Glass solid electrolyte powder and method for producing same, electrode mixture, and lithium-ion secondary battery

Abstract

The present invention relates to a glass solid electrolyte powder that has an average particle diameter of 0.1-3 µm and contains Li and P as elements that constitute a cationic component and S as an element that constitutes an anionic component. In the composition, expressed in atom%, 30-42% of Li and 5-16% of P are satisfied, the glass transition point is 110-300°C, and the lithium-ion conductivity at 25°C is 1 mS / cm or greater. The glass solid electrolyte powder is preferably amorphous. The present invention also relates to a method for producing the glass solid electrolyte powder.

Description

Glass solid electrolyte powder and its manufacturing method, electrode composite material, and lithium-ion secondary battery

[0001] This invention relates to glass solid electrolyte powder and a method for producing the same. It also relates to electrode composites and lithium-ion secondary batteries containing the above glass solid electrolyte powder.

[0002] Lithium-ion rechargeable batteries are widely used in portable electronic devices such as mobile phones and laptop computers, as well as in automobiles. Traditionally, lithium-ion rechargeable batteries have used liquid electrolytes, but concerns about leakage and fire necessitated larger cases for safety design. Improvements were also desired regarding short battery life and narrow operating temperature range.

[0003] In contrast, all-solid-state lithium-ion secondary batteries, which use a solid electrolyte as the electrolyte for lithium-ion secondary batteries, are attracting attention because they offer advantages such as improved safety, faster charging and discharging, and smaller case size.

[0004] In all-solid-state lithium secondary batteries, from the standpoint of their battery characteristics, the active material and solid electrolyte must be homogeneously mixed. Furthermore, the solid electrolyte must be present in a thin, uniform layer around the active material.

[0005] One way to achieve the above is to use a solid electrolyte powder with a small particle size. For example, Patent Document 1 discloses a method for producing a sulfide solid electrolyte that can improve the productivity of sulfide solid electrolytes with a small average particle size.

[0006] International Publication No. 2013 / 073035

[0007] The sulfide solid electrolyte used in the method described in Patent Document 1 is described as being able to be synthesized by methods such as those described in Japanese Patent Application No. 2010-189965 (corresponding to Japanese Patent Publication No. 2012-048973). From this, it is considered that the above sulfide solid electrolyte is a crystalline glass ceramic. As described in Patent Document 1, it is possible to pulverize a crystalline solid electrolyte to a fine powder. However, after diligent research by the present inventors, it was found that the fine powder obtained from a crystalline solid electrolyte has significantly lower ionic conductivity compared to a relatively large-particle powder (coarse powder). This is presumed to be because when a crystalline solid electrolyte is made into a fine powder, many crystalline interfaces are formed, resulting in increased interfacial resistance.

[0008] Therefore, the present invention aims to provide a glass solid electrolyte powder and a method for producing the same that can achieve high lithium-ion conductivity when used in electrode composites or lithium-ion secondary batteries. The invention also aims to provide an electrode composite and a lithium-ion secondary battery containing the above glass solid electrolyte powder.

[0009] As a result of diligent research, the inventors have found that a glass solid electrolyte powder of a specific composition, having a specific average particle size and high ionic conductivity even in an amorphous state, can achieve the above objective.

[0010] One aspect of the present invention relates to a glass solid electrolyte powder having an average particle size of 0.1 to 3 μm, containing Li and P as elements constituting the cationic component, containing S as an element constituting the anionic component, having a composition of Li: 30 to 42% and P: 5 to 16% in atomic percent, a glass transition temperature of 110 to 300°C, and a lithium ion conductivity of 1 mS / cm or more at 25°C.

[0011] Another aspect of the present invention relates to an electrode mixture containing the glass solid electrolyte powder described above.

[0012] Another aspect of the present invention relates to a lithium-ion secondary battery containing the glass solid electrolyte powder described above.

[0013] Another aspect of the present invention relates to a method for producing glass solid electrolyte powder, comprising grinding a raw material glass solid electrolyte using a grinding solvent containing one or more ether groups and a solvent that does not contain ether groups, wherein the average particle size of the glass solid electrolyte powder is 0.1 to 3 μm, and the raw material glass solid electrolyte consists of glass that satisfies all of the following conditions (1) to (4): (1) The glass contains Li and P as elements constituting the cationic component, and S as an element constituting the anionic component. (2) The composition of the glass satisfies Li: 30 to 42% and P: 5 to 16% in atomic percent. (3) The glass transition temperature of the glass is 110 to 300°C. (4) The lithium ion conductivity of the glass at 25°C is 2 mS / cm or more.

[0014] According to the present invention, a glass solid electrolyte powder can be obtained that can achieve high lithium-ion conductivity when used in an electrode mixture or a lithium-ion secondary battery.

[0015] Figure 1 is a flow chart showing the method for manufacturing the glass that constitutes the glass solid electrolyte powder according to this embodiment. Figure 2 is a flow chart showing the method for manufacturing the glass solid electrolyte powder according to this embodiment.

[0016] 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.

[0017] To solve the above-mentioned problems, the inventors investigated pulverizing a glass solid electrolyte of a specific composition that has high ionic conductivity even in an amorphous state to a fine powder. Conventionally, it has been difficult to pulverize such glass to a fine powder. However, as a result of the inventors' investigation, it was found that the above glass can be pulverized to a fine powder by using a specific pulverizing solvent.

[0018] 《Glass Solid Electrolyte Powder》 The glass solid electrolyte powder according to this embodiment has an average particle size of 0.1 to 3 μm. Furthermore, the glass solid electrolyte powder contains Li and P as elements constituting the cationic component, and S as an element constituting the anionic component, and its composition satisfies Li: 30 to 42% and P: 5 to 16% in atomic percent. In addition, the glass transition temperature of the glass solid electrolyte powder is 110 to 300°C, and the lithium ion conductivity at 25°C is 1 mS / cm or more.

[0019] The glass solid electrolyte powder according to this embodiment has an average particle size of 0.1 to 3 μm. From the viewpoint of ease of handling the powder, the average particle size is preferably 0.1 μm or more, preferably 0.3 μm or more, and more preferably 0.5 μm or more. Furthermore, from the viewpoint of increasing the electrode packing efficiency in all-solid-state batteries, the average particle size is preferably 3 μm or less, preferably 2.5 μm or less, more preferably less than 2.5 μm, even more preferably 2 μm or less, and particularly preferably 1 μm or less.

[0020] In this specification, the average particle size refers to the average particle size (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.

[0021] The glass solid electrolyte powder according to this embodiment contains Li and P as elements constituting the cationic component, and S as an element constituting the anionic component, and its composition satisfies Li: 30-42% and P: 5-16% in atomic percent.

