Sulfide solid electrolyte

Abstract

A solid-state battery according to one embodiment of the present disclosure provides a sulfide solid electrolyte that contains at least Li, Sn, S, and O, and has a tetragonal crystal structure.

Description

Sulfide solid electrolyte

[0001] This disclosure relates to sulfide solid electrolytes.

[0002] Rechargeable batteries, which can be repeatedly charged and discharged, have long been used in a variety of applications. For example, rechargeable batteries are used as power sources for electronic devices such as smartphones and laptop computers.

[0003] In secondary batteries, a liquid electrolyte is generally used as a medium for ion transfer that contributes to charging and discharging. In other words, so-called electrolyte solutions are used in secondary batteries. However, safety is generally required in such secondary batteries in terms of preventing electrolyte leakage. Furthermore, since organic solvents used in electrolyte solutions are flammable substances, safety is also required in that respect.

[0004] Therefore, research is underway on solid-state batteries that use solid electrolytes instead of liquid electrolytes.

[0005] K. Kanazawa, et al., Inorg. Chem., 2018, 57, 9925-9930.

[0006] In this context, sulfide solid electrolytes, which exhibit excellent ionic conductivity and moldability at room temperature, are sometimes used as the solid electrolyte. However, since sulfide solid electrolytes can react with moisture to generate harmful hydrogen sulfide, there is a need for sulfide solid electrolytes with excellent water resistance.

[0007] In this regard, Li-Sn-S (LSS) solid electrolytes have attracted attention as sulfide solid electrolytes with excellent water resistance. However, compared to conventionally known Li-P-S (LPS) solid electrolytes, LSS is partially reductively decomposed at a low potential of about 1.0 V, resulting in low reduction resistance. Therefore, the leaching efficiency of Li metal is considerably low, making it difficult to use LSS in combination with commonly used negative electrode active materials in solid-state batteries.

[0008] This disclosure has been made in view of the above issues. Specifically, this disclosure aims to provide a sulfide solid electrolyte capable of improving reduction resistance.

[0009] In order to achieve the above object, a solid battery according to an embodiment of the present disclosure provides a sulfide solid electrolyte that contains at least Li, Sn, S, and O and has a tetragonal crystal structure.

[0010] According to the sulfide solid electrolyte of an embodiment of the present disclosure, it is possible to improve reduction resistance.

[0011] FIG. 1 is a cross-sectional view schematically showing a solid battery including a sulfide solid electrolyte according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view schematically showing a solid battery including a sulfide solid electrolyte according to an embodiment of the present disclosure. FIG. 3 is a cross-sectional view schematically showing a solid battery including a sulfide solid electrolyte according to an embodiment of the present disclosure. FIG. 4A is a graph showing a dissolution / precipitation curve in Comparative Example 1. FIG. 4B is a graph showing a dissolution / precipitation curve in Example 1.

[0012] Hereinafter, the solid battery of the present disclosure will be described in detail. Although the description will be made with reference to the drawings as necessary, the illustrated content is merely schematic and exemplary for the understanding of the present disclosure, and the appearance, dimensional ratios, etc. may be different from the actual ones.

[0013] As used in this specification, the "cross-sectional view" is based on the form captured from a direction substantially perpendicular to the stacking direction in the stacked structure of the solid battery (specifically, the form when cut along a plane parallel to the thickness direction of the layer). Also, as used in this specification, the "planar view" or "planar view shape" is based on the schematic view when the object is viewed from above or below along the thickness direction of such a layer (i.e., the above-mentioned stacking direction).

[0014] The "vertical direction" and "horizontal direction" directly or indirectly used in this specification correspond to the vertical direction and horizontal direction in the drawing, respectively. Unless otherwise specified, the same reference numerals or symbols indicate the same members / parts or the same meaning content. In a preferred embodiment, it can be understood that the vertically downward direction (i.e., the direction in which gravity acts) corresponds to the "downward direction", and the opposite direction corresponds to the "upward direction".

[0015] In the present disclosure, the "solid-state battery" broadly refers to a battery whose components are made of solids, and narrowly refers to an all-solid-state battery whose components (particularly preferably all components) are made of solids. In a certain preferred embodiment, the solid-state battery in the present disclosure is a laminated solid-state battery configured such that each layer forming a battery constituent unit is laminated on top of one another. The "solid-state battery" includes, in addition to primary batteries, so-called "secondary batteries" that can be repeatedly charged and discharged. The "secondary battery" should not be overly restricted by its name, and may include, for example, energy storage devices and the like. Hereinafter, a solid-state battery that is a secondary battery will be taken as an example to describe the specific configuration of the solid-state battery.

