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

Abstract

To provide an active material that can improve the performance of lithium-sulfur batteries. [Solution] The active material of the present invention contains lithium (Li) element, sulfur (S) element, and M element A compound containing a crystalline phase having an argyrodite-type crystal structure, and a surface of the particles of the compound. It has conductive material dispersed on its surface and inside. The M element contains less phosphorus (P) and iron (Fe). This also includes. The active material of the present invention is a composite material of the compound and the conductive material. The conductive material is It is preferable that the material be a carbon material or a metallic material. The content of the lithium element in the active material It is also preferable that the amount be between 10% by mass and 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 binder containing the active material and a battery.

Background Art

[0002] Lithium-ion batteries are widely used as power sources for portable electronic devices such as notebook computers and mobile phones because of their high energy density and ease of miniaturization and weight reduction. Recently, the development of high-power and high-capacity lithium-ion batteries for electric vehicles and hybrid electric vehicles has been underway.

[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 in which Li3PS4 glass, which is a sulfide solid electrolyte, and a carbon-based conductive aid are combined.

[0004] By the way, the present inventor has conducted research on sulfide solid electrolytes used in lithium-ion batteries, and proposed a compound represented by the composition formula Li PS 7-x 6-x Ha (where 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

[0006] [Non-Patent Document 1] Journal of Power Sources 293 (2015) 721-725 [Overview of the project]

[0007] The inventors conducted studies aimed at improving the performance of lithium-ion batteries. As a result, When aiming to further improve the performance of lithium-ion batteries, superior positive electrode active materials are required. We identified a problem that is being addressed. The object of the present invention is to provide an active material that can improve the performance of lithium-ion batteries. It is located there.

[0008] The electrolyte and active material used in batteries each play completely different roles. For example, sulfur In conventional technologies that repurpose materials used in ion solid electrolytes as active material materials, the capacity and Further improving battery performance, such as rate characteristics, has been difficult. On the other hand, the inventors of the present invention have made the above-mentioned The sulfide solid electrolyte proposed in Patent Document 2 is mixed with a conductive material to form a composite. Therefore, it not only functions as an active material, but also as a positive electrode active material for lithium-ion batteries. By using it in this way, it is possible to improve battery performance such as capacity and rate characteristics compared to before. This was discovered.

[0009] This invention is based on the aforementioned findings and involves the elements lithium (Li) and sulfur (S). Elements, and M elements (where M is phosphorus (P), germanium (Ge), antimony (Sb), kerosene, etc.) Element (Si), tin (Sn), aluminum (Al), titanium (Ti), iron (Fe), nitrile It is at least one of the following: nickel (Ni), cobalt (Co), and manganese (Mn). A compound containing . ) and having a crystalline phase having an argyrodite-type crystal structure, Having a conductive material, The above problem is addressed by providing an active material which is a composite material of the compound and the conductive material. This solves the problem.

[0010] Furthermore, the present invention provides a suitable method for producing the active material, Lithium (Li) element, sulfur (S) element, and M element (M is phosphorus (P), germanium Metal (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al ), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co), and manganese ( It contains at least one of Mn, and has an argyrodite-type crystal structure. The first step involves preparing a compound containing a crystalline phase, 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 its preferred embodiments. The present invention relates to an active material for a battery. Currently, the mainstream secondary battery is the lithium-ion battery. There is a demand for even higher energy density in batteries. From that perspective, regarding the active material Sulfides, which have fewer constraints and allow for high energy density, were used as the solid electrolyte. Solid-state batteries are attracting attention. Furthermore, with the aim of achieving even higher energy density, high-capacity solid-state batteries are being developed. There is a need for an active material that possesses high-rate characteristics that can handle short-time charging and discharging. There is also a demand for active materials that perform certain functions. The active material of the present invention meets these demands.

[0013] The active material of the present invention comprises particles of a specific compound and a conductive material compounded with said particles. Therefore, the active material of the present invention comprises a main part containing particles of a specific compound, and the surface of the main part and / or a conductive part containing a conductive material dispersed internally and providing electronic conductivity. It contains particles. The main part and conductive part will be described below.

[0014] The main part is composed of a compound containing a specific element. More specifically, the main part is lithium It is preferable that it is composed of a compound containing the elements of lithium (Li), sulfur (S), and element M. Preferably, element M is at least one of, for example, phosphorus (P), germanium (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co), and manganese (Mn). (Ti), iron (Fe), nickel (Ni), cobalt (Co), and manganese (Mn). It is preferably at least one of the elements.

[0015] Examples of the compound containing the elements of Li, S, and M include compounds containing only the elements of Li, S, and M, such as Li7PS6, Li (P 7+3x ( 5+ 1-x Fe 2+ x )S6 , Li 7+x (P 5+ 1-x Si 4+ x )S6, etc. (where x represents a number of 0.1 or more and 1.0 or less.). In addition, as the compound containing the elements of Li, S, and M, those containing other elements in addition to these three elements can also be used. Examples of the other element include halogen ( X). By using a compound containing the element X in addition to the elements of Li, S, and M, the characteristics of the active material of the present invention are further improved, which is preferable. As the element X, at least one selected from F , Cl, Br, and I can be used. The compound containing the elements of Li, S, M, and X has the composition formula (1) Li MS

[0016] Li a MS b X c (where M is phosphorus (P), germanium (Ge), antimony (Sb), silicon ( Si (silicon), tin (Sn), aluminum (Al), titanium (Ti), iron (Fe), nickel (Ni), at least one of the following elements: cobalt (Co) and manganese (Mn) X is a small number of elements selected from fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). It is at least one type of element.) The fact that it is represented as an active material means that the ionic conductivity is improved. This is preferable because it further enhances the characteristics of the subject.

[0017] From the viewpoint of improving lithium-ion conductivity, a is preferably 3.0 or more and 9.0 or less. 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, and more preferably 4.0 to 5.8. Furthermore, it is more preferably 4.2 to 5.5. Moreover, c is preferably 0.10 More preferably 3.0 or less, more preferably 0.50 or more and 2.5 or less, and even more preferably 1.0 or less. The value is 1.8 or less.