[0022] When a conventional mechanical milling method is applied to a glass raw material mixture obtained by mixing the raw materials to satisfy the above composition, the resulting solid is an amorphous phase but does not have a glass transition temperature. However, as will be described later, by melting the glass raw material mixture and rapidly cooling it, glass that will be used as the raw material for the glass solid electrolyte powder according to this embodiment can be obtained.

[0023] By producing glass as described above, high homogeneity can be achieved without residues such as residual sulfur or unreacted raw materials, resulting in high water resistance with suppressed hydrogen sulfide generation. Furthermore, unlike the mechanical milling method, it is not necessary to consider the hardness of the raw materials, and various anionic and cationic components can be selected to obtain the desired glass. As a result, high lithium ion conductivity can also be achieved.

[0024] The glass solid electrolyte powder contains Li and P as elements constituting the cation component, but may further contain 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 contain at least one element selected from the group consisting of Sb, Si, and Sn, and more preferably to contain Si. Furthermore, from the viewpoint of ionic conductivity, it is preferable to contain at least one of the elements Al and B.

[0025] This section describes each element that makes up the cationic component. Note that the content of each element in the glass solid electrolyte powder is expressed as atomic percent relative to the total content of all elements in the glass solid electrolyte powder.

[0026] Li is an essential element responsible for ion conduction as a solid electrolyte. The Li content in the glass solid electrolyte powder is 30-42%, preferably 33-41%. From the viewpoint of lithium ion conductivity, the above content is 30% or more, preferably 33% or more, and more preferably 35% or more. From the viewpoint of vitrification, the above content is 42% or less, preferably 41% or less, and more preferably 40% or less.

[0027] 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 solid electrolyte powder is 5 to 16%, preferably 5 to 15%, and more preferably 6 to 14%. From the viewpoint of vitrification, the above content is 5% or more, preferably 6% or more, and more preferably 7% or more. Also, from the viewpoint of lithium ion conductivity, the above content is 16% or less, preferably 15% or less, more preferably 14% or less, and even more preferably 12% or less.

[0028] When glass solid electrolyte powder contains Si as an element constituting the cation component, Si has the effect of increasing the viscosity of the melt and promoting vitrification. The Si content in the glass solid electrolyte powder 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 present 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.

[0029] When glass solid electrolyte powder contains Sn as an element constituting the cation component, Sn has the effect of increasing the viscosity of the melt and promoting vitrification. The Sn content in the glass solid electrolyte powder 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.

[0030] When glass solid electrolyte powder contains Sb as an element constituting the cation component, Sb has the effect of increasing the viscosity of the melt and promoting vitrification. The Sb content in the glass solid electrolyte powder 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.

[0031] When the glass solid electrolyte powder 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 solid electrolyte powder 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 properties, the Ge content is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less.

[0032] When glass solid electrolyte powder contains Ga as an element constituting the cation component, Ga has the effect of promoting improved lithium ion conductivity. The Ga content in the glass solid electrolyte powder 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 properties, the Ga content is preferably 10% or less, more preferably 8% or less, and even more preferably 5% or less.

[0033] When glass solid electrolyte powder contains Al as an element constituting the cation component, Al has the effect of increasing the viscosity of the melt and promoting vitrification. The Al content in the glass solid electrolyte powder 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 Al is 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.

[0034] When glass solid electrolyte powder contains B as an element constituting the cation component, B has the effect of increasing the viscosity of the melt and promoting vitrification. The B content in the glass solid electrolyte powder 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.

[0035] When glass solid electrolyte powder contains carbon (C) as an element constituting the cation component, C has the effect of increasing the glass-forming ability. The C content in the glass solid electrolyte powder 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 C is 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.

[0036] When a glass solid electrolyte powder contains alkaline earth metal elements as elements constituting the cation 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. The content of each alkaline earth metal element in the glass solid electrolyte powder 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 alkaline earth metal elements, the content of each alkaline earth metal element when it is included is preferably 0.1% or more, and more preferably 1% or more. Also, 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. Furthermore, the total content of alkaline earth metal elements in the glass solid electrolyte powder is preferably 0 to 20%, more preferably 0.2 to 18%, and even more preferably 1 to 15%. 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.

[0037] The glass solid electrolyte powder contains S as an element constituting the anionic component, but may further contain at least one element selected from the group consisting of F, Cl, Br, I, O, Se, N, and C. In particular, from the viewpoint of improving ionic conductivity, it is preferable to contain at least one element selected from the group consisting of F, Cl, Br, and I (halogen element (X)), more preferably at least one element selected from the group consisting of Cl, Br, and I, and even more preferably I. Furthermore, from the viewpoint of improving vitrification ability, it is preferable to contain at least one element selected from the group consisting of O, Se, N, and C.

[0038] This section describes each element that makes up the anionic component. Note that the content of each element in the glass solid electrolyte powder is expressed as atomic percent relative to the total content of all elements in the glass solid electrolyte powder.

[0039] S is an element that forms a P-S bond with P and is essential for forming the glass phase. The S content in the glass solid electrolyte powder 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.

[0040] When the glass solid electrolyte powder contains a halogen element (X) as an element constituting the anionic component, X is an element that contributes to high lithium ion conductivity. The total content of X in the glass solid electrolyte powder is preferably 0 to 20%, more preferably 1 to 20%, and may also be 1 to 12% or 2 to 10%. Here, from the viewpoint of suitably obtaining the effect of X, the total content when X is included is preferably 1% or more, more preferably 2% or more, even more preferably 3% or more, and particularly preferably 6% or more. Furthermore, from the viewpoint of preventing the precipitation of lithium halide crystals, the total content of X is preferably 20% or less, more preferably 19% or less, and even more preferably 17% or less. Also, the total content of X may be 12% or less, or 10% or less.

[0041] In particular, it is preferable that the combined content of Br and I accounts for 50% or more of the total content of X, more preferably 70% or more, and it is also possible that it accounts for 100%, i.e., X consists only of Br and I. Furthermore, the content ratio expressed as Cl:Br 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 X from containing only Cl.

[0042] When the glass solid electrolyte powder contains F as an element constituting the anionic component, the F content in the glass solid electrolyte powder is preferably 0.1 to 20%, may also be 0.1 to 10%, or 0.5 to 5%. Here, the F content is preferably 0.1% or more, more preferably 0.5% or more, even more preferably 3% or more, and particularly preferably 6% or more. Furthermore, the F content is preferably 20% or less, more preferably 19% or less, and even more preferably 17% or less. If lithium fluoride crystals are likely to precipitate, the F content may be 10% or less, or even 5% or less.

[0043] When the glass solid electrolyte powder contains Cl as an element constituting the anionic component, the Cl content in the glass solid electrolyte powder is preferably 0.1 to 20%, may also be 0.1 to 10%, or 0.5 to 5%. Here, the Cl content is preferably 0.1% or more, more preferably 0.5% or more, even more preferably 3% or more, and particularly preferably 6% or more. Furthermore, the Cl content is preferably 20% or less, more preferably 19% or less, and even more preferably 17% or less. If lithium chloride crystals are likely to precipitate, the Cl content may be 10% or less, or even 5% or less.

