VGCF(registered trademark)-H) or Ketjenblack was used, as in Example 1. These carbon nanotubes had a fiber diameter of 150 nm and a fiber length of 6 μm. In Example 4, active material particles were obtained in the same manner as in Example 1, except that 10 parts of Ketjenbrak were used for every 100 parts of the compound.

[0060] [Examples 5 and 6] Table 1 shows Li7PS6 and Li 7.3 P 0.9 Fe 0.1To achieve the composition of S6, each raw material powder was weighed to a total amount of 2g, and an amorphous mixed powder was prepared by mechanical milling using a planetary ball mill (Fritsch, P-7) at 500 rpm for 20 hours. This amorphous mixed powder was then packed into a carbon container and heated in a tubular electric furnace at a heating / cooling rate of 200°C / h while flowing inert gas (Ar, 100% purity) at 1.0 L / min, and calcined at 400°C for 4 hours. The sample was then crushed in a mortar and pestle, and sieved through a 53 μm mesh to obtain a powdered compound with the particle size shown in Table 1. XRD measurement confirmed that this compound has a crystalline phase with an argyrodite-type crystal structure. The active material particles were obtained in the same manner as in Example 2.

[0061] [Comparative Example 1] This comparative example shows a case in which active material particles were manufactured by compounding a conductive material consisting of Ketjenblack onto the surface or interior of elemental sulfur particles. Particle size D 50 For 100 parts of sulfur particles with a particle size of 35.6 μm, particle size D 50 Twenty parts of Ketjenblack with a particle size of 0.04 μm were used, and the two were mixed and compounded using a planetary ball mill (Fritsch, P-7) at 500 revolutions per minute for 10 hours, as in Example 1. 50 We obtained active material particles with a diameter of 28.4 μm.

[0062] [Comparative Example 2] This comparative example shows a case in which active material particles were manufactured by compounding a conductive material made of carbon nanotubes onto the surface or inside lithium sulfide particles. Particle size D 50 For 100 parts of lithium sulfide particles with a particle size of 20 μm, the particle size D 50 Twenty parts of carbon nanotubes with a particle size of 0.15 μm were used, and both were mixed and compounded using a planetary ball mill (Fritsch, P-7) at 500 revolutions per minute for 10 hours, as in Example 1. 50 We obtained active material particles with a diameter of 17.4 μm.

[0063] [Comparative Example 3] This comparative example uses the Li used in Example 1. 5.8 PS 4.8 Cl 1.2 This is an example of manufacturing active material particles without compounding a conductive material consisting of Ketjenblack on the surface or inside the particles. Particle size D 50 Li is 3.8 μm 5.8 PS 4.8 Cl 1.2 For every 100 parts of the particles, 20 parts of Ketjenbrak were used, and the two were mixed in the same manner as in Example 1 using a planetary ball mill (Fritsch, P-7) at 200 revolutions per minute for 10 hours. In this way, the particle size D 50 We obtained active material particles with a diameter of 3.6 μm.

[0064] [Comparative Example 4] This comparative example, like Comparative Example 3, uses the same Li as in Example 1. 5.8 PS 4.8 Cl 1.2 This is an example of manufacturing active material particles without compounding a conductive material consisting of Ketjenblack on the surface or inside the particles. Particle size D 50 Li is 3.8 μm 5.8 PS 4.8 Cl 1.2 For every 100 parts of the particles, 20 parts of Ketjenbrak were used, and the two were mixed in the same manner as in Example 1 using a planetary ball mill (Fritsch, P-7) at 300 revolutions per hour. In this way, the particle size D 50 We obtained active material particles with a diameter of 3.3 μm.

[0065] [Comparative Example 5] This comparative example uses only the Li7PS6 particles used in Example 5, and is an example of using them as an active material without compounding them with a conductive material.

[0066] [Measurement of elemental composition] The powder of the main compound obtained in the examples and comparative examples was completely dissolved, and its elemental composition was measured by ICP emission spectroscopy. As a result, it was confirmed that it was in general agreement with the blending ratio of the raw material compound. The lithium content of the active material obtained in the examples and comparative examples was measured using the same method.

