Sulfide solid electrolyte, precursor, all-solid-state battery, and method for manufacturing sulfide solid electrolyte

Abstract

The main purpose of the present disclosure is to provide a sulfide solid electrolyte with good ion conductivity and water resistance. In the present disclosure, a sulfide solid electrolyte containing Li, P, S and CO3 is provided. 2‑ The sulfide solid electrolyte solves the above problems. The sulfide solid electrolyte has Li7P3S 11 The crystal phase of the structure is the main phase. In the X-ray diffraction measurement using CuKα radiation, the peak intensity of Li2S appearing at the position of 2θ=27.0°±0.5° is defined as I A The peak intensity of the above-mentioned crystal phase appearing at the position of 2θ=23.65°±0.50° is defined as I B In this case, I A / I B is 0 or more and 0.39 or less, and the sulfide solid electrolyte does not have a heterogeneous peak appearing at the position of 2θ=16.5°±0.5°.

Description

Technical Field

[0001] The present disclosure relates to a sulfide solid electrolyte having excellent ion conductivity and water resistance. Background Art

[0002] All-solid-state batteries are batteries with a solid electrolyte layer between the positive and negative electrode layers. Compared to liquid-based batteries with an electrolyte solution containing a flammable organic solvent, they offer the advantage of simplified safety features. Sulfide solid electrolytes are also known as solid electrolytes used in all-solid-state batteries.

[0003] For example, Patent Document 1 discloses a Li7P3S 11 In particular, Patent Document 1 discloses a so-called Li2S-P2S5-based sulfide solid electrolyte using Li2S and P2S5 as raw materials.

[0004] Prior art literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-053850 Summary of the Invention

[0006] Although Li2S-P2S5-based sulfide solid electrolytes have good ion conductivity, their high sulfur content leaves room for improvement in water resistance. The present disclosure is based on this reality, with the primary objective of providing a sulfide solid electrolyte with both good ion conductivity and water resistance.

[0007] In order to solve the above problems, the present invention provides a sulfide solid electrolyte containing Li, P, S and CO3 2- The above-mentioned sulfide solid electrolyte has Li7P3S 11 The crystal phase of the structure is the main phase. In the X-ray diffraction measurement using CuKα radiation, the peak intensity of Li2S appearing at the position of 2θ=27.0°±0.5° is defined as I A The peak intensity of the above-mentioned crystal phase appearing at the position of 2θ=23.65°±0.50° is defined as I B In this case, I A / I B is 0 or more and 0.39 or less, and the sulfide solid electrolyte does not have a heterogeneous peak appearing at the position of 2θ=16.5°±0.5°.

[0008] According to the present disclosure, CO3 2- , with Li7P3S 11 The crystal phase of the structure is the main phase, I A / I BSince the concentration is equal to or less than a predetermined value and has no heterogeneous peak, a sulfide solid electrolyte having excellent ion conductivity and water resistance can be obtained.

[0009] In the above disclosure, the molar ratio of the S to the P (S / P) may be 3.60 or less.

[0010] In the above disclosure, the ion conductivity at 25° C. can be 0.11 mS / cm or higher.

[0011] In addition, the present disclosure provides a precursor of the above-mentioned sulfide solid electrolyte, wherein the above-mentioned precursor contains the above-mentioned Li, the above-mentioned P, the above-mentioned S and the above-mentioned CO3 2- The decarbonation amount measured by thermogravimetric-differential thermal analysis is 0.49 wt % or more and 1.36 wt % or less.

[0012] According to the present disclosure, the precursor contains CO3 2- , the decarbonation amount is within a predetermined range, so a precursor for obtaining a sulfide solid electrolyte having good ion conductivity and water resistance can be formed.

[0013] In addition, the present disclosure provides an all-solid-state battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer formed between the positive electrode layer and the negative electrode layer, wherein at least one of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer contains the sulfide solid electrolyte.

[0014] According to the present disclosure, by using the above-mentioned sulfide solid electrolyte, an all-solid-state battery having excellent ion conductivity and water resistance can be obtained.