[0044] When the glass solid electrolyte powder contains Br as an element constituting the anionic component, the Br content in the glass solid electrolyte powder is preferably 0.1 to 20%, may also be 0.1 to 10%, or 1 to 8%. Here, the Br content is preferably 0.1% or more, more preferably 1% or more, even more preferably 3% or more, and particularly preferably 6% or more. Furthermore, the Br content is preferably 20% or less, more preferably 19% or less, and even more preferably 17% or less. If lithium bromide crystals are likely to precipitate, the Br content may be 10% or less, or even 8% or less.

[0045] When the glass solid electrolyte powder contains ion (I) as an element constituting the anionic component, I is particularly preferred because it contributes to improving ionic conductivity. The content of I in the glass solid electrolyte powder is preferably 0.1 to 20%, may also be 0.1 to 10%, 1 to 8%, or 2 to 6%. Here, the content of I is preferably 0.1% or more, more preferably 1% or more, even more preferably 2% or more, even more preferably 3% or more, and particularly preferably 6% or more. Furthermore, the content of I is preferably 20% or less, more preferably 19% or less, and even more preferably 17% or less. In cases where lithium iodide crystals are likely to precipitate, or from the viewpoint of improving vitrification, the content of I may be 10% or less, 8% or less, or 6% or less.

[0046] When glass solid electrolyte powder contains oxygen (O) as an element constituting the anionic component, O has the effect of improving ionic conductivity. The O content in the glass solid electrolyte powder 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.

[0047] When glass solid electrolyte powder contains Se as an element constituting the anionic component, Se has the effect of improving ionic conductivity. The Se content in the glass solid electrolyte powder 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. Furthermore, 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.

[0048] When glass solid electrolyte powder contains nitrogen (N) as an element constituting the anionic component, N has the effect of improving ionic conductivity. The N content in the glass solid electrolyte powder 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.

[0049] When glass solid electrolyte powder contains carbon (C) as an element constituting the anionic component, C has the effect of improving ionic conductivity. The C content in glass solid electrolyte powder 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 C is present is preferably 0.1% or more, and more preferably 0.5% or more. Also, 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. Note that C may be an element constituting the cationic component or an anionic component. Whether C is included as one of the above elements can be determined by measuring the glass by XPS (X-ray photoelectron spectroscopy), and C is not present in both states simultaneously.

[0050] The glass solid electrolyte powder may contain other elements in addition to the elements constituting the cationic or anionic components, to the extent that it does not impair the effects of the present invention. Examples of other elements include Na, K, Y, Zr, Cr, Zn, Fe, Co, Ti, Mn, and the like.

[0051] The total content of the above-mentioned other elements in the glass solid electrolyte powder 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.

[0052] The composition of the glass solid electrolyte powder should satisfy Li: 30-42% and P: 5-16% in atomic percent, but it is preferable that it also satisfies one or more of the following: S: 30-60%, X: 1-20%, Si: 1-10%, and Sn: 0.1-10%, preferably two or more, and more preferably three or more. Furthermore, if X: 1-20% is satisfied, it is more preferable that at least one of Br: 0.1-19% and I: 0.1-19% is satisfied. The composition of the glass solid electrolyte powder may also satisfy one or more of the following: S: 30-60%, X: 1-12%, Si: 1-10%, and Sn: 0.1-10%, preferably two or more, and may also satisfy three or more. Furthermore, if X: 1-12% is satisfied, at least one of Br: 0.1-10% and I: 0.1-10% may also be satisfied.

[0053] The method for determining the constituent elements and their respective content (composition ratio) in glass solid electrolyte powder varies depending on the element. For example, P, S, Sn, Sb, Si, Ge, Ga, Al, Mg, Ca, Sr, Ba, and Se can be determined by ICP emission spectrometry, Li and B by atomic absorption spectrometry, X by ion chromatography, and C, O, and N by XPS (X-ray photoelectron spectroscopy).

[0054] The glass transition temperature of the glass solid electrolyte powder is 110 to 300°C, preferably 130 to 300°C, more preferably 140 to 290°C, and particularly preferably 150 to 280°C. By melting a glass raw material mixture and rapidly cooling it, a glass having a glass transition temperature can be obtained. From the viewpoint of improving the stability of the glass solid electrolyte powder, the glass transition temperature is 110°C or higher, preferably 130°C or higher, more preferably 140°C or higher, and particularly preferably 150°C or higher. Furthermore, from the viewpoint of moldability, the glass transition temperature is 300°C or lower, preferably 290°C or lower, and more preferably 280°C or lower. In this specification, the glass transition temperature 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.

[0055] The crystallization temperature of the glass solid electrolyte powder is not particularly limited, but is preferably 130 to 400°C, more preferably 140 to 400°C, and particularly preferably 150 to 370°C. 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 the stability of the glass solid electrolyte powder, the crystallization temperature is preferably 400°C or lower, and more preferably 370°C or lower.

[0056] 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.

[0057] When the glass transition temperature of a glass solid electrolyte powder 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 the stability of the glass solid electrolyte powder, the above difference is preferably 10°C or more, and more preferably 20°C or more. Furthermore, from the viewpoint of productivity, the above difference is preferably 200°C or less, and more preferably 180°C or less.

[0058] The lithium ion conductivity of the glass solid electrolyte powder according to this embodiment at 25°C is 1 mS / cm or more, preferably 1.2 mS / cm or more, more preferably greater than 1.2 mS / cm, even more preferably 2 mS / cm or more, and the higher the value, the better. The lithium ion conductivity of the glass solid electrolyte powder is determined by AC impedance measurement using the powder sample 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 taken as the lithium ion conductivity.

[0059] The lithium-ion conductivity mentioned above can be adjusted by the composition of the glass solid electrolyte powder, reducing thermal unevenness during rapid cooling of the molten glass raw material mixture, and controlling the cooling rate. In particular, the raw material glass solid electrolyte, which is the raw material for the glass solid electrolyte powder, is obtained by melting and rapidly cooling the glass raw material mixture, rather than by the conventional mechanical milling method. This expands the region that can be vitrified, making it easier to include multiple desired anionic and cationic components, and as a result, it becomes possible to adopt a composition that achieves high lithium-ion conductivity.

[0060] H₂ of glass solid electrolyte powder after exposure to air with a dew point of -30°C for 1 hour. ２ The amount of hydrogen sulfide (S) generated is preferably 10 mL / g or less, more preferably 4 mL / g or less, even more preferably 1 mL / g or less, particularly preferably 0.1 mL / g or less, and the less the better. ２ The amount of S generated is an indicator of the water resistance of the glass. Note that the above H ２ The more specific measurement conditions for the amount of sulfur (H) generated are as follows: When 10 mg of the glass solid electrolyte powder sample is exposed to air humidified to a dew point of -30°C for 1 hour, the amount of hydrogen sulfide (H) measured is as follows: ２ S) Monitor the amount generated and the total amount H ２ This is the amount of sulfur produced.

