Sulfide solid electrolyte

Abstract

The solid battery according to one embodiment of the present disclosure provides a sulfide solid electrolyte containing at least Li, Sn, S, and O, and having a tetragonal crystal structure.

Description

Technical Field

[0001] This disclosure relates to sulfide solid electrolytes. Background Technology

[0002] Previously, rechargeable batteries were used for various purposes. For example, they were used as power sources for electronic devices such as smartphones and laptops.

[0003] In secondary batteries, liquid electrolytes are typically used as the medium for ion movement that facilitates charging and discharging. That is, the so-called electrolyte is used in secondary batteries. However, in such secondary batteries, safety is generally required from the viewpoint of preventing electrolyte leakage. Furthermore, since organic solvents and other substances used in the electrolyte are flammable, safety is also required in this regard.

[0004] Therefore, research has been conducted on solid-state batteries that use solid electrolytes instead of liquid electrolytes.

[0005] Existing technical documents

[0006] Non-patent literature

[0007] Non-patent literature 1: K. Kanazawa, et al., Inorg. Chem., 2018, 57, 9925-9930. Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] Here, as the aforementioned solid electrolyte, a sulfide solid electrolyte with excellent ionic conductivity and room temperature formability is sometimes used. However, since sulfide solid electrolytes react with moisture to produce harmful hydrogen sulfide, a sulfide solid electrolyte with excellent water resistance is required.

[0010] In this regard, Li-Sn-S (LSS) solid electrolytes, as sulfide solid electrolytes with excellent water resistance, have attracted attention. However, compared with previously known Li-PS (LPS) solid electrolytes, LSS is partially reduced and decomposed at a low potential of around 1.0V, exhibiting low reduction resistance. Therefore, the dissolution efficiency of Li metal is quite low, making it difficult to combine commonly used negative electrode active materials with LSS in solid-state batteries.

[0011] This disclosure was made in view of the technical problem that is, the object of this disclosure is to provide a sulfide solid electrolyte that can improve resistance to reduction.

[0012] Technical solutions for solving technical problems

[0013] To achieve the above objectives, one embodiment of the solid-state battery disclosed herein provides a sulfide solid electrolyte. It must contain at least Li, Sn, S, and O. The crystal structure is tetragonal.

[0014] The effects of the invention

[0015] According to one embodiment of the present disclosure, the sulfide solid electrolyte can improve resistance to reduction. Attached Figure Description

[0016] Figure 1 This is a schematic cross-sectional view of a solid battery containing a sulfide solid electrolyte according to one embodiment of the present disclosure.

[0017] Figure 2 This is a schematic cross-sectional view of a solid battery containing a sulfide solid electrolyte according to one embodiment of the present disclosure.

[0018] Figure 3 This is a schematic cross-sectional view of a solid battery containing a sulfide solid electrolyte according to one embodiment of the present disclosure.

[0019] Figure 4A This is a graph representing the dissolution-precipitation curve in Comparative Example 1.

[0020] Figure 4B This is a graph representing the dissolution-precipitation curve in Example 1. Detailed Implementation

[0021] The solid-state battery of this disclosure will now be described in detail. Although the description is based on the accompanying drawings as needed, the illustrations are schematic and exemplary only for the purpose of understanding this disclosure, and the appearance and size ratios may differ from the actual product.

[0022] The term "sectional view" as used in this specification refers to a view taken from a direction approximately perpendicular to the stacking direction in the solid-state battery's layered structure (in short, a view taken from a plane parallel to the thickness direction of the layers). Furthermore, the terms "top view" or "top view shape" used in this specification are schematic diagrams taken from above or below the object along the thickness direction of the layer (i.e., the aforementioned stacking direction).

[0023] The terms "up and down" and "left and right" used directly or indirectly in this specification correspond to the up and down and left and right directions in the figures, respectively. Unless otherwise stated, the same reference numerals or symbols indicate the same parts / areas or have the same meaning. In a preferred embodiment, it can be understood that the vertical direction downward (i.e., the direction of gravity) corresponds to the "down direction," and its opposite direction corresponds to the "up direction."