[0015] In addition, the present disclosure provides a method for producing a sulfide solid electrolyte, wherein the sulfide solid electrolyte contains Li, P, S and CO3 2- The manufacturing method includes an amorphization step and a calcination step. The amorphization step is to obtain a precursor by mechanically grinding a raw material composition containing Li2CO3 and P2S5. The calcination step is to calcine the precursor to form a Li7P3S 11 Crystalline phase of the structure.

[0016] According to the present disclosure, a raw material composition containing Li2CO3 can be used to form a Li7P3S 11 The crystal phase of the structure is used to obtain a sulfide solid electrolyte with good ion conductivity and water resistance.

[0017] In the above disclosure, the above precursor may contain the above Li, the above P, the above S and the above CO3 2- The decarbonation amount measured by thermogravimetric-differential thermal analysis can be 0.49 wt % or more and 1.36 wt % or less.

[0018] In the above disclosure, in the amorphization step, the mechanical milling treatment may be performed by a planetary ball mill, the substrate rotation speed may be 400 rpm to 600 rpm, and the treatment time may be 18 hours to 25 hours.

[0019] In the above disclosure, the raw material composition may not contain Li2S.

[0020] The present disclosure has the effect of being able to provide a sulfide solid electrolyte having excellent ion conductivity and water resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic cross-sectional view showing an example of an all-solid-state battery in the present disclosure.

[0022] Figure 2 This is a flowchart showing an example of a method for producing a sulfide solid electrolyte in the present disclosure.

[0023] Figure 3 These are the results of XRD measurement of the sulfide solid electrolytes obtained in Example 3 and Comparative Example 3.

[0024] Description of Reference Numerals

[0025] 1…positive electrode layer

[0026] 2…Negative electrode layer

[0027] 3…Solid electrolyte layer

[0028] 4…Positive electrode current collector

[0029] 5…Negative electrode current collector

[0030] 6…Battery housing

[0031] 10…All-solid-state batteries DETAILED DESCRIPTION

[0032] Hereinafter, the sulfide solid electrolyte, precursor, all-solid-state battery, and method for producing the sulfide solid electrolyte in the present disclosure will be described in detail.

[0033] A. Sulfide solid electrolyte

[0034] The sulfide solid electrolyte disclosed herein contains Li, P, S and CO3 2- , with Li7P3S 11 The crystal phase of the structure is the main phase. In the X-ray diffraction measurement using CuKα radiation, the peak intensity of Li2S appearing at the position of 2θ=27.0°±0.5° is defined as I AThe peak intensity of the above-mentioned crystal phase appearing at the position of 2θ=23.65°±0.50° is defined as I B In this case, I A / I B is 0 or more and 0.39 or less, and the sulfide solid electrolyte does not have a heterogeneous peak appearing at the position of 2θ=16.5°±0.5°.

[0035] According to the present disclosure, CO3 2- , with Li7P3S 11 The crystal phase of the structure is the main phase, I A / I B Since the ion conductivity is below a predetermined value and the sulfide solid electrolyte has no heterogeneous peak, a sulfide solid electrolyte having excellent ion conductivity and water resistance can be obtained.

[0036] As mentioned above, Patent Document 1 discloses a Li7P3S 11 In particular, Patent Document 1 discloses a so-called Li2S-P2S5 sulfide solid electrolyte using Li2S and P2S5 as raw materials. Although the Li2S-P2S5 sulfide solid electrolyte has good ion conductivity, it has a high sulfur content and therefore has room for improvement in water resistance. Specifically, there is room for improvement in water resistance by reducing hydrogen sulfide produced by reaction with water. In contrast, the sulfide solid electrolyte disclosed in the present invention contains carbonate ions (CO3 2- ), so the sulfur content can be reduced. Therefore, the amount of hydrogen sulfide produced can be suppressed, and water resistance becomes good. In addition, due to the carbonate ion (CO3 2- ) and the ionic radius of the sulfur ion (S - ) is similar, so it is believed that the sulfide solid electrolyte containing carbonate ions can maintain Li7P3S 11 As a result, the ion conductivity is also improved. In addition, the sulfide solid electrolyte disclosed in the present invention can be produced without using expensive Li2S as a raw material or by reducing its usage, thereby reducing the manufacturing cost.

