Glass, method for producing same, crystallized glass, sulfide solid electrolyte, electrode mixture, solid electrolyte layer, and lithium ion secondary battery

Abstract

The present invention relates to glass which contains, as elements that constitute a cationic component, Li, P, and a specific element M as an optional element, and also contains, as elements that constitute an anionic component, S and at least one of a specific element X and a specific element Y as an optional element, and which is represented by the composition formula Li(a + c - m × d - y × e)MdP(1 - d)SbXcYe. In the composition formula, m is the valence of the element M, y is the valence of the element Y, and a to e in the composition formula satisfy the relational expressions -5.30 < a - 2b - 5d < -5.00, 1.50 < a < 7.50, c ≥ 0, 0 ≤ d ≤ 4 / 7, and e ≥ 0.

Description

Glass and its manufacturing method, crystallized glass, sulfide solid electrolyte, electrode composite material, solid electrolyte layer, and lithium-ion secondary battery

[0001] This invention relates to glass, a method for producing the same, crystallized glass, sulfide solid electrolyte, electrode composite material, solid electrolyte layer, and lithium-ion secondary battery.

[0002] Lithium-ion rechargeable batteries are widely used in portable electronic devices such as mobile phones and laptop computers. Traditionally, lithium-ion rechargeable batteries have used liquid electrolytes. However, in recent years, all-solid-state lithium-ion rechargeable batteries, which use solid electrolytes, have attracted attention due to the potential for improved safety, faster charging and discharging, and smaller case sizes.

[0003] Sulfide-based glass and crystallized glass obtained by crystallizing it are known as solid electrolyte materials for all-solid-state lithium-ion secondary batteries. Patent Document 1 provides a solid electrolyte that is resistant to hydrolysis and has high ionic conductivity, using Li as the sulfide solid electrolyte. ２ S / P ２ S ５ Sulfide-based glasses where / LiI = 63 / 21 / 16 or 52 / 17 / 31, or Li ２ S / P ２ S ５ A sulfide-based glass ceramic is disclosed, which is formed by crystallizing a portion of a sulfide-based glass with a ratio of / LiBr = 64 / 21 / 14.

[0004] Japanese Patent Application Publication No. 2018-049834

[0005] In all-solid-state lithium-ion secondary batteries, high confinement pressure is necessary to reduce resistance at the interfaces between materials constituting the lithium-ion secondary battery, such as the solid electrolyte and electrode active material. Furthermore, expansion and contraction due to charging and discharging of the negative electrode can cause the solid electrolyte and electrode active material to break or crack, which can degrade the battery's performance. In contrast, as described in Patent Document 1, using sulfide-based glass or its crystallized glass as the solid electrolyte material is useful in terms of the above-mentioned confinement pressure and prevention of breakage and cracking due to its high flexibility.

[0006] However, in sulfide glasses and their crystallized glasses that serve as solid electrolytes, further improvement in ionic conductivity is required.

[0007] Therefore, an object of the present invention is to provide a glass having a new composition that exhibits high lithium ion conductivity and a method for producing the same. Another object is to provide a crystallized glass useful as a sulfide solid electrolyte in which at least a part of the above glass is crystallized. Furthermore, an object is to provide a sulfide solid electrolyte, an electrode composite material, a sulfide solid electrolyte layer, and a lithium ion secondary battery including the above glass or the above crystallized glass.

[0008] The present invention is as follows. [1] As elements constituting the cation component, it contains Li, P, and an element M as an optional element, as elements constituting the anion component, it contains S, and as an optional element, at least one of the elements X and Y, the element M is at least one element selected from the group consisting of Sn, Sb, Si, Ge, Ga, Al, B, C, Mg, Ca, Sr, and Ba, the element X is at least one element selected from the group consisting of F, Cl, Br, and I, the element Y is at least one element selected from the group consisting of O, Se, N, and C, Li(a + c - m×d - y×e)M ｄ P （１－ｄ） S ｂ X ｃ Y ｅ[1] A glass represented by the compositional formula, in which m is the valence of the element M and y is the valence of the element Y, and a to e in the compositional formula satisfy the following relationships: -5.30 < a - 2b - 5d < -5.00, 1.50 < a < 7.50, c ≥ 0, 0 ≤ d ≤ 4 / 7, and e ≥ 0. [2] The glass according to [1], wherein c > 0 in the compositional formula. [3] The glass according to [1] or [2], wherein d > 0 in the compositional formula. [4] The glass according to any one of [1] to [3], wherein e > 0 in the compositional formula. [5] A crystallized glass containing a crystalline phase derived from any one of [1] to [4]. [6] A sulfide solid electrolyte containing the glass according to any one of [1] to [4]. [7] A sulfide solid electrolyte containing the crystallized glass according to [5]. [8] An electrode mixture containing the sulfide solid electrolyte according to [6] or [7]. A solid electrolyte layer comprising the sulfide solid electrolyte described in [9], [6], or [7]. A lithium-ion secondary battery comprising the sulfide solid electrolyte described in

[10] , [6], or [7]. A method for producing glass according to any one of [1] to [4], comprising: mixing raw materials to obtain a raw material mixture comprising Li, P, and S, and as an optional component, at least one element selected from the group consisting of the element M, the element X, and the element Y; heating the raw material mixture at 400 to 1000°C in a gas atmosphere containing S to obtain a molten material; and cooling and solidifying the molten material to obtain the glass. A method for producing glass according to any one of [1] to [4], comprising: mixing raw materials to obtain a raw material mixture containing Li, P, and S, and as an optional component, at least one element selected from the group consisting of the element M, the element X, and the element Y; heating the raw material mixture at 400 to 1000°C to obtain a molten product; and cooling and solidifying the molten product to obtain the glass, wherein the raw materials are mixed such that the ratio of the value of b in the raw material mixture exceeds 100% of the value of b in the composition formula such that a - 2b - 5d = -5.00.

[0009] According to the present invention, a glass with a new composition exhibiting high lithium-ion conductivity can be obtained. Furthermore, by crystallizing at least a portion of this glass, a crystallized glass useful as a sulfide solid electrolyte can be obtained. Therefore, by using the above glass or a solid electrolyte containing the above crystallized glass in an electrode composite, a solid electrolyte layer, or a lithium-ion secondary battery, good battery characteristics can be achieved.

[0010] Figure 1 is a flow chart showing the manufacturing method of glass according to this embodiment. Figure 2 is a flow chart showing the manufacturing method of crystallized glass according to this embodiment.

[0011] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified and implemented as appropriate without departing from the spirit of the invention. Furthermore, the "~" indicating a numerical range is used to mean that the numbers written before and after it are included as the lower limit and upper limit.

[0012] As a result of diligent research, the inventors have found that by employing methods such as heating and melting raw materials or mixtures thereof, and then cooling and solidifying them, and by using a predetermined composition in which sulfur is in excess relative to the stoichiometric ratio, it is possible to produce a glass that exhibits high lithium ion conductivity.

[0013] In the glass according to this embodiment, due to the presence of excess sulfur, PS ４ P is a chain of tetrahedrons. ２ S ６ ２－ Structure and P ２ S ７ ４－ The structure decreases, PS ４ ３－ The structure increases. As a result, lithium ions contained in the glass are less likely to be trapped, and it is estimated that the lithium ion conductivity will improve.

[0014] Furthermore, when the glass according to this embodiment is crystallized by heat treatment, the excess sulfur promotes the precipitation of crystals that contribute to high ionic conductivity, such as crystals having a thiolysicon region II type or LGPS type crystal structure. Therefore, the crystallized glass obtained by crystallizing at least a portion of the glass according to this embodiment also exhibits high lithium ion conductivity.

[0015] 《Glass》 The glass according to this embodiment contains Li, P, and element M as elements constituting the cationic component, and S as elements constituting the anionic component, and at least one of element X and element Y as an optional element.

[0016] The glass according to this embodiment contains Li and P as elements constituting the cationic component, but may further contain element M as an optional element. Element M is at least one element selected from the group consisting of Sn, Sb, Si, Ge, Ga, Al, B, C, Mg, Ca, Sr, and Ba. In particular, from the viewpoint of water resistance, it is preferable to include at least one element selected from the group consisting of Sb, Si, and Sn, and more preferably to include Si. Furthermore, from the viewpoint of ionic conductivity, it is preferable to include at least one of Al and B.

[0017] This section explains each element that makes up the cationic component. Note that the content of each element in the glass is expressed as atomic percent relative to the total content of all elements in the glass.

[0018] Li is an essential element responsible for ion conduction as a solid electrolyte. The Li content in the glass is preferably 30-44%, and more preferably 33-43%. From the viewpoint of lithium ion conductivity, the above content is preferably 30% or more, more preferably 33% or more, and even more preferably 35% or more. From the viewpoint of vitrification, the above content is preferably 44% or less, more preferably 43% or less, and even more preferably 42% or less.