[0024] In this disclosure, "solid-state battery" broadly refers to a battery whose constituent elements are made of solids, and narrowly refers to an all-solid-state battery whose constituent elements (particularly preferably all constituent elements) are made of solids. In a preferred embodiment, the solid-state battery of this disclosure is a stacked solid-state battery in which the layers forming the battery structural units are stacked on top of each other. "Solid-state battery" includes not only primary batteries but also so-called secondary batteries capable of repeated charging and discharging. The term "secondary battery" is not overly limited in its definition; for example, it may also include energy storage devices. Hereinafter, the specific structure of a solid-state battery will be described using a solid-state battery as an example of a secondary battery.

[0025] The features of this disclosure relate to a positive electrode portion and a solid electrolyte portion included in a solid-state battery. Hereinafter, in order to understand the overall structure of the solid-state battery, the basic structure of the solid-state battery of this disclosure will be described. However, the structure of the solid-state battery described herein is merely an example for understanding the invention and does not limit the invention.

[0026] [Basic Structure of Solid-State Batteries]

[0027] Figure 1 This is a schematic cross-sectional view illustrating a solid-state battery comprising a sulfide solid electrolyte according to one embodiment of the present disclosure. This is a schematic cross-sectional view illustrating a solid-state battery according to one embodiment of the present invention. The solid-state battery has at least an electrode portion and a negative electrode portion, and a solid electrolyte portion. Specifically, as... Figure 1 As shown, the solid-state battery 1 includes a battery structure unit consisting of a positive electrode portion 20, a negative electrode portion 30, and a solid electrolyte portion 40 at least in between.

[0028] The solid-state battery 1 of the present invention has at least one battery structure unit along the stacking direction Z, which consists of a positive electrode portion 20, a negative electrode portion 30, and a solid electrolyte portion 40 between them. The positive electrode portion 20 and the negative electrode portion 30 are stacked alternately with the solid electrolyte portion 40 in between.

[0029] The positive electrode portion 20 includes at least a positive electrode active material layer 22. The positive electrode portion may further include a solid electrolyte. On the other hand, the negative electrode portion 30 includes at least a negative electrode active material layer 32. The negative electrode portion 30 may further include a solid electrolyte. The positive electrode portion 20 and the negative electrode portion 30 having such structures can also be referred to as a "composite positive electrode" and a "composite negative electrode," respectively.

[0030] The positive and negative electrode active materials are substances that participate in electron transfer in a solid-state battery. Ions move (conduct) between the positive and negative electrode portions via the solid electrolyte, thus transferring electrons and enabling charging and discharging. The active materials in the positive and negative electrode portions are particularly preferably capable of inserting and deintercalating lithium ions. That is, the solid-state battery is preferably an all-solid-state secondary battery in which lithium ions move between the positive electrode portion 20 and the negative electrode portion 30 via the solid electrolyte for charging and discharging.

[0031] The positive electrode active material included in the positive electrode section 20 may be, for example, at least one selected from the group consisting of lithium phosphate compounds having a NASICON-type structure, lithium phosphate compounds having an olivine-type structure, lithium-containing layered oxides, and lithium-containing oxides having a spinel-type structure.

[0032] Examples of lithium-containing phosphate compounds with a NASICON-type structure include Li3V2(PO4)3. Examples of lithium-containing phosphate compounds with an olivine-type structure include Li3Fe2(PO4)3, LiFePO4, and / or LiMnPO4. Examples of lithium-containing layered oxides include LiCoO2 and / or LiCo. 1 / 3 Ni 1 / 3 Mn 1 / 3 O2, etc. Examples of lithium-containing oxides with a spinel-type structure include LiMn2O4 and / or LiNi. 0.5 Mn 1.5 O4, etc. The types of lithium compounds are not particularly limited; for example, they can be lithium transition metal complex oxides and lithium transition metal phosphates. Lithium transition metal complex oxides are a general term for oxides containing lithium and one or more transition metal elements as constituent elements, and lithium transition metal phosphates are a general term for phosphate compounds containing lithium and one or more transition metal elements as constituent elements. The types of transition metal elements are not particularly limited; for example, they can be cobalt (Co), nickel (Ni), manganese (Mn), and iron (Fe).