[0037] How the sulfide solid electrolyte in this disclosure contains carbonate ions is not yet clear, but it is speculated as follows. First, in a typical Li7P3S 11 In the crystal phase, PS4 3- Unit and P2S7 with cross-linked sulfur (-S-) 4- Unit (S3P-S-PS3) to PS4 3- :P2S7 4- =1:1 ratio (Li3PS4+Li4P2S7→Li7P3S 11). It is believed that cross-linked sulfur has low stability to water and most of the generated hydrogen sulfide comes from cross-linked sulfur. On the other hand, as shown in the examples described below, in the sulfide solid electrolyte of the present disclosure, the amount of hydrogen sulfide generated is significantly small, so it is speculated that carbonate ions and Li7P3S 11 At least a portion of the cross-linking sulfur in the crystalline phase is substituted.

[0038] The sulfide solid electrolyte in the present disclosure contains Li, P, S and CO3 2- Sulfide solid electrolytes can contain only Li, P, S and CO3 2- , and may contain other elements. Examples of other elements include X (X is a halogen). Examples of halogen include F, Cl, Br, and I. X may be one or more.

[0039] The sulfide solid electrolyte disclosed in the present invention has Li7P3S 11 The crystal phase of the structure (hereinafter also referred to as crystal phase A) is speculated to be Li7P3S 11 In the X-ray diffraction measurement using CuKα radiation, the crystal phase A is a crystal phase in which at least a part of the crosslinked sulfur is replaced by carbonate ions. 11 There are peaks at the same position of the crystal phase. Li7P3S 11 Typical peaks of the crystalline phase appear at 2θ = 17.8°, 18.2°, 19.8°, 21.8°, 23.8°, 25.9°, 29.5°, and 30.0°. Crystalline phase A also preferably has peaks at ±0.5° (preferably ±0.3°) of the above positions.

[0040] The sulfide solid electrolyte disclosed herein comprises crystalline phase A as its primary phase. "Having crystalline phase A as its primary phase" means that the proportion (weight %) of crystalline phase A relative to all crystalline phases contained in the sulfide solid electrolyte is the largest. The proportion of crystalline phase A relative to all crystalline phases contained in the sulfide solid electrolyte can be, for example, 50 weight % or greater, 70 weight % or greater, or 90 weight % or greater. The proportion of crystalline phase A can be determined, for example, from the results of radiometric XRD.

[0041] In the X-ray diffraction measurement of the sulfide solid electrolyte in the present disclosure using CuKα rays, the peak intensity of Li2S appearing at the position of 2θ=27.0°±0.5° is defined as I A , and the crystal phase A (with Li7P3S 11 The peak intensity of the crystal phase of the structure is set as I B In this case, I A / I B Below the predetermined value.A / I B Low means that the amount of Li2S component in the sulfide solid electrolyte is small. A / I B It is usually 3.9 or less, and may be 3.0 or less, 2.0 or less, or 1 or less. A / I B It may be 0 or greater than 0. In the present disclosure, when the sulfide solid electrolyte does not have a peak of Li2S appearing at 2θ=27.0°±0.5°, I A The so-called "no Li2S peak" means that the Li2S peak is so small that it cannot be distinguished from the surrounding noise. A / I B If the value of is too large, that is, if the amount of Li2S is too high, ion conduction may be inhibited and / or the amount of hydrogen sulfide generated may increase. In addition, it may cause composition deviation.

[0042] In addition, the sulfide solid electrolyte disclosed in the present invention does not have a heterogeneous peak appearing at the position of 2θ=16.5°±0.5° in the X-ray diffraction measurement using CuKα rays. The so-called heterogeneous phase refers to a crystalline phase that does not belong to either the unreacted raw material or the crystalline phase A, and is a crystalline phase with lower ion conductivity than the crystalline phase A. The so-called "no peak at the position of the above-mentioned heterogeneous phase" means that the peak of the above-mentioned Li2S is so small that it cannot be distinguished from the surrounding noise. Specifically, it means that the intensity of the heterogeneous peak appearing at the position of 2θ=16.5°±0.5° is set to I C In this case, I C / I B Less than 0.1.

