All-solid-state batteries

Abstract

To provide, as a main purpose, an all-solid battery capable of suppressing a binding pressure fluctuation caused by an expansion / constriction of a Si-based active material.SOLUTION: In a present disclosure, an all-solid battery includes: a positive electrode active material layer; a solid electrolyte layer; and a negative electrode active material layer in this order. The negative electrode active material layer includes: a Si-based active material; and a sulfide solid electrolyte. A mean particle diameter (D50) of the Si-based active material is 100nm or more and 800nm or less. The sulfide solid electrolyte includes a peak at a position between 415 cm-1 and 425 cm-1 inclusive in a Raman spectral spectrum. A half value width of the peak is 15.5 cm-1 or more and 20.0 cm-1 or less. With respect to a total of the Si-based active material and the sulfide solid electrolyte, a volume rate of the Si-based active material is 1 vol% or more and 65 vol% or less, and a volume ratio of the sulfide solid electrolyte is 35 vol% or more and 99 vol% or less. The problem to be solved described in the present disclosure is solved by providing the all-solid battery.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to all-solid-state batteries. [Background technology]

[0002] All-solid-state batteries are batteries that have a solid electrolyte layer between a positive electrode active material layer and a negative electrode active material layer, and have the advantage that safety devices can be more easily simplified compared to liquid-based batteries that have an electrolyte solution containing a flammable organic solvent.

[0003] Patent Document 1 discloses a negative electrode active material for a secondary battery, which comprises a Si-oxide solid electrolyte composite including a matrix made of an amorphous or low-crystalline oxide solid electrolyte and Si nanoparticles dispersed in the matrix. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-239267 Summary of the Invention [Problem to be solved by the invention]

[0005] Although Si-based active materials have good capacity characteristics, they tend to undergo large volume changes during charge and discharge. When such Si-based active materials are used as negative electrode active materials for all-solid-state batteries, path disconnection (disconnection of ionic and electronic conduction paths) occurs in the negative electrode active material layer during charge and discharge, which can result in a decrease in battery performance. Furthermore, all-solid-state batteries are typically subjected to a confining pressure to achieve good battery performance. To prevent this, it is desirable for the fluctuations in confining pressure caused by the expansion and contraction of the Si-based active material to be small.

[0006] The present disclosure has been made in view of the above circumstances, and has as its main object to provide an all-solid-state battery capable of suppressing fluctuations in confining pressure caused by expansion and contraction of a Si-based active material. [Means for solving the problem]

[0007] In order to solve the above problems, the present disclosure provides an all-solid-state battery having a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer, wherein the negative electrode active material layer has a Si-based active material and a sulfide solid electrolyte, and the average particle size (D 50 ) is 100 nm or more and 800 nm or less, and the sulfide solid electrolyte has a Raman spectrum of 415 cm -1 Over 425cm -1 The peak has a half-width of 15.5 cm -1 More than 20.0cm -1 the volume ratio of the Si-based active material to the total of the Si-based active material and the sulfide solid electrolyte is 1% by volume or more and 65% by volume or less, and the volume ratio of the sulfide solid electrolyte to the total of the Si-based active material and the sulfide solid electrolyte is 35% by volume or more and 99% by volume or less.

[0008] According to the present disclosure, the negative electrode active material layer contains a Si-based active material having a predetermined average particle size and a sulfide solid electrolyte having low crystallinity identified from a peak in a Raman spectroscopy spectrum in a predetermined ratio, thereby providing an all-solid-state battery that can suppress fluctuations in confining pressure caused by expansion and contraction of the Si-based active material.

[0009] In the above disclosure, the sulfide solid electrolyte is PS4 3- The peak contains the structure PS4 3- It may be a peak of the structure.

[0010] In the above disclosure, the sulfide solid electrolyte may contain at least Li, P, and S.

[0011] In the above disclosure, the sulfide solid electrolyte may contain a halogen.

[0012] In the above disclosure, the sulfide solid electrolyte may have a lithium ion conductivity at 25° C. of 1.5 mS / cm or more and 3.5 mS / cm or less. [Effects of the Invention]

[0013] The all-solid-state battery according to the present disclosure has an effect of being able to suppress fluctuations in confining pressure caused by expansion and contraction of the Si-based active material. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating an example of an all-solid-state battery according to the present disclosure. [Figure 2] 1 is a graph showing the results of confining pressure fluctuations in Examples 1 to 12. [Figure 3] 10 is a graph showing the results of confining pressure fluctuations in Comparative Examples 1 to 14. [Figure 4] 10 is a graph showing the results of confining pressure fluctuations in Example 10 and Comparative Example 14. DETAILED DESCRIPTION OF THE INVENTION

[0015] The all-solid-state battery of the present disclosure will be described in detail below with reference to the drawings. Each of the drawings shown below is a schematic illustration, and the size and shape of each part are appropriately exaggerated for ease of understanding. Furthermore, in each of the drawings, hatching indicating the cross section of a component is appropriately omitted. Furthermore, in this specification, when expressing the arrangement of another component relative to a component, the term "above" or "below" simply refers to both the case where another component is arranged directly above or below the component so as to be in contact with the component, and the case where another component is arranged above or below the component via another component, unless otherwise specified.