[0033] Furthermore, the positive electrode active material can be, for example, an oxide, a disulfide, a chalcogenide, or a conductive polymer. Oxides can be, for example, titanium oxide, vanadium oxide, or manganese dioxide. Disulfides can be, for example, titanium disulfide or molybdenum sulfide. Chalcogenides can be, for example, niobium selenide. Conductive polymers can be, for example, disulfides, polypyrrole, polyaniline, polythiophene, poly(p-styrene), polyacetylene, or poly(phenylene oxide).

[0034] (Negative electrode active material)

[0035] Examples of negative electrode active materials included in the negative electrode section include at least one selected from the group consisting of oxides, carbon materials such as graphite, graphite-lithium compounds, lithium alloys, lithium phosphate compounds with a NASICON-type structure, lithium phosphate compounds with an olivine-type structure, and lithium oxides with a spinel-type structure. The oxide contains at least one element selected from the group consisting of titanium (Ti), silicon (Si), tin (Sn), chromium (Cr), iron (Fe), niobium (Nb), and molybdenum (Mo). Examples of lithium alloys include Li-Al. Examples of lithium phosphate compounds with a NASICON-type structure include Li3V2(PO4)3 and / or LiTi2(PO4)3. Examples of lithium phosphate compounds with an olivine-type structure include Li3Fe2(PO4)3 and / or LiCuPO4. Examples of lithium oxides with a spinel-type structure include Li4Ti5O. 12 wait.

[0036] It should be noted that in the solid-state battery 1, the positive electrode portion 20 and the negative electrode portion 30 can be made of the same material or they can be made of different materials.

[0037] The thickness of the positive electrode portion 20 and the negative electrode portion 30 is not particularly limited. For example, they can be 2 μm or more and 50 μm or less, especially 5 μm or more and 30 μm or less.

[0038] (Positive current collector layer / Negative current collector layer)

[0039] Although not essential elements of the electrode section, the positive electrode section 20 and the negative electrode section 30 may also each include a positive current collector 21 and a negative current collector 31. The positive current collector 21 and the negative current collector 31 may also be in the form of foils. A portion of each of the positive current collector 21 and the negative current collector 31 may be exposed to the outside of the solid-state battery 1. For example, the positive current collector 21 and the negative current collector 31 may each have an electrical connection portion for external electrical connection. In one embodiment, the solid-state battery may further include end-face electrodes (not shown), which are disposed on the end faces of the laminate of the positive electrode section, the negative electrode section, and the solid electrolyte section, and are electrically connected to the positive current collector 21 and the negative current collector 31, respectively.

[0040] As described above, in a solid-state battery, the positive current collector 21 and the negative current collector 31 are not essential, and it is also possible to consider a solid-state battery without such a positive current collector 21 and negative current collector 31. That is, the solid-state battery of this disclosure can be a so-called current collector-free solid-state battery.

[0041] (Solid Electrolyte Section)

[0042] The solid electrolyte section 40 contains a solid electrolyte capable of conducting ions such as lithium ions or sodium ions that facilitate charging and discharging. Particularly in the solid-state battery 1, the solid electrolyte section 40 forming the battery structural unit can form a layer capable of conducting lithium ions between the positive electrode section 20 and the negative electrode section 30. It should be noted that the solid electrolyte section 40 only needs to be provided at least between the positive electrode section 20 and the negative electrode section 30. That is, the solid electrolyte section 40 can also exist around the positive electrode section 20 and / or the negative electrode section 30 in a manner that extends from between the positive electrode section 20 and the negative electrode section 30.

[0043] The thickness of the solid electrolyte section 40 is not particularly limited. The thickness of the solid electrolyte section 40 located between the positive electrode section 20 and the negative electrode section 30 can be, for example, 1 μm or more and 15 μm or less, and in particular, 1 μm or more and 5 μm or less.

[0044] The outer surface of the solid-state battery 1 can be covered by a protective layer 10. The protective layer 10 is a layer provided for physical and chemical protection of the solid-state battery 1. When viewed from above, the protective layer 10 can be arranged to overlap with the laminate of the positive electrode portion 20, the negative electrode portion 30, and the solid electrolyte portion 40. That is, as shown... Figure 1 As shown, the protective layer 10 can be disposed on both sides of the solid battery 1 in the stacking direction Z of the electrode portion and the solid electrolyte portion. The material of the protective layer 10 is not particularly limited as long as it is an insulator, such as resin, glass, ceramic, etc.