[0061] It is preferable that the glass solid electrolyte powder is amorphous, that is, does not contain a crystalline phase. The amorphous nature of the glass solid electrolyte powder can be confirmed by the absence of diffraction peaks indicating crystals in the XRD pattern obtained by powder X-ray diffraction (XRD). When the glass solid electrolyte powder is amorphous, it is possible to suitably achieve both a small, specific average particle size and excellent lithium-ion conductivity.

[0062] Electrode Material The glass solid electrolyte powder according to this embodiment may be used as an electrode material for the positive electrode layer or the negative electrode layer, as described later. That is, the electrode material according to this embodiment includes the glass solid electrolyte powder. The electrode material according to this embodiment can achieve high lithium ion conductivity.

[0063] <Lithium Ion Secondary Battery> The glass solid electrolyte powder according to the present embodiment may be used for a lithium ion secondary battery. That is, the lithium ion secondary battery according to the present embodiment includes the above glass solid electrolyte powder. The lithium ion secondary battery according to the present embodiment includes a solid electrolyte layer, a positive electrode layer, and a negative electrode layer. The above glass solid electrolyte powder only needs to be contained in one or more of the solid electrolyte layer, the positive electrode layer, and the negative electrode layer, and may be contained in two or more thereof, or may be contained in all of them.

[0064] For the configurations of the solid electrolyte layer, the positive electrode layer, and the negative electrode layer other than the above glass solid electrolyte powder, conventionally known configurations can be employed. Specific examples of each configuration are shown below, but the configurations are not limited to these.

[0065] <Positive Electrode Layer> The positive electrode layer contains at least a positive electrode current collector and a positive electrode mixture. The positive electrode mixture includes a positive electrode active material or a coated positive electrode active material, and a solid electrolyte. Examples of the solid electrolyte include oxide-based solid electrolytes, sulfide-based solid electrolytes, and the like, and the solid electrolyte may be the glass solid electrolyte powder according to the present embodiment. The same applies to solid electrolytes used for the negative electrode layer and the solid electrolyte layer described later.

[0066] The positive electrode current collector only needs to be a conductive plate material, and for example, a thin metal plate (metal foil) such as aluminum or an alloy thereof, or stainless steel can be used. These are preferable because they are excellent in electrolytic solution resistance and oxidation resistance.

[0067] There is no particular limitation on the positive electrode active material as long as it can reversibly progress occlusion and release of lithium ions, desorption and insertion (intercalation) of lithium ions, or doping and dedoping of counter anions of the lithium ions (for example, PF ６ － ), and known positive electrode active materials can be used. Examples of the positive electrode active material include lithium cobaltate (LiCoO ２ ), lithium nickelate (LiNiO ２ ), lithium manganate (LiMnO ２ ), lithium nickel manganate, Li(Ni ｘ Co ｙ Mn ｚ M ａ )O２ A composite metal oxide represented by (x + y + z + a = 1, 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, 0 ≤ a ≤ 1, where M is at least one selected from Al, Mg, Nb, Ti, Cu, Zn, Cr), Li ａ M ｂ (PO ４ ) ｃ Examples include polyanion olivine type cathodes represented by (1 ≤ a ≤ 4, 1 ≤ b ≤ 2, 1 ≤ c ≤ 3, where M is at least one selected from Fe, V, Co, Mn, and Ni).

[0068] The positive electrode layer may further contain, for example, a conductive material. The conductive material can form electron conduction paths within the positive electrode layer. The amount of conductive material may be, for example, 0.1 to 10 parts by mass per 100 parts by mass of positive electrode active material or coated positive electrode active material. The conductive material may contain any component. For example, the conductive material may contain at least one selected from the group consisting of acetylene black (AB), carbon black, vapor-grown carbon fiber (VGCF), carbon nanotubes (CNT), and graphene flakes.

[0069] The positive electrode layer may further contain, for example, a binder. The amount of binder may be, for example, 0.1 to 10 parts by mass per 100 parts by mass of positive electrode active material or coated positive electrode active material. The binder may contain any components. For example, the binder may contain at least one selected from the group consisting of polyvinylidene fluoride (PVdF), vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), styrene-butadiene rubber (SBR), and polytetrafluoroethylene (PTFE).

[0070] <Negative Electrode Layer> The negative electrode layer contains at least a negative electrode current collector and a negative electrode composite material. The negative electrode composite material contains a negative electrode active material or coated negative electrode active material and a solid electrolyte. The solid electrolytes in the positive electrode composite material and the negative electrode composite material may be the same or different.

[0071] The negative electrode current collector can be any conductive plate material; for example, a thin metal sheet (metal foil) such as copper or aluminum can be used. These are preferable because they have excellent resistance to electrolytes and oxidation.

[0072] The negative electrode active material is not particularly limited, and any material capable of inserting and deinserting lithium ions may be used. For example, lithium metal, carbon-based materials, silicon, silicon alloys, tin, etc. can be used. The negative electrode active material can be capable of intercalation, deintercalation, or insertion of lithium ions, or a counteranion of the lithium ion (e.g., PF ６ － The negative electrode active material is not particularly limited as long as the doping and dedoping of ) can be carried out reversibly, and known negative electrode active materials can be used. Examples of the above negative electrode active material include carbon-based materials such as graphite, hard carbon, and soft carbon, metals that can form alloys with lithium such as aluminum, silicon, and tin, amorphous oxides such as silicon oxide and tin oxide, and lithium titanate (Li ４ Ti ５ O １２ Examples include:

[0073] The negative electrode layer may further contain, for example, a conductive material. The amount of conductive material may be, for example, 0.1 to 10 parts by mass per 100 parts by mass of negative electrode active material or coated negative electrode active material. The conductive material may be the same as the conductive material used for the positive electrode.

[0074] The negative electrode layer may further contain, for example, a binder. The amount of binder may be, for example, 0.1 to 10 parts by mass per 100 parts by mass of negative electrode active material or coated negative electrode active material. The same binder as the positive electrode binder described above may be used.

[0075] <Solid Electrolyte Layer> The solid electrolyte layer is interposed between the positive electrode layer and the negative electrode layer. The solid electrolyte layer separates the positive electrode layer from the negative electrode layer. The solid electrolyte layer contains a solid electrolyte. The solid electrolyte may be a glass solid electrolyte powder according to this embodiment. The solid electrolyte layer may further contain a binder. The solid electrolytes between the solid electrolyte layer and the positive electrode composite may be of the same type or different types. The solid electrolytes between the solid electrolyte layer and the negative electrode composite may be of the same type or different types.