[0067] [Identification of the generated phase] The powder of the main compound obtained in the examples and comparative examples was analyzed by X-ray diffraction (XRD) to identify the generated phase.

[0068] [XRD measurement] The positive electrode active material powders obtained in the examples and comparative examples were packed into airtight holders that were not exposed to air, in a glove box purged with sufficiently dry Ar gas (dew point below -60°C), and XRD measurements were performed. The generated phase was identified by the XRD measurements, and the full width at half maximum (FWHM) of the peak located at 2θ = 29.62° ± 1.0° of the argyrodite-type crystalline phase (hereinafter sometimes referred to as "peak A") was calculated. The XRD measurement conditions were as follows. • Equipment name: Fully automated multi-purpose X-ray diffractometer SmartLab SE (manufactured by Rigaku Corporation) ·Radiation source:CuKα1 • Tube voltage: 40kV ·Tube current: 50mA ·Measurement method: Concentration method (reflection method) • Optical system: Multilayer mirror divergent beam method (CBO-α) • Detector: One-dimensional semiconductor detector • Incident solar slit: Solar slit 2.5° • Longitudinal limiting slit: 10mm • Solar light receiving slit: 2.5° • Entrance slit: 1 / 6° • Light-receiving slit: 2mm (open) • Measurement range: 2θ = 10~120° Step width: 0.02° • Scan speed: 1.0° / min

[0069] [Particle size D 50 ] The main compound powder and cathode active material powder obtained in the examples and comparative examples were prepared by using an automated sample feeder for laser diffraction particle size distribution analyzers (Microtorac SDC, manufactured by Microtorac-Bell, Inc.). The sample (powder) was placed in an aqueous solvent, and after irradiating it with 40W ultrasound multiple times for 360 seconds at a flow rate of 40%, the particle size distribution was measured using a Microtorac-Bell MT3000II laser diffraction particle size distribution analyzer. The resulting volume-based particle size distribution chart was used to determine the particle size D 50 We measured it.

[0070] [Ionic conductivity] The main compound powders obtained in the examples and comparative examples were uniaxially compressed in a glove box purged with sufficiently dry Ar gas (dew point below -60°C), and then compressed at 200 MPa in a CIP (cold isostatic press) to produce pellets with a diameter of 10 mm and a thickness of approximately 4-5 mm. Carbon paste was then applied to both the upper and lower surfaces of the pellets as electrodes, and then heat-treated at 180°C for 30 minutes to prepare samples for ionic conductivity measurement. Ionic conductivity (S / cm) was measured at room temperature (25°C) using the AC impedance method with a measurement frequency of 0.1 Hz to 1 MHz, using a Solartron 1255B manufactured by Toyo Technica Co., Ltd.

[0071] [Observation of active material particles and elemental mapping] The positive electrode active material powders obtained in the examples and comparative examples were observed using a scanning electron microscope (SEM-EDS) equipped with an energy-dispersive X-ray spectrometer. The sulfur element, which is a constituent element of the main compound, was mapped to the constituent elements of the conductive material, and the state of composite formation was confirmed by measuring the state of existence of the sulfur element of the compound and the constituent elements of the conductive material. Furthermore, after fabricating batteries using the active materials obtained in the examples and comparative examples, the cross-section of the positive electrode layer of the battery was observed in the same manner as described above, and the state of composite formation in the battery was confirmed by measuring the state of the sulfur element of the compound and the constituent elements of the conductive material on the surface and inside the active material.

[0072] [Battery evaluation] Using the active materials obtained in Examples and Comparative Examples as positive electrode active materials, solid batteries were produced by the following procedure. The initial capacity and rate characteristics of the produced solid batteries were evaluated by the following procedure. The results are shown in Tables 1 and 2 below.