[0016] Fig. 1 is a schematic cross-sectional view illustrating an example of an all-solid-state battery according to the present disclosure. The all-solid-state battery 10 shown in Fig. 1 includes, in this order, an anode current collector 1, an anode active material layer 2, a solid electrolyte layer 3, a cathode active material layer 4, and a cathode current collector 5. In the present disclosure, the anode active material layer 2 contains a Si-based active material and a sulfide solid electrolyte, which will be described later, in predetermined proportions.

[0017] According to the present disclosure, an all-solid-state battery is obtained in which the negative electrode active material layer contains a Si-based active material having a predetermined average particle size and a sulfide solid electrolyte having low crystallinity as determined from a peak in a Raman spectroscopy spectrum in a predetermined ratio, thereby suppressing fluctuations in confining pressure due to expansion and contraction of the Si-based active material. Here, the sulfide solid electrolyte has a peak at a predetermined position in a Raman spectroscopy spectrum obtained by Raman spectroscopy measurement. Furthermore, the half-width of the predetermined peak is within a predetermined range. The half-width of the Raman spectroscopy peak is related to the crystallinity of the sulfide solid electrolyte, and the lower the crystallinity, the larger the half-width. In this specification, 415 cm -1 Over 425cm -1 The peak has a half-width of 15.5 cm -1 More than 20.0cm -1 Hereinafter, the sulfide solid electrolyte will also be referred to as a "low-crystalline sulfide solid electrolyte."

[0018] The low-crystalline sulfide solid electrolyte has a lower proportion of crystalline phase than a highly crystalline sulfide solid electrolyte, and therefore can follow the expansion and contraction of the Si-based active material. As a result, when the Si-based active material expands and contracts, the volume change in the entire negative electrode active material layer can be reduced, and fluctuations in the confining pressure can be suppressed. Furthermore, since the Si-based active material in the present disclosure has a small average particle size, fluctuations in the confining pressure can be further suppressed.

[0019] 1.Negative electrode The negative electrode of the present disclosure has a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer contains a negative electrode active material having a predetermined average particle size (D 50The negative electrode active material layer may further contain at least one of a conductive material and a binder.

[0020] (1)Si-based active material The negative electrode active material layer may be made of a Si-based active material. The Si-based active material is an active material containing Si element. Examples of the Si-based active material include simple Si, Si alloys, and Si oxides. The Si alloy preferably contains Si element as a main component.

[0021] The shape of the Si-based active material is usually particulate. 50 ) is usually 100 nm or more, and may be 400 nm or more, or may be 470 nm or more. On the other hand, the average particle diameter (D 50 The average particle size (D) of the Si-based active material is usually 800 nm or less, and may be 700 nm or less, or may be 630 nm or less. 50 If the average particle size (D 50 ) can be calculated, for example, from measurements using a laser diffraction particle size distribution analyzer or a scanning electron microscope (SEM).

[0022] In the negative electrode active material layer, the volume ratio of the Si-based active material to the total of the Si-based active material and the low-crystalline sulfide solid electrolyte is typically 1% by volume or more, and may be 20% by volume or more, or 50% by volume or more. On the other hand, the volume ratio of the Si-based active material is typically 65% ​​by volume or less, and may be 60% by volume or less, or may be 55% by volume or less. If the volume ratio of the Si-based active material is too high, it is difficult to obtain the effect of suppressing the confining pressure fluctuation.

[0023] The proportion of the negative electrode active material in the negative electrode active material layer is, for example, 20% by weight or more, or alternatively, 40% by weight or more, or even 60% by weight or more, while the proportion of the negative electrode active material is, for example, 80% by weight or less.

[0024] (2)Low crystalline sulfide solid electrolyte The negative electrode active material layer according to the present disclosure contains a sulfide solid electrolyte having low crystallinity as determined from a peak in a Raman spectrum. -1 Over 425cm -1 This peak is due to the PS4 contained in the low-crystalline sulfide solid electrolyte. 3- This is a peak derived from the structure.