[0043] In the sulfide solid electrolyte, the molar ratio of S to P (S / P) is, for example, 3.60 or less, 3.2 or less, 3.0 or less, or 2.8 or less. 11 The S / P ratio in the crystal phase is 3.67. On the other hand, the S / P ratio may be, for example, 2.0 or more, or 2.2 or more.

[0044] In the sulfide solid electrolyte, the molar ratio of Li to the total of Li and P (Li / (Li+P)) is, for example, 0.65 or more, or 0.68 or more. On the other hand, Li / (Li+P) can be, for example, 0.75 or less, or 0.72 or less. 11The Li / (Li+P) ratio in the crystal phase is 0.70. When the sulfide solid electrolyte contains X (X is a halogen), the Li excluding an amount of Li equimolar to X preferably satisfies the above-mentioned molar ratio (Li / (Li+P)).

[0045] The sulfide solid electrolyte preferably has high ion conductivity. The ion conductivity at 25° C. is, for example, 0.11 mS / cm or higher, or may be 0.5 mS / cm or higher. The ion conductivity of the sulfide solid electrolyte can be measured, for example, by an AC impedance method.

[0046] The shape of the sulfide solid electrolyte may be, for example, a granular shape. 50 ) is, for example, 0.1 μm or more and 50 μm or less. The average particle size (D 50 ) can be determined based on the results of particle size distribution measurement using a laser diffraction scattering method. The use of the sulfide solid electrolyte is not particularly limited, but is preferably used in all-solid-state batteries, for example.

[0047] B. Precursors

[0048] The precursor of the sulfide solid electrolyte in the present disclosure is the precursor of the above-mentioned sulfide solid electrolyte, and the above-mentioned precursor contains the above-mentioned Li, the above-mentioned P, the above-mentioned S and the above-mentioned CO3 2- The decarbonation amount determined by thermogravimetric-differential thermal analysis is within a predetermined range.

[0049] According to the present disclosure, the precursor contains CO3 2- , the decarbonation amount is within a predetermined range, so a precursor for obtaining a sulfide solid electrolyte having good ion conductivity and water resistance can be formed.

[0050] The decarbonation amount is generally more than the 0.49 % by weight, can be more than the 0.6 % by weight, also can be more than the 0.7 % by weight. On the other hand, the decarbonation amount is generally below the 1.36 % by weight, can be below the 1.3 % by weight, can be below the 1.1 % by weight, also can be below the 0.9 % by weight. The decarbonation amount adopts thermogravimetric-differential thermal analysis (TG-DTA) to calculate.

[0051] The precursors used in this disclosure are typically amorphous sulfide glasses. Amorphous refers to the absence of crystalline periodicity in X-ray diffraction (XRD) measurements, where a so-called halo pattern is observed. Furthermore, the precursors are typically used to obtain the sulfide solid electrolytes described in "A. Sulfide Solid Electrolytes" above.

[0052] C. All-solid-state batteries

[0053] Figure 1 This is a schematic cross-sectional view showing an example of an all-solid-state battery in the present disclosure. Figure 1 The illustrated all-solid-state battery 10 includes a positive electrode layer 1, a negative electrode layer 2, a solid electrolyte layer 3 formed between the positive electrode layer 1 and the negative electrode layer 2, a positive electrode current collector 4 for collecting current from the positive electrode layer 1, a negative electrode current collector 5 for collecting current from the negative electrode layer 2, and a battery case 6 for housing these components. Furthermore, at least one of the positive electrode layer 1, the negative electrode layer 2, and the solid electrolyte layer 3 contains the sulfide solid electrolyte described in "A. Sulfide Solid Electrolyte" above.

[0054] According to the present disclosure, by using the above-mentioned sulfide solid electrolyte, an all-solid-state battery having excellent ion conductivity and water resistance can be obtained.

[0055] 1. Positive electrode layer

[0056] The positive electrode layer in the present disclosure is a layer containing at least a positive electrode active material. The positive electrode layer may contain at least one of a solid electrolyte, a conductive material, and a binder in addition to the positive electrode active material.

[0057] Examples of positive electrode active materials include oxide active materials. Examples of oxide active materials include LiCoO2, LiMnO2, LiNiO2, LiVO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and other rock salt layered active materials, LiMn2O4, Li(Ni 0.5 Mn 1.5 )O4 and other spinel active materials, LiFePO4, LiMnPO4, LiNiPO4, LiCuPO4 and other olivine active materials.