[0018] In particular, the element M in the above compositional formula is phosphorus (P), germanium (Ge), and anthracite. At least one of the elements timon (Sb), tin (Sn), and silicon (Si) It is preferable that the active material contains phosphorus (P), and in particular, the properties of the active material are enhanced. This is preferable because it will increase even further.

[0019] The main compound is, in particular, Li (2) 7-d MS 6-d X d This is represented by This is preferable because it further enhances the properties of the active material. In the formula, d is preferably 0. 40 to 2.2, more preferably 0.80 to 2.0, and even more preferably 1. It is between 2 and 1.8.

[0020] In compositional formulas (1) and (2), a portion of the M element is silicon (Si), germanium Ge (metal), tin (sn), lead (pb), boron (b), aluminum (Al) element, gallium (Ga) element, arsenic (As) element, antimony (Sb) element and It may be substituted with one or more elements selected from the element bismuth (Bi). In this case, equation (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 This is the result. M2 is silicon (Si) element, germanium Element nium (Ge), element tin (Sn), element lead (Pb), element boron (B), aluminum The elements of aluminum (Al), gallium (Ga), arsenic (As), and antimony (Sb) and one or more elements selected from the element bismuth (Bi). y is preferred More preferably 0.010 to 0.70, more preferably 0.020 to 0.40, More preferably, it is 0.050 or more and 0.20 or less. Note that element M1 is of compositional formula (1) It is similar to the M element explained earlier.

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

[0022] The compound constituting the main part contains the elements mentioned above, as well as an argyrodite crystal. It is preferable that the active material of the present invention contains a crystalline phase having a structure. Further improvement. In particular, the compound constituting the main part has a cubic argylodite crystal structure. It is preferable that it contains a crystalline phase. Whether or not it contains a crystalline phase having an argyrodite-type crystalline structure This can be determined by analyzing the active material of the present invention by X-ray diffraction. As CuKα rays For example, CuKα1 line can be used.

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

[0024] The compound constituting the main part is found in the X-ray diffraction pattern measured using CuKα1 rays. In addition to the positions 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° It is even more preferable that the peaks be located at one or more positions selected from 2θ = 25.1 In addition to the positions 9°±1.00° and 29.62°±1.00°, 2θ=15.34°± 1.00°, 17.74°±1.00°, 30.97°±1.00°, 44.37°±1 P It is even more preferable to have these peaks. These peaks are due to the argyrodite-type crystalline phase. This is the upcoming peak.

[0025] Note that the peak position mentioned above is expressed as median ± 1.00°, but median ± 0. It is preferably 500°, and more preferably ±0.300° of the median.

[0026] The main part contains the compound described above, and may contain other materials or other components as needed. Therefore, the main part consists of a single phase composed of a crystalline phase with an argyrodite-type crystal structure. It may be, or it may include other phases in addition to the phase in question. For example, the core part is In addition to the crystalline phase with an argyrodite-type crystal structure, there are also Li2S phase, Li3PS4 phase, and Li4P It may contain a 2S6 phase, LiCl or LiBr phase, etc. In particular, if the main part is argillodi The presence of a Li2S phase in addition to the crystalline phase with a T-type crystal structure increases the capacity of the active material. Preferably, the main part contains Li, S, M and X elements, and is argyrodyne. It is preferable to use a compound containing a crystalline phase having a T-type crystalline structure as the main material. Furthermore, the main part is In addition to the other materials and components mentioned above, to an extent that does not adversely affect the effects of the present invention, for example, 5 It may contain unavoidable impurities in amounts less than 1% by mass, particularly less than 3% by mass.

[0027] The main part containing the above-mentioned compound has the form of particles, and on the surface or inside of these particles, A conductive part containing the aforementioned conductive material is arranged. The conductive material is an electronically conductive material. It can be used without any particular restrictions. Examples of conductive materials include various metal materials and conductive non-conductive materials. Examples include metallic materials. Metallic materials and conductive nonmetallic materials are either one of these. They may be used, or both may be used in combination. The metal material may be each Precious metal elements, for example, gold (Au), silver (Ag), platinum (Pt), palladium Pd (Particle), Rh (Rh), Iridium (Ir), Ruthenium (Ru) Examples include elements such as osmium (Os). Also, various transition metal elements, such as copper. Examples include elements such as (Cu) (copper), iron (Fe), and tin (Sn). An element may be used alone, or two or more elements may be used in combination. As the conductive nonmetallic material, for example, a carbon material can be used. It contains graphite, acetylene black, carbon black, carbon nanofiber, and Examples include carbon nanotubes, nanographene, and fullerene nanowhiskers. These carbon materials may be used individually or in combination of two or more. Good. Of these carbon materials, using carbon black will improve the initial capacity of the battery and This is preferable in terms of improving discharge rate characteristics. From the viewpoint of making this advantage even more pronounced, It is preferable to use Ketjenblack as the carbon black, and among them, Furnace Black It is preferable to use a rack, and in particular, it is preferable to use an oil furnace black. .

[0028] The conductive part containing the various conductive materials described above, when lithium is deabsorbed from the main part, the electron conduction part To fulfill its role as a particle, it needs to be uniformly dispersed and adhered to the surface and interior.

[0029] From the perspective of uniformly dispersing the conductive material, including the conductive part, on the surface and inside the main part, the size of the conductive material It is preferable that the size is smaller than the size of the main part. Specifically, let the particle size of the main part be D1, and the conductive When the grain size of the material is D2, the value of D1 / D2 is preferably 2 or more, for example, 5 It is more preferable that it be greater than or equal to 10, and even more preferable that it be 10 or more. On the other hand, D1 / D2 The value of is preferably 1000 or less, and more preferably 500 or less. Furthermore, it is even more preferable that the value be between 10 and 100.