[0016] The features of the present disclosure relate to the positive electrode part and the solid electrolyte part included in the solid-state battery. Hereinafter, first, for understanding the overall structure of the solid-state battery, the basic configuration of the solid-state battery of the present disclosure will be described. However, the configuration of the solid-state battery described here is merely an example for understanding the invention and does not limit the invention.

[0017] [Basic Configuration of Solid-State Battery] FIG. 1 is a cross-sectional view schematically showing a solid-state battery including a sulfide solid electrolyte according to an embodiment of the present disclosure. It is a cross-sectional view schematically showing a solid-state battery according to an embodiment of the present invention. The solid-state battery has at least an electrode part including a positive electrode part and a negative electrode part and a solid electrolyte part. Specifically, as shown in FIG. 1, the solid-state battery 1 includes a battery constituent unit composed of a positive electrode part 20, a negative electrode part 30, and at least a solid electrolyte part 40 intervening therebetween.

[0018] The solid-state battery 1 according to the present invention includes at least one battery constituent unit composed of a positive electrode part 20, a negative electrode part 30, and a solid electrolyte part intervening therebetween along the stacking direction Z. The positive electrode part 20 and the negative electrode part 30 are alternately stacked via the solid electrolyte part 40.

[0019] The positive electrode part 20 includes at least a positive electrode active material layer 22. The positive electrode part may further include a solid electrolyte. On the other hand, the negative electrode part 30 includes at least a negative electrode active material layer 32. The negative electrode part 30 may further include a solid electrolyte. The positive electrode part 20 and the negative electrode part 30 having such a configuration can also be referred to as a "composite positive electrode body" and a "composite negative electrode body", respectively.

[0020] The positive electrode active material and the negative electrode active material are substances that participate in the transfer of electrons in a solid-state battery. Ions move (conduct) between the positive electrode part and the negative electrode part through the solid electrolyte, and charge and discharge are performed by the transfer of electrons. It is particularly preferable that the active materials of the positive electrode part and the negative electrode part can occlude and release 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 part 20 and the negative electrode part 30 through the solid electrolyte to perform charge and discharge of the battery.

[0021] Examples of the positive electrode active material included in the positive electrode part 20 include at least one selected from the group consisting of a lithium-containing phosphate compound having a NASICON-type structure, a lithium-containing phosphate compound having an olivine-type structure, a lithium-containing layered oxide, and a lithium-containing oxide having a spinel-type structure.

[0022] An example of the lithium-containing phosphate compound having a NASICON-type structure is Li ３ V ２ (PO ４ ) ３ and the like. Examples of the lithium-containing phosphate compound having an olivine-type structure include Li ３ Fe ２ (PO ４ ) ３ , LiFePO ４ , and / or LiMnPO ４ and the like. Examples of the lithium-containing layered oxide include LiCoO ２ , and / or LiCo １／３ Ni １／３ Mn １／３ O ２ and the like. Examples of the lithium-containing oxide having a spinel-type structure include LiMn ２ O４ , and / or LiNi ０．５ Mn １．５ O ４ Examples include the following. The type of lithium compound is not particularly limited, but may be, for example, lithium transition metal composite oxides and lithium transition metal phosphate compounds. Lithium transition metal composite oxides are a general term for oxides that contain lithium and one or more transition metal elements as constituent elements, and lithium transition metal phosphate compounds are a general term for phosphate compounds that contain lithium and one or more transition metal elements as constituent elements. The type of transition metal element is not particularly limited, but may be, for example, cobalt (Co), nickel (Ni), manganese (Mn), and iron (Fe).

[0023] In addition, the positive electrode active material may be, for example, an oxide, disulfide, chalcogenide, or conductive polymer. Oxides may be, for example, titanium oxide, vanadium oxide, or manganese dioxide. Disulfides may be, for example, titanium disulfide or molybdenum sulfide. Chalcogenides may be, for example, niobium selenide. Conductive polymers may be, for example, disulfide, polypyrrole, polyaniline, polythiophene, polyparastyrene, polyacetylene, or polyacene.