[0045] The solid-state battery 1 may further include a reinforcement portion 60 disposed on a side facing each other in a direction intersecting the stacking direction Z. The reinforcement portion 60 can help prevent short circuits in the solid-state battery 1. The reinforcement portion 60 is not particularly limited as long as it is an insulator, and can be, for example, resin, glass, ceramic, etc.

[0046] [Features of this disclosure]

[0047] The present disclosure is characterized by a solid electrolyte that is a component of the aforementioned solid-state battery. The present disclosure is further characterized by the use of sulfide solid electrolytes, particularly Li-Sn-S (LSS) based solid electrolytes, as solid electrolytes.

[0048] In this disclosure, the sulfide solid electrolyte is characterized by containing at least Li (lithium), Sn (tin), S (sulfur), and O (oxygen), and its crystal structure is tetragonal. That is, the sulfide solid electrolyte of this disclosure is characterized by further containing O (oxygen) compared to the Li-Sn-S (LSS) solid electrolytes of the present invention, and its main crystal structure is determined to be tetragonal.

[0049] If this characteristic is present, the water resistance of the LSS-based solid electrolyte can be ensured, while the reducing decomposition at high potentials around 1.0V can be suppressed, thus improving the reduction resistance. Therefore, the dissolution efficiency of Li metal can be appropriately ensured, allowing for proper charging and discharging of the solid-state battery.

[0050] Specifically, the sulfide solid electrolyte of this disclosure is represented by the formula Li-MYO.

[0051] In the formula, M contains at least Sn, which is one or more elements selected from Groups 14 and 15, and Y contains at least S. Furthermore, the content of O in the above formula is greater than 0.1 mol and less than 1.5 mol.

[0052] More specifically, the sulfide solid electrolyte of this disclosure is represented by the formula Lix-M-Yy-Oz. In this formula, M contains at least Sn, which is one or more elements selected from Groups 14 and 15, and Y contains at least S. Additionally, in this formula, 3 < x ≤ 4, y + z ≤ 4, and 0.1 < z < 1.5 can be used.

[0053] Preferably, in the above formula, z ≤ 0.3 ≤ z ≤ 1.0. In this case, it is possible to appropriately ensure the efficiency of tens of percent Li precipitation and dissolution, and to properly charge and discharge the solid-state battery.

[0054] More preferably, M in the above formula further includes Si or Sb. In this case, the efficiency of Li precipitation and dissolution can be improved, and the charging and discharging of solid-state batteries can be performed more appropriately.

[0055] In one example, as described above Figure 1 As shown, the solid electrolyte section 40 includes a "first solid electrolyte section 42" and a "second solid electrolyte section 41". The "first solid electrolyte section 42" has a solid electrolyte formed between the positive electrode section 20 and the negative electrode section 30. The "second solid electrolyte section 41" is located between the first solid electrolyte section 42 and the negative electrode section 30, and is in contact with both the first solid electrolyte section 42 and the negative electrode section 30. The "second solid electrolyte section 41" is characterized by being composed of the sulfide solid electrolyte of the present disclosure described above.

[0056] Based on this characteristic, the water resistance of the LSS-based solid electrolyte can be ensured, while suppressing reduction decomposition at high potentials of around 1.0V, thus improving reduction resistance. Therefore, the dissolution efficiency of Li metal can be appropriately ensured. Furthermore, from the viewpoint of further optimizing this dissolution efficiency, it is preferable that the aforementioned "first solid electrolyte section 42" is also composed of the sulfide solid electrolyte of this disclosure.

[0057] In another example, such as Figure 2 As shown, the negative electrode active material layer 32a of the negative electrode portion 30A can contain particulate negative electrode active material 32a and the sulfide solid electrolyte 32b of this disclosure. In this case, the water resistance of the LSS-based solid electrolyte can be ensured, while the reduction decomposition at a high potential of around 1.0V can be suppressed, thus improving the reduction resistance. Therefore, the dissolution efficiency of Li metal can be appropriately ensured.