[0025] The full width at half maximum (FWHM) of the above peak is typically 15.5 cm -1 More than 16.0cm -1 It may be more than 16.5cm -1 It may be more than 17.0cm -1 If the half-value width is too small, it is difficult to obtain the effect of suppressing the confining pressure fluctuation. On the other hand, the half-value width of the above peak is usually 20.0 cm or more. -1 Less than or equal to 18.0 cm -1 The half-width may be less than 1 / 2. If the half-width is too large, the ionic conductivity is likely to decrease. As the device for Raman spectroscopy, a commercially available Raman spectrophotometer (for example, NRS-3100 manufactured by JASCO Corporation) can be used. The measurement conditions are, for example, an excitation laser wavelength of 532 nm, a resolution of 4 cm, and the like. -1 The light attenuation rate is preferably 0.6, and the exposure time is preferably 120 seconds. The number of measurements is, for example, about 5 times.

[0026] Low-crystalline sulfide solid electrolyte is PS4 3- Low-crystalline sulfide solid electrolytes contain anion structures containing P and S (e.g., PS4 3- Structure, P2S6 4- Structure, P2S7 4- As the main component of PS4 3- In the low-crystalline sulfide solid electrolyte, it is preferable to have a PS4 structure for all anion structures containing P and S. 3- The proportion of the structure is, for example, 50 mol % or more, or may be 70 mol % or more, or may be 90 mol % or more.

[0027] The low-crystalline sulfide solid electrolyte preferably contains at least Li, P, and S. The low-crystalline sulfide solid electrolyte may further contain a halogen such as F, Cl, Br, or I. Among them, the low-crystalline sulfide solid electrolyte preferably further contains at least one of Br and I.

[0028] The low-crystalline sulfide solid electrolyte may have a composition represented by xLiI·yLiBr·z(αLi2S·(1-α)P2S5). Here, x + y + z = 100, 0 ≦ x < 100, 0 ≦ y < 100, 0 < z ≦ 100, 0.70 ≦ α ≦ 0.80. x may be greater than 0. In this case, x may be 5 or more, and may be 10 or more. Also, x may be 50 or less, and may be 30 or less. Also, y may be greater than 0. In this case, y may be 5 or more, and may be 10 or more. Also, y may be 50 or less, and may be 30 or less. z may be 50 or more, and may be 60 or more. α may be 0.72 or more, and may be 0.74 or more. On the other hand, α may be 0.78 or less, and may be 0.76 or less.

[0029] The low-crystalline sulfide solid electrolyte may contain O, or may not contain O. In the former case, the proportion of O contained in the low-crystalline sulfide solid electrolyte is preferably less than the proportion of S contained in the low-crystalline sulfide solid electrolyte.

[0030] The low-crystalline sulfide solid electrolyte may have a crystal phase A having peaks at positions of 2θ = 20.2° ± 0.5° and 23.6° ± 0.5° in X-ray diffraction measurement using CuKα radiation. The crystal phase A is a crystal phase with high Li ion conductivity. The crystal phase A may have peaks at positions of 2θ = 29.4° ± 0.5°, 37.8° ± 0.5°, 41.1° ± 0.5°, and 47.0° ± 0.5°, depending on its crystallinity.

[0031] The low-crystalline sulfide solid electrolyte preferably does not have crystalline phase B, which has peaks at 2θ=21.0°±0.5 and 28.0°±0.5 in X-ray diffraction measurement using CuKα radiation. Crystalline phase B is a crystalline phase having lower Li ion conductivity than crystalline phase A. Crystalline phase B may have peaks at 2θ=32.0°±0.5°, 33.4°±0.5°, 38.7°±0.5°, 42.8°±0.5°, and 44.2°±0.5°, depending on its crystallinity.

[0032] The intensity of the peak at 2θ = 20.2° ± 0.5° is calculated as I 20.2 The intensity of the peak at 2θ = 21.0° ± 0.5° is defined as I 21.0 I 21.0 / I 20.2 is, for example, 0.4 or less, may be 0.2 or less, may be 0.1 or less, or may be 0.

[0033] The low-crystalline sulfide solid electrolyte has a lithium ion conductivity at 25° C. of, for example, 1.5 mS / cm or more, or alternatively, 2.0 mS / cm or more, or 2.4 mS / cm or more. On the other hand, the lithium ion conductivity is, for example, 3.5 mS / cm or less, or alternatively, 3.2 mS / cm or less.

[0034] The low-crystalline sulfide solid electrolyte in the present disclosure is usually in the form of particles. The average particle size (D 50 ) is, for example, 40 μm or less, may be 10 μm or less, or may be 5 μm or less. On the other hand, the average particle size is, for example, 0.01 μm or more, and may be 0.1 μm or more.