[0030] The particle size D1 of the main part is preferably 0.1 μm or larger, and preferably 0.2 μm or larger. It is even more preferable that it be 0.5 μm or larger. On the other hand, D1 is, for example It is preferably 20 μm or less, more preferably 10 μm or less, and 5 μm The following is even more preferable. Furthermore, the particle size D2 of the conductive part is, for example, 1 nm or larger. It is preferable that it be 10 nm or more, more preferably 20 nm or more. A layer is preferable. On the other hand, D2 is preferably 500 nm or less, and 300 nm or less. It is even more preferable that it be below this value, and even more preferable that it be 200 nm or less.

[0031] The particle size of the main part is measured by the cumulative volume 50 volume by the laser diffraction scattering particle size distribution method. Volume cumulative particle size D in % 50 (hereinafter referred to as "D") 50 When we say "this particle size", we mean (Meaning.) On the other hand, the particle size of the conductive part is when the conductive part is dispersed inside the particles of the main part. In this case, measurement is difficult using laser diffraction scattering particle size distribution measurement. Therefore, SEM (Scanning Emission Microscope) Using an electron microscope (TEM) or a transmission electron microscope (TEM), the conductive parts dispersed inside the main body are directly examined. The average particle size is measured by close observation. For example, if the conductive material is carbon nanotubes as described above... In the case of fibers or carbon nanofibers, fiber diameter refers to the diameter or major axis of the fiber cross-section. This refers to the average value of the minor axis.

[0032] In the active material of the present invention, a material is formed by the combination of a main part and a conductive part, that is, the main part is composed of This is a composite material consisting of compound particles and a conductive material that constitutes the conductive part. In this state, the conductive part is dispersed on the surface or inside the main part, in close contact with the main part and inseparably integrated with it. It is preferable that the "compounded" form includes, for example, the surface of the compound particles and / or This includes embodiments in which conductive material particles are inseparably dispersed inside, and particles of the compound constituting the main part and One example is a configuration in which the conductive material particles constituting the conductive part chemically react and bond with each other. "The conductive material particles are inseparably dispersed on the surface and within the particles of the compound that constitutes the main part." For example, the active material of the present invention is measured using a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer. The active material is observed using a mirror (SEM-EDS) to identify the constituent elements of the compound that makes up the main part (e.g., sulfur When the yellow element is mapped to the constituent elements of the conductive material that makes up the conductive part, the main part is composed of The constituent elements of the compound (e.g., sulfur) and the constituent elements of the conductive material that makes up the conductive part overlap. This refers to a state in which it can be confirmed that it exists in such a way. Alternatively, it refers to the active use of the present invention. When observing the cross-section of the positive electrode layer of a battery made using a material, the surface and interior of the active material The constituent elements of the compound that makes up the main part (e.g., sulfur element) and the composition of the conductive material that makes up the conductive part This refers to a state in which the constituent elements can be observed to be overlapping. The fact that the conductive part is composite can be determined by, for example, Raman spectroscopy or photoelectron spectroscopy. This can be confirmed by checking whether or not the material is compatible (if the conductive material is made of carbon).

[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. It becomes possible to break it down, acquire conductivity, and acquire lithium-ion deabsorption function. Furthermore, argyrodite type crystals have a high lithium content and high lithium ion conductivity. By utilizing a compound having a crystalline structure as the main component, the battery having the active material of the present invention is This will result in high capacity and high rate characteristics. In particular, the active material of the present invention is lithium-ion battery It will be useful as a positive electrode active material for ponds. In contrast to conventionally known elemental sulfur and sulfur Lithium oxide (Li2S) and its composite materials, or sulfur-based positive electrode active materials such as metal sulfides Because these materials do not exhibit conductivity or have poor conductivity, they are used as active materials. There is a problem in that the desired battery performance cannot be obtained when used in this way.

[0034] The active material of the present invention exhibits the following characteristics in its X-ray diffraction pattern measured using CuKα1 rays: 2θ The full width at half maximum of the peak located at the position =29.62±1.0° is, for example, 0.4 or greater. It is preferable that it is 0.5 or higher, more preferably 0.6 or higher. i. The above-mentioned full width at half maximum is usually 3.0 or less. In the present invention, the manufacturing method described later In this process, the main part and the conductive part are combined by performing the second step under predetermined conditions, and the full width at half maximum This can be achieved. This is evident from the results of the examples and comparative examples described later. Therefore, the full width at half maximum of the peak located at 2θ = 29.62 ± 1.0° is the active function of the present invention. This serves as an indicator of the degree of composite formation between the main component and the conductive component in a material.

[0035] In the active material of the present invention, the conductive material is present in 100 parts by mass of particles of the compound constituting the main part. The amount is preferably, for example, 1 part by mass or more, and more preferably 2 parts by mass or more. Furthermore, it is more preferable that the amount be 5 parts by mass or more. On the other hand, the particles 10 of the compound constituting the main part The amount of conductive material relative to 0 parts by mass is preferably, for example, 50 parts by mass or less, and 20 parts by mass It is more preferably less than or equal to parts, and even more preferably less than or equal to 10 parts by mass. The presence of a main part and a conductive part allows the battery equipped with the active material of the present invention to have high capacity and high latency. The characteristic will be clearly expressed.

[0036] In the active material of the present invention, the lithium element content in the compound is, for example, 10 Preferably it is 1% by mass or more, more preferably 12% by mass or more, and 15% by mass It is even more preferable that the content be % or more. On the other hand, the content may be, for example, 25% by mass or less. Preferably, it is 23% by mass or less, and more preferably 21% by mass or less. Even more preferable. By setting the lithium element content within this range, the active material of the present invention The battery capacity can be further increased.

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

[0038] Next, a preferred method for producing the active material of the present invention will be described. This production method mainly involves, A first step is to prepare particles of the compound that constitute the main part, and a second step is to mix the particles of the compound with a conductive material. The process is broadly divided into two stages: the first stage, the second stage, and the third stage, which combines the two. The following describes each stage.