[0058] In yet another example, such as Figure 3 As shown, the negative electrode active material layer 32B of the negative electrode portion 30B can include particulate negative electrode active material 32a, a sulfide solid electrolyte 32b of this disclosure covering the surface of the negative electrode active material 32a, and a first solid electrolyte 32c. In this case, the water resistance of the LSS-based solid electrolyte can be ensured, while the reduction decomposition at a high potential of around 1.0V can be suppressed, improving the reduction resistance. Thus, the dissolution efficiency of Li metal can be appropriately ensured.

[0059] The average charging potential of the negative electrode active material is preferably 1.0V vs Li+ / Li or less. This improves the battery's output voltage. It should be noted that, without using the sulfide solid electrolyte of this disclosure, when the average charging potential of the negative electrode active material is 1.0V vs Li+ / Li or less, it is lower than the reduction potential of Li4SnS4. Therefore, the solid electrolyte in contact with the negative electrode active material decomposes, resulting in reduced discharge characteristics.

[0060] In this regard, by using the solid electrolyte in contact with the negative electrode active material as the solid electrolyte of this disclosure, even if the average charging potential of the negative electrode active material is less than 1.0V vs Li+ / Li, the reduction of the solid electrolyte in contact with the negative electrode active material can be suppressed, while improving the discharge characteristics.

[0061] It should be noted that the average charging potential of the negative electrode active material refers to the average of the negative electrode potentials in the charging curve obtained by conducting a charging test on a half-cell using the negative electrode active material of the test object. For example, the charging test of the above-mentioned half-cell can be performed under the following conditions, and the average value of the negative electrode potential from the start to the end of charging in the obtained charging curve can be used as the average charging potential of the negative electrode active material.

[0062] Charging rate: 0.1C

[0063] Charging method: CC

[0064] Charging termination voltage: 0.03V

[0065] The negative electrode active material layer 32 can be at least one selected from the group consisting of carbon (C), tin (Sn), silicon (Si), and lithium (Li) metal. In this case, the average charging potential of the negative electrode active material can be below 1.0V vs Li+ / Li, thereby improving the discharge characteristics.

[0066] Furthermore, from the viewpoint of suppressing the reduction of the solid electrolyte in contact with the negative electrode active material, it is preferable that the sulfide solid electrolyte of this disclosure can contact the negative electrode active material.

[0067] Example

[0068] The following describes embodiments of this disclosure.

[0069] (Preparation of sulfide solid electrolytes)

[0070] First, under an atmosphere with a dew point temperature below -60°C, the raw materials Li₂S (Sigma-Aldrich, model 213241):Li₂O (Sigma-Aldrich, model 374725):Sn (High Purity Chemical Research Institute, model SNE06PB):X:S (Fujifilm Wooko Pure Chemicals, model 195-04625)) were weighed in a specified molar ratio. Next, H₂O was added with a solute concentration of 10 wt% relative to the total amount (g). Then, the mixture was heated and stirred at 80°C for 24 hours. It should be noted that Si (High Purity Chemical Research Institute, model SIE23PB) and Sb (Fujifilm Wooko Pure Chemicals, model 013-19222) were used as monomer powders.

[0071] Example 1: Li₂S:Li₂O:Sn:S = 1.7:0.3:1:2 Example 2: Li₂S:Li₂O:Sn:S = 1.5:0.5:1:2 Example 3: Li₂S:Li₂O:Sn:S = 1:1:1:2 Example 4: Li₂S:Li₂O:Sn:Si:S = 1.7:0.3:0.9:0.1:2 Example 5: Li₂S:Li₂O:Sn:Sb:S = 1.65:0.3:0.9:0.1:2 Comparative Example 1: Li₂S:Sn:S = 2:1:2 Comparative Example 2: Li₂S:Li₂O:Sn:S = 1.9:0.1:1:2 Comparative Example 3: Li₂S:Li₂O:Sn:S = 0.5:1.5:1:2 The obtained mixture was vacuum dried at 120°C to obtain solid electrolyte precursor powder. Then, the obtained powder was heat-treated in an inert gas at a heating rate of 10°C / min to 200°C for 3 hours to obtain solid electrolyte powders of various sulfides.