[0035] In the negative electrode active material layer, the volume ratio of the low-crystalline sulfide solid electrolyte to the total of the Si-based active material and the low-crystalline sulfide solid electrolyte is typically 35% by volume or more, and may be 40% by volume or more, or even 45% by volume or more. If the volume ratio of the low-crystalline sulfide solid electrolyte is too small, it is difficult to obtain the effect of suppressing the confining pressure fluctuation. On the other hand, the volume ratio of the low-crystalline sulfide solid electrolyte is typically 99% by volume or less, and may be 80% by volume or less, or even 60% by volume or less.

[0036] The proportion of the low-crystalline sulfide solid electrolyte in the negative electrode active material layer is, for example, 20% by weight or more, or alternatively, 40% by weight or more, or even 60% by weight or more, while the proportion of the low-crystalline sulfide solid electrolyte is, for example, 80% by weight or less.

[0037] The low-crystalline sulfide solid electrolyte can be produced by heat-treating an amorphous precursor. The amorphous precursor can be obtained, for example, by amorphous treatment of a raw material composition. The raw material composition preferably contains, for example, Li2S and P2S5. The raw material composition may further contain one or more LiX (X is a halogen). Examples of amorphous treatments include mechanical milling and melt quenching.

[0038] Furthermore, the amorphous precursor may be subjected to a micronization treatment before being subjected to a heat treatment. In the micronization treatment, wet pulverization using a dispersion medium is preferably performed. Examples of the dispersion medium include ethers and mixed dispersion mediums containing ethers. Examples of the ethers include chain ethers such as dibutyl ether, diethyl ether, and dimethyl ether, and cyclic ethers such as tetrahydrofuran. Examples of the pulverization method include a bead mill and a planetary ball mill.

[0039] By heat-treating an amorphous precursor, a sulfide solid electrolyte having low crystallinity is produced while crystallizing the sulfide solid electrolyte. The heating temperature is, for example, 120°C or higher, and may be 150°C or higher. Alternatively, it is, for example, 180°C or lower. The heat treatment time is, for example, 3 hours or more and 5 hours or less. The heating atmosphere is preferably a reduced pressure atmosphere (for example, 500 Pa or lower). A general heating furnace can be used as the heating means.

[0040] (3) Negative electrode The negative electrode active material layer may contain a conductive material. Examples of the conductive material include carbon materials, metal particles, and conductive polymers. Examples of the carbon material include particulate carbon materials such as acetylene black (AB) and ketjen black (KB), and fibrous carbon materials such as carbon fibers, carbon nanotubes (CNT), and carbon nanofibers (CNF).

[0041] The negative electrode active material layer may contain a binder, such as a fluoride-based binder, a polyimide-based binder, or a rubber-based binder.

[0042] The negative electrode active material layer can be formed, for example, by preparing a slurry containing a Si-based active material, a low-crystalline sulfide solid electrolyte, and a dispersion medium, applying the slurry to a negative electrode current collector, and drying the slurry. The method for applying the slurry is not particularly limited, and any known application method can be used.

[0043] The negative electrode current collector is a layer that collects current from the negative electrode active material layer. Examples of the negative electrode current collector include SUS, copper, nickel, and carbon. The negative electrode current collector may be in the form of, for example, a foil.

[0044] 2. Positive electrode The positive electrode in the present disclosure has a positive electrode active material layer and a positive electrode current collector. The positive electrode active material layer is a layer containing at least a positive electrode active material. The positive electrode active material layer may also contain at least one of a solid electrolyte, a conductive material, and a binder, as necessary.

[0045] Examples of the positive electrode active material include oxide active materials, such as LiCoO2, LiMnO2, LiNiO2, LiVO2, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, etc., rock salt layered active materials, LiMn2O4, Li4Ti5O 12 , Li(Ni 0.5 Mn 1.5 )O4, and olivine type active materials such as LiFePO4, LiMnPO4, LiNiPO4, and LiCoPO4.

[0046] A protective layer containing a Li-ion conductive oxide may be formed on the surface of the oxide active material. This is because it can suppress the reaction between the oxide active material and the solid electrolyte. An example of the Li-ion conductive oxide is LiNbO3. The thickness of the protective layer is, for example, 1 nm or more and 30 nm or less. Furthermore, Li2S, for example, can also be used as the positive electrode active material.

[0047] The positive electrode active material may be in the form of particles, for example. 50 ) is not particularly limited, but may be, for example, 10 nm or more, or may be 100 nm or more. On the other hand, the average particle diameter (D 50 ) is, for example, 50 μm or less, and may be 20 μm or less.