[0058] The surface of the positive electrode active material may be covered with a coating layer. This helps suppress the reaction between the positive electrode active material and the sulfide solid electrolyte. Examples of materials for the coating layer include Li-ion conductive oxides such as LiNbO3, Li3PO4, and LiPON. The average thickness of the coating layer is, for example, 1 nm to 20 μm, or 1 nm to 10 nm.

[0059] The positive electrode layer in the present disclosure preferably contains the above-mentioned sulfide solid electrolyte. In addition, as a conductive material, for example, a carbon material can be mentioned. As a carbon material, for example, granular carbon materials such as acetylene black (AB) and Ketjen black (KB), fibrous carbon materials such as carbon fibers, carbon nanotubes (CNTs) and carbon nanofibers (CNFs) can be mentioned. As an adhesive, for example, a fluorine-based adhesive such as polyvinylidene fluoride (PVDF) can be mentioned. The thickness of the positive electrode layer is, for example, not less than 0.1 μm and not more than 1000 μm.

[0060] 2. Negative electrode layer

[0061] The negative electrode layer in the present disclosure is a layer containing at least a negative electrode active material. In addition, the negative electrode layer may further contain at least one of a solid electrolyte, a conductive material, and a binder in addition to the negative electrode active material.

[0062] Examples of negative electrode active materials include metal active materials and carbon active materials. Examples of metal active materials include In, Al, Si, and Sn. On the other hand, examples of carbon active materials include mesocarbon microbeads (MCMB), highly oriented pyrolytic graphite (HOPG), hard carbon, and soft carbon.

[0063] The solid electrolyte, conductive material, and binder are the same as those described above. The negative electrode layer in the present disclosure preferably contains the above-mentioned sulfide solid electrolyte. The thickness of the negative electrode layer is, for example, 0.1 μm to 1000 μm.

[0064] 3. Solid electrolyte layer

[0065] The solid electrolyte layer in the present disclosure is a layer formed between the positive electrode layer and the negative electrode layer, and contains at least a solid electrolyte. Furthermore, the solid electrolyte layer may contain a binder in addition to the solid electrolyte. The solid electrolyte and binder are the same as described above. The solid electrolyte layer in the present disclosure preferably contains the sulfide solid electrolyte described above. The thickness of the solid electrolyte layer is, for example, not less than 0.1 μm and not more than 1000 μm.

[0066] 4. Other structures

[0067] The all-solid-state battery disclosed herein generally comprises a positive electrode current collector for collecting current in the positive electrode layer and a negative electrode current collector for collecting current in the negative electrode layer. Examples of materials for the positive electrode current collector include SUS, aluminum, nickel, iron, titanium, and carbon. On the other hand, examples of materials for the negative electrode current collector include SUS, copper, nickel, and carbon. In addition, the battery case may be a general battery case such as a SUS battery case.

[0068] 5. All-solid-state batteries

[0069] The all-solid-state battery in the present disclosure is preferably an all-solid-state lithium-ion battery. In addition, the all-solid-state battery may be a primary battery or a secondary battery, wherein a secondary battery is preferred. Because it can be repeatedly charged and discharged, it is useful as, for example, a vehicle-mounted battery. Furthermore, the term "secondary battery" also includes a case where the secondary battery is used in the form of a primary battery (used for the purpose of only one discharge after charging). In addition, as the shape of the all-solid-state battery, for example, a coin type, a laminated type, a cylindrical type, and a square type can be cited.

[0070] D. Method for manufacturing sulfide solid electrolyte

[0071] Figure 2This is a flowchart showing an example of a method for producing a sulfide solid electrolyte in the present disclosure. Figure 2 In the process, a raw material composition containing Li2CO3 and P2S5 is first prepared. Then, the raw material composition is subjected to mechanical milling to obtain a precursor. Then, the obtained precursor is calcined to form a Li7P3S 11 Thus, a sulfide solid electrolyte is obtained.