[0024] (Negative electrode active material) Examples of negative electrode active materials include oxides containing 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), carbon materials such as graphite, graphite-lithium compounds, lithium alloys, lithium-containing phosphate compounds having a NASCICON-type structure, lithium-containing phosphate compounds having an olivine-type structure, and lithium-containing oxides having a spinel-type structure. An example of a lithium alloy is Li-Al. An example of a lithium-containing phosphate compound having a NASCICON-type structure is Li ３ V ２ (PO ４ ) ３ , and / or LiTi ２ (PO ４ )３ Examples include Li ３ Fe ２ (PO ４ ) ３ , and / or LiCuPO ４ Examples include Li ４ Ti ５ O １２ These are some examples.

[0025] In addition, in the solid-state battery 1, the positive electrode portion 20 and the negative electrode portion 30 may be made of the same material, or they may be made of different materials.

[0026] The thickness of the positive electrode portion 20 and the negative electrode portion 30 is not particularly limited, but for example, they may be 2 μm or more and 50 μm or less, and more particularly 5 μm or more and 30 μm or less, respectively.

[0027] (Positive electrode current collector layer / Negative electrode current collector layer) Although not essential elements of the electrode section, the positive electrode section 20 and the negative electrode section 30 may each include a positive electrode current collector 21 and a negative electrode current collector 31. The positive electrode current collector 21 and the negative electrode current collector 31 may each be in the form of foil. Parts of the positive electrode current collector 21 and the negative electrode current collector 31 may each be exposed to the outside of the solid battery 1. For example, the positive electrode current collector 21 and the negative electrode current collector 31 may each have an electrical connection part for electrically connecting to the outside. In one embodiment, the solid battery may further include an end face electrode (not shown) provided on the end face of the laminate of the positive electrode section, the negative electrode section and the solid electrolyte section, and electrically connected to each of the positive electrode current collector 21 and the negative electrode current collector 31.

[0028] As described above, the positive electrode current collector 21 and the negative electrode current collector 31 are not essential in a solid-state battery, and solid-state batteries without such positive electrode current collectors 21 and negative electrode current collectors 31 are also conceivable. In other words, the solid-state battery of this disclosure may be a so-called current collector-less solid-state battery.

[0029] (Solid Electrolyte Section) The solid electrolyte section 40 includes a solid electrolyte through which ions contributing to charging and discharging, such as lithium ions or sodium ions, can conduct. In particular, the solid electrolyte section 40 that forms a battery component unit in the solid battery 1 may form a layer through which lithium ions can conduct between the positive electrode section 20 and the negative electrode section 30. The solid electrolyte section 40 only needs to be provided between the positive electrode section 20 and the negative electrode section 30. In other words, the solid electrolyte section 40 may exist around the positive electrode section 20 and / or the negative electrode section 30 so as to protrude from between the positive electrode section 20 and the negative electrode section 30.

[0030] The thickness of the solid electrolyte portion 40 is not particularly limited. The thickness of the solid electrolyte portion 40 located between the positive electrode portion 20 and the negative electrode portion 30 may be, for example, 1 μm or more and 15 μm or less, and particularly 1 μm or more and 5 μm or less.

[0031] The outer surface of the solid-state battery 1 may be covered with a protective layer 10. The protective layer 10 is a layer provided to physically and chemically protect the solid-state battery 1. The protective layer 10 may be provided so as to overlap the laminate of the positive electrode portion 20, the negative electrode portion 30, and the solid electrolyte portion 40 in a plan view. That is, as shown in Figure 1, the protective layer 10 may be provided on both sides of the solid-state 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, and may be, for example, resin, glass, ceramics, etc.

[0032] The solid-state battery 1 may further include reinforcing portions 60 provided on opposing sides in a direction intersecting the stacking direction Z. The reinforcing portions 60 may contribute to preventing short circuits in the solid-state battery 1. The reinforcing portions 60 are not particularly limited as long as they are insulators, and may be made of, for example, resin, glass, ceramics, etc.

[0033] [Features of this disclosure] This disclosure is characterized by a solid electrolyte, which is a component of the solid-state battery described above. This disclosure is characterized in that a sulfide solid electrolyte, particularly a Li-Sn-S (LSS) system solid electrolyte, may be used as the solid electrolyte.