[0072] (Evaluation of Li dissolution)

[0073] First, at 10mm In a zirconium oxide cylinder, 60 mg of Li3PS4 powder was added at a rate of 1 tf / (cm³). 2 Compacted and granulated (min). In addition, 20 mg of the obtained sulfide solid electrolyte was introduced at 3 tf / (cm). 2 The material was compacted (min) and then granulated into two layers.

[0074] Next, 8mm thick particles were introduced into the Li3PS4 side of the fabricated two-layer particle structure. Li metal was introduced into the solid electrolyte side at a depth of 10 mm. SUS (Stainless Used Steel) foil, at 0.5 tf / (cm²) 2 (min) is confined to a closed container.

[0075] Next, a bipolar cell was fabricated with the SUS foil side as the working electrode and the Li foil side as the counter electrode. The Li dissolution and precipitation efficiency was evaluated by scanning from the open-circuit voltage to -0.5V and then to +2.5V. The feasibility of Li dissolution-precipitation and the efficiency calculation were based on the definition in Scientific Reports, 3(2013)1401. The presence or absence of a dissolution-precipitation curve was determined, and the efficiency was calculated based on the charge quantity obtained by cyclic voltammetry.

[0076] Figure 4A This is a graph representing the dissolution-precipitation curve in Comparative Example 1. Figure 4B This is a graph representing the dissolution-precipitation curve in Example 1. In Comparative Example 1, as... Figure 4A As shown in the curves above, during the scan from open-circuit voltage to -0.5V, the battery reduction reaction begins around 1.1V, and no Li precipitation is observed starting from 0V. That is, the battery is in a non-rechargeable state.

[0077] On the other hand, in Example 1, as Figure 4B As shown in the curves above, no reduction reaction was observed in the battery during the scan from open-circuit voltage to -0.5V, but Li deposition was observed starting from 0V. That is, the battery is in a state where it can be properly charged.

[0078] Then, during the scan to +2.5V, the current gradually increased and then decreased, starting from near 0V, resulting in a "bulge"-shaped curve observed on the graph. The appearance of this "bulge"-shaped curve indicates the presence of Li dissolution behavior.

[0079] It should be noted that, as Figure 4BAs shown, for the precipitation curve formed during the scan from the open-circuit voltage to near 0V, a first approximation line (corresponding to the dashed straight line in the graph) is drawn by passing through the precipitation curve at 0V. Furthermore, a second approximation line is drawn on the high-voltage side of the dissolution curve forming the convex curve, by passing through the apex of the convex curve in the dissolution curve formed during the scan from -0.5V to near +2.5V. A third approximation line is drawn on the low-voltage side of the convex curve forming the dissolution curve at 0V. The area of ​​the graph formed by these first, second, and third approximation lines is used as the first calculated area.

[0080] Next, using the intersection of the dissolution-precipitation curves at -0.5V, a fourth approximation line is drawn for both the precipitation curve formed during the scan from 0V to near -0.5V and the dissolution curve formed during the scan from -0.5V to near 0V, using the least squares method. Additionally, a first straight line parallel to the Y-axis of the graph is drawn using -0.05V, the minimum voltage of the scan range. The graph formed by the first, fourth approximation lines, and the first straight line is then used as the second calculated area.

[0081] Then, the ratio of the first calculated area to twice the second calculated area is calculated as the dissolution-precipitation efficiency.

[0082] As a result, a ratio of 42% was calculated in Example 1. It should be noted that, although not illustrated, the same ratios in Examples 2-5 were calculated using the same method.

[0083] On the other hand, in Comparative Example 1, no convex curve was formed in the melting curve during the scan to +2.5V, so the ratio could not be calculated. The above ratio was also calculated in Comparative Examples 2 and 3 using the same method, but since no convex curve was formed as in Comparative Example 1, it could not be obtained at all, so the ratio could not be calculated.

[0084] The measurement results are shown in Table 1 below.

[0085] [Table 1]

[0086] Based on Table 1, the following items can be read.