[0072] According to the present disclosure, a raw material composition containing Li2CO3 is used to form a Li7P3S 11 The crystal phase of the structure can produce a sulfide solid electrolyte with good ion conductivity and water resistance. In addition, in the present disclosure, since the expensive Li2S raw material can be eliminated or its usage can be reduced to produce the above-mentioned sulfide solid electrolyte, the manufacturing cost can be reduced.

[0073] 1. Amorphization process

[0074] The amorphization step is a step of obtaining a precursor by mechanically milling a raw material composition containing Li2CO3 and P2S5.

[0075] The raw material composition contains at least Li2CO3 and P2S5. The raw material composition may or may not contain Li2S, but the latter is preferred because it can reduce the sulfur content of the sulfide solid electrolyte. In the former case, the ratio of Li2S to the total of Li2CO3 and Li2S can be, for example, 50 mol% or less, 30 mol% or less, or 10 mol% or less. Alternatively, the above ratio can be, for example, 1 mol% or more.

[0076] The raw material composition may further contain LiX (X is a halogen). Examples of LiX include LiF, LiCl, LiBr, and LiI. Furthermore, the raw material composition may or may not contain an oxide such as Li2O.

[0077] The molar ratio of S to P (S / P) in the raw material composition is, for example, 3.60 or less, 3.2 or less, 3.0 or less, or 2.8 or less. 11 The S / P ratio in the crystal phase is 3.67. On the other hand, the S / P ratio is, for example, 2.0 or more, or 2.2 or more.

[0078] The molar ratio of Li to the total of Li and P in the raw material composition (Li / (Li+P)) is, for example, 0.65 or more, or 0.68 or more. On the other hand, Li / (Li+P) is, for example, 0.75 or less, or 0.72 or less.11 Li / (Li+P) in the crystal phase is 0.70. When the raw material composition contains X (X is a halogen), the Li excluding an amount of Li equimolar to X preferably satisfies the above-mentioned molar ratio (Li / (Li+P)).

[0079] In addition, as for mechanical grinding, there is no particular limitation as long as it is a method that can impart mechanical energy, and examples thereof include ball milling, vibration milling, turbine milling, mechanical fusion, and disc milling. Mechanical grinding can be dry or wet, but the latter is preferred from the viewpoint of uniform treatment. The type of dispersion medium used in the wet mechanical grinding method is not particularly limited.

[0080] Various conditions for mechanical milling are set to obtain the desired precursor. For example, when a planetary ball mill is used, the raw material composition and grinding balls are added and the process is carried out at a predetermined rotation speed and time. The substrate rotation speed of the planetary ball mill is, for example, 300 rpm or more, or 400 rpm or more. On the other hand, the substrate rotation speed of the planetary ball mill is, for example, 600 rpm or less, or 550 rpm or less. In addition, the processing time of the planetary ball mill is, for example, 10 hours or more, 18 hours or more, or 20 hours or more. On the other hand, the processing time is, for example, less than 30 hours, or less than 25 hours.

[0081] The precursor obtained by the amorphization step is the same as that described in "B. Precursor of sulfide solid electrolyte", and therefore description thereof is omitted here.

[0082] 2. Firing process

[0083] The calcination step is to calcine the above precursor to form a Li7P3S 11 The process of the crystal phase of the structure.

[0084] The calcination temperature is preferably equal to or higher than the crystallization temperature (Tc) of the sulfide solid electrolyte obtained by calcining the precursor. The crystallization temperature (Tc) of the sulfide solid electrolyte is, for example, 170°C to 280°C. The crystallization temperature (Tc) of the sulfide solid electrolyte can be determined using differential thermal analysis (DTA). The calcination temperature is, for example, equal to or higher than Tc. Alternatively, the calcination temperature is, for example, 200°C to 320°C.

[0085] The heating time is not particularly limited as long as it is sufficient to obtain the desired sulfide solid electrolyte. For example, the heating time is 1 minute to 24 hours, or 1 minute to 10 hours. Furthermore, heating is preferably performed in an inert gas atmosphere (e.g., an Ar gas atmosphere) or a reduced pressure atmosphere (e.g., a vacuum atmosphere). This prevents degradation (e.g., oxidation) of the sulfide solid electrolyte. The heating method is not particularly limited, and examples thereof include methods using a sintering furnace.