[0048] The conductive material and binder used in the positive electrode active material layer are the same as those described in "1. Negative electrode" above, and therefore will not be described here. The solid electrolyte used in the positive electrode active material layer is the same as that described in "3. Solid electrolyte layer" below, and therefore will not be described here. The thickness of the positive electrode active material layer is, for example, 0.1 μm or more and 1000 μm or less.

[0049] The positive electrode current collector is a layer that collects current from the positive electrode active material layer. Examples of the positive electrode current collector include SUS, aluminum, nickel, iron, titanium, and carbon. Examples of the shape of the positive electrode current collector include foil.

[0050] 3.Solid electrolyte layer The solid electrolyte layer in the present disclosure is a layer disposed between the positive electrode active material layer and the negative electrode active material layer and containing at least a solid electrolyte. Examples of the solid electrolyte include inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and halide solid electrolytes. The solid electrolyte layer preferably contains a sulfide solid electrolyte as the solid electrolyte. When a sulfide solid electrolyte is used, it may be the low-crystalline sulfide solid electrolyte described above, or a sulfide solid electrolyte other than the low-crystalline sulfide solid electrolyte described above.

[0051] The sulfide solid electrolyte contained in the solid electrolyte layer typically contains Li and S. Preferably, the sulfide solid electrolyte further contains at least one of P, Ge, Sn, and Si. The sulfide solid electrolyte may also contain O and at least one of halogen elements (e.g., F, Cl, Br, and I).

[0052] Examples of sulfide solid electrolytes contained in the solid electrolyte layer include Li2S-P2S5, Li2S-P2S5-GeS2, Li2S-P2S5-SnS2, Li2S-P2S5-SiS2, Li2S-P2S5-LiI, Li2S-P2S5-LiI-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, and Li2S-P2S5-Z. m S n (where m and n are positive numbers. Z is Ge, Zn, or Ga.), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Lix MO y (where x and y are positive numbers, and M is any of P, Si, Ge, B, Al, Ga, and In.) The above description of "Li2S-P2S5" means a material obtained using a raw material composition containing Li2S and P2S5, and the same applies to other descriptions.

[0053] The solid electrolyte contained in the solid electrolyte layer may be glass, glass ceramics, or a crystalline material. Glass can be obtained by amorphous processing of a raw material composition (e.g., a mixture of Li2S and P2S5). Examples of amorphous processing include mechanical milling. Mechanical milling may be dry mechanical milling or wet mechanical milling, with the latter being preferred. This is because it can prevent the raw material composition from adhering to the wall surface of a container or the like. Glass ceramics can be obtained by heat treating glass. Crystalline materials can be obtained, for example, by solid-phase reaction processing of the raw material composition.

[0054] The solid electrolyte contained in the solid electrolyte layer is preferably in the form of particles. 50 On the other hand, the average particle diameter (D 50 ) is, for example, 10 μm or less, and may be 5 μm or less. The Li ion conductivity of the solid electrolyte at 25° C. is, for example, 1×10 -4 S / cm or more, 1×10 -3 It is preferably S / cm or more.

[0055] The content of the solid electrolyte in the solid electrolyte layer is, for example, 70% by weight or more, and may be 90% by weight or more. The solid electrolyte layer may contain a binder as needed. The binder is the same as that described above in "1. Negative electrode," and therefore will not be described here. The thickness of the solid electrolyte layer is, for example, 0.1 μm or more. On the other hand, the thickness of the solid electrolyte layer is, for example, 300 μm or less, and may be 100 μm or less.

[0056] 4.All-solid-state battery The all-solid-state battery of the present disclosure has at least one power generation unit having a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, and may have two or more. When the all-solid-state battery has multiple power generation units, they may be connected in parallel or in series. The all-solid-state battery of the present disclosure includes an exterior body that houses a positive electrode, a solid electrolyte layer, and a negative electrode. The type of the exterior body is not particularly limited, but examples include laminate exterior bodies. In addition, it is preferable that the all-solid-state battery does not contain an electrolyte solution.

[0057] The all-solid-state battery of the present disclosure may have a confining jig that applies a confining pressure to the positive electrode, the solid electrolyte layer, and the negative electrode in the thickness direction. By applying the confining pressure, good ionic conduction paths and electron conduction paths are formed. The confining pressure is, for example, 0.1 MPa or more, or may be 1 MPa or more, or may be 5 MPa or more. On the other hand, the confining pressure is, for example, 100 MPa or less, or may be 50 MPa or less, or may be 20 MPa or less.