[0034] In this disclosure, the sulfide solid electrolyze is characterized by containing at least Li (lithium), Sn (tin), S (sulfur), and O (oxygen), and having a tetragonal crystal structure. That is, the sulfide solid electrolyze of this disclosure is characterized by containing even more O (oxygen) than conventional Li-Sn-S (LSS) solid electrolytes, and further by having a tetragonal crystal structure as its main component.

[0035] Having these characteristics makes it possible to suppress reductive decomposition at high potentials of around 1.0V while ensuring the water resistance of LSS-based solid electrolytes, thereby improving reduction resistance. This allows for optimal dissolution and extraction efficiency of Li metal, and enables optimal charging and discharging of solid-state batteries.

[0036] Specifically, the sulfide solid electrophores of this disclosure are represented by the formula Li-M-Y-O, where M is at least Sn and one or more elements selected from Groups 14 and 15, and Y is at least S. Furthermore, the O content in the above formula is greater than 0.1 moles and less than 1.5 moles.

[0037] More specifically, the sulfide solid electrophores of this disclosure are represented by the formula Lix-M-Yy-Oz, where M is at least Sn and one or more elements selected from Groups 14 and 15, and Y is at least S. Furthermore, in the formula, 3 < x ≤ 4, y + z ≤ 4, and 0.1 < z < 1.5.

[0038] Preferably, in the above formula, 0.3 ≤ z ≤ 1.0. In this case, the efficiency of Li deposition and dissolution can be suitably secured by several tens of percent, and the charging and discharging of the solid-state battery can be suitably performed.

[0039] More preferably, M in the above formula further comprises Si or Sb. In this case, the efficiency of Li deposition and dissolution can be increased, and charging and discharging of the solid-state battery can be performed more favorably.

[0040] In one example, as shown in Figure 1 above, the solid electrolyte portion 40 comprises a "first solid electrolyte portion 42" having a solid electrolyte formed between the positive electrode portion 20 and the negative electrode portion 30, and a "second solid electrolyte portion 41" interposed between the first solid electrolyte portion 42 and the negative electrode portion 30, and in contact with the first solid electrolyte portion 42 and the negative electrode portion 30, respectively. Furthermore, the "second solid electrolyte portion 41" is characterized in that it is composed of the sulfide solid electrolyte of the present disclosure described above.

[0041] According to these characteristics, while ensuring the water resistance of the LSS-based solid electrolyte, reductive decomposition at high potentials of about 1.0 V is suppressed, thereby improving reduction resistance. This allows for favorable dissolution and extraction efficiency of Li metal. Furthermore, from the viewpoint of further optimizing this dissolution and extraction efficiency, it is preferable that the "first solid electrolyte portion 42" described above is also composed of the sulfide solid electrolyte of this disclosure.

[0042] In another example, as shown in Figure 2, the negative electrode active material layer 32A of the negative electrode portion 30A may include particulate negative electrode active material 32a and the sulfide solid electrolyte 32b of this disclosure. In this case as well, while ensuring the water resistance of the LSS-based solid electrolyte, it is possible to suppress reductive decomposition at a high potential of about 1.0 V and improve reduction resistance. This makes it possible to suitably ensure the dissolution and extraction efficiency of Li metal.

[0043] In another example, as shown in Figure 3, the negative electrode active material layer 32B of the negative electrode portion 30B may include particulate negative electrode active material 32a, the sulfide solid electrolyte 32b of this disclosure covering its surface, and a first solid electrolyte 32c. In this case as well, while ensuring the water resistance of the LSS-based solid electrolyte, it is possible to suppress reductive decomposition at a high potential of about 1.0 V and improve reduction resistance. This makes it possible to suitably ensure the leaching and extraction efficiency of Li metal.

[0044] The average charging potential of the negative electrode active material is preferably 1.0 V vs Li+ / Li or less. This allows the output voltage of the battery to be increased. However, if the sulfide solid electrolyte of this disclosure is not used, when the average charging potential of the negative electrode active material is 1.0 V vs Li+ / Li or less, it will be lower than the potential at which Li4SnS4 is reduced, causing the solid electrolyte in contact with the negative electrode active material to decompose and the discharge characteristics to deteriorate.

[0045] In this regard, by using the solid electrolyte of this disclosure as the solid electrolyte in contact with the negative electrode active material, it is possible to improve discharge characteristics while suppressing reduction of the solid electrolyte in contact with the negative electrode active material, even when the average charging potential of the negative electrode active material is 1.0 V vs Li+ / Li or less.