[0086] 3. Sulfide solid electrolyte

[0087] Through the above process, a mixture containing Li, P, S and CO3 can be obtained. 2- The sulfide solid electrolyte is preferably the same as that described in the above "A. Sulfide solid electrolyte".

[0088] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely illustrative, and any solutions that have substantially the same technical concept as that described in the claims of the present disclosure and that exhibit the same functions and effects are all encompassed within the technical scope of the present disclosure.

[0089] [Example]

[0090] [Example 1]

[0091] Using Li2CO3 (High Purity Chemical) and P2S5 (Aldrich) as raw materials, a sulfide solid electrolyte was prepared as follows. First, 0.8736 g of Li2CO3 and 1.1264 g of P2S5 were weighed and mixed. The resulting raw material composition (70Li2CO3-30P2S5) was placed in a zirconia pot (45 ml) containing zirconia balls with a diameter of 5 mm, 4 g of dehydrated heptane (Kanto Chemical Industry) was added thereto, and the lid was closed. It was placed in a planetary ball mill (Fritch P-7) and mechanically ground at a rotation speed of 500 rpm for 18 hours to obtain a precursor (glass). Next, the obtained precursor was heated at 300°C above the crystallization temperature for 3 hours under an inert atmosphere to thereby sinter it. It was then cooled to produce a sulfide solid electrolyte as a glass ceramic. Furthermore, the obtained sulfide solid electrolyte was heated, and the released gas was analyzed by gas chromatography, and carbon dioxide was mainly detected. Therefore, it was confirmed that the sulfide solid electrolyte contained carbonate ions.

[0092] [Comparative Example 1]

[0093] 0.6508 g of Li2S (Fluuchi Chemical) and 1.3492 g of P2S5 were weighed and mixed as raw materials. A sulfide solid electrolyte was prepared in the same manner as in Example 1 except that the obtained raw material composition (70Li2S-30P2S5) was used.

[0094] [Examples 2 and 3 and Comparative Examples 2 and 3]

[0095] A sulfide solid electrolyte was produced in the same manner as in Example 1 except that the processing time of mechanical milling was changed to the time shown in Table 1.

[0096] [evaluate]

[0097] (XRD measurement)

[0098] The sulfide solid electrolytes obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were subjected to X-ray diffraction (XRD) measurement using CuKα radiation. The results of Example 3 and Comparative Example 3 are shown as representative results. Figure 3 .like Figure 3 As shown by the arrow in (a), in Example 3, it was confirmed that Li7P3S 11 In addition, in Example 3, no peak from a different phase was observed near 2θ=16.5°. Figure 3 As shown in (b), in Comparative Example 3, a peak originating from a different phase was observed near 2θ=16.5°. A / I B After that, Example 3 is 0.39, and Comparative Example 3 is 1.41. C / I B After that, Example 3 is 0.098 and Comparative Example 3 is 0.61.

[0099] (Thermogravimetry-differential thermal analysis)

[0100] The crystallization temperature (Tc) and the amount of decarbonation were determined by thermogravimetric-differential thermal analysis (TG-DTA) of each precursor in Examples 1 to 3 and Comparative Examples 1 to 3 as follows. The amount of decarbonation was determined using a TG-DTA apparatus (manufactured by Rigaku). The precursor was heated from room temperature to 400°C at a rate of 10°C / min, and the amount of decarbonation was calculated from the TG curves before and after the crystallization temperature. The results are shown in Table 1.

[0101] (Ionic conductivity measurement)

[0102] The ion conductivity of the sulfide solid electrolytes obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was measured (25°C). A pelletizer was used at 6 ton / cm 2100 mg of the resulting sulfide solid electrolyte powder was pressed under a pressure of 100 to produce pellets. The resistance of the pellets was determined using the AC impedance method, and the ion conductivity was determined based on the pellet thickness. The results are shown in Table 1.

[0103] (Determination of hydrogen sulfide generation)

[0104] Water resistance was evaluated by measuring hydrogen sulfide generation for the sulfide solid electrolytes obtained in Example 2 and Comparative Example 1 as follows. A 1.5L desiccator was placed in a dry gas glove box set at a dew point of -30°C. An aluminum container containing 2 mg of the sulfide solid electrolyte was placed inside the desiccator. The desiccator lid was closed with a fan running, and the desiccator was exposed to water for 30 minutes. The generated hydrogen sulfide was observed using a sensor. The results are shown in Table 1.