[0058] The all-solid-state battery in the present disclosure is typically an all-solid-state lithium-ion secondary battery. Applications of the all-solid-state battery are not particularly limited, and examples include power sources for vehicles such as hybrid automobiles, electric automobiles, gasoline-powered automobiles, and diesel-powered automobiles. It is particularly preferred that the all-solid-state battery be used as a driving power source for hybrid automobiles or electric automobiles. The all-solid-state battery in the present disclosure may also be used as a power source for mobile objects other than vehicles (e.g., trains, ships, and aircraft), or as a power source for electrical appliances such as information processing devices.

[0059] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Example]

[0060] [Production example] (Preparation of sulfide solid electrolyte 1) A raw material composition containing Li2S, P2S5, LiBr, and LiI was subjected to mechanical milling to form an amorphous precursor with a composition of 15LiBr-10LiI-75 (0.75Li2S-0.25P2S5). A bead mill (LMZ015, manufactured by Ashizawa Finetech) was loaded with 6 kg of ZrO2 balls (φ0.2 mm). A precursor having a composition of 15LiBr-10LiI-75 (0.75Li2S-0.25P2S5), dehydrated heptane, and dibutyl ether were added to a stirring tank. The mixture was milled at a peripheral speed of 16 m / s for 1 hour, then at a peripheral speed of 9 m / s for 7 hours to obtain a slurry (micronization process). The resulting slurry was vacuum dried at 120 °C for 3 hours. It was then heat-treated at 180 °C for 3 hours under a vacuum of 500 Pa or less (heat treatment process). This produced sulfide solid electrolyte 1.

[0061] (Preparation of sulfide solid electrolyte 2) Sulfide solid electrolyte 2 was obtained in the same manner as sulfide solid electrolyte 1, except that the heat treatment step was performed at 150° C. for 5 hours under a vacuum of 500 Pa or less.

[0062] (Preparation of sulfide solid electrolyte 3) Sulfide solid electrolyte 3 was obtained in the same manner as sulfide solid electrolyte 1, except that the heat treatment step was performed at 120° C. for 5 hours under a vacuum of 500 Pa or less.

[0063] (Preparation of sulfide solid electrolyte 4) Sulfide solid electrolyte 4 was obtained in the same manner as sulfide solid electrolyte 1, except that the heat treatment step was performed at 200° C. for 5 hours under a vacuum of 500 Pa or less.

[0064] [evaluation] The Raman spectra of the obtained sulfide solid electrolytes 1 to 4 were measured, and the peak positions and half widths were calculated. The results are shown in Table 1.

[0065] [Table 1]

[0066] As shown in Table 1, all of the sulfide solid electrolytes 1 to 4 had a capacitance of 415 cm -1 Over 425cm -1 The peaks were confirmed at the following positions. In addition, the half-width of the peaks for sulfide solid electrolytes 1 to 3 was 15.5 cm. -1 In contrast, the sulfide solid electrolyte 4 had a half-width of 15.5 cm -1 It was less than.

[0067] [Example 1] (Preparation of negative electrode) We weighed 22.1 g of nanomaterial anode active material (Si particles), 11.3 g of sulfide solid electrolyte (sulfide solid electrolyte 1), and 2.9 g of conductive material (VGCF). We also prepared a binder (PVDF) diluted to 5 wt% and a dispersion medium (diisobutyl ketone, DIBK).

[0068] These were placed in a kneading machine (Filmix (registered trademark), manufactured by Primix Corporation) and kneaded at a peripheral speed of 5 m / s to 30 m / s to obtain a slurry with a solid content of 39 wt %. The mixing volume ratio of the Si particles to the sulfide solid electrolyte 1 (Si particles: sulfide solid electrolyte 1) was equivalent to 65:35. The obtained slurry was applied to a negative electrode current collector (Ni foil) and dried to obtain a negative electrode having a negative electrode active material layer and a negative electrode current collector.

[0069] (Preparation of solid electrolyte layer) 39.0 g of sulfide solid electrolyte (sulfide solid electrolyte 4) was weighed. A binder (PVDF) diluted to 5 wt % and a dispersion medium (a mixture of heptane and dibutyl ether) were also prepared. These were mixed at 2000 rpm using a kneading device (barrel kneader) to obtain a solid electrolyte layer slurry with a solid content of 50 wt %. The obtained solid electrolyte layer slurry was applied to an Al foil and dried to obtain a solid electrolyte layer on the Al foil.

[0070] (Preparation of positive electrode) Cathode active material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2), a dispersion medium (butyl butyrate), a binder (a 5 wt% butyl butyrate solution of a PVdF-based binder), a sulfide solid electrolyte (sulfide solid electrolyte 4), and a conductive material (VGCF) were mixed to obtain a slurry. The obtained slurry was applied to a positive electrode current collector (Al foil) and dried to obtain a positive electrode having a positive electrode active material layer and a positive electrode current collector.