[0087] By comparing Example 1 with Examples 1-5, compared with Li-Sn-S (LSS) solid electrolytes, if O (oxygen) is further contained and its main crystal structure is tetragonal, the reduction decomposition at a low potential of around 1.0V is suppressed, and the Li precipitation behavior and Li dissolution behavior starting from 0V can be confirmed.

[0088] If the O content in the obtained solid electrolyte is greater than 0.1 mol and less than 1.5 mol, specifically, if it is greater than 0.3 mol and less than 1.0 mol, then the Li precipitation behavior and Li dissolution behavior starting from 0 V can be confirmed.

[0089] It can be seen that when the obtained solid electrolyte further contains Si or Sb, the efficiency of Li precipitation and dissolution can be improved compared with the case where it does not contain Si or Sb.

[0090] The embodiments of the present invention have been described above, but these are merely typical examples. Therefore, the present invention is not limited thereto, and those skilled in the art will readily understand that various approaches can be considered without altering the spirit of the present invention.

[0091] It should be noted that one embodiment of the present invention as described above includes the following preferred embodiments.

[0092] <1>

[0093] A sulfide solid electrolyte, It must contain at least Li, Sn, S, and O. The crystal structure is tetragonal.

[0094] <2>

[0095] According to the sulfide solid electrolyte described in <1> Represented by the Li-MYO formula, In the formula, M contains at least Sn, which is an element selected from Group 14 and Group 15, and Y contains at least S. The content of O is greater than 0.1 mol and less than 1.5 mol.

[0096] <3>

[0097] According to the sulfide solid electrolyte described in <1> or <2>, Represented by the formula Lix-M-Yy-Oz, In the formula, M contains at least Sn, which is an element selected from Group 14 and Group 15, and Y contains at least S. 3<x≤4, y+z≤4, 0.1<z<1.5.

[0098] <4>

[0099] According to the sulfide solid electrolyte described in <3> In the formula, 0.3≤z≤1.0.

[0100] <5>

[0101] According to the sulfide solid electrolyte described in <2> or <3>, The M further comprises Si or Sb.

[0102] <6>

[0103] A solid-state battery, It comprises a positive electrode portion having a positive electrode active material, a negative electrode portion having a negative electrode active material, and a first solid electrolyte portion having a solid electrolyte formed between the positive electrode portion and the negative electrode portion. The device further comprises a second solid electrolyte portion located between the first solid electrolyte portion and the negative electrode portion in the thickness direction, and in contact with both the first solid electrolyte portion and the negative electrode portion, wherein the second solid electrolyte portion is composed of the sulfide solid electrolyte as described in any one of <1> to <5>.

[0104] <7>

[0105] According to the solid-state battery described in <6> The first solid electrolyte section is composed of the sulfide solid electrolyte as described in claim 1.

[0106] <8>

[0107] A solid-state battery, It comprises a positive electrode portion having a positive electrode active material, a negative electrode portion having a negative electrode active material, and a solid electrolyte portion having a solid electrolyte formed between the positive electrode portion and the negative electrode portion. The negative electrode portion comprises the particulate negative electrode active material and the sulfide solid electrolyte as described in any one of <1> to <5>.

[0108] <9>

[0109] A solid-state battery, It comprises a positive electrode portion having a positive electrode active material, a negative electrode portion having a negative electrode active material, and a solid electrolyte portion having a solid electrolyte formed between the positive electrode portion and the negative electrode portion. The particulate negative electrode active material is covered by the sulfide solid electrolyte as described in any one of <1> to <5>.

[0110] <10>

[0111] According to any one of <6> to <9>, a solid-state battery The average charging potential of the negative electrode active material is 1.0V vs Li + / Li and below.

[0112] <11>

[0113] Solid-state battery according to any one of <6> to <10>, The negative electrode active material is at least one selected from the group consisting of C, Si, Sn and Li.

[0114] <12>

[0115] Solid-state battery according to any one of <6> to <11> The negative electrode portion further includes a negative electrode current collector. The sulfide solid electrolyte of claim 1 is capable of contacting the negative electrode active material or the negative electrode current collector.