[0105] Table 1

[0106]

[0107] As shown in Table 1, in Comparative Example 1, although the ion conductivity was high, the amount of hydrogen sulfide generated was large. On the other hand, in Examples 1 to 3, 10 -1 The ionic conductivity was excellent, with mS / cm or higher. Furthermore, in Example 2, the amount of hydrogen sulfide generated was significantly reduced compared to Comparative Example 1. Although the amount of hydrogen sulfide generated was not measured in Examples 1 and 3, since the raw material compositions were the same, it is believed that similar results to those in Example 2 were obtained.

[0108] In addition, the ion conductivity of Comparative Examples 2 and 3 is lower than that of Examples 1 to 3. In addition, the amount of decarbonation in Comparative Example 2 is extremely large. It is speculated that this is because the treatment time is short and the carbonate ions do not enter the glass. This shows that the sulfide solid electrolyte obtained in Comparative Example 2 does not contain carbonate ions (CO3 2- ). In addition, in Comparative Example 2, the ion conductivity is one digit lower than that of Examples 1 to 3. Therefore, it is shown that the sulfide solid electrolyte obtained in Comparative Example 2 does not have Li7P3S 11 On the other hand, as shown in Table 1, in Comparative Example 3, I A / I B This is larger than that of Example 3, indicating low water resistance. In Comparative Example 3, a heterogeneous peak was observed, and it is presumed that the heterogeneous phase caused a decrease in ion conductivity.

Claims

1. A sulfide solid electrolyte containing Li, P, S and CO3 2- , The sulfide solid electrolyte has Li7P3S 11 The crystal phase of the structure is the main phase, In X-ray diffraction measurement using CuKα rays, The peak intensity of Li2S appearing at the position of 2θ = 27.0° ± 0.5° is defined as I A The peak intensity of the crystal phase appearing at the position of 2θ=23.65°±0.50° is defined as I B In this case, I A / I B is greater than 0 and less than 0.39, The sulfide solid electrolyte does not have a heterogeneous peak appearing at a position of 2θ=16.5°±0.5°.

2. The sulfide solid electrolyte according to claim 1, wherein the crystal phase is Li7P3S 11 A crystalline phase in which at least a portion of the cross-linked sulfur in the crystalline phase is replaced by carbonate ions. 3 . The sulfide solid electrolyte according to claim 1 , wherein a molar ratio of the S to the P (S / P) is 3.60 or less. The sulfide solid electrolyte according to claim 1 , wherein the ion conductivity at 25° C. is 0.11 mS / cm or higher.

5. A precursor of the sulfide solid electrolyte according to any one of claims 1 to 4, The precursor contains Li, P, S and CO3 2- , The decarbonation amount measured by thermogravimetric-differential thermal analysis is 0.49% by weight or more and 1.36% by weight or less.

6. An all-solid-state battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer formed between the positive electrode layer and the negative electrode layer. At least one of the positive electrode layer, the negative electrode layer, and the solid electrolyte layer contains the sulfide solid electrolyte according to any one of claims 1 to 4.

7. A method for producing a sulfide solid electrolyte, wherein the sulfide solid electrolyte contains Li, P, S and CO3 2- The manufacturing method includes an amorphization step and a sintering step, The amorphization step is to obtain a precursor by mechanically grinding the raw material composition containing Li2CO3 and P2S5. The calcination step calcines the precursor to form a Li7P3S 11 Crystalline phase of the structure.

8. The method for producing a sulfide solid electrolyte according to claim 7, wherein the precursor contains the Li, P, S and CO3 2- The decarbonation amount measured by thermogravimetric-differential thermal analysis is 0.49 wt % or more and 1.36 wt % or less.

9. The method for producing a sulfide solid electrolyte according to claim 7, wherein in the amorphization step, the mechanical milling treatment uses a planetary ball mill, the substrate rotation speed is 400 rpm to 600 rpm, and the treatment time is 18 hours to 25 hours. 10 . The method for producing a sulfide solid electrolyte according to claim 7 , wherein the raw material composition does not contain Li 2 S.

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