[0071] (Preparation of evaluation cells) The solid electrolyte layer was laminated on the positive electrode active material layer so that the solid electrolyte layer was in contact with the positive electrode active material layer, and then pressed. Then, the substrate (Al foil) of the solid electrolyte layer was peeled off, and the negative electrode active material layer was laminated on the negative electrode active material layer so that the solid electrolyte layer was in contact with the negative electrode active material layer, and then pressed. In this way, an evaluation cell was produced.

[0072] [Examples 2 and 3] An evaluation cell was produced in the same manner as in Example 1, except that the Si particles and sulfide solid electrolyte in the negative electrode active material layer were changed as shown in Table 2.

[0073] [Example 4] 22.1 g of nanomaterial negative electrode active material (Si particles), 14.0 g of sulfide solid electrolyte (sulfide solid electrolyte 1), and 2.9 g of conductive material (VGCF) were weighed. A binder, dispersant, and dispersion medium were prepared in the same manner as in Example 1. These were placed in a kneading machine (Filmix (registered trademark), manufactured by Primix Corporation) and kneaded at a peripheral speed of 5 m / s to 30 m / s to obtain a slurry with a solid content of 39 wt %. The volume ratio of the Si particles to the sulfide solid electrolyte 1 (Si particles:sulfide solid electrolyte 1) was equivalent to 60:40. The obtained slurry was applied to a negative electrode current collector (Cu foil) and dried to obtain a negative electrode having a negative electrode active material layer and a negative electrode current collector. A test cell was obtained in the same manner as in Example 1, except for using the obtained negative electrode.

[0074] [Examples 5 and 6] An evaluation cell was produced in the same manner as in Example 4, except that the Si particles and sulfide solid electrolyte in the negative electrode active material layer were changed as shown in Table 2.

[0075] [Example 7] 22.1 g of nanomaterial negative electrode active material (Si particles), 17.2 g of sulfide solid electrolyte (sulfide solid electrolyte 1), and 2.9 g of conductive material (VGCF) were weighed. A binder, dispersant, and dispersion medium were prepared in the same manner as in Example 1. These were placed in a kneading machine (Filmix (registered trademark), manufactured by Primix Corporation) and kneaded at a peripheral speed of 5 m / s to 30 m / s to obtain a slurry with a solid content of 39 wt %. The volume ratio of the Si particles to the sulfide solid electrolyte 1 (Si particles:sulfide solid electrolyte 1) was 55:45. The obtained slurry was applied to a negative electrode current collector (Cu foil) and dried to obtain a negative electrode having a negative electrode active material layer and a negative electrode current collector. A test cell was obtained in the same manner as in Example 1, except for using the obtained negative electrode.

[0076] [Examples 8 and 9] An evaluation cell was produced in the same manner as in Example 7, except that the Si particles and sulfide solid electrolyte in the negative electrode active material layer were changed as shown in Table 2.

[0077] [Example 10] 22.1 g of nanomaterial negative electrode active material (Si particles), 21.0 g of sulfide solid electrolyte (sulfide solid electrolyte 1), and 2.9 g of conductive material (VGCF) were weighed. A binder, dispersant, and dispersion medium were prepared in the same manner as in Example 1. These were placed in a kneading machine (Filmix (registered trademark), manufactured by Primix Corporation) and kneaded at a peripheral speed of 5 m / s to 30 m / s to obtain a slurry with a solid content of 39 wt %. The volume ratio of the Si particles to the sulfide solid electrolyte 1 (Si particles:sulfide solid electrolyte 1) was equivalent to 50:50. The obtained slurry was applied to a negative electrode current collector (Cu foil) and dried to obtain a negative electrode having a negative electrode active material layer and a negative electrode current collector. A test cell was obtained in the same manner as in Example 1, except for using the obtained negative electrode.

[0078] [Examples 11 and 12] An evaluation cell was produced in the same manner as in Example 10, except that the Si particles and sulfide solid electrolyte in the negative electrode active material layer were changed as shown in Table 2.

[0079] [Comparative Examples 1 to 12] Si particles that were not nanomaterials were prepared. Furthermore, sulfide solid electrolytes 1 to 3 were prepared. A binder, a dispersant, and a dispersion medium were prepared in the same manner as in Example 1. These were placed in a kneading device (Filmix (registered trademark), manufactured by Primix Corporation) and kneaded at a peripheral speed of 5 m / s to 30 m / s to obtain a slurry with a solid content of 53 wt %. The type of sulfide solid electrolyte and the volume ratio of the Si particles to the sulfide solid electrolyte in the slurry are shown in Table 3. The obtained slurry was applied to a negative electrode current collector (Cu foil) and dried to obtain a negative electrode having a negative electrode active material layer and a negative electrode current collector. A test cell was obtained in the same manner as in Example 1, except for using the obtained negative electrode.