[0019] P is an essential element for forming the glass phase. The P-S bond is highly resistant to both oxidation and reduction in sulfides. Therefore, as a solid electrolyte, it has a wide potential window and excellent electrochemical stability. The P content in the glass is preferably 4 to 16%, and more preferably 5 to 15%. Here, from the viewpoint of vitrification, the above content is preferably 4% or more, more preferably 5% or more, and even more preferably 5.5% or more. Furthermore, from the viewpoint of lithium ion conductivity, the above content is preferably 16% or less, more preferably 15% or less, and even more preferably 13% or less.

[0020] When the glass according to this embodiment contains Si as an element constituting the cationic component, Si has the effect of increasing the viscosity of the melt and promoting vitrification. The Si content in the glass is preferably 0 to 10%, more preferably 0.5 to 10%, and even more preferably 2 to 9%. Here, from the viewpoint of suitably obtaining the effect of Si, the Si content when included is preferably 0.5% or more, and more preferably 2% or more. Furthermore, from the viewpoint of electrochemical stability, the Si content is preferably 10% or less, and more preferably 9% or less.

[0021] When the glass according to this embodiment contains Sn as an element constituting the cationic component, Sn has the effect of increasing the viscosity of the melt and promoting vitrification. The Sn content in the glass is preferably 0 to 10%, more preferably 0.1 to 10%, and even more preferably 0.5 to 8%. Here, from the viewpoint of suitably obtaining the effect of Sn, the Sn content when present is preferably 0.1% or more, and more preferably 0.5% or more. Furthermore, from the viewpoint of electrochemical stability, the Sn content is preferably 10% or less, and more preferably 8% or less.

[0022] When the glass according to this embodiment contains Sb as an element constituting the cationic component, Sb has the effect of increasing the viscosity of the melt and promoting vitrification. The Sb content in the glass is preferably 0 to 10%, more preferably 0.1 to 8%, and even more preferably 1 to 5%. Here, from the viewpoint of suitably obtaining the effect of Sb, the Sb content when present is preferably 0.1% or more, and more preferably 1% or more. Furthermore, from the viewpoint of lithium ion conductivity, the Sb content is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less.

[0023] When the glass according to this embodiment contains Ge as an element constituting the cation component, Ge has the effect of promoting improved lithium ion conductivity. The Ge content in the glass is preferably 0 to 10%, more preferably 0.1 to 8%, and even more preferably 1 to 5%. Here, from the viewpoint of suitably obtaining the effect of Ge, the Ge content when Ge is included is preferably 0.1% or more, and more preferably 1% or more. Furthermore, from the viewpoint of glass formation, the Ge content is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less.

[0024] When the glass according to this embodiment contains Ga as an element constituting the cationic component, Ga has the effect of promoting improved lithium ion conductivity. The Ga content in the glass is preferably 0 to 10%, more preferably 0.1 to 8%, and even more preferably 1 to 5%. Here, from the viewpoint of suitably obtaining the effect of Ga, the Ga content when Ga is included is preferably 0.1% or more, and more preferably 1% or more. Furthermore, from the viewpoint of glass formation, the Ga content is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less.

[0025] When the glass according to this embodiment contains Al as an element constituting the cationic component, Al has the effect of increasing the viscosity of the melt and promoting vitrification. The Al content in the glass is preferably 0 to 10%, more preferably 0.1 to 8%, and even more preferably 1 to 5%. Here, from the viewpoint of suitably obtaining the effect of Al, the Al content when included is preferably 0.1% or more, and more preferably 1% or more. Furthermore, from the viewpoint of lithium ion conductivity, the Al content is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less.

[0026] When the glass according to this embodiment contains B as an element constituting the cationic component, B has the effect of increasing the viscosity of the melt and promoting vitrification. The B content in the glass is preferably 0 to 10%, more preferably 0.1 to 8%, and even more preferably 1 to 5%. Here, from the viewpoint of suitably obtaining the effect of B, the B content when B is included is preferably 0.1% or more, and more preferably 1% or more. Furthermore, from the viewpoint of lithium ion conductivity, the B content is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less.

[0027] When the glass according to this embodiment contains carbon (C) as an element constituting the cationic component, C has the effect of increasing the glass-forming ability. The C content in the glass is preferably 0 to 10%, more preferably 0.1 to 8%, and even more preferably 1 to 5%. Here, from the viewpoint of suitably obtaining the effect of C, the C content when included is preferably 0.1% or more, and more preferably 1% or more. Furthermore, from the viewpoint of lithium ion conductivity, the C content is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less.

[0028] When the glass according to this embodiment contains alkaline earth metal elements as elements constituting the cationic component, the alkaline earth metal elements have the effect of increasing the glass-forming ability. Examples of alkaline earth metal elements include one or more selected from the group consisting of Mg, Ca, Sr, and Ba.

[0029] The content of each alkaline earth metal element in the glass is preferably 0 to 10%, more preferably 0.1 to 8%, and even more preferably 1 to 5%. Here, from the viewpoint of suitably obtaining the effects of alkaline earth metal elements, the content of each alkaline earth metal element when included is preferably 0.1% or more, and more preferably 1% or more. Furthermore, from the viewpoint of lithium ion conductivity, the content of each alkaline earth metal element is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less.

[0030] Furthermore, the total content of alkaline earth metal elements in the glass is preferably 0 to 20%, more preferably 0.2 to 18% and even more preferably 1 to 15% if alkaline earth metal elements are present. Here, the total content is preferably 0.2% or more, more preferably 1% or more, preferably 20% or less, more preferably 18% or less, and even more preferably 15% or less.

[0031] The glass according to this embodiment contains S as an element constituting the anionic component, but may further contain at least one of element X and element Y as an optional element. Element X is at least one halogen element selected from the group consisting of F, Cl, Br, and I, and element Y is at least one element selected from the group consisting of O, Se, N, and C. In particular, from the viewpoint of improving ionic conductivity, it is preferable to include element X, more preferably to include at least one element selected from the group consisting of Cl, Br, and I, and even more preferably to include I. Furthermore, from the viewpoint of improving vitrification ability, it is preferable to include element Y.

[0032] This section explains each element that makes up the anionic component. Note that the content of each element in the glass is expressed as atomic percentage (%) relative to the total content of all elements in the glass.

[0033] S is an element that forms a P-S bond with P and is an essential element for forming the glass phase. The S content in the glass is preferably 30-60%, more preferably 33-55%, and even more preferably 37-50%. From the viewpoint of vitrification, the above content is preferably 30% or more, more preferably 33% or more, and even more preferably 37% or more. Also, from the viewpoint of lithium ion conductivity, the above content is preferably 60% or less, more preferably 55% or less, and even more preferably 50% or less.

[0034] When the glass according to this embodiment contains element X (a halogen element) as an element constituting the anionic component, element X is an element that contributes to high lithium ion conductivity. The total content of element X in the glass is preferably 0 to 25%, and more preferably 1 to 25% when element X is included. Here, from the viewpoint of suitably obtaining the effect of element X, the total content when element X is included is preferably 1% or more, and more preferably 2% or more. Furthermore, from the viewpoint of preventing the precipitation of lithium halide crystals, the total content of element X is preferably 25% or less, and more preferably 20% or less. Also, the total content of element X may be 17% or less, or 10% or less.

[0035] In particular, it is preferable that the combined content of Br and I accounts for 50% or more of the total content of element X, more preferably 70% or more, and it may even consist of 100%, i.e., only Br and I. Furthermore, the content ratio expressed as Br:I is preferably 100:0 to 0:100, more preferably 80:20 to 0:100, and even more preferably 60:40 to 0:100. However, this does not preclude the inclusion of Br alone as element X.

[0036] When the glass according to this embodiment contains F as an element constituting the anionic component, the F content in the glass is preferably 0.1 to 10%, and more preferably 0.5 to 5%. Here, the F content is preferably 0.1% or more, more preferably 0.5% or more, and preferably 10% or less, and more preferably 5% or less.

[0037] When the glass according to this embodiment contains Cl as an element constituting the anionic component, the Cl content in the glass is preferably 0.1 to 10%, and more preferably 0.5 to 5%. Here, the Cl content is preferably 0.1% or more, more preferably 0.5% or more, and preferably 10% or less, and more preferably 5% or less.

[0038] When the glass according to this embodiment contains Br as an element constituting the anionic component, the Br content in the glass is preferably 0.1 to 25%, and more preferably 1 to 20%. Here, the Br content is preferably 0.1% or more, more preferably 1% or more, and preferably 25% or less, and more preferably 20% or less.

[0039] When the glass according to this embodiment contains I as an element constituting the anionic component, the I content in the glass is preferably 0.1 to 25%, more preferably 1 to 20%, and even more preferably 1.5 to 17%. Here, the I content is preferably 0.1% or more, more preferably 1% or more, and even more preferably 1.5% or more. Furthermore, from the viewpoint of suppressing the deposition of lithium halide, the I content is preferably 25% or less, more preferably 20% or less, and even more preferably 17% or less.