[0076] The components of the lithium-ion secondary battery, such as the solid electrolyte layer, positive electrode layer, and negative electrode layer, are housed in a battery casing. While conventionally known materials can be used for the battery casing, specific examples include nickel-plated iron, stainless steel, aluminum or its alloys, nickel, titanium, resin materials, and film materials.

[0077] Lithium-ion secondary batteries come in various shapes, including coin-type, sheet-type (film-type), foldable, wound-type with a closed bottom, and button-type, and can be selected appropriately depending on the application.

[0078] The glass solid electrolyte powder according to this embodiment has an average particle size within a specific range, allowing it to exist thinly and uniformly around the active material, and is made of glass of a specific composition that has high ionic conductivity even in an amorphous state. Therefore, the lithium-ion secondary battery according to this embodiment, which includes the glass solid electrolyte powder according to this embodiment, can achieve high lithium-ion conductivity.

[0079] 《Method for Manufacturing Raw Material Glass Solid Electrolyte》 In the method for manufacturing glass solid electrolyte powder described later, the raw material glass solid electrolyte that will be used as the raw material for the glass solid electrolyte powder consists of glass (hereinafter also referred to as "this glass") that satisfies all of the following conditions (1) to (4). (1) The glass contains Li and P as elements constituting the cationic component, and S as an element constituting the anionic component. (2) The composition of the glass satisfies Li: 30 to 42% and P: 5 to 16% in atomic percent. (3) The glass transition temperature of the glass is 110 to 300°C. (4) The lithium ion conductivity of the glass at 25°C is 2 mS / cm or more.

[0080] As shown in Figure 1, the method for manufacturing this glass includes the following steps 1 and 2 in order as steps S1 and S2. Step S1: Step 1: Heat a glass raw material mixture obtained by mixing Li, P, and S to obtain a molten product. Step S2: Cool and solidify the molten product obtained in step 1 to obtain glass.

[0081] The heating in step 1 and the cooling in step 2 are carried out under atmospheric pressure conditions, and the cooling rate during solidification is 100°C / second or more. During cooling, the molten material is cooled uniformly and without thermal unevenness. This eliminates residues such as residual sulfur and unreacted raw materials, resulting in a homogeneous material with good water resistance. Furthermore, the wide range of vitrification and increased freedom in composition allow for the achievement of high lithium ion conductivity. In this specification, atmospheric pressure conditions mean a pressure range of approximately (gauge pressure ± 15 kPa). Gauge pressure means atmospheric pressure and is defined as 101.3 kPa in this specification.

[0082] In step 1 described above, the raw materials are mixed such that the resulting glass contains Li and P as elements constituting the cation component, and S as an element constituting the anion component, and its composition satisfies the requirements of Li: 30-42% and P: 5-16% in atomic percent.

[0083] Each step is explained below.

[0084] <Step 1> Step S1 in this embodiment is a step 1 in which each raw material is mixed to obtain a glass raw material mixture containing Li, P, and S, and then heated. Specifically, a glass raw material mixture is obtained by mixing a raw material containing Li, a raw material containing P, and a raw material containing S. Furthermore, if it is desired to obtain glass containing X as a constituent element, a raw material containing X is added to the raw material containing Li, a raw material containing P, and a raw material containing S, to obtain a glass raw material mixture containing Li, P, S, and X. Here, element X is at least one element selected from the group consisting of F, Cl, Br, and I.

[0085] 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 ２Examples include lithium compounds such as lithium hydroxide (LiOH) and metallic lithium. One or more Li-containing raw materials may be used. From the viewpoint of obtaining sulfide-based glass, lithium sulfide is preferred as the Li-containing raw material. Furthermore, if the resulting glass contains halogen elements, lithium halide (LiX, where X is a halogen element) is also preferred as the Li-containing raw material. Lithium halides will be discussed later.

[0086] 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 raw material containing element P may be used, or two or more types may be used in combination. 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.

[0087] 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－ｘExamples include S (such as sulfur). One type of raw material containing S may be used, or two or more types may be used in combination. From the viewpoint of preventing the inclusion of elements other than those constituting the target glass, lithium sulfide or phosphorus sulfide are preferred as raw materials containing 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.

[0088] 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. From the viewpoint of reactivity, lithium halides are preferred as raw materials containing element X, LiCl, LiBr, and LiI are more preferred, and LiBr and LiI are even more preferred.

[0089] Depending on the desired glass composition, other raw materials may be added to obtain a glass raw material mixture. For example, if the glass further contains at least one element selected from the group consisting of Sn, Sb, Si, Ge, Ga, Al, B, C, Mg, Ca, Sr, and Ba as elements constituting the cationic component, raw materials containing those elements may be used. These raw materials are not limited to compounds, but may also be elemental metals.

[0090] If the glass contains, in addition to X, at least one element selected from the group consisting of O, Se, N, and C as an element constituting the anionic component, then raw materials containing those elements may also be used. These raw materials are not limited to compounds, but may also be elemental metals.

[0091] If the glass further contains other elements as mentioned above, raw materials containing Na, K, Y, Zr, Cr, Zn, Fe, Co, Ti, Mn, etc., may also be used. These other raw materials can be those that are conventionally known.

[0092] For example, raw materials containing the element Si include Si, SiO ２ SiS ２ Examples include SiS. Among them, from the viewpoint of lithium ion conductivity, SiO ２ This is more preferable. These compounds may be used individually or in combination of two or more.

[0093] Raw materials containing the element Sn include Sn, SnS, and SnS ２ SnO, SnO ２ SnCl ２ These are some examples. In particular, from the viewpoint of lithium-ion conductivity, SnS ２ SnCl ２ Preferably, SnS ２ This is more preferable. These compounds may be used individually or in combination of two or more.

[0094] Examples of raw materials containing the element Sb include Sb, Sb ２ S ３ Sb ２ O ３ Sb ２ O ５ SbCl ３ SbCl ５ These include, in particular, Sb from the standpoint of lithium-ion conductivity and water resistance. ２ S ３ SbCl ３ Sb is preferred. ２ S ３ This is more preferable. These compounds may be used individually or in combination of two or more.

[0095] Raw materials containing the element Ge include Ge and GeO. ２ , GeS, GeS ２ GeCl ２ These are some examples. In particular, from the viewpoint of lithium-ion conductivity, GeS ２ GeCl ２ Preferably, GeS ２ This is more preferable. These compounds may be used individually or in combination of two or more.

[0096] Raw materials containing the element Ga include Ga, Ga ２O ３ , Ga ２ S ３ , GaCl ３ , etc. Among these, from the viewpoint of lithium ion conductivity, Ga ２ S ３ , GaCl ３ is preferable, and Ga ２ S ３ is more preferable. These compounds may be used alone, or two or more kinds thereof may be used in combination.

[0097] Examples of raw materials containing Al element include Al, Al ２ S ３ , Al ２ O ３ , AlCl ３ . Among these, from the viewpoints of lithium ion conductivity and water resistance, Al ２ S ３ , AlCl ３ is preferable, and Al ２ S ３ is more preferable. These compounds may be used alone, or two or more kinds thereof may be used in combination.