[0039] In the first step, the aforementioned elements are contained and have an argyrodite-type crystal structure. Particles of a compound containing a crystalline phase are prepared. This compound can be produced by known methods. Yes, it is possible. This compound can contain, for example, lithium (Li), phosphorus (P), sulfur (S), If chlorine (Cl) and bromine (Br) elements are present, lithium sulfide (Li2S) powder is used. And phosphorus pentasulfide (P2S5) powder, lithium chloride (LiCl) powder, and lithium bromide. (LiBr) powder is mixed with the compound and calcined to obtain particles of the compound. For mixing methods, for example, ball mills, bead mills, homogenizers, etc., can be used. preferable.

[0040] After mixing as described above, dry as necessary, and then treat with an inert atmosphere or hydrogen sulfide. The mixed powder is calcined under gas (H2S) flow, crushed and ground as needed, and then classified. This allows us to obtain the aforementioned compound. When firing in an atmosphere containing hydrogen sulfide gas, the firing temperature is, for example, 350°C or higher. It is preferable that it be present, and more preferably 450°C or higher. On the other hand, the above firing temperature is For example, it is preferable that the temperature is 650°C or lower, and more preferably 600°C or lower. It is even more preferable if the temperature is below 00°C. On the other hand, when firing in an inert atmosphere, the firing temperature is, for example, 350°C or higher. Preferably, the firing temperature is 550°C or lower, and 500°C is preferable. It is even more preferable that the temperature is below 450°C.

[0041] The compound particles that make up the main part are formed by amorphizing the raw material powder using a mechanical milling method. Alternatively, it can be manufactured by heat-treating the amorphous raw material powder as needed to crystallize it. In this case, as long as the raw material powder can be sufficiently mixed and amorphous, there are no special requirements for the processing equipment and processing conditions. It is not limited to this. In particular, when using a planetary ball mill, the container for filling the raw material powder moves at high speed. Because it revolves, there is a high distance between it and the balls, which are the grinding media that are placed inside the container along with the raw material powder. Impact energy is generated, making it possible to efficiently and uniformly amorphousize the raw material powder. The mechanical milling method may be either dry or wet.

[0042] The processing conditions for the mechanical milling method can be set appropriately depending on the processing device used, for example. For example, processing in a time of 0.1 hours to 100 hours would result in greater efficiency and uniformity. The raw material powder can be made amorphous. The balls used as grinding media are ZrO2, Al2O3, S The ball is preferably made of i3N4 (silicon nitride) or WC (tungsten carbide), and the ball diameter is It is preferable that the thickness be between 0.2 mm and 10 mm.

[0043] The amorphous raw material powder, obtained by mechanical milling, is subjected to the same calcination conditions as described above. The compound can be obtained by heat treatment and crystallization. The processed raw material powder is more uniformly mixed than the raw material powder obtained by conventional grinding and mixing. Therefore, it is possible to further reduce the heat treatment temperature.

[0044] Furthermore, the particles of the compound that constitute the main part can also be produced by a liquid-phase method using an organic solvent. In this case, the sulfides and halides that serve as raw materials for the compounds constituting the main part are tetrahydrofuran. By dissolving it in a solvent such as ethanol and precipitating the compound using the solvent as a reaction field, It can be obtained. Alternatively, the compounds constituting the main part can be synthesized in advance using another method, and ethanol The compound can be obtained by dissolving it in any solvent and then reprecipitation it. The liquid phase method allows for the particle formation of the main compound in a shorter time and with less energy than other methods. It is possible to manufacture these particles, and it is also relatively easy to reduce their particle size.

[0045] Once the main part, consisting of compound particles, is obtained in this way, this main part is divided into particles of an appropriate size. It is preferable to adjust the diameter. The preferred particle size of the main part can be the same as described above. Therefore, the details are omitted here.

[0046] Next, the main component and the conductive material are mixed and compounded. The conductive material to be used is as described above. Since it can be treated the same way, the description here is omitted.

[0047] The composite of the main body and the conductive material is, for example, composed of particles of the compound that make up the main body and particles of the conductive material. This is achieved by applying mechanical energy to the main body and the conductive material. It is preferable to apply compressive and impact forces, or shear and frictional forces, under these mixed conditions. It seems so.

[0048] Mechanical energy such as compressive and impact forces, shear and frictional forces are applied to the main body and conductive material in a mixed state. To compound by adding -, the powder is mainly stirred, mixed, kneaded, granulated, crushed, dispersed, and Alternatively, it is preferable to use equipment used when modifying surfaces, etc. For example, a planetary type Ball mills, jet mills, bead mills, agitator-type grinders, vibratory mills, hammer mills Mills, roller mills, and atomizers can be used. The main types of mechanical energy that can be imparted vary depending on the device, for example, planetary ball bearings When using this method, compressive and impact forces are primarily applied to the main component and conductive material in a mixed state. Therefore, both can be combined. The centrifugal acceleration obtained when the device rotates is a combination of the main part and the conductive part. While not particularly limited as long as it can be converted, it is preferable that it be 10G or more, for example. It is more preferable that it be 15G or more, and even more preferable that it be 18G or more. The centrifugal acceleration is preferably, for example, 40G or less, and more preferably 30G or less. Preferably, the centrifugal acceleration is within the above range, and more preferably, 25G or less. This makes the effects of the present invention even more remarkable.

[0049] Furthermore, the aforementioned liquid-phase method can also be used in the composite formation of the main body and the conductive material. In this case, the conductive material is first dispersed in an organic solvent, and then the particles of the compound that constitute the main part are used. By placing the material or the compound that makes up the main part into an organic solvent, the particles are formed on the surface or inside the conductive material. Compounding can be achieved by precipitation. In compounding using this method, the compounded It is possible to further reduce the particle size.

[0050] The active material of the present invention can be used to generate electricity by mixing it with an electrolyte, a conductive material, a binder, etc. It can be used as an electrode compounding agent. When the active material of the present invention is used as a positive electrode active material, the electrode compounding agent can be used. The agent becomes the positive electrode mixture that constitutes the positive electrode layer.