[0073] <Production of All-Solid-State Battery Cell> The materials produced in Examples and Comparative Examples were used as positive electrode active materials, and Li having an argyrodite-type crystal structure was used as the solid electrolyte powder for the positive electrode layer and the solid electrolyte layer 5.4 PS 4.4 Cl 0.8 Br 0.8 , and an In-Li alloy was used as the negative electrode active material for the negative electrode layer to produce an all-solid-state battery. (Preparation of Positive Electrode Mixture) The positive electrode mixture powder for the positive electrode layer was prepared by mixing the positive electrode active material powder obtained in Examples and Comparative Examples and the solid electrolyte powder in a mortar at a mass ratio of 60:40. In Comparative Example 4, since the positive electrode active material powder was not compounded with a conductive material, it was prepared by mixing the positive electrode active material powder, the solid electrolyte powder, and the aforementioned carbon nanotubes as a conductive material for imparting conductivity to the positive electrode layer in a mortar at a mass ratio of 50:40:10.

[0074] (Production of All-Solid-State Battery Cell) A polypropylene cylinder (opening diameter 10.5 mm, height 18 mm) with open top and bottom was sealed at the bottom opening with a negative electrode (made of stainless steel), solid electrolyte powder was placed on top, sealed with a positive electrode (made of stainless steel), and then uniaxially pressed at 200 MPa to form a solid electrolyte layer. Next, the positive electrode was removed, positive electrode mixture powder was placed on top of the solid electrolyte layer, sealed again with the positive electrode, and then uniaxially pressed at 560 MPa to laminate the positive electrode layer and the solid electrolyte layer. After that, the cylinder was inverted, the negative electrode was removed, In-Li foil was placed on top of the solid electrolyte layer, sealed again with the negative electrode, and finally, the positive and negative electrodes were clamped together with a C-clamp under a load of 6 N·m to produce an all-solid-state battery cell in which the positive electrode layer, solid electrolyte layer, and negative electrode layer were laminated. The thickness of each layer is approximately 40 μm for the positive electrode layer, approximately 600 μm for the solid electrolyte layer, and approximately 400 μm for the negative electrode layer. The all-solid-state battery cells were fabricated in a glove box purged with argon gas at a dew point of -60°C. The fabricated all-solid-state batteries were then connected to a charge / discharge measurement device in an environmental test chamber maintained at 25°C to evaluate their battery characteristics. A charge / discharge current of 2.0 mA was defined as the 1C rate.

[0075] [Initial capacity] In the initial charge-discharge cycle (1st cycle), to efficiently de-absorb lithium ions contained in the positive electrode active material, the device was charged to 3.0V at 0.03C using the CC-CV method and discharged to 0.38V at 0.03C using the CC method. In the 2nd cycle, the device was charged to 3.0V at 0.1C using the CC-CV method and discharged to 0.38V at 0.1C using the CC method. Here, the charge-discharge capacity of the 2nd cycle was defined as the initial charge-discharge capacity. Note that in the active material of Comparative Example 1, which is a composite of elemental sulfur and a conductive material, the active material does not contain lithium, so the 1st cycle started with discharge.

[0076] [Rate characteristics] The third charge-discharge cycle was performed using the method described above. From the fourth cycle onward, charge-discharge was performed at rates of 0.2C, 0.5C, 1C, 2C, and 5C, and the rate characteristics were evaluated by comparing the discharge capacity at each rate with the discharge capacity in the second cycle (0.1C).

[0077] [Table 1]

[0078] [Table 2]

[0079] As is clear from the results shown in Tables 1 and 2, 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 examples. In particular, as is clear from the comparison between Examples 1 and 3, which contain Ketjenblack in the conductive portion, and Examples 2, 3, 5, and 6, which contain carbon nanotubes in the conductive portion, Examples 1 and 3 have higher battery discharge rate characteristics. In other words, it can be seen that including Ketjenblack in the conductive portion can improve the battery's discharge rate characteristics. Comparative Example 1, which uses elemental sulfur as the main component, has a high initial capacity but a low rate characteristic. The inventors speculate that this is because elemental sulfur has such low lithium ion conductivity that it cannot be measured, and therefore lithium ions cannot be quickly absorbed into the elemental sulfur even if the discharge current is increased to raise the rate. Elemental mapping using SEM-EDS confirmed that the active materials obtained in each example had sulfur and carbon elements overlapping on their surface and within their interior.