[0116] Industrial availability

[0117] The solid-state battery of the present invention can be used in various fields of assumed energy storage. Although only examples, the solid-state battery of the present invention can be used in electrical / information / communication fields using mobile devices, etc. (e.g., electrical / electronic fields including mobile phones, smartphones, laptops and small electronic devices such as digital cameras, activity meters, wrist computers, electronic paper, RFID tags, card-type electronic money, smartwatches, etc. or mobile device fields), home / small industrial applications (e.g., power tools, golf carts, home / care / industrial robots), large industrial applications (e.g., forklifts, elevators, port cranes), transportation systems (e.g., hybrid vehicles, electric vehicles, buses, trams, electric-assisted bicycles, electric motorcycles, etc.), power system applications (e.g., various power generation, load regulators, smart grids, general household energy storage systems, etc.), medical applications (medical devices such as headphones and hearing aids), pharmaceutical applications (medical management systems, etc.), as well as IoT fields, space / deep-sea applications (e.g., space probes, underwater research vessels, etc.), etc.

[0118] Explanation of reference numerals in the attached figures

[0119] 1. 1A~1B: Battery; 10: Protective layer; 20: Positive electrode; 21: Positive current collector; 22: Positive active material; 22a: Positive active material particles; 30: Negative electrode; 31: Negative current collector; 32: Negative active material layer; 40, 40A: Solid electrolyte section; 41: First solid electrolyte section; 42: Second solid electrolyte section; 60: Reinforcement section.

Claims

1. A sulfide solid electrolyte, It must contain at least Li, Sn, S, and O. The crystal structure is tetragonal.

2. The sulfide solid electrolyte according to claim 1, wherein, Represented by the Li-MYO formula, In the formula, M contains at least Sn, which is an element selected from Group 14 and Group 15, and Y contains at least S. The content of O is greater than 0.1 mol and less than 1.5 mol.

3. The sulfide solid electrolyte according to claim 1, wherein, Represented by the formula Lix-M-Yy-Oz, In the formula, M contains at least Sn, which is an element selected from Group 14 and Group 15, and Y contains at least S. 3<x≤4, y+z≤4, 0.1<z<1.

5.

4. The sulfide solid electrolyte according to claim 3, wherein, In the formula, 0.3≤z≤1.

0.

5. The sulfide solid electrolyte according to claim 2 or 3, wherein, The M further comprises Si or Sb.

6. A solid-state battery, It comprises a positive electrode portion having a positive electrode active material, a negative electrode portion having a negative electrode active material, and a first solid electrolyte portion having a solid electrolyte formed between the positive electrode portion and the negative electrode portion. The device further comprises a second solid electrolyte portion, which is located between the first solid electrolyte portion and the negative electrode portion in the thickness direction and is in contact with both the first solid electrolyte portion and the negative electrode portion. The second solid electrolyte portion is composed of the sulfide solid electrolyte as described in claim 1.

7. The solid-state battery according to claim 6, wherein, The first solid electrolyte section is composed of the sulfide solid electrolyte as described in claim 1.

8. A solid-state battery, It comprises a positive electrode portion having a positive electrode active material, a negative electrode portion having a negative electrode active material, and a solid electrolyte portion having a solid electrolyte formed between the positive electrode portion and the negative electrode portion. The negative electrode portion comprises the particulate negative electrode active material and the sulfide solid electrolyte as described in claim 1.

9. A solid-state battery, It comprises a positive electrode portion having a positive electrode active material, a negative electrode portion having a negative electrode active material, and a solid electrolyte portion having a solid electrolyte formed between the positive electrode portion and the negative electrode portion. The particulate negative electrode active material is covered by the sulfide solid electrolyte as described in claim 1.

10. The solid-state battery according to any one of claims 6 to 9, wherein, The average charging potential of the negative electrode active material is 1.0V vs Li + / Li and below.

11. The solid-state battery according to claim 10, wherein, The negative electrode active material is at least one selected from the group consisting of C, Si, Sn and Li.

12. The solid-state battery according to any one of claims 6 to 9, wherein, The negative electrode portion further includes a negative electrode current collector. The sulfide solid electrolyte of claim 1 is capable of contacting the negative electrode active material or the negative electrode current collector.

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