[0046] The average charging potential of the negative electrode active material refers to the average negative electrode potential in the charging curve obtained from a charging test of a half-cell to which the negative electrode active material being measured is applied. For example, by performing a charging measurement on the above half-cell under the following conditions, the average value of the negative electrode potential from the start to the end of charging in the resulting charging curve can be measured as the average charging potential of the negative electrode active material. Charging rate: 0.1C Charging method: CC Charging termination voltage: 0.03V

[0047] The negative electrode active material layer 32 may be at least one selected from the group consisting of carbon (C), tin (Sn), silicon (Si), and Li (lithium) metal. In this case, the average charging potential of the negative electrode active material can be set to 1.0 V vs Li+ / Li or less, thereby improving the discharge characteristics.

[0048] Furthermore, from the viewpoint of suppressing the reduction of the solid electrolyte that comes into contact with the negative electrode active material, it is preferable that the sulfide solid electrolyte of this disclosure is capable of coming into contact with the negative electrode active material.

[0049] The following describes embodiments of this disclosure.

[0050] (Preparation of sulfide solid electrolyte) First, in an atmosphere with a dew point temperature of -60 degrees Celsius or lower, the raw material reagent Li ２ S (Sigma-Aldrich, model number 213241): Li ２The molar ratio of O (Sigma-Aldrich, 374725 (model number)): Sn (High Purity Chemical Laboratory, SNE06PB (model number)): X:S (Fujifilm Wako Pure Chemical Industries, 195-04625 (model number)) was weighed to the predetermined ratio. Next, H was added so that the solute concentration was 10 wt% relative to the total amount (g). ２ O was injected. Then, the mixture was heated and stirred at 80°C for 24 hours. Si (manufactured by Kojun Chemical Laboratory, model number SIE23PB) and Sb (manufactured by Fujifilm Wako Pure Chemical Industries, model number 013-19222) were used as individual powders.

[0051] Example 1: Li ２ S: Li ２ O:Sn:S = 1.7:0.3:1:2 • Example 2: Li ２ S: Li ２ O:Sn:S = 1.5:0.5:1:2 • Example 3: Li ２ S: Li ２ O:Sn:S = 1:1:1:2 • Example 4: Li ２ S: Li ２ O:Sn:Si:S = 1.7:0.3:0.9:0.1:2 • Example 5: Li ２ S: Li ２ O:Sn:Sb:S=1.65:0.3:0.9:0.1:2 Comparative example 1: Li ２ S:Sn:S=2:1:2 Comparative example 2: Li ２ S: Li ２ O:Sn:S=1.9:0.1:1:2 Comparative example 3: Li ２ S: Li ２ O:Sn:S=0.5:1.5:1:2

[0052] The resulting mixture was vacuum-dried at 120°C to obtain a solid electrolyte precursor powder. The obtained powder was then heat-treated in an inert gas at a heating rate of 10°C / min to 200°C for 3 hours to obtain each sulfide solid electrolyte powder.

[0053] (Li dissolution analysis and extraction evaluation) First, in a 10 mm diameter zirconia cylinder, Li ３ PS ４ 60 mg of the powder at 1 tf / cm ２The mixture was then compacted into pellets at a rate of min(1 / min). Furthermore, 20 mg of the obtained sulfide solid electrolyte was introduced at a rate of 3 tf / cm². ２ The pellets were compacted using a 2-layer press (min).

[0054] Next, the Li of the two-layer pellet that was prepared ３ PS ４ An 8 mm diameter Li metal foil was introduced to the side, and a 10 mm diameter SUS (Stainless Used Steel) foil was introduced to the resulting solid electrolyte side, with a concentration of 0.5 tf / cm². ２ - The person was restrained in a sealed container (min).

[0055] Next, a two-electrode cell was constructed with the SUS foil side as the working electrode and the Li foil side as the counter electrode. The Li dissolution and deposition efficiency was evaluated by sweeping from the open-circuit voltage down to -0.5V, and then sweeping up to +2.5V. For determining whether Li dissolution and deposition were possible and calculating the efficiency, the presence or absence of a dissolution / deposition curve was determined based on the definition in Scientific Reports, 3 (2013) 1401, and the efficiency was calculated from the charge amount obtained by cyclic voltammetry.