[0080] [Comparative Examples 13 and 14] Si particles, which are nanomaterials, were prepared. Furthermore, sulfide solid electrolyte 4 was prepared. A binder, a dispersant, and a dispersion medium were prepared in the same manner as in Example 1. These were placed in a kneading device (Filmix (registered trademark), manufactured by Primix Corporation) and kneaded at a peripheral speed of 5 m / s to 30 m / s to obtain a slurry with a solid content of 39 wt %. The mixing volume ratio of Si particles to sulfide solid electrolyte in the slurry is shown in Table 3. The obtained slurry was applied to a negative electrode current collector (Cu foil) and dried to obtain a negative electrode having a negative electrode active material layer and a negative electrode current collector. A test cell was obtained in the same manner as in Example 1, except that the obtained negative electrode was used.

[0081] [evaluation] (Confining pressure fluctuation evaluation) The obtained evaluation cell was subjected to four cycles of CCCV charge / discharge at 0.1C with an upper limit voltage of 4.05V and a lower limit voltage of 2.5V. The design capacity of the solid-state battery was 0.4Ah. An NR600 data logger (manufactured by KEYENCE Corporation) was connected to the pressure gauge of the cell restraining jig to measure the cell pressure fluctuations. The confining pressure fluctuations were calculated using the following formula. The results of the confining pressure fluctuations during the first full charge are shown in Tables 2 and 3, and Figures 2 and 3. Confining pressure fluctuation (ΔMPa / Ah) = Pressure fluctuation (ΔMPa) / Charging capacity (Ah)

[0082] [Table 2]

[0083] [Table 3]

[0084] As shown in Tables 2, 3, and FIGS. 2 and 3, Examples 1 to 12, which used a nanomaterial Si-based active material and a sulfide solid electrolyte with low crystallinity, exhibited small confining pressure fluctuations. In contrast, Comparative Examples 1 to 12, which used a non-nanomaterial Si-based active material and a sulfide solid electrolyte with low crystallinity, exhibited large confining pressure fluctuations. Furthermore, Example 5 and Comparative Example 13 had the same Si particle size and active material:solid electrolyte ratio, but the use of a sulfide solid electrolyte with low crystallinity reduced the confining pressure fluctuations. Similarly, Example 11 and Comparative Example 14 had approximately the same Si particle size and active material:solid electrolyte ratio, but the use of a sulfide solid electrolyte with low crystallinity reduced the confining pressure fluctuations. The time-dependent changes in the confining pressure fluctuations of Example 10 and Comparative Example 14 are shown in FIG. 4. As shown in FIG. 4, Example 10 exhibited smaller confining pressure fluctuations than Comparative Example 14. [Explanation of symbols]

[0085] 1...Negative electrode current collector 2...Negative electrode active material layer 3...Solid electrolyte layer 4...Cathode active material layer 5...Positive electrode current collector 10 …All-solid-state batteries

Claims

1. An all-solid-state battery having a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer, the negative electrode active material layer includes a Si-based active material and a sulfide solid electrolyte, The average particle size (D ５０ ) is 100 nm or more and 800 nm or less, The sulfide solid electrolyte has a Raman spectrum of 415 cm －１ Over 425cm －１ The peak has a half-width of 15.5 cm －１ 20.0cm or more －１ is as follows: The volume ratio of the Si-based active material to the total of the Si-based active material and the sulfide solid electrolyte is 1% by volume or more and 65% by volume or less, a volume ratio of the sulfide solid electrolyte to the total volume of the Si-based active material and the sulfide solid electrolyte is 35% by volume or more and 99% by volume or less.

2. The sulfide solid electrolyte is PS ４ ３－ containing the structure The peak is the PS ４ ３－ The all-solid-state battery according to claim 1 , wherein the peak of the structure is

3. 3. The all-solid-state battery according to claim 1, wherein the sulfide solid electrolyte contains at least Li, P, and S.

4. The all-solid-state battery according to any one of claims 1 to 3, wherein the sulfide solid electrolyte contains a halogen.

5. 5. The all-solid-state battery according to claim 1, wherein the sulfide solid electrolyte has a lithium ion conductivity at 25°C of 1.5 mS / cm or more and 3.5 mS / cm or less.

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