[0040] When the glass according to this embodiment contains oxygen (O) as an element constituting the anionic component, O has the effect of improving ionic conductivity. The O content in the glass is preferably 0 to 5%, more preferably 0.1 to 4%, and even more preferably 0.5 to 3%. Here, from the viewpoint of suitably obtaining the effect of O, the O content when present is preferably 0.1% or more, and more preferably 0.5% or more. Furthermore, from the viewpoint of water resistance, the O content is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0041] When the glass according to this embodiment contains Se as an element constituting the anionic component, Se has the effect of improving ionic conductivity. The Se content in the glass is preferably 0 to 5%, more preferably 0.1 to 4%, and even more preferably 0.5 to 3%. Here, from the viewpoint of suitably obtaining the effect of Se, the Se content when Se is included is preferably 0.1% or more, and more preferably 0.5% or more. Also, from the viewpoint of water resistance, the Se content is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0042] When the glass according to this embodiment contains nitrogen (N) as an element constituting the anionic component, N has the effect of improving ionic conductivity. The N content in the glass is preferably 0 to 5%, more preferably 0.1 to 4%, and even more preferably 0.5 to 3%. Here, from the viewpoint of suitably obtaining the effect of N, the N content when present is preferably 0.1% or more, and more preferably 0.5% or more. Furthermore, from the viewpoint of water resistance, the N content is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0043] When the glass according to this embodiment contains carbon (C) as an element constituting the anionic component, C has the effect of improving ionic conductivity. The C content in the glass is preferably 0 to 5%, more preferably 0.1 to 4%, and even more preferably 0.5 to 3%. Here, from the viewpoint of suitably obtaining the effect of C, the C content when included is preferably 0.1% or more, and more preferably 0.5% or more. Furthermore, from the viewpoint of water resistance, the C content is preferably 5% or less, more preferably 4% or less, and even more preferably 3% or less.

[0044] Note that carbon (C) can be an element that constitutes either a cationic component or an anionic component. Whether carbon is present in one of these two states can be determined by measuring the glass using XPS (X-ray photoelectron spectroscopy), and carbon is never present in both states simultaneously.

[0045] The glass according to this embodiment may contain other elements in addition to the above-mentioned Li, P, S, and the optional elements M, X, and Y, as long as the effects of the present invention are not impaired. Examples of other elements include Na, K, Y, Zr, Cr, Zn, Fe, Co, Ti, Mn, etc.

[0046] The total content of the other elements in the glass according to this embodiment may be, for example, 0 to 5% in atomic percent, or 0.1 to 4% or 0.5 to 3% if other elements are included. Here, the total content may be 0.1% or more, 0.5% or more, 5% or less, 4% or less, or 3% or less.

[0047] The method for determining the constituent elements of the glass according to this embodiment and their respective content (composition ratio) differs depending on the element. For example, P, S, Sn, Sb, Si, Ge, Ga, Al, Mg, Ca, Sr, Ba, and Se are determined by ICP emission spectrometry, Li and B by atomic absorption spectrometry, halogens by ion chromatography, and C, O, and N by XPS (X-ray photoelectron spectroscopy). Details of each analysis will be described in the Examples section below.

[0048] The glass according to this embodiment is Li(a+c-m×d-y×e)M ｄ P （１－ｄ） S ｂ X ｃ Y ｅ It is represented by the following empirical formula. In this empirical formula, a to e satisfy the following relationships: -5.30 < a - 2b - 5d < -5.00, 1.50 < a < 7.50, c ≥ 0, 0 ≤ d ≤ 4 / 7, and e ≥ 0. Here, m is the valence of element M, and y is the valence of element Y.

[0049] The above composition formula Li(a+c-m×d-y×e)M ｄ P （１－ｄ） S ｂ X ｃ Y ｅ This is the glass composition expressed in terms of atomic ratios where the sum of P and M is 1. The atomic ratio of Li, "a + c - m × d - y × e", represents the Li atomic ratio that reflects charge compensation according to the atomic ratios of elements M, X, and Y.

[0050] In the above compositional formula, a, b, and d satisfy the relationship -5.30 < a-2b-5d < -5.00. In this specification, the value of "a-2b-5d" is also referred to as the "sulfur parameter". When the sulfur parameter is equal to -5.00, the glass composition corresponds to the stoichiometric ratio. In the glass according to this embodiment, the sulfur parameter is less than -5.00, resulting in a glass composition with excess sulfur. This results in a glass that exhibits high lithium ion conductivity.

[0051] The sulfur parameter is greater than -5.30 and less than -5.00, preferably between -5.25 and -5.01, more preferably between -5.20 and -5.02, and even more preferably between -5.15 and -5.03. From the viewpoint of obtaining high lithium-ion conductivity by having an excess of sulfur, the sulfur parameter is less than -5.00, preferably between -5.01, more preferably between -5.02, and even more preferably between -5.03. Furthermore, from the viewpoint of glass-forming ability, the sulfur parameter is greater than -5.30, preferably above -5.25, more preferably above -5.20, and even more preferably above -5.15. Note that even a slight variation in the absolute value of the sulfur parameter, such as 0.01, can have a significant impact on the properties of the glass.

[0052] In the above composition formula, a is greater than 1.50 and less than 7.50, preferably 1.70 or more and 6.50 or less, and more preferably 7 / 3 or more and 5.00 or less. From the viewpoint of obtaining a glass composition with a high lithium content and improving lithium ion conductivity, a is greater than 1.50, preferably 1.70 or more, and more preferably 7 / 3 or more. Also, from the viewpoint of vitrification ability, a is less than 7.50, preferably 6.50 or less, and more preferably 5.00 or less.

[0053] In the above compositional formula, b is preferably 2.5 or more and 6 or less, and more preferably 3 or more and 5 or less. From the viewpoint of having an excess of sulfur and obtaining high lithium ion conductivity, b is preferably 2.5 or more and more preferably 3 or more. Also from the viewpoint of obtaining high lithium ion conductivity, b is preferably 6 or less and more preferably 5 or less.

[0054] In the above compositional formula, c is 0 or greater, indicating that element X is an arbitrary element. c may satisfy c > 0, meaning that the glass according to this embodiment may contain element X. When the glass according to this embodiment contains element X, c is preferably greater than 0 and 6 or less, and more preferably 0.3 or more and 3 or less. From the viewpoint of suitably obtaining the effects of element X, c is preferably greater than 0 and more preferably 0.3 or more. Furthermore, from the viewpoint of preventing the precipitation of lithium halide crystals, c is preferably 6 or less and more preferably 3 or less.

[0055] In the above compositional formula, d is 0 or greater, indicating that element M is an arbitrary element. d may satisfy d > 0, meaning the glass according to this embodiment may contain element M. d is 0 or greater and 4 / 7 or less, and if the glass according to this embodiment contains element M, it is more preferably greater than 0 and 0.55 or less, and even more preferably 0.10 or greater and 0.50 or less. From the viewpoint of suitably obtaining the effects of element M, d is preferably greater than 0, and more preferably 0.10 or greater. Furthermore, from the viewpoint of the oxidation-reduction resistance of the glass, d is 4 / 7 or less, preferably 0.55 or less, and more preferably 0.50 or less.

[0056] In the above compositional formula, e is 0 or greater, indicating that element Y is an arbitrary element. e may satisfy e > 0, meaning that the glass according to this embodiment may contain element Y. When the glass according to this embodiment contains element Y, e is preferably greater than 0 and 6 or less, and more preferably between 0.1 and 3. From the viewpoint of suitably obtaining the effects of element Y, e is preferably greater than 0 and more preferably 0.1 or greater. Also, from the viewpoint of water resistance, e is preferably 6 or less and more preferably 3 or less.

[0057] In the above compositional formula, a, c, d, and e preferably satisfy 1.50 < a < 7.50, c ≥ 0, 0 ≤ d ≤ 4 / 7, and e ≥ 0, and more preferably satisfy 1.70 ≤ a ≤ 6.50, 0 ≤ c ≤ 6, 0 ≤ d ≤ 0.55, and 0 ≤ e ≤ 6, and more preferably satisfy 7 / 3 ≤ a ≤ 5.00, 0 ≤ c ≤ 3, 0 ≤ d ≤ 0.50, and 0 ≤ e ≤ 3.

[0058] Furthermore, it is preferable that a and b in the above compositional formula satisfy 1.70 ≤ a ≤ 6.50 and 2.5 ≤ b ≤ 6, and more preferably that 7 / 3 ≤ a ≤ 5.00 and 3 ≤ b ≤ 5.

[0059] Furthermore, when the glass according to this embodiment contains elements X and M, it is preferable that a, c, and d in the above composition formula satisfy 1.50 < a < 7.50, c > 0, and 0 < d ≤ 4 / 7, and more preferably that 1.70 ≤ a ≤ 6.50, 0 < c ≤ 6, and 0 < d ≤ 0.55, and more preferably that 7 / 3 ≤ a ≤ 5.00, 0.3 ≤ c ≤ 3, and 0.10 ≤ d ≤ 0.50.