[0056] Figure 4A is a graph showing the dissolution and precipitation curve in Comparative Example 1. Figure 4B is a graph showing the dissolution and precipitation curve in Example 1. In Comparative Example 1, as shown in Figure 4A, in the above curve, the reduction reaction of the battery started at around 1.1V during the process of sweeping from the open-circuit voltage down to -0.5V, and no Li precipitation was observed from 0V. In other words, the battery was in a state where it could not be charged.

[0057] On the other hand, in Example 1, as shown in Figure 4B, in the curve described above, no reduction reaction behavior of the battery was observed during the sweep from the open-circuit voltage down to -0.5V, and Li deposition behavior was observed from 0V. That is, the battery was in a state where it could be suitably charged.

[0058] Subsequently, during the sweep process up to +2.5V, the current gradually increased and then decreased, and a "bump"-shaped curve was observed on the graph from around 0V. The occurrence of this "bump"-shaped curve allowed us to conclude that Li was dissolving.

[0059] As shown in Figure 4B, a first approximation line (corresponding to the dotted line in the graph) is drawn so as to pass through the deposition curve formed during the sweep from the open-circuit voltage to near 0V. A second approximation line is drawn on the high-voltage side curve that forms the bump-shaped curve in the dissolution curve formed during the sweep from -0.5V to near +2.5V, and a third approximation line is drawn on the low-voltage side curve that forms the bump-shaped curve so as to pass through the dissolution curve at 0V. The area of ​​the figure formed by the first, second, and third approximation lines in this way is taken as the first calculated area. Next, a fourth approximation line is drawn using the least squares method on both the deposition curve formed during the sweep from 0V to near -0.5V and the dissolution curve formed when sweeping from -0.5V to near 0V, so as to pass through the intersection of the dissolution and deposition curves at -0.5V. Furthermore, a first straight line parallel to the Y-axis of the graph is drawn so as to pass through -0.05V, which is the minimum voltage in the sweep range. The figure formed by the first and fourth approximation lines and the first straight line is used as the second calculated area. The ratio of the first calculated area to twice the area of ​​the second calculated area is then calculated and used as the dissolution and precipitation efficiency. As a result, a ratio of 42% was calculated for Example 1. Although not shown in the figures, the above ratios for Examples 2 to 5 were calculated using a similar method.

[0060] On the other hand, in Comparative Example 1, a bulge-like curve was not formed in the dissolution curve during the sweep process up to +2.5V, so the ratio could not be calculated. The same method was used to calculate the above ratio in Comparative Examples 2 and 3, but as with Comparative Example 1, a bulge-like curve was not formed, so the ratio could not be calculated.

[0061] The measurement results are shown in Table 1 below.

[0062] [Table 1]

[0063] From Table 1, the following points could be inferred: • By comparing Comparative Example 1 with Examples 1-5, it was found that when the solid electrolyte contains more oxygen (O) compared to the Li-Sn-S (LSS) system, and its main crystal structure is tetragonal, reductive decomposition at low potentials of around 1.0 V is suppressed, and the Li precipitation behavior from 0 V and the Li dissolution behavior from 0 V can be confirmed. • When the O content in the obtained solid electrolyte is greater than 0.1 moles and less than 1.5 moles, specifically between 0.3 moles and 1.0 moles, the Li precipitation behavior from 0 V and the Li dissolution behavior from 0 V can be confirmed. • It was found that when the obtained solid electrolyte further contains Si or Sb, the efficiency of Li precipitation and dissolution can be increased compared to when it does not contain these elements.

[0064] 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 easily understand that various embodiments are conceivable without altering the essence of the invention.