[0080] Figures 1, 2, 3, and 10 show the charge-discharge curves of all-solid-state batteries using the positive electrode active materials prepared in Example 1, Example 5, Comparative Example 3, and Comparative Example 10, respectively, when the charge-discharge rates were varied to 0.1C, 0.2C, 0.5C, 1C, 2C, and 5C. In the all-solid-state batteries using the positive electrode active materials prepared in Examples 1 and 5, high discharge capacity was observed even at high charge-discharge rates. However, in the all-solid-state batteries using the positive electrode active materials prepared in Comparative Examples 3 and 4, the discharge capacity decreased significantly when the charge-discharge rate was increased. In particular, in Comparative Examples 3 and 4, despite using compound powder with the same composition as Example 1 as the main component, the initial capacity and discharge rate characteristics were 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 was large, and the rotation speed of the planetary ball mill used during the compounding process was low, resulting in the conductive material not being uniformly dispersed on the surface and inside the compound particles, thus preventing it from exhibiting its performance as a positive electrode active material.

[0081] Figures 4 and 5 show SEM images of the appearance of the positive electrode active material powders prepared in Example 5 and Comparative Example 4, and EDS mapping of the carbon and sulfur elements. The compounds used in Example 5 and Comparative Example 4 had the same composition. In the positive electrode active material powder prepared in Example 5, the carbon element, which is the conductive material component, and the sulfur element, which is the compound component, were found to be overlapping, confirming that the compound particles and the conductive material were uniformly composited. On the other hand, in the positive electrode active material powder prepared in Comparative Example 4, the carbon element, which is the conductive material component, was found to be in a different position from the sulfur element of the compound, confirming that the positive electrode active material prepared in Comparative Example 4 was not composited with the compound particles and the conductive material, but was simply mixed.

[0082] Figures 6 and 7 show the cross-sections of all-solid-state batteries prepared using the positive electrode active material powders in Example 5 and Comparative Example 4, which were processed with a cross-section polisher (CP) to create cross-sections. The states of carbon, sulfur, and bromine elements were then mapped using SEM observation and EDS. In the cross-section of the all-solid-state battery prepared using the positive electrode active material powder in Example 5, the carbon element, which is a conductive material component, was located in areas where bromine, a component of the solid electrolyte, was absent and sulfur was abundant. This confirmed that the conductive material was uniformly compounded on the surface and inside the compound particles. On the other hand, in the cross-section of the all-solid-state battery prepared using the positive electrode active material powder in Comparative Example 4, the carbon element, which is a conductive material component, was located around areas where bromine, a component of the compound, was present and sulfur was abundant. This confirmed that the conductive material was not compounded with the compound particles, and that the compound powder and conductive material powder were simply mixed together.

[0083] Figure 8 shows the XRD patterns of the positive electrode active material powders prepared in Examples 1, 3, and 4. In Examples 1, 3, and 4, when the main portion and conductive portion, which are in a mixed state, are compounded using a planetary ball mill, high rotational speed conditions are adopted to apply high centrifugal acceleration, resulting in high mechanical energy being applied to both the main portion and the conductive portion, thus compounding them. During compounding, while maintaining the argyrodite-type crystalline phase, the crystal phase becomes moderately less crystallinity, which broadens the full width at half maximum (FWHM) of each diffraction peak attributed to the argyrodite-type crystalline phase, as can be confirmed from the XRD diffraction patterns shown in Figure 8 and the FWHMs shown in Table 3 below.

[0084] Figure 9 shows the XRD patterns of the positive electrode active material powders prepared in Comparative Examples 3 and 4. In Comparative Examples 3 and 4, when the main portion and conductive portion were combined in a planetary ball mill using a low rotation speed, the centrifugal acceleration applied was insufficient. As a result, high mechanical energy was not applied to the main portion and conductive portion, and they did not combine sufficiently. Furthermore, the high crystallinity of the argyrodite-type crystalline phase contained in the main portion was confirmed from the XRD diffraction patterns shown in Figure 9 and the full width at half maximum shown in Table 3 below.

[0085] [Table 3] [Industrial applicability]

[0086] As described in detail above, the active material of the present invention can improve the performance of lithium-ion batteries.