[0051] The electrolyte may be, for example, a solid electrolyte. Solid electrolytes have lithium ion conductivity, etc. It is preferable that it has ionic conductivity. Specifically, for example, sulfide solid electrolytes, oxidation Inorganic solid electrolytes such as polymer solid electrolytes, nitride solid electrolytes, and halogen solid electrolytes, - Examples include organic polymer electrolytes such as electrolytes. From the viewpoint of enabling this, the solid electrolyte is preferably a sulfide solid electrolyte. Regarding decomposition, it can be done in the same way as the sulfide solid electrolyte used in general solid-state batteries. Sulfide solid electrolytes include, for example, those containing Li and S and having lithium ion conductivity. That is also acceptable. 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 solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiX( "X" indicates 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 is 3.0 or greater than 9.) b represents numbers less than or equal to 0. b represents numbers between 3.5 and 6.0. c represents numbers between 0.1 and 3.0. Examples include compounds represented by (a number). In addition, for example, International Publication No. 2 Pamphlet No. 013 / 099834, International Publication No. 2015 / 001818 The sulfide solid electrolyte described in T can be used.

[0052] The active material contained in the electrode mixture may consist solely of the active material of the present invention, or it may contain other active materials. They can also be used in combination. Other active materials include known elemental sulfur and sulfur Examples of active materials included are: For example, the proportion of the active material of the present invention in the electrode mixture is 20% by mass. It may be more than 30% by mass or more, or 40% by mass or more. On the other hand, the aforementioned percentage may be, for example, 70% by mass or less, or 60% by mass or less. stomach.

[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. The system comprises a solid electrolyte layer containing the above-mentioned active material, and it is preferable that the positive electrode active material is the active material described above. The battery consists of, for example, a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, all prepared as described above, stacked in three layers. It can be manufactured by pressing and molding.

[0054] The battery of the present invention uses a positive electrode active material and a solid electrolyte to make the desired effect more pronounced. It is preferable that there is an interface in which the positive electrode active material and the solid electrolyte come into contact. "Coming into contact" means that the positive electrode active material contained in the positive electrode layer comes into contact with the solid electrolyte, and that the positive electrode layer contains Whether the positive electrode active material and the solid electrolyte contained in the solid electrolyte layer come into contact with each other To include.

[0055] The battery having the active material of the present invention is preferably a lithium-ion battery, and among them, A lithium-sulfur battery is preferred. The battery here is a solid electrolyte layer having a solid electrolyte layer. Examples include solid batteries, particularly all-solid-state batteries. Furthermore, the battery in this invention is a primary battery. Lithium-ion batteries are also acceptable, but lithium-ion batteries are preferred for use in secondary batteries. It is particularly preferable to use it in secondary batteries. A "lithium secondary battery" is a battery in which lithium ions This broadly encompasses secondary batteries that charge and discharge by moving between a positive electrode and a negative electrode.

[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. "Solid-state battery" refers to a liquid or In addition to solid batteries that do not contain any gel-like substance as an electrolyte, other types of batteries may contain, for example, 50% or less by mass, or 30% by mass. This also includes embodiments that contain a liquid or gel-like substance as an electrolyte in an amount of % or less, or 10% by mass or less. . [Examples]

[0057] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is limited to... The embodiments are not limited to those described above. Unless otherwise specified, "%" and "parts" refer to "mass%" and "parts" respectively. It means "part of mass".

[0058] [Example 1] Li shown in Table 1 5.8 PS 4.8 Cl 1.2 Lithium sulfide (L) i2S) powder, phosphorus pentasulfide (P2S5) powder, and lithium chloride (LiCl) powder Using this method, weigh each component so that the total amount is 2g, and mill using a planetary ball mill (made by Fritsch, P Using (7), the mixture was mixed and ground at 150 rpm for 20 hours to prepare a mixed powder. The combined powder is filled into a carbon container and then heated in a tubular electric furnace to produce hydrogen sulfide gas (H2S, purity While circulating 100% at 1.0 L / min, heat at a heating rate of 200°C / h, 5 It was fired at 0°C for 4 hours. After that, the sample was crushed in a mortar and pestle, then ground in a ball mill, and then opened up. Sorted using a 53 μm sieve to determine particle size D50 A powdered compound with a particle size of 3.8 μm was obtained. XRD (hereinafter also referred to as "XRD") measurement results showed that this compound has an argyrodite-type crystal structure. It was confirmed that it possesses a crystalline phase. The conductive material used is conductive carbon black manufactured by Lion Specialty Chemicals. Ketjenbrak® EC300 was used. This conductive material has a particle size of D 50 0.0 The particle size was 4 μm. 20 parts of conductive material were used for 100 parts of the compound, forming a planetary ball. The mixture was prepared using a mill (Fritsch, P-7) at 500 revolutions per minute for 10 hours. The sample was then crushed in a mortar and pestle, and sieved to a particle size of D. 50 3.2μ Particles of the positive electrode active material were obtained at m. All of the above operations are performed in a well-dried Ar gas (dew point below -60°C) The procedure was carried out inside a robe box.

[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 B r 0.8 , and Li 5.8 PS 4.8 Cl 1.2 The raw material powders are mixed to achieve the following composition. A powder of the compound was obtained in the same manner as in Example 1, except for the following. XRD measurement results showed that the obtained compound It was confirmed that it has a crystalline phase with an argyrodite-type crystal structure. For example, carbon nanotubes (manufactured by Showa Denko, VGCF(registered trademark)-H) or Example 1 Similarly, Ketjenblack was used. Note that this carbon nanotube has a fiber diameter of 150 n. It was a fiber with a length of 6 μm. In Example 4, 10 parts of Ketjenblack were used for every 100 parts of the compound. Particles of the active material were obtained in the same manner as in Example 1, except for the rest.