[0065] Furthermore, the embodiment described above includes the following preferred embodiments: <1> A sulfide solid electrolyte comprising at least Li, Sn, S, and O, and having a tetragonal crystal structure. <2> The sulfide solid electrolyte according to <1>, represented by the formula Li-M-Y-O, where M comprises at least Sn and is one or more elements selected from Group 14 and Group 15, Y comprises at least S, and the O content is greater than 0.1 moles and less than 1.5 moles. <3> The sulfide solid electrolyte according to <1> or <2>, represented by the formula Lix-M-Yy-Oz, where M comprises at least Sn and is one or more elements selected from Group 14 and Group 15, Y comprises at least S, and 3 < x ≤ 4, y + z ≤ 4, and 0.1 < z < 1.5. <4> The sulfide solid electrolyte according to <3>, wherein 0.3 ≤ z ≤ 1.0 in the formula. <5> The sulfide solid electrolyte according to <2> or <3>, wherein M further comprises Si or Sb. <6> A solid battery comprising 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, further comprising a second solid electrolyte portion interposed between the first solid electrolyte portion and the negative electrode portion in the thickness direction and in contact with the first solid electrolyte portion and the negative electrode portion, wherein the second solid electrolyte portion is composed of the sulfide solid electrolyte according to any one of <1> to <5>. <7> The solid battery according to <6>, wherein the first solid electrolyte portion is composed of the sulfide solid electrolyte according to claim 1. <8> A solid-state battery comprising 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, wherein the negative electrode portion comprises particulate negative electrode active material and the sulfide solid electrolyte described in any of <1> to <5>. <9> A solid-state battery comprising 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, wherein the particulate negative electrode active material is covered with the sulfide solid electrolyte described in any of <1> to <5>. <10> The average charging potential of the negative electrode active material is 1.0V vs Li ＋A solid battery according to any one of <6> to <9>, wherein the ratio of the negative electrode active material is less than or equal to / Li. <11> A solid battery according to any one of <6> to <10>, wherein the negative electrode active material is at least one selected from the group consisting of C, Si, Sn, and Li. <12> A solid battery according to any one of <6> to <11>, wherein the negative electrode portion further comprises a negative electrode current collector, and the sulfide solid electrolyte according to claim 1 is in contact with the negative electrode active material or the negative electrode current collector.

[0066] The solid-state battery of the present invention can be used in a variety of fields where energy storage is anticipated. While these are merely examples, the solid-state battery of the present invention can be used in the electrical, information, and communication fields where mobile devices are used (e.g., the electrical and electronic equipment field or mobile device field, including small electronic devices such as mobile phones, smartphones, laptops and digital cameras, activity trackers, arm computers, electronic paper, RFID tags, card-type electronic money, and smartwatches), household and small-scale industrial applications (e.g., power tools, golf carts, household, caregiving, and industrial robots), large-scale industrial applications (e.g., forklifts, elevators, and port cranes), transportation systems (e.g., hybrid vehicles, electric vehicles, buses, trains, electric-assist bicycles, electric motorcycles, etc.), power grid applications (e.g., various power generation, road conditioners, smart grids, and general household energy storage systems), medical applications (medical equipment such as earphones and hearing aids), pharmaceutical applications (medication management systems, etc.), as well as IoT, space, and deep-sea applications (e.g., space probes, submersible research vessels, etc.).

[0067] 1, 1A-1B Battery 10 Protective layer 20 Positive electrode section 21 Positive electrode current collector 22 Positive electrode active material 22a Positive electrode active material particles 30 Negative electrode section 31 Negative electrode current collector 32 Negative electrode 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 containing at least Li, Sn, S, and O, and having a tetragonal crystal structure.

2. The sulfide solid electrolyte according to claim 1, represented by the formula Li-M-Y-O, where M is at least Sn and one or more elements selected from Group 14 and Group 15, Y is at least S, and the content of O is greater than 0.1 moles and less than 1.5 moles.

3. The sulfide solid electrolyte according to claim 1, represented by the formula Lix-M-Yy-Oz, where M is at least Sn and one or more elements selected from Groups 14 and 15, and Y is at least S, with 3 < x ≤ 4, y + z ≤ 4, and 0.1 < z < 1.

5.

4. The sulfide solid electrolyte according to claim 3, wherein 0.3 ≤ z ≤ 1.0 in the formula.

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

6. A solid-state battery comprising 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, further comprising a second solid electrolyte portion interposed between the first solid electrolyte portion and the negative electrode portion in the thickness direction and in contact with the first solid electrolyte portion and the negative electrode portion, wherein the second solid electrolyte portion is made of the sulfide solid electrolyte described in claim 1.

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

8. A solid-state battery comprising 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, wherein the negative electrode portion comprises particulate negative electrode active material and the sulfide solid electrolyte described in claim 1.

9. A solid-state battery comprising 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, wherein the particulate negative electrode active material is covered with the sulfide solid electrolyte described in claim 1.

10. The average charging potential of the negative electrode active material is 1.0V vs Li ＋ A solid battery according to any one of claims 6 to 9, wherein the value is less than or equal to / Li.

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 battery according to any one of claims 6 to 9, wherein the negative electrode portion further comprises a negative electrode current collector, and the sulfide solid electrolyte according to claim 1 is in contact with the negative electrode active material or the negative electrode current collector.

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