[0098] Examples of raw materials containing B element include B, B ２ O ３ , B ２ S ３ , etc. Among these, from the viewpoint of water resistance of glass, B ２ O ３ is more preferable. These compounds may be used alone, or two or more kinds thereof may be used in combination.

[0099] Examples of raw materials containing C element include Li ２ CO ３ , Li ２ C ２ , CaCO ３ , etc. Among these, from the viewpoints of procurement availability and lithium ion conductivity, Li ２ CO ３ is preferable. These compounds may be used alone, or two or more kinds thereof may be used in combination.

[0100] Examples of raw materials containing Mg element include Mg, MgO, MgS, MgBr ２ , MgI２ 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.

[0101] Raw materials containing the element Ca include Ca, CaO, CaS, and CaBr. ２ CaI ２ These are some examples. In particular, from the viewpoint of ease of solubility, CaBr ２ CaI ２ This is preferable. These compounds may be used individually or in combination of two or more.

[0102] 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.

[0103] Raw materials containing the element Ba include Ba, BaO, BaS, and BaBr. ２ These are some examples. Among them, Ba is preferred from the viewpoint of ease of solubility. These compounds may be used individually or in combination of two or more.

[0104] As raw materials containing element O, examples include 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 ５ This is more preferable. These compounds may be used individually or in combination of two or more.

[0105] Raw materials containing the element Se include Se, Li２ 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.

[0106] 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.

[0107] These raw materials are blended appropriately according to the desired composition of the glass. Specifically, to obtain the glass described above, the raw materials are mixed so that they contain Li, P, and S, and satisfy at least the following ratios: Li: 30-42% and P: 5-16%.

[0108] From the viewpoint of shortening the holding time during heating to obtain the molten material and from the viewpoint of glass homogeneity, it is preferable to reduce the particle size of each raw material. However, the method for producing the raw material glass solid electrolyte described herein offers excellent compositional control. Therefore, even if raw materials with particle sizes that may reduce homogeneity in conventional manufacturing methods are used, for example, the method for producing the raw material glass solid electrolyte described herein can produce a more homogeneous glass.

[0109] 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 method for producing raw material glass solid electrolytes described herein, 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.

[0110] From these, 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. In this specification, the particle size of each raw material refers to the average particle diameter (D50) expressed as the median diameter obtained 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.

[0111] 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.

[0112] The specific method for heating a glass raw material mixture to obtain a molten product is not particularly limited, other than performing the heating under atmospheric pressure conditions. In the manufacturing method according to this embodiment, the compositional deviation between the composition of the glass raw material mixture and the composition of the resulting glass is small because the heating for melting the glass raw material mixture is performed under atmospheric pressure conditions. Furthermore, the compositional deviation can be further suppressed by performing the heating under a gas atmosphere containing sulfur elements.

[0113] Here, in an environment with controlled atmosphere under atmospheric pressure conditions, the pressure inside the container during heating is within the range of (gauge pressure ± 15 kPa). That is, in the manufacturing method according to this embodiment, heating to obtain a molten material is carried out under atmospheric pressure conditions of (gauge pressure ± 15 kPa). The pressure during heating may be any atmospheric pressure conditions of (gauge pressure ± 15 kPa), preferably (gauge pressure ± 10 kPa), more preferably (gauge pressure ± 5 kPa), and even more preferably (gauge pressure ± 2 kPa).

[0114] Furthermore, when heating the glass raw material mixture, it is preferable to adjust the addition ratio of Li and P in the glass 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. The manufacturing method according to this embodiment may be either a batch method or a continuous method.

[0115] Examples of heat-resistant containers for glass 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 with layers of carbon, oxides, nitrides, carbides, etc., formed on the surface, such as carbon-coated quartz tubes.

[0116] The heating temperature when obtaining a molten glass raw material mixture varies depending on the raw materials used and the composition of the glass 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 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 preferably 950°C or lower, more preferably 850°C or lower, and even more preferably 750°C or lower.

[0117] 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.

[0118] The atmosphere inside the container during heating is not particularly limited. For example, it may be under a nitrogen atmosphere, an argon atmosphere, or a gas atmosphere containing sulfur. Among these, a gas atmosphere containing sulfur is preferred from the viewpoint of more effectively suppressing compositional deviations.

[0119] When using a gas atmosphere containing sulfur, examples of sulfur sources include sulfur gas, hydrogen sulfide gas, and sulfur dioxide gas, and it is preferable to include sulfur gas from the viewpoint of reactivity with the glass raw material mixture. Alternatively, a gas containing sulfur may be introduced by adding elemental sulfur powder and vaporizing it by heating. Elemental sulfur powder may be added together with the raw materials when mixing them to obtain the glass raw material mixture, or it may be added separately after obtaining the glass raw material mixture. However, when elemental sulfur powder is added together with the raw materials when obtaining the glass raw material mixture, the mass of the elemental sulfur powder is not included in the mass of the obtained glass raw material mixture. In addition to introducing the above-mentioned sulfur gas, hydrogen sulfide gas, and sulfur dioxide gas as gases containing sulfur, a gas containing sulfur may also be introduced by adding elemental sulfur powder.

[0120] For gases containing S element, it is preferable to use the above-mentioned S element source gas as a mixed gas with, for example, an inert gas. The mixing ratio with the inert gas is arbitrary and is not particularly limited as long as the cumulative amount of S element introduced relative to the mass of the glass raw material mixture can be set to a desired value.

[0121] Examples of the above-mentioned inert gases include nitrogen gas, argon gas, and helium gas, and these may be used individually or in mixtures of two or more.

[0122] The oxygen concentration in the atmosphere inside the container during heating is preferably 1000 ppm by volume or less.

[0123] 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.

[0124] In step 1, the melting of the glass 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.

[0125] <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 the glass.

[0126] Cooling and solidification are carried out under atmospheric pressure conditions. Here, atmospheric pressure conditions refer to an atmosphere under a pressure of approximately (gauge pressure ± 15 kPa), as mentioned above. The pressure used for cooling and solidification should be under atmospheric pressure conditions of (gauge pressure ± 15 kPa), preferably (gauge pressure ± 10 kPa), more preferably (gauge pressure ± 5 kPa), and even more preferably (gauge pressure ± 2 kPa).

[0127] The cooling rate in the cooling solidification process is 100°C / second or higher, preferably 100 to 100,000°C / second, more preferably 200 to 50,000°C / second, and even more preferably 300 to 10,000°C / second. Here, we have found that by using ultra-rapid cooling of 100°C / second or higher, which is faster than conventional methods, compositions that would conventionally result in crystal precipitation can be solidified as glass. This significantly increases the degree of freedom in composition, and allows for the selection of compositions that exhibit high lithium-ion conductivity.