[0060] [Examples 5 and 6] Table 1 shows Li7PS6 and Li 7.3 P 0.9 Fe 0.1 To achieve the composition of S6 Next, weigh each of the raw material powders so that the total amount is 2g, and mill them in a planetary ball mill (fritt). Using a P-7 (manufactured by [company name]), mechanical milling was performed at 500 rpm for 20 hours. A crystalline mixed powder was prepared. Then, this amorphous mixed powder was placed in a carbon container. Fill it and heat it in a tubular electric furnace with inert gas (Ar, 100% purity) at a rate of 1.0 L / min. While being distributed, it was heated at a heating / cooling rate of 200°C / h and then baked at 400°C for 4 hours. Next, the sample was crushed in a mortar and pestle, then sieved through a 53 μm mesh sieve to obtain powders with the particle sizes shown in Table 1. A powdered compound was obtained. XRD measurement revealed that this compound has an argyrodite-type crystal structure. It was confirmed that it has a phase. Otherwise, the particles of the active material were prepared in the same manner as in Example 2. I obtained it.

[0061] [Comparative Example 1] This comparative example involves a composite of a conductive material consisting of Ketjenblack on the surface or inside of elemental sulfur particles. This is an example of producing active material particles by fermentation. Particle size D 50 For 100 parts of sulfur particles with a particle size of 35.6 μm, particle size D 50 0.04 Using 20 parts of Ketjenbrak in μm size, both were placed in a planetary ball mill in the same manner as in Example 1. Using a Fritsch P-7, the mixture was blended and compounded at 500 rpm for 10 hours. Particle size D 50 We obtained active material particles with a diameter of 28.4 μm.

[0062] [Comparative Example 2] This comparative example involves a conductive material consisting of carbon nanotubes on the surface or inside lithium sulfide particles. This is an example of manufacturing active material particles by compounding them. Particle size D 50 For 100 parts of lithium sulfide particles with a particle size of 20 μm, the particle size D 50 0. Twenty parts of 15 μm carbon nanotubes were used, and both were placed in a planetary bore in the same manner as in Example 1. Using a Lumil (made by Fritsch, P-7), the mixture was combined and compounded under conditions of 500 revolutions per minute for 10 hours. In this way, particle size D 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 on the surface and inside of the particles This is an example of manufacturing active material particles without compounding conductive materials made from Ketjenbrak. Particle size D 50 Li is 3.8 μm 5.8 PS 4.8 Cl 1.2 For 100 parts of particles Then, using 20 parts of Ketjenbrak, both were used in a planetary ball mill (free) in the same manner as in Example 1. Mixing was performed using a P-7 (manufactured by Tsch) at 200 rpm for 10 hours. Diameter 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 of Without compounding the conductive material, which consists of Ketjenblack, onto the surface or interior of the particles, the active material particles This is an example of a product that was manufactured. Particle size D 50 Li is 3.8 μm 5.8 PS 4.8 Cl 1.2 For 100 parts of particles Then, using 20 parts of Ketjenbrak, both were used in a planetary ball mill (free) in the same manner as in Example 1. Mixing was performed using a P-7 (manufactured by Tsch) at 300 rpm for 1 hour. The resulting particle size was then determined. 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 not compounded with a conductive material. This is an example of using it as an active material.

[0066] [Measurement of elemental composition] The powder of the main compound obtained in the examples and comparative examples was completely dissolved and subjected to ICP emission spectroscopy analysis. The elemental composition was measured according to the law. The results were in general agreement with the mixing ratio of the raw material compounds used in the preparation. This was confirmed. Similarly, the lithium content of the active material obtained in the examples and comparative examples was confirmed. The quantity was measured.

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

[0068] [XRD measurement] The positive electrode active material powder obtained in the examples and comparative examples was subjected to a well-dried Ar gas (dew point -6 Fill an airtight holder that is not exposed to the atmosphere inside a glove box that has been replaced with a temperature below 0°C. XRD measurements were performed. The XRD measurements identified the generated phase, as well as the argyrodite. The peak located at 2θ = 29.62° ± 1.0° in the type crystal phase (hereinafter referred to as "peak A") The full width at half maximum (FWHM) was calculated. The measurement conditions for XRD 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 compound powders and cathode active material powders obtained in the examples and comparative examples are used in lasers. - Automatic sample feeder for diffraction particle size distribution analyzer (Microtrac-Bell Co., Ltd. "Mi Using "crotorac SDC", the sample (powder) was placed in an aqueous solvent and 40% After irradiating the flow with 40W ultrasound multiple times for 360 seconds, Microtrac Bell Co., Ltd. The particle size distribution was measured using the company's laser diffraction particle size distribution analyzer "MT3000II" and obtained From the volume-based particle size distribution chart, particle size D 50 We measured it.

[0070] [Ionic conductivity] The powder of the main compound obtained in the examples and comparative examples was thoroughly dried with Ar gas ( Uniaxial compression molding is performed in a glove box with a dew point of -60°C or lower, and then further CIP (cold injection molding). Using an isostatic pressurizing device, the material is compressed at 200 MPa to form pellets with a diameter of 10 mm and a thickness of approximately 4-5 mm. A pellet was prepared. After applying carbon paste as electrodes to both the top and bottom surfaces of the pellet, The samples were then heat-treated at 180°C for 30 minutes to prepare samples for ionic conductivity measurement. The conductivity (S / cm) was measured at room temperature (25°C) using a solar meter manufactured by Toyo Technica Co., Ltd. Using the N1255B, under the condition of a measurement frequency of 0.1Hz to 1MHz, the AC impedance method was used. Measured at [location / location].

[0071] [Observation of active material particles and elemental mapping] The positive electrode active material powders obtained in the examples and comparative examples were subjected to an energy-dispersive X-ray spectrometer. Observation using a scanning electron microscope (SEM-EDS) revealed that the main constituent elements of the compound are The sulfur element is mapped to the constituent elements of the conductive material, and the sulfur element of the compound and the constituent elements of the conductive material are mapped. The state of composite formation was confirmed by measuring the state of existence of the elements. Furthermore, after fabricating the batteries described below using the active materials obtained in the examples and comparative examples, the positive voltage of the batteries was measured. The polar cross-section was observed in the same manner as described above, and the sulfur element of the compound and the conductor were found on the surface and inside the active material. By measuring the state of existence of constituent elements in the electrical material, the state of composite formation in the battery can be confirmed. did.