[0060] In the above empirical formula, if element X contains multiple elements, the c in the atomic ratio of Li (a + c - m × d - y × e) in the empirical formula represents the sum of the atomic ratios of each element X. That is, element X ｐ is the atomic ratio c ｐ Regarding the glass composition contained therein, c in the atomic ratio of Li (a + c - m × d - y × e) is expressed by the following formula (1).

[0061]

[0062] In the above empirical formula, m represents the valence of element M. When element M includes multiple elements, the m × d in the atomic ratio of Li (a + c - m × d - y × e) in the empirical formula represents the sum of the products of the valence and atomic ratio of each element M. That is, m ｑ Valence of element M ｑ is atomic ratio d ｑ The glass composition contained in is expressed by the following formula (2), where m × d is given by the following formula. Note that in a given glass composition, one element M ｑ multiple valencies m ｑ１ , m ｑ２ ...when taking the above m ｑ This is the weighted average of these valencies.

[0063]

[0064] The valence m of element M contained in glass can be determined by measuring the glass using methods such as X-ray fluorescence analysis (EPMA) or Mössbauer spectroscopy.

[0065] In the above empirical formula, y represents the valence of element Y. When element Y includes multiple elements, y × e in the atomic ratio of Li (a + c - m × d - y × e) in the empirical formula represents the sum of the products of the valence and atomic ratio of each element Y. That is, y ｒ Valence of element Y ｒ is the atomic ratio e ｒ The glass composition contained in is expressed by the following formula (3). Note that in a given glass composition, one element Y ｒ multiple valencies y ｒ１ , y ｒ２ ...if you take the above y ｒ This is the weighted average of these valencies.

[0066]

[0067] The valence y of element Y contained in glass can be determined by measuring the glass, for example, using X-ray photoelectron spectroscopy (XPS) or X-ray fluorescence analysis.

[0068] The glass according to this embodiment preferably has a glass transition temperature of 110 to 300°C, more preferably 130 to 300°C, even more preferably 140 to 290°C, and particularly preferably 150 to 280°C. In this embodiment, a glass having a glass transition temperature can be obtained by melting a raw material mixture and then cooling and solidifying it.

[0069] From the viewpoint of improving the stability of the glass, the glass transition temperature is preferably 110°C or higher, more preferably 115°C or higher, even more preferably 120°C or higher, even more preferably 130°C or higher, particularly preferably 140°C or higher, and most preferably 150°C or higher. Furthermore, from the viewpoint of moldability, the glass transition temperature is preferably 300°C or lower, more preferably 290°C or lower, and even more preferably 280°C or lower.

[0070] In this specification, the glass transition point is the temperature at the first inflection point of the DSC chart obtained by differential scanning calorimetry (DSC), and can be adjusted by the composition of the glass and the cooling rate from the melt.

[0071] The crystallization temperature of the glass according to this embodiment is not particularly limited, but is preferably 130 to 400°C, more preferably 140 to 400°C, and particularly preferably 150 to 370°C. Here, from the viewpoint of moldability, the crystallization temperature is preferably 130°C or higher, more preferably 140°C or higher, and particularly preferably 150°C or higher. Furthermore, from the viewpoint of glass stability, the crystallization temperature is preferably 400°C or lower, and more preferably 370°C or lower.

[0072] In this specification, the crystallization temperature refers to the temperature at the peak of the exothermic peak observed when glass is subjected to DSC and heated at a heating rate of 10°C / min.

[0073] When the glass transition temperature of the glass according to this embodiment is Tg and the crystallization temperature is Tc, the temperature difference expressed as (Tc - Tg) is preferably 10 to 200°C, and more preferably 20 to 180°C. Here, from the viewpoint of glass stability, the above difference is preferably 10°C or more, and more preferably 20°C or more. Also, from the viewpoint of productivity, the above difference is preferably 200°C or less, and more preferably 180°C or less.

[0074] When the glass according to this embodiment is compacted into powder at 380 MPa, the lithium ion conductivity at 25°C is preferably 0.80 mS / cm or higher, more preferably 0.85 mS / cm or higher, more preferably 0.90 mS / cm or higher, more preferably 1.0 mS / cm or higher, more preferably 1.4 mS / cm or higher, more preferably 2.0 mS / cm or higher, and more preferably 3.0 mS / cm or higher; the higher the value, the better.

[0075] In this specification, lithium-ion conductivity is determined by AC impedance measurement using a powder sample compacted at 380 MPa as the measurement sample. Specifically, the AC impedance measurement of the measurement sample is performed with a measurement frequency of 100 Hz to 1 MHz, a measurement voltage of 100 mV, and a measurement temperature of 25°C, and the value obtained from the resulting Nyquist plot is defined as the lithium-ion conductivity.

[0076] The lithium ion conductivity described above can be adjusted by the composition of the glass, reducing thermal unevenness during the cooling and solidification of the molten raw material mixture, and the cooling rate. In particular, the glass according to this embodiment can be made to have a high lithium ion concentration and high lithium ion conductivity by having a composition in which sulfur is in excess relative to the stoichiometric ratio.

[0077] Crystallized Glass The crystallized glass according to this embodiment is obtained by heat-treating the glass described in the above description of "Glass" to crystallize at least a portion thereof. That is, the crystallized glass according to this embodiment includes a crystalline phase derived from the glass described in the above description of "Glass". It may also optionally further include an amorphous phase, in which case the amorphous phase includes a phase made of the glass described in the above description of "Glass".

[0078] Here, the phase derived from the above-mentioned glass refers to the crystalline phase obtained by crystallizing such glass through heat treatment. Except in cases where the crystallized glass consists solely of a crystalline phase with 100% crystallinity, the glass from which the crystalline phase originates can be inferred from the crystal structure and mass ratio of the crystalline phase and the overall composition of the crystallized glass.

[0079] Specifically, the crystalline phase is analyzed using Rietveld analysis and other methods on the XRD patterns obtained by powder X-ray diffraction (XRD) measurements to calculate the crystalline structure and mass ratio of the crystalline phase. On the other hand, the overall composition of the crystallized glass is determined using methods such as ICP emission spectroscopy, atomic absorption spectroscopy, ion chromatography, and XPS, depending on the type of element, similar to how the constituent elements of the glass and their respective content (composition ratio) are determined.

[0080] Then, by subtracting the composition of the crystalline phase by its mass ratio from the overall composition of the crystallized glass, the composition and amount of the amorphous phase can be calculated. The composition of this amorphous phase is considered to be the composition of the glass before crystallization (also referred to as the master composition). If this master composition corresponds to the glass according to this embodiment as described in the section "Glass" above, then the crystallized glass can be determined to be the crystallized glass according to this embodiment.

[0081] The matrix composition of the crystallized glass according to this embodiment is the same as the composition described in the "Glass" section above. In other words, the composition of the amorphous phase of the crystallized glass according to this embodiment is identical to that of the matrix composition.

[0082] Furthermore, the composition of the crystalline phase in this embodiment differs from the above-mentioned parent composition by at most about 30%, and the amount of P tends to decrease. The above-mentioned crystalline phase can take the form of a thiolysicon region II type or LGPS type crystalline structure.

[0083] The crystalline phase of the crystallized glass according to this embodiment more preferably includes crystals having at least one of the thiolysicon region II type and LGPS type crystalline structures. The crystalline structure of the crystals contained in the crystallized glass can be confirmed by performing Rietveld analysis or the like on the XRD pattern obtained by powder X-ray diffraction (XRD) measurement.

[0084] In the crystallized glass according to this embodiment, the proportion of the crystalline phase (degree of crystallinity) is preferably 10 to 100% by mass, more preferably 20 to 90% by mass, and even more preferably 30 to 80% by mass. Here, from the viewpoint of lithium ion conductivity, the degree of crystallinity is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. Furthermore, from the viewpoint of productivity, the degree of crystallinity is preferably 100% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less. Note that the crystallized glass according to this embodiment may have a degree of crystallinity of 100% by mass and consist only of the crystalline phase.

[0085] The above degree of crystallinity is determined by powder X-ray diffraction (XRD) measurement of the crystallized glass together with an internal standard crystal powder, and then performing Rietveld analysis to determine the proportion of crystals, which is then subtracted from 100% by mass.

[0086] The glass in this embodiment before crystallization has high lithium ion conductivity, and crystals that contribute to high ionic conductivity easily precipitate. Therefore, the lithium ion conductivity of the crystallized glass according to this embodiment is also high, making it suitable for use as a solid electrolyte. Specifically, when the crystallized glass according to this embodiment is compacted into powder at 380 MPa, the lithium ion conductivity at 25°C is preferably 2.0 mS / cm or higher, more preferably 3.0 mS / cm or higher, even more preferably 4.0 mS / cm or higher, and even more preferably 5.0 mS / cm or higher; the higher the value, the better.

[0087] Sulfide Solid Electrolyte The sulfide solid electrolyte according to this embodiment includes the glass described in "Glass" above or the crystallized glass described in "Crystallized Glass" above.