Claims

1. A method for producing an active material, A first step of preparing a compound containing lithium (Li) element, sulfur (S) element, and M element (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 containing at least phosphorus (P) and iron (Fe)), and including a crystalline phase having an argyrodite type crystal structure, The process includes a second step of mixing the aforementioned compound with a conductive material to form a composite, The second step is to apply mechanical energy of 10G or more in centrifugal acceleration to mix and composite the compound and the conductive material. A method for producing active material.

2. The manufacturing method according to claim 1, wherein in the second step, mechanical energy is applied to the compound and the conductive material using a planetary ball mill to composite them.

3. The manufacturing method according to claim 1 or 2, wherein the second step is performed such that the full width at half maximum of the peak located at 2θ = 29.62 ± 1.0° in the X-ray diffraction pattern measured using CuKα1 line is 0.4° or more.

4. The manufacturing method according to any one of claims 1 to 3, wherein in the second step, 1 to 50 parts by mass of the conductive material is mixed with 100 parts by mass of the compound.

5. The aforementioned compound has a cumulative volume particle size D at 50% of the cumulative volume, as measured by laser diffraction scattering particle size distribution analysis. ５０ The manufacturing method according to any one of claims 1 to 4, wherein the particle size is 0.1 μm or more and 20 μm or less.

6. The manufacturing method according to any one of claims 1 to 5, wherein the compound further contains a halogen (X) element.

7. The aforementioned compound has the compositional formula Li ａ MS ｂ X ｃ The manufacturing method according to claim 6, represented by the formula (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), and contains at least phosphorus (P) and iron (Fe). X is at least one element selected from fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). a is 3.0 or more and 9.0 or less, b is 3.5 or more and 6.0 or less, and c is 0.10 or more and 3.0 or less.)

8. The manufacturing method according to any one of claims 1 to 7, wherein the conductive material is carbon black.

9. The manufacturing method according to claim 8, wherein the conductive material is Ketjenblack.

10. It is an active material, A compound containing lithium (Li) element, sulfur (S) element, and M element (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 containing at least phosphorus (P) and iron (Fe), and having a crystalline phase having an argyrodite type crystal structure, Having a conductive material, The active material comprises a main portion containing the compound and a conductive portion disposed on at least one of the surface and interior of the main portion, which contains the conductive material. The active material is a composite material of the compound and the conductive material, The aforementioned active material is When the active material is observed using a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer, and the constituent elements of the compound are mapped to the constituent elements of the conductive material, it can be confirmed that the constituent elements of the compound and the constituent elements of the conductive material are present in an overlapping manner, or When observing the cross-section of the positive electrode layer of a battery made using the active material, can it be confirmed that the constituent elements of the compound and the constituent elements of the conductive material are present in an overlapping manner, or An active material in which the presence of C-S bonds can be confirmed by Raman spectroscopy or photoelectron spectroscopy applied to the aforementioned active material.

11. The active material according to claim 10, wherein the conductive material is inseparably dispersed in the compound.

12. The active material according to claim 10 or 11, wherein, in the X-ray diffraction pattern measured using CuKα1 rays, the full width at half maximum of the peak located at 2θ = 29.62 ± 1.0° is 0.4° or more.

13. The active material according to any one of claims 10 to 12, wherein the conductive material is contained in 1 to 50 parts by mass per 100 parts by mass of the compound.

14. The active material according to any one of claims 10 to 13, wherein the conductive material is a carbon material or a metallic material.

15. The active material according to claim 14, wherein the conductive material is carbon black.

16. The active material according to claim 15, wherein the conductive material is Ketjenblack.

17. The active material according to any one of claims 10 to 16, wherein the content of the lithium element in the compound is 10% by mass or more and 25% by mass or less.

18. The active material according to any one of claims 10 to 17, wherein the compound further contains a halogen (X) element.

19. An electrode mixture comprising an active material according to any one of claims 10 to 18 and a sulfide solid electrolyte.

20. A battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer, A battery wherein the positive electrode layer contains the active material described in any one of claims 10 to 18.

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