[0072] [Battery evaluation] Using the active materials obtained in the examples and comparative examples as positive electrode active materials, a solid-state battery was constructed according to the following procedure. The solid-state batteries were fabricated. The initial capacity and rate characteristics of the fabricated batteries were evaluated using the following procedure. The results are shown in Tables 1 and 2 below.

[0073] <Fabrication of All-Solid-State Battery Cells> Using the materials prepared in the examples and comparative examples as the positive electrode active material, in the positive electrode layer and the solid electrolyte layer As the solid electrolyte powder used, Li having an argyrodite-type crystal structure 5.4 PS 4.4 C l 0.8 Br 0.8 , an all-solid-state battery was fabricated using In-Li metal as the negative electrode active material of the negative electrode layer fabricated. (Preparation of Positive Electrode Composite) The positive electrode composite powder for the positive electrode layer was prepared by mixing the positive electrode active material powder obtained in the examples and comparative examples and the solid electrolyte powder in a mass ratio of 60:40 in a mortar. In Comparative Example 4, , since it is a positive electrode active material powder not compounded with a conductive material, the positive electrode active material powder, the solid electrolyte powder powder, and the above-mentioned carbon nanotube as a conductive material for imparting conductivity to the positive electrode layer were prepared by mixing in a mortar at a mass ratio of 50:40:10.

[0074] (Fabrication of All-Solid-State Battery Cells) The lower opening of a polypropylene cylinder with openings at the top and bottom (opening diameter 10.5 mm, height 18 mm) was closed with a negative electrode (made of SUS), and the solid electrolyte powder was placed on it, and after closing with a positive electrode (made of S US), a solid electrolyte layer was formed by uniaxially pressing at 200 MPa . Next, once the positive electrode was removed, the positive electrode composite powder was placed on the solid electrolyte layer and closed again with the positive electrode , and then uniaxially pressed at 560 MPa to laminate the positive electrode layer and the solid electrolyte layer. Then , the cylinder was inverted, the negative electrode was removed once, an In-Li foil was placed on the solid electrolyte layer and closed again with the negative electrode, and finally, the space between the positive and negative electrodes was loaded with a load of 6 N·m using a vice By sandwiching them together, an all-solid-state battery cell is formed in which a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are stacked. The following was fabricated: The thickness of each layer was approximately 40 μm for the positive electrode layer and approximately 600 μm for the solid electrolyte layer. The negative electrode layer is approximately 400 μm thick. The all-solid-state battery cell is fabricated using aluminum with a dew point temperature of -60°C. The experiment was conducted inside a glove box filled with gas. The fabricated all-solid-state battery was kept at 25°C. The battery characteristics were evaluated by connecting it to a charge / discharge measurement device in a sagging environmental testing chamber. A current of 2.0mA was defined as the 1C rate.

[0075] [Initial capacity] During the initial charge / discharge (first cycle), lithium ions contained within the positive electrode active material are efficiently removed. For the purpose of storage, it was charged to 3.0V at 0.03C using the CC-CV method, and then at 0.03C The battery was discharged using the CC method down to 0.38V. In the second cycle, it was discharged to 3.0V at 0.1C using the CC-C method. It was charged using the V method and discharged using the CC method at 0.1C down to 0.38V. This is the second cycle. The charge / discharge capacity was defined as the initial charge / discharge capacity. Note that the active sulfur composite of elemental sulfur and conductive material in Comparative Example 1 was used. In terms of materials, since the active material does not contain lithium elements, the first cycle is discharged. Then it started.

[0076] [Rate characteristics] Perform the third charge / discharge cycle using the method described above, and from the fourth cycle onward, 0.2C, 0 Charge and discharge at rates of 0.5C, 1C, 2C, and 5C, and calculate the discharge capacity for each rate over two cycles. The rate characteristics were evaluated by comparing them with the discharge capacity (0.1C) in the eye.

[0077] [Table 1]

[0078] [Table 2]

[0079] As is clear from the results shown in Tables 1 and 2, the active material of each example can be used as the positive electrode active material. The all-solid-state battery was found to have superior initial capacity and rate characteristics compared to the comparative example. In particular, Examples 1 and 3, in which the conductive part contains Ketjenblack, and the conductive part contains carbon As is clear from the comparison with Examples 2, 3, 5 and 6 which include Notube, Examples 1 and 3 This indicates that the battery has a higher discharge rate characteristic. In other words, the conductive part is Ketjenbrak It has been found that including this improves the battery's discharge rate characteristics. Comparative Example 1, which used elemental sulfur as the main component, had a high initial volume but poor rate characteristics. This is because elemental sulfur has such low lithium-ion conductivity that it cannot be measured. Therefore, even if the discharge current is increased and the rate is raised, lithium ions will not remain in elemental sulfur. The inventors speculate that this is because it cannot be absorbed quickly. The active material obtained in each example was analyzed by elemental mapping using SEM-EDS. It has been confirmed that sulfur and carbon elements exist in an overlapping manner on the surface and within the material. It was done.

[0080] Figures 1, 2, 3, and 10 are prepared according to Example 1, Example 5, Comparative Example 3, and Comparative Example 10, respectively. In an all-solid-state battery using the manufactured positive electrode active material, the charge-discharge rates are set to 0.1C, 0.2C, and 0 The charge-discharge curves when the current is varied to 0.5C, 1C, 2C, and 5C are shown. These curves were prepared in Examples 1 and 5. In all-solid-state batteries using the manufactured positive electrode active material, high discharge rate is maintained even when the charge / discharge rate is increased. The capacity is shown, but in all-solid-state batteries using the positive electrode active material prepared in Comparative Examples 3 and 4 In this case, increasing the charge / discharge rate significantly reduces the discharge capacity. This is especially true in Comparative Examples 3 and 4. Although the main component is a powder of the same compound as in Example 1, the initial volume and The discharge rate characteristics are significantly inferior compared to Example 1. This is because the material used in Comparative Example 3 is... Under the conditions of a planetary ball mill used when compound powders have a large particle size and undergo compounding treatment, Due to a low rotational speed, the conductive material does not disperse uniformly on the surface and inside the compound particles, The inventors surmise that the material failed to exhibit its performance as an extremely active material.