[0088] The constituent elements and composition ratios of the glass or crystallized glass described above can be considered to be substantially the same as those of the sulfide solid electrolyte according to this embodiment. Therefore, a preferred embodiment of the constituent elements and composition ratios of the sulfide solid electrolyte described above can be read as a preferred embodiment of the constituent elements and composition ratios of the glass or crystallized glass described above. However, the sulfide solid electrolyte according to this embodiment may also include other phases besides the glass or crystallized glass described above.

[0089] In this embodiment, the average particle size (D50) of the sulfide solid electrolyte is preferably 0.5 to 100 μm, more preferably 0.8 to 80 μm, and even more preferably 1 to 50 μm. Here, from the viewpoint of reducing the load of the fine grinding process when using the sulfide solid electrolyte in a secondary battery, the above average particle size is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less. Furthermore, from the viewpoint of handling the powder, the above average particle size is preferably 0.5 μm or more, more preferably 0.8 μm or more, and even more preferably 1 μm or more.

[0090] The average particle size (D50) can be adjusted by coarse grinding of the obtained sulfide solid electrolyte. Coarse grinding can be performed using conventionally known methods, such as cutter mills, planetary ball mills, bead mills, and jet mills. Furthermore, wet grinding is preferred when performing coarse grinding.

[0091] The sulfide solid electrolyte according to this embodiment is suitable as an electrolyte for lithium-ion secondary batteries. When used in a lithium-ion secondary battery, the sulfide solid electrolyte forms a solid electrolyte layer together with other components such as a binder, as needed. That is, the solid electrolyte layer according to this embodiment includes the above-mentioned sulfide solid electrolyte.

[0092] The binder and other components that make up the solid electrolyte layer can be those that are conventionally known.

[0093] The content of the sulfide solid electrolyte according to this embodiment is preferably 80% by mass or more, and more preferably 90% by mass or more, relative to the entire solid electrolyte layer.

[0094] The sulfide solid electrolyte according to this embodiment may be mixed with a positive electrode active material or a negative electrode active material and used as an electrode composite material for the positive electrode layer or the negative electrode layer. That is, the electrode composite material according to this embodiment includes the above-mentioned sulfide solid electrolyte.

[0095] Conventional known materials can be used for the positive electrode active material or negative electrode active material used in the positive electrode layer or negative electrode layer, current collector, binder, conductive additive, etc.

[0096] The lithium-ion secondary battery according to this embodiment includes the above-mentioned sulfide solid electrolyte. The lithium-ion secondary battery according to this embodiment includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, and it is preferable that at least one layer selected from the group consisting of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer contains the sulfide solid electrolyte according to this embodiment.

[0097] The materials used for the casing of the lithium-ion secondary battery can also be those that are already known. The shape of the lithium-ion secondary battery can also be those that are already known, such as coin-shaped, sheet-shaped (film-shaped), foldable, wound-type bottomed cylindrical, button-shaped, etc., and can be appropriately selected depending on the application.

[0098] 《Method for Manufacturing Glass and Crystallized Glass》 The method for manufacturing glass according to this embodiment, as shown in Figure 1, includes the following steps 1 and 2 in order as steps S1 and S2. Step S1: Mix raw materials to obtain a raw material mixture containing Li, P, S, and at least one element selected from the group consisting of element M, element X, and element Y as an optional component, and heat the raw material mixture at 400 to 1000°C to obtain a molten product. Step S2: Cool and solidify the molten product obtained in step 1 to obtain glass.

[0099] The method for manufacturing crystallized glass according to this embodiment includes the following steps 1 to 3 in order, as shown in Figure 2, as steps S1 to S3. Here, steps S1 and S2 are the same as steps S1 and S2 in the glass manufacturing method according to this embodiment described above. Step S1: Mix raw materials to obtain a raw material mixture containing Li, P, S, and at least one element selected from the group consisting of element M, element X, and element Y as an optional component, and heat the raw material mixture at 400 to 1000°C to obtain a molten product. Step S2: Cool and solidify the molten product obtained in step 1 to obtain glass. Step S3: Heat treat the glass obtained in step 2 to crystallize at least a portion thereof to obtain crystallized glass.

[0100] The present inventors have come to realize that, among methods for manufacturing the glass described above, the first and second embodiments described below are particularly noteworthy, as methods for manufacturing the glass described above.

[0101] <First Embodiment> In the first embodiment, in step 1, the raw material mixture is heated at 400 to 1000°C in a gas atmosphere containing S (sulfur element). That is, the method for manufacturing glass according to the first embodiment is a method for manufacturing glass according to the present embodiment, comprising: mixing raw materials to obtain a raw material mixture containing Li, P, and S, and as an optional component, at least one element selected from the group consisting of the above elements M, X, and Y; heating the raw material mixture at 400 to 1000°C in a gas atmosphere containing S to obtain a molten product; and cooling and solidifying the molten product to obtain the glass.

[0102] In the first embodiment, the raw material mixture is heated at 400 to 1000°C in a gas atmosphere containing sulfur (S) in step 1 above, thereby introducing sulfur into the molten material, and the resulting glass has a predetermined composition in which sulfur is in excess relative to the stoichiometric ratio.

[0103] Examples of gases containing the sulfur element include sulfur gas, hydrogen sulfide gas, carbon disulfide gas, and other compounds or gases containing the sulfur element or elemental sulfur.

[0104] The above-mentioned gas atmosphere containing sulfur elements may also be obtained by supplying a sulfur source to a molten mixture obtained by heating and melting the raw material mixture, and generating a gas containing sulfur elements by heating the sulfur source. In this case, the sulfur source is not particularly limited as long as it is elemental sulfur or a sulfur compound from which a gas containing sulfur elements can be obtained by heating, but for example, elemental sulfur, hydrogen sulfide, organic sulfur compounds such as carbon disulfide, iron sulfide (FeS, Fe) ２ S ３ FeS ２ Fe １－ｘ S, etc.), bismuth sulfide (Bi ２ S ３ ), copper sulfide (CuS, Cu ２ S, Cu １－ｘ Examples include polysulfides such as sodium polysulfide, lithium polysulfide, and sodium polysulfide, as well as polysulfides and sulfur-vulcanized rubber. A preferred sulfur source is sulfur powder.

[0105] Alternatively, a gas atmosphere containing sulfur elements may be obtained by introducing pre-obtained sulfur vapor into a heating vessel. For example, sulfur is heated to 200-450°C to generate sulfur vapor, and N ２ By transporting inert gases such as gas, argon gas, and helium gas into the heating container as carrier gases, a gas atmosphere containing sulfur elements can be obtained.

[0106] Alternatively, a gaseous atmosphere containing sulfur elements may be obtained by incorporating a sulfur source into the raw material mixture. This way, when the raw material mixture is heated and melted, the sulfur source is also heated, allowing the raw material mixture to be heated and melted under a gaseous atmosphere containing the generated sulfur elements.

[0107] In the first embodiment, the method for obtaining the above-described gas atmosphere containing sulfur elements may be any one of the methods or a combination of multiple methods.

[0108] In a gaseous atmosphere containing the above-mentioned sulfur element, increasing the sulfur vapor pressure results in an excess of sulfur in the resulting glass composition, while decreasing the sulfur vapor pressure results in a deficiency of sulfur in the resulting glass composition. Therefore, by adjusting the sulfur vapor pressure along with the raw material composition and heating temperature, the desired degree of sulfur excess can be achieved.

[0109] <Second Embodiment> In the second embodiment, the raw materials are mixed such that the ratio of the value of b in the raw material mixture exceeds 100% with respect to the value of b such that a - 2b - 5d = -5.00 in the above composition formula. That is, the method for manufacturing glass according to the second embodiment is a method for manufacturing glass according to the present embodiment, which includes mixing raw materials to obtain a raw material mixture containing Li, P, and S, and as an optional component, at least one element selected from the group consisting of the above element M, the above element X, and the above element Y; heating the raw material mixture at 400 to 1000°C to obtain a molten product; and cooling and solidifying the molten product to obtain the above glass, wherein the raw materials are mixed such that the ratio of the value of b in the raw material mixture exceeds 100% with respect to the value of b such that a - 2b - 5d = -5.00 in the above composition formula.

[0110] In the second embodiment, the raw materials are mixed such that the ratio of the value of b in the raw material mixture exceeds 100% of the value of b when the sulfur parameter matches -5.00, i.e., when the composition is in accordance with the stoichiometric ratio. The resulting glass has a predetermined composition in excess of sulfur relative to the stoichiometric ratio. The above ratio is greater than 100%, preferably greater than 100% and 125% or less, more preferably 103-120%, and even more preferably 105-115%. From the viewpoint of setting the composition of the resulting glass within a predetermined range, the above ratio is greater than 100%, preferably 103% or more, more preferably 105% or more, and also preferably 125% or less, more preferably 120% or less, and even more preferably 115% or less.