[0128] Furthermore, by performing the above cooling and solidification process in a way that ensures the molten material is cooled uniformly and without thermal unevenness, a higher lithium-ion conductivity can be achieved compared to conventional glass. In addition, by performing the above cooling and solidification process under atmospheric pressure, the compositional deviation between the glass raw material mixture and the resulting glass can be minimized.

[0129] The above cooling rate is 100°C / second or higher, but from the viewpoint of ease of glass formation, 200°C / second or higher is preferred, and 300°C / second or higher is more preferred. Furthermore, there is no particular upper limit to the cooling rate, but from the viewpoint of equipment capacity, 100,000°C / second or lower is preferred, 50,000°C / second or lower is more preferred, and 10,000°C / second or lower is even more preferred. Such ultra-rapid cooling can be achieved, for example, by using a rapid cooling twin roll.

[0130] The lithium ion conductivity of the glass obtained by the above method, when compacted at 380 MPa, is 2 mS / cm or higher at 25°C, preferably 3 mS / cm or higher, and higher is preferable. The lithium ion conductivity of this glass is determined by AC impedance measurement using a 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 taken as the lithium ion conductivity. The average particle size of the above compacted material is usually about 100 μm.

[0131] In addition to the above, preferred embodiments of the resulting glass are the same as those described for the glass solid electrolyte powder described above.

[0132] 《Method for Producing Glass Solid Electrolyte Powder》 The method for producing glass solid electrolyte powder according to this embodiment (hereinafter also referred to as "this manufacturing method") includes step S11 of grinding the raw material glass solid electrolyte made of the glass described above using a grinding solvent, as shown in Figure 2. The grinding solvent includes a solvent containing one or more ether groups and a solvent that does not contain ether groups. This yields glass solid electrolyte powder having a predetermined average particle size. The composition and physical properties of the solid electrolyte powder obtained by this manufacturing method are as described above.

[0133] <Raw material glass solid electrolyte> The raw material glass solid electrolyte used in this manufacturing method consists of the aforementioned glass. As for the method of producing the raw material glass solid electrolyte, for example, the glass is dry-ground using a ball mill and passed through a 100-mesh (150 μm opening) sieve.

[0134] The average particle size of the raw glass solid electrolyte is preferably 10 to 150 μm. From the viewpoint of ease of handling the powder, the average particle size is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. Furthermore, from the viewpoint of ease of grinding, the average particle size is preferably 150 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less.

[0135] <Grinding solvent> The grinding solvent used in this manufacturing method includes a solvent containing one or more ether groups and a solvent that does not contain ether groups.

[0136] Examples of solvents containing one or more ether groups include dimethyl ether, diethyl ether, dipropyl ether, dibutyl ether, and anisole. One or more solvents containing one or more ether groups may be used. When using two or more solvents containing one or more ether groups in combination, it is more preferable to use solvents with similar boiling points.

[0137] Examples of solvents that do not contain ether groups include saturated hydrocarbons such as heptane, hexane, and cyclohexane, as well as aromatic compounds such as benzene, toluene, and xylene. One ether-free solvent may be used, or two or more may be used in combination. When using two or more ether-free solvents in combination, it is more preferable to use solvents with similar boiling points.

[0138] The content of solvents containing one or more ether groups in the grinding solvent (or the total content when two or more types are used in combination) is preferably 0.5 to 50% by mass, and more preferably 0.5 to 30% by mass. From the viewpoint of improving the dispersibility of the glass solid electrolyte powder, the above content is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more. Furthermore, from the viewpoint of not damaging the surface of the glass solid electrolyte powder, the above content is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably less than 40% by mass, even more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 15% by mass or less.

[0139] The content of solvents that do not contain ether groups in the grinding solvent (total content when two or more types are used in combination) is preferably 50 to 99.5% by mass, and more preferably 70 to 99.5% by mass. From the viewpoint of improving the stability of the glass solid electrolyte powder obtained by grinding, the above content is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably more than 60% by mass, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 85% by mass or more. Furthermore, from the viewpoint of improving the dispersibility of the glass solid electrolyte powder, the above content is preferably 99.5% by mass or less, more preferably 99% by mass or less, and even more preferably 98% by mass or less.

[0140] The grinding method in this manufacturing method is not particularly limited as long as the above-mentioned grinding solvent is used, and grinding can be performed using a grinding machine that uses media, such as a ball mill, planetary ball mill, or bead mill.

[0141] The grinding time may be, for example, 10 to 120 minutes. The above time is preferably 10 minutes or more, more preferably 15 minutes or more, preferably 120 minutes or less, and more preferably 80 minutes or less.

[0142] For example, when grinding is performed using a planetary ball mill (Fritsch, P7) having a 45 ml pot, the rotational speed during grinding may be, for example, 100 to 500 rpm. The rotational speed is preferably 100 rpm or more, more preferably 150 rpm or more, preferably 500 rpm or less, and more preferably 300 rpm or less.

[0143] As described above, the following configurations are disclosed in this specification: [1] A glass solid electrolyte powder having an average particle size of 0.1 to 3 μm, containing Li and P as elements constituting the cationic component, containing S as an element constituting the anionic component, having a composition of Li: 30 to 42% and P: 5 to 16% in atomic percent, having a glass transition temperature of 110 to 300°C, and a lithium ion conductivity of 1 mS / cm or more at 25°C. [2] The glass solid electrolyte powder according to [1], which is amorphous. [3] An electrode mixture containing the glass solid electrolyte powder according to [1] or [2]. [4] A lithium-ion secondary battery containing the glass solid electrolyte powder according to any one of [1] to [3]. [5] A method for producing glass solid electrolyte powder, comprising grinding a raw material glass solid electrolyte using a grinding solvent containing one or more ether groups and a solvent that does not contain ether groups, wherein the average particle size of the glass solid electrolyte powder is 0.1 to 3 μm, and the raw material glass solid electrolyte consists of glass that satisfies all of the following conditions (1) to (4): (1) The glass contains Li and P as elements constituting the cationic component, and S as an element constituting the anionic component. (2) The composition of the glass satisfies Li: 30 to 42% and P: 5 to 16% in atomic percent. (3) The glass transition temperature of the glass is 110 to 300°C. (4) The lithium ion conductivity of the glass at 25°C is 2 mS / cm or more. [6] The method for producing glass solid electrolyte powder according to [5], wherein the glass solid electrolyte powder is amorphous. [7] The method for producing glass solid electrolyte powder according to [5] or [6], wherein the content of the solvent containing one or more ether groups in the grinding solvent is 0.5 to 30% by mass.

[0144] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. Examples 1 to 3 and Examples 6 to 9 are examples, and Examples 4 to 5 are comparative examples.