[0081] Figures 4 and 5 show SEM images of the appearance of the cathode active material powder prepared in Example 5 and Comparative Example 4. The image shows the mapping of the carbon and sulfur element states using EDS. The compositions of the compounds used in Example 5 and Comparative Example 4 are the same. The positive electrode activity prepared in Example 5 The carbon element, which is a conductive material component of the material powder, and the sulfur element, which is a component of the compound, are located in an overlapping manner. The presence of these particles confirmed 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 a conductive material component, is compounded Because the sulfur element is located in a different position from the other element, the positive electrode active material prepared in Comparative Example 4 is a compound It was confirmed that the particles of the material and the conductive material were not compounded, but simply mixed together. Ta.

[0082] Figures 6 and 7 show all-solid-state batteries using the positive electrode active material powder prepared in Example 5 and Comparative Example 4. The cross-section was prepared by machining with a cross-section polisher (CP), followed by SEM observation and ED observation. This map shows the states of existence of carbon, sulfur, and bromine elements using S. In the cross-section of the all-solid-state battery using the positive electrode active material powder prepared in Example 5, the conductive material component is carbon The ideal location for this is where bromine, a component of solid electrolytes, is absent, and sulfur is abundant. Due to its location, the conductive material is uniformly compounded on the surface and inside the compound particles. It was confirmed that this was the case. On the other hand, all-solid-state battery using the positive electrode active material powder prepared in Comparative Example 4 In the cross-section, the carbon element, which is a conductive material component, is located where the bromine element, which is a component of the compound, is present. Furthermore, because they exist around areas with high concentrations of sulfur, conductive materials are compound particles. It is not compounded, but simply a mixture of compound powder and conductive material powder. This was confirmed.

[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 part and the conductive part in a mixed state are combined using a planetary ball mill... Furthermore, due to the adoption of high rotational speed conditions to impart high centrifugal acceleration, the main part and the conductive High mechanical energy is applied to the part, and the two become combined. During the combination, the argilla While maintaining the dite-type crystalline phase, the crystalline phase becomes moderately low in crystallinity, resulting in argyrodite. The broadening of the full width at half maximum of each diffraction peak attributed to the type crystal phase is shown in Figure 8 of the XRD results. This was confirmed from the folding pattern and the half-width 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. Comparative Example 3 In and 4, when the main part and the conductive part in a mixed state are combined using a planetary ball mill, low rotation Due to the adoption of the number of rotations condition, the centrifugal acceleration that is applied is insufficient, High mechanical energy was not applied to the conductive part, and the two did not sufficiently combine. It can be confirmed from the XRD diffraction pattern shown in Fig. 9 and the half-value widths shown in Table 3 below that the crystallinity of the aldirodite-type crystal phase contained in the main part is maintained in a high state.

[0085] [Table 3] [Industrial Applicability]

[0086] As described in detail above, according to the active material of the present invention, the performance of the lithium-ion battery can be improved. This is possible.

Claims

1. A method for producing an active material, Lithium (Li) element, sulfur (S) element, and M element (where M is phosphorus (P), germanium Metal (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al ), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co), and manganese ( It is at least one of the elements (Mn), and contains at least phosphorus (P) and iron (Fe). The first step is to prepare a compound containing a crystalline phase having an argyrodite-type crystal structure, and 、 The process includes a second step of mixing the compound with a conductive material to form a composite. A method for producing active material.

2. In the second step, mechanical energy is applied to the compound and the conductive material to form a composite. The manufacturing method according to claim 1.

3. In the X-ray diffraction pattern measured using the CuKα1 line, 2θ = 29.62 ± 1. The second step is performed such that the full width at half maximum of the peak located at 0° is 0.4° or more, according to the claim. The manufacturing method described in 1 or 2.

4. In the second step, 1 to 50 parts by mass of the above compound are added to 100 parts by mass of the above compound. A manufacturing method according to any one of claims 1 to 3, comprising mixing the conductive material.

5. The aforementioned compound is measured by a laser diffraction scattering particle size distribution method at a cumulative volume of 50% by volume. Volume cumulative particle size D ５０ Any of claims 1 to 4, wherein the particle size is 0.1 μm or more and 20 μm or less. The manufacturing method described in item 1.

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

7. The aforementioned compound has the compositional formula Li ａ MS ｂ X ｃ (In the formula, M is phosphorus (P) and germanium (G) e) Antimony (Sb), Silicon (Si), Tin (Sn), Aluminum (Al), Chi Tungsten (Ti), iron (Fe), nickel (Ni), cobalt (Co), and manganese (Mn) It is at least one of the following elements, and contains at least phosphorus (P) and iron (Fe). This is selected from fluorine (F), chlorine (Cl), bromine (Br), and iodine (I) It is also a type of element. a is between 3.0 and 9.0, and b is between 3.5 and 6.

0. The manufacturing method according to claim 6, wherein 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. method.

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

10. Lithium (Li) element, sulfur (S) element, and M element (where M is phosphorus (P), germanium Metal (Ge), antimony (Sb), silicon (Si), tin (Sn), aluminum (Al ), titanium (Ti), iron (Fe), nickel (Ni), cobalt (Co), and manganese ( It is at least one of the elements (Mn), and contains at least phosphorus (P) and iron (Fe). A compound containing a crystalline phase having an argyrodite-type crystal structure, Having a conductive material, An active material which is a composite material of the compound and the conductive material.

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

12. In the X-ray diffraction pattern measured using the CuKα1 line, 2θ = 29.62 ± 1. The full width at half maximum of the peak located at 0° is 0.4° or more, according to claim 10 or 11. active material.

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

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

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 content of the lithium element in the compound is 10% by mass or more and 25% by mass or less. The active material described in any one of the requirements 10 to 16.

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

19. A material comprising the active material according to any one of claims 10 to 18 and a sulfide solid electrolyte, Electrode mixture.

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. There is, The positive electrode layer contains the active material described in any one of claims 10 to 18, 。

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