[0111] The glass manufacturing method according to this embodiment may be a combination of the first and second embodiments described above. That is, the glass manufacturing method according to this embodiment is a method for manufacturing glass according to this embodiment, comprising: mixing raw materials to obtain a raw material mixture containing Li, P, S, and at least one element selected from the group consisting of element M, element X, and element Y as an optional component; heating the raw material mixture at 400 to 1000°C in a gas atmosphere containing S to obtain a molten product; and cooling and solidifying the molten product to obtain the glass described above, wherein the raw materials may be mixed such that the ratio of the value of b in the raw material mixture exceeds 100% of the value of b such that a - 2b - 5d = -5.00.

[0112] Each step is described below. The information described here can be applied to either the first or second embodiment described above.

[0113] <Step 1> Step S1 in this embodiment is a step 1 in which each raw material is mixed to obtain a raw material mixture containing Li, P, S, and at least one element selected from the group consisting of element M, element X, and element Y as an optional component, and the mixture is heated at 400 to 1000°C.

[0114] Specifically, a raw material mixture is obtained by mixing raw materials containing Li, P, and S. Furthermore, if it is desired to obtain a glass containing at least one element selected from the group consisting of M, X, and Y, a raw material mixture is obtained by mixing raw materials containing Li, P, and S with a raw material containing the target element.

[0115] Examples of raw materials containing the element Li include lithium sulfide (Li ２ S), Lithium carbonate (Li ２ CO ３ ), lithium sulfate (Li ２ SO ４ ), lithium oxide (Li ２ Examples include lithium compounds such as lithium hydroxide (LiOH) and metallic lithium. One type of Li-containing raw material may be used, or two or more types may be used in combination.

[0116] From the viewpoint of obtaining sulfide-based glass, lithium sulfide is preferred as the raw material containing the element Li. Furthermore, if the resulting glass contains element X (halogen element), lithium halide (LiX) is also preferred as the raw material containing the element Li. Lithium halide will be discussed later.

[0117] Examples of raw materials containing element P include phosphorus pentasulfide (P ２ S ５ ), diphosphorus trisulfide (P ２ S ３ ) such as phosphorus sulfide, sodium phosphate (Na ３ PO ４ Examples include phosphorus compounds such as ) and elemental phosphorus. One type of phosphorus-containing raw material may be used, or two or more types may be used in combination.

[0118] From the viewpoint of preventing the inclusion of elements other than those constituting the target glass, phosphorus sulfide is preferred as the raw material containing element P, and diphosphorus pentasulfide (P ２ S ５ ) is more preferable. Furthermore, when using elemental phosphorus as a raw material containing element P, examples include yellow phosphorus, red phosphorus, violet phosphorus, black phosphorus, etc.

[0119] Examples of raw materials containing element S include lithium sulfide (Li ２ S), diphosphorus trisulfide (P ２ S ３ ), diphosphorus pentasulfide (P ２ S ５ Examples include phosphorus sulfide, other sulfur compounds containing phosphorus, and sulfur-containing compounds. Examples of sulfur-containing compounds include H ２ S, CS ２ , iron sulfide (FeS, Fe ２ S ３ FeS ２ Fe １－ｘ S, etc.), bismuth sulfide (Bi ２ S ３ ), copper sulfide (CuS, Cu ２ S, Cu １－ｘ Examples include sulfur (S). A single raw material containing S may be used, or a combination of two or more may be used.

[0120] From the viewpoint of preventing the inclusion of elements other than those constituting the target glass, lithium sulfide and phosphorus sulfide are preferred as raw materials containing element S, and as phosphorus sulfide, diphosphorus pentasulfide (P ２ S ５ ) is more preferable. Note that lithium sulfide is a compound that contains both a Li element and a S element as raw materials, and phosphorus sulfide is a compound that contains both a S element and a P element as raw materials.

[0121] Examples of raw materials containing element X include lithium halides such as lithium fluoride (LiF), lithium chloride (LiCl), lithium bromide (LiBr), and lithium iodide (LiI), as well as phosphorus halides, phosphoryl halides, sulfur halides, sodium halides, and boron halides. One raw material containing element X may be used, or two or more may be used in combination.

[0122] From the viewpoint of reactivity, the raw material containing element X is preferably lithium halide, more preferably LiCl, LiBr, and LiI, and even more preferably LiBr and LiI.

[0123] As raw materials containing element M, conventionally known materials can be used.

[0124] For example, as raw materials containing Si element, Si, SiO ２ , SiS ２ , etc. can be mentioned. Among them, from the viewpoint of lithium ion conductivity, Si, SiO ２ are more preferable. These compounds may be used alone or in combination of two or more kinds.

[0125] As raw materials containing Sn element, Sn, SnS, SnS ２ , SnO, SnO ２ , SnI ２ , SnI<​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​３ Ga ２ S ３ GaCl ３ These are some examples. In particular, from the viewpoint of lithium-ion conductivity, Ga ２ S ３ GaCl ３ Preferably, Ga ２ S ３ This is more preferable. These compounds may be used individually or in combination of two or more.

[0129] Examples of raw materials containing the element Al include Al, Al ２ S ３ Al ２ O ３ AlCl ３ These include, in particular, Al, from the standpoint of lithium-ion conductivity and water resistance. ２ S ３ AlCl ３ Preferably, Al ２ S ３ This is more preferable. These compounds may be used individually or in combination of two or more.

[0130] Examples of raw materials containing element B include B, B ２ O ３ , B ２ S ３ These are some examples. In particular, from the standpoint of the water resistance of glass, B ２ O ３ This is more preferable. These compounds may be used individually or in combination of two or more.

[0131] As a raw material containing element C, Li ２ CO ３ Li ２ C ２ CaCO ３ These are some examples. In particular, from the standpoint of availability and lithium-ion conductivity, Li ２ CO ３ This is preferable. These compounds may be used individually or in combination of two or more.

[0132] Raw materials containing the element Mg include Mg and MgO. ２ MgS, MgBr２ MgI ２ These are some examples. In particular, from the viewpoint of ease of solubility, Mg and MgBr ２ Preferably, MgBr ２ This is more preferable. These compounds may be used individually or in combination of two or more.

[0133] Raw materials containing the element Ca include Ca and CaO. ２ CaS, CaBr ２ CaI ２ These are some examples. In particular, from the viewpoint of ease of solubility, CaBr ２ CaI ２ This is more preferable. These compounds may be used individually or in combination of two or more.

[0134] Raw materials containing the element Sr include Sr, SrO, SrS, and SrBr. ２ , SrI ２ These are some examples. In particular, from the viewpoint of ease of solubility, SrBr ２ , SrI ２ Preferably, SrI ２ This is more preferable. These compounds may be used individually or in combination of two or more.

[0135] Raw materials containing the element Ba include Ba, BaO, BaS, and BaBr. ２ These are some examples. Among them, Ba is more preferred from the viewpoint of ease of solubility. These compounds may be used individually or in combination of two or more.

[0136] As raw materials containing element Y, conventionally known materials can be used.

[0137] For example, as a raw material containing element O, one could use oxides of the above-mentioned compounds, for example Li ２ O, Li ２ CO ３ , P ２ O ５ These are some examples. In particular, from the standpoint of productivity, Li ２ O, P ２ O ５ P is preferred. ２ O ５This is more preferable. These compounds may be used individually or in combination of two or more.

[0138] Raw materials containing the element Se include Se, Li ２ Se, P ２ See ５ These are some examples. Among them, Se is preferred from the viewpoint of availability. These compounds may be used individually or in combination of two or more.

[0139] As a raw material containing element N, Li ３ N, LiNO ３ , P ３ N ５ These are some examples. In particular, from the perspective of procurement, Li ３ N, LiNO ３ Preferably, LiNO ３ This is more preferable. These compounds may be used individually or in combination of two or more.

[0140] The above-mentioned materials are examples of raw materials containing element C.

[0141] Depending on the desired glass composition, other raw materials may be added to obtain a raw material mixture. For example, if the glass contains other elements as mentioned above, raw materials containing Na, K, Y, Zr, Cr, Zn, Fe, Co, Ti, Mn, etc. may be used. Note that Si, B, Ge, Al, Sn, and Sb are elements that can occupy the P position when the obtained glass is further crystallized into glass.

[0142] These other raw materials can be those that are conventionally known.

[0143] These raw materials are blended appropriately according to the desired composition of the glass. Specifically, in order to obtain the glass or crystallized glass described above in "Glass" or "Crystallized Glass," the glass must contain Li, P, S, and, as an optional component, at least one element selected from the group consisting of element M, element X, and element Y, and the resulting glass must be Li(a+c-m×d-y×e)M ｄ P （１－ｄ） S ｂ X ｃ Y ｅThe compositional formula is represented as follows, and the raw materials are mixed such that a to e satisfy the following relationships: -5.30 < a - 2b - 5d < -5.00, 1.50 < a < 7.50, c ≥ 0, 0 ≤ d ≤ 4 / 7, and e ≥ 0, to obtain a raw material mixture.