[0145] <Test Examples> <Example 1> (Glass Preparation) Under a dry nitrogen gas atmosphere, lithium sulfide powder (manufactured by Albemarle, purity 99.9%) and phosphorus pentasulfide powder (manufactured by Perimeter, purity 95-100%) were weighed out in the composition ratios shown in Table 1, and optionally lithium chloride powder (manufactured by Sigma-Aldrich, purity 99.995%), lithium bromide powder (manufactured by Sigma-Aldrich, purity 99.995%), and lithium iodide powder (manufactured by Tokyo Chemical Industry Co., Ltd., purity 99.9%) were weighed out and mixed in a mortar to obtain a raw material mixture. The obtained raw material mixture was placed in a carbon container under a nitrogen atmosphere with a dew point of -50°C or lower, containing sulfur powder (Sigma-Aldrich, 99.998% purity) as the S element source. The container was then placed in an electric furnace inside a glove box and heated for 1 hour at a pressure of gauge pressure + 1 kPa and a temperature of 750°C to obtain a molten material (Step 1). Next, the tip of the container was heated to melt it, and the molten material was flowed onto twin rolls at an outflow rate that would not cause temperature unevenness. The mixture 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.

[0146] (Preparation of raw material glass solid electrolyte) The glass obtained above was dry-ground using a ball mill, adjusted so that the D50 was 10 to 20 μm, and then passed through a 100-mesh (150 μm opening) sieve to obtain the raw material glass solid electrolyte, which is coarse pulverized glass.

[0147] (Preparation of Glass Solid Electrolyte Powder) A slurry with a solid content of 20% by mass was obtained by mixing the raw material glass solid electrolyte obtained above with a grinding solvent having the composition described in Table 1. In Table 1, blank spaces in the grinding solvent composition column indicate that the corresponding component is not present. 5 g of the slurry and 50 g of 1 mm diameter zirconia balls were placed in a zirconia container, and wet grinding was performed for 90 minutes at a rotation speed of 200 rpm. After that, the balls were separated in a glove box using a stainless steel sieve (mesh opening 100 μm). Thus, the glass solid electrolyte powder of Example 1 was obtained.

[0148] <Examples 2 to 7> Solid electrolyte powders were prepared in the same manner as in Example 1, except that the composition of the grinding solvent was changed to that listed in Table 1.

[0149] <Example 8> A glass solid electrolyte powder was prepared in the same manner as in Example 2, except that the composition of the glass was changed to that listed in Table 1.

[0150] <Example 9> A glass solid electrolyte powder was prepared in the same manner as in Example 3, except that the composition of the glass was changed to that listed in Table 1.

[0151] 《Evaluation》 〈Glass Transition Temperature〉 The glass obtained in the above (glass preparation) was measured using differential scanning calorimetry (DSC) under conditions of 10°C / min. The temperature at the first inflection point of the obtained DSC chart was determined as the glass transition temperature. The glass transition temperature was evaluated based on the following criteria. The results are shown in Table 1. Note that the glass transition temperature obtained in the above manner is considered to be equivalent to the glass transition temperature of the raw glass solid electrolyte and the glass solid electrolyte powder. A: The glass transition temperature was between 110 and 300°C. C: The glass transition temperature was below 110°C or above 300°C.

[0152] <Lithium Ion Conductivity> The raw material glass solid electrolyte (dry-ground glass) was compacted into powder at a pressure of 380 MPa and used as a measurement sample, or the glass solid electrolyte powder (wet-ground raw material glass solid electrolyte) was used as a measurement sample, and both were 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 lithium ion conductivity of the raw material glass solid electrolyte was evaluated based on the following criteria. The results are shown in Table 1. A: Lithium ion conductivity was 2 mS / cm or higher. C: Lithium ion conductivity was less than 2 mS / cm. The lithium ion conductivity of the glass solid electrolyte powder was also evaluated based on the following criteria. The results are shown in Table 1. A: Lithium-ion conductivity was greater than 1.2 mS / cm. B: Lithium-ion conductivity was between 1 and 1.2 mS / cm. C: Lithium-ion conductivity was less than 1 mS / cm.

[0153] <Average Particle Size> The average particle size of the glass solid electrolyte powder was measured using a particle size analyzer with a laser diffraction method (Microtrac MT3300EXII laser diffraction particle size analyzer), and the value at which 50% of the particle size was less than or equal to that value was measured. The average particle size of the glass solid electrolyte powder was evaluated based on the following criteria. The results are shown in Table 1. A: Average particle size was 0.1 to 2.5 μm. B: Average particle size was greater than 2.5 μm and 3 μm or less. C: Average particle size was less than 0.1 μm or greater than 3 μm.

[0154]

[0155] From the results above, the glass solid electrolyte powders of Examples 1 to 3 and Examples 6 to 9, which are glass solid electrolyte powders according to this embodiment, showed high lithium ion conductivity. On the other hand, the glass solid electrolyte powder of Example 4, which was prepared using only dibutyl ether, a solvent containing one or more ether groups, as the grinding solvent, had inferior lithium ion conductivity. Furthermore, the glass solid electrolyte powder of Example 5, which was prepared using only heptane, a solvent that does not contain ether groups, as the grinding solvent, had an average particle size outside the predetermined range, which was undesirable from the viewpoint of handling the powder and filling in electrode composites or lithium-ion secondary batteries.

[0156] 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. 2025-048763, filed on 24 March 2025, which is incorporated herein by reference in its entirety.

Claims

1. A glass solid electrolyte powder having an average particle size of 0.1 to 3 μm, containing Li and P as elements constituting the cation component, and S as an element constituting the anion component, with a composition of Li: 30 to 42% and P: 5 to 16% in atomic percent, a glass transition temperature of 110 to 300°C, and a lithium ion conductivity of 1 mS / cm or more at 25°C.

2. The glass solid electrolyte powder according to claim 1, wherein it is amorphous.

3. An electrode mixture comprising the glass solid electrolyte powder described in claim 1 or 2.

4. A lithium-ion secondary battery comprising the glass solid electrolyte powder according to claim 1 or 2.

5. A method for producing glass solid electrolyte powder, comprising grinding a raw material glass solid electrolyte using a grinding solvent containing one or more ether groups and a solvent that does not contain ether groups, wherein the average particle size of the glass solid electrolyte powder is 0.1 to 3 μm, and the raw material glass solid electrolyte consists of glass that satisfies all of the following conditions (1) to (4): (1) The glass contains Li and P as elements constituting the cationic component, and S as an element constituting the anionic component. (2) The composition of the glass satisfies Li: 30 to 42% and P: 5 to 16% in atomic percent. (3) The glass transition temperature of the glass is 110 to 300°C. (4) The lithium ion conductivity of the glass at 25°C is 2 mS / cm or more.

6. The method for producing a glass solid electrolyte powder according to claim 5, wherein the glass solid electrolyte powder is amorphous.

7. The method for producing glass solid electrolyte powder according to claim 5 or 6, wherein the content of the solvent containing one or more ether groups in the grinding solvent is 0.5 to 30% by mass.

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