[0144] Furthermore, when heating the raw material mixture, it is preferable to adjust the addition ratio of Li and P in the raw material mixture so that the desired Li and P content ratio for the glass is achieved, taking into consideration, for example, that Li is an element that does not easily volatilize and P is an element that volatilizes easily.

[0145] However, in the second embodiment, the raw materials are mixed in such a way as to further satisfy the requirements described above in the second embodiment, in order to obtain a raw material mixture.

[0146] From the viewpoint of shortening the holding time during heating to obtain the molten material, it is preferable to reduce the particle size of each raw material. Furthermore, if the particle size of the raw materials is too large, it may affect the homogeneity of the glass, so from this viewpoint as well, it is preferable to have a certain degree of small particle size. However, the manufacturing method according to this embodiment has excellent composition controllability. Therefore, for example, even if raw materials with particle sizes that may reduce homogeneity in conventional manufacturing methods are used, the manufacturing method according to this embodiment can produce more homogeneous glass.

[0147] From the above viewpoint, specifically, the particle size of each raw material is preferably 1 mm or less, more preferably 500 μm or less, even more preferably 250 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less. Smaller particle sizes are preferable, but a practical lower limit is around 0.1 μm, although it may be 1 μm or more, or 5 μm or more. Furthermore, as described above, according to the manufacturing method of this embodiment, homogeneous glass can be easily obtained even when using raw materials with relatively large particle sizes. Taking this into consideration, for example from the viewpoint of suppressing manufacturing costs, the particle size of each raw material may be 10 μm or more, 100 μm or more, or 250 μm or more.

[0148] From these considerations, the particle size of each raw material is preferably 0.1 μm to 1 mm, more preferably 1 to 500 μm, even more preferably 5 to 250 μm, even more preferably 5 to 100 μm, and particularly preferably 5 to 50 μm. Furthermore, from the viewpoint of manufacturing cost, the particle size of each raw material is preferably 10 μm to 1 mm, more preferably 100 μm to 1 mm, and even more preferably 250 to 500 μm.

[0149] In this specification, the particle size of each raw material refers to the average particle diameter (D50) expressed as the median diameter, which is determined from the volume-based particle size distribution chart obtained by measuring the particle size distribution using a Microtrac MT3300EXII laser diffraction particle size distribution analyzer.

[0150] The raw materials can be mixed by methods such as mortar and pestle, media-based mixing such as a planetary ball mill, or media-less mixing such as a pin mill, powder agitator, or airflow mixing. The raw materials may be amorphous by mixing before heating.

[0151] The specific method for heating the raw material mixture to obtain a molten product is not particularly limited, but for example, heating may be carried out under atmospheric pressure conditions. When heating the raw material mixture to melt it is carried out under atmospheric pressure conditions, the compositional difference between the composition of the raw material mixture and the composition of the resulting glass is reduced. In the manufacturing method according to this embodiment, heating to obtain a molten product is carried out, for example, under atmospheric pressure conditions in a controlled atmosphere, and does not need to be done using a sealed tube. However, this does not preclude the use of a sealed tube.

[0152] Here, the difference between a sealed tube and an environment with controlled atmosphere under atmospheric pressure is that in a sealed tube, the pressure inside the container is in a vacuum state, i.e., less than (gauge pressure - 15 kPa), whereas in an environment with controlled atmosphere under atmospheric pressure, the pressure inside the container during heating is within the range of (gauge pressure ± 15 kPa). Gauge pressure means atmospheric pressure and is defined as 101.3 kPa in this specification.

[0153] In other words, the manufacturing method according to this embodiment may be carried out under atmospheric pressure conditions of (gauge pressure ± 15 kPa) for heating to obtain a molten material. The pressure during the above heating may be atmospheric pressure conditions of (gauge pressure ± 15 kPa), (gauge pressure ± 10 kPa), (gauge pressure ± 5 kPa), or (gauge pressure ± 2 kPa).

[0154] The manufacturing method according to this embodiment may be a batch method or a continuous method.

[0155] Examples of heat-resistant containers for holding raw material mixtures include carbon heat-resistant containers, heat-resistant containers containing oxides such as quartz, quartz glass, borosilicate glass, aluminosilicate glass, alumina, zirconia, and mullite, heat-resistant containers containing nitrides such as silicon nitride and boron nitride, and heat-resistant containers containing carbides such as silicon carbide. Furthermore, these heat-resistant containers may be formed in bulk from the above materials, or they may be containers in which layers of carbon, oxides, nitrides, carbides, etc., are formed, such as carbon-coated quartz tubes.

[0156] The heating temperature for obtaining the molten raw material mixture is 400 to 1000°C, and varies depending on the raw materials used and the composition of the raw material mixture, but for example, 600 to 950°C is preferred, 630 to 850°C is more preferred, and 650 to 750°C is even more preferred. Here, from the viewpoint of reaction rate, the heating temperature is 400°C or higher, preferably 600°C or higher, more preferably 630°C or higher, and even more preferably 650°C or higher. Furthermore, from the viewpoint of suppressing compositional shifts due to volatilization of components, the above heating temperature is 1000°C or lower, preferably 950°C or lower, more preferably 850°C or lower, and even more preferably 750°C or lower.

[0157] The heating time varies depending on the scale, but is preferably 10 minutes to 10 hours, more preferably 30 minutes to 9.5 hours, even more preferably 45 minutes to 9 hours, and particularly preferably 1 to 9 hours. From the viewpoint of ensuring the reaction proceeds well, the heating time is preferably 10 minutes or more, more preferably 30 minutes or more, even more preferably 45 minutes or more, and particularly preferably 1 hour or more. Also, from the viewpoint of productivity, the heating time is preferably 10 hours or less, more preferably 9.5 hours or less, and even more preferably 9 hours or less.

[0158] The dew point during heating is preferably -20°C or lower, and although there is no particular lower limit, it is usually around -80°C.

[0159] In step 1, the dissolution of the raw material mixture can be confirmed by the absence of crystal-derived peaks in high-temperature X-ray diffraction measurements. It can also be confirmed by heating the molten material to a predetermined temperature and tilting it to check for fluidity.

[0160] <Step 2> Step S2 in this embodiment is Step 2, in which the molten material obtained in Step 1 is cooled and solidified to obtain glass.

[0161] Cooling and solidification may be carried out under atmospheric pressure conditions of (gauge pressure ± 15 kPa). The pressure used during cooling and solidification may be atmospheric pressure conditions of (gauge pressure ± 15 kPa), (gauge pressure ± 10 kPa), (gauge pressure ± 5 kPa), or (gauge pressure ± 2 kPa).

[0162] In the cooling and solidification process, the cooling rate is preferably ultra-rapid cooling of 100°C / second or more, more preferably 100 to 100,000°C / second, even more preferably 200 to 50,000°C / second, and particularly preferably 300 to 10,000°C / second. From the viewpoint of ease of glass formation, the above cooling rate is preferably 100°C / second or more, more preferably 200°C / second or more, and even more preferably 300°C / second or more. Furthermore, there is no particular upper limit to the cooling rate, but from the viewpoint of equipment capacity, it is preferably 100,000°C / second or less, more preferably 50,000°C / second or less, and even more preferably 10,000°C / second or less.

[0163] Furthermore, by ensuring that the molten material is cooled uniformly and without thermal unevenness during the cooling and solidification process described above, a higher lithium-ion conductivity can be achieved compared to conventional glass. As a result, the lithium-ion conductivity of the crystallized glass obtained by heat-treating this glass can also be increased.

[0164] The ultra-rapid cooling described above can be achieved, for example, by using a rapid cooling twin-roll system.

[0165] The glass obtained above may be used as a sulfide solid electrolyte without undergoing crystallization in step 3. Furthermore, the sulfide solid electrolyte may be used in a sulfide solid electrolyte layer, electrode composite, or lithium-ion secondary battery. Additionally, the glass may be used after being crushed or dried, depending on the application.

[0166] <Step 3> Step S3 in this embodiment is a step 3 in which the glass obtained above is heat-treated to crystallize at least a part of it in order to obtain crystallized glass.

[0167] The temperature in the above heat treatment can be determined by the crystallization temperature of the glass. Specifically, from the viewpoint of effectively promoting crystallization, the temperature in the above heat treatment is preferably (crystallization temperature - 15°C) or higher, may also be (crystallization temperature - 10°C) or higher, may also be (crystallization temperature + 1°C) or higher. Furthermore, from the viewpoint of preventing the precipitation of crystals other than the desired crystalline phase when heated at high temperatures, the crystallization temperature is preferably (crystallization temperature + 20°C) or lower, and more preferably (crystallization temperature + 15°C) or lower.

[0168] The heating time for crystallization is, for example, 1 minute or more, preferably 1 minute to 6 hours, more preferably 1 minute to 3 hours, even more preferably 5 minutes to 2 hours, and even more preferably 10 minutes to 100 minutes. Here, from the viewpoint of quality stability, the above heating time is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 10 minutes or more. Also, from the viewpoint of productivity, the above heating time is preferably 6 hours or less, more preferably 3 hours or less, even more preferably 2 hours or less, and even more preferably 100 minutes or less.

[0169] By adjusting the heating temperature and heating time during crystallization, the proportion of the crystalline phase in the crystallized glass can be adjusted.

[0170] The atmosphere used during heating for crystallization can be a vacuum atmosphere, a nitrogen atmosphere, an argon atmosphere, or a dry air atmosphere. Among these, a nitrogen atmosphere or an argon atmosphere is preferred from the viewpoint of not impairing lithium ion conductivity.

[0171] While a dry air environment is acceptable for the oxygen concentration in the heating atmosphere during crystallization, from a safety standpoint, 5% by volume or less is preferable.

[0172] Furthermore, the dew point during crystallization is preferably -30°C or lower.

[0173] After heating, the crystallized glass according to this embodiment can be obtained by cooling to room temperature at, for example, 1 to 10,000°C / min.

[0174] The crystallized glass obtained above can be suitably used as a sulfide solid electrolyte. Furthermore, the sulfide solid electrolyte may be used in sulfide solid electrolyte layers, electrode composites, and lithium-ion secondary batteries. In addition, the crystallized glass may be used after being crushed, dried, or otherwise processed depending on the application.

[0175] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Examples 1, 3, and 4-7 are examples, and Example 2 is a comparative example.

[0176] Examples of Tests: Examples 1-7 Under a dry nitrogen gas atmosphere, lithium sulfide powder (manufactured by Albemarle, 99.9% purity or Sigma-Aldrich, 99.98% purity) and phosphorus pentasulfide powder (manufactured by Perimeter, 95-100% purity), along with optional lithium bromide powder (manufactured by Konan Inorganic Chemicals, 99.9% purity), lithium iodide powder (manufactured by Tokyo Chemical Industry Co., Ltd., 99.9% purity), sulfur powder (manufactured by Sigma-Aldrich, 99.998% purity), phosphorus pentoxide powder (manufactured by Sigma-Aldrich, 99.99% purity), calcium oxide (manufactured by Sigma-Aldrich, 99.99% purity), and calcium sulfide (manufactured by Kojunsei Kagaku Co., Ltd., 99% purity), were weighed to obtain a raw material mixture by placing them in a sealed container and shaking them.

[0177] The obtained raw material mixture was placed in a carbon container under a nitrogen atmosphere with a dew point of -50°C or lower, and 4% by mass of sulfur powder relative to the total weight of the raw material mixture was added. The container was placed in an electric furnace inside a glove box. It was heated for 1 hour at a pressure of gauge pressure + 1 kPa and the heating temperature listed in Table 1 to obtain a molten material (Step 1). The sulfur powder acted as a sulfur source, and a gas containing sulfur was generated upon heating, resulting in a gas atmosphere containing sulfur.

[0178] Next, the tip of the container was heated and melted, and the molten material was flowed onto twin rolls at an outflow rate that prevented temperature unevenness. The material was then cooled to room temperature at a cooling rate of 500°C / second to obtain glass (Step 2). The pressure at this time was (gauge pressure + 1 kPa), and the cooling rate was adjusted by the outflow rate of the molten material, the roll gap of the twin rolls, and the rotation speed.

[0179] The obtained glass was heat-treated at 190°C for 60 minutes to obtain crystallized glass (Step 3). Powder X-ray diffraction (XRD) measurements confirmed that the crystallized glass contained crystals having at least one of the thiolysicon region II type and LGPS type crystal structures.

[0180] 《Evaluation》 〈Percentage of b〉 The above composition is expressed using the atomic ratio where the sum of P and M is 1, as the compositional formula Li(a+c-m×d-y×e)M ｄ P （１－ｄ） S ｂ X ｃ Y ｅ Given this, we calculated the value of b such that a - 2b - 5d = -5.00. The results are shown in Table 1 under "b that satisfies stoichiometric ratio". Furthermore, we calculated the ratio of the value of b in the initial composition to the above value of b. The results are shown in Table 1 under "ratio of b".

[0181] <Composition Analysis> The glass obtained in the above test example was weighed in a glove box and dissolved in an alkaline aqueous solution, and the composition was analyzed element by element. Specifically, Li, P, S, I, and Ca were analyzed by ICP emission spectroscopy (instrument: Hitachi High-Tech Science Corporation, model PS3520UVDDII). Br was analyzed by ion chromatography (instrument: Thermo Fisher Scientific, model ICS-2100 (column: AS11HC), H ２ O ２ (A small amount of [substance] was added and diluted with ultrapure water for measurement.) O was analyzed by XPS (instrument: QuanteraSXM, ULVAC PHI). The results are shown in Table 2 under the "Glass Composition" section as "Composition Formula".

[0182] <Sulfur Parameters> The compositional formula of the glass obtained in the above test example is expressed as Li(a+c-m×d-y×e)M, where the sum of P and M is 1. ｄ P （１－ｄ） S ｂ X ｃ Y ｅ In this case, the sulfur parameter values ​​represented by a-2b-5d were calculated. The results are shown in Table 2 under "Sulfur Parameter".

[0183] <Lithium Ion Conductivity> The obtained glass and crystallized glass were crushed in a mortar and then passed through a 100 μm sieve to obtain a powder with an average particle size (D50) of approximately 20 μm, which was used as the sample. The above sample was compacted into powder at a pressure of 380 MPa and used as the measurement sample, and measured using an AC impedance measuring device (Bio-Logic Sciences Instruments, potentiostat / galvanostat VSP). The measurement conditions were: measurement frequency: 100 Hz to 1 MHz, measurement voltage: 100 mV, measurement temperature: 25 °C, and lithium ion conductivity was determined from the obtained Nyquist plot. The results are shown in Table 2 under "Ionic Conductivity (mS / cm)". Note that "-" in Table 2 indicates that lithium ion conductivity was not measured.

[0184]

[0185]

[0186] From the above results, the glasses of Examples 1, 3, and 4-7 according to this embodiment were able to achieve high lithium ion conductivity. Furthermore, it was found that crystallized glass obtained by crystallizing the glass according to this embodiment by heat treatment could also achieve high lithium ion conductivity. On the other hand, the glass of Example 2, in which the sulfur parameter value was -5.00 or higher, had low lithium ion conductivity. Crystallized glass obtained by crystallizing this glass by heat treatment also had low lithium ion conductivity.

[0187] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications are possible without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2025-007965, filed on January 20, 2025, which is incorporated herein by reference in its entirety.

Claims

1. The cation component comprises Li, P, and an optional element M, and the anion component comprises S, and an optional element at least one of elements X and Y, wherein element M is at least one element selected from the group consisting of Sn, Sb, Si, Ge, Ga, Al, B, C, Mg, Ca, Sr, and Ba, element X is at least one element selected from the group consisting of F, Cl, Br, and I, and element Y is at least one element selected from the group consisting of O, Se, N, and C, Li(a+c-m×d-y×e)M ｄ P （１－ｄ） S ｂ X ｃ Y ｅ A glass represented by the following compositional formula, where m is the valence of element M, y is the valence of element Y, and a to e in the compositional formula satisfy the following relationships: -5.30 < a - 2b - 5d < -5.00, 1.50 < a < 7.50, c ≥ 0, 0 ≤ d ≤ 4 / 7, and e ≥ 0.

2. The glass according to claim 1, wherein c > 0 is satisfied in the composition formula.

3. The glass according to claim 1, wherein d > 0 in the composition formula.

4. The glass according to claim 1, wherein e > 0 is satisfied in the composition formula.

5. Crystallized glass comprising a crystalline phase derived from the glass described in any one of claims 1 to 4.

6. A sulfide solid electrolyte comprising the glass described in any one of claims 1 to 4.

7. A sulfide solid electrolyte comprising the crystallized glass described in claim 5.

8. An electrode mixture containing a sulfide solid electrolyte as described in claim 7.

9. A solid electrolyte layer comprising the sulfide solid electrolyte according to claim 7.

10. A lithium-ion secondary battery comprising a sulfide solid electrolyte as described in claim 7.

11. A method for producing glass according to any one of claims 1 to 4, comprising: mixing raw materials to obtain a raw material mixture containing Li, P, and S, and as an optional component, at least one element selected from the group consisting of the element M, the element X, and the element Y; heating the raw material mixture at 400 to 1000°C in a gas atmosphere containing S to obtain a molten product; and cooling and solidifying the molten product to obtain the glass.

12. A method for producing glass according to any one of claims 1 to 4, comprising: mixing raw materials to obtain a raw material mixture containing Li, P, and S, and as an optional component, at least one element selected from the group consisting of the element M, the element X, and the element Y; heating the raw material mixture at 400 to 1000°C to obtain a molten product; and cooling and solidifying the molten product to obtain the glass, wherein the raw materials are mixed such that the ratio of the value of b in the raw material mixture exceeds 100% of the value of b in the composition formula such that a - 2b - 5d = -5.00.

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